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* [WIP] libstdc++: Implement C++26 std::text_encoding [PR113318]
@ 2024-01-12 22:29 Jonathan Wakely
  2024-01-13 12:44 ` [PATCH v2] " Jonathan Wakely
  0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-12 22:29 UTC (permalink / raw)
  To: libstdc++, gcc-patches

Here's a partial patch for PR libstdc++/113318 to implement another
C++26 feature: https://wg21.link/p1885r12

I'm writing the rest of the tests, but thought I would post it now for
comments on the general approach.

The text_encoding class is basically just a pointer to an {ID,name} pair
in the static array. The aliases view is also just the same pointer (or
empty), and the view's iterator moves forwards and backwards in the
array while the array elements have the same ID. The iterator should
never be able to access out-of-bounds, it always points to an element of
the static array (even when not dereferenceable) and always returns
something when dereferenced (even when not dereferenceable). In the
language being proposed for C++26, it erroneously returns "" when a
non-dereferenceable iterator is dereferenced (and abort with assertions
enabled).  Incrementing/decrementing past the last/first element in the
view is idempotent (erroneously). That's the idea anyway ... there might
be bugs in the implementation. My thinking is that since those iterators
refer to a global array that never goes out of scope, there's no reason
they should every produce undefined behaviour or indeterminate values.
They should either have well-defined behaviour, or abort. The overhead
of ensuring those properties is pretty low, so seems worth it.

Comments welcome while I write the rest of the tests (and no doubt find
problems with the code)

-- >8 --

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_CHECK_TEXT_ENCODING): Define.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
	* include/Makefile.am: Add new headers.
	* include/Makefile.in: Regenerate.
	* include/bits/locale_classes.h (locale::encoding): Declare new
	member function.
	* include/bits/unicode.h (__charset_alias_match): New function.
	* include/bits/text_encoding-data.h: New file.
	* include/bits/version.def (text_encoding): Define.
	* include/bits/version.h: Regenerate.
	* include/std/text_encoding: New file.
	* src/c++26/Makefile.am: Add test_encoding.cc.
	* src/c++26/Makefile.in: Regenerate.
	* src/c++26/text_encoding.cc: New file.
	* python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
	printer.
	* scripts/gen_text_encoding_data.py: New file.
	* testsuite/ext/unicode/charset_alias_match.cc: New test.
	* testsuite/std/text_encoding/requirements.cc: New test.
---
 libstdc++-v3/acinclude.m4                     |  28 +
 libstdc++-v3/config.h.in                      |   3 +
 libstdc++-v3/configure                        |  54 ++
 libstdc++-v3/configure.ac                     |   3 +
 libstdc++-v3/include/Makefile.am              |   2 +
 libstdc++-v3/include/Makefile.in              |   2 +
 libstdc++-v3/include/bits/locale_classes.h    |  14 +
 .../include/bits/text_encoding-data.h         | 907 ++++++++++++++++++
 libstdc++-v3/include/bits/unicode.h           | 157 ++-
 libstdc++-v3/include/bits/version.def         |  10 +
 libstdc++-v3/include/bits/version.h           |  13 +-
 libstdc++-v3/include/std/text_encoding        | 688 +++++++++++++
 libstdc++-v3/python/libstdcxx/v6/printers.py  |  17 +
 .../scripts/gen_text_encoding_data.py         |  61 ++
 libstdc++-v3/src/c++26/Makefile.am            |   2 +-
 libstdc++-v3/src/c++26/Makefile.in            |   4 +-
 libstdc++-v3/src/c++26/text_encoding.cc       |  70 ++
 .../ext/unicode/charset_alias_match.cc        |  18 +
 .../std/text_encoding/requirements.cc         |  31 +
 19 files changed, 2079 insertions(+), 5 deletions(-)
 create mode 100644 libstdc++-v3/include/bits/text_encoding-data.h
 create mode 100644 libstdc++-v3/include/std/text_encoding
 create mode 100755 libstdc++-v3/scripts/gen_text_encoding_data.py
 create mode 100644 libstdc++-v3/src/c++26/text_encoding.cc
 create mode 100644 libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/requirements.cc

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index aa2cc4af52b..f9ba7ef744b 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -5821,6 +5821,34 @@ AC_LANG_SAVE
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check whether the dependencies for std::text_encoding are available.
+dnl
+dnl Defines:
+dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
+AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
+  AC_TRY_COMPILE([
+  #include <locale.h>
+  #include <langinfo.h>
+  ],[
+    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
+    const char* enc = nl_langinfo_l(CODESET, loc);
+    freelocale(loc);
+  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
+  AC_MSG_RESULT($ac_nl_langinfo_l)
+  if test "$ac_nl_langinfo_l" = yes; then
+    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
+      [Define if nl_langinfo_l should be used for std::text_encoding.])
+  fi
+
+  AC_LANG_RESTORE
+])
+
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
 m4_include([../config/tls.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index c8b36333019..c68cac4f345 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
 # For __basic_file::native_handle()
 GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
 
+# For std::text_encoding
+GLIBCXX_CHECK_TEXT_ENCODING
+
 # Define documentation rules conditionally.
 
 # See if makeinfo has been installed and is modern enough
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index f9957c9de73..c1204fa5818 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -105,6 +105,7 @@ std_headers = \
 	${std_srcdir}/streambuf \
 	${std_srcdir}/string \
 	${std_srcdir}/system_error \
+	${std_srcdir}/text_encoding \
 	${std_srcdir}/thread \
 	${std_srcdir}/unordered_map \
 	${std_srcdir}/unordered_set \
@@ -160,6 +161,7 @@ bits_freestanding = \
 	${bits_srcdir}/stl_raw_storage_iter.h \
 	${bits_srcdir}/stl_relops.h \
 	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/text_encoding-data.h \
 	${bits_srcdir}/version.h \
 	${bits_srcdir}/string_view.tcc \
 	${bits_srcdir}/unicode.h \
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 621f2a29f50..a2e94217006 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -40,6 +40,10 @@
 #include <string>
 #include <ext/atomicity.h>
 
+#ifdef __glibcxx_text_encoding
+#include <text_encoding>
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string
     name() const;
 
+#ifdef __glibcxx_text_encoding
+# if __CHAR_BIT__ == 8
+    text_encoding
+    encoding() const;
+# else
+    text_encoding
+    encoding() const = delete;
+# endif
+#endif
+
     /**
      *  @brief  Locale equality.
      *
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
new file mode 100644
index 00000000000..5fe339464a0
--- /dev/null
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -0,0 +1,907 @@
+// Generated by gen_text_encoding_data.py, do not edit.
+
+#ifndef _GLIBCXX_GET_ENCODING_DATA
+# error "This is not a public header, do not include it directly"
+#endif
+
+  {    3, "US-ASCII" },
+  {    3, "iso-ir-6" },
+  {    3, "ANSI_X3.4-1968" },
+  {    3, "ANSI_X3.4-1986" },
+  {    3, "ISO_646.irv:1991" },
+  {    3, "ISO646-US" },
+  {    3, "us" },
+  {    3, "IBM367" },
+  {    3, "cp367" },
+  {    3, "csASCII" },
+  {    4, "ISO_8859-1:1987" },
+  {    4, "iso-ir-100" },
+  {    4, "ISO_8859-1" },
+  {    4, "ISO-8859-1" },
+  {    4, "latin1" },
+  {    4, "l1" },
+  {    4, "IBM819" },
+  {    4, "CP819" },
+  {    4, "csISOLatin1" },
+  {    5, "ISO_8859-2:1987" },
+  {    5, "iso-ir-101" },
+  {    5, "ISO_8859-2" },
+  {    5, "ISO-8859-2" },
+  {    5, "latin2" },
+  {    5, "l2" },
+  {    5, "csISOLatin2" },
+  {    6, "ISO_8859-3:1988" },
+  {    6, "iso-ir-109" },
+  {    6, "ISO_8859-3" },
+  {    6, "ISO-8859-3" },
+  {    6, "latin3" },
+  {    6, "l3" },
+  {    6, "csISOLatin3" },
+  {    7, "ISO_8859-4:1988" },
+  {    7, "iso-ir-110" },
+  {    7, "ISO_8859-4" },
+  {    7, "ISO-8859-4" },
+  {    7, "latin4" },
+  {    7, "l4" },
+  {    7, "csISOLatin4" },
+  {    8, "ISO_8859-5:1988" },
+  {    8, "iso-ir-144" },
+  {    8, "ISO_8859-5" },
+  {    8, "ISO-8859-5" },
+  {    8, "cyrillic" },
+  {    8, "csISOLatinCyrillic" },
+  {    9, "ISO_8859-6:1987" },
+  {    9, "iso-ir-127" },
+  {    9, "ISO_8859-6" },
+  {    9, "ISO-8859-6" },
+  {    9, "ECMA-114" },
+  {    9, "ASMO-708" },
+  {    9, "arabic" },
+  {    9, "csISOLatinArabic" },
+  {   10, "ISO_8859-7:1987" },
+  {   10, "iso-ir-126" },
+  {   10, "ISO_8859-7" },
+  {   10, "ISO-8859-7" },
+  {   10, "ELOT_928" },
+  {   10, "ECMA-118" },
+  {   10, "greek" },
+  {   10, "greek8" },
+  {   10, "csISOLatinGreek" },
+  {   11, "ISO_8859-8:1988" },
+  {   11, "iso-ir-138" },
+  {   11, "ISO_8859-8" },
+  {   11, "ISO-8859-8" },
+  {   11, "hebrew" },
+  {   11, "csISOLatinHebrew" },
+  {   12, "ISO_8859-9:1989" },
+  {   12, "iso-ir-148" },
+  {   12, "ISO_8859-9" },
+  {   12, "ISO-8859-9" },
+  {   12, "latin5" },
+  {   12, "l5" },
+  {   12, "csISOLatin5" },
+  {   13, "ISO-8859-10" },
+  {   13, "iso-ir-157" },
+  {   13, "l6" },
+  {   13, "ISO_8859-10:1992" },
+  {   13, "csISOLatin6" },
+  {   13, "latin6" },
+  {   14, "ISO_6937-2-add" },
+  {   14, "iso-ir-142" },
+  {   14, "csISOTextComm" },
+  {   15, "JIS_X0201" },
+  {   15, "X0201" },
+  {   15, "csHalfWidthKatakana" },
+  {   16, "JIS_Encoding" },
+  {   16, "csJISEncoding" },
+  {   17, "Shift_JIS" },
+  {   17, "MS_Kanji" },
+  {   17, "csShiftJIS" },
+  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
+  {   18, "csEUCPkdFmtJapanese" },
+  {   18, "EUC-JP" },
+  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
+  {   19, "csEUCFixWidJapanese" },
+  {   20, "BS_4730" },
+  {   20, "iso-ir-4" },
+  {   20, "ISO646-GB" },
+  {   20, "gb" },
+  {   20, "uk" },
+  {   20, "csISO4UnitedKingdom" },
+  {   21, "SEN_850200_C" },
+  {   21, "iso-ir-11" },
+  {   21, "ISO646-SE2" },
+  {   21, "se2" },
+  {   21, "csISO11SwedishForNames" },
+  {   22, "IT" },
+  {   22, "iso-ir-15" },
+  {   22, "ISO646-IT" },
+  {   22, "csISO15Italian" },
+  {   23, "ES" },
+  {   23, "iso-ir-17" },
+  {   23, "ISO646-ES" },
+  {   23, "csISO17Spanish" },
+  {   24, "DIN_66003" },
+  {   24, "iso-ir-21" },
+  {   24, "de" },
+  {   24, "ISO646-DE" },
+  {   24, "csISO21German" },
+  {   25, "NS_4551-1" },
+  {   25, "iso-ir-60" },
+  {   25, "ISO646-NO" },
+  {   25, "no" },
+  {   25, "csISO60DanishNorwegian" },
+  {   25, "csISO60Norwegian1" },
+  {   26, "NF_Z_62-010" },
+  {   26, "iso-ir-69" },
+  {   26, "ISO646-FR" },
+  {   26, "fr" },
+  {   26, "csISO69French" },
+  {   27, "ISO-10646-UTF-1" },
+  {   27, "csISO10646UTF1" },
+  {   28, "ISO_646.basic:1983" },
+  {   28, "ref" },
+  {   28, "csISO646basic1983" },
+  {   29, "INVARIANT" },
+  {   29, "csINVARIANT" },
+  {   30, "ISO_646.irv:1983" },
+  {   30, "iso-ir-2" },
+  {   30, "irv" },
+  {   30, "csISO2IntlRefVersion" },
+  {   31, "NATS-SEFI" },
+  {   31, "iso-ir-8-1" },
+  {   31, "csNATSSEFI" },
+  {   32, "NATS-SEFI-ADD" },
+  {   32, "iso-ir-8-2" },
+  {   32, "csNATSSEFIADD" },
+  {   33, "NATS-DANO" },
+  {   33, "iso-ir-9-1" },
+  {   33, "csNATSDANO" },
+  {   34, "NATS-DANO-ADD" },
+  {   34, "iso-ir-9-2" },
+  {   34, "csNATSDANOADD" },
+  {   35, "SEN_850200_B" },
+  {   35, "iso-ir-10" },
+  {   35, "FI" },
+  {   35, "ISO646-FI" },
+  {   35, "ISO646-SE" },
+  {   35, "se" },
+  {   35, "csISO10Swedish" },
+  {   36, "KS_C_5601-1987" },
+  {   36, "iso-ir-149" },
+  {   36, "KS_C_5601-1989" },
+  {   36, "KSC_5601" },
+  {   36, "korean" },
+  {   36, "csKSC56011987" },
+  {   37, "ISO-2022-KR" },
+  {   37, "csISO2022KR" },
+  {   38, "EUC-KR" },
+  {   38, "csEUCKR" },
+  {   39, "ISO-2022-JP" },
+  {   39, "csISO2022JP" },
+  {   40, "ISO-2022-JP-2" },
+  {   40, "csISO2022JP2" },
+  {   41, "JIS_C6220-1969-jp" },
+  {   41, "JIS_C6220-1969" },
+  {   41, "iso-ir-13" },
+  {   41, "katakana" },
+  {   41, "x0201-7" },
+  {   41, "csISO13JISC6220jp" },
+  {   42, "JIS_C6220-1969-ro" },
+  {   42, "iso-ir-14" },
+  {   42, "jp" },
+  {   42, "ISO646-JP" },
+  {   42, "csISO14JISC6220ro" },
+  {   43, "PT" },
+  {   43, "iso-ir-16" },
+  {   43, "ISO646-PT" },
+  {   43, "csISO16Portuguese" },
+  {   44, "greek7-old" },
+  {   44, "iso-ir-18" },
+  {   44, "csISO18Greek7Old" },
+  {   45, "latin-greek" },
+  {   45, "iso-ir-19" },
+  {   45, "csISO19LatinGreek" },
+  {   46, "NF_Z_62-010_(1973)" },
+  {   46, "iso-ir-25" },
+  {   46, "ISO646-FR1" },
+  {   46, "csISO25French" },
+  {   47, "Latin-greek-1" },
+  {   47, "iso-ir-27" },
+  {   47, "csISO27LatinGreek1" },
+  {   48, "ISO_5427" },
+  {   48, "iso-ir-37" },
+  {   48, "csISO5427Cyrillic" },
+  {   49, "JIS_C6226-1978" },
+  {   49, "iso-ir-42" },
+  {   49, "csISO42JISC62261978" },
+  {   50, "BS_viewdata" },
+  {   50, "iso-ir-47" },
+  {   50, "csISO47BSViewdata" },
+  {   51, "INIS" },
+  {   51, "iso-ir-49" },
+  {   51, "csISO49INIS" },
+  {   52, "INIS-8" },
+  {   52, "iso-ir-50" },
+  {   52, "csISO50INIS8" },
+  {   53, "INIS-cyrillic" },
+  {   53, "iso-ir-51" },
+  {   53, "csISO51INISCyrillic" },
+  {   54, "ISO_5427:1981" },
+  {   54, "iso-ir-54" },
+  {   54, "ISO5427Cyrillic1981" },
+  {   54, "csISO54271981" },
+  {   55, "ISO_5428:1980" },
+  {   55, "iso-ir-55" },
+  {   55, "csISO5428Greek" },
+  {   56, "GB_1988-80" },
+  {   56, "iso-ir-57" },
+  {   56, "cn" },
+  {   56, "ISO646-CN" },
+  {   56, "csISO57GB1988" },
+  {   57, "GB_2312-80" },
+  {   57, "iso-ir-58" },
+  {   57, "chinese" },
+  {   57, "csISO58GB231280" },
+  {   58, "NS_4551-2" },
+  {   58, "ISO646-NO2" },
+  {   58, "iso-ir-61" },
+  {   58, "no2" },
+  {   58, "csISO61Norwegian2" },
+  {   59, "videotex-suppl" },
+  {   59, "iso-ir-70" },
+  {   59, "csISO70VideotexSupp1" },
+  {   60, "PT2" },
+  {   60, "iso-ir-84" },
+  {   60, "ISO646-PT2" },
+  {   60, "csISO84Portuguese2" },
+  {   61, "ES2" },
+  {   61, "iso-ir-85" },
+  {   61, "ISO646-ES2" },
+  {   61, "csISO85Spanish2" },
+  {   62, "MSZ_7795.3" },
+  {   62, "iso-ir-86" },
+  {   62, "ISO646-HU" },
+  {   62, "hu" },
+  {   62, "csISO86Hungarian" },
+  {   63, "JIS_C6226-1983" },
+  {   63, "iso-ir-87" },
+  {   63, "x0208" },
+  {   63, "JIS_X0208-1983" },
+  {   63, "csISO87JISX0208" },
+  {   64, "greek7" },
+  {   64, "iso-ir-88" },
+  {   64, "csISO88Greek7" },
+  {   65, "ASMO_449" },
+  {   65, "ISO_9036" },
+  {   65, "arabic7" },
+  {   65, "iso-ir-89" },
+  {   65, "csISO89ASMO449" },
+  {   66, "iso-ir-90" },
+  {   66, "csISO90" },
+  {   67, "JIS_C6229-1984-a" },
+  {   67, "iso-ir-91" },
+  {   67, "jp-ocr-a" },
+  {   67, "csISO91JISC62291984a" },
+  {   68, "JIS_C6229-1984-b" },
+  {   68, "iso-ir-92" },
+  {   68, "ISO646-JP-OCR-B" },
+  {   68, "jp-ocr-b" },
+  {   68, "csISO92JISC62991984b" },
+  {   69, "JIS_C6229-1984-b-add" },
+  {   69, "iso-ir-93" },
+  {   69, "jp-ocr-b-add" },
+  {   69, "csISO93JIS62291984badd" },
+  {   70, "JIS_C6229-1984-hand" },
+  {   70, "iso-ir-94" },
+  {   70, "jp-ocr-hand" },
+  {   70, "csISO94JIS62291984hand" },
+  {   71, "JIS_C6229-1984-hand-add" },
+  {   71, "iso-ir-95" },
+  {   71, "jp-ocr-hand-add" },
+  {   71, "csISO95JIS62291984handadd" },
+  {   72, "JIS_C6229-1984-kana" },
+  {   72, "iso-ir-96" },
+  {   72, "csISO96JISC62291984kana" },
+  {   73, "ISO_2033-1983" },
+  {   73, "iso-ir-98" },
+  {   73, "e13b" },
+  {   73, "csISO2033" },
+  {   74, "ANSI_X3.110-1983" },
+  {   74, "iso-ir-99" },
+  {   74, "CSA_T500-1983" },
+  {   74, "NAPLPS" },
+  {   74, "csISO99NAPLPS" },
+  {   75, "T.61-7bit" },
+  {   75, "iso-ir-102" },
+  {   75, "csISO102T617bit" },
+  {   76, "T.61-8bit" },
+  {   76, "T.61" },
+  {   76, "iso-ir-103" },
+  {   76, "csISO103T618bit" },
+  {   77, "ECMA-cyrillic" },
+  {   77, "iso-ir-111" },
+  {   77, "KOI8-E" },
+  {   77, "csISO111ECMACyrillic" },
+  {   78, "CSA_Z243.4-1985-1" },
+  {   78, "iso-ir-121" },
+  {   78, "ISO646-CA" },
+  {   78, "csa7-1" },
+  {   78, "csa71" },
+  {   78, "ca" },
+  {   78, "csISO121Canadian1" },
+  {   79, "CSA_Z243.4-1985-2" },
+  {   79, "iso-ir-122" },
+  {   79, "ISO646-CA2" },
+  {   79, "csa7-2" },
+  {   79, "csa72" },
+  {   79, "csISO122Canadian2" },
+  {   80, "CSA_Z243.4-1985-gr" },
+  {   80, "iso-ir-123" },
+  {   80, "csISO123CSAZ24341985gr" },
+  {   81, "ISO_8859-6-E" },
+  {   81, "csISO88596E" },
+  {   81, "ISO-8859-6-E" },
+  {   82, "ISO_8859-6-I" },
+  {   82, "csISO88596I" },
+  {   82, "ISO-8859-6-I" },
+  {   83, "T.101-G2" },
+  {   83, "iso-ir-128" },
+  {   83, "csISO128T101G2" },
+  {   84, "ISO_8859-8-E" },
+  {   84, "csISO88598E" },
+  {   84, "ISO-8859-8-E" },
+  {   85, "ISO_8859-8-I" },
+  {   85, "csISO88598I" },
+  {   85, "ISO-8859-8-I" },
+  {   86, "CSN_369103" },
+  {   86, "iso-ir-139" },
+  {   86, "csISO139CSN369103" },
+  {   87, "JUS_I.B1.002" },
+  {   87, "iso-ir-141" },
+  {   87, "ISO646-YU" },
+  {   87, "js" },
+  {   87, "yu" },
+  {   87, "csISO141JUSIB1002" },
+  {   88, "IEC_P27-1" },
+  {   88, "iso-ir-143" },
+  {   88, "csISO143IECP271" },
+  {   89, "JUS_I.B1.003-serb" },
+  {   89, "iso-ir-146" },
+  {   89, "serbian" },
+  {   89, "csISO146Serbian" },
+  {   90, "JUS_I.B1.003-mac" },
+  {   90, "macedonian" },
+  {   90, "iso-ir-147" },
+  {   90, "csISO147Macedonian" },
+  {   91, "greek-ccitt" },
+  {   91, "iso-ir-150" },
+  {   91, "csISO150" },
+  {   91, "csISO150GreekCCITT" },
+  {   92, "NC_NC00-10:81" },
+  {   92, "cuba" },
+  {   92, "iso-ir-151" },
+  {   92, "ISO646-CU" },
+  {   92, "csISO151Cuba" },
+  {   93, "ISO_6937-2-25" },
+  {   93, "iso-ir-152" },
+  {   93, "csISO6937Add" },
+  {   94, "GOST_19768-74" },
+  {   94, "ST_SEV_358-88" },
+  {   94, "iso-ir-153" },
+  {   94, "csISO153GOST1976874" },
+  {   95, "ISO_8859-supp" },
+  {   95, "iso-ir-154" },
+  {   95, "latin1-2-5" },
+  {   95, "csISO8859Supp" },
+  {   96, "ISO_10367-box" },
+  {   96, "iso-ir-155" },
+  {   96, "csISO10367Box" },
+  {   97, "latin-lap" },
+  {   97, "lap" },
+  {   97, "iso-ir-158" },
+  {   97, "csISO158Lap" },
+  {   98, "JIS_X0212-1990" },
+  {   98, "x0212" },
+  {   98, "iso-ir-159" },
+  {   98, "csISO159JISX02121990" },
+  {   99, "DS_2089" },
+  {   99, "DS2089" },
+  {   99, "ISO646-DK" },
+  {   99, "dk" },
+  {   99, "csISO646Danish" },
+  {  100, "us-dk" },
+  {  100, "csUSDK" },
+  {  101, "dk-us" },
+  {  101, "csDKUS" },
+  {  102, "KSC5636" },
+  {  102, "ISO646-KR" },
+  {  102, "csKSC5636" },
+  {  103, "UNICODE-1-1-UTF-7" },
+  {  103, "csUnicode11UTF7" },
+  {  104, "ISO-2022-CN" },
+  {  104, "csISO2022CN" },
+  {  105, "ISO-2022-CN-EXT" },
+  {  105, "csISO2022CNEXT" },
+  {  106, "UTF-8" },
+  {  106, "csUTF8" },
+  {  109, "ISO-8859-13" },
+  {  109, "csISO885913" },
+  {  110, "ISO-8859-14" },
+  {  110, "iso-ir-199" },
+  {  110, "ISO_8859-14:1998" },
+  {  110, "ISO_8859-14" },
+  {  110, "latin8" },
+  {  110, "iso-celtic" },
+  {  110, "l8" },
+  {  110, "csISO885914" },
+  {  111, "ISO-8859-15" },
+  {  111, "ISO_8859-15" },
+  {  111, "Latin-9" },
+  {  111, "csISO885915" },
+  {  112, "ISO-8859-16" },
+  {  112, "iso-ir-226" },
+  {  112, "ISO_8859-16:2001" },
+  {  112, "ISO_8859-16" },
+  {  112, "latin10" },
+  {  112, "l10" },
+  {  112, "csISO885916" },
+  {  113, "GBK" },
+  {  113, "CP936" },
+  {  113, "MS936" },
+  {  113, "windows-936" },
+  {  113, "csGBK" },
+  {  114, "GB18030" },
+  {  114, "csGB18030" },
+  {  115, "OSD_EBCDIC_DF04_15" },
+  {  115, "csOSDEBCDICDF0415" },
+  {  116, "OSD_EBCDIC_DF03_IRV" },
+  {  116, "csOSDEBCDICDF03IRV" },
+  {  117, "OSD_EBCDIC_DF04_1" },
+  {  117, "csOSDEBCDICDF041" },
+  {  118, "ISO-11548-1" },
+  {  118, "ISO_11548-1" },
+  {  118, "ISO_TR_11548-1" },
+  {  118, "csISO115481" },
+  {  119, "KZ-1048" },
+  {  119, "STRK1048-2002" },
+  {  119, "RK1048" },
+  {  119, "csKZ1048" },
+  { 1000, "ISO-10646-UCS-2" },
+  { 1000, "csUnicode" },
+  { 1001, "ISO-10646-UCS-4" },
+  { 1001, "csUCS4" },
+  { 1002, "ISO-10646-UCS-Basic" },
+  { 1002, "csUnicodeASCII" },
+  { 1003, "ISO-10646-Unicode-Latin1" },
+  { 1003, "csUnicodeLatin1" },
+  { 1003, "ISO-10646" },
+  { 1004, "ISO-10646-J-1" },
+  { 1004, "csUnicodeJapanese" },
+  { 1005, "ISO-Unicode-IBM-1261" },
+  { 1005, "csUnicodeIBM1261" },
+  { 1006, "ISO-Unicode-IBM-1268" },
+  { 1006, "csUnicodeIBM1268" },
+  { 1007, "ISO-Unicode-IBM-1276" },
+  { 1007, "csUnicodeIBM1276" },
+  { 1008, "ISO-Unicode-IBM-1264" },
+  { 1008, "csUnicodeIBM1264" },
+  { 1009, "ISO-Unicode-IBM-1265" },
+  { 1009, "csUnicodeIBM1265" },
+  { 1010, "UNICODE-1-1" },
+  { 1010, "csUnicode11" },
+  { 1011, "SCSU" },
+  { 1011, "csSCSU" },
+  { 1012, "UTF-7" },
+  { 1012, "csUTF7" },
+  { 1013, "UTF-16BE" },
+  { 1013, "csUTF16BE" },
+  { 1014, "UTF-16LE" },
+  { 1014, "csUTF16LE" },
+  { 1015, "UTF-16" },
+  { 1015, "csUTF16" },
+  { 1016, "CESU-8" },
+  { 1016, "csCESU8" },
+  { 1016, "csCESU-8" },
+  { 1017, "UTF-32" },
+  { 1017, "csUTF32" },
+  { 1018, "UTF-32BE" },
+  { 1018, "csUTF32BE" },
+  { 1019, "UTF-32LE" },
+  { 1019, "csUTF32LE" },
+  { 1020, "BOCU-1" },
+  { 1020, "csBOCU1" },
+  { 1020, "csBOCU-1" },
+  { 1021, "UTF-7-IMAP" },
+  { 1021, "csUTF7IMAP" },
+  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
+  { 2000, "csWindows30Latin1" },
+  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
+  { 2001, "csWindows31Latin1" },
+  { 2002, "ISO-8859-2-Windows-Latin-2" },
+  { 2002, "csWindows31Latin2" },
+  { 2003, "ISO-8859-9-Windows-Latin-5" },
+  { 2003, "csWindows31Latin5" },
+  { 2004, "hp-roman8" },
+  { 2004, "roman8" },
+  { 2004, "r8" },
+  { 2004, "csHPRoman8" },
+  { 2005, "Adobe-Standard-Encoding" },
+  { 2005, "csAdobeStandardEncoding" },
+  { 2006, "Ventura-US" },
+  { 2006, "csVenturaUS" },
+  { 2007, "Ventura-International" },
+  { 2007, "csVenturaInternational" },
+  { 2008, "DEC-MCS" },
+  { 2008, "dec" },
+  { 2008, "csDECMCS" },
+  { 2009, "IBM850" },
+  { 2009, "cp850" },
+  { 2009, "850" },
+  { 2009, "csPC850Multilingual" },
+  { 2010, "IBM852" },
+  { 2010, "cp852" },
+  { 2010, "852" },
+  { 2010, "csPCp852" },
+  { 2011, "IBM437" },
+  { 2011, "cp437" },
+  { 2011, "437" },
+  { 2011, "csPC8CodePage437" },
+  { 2012, "PC8-Danish-Norwegian" },
+  { 2012, "csPC8DanishNorwegian" },
+  { 2013, "IBM862" },
+  { 2013, "cp862" },
+  { 2013, "862" },
+  { 2013, "csPC862LatinHebrew" },
+  { 2014, "PC8-Turkish" },
+  { 2014, "csPC8Turkish" },
+  { 2015, "IBM-Symbols" },
+  { 2015, "csIBMSymbols" },
+  { 2016, "IBM-Thai" },
+  { 2016, "csIBMThai" },
+  { 2017, "HP-Legal" },
+  { 2017, "csHPLegal" },
+  { 2018, "HP-Pi-font" },
+  { 2018, "csHPPiFont" },
+  { 2019, "HP-Math8" },
+  { 2019, "csHPMath8" },
+  { 2020, "Adobe-Symbol-Encoding" },
+  { 2020, "csHPPSMath" },
+  { 2021, "HP-DeskTop" },
+  { 2021, "csHPDesktop" },
+  { 2022, "Ventura-Math" },
+  { 2022, "csVenturaMath" },
+  { 2023, "Microsoft-Publishing" },
+  { 2023, "csMicrosoftPublishing" },
+  { 2024, "Windows-31J" },
+  { 2024, "csWindows31J" },
+  { 2025, "GB2312" },
+  { 2025, "csGB2312" },
+  { 2026, "Big5" },
+  { 2026, "csBig5" },
+  { 2027, "macintosh" },
+  { 2027, "mac" },
+  { 2027, "csMacintosh" },
+  { 2028, "IBM037" },
+  { 2028, "cp037" },
+  { 2028, "ebcdic-cp-us" },
+  { 2028, "ebcdic-cp-ca" },
+  { 2028, "ebcdic-cp-wt" },
+  { 2028, "ebcdic-cp-nl" },
+  { 2028, "csIBM037" },
+  { 2029, "IBM038" },
+  { 2029, "EBCDIC-INT" },
+  { 2029, "cp038" },
+  { 2029, "csIBM038" },
+  { 2030, "IBM273" },
+  { 2030, "CP273" },
+  { 2030, "csIBM273" },
+  { 2031, "IBM274" },
+  { 2031, "EBCDIC-BE" },
+  { 2031, "CP274" },
+  { 2031, "csIBM274" },
+  { 2032, "IBM275" },
+  { 2032, "EBCDIC-BR" },
+  { 2032, "cp275" },
+  { 2032, "csIBM275" },
+  { 2033, "IBM277" },
+  { 2033, "EBCDIC-CP-DK" },
+  { 2033, "EBCDIC-CP-NO" },
+  { 2033, "csIBM277" },
+  { 2034, "IBM278" },
+  { 2034, "CP278" },
+  { 2034, "ebcdic-cp-fi" },
+  { 2034, "ebcdic-cp-se" },
+  { 2034, "csIBM278" },
+  { 2035, "IBM280" },
+  { 2035, "CP280" },
+  { 2035, "ebcdic-cp-it" },
+  { 2035, "csIBM280" },
+  { 2036, "IBM281" },
+  { 2036, "EBCDIC-JP-E" },
+  { 2036, "cp281" },
+  { 2036, "csIBM281" },
+  { 2037, "IBM284" },
+  { 2037, "CP284" },
+  { 2037, "ebcdic-cp-es" },
+  { 2037, "csIBM284" },
+  { 2038, "IBM285" },
+  { 2038, "CP285" },
+  { 2038, "ebcdic-cp-gb" },
+  { 2038, "csIBM285" },
+  { 2039, "IBM290" },
+  { 2039, "cp290" },
+  { 2039, "EBCDIC-JP-kana" },
+  { 2039, "csIBM290" },
+  { 2040, "IBM297" },
+  { 2040, "cp297" },
+  { 2040, "ebcdic-cp-fr" },
+  { 2040, "csIBM297" },
+  { 2041, "IBM420" },
+  { 2041, "cp420" },
+  { 2041, "ebcdic-cp-ar1" },
+  { 2041, "csIBM420" },
+  { 2042, "IBM423" },
+  { 2042, "cp423" },
+  { 2042, "ebcdic-cp-gr" },
+  { 2042, "csIBM423" },
+  { 2043, "IBM424" },
+  { 2043, "cp424" },
+  { 2043, "ebcdic-cp-he" },
+  { 2043, "csIBM424" },
+  { 2044, "IBM500" },
+  { 2044, "CP500" },
+  { 2044, "ebcdic-cp-be" },
+  { 2044, "ebcdic-cp-ch" },
+  { 2044, "csIBM500" },
+  { 2045, "IBM851" },
+  { 2045, "cp851" },
+  { 2045, "851" },
+  { 2045, "csIBM851" },
+  { 2046, "IBM855" },
+  { 2046, "cp855" },
+  { 2046, "855" },
+  { 2046, "csIBM855" },
+  { 2047, "IBM857" },
+  { 2047, "cp857" },
+  { 2047, "857" },
+  { 2047, "csIBM857" },
+  { 2048, "IBM860" },
+  { 2048, "cp860" },
+  { 2048, "860" },
+  { 2048, "csIBM860" },
+  { 2049, "IBM861" },
+  { 2049, "cp861" },
+  { 2049, "861" },
+  { 2049, "cp-is" },
+  { 2049, "csIBM861" },
+  { 2050, "IBM863" },
+  { 2050, "cp863" },
+  { 2050, "863" },
+  { 2050, "csIBM863" },
+  { 2051, "IBM864" },
+  { 2051, "cp864" },
+  { 2051, "csIBM864" },
+  { 2052, "IBM865" },
+  { 2052, "cp865" },
+  { 2052, "865" },
+  { 2052, "csIBM865" },
+  { 2053, "IBM868" },
+  { 2053, "CP868" },
+  { 2053, "cp-ar" },
+  { 2053, "csIBM868" },
+  { 2054, "IBM869" },
+  { 2054, "cp869" },
+  { 2054, "869" },
+  { 2054, "cp-gr" },
+  { 2054, "csIBM869" },
+  { 2055, "IBM870" },
+  { 2055, "CP870" },
+  { 2055, "ebcdic-cp-roece" },
+  { 2055, "ebcdic-cp-yu" },
+  { 2055, "csIBM870" },
+  { 2056, "IBM871" },
+  { 2056, "CP871" },
+  { 2056, "ebcdic-cp-is" },
+  { 2056, "csIBM871" },
+  { 2057, "IBM880" },
+  { 2057, "cp880" },
+  { 2057, "EBCDIC-Cyrillic" },
+  { 2057, "csIBM880" },
+  { 2058, "IBM891" },
+  { 2058, "cp891" },
+  { 2058, "csIBM891" },
+  { 2059, "IBM903" },
+  { 2059, "cp903" },
+  { 2059, "csIBM903" },
+  { 2060, "IBM904" },
+  { 2060, "cp904" },
+  { 2060, "904" },
+  { 2060, "csIBBM904" },
+  { 2061, "IBM905" },
+  { 2061, "CP905" },
+  { 2061, "ebcdic-cp-tr" },
+  { 2061, "csIBM905" },
+  { 2062, "IBM918" },
+  { 2062, "CP918" },
+  { 2062, "ebcdic-cp-ar2" },
+  { 2062, "csIBM918" },
+  { 2063, "IBM1026" },
+  { 2063, "CP1026" },
+  { 2063, "csIBM1026" },
+  { 2064, "EBCDIC-AT-DE" },
+  { 2064, "csIBMEBCDICATDE" },
+  { 2065, "EBCDIC-AT-DE-A" },
+  { 2065, "csEBCDICATDEA" },
+  { 2066, "EBCDIC-CA-FR" },
+  { 2066, "csEBCDICCAFR" },
+  { 2067, "EBCDIC-DK-NO" },
+  { 2067, "csEBCDICDKNO" },
+  { 2068, "EBCDIC-DK-NO-A" },
+  { 2068, "csEBCDICDKNOA" },
+  { 2069, "EBCDIC-FI-SE" },
+  { 2069, "csEBCDICFISE" },
+  { 2070, "EBCDIC-FI-SE-A" },
+  { 2070, "csEBCDICFISEA" },
+  { 2071, "EBCDIC-FR" },
+  { 2071, "csEBCDICFR" },
+  { 2072, "EBCDIC-IT" },
+  { 2072, "csEBCDICIT" },
+  { 2073, "EBCDIC-PT" },
+  { 2073, "csEBCDICPT" },
+  { 2074, "EBCDIC-ES" },
+  { 2074, "csEBCDICES" },
+  { 2075, "EBCDIC-ES-A" },
+  { 2075, "csEBCDICESA" },
+  { 2076, "EBCDIC-ES-S" },
+  { 2076, "csEBCDICESS" },
+  { 2077, "EBCDIC-UK" },
+  { 2077, "csEBCDICUK" },
+  { 2078, "EBCDIC-US" },
+  { 2078, "csEBCDICUS" },
+  { 2079, "UNKNOWN-8BIT" },
+  { 2079, "csUnknown8BiT" },
+  { 2080, "MNEMONIC" },
+  { 2080, "csMnemonic" },
+  { 2081, "MNEM" },
+  { 2081, "csMnem" },
+  { 2082, "VISCII" },
+  { 2082, "csVISCII" },
+  { 2083, "VIQR" },
+  { 2083, "csVIQR" },
+  { 2084, "KOI8-R" },
+  { 2084, "csKOI8R" },
+  { 2085, "HZ-GB-2312" },
+  { 2086, "IBM866" },
+  { 2086, "cp866" },
+  { 2086, "866" },
+  { 2086, "csIBM866" },
+  { 2087, "IBM775" },
+  { 2087, "cp775" },
+  { 2087, "csPC775Baltic" },
+  { 2088, "KOI8-U" },
+  { 2088, "csKOI8U" },
+  { 2089, "IBM00858" },
+  { 2089, "CCSID00858" },
+  { 2089, "CP00858" },
+  { 2089, "PC-Multilingual-850+euro" },
+  { 2089, "csIBM00858" },
+  { 2090, "IBM00924" },
+  { 2090, "CCSID00924" },
+  { 2090, "CP00924" },
+  { 2090, "ebcdic-Latin9--euro" },
+  { 2090, "csIBM00924" },
+  { 2091, "IBM01140" },
+  { 2091, "CCSID01140" },
+  { 2091, "CP01140" },
+  { 2091, "ebcdic-us-37+euro" },
+  { 2091, "csIBM01140" },
+  { 2092, "IBM01141" },
+  { 2092, "CCSID01141" },
+  { 2092, "CP01141" },
+  { 2092, "ebcdic-de-273+euro" },
+  { 2092, "csIBM01141" },
+  { 2093, "IBM01142" },
+  { 2093, "CCSID01142" },
+  { 2093, "CP01142" },
+  { 2093, "ebcdic-dk-277+euro" },
+  { 2093, "ebcdic-no-277+euro" },
+  { 2093, "csIBM01142" },
+  { 2094, "IBM01143" },
+  { 2094, "CCSID01143" },
+  { 2094, "CP01143" },
+  { 2094, "ebcdic-fi-278+euro" },
+  { 2094, "ebcdic-se-278+euro" },
+  { 2094, "csIBM01143" },
+  { 2095, "IBM01144" },
+  { 2095, "CCSID01144" },
+  { 2095, "CP01144" },
+  { 2095, "ebcdic-it-280+euro" },
+  { 2095, "csIBM01144" },
+  { 2096, "IBM01145" },
+  { 2096, "CCSID01145" },
+  { 2096, "CP01145" },
+  { 2096, "ebcdic-es-284+euro" },
+  { 2096, "csIBM01145" },
+  { 2097, "IBM01146" },
+  { 2097, "CCSID01146" },
+  { 2097, "CP01146" },
+  { 2097, "ebcdic-gb-285+euro" },
+  { 2097, "csIBM01146" },
+  { 2098, "IBM01147" },
+  { 2098, "CCSID01147" },
+  { 2098, "CP01147" },
+  { 2098, "ebcdic-fr-297+euro" },
+  { 2098, "csIBM01147" },
+  { 2099, "IBM01148" },
+  { 2099, "CCSID01148" },
+  { 2099, "CP01148" },
+  { 2099, "ebcdic-international-500+euro" },
+  { 2099, "csIBM01148" },
+  { 2100, "IBM01149" },
+  { 2100, "CCSID01149" },
+  { 2100, "CP01149" },
+  { 2100, "ebcdic-is-871+euro" },
+  { 2100, "csIBM01149" },
+  { 2101, "Big5-HKSCS" },
+  { 2101, "csBig5HKSCS" },
+  { 2102, "IBM1047" },
+  { 2102, "IBM-1047" },
+  { 2102, "csIBM1047" },
+  { 2103, "PTCP154" },
+  { 2103, "csPTCP154" },
+  { 2103, "PT154" },
+  { 2103, "CP154" },
+  { 2103, "Cyrillic-Asian" },
+  { 2104, "Amiga-1251" },
+  { 2104, "Ami1251" },
+  { 2104, "Amiga1251" },
+  { 2104, "Ami-1251" },
+  { 2104, "csAmiga1251" },
+  { 2104, "(Aliases" },
+  { 2104, "are" },
+  { 2104, "provided" },
+  { 2104, "for" },
+  { 2104, "historical" },
+  { 2104, "reasons" },
+  { 2104, "and" },
+  { 2104, "should" },
+  { 2104, "not" },
+  { 2104, "be" },
+  { 2104, "used)" },
+  { 2104, "[Malyshev]" },
+  { 2105, "KOI7-switched" },
+  { 2105, "csKOI7switched" },
+  { 2106, "BRF" },
+  { 2106, "csBRF" },
+  { 2107, "TSCII" },
+  { 2107, "csTSCII" },
+  { 2108, "CP51932" },
+  { 2108, "csCP51932" },
+  { 2109, "windows-874" },
+  { 2109, "cswindows874" },
+  { 2250, "windows-1250" },
+  { 2250, "cswindows1250" },
+  { 2251, "windows-1251" },
+  { 2251, "cswindows1251" },
+  { 2252, "windows-1252" },
+  { 2252, "cswindows1252" },
+  { 2253, "windows-1253" },
+  { 2253, "cswindows1253" },
+  { 2254, "windows-1254" },
+  { 2254, "cswindows1254" },
+  { 2255, "windows-1255" },
+  { 2255, "cswindows1255" },
+  { 2256, "windows-1256" },
+  { 2256, "cswindows1256" },
+  { 2257, "windows-1257" },
+  { 2257, "cswindows1257" },
+  { 2258, "windows-1258" },
+  { 2258, "cswindows1258" },
+  { 2259, "TIS-620" },
+  { 2259, "csTIS620" },
+  { 2259, "ISO-8859-11" },
+  { 2260, "CP50220" },
+  { 2260, "csCP50220" },
+
+#undef _GLIBCXX_GET_ENCODING_DATA
diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
index f1b2b359bdf..f531faa04d0 100644
--- a/libstdc++-v3/include/bits/unicode.h
+++ b/libstdc++-v3/include/bits/unicode.h
@@ -986,7 +986,7 @@ inline namespace __v15_1_0
       return __n;
     }
 
-    template<typename _CharT>
+  template<typename _CharT>
     consteval bool
     __literal_encoding_is_unicode()
     {
@@ -1056,6 +1056,161 @@ inline namespace __v15_1_0
   __literal_encoding_is_utf8()
   { return __literal_encoding_is_unicode<char>(); }
 
+  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
+  constexpr bool
+  __charset_alias_match(string_view __a, string_view __b)
+  {
+    auto __map = [](char __c, bool& __num) {
+      switch (__c)
+      {
+	case '0':
+	  return __num ? __c : '\0';
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+	case '8':
+	case '9':
+	  __num = true;
+	  return __c;
+	case 'A':
+	  __c = 'a';
+	  break;
+	case 'B':
+	  __c = 'b';
+	  break;
+	case 'C':
+	  __c = 'c';
+	  break;
+	case 'D':
+	  __c = 'd';
+	  break;
+	case 'E':
+	  __c = 'e';
+	  break;
+	case 'F':
+	  __c = 'f';
+	  break;
+	case 'G':
+	  __c = 'g';
+	  break;
+	case 'H':
+	  __c = 'h';
+	  break;
+	case 'I':
+	  __c = 'i';
+	  break;
+	case 'J':
+	  __c = 'j';
+	  break;
+	case 'K':
+	  __c = 'k';
+	  break;
+	case 'L':
+	  __c = 'l';
+	  break;
+	case 'M':
+	  __c = 'm';
+	  break;
+	case 'N':
+	  __c = 'n';
+	  break;
+	case 'O':
+	  __c = 'o';
+	  break;
+	case 'P':
+	  __c = 'p';
+	  break;
+	case 'Q':
+	  __c = 'q';
+	  break;
+	case 'R':
+	  __c = 'r';
+	  break;
+	case 'S':
+	  __c = 's';
+	  break;
+	case 'T':
+	  __c = 't';
+	  break;
+	case 'U':
+	  __c = 'u';
+	  break;
+	case 'V':
+	  __c = 'v';
+	  break;
+	case 'W':
+	  __c = 'w';
+	  break;
+	case 'X':
+	  __c = 'x';
+	  break;
+	case 'Y':
+	  __c = 'y';
+	  break;
+	case 'Z':
+	  __c = 'z';
+	  break;
+	case 'a':
+	case 'b':
+	case 'c':
+	case 'd':
+	case 'e':
+	case 'f':
+	case 'g':
+	case 'h':
+	case 'i':
+	case 'j':
+	case 'k':
+	case 'l':
+	case 'm':
+	case 'n':
+	case 'o':
+	case 'p':
+	case 'q':
+	case 'r':
+	case 's':
+	case 't':
+	case 'u':
+	case 'v':
+	case 'w':
+	case 'x':
+	case 'y':
+	case 'z':
+	  break;
+	default:
+	  __c = '\0';
+	}
+      __num = false;
+      return __c;
+    };
+
+    auto __ptr_a = __a.begin(), __end_a = __a.end();
+    auto __ptr_b = __b.begin(), __end_b = __b.end();
+    bool __num_a = false, __num_b = false;
+
+    while (true)
+      {
+	char __chr_a, __chr_b;
+	while (__ptr_a != __end_a && (__chr_a = __map(*__ptr_a, __num_a)) == 0)
+	  ++__ptr_a;
+	while (__ptr_b != __end_b && (__chr_b = __map(*__ptr_b, __num_b)) == 0)
+	  ++__ptr_b;
+	if (__ptr_a == __end_a)
+	  return __ptr_b == __end_b;
+	if (__ptr_b == __end_b)
+	  return false;
+	else if (__chr_a != __chr_b)
+	  return false; // Found non-matching characters.
+	++__ptr_a;
+	++__ptr_b;
+      }
+    return true;
+  }
+
 } // namespace __unicode
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index 3ff793cbcaa..3b326be7b22 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1747,6 +1747,16 @@ ftms = {
   };
 };
 
+ftms = {
+  name = text_encoding;
+  values = {
+    v = 202306;
+    cxxmin = 26;
+    hosted = yes;
+    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
+  };
+};
+
 ftms = {
   name = to_string;
   values = {
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 9db0bc6913e..cdea6633e23 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2131,6 +2131,17 @@
 #undef __glibcxx_want_saturation_arithmetic
 
 // from version.def line 1751
+#if !defined(__cpp_lib_text_encoding)
+# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
+#  define __glibcxx_text_encoding 202306L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
+#   define __cpp_lib_text_encoding 202306L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
+#undef __glibcxx_want_text_encoding
+
+// from version.def line 1761
 #if !defined(__cpp_lib_to_string)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
 #  define __glibcxx_to_string 202306L
@@ -2141,7 +2152,7 @@
 #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
 #undef __glibcxx_want_to_string
 
-// from version.def line 1761
+// from version.def line 1771
 #if !defined(__cpp_lib_generator)
 # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
 #  define __glibcxx_generator 202207L
diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
new file mode 100644
index 00000000000..6235a3c133f
--- /dev/null
+++ b/libstdc++-v3/include/std/text_encoding
@@ -0,0 +1,688 @@
+// <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/text_encoding
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TEXT_ENCODING
+#define _GLIBCXX_TEXT_ENCODING
+
+#pragma GCC system_header
+
+#define __glibcxx_want_text_encoding
+#include <bits/version.h>
+
+#ifdef __cpp_lib_text_encoding
+#include <compare>
+#include <string_view>
+#include <bits/functional_hash.h> // hash
+#include <bits/ranges_util.h>     // view_interface
+#include <bits/unicode.h>         // __charset_alias_match
+#include <ext/numeric_traits.h>   // __int_traits
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  /**
+   * @brief An interface for accessing the IANA Character Sets registry.
+   * @ingroup locales
+   * @since C++23
+   */
+  struct text_encoding
+  {
+  private:
+    struct _Rep
+    {
+      using id = __INT_LEAST32_TYPE__;
+      id _M_id;
+      const char* _M_name;
+
+      friend constexpr bool
+      operator<(const _Rep& __r, id __m) noexcept
+      { return __r._M_id < __m; }
+
+      friend constexpr bool
+      operator==(const _Rep& __r, string_view __name) noexcept
+      { return __r._M_name == __name; }
+    };
+
+  public:
+    static constexpr size_t max_name_length = 63;
+
+    enum class id : _Rep::id
+    {
+      other = 1,
+      unknown = 2,
+      ASCII = 3,
+      ISOLatin1 = 4,
+      ISOLatin2 = 5,
+      ISOLatin3 = 6,
+      ISOLatin4 = 7,
+      ISOLatinCyrillic = 8,
+      ISOLatinArabic = 9,
+      ISOLatinGreek = 10,
+      ISOLatinHebrew = 11,
+      ISOLatin5 = 12,
+      ISOLatin6 = 13,
+      ISOTextComm = 14,
+      HalfWidthKatakana = 15,
+      JISEncoding = 16,
+      ShiftJIS = 17,
+      EUCPkdFmtJapanese = 18,
+      EUCFixWidJapanese = 19,
+      ISO4UnitedKingdom = 20,
+      ISO11SwedishForNames = 21,
+      ISO15Italian = 22,
+      ISO17Spanish = 23,
+      ISO21German = 24,
+      ISO60DanishNorwegian = 25,
+      ISO69French = 26,
+      ISO10646UTF1 = 27,
+      ISO646basic1983 = 28,
+      INVARIANT = 29,
+      ISO2IntlRefVersion = 30,
+      NATSSEFI = 31,
+      NATSSEFIADD = 32,
+      ISO10Swedish = 35,
+      KSC56011987 = 36,
+      ISO2022KR = 37,
+      EUCKR = 38,
+      ISO2022JP = 39,
+      ISO2022JP2 = 40,
+      ISO13JISC6220jp = 41,
+      ISO14JISC6220ro = 42,
+      ISO16Portuguese = 43,
+      ISO18Greek7Old = 44,
+      ISO19LatinGreek = 45,
+      ISO25French = 46,
+      ISO27LatinGreek1 = 47,
+      ISO5427Cyrillic = 48,
+      ISO42JISC62261978 = 49,
+      ISO47BSViewdata = 50,
+      ISO49INIS = 51,
+      ISO50INIS8 = 52,
+      ISO51INISCyrillic = 53,
+      ISO54271981 = 54,
+      ISO5428Greek = 55,
+      ISO57GB1988 = 56,
+      ISO58GB231280 = 57,
+      ISO61Norwegian2 = 58,
+      ISO70VideotexSupp1 = 59,
+      ISO84Portuguese2 = 60,
+      ISO85Spanish2 = 61,
+      ISO86Hungarian = 62,
+      ISO87JISX0208 = 63,
+      ISO88Greek7 = 64,
+      ISO89ASMO449 = 65,
+      ISO90 = 66,
+      ISO91JISC62291984a = 67,
+      ISO92JISC62991984b = 68,
+      ISO93JIS62291984badd = 69,
+      ISO94JIS62291984hand = 70,
+      ISO95JIS62291984handadd = 71,
+      ISO96JISC62291984kana = 72,
+      ISO2033 = 73,
+      ISO99NAPLPS = 74,
+      ISO102T617bit = 75,
+      ISO103T618bit = 76,
+      ISO111ECMACyrillic = 77,
+      ISO121Canadian1 = 78,
+      ISO122Canadian2 = 79,
+      ISO123CSAZ24341985gr = 80,
+      ISO88596E = 81,
+      ISO88596I = 82,
+      ISO128T101G2 = 83,
+      ISO88598E = 84,
+      ISO88598I = 85,
+      ISO139CSN369103 = 86,
+      ISO141JUSIB1002 = 87,
+      ISO143IECP271 = 88,
+      ISO146Serbian = 89,
+      ISO147Macedonian = 90,
+      ISO150 = 91,
+      ISO151Cuba = 92,
+      ISO6937Add = 93,
+      ISO153GOST1976874 = 94,
+      ISO8859Supp = 95,
+      ISO10367Box = 96,
+      ISO158Lap = 97,
+      ISO159JISX02121990 = 98,
+      ISO646Danish = 99,
+      USDK = 100,
+      DKUS = 101,
+      KSC5636 = 102,
+      Unicode11UTF7 = 103,
+      ISO2022CN = 104,
+      ISO2022CNEXT = 105,
+      UTF8 = 106,
+      ISO885913 = 109,
+      ISO885914 = 110,
+      ISO885915 = 111,
+      ISO885916 = 112,
+      GBK = 113,
+      GB18030 = 114,
+      OSDEBCDICDF0415 = 115,
+      OSDEBCDICDF03IRV = 116,
+      OSDEBCDICDF041 = 117,
+      ISO115481 = 118,
+      KZ1048 = 119,
+      UCS2 = 1000,
+      UCS4 = 1001,
+      UnicodeASCII = 1002,
+      UnicodeLatin1 = 1003,
+      UnicodeJapanese = 1004,
+      UnicodeIBM1261 = 1005,
+      UnicodeIBM1268 = 1006,
+      UnicodeIBM1276 = 1007,
+      UnicodeIBM1264 = 1008,
+      UnicodeIBM1265 = 1009,
+      Unicode11 = 1010,
+      SCSU = 1011,
+      UTF7 = 1012,
+      UTF16BE = 1013,
+      UTF16LE = 1014,
+      UTF16 = 1015,
+      CESU8 = 1016,
+      UTF32 = 1017,
+      UTF32BE = 1018,
+      UTF32LE = 1019,
+      BOCU1 = 1020,
+      UTF7IMAP = 1021,
+      Windows30Latin1 = 2000,
+      Windows31Latin1 = 2001,
+      Windows31Latin2 = 2002,
+      Windows31Latin5 = 2003,
+      HPRoman8 = 2004,
+      AdobeStandardEncoding = 2005,
+      VenturaUS = 2006,
+      VenturaInternational = 2007,
+      DECMCS = 2008,
+      PC850Multilingual = 2009,
+      PC8DanishNorwegian = 2012,
+      PC862LatinHebrew = 2013,
+      PC8Turkish = 2014,
+      IBMSymbols = 2015,
+      IBMThai = 2016,
+      HPLegal = 2017,
+      HPPiFont = 2018,
+      HPMath8 = 2019,
+      HPPSMath = 2020,
+      HPDesktop = 2021,
+      VenturaMath = 2022,
+      MicrosoftPublishing = 2023,
+      Windows31J = 2024,
+      GB2312 = 2025,
+      Big5 = 2026,
+      Macintosh = 2027,
+      IBM037 = 2028,
+      IBM038 = 2029,
+      IBM273 = 2030,
+      IBM274 = 2031,
+      IBM275 = 2032,
+      IBM277 = 2033,
+      IBM278 = 2034,
+      IBM280 = 2035,
+      IBM281 = 2036,
+      IBM284 = 2037,
+      IBM285 = 2038,
+      IBM290 = 2039,
+      IBM297 = 2040,
+      IBM420 = 2041,
+      IBM423 = 2042,
+      IBM424 = 2043,
+      PC8CodePage437 = 2011,
+      IBM500 = 2044,
+      IBM851 = 2045,
+      PCp852 = 2010,
+      IBM855 = 2046,
+      IBM857 = 2047,
+      IBM860 = 2048,
+      IBM861 = 2049,
+      IBM863 = 2050,
+      IBM864 = 2051,
+      IBM865 = 2052,
+      IBM868 = 2053,
+      IBM869 = 2054,
+      IBM870 = 2055,
+      IBM871 = 2056,
+      IBM880 = 2057,
+      IBM891 = 2058,
+      IBM903 = 2059,
+      IBM904 = 2060,
+      IBM905 = 2061,
+      IBM918 = 2062,
+      IBM1026 = 2063,
+      IBMEBCDICATDE = 2064,
+      EBCDICATDEA = 2065,
+      EBCDICCAFR = 2066,
+      EBCDICDKNO = 2067,
+      EBCDICDKNOA = 2068,
+      EBCDICFISE = 2069,
+      EBCDICFISEA = 2070,
+      EBCDICFR = 2071,
+      EBCDICIT = 2072,
+      EBCDICPT = 2073,
+      EBCDICES = 2074,
+      EBCDICESA = 2075,
+      EBCDICESS = 2076,
+      EBCDICUK = 2077,
+      EBCDICUS = 2078,
+      Unknown8BiT = 2079,
+      Mnemonic = 2080,
+      Mnem = 2081,
+      VISCII = 2082,
+      VIQR = 2083,
+      KOI8R = 2084,
+      HZGB2312 = 2085,
+      IBM866 = 2086,
+      PC775Baltic = 2087,
+      KOI8U = 2088,
+      IBM00858 = 2089,
+      IBM00924 = 2090,
+      IBM01140 = 2091,
+      IBM01141 = 2092,
+      IBM01142 = 2093,
+      IBM01143 = 2094,
+      IBM01144 = 2095,
+      IBM01145 = 2096,
+      IBM01146 = 2097,
+      IBM01147 = 2098,
+      IBM01148 = 2099,
+      IBM01149 = 2100,
+      Big5HKSCS = 2101,
+      IBM1047 = 2102,
+      PTCP154 = 2103,
+      Amiga1251 = 2104,
+      KOI7switched = 2105,
+      BRF = 2106,
+      TSCII = 2107,
+      CP51932 = 2108,
+      windows874 = 2109,
+      windows1250 = 2250,
+      windows1251 = 2251,
+      windows1252 = 2252,
+      windows1253 = 2253,
+      windows1254 = 2254,
+      windows1255 = 2255,
+      windows1256 = 2256,
+      windows1257 = 2257,
+      windows1258 = 2258,
+      TIS620 = 2259,
+      CP50220 = 2260
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+
+    constexpr explicit
+    text_encoding(string_view __enc) noexcept
+    : _M_rep(_S_find_name(__enc))
+    {
+      __enc.copy(_M_name, max_name_length);
+    }
+
+    // @pre i has the value of one of the enumerators of id.
+    constexpr
+    text_encoding(id __i) noexcept
+    : _M_rep(_S_find_id(__i))
+    {
+      if (string_view __name(_M_rep->_M_name); !__name.empty())
+	__name.copy(_M_name, max_name_length);
+    }
+
+    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
+
+    constexpr const char* name() const noexcept { return _M_name; }
+
+    struct aliases_view : ranges::view_interface<aliases_view>
+    {
+    private:
+      class _Iterator;
+      struct _Sentinel { };
+
+    public:
+      constexpr _Iterator begin() const noexcept { return _Iterator(_M_begin); }
+      constexpr _Sentinel end() const noexcept { return _Sentinel{}; }
+
+    private:
+      friend struct text_encoding;
+
+      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
+
+      class _Iterator
+      {
+      public:
+	using value_type = const char*;
+	using reference = const char*;
+	using difference_type = int;
+
+	constexpr _Iterator() = default;
+	constexpr value_type operator*() const;
+	constexpr _Iterator& operator++();
+	constexpr _Iterator& operator--();
+	constexpr _Iterator operator++(int);
+	constexpr _Iterator operator--(int);
+	constexpr value_type operator[](difference_type) const;
+	constexpr _Iterator& operator+=(difference_type);
+	constexpr _Iterator& operator-=(difference_type);
+	constexpr difference_type operator-(const _Iterator&) const;
+	constexpr bool operator==(const _Iterator&) const = default;
+	constexpr bool operator==(_Sentinel) const noexcept;
+	constexpr strong_ordering operator<=>(const _Iterator&) const;
+
+	friend _Iterator
+	operator+(_Iterator __i, difference_type __n)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator+(difference_type __n, _Iterator __i)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator-(_Iterator __i, difference_type __n)
+	{
+	  __i -= __n;
+	  return __i;
+	}
+
+      private:
+	friend class text_encoding;
+
+	constexpr explicit
+	_Iterator(const _Rep* __r) noexcept
+	: _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
+	{ }
+
+	constexpr bool _M_dereferenceable() const noexcept;
+	static constexpr difference_type _S_neg(difference_type) noexcept;
+
+	const _Rep* _M_rep = nullptr;
+	_Rep::id _M_id = 0;
+      };
+
+      const _Rep* _M_begin = nullptr;
+    };
+
+    constexpr aliases_view
+    aliases() const noexcept
+    {
+      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __a,
+	       const text_encoding& __b) noexcept
+    {
+      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
+	return _S_comp(__a._M_name, __b._M_name);
+      else
+	return __a.mib() == __b.mib();
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __encoding, id __i) noexcept
+    { return __encoding.mib() == __i; }
+
+#if __CHAR_BIT__ == 8
+    static consteval text_encoding
+    literal() noexcept
+    {
+      if constexpr (__CHAR_BIT__ != 8)
+	throw;
+
+#ifdef __GNUC_EXECUTION_CHARSET_NAME
+      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
+#elif defined __clang_literal_encoding__
+      return text_encoding(__clang_literal_encoding__);
+#else
+      return text_encoding();
+#endif
+    }
+
+    static text_encoding
+    environment();
+
+    template<id _Id>
+      static bool environment_is()
+      { return environment() == _Id; }
+#else
+    static text_encoding literal() = delete;
+    static text_encoding environment() = delete;
+    template<id> static bool environment_is() = delete;
+#endif
+
+  private:
+    const _Rep* _M_rep = _S_reps + 1; // id::unknown
+    char _M_name[max_name_length + 1] = {0};
+
+    static constexpr bool
+    _S_comp(string_view __a, string_view __b)
+    { return __unicode::__charset_alias_match(__a, __b); }
+
+    static constexpr const _Rep*
+    _S_find_name(string_view __name) noexcept
+    {
+      // The first two array elements (other and unknown) don't have names.
+      // The last element is a sentinel that can never match anything.
+      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
+      for (auto __r = __first; __r != __end; ++__r)
+	if (_S_comp(__r->_M_name, __name))
+	  return __r;
+      return _S_reps; // id::other
+    }
+
+    static constexpr const _Rep*
+    _S_find_id(id __id) noexcept
+    {
+      const auto __i = (_Rep::id)__id;
+      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
+      if (__r->_M_id == __i) [[likely]]
+	return __r;
+      else
+	{
+	  // Preconditions: i has the value of one of the enumerators of id.
+	  __glibcxx_assert(__r->_M_id == __i);
+	  return _S_reps + 1; // id::unknown
+	}
+    }
+
+    static inline constexpr _Rep _S_reps[] = {
+      { 1, "" }, { 2, "" },
+#define _GLIBCXX_GET_ENCODING_DATA
+#include <bits/text_encoding-data.h>
+#ifdef _GLIBCXX_GET_ENCODING_DATA
+# error "Invalid text_encoding data"
+#endif
+      { 9999, nullptr }, // sentinel
+    };
+  };
+
+  template<>
+    struct hash<text_encoding>
+    {
+      size_t
+      operator()(const text_encoding& __enc) const noexcept
+      { return std::hash<text_encoding::id>()(__enc.mib()); }
+    };
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator*() const
+  -> value_type
+  {
+    if (_M_dereferenceable()) [[likely]]
+      return _M_rep->_M_name;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	return "";
+      }
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++()
+  -> _Iterator&
+  {
+    if (_M_dereferenceable()) [[likely]]
+      ++_M_rep;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--()
+  -> _Iterator&
+  {
+    const bool __decrementable = _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
+    if (__decrementable) [[likely]]
+      --_M_rep;
+    else
+      {
+	__glibcxx_assert(__decrementable);
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    ++*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    --*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator[](difference_type __n) const
+  -> value_type
+  { return *(*this + __n); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator+=(difference_type __n)
+  -> _Iterator&
+  {
+    if (_M_rep != nullptr)
+      {
+	if ((__n > 0 && __n < (std::end(_S_reps) - _M_rep))
+	      || (__n < 0 && __n > (_S_reps - _M_rep)))
+	  {
+	    if (_M_rep[__n]._M_id == _M_id)
+	      _M_rep += __n;
+	    else
+	      *this = _Iterator{};
+	  }
+	else if (__n != 0)
+	  *this = _Iterator{};
+      }
+    __glibcxx_assert(_M_rep != nullptr);
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-=(difference_type __n)
+  -> _Iterator&
+  { return operator+=(_S_neg(__n)); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-(const _Iterator& __i) const noexcept
+  -> difference_type
+  {
+    if (_M_id == __i._M_id)
+      return _M_rep - __i._M_rep;
+    __glibcxx_assert(_M_id == __i._M_id);
+    return __gnu_cxx::__int_traits<difference_type>::__max;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::operator==(_Sentinel) const noexcept
+  { return !_M_dereferenceable(); }
+
+  constexpr strong_ordering
+  text_encoding::aliases_view::
+  _Iterator::operator<=>(const _Iterator& __i) const
+  {
+    __glibcxx_assert(_M_id == __i._M_id);
+    return _M_rep <=> __i._M_rep;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::_M_dereferenceable() const noexcept
+  { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::_S_neg(difference_type __n) noexcept
+  -> difference_type
+  {
+    using _Traits = __gnu_cxx::__int_traits<difference_type>;
+    if (__n == _Traits::__min) [[unlikely]]
+      return _Traits::__max;
+    return -__n;
+  }
+
+namespace ranges
+{
+  // Opt-in to borrowed_range concept
+  template<>
+    inline constexpr bool
+    enable_borrowed_range<std::text_encoding::aliases_view> = true;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cpp_lib_text_encoding
+#endif // _GLIBCXX_TEXT_ENCODING
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 032a7aa58a2..03f57f62237 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
         typename = strip_versioned_namespace(self._typename)
         return "{}<{}, {}>".format(typename, value_type, value)
 
+class StdTextEncodingPrinter(printer_base):
+    """Print a std::text_encoding."""
+
+    def __init__(self, typename, val):
+        self._val = val
+        self._typename = typename
+
+    def to_string(self):
+        rep = self._val.dereference()
+        if rep['_M_id'] == 1:
+            return self._val['_M_name']
+        if rep['_M_id'] == 2:
+            return 'unknown'
+        return rep['_M_name']
+
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
 class RxPrinter(object):
@@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
 
     libstdcxx_printer.add_version('std::', 'integral_constant',
                                   StdIntegralConstantPrinter)
+    libstdcxx_printer.add_version('std::', 'text_encoding',
+                                  StdTextEncodingPrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
new file mode 100755
index 00000000000..55000c67256
--- /dev/null
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+#
+# Script to generate tables for libstdc++ std::text_encoding.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+#
+# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
+# the latest:
+# https://www.iana.org/assignments/character-sets/character-sets-1.csv
+# Then run this script and save the output to
+# include/bits/text_encoding-data.h
+
+import sys
+import csv
+
+if len(sys.argv) != 2:
+    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
+    sys.exit(1)
+
+print("// Generated by gen_text_encoding_data.py, do not edit.\n")
+print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
+print('# error "This is not a public header, do not include it directly"')
+print("#endif\n")
+
+
+charsets = {}
+with open(sys.argv[1], newline='') as f:
+    reader = csv.reader(f)
+    next(reader) # skip header row
+    for row in reader:
+        mib = int(row[2])
+        if mib in charsets:
+            raise ValueError("Multiple rows for mibEnum={}".format(mib))
+        name = row[1]
+        aliases = row[5].split()
+        # Ensure primary name comes first
+        if name in aliases:
+            aliases.remove(name)
+        charsets[mib] = [name] + aliases
+
+for mib in sorted(charsets.keys()):
+    for name in charsets[mib]:
+        print('  {{ {:4}, "{}" }},'.format(mib, name))
+
+# <text_encoding> gives an error if this macro is left defined.
+# Do this last, so that the generated output is not usable unless we reach here.
+print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
index 8e9ec78fe0d..201999a3577 100644
--- a/libstdc++-v3/src/c++26/Makefile.am
+++ b/libstdc++-v3/src/c++26/Makefile.am
@@ -35,7 +35,7 @@ else
 inst_sources =
 endif
 
-sources = debugging.cc
+sources = debugging.cc text_encoding.cc
 
 vpath % $(top_srcdir)/src/c++26
 
diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
new file mode 100644
index 00000000000..56e5851030e
--- /dev/null
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -0,0 +1,70 @@
+// Definitions for <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <text_encoding>
+#include <locale>
+
+#ifdef _GLIBCXX_USE_NL_LANGINFO_L
+#include <locale.h>
+#include <langinfo.h>
+
+#if __CHAR_BIT__ == 8
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+std::text_encoding
+__locale_encoding(const char* name)
+{
+  text_encoding enc;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view s(codeset);
+	  if (s.size() < std::text_encoding::max_name_length)
+	    enc = std::text_encoding(s);
+	}
+      ::freelocale(loc);
+    }
+  return enc;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+std::text_encoding
+std::text_encoding::environment()
+{
+  return std::__locale_encoding("");
+}
+
+std::text_encoding
+std::locale::encoding() const
+{
+  return std::__locale_encoding(name().c_str());
+}
+#endif // CHAR_BIT == 8
+
+#endif // _GLIBCXX_USE_NL_LANGINFO_L
diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
new file mode 100644
index 00000000000..f6272ae998b
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+#include <format>
+
+using std::__unicode::__charset_alias_match;
+static_assert( __charset_alias_match("UTF-8", "utf8") == true );
+static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
+static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
+static_assert( __charset_alias_match("UTF-8", "ut8") == false );
+
+static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
+
+static_assert( __charset_alias_match("", "") == true );
+static_assert( __charset_alias_match("", ".") == true );
+static_assert( __charset_alias_match("--", "...") == true );
+static_assert( __charset_alias_match("--a", "a...") == true );
+static_assert( __charset_alias_match("--a010", "a..10.") == true );
+static_assert( __charset_alias_match("--a010", "a..1.0") == false );
+static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
new file mode 100644
index 00000000000..d62d93dcda4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <text_encoding>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <text_encoding>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
+#endif
+
+#undef __cpp_lib_expected
+#include <version>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <version>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <version>"
+#endif
+
+#include <concepts>
+#include <ranges>
+static_assert( std::is_trivially_copyable_v<std::text_encoding> );
+
+using aliases_view = std::text_encoding::aliases_view;
+static_assert( std::copyable<aliases_view> );
+static_assert( std::ranges::view<aliases_view> );
+static_assert( std::ranges::random_access_range<aliases_view> );
+static_assert( std::ranges::borrowed_range<aliases_view> );
+static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
+			    const char*> );
+static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
+			    const char*> );
-- 
2.43.0


^ permalink raw reply	[flat|nested] 9+ messages in thread
* [PATCH v2] libstdc++: Implement C++26 std::text_encoding [PR113318]
  2024-01-12 22:29 [WIP] libstdc++: Implement C++26 std::text_encoding [PR113318] Jonathan Wakely
@ 2024-01-13 12:44 ` Jonathan Wakely
  2024-01-15 20:45   ` [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] Jonathan Wakely
  0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-13 12:44 UTC (permalink / raw)
  To: libstdc++, gcc-patches

Patch v2, with more tests. This fixes a bug in lookup by name where if
an alias was matched then the aliases() view wouldn't contain the
primary name or other aliases earlier in the table.

It also optimizes text_encoding::environment_is<I> so it constructs an
encoding by ID and then only matches the environment's encoding against
that object's aliases, not every string in the table.

There's also a fast path for text_encoding("UTF-8") so we don't search
the table for that case.

More tests still needed...

-- >8 --

libstdc++-v3/ChangeLog:

	PR libstdc++/113318
	* acinclude.m4 (GLIBCXX_CHECK_TEXT_ENCODING): Define.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
	* include/Makefile.am: Add new headers.
	* include/Makefile.in: Regenerate.
	* include/bits/locale_classes.h (locale::encoding): Declare new
	member function.
	* include/bits/unicode.h (__charset_alias_match): New function.
	* include/bits/text_encoding-data.h: New file.
	* include/bits/version.def (text_encoding): Define.
	* include/bits/version.h: Regenerate.
	* include/std/text_encoding: New file.
	* src/c++26/Makefile.am: Add test_encoding.cc.
	* src/c++26/Makefile.in: Regenerate.
	* src/c++26/text_encoding.cc: New file.
	* python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
	printer.
	* scripts/gen_text_encoding_data.py: New file.
	* testsuite/ext/unicode/charset_alias_match.cc: New test.
	* testsuite/std/text_encoding/cons.cc: New test.
	* testsuite/std/text_encoding/requirements.cc: New test.
---
 libstdc++-v3/acinclude.m4                     |  28 +
 libstdc++-v3/config.h.in                      |   3 +
 libstdc++-v3/configure                        |  54 ++
 libstdc++-v3/configure.ac                     |   3 +
 libstdc++-v3/include/Makefile.am              |   2 +
 libstdc++-v3/include/Makefile.in              |   2 +
 libstdc++-v3/include/bits/locale_classes.h    |  14 +
 .../include/bits/text_encoding-data.h         | 902 ++++++++++++++++++
 libstdc++-v3/include/bits/unicode.h           | 157 ++-
 libstdc++-v3/include/bits/version.def         |  10 +
 libstdc++-v3/include/bits/version.h           |  13 +-
 libstdc++-v3/include/std/text_encoding        | 704 ++++++++++++++
 libstdc++-v3/python/libstdcxx/v6/printers.py  |  17 +
 .../scripts/gen_text_encoding_data.py         |  70 ++
 libstdc++-v3/src/c++26/Makefile.am            |   2 +-
 libstdc++-v3/src/c++26/Makefile.in            |   4 +-
 libstdc++-v3/src/c++26/text_encoding.cc       |  91 ++
 .../ext/unicode/charset_alias_match.cc        |  18 +
 .../testsuite/std/text_encoding/cons.cc       | 106 ++
 .../std/text_encoding/requirements.cc         |  31 +
 20 files changed, 2226 insertions(+), 5 deletions(-)
 create mode 100644 libstdc++-v3/include/bits/text_encoding-data.h
 create mode 100644 libstdc++-v3/include/std/text_encoding
 create mode 100755 libstdc++-v3/scripts/gen_text_encoding_data.py
 create mode 100644 libstdc++-v3/src/c++26/text_encoding.cc
 create mode 100644 libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/cons.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/requirements.cc

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index aa2cc4af52b..f9ba7ef744b 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -5821,6 +5821,34 @@ AC_LANG_SAVE
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check whether the dependencies for std::text_encoding are available.
+dnl
+dnl Defines:
+dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
+AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
+  AC_TRY_COMPILE([
+  #include <locale.h>
+  #include <langinfo.h>
+  ],[
+    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
+    const char* enc = nl_langinfo_l(CODESET, loc);
+    freelocale(loc);
+  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
+  AC_MSG_RESULT($ac_nl_langinfo_l)
+  if test "$ac_nl_langinfo_l" = yes; then
+    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
+      [Define if nl_langinfo_l should be used for std::text_encoding.])
+  fi
+
+  AC_LANG_RESTORE
+])
+
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
 m4_include([../config/tls.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index c8b36333019..c68cac4f345 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
 # For __basic_file::native_handle()
 GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
 
+# For std::text_encoding
+GLIBCXX_CHECK_TEXT_ENCODING
+
 # Define documentation rules conditionally.
 
 # See if makeinfo has been installed and is modern enough
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index f9957c9de73..c1204fa5818 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -105,6 +105,7 @@ std_headers = \
 	${std_srcdir}/streambuf \
 	${std_srcdir}/string \
 	${std_srcdir}/system_error \
+	${std_srcdir}/text_encoding \
 	${std_srcdir}/thread \
 	${std_srcdir}/unordered_map \
 	${std_srcdir}/unordered_set \
@@ -160,6 +161,7 @@ bits_freestanding = \
 	${bits_srcdir}/stl_raw_storage_iter.h \
 	${bits_srcdir}/stl_relops.h \
 	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/text_encoding-data.h \
 	${bits_srcdir}/version.h \
 	${bits_srcdir}/string_view.tcc \
 	${bits_srcdir}/unicode.h \
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 621f2a29f50..a2e94217006 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -40,6 +40,10 @@
 #include <string>
 #include <ext/atomicity.h>
 
+#ifdef __glibcxx_text_encoding
+#include <text_encoding>
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string
     name() const;
 
+#ifdef __glibcxx_text_encoding
+# if __CHAR_BIT__ == 8
+    text_encoding
+    encoding() const;
+# else
+    text_encoding
+    encoding() const = delete;
+# endif
+#endif
+
     /**
      *  @brief  Locale equality.
      *
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
new file mode 100644
index 00000000000..7ac2e9dc3d9
--- /dev/null
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -0,0 +1,902 @@
+// Generated by gen_text_encoding_data.py, do not edit.
+
+#ifndef _GLIBCXX_GET_ENCODING_DATA
+# error "This is not a public header, do not include it directly"
+#endif
+
+  {    3, "US-ASCII" },
+  {    3, "iso-ir-6" },
+  {    3, "ANSI_X3.4-1968" },
+  {    3, "ANSI_X3.4-1986" },
+  {    3, "ISO_646.irv:1991" },
+  {    3, "ISO646-US" },
+  {    3, "us" },
+  {    3, "IBM367" },
+  {    3, "cp367" },
+  {    3, "csASCII" },
+  {    4, "ISO_8859-1:1987" },
+  {    4, "iso-ir-100" },
+  {    4, "ISO_8859-1" },
+  {    4, "ISO-8859-1" },
+  {    4, "latin1" },
+  {    4, "l1" },
+  {    4, "IBM819" },
+  {    4, "CP819" },
+  {    4, "csISOLatin1" },
+  {    5, "ISO_8859-2:1987" },
+  {    5, "iso-ir-101" },
+  {    5, "ISO_8859-2" },
+  {    5, "ISO-8859-2" },
+  {    5, "latin2" },
+  {    5, "l2" },
+  {    5, "csISOLatin2" },
+  {    6, "ISO_8859-3:1988" },
+  {    6, "iso-ir-109" },
+  {    6, "ISO_8859-3" },
+  {    6, "ISO-8859-3" },
+  {    6, "latin3" },
+  {    6, "l3" },
+  {    6, "csISOLatin3" },
+  {    7, "ISO_8859-4:1988" },
+  {    7, "iso-ir-110" },
+  {    7, "ISO_8859-4" },
+  {    7, "ISO-8859-4" },
+  {    7, "latin4" },
+  {    7, "l4" },
+  {    7, "csISOLatin4" },
+  {    8, "ISO_8859-5:1988" },
+  {    8, "iso-ir-144" },
+  {    8, "ISO_8859-5" },
+  {    8, "ISO-8859-5" },
+  {    8, "cyrillic" },
+  {    8, "csISOLatinCyrillic" },
+  {    9, "ISO_8859-6:1987" },
+  {    9, "iso-ir-127" },
+  {    9, "ISO_8859-6" },
+  {    9, "ISO-8859-6" },
+  {    9, "ECMA-114" },
+  {    9, "ASMO-708" },
+  {    9, "arabic" },
+  {    9, "csISOLatinArabic" },
+  {   10, "ISO_8859-7:1987" },
+  {   10, "iso-ir-126" },
+  {   10, "ISO_8859-7" },
+  {   10, "ISO-8859-7" },
+  {   10, "ELOT_928" },
+  {   10, "ECMA-118" },
+  {   10, "greek" },
+  {   10, "greek8" },
+  {   10, "csISOLatinGreek" },
+  {   11, "ISO_8859-8:1988" },
+  {   11, "iso-ir-138" },
+  {   11, "ISO_8859-8" },
+  {   11, "ISO-8859-8" },
+  {   11, "hebrew" },
+  {   11, "csISOLatinHebrew" },
+  {   12, "ISO_8859-9:1989" },
+  {   12, "iso-ir-148" },
+  {   12, "ISO_8859-9" },
+  {   12, "ISO-8859-9" },
+  {   12, "latin5" },
+  {   12, "l5" },
+  {   12, "csISOLatin5" },
+  {   13, "ISO-8859-10" },
+  {   13, "iso-ir-157" },
+  {   13, "l6" },
+  {   13, "ISO_8859-10:1992" },
+  {   13, "csISOLatin6" },
+  {   13, "latin6" },
+  {   14, "ISO_6937-2-add" },
+  {   14, "iso-ir-142" },
+  {   14, "csISOTextComm" },
+  {   15, "JIS_X0201" },
+  {   15, "X0201" },
+  {   15, "csHalfWidthKatakana" },
+  {   16, "JIS_Encoding" },
+  {   16, "csJISEncoding" },
+  {   17, "Shift_JIS" },
+  {   17, "MS_Kanji" },
+  {   17, "csShiftJIS" },
+  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
+  {   18, "csEUCPkdFmtJapanese" },
+  {   18, "EUC-JP" },
+  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
+  {   19, "csEUCFixWidJapanese" },
+  {   20, "BS_4730" },
+  {   20, "iso-ir-4" },
+  {   20, "ISO646-GB" },
+  {   20, "gb" },
+  {   20, "uk" },
+  {   20, "csISO4UnitedKingdom" },
+  {   21, "SEN_850200_C" },
+  {   21, "iso-ir-11" },
+  {   21, "ISO646-SE2" },
+  {   21, "se2" },
+  {   21, "csISO11SwedishForNames" },
+  {   22, "IT" },
+  {   22, "iso-ir-15" },
+  {   22, "ISO646-IT" },
+  {   22, "csISO15Italian" },
+  {   23, "ES" },
+  {   23, "iso-ir-17" },
+  {   23, "ISO646-ES" },
+  {   23, "csISO17Spanish" },
+  {   24, "DIN_66003" },
+  {   24, "iso-ir-21" },
+  {   24, "de" },
+  {   24, "ISO646-DE" },
+  {   24, "csISO21German" },
+  {   25, "NS_4551-1" },
+  {   25, "iso-ir-60" },
+  {   25, "ISO646-NO" },
+  {   25, "no" },
+  {   25, "csISO60DanishNorwegian" },
+  {   25, "csISO60Norwegian1" },
+  {   26, "NF_Z_62-010" },
+  {   26, "iso-ir-69" },
+  {   26, "ISO646-FR" },
+  {   26, "fr" },
+  {   26, "csISO69French" },
+  {   27, "ISO-10646-UTF-1" },
+  {   27, "csISO10646UTF1" },
+  {   28, "ISO_646.basic:1983" },
+  {   28, "ref" },
+  {   28, "csISO646basic1983" },
+  {   29, "INVARIANT" },
+  {   29, "csINVARIANT" },
+  {   30, "ISO_646.irv:1983" },
+  {   30, "iso-ir-2" },
+  {   30, "irv" },
+  {   30, "csISO2IntlRefVersion" },
+  {   31, "NATS-SEFI" },
+  {   31, "iso-ir-8-1" },
+  {   31, "csNATSSEFI" },
+  {   32, "NATS-SEFI-ADD" },
+  {   32, "iso-ir-8-2" },
+  {   32, "csNATSSEFIADD" },
+  {   35, "SEN_850200_B" },
+  {   35, "iso-ir-10" },
+  {   35, "FI" },
+  {   35, "ISO646-FI" },
+  {   35, "ISO646-SE" },
+  {   35, "se" },
+  {   35, "csISO10Swedish" },
+  {   36, "KS_C_5601-1987" },
+  {   36, "iso-ir-149" },
+  {   36, "KS_C_5601-1989" },
+  {   36, "KSC_5601" },
+  {   36, "korean" },
+  {   36, "csKSC56011987" },
+  {   37, "ISO-2022-KR" },
+  {   37, "csISO2022KR" },
+  {   38, "EUC-KR" },
+  {   38, "csEUCKR" },
+  {   39, "ISO-2022-JP" },
+  {   39, "csISO2022JP" },
+  {   40, "ISO-2022-JP-2" },
+  {   40, "csISO2022JP2" },
+  {   41, "JIS_C6220-1969-jp" },
+  {   41, "JIS_C6220-1969" },
+  {   41, "iso-ir-13" },
+  {   41, "katakana" },
+  {   41, "x0201-7" },
+  {   41, "csISO13JISC6220jp" },
+  {   42, "JIS_C6220-1969-ro" },
+  {   42, "iso-ir-14" },
+  {   42, "jp" },
+  {   42, "ISO646-JP" },
+  {   42, "csISO14JISC6220ro" },
+  {   43, "PT" },
+  {   43, "iso-ir-16" },
+  {   43, "ISO646-PT" },
+  {   43, "csISO16Portuguese" },
+  {   44, "greek7-old" },
+  {   44, "iso-ir-18" },
+  {   44, "csISO18Greek7Old" },
+  {   45, "latin-greek" },
+  {   45, "iso-ir-19" },
+  {   45, "csISO19LatinGreek" },
+  {   46, "NF_Z_62-010_(1973)" },
+  {   46, "iso-ir-25" },
+  {   46, "ISO646-FR1" },
+  {   46, "csISO25French" },
+  {   47, "Latin-greek-1" },
+  {   47, "iso-ir-27" },
+  {   47, "csISO27LatinGreek1" },
+  {   48, "ISO_5427" },
+  {   48, "iso-ir-37" },
+  {   48, "csISO5427Cyrillic" },
+  {   49, "JIS_C6226-1978" },
+  {   49, "iso-ir-42" },
+  {   49, "csISO42JISC62261978" },
+  {   50, "BS_viewdata" },
+  {   50, "iso-ir-47" },
+  {   50, "csISO47BSViewdata" },
+  {   51, "INIS" },
+  {   51, "iso-ir-49" },
+  {   51, "csISO49INIS" },
+  {   52, "INIS-8" },
+  {   52, "iso-ir-50" },
+  {   52, "csISO50INIS8" },
+  {   53, "INIS-cyrillic" },
+  {   53, "iso-ir-51" },
+  {   53, "csISO51INISCyrillic" },
+  {   54, "ISO_5427:1981" },
+  {   54, "iso-ir-54" },
+  {   54, "ISO5427Cyrillic1981" },
+  {   54, "csISO54271981" },
+  {   55, "ISO_5428:1980" },
+  {   55, "iso-ir-55" },
+  {   55, "csISO5428Greek" },
+  {   56, "GB_1988-80" },
+  {   56, "iso-ir-57" },
+  {   56, "cn" },
+  {   56, "ISO646-CN" },
+  {   56, "csISO57GB1988" },
+  {   57, "GB_2312-80" },
+  {   57, "iso-ir-58" },
+  {   57, "chinese" },
+  {   57, "csISO58GB231280" },
+  {   58, "NS_4551-2" },
+  {   58, "ISO646-NO2" },
+  {   58, "iso-ir-61" },
+  {   58, "no2" },
+  {   58, "csISO61Norwegian2" },
+  {   59, "videotex-suppl" },
+  {   59, "iso-ir-70" },
+  {   59, "csISO70VideotexSupp1" },
+  {   60, "PT2" },
+  {   60, "iso-ir-84" },
+  {   60, "ISO646-PT2" },
+  {   60, "csISO84Portuguese2" },
+  {   61, "ES2" },
+  {   61, "iso-ir-85" },
+  {   61, "ISO646-ES2" },
+  {   61, "csISO85Spanish2" },
+  {   62, "MSZ_7795.3" },
+  {   62, "iso-ir-86" },
+  {   62, "ISO646-HU" },
+  {   62, "hu" },
+  {   62, "csISO86Hungarian" },
+  {   63, "JIS_C6226-1983" },
+  {   63, "iso-ir-87" },
+  {   63, "x0208" },
+  {   63, "JIS_X0208-1983" },
+  {   63, "csISO87JISX0208" },
+  {   64, "greek7" },
+  {   64, "iso-ir-88" },
+  {   64, "csISO88Greek7" },
+  {   65, "ASMO_449" },
+  {   65, "ISO_9036" },
+  {   65, "arabic7" },
+  {   65, "iso-ir-89" },
+  {   65, "csISO89ASMO449" },
+  {   66, "iso-ir-90" },
+  {   66, "csISO90" },
+  {   67, "JIS_C6229-1984-a" },
+  {   67, "iso-ir-91" },
+  {   67, "jp-ocr-a" },
+  {   67, "csISO91JISC62291984a" },
+  {   68, "JIS_C6229-1984-b" },
+  {   68, "iso-ir-92" },
+  {   68, "ISO646-JP-OCR-B" },
+  {   68, "jp-ocr-b" },
+  {   68, "csISO92JISC62991984b" },
+  {   69, "JIS_C6229-1984-b-add" },
+  {   69, "iso-ir-93" },
+  {   69, "jp-ocr-b-add" },
+  {   69, "csISO93JIS62291984badd" },
+  {   70, "JIS_C6229-1984-hand" },
+  {   70, "iso-ir-94" },
+  {   70, "jp-ocr-hand" },
+  {   70, "csISO94JIS62291984hand" },
+  {   71, "JIS_C6229-1984-hand-add" },
+  {   71, "iso-ir-95" },
+  {   71, "jp-ocr-hand-add" },
+  {   71, "csISO95JIS62291984handadd" },
+  {   72, "JIS_C6229-1984-kana" },
+  {   72, "iso-ir-96" },
+  {   72, "csISO96JISC62291984kana" },
+  {   73, "ISO_2033-1983" },
+  {   73, "iso-ir-98" },
+  {   73, "e13b" },
+  {   73, "csISO2033" },
+  {   74, "ANSI_X3.110-1983" },
+  {   74, "iso-ir-99" },
+  {   74, "CSA_T500-1983" },
+  {   74, "NAPLPS" },
+  {   74, "csISO99NAPLPS" },
+  {   75, "T.61-7bit" },
+  {   75, "iso-ir-102" },
+  {   75, "csISO102T617bit" },
+  {   76, "T.61-8bit" },
+  {   76, "T.61" },
+  {   76, "iso-ir-103" },
+  {   76, "csISO103T618bit" },
+  {   77, "ECMA-cyrillic" },
+  {   77, "iso-ir-111" },
+  {   77, "KOI8-E" },
+  {   77, "csISO111ECMACyrillic" },
+  {   78, "CSA_Z243.4-1985-1" },
+  {   78, "iso-ir-121" },
+  {   78, "ISO646-CA" },
+  {   78, "csa7-1" },
+  {   78, "csa71" },
+  {   78, "ca" },
+  {   78, "csISO121Canadian1" },
+  {   79, "CSA_Z243.4-1985-2" },
+  {   79, "iso-ir-122" },
+  {   79, "ISO646-CA2" },
+  {   79, "csa7-2" },
+  {   79, "csa72" },
+  {   79, "csISO122Canadian2" },
+  {   80, "CSA_Z243.4-1985-gr" },
+  {   80, "iso-ir-123" },
+  {   80, "csISO123CSAZ24341985gr" },
+  {   81, "ISO_8859-6-E" },
+  {   81, "csISO88596E" },
+  {   81, "ISO-8859-6-E" },
+  {   82, "ISO_8859-6-I" },
+  {   82, "csISO88596I" },
+  {   82, "ISO-8859-6-I" },
+  {   83, "T.101-G2" },
+  {   83, "iso-ir-128" },
+  {   83, "csISO128T101G2" },
+  {   84, "ISO_8859-8-E" },
+  {   84, "csISO88598E" },
+  {   84, "ISO-8859-8-E" },
+  {   85, "ISO_8859-8-I" },
+  {   85, "csISO88598I" },
+  {   85, "ISO-8859-8-I" },
+  {   86, "CSN_369103" },
+  {   86, "iso-ir-139" },
+  {   86, "csISO139CSN369103" },
+  {   87, "JUS_I.B1.002" },
+  {   87, "iso-ir-141" },
+  {   87, "ISO646-YU" },
+  {   87, "js" },
+  {   87, "yu" },
+  {   87, "csISO141JUSIB1002" },
+  {   88, "IEC_P27-1" },
+  {   88, "iso-ir-143" },
+  {   88, "csISO143IECP271" },
+  {   89, "JUS_I.B1.003-serb" },
+  {   89, "iso-ir-146" },
+  {   89, "serbian" },
+  {   89, "csISO146Serbian" },
+  {   90, "JUS_I.B1.003-mac" },
+  {   90, "macedonian" },
+  {   90, "iso-ir-147" },
+  {   90, "csISO147Macedonian" },
+  {   91, "greek-ccitt" },
+  {   91, "iso-ir-150" },
+  {   91, "csISO150" },
+  {   91, "csISO150GreekCCITT" },
+  {   92, "NC_NC00-10:81" },
+  {   92, "cuba" },
+  {   92, "iso-ir-151" },
+  {   92, "ISO646-CU" },
+  {   92, "csISO151Cuba" },
+  {   93, "ISO_6937-2-25" },
+  {   93, "iso-ir-152" },
+  {   93, "csISO6937Add" },
+  {   94, "GOST_19768-74" },
+  {   94, "ST_SEV_358-88" },
+  {   94, "iso-ir-153" },
+  {   94, "csISO153GOST1976874" },
+  {   95, "ISO_8859-supp" },
+  {   95, "iso-ir-154" },
+  {   95, "latin1-2-5" },
+  {   95, "csISO8859Supp" },
+  {   96, "ISO_10367-box" },
+  {   96, "iso-ir-155" },
+  {   96, "csISO10367Box" },
+  {   97, "latin-lap" },
+  {   97, "lap" },
+  {   97, "iso-ir-158" },
+  {   97, "csISO158Lap" },
+  {   98, "JIS_X0212-1990" },
+  {   98, "x0212" },
+  {   98, "iso-ir-159" },
+  {   98, "csISO159JISX02121990" },
+  {   99, "DS_2089" },
+  {   99, "DS2089" },
+  {   99, "ISO646-DK" },
+  {   99, "dk" },
+  {   99, "csISO646Danish" },
+  {  100, "us-dk" },
+  {  100, "csUSDK" },
+  {  101, "dk-us" },
+  {  101, "csDKUS" },
+  {  102, "KSC5636" },
+  {  102, "ISO646-KR" },
+  {  102, "csKSC5636" },
+  {  103, "UNICODE-1-1-UTF-7" },
+  {  103, "csUnicode11UTF7" },
+  {  104, "ISO-2022-CN" },
+  {  104, "csISO2022CN" },
+  {  105, "ISO-2022-CN-EXT" },
+  {  105, "csISO2022CNEXT" },
+#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
+  {  106, "UTF-8" },
+  {  106, "csUTF8" },
+  {  109, "ISO-8859-13" },
+  {  109, "csISO885913" },
+  {  110, "ISO-8859-14" },
+  {  110, "iso-ir-199" },
+  {  110, "ISO_8859-14:1998" },
+  {  110, "ISO_8859-14" },
+  {  110, "latin8" },
+  {  110, "iso-celtic" },
+  {  110, "l8" },
+  {  110, "csISO885914" },
+  {  111, "ISO-8859-15" },
+  {  111, "ISO_8859-15" },
+  {  111, "Latin-9" },
+  {  111, "csISO885915" },
+  {  112, "ISO-8859-16" },
+  {  112, "iso-ir-226" },
+  {  112, "ISO_8859-16:2001" },
+  {  112, "ISO_8859-16" },
+  {  112, "latin10" },
+  {  112, "l10" },
+  {  112, "csISO885916" },
+  {  113, "GBK" },
+  {  113, "CP936" },
+  {  113, "MS936" },
+  {  113, "windows-936" },
+  {  113, "csGBK" },
+  {  114, "GB18030" },
+  {  114, "csGB18030" },
+  {  115, "OSD_EBCDIC_DF04_15" },
+  {  115, "csOSDEBCDICDF0415" },
+  {  116, "OSD_EBCDIC_DF03_IRV" },
+  {  116, "csOSDEBCDICDF03IRV" },
+  {  117, "OSD_EBCDIC_DF04_1" },
+  {  117, "csOSDEBCDICDF041" },
+  {  118, "ISO-11548-1" },
+  {  118, "ISO_11548-1" },
+  {  118, "ISO_TR_11548-1" },
+  {  118, "csISO115481" },
+  {  119, "KZ-1048" },
+  {  119, "STRK1048-2002" },
+  {  119, "RK1048" },
+  {  119, "csKZ1048" },
+  { 1000, "ISO-10646-UCS-2" },
+  { 1000, "csUnicode" },
+  { 1001, "ISO-10646-UCS-4" },
+  { 1001, "csUCS4" },
+  { 1002, "ISO-10646-UCS-Basic" },
+  { 1002, "csUnicodeASCII" },
+  { 1003, "ISO-10646-Unicode-Latin1" },
+  { 1003, "csUnicodeLatin1" },
+  { 1003, "ISO-10646" },
+  { 1004, "ISO-10646-J-1" },
+  { 1004, "csUnicodeJapanese" },
+  { 1005, "ISO-Unicode-IBM-1261" },
+  { 1005, "csUnicodeIBM1261" },
+  { 1006, "ISO-Unicode-IBM-1268" },
+  { 1006, "csUnicodeIBM1268" },
+  { 1007, "ISO-Unicode-IBM-1276" },
+  { 1007, "csUnicodeIBM1276" },
+  { 1008, "ISO-Unicode-IBM-1264" },
+  { 1008, "csUnicodeIBM1264" },
+  { 1009, "ISO-Unicode-IBM-1265" },
+  { 1009, "csUnicodeIBM1265" },
+  { 1010, "UNICODE-1-1" },
+  { 1010, "csUnicode11" },
+  { 1011, "SCSU" },
+  { 1011, "csSCSU" },
+  { 1012, "UTF-7" },
+  { 1012, "csUTF7" },
+  { 1013, "UTF-16BE" },
+  { 1013, "csUTF16BE" },
+  { 1014, "UTF-16LE" },
+  { 1014, "csUTF16LE" },
+  { 1015, "UTF-16" },
+  { 1015, "csUTF16" },
+  { 1016, "CESU-8" },
+  { 1016, "csCESU8" },
+  { 1016, "csCESU-8" },
+  { 1017, "UTF-32" },
+  { 1017, "csUTF32" },
+  { 1018, "UTF-32BE" },
+  { 1018, "csUTF32BE" },
+  { 1019, "UTF-32LE" },
+  { 1019, "csUTF32LE" },
+  { 1020, "BOCU-1" },
+  { 1020, "csBOCU1" },
+  { 1020, "csBOCU-1" },
+  { 1021, "UTF-7-IMAP" },
+  { 1021, "csUTF7IMAP" },
+  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
+  { 2000, "csWindows30Latin1" },
+  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
+  { 2001, "csWindows31Latin1" },
+  { 2002, "ISO-8859-2-Windows-Latin-2" },
+  { 2002, "csWindows31Latin2" },
+  { 2003, "ISO-8859-9-Windows-Latin-5" },
+  { 2003, "csWindows31Latin5" },
+  { 2004, "hp-roman8" },
+  { 2004, "roman8" },
+  { 2004, "r8" },
+  { 2004, "csHPRoman8" },
+  { 2005, "Adobe-Standard-Encoding" },
+  { 2005, "csAdobeStandardEncoding" },
+  { 2006, "Ventura-US" },
+  { 2006, "csVenturaUS" },
+  { 2007, "Ventura-International" },
+  { 2007, "csVenturaInternational" },
+  { 2008, "DEC-MCS" },
+  { 2008, "dec" },
+  { 2008, "csDECMCS" },
+  { 2009, "IBM850" },
+  { 2009, "cp850" },
+  { 2009, "850" },
+  { 2009, "csPC850Multilingual" },
+  { 2010, "IBM852" },
+  { 2010, "cp852" },
+  { 2010, "852" },
+  { 2010, "csPCp852" },
+  { 2011, "IBM437" },
+  { 2011, "cp437" },
+  { 2011, "437" },
+  { 2011, "csPC8CodePage437" },
+  { 2012, "PC8-Danish-Norwegian" },
+  { 2012, "csPC8DanishNorwegian" },
+  { 2013, "IBM862" },
+  { 2013, "cp862" },
+  { 2013, "862" },
+  { 2013, "csPC862LatinHebrew" },
+  { 2014, "PC8-Turkish" },
+  { 2014, "csPC8Turkish" },
+  { 2015, "IBM-Symbols" },
+  { 2015, "csIBMSymbols" },
+  { 2016, "IBM-Thai" },
+  { 2016, "csIBMThai" },
+  { 2017, "HP-Legal" },
+  { 2017, "csHPLegal" },
+  { 2018, "HP-Pi-font" },
+  { 2018, "csHPPiFont" },
+  { 2019, "HP-Math8" },
+  { 2019, "csHPMath8" },
+  { 2020, "Adobe-Symbol-Encoding" },
+  { 2020, "csHPPSMath" },
+  { 2021, "HP-DeskTop" },
+  { 2021, "csHPDesktop" },
+  { 2022, "Ventura-Math" },
+  { 2022, "csVenturaMath" },
+  { 2023, "Microsoft-Publishing" },
+  { 2023, "csMicrosoftPublishing" },
+  { 2024, "Windows-31J" },
+  { 2024, "csWindows31J" },
+  { 2025, "GB2312" },
+  { 2025, "csGB2312" },
+  { 2026, "Big5" },
+  { 2026, "csBig5" },
+  { 2027, "macintosh" },
+  { 2027, "mac" },
+  { 2027, "csMacintosh" },
+  { 2028, "IBM037" },
+  { 2028, "cp037" },
+  { 2028, "ebcdic-cp-us" },
+  { 2028, "ebcdic-cp-ca" },
+  { 2028, "ebcdic-cp-wt" },
+  { 2028, "ebcdic-cp-nl" },
+  { 2028, "csIBM037" },
+  { 2029, "IBM038" },
+  { 2029, "EBCDIC-INT" },
+  { 2029, "cp038" },
+  { 2029, "csIBM038" },
+  { 2030, "IBM273" },
+  { 2030, "CP273" },
+  { 2030, "csIBM273" },
+  { 2031, "IBM274" },
+  { 2031, "EBCDIC-BE" },
+  { 2031, "CP274" },
+  { 2031, "csIBM274" },
+  { 2032, "IBM275" },
+  { 2032, "EBCDIC-BR" },
+  { 2032, "cp275" },
+  { 2032, "csIBM275" },
+  { 2033, "IBM277" },
+  { 2033, "EBCDIC-CP-DK" },
+  { 2033, "EBCDIC-CP-NO" },
+  { 2033, "csIBM277" },
+  { 2034, "IBM278" },
+  { 2034, "CP278" },
+  { 2034, "ebcdic-cp-fi" },
+  { 2034, "ebcdic-cp-se" },
+  { 2034, "csIBM278" },
+  { 2035, "IBM280" },
+  { 2035, "CP280" },
+  { 2035, "ebcdic-cp-it" },
+  { 2035, "csIBM280" },
+  { 2036, "IBM281" },
+  { 2036, "EBCDIC-JP-E" },
+  { 2036, "cp281" },
+  { 2036, "csIBM281" },
+  { 2037, "IBM284" },
+  { 2037, "CP284" },
+  { 2037, "ebcdic-cp-es" },
+  { 2037, "csIBM284" },
+  { 2038, "IBM285" },
+  { 2038, "CP285" },
+  { 2038, "ebcdic-cp-gb" },
+  { 2038, "csIBM285" },
+  { 2039, "IBM290" },
+  { 2039, "cp290" },
+  { 2039, "EBCDIC-JP-kana" },
+  { 2039, "csIBM290" },
+  { 2040, "IBM297" },
+  { 2040, "cp297" },
+  { 2040, "ebcdic-cp-fr" },
+  { 2040, "csIBM297" },
+  { 2041, "IBM420" },
+  { 2041, "cp420" },
+  { 2041, "ebcdic-cp-ar1" },
+  { 2041, "csIBM420" },
+  { 2042, "IBM423" },
+  { 2042, "cp423" },
+  { 2042, "ebcdic-cp-gr" },
+  { 2042, "csIBM423" },
+  { 2043, "IBM424" },
+  { 2043, "cp424" },
+  { 2043, "ebcdic-cp-he" },
+  { 2043, "csIBM424" },
+  { 2044, "IBM500" },
+  { 2044, "CP500" },
+  { 2044, "ebcdic-cp-be" },
+  { 2044, "ebcdic-cp-ch" },
+  { 2044, "csIBM500" },
+  { 2045, "IBM851" },
+  { 2045, "cp851" },
+  { 2045, "851" },
+  { 2045, "csIBM851" },
+  { 2046, "IBM855" },
+  { 2046, "cp855" },
+  { 2046, "855" },
+  { 2046, "csIBM855" },
+  { 2047, "IBM857" },
+  { 2047, "cp857" },
+  { 2047, "857" },
+  { 2047, "csIBM857" },
+  { 2048, "IBM860" },
+  { 2048, "cp860" },
+  { 2048, "860" },
+  { 2048, "csIBM860" },
+  { 2049, "IBM861" },
+  { 2049, "cp861" },
+  { 2049, "861" },
+  { 2049, "cp-is" },
+  { 2049, "csIBM861" },
+  { 2050, "IBM863" },
+  { 2050, "cp863" },
+  { 2050, "863" },
+  { 2050, "csIBM863" },
+  { 2051, "IBM864" },
+  { 2051, "cp864" },
+  { 2051, "csIBM864" },
+  { 2052, "IBM865" },
+  { 2052, "cp865" },
+  { 2052, "865" },
+  { 2052, "csIBM865" },
+  { 2053, "IBM868" },
+  { 2053, "CP868" },
+  { 2053, "cp-ar" },
+  { 2053, "csIBM868" },
+  { 2054, "IBM869" },
+  { 2054, "cp869" },
+  { 2054, "869" },
+  { 2054, "cp-gr" },
+  { 2054, "csIBM869" },
+  { 2055, "IBM870" },
+  { 2055, "CP870" },
+  { 2055, "ebcdic-cp-roece" },
+  { 2055, "ebcdic-cp-yu" },
+  { 2055, "csIBM870" },
+  { 2056, "IBM871" },
+  { 2056, "CP871" },
+  { 2056, "ebcdic-cp-is" },
+  { 2056, "csIBM871" },
+  { 2057, "IBM880" },
+  { 2057, "cp880" },
+  { 2057, "EBCDIC-Cyrillic" },
+  { 2057, "csIBM880" },
+  { 2058, "IBM891" },
+  { 2058, "cp891" },
+  { 2058, "csIBM891" },
+  { 2059, "IBM903" },
+  { 2059, "cp903" },
+  { 2059, "csIBM903" },
+  { 2060, "IBM904" },
+  { 2060, "cp904" },
+  { 2060, "904" },
+  { 2060, "csIBBM904" },
+  { 2061, "IBM905" },
+  { 2061, "CP905" },
+  { 2061, "ebcdic-cp-tr" },
+  { 2061, "csIBM905" },
+  { 2062, "IBM918" },
+  { 2062, "CP918" },
+  { 2062, "ebcdic-cp-ar2" },
+  { 2062, "csIBM918" },
+  { 2063, "IBM1026" },
+  { 2063, "CP1026" },
+  { 2063, "csIBM1026" },
+  { 2064, "EBCDIC-AT-DE" },
+  { 2064, "csIBMEBCDICATDE" },
+  { 2065, "EBCDIC-AT-DE-A" },
+  { 2065, "csEBCDICATDEA" },
+  { 2066, "EBCDIC-CA-FR" },
+  { 2066, "csEBCDICCAFR" },
+  { 2067, "EBCDIC-DK-NO" },
+  { 2067, "csEBCDICDKNO" },
+  { 2068, "EBCDIC-DK-NO-A" },
+  { 2068, "csEBCDICDKNOA" },
+  { 2069, "EBCDIC-FI-SE" },
+  { 2069, "csEBCDICFISE" },
+  { 2070, "EBCDIC-FI-SE-A" },
+  { 2070, "csEBCDICFISEA" },
+  { 2071, "EBCDIC-FR" },
+  { 2071, "csEBCDICFR" },
+  { 2072, "EBCDIC-IT" },
+  { 2072, "csEBCDICIT" },
+  { 2073, "EBCDIC-PT" },
+  { 2073, "csEBCDICPT" },
+  { 2074, "EBCDIC-ES" },
+  { 2074, "csEBCDICES" },
+  { 2075, "EBCDIC-ES-A" },
+  { 2075, "csEBCDICESA" },
+  { 2076, "EBCDIC-ES-S" },
+  { 2076, "csEBCDICESS" },
+  { 2077, "EBCDIC-UK" },
+  { 2077, "csEBCDICUK" },
+  { 2078, "EBCDIC-US" },
+  { 2078, "csEBCDICUS" },
+  { 2079, "UNKNOWN-8BIT" },
+  { 2079, "csUnknown8BiT" },
+  { 2080, "MNEMONIC" },
+  { 2080, "csMnemonic" },
+  { 2081, "MNEM" },
+  { 2081, "csMnem" },
+  { 2082, "VISCII" },
+  { 2082, "csVISCII" },
+  { 2083, "VIQR" },
+  { 2083, "csVIQR" },
+  { 2084, "KOI8-R" },
+  { 2084, "csKOI8R" },
+  { 2085, "HZ-GB-2312" },
+  { 2086, "IBM866" },
+  { 2086, "cp866" },
+  { 2086, "866" },
+  { 2086, "csIBM866" },
+  { 2087, "IBM775" },
+  { 2087, "cp775" },
+  { 2087, "csPC775Baltic" },
+  { 2088, "KOI8-U" },
+  { 2088, "csKOI8U" },
+  { 2089, "IBM00858" },
+  { 2089, "CCSID00858" },
+  { 2089, "CP00858" },
+  { 2089, "PC-Multilingual-850+euro" },
+  { 2089, "csIBM00858" },
+  { 2090, "IBM00924" },
+  { 2090, "CCSID00924" },
+  { 2090, "CP00924" },
+  { 2090, "ebcdic-Latin9--euro" },
+  { 2090, "csIBM00924" },
+  { 2091, "IBM01140" },
+  { 2091, "CCSID01140" },
+  { 2091, "CP01140" },
+  { 2091, "ebcdic-us-37+euro" },
+  { 2091, "csIBM01140" },
+  { 2092, "IBM01141" },
+  { 2092, "CCSID01141" },
+  { 2092, "CP01141" },
+  { 2092, "ebcdic-de-273+euro" },
+  { 2092, "csIBM01141" },
+  { 2093, "IBM01142" },
+  { 2093, "CCSID01142" },
+  { 2093, "CP01142" },
+  { 2093, "ebcdic-dk-277+euro" },
+  { 2093, "ebcdic-no-277+euro" },
+  { 2093, "csIBM01142" },
+  { 2094, "IBM01143" },
+  { 2094, "CCSID01143" },
+  { 2094, "CP01143" },
+  { 2094, "ebcdic-fi-278+euro" },
+  { 2094, "ebcdic-se-278+euro" },
+  { 2094, "csIBM01143" },
+  { 2095, "IBM01144" },
+  { 2095, "CCSID01144" },
+  { 2095, "CP01144" },
+  { 2095, "ebcdic-it-280+euro" },
+  { 2095, "csIBM01144" },
+  { 2096, "IBM01145" },
+  { 2096, "CCSID01145" },
+  { 2096, "CP01145" },
+  { 2096, "ebcdic-es-284+euro" },
+  { 2096, "csIBM01145" },
+  { 2097, "IBM01146" },
+  { 2097, "CCSID01146" },
+  { 2097, "CP01146" },
+  { 2097, "ebcdic-gb-285+euro" },
+  { 2097, "csIBM01146" },
+  { 2098, "IBM01147" },
+  { 2098, "CCSID01147" },
+  { 2098, "CP01147" },
+  { 2098, "ebcdic-fr-297+euro" },
+  { 2098, "csIBM01147" },
+  { 2099, "IBM01148" },
+  { 2099, "CCSID01148" },
+  { 2099, "CP01148" },
+  { 2099, "ebcdic-international-500+euro" },
+  { 2099, "csIBM01148" },
+  { 2100, "IBM01149" },
+  { 2100, "CCSID01149" },
+  { 2100, "CP01149" },
+  { 2100, "ebcdic-is-871+euro" },
+  { 2100, "csIBM01149" },
+  { 2101, "Big5-HKSCS" },
+  { 2101, "csBig5HKSCS" },
+  { 2102, "IBM1047" },
+  { 2102, "IBM-1047" },
+  { 2102, "csIBM1047" },
+  { 2103, "PTCP154" },
+  { 2103, "csPTCP154" },
+  { 2103, "PT154" },
+  { 2103, "CP154" },
+  { 2103, "Cyrillic-Asian" },
+  { 2104, "Amiga-1251" },
+  { 2104, "Ami1251" },
+  { 2104, "Amiga1251" },
+  { 2104, "Ami-1251" },
+  { 2104, "csAmiga1251" },
+  { 2104, "(Aliases" },
+  { 2104, "are" },
+  { 2104, "provided" },
+  { 2104, "for" },
+  { 2104, "historical" },
+  { 2104, "reasons" },
+  { 2104, "and" },
+  { 2104, "should" },
+  { 2104, "not" },
+  { 2104, "be" },
+  { 2104, "used)" },
+  { 2104, "[Malyshev]" },
+  { 2105, "KOI7-switched" },
+  { 2105, "csKOI7switched" },
+  { 2106, "BRF" },
+  { 2106, "csBRF" },
+  { 2107, "TSCII" },
+  { 2107, "csTSCII" },
+  { 2108, "CP51932" },
+  { 2108, "csCP51932" },
+  { 2109, "windows-874" },
+  { 2109, "cswindows874" },
+  { 2250, "windows-1250" },
+  { 2250, "cswindows1250" },
+  { 2251, "windows-1251" },
+  { 2251, "cswindows1251" },
+  { 2252, "windows-1252" },
+  { 2252, "cswindows1252" },
+  { 2253, "windows-1253" },
+  { 2253, "cswindows1253" },
+  { 2254, "windows-1254" },
+  { 2254, "cswindows1254" },
+  { 2255, "windows-1255" },
+  { 2255, "cswindows1255" },
+  { 2256, "windows-1256" },
+  { 2256, "cswindows1256" },
+  { 2257, "windows-1257" },
+  { 2257, "cswindows1257" },
+  { 2258, "windows-1258" },
+  { 2258, "cswindows1258" },
+  { 2259, "TIS-620" },
+  { 2259, "csTIS620" },
+  { 2259, "ISO-8859-11" },
+  { 2260, "CP50220" },
+  { 2260, "csCP50220" },
+
+#undef _GLIBCXX_GET_ENCODING_DATA
diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
index f1b2b359bdf..f531faa04d0 100644
--- a/libstdc++-v3/include/bits/unicode.h
+++ b/libstdc++-v3/include/bits/unicode.h
@@ -986,7 +986,7 @@ inline namespace __v15_1_0
       return __n;
     }
 
-    template<typename _CharT>
+  template<typename _CharT>
     consteval bool
     __literal_encoding_is_unicode()
     {
@@ -1056,6 +1056,161 @@ inline namespace __v15_1_0
   __literal_encoding_is_utf8()
   { return __literal_encoding_is_unicode<char>(); }
 
+  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
+  constexpr bool
+  __charset_alias_match(string_view __a, string_view __b)
+  {
+    auto __map = [](char __c, bool& __num) {
+      switch (__c)
+      {
+	case '0':
+	  return __num ? __c : '\0';
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+	case '8':
+	case '9':
+	  __num = true;
+	  return __c;
+	case 'A':
+	  __c = 'a';
+	  break;
+	case 'B':
+	  __c = 'b';
+	  break;
+	case 'C':
+	  __c = 'c';
+	  break;
+	case 'D':
+	  __c = 'd';
+	  break;
+	case 'E':
+	  __c = 'e';
+	  break;
+	case 'F':
+	  __c = 'f';
+	  break;
+	case 'G':
+	  __c = 'g';
+	  break;
+	case 'H':
+	  __c = 'h';
+	  break;
+	case 'I':
+	  __c = 'i';
+	  break;
+	case 'J':
+	  __c = 'j';
+	  break;
+	case 'K':
+	  __c = 'k';
+	  break;
+	case 'L':
+	  __c = 'l';
+	  break;
+	case 'M':
+	  __c = 'm';
+	  break;
+	case 'N':
+	  __c = 'n';
+	  break;
+	case 'O':
+	  __c = 'o';
+	  break;
+	case 'P':
+	  __c = 'p';
+	  break;
+	case 'Q':
+	  __c = 'q';
+	  break;
+	case 'R':
+	  __c = 'r';
+	  break;
+	case 'S':
+	  __c = 's';
+	  break;
+	case 'T':
+	  __c = 't';
+	  break;
+	case 'U':
+	  __c = 'u';
+	  break;
+	case 'V':
+	  __c = 'v';
+	  break;
+	case 'W':
+	  __c = 'w';
+	  break;
+	case 'X':
+	  __c = 'x';
+	  break;
+	case 'Y':
+	  __c = 'y';
+	  break;
+	case 'Z':
+	  __c = 'z';
+	  break;
+	case 'a':
+	case 'b':
+	case 'c':
+	case 'd':
+	case 'e':
+	case 'f':
+	case 'g':
+	case 'h':
+	case 'i':
+	case 'j':
+	case 'k':
+	case 'l':
+	case 'm':
+	case 'n':
+	case 'o':
+	case 'p':
+	case 'q':
+	case 'r':
+	case 's':
+	case 't':
+	case 'u':
+	case 'v':
+	case 'w':
+	case 'x':
+	case 'y':
+	case 'z':
+	  break;
+	default:
+	  __c = '\0';
+	}
+      __num = false;
+      return __c;
+    };
+
+    auto __ptr_a = __a.begin(), __end_a = __a.end();
+    auto __ptr_b = __b.begin(), __end_b = __b.end();
+    bool __num_a = false, __num_b = false;
+
+    while (true)
+      {
+	char __chr_a, __chr_b;
+	while (__ptr_a != __end_a && (__chr_a = __map(*__ptr_a, __num_a)) == 0)
+	  ++__ptr_a;
+	while (__ptr_b != __end_b && (__chr_b = __map(*__ptr_b, __num_b)) == 0)
+	  ++__ptr_b;
+	if (__ptr_a == __end_a)
+	  return __ptr_b == __end_b;
+	if (__ptr_b == __end_b)
+	  return false;
+	else if (__chr_a != __chr_b)
+	  return false; // Found non-matching characters.
+	++__ptr_a;
+	++__ptr_b;
+      }
+    return true;
+  }
+
 } // namespace __unicode
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index 5de88f955aa..91d882edaa5 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1756,6 +1756,16 @@ ftms = {
   };
 };
 
+ftms = {
+  name = text_encoding;
+  values = {
+    v = 202306;
+    cxxmin = 26;
+    hosted = yes;
+    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
+  };
+};
+
 ftms = {
   name = to_string;
   values = {
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 00bb7a8cbd1..8436822a141 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2142,6 +2142,17 @@
 #undef __glibcxx_want_saturation_arithmetic
 
 // from version.def line 1760
+#if !defined(__cpp_lib_text_encoding)
+# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
+#  define __glibcxx_text_encoding 202306L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
+#   define __cpp_lib_text_encoding 202306L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
+#undef __glibcxx_want_text_encoding
+
+// from version.def line 1770
 #if !defined(__cpp_lib_to_string)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
 #  define __glibcxx_to_string 202306L
@@ -2152,7 +2163,7 @@
 #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
 #undef __glibcxx_want_to_string
 
-// from version.def line 1770
+// from version.def line 1780
 #if !defined(__cpp_lib_generator)
 # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
 #  define __glibcxx_generator 202207L
diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
new file mode 100644
index 00000000000..df8a09c5810
--- /dev/null
+++ b/libstdc++-v3/include/std/text_encoding
@@ -0,0 +1,704 @@
+// <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/text_encoding
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TEXT_ENCODING
+#define _GLIBCXX_TEXT_ENCODING
+
+#pragma GCC system_header
+
+#include <bits/requires_hosted.h>
+
+#define __glibcxx_want_text_encoding
+#include <bits/version.h>
+
+#ifdef __cpp_lib_text_encoding
+#include <compare>
+#include <string_view>
+#include <bits/functional_hash.h> // hash
+#include <bits/ranges_util.h>     // view_interface
+#include <bits/unicode.h>         // __charset_alias_match
+#include <ext/numeric_traits.h>   // __int_traits
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  /**
+   * @brief An interface for accessing the IANA Character Sets registry.
+   * @ingroup locales
+   * @since C++23
+   */
+  struct text_encoding
+  {
+  private:
+    struct _Rep
+    {
+      using id = __INT_LEAST32_TYPE__;
+      id _M_id;
+      const char* _M_name;
+
+      friend constexpr bool
+      operator<(const _Rep& __r, id __m) noexcept
+      { return __r._M_id < __m; }
+
+      friend constexpr bool
+      operator==(const _Rep& __r, string_view __name) noexcept
+      { return __r._M_name == __name; }
+    };
+
+  public:
+    static constexpr size_t max_name_length = 63;
+
+    enum class id : _Rep::id
+    {
+      other = 1,
+      unknown = 2,
+      ASCII = 3,
+      ISOLatin1 = 4,
+      ISOLatin2 = 5,
+      ISOLatin3 = 6,
+      ISOLatin4 = 7,
+      ISOLatinCyrillic = 8,
+      ISOLatinArabic = 9,
+      ISOLatinGreek = 10,
+      ISOLatinHebrew = 11,
+      ISOLatin5 = 12,
+      ISOLatin6 = 13,
+      ISOTextComm = 14,
+      HalfWidthKatakana = 15,
+      JISEncoding = 16,
+      ShiftJIS = 17,
+      EUCPkdFmtJapanese = 18,
+      EUCFixWidJapanese = 19,
+      ISO4UnitedKingdom = 20,
+      ISO11SwedishForNames = 21,
+      ISO15Italian = 22,
+      ISO17Spanish = 23,
+      ISO21German = 24,
+      ISO60DanishNorwegian = 25,
+      ISO69French = 26,
+      ISO10646UTF1 = 27,
+      ISO646basic1983 = 28,
+      INVARIANT = 29,
+      ISO2IntlRefVersion = 30,
+      NATSSEFI = 31,
+      NATSSEFIADD = 32,
+      ISO10Swedish = 35,
+      KSC56011987 = 36,
+      ISO2022KR = 37,
+      EUCKR = 38,
+      ISO2022JP = 39,
+      ISO2022JP2 = 40,
+      ISO13JISC6220jp = 41,
+      ISO14JISC6220ro = 42,
+      ISO16Portuguese = 43,
+      ISO18Greek7Old = 44,
+      ISO19LatinGreek = 45,
+      ISO25French = 46,
+      ISO27LatinGreek1 = 47,
+      ISO5427Cyrillic = 48,
+      ISO42JISC62261978 = 49,
+      ISO47BSViewdata = 50,
+      ISO49INIS = 51,
+      ISO50INIS8 = 52,
+      ISO51INISCyrillic = 53,
+      ISO54271981 = 54,
+      ISO5428Greek = 55,
+      ISO57GB1988 = 56,
+      ISO58GB231280 = 57,
+      ISO61Norwegian2 = 58,
+      ISO70VideotexSupp1 = 59,
+      ISO84Portuguese2 = 60,
+      ISO85Spanish2 = 61,
+      ISO86Hungarian = 62,
+      ISO87JISX0208 = 63,
+      ISO88Greek7 = 64,
+      ISO89ASMO449 = 65,
+      ISO90 = 66,
+      ISO91JISC62291984a = 67,
+      ISO92JISC62991984b = 68,
+      ISO93JIS62291984badd = 69,
+      ISO94JIS62291984hand = 70,
+      ISO95JIS62291984handadd = 71,
+      ISO96JISC62291984kana = 72,
+      ISO2033 = 73,
+      ISO99NAPLPS = 74,
+      ISO102T617bit = 75,
+      ISO103T618bit = 76,
+      ISO111ECMACyrillic = 77,
+      ISO121Canadian1 = 78,
+      ISO122Canadian2 = 79,
+      ISO123CSAZ24341985gr = 80,
+      ISO88596E = 81,
+      ISO88596I = 82,
+      ISO128T101G2 = 83,
+      ISO88598E = 84,
+      ISO88598I = 85,
+      ISO139CSN369103 = 86,
+      ISO141JUSIB1002 = 87,
+      ISO143IECP271 = 88,
+      ISO146Serbian = 89,
+      ISO147Macedonian = 90,
+      ISO150 = 91,
+      ISO151Cuba = 92,
+      ISO6937Add = 93,
+      ISO153GOST1976874 = 94,
+      ISO8859Supp = 95,
+      ISO10367Box = 96,
+      ISO158Lap = 97,
+      ISO159JISX02121990 = 98,
+      ISO646Danish = 99,
+      USDK = 100,
+      DKUS = 101,
+      KSC5636 = 102,
+      Unicode11UTF7 = 103,
+      ISO2022CN = 104,
+      ISO2022CNEXT = 105,
+      UTF8 = 106,
+      ISO885913 = 109,
+      ISO885914 = 110,
+      ISO885915 = 111,
+      ISO885916 = 112,
+      GBK = 113,
+      GB18030 = 114,
+      OSDEBCDICDF0415 = 115,
+      OSDEBCDICDF03IRV = 116,
+      OSDEBCDICDF041 = 117,
+      ISO115481 = 118,
+      KZ1048 = 119,
+      UCS2 = 1000,
+      UCS4 = 1001,
+      UnicodeASCII = 1002,
+      UnicodeLatin1 = 1003,
+      UnicodeJapanese = 1004,
+      UnicodeIBM1261 = 1005,
+      UnicodeIBM1268 = 1006,
+      UnicodeIBM1276 = 1007,
+      UnicodeIBM1264 = 1008,
+      UnicodeIBM1265 = 1009,
+      Unicode11 = 1010,
+      SCSU = 1011,
+      UTF7 = 1012,
+      UTF16BE = 1013,
+      UTF16LE = 1014,
+      UTF16 = 1015,
+      CESU8 = 1016,
+      UTF32 = 1017,
+      UTF32BE = 1018,
+      UTF32LE = 1019,
+      BOCU1 = 1020,
+      UTF7IMAP = 1021,
+      Windows30Latin1 = 2000,
+      Windows31Latin1 = 2001,
+      Windows31Latin2 = 2002,
+      Windows31Latin5 = 2003,
+      HPRoman8 = 2004,
+      AdobeStandardEncoding = 2005,
+      VenturaUS = 2006,
+      VenturaInternational = 2007,
+      DECMCS = 2008,
+      PC850Multilingual = 2009,
+      PC8DanishNorwegian = 2012,
+      PC862LatinHebrew = 2013,
+      PC8Turkish = 2014,
+      IBMSymbols = 2015,
+      IBMThai = 2016,
+      HPLegal = 2017,
+      HPPiFont = 2018,
+      HPMath8 = 2019,
+      HPPSMath = 2020,
+      HPDesktop = 2021,
+      VenturaMath = 2022,
+      MicrosoftPublishing = 2023,
+      Windows31J = 2024,
+      GB2312 = 2025,
+      Big5 = 2026,
+      Macintosh = 2027,
+      IBM037 = 2028,
+      IBM038 = 2029,
+      IBM273 = 2030,
+      IBM274 = 2031,
+      IBM275 = 2032,
+      IBM277 = 2033,
+      IBM278 = 2034,
+      IBM280 = 2035,
+      IBM281 = 2036,
+      IBM284 = 2037,
+      IBM285 = 2038,
+      IBM290 = 2039,
+      IBM297 = 2040,
+      IBM420 = 2041,
+      IBM423 = 2042,
+      IBM424 = 2043,
+      PC8CodePage437 = 2011,
+      IBM500 = 2044,
+      IBM851 = 2045,
+      PCp852 = 2010,
+      IBM855 = 2046,
+      IBM857 = 2047,
+      IBM860 = 2048,
+      IBM861 = 2049,
+      IBM863 = 2050,
+      IBM864 = 2051,
+      IBM865 = 2052,
+      IBM868 = 2053,
+      IBM869 = 2054,
+      IBM870 = 2055,
+      IBM871 = 2056,
+      IBM880 = 2057,
+      IBM891 = 2058,
+      IBM903 = 2059,
+      IBM904 = 2060,
+      IBM905 = 2061,
+      IBM918 = 2062,
+      IBM1026 = 2063,
+      IBMEBCDICATDE = 2064,
+      EBCDICATDEA = 2065,
+      EBCDICCAFR = 2066,
+      EBCDICDKNO = 2067,
+      EBCDICDKNOA = 2068,
+      EBCDICFISE = 2069,
+      EBCDICFISEA = 2070,
+      EBCDICFR = 2071,
+      EBCDICIT = 2072,
+      EBCDICPT = 2073,
+      EBCDICES = 2074,
+      EBCDICESA = 2075,
+      EBCDICESS = 2076,
+      EBCDICUK = 2077,
+      EBCDICUS = 2078,
+      Unknown8BiT = 2079,
+      Mnemonic = 2080,
+      Mnem = 2081,
+      VISCII = 2082,
+      VIQR = 2083,
+      KOI8R = 2084,
+      HZGB2312 = 2085,
+      IBM866 = 2086,
+      PC775Baltic = 2087,
+      KOI8U = 2088,
+      IBM00858 = 2089,
+      IBM00924 = 2090,
+      IBM01140 = 2091,
+      IBM01141 = 2092,
+      IBM01142 = 2093,
+      IBM01143 = 2094,
+      IBM01144 = 2095,
+      IBM01145 = 2096,
+      IBM01146 = 2097,
+      IBM01147 = 2098,
+      IBM01148 = 2099,
+      IBM01149 = 2100,
+      Big5HKSCS = 2101,
+      IBM1047 = 2102,
+      PTCP154 = 2103,
+      Amiga1251 = 2104,
+      KOI7switched = 2105,
+      BRF = 2106,
+      TSCII = 2107,
+      CP51932 = 2108,
+      windows874 = 2109,
+      windows1250 = 2250,
+      windows1251 = 2251,
+      windows1252 = 2252,
+      windows1253 = 2253,
+      windows1254 = 2254,
+      windows1255 = 2255,
+      windows1256 = 2256,
+      windows1257 = 2257,
+      windows1258 = 2258,
+      TIS620 = 2259,
+      CP50220 = 2260
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+
+    constexpr explicit
+    text_encoding(string_view __enc) noexcept
+    : _M_rep(_S_find_name(__enc))
+    {
+      __enc.copy(_M_name, max_name_length);
+    }
+
+    // @pre i has the value of one of the enumerators of id.
+    constexpr
+    text_encoding(id __i) noexcept
+    : _M_rep(_S_find_id(__i))
+    {
+      if (string_view __name(_M_rep->_M_name); !__name.empty())
+	__name.copy(_M_name, max_name_length);
+    }
+
+    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
+
+    constexpr const char* name() const noexcept { return _M_name; }
+
+    struct aliases_view : ranges::view_interface<aliases_view>
+    {
+    private:
+      class _Iterator;
+      struct _Sentinel { };
+
+    public:
+      constexpr _Iterator begin() const noexcept { return _Iterator(_M_begin); }
+      constexpr _Sentinel end() const noexcept { return _Sentinel{}; }
+
+    private:
+      friend struct text_encoding;
+
+      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
+
+      class _Iterator
+      {
+      public:
+	using value_type = const char*;
+	using reference = const char*;
+	using difference_type = int;
+
+	constexpr _Iterator() = default;
+	constexpr value_type operator*() const;
+	constexpr _Iterator& operator++();
+	constexpr _Iterator& operator--();
+	constexpr _Iterator operator++(int);
+	constexpr _Iterator operator--(int);
+	constexpr value_type operator[](difference_type) const;
+	constexpr _Iterator& operator+=(difference_type);
+	constexpr _Iterator& operator-=(difference_type);
+	constexpr difference_type operator-(const _Iterator&) const;
+	constexpr bool operator==(const _Iterator&) const = default;
+	constexpr bool operator==(_Sentinel) const noexcept;
+	constexpr strong_ordering operator<=>(const _Iterator&) const;
+
+	friend _Iterator
+	operator+(_Iterator __i, difference_type __n)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator+(difference_type __n, _Iterator __i)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator-(_Iterator __i, difference_type __n)
+	{
+	  __i -= __n;
+	  return __i;
+	}
+
+      private:
+	friend class text_encoding;
+
+	constexpr explicit
+	_Iterator(const _Rep* __r) noexcept
+	: _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
+	{ }
+
+	constexpr bool _M_dereferenceable() const noexcept;
+	static constexpr difference_type _S_neg(difference_type) noexcept;
+
+	const _Rep* _M_rep = nullptr;
+	_Rep::id _M_id = 0;
+      };
+
+      const _Rep* _M_begin = nullptr;
+    };
+
+    constexpr aliases_view
+    aliases() const noexcept
+    {
+      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __a,
+	       const text_encoding& __b) noexcept
+    {
+      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
+	return _S_comp(__a._M_name, __b._M_name);
+      else
+	return __a.mib() == __b.mib();
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __encoding, id __i) noexcept
+    { return __encoding.mib() == __i; }
+
+#if __CHAR_BIT__ == 8
+    static consteval text_encoding
+    literal() noexcept
+    {
+#ifdef __GNUC_EXECUTION_CHARSET_NAME
+      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
+#elif defined __clang_literal_encoding__
+      return text_encoding(__clang_literal_encoding__);
+#else
+      return text_encoding();
+#endif
+    }
+
+    static text_encoding
+    environment();
+
+    template<id _Id>
+      static bool
+      environment_is()
+      { return text_encoding(_Id)._M_is_environment(); }
+#else
+    static text_encoding literal() = delete;
+    static text_encoding environment() = delete;
+    template<id> static bool environment_is() = delete;
+#endif
+
+  private:
+    const _Rep* _M_rep = _S_reps + 1; // id::unknown
+    char _M_name[max_name_length + 1] = {0};
+
+    bool
+    _M_is_environment() const;
+
+    static inline constexpr _Rep _S_reps[] = {
+      { 1, "" }, { 2, "" },
+#define _GLIBCXX_GET_ENCODING_DATA
+#include <bits/text_encoding-data.h>
+#ifdef _GLIBCXX_GET_ENCODING_DATA
+# error "Invalid text_encoding data"
+#endif
+      { 9999, nullptr }, // sentinel
+    };
+
+    static constexpr bool
+    _S_comp(string_view __a, string_view __b)
+    { return __unicode::__charset_alias_match(__a, __b); }
+
+    static constexpr const _Rep*
+    _S_find_name(string_view __name) noexcept
+    {
+#ifdef _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET
+      // Optimize the common UTF-8 case to avoid a linear search through all
+      // strings in the table using the _S_comp function.
+      if (__name == "UTF-8")
+	return _S_reps + 2 + _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET;
+#endif
+
+      // The first two array elements (other and unknown) don't have names.
+      // The last element is a sentinel that can never match anything.
+      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
+      for (auto __r = __first; __r != __end; ++__r)
+	if (_S_comp(__r->_M_name, __name))
+	  {
+	    // Might have matched an alias. Find the first entry for this ID.
+	    const auto __id = __r->_M_id;
+	    while (__r[-1]._M_id == __id)
+	      --__r;
+	    return __r;
+	  }
+      return _S_reps; // id::other
+    }
+
+    static constexpr const _Rep*
+    _S_find_id(id __id) noexcept
+    {
+      const auto __i = (_Rep::id)__id;
+      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
+      if (__r->_M_id == __i) [[likely]]
+	return __r;
+      else
+	{
+	  // Preconditions: i has the value of one of the enumerators of id.
+	  __glibcxx_assert(__r->_M_id == __i);
+	  return _S_reps + 1; // id::unknown
+	}
+    }
+  };
+
+  template<>
+    struct hash<text_encoding>
+    {
+      size_t
+      operator()(const text_encoding& __enc) const noexcept
+      { return std::hash<text_encoding::id>()(__enc.mib()); }
+    };
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator*() const
+  -> value_type
+  {
+    if (_M_dereferenceable()) [[likely]]
+      return _M_rep->_M_name;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	return "";
+      }
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++()
+  -> _Iterator&
+  {
+    if (_M_dereferenceable()) [[likely]]
+      ++_M_rep;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--()
+  -> _Iterator&
+  {
+    const bool __decrementable = _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
+    if (__decrementable) [[likely]]
+      --_M_rep;
+    else
+      {
+	__glibcxx_assert(__decrementable);
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    ++*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    --*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator[](difference_type __n) const
+  -> value_type
+  { return *(*this + __n); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator+=(difference_type __n)
+  -> _Iterator&
+  {
+    if (_M_rep != nullptr)
+      {
+	if ((__n > 0 && __n < (std::end(_S_reps) - _M_rep))
+	      || (__n < 0 && __n > (_S_reps - _M_rep)))
+	  {
+	    if (_M_rep[__n]._M_id == _M_id)
+	      _M_rep += __n;
+	    else
+	      *this = _Iterator{};
+	  }
+	else if (__n != 0)
+	  *this = _Iterator{};
+      }
+    __glibcxx_assert(_M_rep != nullptr);
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-=(difference_type __n)
+  -> _Iterator&
+  { return operator+=(_S_neg(__n)); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-(const _Iterator& __i) const noexcept
+  -> difference_type
+  {
+    if (_M_id == __i._M_id)
+      return _M_rep - __i._M_rep;
+    __glibcxx_assert(_M_id == __i._M_id);
+    return __gnu_cxx::__int_traits<difference_type>::__max;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::operator==(_Sentinel) const noexcept
+  { return !_M_dereferenceable(); }
+
+  constexpr strong_ordering
+  text_encoding::aliases_view::
+  _Iterator::operator<=>(const _Iterator& __i) const
+  {
+    __glibcxx_assert(_M_id == __i._M_id);
+    return _M_rep <=> __i._M_rep;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::_M_dereferenceable() const noexcept
+  { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::_S_neg(difference_type __n) noexcept
+  -> difference_type
+  {
+    using _Traits = __gnu_cxx::__int_traits<difference_type>;
+    if (__n == _Traits::__min) [[unlikely]]
+      return _Traits::__max;
+    return -__n;
+  }
+
+namespace ranges
+{
+  // Opt-in to borrowed_range concept
+  template<>
+    inline constexpr bool
+    enable_borrowed_range<std::text_encoding::aliases_view> = true;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cpp_lib_text_encoding
+#endif // _GLIBCXX_TEXT_ENCODING
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 032a7aa58a2..a6c2ed4599f 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
         typename = strip_versioned_namespace(self._typename)
         return "{}<{}, {}>".format(typename, value_type, value)
 
+class StdTextEncodingPrinter(printer_base):
+    """Print a std::text_encoding."""
+
+    def __init__(self, typename, val):
+        self._val = val
+        self._typename = typename
+
+    def to_string(self):
+        rep = self._val['_M_rep'].dereference()
+        if rep['_M_id'] == 1:
+            return self._val['_M_name']
+        if rep['_M_id'] == 2:
+            return 'unknown'
+        return rep['_M_name']
+
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
 class RxPrinter(object):
@@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
 
     libstdcxx_printer.add_version('std::', 'integral_constant',
                                   StdIntegralConstantPrinter)
+    libstdcxx_printer.add_version('std::', 'text_encoding',
+                                  StdTextEncodingPrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
new file mode 100755
index 00000000000..2d6f3e4077a
--- /dev/null
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+#
+# Script to generate tables for libstdc++ std::text_encoding.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+#
+# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
+# the latest:
+# https://www.iana.org/assignments/character-sets/character-sets-1.csv
+# Then run this script and save the output to
+# include/bits/text_encoding-data.h
+
+import sys
+import csv
+
+if len(sys.argv) != 2:
+    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
+    sys.exit(1)
+
+print("// Generated by gen_text_encoding_data.py, do not edit.\n")
+print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
+print('# error "This is not a public header, do not include it directly"')
+print("#endif\n")
+
+
+charsets = {}
+with open(sys.argv[1], newline='') as f:
+    reader = csv.reader(f)
+    next(reader) # skip header row
+    for row in reader:
+        mib = int(row[2])
+        if mib in charsets:
+            raise ValueError("Multiple rows for mibEnum={}".format(mib))
+        name = row[1]
+        aliases = row[5].split()
+        # Ensure primary name comes first
+        if name in aliases:
+            aliases.remove(name)
+        charsets[mib] = [name] + aliases
+
+# Remove "NATS-DANO" and "NATS-DANO-ADD"
+charsets.pop(33, None)
+charsets.pop(34, None)
+
+count = 0
+for mib in sorted(charsets.keys()):
+    names = charsets[mib]
+    if names[0] == "UTF-8":
+        print("#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET {}".format(count))
+    for name in names:
+        print('  {{ {:4}, "{}" }},'.format(mib, name))
+    count += len(names)
+
+# <text_encoding> gives an error if this macro is left defined.
+# Do this last, so that the generated output is not usable unless we reach here.
+print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
index 8e9ec78fe0d..201999a3577 100644
--- a/libstdc++-v3/src/c++26/Makefile.am
+++ b/libstdc++-v3/src/c++26/Makefile.am
@@ -35,7 +35,7 @@ else
 inst_sources =
 endif
 
-sources = debugging.cc
+sources = debugging.cc text_encoding.cc
 
 vpath % $(top_srcdir)/src/c++26
 
diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
new file mode 100644
index 00000000000..9a7df07db29
--- /dev/null
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -0,0 +1,91 @@
+// Definitions for <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <text_encoding>
+#include <locale>
+
+#ifdef _GLIBCXX_USE_NL_LANGINFO_L
+#include <locale.h>
+#include <langinfo.h>
+
+#if __CHAR_BIT__ == 8
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+text_encoding
+__locale_encoding(const char* name)
+{
+  text_encoding enc;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view s(codeset);
+	  if (s.size() < text_encoding::max_name_length)
+	    enc = text_encoding(s);
+	}
+      ::freelocale(loc);
+    }
+  return enc;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+std::text_encoding
+std::text_encoding::environment()
+{
+  return std::__locale_encoding("");
+}
+
+bool
+std::text_encoding::_M_is_environment() const
+{
+  bool matched = false;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, "", (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view sv(codeset);
+	  for (auto alias : aliases())
+	    if (__unicode::__charset_alias_match(alias, sv))
+	      {
+		matched = true;
+		break;
+	      }
+	}
+      ::freelocale(loc);
+    }
+  return matched;
+}
+
+std::text_encoding
+std::locale::encoding() const
+{
+  return std::__locale_encoding(name().c_str());
+}
+#endif // CHAR_BIT == 8
+
+#endif // _GLIBCXX_USE_NL_LANGINFO_L
diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
new file mode 100644
index 00000000000..f6272ae998b
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+#include <format>
+
+using std::__unicode::__charset_alias_match;
+static_assert( __charset_alias_match("UTF-8", "utf8") == true );
+static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
+static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
+static_assert( __charset_alias_match("UTF-8", "ut8") == false );
+
+static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
+
+static_assert( __charset_alias_match("", "") == true );
+static_assert( __charset_alias_match("", ".") == true );
+static_assert( __charset_alias_match("--", "...") == true );
+static_assert( __charset_alias_match("--a", "a...") == true );
+static_assert( __charset_alias_match("--a010", "a..10.") == true );
+static_assert( __charset_alias_match("--a010", "a..1.0") == false );
+static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
new file mode 100644
index 00000000000..2d84d3bb394
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
@@ -0,0 +1,106 @@
+// { dg-do run { target c++26 } }
+
+#include <text_encoding>
+#include <string_view>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+constexpr void
+test_default_construct()
+{
+  std::text_encoding e0;
+  VERIFY( e0.mib() == std::text_encoding::unknown );
+  VERIFY( e0.name()[0] == '\0' ); // P2862R1 name() should never return null
+  VERIFY( e0.aliases().empty() );
+}
+
+constexpr void
+test_construct_by_name()
+{
+  std::string_view s;
+  std::text_encoding e0(s);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == s );
+  VERIFY( e0.aliases().empty() );
+
+  s = "not a real encoding";
+  std::text_encoding e1(s);
+  VERIFY( e1.mib() == std::text_encoding::other );
+  VERIFY( e1.name() == s );
+  VERIFY( e1.aliases().empty() );
+
+  VERIFY( e1 != e0 );
+  VERIFY( e1 == e0.mib() );
+
+  s = "utf8";
+  std::text_encoding e2(s);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == s );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == "UTF-8"sv );
+
+  s = "latin1";
+  std::text_encoding e3(s);
+  VERIFY( e3.mib() == std::text_encoding::ISOLatin1 );
+  VERIFY( e3.name() == s );
+  VERIFY( ! e3.aliases().empty() );
+  VERIFY( e3.aliases().front() == "ISO_8859-1:1987"sv ); // primary name
+}
+
+constexpr void
+test_construct_by_id()
+{
+  std::text_encoding e0(std::text_encoding::other);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == ""sv );
+  VERIFY( e0.aliases().empty() );
+
+  std::text_encoding e1(std::text_encoding::unknown);
+  VERIFY( e1.mib() == std::text_encoding::unknown );
+  VERIFY( e1.name() == ""sv );
+  VERIFY( e1.aliases().empty() );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == "UTF-8"sv );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == std::string_view(e2.name()) );
+  bool found = false;
+  for (auto alias : e2.aliases())
+    if (alias == "csUTF8"sv)
+    {
+      found = true;
+      break;
+    }
+  VERIFY( found );
+}
+
+constexpr void
+test_copy_construct()
+{
+  std::text_encoding e0;
+  std::text_encoding e1 = e0;
+  VERIFY( e1 == e0 );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  auto e3 = e2;
+  VERIFY( e3 == e2 );
+
+  e1 = e3;
+  VERIFY( e1 == e2 );
+}
+
+int main()
+{
+  auto run_tests = [] {
+    test_default_construct();
+    test_construct_by_name();
+    test_construct_by_id();
+    test_copy_construct();
+    return true;
+  };
+
+  run_tests();
+  static_assert( run_tests() );
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
new file mode 100644
index 00000000000..d62d93dcda4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <text_encoding>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <text_encoding>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
+#endif
+
+#undef __cpp_lib_expected
+#include <version>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <version>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <version>"
+#endif
+
+#include <concepts>
+#include <ranges>
+static_assert( std::is_trivially_copyable_v<std::text_encoding> );
+
+using aliases_view = std::text_encoding::aliases_view;
+static_assert( std::copyable<aliases_view> );
+static_assert( std::ranges::view<aliases_view> );
+static_assert( std::ranges::random_access_range<aliases_view> );
+static_assert( std::ranges::borrowed_range<aliases_view> );
+static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
+			    const char*> );
+static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
+			    const char*> );
-- 
2.43.0


^ permalink raw reply	[flat|nested] 9+ messages in thread
* [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-13 12:44 ` [PATCH v2] " Jonathan Wakely
@ 2024-01-15 20:45   ` Jonathan Wakely
  2024-01-15 22:24     ` Ulrich Drepper
  2024-01-16  0:09     ` Patrick Palka
  0 siblings, 2 replies; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-15 20:45 UTC (permalink / raw)
  To: libstdc++, gcc-patches

I think I'm happy with this now. It has tests for all the new functions,
and the performance of the charset alias match algorithm is improved by
reusing part of <charconv>.

Tested x86_64-linux.

-- >8 --

This is another C++26 change, approved in Varna 2022. We require a new
static array of data that is extracted from the IANA Character Sets
database. A new Python script to generate a header from the IANA CSV
file is added.

libstdc++-v3/ChangeLog:

	PR libstdc++/113318
	* acinclude.m4 (GLIBCXX_CONFIGURE): Add c++26 directory.
	(GLIBCXX_CHECK_TEXT_ENCODING): Define.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
	* include/Makefile.am: Add new headers.
	* include/Makefile.in: Regenerate.
	* include/bits/locale_classes.h (locale::encoding): Declare new
	member function.
	* include/bits/unicode.h (__charset_alias_match): New function.
	* include/bits/text_encoding-data.h: New file.
	* include/bits/version.def (text_encoding): Define.
	* include/bits/version.h: Regenerate.
	* include/std/text_encoding: New file.
	* src/Makefile.am: Add new subdirectory.
	* src/Makefile.in: Regenerate.
	* src/c++26/Makefile.am: New file.
	* src/c++26/Makefile.in: New file.
	* src/c++26/text_encoding.cc: New file.
	* src/experimental/Makefile.am: Include c++26 convenience
	library.
	* src/experimental/Makefile.in: Regenerate.
	* python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
	printer.
	* scripts/gen_text_encoding_data.py: New file.
	* testsuite/22_locale/locale/encoding.cc: New test.
	* testsuite/ext/unicode/charset_alias_match.cc: New test.
	* testsuite/std/text_encoding/cons.cc: New test.
	* testsuite/std/text_encoding/members.cc: New test.
	* testsuite/std/text_encoding/requirements.cc: New test.
---
 libstdc++-v3/acinclude.m4                     |  30 +-
 libstdc++-v3/config.h.in                      |   3 +
 libstdc++-v3/configure                        |  70 +-
 libstdc++-v3/configure.ac                     |   3 +
 libstdc++-v3/include/Makefile.am              |   2 +
 libstdc++-v3/include/Makefile.in              |   2 +
 libstdc++-v3/include/bits/locale_classes.h    |  14 +
 .../include/bits/text_encoding-data.h         | 902 ++++++++++++++++++
 libstdc++-v3/include/bits/unicode.h           |  53 +-
 libstdc++-v3/include/bits/version.def         |  10 +
 libstdc++-v3/include/bits/version.h           |  13 +-
 libstdc++-v3/include/std/text_encoding        | 704 ++++++++++++++
 libstdc++-v3/python/libstdcxx/v6/printers.py  |  17 +
 .../scripts/gen_text_encoding_data.py         |  70 ++
 libstdc++-v3/src/Makefile.am                  |   3 +-
 libstdc++-v3/src/Makefile.in                  |   7 +-
 libstdc++-v3/src/c++26/Makefile.am            | 109 +++
 libstdc++-v3/src/c++26/Makefile.in            | 747 +++++++++++++++
 libstdc++-v3/src/c++26/text_encoding.cc       |  91 ++
 libstdc++-v3/src/experimental/Makefile.am     |   2 +
 libstdc++-v3/src/experimental/Makefile.in     |   2 +
 .../testsuite/22_locale/locale/encoding.cc    |  36 +
 .../ext/unicode/charset_alias_match.cc        |  18 +
 .../testsuite/std/text_encoding/cons.cc       | 113 +++
 .../testsuite/std/text_encoding/members.cc    |  41 +
 .../std/text_encoding/requirements.cc         |  31 +
 26 files changed, 3083 insertions(+), 10 deletions(-)
 create mode 100644 libstdc++-v3/include/bits/text_encoding-data.h
 create mode 100644 libstdc++-v3/include/std/text_encoding
 create mode 100755 libstdc++-v3/scripts/gen_text_encoding_data.py
 create mode 100644 libstdc++-v3/src/c++26/Makefile.am
 create mode 100644 libstdc++-v3/src/c++26/Makefile.in
 create mode 100644 libstdc++-v3/src/c++26/text_encoding.cc
 create mode 100644 libstdc++-v3/testsuite/22_locale/locale/encoding.cc
 create mode 100644 libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/cons.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/members.cc
 create mode 100644 libstdc++-v3/testsuite/std/text_encoding/requirements.cc

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index e7cbf0fcf96..f9ba7ef744b 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -49,7 +49,7 @@ AC_DEFUN([GLIBCXX_CONFIGURE], [
   # Keep these sync'd with the list in Makefile.am.  The first provides an
   # expandable list at autoconf time; the second provides an expandable list
   # (i.e., shell variable) at configure time.
-  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
+  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/c++26 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
   SUBDIRS='glibcxx_SUBDIRS'
 
   # These need to be absolute paths, yet at the same time need to
@@ -5821,6 +5821,34 @@ AC_LANG_SAVE
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check whether the dependencies for std::text_encoding are available.
+dnl
+dnl Defines:
+dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
+AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
+  AC_TRY_COMPILE([
+  #include <locale.h>
+  #include <langinfo.h>
+  ],[
+    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
+    const char* enc = nl_langinfo_l(CODESET, loc);
+    freelocale(loc);
+  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
+  AC_MSG_RESULT($ac_nl_langinfo_l)
+  if test "$ac_nl_langinfo_l" = yes; then
+    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
+      [Define if nl_langinfo_l should be used for std::text_encoding.])
+  fi
+
+  AC_LANG_RESTORE
+])
+
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
 m4_include([../config/tls.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index c8b36333019..c68cac4f345 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
 # For __basic_file::native_handle()
 GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
 
+# For std::text_encoding
+GLIBCXX_CHECK_TEXT_ENCODING
+
 # Define documentation rules conditionally.
 
 # See if makeinfo has been installed and is modern enough
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index c6d6a24eb9e..64152351ed0 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -104,6 +104,7 @@ std_headers = \
 	${std_srcdir}/streambuf \
 	${std_srcdir}/string \
 	${std_srcdir}/system_error \
+	${std_srcdir}/text_encoding \
 	${std_srcdir}/thread \
 	${std_srcdir}/unordered_map \
 	${std_srcdir}/unordered_set \
@@ -159,6 +160,7 @@ bits_freestanding = \
 	${bits_srcdir}/stl_raw_storage_iter.h \
 	${bits_srcdir}/stl_relops.h \
 	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/text_encoding-data.h \
 	${bits_srcdir}/version.h \
 	${bits_srcdir}/string_view.tcc \
 	${bits_srcdir}/unicode.h \
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 621f2a29f50..a2e94217006 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -40,6 +40,10 @@
 #include <string>
 #include <ext/atomicity.h>
 
+#ifdef __glibcxx_text_encoding
+#include <text_encoding>
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string
     name() const;
 
+#ifdef __glibcxx_text_encoding
+# if __CHAR_BIT__ == 8
+    text_encoding
+    encoding() const;
+# else
+    text_encoding
+    encoding() const = delete;
+# endif
+#endif
+
     /**
      *  @brief  Locale equality.
      *
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
new file mode 100644
index 00000000000..7ac2e9dc3d9
--- /dev/null
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -0,0 +1,902 @@
+// Generated by gen_text_encoding_data.py, do not edit.
+
+#ifndef _GLIBCXX_GET_ENCODING_DATA
+# error "This is not a public header, do not include it directly"
+#endif
+
+  {    3, "US-ASCII" },
+  {    3, "iso-ir-6" },
+  {    3, "ANSI_X3.4-1968" },
+  {    3, "ANSI_X3.4-1986" },
+  {    3, "ISO_646.irv:1991" },
+  {    3, "ISO646-US" },
+  {    3, "us" },
+  {    3, "IBM367" },
+  {    3, "cp367" },
+  {    3, "csASCII" },
+  {    4, "ISO_8859-1:1987" },
+  {    4, "iso-ir-100" },
+  {    4, "ISO_8859-1" },
+  {    4, "ISO-8859-1" },
+  {    4, "latin1" },
+  {    4, "l1" },
+  {    4, "IBM819" },
+  {    4, "CP819" },
+  {    4, "csISOLatin1" },
+  {    5, "ISO_8859-2:1987" },
+  {    5, "iso-ir-101" },
+  {    5, "ISO_8859-2" },
+  {    5, "ISO-8859-2" },
+  {    5, "latin2" },
+  {    5, "l2" },
+  {    5, "csISOLatin2" },
+  {    6, "ISO_8859-3:1988" },
+  {    6, "iso-ir-109" },
+  {    6, "ISO_8859-3" },
+  {    6, "ISO-8859-3" },
+  {    6, "latin3" },
+  {    6, "l3" },
+  {    6, "csISOLatin3" },
+  {    7, "ISO_8859-4:1988" },
+  {    7, "iso-ir-110" },
+  {    7, "ISO_8859-4" },
+  {    7, "ISO-8859-4" },
+  {    7, "latin4" },
+  {    7, "l4" },
+  {    7, "csISOLatin4" },
+  {    8, "ISO_8859-5:1988" },
+  {    8, "iso-ir-144" },
+  {    8, "ISO_8859-5" },
+  {    8, "ISO-8859-5" },
+  {    8, "cyrillic" },
+  {    8, "csISOLatinCyrillic" },
+  {    9, "ISO_8859-6:1987" },
+  {    9, "iso-ir-127" },
+  {    9, "ISO_8859-6" },
+  {    9, "ISO-8859-6" },
+  {    9, "ECMA-114" },
+  {    9, "ASMO-708" },
+  {    9, "arabic" },
+  {    9, "csISOLatinArabic" },
+  {   10, "ISO_8859-7:1987" },
+  {   10, "iso-ir-126" },
+  {   10, "ISO_8859-7" },
+  {   10, "ISO-8859-7" },
+  {   10, "ELOT_928" },
+  {   10, "ECMA-118" },
+  {   10, "greek" },
+  {   10, "greek8" },
+  {   10, "csISOLatinGreek" },
+  {   11, "ISO_8859-8:1988" },
+  {   11, "iso-ir-138" },
+  {   11, "ISO_8859-8" },
+  {   11, "ISO-8859-8" },
+  {   11, "hebrew" },
+  {   11, "csISOLatinHebrew" },
+  {   12, "ISO_8859-9:1989" },
+  {   12, "iso-ir-148" },
+  {   12, "ISO_8859-9" },
+  {   12, "ISO-8859-9" },
+  {   12, "latin5" },
+  {   12, "l5" },
+  {   12, "csISOLatin5" },
+  {   13, "ISO-8859-10" },
+  {   13, "iso-ir-157" },
+  {   13, "l6" },
+  {   13, "ISO_8859-10:1992" },
+  {   13, "csISOLatin6" },
+  {   13, "latin6" },
+  {   14, "ISO_6937-2-add" },
+  {   14, "iso-ir-142" },
+  {   14, "csISOTextComm" },
+  {   15, "JIS_X0201" },
+  {   15, "X0201" },
+  {   15, "csHalfWidthKatakana" },
+  {   16, "JIS_Encoding" },
+  {   16, "csJISEncoding" },
+  {   17, "Shift_JIS" },
+  {   17, "MS_Kanji" },
+  {   17, "csShiftJIS" },
+  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
+  {   18, "csEUCPkdFmtJapanese" },
+  {   18, "EUC-JP" },
+  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
+  {   19, "csEUCFixWidJapanese" },
+  {   20, "BS_4730" },
+  {   20, "iso-ir-4" },
+  {   20, "ISO646-GB" },
+  {   20, "gb" },
+  {   20, "uk" },
+  {   20, "csISO4UnitedKingdom" },
+  {   21, "SEN_850200_C" },
+  {   21, "iso-ir-11" },
+  {   21, "ISO646-SE2" },
+  {   21, "se2" },
+  {   21, "csISO11SwedishForNames" },
+  {   22, "IT" },
+  {   22, "iso-ir-15" },
+  {   22, "ISO646-IT" },
+  {   22, "csISO15Italian" },
+  {   23, "ES" },
+  {   23, "iso-ir-17" },
+  {   23, "ISO646-ES" },
+  {   23, "csISO17Spanish" },
+  {   24, "DIN_66003" },
+  {   24, "iso-ir-21" },
+  {   24, "de" },
+  {   24, "ISO646-DE" },
+  {   24, "csISO21German" },
+  {   25, "NS_4551-1" },
+  {   25, "iso-ir-60" },
+  {   25, "ISO646-NO" },
+  {   25, "no" },
+  {   25, "csISO60DanishNorwegian" },
+  {   25, "csISO60Norwegian1" },
+  {   26, "NF_Z_62-010" },
+  {   26, "iso-ir-69" },
+  {   26, "ISO646-FR" },
+  {   26, "fr" },
+  {   26, "csISO69French" },
+  {   27, "ISO-10646-UTF-1" },
+  {   27, "csISO10646UTF1" },
+  {   28, "ISO_646.basic:1983" },
+  {   28, "ref" },
+  {   28, "csISO646basic1983" },
+  {   29, "INVARIANT" },
+  {   29, "csINVARIANT" },
+  {   30, "ISO_646.irv:1983" },
+  {   30, "iso-ir-2" },
+  {   30, "irv" },
+  {   30, "csISO2IntlRefVersion" },
+  {   31, "NATS-SEFI" },
+  {   31, "iso-ir-8-1" },
+  {   31, "csNATSSEFI" },
+  {   32, "NATS-SEFI-ADD" },
+  {   32, "iso-ir-8-2" },
+  {   32, "csNATSSEFIADD" },
+  {   35, "SEN_850200_B" },
+  {   35, "iso-ir-10" },
+  {   35, "FI" },
+  {   35, "ISO646-FI" },
+  {   35, "ISO646-SE" },
+  {   35, "se" },
+  {   35, "csISO10Swedish" },
+  {   36, "KS_C_5601-1987" },
+  {   36, "iso-ir-149" },
+  {   36, "KS_C_5601-1989" },
+  {   36, "KSC_5601" },
+  {   36, "korean" },
+  {   36, "csKSC56011987" },
+  {   37, "ISO-2022-KR" },
+  {   37, "csISO2022KR" },
+  {   38, "EUC-KR" },
+  {   38, "csEUCKR" },
+  {   39, "ISO-2022-JP" },
+  {   39, "csISO2022JP" },
+  {   40, "ISO-2022-JP-2" },
+  {   40, "csISO2022JP2" },
+  {   41, "JIS_C6220-1969-jp" },
+  {   41, "JIS_C6220-1969" },
+  {   41, "iso-ir-13" },
+  {   41, "katakana" },
+  {   41, "x0201-7" },
+  {   41, "csISO13JISC6220jp" },
+  {   42, "JIS_C6220-1969-ro" },
+  {   42, "iso-ir-14" },
+  {   42, "jp" },
+  {   42, "ISO646-JP" },
+  {   42, "csISO14JISC6220ro" },
+  {   43, "PT" },
+  {   43, "iso-ir-16" },
+  {   43, "ISO646-PT" },
+  {   43, "csISO16Portuguese" },
+  {   44, "greek7-old" },
+  {   44, "iso-ir-18" },
+  {   44, "csISO18Greek7Old" },
+  {   45, "latin-greek" },
+  {   45, "iso-ir-19" },
+  {   45, "csISO19LatinGreek" },
+  {   46, "NF_Z_62-010_(1973)" },
+  {   46, "iso-ir-25" },
+  {   46, "ISO646-FR1" },
+  {   46, "csISO25French" },
+  {   47, "Latin-greek-1" },
+  {   47, "iso-ir-27" },
+  {   47, "csISO27LatinGreek1" },
+  {   48, "ISO_5427" },
+  {   48, "iso-ir-37" },
+  {   48, "csISO5427Cyrillic" },
+  {   49, "JIS_C6226-1978" },
+  {   49, "iso-ir-42" },
+  {   49, "csISO42JISC62261978" },
+  {   50, "BS_viewdata" },
+  {   50, "iso-ir-47" },
+  {   50, "csISO47BSViewdata" },
+  {   51, "INIS" },
+  {   51, "iso-ir-49" },
+  {   51, "csISO49INIS" },
+  {   52, "INIS-8" },
+  {   52, "iso-ir-50" },
+  {   52, "csISO50INIS8" },
+  {   53, "INIS-cyrillic" },
+  {   53, "iso-ir-51" },
+  {   53, "csISO51INISCyrillic" },
+  {   54, "ISO_5427:1981" },
+  {   54, "iso-ir-54" },
+  {   54, "ISO5427Cyrillic1981" },
+  {   54, "csISO54271981" },
+  {   55, "ISO_5428:1980" },
+  {   55, "iso-ir-55" },
+  {   55, "csISO5428Greek" },
+  {   56, "GB_1988-80" },
+  {   56, "iso-ir-57" },
+  {   56, "cn" },
+  {   56, "ISO646-CN" },
+  {   56, "csISO57GB1988" },
+  {   57, "GB_2312-80" },
+  {   57, "iso-ir-58" },
+  {   57, "chinese" },
+  {   57, "csISO58GB231280" },
+  {   58, "NS_4551-2" },
+  {   58, "ISO646-NO2" },
+  {   58, "iso-ir-61" },
+  {   58, "no2" },
+  {   58, "csISO61Norwegian2" },
+  {   59, "videotex-suppl" },
+  {   59, "iso-ir-70" },
+  {   59, "csISO70VideotexSupp1" },
+  {   60, "PT2" },
+  {   60, "iso-ir-84" },
+  {   60, "ISO646-PT2" },
+  {   60, "csISO84Portuguese2" },
+  {   61, "ES2" },
+  {   61, "iso-ir-85" },
+  {   61, "ISO646-ES2" },
+  {   61, "csISO85Spanish2" },
+  {   62, "MSZ_7795.3" },
+  {   62, "iso-ir-86" },
+  {   62, "ISO646-HU" },
+  {   62, "hu" },
+  {   62, "csISO86Hungarian" },
+  {   63, "JIS_C6226-1983" },
+  {   63, "iso-ir-87" },
+  {   63, "x0208" },
+  {   63, "JIS_X0208-1983" },
+  {   63, "csISO87JISX0208" },
+  {   64, "greek7" },
+  {   64, "iso-ir-88" },
+  {   64, "csISO88Greek7" },
+  {   65, "ASMO_449" },
+  {   65, "ISO_9036" },
+  {   65, "arabic7" },
+  {   65, "iso-ir-89" },
+  {   65, "csISO89ASMO449" },
+  {   66, "iso-ir-90" },
+  {   66, "csISO90" },
+  {   67, "JIS_C6229-1984-a" },
+  {   67, "iso-ir-91" },
+  {   67, "jp-ocr-a" },
+  {   67, "csISO91JISC62291984a" },
+  {   68, "JIS_C6229-1984-b" },
+  {   68, "iso-ir-92" },
+  {   68, "ISO646-JP-OCR-B" },
+  {   68, "jp-ocr-b" },
+  {   68, "csISO92JISC62991984b" },
+  {   69, "JIS_C6229-1984-b-add" },
+  {   69, "iso-ir-93" },
+  {   69, "jp-ocr-b-add" },
+  {   69, "csISO93JIS62291984badd" },
+  {   70, "JIS_C6229-1984-hand" },
+  {   70, "iso-ir-94" },
+  {   70, "jp-ocr-hand" },
+  {   70, "csISO94JIS62291984hand" },
+  {   71, "JIS_C6229-1984-hand-add" },
+  {   71, "iso-ir-95" },
+  {   71, "jp-ocr-hand-add" },
+  {   71, "csISO95JIS62291984handadd" },
+  {   72, "JIS_C6229-1984-kana" },
+  {   72, "iso-ir-96" },
+  {   72, "csISO96JISC62291984kana" },
+  {   73, "ISO_2033-1983" },
+  {   73, "iso-ir-98" },
+  {   73, "e13b" },
+  {   73, "csISO2033" },
+  {   74, "ANSI_X3.110-1983" },
+  {   74, "iso-ir-99" },
+  {   74, "CSA_T500-1983" },
+  {   74, "NAPLPS" },
+  {   74, "csISO99NAPLPS" },
+  {   75, "T.61-7bit" },
+  {   75, "iso-ir-102" },
+  {   75, "csISO102T617bit" },
+  {   76, "T.61-8bit" },
+  {   76, "T.61" },
+  {   76, "iso-ir-103" },
+  {   76, "csISO103T618bit" },
+  {   77, "ECMA-cyrillic" },
+  {   77, "iso-ir-111" },
+  {   77, "KOI8-E" },
+  {   77, "csISO111ECMACyrillic" },
+  {   78, "CSA_Z243.4-1985-1" },
+  {   78, "iso-ir-121" },
+  {   78, "ISO646-CA" },
+  {   78, "csa7-1" },
+  {   78, "csa71" },
+  {   78, "ca" },
+  {   78, "csISO121Canadian1" },
+  {   79, "CSA_Z243.4-1985-2" },
+  {   79, "iso-ir-122" },
+  {   79, "ISO646-CA2" },
+  {   79, "csa7-2" },
+  {   79, "csa72" },
+  {   79, "csISO122Canadian2" },
+  {   80, "CSA_Z243.4-1985-gr" },
+  {   80, "iso-ir-123" },
+  {   80, "csISO123CSAZ24341985gr" },
+  {   81, "ISO_8859-6-E" },
+  {   81, "csISO88596E" },
+  {   81, "ISO-8859-6-E" },
+  {   82, "ISO_8859-6-I" },
+  {   82, "csISO88596I" },
+  {   82, "ISO-8859-6-I" },
+  {   83, "T.101-G2" },
+  {   83, "iso-ir-128" },
+  {   83, "csISO128T101G2" },
+  {   84, "ISO_8859-8-E" },
+  {   84, "csISO88598E" },
+  {   84, "ISO-8859-8-E" },
+  {   85, "ISO_8859-8-I" },
+  {   85, "csISO88598I" },
+  {   85, "ISO-8859-8-I" },
+  {   86, "CSN_369103" },
+  {   86, "iso-ir-139" },
+  {   86, "csISO139CSN369103" },
+  {   87, "JUS_I.B1.002" },
+  {   87, "iso-ir-141" },
+  {   87, "ISO646-YU" },
+  {   87, "js" },
+  {   87, "yu" },
+  {   87, "csISO141JUSIB1002" },
+  {   88, "IEC_P27-1" },
+  {   88, "iso-ir-143" },
+  {   88, "csISO143IECP271" },
+  {   89, "JUS_I.B1.003-serb" },
+  {   89, "iso-ir-146" },
+  {   89, "serbian" },
+  {   89, "csISO146Serbian" },
+  {   90, "JUS_I.B1.003-mac" },
+  {   90, "macedonian" },
+  {   90, "iso-ir-147" },
+  {   90, "csISO147Macedonian" },
+  {   91, "greek-ccitt" },
+  {   91, "iso-ir-150" },
+  {   91, "csISO150" },
+  {   91, "csISO150GreekCCITT" },
+  {   92, "NC_NC00-10:81" },
+  {   92, "cuba" },
+  {   92, "iso-ir-151" },
+  {   92, "ISO646-CU" },
+  {   92, "csISO151Cuba" },
+  {   93, "ISO_6937-2-25" },
+  {   93, "iso-ir-152" },
+  {   93, "csISO6937Add" },
+  {   94, "GOST_19768-74" },
+  {   94, "ST_SEV_358-88" },
+  {   94, "iso-ir-153" },
+  {   94, "csISO153GOST1976874" },
+  {   95, "ISO_8859-supp" },
+  {   95, "iso-ir-154" },
+  {   95, "latin1-2-5" },
+  {   95, "csISO8859Supp" },
+  {   96, "ISO_10367-box" },
+  {   96, "iso-ir-155" },
+  {   96, "csISO10367Box" },
+  {   97, "latin-lap" },
+  {   97, "lap" },
+  {   97, "iso-ir-158" },
+  {   97, "csISO158Lap" },
+  {   98, "JIS_X0212-1990" },
+  {   98, "x0212" },
+  {   98, "iso-ir-159" },
+  {   98, "csISO159JISX02121990" },
+  {   99, "DS_2089" },
+  {   99, "DS2089" },
+  {   99, "ISO646-DK" },
+  {   99, "dk" },
+  {   99, "csISO646Danish" },
+  {  100, "us-dk" },
+  {  100, "csUSDK" },
+  {  101, "dk-us" },
+  {  101, "csDKUS" },
+  {  102, "KSC5636" },
+  {  102, "ISO646-KR" },
+  {  102, "csKSC5636" },
+  {  103, "UNICODE-1-1-UTF-7" },
+  {  103, "csUnicode11UTF7" },
+  {  104, "ISO-2022-CN" },
+  {  104, "csISO2022CN" },
+  {  105, "ISO-2022-CN-EXT" },
+  {  105, "csISO2022CNEXT" },
+#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
+  {  106, "UTF-8" },
+  {  106, "csUTF8" },
+  {  109, "ISO-8859-13" },
+  {  109, "csISO885913" },
+  {  110, "ISO-8859-14" },
+  {  110, "iso-ir-199" },
+  {  110, "ISO_8859-14:1998" },
+  {  110, "ISO_8859-14" },
+  {  110, "latin8" },
+  {  110, "iso-celtic" },
+  {  110, "l8" },
+  {  110, "csISO885914" },
+  {  111, "ISO-8859-15" },
+  {  111, "ISO_8859-15" },
+  {  111, "Latin-9" },
+  {  111, "csISO885915" },
+  {  112, "ISO-8859-16" },
+  {  112, "iso-ir-226" },
+  {  112, "ISO_8859-16:2001" },
+  {  112, "ISO_8859-16" },
+  {  112, "latin10" },
+  {  112, "l10" },
+  {  112, "csISO885916" },
+  {  113, "GBK" },
+  {  113, "CP936" },
+  {  113, "MS936" },
+  {  113, "windows-936" },
+  {  113, "csGBK" },
+  {  114, "GB18030" },
+  {  114, "csGB18030" },
+  {  115, "OSD_EBCDIC_DF04_15" },
+  {  115, "csOSDEBCDICDF0415" },
+  {  116, "OSD_EBCDIC_DF03_IRV" },
+  {  116, "csOSDEBCDICDF03IRV" },
+  {  117, "OSD_EBCDIC_DF04_1" },
+  {  117, "csOSDEBCDICDF041" },
+  {  118, "ISO-11548-1" },
+  {  118, "ISO_11548-1" },
+  {  118, "ISO_TR_11548-1" },
+  {  118, "csISO115481" },
+  {  119, "KZ-1048" },
+  {  119, "STRK1048-2002" },
+  {  119, "RK1048" },
+  {  119, "csKZ1048" },
+  { 1000, "ISO-10646-UCS-2" },
+  { 1000, "csUnicode" },
+  { 1001, "ISO-10646-UCS-4" },
+  { 1001, "csUCS4" },
+  { 1002, "ISO-10646-UCS-Basic" },
+  { 1002, "csUnicodeASCII" },
+  { 1003, "ISO-10646-Unicode-Latin1" },
+  { 1003, "csUnicodeLatin1" },
+  { 1003, "ISO-10646" },
+  { 1004, "ISO-10646-J-1" },
+  { 1004, "csUnicodeJapanese" },
+  { 1005, "ISO-Unicode-IBM-1261" },
+  { 1005, "csUnicodeIBM1261" },
+  { 1006, "ISO-Unicode-IBM-1268" },
+  { 1006, "csUnicodeIBM1268" },
+  { 1007, "ISO-Unicode-IBM-1276" },
+  { 1007, "csUnicodeIBM1276" },
+  { 1008, "ISO-Unicode-IBM-1264" },
+  { 1008, "csUnicodeIBM1264" },
+  { 1009, "ISO-Unicode-IBM-1265" },
+  { 1009, "csUnicodeIBM1265" },
+  { 1010, "UNICODE-1-1" },
+  { 1010, "csUnicode11" },
+  { 1011, "SCSU" },
+  { 1011, "csSCSU" },
+  { 1012, "UTF-7" },
+  { 1012, "csUTF7" },
+  { 1013, "UTF-16BE" },
+  { 1013, "csUTF16BE" },
+  { 1014, "UTF-16LE" },
+  { 1014, "csUTF16LE" },
+  { 1015, "UTF-16" },
+  { 1015, "csUTF16" },
+  { 1016, "CESU-8" },
+  { 1016, "csCESU8" },
+  { 1016, "csCESU-8" },
+  { 1017, "UTF-32" },
+  { 1017, "csUTF32" },
+  { 1018, "UTF-32BE" },
+  { 1018, "csUTF32BE" },
+  { 1019, "UTF-32LE" },
+  { 1019, "csUTF32LE" },
+  { 1020, "BOCU-1" },
+  { 1020, "csBOCU1" },
+  { 1020, "csBOCU-1" },
+  { 1021, "UTF-7-IMAP" },
+  { 1021, "csUTF7IMAP" },
+  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
+  { 2000, "csWindows30Latin1" },
+  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
+  { 2001, "csWindows31Latin1" },
+  { 2002, "ISO-8859-2-Windows-Latin-2" },
+  { 2002, "csWindows31Latin2" },
+  { 2003, "ISO-8859-9-Windows-Latin-5" },
+  { 2003, "csWindows31Latin5" },
+  { 2004, "hp-roman8" },
+  { 2004, "roman8" },
+  { 2004, "r8" },
+  { 2004, "csHPRoman8" },
+  { 2005, "Adobe-Standard-Encoding" },
+  { 2005, "csAdobeStandardEncoding" },
+  { 2006, "Ventura-US" },
+  { 2006, "csVenturaUS" },
+  { 2007, "Ventura-International" },
+  { 2007, "csVenturaInternational" },
+  { 2008, "DEC-MCS" },
+  { 2008, "dec" },
+  { 2008, "csDECMCS" },
+  { 2009, "IBM850" },
+  { 2009, "cp850" },
+  { 2009, "850" },
+  { 2009, "csPC850Multilingual" },
+  { 2010, "IBM852" },
+  { 2010, "cp852" },
+  { 2010, "852" },
+  { 2010, "csPCp852" },
+  { 2011, "IBM437" },
+  { 2011, "cp437" },
+  { 2011, "437" },
+  { 2011, "csPC8CodePage437" },
+  { 2012, "PC8-Danish-Norwegian" },
+  { 2012, "csPC8DanishNorwegian" },
+  { 2013, "IBM862" },
+  { 2013, "cp862" },
+  { 2013, "862" },
+  { 2013, "csPC862LatinHebrew" },
+  { 2014, "PC8-Turkish" },
+  { 2014, "csPC8Turkish" },
+  { 2015, "IBM-Symbols" },
+  { 2015, "csIBMSymbols" },
+  { 2016, "IBM-Thai" },
+  { 2016, "csIBMThai" },
+  { 2017, "HP-Legal" },
+  { 2017, "csHPLegal" },
+  { 2018, "HP-Pi-font" },
+  { 2018, "csHPPiFont" },
+  { 2019, "HP-Math8" },
+  { 2019, "csHPMath8" },
+  { 2020, "Adobe-Symbol-Encoding" },
+  { 2020, "csHPPSMath" },
+  { 2021, "HP-DeskTop" },
+  { 2021, "csHPDesktop" },
+  { 2022, "Ventura-Math" },
+  { 2022, "csVenturaMath" },
+  { 2023, "Microsoft-Publishing" },
+  { 2023, "csMicrosoftPublishing" },
+  { 2024, "Windows-31J" },
+  { 2024, "csWindows31J" },
+  { 2025, "GB2312" },
+  { 2025, "csGB2312" },
+  { 2026, "Big5" },
+  { 2026, "csBig5" },
+  { 2027, "macintosh" },
+  { 2027, "mac" },
+  { 2027, "csMacintosh" },
+  { 2028, "IBM037" },
+  { 2028, "cp037" },
+  { 2028, "ebcdic-cp-us" },
+  { 2028, "ebcdic-cp-ca" },
+  { 2028, "ebcdic-cp-wt" },
+  { 2028, "ebcdic-cp-nl" },
+  { 2028, "csIBM037" },
+  { 2029, "IBM038" },
+  { 2029, "EBCDIC-INT" },
+  { 2029, "cp038" },
+  { 2029, "csIBM038" },
+  { 2030, "IBM273" },
+  { 2030, "CP273" },
+  { 2030, "csIBM273" },
+  { 2031, "IBM274" },
+  { 2031, "EBCDIC-BE" },
+  { 2031, "CP274" },
+  { 2031, "csIBM274" },
+  { 2032, "IBM275" },
+  { 2032, "EBCDIC-BR" },
+  { 2032, "cp275" },
+  { 2032, "csIBM275" },
+  { 2033, "IBM277" },
+  { 2033, "EBCDIC-CP-DK" },
+  { 2033, "EBCDIC-CP-NO" },
+  { 2033, "csIBM277" },
+  { 2034, "IBM278" },
+  { 2034, "CP278" },
+  { 2034, "ebcdic-cp-fi" },
+  { 2034, "ebcdic-cp-se" },
+  { 2034, "csIBM278" },
+  { 2035, "IBM280" },
+  { 2035, "CP280" },
+  { 2035, "ebcdic-cp-it" },
+  { 2035, "csIBM280" },
+  { 2036, "IBM281" },
+  { 2036, "EBCDIC-JP-E" },
+  { 2036, "cp281" },
+  { 2036, "csIBM281" },
+  { 2037, "IBM284" },
+  { 2037, "CP284" },
+  { 2037, "ebcdic-cp-es" },
+  { 2037, "csIBM284" },
+  { 2038, "IBM285" },
+  { 2038, "CP285" },
+  { 2038, "ebcdic-cp-gb" },
+  { 2038, "csIBM285" },
+  { 2039, "IBM290" },
+  { 2039, "cp290" },
+  { 2039, "EBCDIC-JP-kana" },
+  { 2039, "csIBM290" },
+  { 2040, "IBM297" },
+  { 2040, "cp297" },
+  { 2040, "ebcdic-cp-fr" },
+  { 2040, "csIBM297" },
+  { 2041, "IBM420" },
+  { 2041, "cp420" },
+  { 2041, "ebcdic-cp-ar1" },
+  { 2041, "csIBM420" },
+  { 2042, "IBM423" },
+  { 2042, "cp423" },
+  { 2042, "ebcdic-cp-gr" },
+  { 2042, "csIBM423" },
+  { 2043, "IBM424" },
+  { 2043, "cp424" },
+  { 2043, "ebcdic-cp-he" },
+  { 2043, "csIBM424" },
+  { 2044, "IBM500" },
+  { 2044, "CP500" },
+  { 2044, "ebcdic-cp-be" },
+  { 2044, "ebcdic-cp-ch" },
+  { 2044, "csIBM500" },
+  { 2045, "IBM851" },
+  { 2045, "cp851" },
+  { 2045, "851" },
+  { 2045, "csIBM851" },
+  { 2046, "IBM855" },
+  { 2046, "cp855" },
+  { 2046, "855" },
+  { 2046, "csIBM855" },
+  { 2047, "IBM857" },
+  { 2047, "cp857" },
+  { 2047, "857" },
+  { 2047, "csIBM857" },
+  { 2048, "IBM860" },
+  { 2048, "cp860" },
+  { 2048, "860" },
+  { 2048, "csIBM860" },
+  { 2049, "IBM861" },
+  { 2049, "cp861" },
+  { 2049, "861" },
+  { 2049, "cp-is" },
+  { 2049, "csIBM861" },
+  { 2050, "IBM863" },
+  { 2050, "cp863" },
+  { 2050, "863" },
+  { 2050, "csIBM863" },
+  { 2051, "IBM864" },
+  { 2051, "cp864" },
+  { 2051, "csIBM864" },
+  { 2052, "IBM865" },
+  { 2052, "cp865" },
+  { 2052, "865" },
+  { 2052, "csIBM865" },
+  { 2053, "IBM868" },
+  { 2053, "CP868" },
+  { 2053, "cp-ar" },
+  { 2053, "csIBM868" },
+  { 2054, "IBM869" },
+  { 2054, "cp869" },
+  { 2054, "869" },
+  { 2054, "cp-gr" },
+  { 2054, "csIBM869" },
+  { 2055, "IBM870" },
+  { 2055, "CP870" },
+  { 2055, "ebcdic-cp-roece" },
+  { 2055, "ebcdic-cp-yu" },
+  { 2055, "csIBM870" },
+  { 2056, "IBM871" },
+  { 2056, "CP871" },
+  { 2056, "ebcdic-cp-is" },
+  { 2056, "csIBM871" },
+  { 2057, "IBM880" },
+  { 2057, "cp880" },
+  { 2057, "EBCDIC-Cyrillic" },
+  { 2057, "csIBM880" },
+  { 2058, "IBM891" },
+  { 2058, "cp891" },
+  { 2058, "csIBM891" },
+  { 2059, "IBM903" },
+  { 2059, "cp903" },
+  { 2059, "csIBM903" },
+  { 2060, "IBM904" },
+  { 2060, "cp904" },
+  { 2060, "904" },
+  { 2060, "csIBBM904" },
+  { 2061, "IBM905" },
+  { 2061, "CP905" },
+  { 2061, "ebcdic-cp-tr" },
+  { 2061, "csIBM905" },
+  { 2062, "IBM918" },
+  { 2062, "CP918" },
+  { 2062, "ebcdic-cp-ar2" },
+  { 2062, "csIBM918" },
+  { 2063, "IBM1026" },
+  { 2063, "CP1026" },
+  { 2063, "csIBM1026" },
+  { 2064, "EBCDIC-AT-DE" },
+  { 2064, "csIBMEBCDICATDE" },
+  { 2065, "EBCDIC-AT-DE-A" },
+  { 2065, "csEBCDICATDEA" },
+  { 2066, "EBCDIC-CA-FR" },
+  { 2066, "csEBCDICCAFR" },
+  { 2067, "EBCDIC-DK-NO" },
+  { 2067, "csEBCDICDKNO" },
+  { 2068, "EBCDIC-DK-NO-A" },
+  { 2068, "csEBCDICDKNOA" },
+  { 2069, "EBCDIC-FI-SE" },
+  { 2069, "csEBCDICFISE" },
+  { 2070, "EBCDIC-FI-SE-A" },
+  { 2070, "csEBCDICFISEA" },
+  { 2071, "EBCDIC-FR" },
+  { 2071, "csEBCDICFR" },
+  { 2072, "EBCDIC-IT" },
+  { 2072, "csEBCDICIT" },
+  { 2073, "EBCDIC-PT" },
+  { 2073, "csEBCDICPT" },
+  { 2074, "EBCDIC-ES" },
+  { 2074, "csEBCDICES" },
+  { 2075, "EBCDIC-ES-A" },
+  { 2075, "csEBCDICESA" },
+  { 2076, "EBCDIC-ES-S" },
+  { 2076, "csEBCDICESS" },
+  { 2077, "EBCDIC-UK" },
+  { 2077, "csEBCDICUK" },
+  { 2078, "EBCDIC-US" },
+  { 2078, "csEBCDICUS" },
+  { 2079, "UNKNOWN-8BIT" },
+  { 2079, "csUnknown8BiT" },
+  { 2080, "MNEMONIC" },
+  { 2080, "csMnemonic" },
+  { 2081, "MNEM" },
+  { 2081, "csMnem" },
+  { 2082, "VISCII" },
+  { 2082, "csVISCII" },
+  { 2083, "VIQR" },
+  { 2083, "csVIQR" },
+  { 2084, "KOI8-R" },
+  { 2084, "csKOI8R" },
+  { 2085, "HZ-GB-2312" },
+  { 2086, "IBM866" },
+  { 2086, "cp866" },
+  { 2086, "866" },
+  { 2086, "csIBM866" },
+  { 2087, "IBM775" },
+  { 2087, "cp775" },
+  { 2087, "csPC775Baltic" },
+  { 2088, "KOI8-U" },
+  { 2088, "csKOI8U" },
+  { 2089, "IBM00858" },
+  { 2089, "CCSID00858" },
+  { 2089, "CP00858" },
+  { 2089, "PC-Multilingual-850+euro" },
+  { 2089, "csIBM00858" },
+  { 2090, "IBM00924" },
+  { 2090, "CCSID00924" },
+  { 2090, "CP00924" },
+  { 2090, "ebcdic-Latin9--euro" },
+  { 2090, "csIBM00924" },
+  { 2091, "IBM01140" },
+  { 2091, "CCSID01140" },
+  { 2091, "CP01140" },
+  { 2091, "ebcdic-us-37+euro" },
+  { 2091, "csIBM01140" },
+  { 2092, "IBM01141" },
+  { 2092, "CCSID01141" },
+  { 2092, "CP01141" },
+  { 2092, "ebcdic-de-273+euro" },
+  { 2092, "csIBM01141" },
+  { 2093, "IBM01142" },
+  { 2093, "CCSID01142" },
+  { 2093, "CP01142" },
+  { 2093, "ebcdic-dk-277+euro" },
+  { 2093, "ebcdic-no-277+euro" },
+  { 2093, "csIBM01142" },
+  { 2094, "IBM01143" },
+  { 2094, "CCSID01143" },
+  { 2094, "CP01143" },
+  { 2094, "ebcdic-fi-278+euro" },
+  { 2094, "ebcdic-se-278+euro" },
+  { 2094, "csIBM01143" },
+  { 2095, "IBM01144" },
+  { 2095, "CCSID01144" },
+  { 2095, "CP01144" },
+  { 2095, "ebcdic-it-280+euro" },
+  { 2095, "csIBM01144" },
+  { 2096, "IBM01145" },
+  { 2096, "CCSID01145" },
+  { 2096, "CP01145" },
+  { 2096, "ebcdic-es-284+euro" },
+  { 2096, "csIBM01145" },
+  { 2097, "IBM01146" },
+  { 2097, "CCSID01146" },
+  { 2097, "CP01146" },
+  { 2097, "ebcdic-gb-285+euro" },
+  { 2097, "csIBM01146" },
+  { 2098, "IBM01147" },
+  { 2098, "CCSID01147" },
+  { 2098, "CP01147" },
+  { 2098, "ebcdic-fr-297+euro" },
+  { 2098, "csIBM01147" },
+  { 2099, "IBM01148" },
+  { 2099, "CCSID01148" },
+  { 2099, "CP01148" },
+  { 2099, "ebcdic-international-500+euro" },
+  { 2099, "csIBM01148" },
+  { 2100, "IBM01149" },
+  { 2100, "CCSID01149" },
+  { 2100, "CP01149" },
+  { 2100, "ebcdic-is-871+euro" },
+  { 2100, "csIBM01149" },
+  { 2101, "Big5-HKSCS" },
+  { 2101, "csBig5HKSCS" },
+  { 2102, "IBM1047" },
+  { 2102, "IBM-1047" },
+  { 2102, "csIBM1047" },
+  { 2103, "PTCP154" },
+  { 2103, "csPTCP154" },
+  { 2103, "PT154" },
+  { 2103, "CP154" },
+  { 2103, "Cyrillic-Asian" },
+  { 2104, "Amiga-1251" },
+  { 2104, "Ami1251" },
+  { 2104, "Amiga1251" },
+  { 2104, "Ami-1251" },
+  { 2104, "csAmiga1251" },
+  { 2104, "(Aliases" },
+  { 2104, "are" },
+  { 2104, "provided" },
+  { 2104, "for" },
+  { 2104, "historical" },
+  { 2104, "reasons" },
+  { 2104, "and" },
+  { 2104, "should" },
+  { 2104, "not" },
+  { 2104, "be" },
+  { 2104, "used)" },
+  { 2104, "[Malyshev]" },
+  { 2105, "KOI7-switched" },
+  { 2105, "csKOI7switched" },
+  { 2106, "BRF" },
+  { 2106, "csBRF" },
+  { 2107, "TSCII" },
+  { 2107, "csTSCII" },
+  { 2108, "CP51932" },
+  { 2108, "csCP51932" },
+  { 2109, "windows-874" },
+  { 2109, "cswindows874" },
+  { 2250, "windows-1250" },
+  { 2250, "cswindows1250" },
+  { 2251, "windows-1251" },
+  { 2251, "cswindows1251" },
+  { 2252, "windows-1252" },
+  { 2252, "cswindows1252" },
+  { 2253, "windows-1253" },
+  { 2253, "cswindows1253" },
+  { 2254, "windows-1254" },
+  { 2254, "cswindows1254" },
+  { 2255, "windows-1255" },
+  { 2255, "cswindows1255" },
+  { 2256, "windows-1256" },
+  { 2256, "cswindows1256" },
+  { 2257, "windows-1257" },
+  { 2257, "cswindows1257" },
+  { 2258, "windows-1258" },
+  { 2258, "cswindows1258" },
+  { 2259, "TIS-620" },
+  { 2259, "csTIS620" },
+  { 2259, "ISO-8859-11" },
+  { 2260, "CP50220" },
+  { 2260, "csCP50220" },
+
+#undef _GLIBCXX_GET_ENCODING_DATA
diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
index f1b2b359bdf..8bc55e9c136 100644
--- a/libstdc++-v3/include/bits/unicode.h
+++ b/libstdc++-v3/include/bits/unicode.h
@@ -32,7 +32,8 @@
 
 #if __cplusplus >= 202002L
 #include <array>
-#include <bit>
+#include <bit>      // bit_width
+#include <charconv> // __detail::__from_chars_alnum_to_val_table
 #include <cstdint>
 #include <bits/stl_algo.h>
 #include <bits/stl_iterator.h>
@@ -986,7 +987,7 @@ inline namespace __v15_1_0
       return __n;
     }
 
-    template<typename _CharT>
+  template<typename _CharT>
     consteval bool
     __literal_encoding_is_unicode()
     {
@@ -1056,6 +1057,54 @@ inline namespace __v15_1_0
   __literal_encoding_is_utf8()
   { return __literal_encoding_is_unicode<char>(); }
 
+  consteval bool
+  __literal_encoding_is_extended_ascii()
+  {
+    return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
+	     && 'a' == 0x61 && 'z' == 0x7a;
+  }
+
+  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
+  constexpr bool
+  __charset_alias_match(string_view __a, string_view __b)
+  {
+    // Map alphanumeric chars to their base 64 value, everything else to 127.
+    auto __map = [](char __c, bool& __num) -> unsigned char {
+      using __detail::__from_chars_alnum_to_val_table;
+      if (__c == '0') [[unlikely]]
+	return __num ? 0 : 127;
+      auto __v = __from_chars_alnum_to_val_table<false>::value.__data[__c];
+      __num = __v < 10;
+      return __v;
+    };
+
+    auto __ptr_a = __a.begin(), __end_a = __a.end();
+    auto __ptr_b = __b.begin(), __end_b = __b.end();
+    bool __num_a = false, __num_b = false;
+
+    while (true)
+      {
+	// Find the value of the next alphanumeric character in each string.
+	unsigned char __val_a, __val_b;
+	while (__ptr_a != __end_a
+		 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
+	  ++__ptr_a;
+	while (__ptr_b != __end_b
+		 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
+	  ++__ptr_b;
+	// Stop when we reach the end of a string, or get a mismatch.
+	if (__ptr_a == __end_a)
+	  return __ptr_b == __end_b;
+	else if (__ptr_b == __end_b)
+	  return false;
+	else if (__val_a != __val_b)
+	  return false; // Found non-matching characters.
+	++__ptr_a;
+	++__ptr_b;
+      }
+    return true;
+  }
+
 } // namespace __unicode
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index afbec6c3e6a..8fb8a2877ee 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1751,6 +1751,16 @@ ftms = {
   };
 };
 
+ftms = {
+  name = text_encoding;
+  values = {
+    v = 202306;
+    cxxmin = 26;
+    hosted = yes;
+    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
+  };
+};
+
 ftms = {
   name = to_string;
   values = {
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 9688b246ef4..9ba99deeda6 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2137,6 +2137,17 @@
 #undef __glibcxx_want_saturation_arithmetic
 
 // from version.def line 1755
+#if !defined(__cpp_lib_text_encoding)
+# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
+#  define __glibcxx_text_encoding 202306L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
+#   define __cpp_lib_text_encoding 202306L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
+#undef __glibcxx_want_text_encoding
+
+// from version.def line 1765
 #if !defined(__cpp_lib_to_string)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
 #  define __glibcxx_to_string 202306L
@@ -2147,7 +2158,7 @@
 #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
 #undef __glibcxx_want_to_string
 
-// from version.def line 1765
+// from version.def line 1775
 #if !defined(__cpp_lib_generator)
 # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
 #  define __glibcxx_generator 202207L
diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
new file mode 100644
index 00000000000..df8a09c5810
--- /dev/null
+++ b/libstdc++-v3/include/std/text_encoding
@@ -0,0 +1,704 @@
+// <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/text_encoding
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TEXT_ENCODING
+#define _GLIBCXX_TEXT_ENCODING
+
+#pragma GCC system_header
+
+#include <bits/requires_hosted.h>
+
+#define __glibcxx_want_text_encoding
+#include <bits/version.h>
+
+#ifdef __cpp_lib_text_encoding
+#include <compare>
+#include <string_view>
+#include <bits/functional_hash.h> // hash
+#include <bits/ranges_util.h>     // view_interface
+#include <bits/unicode.h>         // __charset_alias_match
+#include <ext/numeric_traits.h>   // __int_traits
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  /**
+   * @brief An interface for accessing the IANA Character Sets registry.
+   * @ingroup locales
+   * @since C++23
+   */
+  struct text_encoding
+  {
+  private:
+    struct _Rep
+    {
+      using id = __INT_LEAST32_TYPE__;
+      id _M_id;
+      const char* _M_name;
+
+      friend constexpr bool
+      operator<(const _Rep& __r, id __m) noexcept
+      { return __r._M_id < __m; }
+
+      friend constexpr bool
+      operator==(const _Rep& __r, string_view __name) noexcept
+      { return __r._M_name == __name; }
+    };
+
+  public:
+    static constexpr size_t max_name_length = 63;
+
+    enum class id : _Rep::id
+    {
+      other = 1,
+      unknown = 2,
+      ASCII = 3,
+      ISOLatin1 = 4,
+      ISOLatin2 = 5,
+      ISOLatin3 = 6,
+      ISOLatin4 = 7,
+      ISOLatinCyrillic = 8,
+      ISOLatinArabic = 9,
+      ISOLatinGreek = 10,
+      ISOLatinHebrew = 11,
+      ISOLatin5 = 12,
+      ISOLatin6 = 13,
+      ISOTextComm = 14,
+      HalfWidthKatakana = 15,
+      JISEncoding = 16,
+      ShiftJIS = 17,
+      EUCPkdFmtJapanese = 18,
+      EUCFixWidJapanese = 19,
+      ISO4UnitedKingdom = 20,
+      ISO11SwedishForNames = 21,
+      ISO15Italian = 22,
+      ISO17Spanish = 23,
+      ISO21German = 24,
+      ISO60DanishNorwegian = 25,
+      ISO69French = 26,
+      ISO10646UTF1 = 27,
+      ISO646basic1983 = 28,
+      INVARIANT = 29,
+      ISO2IntlRefVersion = 30,
+      NATSSEFI = 31,
+      NATSSEFIADD = 32,
+      ISO10Swedish = 35,
+      KSC56011987 = 36,
+      ISO2022KR = 37,
+      EUCKR = 38,
+      ISO2022JP = 39,
+      ISO2022JP2 = 40,
+      ISO13JISC6220jp = 41,
+      ISO14JISC6220ro = 42,
+      ISO16Portuguese = 43,
+      ISO18Greek7Old = 44,
+      ISO19LatinGreek = 45,
+      ISO25French = 46,
+      ISO27LatinGreek1 = 47,
+      ISO5427Cyrillic = 48,
+      ISO42JISC62261978 = 49,
+      ISO47BSViewdata = 50,
+      ISO49INIS = 51,
+      ISO50INIS8 = 52,
+      ISO51INISCyrillic = 53,
+      ISO54271981 = 54,
+      ISO5428Greek = 55,
+      ISO57GB1988 = 56,
+      ISO58GB231280 = 57,
+      ISO61Norwegian2 = 58,
+      ISO70VideotexSupp1 = 59,
+      ISO84Portuguese2 = 60,
+      ISO85Spanish2 = 61,
+      ISO86Hungarian = 62,
+      ISO87JISX0208 = 63,
+      ISO88Greek7 = 64,
+      ISO89ASMO449 = 65,
+      ISO90 = 66,
+      ISO91JISC62291984a = 67,
+      ISO92JISC62991984b = 68,
+      ISO93JIS62291984badd = 69,
+      ISO94JIS62291984hand = 70,
+      ISO95JIS62291984handadd = 71,
+      ISO96JISC62291984kana = 72,
+      ISO2033 = 73,
+      ISO99NAPLPS = 74,
+      ISO102T617bit = 75,
+      ISO103T618bit = 76,
+      ISO111ECMACyrillic = 77,
+      ISO121Canadian1 = 78,
+      ISO122Canadian2 = 79,
+      ISO123CSAZ24341985gr = 80,
+      ISO88596E = 81,
+      ISO88596I = 82,
+      ISO128T101G2 = 83,
+      ISO88598E = 84,
+      ISO88598I = 85,
+      ISO139CSN369103 = 86,
+      ISO141JUSIB1002 = 87,
+      ISO143IECP271 = 88,
+      ISO146Serbian = 89,
+      ISO147Macedonian = 90,
+      ISO150 = 91,
+      ISO151Cuba = 92,
+      ISO6937Add = 93,
+      ISO153GOST1976874 = 94,
+      ISO8859Supp = 95,
+      ISO10367Box = 96,
+      ISO158Lap = 97,
+      ISO159JISX02121990 = 98,
+      ISO646Danish = 99,
+      USDK = 100,
+      DKUS = 101,
+      KSC5636 = 102,
+      Unicode11UTF7 = 103,
+      ISO2022CN = 104,
+      ISO2022CNEXT = 105,
+      UTF8 = 106,
+      ISO885913 = 109,
+      ISO885914 = 110,
+      ISO885915 = 111,
+      ISO885916 = 112,
+      GBK = 113,
+      GB18030 = 114,
+      OSDEBCDICDF0415 = 115,
+      OSDEBCDICDF03IRV = 116,
+      OSDEBCDICDF041 = 117,
+      ISO115481 = 118,
+      KZ1048 = 119,
+      UCS2 = 1000,
+      UCS4 = 1001,
+      UnicodeASCII = 1002,
+      UnicodeLatin1 = 1003,
+      UnicodeJapanese = 1004,
+      UnicodeIBM1261 = 1005,
+      UnicodeIBM1268 = 1006,
+      UnicodeIBM1276 = 1007,
+      UnicodeIBM1264 = 1008,
+      UnicodeIBM1265 = 1009,
+      Unicode11 = 1010,
+      SCSU = 1011,
+      UTF7 = 1012,
+      UTF16BE = 1013,
+      UTF16LE = 1014,
+      UTF16 = 1015,
+      CESU8 = 1016,
+      UTF32 = 1017,
+      UTF32BE = 1018,
+      UTF32LE = 1019,
+      BOCU1 = 1020,
+      UTF7IMAP = 1021,
+      Windows30Latin1 = 2000,
+      Windows31Latin1 = 2001,
+      Windows31Latin2 = 2002,
+      Windows31Latin5 = 2003,
+      HPRoman8 = 2004,
+      AdobeStandardEncoding = 2005,
+      VenturaUS = 2006,
+      VenturaInternational = 2007,
+      DECMCS = 2008,
+      PC850Multilingual = 2009,
+      PC8DanishNorwegian = 2012,
+      PC862LatinHebrew = 2013,
+      PC8Turkish = 2014,
+      IBMSymbols = 2015,
+      IBMThai = 2016,
+      HPLegal = 2017,
+      HPPiFont = 2018,
+      HPMath8 = 2019,
+      HPPSMath = 2020,
+      HPDesktop = 2021,
+      VenturaMath = 2022,
+      MicrosoftPublishing = 2023,
+      Windows31J = 2024,
+      GB2312 = 2025,
+      Big5 = 2026,
+      Macintosh = 2027,
+      IBM037 = 2028,
+      IBM038 = 2029,
+      IBM273 = 2030,
+      IBM274 = 2031,
+      IBM275 = 2032,
+      IBM277 = 2033,
+      IBM278 = 2034,
+      IBM280 = 2035,
+      IBM281 = 2036,
+      IBM284 = 2037,
+      IBM285 = 2038,
+      IBM290 = 2039,
+      IBM297 = 2040,
+      IBM420 = 2041,
+      IBM423 = 2042,
+      IBM424 = 2043,
+      PC8CodePage437 = 2011,
+      IBM500 = 2044,
+      IBM851 = 2045,
+      PCp852 = 2010,
+      IBM855 = 2046,
+      IBM857 = 2047,
+      IBM860 = 2048,
+      IBM861 = 2049,
+      IBM863 = 2050,
+      IBM864 = 2051,
+      IBM865 = 2052,
+      IBM868 = 2053,
+      IBM869 = 2054,
+      IBM870 = 2055,
+      IBM871 = 2056,
+      IBM880 = 2057,
+      IBM891 = 2058,
+      IBM903 = 2059,
+      IBM904 = 2060,
+      IBM905 = 2061,
+      IBM918 = 2062,
+      IBM1026 = 2063,
+      IBMEBCDICATDE = 2064,
+      EBCDICATDEA = 2065,
+      EBCDICCAFR = 2066,
+      EBCDICDKNO = 2067,
+      EBCDICDKNOA = 2068,
+      EBCDICFISE = 2069,
+      EBCDICFISEA = 2070,
+      EBCDICFR = 2071,
+      EBCDICIT = 2072,
+      EBCDICPT = 2073,
+      EBCDICES = 2074,
+      EBCDICESA = 2075,
+      EBCDICESS = 2076,
+      EBCDICUK = 2077,
+      EBCDICUS = 2078,
+      Unknown8BiT = 2079,
+      Mnemonic = 2080,
+      Mnem = 2081,
+      VISCII = 2082,
+      VIQR = 2083,
+      KOI8R = 2084,
+      HZGB2312 = 2085,
+      IBM866 = 2086,
+      PC775Baltic = 2087,
+      KOI8U = 2088,
+      IBM00858 = 2089,
+      IBM00924 = 2090,
+      IBM01140 = 2091,
+      IBM01141 = 2092,
+      IBM01142 = 2093,
+      IBM01143 = 2094,
+      IBM01144 = 2095,
+      IBM01145 = 2096,
+      IBM01146 = 2097,
+      IBM01147 = 2098,
+      IBM01148 = 2099,
+      IBM01149 = 2100,
+      Big5HKSCS = 2101,
+      IBM1047 = 2102,
+      PTCP154 = 2103,
+      Amiga1251 = 2104,
+      KOI7switched = 2105,
+      BRF = 2106,
+      TSCII = 2107,
+      CP51932 = 2108,
+      windows874 = 2109,
+      windows1250 = 2250,
+      windows1251 = 2251,
+      windows1252 = 2252,
+      windows1253 = 2253,
+      windows1254 = 2254,
+      windows1255 = 2255,
+      windows1256 = 2256,
+      windows1257 = 2257,
+      windows1258 = 2258,
+      TIS620 = 2259,
+      CP50220 = 2260
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+
+    constexpr explicit
+    text_encoding(string_view __enc) noexcept
+    : _M_rep(_S_find_name(__enc))
+    {
+      __enc.copy(_M_name, max_name_length);
+    }
+
+    // @pre i has the value of one of the enumerators of id.
+    constexpr
+    text_encoding(id __i) noexcept
+    : _M_rep(_S_find_id(__i))
+    {
+      if (string_view __name(_M_rep->_M_name); !__name.empty())
+	__name.copy(_M_name, max_name_length);
+    }
+
+    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
+
+    constexpr const char* name() const noexcept { return _M_name; }
+
+    struct aliases_view : ranges::view_interface<aliases_view>
+    {
+    private:
+      class _Iterator;
+      struct _Sentinel { };
+
+    public:
+      constexpr _Iterator begin() const noexcept { return _Iterator(_M_begin); }
+      constexpr _Sentinel end() const noexcept { return _Sentinel{}; }
+
+    private:
+      friend struct text_encoding;
+
+      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
+
+      class _Iterator
+      {
+      public:
+	using value_type = const char*;
+	using reference = const char*;
+	using difference_type = int;
+
+	constexpr _Iterator() = default;
+	constexpr value_type operator*() const;
+	constexpr _Iterator& operator++();
+	constexpr _Iterator& operator--();
+	constexpr _Iterator operator++(int);
+	constexpr _Iterator operator--(int);
+	constexpr value_type operator[](difference_type) const;
+	constexpr _Iterator& operator+=(difference_type);
+	constexpr _Iterator& operator-=(difference_type);
+	constexpr difference_type operator-(const _Iterator&) const;
+	constexpr bool operator==(const _Iterator&) const = default;
+	constexpr bool operator==(_Sentinel) const noexcept;
+	constexpr strong_ordering operator<=>(const _Iterator&) const;
+
+	friend _Iterator
+	operator+(_Iterator __i, difference_type __n)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator+(difference_type __n, _Iterator __i)
+	{
+	  __i += __n;
+	  return __i;
+	}
+
+	friend _Iterator
+	operator-(_Iterator __i, difference_type __n)
+	{
+	  __i -= __n;
+	  return __i;
+	}
+
+      private:
+	friend class text_encoding;
+
+	constexpr explicit
+	_Iterator(const _Rep* __r) noexcept
+	: _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
+	{ }
+
+	constexpr bool _M_dereferenceable() const noexcept;
+	static constexpr difference_type _S_neg(difference_type) noexcept;
+
+	const _Rep* _M_rep = nullptr;
+	_Rep::id _M_id = 0;
+      };
+
+      const _Rep* _M_begin = nullptr;
+    };
+
+    constexpr aliases_view
+    aliases() const noexcept
+    {
+      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __a,
+	       const text_encoding& __b) noexcept
+    {
+      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
+	return _S_comp(__a._M_name, __b._M_name);
+      else
+	return __a.mib() == __b.mib();
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __encoding, id __i) noexcept
+    { return __encoding.mib() == __i; }
+
+#if __CHAR_BIT__ == 8
+    static consteval text_encoding
+    literal() noexcept
+    {
+#ifdef __GNUC_EXECUTION_CHARSET_NAME
+      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
+#elif defined __clang_literal_encoding__
+      return text_encoding(__clang_literal_encoding__);
+#else
+      return text_encoding();
+#endif
+    }
+
+    static text_encoding
+    environment();
+
+    template<id _Id>
+      static bool
+      environment_is()
+      { return text_encoding(_Id)._M_is_environment(); }
+#else
+    static text_encoding literal() = delete;
+    static text_encoding environment() = delete;
+    template<id> static bool environment_is() = delete;
+#endif
+
+  private:
+    const _Rep* _M_rep = _S_reps + 1; // id::unknown
+    char _M_name[max_name_length + 1] = {0};
+
+    bool
+    _M_is_environment() const;
+
+    static inline constexpr _Rep _S_reps[] = {
+      { 1, "" }, { 2, "" },
+#define _GLIBCXX_GET_ENCODING_DATA
+#include <bits/text_encoding-data.h>
+#ifdef _GLIBCXX_GET_ENCODING_DATA
+# error "Invalid text_encoding data"
+#endif
+      { 9999, nullptr }, // sentinel
+    };
+
+    static constexpr bool
+    _S_comp(string_view __a, string_view __b)
+    { return __unicode::__charset_alias_match(__a, __b); }
+
+    static constexpr const _Rep*
+    _S_find_name(string_view __name) noexcept
+    {
+#ifdef _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET
+      // Optimize the common UTF-8 case to avoid a linear search through all
+      // strings in the table using the _S_comp function.
+      if (__name == "UTF-8")
+	return _S_reps + 2 + _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET;
+#endif
+
+      // The first two array elements (other and unknown) don't have names.
+      // The last element is a sentinel that can never match anything.
+      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
+      for (auto __r = __first; __r != __end; ++__r)
+	if (_S_comp(__r->_M_name, __name))
+	  {
+	    // Might have matched an alias. Find the first entry for this ID.
+	    const auto __id = __r->_M_id;
+	    while (__r[-1]._M_id == __id)
+	      --__r;
+	    return __r;
+	  }
+      return _S_reps; // id::other
+    }
+
+    static constexpr const _Rep*
+    _S_find_id(id __id) noexcept
+    {
+      const auto __i = (_Rep::id)__id;
+      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
+      if (__r->_M_id == __i) [[likely]]
+	return __r;
+      else
+	{
+	  // Preconditions: i has the value of one of the enumerators of id.
+	  __glibcxx_assert(__r->_M_id == __i);
+	  return _S_reps + 1; // id::unknown
+	}
+    }
+  };
+
+  template<>
+    struct hash<text_encoding>
+    {
+      size_t
+      operator()(const text_encoding& __enc) const noexcept
+      { return std::hash<text_encoding::id>()(__enc.mib()); }
+    };
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator*() const
+  -> value_type
+  {
+    if (_M_dereferenceable()) [[likely]]
+      return _M_rep->_M_name;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	return "";
+      }
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++()
+  -> _Iterator&
+  {
+    if (_M_dereferenceable()) [[likely]]
+      ++_M_rep;
+    else
+      {
+	__glibcxx_assert(_M_dereferenceable());
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--()
+  -> _Iterator&
+  {
+    const bool __decrementable = _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
+    if (__decrementable) [[likely]]
+      --_M_rep;
+    else
+      {
+	__glibcxx_assert(__decrementable);
+	*this = _Iterator{};
+      }
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator++(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    ++*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator--(int)
+  -> _Iterator
+  {
+    auto __it = *this;
+    --*this;
+    return __it;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator[](difference_type __n) const
+  -> value_type
+  { return *(*this + __n); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator+=(difference_type __n)
+  -> _Iterator&
+  {
+    if (_M_rep != nullptr)
+      {
+	if ((__n > 0 && __n < (std::end(_S_reps) - _M_rep))
+	      || (__n < 0 && __n > (_S_reps - _M_rep)))
+	  {
+	    if (_M_rep[__n]._M_id == _M_id)
+	      _M_rep += __n;
+	    else
+	      *this = _Iterator{};
+	  }
+	else if (__n != 0)
+	  *this = _Iterator{};
+      }
+    __glibcxx_assert(_M_rep != nullptr);
+    return *this;
+  }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-=(difference_type __n)
+  -> _Iterator&
+  { return operator+=(_S_neg(__n)); }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::operator-(const _Iterator& __i) const noexcept
+  -> difference_type
+  {
+    if (_M_id == __i._M_id)
+      return _M_rep - __i._M_rep;
+    __glibcxx_assert(_M_id == __i._M_id);
+    return __gnu_cxx::__int_traits<difference_type>::__max;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::operator==(_Sentinel) const noexcept
+  { return !_M_dereferenceable(); }
+
+  constexpr strong_ordering
+  text_encoding::aliases_view::
+  _Iterator::operator<=>(const _Iterator& __i) const
+  {
+    __glibcxx_assert(_M_id == __i._M_id);
+    return _M_rep <=> __i._M_rep;
+  }
+
+  constexpr bool
+  text_encoding::aliases_view::
+  _Iterator::_M_dereferenceable() const noexcept
+  { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
+
+  constexpr auto
+  text_encoding::aliases_view::
+  _Iterator::_S_neg(difference_type __n) noexcept
+  -> difference_type
+  {
+    using _Traits = __gnu_cxx::__int_traits<difference_type>;
+    if (__n == _Traits::__min) [[unlikely]]
+      return _Traits::__max;
+    return -__n;
+  }
+
+namespace ranges
+{
+  // Opt-in to borrowed_range concept
+  template<>
+    inline constexpr bool
+    enable_borrowed_range<std::text_encoding::aliases_view> = true;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cpp_lib_text_encoding
+#endif // _GLIBCXX_TEXT_ENCODING
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 032a7aa58a2..a6c2ed4599f 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
         typename = strip_versioned_namespace(self._typename)
         return "{}<{}, {}>".format(typename, value_type, value)
 
+class StdTextEncodingPrinter(printer_base):
+    """Print a std::text_encoding."""
+
+    def __init__(self, typename, val):
+        self._val = val
+        self._typename = typename
+
+    def to_string(self):
+        rep = self._val['_M_rep'].dereference()
+        if rep['_M_id'] == 1:
+            return self._val['_M_name']
+        if rep['_M_id'] == 2:
+            return 'unknown'
+        return rep['_M_name']
+
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
 class RxPrinter(object):
@@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
 
     libstdcxx_printer.add_version('std::', 'integral_constant',
                                   StdIntegralConstantPrinter)
+    libstdcxx_printer.add_version('std::', 'text_encoding',
+                                  StdTextEncodingPrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
new file mode 100755
index 00000000000..2d6f3e4077a
--- /dev/null
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+#
+# Script to generate tables for libstdc++ std::text_encoding.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+#
+# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
+# the latest:
+# https://www.iana.org/assignments/character-sets/character-sets-1.csv
+# Then run this script and save the output to
+# include/bits/text_encoding-data.h
+
+import sys
+import csv
+
+if len(sys.argv) != 2:
+    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
+    sys.exit(1)
+
+print("// Generated by gen_text_encoding_data.py, do not edit.\n")
+print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
+print('# error "This is not a public header, do not include it directly"')
+print("#endif\n")
+
+
+charsets = {}
+with open(sys.argv[1], newline='') as f:
+    reader = csv.reader(f)
+    next(reader) # skip header row
+    for row in reader:
+        mib = int(row[2])
+        if mib in charsets:
+            raise ValueError("Multiple rows for mibEnum={}".format(mib))
+        name = row[1]
+        aliases = row[5].split()
+        # Ensure primary name comes first
+        if name in aliases:
+            aliases.remove(name)
+        charsets[mib] = [name] + aliases
+
+# Remove "NATS-DANO" and "NATS-DANO-ADD"
+charsets.pop(33, None)
+charsets.pop(34, None)
+
+count = 0
+for mib in sorted(charsets.keys()):
+    names = charsets[mib]
+    if names[0] == "UTF-8":
+        print("#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET {}".format(count))
+    for name in names:
+        print('  {{ {:4}, "{}" }},'.format(mib, name))
+    count += len(names)
+
+# <text_encoding> gives an error if this macro is left defined.
+# Do this last, so that the generated output is not usable unless we reach here.
+print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 7292ae70f81..37ba1491dea 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -43,7 +43,7 @@ experimental_dir =
 endif
 
 ## Keep this list sync'd with acinclude.m4:GLIBCXX_CONFIGURE.
-SUBDIRS = c++98 c++11 c++17 c++20 c++23 \
+SUBDIRS = c++98 c++11 c++17 c++20 c++23 c++26 \
 	$(filesystem_dir) $(backtrace_dir) $(experimental_dir)
 
 # Cross compiler support.
@@ -77,6 +77,7 @@ vpath % $(top_srcdir)/src/c++11
 vpath % $(top_srcdir)/src/c++17
 vpath % $(top_srcdir)/src/c++20
 vpath % $(top_srcdir)/src/c++23
+vpath % $(top_srcdir)/src/c++26
 if ENABLE_FILESYSTEM_TS
 vpath % $(top_srcdir)/src/filesystem
 endif
diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
new file mode 100644
index 00000000000..000ced1f501
--- /dev/null
+++ b/libstdc++-v3/src/c++26/Makefile.am
@@ -0,0 +1,109 @@
+## Makefile for the C++26 sources of the GNU C++ Standard library.
+##
+## Copyright (C) 1997-2023 Free Software Foundation, Inc.
+##
+## This file is part of the libstdc++ version 3 distribution.
+## Process this file with automake to produce Makefile.in.
+
+## This file is part of the GNU ISO C++ Library.  This library is free
+## software; you can redistribute it and/or modify it under the
+## terms of the GNU General Public License as published by the
+## Free Software Foundation; either version 3, or (at your option)
+## any later version.
+
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+## You should have received a copy of the GNU General Public License along
+## with this library; see the file COPYING3.  If not see
+## <http://www.gnu.org/licenses/>.
+
+include $(top_srcdir)/fragment.am
+
+# Convenience library for C++26 runtime.
+noinst_LTLIBRARIES = libc++26convenience.la
+
+headers =
+
+if ENABLE_EXTERN_TEMPLATE
+# XTEMPLATE_FLAGS = -fno-implicit-templates
+inst_sources =
+else
+# XTEMPLATE_FLAGS =
+inst_sources =
+endif
+
+sources = text_encoding.cc
+
+vpath % $(top_srcdir)/src/c++26
+
+
+if GLIBCXX_HOSTED
+libc__26convenience_la_SOURCES = $(sources)  $(inst_sources)
+else
+libc__26convenience_la_SOURCES =
+endif
+
+# AM_CXXFLAGS needs to be in each subdirectory so that it can be
+# modified in a per-library or per-sub-library way.  Need to manually
+# set this option because CONFIG_CXXFLAGS has to be after
+# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
+# as the occasion calls for it.
+AM_CXXFLAGS = \
+	-std=gnu++26 \
+	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
+	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
+	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
+	-fimplicit-templates
+
+AM_MAKEFLAGS = \
+	"gxx_include_dir=$(gxx_include_dir)"
+
+# Libtool notes
+
+# 1) In general, libtool expects an argument such as `--tag=CXX' when
+# using the C++ compiler, because that will enable the settings
+# detected when C++ support was being configured.  However, when no
+# such flag is given in the command line, libtool attempts to figure
+# it out by matching the compiler name in each configuration section
+# against a prefix of the command line.  The problem is that, if the
+# compiler name and its initial flags stored in the libtool
+# configuration file don't match those in the command line, libtool
+# can't decide which configuration to use, and it gives up.  The
+# correct solution is to add `--tag CXX' to LTCXXCOMPILE and maybe
+# CXXLINK, just after $(LIBTOOL), so that libtool doesn't have to
+# attempt to infer which configuration to use.
+#
+# The second tag argument, `--tag disable-shared` means that libtool
+# only compiles each source once, for static objects. In actuality,
+# glibcxx_lt_pic_flag and glibcxx_compiler_shared_flag are added to
+# the libtool command that is used create the object, which is
+# suitable for shared libraries.  The `--tag disable-shared` must be
+# placed after --tag CXX lest things CXX undo the affect of
+# disable-shared.
+
+# 2) Need to explicitly set LTCXXCOMPILE so that EXTRA_CXX_FLAGS is
+# last. (That way, things like -O2 passed down from the toplevel can
+# be overridden by --enable-debug.)
+LTCXXCOMPILE = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=compile $(CXX) $(TOPLEVEL_INCLUDES) \
+	$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CXXFLAGS) $(CXXFLAGS) $(EXTRA_CXX_FLAGS)
+
+LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
+
+# 3) We'd have a problem when building the shared libstdc++ object if
+# the rules automake generates would be used.  We cannot allow g++ to
+# be used since this would add -lstdc++ to the link line which of
+# course is problematic at this point.  So, we get the top-level
+# directory to configure libstdc++-v3 to use gcc as the C++
+# compilation driver.
+CXXLINK = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=link $(CXX) \
+	$(VTV_CXXLINKFLAGS) \
+	$(OPT_LDFLAGS) $(SECTION_LDFLAGS) $(AM_CXXFLAGS) $(LTLDFLAGS) -o $@
diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
new file mode 100644
index 00000000000..9a7df07db29
--- /dev/null
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -0,0 +1,91 @@
+// Definitions for <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <text_encoding>
+#include <locale>
+
+#ifdef _GLIBCXX_USE_NL_LANGINFO_L
+#include <locale.h>
+#include <langinfo.h>
+
+#if __CHAR_BIT__ == 8
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+text_encoding
+__locale_encoding(const char* name)
+{
+  text_encoding enc;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view s(codeset);
+	  if (s.size() < text_encoding::max_name_length)
+	    enc = text_encoding(s);
+	}
+      ::freelocale(loc);
+    }
+  return enc;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+std::text_encoding
+std::text_encoding::environment()
+{
+  return std::__locale_encoding("");
+}
+
+bool
+std::text_encoding::_M_is_environment() const
+{
+  bool matched = false;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, "", (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view sv(codeset);
+	  for (auto alias : aliases())
+	    if (__unicode::__charset_alias_match(alias, sv))
+	      {
+		matched = true;
+		break;
+	      }
+	}
+      ::freelocale(loc);
+    }
+  return matched;
+}
+
+std::text_encoding
+std::locale::encoding() const
+{
+  return std::__locale_encoding(name().c_str());
+}
+#endif // CHAR_BIT == 8
+
+#endif // _GLIBCXX_USE_NL_LANGINFO_L
diff --git a/libstdc++-v3/src/experimental/Makefile.am b/libstdc++-v3/src/experimental/Makefile.am
index 8259f986d95..6241430988e 100644
--- a/libstdc++-v3/src/experimental/Makefile.am
+++ b/libstdc++-v3/src/experimental/Makefile.am
@@ -47,10 +47,12 @@ libstdc__exp_la_SOURCES = $(sources)
 
 libstdc__exp_la_LIBADD = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 libstdc__exp_la_DEPENDENCIES = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 # AM_CXXFLAGS needs to be in each subdirectory so that it can be
diff --git a/libstdc++-v3/testsuite/22_locale/locale/encoding.cc b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
new file mode 100644
index 00000000000..18825fb88b9
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
@@ -0,0 +1,36 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <locale>
+#include <testsuite_hooks.h>
+
+void
+test_encoding()
+{
+  const std::locale c = std::locale::classic();
+  std::text_encoding c_enc = c.encoding();
+  VERIFY( c_enc == std::text_encoding::ASCII );
+
+  const std::locale fr = std::locale(ISO_8859(15, fr_FR));
+  std::text_encoding fr_enc = fr.encoding();
+  VERIFY( fr_enc == std::text_encoding::ISO885915 );
+
+  const std::locale en = std::locale(ISO_8859(1, en_US));
+  std::text_encoding en_enc = en.encoding();
+  VERIFY( en_enc == std::text_encoding::ISOLatin1 );
+
+#if __cpp_exceptions
+  try {
+    const std::locale c_utf8 = std::locale("C.UTF-8");
+    VERIFY( c_utf8.encoding() == std::text_encoding::UTF8 );
+  } catch (...) {
+  }
+#endif
+}
+
+int main()
+{
+  test_encoding();
+}
diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
new file mode 100644
index 00000000000..f6272ae998b
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+#include <format>
+
+using std::__unicode::__charset_alias_match;
+static_assert( __charset_alias_match("UTF-8", "utf8") == true );
+static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
+static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
+static_assert( __charset_alias_match("UTF-8", "ut8") == false );
+
+static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
+
+static_assert( __charset_alias_match("", "") == true );
+static_assert( __charset_alias_match("", ".") == true );
+static_assert( __charset_alias_match("--", "...") == true );
+static_assert( __charset_alias_match("--a", "a...") == true );
+static_assert( __charset_alias_match("--a010", "a..10.") == true );
+static_assert( __charset_alias_match("--a010", "a..1.0") == false );
+static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
new file mode 100644
index 00000000000..b9d93641de4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
@@ -0,0 +1,113 @@
+// { dg-do run { target c++26 } }
+
+#include <text_encoding>
+#include <string_view>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+constexpr void
+test_default_construct()
+{
+  std::text_encoding e0;
+  VERIFY( e0.mib() == std::text_encoding::unknown );
+  VERIFY( e0.name()[0] == '\0' ); // P2862R1 name() should never return null
+  VERIFY( e0.aliases().empty() );
+}
+
+constexpr void
+test_construct_by_name()
+{
+  std::string_view s;
+  std::text_encoding e0(s);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == s );
+  VERIFY( e0.aliases().empty() );
+
+  s = "not a real encoding";
+  std::text_encoding e1(s);
+  VERIFY( e1.mib() == std::text_encoding::other );
+  VERIFY( e1.name() == s );
+  VERIFY( e1.aliases().empty() );
+
+  VERIFY( e1 != e0 );
+  VERIFY( e1 == e0.mib() );
+
+  s = "utf8";
+  std::text_encoding e2(s);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == s );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == "UTF-8"sv );
+
+  s = "Latin-1"; // matches "latin1"
+  std::text_encoding e3(s);
+  VERIFY( e3.mib() == std::text_encoding::ISOLatin1 );
+  VERIFY( e3.name() == s );
+  VERIFY( ! e3.aliases().empty() );
+  VERIFY( e3.aliases().front() == "ISO_8859-1:1987"sv ); // primary name
+
+  s = "U.S."; // matches "us"
+  std::text_encoding e4(s);
+  VERIFY( e4.mib() == std::text_encoding::ASCII );
+  VERIFY( e4.name() == s );
+  VERIFY( ! e4.aliases().empty() );
+  VERIFY( e4.aliases().front() == "US-ASCII"sv ); // primary name
+}
+
+constexpr void
+test_construct_by_id()
+{
+  std::text_encoding e0(std::text_encoding::other);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == ""sv );
+  VERIFY( e0.aliases().empty() );
+
+  std::text_encoding e1(std::text_encoding::unknown);
+  VERIFY( e1.mib() == std::text_encoding::unknown );
+  VERIFY( e1.name() == ""sv );
+  VERIFY( e1.aliases().empty() );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == "UTF-8"sv );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == std::string_view(e2.name()) );
+  bool found = false;
+  for (auto alias : e2.aliases())
+    if (alias == "csUTF8"sv)
+    {
+      found = true;
+      break;
+    }
+  VERIFY( found );
+}
+
+constexpr void
+test_copy_construct()
+{
+  std::text_encoding e0;
+  std::text_encoding e1 = e0;
+  VERIFY( e1 == e0 );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  auto e3 = e2;
+  VERIFY( e3 == e2 );
+
+  e1 = e3;
+  VERIFY( e1 == e2 );
+}
+
+int main()
+{
+  auto run_tests = [] {
+    test_default_construct();
+    test_construct_by_name();
+    test_construct_by_id();
+    test_copy_construct();
+    return true;
+  };
+
+  run_tests();
+  static_assert( run_tests() );
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/members.cc b/libstdc++-v3/testsuite/std/text_encoding/members.cc
new file mode 100644
index 00000000000..0b0d6bd0c96
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/members.cc
@@ -0,0 +1,41 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <text_encoding>
+#include <string_view>
+#include <locale.h>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+void
+test_literal()
+{
+  const std::text_encoding lit = std::text_encoding::literal();
+  VERIFY( lit.name() == std::string_view(__GNUC_EXECUTION_CHARSET_NAME) );
+}
+
+void
+test_env()
+{
+  const std::text_encoding env = std::text_encoding::environment();
+
+  if (env.mib() == std::text_encoding::UTF8)
+    VERIFY( std::text_encoding::environment_is<std::text_encoding::UTF8>() );
+
+  ::setlocale(LC_ALL, ISO_8859(1, en_US));
+  const std::text_encoding env1 = std::text_encoding::environment();
+  VERIFY( env1 == env );
+
+  ::setlocale(LC_ALL, ISO_8859(15, fr_FR));
+  const std::text_encoding env2 = std::text_encoding::environment();
+  VERIFY( env2 == env );
+}
+
+int main()
+{
+  test_literal();
+  test_env();
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
new file mode 100644
index 00000000000..d62d93dcda4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <text_encoding>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <text_encoding>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
+#endif
+
+#undef __cpp_lib_expected
+#include <version>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <version>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <version>"
+#endif
+
+#include <concepts>
+#include <ranges>
+static_assert( std::is_trivially_copyable_v<std::text_encoding> );
+
+using aliases_view = std::text_encoding::aliases_view;
+static_assert( std::copyable<aliases_view> );
+static_assert( std::ranges::view<aliases_view> );
+static_assert( std::ranges::random_access_range<aliases_view> );
+static_assert( std::ranges::borrowed_range<aliases_view> );
+static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
+			    const char*> );
+static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
+			    const char*> );
-- 
2.43.0


^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-15 20:45   ` [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] Jonathan Wakely
@ 2024-01-15 22:24     ` Ulrich Drepper
  2024-01-16  0:09     ` Patrick Palka
  1 sibling, 0 replies; 9+ messages in thread
From: Ulrich Drepper @ 2024-01-15 22:24 UTC (permalink / raw)
  To: Jonathan Wakely; +Cc: libstdc++, gcc-patches

On Mon, Jan 15, 2024 at 9:45 PM Jonathan Wakely <jwakely@redhat.com> wrote:
> I think I'm happy with this now. It has tests for all the new functions,
> and the performance of the charset alias match algorithm is improved by
> reusing part of <charconv>.
>
> Tested x86_64-linux.

Looks good to me.  Good work, Jon.

^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-15 20:45   ` [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] Jonathan Wakely
  2024-01-15 22:24     ` Ulrich Drepper
@ 2024-01-16  0:09     ` Patrick Palka
  2024-01-16 14:06       ` [PATCH v4] " Jonathan Wakely
  1 sibling, 1 reply; 9+ messages in thread
From: Patrick Palka @ 2024-01-16  0:09 UTC (permalink / raw)
  To: Jonathan Wakely; +Cc: libstdc++, gcc-patches

On Mon, 15 Jan 2024, Jonathan Wakely wrote:

> I think I'm happy with this now. It has tests for all the new functions,
> and the performance of the charset alias match algorithm is improved by
> reusing part of <charconv>.
> 
> Tested x86_64-linux.
> 
> -- >8 --
> 
> This is another C++26 change, approved in Varna 2022. We require a new

2023?

> static array of data that is extracted from the IANA Character Sets
> database. A new Python script to generate a header from the IANA CSV
> file is added.
> 
> libstdc++-v3/ChangeLog:
> 
> 	PR libstdc++/113318
> 	* acinclude.m4 (GLIBCXX_CONFIGURE): Add c++26 directory.
> 	(GLIBCXX_CHECK_TEXT_ENCODING): Define.
> 	* config.h.in: Regenerate.
> 	* configure: Regenerate.
> 	* configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
> 	* include/Makefile.am: Add new headers.
> 	* include/Makefile.in: Regenerate.
> 	* include/bits/locale_classes.h (locale::encoding): Declare new
> 	member function.
> 	* include/bits/unicode.h (__charset_alias_match): New function.
> 	* include/bits/text_encoding-data.h: New file.
> 	* include/bits/version.def (text_encoding): Define.
> 	* include/bits/version.h: Regenerate.
> 	* include/std/text_encoding: New file.
> 	* src/Makefile.am: Add new subdirectory.
> 	* src/Makefile.in: Regenerate.
> 	* src/c++26/Makefile.am: New file.
> 	* src/c++26/Makefile.in: New file.
> 	* src/c++26/text_encoding.cc: New file.
> 	* src/experimental/Makefile.am: Include c++26 convenience
> 	library.
> 	* src/experimental/Makefile.in: Regenerate.
> 	* python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
> 	printer.
> 	* scripts/gen_text_encoding_data.py: New file.
> 	* testsuite/22_locale/locale/encoding.cc: New test.
> 	* testsuite/ext/unicode/charset_alias_match.cc: New test.
> 	* testsuite/std/text_encoding/cons.cc: New test.
> 	* testsuite/std/text_encoding/members.cc: New test.
> 	* testsuite/std/text_encoding/requirements.cc: New test.
> ---
>  libstdc++-v3/acinclude.m4                     |  30 +-
>  libstdc++-v3/config.h.in                      |   3 +
>  libstdc++-v3/configure                        |  70 +-
>  libstdc++-v3/configure.ac                     |   3 +
>  libstdc++-v3/include/Makefile.am              |   2 +
>  libstdc++-v3/include/Makefile.in              |   2 +
>  libstdc++-v3/include/bits/locale_classes.h    |  14 +
>  .../include/bits/text_encoding-data.h         | 902 ++++++++++++++++++
>  libstdc++-v3/include/bits/unicode.h           |  53 +-
>  libstdc++-v3/include/bits/version.def         |  10 +
>  libstdc++-v3/include/bits/version.h           |  13 +-
>  libstdc++-v3/include/std/text_encoding        | 704 ++++++++++++++
>  libstdc++-v3/python/libstdcxx/v6/printers.py  |  17 +
>  .../scripts/gen_text_encoding_data.py         |  70 ++
>  libstdc++-v3/src/Makefile.am                  |   3 +-
>  libstdc++-v3/src/Makefile.in                  |   7 +-
>  libstdc++-v3/src/c++26/Makefile.am            | 109 +++
>  libstdc++-v3/src/c++26/Makefile.in            | 747 +++++++++++++++
>  libstdc++-v3/src/c++26/text_encoding.cc       |  91 ++
>  libstdc++-v3/src/experimental/Makefile.am     |   2 +
>  libstdc++-v3/src/experimental/Makefile.in     |   2 +
>  .../testsuite/22_locale/locale/encoding.cc    |  36 +
>  .../ext/unicode/charset_alias_match.cc        |  18 +
>  .../testsuite/std/text_encoding/cons.cc       | 113 +++
>  .../testsuite/std/text_encoding/members.cc    |  41 +
>  .../std/text_encoding/requirements.cc         |  31 +
>  26 files changed, 3083 insertions(+), 10 deletions(-)
>  create mode 100644 libstdc++-v3/include/bits/text_encoding-data.h
>  create mode 100644 libstdc++-v3/include/std/text_encoding
>  create mode 100755 libstdc++-v3/scripts/gen_text_encoding_data.py
>  create mode 100644 libstdc++-v3/src/c++26/Makefile.am
>  create mode 100644 libstdc++-v3/src/c++26/Makefile.in
>  create mode 100644 libstdc++-v3/src/c++26/text_encoding.cc
>  create mode 100644 libstdc++-v3/testsuite/22_locale/locale/encoding.cc
>  create mode 100644 libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
>  create mode 100644 libstdc++-v3/testsuite/std/text_encoding/cons.cc
>  create mode 100644 libstdc++-v3/testsuite/std/text_encoding/members.cc
>  create mode 100644 libstdc++-v3/testsuite/std/text_encoding/requirements.cc
> 
> diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> index e7cbf0fcf96..f9ba7ef744b 100644
> --- a/libstdc++-v3/acinclude.m4
> +++ b/libstdc++-v3/acinclude.m4
> @@ -49,7 +49,7 @@ AC_DEFUN([GLIBCXX_CONFIGURE], [
>    # Keep these sync'd with the list in Makefile.am.  The first provides an
>    # expandable list at autoconf time; the second provides an expandable list
>    # (i.e., shell variable) at configure time.
> -  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
> +  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/c++26 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
>    SUBDIRS='glibcxx_SUBDIRS'
>  
>    # These need to be absolute paths, yet at the same time need to
> @@ -5821,6 +5821,34 @@ AC_LANG_SAVE
>    AC_LANG_RESTORE
>  ])
>  
> +dnl
> +dnl Check whether the dependencies for std::text_encoding are available.
> +dnl
> +dnl Defines:
> +dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
> +dnl
> +AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
> +AC_LANG_SAVE
> +  AC_LANG_CPLUSPLUS
> +
> +  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
> +  AC_TRY_COMPILE([
> +  #include <locale.h>
> +  #include <langinfo.h>
> +  ],[
> +    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
> +    const char* enc = nl_langinfo_l(CODESET, loc);
> +    freelocale(loc);
> +  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
> +  AC_MSG_RESULT($ac_nl_langinfo_l)
> +  if test "$ac_nl_langinfo_l" = yes; then
> +    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
> +      [Define if nl_langinfo_l should be used for std::text_encoding.])
> +  fi
> +
> +  AC_LANG_RESTORE
> +])
> +
>  # Macros from the top-level gcc directory.
>  m4_include([../config/gc++filt.m4])
>  m4_include([../config/tls.m4])
> diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
> index c8b36333019..c68cac4f345 100644
> --- a/libstdc++-v3/configure.ac
> +++ b/libstdc++-v3/configure.ac
> @@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
>  # For __basic_file::native_handle()
>  GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
>  
> +# For std::text_encoding
> +GLIBCXX_CHECK_TEXT_ENCODING
> +
>  # Define documentation rules conditionally.
>  
>  # See if makeinfo has been installed and is modern enough
> diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
> index c6d6a24eb9e..64152351ed0 100644
> --- a/libstdc++-v3/include/Makefile.am
> +++ b/libstdc++-v3/include/Makefile.am
> @@ -104,6 +104,7 @@ std_headers = \
>  	${std_srcdir}/streambuf \
>  	${std_srcdir}/string \
>  	${std_srcdir}/system_error \
> +	${std_srcdir}/text_encoding \
>  	${std_srcdir}/thread \
>  	${std_srcdir}/unordered_map \
>  	${std_srcdir}/unordered_set \
> @@ -159,6 +160,7 @@ bits_freestanding = \
>  	${bits_srcdir}/stl_raw_storage_iter.h \
>  	${bits_srcdir}/stl_relops.h \
>  	${bits_srcdir}/stl_uninitialized.h \
> +	${bits_srcdir}/text_encoding-data.h \
>  	${bits_srcdir}/version.h \
>  	${bits_srcdir}/string_view.tcc \
>  	${bits_srcdir}/unicode.h \
> diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
> index 621f2a29f50..a2e94217006 100644
> --- a/libstdc++-v3/include/bits/locale_classes.h
> +++ b/libstdc++-v3/include/bits/locale_classes.h
> @@ -40,6 +40,10 @@
>  #include <string>
>  #include <ext/atomicity.h>
>  
> +#ifdef __glibcxx_text_encoding
> +#include <text_encoding>
> +#endif
> +
>  namespace std _GLIBCXX_VISIBILITY(default)
>  {
>  _GLIBCXX_BEGIN_NAMESPACE_VERSION
> @@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      string
>      name() const;
>  
> +#ifdef __glibcxx_text_encoding
> +# if __CHAR_BIT__ == 8
> +    text_encoding
> +    encoding() const;
> +# else
> +    text_encoding
> +    encoding() const = delete;
> +# endif
> +#endif
> +
>      /**
>       *  @brief  Locale equality.
>       *
> diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
> new file mode 100644
> index 00000000000..7ac2e9dc3d9
> --- /dev/null
> +++ b/libstdc++-v3/include/bits/text_encoding-data.h
> @@ -0,0 +1,902 @@
> +// Generated by gen_text_encoding_data.py, do not edit.
> +
> +#ifndef _GLIBCXX_GET_ENCODING_DATA
> +# error "This is not a public header, do not include it directly"
> +#endif
> +
> +  {    3, "US-ASCII" },
> +  {    3, "iso-ir-6" },
> +  {    3, "ANSI_X3.4-1968" },
> +  {    3, "ANSI_X3.4-1986" },
> +  {    3, "ISO_646.irv:1991" },
> +  {    3, "ISO646-US" },
> +  {    3, "us" },
> +  {    3, "IBM367" },
> +  {    3, "cp367" },
> +  {    3, "csASCII" },
> +  {    4, "ISO_8859-1:1987" },
> +  {    4, "iso-ir-100" },
> +  {    4, "ISO_8859-1" },
> +  {    4, "ISO-8859-1" },
> +  {    4, "latin1" },
> +  {    4, "l1" },
> +  {    4, "IBM819" },
> +  {    4, "CP819" },
> +  {    4, "csISOLatin1" },
> +  {    5, "ISO_8859-2:1987" },
> +  {    5, "iso-ir-101" },
> +  {    5, "ISO_8859-2" },
> +  {    5, "ISO-8859-2" },
> +  {    5, "latin2" },
> +  {    5, "l2" },
> +  {    5, "csISOLatin2" },
> +  {    6, "ISO_8859-3:1988" },
> +  {    6, "iso-ir-109" },
> +  {    6, "ISO_8859-3" },
> +  {    6, "ISO-8859-3" },
> +  {    6, "latin3" },
> +  {    6, "l3" },
> +  {    6, "csISOLatin3" },
> +  {    7, "ISO_8859-4:1988" },
> +  {    7, "iso-ir-110" },
> +  {    7, "ISO_8859-4" },
> +  {    7, "ISO-8859-4" },
> +  {    7, "latin4" },
> +  {    7, "l4" },
> +  {    7, "csISOLatin4" },
> +  {    8, "ISO_8859-5:1988" },
> +  {    8, "iso-ir-144" },
> +  {    8, "ISO_8859-5" },
> +  {    8, "ISO-8859-5" },
> +  {    8, "cyrillic" },
> +  {    8, "csISOLatinCyrillic" },
> +  {    9, "ISO_8859-6:1987" },
> +  {    9, "iso-ir-127" },
> +  {    9, "ISO_8859-6" },
> +  {    9, "ISO-8859-6" },
> +  {    9, "ECMA-114" },
> +  {    9, "ASMO-708" },
> +  {    9, "arabic" },
> +  {    9, "csISOLatinArabic" },
> +  {   10, "ISO_8859-7:1987" },
> +  {   10, "iso-ir-126" },
> +  {   10, "ISO_8859-7" },
> +  {   10, "ISO-8859-7" },
> +  {   10, "ELOT_928" },
> +  {   10, "ECMA-118" },
> +  {   10, "greek" },
> +  {   10, "greek8" },
> +  {   10, "csISOLatinGreek" },
> +  {   11, "ISO_8859-8:1988" },
> +  {   11, "iso-ir-138" },
> +  {   11, "ISO_8859-8" },
> +  {   11, "ISO-8859-8" },
> +  {   11, "hebrew" },
> +  {   11, "csISOLatinHebrew" },
> +  {   12, "ISO_8859-9:1989" },
> +  {   12, "iso-ir-148" },
> +  {   12, "ISO_8859-9" },
> +  {   12, "ISO-8859-9" },
> +  {   12, "latin5" },
> +  {   12, "l5" },
> +  {   12, "csISOLatin5" },
> +  {   13, "ISO-8859-10" },
> +  {   13, "iso-ir-157" },
> +  {   13, "l6" },
> +  {   13, "ISO_8859-10:1992" },
> +  {   13, "csISOLatin6" },
> +  {   13, "latin6" },
> +  {   14, "ISO_6937-2-add" },
> +  {   14, "iso-ir-142" },
> +  {   14, "csISOTextComm" },
> +  {   15, "JIS_X0201" },
> +  {   15, "X0201" },
> +  {   15, "csHalfWidthKatakana" },
> +  {   16, "JIS_Encoding" },
> +  {   16, "csJISEncoding" },
> +  {   17, "Shift_JIS" },
> +  {   17, "MS_Kanji" },
> +  {   17, "csShiftJIS" },
> +  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
> +  {   18, "csEUCPkdFmtJapanese" },
> +  {   18, "EUC-JP" },
> +  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
> +  {   19, "csEUCFixWidJapanese" },
> +  {   20, "BS_4730" },
> +  {   20, "iso-ir-4" },
> +  {   20, "ISO646-GB" },
> +  {   20, "gb" },
> +  {   20, "uk" },
> +  {   20, "csISO4UnitedKingdom" },
> +  {   21, "SEN_850200_C" },
> +  {   21, "iso-ir-11" },
> +  {   21, "ISO646-SE2" },
> +  {   21, "se2" },
> +  {   21, "csISO11SwedishForNames" },
> +  {   22, "IT" },
> +  {   22, "iso-ir-15" },
> +  {   22, "ISO646-IT" },
> +  {   22, "csISO15Italian" },
> +  {   23, "ES" },
> +  {   23, "iso-ir-17" },
> +  {   23, "ISO646-ES" },
> +  {   23, "csISO17Spanish" },
> +  {   24, "DIN_66003" },
> +  {   24, "iso-ir-21" },
> +  {   24, "de" },
> +  {   24, "ISO646-DE" },
> +  {   24, "csISO21German" },
> +  {   25, "NS_4551-1" },
> +  {   25, "iso-ir-60" },
> +  {   25, "ISO646-NO" },
> +  {   25, "no" },
> +  {   25, "csISO60DanishNorwegian" },
> +  {   25, "csISO60Norwegian1" },
> +  {   26, "NF_Z_62-010" },
> +  {   26, "iso-ir-69" },
> +  {   26, "ISO646-FR" },
> +  {   26, "fr" },
> +  {   26, "csISO69French" },
> +  {   27, "ISO-10646-UTF-1" },
> +  {   27, "csISO10646UTF1" },
> +  {   28, "ISO_646.basic:1983" },
> +  {   28, "ref" },
> +  {   28, "csISO646basic1983" },
> +  {   29, "INVARIANT" },
> +  {   29, "csINVARIANT" },
> +  {   30, "ISO_646.irv:1983" },
> +  {   30, "iso-ir-2" },
> +  {   30, "irv" },
> +  {   30, "csISO2IntlRefVersion" },
> +  {   31, "NATS-SEFI" },
> +  {   31, "iso-ir-8-1" },
> +  {   31, "csNATSSEFI" },
> +  {   32, "NATS-SEFI-ADD" },
> +  {   32, "iso-ir-8-2" },
> +  {   32, "csNATSSEFIADD" },
> +  {   35, "SEN_850200_B" },
> +  {   35, "iso-ir-10" },
> +  {   35, "FI" },
> +  {   35, "ISO646-FI" },
> +  {   35, "ISO646-SE" },
> +  {   35, "se" },
> +  {   35, "csISO10Swedish" },
> +  {   36, "KS_C_5601-1987" },
> +  {   36, "iso-ir-149" },
> +  {   36, "KS_C_5601-1989" },
> +  {   36, "KSC_5601" },
> +  {   36, "korean" },
> +  {   36, "csKSC56011987" },
> +  {   37, "ISO-2022-KR" },
> +  {   37, "csISO2022KR" },
> +  {   38, "EUC-KR" },
> +  {   38, "csEUCKR" },
> +  {   39, "ISO-2022-JP" },
> +  {   39, "csISO2022JP" },
> +  {   40, "ISO-2022-JP-2" },
> +  {   40, "csISO2022JP2" },
> +  {   41, "JIS_C6220-1969-jp" },
> +  {   41, "JIS_C6220-1969" },
> +  {   41, "iso-ir-13" },
> +  {   41, "katakana" },
> +  {   41, "x0201-7" },
> +  {   41, "csISO13JISC6220jp" },
> +  {   42, "JIS_C6220-1969-ro" },
> +  {   42, "iso-ir-14" },
> +  {   42, "jp" },
> +  {   42, "ISO646-JP" },
> +  {   42, "csISO14JISC6220ro" },
> +  {   43, "PT" },
> +  {   43, "iso-ir-16" },
> +  {   43, "ISO646-PT" },
> +  {   43, "csISO16Portuguese" },
> +  {   44, "greek7-old" },
> +  {   44, "iso-ir-18" },
> +  {   44, "csISO18Greek7Old" },
> +  {   45, "latin-greek" },
> +  {   45, "iso-ir-19" },
> +  {   45, "csISO19LatinGreek" },
> +  {   46, "NF_Z_62-010_(1973)" },
> +  {   46, "iso-ir-25" },
> +  {   46, "ISO646-FR1" },
> +  {   46, "csISO25French" },
> +  {   47, "Latin-greek-1" },
> +  {   47, "iso-ir-27" },
> +  {   47, "csISO27LatinGreek1" },
> +  {   48, "ISO_5427" },
> +  {   48, "iso-ir-37" },
> +  {   48, "csISO5427Cyrillic" },
> +  {   49, "JIS_C6226-1978" },
> +  {   49, "iso-ir-42" },
> +  {   49, "csISO42JISC62261978" },
> +  {   50, "BS_viewdata" },
> +  {   50, "iso-ir-47" },
> +  {   50, "csISO47BSViewdata" },
> +  {   51, "INIS" },
> +  {   51, "iso-ir-49" },
> +  {   51, "csISO49INIS" },
> +  {   52, "INIS-8" },
> +  {   52, "iso-ir-50" },
> +  {   52, "csISO50INIS8" },
> +  {   53, "INIS-cyrillic" },
> +  {   53, "iso-ir-51" },
> +  {   53, "csISO51INISCyrillic" },
> +  {   54, "ISO_5427:1981" },
> +  {   54, "iso-ir-54" },
> +  {   54, "ISO5427Cyrillic1981" },
> +  {   54, "csISO54271981" },
> +  {   55, "ISO_5428:1980" },
> +  {   55, "iso-ir-55" },
> +  {   55, "csISO5428Greek" },
> +  {   56, "GB_1988-80" },
> +  {   56, "iso-ir-57" },
> +  {   56, "cn" },
> +  {   56, "ISO646-CN" },
> +  {   56, "csISO57GB1988" },
> +  {   57, "GB_2312-80" },
> +  {   57, "iso-ir-58" },
> +  {   57, "chinese" },
> +  {   57, "csISO58GB231280" },
> +  {   58, "NS_4551-2" },
> +  {   58, "ISO646-NO2" },
> +  {   58, "iso-ir-61" },
> +  {   58, "no2" },
> +  {   58, "csISO61Norwegian2" },
> +  {   59, "videotex-suppl" },
> +  {   59, "iso-ir-70" },
> +  {   59, "csISO70VideotexSupp1" },
> +  {   60, "PT2" },
> +  {   60, "iso-ir-84" },
> +  {   60, "ISO646-PT2" },
> +  {   60, "csISO84Portuguese2" },
> +  {   61, "ES2" },
> +  {   61, "iso-ir-85" },
> +  {   61, "ISO646-ES2" },
> +  {   61, "csISO85Spanish2" },
> +  {   62, "MSZ_7795.3" },
> +  {   62, "iso-ir-86" },
> +  {   62, "ISO646-HU" },
> +  {   62, "hu" },
> +  {   62, "csISO86Hungarian" },
> +  {   63, "JIS_C6226-1983" },
> +  {   63, "iso-ir-87" },
> +  {   63, "x0208" },
> +  {   63, "JIS_X0208-1983" },
> +  {   63, "csISO87JISX0208" },
> +  {   64, "greek7" },
> +  {   64, "iso-ir-88" },
> +  {   64, "csISO88Greek7" },
> +  {   65, "ASMO_449" },
> +  {   65, "ISO_9036" },
> +  {   65, "arabic7" },
> +  {   65, "iso-ir-89" },
> +  {   65, "csISO89ASMO449" },
> +  {   66, "iso-ir-90" },
> +  {   66, "csISO90" },
> +  {   67, "JIS_C6229-1984-a" },
> +  {   67, "iso-ir-91" },
> +  {   67, "jp-ocr-a" },
> +  {   67, "csISO91JISC62291984a" },
> +  {   68, "JIS_C6229-1984-b" },
> +  {   68, "iso-ir-92" },
> +  {   68, "ISO646-JP-OCR-B" },
> +  {   68, "jp-ocr-b" },
> +  {   68, "csISO92JISC62991984b" },
> +  {   69, "JIS_C6229-1984-b-add" },
> +  {   69, "iso-ir-93" },
> +  {   69, "jp-ocr-b-add" },
> +  {   69, "csISO93JIS62291984badd" },
> +  {   70, "JIS_C6229-1984-hand" },
> +  {   70, "iso-ir-94" },
> +  {   70, "jp-ocr-hand" },
> +  {   70, "csISO94JIS62291984hand" },
> +  {   71, "JIS_C6229-1984-hand-add" },
> +  {   71, "iso-ir-95" },
> +  {   71, "jp-ocr-hand-add" },
> +  {   71, "csISO95JIS62291984handadd" },
> +  {   72, "JIS_C6229-1984-kana" },
> +  {   72, "iso-ir-96" },
> +  {   72, "csISO96JISC62291984kana" },
> +  {   73, "ISO_2033-1983" },
> +  {   73, "iso-ir-98" },
> +  {   73, "e13b" },
> +  {   73, "csISO2033" },
> +  {   74, "ANSI_X3.110-1983" },
> +  {   74, "iso-ir-99" },
> +  {   74, "CSA_T500-1983" },
> +  {   74, "NAPLPS" },
> +  {   74, "csISO99NAPLPS" },
> +  {   75, "T.61-7bit" },
> +  {   75, "iso-ir-102" },
> +  {   75, "csISO102T617bit" },
> +  {   76, "T.61-8bit" },
> +  {   76, "T.61" },
> +  {   76, "iso-ir-103" },
> +  {   76, "csISO103T618bit" },
> +  {   77, "ECMA-cyrillic" },
> +  {   77, "iso-ir-111" },
> +  {   77, "KOI8-E" },
> +  {   77, "csISO111ECMACyrillic" },
> +  {   78, "CSA_Z243.4-1985-1" },
> +  {   78, "iso-ir-121" },
> +  {   78, "ISO646-CA" },
> +  {   78, "csa7-1" },
> +  {   78, "csa71" },
> +  {   78, "ca" },
> +  {   78, "csISO121Canadian1" },
> +  {   79, "CSA_Z243.4-1985-2" },
> +  {   79, "iso-ir-122" },
> +  {   79, "ISO646-CA2" },
> +  {   79, "csa7-2" },
> +  {   79, "csa72" },
> +  {   79, "csISO122Canadian2" },
> +  {   80, "CSA_Z243.4-1985-gr" },
> +  {   80, "iso-ir-123" },
> +  {   80, "csISO123CSAZ24341985gr" },
> +  {   81, "ISO_8859-6-E" },
> +  {   81, "csISO88596E" },
> +  {   81, "ISO-8859-6-E" },
> +  {   82, "ISO_8859-6-I" },
> +  {   82, "csISO88596I" },
> +  {   82, "ISO-8859-6-I" },
> +  {   83, "T.101-G2" },
> +  {   83, "iso-ir-128" },
> +  {   83, "csISO128T101G2" },
> +  {   84, "ISO_8859-8-E" },
> +  {   84, "csISO88598E" },
> +  {   84, "ISO-8859-8-E" },
> +  {   85, "ISO_8859-8-I" },
> +  {   85, "csISO88598I" },
> +  {   85, "ISO-8859-8-I" },
> +  {   86, "CSN_369103" },
> +  {   86, "iso-ir-139" },
> +  {   86, "csISO139CSN369103" },
> +  {   87, "JUS_I.B1.002" },
> +  {   87, "iso-ir-141" },
> +  {   87, "ISO646-YU" },
> +  {   87, "js" },
> +  {   87, "yu" },
> +  {   87, "csISO141JUSIB1002" },
> +  {   88, "IEC_P27-1" },
> +  {   88, "iso-ir-143" },
> +  {   88, "csISO143IECP271" },
> +  {   89, "JUS_I.B1.003-serb" },
> +  {   89, "iso-ir-146" },
> +  {   89, "serbian" },
> +  {   89, "csISO146Serbian" },
> +  {   90, "JUS_I.B1.003-mac" },
> +  {   90, "macedonian" },
> +  {   90, "iso-ir-147" },
> +  {   90, "csISO147Macedonian" },
> +  {   91, "greek-ccitt" },
> +  {   91, "iso-ir-150" },
> +  {   91, "csISO150" },
> +  {   91, "csISO150GreekCCITT" },
> +  {   92, "NC_NC00-10:81" },
> +  {   92, "cuba" },
> +  {   92, "iso-ir-151" },
> +  {   92, "ISO646-CU" },
> +  {   92, "csISO151Cuba" },
> +  {   93, "ISO_6937-2-25" },
> +  {   93, "iso-ir-152" },
> +  {   93, "csISO6937Add" },
> +  {   94, "GOST_19768-74" },
> +  {   94, "ST_SEV_358-88" },
> +  {   94, "iso-ir-153" },
> +  {   94, "csISO153GOST1976874" },
> +  {   95, "ISO_8859-supp" },
> +  {   95, "iso-ir-154" },
> +  {   95, "latin1-2-5" },
> +  {   95, "csISO8859Supp" },
> +  {   96, "ISO_10367-box" },
> +  {   96, "iso-ir-155" },
> +  {   96, "csISO10367Box" },
> +  {   97, "latin-lap" },
> +  {   97, "lap" },
> +  {   97, "iso-ir-158" },
> +  {   97, "csISO158Lap" },
> +  {   98, "JIS_X0212-1990" },
> +  {   98, "x0212" },
> +  {   98, "iso-ir-159" },
> +  {   98, "csISO159JISX02121990" },
> +  {   99, "DS_2089" },
> +  {   99, "DS2089" },
> +  {   99, "ISO646-DK" },
> +  {   99, "dk" },
> +  {   99, "csISO646Danish" },
> +  {  100, "us-dk" },
> +  {  100, "csUSDK" },
> +  {  101, "dk-us" },
> +  {  101, "csDKUS" },
> +  {  102, "KSC5636" },
> +  {  102, "ISO646-KR" },
> +  {  102, "csKSC5636" },
> +  {  103, "UNICODE-1-1-UTF-7" },
> +  {  103, "csUnicode11UTF7" },
> +  {  104, "ISO-2022-CN" },
> +  {  104, "csISO2022CN" },
> +  {  105, "ISO-2022-CN-EXT" },
> +  {  105, "csISO2022CNEXT" },
> +#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
> +  {  106, "UTF-8" },
> +  {  106, "csUTF8" },
> +  {  109, "ISO-8859-13" },
> +  {  109, "csISO885913" },
> +  {  110, "ISO-8859-14" },
> +  {  110, "iso-ir-199" },
> +  {  110, "ISO_8859-14:1998" },
> +  {  110, "ISO_8859-14" },
> +  {  110, "latin8" },
> +  {  110, "iso-celtic" },
> +  {  110, "l8" },
> +  {  110, "csISO885914" },
> +  {  111, "ISO-8859-15" },
> +  {  111, "ISO_8859-15" },
> +  {  111, "Latin-9" },
> +  {  111, "csISO885915" },
> +  {  112, "ISO-8859-16" },
> +  {  112, "iso-ir-226" },
> +  {  112, "ISO_8859-16:2001" },
> +  {  112, "ISO_8859-16" },
> +  {  112, "latin10" },
> +  {  112, "l10" },
> +  {  112, "csISO885916" },
> +  {  113, "GBK" },
> +  {  113, "CP936" },
> +  {  113, "MS936" },
> +  {  113, "windows-936" },
> +  {  113, "csGBK" },
> +  {  114, "GB18030" },
> +  {  114, "csGB18030" },
> +  {  115, "OSD_EBCDIC_DF04_15" },
> +  {  115, "csOSDEBCDICDF0415" },
> +  {  116, "OSD_EBCDIC_DF03_IRV" },
> +  {  116, "csOSDEBCDICDF03IRV" },
> +  {  117, "OSD_EBCDIC_DF04_1" },
> +  {  117, "csOSDEBCDICDF041" },
> +  {  118, "ISO-11548-1" },
> +  {  118, "ISO_11548-1" },
> +  {  118, "ISO_TR_11548-1" },
> +  {  118, "csISO115481" },
> +  {  119, "KZ-1048" },
> +  {  119, "STRK1048-2002" },
> +  {  119, "RK1048" },
> +  {  119, "csKZ1048" },
> +  { 1000, "ISO-10646-UCS-2" },
> +  { 1000, "csUnicode" },
> +  { 1001, "ISO-10646-UCS-4" },
> +  { 1001, "csUCS4" },
> +  { 1002, "ISO-10646-UCS-Basic" },
> +  { 1002, "csUnicodeASCII" },
> +  { 1003, "ISO-10646-Unicode-Latin1" },
> +  { 1003, "csUnicodeLatin1" },
> +  { 1003, "ISO-10646" },
> +  { 1004, "ISO-10646-J-1" },
> +  { 1004, "csUnicodeJapanese" },
> +  { 1005, "ISO-Unicode-IBM-1261" },
> +  { 1005, "csUnicodeIBM1261" },
> +  { 1006, "ISO-Unicode-IBM-1268" },
> +  { 1006, "csUnicodeIBM1268" },
> +  { 1007, "ISO-Unicode-IBM-1276" },
> +  { 1007, "csUnicodeIBM1276" },
> +  { 1008, "ISO-Unicode-IBM-1264" },
> +  { 1008, "csUnicodeIBM1264" },
> +  { 1009, "ISO-Unicode-IBM-1265" },
> +  { 1009, "csUnicodeIBM1265" },
> +  { 1010, "UNICODE-1-1" },
> +  { 1010, "csUnicode11" },
> +  { 1011, "SCSU" },
> +  { 1011, "csSCSU" },
> +  { 1012, "UTF-7" },
> +  { 1012, "csUTF7" },
> +  { 1013, "UTF-16BE" },
> +  { 1013, "csUTF16BE" },
> +  { 1014, "UTF-16LE" },
> +  { 1014, "csUTF16LE" },
> +  { 1015, "UTF-16" },
> +  { 1015, "csUTF16" },
> +  { 1016, "CESU-8" },
> +  { 1016, "csCESU8" },
> +  { 1016, "csCESU-8" },
> +  { 1017, "UTF-32" },
> +  { 1017, "csUTF32" },
> +  { 1018, "UTF-32BE" },
> +  { 1018, "csUTF32BE" },
> +  { 1019, "UTF-32LE" },
> +  { 1019, "csUTF32LE" },
> +  { 1020, "BOCU-1" },
> +  { 1020, "csBOCU1" },
> +  { 1020, "csBOCU-1" },
> +  { 1021, "UTF-7-IMAP" },
> +  { 1021, "csUTF7IMAP" },
> +  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
> +  { 2000, "csWindows30Latin1" },
> +  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
> +  { 2001, "csWindows31Latin1" },
> +  { 2002, "ISO-8859-2-Windows-Latin-2" },
> +  { 2002, "csWindows31Latin2" },
> +  { 2003, "ISO-8859-9-Windows-Latin-5" },
> +  { 2003, "csWindows31Latin5" },
> +  { 2004, "hp-roman8" },
> +  { 2004, "roman8" },
> +  { 2004, "r8" },
> +  { 2004, "csHPRoman8" },
> +  { 2005, "Adobe-Standard-Encoding" },
> +  { 2005, "csAdobeStandardEncoding" },
> +  { 2006, "Ventura-US" },
> +  { 2006, "csVenturaUS" },
> +  { 2007, "Ventura-International" },
> +  { 2007, "csVenturaInternational" },
> +  { 2008, "DEC-MCS" },
> +  { 2008, "dec" },
> +  { 2008, "csDECMCS" },
> +  { 2009, "IBM850" },
> +  { 2009, "cp850" },
> +  { 2009, "850" },
> +  { 2009, "csPC850Multilingual" },
> +  { 2010, "IBM852" },
> +  { 2010, "cp852" },
> +  { 2010, "852" },
> +  { 2010, "csPCp852" },
> +  { 2011, "IBM437" },
> +  { 2011, "cp437" },
> +  { 2011, "437" },
> +  { 2011, "csPC8CodePage437" },
> +  { 2012, "PC8-Danish-Norwegian" },
> +  { 2012, "csPC8DanishNorwegian" },
> +  { 2013, "IBM862" },
> +  { 2013, "cp862" },
> +  { 2013, "862" },
> +  { 2013, "csPC862LatinHebrew" },
> +  { 2014, "PC8-Turkish" },
> +  { 2014, "csPC8Turkish" },
> +  { 2015, "IBM-Symbols" },
> +  { 2015, "csIBMSymbols" },
> +  { 2016, "IBM-Thai" },
> +  { 2016, "csIBMThai" },
> +  { 2017, "HP-Legal" },
> +  { 2017, "csHPLegal" },
> +  { 2018, "HP-Pi-font" },
> +  { 2018, "csHPPiFont" },
> +  { 2019, "HP-Math8" },
> +  { 2019, "csHPMath8" },
> +  { 2020, "Adobe-Symbol-Encoding" },
> +  { 2020, "csHPPSMath" },
> +  { 2021, "HP-DeskTop" },
> +  { 2021, "csHPDesktop" },
> +  { 2022, "Ventura-Math" },
> +  { 2022, "csVenturaMath" },
> +  { 2023, "Microsoft-Publishing" },
> +  { 2023, "csMicrosoftPublishing" },
> +  { 2024, "Windows-31J" },
> +  { 2024, "csWindows31J" },
> +  { 2025, "GB2312" },
> +  { 2025, "csGB2312" },
> +  { 2026, "Big5" },
> +  { 2026, "csBig5" },
> +  { 2027, "macintosh" },
> +  { 2027, "mac" },
> +  { 2027, "csMacintosh" },
> +  { 2028, "IBM037" },
> +  { 2028, "cp037" },
> +  { 2028, "ebcdic-cp-us" },
> +  { 2028, "ebcdic-cp-ca" },
> +  { 2028, "ebcdic-cp-wt" },
> +  { 2028, "ebcdic-cp-nl" },
> +  { 2028, "csIBM037" },
> +  { 2029, "IBM038" },
> +  { 2029, "EBCDIC-INT" },
> +  { 2029, "cp038" },
> +  { 2029, "csIBM038" },
> +  { 2030, "IBM273" },
> +  { 2030, "CP273" },
> +  { 2030, "csIBM273" },
> +  { 2031, "IBM274" },
> +  { 2031, "EBCDIC-BE" },
> +  { 2031, "CP274" },
> +  { 2031, "csIBM274" },
> +  { 2032, "IBM275" },
> +  { 2032, "EBCDIC-BR" },
> +  { 2032, "cp275" },
> +  { 2032, "csIBM275" },
> +  { 2033, "IBM277" },
> +  { 2033, "EBCDIC-CP-DK" },
> +  { 2033, "EBCDIC-CP-NO" },
> +  { 2033, "csIBM277" },
> +  { 2034, "IBM278" },
> +  { 2034, "CP278" },
> +  { 2034, "ebcdic-cp-fi" },
> +  { 2034, "ebcdic-cp-se" },
> +  { 2034, "csIBM278" },
> +  { 2035, "IBM280" },
> +  { 2035, "CP280" },
> +  { 2035, "ebcdic-cp-it" },
> +  { 2035, "csIBM280" },
> +  { 2036, "IBM281" },
> +  { 2036, "EBCDIC-JP-E" },
> +  { 2036, "cp281" },
> +  { 2036, "csIBM281" },
> +  { 2037, "IBM284" },
> +  { 2037, "CP284" },
> +  { 2037, "ebcdic-cp-es" },
> +  { 2037, "csIBM284" },
> +  { 2038, "IBM285" },
> +  { 2038, "CP285" },
> +  { 2038, "ebcdic-cp-gb" },
> +  { 2038, "csIBM285" },
> +  { 2039, "IBM290" },
> +  { 2039, "cp290" },
> +  { 2039, "EBCDIC-JP-kana" },
> +  { 2039, "csIBM290" },
> +  { 2040, "IBM297" },
> +  { 2040, "cp297" },
> +  { 2040, "ebcdic-cp-fr" },
> +  { 2040, "csIBM297" },
> +  { 2041, "IBM420" },
> +  { 2041, "cp420" },
> +  { 2041, "ebcdic-cp-ar1" },
> +  { 2041, "csIBM420" },
> +  { 2042, "IBM423" },
> +  { 2042, "cp423" },
> +  { 2042, "ebcdic-cp-gr" },
> +  { 2042, "csIBM423" },
> +  { 2043, "IBM424" },
> +  { 2043, "cp424" },
> +  { 2043, "ebcdic-cp-he" },
> +  { 2043, "csIBM424" },
> +  { 2044, "IBM500" },
> +  { 2044, "CP500" },
> +  { 2044, "ebcdic-cp-be" },
> +  { 2044, "ebcdic-cp-ch" },
> +  { 2044, "csIBM500" },
> +  { 2045, "IBM851" },
> +  { 2045, "cp851" },
> +  { 2045, "851" },
> +  { 2045, "csIBM851" },
> +  { 2046, "IBM855" },
> +  { 2046, "cp855" },
> +  { 2046, "855" },
> +  { 2046, "csIBM855" },
> +  { 2047, "IBM857" },
> +  { 2047, "cp857" },
> +  { 2047, "857" },
> +  { 2047, "csIBM857" },
> +  { 2048, "IBM860" },
> +  { 2048, "cp860" },
> +  { 2048, "860" },
> +  { 2048, "csIBM860" },
> +  { 2049, "IBM861" },
> +  { 2049, "cp861" },
> +  { 2049, "861" },
> +  { 2049, "cp-is" },
> +  { 2049, "csIBM861" },
> +  { 2050, "IBM863" },
> +  { 2050, "cp863" },
> +  { 2050, "863" },
> +  { 2050, "csIBM863" },
> +  { 2051, "IBM864" },
> +  { 2051, "cp864" },
> +  { 2051, "csIBM864" },
> +  { 2052, "IBM865" },
> +  { 2052, "cp865" },
> +  { 2052, "865" },
> +  { 2052, "csIBM865" },
> +  { 2053, "IBM868" },
> +  { 2053, "CP868" },
> +  { 2053, "cp-ar" },
> +  { 2053, "csIBM868" },
> +  { 2054, "IBM869" },
> +  { 2054, "cp869" },
> +  { 2054, "869" },
> +  { 2054, "cp-gr" },
> +  { 2054, "csIBM869" },
> +  { 2055, "IBM870" },
> +  { 2055, "CP870" },
> +  { 2055, "ebcdic-cp-roece" },
> +  { 2055, "ebcdic-cp-yu" },
> +  { 2055, "csIBM870" },
> +  { 2056, "IBM871" },
> +  { 2056, "CP871" },
> +  { 2056, "ebcdic-cp-is" },
> +  { 2056, "csIBM871" },
> +  { 2057, "IBM880" },
> +  { 2057, "cp880" },
> +  { 2057, "EBCDIC-Cyrillic" },
> +  { 2057, "csIBM880" },
> +  { 2058, "IBM891" },
> +  { 2058, "cp891" },
> +  { 2058, "csIBM891" },
> +  { 2059, "IBM903" },
> +  { 2059, "cp903" },
> +  { 2059, "csIBM903" },
> +  { 2060, "IBM904" },
> +  { 2060, "cp904" },
> +  { 2060, "904" },
> +  { 2060, "csIBBM904" },
> +  { 2061, "IBM905" },
> +  { 2061, "CP905" },
> +  { 2061, "ebcdic-cp-tr" },
> +  { 2061, "csIBM905" },
> +  { 2062, "IBM918" },
> +  { 2062, "CP918" },
> +  { 2062, "ebcdic-cp-ar2" },
> +  { 2062, "csIBM918" },
> +  { 2063, "IBM1026" },
> +  { 2063, "CP1026" },
> +  { 2063, "csIBM1026" },
> +  { 2064, "EBCDIC-AT-DE" },
> +  { 2064, "csIBMEBCDICATDE" },
> +  { 2065, "EBCDIC-AT-DE-A" },
> +  { 2065, "csEBCDICATDEA" },
> +  { 2066, "EBCDIC-CA-FR" },
> +  { 2066, "csEBCDICCAFR" },
> +  { 2067, "EBCDIC-DK-NO" },
> +  { 2067, "csEBCDICDKNO" },
> +  { 2068, "EBCDIC-DK-NO-A" },
> +  { 2068, "csEBCDICDKNOA" },
> +  { 2069, "EBCDIC-FI-SE" },
> +  { 2069, "csEBCDICFISE" },
> +  { 2070, "EBCDIC-FI-SE-A" },
> +  { 2070, "csEBCDICFISEA" },
> +  { 2071, "EBCDIC-FR" },
> +  { 2071, "csEBCDICFR" },
> +  { 2072, "EBCDIC-IT" },
> +  { 2072, "csEBCDICIT" },
> +  { 2073, "EBCDIC-PT" },
> +  { 2073, "csEBCDICPT" },
> +  { 2074, "EBCDIC-ES" },
> +  { 2074, "csEBCDICES" },
> +  { 2075, "EBCDIC-ES-A" },
> +  { 2075, "csEBCDICESA" },
> +  { 2076, "EBCDIC-ES-S" },
> +  { 2076, "csEBCDICESS" },
> +  { 2077, "EBCDIC-UK" },
> +  { 2077, "csEBCDICUK" },
> +  { 2078, "EBCDIC-US" },
> +  { 2078, "csEBCDICUS" },
> +  { 2079, "UNKNOWN-8BIT" },
> +  { 2079, "csUnknown8BiT" },
> +  { 2080, "MNEMONIC" },
> +  { 2080, "csMnemonic" },
> +  { 2081, "MNEM" },
> +  { 2081, "csMnem" },
> +  { 2082, "VISCII" },
> +  { 2082, "csVISCII" },
> +  { 2083, "VIQR" },
> +  { 2083, "csVIQR" },
> +  { 2084, "KOI8-R" },
> +  { 2084, "csKOI8R" },
> +  { 2085, "HZ-GB-2312" },
> +  { 2086, "IBM866" },
> +  { 2086, "cp866" },
> +  { 2086, "866" },
> +  { 2086, "csIBM866" },
> +  { 2087, "IBM775" },
> +  { 2087, "cp775" },
> +  { 2087, "csPC775Baltic" },
> +  { 2088, "KOI8-U" },
> +  { 2088, "csKOI8U" },
> +  { 2089, "IBM00858" },
> +  { 2089, "CCSID00858" },
> +  { 2089, "CP00858" },
> +  { 2089, "PC-Multilingual-850+euro" },
> +  { 2089, "csIBM00858" },
> +  { 2090, "IBM00924" },
> +  { 2090, "CCSID00924" },
> +  { 2090, "CP00924" },
> +  { 2090, "ebcdic-Latin9--euro" },
> +  { 2090, "csIBM00924" },
> +  { 2091, "IBM01140" },
> +  { 2091, "CCSID01140" },
> +  { 2091, "CP01140" },
> +  { 2091, "ebcdic-us-37+euro" },
> +  { 2091, "csIBM01140" },
> +  { 2092, "IBM01141" },
> +  { 2092, "CCSID01141" },
> +  { 2092, "CP01141" },
> +  { 2092, "ebcdic-de-273+euro" },
> +  { 2092, "csIBM01141" },
> +  { 2093, "IBM01142" },
> +  { 2093, "CCSID01142" },
> +  { 2093, "CP01142" },
> +  { 2093, "ebcdic-dk-277+euro" },
> +  { 2093, "ebcdic-no-277+euro" },
> +  { 2093, "csIBM01142" },
> +  { 2094, "IBM01143" },
> +  { 2094, "CCSID01143" },
> +  { 2094, "CP01143" },
> +  { 2094, "ebcdic-fi-278+euro" },
> +  { 2094, "ebcdic-se-278+euro" },
> +  { 2094, "csIBM01143" },
> +  { 2095, "IBM01144" },
> +  { 2095, "CCSID01144" },
> +  { 2095, "CP01144" },
> +  { 2095, "ebcdic-it-280+euro" },
> +  { 2095, "csIBM01144" },
> +  { 2096, "IBM01145" },
> +  { 2096, "CCSID01145" },
> +  { 2096, "CP01145" },
> +  { 2096, "ebcdic-es-284+euro" },
> +  { 2096, "csIBM01145" },
> +  { 2097, "IBM01146" },
> +  { 2097, "CCSID01146" },
> +  { 2097, "CP01146" },
> +  { 2097, "ebcdic-gb-285+euro" },
> +  { 2097, "csIBM01146" },
> +  { 2098, "IBM01147" },
> +  { 2098, "CCSID01147" },
> +  { 2098, "CP01147" },
> +  { 2098, "ebcdic-fr-297+euro" },
> +  { 2098, "csIBM01147" },
> +  { 2099, "IBM01148" },
> +  { 2099, "CCSID01148" },
> +  { 2099, "CP01148" },
> +  { 2099, "ebcdic-international-500+euro" },
> +  { 2099, "csIBM01148" },
> +  { 2100, "IBM01149" },
> +  { 2100, "CCSID01149" },
> +  { 2100, "CP01149" },
> +  { 2100, "ebcdic-is-871+euro" },
> +  { 2100, "csIBM01149" },
> +  { 2101, "Big5-HKSCS" },
> +  { 2101, "csBig5HKSCS" },
> +  { 2102, "IBM1047" },
> +  { 2102, "IBM-1047" },
> +  { 2102, "csIBM1047" },
> +  { 2103, "PTCP154" },
> +  { 2103, "csPTCP154" },
> +  { 2103, "PT154" },
> +  { 2103, "CP154" },
> +  { 2103, "Cyrillic-Asian" },
> +  { 2104, "Amiga-1251" },
> +  { 2104, "Ami1251" },
> +  { 2104, "Amiga1251" },
> +  { 2104, "Ami-1251" },
> +  { 2104, "csAmiga1251" },
> +  { 2104, "(Aliases" },
> +  { 2104, "are" },
> +  { 2104, "provided" },
> +  { 2104, "for" },
> +  { 2104, "historical" },
> +  { 2104, "reasons" },
> +  { 2104, "and" },
> +  { 2104, "should" },
> +  { 2104, "not" },
> +  { 2104, "be" },
> +  { 2104, "used)" },
> +  { 2104, "[Malyshev]" },
> +  { 2105, "KOI7-switched" },
> +  { 2105, "csKOI7switched" },
> +  { 2106, "BRF" },
> +  { 2106, "csBRF" },
> +  { 2107, "TSCII" },
> +  { 2107, "csTSCII" },
> +  { 2108, "CP51932" },
> +  { 2108, "csCP51932" },
> +  { 2109, "windows-874" },
> +  { 2109, "cswindows874" },
> +  { 2250, "windows-1250" },
> +  { 2250, "cswindows1250" },
> +  { 2251, "windows-1251" },
> +  { 2251, "cswindows1251" },
> +  { 2252, "windows-1252" },
> +  { 2252, "cswindows1252" },
> +  { 2253, "windows-1253" },
> +  { 2253, "cswindows1253" },
> +  { 2254, "windows-1254" },
> +  { 2254, "cswindows1254" },
> +  { 2255, "windows-1255" },
> +  { 2255, "cswindows1255" },
> +  { 2256, "windows-1256" },
> +  { 2256, "cswindows1256" },
> +  { 2257, "windows-1257" },
> +  { 2257, "cswindows1257" },
> +  { 2258, "windows-1258" },
> +  { 2258, "cswindows1258" },
> +  { 2259, "TIS-620" },
> +  { 2259, "csTIS620" },
> +  { 2259, "ISO-8859-11" },
> +  { 2260, "CP50220" },
> +  { 2260, "csCP50220" },
> +
> +#undef _GLIBCXX_GET_ENCODING_DATA
> diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
> index f1b2b359bdf..8bc55e9c136 100644
> --- a/libstdc++-v3/include/bits/unicode.h
> +++ b/libstdc++-v3/include/bits/unicode.h
> @@ -32,7 +32,8 @@
>  
>  #if __cplusplus >= 202002L
>  #include <array>
> -#include <bit>
> +#include <bit>      // bit_width
> +#include <charconv> // __detail::__from_chars_alnum_to_val_table
>  #include <cstdint>
>  #include <bits/stl_algo.h>
>  #include <bits/stl_iterator.h>
> @@ -986,7 +987,7 @@ inline namespace __v15_1_0
>        return __n;
>      }
>  
> -    template<typename _CharT>
> +  template<typename _CharT>
>      consteval bool
>      __literal_encoding_is_unicode()
>      {
> @@ -1056,6 +1057,54 @@ inline namespace __v15_1_0
>    __literal_encoding_is_utf8()
>    { return __literal_encoding_is_unicode<char>(); }
>  
> +  consteval bool
> +  __literal_encoding_is_extended_ascii()
> +  {
> +    return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
> +	     && 'a' == 0x61 && 'z' == 0x7a;
> +  }

This function seems unused now.

> +
> +  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
> +  constexpr bool
> +  __charset_alias_match(string_view __a, string_view __b)
> +  {
> +    // Map alphanumeric chars to their base 64 value, everything else to 127.
> +    auto __map = [](char __c, bool& __num) -> unsigned char {
> +      using __detail::__from_chars_alnum_to_val_table;
> +      if (__c == '0') [[unlikely]]
> +	return __num ? 0 : 127;
> +      auto __v = __from_chars_alnum_to_val_table<false>::value.__data[__c];

Maybe it'd be more concise to use the accessor function
__from_chars_alnum_to_val here (so e.g. the caller doesn't have to pass
_DecOnly=false explicitly)?

> +      __num = __v < 10;
> +      return __v;
> +    };
> +
> +    auto __ptr_a = __a.begin(), __end_a = __a.end();
> +    auto __ptr_b = __b.begin(), __end_b = __b.end();
> +    bool __num_a = false, __num_b = false;
> +
> +    while (true)
> +      {
> +	// Find the value of the next alphanumeric character in each string.
> +	unsigned char __val_a, __val_b;
> +	while (__ptr_a != __end_a
> +		 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
> +	  ++__ptr_a;
> +	while (__ptr_b != __end_b
> +		 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
> +	  ++__ptr_b;
> +	// Stop when we reach the end of a string, or get a mismatch.
> +	if (__ptr_a == __end_a)
> +	  return __ptr_b == __end_b;
> +	else if (__ptr_b == __end_b)
> +	  return false;
> +	else if (__val_a != __val_b)
> +	  return false; // Found non-matching characters.
> +	++__ptr_a;
> +	++__ptr_b;
> +      }
> +    return true;
> +  }
> +
>  } // namespace __unicode
>  
>  _GLIBCXX_END_NAMESPACE_VERSION
> diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
> index afbec6c3e6a..8fb8a2877ee 100644
> --- a/libstdc++-v3/include/bits/version.def
> +++ b/libstdc++-v3/include/bits/version.def
> @@ -1751,6 +1751,16 @@ ftms = {
>    };
>  };
>  
> +ftms = {
> +  name = text_encoding;
> +  values = {
> +    v = 202306;
> +    cxxmin = 26;
> +    hosted = yes;
> +    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
> +  };
> +};
> +
>  ftms = {
>    name = to_string;
>    values = {
> diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
> index 9688b246ef4..9ba99deeda6 100644
> --- a/libstdc++-v3/include/bits/version.h
> +++ b/libstdc++-v3/include/bits/version.h
> @@ -2137,6 +2137,17 @@
>  #undef __glibcxx_want_saturation_arithmetic
>  
>  // from version.def line 1755
> +#if !defined(__cpp_lib_text_encoding)
> +# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
> +#  define __glibcxx_text_encoding 202306L
> +#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
> +#   define __cpp_lib_text_encoding 202306L
> +#  endif
> +# endif
> +#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
> +#undef __glibcxx_want_text_encoding
> +
> +// from version.def line 1765
>  #if !defined(__cpp_lib_to_string)
>  # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
>  #  define __glibcxx_to_string 202306L
> @@ -2147,7 +2158,7 @@
>  #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
>  #undef __glibcxx_want_to_string
>  
> -// from version.def line 1765
> +// from version.def line 1775
>  #if !defined(__cpp_lib_generator)
>  # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
>  #  define __glibcxx_generator 202207L
> diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
> new file mode 100644
> index 00000000000..df8a09c5810
> --- /dev/null
> +++ b/libstdc++-v3/include/std/text_encoding
> @@ -0,0 +1,704 @@
> +// <text_encoding> -*- C++ -*-
> +
> +// Copyright The GNU Toolchain Authors.
> +//
> +// This file is part of the GNU ISO C++ Library.  This library is free
> +// software; you can redistribute it and/or modify it under the
> +// terms of the GNU General Public License as published by the
> +// Free Software Foundation; either version 3, or (at your option)
> +// any later version.
> +
> +// This library is distributed in the hope that it will be useful,
> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +// GNU General Public License for more details.
> +
> +// Under Section 7 of GPL version 3, you are granted additional
> +// permissions described in the GCC Runtime Library Exception, version
> +// 3.1, as published by the Free Software Foundation.
> +
> +// You should have received a copy of the GNU General Public License and
> +// a copy of the GCC Runtime Library Exception along with this program;
> +// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +// <http://www.gnu.org/licenses/>.
> +
> +/** @file include/text_encoding
> + *  This is a Standard C++ Library header.
> + */
> +
> +#ifndef _GLIBCXX_TEXT_ENCODING
> +#define _GLIBCXX_TEXT_ENCODING
> +
> +#pragma GCC system_header
> +
> +#include <bits/requires_hosted.h>
> +
> +#define __glibcxx_want_text_encoding
> +#include <bits/version.h>
> +
> +#ifdef __cpp_lib_text_encoding
> +#include <compare>
> +#include <string_view>
> +#include <bits/functional_hash.h> // hash
> +#include <bits/ranges_util.h>     // view_interface
> +#include <bits/unicode.h>         // __charset_alias_match
> +#include <ext/numeric_traits.h>   // __int_traits
> +
> +namespace std _GLIBCXX_VISIBILITY(default)
> +{
> +_GLIBCXX_BEGIN_NAMESPACE_VERSION
> +
> +  /**
> +   * @brief An interface for accessing the IANA Character Sets registry.
> +   * @ingroup locales
> +   * @since C++23
> +   */
> +  struct text_encoding
> +  {
> +  private:
> +    struct _Rep
> +    {
> +      using id = __INT_LEAST32_TYPE__;
> +      id _M_id;
> +      const char* _M_name;
> +
> +      friend constexpr bool
> +      operator<(const _Rep& __r, id __m) noexcept
> +      { return __r._M_id < __m; }
> +
> +      friend constexpr bool
> +      operator==(const _Rep& __r, string_view __name) noexcept
> +      { return __r._M_name == __name; }
> +    };
> +
> +  public:
> +    static constexpr size_t max_name_length = 63;
> +
> +    enum class id : _Rep::id
> +    {
> +      other = 1,
> +      unknown = 2,
> +      ASCII = 3,
> +      ISOLatin1 = 4,
> +      ISOLatin2 = 5,
> +      ISOLatin3 = 6,
> +      ISOLatin4 = 7,
> +      ISOLatinCyrillic = 8,
> +      ISOLatinArabic = 9,
> +      ISOLatinGreek = 10,
> +      ISOLatinHebrew = 11,
> +      ISOLatin5 = 12,
> +      ISOLatin6 = 13,
> +      ISOTextComm = 14,
> +      HalfWidthKatakana = 15,
> +      JISEncoding = 16,
> +      ShiftJIS = 17,
> +      EUCPkdFmtJapanese = 18,
> +      EUCFixWidJapanese = 19,
> +      ISO4UnitedKingdom = 20,
> +      ISO11SwedishForNames = 21,
> +      ISO15Italian = 22,
> +      ISO17Spanish = 23,
> +      ISO21German = 24,
> +      ISO60DanishNorwegian = 25,
> +      ISO69French = 26,
> +      ISO10646UTF1 = 27,
> +      ISO646basic1983 = 28,
> +      INVARIANT = 29,
> +      ISO2IntlRefVersion = 30,
> +      NATSSEFI = 31,
> +      NATSSEFIADD = 32,
> +      ISO10Swedish = 35,
> +      KSC56011987 = 36,
> +      ISO2022KR = 37,
> +      EUCKR = 38,
> +      ISO2022JP = 39,
> +      ISO2022JP2 = 40,
> +      ISO13JISC6220jp = 41,
> +      ISO14JISC6220ro = 42,
> +      ISO16Portuguese = 43,
> +      ISO18Greek7Old = 44,
> +      ISO19LatinGreek = 45,
> +      ISO25French = 46,
> +      ISO27LatinGreek1 = 47,
> +      ISO5427Cyrillic = 48,
> +      ISO42JISC62261978 = 49,
> +      ISO47BSViewdata = 50,
> +      ISO49INIS = 51,
> +      ISO50INIS8 = 52,
> +      ISO51INISCyrillic = 53,
> +      ISO54271981 = 54,
> +      ISO5428Greek = 55,
> +      ISO57GB1988 = 56,
> +      ISO58GB231280 = 57,
> +      ISO61Norwegian2 = 58,
> +      ISO70VideotexSupp1 = 59,
> +      ISO84Portuguese2 = 60,
> +      ISO85Spanish2 = 61,
> +      ISO86Hungarian = 62,
> +      ISO87JISX0208 = 63,
> +      ISO88Greek7 = 64,
> +      ISO89ASMO449 = 65,
> +      ISO90 = 66,
> +      ISO91JISC62291984a = 67,
> +      ISO92JISC62991984b = 68,
> +      ISO93JIS62291984badd = 69,
> +      ISO94JIS62291984hand = 70,
> +      ISO95JIS62291984handadd = 71,
> +      ISO96JISC62291984kana = 72,
> +      ISO2033 = 73,
> +      ISO99NAPLPS = 74,
> +      ISO102T617bit = 75,
> +      ISO103T618bit = 76,
> +      ISO111ECMACyrillic = 77,
> +      ISO121Canadian1 = 78,
> +      ISO122Canadian2 = 79,
> +      ISO123CSAZ24341985gr = 80,
> +      ISO88596E = 81,
> +      ISO88596I = 82,
> +      ISO128T101G2 = 83,
> +      ISO88598E = 84,
> +      ISO88598I = 85,
> +      ISO139CSN369103 = 86,
> +      ISO141JUSIB1002 = 87,
> +      ISO143IECP271 = 88,
> +      ISO146Serbian = 89,
> +      ISO147Macedonian = 90,
> +      ISO150 = 91,
> +      ISO151Cuba = 92,
> +      ISO6937Add = 93,
> +      ISO153GOST1976874 = 94,
> +      ISO8859Supp = 95,
> +      ISO10367Box = 96,
> +      ISO158Lap = 97,
> +      ISO159JISX02121990 = 98,
> +      ISO646Danish = 99,
> +      USDK = 100,
> +      DKUS = 101,
> +      KSC5636 = 102,
> +      Unicode11UTF7 = 103,
> +      ISO2022CN = 104,
> +      ISO2022CNEXT = 105,
> +      UTF8 = 106,
> +      ISO885913 = 109,
> +      ISO885914 = 110,
> +      ISO885915 = 111,
> +      ISO885916 = 112,
> +      GBK = 113,
> +      GB18030 = 114,
> +      OSDEBCDICDF0415 = 115,
> +      OSDEBCDICDF03IRV = 116,
> +      OSDEBCDICDF041 = 117,
> +      ISO115481 = 118,
> +      KZ1048 = 119,
> +      UCS2 = 1000,
> +      UCS4 = 1001,
> +      UnicodeASCII = 1002,
> +      UnicodeLatin1 = 1003,
> +      UnicodeJapanese = 1004,
> +      UnicodeIBM1261 = 1005,
> +      UnicodeIBM1268 = 1006,
> +      UnicodeIBM1276 = 1007,
> +      UnicodeIBM1264 = 1008,
> +      UnicodeIBM1265 = 1009,
> +      Unicode11 = 1010,
> +      SCSU = 1011,
> +      UTF7 = 1012,
> +      UTF16BE = 1013,
> +      UTF16LE = 1014,
> +      UTF16 = 1015,
> +      CESU8 = 1016,
> +      UTF32 = 1017,
> +      UTF32BE = 1018,
> +      UTF32LE = 1019,
> +      BOCU1 = 1020,
> +      UTF7IMAP = 1021,
> +      Windows30Latin1 = 2000,
> +      Windows31Latin1 = 2001,
> +      Windows31Latin2 = 2002,
> +      Windows31Latin5 = 2003,
> +      HPRoman8 = 2004,
> +      AdobeStandardEncoding = 2005,
> +      VenturaUS = 2006,
> +      VenturaInternational = 2007,
> +      DECMCS = 2008,
> +      PC850Multilingual = 2009,
> +      PC8DanishNorwegian = 2012,
> +      PC862LatinHebrew = 2013,
> +      PC8Turkish = 2014,
> +      IBMSymbols = 2015,
> +      IBMThai = 2016,
> +      HPLegal = 2017,
> +      HPPiFont = 2018,
> +      HPMath8 = 2019,
> +      HPPSMath = 2020,
> +      HPDesktop = 2021,
> +      VenturaMath = 2022,
> +      MicrosoftPublishing = 2023,
> +      Windows31J = 2024,
> +      GB2312 = 2025,
> +      Big5 = 2026,
> +      Macintosh = 2027,
> +      IBM037 = 2028,
> +      IBM038 = 2029,
> +      IBM273 = 2030,
> +      IBM274 = 2031,
> +      IBM275 = 2032,
> +      IBM277 = 2033,
> +      IBM278 = 2034,
> +      IBM280 = 2035,
> +      IBM281 = 2036,
> +      IBM284 = 2037,
> +      IBM285 = 2038,
> +      IBM290 = 2039,
> +      IBM297 = 2040,
> +      IBM420 = 2041,
> +      IBM423 = 2042,
> +      IBM424 = 2043,
> +      PC8CodePage437 = 2011,
> +      IBM500 = 2044,
> +      IBM851 = 2045,
> +      PCp852 = 2010,
> +      IBM855 = 2046,
> +      IBM857 = 2047,
> +      IBM860 = 2048,
> +      IBM861 = 2049,
> +      IBM863 = 2050,
> +      IBM864 = 2051,
> +      IBM865 = 2052,
> +      IBM868 = 2053,
> +      IBM869 = 2054,
> +      IBM870 = 2055,
> +      IBM871 = 2056,
> +      IBM880 = 2057,
> +      IBM891 = 2058,
> +      IBM903 = 2059,
> +      IBM904 = 2060,
> +      IBM905 = 2061,
> +      IBM918 = 2062,
> +      IBM1026 = 2063,
> +      IBMEBCDICATDE = 2064,
> +      EBCDICATDEA = 2065,
> +      EBCDICCAFR = 2066,
> +      EBCDICDKNO = 2067,
> +      EBCDICDKNOA = 2068,
> +      EBCDICFISE = 2069,
> +      EBCDICFISEA = 2070,
> +      EBCDICFR = 2071,
> +      EBCDICIT = 2072,
> +      EBCDICPT = 2073,
> +      EBCDICES = 2074,
> +      EBCDICESA = 2075,
> +      EBCDICESS = 2076,
> +      EBCDICUK = 2077,
> +      EBCDICUS = 2078,
> +      Unknown8BiT = 2079,
> +      Mnemonic = 2080,
> +      Mnem = 2081,
> +      VISCII = 2082,
> +      VIQR = 2083,
> +      KOI8R = 2084,
> +      HZGB2312 = 2085,
> +      IBM866 = 2086,
> +      PC775Baltic = 2087,
> +      KOI8U = 2088,
> +      IBM00858 = 2089,
> +      IBM00924 = 2090,
> +      IBM01140 = 2091,
> +      IBM01141 = 2092,
> +      IBM01142 = 2093,
> +      IBM01143 = 2094,
> +      IBM01144 = 2095,
> +      IBM01145 = 2096,
> +      IBM01146 = 2097,
> +      IBM01147 = 2098,
> +      IBM01148 = 2099,
> +      IBM01149 = 2100,
> +      Big5HKSCS = 2101,
> +      IBM1047 = 2102,
> +      PTCP154 = 2103,
> +      Amiga1251 = 2104,
> +      KOI7switched = 2105,
> +      BRF = 2106,
> +      TSCII = 2107,
> +      CP51932 = 2108,
> +      windows874 = 2109,
> +      windows1250 = 2250,
> +      windows1251 = 2251,
> +      windows1252 = 2252,
> +      windows1253 = 2253,
> +      windows1254 = 2254,
> +      windows1255 = 2255,
> +      windows1256 = 2256,
> +      windows1257 = 2257,
> +      windows1258 = 2258,
> +      TIS620 = 2259,
> +      CP50220 = 2260
> +    };
> +    using enum id;
> +
> +    constexpr text_encoding() = default;
> +
> +    constexpr explicit
> +    text_encoding(string_view __enc) noexcept
> +    : _M_rep(_S_find_name(__enc))
> +    {
> +      __enc.copy(_M_name, max_name_length);
> +    }
> +
> +    // @pre i has the value of one of the enumerators of id.
> +    constexpr
> +    text_encoding(id __i) noexcept
> +    : _M_rep(_S_find_id(__i))
> +    {
> +      if (string_view __name(_M_rep->_M_name); !__name.empty())
> +	__name.copy(_M_name, max_name_length);
> +    }
> +
> +    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
> +
> +    constexpr const char* name() const noexcept { return _M_name; }
> +
> +    struct aliases_view : ranges::view_interface<aliases_view>
> +    {
> +    private:
> +      class _Iterator;
> +      struct _Sentinel { };
> +
> +    public:
> +      constexpr _Iterator begin() const noexcept { return _Iterator(_M_begin); }
> +      constexpr _Sentinel end() const noexcept { return _Sentinel{}; }
> +
> +    private:
> +      friend struct text_encoding;
> +
> +      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
> +
> +      class _Iterator
> +      {
> +      public:
> +	using value_type = const char*;
> +	using reference = const char*;
> +	using difference_type = int;
> +	constexpr value_type operator*() const;

Are these defined out-of-line to avoid excessive indentation?  Perhaps
we could define _Iterator (and aliases_view::begin) out-of-line instead?

> +	constexpr _Iterator& operator++();
> +	constexpr _Iterator& operator--();
> +	constexpr _Iterator operator++(int);
> +	constexpr _Iterator operator--(int);
> +	constexpr value_type operator[](difference_type) const;
> +	constexpr _Iterator& operator+=(difference_type);
> +	constexpr _Iterator& operator-=(difference_type);
> +	constexpr difference_type operator-(const _Iterator&) const;
> +	constexpr bool operator==(const _Iterator&) const = default;
> +	constexpr bool operator==(_Sentinel) const noexcept;
> +	constexpr strong_ordering operator<=>(const _Iterator&) const;
> +
> +	friend _Iterator
> +	operator+(_Iterator __i, difference_type __n)

constexpr?

> +	{
> +	  __i += __n;
> +	  return __i;
> +	}
> +
> +	friend _Iterator
> +	operator+(difference_type __n, _Iterator __i)
> +	{
> +	  __i += __n;
> +	  return __i;
> +	}
> +
> +	friend _Iterator
> +	operator-(_Iterator __i, difference_type __n)
> +	{
> +	  __i -= __n;
> +	  return __i;
> +	}
> +
> +      private:
> +	friend class text_encoding;
> +
> +	constexpr explicit
> +	_Iterator(const _Rep* __r) noexcept
> +	: _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
> +	{ }
> +
> +	constexpr bool _M_dereferenceable() const noexcept;
> +	static constexpr difference_type _S_neg(difference_type) noexcept;
> +
> +	const _Rep* _M_rep = nullptr;
> +	_Rep::id _M_id = 0;
> +      };
> +
> +      const _Rep* _M_begin = nullptr;
> +    };
> +
> +    constexpr aliases_view
> +    aliases() const noexcept
> +    {
> +      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
> +    }
> +
> +    friend constexpr bool
> +    operator==(const text_encoding& __a,
> +	       const text_encoding& __b) noexcept
> +    {
> +      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
> +	return _S_comp(__a._M_name, __b._M_name);
> +      else
> +	return __a.mib() == __b.mib();
> +    }
> +
> +    friend constexpr bool
> +    operator==(const text_encoding& __encoding, id __i) noexcept
> +    { return __encoding.mib() == __i; }
> +
> +#if __CHAR_BIT__ == 8
> +    static consteval text_encoding
> +    literal() noexcept
> +    {
> +#ifdef __GNUC_EXECUTION_CHARSET_NAME
> +      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
> +#elif defined __clang_literal_encoding__
> +      return text_encoding(__clang_literal_encoding__);
> +#else
> +      return text_encoding();
> +#endif
> +    }
> +
> +    static text_encoding
> +    environment();
> +
> +    template<id _Id>
> +      static bool
> +      environment_is()
> +      { return text_encoding(_Id)._M_is_environment(); }
> +#else
> +    static text_encoding literal() = delete;
> +    static text_encoding environment() = delete;
> +    template<id> static bool environment_is() = delete;
> +#endif
> +
> +  private:
> +    const _Rep* _M_rep = _S_reps + 1; // id::unknown
> +    char _M_name[max_name_length + 1] = {0};
> +
> +    bool
> +    _M_is_environment() const;
> +
> +    static inline constexpr _Rep _S_reps[] = {
> +      { 1, "" }, { 2, "" },
> +#define _GLIBCXX_GET_ENCODING_DATA
> +#include <bits/text_encoding-data.h>
> +#ifdef _GLIBCXX_GET_ENCODING_DATA
> +# error "Invalid text_encoding data"
> +#endif
> +      { 9999, nullptr }, // sentinel
> +    };
> +
> +    static constexpr bool
> +    _S_comp(string_view __a, string_view __b)
> +    { return __unicode::__charset_alias_match(__a, __b); }
> +
> +    static constexpr const _Rep*
> +    _S_find_name(string_view __name) noexcept
> +    {
> +#ifdef _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET
> +      // Optimize the common UTF-8 case to avoid a linear search through all
> +      // strings in the table using the _S_comp function.
> +      if (__name == "UTF-8")
> +	return _S_reps + 2 + _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET;
> +#endif
> +
> +      // The first two array elements (other and unknown) don't have names.
> +      // The last element is a sentinel that can never match anything.
> +      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
> +      for (auto __r = __first; __r != __end; ++__r)
> +	if (_S_comp(__r->_M_name, __name))
> +	  {
> +	    // Might have matched an alias. Find the first entry for this ID.
> +	    const auto __id = __r->_M_id;
> +	    while (__r[-1]._M_id == __id)
> +	      --__r;
> +	    return __r;
> +	  }
> +      return _S_reps; // id::other
> +    }
> +
> +    static constexpr const _Rep*
> +    _S_find_id(id __id) noexcept
> +    {
> +      const auto __i = (_Rep::id)__id;
> +      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
> +      if (__r->_M_id == __i) [[likely]]
> +	return __r;
> +      else
> +	{
> +	  // Preconditions: i has the value of one of the enumerators of id.
> +	  __glibcxx_assert(__r->_M_id == __i);
> +	  return _S_reps + 1; // id::unknown
> +	}
> +    }
> +  };
> +
> +  template<>
> +    struct hash<text_encoding>
> +    {
> +      size_t
> +      operator()(const text_encoding& __enc) const noexcept
> +      { return std::hash<text_encoding::id>()(__enc.mib()); }
> +    };
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator*() const
> +  -> value_type
> +  {
> +    if (_M_dereferenceable()) [[likely]]
> +      return _M_rep->_M_name;
> +    else
> +      {
> +	__glibcxx_assert(_M_dereferenceable());
> +	return "";
> +      }
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator++()
> +  -> _Iterator&
> +  {
> +    if (_M_dereferenceable()) [[likely]]
> +      ++_M_rep;
> +    else
> +      {
> +	__glibcxx_assert(_M_dereferenceable());
> +	*this = _Iterator{};
> +      }
> +    return *this;
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator--()
> +  -> _Iterator&
> +  {
> +    const bool __decrementable = _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
> +    if (__decrementable) [[likely]]
> +      --_M_rep;
> +    else
> +      {
> +	__glibcxx_assert(__decrementable);
> +	*this = _Iterator{};
> +      }
> +    return *this;
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator++(int)
> +  -> _Iterator
> +  {
> +    auto __it = *this;
> +    ++*this;
> +    return __it;
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator--(int)
> +  -> _Iterator
> +  {
> +    auto __it = *this;
> +    --*this;
> +    return __it;
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator[](difference_type __n) const
> +  -> value_type
> +  { return *(*this + __n); }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator+=(difference_type __n)
> +  -> _Iterator&
> +  {
> +    if (_M_rep != nullptr)
> +      {
> +	if ((__n > 0 && __n < (std::end(_S_reps) - _M_rep))
> +	      || (__n < 0 && __n > (_S_reps - _M_rep)))
> +	  {
> +	    if (_M_rep[__n]._M_id == _M_id)
> +	      _M_rep += __n;
> +	    else
> +	      *this = _Iterator{};
> +	  }
> +	else if (__n != 0)
> +	  *this = _Iterator{};
> +      }
> +    __glibcxx_assert(_M_rep != nullptr);
> +    return *this;
> +  }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator-=(difference_type __n)
> +  -> _Iterator&
> +  { return operator+=(_S_neg(__n)); }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::operator-(const _Iterator& __i) const noexcept
> +  -> difference_type
> +  {
> +    if (_M_id == __i._M_id)
> +      return _M_rep - __i._M_rep;
> +    __glibcxx_assert(_M_id == __i._M_id);
> +    return __gnu_cxx::__int_traits<difference_type>::__max;
> +  }
> +
> +  constexpr bool
> +  text_encoding::aliases_view::
> +  _Iterator::operator==(_Sentinel) const noexcept
> +  { return !_M_dereferenceable(); }
> +
> +  constexpr strong_ordering
> +  text_encoding::aliases_view::
> +  _Iterator::operator<=>(const _Iterator& __i) const
> +  {
> +    __glibcxx_assert(_M_id == __i._M_id);
> +    return _M_rep <=> __i._M_rep;
> +  }
> +
> +  constexpr bool
> +  text_encoding::aliases_view::
> +  _Iterator::_M_dereferenceable() const noexcept
> +  { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
> +
> +  constexpr auto
> +  text_encoding::aliases_view::
> +  _Iterator::_S_neg(difference_type __n) noexcept
> +  -> difference_type
> +  {
> +    using _Traits = __gnu_cxx::__int_traits<difference_type>;
> +    if (__n == _Traits::__min) [[unlikely]]
> +      return _Traits::__max;
> +    return -__n;
> +  }
> +
> +namespace ranges
> +{
> +  // Opt-in to borrowed_range concept
> +  template<>
> +    inline constexpr bool
> +    enable_borrowed_range<std::text_encoding::aliases_view> = true;
> +}
> +
> +_GLIBCXX_END_NAMESPACE_VERSION
> +} // namespace std
> +
> +#endif // __cpp_lib_text_encoding
> +#endif // _GLIBCXX_TEXT_ENCODING
> diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
> index 032a7aa58a2..a6c2ed4599f 100644
> --- a/libstdc++-v3/python/libstdcxx/v6/printers.py
> +++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
> @@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
>          typename = strip_versioned_namespace(self._typename)
>          return "{}<{}, {}>".format(typename, value_type, value)
>  
> +class StdTextEncodingPrinter(printer_base):
> +    """Print a std::text_encoding."""
> +
> +    def __init__(self, typename, val):
> +        self._val = val
> +        self._typename = typename
> +
> +    def to_string(self):
> +        rep = self._val['_M_rep'].dereference()
> +        if rep['_M_id'] == 1:
> +            return self._val['_M_name']
> +        if rep['_M_id'] == 2:
> +            return 'unknown'
> +        return rep['_M_name']
> +
>  # A "regular expression" printer which conforms to the
>  # "SubPrettyPrinter" protocol from gdb.printing.
>  class RxPrinter(object):
> @@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
>  
>      libstdcxx_printer.add_version('std::', 'integral_constant',
>                                    StdIntegralConstantPrinter)
> +    libstdcxx_printer.add_version('std::', 'text_encoding',
> +                                  StdTextEncodingPrinter)
>  
>      if hasattr(gdb.Value, 'dynamic_type'):
>          libstdcxx_printer.add_version('std::', 'error_code',
> diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
> new file mode 100755
> index 00000000000..2d6f3e4077a
> --- /dev/null
> +++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
> @@ -0,0 +1,70 @@
> +#!/usr/bin/env python3
> +#
> +# Script to generate tables for libstdc++ std::text_encoding.
> +#
> +# This file is part of GCC.
> +#
> +# GCC is free software; you can redistribute it and/or modify it under
> +# the terms of the GNU General Public License as published by the Free
> +# Software Foundation; either version 3, or (at your option) any later
> +# version.
> +#
> +# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +# WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +# for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with GCC; see the file COPYING3.  If not see
> +# <http://www.gnu.org/licenses/>.
> +
> +# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
> +# the latest:
> +# https://www.iana.org/assignments/character-sets/character-sets-1.csv
> +# Then run this script and save the output to
> +# include/bits/text_encoding-data.h
> +
> +import sys
> +import csv
> +
> +if len(sys.argv) != 2:
> +    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
> +    sys.exit(1)
> +
> +print("// Generated by gen_text_encoding_data.py, do not edit.\n")
> +print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
> +print('# error "This is not a public header, do not include it directly"')
> +print("#endif\n")
> +
> +
> +charsets = {}
> +with open(sys.argv[1], newline='') as f:
> +    reader = csv.reader(f)
> +    next(reader) # skip header row
> +    for row in reader:
> +        mib = int(row[2])
> +        if mib in charsets:
> +            raise ValueError("Multiple rows for mibEnum={}".format(mib))
> +        name = row[1]
> +        aliases = row[5].split()
> +        # Ensure primary name comes first
> +        if name in aliases:
> +            aliases.remove(name)
> +        charsets[mib] = [name] + aliases
> +
> +# Remove "NATS-DANO" and "NATS-DANO-ADD"
> +charsets.pop(33, None)
> +charsets.pop(34, None)
> +
> +count = 0
> +for mib in sorted(charsets.keys()):
> +    names = charsets[mib]
> +    if names[0] == "UTF-8":
> +        print("#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET {}".format(count))
> +    for name in names:
> +        print('  {{ {:4}, "{}" }},'.format(mib, name))
> +    count += len(names)
> +
> +# <text_encoding> gives an error if this macro is left defined.
> +# Do this last, so that the generated output is not usable unless we reach here.
> +print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
> diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
> index 7292ae70f81..37ba1491dea 100644
> --- a/libstdc++-v3/src/Makefile.am
> +++ b/libstdc++-v3/src/Makefile.am
> @@ -43,7 +43,7 @@ experimental_dir =
>  endif
>  
>  ## Keep this list sync'd with acinclude.m4:GLIBCXX_CONFIGURE.
> -SUBDIRS = c++98 c++11 c++17 c++20 c++23 \
> +SUBDIRS = c++98 c++11 c++17 c++20 c++23 c++26 \
>  	$(filesystem_dir) $(backtrace_dir) $(experimental_dir)
>  
>  # Cross compiler support.
> @@ -77,6 +77,7 @@ vpath % $(top_srcdir)/src/c++11
>  vpath % $(top_srcdir)/src/c++17
>  vpath % $(top_srcdir)/src/c++20
>  vpath % $(top_srcdir)/src/c++23
> +vpath % $(top_srcdir)/src/c++26
>  if ENABLE_FILESYSTEM_TS
>  vpath % $(top_srcdir)/src/filesystem
>  endif
> diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
> new file mode 100644
> index 00000000000..000ced1f501
> --- /dev/null
> +++ b/libstdc++-v3/src/c++26/Makefile.am
> @@ -0,0 +1,109 @@
> +## Makefile for the C++26 sources of the GNU C++ Standard library.
> +##
> +## Copyright (C) 1997-2023 Free Software Foundation, Inc.
> +##
> +## This file is part of the libstdc++ version 3 distribution.
> +## Process this file with automake to produce Makefile.in.
> +
> +## This file is part of the GNU ISO C++ Library.  This library is free
> +## software; you can redistribute it and/or modify it under the
> +## terms of the GNU General Public License as published by the
> +## Free Software Foundation; either version 3, or (at your option)
> +## any later version.
> +
> +## This library is distributed in the hope that it will be useful,
> +## but WITHOUT ANY WARRANTY; without even the implied warranty of
> +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +## GNU General Public License for more details.
> +
> +## You should have received a copy of the GNU General Public License along
> +## with this library; see the file COPYING3.  If not see
> +## <http://www.gnu.org/licenses/>.
> +
> +include $(top_srcdir)/fragment.am
> +
> +# Convenience library for C++26 runtime.
> +noinst_LTLIBRARIES = libc++26convenience.la
> +
> +headers =
> +
> +if ENABLE_EXTERN_TEMPLATE
> +# XTEMPLATE_FLAGS = -fno-implicit-templates
> +inst_sources =
> +else
> +# XTEMPLATE_FLAGS =
> +inst_sources =
> +endif
> +
> +sources = text_encoding.cc
> +
> +vpath % $(top_srcdir)/src/c++26
> +
> +
> +if GLIBCXX_HOSTED
> +libc__26convenience_la_SOURCES = $(sources)  $(inst_sources)
> +else
> +libc__26convenience_la_SOURCES =
> +endif
> +
> +# AM_CXXFLAGS needs to be in each subdirectory so that it can be
> +# modified in a per-library or per-sub-library way.  Need to manually
> +# set this option because CONFIG_CXXFLAGS has to be after
> +# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
> +# as the occasion calls for it.
> +AM_CXXFLAGS = \
> +	-std=gnu++26 \
> +	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
> +	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
> +	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
> +	-fimplicit-templates
> +
> +AM_MAKEFLAGS = \
> +	"gxx_include_dir=$(gxx_include_dir)"
> +
> +# Libtool notes
> +
> +# 1) In general, libtool expects an argument such as `--tag=CXX' when
> +# using the C++ compiler, because that will enable the settings
> +# detected when C++ support was being configured.  However, when no
> +# such flag is given in the command line, libtool attempts to figure
> +# it out by matching the compiler name in each configuration section
> +# against a prefix of the command line.  The problem is that, if the
> +# compiler name and its initial flags stored in the libtool
> +# configuration file don't match those in the command line, libtool
> +# can't decide which configuration to use, and it gives up.  The
> +# correct solution is to add `--tag CXX' to LTCXXCOMPILE and maybe
> +# CXXLINK, just after $(LIBTOOL), so that libtool doesn't have to
> +# attempt to infer which configuration to use.
> +#
> +# The second tag argument, `--tag disable-shared` means that libtool
> +# only compiles each source once, for static objects. In actuality,
> +# glibcxx_lt_pic_flag and glibcxx_compiler_shared_flag are added to
> +# the libtool command that is used create the object, which is
> +# suitable for shared libraries.  The `--tag disable-shared` must be
> +# placed after --tag CXX lest things CXX undo the affect of
> +# disable-shared.
> +
> +# 2) Need to explicitly set LTCXXCOMPILE so that EXTRA_CXX_FLAGS is
> +# last. (That way, things like -O2 passed down from the toplevel can
> +# be overridden by --enable-debug.)
> +LTCXXCOMPILE = \
> +	$(LIBTOOL) --tag CXX --tag disable-shared \
> +	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
> +	--mode=compile $(CXX) $(TOPLEVEL_INCLUDES) \
> +	$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CXXFLAGS) $(CXXFLAGS) $(EXTRA_CXX_FLAGS)
> +
> +LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
> +
> +# 3) We'd have a problem when building the shared libstdc++ object if
> +# the rules automake generates would be used.  We cannot allow g++ to
> +# be used since this would add -lstdc++ to the link line which of
> +# course is problematic at this point.  So, we get the top-level
> +# directory to configure libstdc++-v3 to use gcc as the C++
> +# compilation driver.
> +CXXLINK = \
> +	$(LIBTOOL) --tag CXX --tag disable-shared \
> +	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
> +	--mode=link $(CXX) \
> +	$(VTV_CXXLINKFLAGS) \
> +	$(OPT_LDFLAGS) $(SECTION_LDFLAGS) $(AM_CXXFLAGS) $(LTLDFLAGS) -o $@
> diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
> new file mode 100644
> index 00000000000..9a7df07db29
> --- /dev/null
> +++ b/libstdc++-v3/src/c++26/text_encoding.cc
> @@ -0,0 +1,91 @@
> +// Definitions for <text_encoding> -*- C++ -*-
> +
> +// Copyright The GNU Toolchain Authors.
> +//
> +// This file is part of the GNU ISO C++ Library.  This library is free
> +// software; you can redistribute it and/or modify it under the
> +// terms of the GNU General Public License as published by the
> +// Free Software Foundation; either version 3, or (at your option)
> +// any later version.
> +
> +// This library is distributed in the hope that it will be useful,
> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +// GNU General Public License for more details.
> +
> +// Under Section 7 of GPL version 3, you are granted additional
> +// permissions described in the GCC Runtime Library Exception, version
> +// 3.1, as published by the Free Software Foundation.
> +
> +// You should have received a copy of the GNU General Public License and
> +// a copy of the GCC Runtime Library Exception along with this program;
> +// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +// <http://www.gnu.org/licenses/>.
> +
> +#include <text_encoding>
> +#include <locale>
> +
> +#ifdef _GLIBCXX_USE_NL_LANGINFO_L
> +#include <locale.h>
> +#include <langinfo.h>
> +
> +#if __CHAR_BIT__ == 8
> +namespace std
> +{
> +_GLIBCXX_BEGIN_NAMESPACE_VERSION
> +
> +text_encoding
> +__locale_encoding(const char* name)
> +{
> +  text_encoding enc;
> +  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
> +    {
> +      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
> +	{
> +	  string_view s(codeset);
> +	  if (s.size() < text_encoding::max_name_length)
> +	    enc = text_encoding(s);
> +	}
> +      ::freelocale(loc);
> +    }
> +  return enc;
> +}
> +
> +_GLIBCXX_END_NAMESPACE_VERSION
> +} // namespace std
> +
> +std::text_encoding
> +std::text_encoding::environment()
> +{
> +  return std::__locale_encoding("");
> +}
> +
> +bool
> +std::text_encoding::_M_is_environment() const
> +{
> +  bool matched = false;
> +  if (locale_t loc = ::newlocale(LC_ALL_MASK, "", (locale_t)0))
> +    {
> +      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
> +	{
> +	  string_view sv(codeset);
> +	  for (auto alias : aliases())
> +	    if (__unicode::__charset_alias_match(alias, sv))
> +	      {
> +		matched = true;
> +		break;
> +	      }
> +	}
> +      ::freelocale(loc);
> +    }
> +  return matched;
> +}
> +
> +std::text_encoding
> +std::locale::encoding() const
> +{
> +  return std::__locale_encoding(name().c_str());
> +}
> +#endif // CHAR_BIT == 8
> +
> +#endif // _GLIBCXX_USE_NL_LANGINFO_L
> diff --git a/libstdc++-v3/src/experimental/Makefile.am b/libstdc++-v3/src/experimental/Makefile.am
> index 8259f986d95..6241430988e 100644
> --- a/libstdc++-v3/src/experimental/Makefile.am
> +++ b/libstdc++-v3/src/experimental/Makefile.am
> @@ -47,10 +47,12 @@ libstdc__exp_la_SOURCES = $(sources)
>  
>  libstdc__exp_la_LIBADD = \
>  	$(top_builddir)/src/c++23/libc++23convenience.la \
> +	$(top_builddir)/src/c++26/libc++26convenience.la \
>  	$(filesystem_lib) $(backtrace_lib)
>  
>  libstdc__exp_la_DEPENDENCIES = \
>  	$(top_builddir)/src/c++23/libc++23convenience.la \
> +	$(top_builddir)/src/c++26/libc++26convenience.la \
>  	$(filesystem_lib) $(backtrace_lib)
>  
>  # AM_CXXFLAGS needs to be in each subdirectory so that it can be
> diff --git a/libstdc++-v3/testsuite/22_locale/locale/encoding.cc b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
> new file mode 100644
> index 00000000000..18825fb88b9
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
> @@ -0,0 +1,36 @@
> +// { dg-options "-lstdc++exp" }
> +// { dg-do run { target c++26 } }
> +// { dg-require-namedlocale "en_US.ISO8859-1" }
> +// { dg-require-namedlocale "fr_FR.ISO8859-15" }
> +
> +#include <locale>
> +#include <testsuite_hooks.h>
> +
> +void
> +test_encoding()
> +{
> +  const std::locale c = std::locale::classic();
> +  std::text_encoding c_enc = c.encoding();
> +  VERIFY( c_enc == std::text_encoding::ASCII );
> +
> +  const std::locale fr = std::locale(ISO_8859(15, fr_FR));
> +  std::text_encoding fr_enc = fr.encoding();
> +  VERIFY( fr_enc == std::text_encoding::ISO885915 );
> +
> +  const std::locale en = std::locale(ISO_8859(1, en_US));
> +  std::text_encoding en_enc = en.encoding();
> +  VERIFY( en_enc == std::text_encoding::ISOLatin1 );
> +
> +#if __cpp_exceptions
> +  try {
> +    const std::locale c_utf8 = std::locale("C.UTF-8");
> +    VERIFY( c_utf8.encoding() == std::text_encoding::UTF8 );
> +  } catch (...) {
> +  }
> +#endif
> +}
> +
> +int main()
> +{
> +  test_encoding();
> +}
> diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
> new file mode 100644
> index 00000000000..f6272ae998b
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
> @@ -0,0 +1,18 @@
> +// { dg-do compile { target c++20 } }
> +#include <format>
> +
> +using std::__unicode::__charset_alias_match;
> +static_assert( __charset_alias_match("UTF-8", "utf8") == true );
> +static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
> +static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
> +static_assert( __charset_alias_match("UTF-8", "ut8") == false );
> +
> +static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
> +
> +static_assert( __charset_alias_match("", "") == true );
> +static_assert( __charset_alias_match("", ".") == true );
> +static_assert( __charset_alias_match("--", "...") == true );
> +static_assert( __charset_alias_match("--a", "a...") == true );
> +static_assert( __charset_alias_match("--a010", "a..10.") == true );
> +static_assert( __charset_alias_match("--a010", "a..1.0") == false );
> +static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
> diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
> new file mode 100644
> index 00000000000..b9d93641de4
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
> @@ -0,0 +1,113 @@
> +// { dg-do run { target c++26 } }
> +
> +#include <text_encoding>
> +#include <string_view>
> +#include <testsuite_hooks.h>
> +
> +using namespace std::string_view_literals;
> +
> +constexpr void
> +test_default_construct()
> +{
> +  std::text_encoding e0;
> +  VERIFY( e0.mib() == std::text_encoding::unknown );
> +  VERIFY( e0.name()[0] == '\0' ); // P2862R1 name() should never return null
> +  VERIFY( e0.aliases().empty() );
> +}
> +
> +constexpr void
> +test_construct_by_name()
> +{
> +  std::string_view s;
> +  std::text_encoding e0(s);
> +  VERIFY( e0.mib() == std::text_encoding::other );
> +  VERIFY( e0.name() == s );
> +  VERIFY( e0.aliases().empty() );
> +
> +  s = "not a real encoding";
> +  std::text_encoding e1(s);
> +  VERIFY( e1.mib() == std::text_encoding::other );
> +  VERIFY( e1.name() == s );
> +  VERIFY( e1.aliases().empty() );
> +
> +  VERIFY( e1 != e0 );
> +  VERIFY( e1 == e0.mib() );
> +
> +  s = "utf8";
> +  std::text_encoding e2(s);
> +  VERIFY( e2.mib() == std::text_encoding::UTF8 );
> +  VERIFY( e2.name() == s );
> +  VERIFY( ! e2.aliases().empty() );
> +  VERIFY( e2.aliases().front() == "UTF-8"sv );
> +
> +  s = "Latin-1"; // matches "latin1"
> +  std::text_encoding e3(s);
> +  VERIFY( e3.mib() == std::text_encoding::ISOLatin1 );
> +  VERIFY( e3.name() == s );
> +  VERIFY( ! e3.aliases().empty() );
> +  VERIFY( e3.aliases().front() == "ISO_8859-1:1987"sv ); // primary name
> +
> +  s = "U.S."; // matches "us"
> +  std::text_encoding e4(s);
> +  VERIFY( e4.mib() == std::text_encoding::ASCII );
> +  VERIFY( e4.name() == s );
> +  VERIFY( ! e4.aliases().empty() );
> +  VERIFY( e4.aliases().front() == "US-ASCII"sv ); // primary name
> +}
> +
> +constexpr void
> +test_construct_by_id()
> +{
> +  std::text_encoding e0(std::text_encoding::other);
> +  VERIFY( e0.mib() == std::text_encoding::other );
> +  VERIFY( e0.name() == ""sv );
> +  VERIFY( e0.aliases().empty() );
> +
> +  std::text_encoding e1(std::text_encoding::unknown);
> +  VERIFY( e1.mib() == std::text_encoding::unknown );
> +  VERIFY( e1.name() == ""sv );
> +  VERIFY( e1.aliases().empty() );
> +
> +  std::text_encoding e2(std::text_encoding::UTF8);
> +  VERIFY( e2.mib() == std::text_encoding::UTF8 );
> +  VERIFY( e2.name() == "UTF-8"sv );
> +  VERIFY( ! e2.aliases().empty() );
> +  VERIFY( e2.aliases().front() == std::string_view(e2.name()) );
> +  bool found = false;
> +  for (auto alias : e2.aliases())
> +    if (alias == "csUTF8"sv)
> +    {
> +      found = true;
> +      break;
> +    }
> +  VERIFY( found );
> +}
> +
> +constexpr void
> +test_copy_construct()
> +{
> +  std::text_encoding e0;
> +  std::text_encoding e1 = e0;
> +  VERIFY( e1 == e0 );
> +
> +  std::text_encoding e2(std::text_encoding::UTF8);
> +  auto e3 = e2;
> +  VERIFY( e3 == e2 );
> +
> +  e1 = e3;
> +  VERIFY( e1 == e2 );
> +}
> +
> +int main()
> +{
> +  auto run_tests = [] {
> +    test_default_construct();
> +    test_construct_by_name();
> +    test_construct_by_id();
> +    test_copy_construct();
> +    return true;
> +  };
> +
> +  run_tests();
> +  static_assert( run_tests() );
> +}
> diff --git a/libstdc++-v3/testsuite/std/text_encoding/members.cc b/libstdc++-v3/testsuite/std/text_encoding/members.cc
> new file mode 100644
> index 00000000000..0b0d6bd0c96
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/text_encoding/members.cc
> @@ -0,0 +1,41 @@
> +// { dg-options "-lstdc++exp" }
> +// { dg-do run { target c++26 } }
> +// { dg-require-namedlocale "en_US.ISO8859-1" }
> +// { dg-require-namedlocale "fr_FR.ISO8859-15" }
> +
> +#include <text_encoding>
> +#include <string_view>
> +#include <locale.h>
> +#include <testsuite_hooks.h>
> +
> +using namespace std::string_view_literals;
> +
> +void
> +test_literal()
> +{
> +  const std::text_encoding lit = std::text_encoding::literal();
> +  VERIFY( lit.name() == std::string_view(__GNUC_EXECUTION_CHARSET_NAME) );
> +}
> +
> +void
> +test_env()
> +{
> +  const std::text_encoding env = std::text_encoding::environment();
> +
> +  if (env.mib() == std::text_encoding::UTF8)
> +    VERIFY( std::text_encoding::environment_is<std::text_encoding::UTF8>() );
> +
> +  ::setlocale(LC_ALL, ISO_8859(1, en_US));
> +  const std::text_encoding env1 = std::text_encoding::environment();
> +  VERIFY( env1 == env );
> +
> +  ::setlocale(LC_ALL, ISO_8859(15, fr_FR));
> +  const std::text_encoding env2 = std::text_encoding::environment();
> +  VERIFY( env2 == env );
> +}
> +
> +int main()
> +{
> +  test_literal();
> +  test_env();
> +}
> diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
> new file mode 100644
> index 00000000000..d62d93dcda4
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
> @@ -0,0 +1,31 @@
> +// { dg-do compile { target c++26 } }
> +// { dg-add-options no_pch }
> +
> +#include <text_encoding>
> +#ifndef __cpp_lib_text_encoding
> +# error "Feature-test macro for text_encoding missing in <text_encoding>"
> +#elif __cpp_lib_text_encoding != 202306L
> +# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
> +#endif
> +
> +#undef __cpp_lib_expected
> +#include <version>
> +#ifndef __cpp_lib_text_encoding
> +# error "Feature-test macro for text_encoding missing in <version>"
> +#elif __cpp_lib_text_encoding != 202306L
> +# error "Feature-test macro for text_encoding has wrong value in <version>"
> +#endif
> +
> +#include <concepts>
> +#include <ranges>
> +static_assert( std::is_trivially_copyable_v<std::text_encoding> );
> +
> +using aliases_view = std::text_encoding::aliases_view;
> +static_assert( std::copyable<aliases_view> );
> +static_assert( std::ranges::view<aliases_view> );
> +static_assert( std::ranges::random_access_range<aliases_view> );
> +static_assert( std::ranges::borrowed_range<aliases_view> );
> +static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
> +			    const char*> );
> +static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
> +			    const char*> );
> -- 
> 2.43.0
> 
> 


^ permalink raw reply	[flat|nested] 9+ messages in thread
* [PATCH v4] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-16  0:09     ` Patrick Palka
@ 2024-01-16 14:06       ` Jonathan Wakely
  2024-01-16 15:39         ` Jonathan Wakely
  0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-16 14:06 UTC (permalink / raw)
  To: Patrick Palka; +Cc: libstdc++, gcc-patches

[-- Attachment #1: Type: text/plain, Size: 3871 bytes --]

On 15/01/24 19:09 -0500, Patrick Palka wrote:
>On Mon, 15 Jan 2024, Jonathan Wakely wrote:
>
>> I think I'm happy with this now. It has tests for all the new functions,
>> and the performance of the charset alias match algorithm is improved by
>> reusing part of <charconv>.
>>
>> Tested x86_64-linux.
>>
>> -- >8 --
>>
>> This is another C++26 change, approved in Varna 2022. We require a new
>
>2023?

Oops, yes.

>> @@ -1056,6 +1057,54 @@ inline namespace __v15_1_0
>>    __literal_encoding_is_utf8()
>>    { return __literal_encoding_is_unicode<char>(); }
>>
>> +  consteval bool
>> +  __literal_encoding_is_extended_ascii()
>> +  {
>> +    return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
>> +	     && 'a' == 0x61 && 'z' == 0x7a;
>> +  }
>
>This function seems unused now.

It is. I thought it might be a useful utility to have in the unicode
file, but it's easy enough to recreate if needed. I'll remove it.

>> +
>> +  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
>> +  constexpr bool
>> +  __charset_alias_match(string_view __a, string_view __b)
>> +  {
>> +    // Map alphanumeric chars to their base 64 value, everything else to 127.
>> +    auto __map = [](char __c, bool& __num) -> unsigned char {
>> +      using __detail::__from_chars_alnum_to_val_table;
>> +      if (__c == '0') [[unlikely]]
>> +	return __num ? 0 : 127;
>> +      auto __v = __from_chars_alnum_to_val_table<false>::value.__data[__c];
>
>Maybe it'd be more concise to use the accessor function
>__from_chars_alnum_to_val here (so e.g. the caller doesn't have to pass
>_DecOnly=false explicitly)?

Yup, done.

> +
>> +      class _Iterator
>> +      {
>> +      public:
>> +	using value_type = const char*;
>> +	using reference = const char*;
>> +	using difference_type = int;
>> +	constexpr value_type operator*() const;
>
>Are these defined out-of-line to avoid excessive indentation?  Perhaps
>we could define _Iterator (and aliases_view::begin) out-of-line instead?

Not due to indentation, but because the text_encoding class itself
became even more unreadable with this code in the middle of it. I
realise that the huge list of enumerators in the id enum already makes
it unwieldy, but at least that's just a repetitive list of constants.
The iterator function bodies don't really add anything to the
understanding of the std::text_encoding API (it's an iterator, it has
the expected iterator operations, the details of how they're
implemented don't matter to most casual readers). But moving the whole
_Iterator class to the end serves the same purpose.

I didn't try moving it to the end because I was concerned about Clang
giving bogus errors about constexpr functions not being defined, like
this recent one: https://github.com/llvm/llvm-project/issues/73232
Although if that was going to be a problem, defining the members
out-of-line would probably already fail.

I've moved it (and the begin() function that uses it).

>
>> +	constexpr _Iterator& operator++();
>> +	constexpr _Iterator& operator--();
>> +	constexpr _Iterator operator++(int);
>> +	constexpr _Iterator operator--(int);
>> +	constexpr value_type operator[](difference_type) const;
>> +	constexpr _Iterator& operator+=(difference_type);
>> +	constexpr _Iterator& operator-=(difference_type);
>> +	constexpr difference_type operator-(const _Iterator&) const;
>> +	constexpr bool operator==(const _Iterator&) const = default;
>> +	constexpr bool operator==(_Sentinel) const noexcept;
>> +	constexpr strong_ordering operator<=>(const _Iterator&) const;
>> +
>> +	friend _Iterator
>> +	operator+(_Iterator __i, difference_type __n)
>
>constexpr?

Fixed. I've added tests that all iterator ops are usable in constant
expressions, which found a bug in operator+= (it didn't let you
increment one past the end of the range).

Thanks for the review. Patch v4 attached. I'm testing it now.



[-- Attachment #2: patch.txt --]
[-- Type: text/x-patch, Size: 76283 bytes --]

commit 175ab4d9474d6d6f835714dc4c261249b75f98a5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Jan 15 15:42:50 2024

    libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
    
    This is another C++26 change, approved in Varna 2023. We require a new
    static array of data that is extracted from the IANA Character Sets
    database. A new Python script to generate a header from the IANA CSV
    file is added.
    
    The text_encoding class is basically just a pointer to an {ID,name} pair
    in the static array. The aliases view is also just the same pointer (or
    empty), and the view's iterator moves forwards and backwards in the
    array while the array elements have the same ID (or to one element
    further, for a past-the-end iterator).
    
    Because those iterators refer to a global array that never goes out of
    scope, there's no reason they should every produce undefined behaviour
    or indeterminate values.  They should either have well-defined
    behaviour, or abort. The overhead of ensuring those properties is pretty
    low, so seems worth it.
    
    This means that an aliases_view iterator should never be able to access
    out-of-bounds. A non-value-initialized iterator always points to an
    element of the static array even when not dereferenceable (the array has
    unreachable entries at the start and end, which means that even a
    past-the-end iterator for the last encoding in the array still points to
    valid memory).  Dereferencing an iterator can always return a valid
    array element, or "" for a non-dereferenceable iterator (but doing so
    will abort when assertions are enabled).  In the language being proposed
    for C++26, dereferencing an invalid iterator erroneously returns "".
    Attempting to increment/decrement past the last/first element in the
    view is erroneously a no-op, so aborts when assertions are enabled, and
    doesn't change value otherwise.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/113318
            * acinclude.m4 (GLIBCXX_CONFIGURE): Add c++26 directory.
            (GLIBCXX_CHECK_TEXT_ENCODING): Define.
            * config.h.in: Regenerate.
            * configure: Regenerate.
            * configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
            * include/Makefile.am: Add new headers.
            * include/Makefile.in: Regenerate.
            * include/bits/locale_classes.h (locale::encoding): Declare new
            member function.
            * include/bits/unicode.h (__charset_alias_match): New function.
            * include/bits/text_encoding-data.h: New file.
            * include/bits/version.def (text_encoding): Define.
            * include/bits/version.h: Regenerate.
            * include/std/text_encoding: New file.
            * src/Makefile.am: Add new subdirectory.
            * src/Makefile.in: Regenerate.
            * src/c++26/Makefile.am: New file.
            * src/c++26/Makefile.in: New file.
            * src/c++26/text_encoding.cc: New file.
            * src/experimental/Makefile.am: Include c++26 convenience
            library.
            * src/experimental/Makefile.in: Regenerate.
            * python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
            printer.
            * scripts/gen_text_encoding_data.py: New file.
            * testsuite/22_locale/locale/encoding.cc: New test.
            * testsuite/ext/unicode/charset_alias_match.cc: New test.
            * testsuite/std/text_encoding/cons.cc: New test.
            * testsuite/std/text_encoding/members.cc: New test.
            * testsuite/std/text_encoding/requirements.cc: New test.

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index e7cbf0fcf96..f9ba7ef744b 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -49,7 +49,7 @@ AC_DEFUN([GLIBCXX_CONFIGURE], [
   # Keep these sync'd with the list in Makefile.am.  The first provides an
   # expandable list at autoconf time; the second provides an expandable list
   # (i.e., shell variable) at configure time.
-  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
+  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/c++26 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
   SUBDIRS='glibcxx_SUBDIRS'
 
   # These need to be absolute paths, yet at the same time need to
@@ -5821,6 +5821,34 @@ AC_LANG_SAVE
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check whether the dependencies for std::text_encoding are available.
+dnl
+dnl Defines:
+dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
+AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
+  AC_TRY_COMPILE([
+  #include <locale.h>
+  #include <langinfo.h>
+  ],[
+    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
+    const char* enc = nl_langinfo_l(CODESET, loc);
+    freelocale(loc);
+  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
+  AC_MSG_RESULT($ac_nl_langinfo_l)
+  if test "$ac_nl_langinfo_l" = yes; then
+    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
+      [Define if nl_langinfo_l should be used for std::text_encoding.])
+  fi
+
+  AC_LANG_RESTORE
+])
+
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
 m4_include([../config/tls.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index c8b36333019..c68cac4f345 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
 # For __basic_file::native_handle()
 GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
 
+# For std::text_encoding
+GLIBCXX_CHECK_TEXT_ENCODING
+
 # Define documentation rules conditionally.
 
 # See if makeinfo has been installed and is modern enough
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index c6d6a24eb9e..64152351ed0 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -104,6 +104,7 @@ std_headers = \
 	${std_srcdir}/streambuf \
 	${std_srcdir}/string \
 	${std_srcdir}/system_error \
+	${std_srcdir}/text_encoding \
 	${std_srcdir}/thread \
 	${std_srcdir}/unordered_map \
 	${std_srcdir}/unordered_set \
@@ -159,6 +160,7 @@ bits_freestanding = \
 	${bits_srcdir}/stl_raw_storage_iter.h \
 	${bits_srcdir}/stl_relops.h \
 	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/text_encoding-data.h \
 	${bits_srcdir}/version.h \
 	${bits_srcdir}/string_view.tcc \
 	${bits_srcdir}/unicode.h \
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 621f2a29f50..a2e94217006 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -40,6 +40,10 @@
 #include <string>
 #include <ext/atomicity.h>
 
+#ifdef __glibcxx_text_encoding
+#include <text_encoding>
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string
     name() const;
 
+#ifdef __glibcxx_text_encoding
+# if __CHAR_BIT__ == 8
+    text_encoding
+    encoding() const;
+# else
+    text_encoding
+    encoding() const = delete;
+# endif
+#endif
+
     /**
      *  @brief  Locale equality.
      *
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
new file mode 100644
index 00000000000..7ac2e9dc3d9
--- /dev/null
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -0,0 +1,902 @@
+// Generated by gen_text_encoding_data.py, do not edit.
+
+#ifndef _GLIBCXX_GET_ENCODING_DATA
+# error "This is not a public header, do not include it directly"
+#endif
+
+  {    3, "US-ASCII" },
+  {    3, "iso-ir-6" },
+  {    3, "ANSI_X3.4-1968" },
+  {    3, "ANSI_X3.4-1986" },
+  {    3, "ISO_646.irv:1991" },
+  {    3, "ISO646-US" },
+  {    3, "us" },
+  {    3, "IBM367" },
+  {    3, "cp367" },
+  {    3, "csASCII" },
+  {    4, "ISO_8859-1:1987" },
+  {    4, "iso-ir-100" },
+  {    4, "ISO_8859-1" },
+  {    4, "ISO-8859-1" },
+  {    4, "latin1" },
+  {    4, "l1" },
+  {    4, "IBM819" },
+  {    4, "CP819" },
+  {    4, "csISOLatin1" },
+  {    5, "ISO_8859-2:1987" },
+  {    5, "iso-ir-101" },
+  {    5, "ISO_8859-2" },
+  {    5, "ISO-8859-2" },
+  {    5, "latin2" },
+  {    5, "l2" },
+  {    5, "csISOLatin2" },
+  {    6, "ISO_8859-3:1988" },
+  {    6, "iso-ir-109" },
+  {    6, "ISO_8859-3" },
+  {    6, "ISO-8859-3" },
+  {    6, "latin3" },
+  {    6, "l3" },
+  {    6, "csISOLatin3" },
+  {    7, "ISO_8859-4:1988" },
+  {    7, "iso-ir-110" },
+  {    7, "ISO_8859-4" },
+  {    7, "ISO-8859-4" },
+  {    7, "latin4" },
+  {    7, "l4" },
+  {    7, "csISOLatin4" },
+  {    8, "ISO_8859-5:1988" },
+  {    8, "iso-ir-144" },
+  {    8, "ISO_8859-5" },
+  {    8, "ISO-8859-5" },
+  {    8, "cyrillic" },
+  {    8, "csISOLatinCyrillic" },
+  {    9, "ISO_8859-6:1987" },
+  {    9, "iso-ir-127" },
+  {    9, "ISO_8859-6" },
+  {    9, "ISO-8859-6" },
+  {    9, "ECMA-114" },
+  {    9, "ASMO-708" },
+  {    9, "arabic" },
+  {    9, "csISOLatinArabic" },
+  {   10, "ISO_8859-7:1987" },
+  {   10, "iso-ir-126" },
+  {   10, "ISO_8859-7" },
+  {   10, "ISO-8859-7" },
+  {   10, "ELOT_928" },
+  {   10, "ECMA-118" },
+  {   10, "greek" },
+  {   10, "greek8" },
+  {   10, "csISOLatinGreek" },
+  {   11, "ISO_8859-8:1988" },
+  {   11, "iso-ir-138" },
+  {   11, "ISO_8859-8" },
+  {   11, "ISO-8859-8" },
+  {   11, "hebrew" },
+  {   11, "csISOLatinHebrew" },
+  {   12, "ISO_8859-9:1989" },
+  {   12, "iso-ir-148" },
+  {   12, "ISO_8859-9" },
+  {   12, "ISO-8859-9" },
+  {   12, "latin5" },
+  {   12, "l5" },
+  {   12, "csISOLatin5" },
+  {   13, "ISO-8859-10" },
+  {   13, "iso-ir-157" },
+  {   13, "l6" },
+  {   13, "ISO_8859-10:1992" },
+  {   13, "csISOLatin6" },
+  {   13, "latin6" },
+  {   14, "ISO_6937-2-add" },
+  {   14, "iso-ir-142" },
+  {   14, "csISOTextComm" },
+  {   15, "JIS_X0201" },
+  {   15, "X0201" },
+  {   15, "csHalfWidthKatakana" },
+  {   16, "JIS_Encoding" },
+  {   16, "csJISEncoding" },
+  {   17, "Shift_JIS" },
+  {   17, "MS_Kanji" },
+  {   17, "csShiftJIS" },
+  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
+  {   18, "csEUCPkdFmtJapanese" },
+  {   18, "EUC-JP" },
+  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
+  {   19, "csEUCFixWidJapanese" },
+  {   20, "BS_4730" },
+  {   20, "iso-ir-4" },
+  {   20, "ISO646-GB" },
+  {   20, "gb" },
+  {   20, "uk" },
+  {   20, "csISO4UnitedKingdom" },
+  {   21, "SEN_850200_C" },
+  {   21, "iso-ir-11" },
+  {   21, "ISO646-SE2" },
+  {   21, "se2" },
+  {   21, "csISO11SwedishForNames" },
+  {   22, "IT" },
+  {   22, "iso-ir-15" },
+  {   22, "ISO646-IT" },
+  {   22, "csISO15Italian" },
+  {   23, "ES" },
+  {   23, "iso-ir-17" },
+  {   23, "ISO646-ES" },
+  {   23, "csISO17Spanish" },
+  {   24, "DIN_66003" },
+  {   24, "iso-ir-21" },
+  {   24, "de" },
+  {   24, "ISO646-DE" },
+  {   24, "csISO21German" },
+  {   25, "NS_4551-1" },
+  {   25, "iso-ir-60" },
+  {   25, "ISO646-NO" },
+  {   25, "no" },
+  {   25, "csISO60DanishNorwegian" },
+  {   25, "csISO60Norwegian1" },
+  {   26, "NF_Z_62-010" },
+  {   26, "iso-ir-69" },
+  {   26, "ISO646-FR" },
+  {   26, "fr" },
+  {   26, "csISO69French" },
+  {   27, "ISO-10646-UTF-1" },
+  {   27, "csISO10646UTF1" },
+  {   28, "ISO_646.basic:1983" },
+  {   28, "ref" },
+  {   28, "csISO646basic1983" },
+  {   29, "INVARIANT" },
+  {   29, "csINVARIANT" },
+  {   30, "ISO_646.irv:1983" },
+  {   30, "iso-ir-2" },
+  {   30, "irv" },
+  {   30, "csISO2IntlRefVersion" },
+  {   31, "NATS-SEFI" },
+  {   31, "iso-ir-8-1" },
+  {   31, "csNATSSEFI" },
+  {   32, "NATS-SEFI-ADD" },
+  {   32, "iso-ir-8-2" },
+  {   32, "csNATSSEFIADD" },
+  {   35, "SEN_850200_B" },
+  {   35, "iso-ir-10" },
+  {   35, "FI" },
+  {   35, "ISO646-FI" },
+  {   35, "ISO646-SE" },
+  {   35, "se" },
+  {   35, "csISO10Swedish" },
+  {   36, "KS_C_5601-1987" },
+  {   36, "iso-ir-149" },
+  {   36, "KS_C_5601-1989" },
+  {   36, "KSC_5601" },
+  {   36, "korean" },
+  {   36, "csKSC56011987" },
+  {   37, "ISO-2022-KR" },
+  {   37, "csISO2022KR" },
+  {   38, "EUC-KR" },
+  {   38, "csEUCKR" },
+  {   39, "ISO-2022-JP" },
+  {   39, "csISO2022JP" },
+  {   40, "ISO-2022-JP-2" },
+  {   40, "csISO2022JP2" },
+  {   41, "JIS_C6220-1969-jp" },
+  {   41, "JIS_C6220-1969" },
+  {   41, "iso-ir-13" },
+  {   41, "katakana" },
+  {   41, "x0201-7" },
+  {   41, "csISO13JISC6220jp" },
+  {   42, "JIS_C6220-1969-ro" },
+  {   42, "iso-ir-14" },
+  {   42, "jp" },
+  {   42, "ISO646-JP" },
+  {   42, "csISO14JISC6220ro" },
+  {   43, "PT" },
+  {   43, "iso-ir-16" },
+  {   43, "ISO646-PT" },
+  {   43, "csISO16Portuguese" },
+  {   44, "greek7-old" },
+  {   44, "iso-ir-18" },
+  {   44, "csISO18Greek7Old" },
+  {   45, "latin-greek" },
+  {   45, "iso-ir-19" },
+  {   45, "csISO19LatinGreek" },
+  {   46, "NF_Z_62-010_(1973)" },
+  {   46, "iso-ir-25" },
+  {   46, "ISO646-FR1" },
+  {   46, "csISO25French" },
+  {   47, "Latin-greek-1" },
+  {   47, "iso-ir-27" },
+  {   47, "csISO27LatinGreek1" },
+  {   48, "ISO_5427" },
+  {   48, "iso-ir-37" },
+  {   48, "csISO5427Cyrillic" },
+  {   49, "JIS_C6226-1978" },
+  {   49, "iso-ir-42" },
+  {   49, "csISO42JISC62261978" },
+  {   50, "BS_viewdata" },
+  {   50, "iso-ir-47" },
+  {   50, "csISO47BSViewdata" },
+  {   51, "INIS" },
+  {   51, "iso-ir-49" },
+  {   51, "csISO49INIS" },
+  {   52, "INIS-8" },
+  {   52, "iso-ir-50" },
+  {   52, "csISO50INIS8" },
+  {   53, "INIS-cyrillic" },
+  {   53, "iso-ir-51" },
+  {   53, "csISO51INISCyrillic" },
+  {   54, "ISO_5427:1981" },
+  {   54, "iso-ir-54" },
+  {   54, "ISO5427Cyrillic1981" },
+  {   54, "csISO54271981" },
+  {   55, "ISO_5428:1980" },
+  {   55, "iso-ir-55" },
+  {   55, "csISO5428Greek" },
+  {   56, "GB_1988-80" },
+  {   56, "iso-ir-57" },
+  {   56, "cn" },
+  {   56, "ISO646-CN" },
+  {   56, "csISO57GB1988" },
+  {   57, "GB_2312-80" },
+  {   57, "iso-ir-58" },
+  {   57, "chinese" },
+  {   57, "csISO58GB231280" },
+  {   58, "NS_4551-2" },
+  {   58, "ISO646-NO2" },
+  {   58, "iso-ir-61" },
+  {   58, "no2" },
+  {   58, "csISO61Norwegian2" },
+  {   59, "videotex-suppl" },
+  {   59, "iso-ir-70" },
+  {   59, "csISO70VideotexSupp1" },
+  {   60, "PT2" },
+  {   60, "iso-ir-84" },
+  {   60, "ISO646-PT2" },
+  {   60, "csISO84Portuguese2" },
+  {   61, "ES2" },
+  {   61, "iso-ir-85" },
+  {   61, "ISO646-ES2" },
+  {   61, "csISO85Spanish2" },
+  {   62, "MSZ_7795.3" },
+  {   62, "iso-ir-86" },
+  {   62, "ISO646-HU" },
+  {   62, "hu" },
+  {   62, "csISO86Hungarian" },
+  {   63, "JIS_C6226-1983" },
+  {   63, "iso-ir-87" },
+  {   63, "x0208" },
+  {   63, "JIS_X0208-1983" },
+  {   63, "csISO87JISX0208" },
+  {   64, "greek7" },
+  {   64, "iso-ir-88" },
+  {   64, "csISO88Greek7" },
+  {   65, "ASMO_449" },
+  {   65, "ISO_9036" },
+  {   65, "arabic7" },
+  {   65, "iso-ir-89" },
+  {   65, "csISO89ASMO449" },
+  {   66, "iso-ir-90" },
+  {   66, "csISO90" },
+  {   67, "JIS_C6229-1984-a" },
+  {   67, "iso-ir-91" },
+  {   67, "jp-ocr-a" },
+  {   67, "csISO91JISC62291984a" },
+  {   68, "JIS_C6229-1984-b" },
+  {   68, "iso-ir-92" },
+  {   68, "ISO646-JP-OCR-B" },
+  {   68, "jp-ocr-b" },
+  {   68, "csISO92JISC62991984b" },
+  {   69, "JIS_C6229-1984-b-add" },
+  {   69, "iso-ir-93" },
+  {   69, "jp-ocr-b-add" },
+  {   69, "csISO93JIS62291984badd" },
+  {   70, "JIS_C6229-1984-hand" },
+  {   70, "iso-ir-94" },
+  {   70, "jp-ocr-hand" },
+  {   70, "csISO94JIS62291984hand" },
+  {   71, "JIS_C6229-1984-hand-add" },
+  {   71, "iso-ir-95" },
+  {   71, "jp-ocr-hand-add" },
+  {   71, "csISO95JIS62291984handadd" },
+  {   72, "JIS_C6229-1984-kana" },
+  {   72, "iso-ir-96" },
+  {   72, "csISO96JISC62291984kana" },
+  {   73, "ISO_2033-1983" },
+  {   73, "iso-ir-98" },
+  {   73, "e13b" },
+  {   73, "csISO2033" },
+  {   74, "ANSI_X3.110-1983" },
+  {   74, "iso-ir-99" },
+  {   74, "CSA_T500-1983" },
+  {   74, "NAPLPS" },
+  {   74, "csISO99NAPLPS" },
+  {   75, "T.61-7bit" },
+  {   75, "iso-ir-102" },
+  {   75, "csISO102T617bit" },
+  {   76, "T.61-8bit" },
+  {   76, "T.61" },
+  {   76, "iso-ir-103" },
+  {   76, "csISO103T618bit" },
+  {   77, "ECMA-cyrillic" },
+  {   77, "iso-ir-111" },
+  {   77, "KOI8-E" },
+  {   77, "csISO111ECMACyrillic" },
+  {   78, "CSA_Z243.4-1985-1" },
+  {   78, "iso-ir-121" },
+  {   78, "ISO646-CA" },
+  {   78, "csa7-1" },
+  {   78, "csa71" },
+  {   78, "ca" },
+  {   78, "csISO121Canadian1" },
+  {   79, "CSA_Z243.4-1985-2" },
+  {   79, "iso-ir-122" },
+  {   79, "ISO646-CA2" },
+  {   79, "csa7-2" },
+  {   79, "csa72" },
+  {   79, "csISO122Canadian2" },
+  {   80, "CSA_Z243.4-1985-gr" },
+  {   80, "iso-ir-123" },
+  {   80, "csISO123CSAZ24341985gr" },
+  {   81, "ISO_8859-6-E" },
+  {   81, "csISO88596E" },
+  {   81, "ISO-8859-6-E" },
+  {   82, "ISO_8859-6-I" },
+  {   82, "csISO88596I" },
+  {   82, "ISO-8859-6-I" },
+  {   83, "T.101-G2" },
+  {   83, "iso-ir-128" },
+  {   83, "csISO128T101G2" },
+  {   84, "ISO_8859-8-E" },
+  {   84, "csISO88598E" },
+  {   84, "ISO-8859-8-E" },
+  {   85, "ISO_8859-8-I" },
+  {   85, "csISO88598I" },
+  {   85, "ISO-8859-8-I" },
+  {   86, "CSN_369103" },
+  {   86, "iso-ir-139" },
+  {   86, "csISO139CSN369103" },
+  {   87, "JUS_I.B1.002" },
+  {   87, "iso-ir-141" },
+  {   87, "ISO646-YU" },
+  {   87, "js" },
+  {   87, "yu" },
+  {   87, "csISO141JUSIB1002" },
+  {   88, "IEC_P27-1" },
+  {   88, "iso-ir-143" },
+  {   88, "csISO143IECP271" },
+  {   89, "JUS_I.B1.003-serb" },
+  {   89, "iso-ir-146" },
+  {   89, "serbian" },
+  {   89, "csISO146Serbian" },
+  {   90, "JUS_I.B1.003-mac" },
+  {   90, "macedonian" },
+  {   90, "iso-ir-147" },
+  {   90, "csISO147Macedonian" },
+  {   91, "greek-ccitt" },
+  {   91, "iso-ir-150" },
+  {   91, "csISO150" },
+  {   91, "csISO150GreekCCITT" },
+  {   92, "NC_NC00-10:81" },
+  {   92, "cuba" },
+  {   92, "iso-ir-151" },
+  {   92, "ISO646-CU" },
+  {   92, "csISO151Cuba" },
+  {   93, "ISO_6937-2-25" },
+  {   93, "iso-ir-152" },
+  {   93, "csISO6937Add" },
+  {   94, "GOST_19768-74" },
+  {   94, "ST_SEV_358-88" },
+  {   94, "iso-ir-153" },
+  {   94, "csISO153GOST1976874" },
+  {   95, "ISO_8859-supp" },
+  {   95, "iso-ir-154" },
+  {   95, "latin1-2-5" },
+  {   95, "csISO8859Supp" },
+  {   96, "ISO_10367-box" },
+  {   96, "iso-ir-155" },
+  {   96, "csISO10367Box" },
+  {   97, "latin-lap" },
+  {   97, "lap" },
+  {   97, "iso-ir-158" },
+  {   97, "csISO158Lap" },
+  {   98, "JIS_X0212-1990" },
+  {   98, "x0212" },
+  {   98, "iso-ir-159" },
+  {   98, "csISO159JISX02121990" },
+  {   99, "DS_2089" },
+  {   99, "DS2089" },
+  {   99, "ISO646-DK" },
+  {   99, "dk" },
+  {   99, "csISO646Danish" },
+  {  100, "us-dk" },
+  {  100, "csUSDK" },
+  {  101, "dk-us" },
+  {  101, "csDKUS" },
+  {  102, "KSC5636" },
+  {  102, "ISO646-KR" },
+  {  102, "csKSC5636" },
+  {  103, "UNICODE-1-1-UTF-7" },
+  {  103, "csUnicode11UTF7" },
+  {  104, "ISO-2022-CN" },
+  {  104, "csISO2022CN" },
+  {  105, "ISO-2022-CN-EXT" },
+  {  105, "csISO2022CNEXT" },
+#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
+  {  106, "UTF-8" },
+  {  106, "csUTF8" },
+  {  109, "ISO-8859-13" },
+  {  109, "csISO885913" },
+  {  110, "ISO-8859-14" },
+  {  110, "iso-ir-199" },
+  {  110, "ISO_8859-14:1998" },
+  {  110, "ISO_8859-14" },
+  {  110, "latin8" },
+  {  110, "iso-celtic" },
+  {  110, "l8" },
+  {  110, "csISO885914" },
+  {  111, "ISO-8859-15" },
+  {  111, "ISO_8859-15" },
+  {  111, "Latin-9" },
+  {  111, "csISO885915" },
+  {  112, "ISO-8859-16" },
+  {  112, "iso-ir-226" },
+  {  112, "ISO_8859-16:2001" },
+  {  112, "ISO_8859-16" },
+  {  112, "latin10" },
+  {  112, "l10" },
+  {  112, "csISO885916" },
+  {  113, "GBK" },
+  {  113, "CP936" },
+  {  113, "MS936" },
+  {  113, "windows-936" },
+  {  113, "csGBK" },
+  {  114, "GB18030" },
+  {  114, "csGB18030" },
+  {  115, "OSD_EBCDIC_DF04_15" },
+  {  115, "csOSDEBCDICDF0415" },
+  {  116, "OSD_EBCDIC_DF03_IRV" },
+  {  116, "csOSDEBCDICDF03IRV" },
+  {  117, "OSD_EBCDIC_DF04_1" },
+  {  117, "csOSDEBCDICDF041" },
+  {  118, "ISO-11548-1" },
+  {  118, "ISO_11548-1" },
+  {  118, "ISO_TR_11548-1" },
+  {  118, "csISO115481" },
+  {  119, "KZ-1048" },
+  {  119, "STRK1048-2002" },
+  {  119, "RK1048" },
+  {  119, "csKZ1048" },
+  { 1000, "ISO-10646-UCS-2" },
+  { 1000, "csUnicode" },
+  { 1001, "ISO-10646-UCS-4" },
+  { 1001, "csUCS4" },
+  { 1002, "ISO-10646-UCS-Basic" },
+  { 1002, "csUnicodeASCII" },
+  { 1003, "ISO-10646-Unicode-Latin1" },
+  { 1003, "csUnicodeLatin1" },
+  { 1003, "ISO-10646" },
+  { 1004, "ISO-10646-J-1" },
+  { 1004, "csUnicodeJapanese" },
+  { 1005, "ISO-Unicode-IBM-1261" },
+  { 1005, "csUnicodeIBM1261" },
+  { 1006, "ISO-Unicode-IBM-1268" },
+  { 1006, "csUnicodeIBM1268" },
+  { 1007, "ISO-Unicode-IBM-1276" },
+  { 1007, "csUnicodeIBM1276" },
+  { 1008, "ISO-Unicode-IBM-1264" },
+  { 1008, "csUnicodeIBM1264" },
+  { 1009, "ISO-Unicode-IBM-1265" },
+  { 1009, "csUnicodeIBM1265" },
+  { 1010, "UNICODE-1-1" },
+  { 1010, "csUnicode11" },
+  { 1011, "SCSU" },
+  { 1011, "csSCSU" },
+  { 1012, "UTF-7" },
+  { 1012, "csUTF7" },
+  { 1013, "UTF-16BE" },
+  { 1013, "csUTF16BE" },
+  { 1014, "UTF-16LE" },
+  { 1014, "csUTF16LE" },
+  { 1015, "UTF-16" },
+  { 1015, "csUTF16" },
+  { 1016, "CESU-8" },
+  { 1016, "csCESU8" },
+  { 1016, "csCESU-8" },
+  { 1017, "UTF-32" },
+  { 1017, "csUTF32" },
+  { 1018, "UTF-32BE" },
+  { 1018, "csUTF32BE" },
+  { 1019, "UTF-32LE" },
+  { 1019, "csUTF32LE" },
+  { 1020, "BOCU-1" },
+  { 1020, "csBOCU1" },
+  { 1020, "csBOCU-1" },
+  { 1021, "UTF-7-IMAP" },
+  { 1021, "csUTF7IMAP" },
+  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
+  { 2000, "csWindows30Latin1" },
+  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
+  { 2001, "csWindows31Latin1" },
+  { 2002, "ISO-8859-2-Windows-Latin-2" },
+  { 2002, "csWindows31Latin2" },
+  { 2003, "ISO-8859-9-Windows-Latin-5" },
+  { 2003, "csWindows31Latin5" },
+  { 2004, "hp-roman8" },
+  { 2004, "roman8" },
+  { 2004, "r8" },
+  { 2004, "csHPRoman8" },
+  { 2005, "Adobe-Standard-Encoding" },
+  { 2005, "csAdobeStandardEncoding" },
+  { 2006, "Ventura-US" },
+  { 2006, "csVenturaUS" },
+  { 2007, "Ventura-International" },
+  { 2007, "csVenturaInternational" },
+  { 2008, "DEC-MCS" },
+  { 2008, "dec" },
+  { 2008, "csDECMCS" },
+  { 2009, "IBM850" },
+  { 2009, "cp850" },
+  { 2009, "850" },
+  { 2009, "csPC850Multilingual" },
+  { 2010, "IBM852" },
+  { 2010, "cp852" },
+  { 2010, "852" },
+  { 2010, "csPCp852" },
+  { 2011, "IBM437" },
+  { 2011, "cp437" },
+  { 2011, "437" },
+  { 2011, "csPC8CodePage437" },
+  { 2012, "PC8-Danish-Norwegian" },
+  { 2012, "csPC8DanishNorwegian" },
+  { 2013, "IBM862" },
+  { 2013, "cp862" },
+  { 2013, "862" },
+  { 2013, "csPC862LatinHebrew" },
+  { 2014, "PC8-Turkish" },
+  { 2014, "csPC8Turkish" },
+  { 2015, "IBM-Symbols" },
+  { 2015, "csIBMSymbols" },
+  { 2016, "IBM-Thai" },
+  { 2016, "csIBMThai" },
+  { 2017, "HP-Legal" },
+  { 2017, "csHPLegal" },
+  { 2018, "HP-Pi-font" },
+  { 2018, "csHPPiFont" },
+  { 2019, "HP-Math8" },
+  { 2019, "csHPMath8" },
+  { 2020, "Adobe-Symbol-Encoding" },
+  { 2020, "csHPPSMath" },
+  { 2021, "HP-DeskTop" },
+  { 2021, "csHPDesktop" },
+  { 2022, "Ventura-Math" },
+  { 2022, "csVenturaMath" },
+  { 2023, "Microsoft-Publishing" },
+  { 2023, "csMicrosoftPublishing" },
+  { 2024, "Windows-31J" },
+  { 2024, "csWindows31J" },
+  { 2025, "GB2312" },
+  { 2025, "csGB2312" },
+  { 2026, "Big5" },
+  { 2026, "csBig5" },
+  { 2027, "macintosh" },
+  { 2027, "mac" },
+  { 2027, "csMacintosh" },
+  { 2028, "IBM037" },
+  { 2028, "cp037" },
+  { 2028, "ebcdic-cp-us" },
+  { 2028, "ebcdic-cp-ca" },
+  { 2028, "ebcdic-cp-wt" },
+  { 2028, "ebcdic-cp-nl" },
+  { 2028, "csIBM037" },
+  { 2029, "IBM038" },
+  { 2029, "EBCDIC-INT" },
+  { 2029, "cp038" },
+  { 2029, "csIBM038" },
+  { 2030, "IBM273" },
+  { 2030, "CP273" },
+  { 2030, "csIBM273" },
+  { 2031, "IBM274" },
+  { 2031, "EBCDIC-BE" },
+  { 2031, "CP274" },
+  { 2031, "csIBM274" },
+  { 2032, "IBM275" },
+  { 2032, "EBCDIC-BR" },
+  { 2032, "cp275" },
+  { 2032, "csIBM275" },
+  { 2033, "IBM277" },
+  { 2033, "EBCDIC-CP-DK" },
+  { 2033, "EBCDIC-CP-NO" },
+  { 2033, "csIBM277" },
+  { 2034, "IBM278" },
+  { 2034, "CP278" },
+  { 2034, "ebcdic-cp-fi" },
+  { 2034, "ebcdic-cp-se" },
+  { 2034, "csIBM278" },
+  { 2035, "IBM280" },
+  { 2035, "CP280" },
+  { 2035, "ebcdic-cp-it" },
+  { 2035, "csIBM280" },
+  { 2036, "IBM281" },
+  { 2036, "EBCDIC-JP-E" },
+  { 2036, "cp281" },
+  { 2036, "csIBM281" },
+  { 2037, "IBM284" },
+  { 2037, "CP284" },
+  { 2037, "ebcdic-cp-es" },
+  { 2037, "csIBM284" },
+  { 2038, "IBM285" },
+  { 2038, "CP285" },
+  { 2038, "ebcdic-cp-gb" },
+  { 2038, "csIBM285" },
+  { 2039, "IBM290" },
+  { 2039, "cp290" },
+  { 2039, "EBCDIC-JP-kana" },
+  { 2039, "csIBM290" },
+  { 2040, "IBM297" },
+  { 2040, "cp297" },
+  { 2040, "ebcdic-cp-fr" },
+  { 2040, "csIBM297" },
+  { 2041, "IBM420" },
+  { 2041, "cp420" },
+  { 2041, "ebcdic-cp-ar1" },
+  { 2041, "csIBM420" },
+  { 2042, "IBM423" },
+  { 2042, "cp423" },
+  { 2042, "ebcdic-cp-gr" },
+  { 2042, "csIBM423" },
+  { 2043, "IBM424" },
+  { 2043, "cp424" },
+  { 2043, "ebcdic-cp-he" },
+  { 2043, "csIBM424" },
+  { 2044, "IBM500" },
+  { 2044, "CP500" },
+  { 2044, "ebcdic-cp-be" },
+  { 2044, "ebcdic-cp-ch" },
+  { 2044, "csIBM500" },
+  { 2045, "IBM851" },
+  { 2045, "cp851" },
+  { 2045, "851" },
+  { 2045, "csIBM851" },
+  { 2046, "IBM855" },
+  { 2046, "cp855" },
+  { 2046, "855" },
+  { 2046, "csIBM855" },
+  { 2047, "IBM857" },
+  { 2047, "cp857" },
+  { 2047, "857" },
+  { 2047, "csIBM857" },
+  { 2048, "IBM860" },
+  { 2048, "cp860" },
+  { 2048, "860" },
+  { 2048, "csIBM860" },
+  { 2049, "IBM861" },
+  { 2049, "cp861" },
+  { 2049, "861" },
+  { 2049, "cp-is" },
+  { 2049, "csIBM861" },
+  { 2050, "IBM863" },
+  { 2050, "cp863" },
+  { 2050, "863" },
+  { 2050, "csIBM863" },
+  { 2051, "IBM864" },
+  { 2051, "cp864" },
+  { 2051, "csIBM864" },
+  { 2052, "IBM865" },
+  { 2052, "cp865" },
+  { 2052, "865" },
+  { 2052, "csIBM865" },
+  { 2053, "IBM868" },
+  { 2053, "CP868" },
+  { 2053, "cp-ar" },
+  { 2053, "csIBM868" },
+  { 2054, "IBM869" },
+  { 2054, "cp869" },
+  { 2054, "869" },
+  { 2054, "cp-gr" },
+  { 2054, "csIBM869" },
+  { 2055, "IBM870" },
+  { 2055, "CP870" },
+  { 2055, "ebcdic-cp-roece" },
+  { 2055, "ebcdic-cp-yu" },
+  { 2055, "csIBM870" },
+  { 2056, "IBM871" },
+  { 2056, "CP871" },
+  { 2056, "ebcdic-cp-is" },
+  { 2056, "csIBM871" },
+  { 2057, "IBM880" },
+  { 2057, "cp880" },
+  { 2057, "EBCDIC-Cyrillic" },
+  { 2057, "csIBM880" },
+  { 2058, "IBM891" },
+  { 2058, "cp891" },
+  { 2058, "csIBM891" },
+  { 2059, "IBM903" },
+  { 2059, "cp903" },
+  { 2059, "csIBM903" },
+  { 2060, "IBM904" },
+  { 2060, "cp904" },
+  { 2060, "904" },
+  { 2060, "csIBBM904" },
+  { 2061, "IBM905" },
+  { 2061, "CP905" },
+  { 2061, "ebcdic-cp-tr" },
+  { 2061, "csIBM905" },
+  { 2062, "IBM918" },
+  { 2062, "CP918" },
+  { 2062, "ebcdic-cp-ar2" },
+  { 2062, "csIBM918" },
+  { 2063, "IBM1026" },
+  { 2063, "CP1026" },
+  { 2063, "csIBM1026" },
+  { 2064, "EBCDIC-AT-DE" },
+  { 2064, "csIBMEBCDICATDE" },
+  { 2065, "EBCDIC-AT-DE-A" },
+  { 2065, "csEBCDICATDEA" },
+  { 2066, "EBCDIC-CA-FR" },
+  { 2066, "csEBCDICCAFR" },
+  { 2067, "EBCDIC-DK-NO" },
+  { 2067, "csEBCDICDKNO" },
+  { 2068, "EBCDIC-DK-NO-A" },
+  { 2068, "csEBCDICDKNOA" },
+  { 2069, "EBCDIC-FI-SE" },
+  { 2069, "csEBCDICFISE" },
+  { 2070, "EBCDIC-FI-SE-A" },
+  { 2070, "csEBCDICFISEA" },
+  { 2071, "EBCDIC-FR" },
+  { 2071, "csEBCDICFR" },
+  { 2072, "EBCDIC-IT" },
+  { 2072, "csEBCDICIT" },
+  { 2073, "EBCDIC-PT" },
+  { 2073, "csEBCDICPT" },
+  { 2074, "EBCDIC-ES" },
+  { 2074, "csEBCDICES" },
+  { 2075, "EBCDIC-ES-A" },
+  { 2075, "csEBCDICESA" },
+  { 2076, "EBCDIC-ES-S" },
+  { 2076, "csEBCDICESS" },
+  { 2077, "EBCDIC-UK" },
+  { 2077, "csEBCDICUK" },
+  { 2078, "EBCDIC-US" },
+  { 2078, "csEBCDICUS" },
+  { 2079, "UNKNOWN-8BIT" },
+  { 2079, "csUnknown8BiT" },
+  { 2080, "MNEMONIC" },
+  { 2080, "csMnemonic" },
+  { 2081, "MNEM" },
+  { 2081, "csMnem" },
+  { 2082, "VISCII" },
+  { 2082, "csVISCII" },
+  { 2083, "VIQR" },
+  { 2083, "csVIQR" },
+  { 2084, "KOI8-R" },
+  { 2084, "csKOI8R" },
+  { 2085, "HZ-GB-2312" },
+  { 2086, "IBM866" },
+  { 2086, "cp866" },
+  { 2086, "866" },
+  { 2086, "csIBM866" },
+  { 2087, "IBM775" },
+  { 2087, "cp775" },
+  { 2087, "csPC775Baltic" },
+  { 2088, "KOI8-U" },
+  { 2088, "csKOI8U" },
+  { 2089, "IBM00858" },
+  { 2089, "CCSID00858" },
+  { 2089, "CP00858" },
+  { 2089, "PC-Multilingual-850+euro" },
+  { 2089, "csIBM00858" },
+  { 2090, "IBM00924" },
+  { 2090, "CCSID00924" },
+  { 2090, "CP00924" },
+  { 2090, "ebcdic-Latin9--euro" },
+  { 2090, "csIBM00924" },
+  { 2091, "IBM01140" },
+  { 2091, "CCSID01140" },
+  { 2091, "CP01140" },
+  { 2091, "ebcdic-us-37+euro" },
+  { 2091, "csIBM01140" },
+  { 2092, "IBM01141" },
+  { 2092, "CCSID01141" },
+  { 2092, "CP01141" },
+  { 2092, "ebcdic-de-273+euro" },
+  { 2092, "csIBM01141" },
+  { 2093, "IBM01142" },
+  { 2093, "CCSID01142" },
+  { 2093, "CP01142" },
+  { 2093, "ebcdic-dk-277+euro" },
+  { 2093, "ebcdic-no-277+euro" },
+  { 2093, "csIBM01142" },
+  { 2094, "IBM01143" },
+  { 2094, "CCSID01143" },
+  { 2094, "CP01143" },
+  { 2094, "ebcdic-fi-278+euro" },
+  { 2094, "ebcdic-se-278+euro" },
+  { 2094, "csIBM01143" },
+  { 2095, "IBM01144" },
+  { 2095, "CCSID01144" },
+  { 2095, "CP01144" },
+  { 2095, "ebcdic-it-280+euro" },
+  { 2095, "csIBM01144" },
+  { 2096, "IBM01145" },
+  { 2096, "CCSID01145" },
+  { 2096, "CP01145" },
+  { 2096, "ebcdic-es-284+euro" },
+  { 2096, "csIBM01145" },
+  { 2097, "IBM01146" },
+  { 2097, "CCSID01146" },
+  { 2097, "CP01146" },
+  { 2097, "ebcdic-gb-285+euro" },
+  { 2097, "csIBM01146" },
+  { 2098, "IBM01147" },
+  { 2098, "CCSID01147" },
+  { 2098, "CP01147" },
+  { 2098, "ebcdic-fr-297+euro" },
+  { 2098, "csIBM01147" },
+  { 2099, "IBM01148" },
+  { 2099, "CCSID01148" },
+  { 2099, "CP01148" },
+  { 2099, "ebcdic-international-500+euro" },
+  { 2099, "csIBM01148" },
+  { 2100, "IBM01149" },
+  { 2100, "CCSID01149" },
+  { 2100, "CP01149" },
+  { 2100, "ebcdic-is-871+euro" },
+  { 2100, "csIBM01149" },
+  { 2101, "Big5-HKSCS" },
+  { 2101, "csBig5HKSCS" },
+  { 2102, "IBM1047" },
+  { 2102, "IBM-1047" },
+  { 2102, "csIBM1047" },
+  { 2103, "PTCP154" },
+  { 2103, "csPTCP154" },
+  { 2103, "PT154" },
+  { 2103, "CP154" },
+  { 2103, "Cyrillic-Asian" },
+  { 2104, "Amiga-1251" },
+  { 2104, "Ami1251" },
+  { 2104, "Amiga1251" },
+  { 2104, "Ami-1251" },
+  { 2104, "csAmiga1251" },
+  { 2104, "(Aliases" },
+  { 2104, "are" },
+  { 2104, "provided" },
+  { 2104, "for" },
+  { 2104, "historical" },
+  { 2104, "reasons" },
+  { 2104, "and" },
+  { 2104, "should" },
+  { 2104, "not" },
+  { 2104, "be" },
+  { 2104, "used)" },
+  { 2104, "[Malyshev]" },
+  { 2105, "KOI7-switched" },
+  { 2105, "csKOI7switched" },
+  { 2106, "BRF" },
+  { 2106, "csBRF" },
+  { 2107, "TSCII" },
+  { 2107, "csTSCII" },
+  { 2108, "CP51932" },
+  { 2108, "csCP51932" },
+  { 2109, "windows-874" },
+  { 2109, "cswindows874" },
+  { 2250, "windows-1250" },
+  { 2250, "cswindows1250" },
+  { 2251, "windows-1251" },
+  { 2251, "cswindows1251" },
+  { 2252, "windows-1252" },
+  { 2252, "cswindows1252" },
+  { 2253, "windows-1253" },
+  { 2253, "cswindows1253" },
+  { 2254, "windows-1254" },
+  { 2254, "cswindows1254" },
+  { 2255, "windows-1255" },
+  { 2255, "cswindows1255" },
+  { 2256, "windows-1256" },
+  { 2256, "cswindows1256" },
+  { 2257, "windows-1257" },
+  { 2257, "cswindows1257" },
+  { 2258, "windows-1258" },
+  { 2258, "cswindows1258" },
+  { 2259, "TIS-620" },
+  { 2259, "csTIS620" },
+  { 2259, "ISO-8859-11" },
+  { 2260, "CP50220" },
+  { 2260, "csCP50220" },
+
+#undef _GLIBCXX_GET_ENCODING_DATA
diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
index f1b2b359bdf..048f02a4bcd 100644
--- a/libstdc++-v3/include/bits/unicode.h
+++ b/libstdc++-v3/include/bits/unicode.h
@@ -32,7 +32,8 @@
 
 #if __cplusplus >= 202002L
 #include <array>
-#include <bit>
+#include <bit>      // bit_width
+#include <charconv> // __detail::__from_chars_alnum_to_val_table
 #include <cstdint>
 #include <bits/stl_algo.h>
 #include <bits/stl_iterator.h>
@@ -986,7 +987,7 @@ inline namespace __v15_1_0
       return __n;
     }
 
-    template<typename _CharT>
+  template<typename _CharT>
     consteval bool
     __literal_encoding_is_unicode()
     {
@@ -1056,6 +1057,53 @@ inline namespace __v15_1_0
   __literal_encoding_is_utf8()
   { return __literal_encoding_is_unicode<char>(); }
 
+  consteval bool
+  __literal_encoding_is_extended_ascii()
+  {
+    return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
+	     && 'a' == 0x61 && 'z' == 0x7a;
+  }
+
+  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
+  constexpr bool
+  __charset_alias_match(string_view __a, string_view __b)
+  {
+    // Map alphanumeric chars to their base 64 value, everything else to 127.
+    auto __map = [](char __c, bool& __num) -> unsigned char {
+      if (__c == '0') [[unlikely]]
+	return __num ? 0 : 127;
+      const auto __v = __detail::__from_chars_alnum_to_val(__c);
+      __num = __v < 10;
+      return __v;
+    };
+
+    auto __ptr_a = __a.begin(), __end_a = __a.end();
+    auto __ptr_b = __b.begin(), __end_b = __b.end();
+    bool __num_a = false, __num_b = false;
+
+    while (true)
+      {
+	// Find the value of the next alphanumeric character in each string.
+	unsigned char __val_a, __val_b;
+	while (__ptr_a != __end_a
+		 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
+	  ++__ptr_a;
+	while (__ptr_b != __end_b
+		 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
+	  ++__ptr_b;
+	// Stop when we reach the end of a string, or get a mismatch.
+	if (__ptr_a == __end_a)
+	  return __ptr_b == __end_b;
+	else if (__ptr_b == __end_b)
+	  return false;
+	else if (__val_a != __val_b)
+	  return false; // Found non-matching characters.
+	++__ptr_a;
+	++__ptr_b;
+      }
+    return true;
+  }
+
 } // namespace __unicode
 
 _GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index afbec6c3e6a..8fb8a2877ee 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1751,6 +1751,16 @@ ftms = {
   };
 };
 
+ftms = {
+  name = text_encoding;
+  values = {
+    v = 202306;
+    cxxmin = 26;
+    hosted = yes;
+    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
+  };
+};
+
 ftms = {
   name = to_string;
   values = {
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 9688b246ef4..9ba99deeda6 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2137,6 +2137,17 @@
 #undef __glibcxx_want_saturation_arithmetic
 
 // from version.def line 1755
+#if !defined(__cpp_lib_text_encoding)
+# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
+#  define __glibcxx_text_encoding 202306L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
+#   define __cpp_lib_text_encoding 202306L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
+#undef __glibcxx_want_text_encoding
+
+// from version.def line 1765
 #if !defined(__cpp_lib_to_string)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
 #  define __glibcxx_to_string 202306L
@@ -2147,7 +2158,7 @@
 #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
 #undef __glibcxx_want_to_string
 
-// from version.def line 1765
+// from version.def line 1775
 #if !defined(__cpp_lib_generator)
 # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
 #  define __glibcxx_generator 202207L
diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
new file mode 100644
index 00000000000..934103f5d88
--- /dev/null
+++ b/libstdc++-v3/include/std/text_encoding
@@ -0,0 +1,677 @@
+// <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/text_encoding
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TEXT_ENCODING
+#define _GLIBCXX_TEXT_ENCODING
+
+#pragma GCC system_header
+
+#include <bits/requires_hosted.h>
+
+#define __glibcxx_want_text_encoding
+#include <bits/version.h>
+
+#ifdef __cpp_lib_text_encoding
+#include <compare>
+#include <string_view>
+#include <bits/functional_hash.h> // hash
+#include <bits/ranges_util.h>     // view_interface
+#include <bits/unicode.h>         // __charset_alias_match
+#include <ext/numeric_traits.h>   // __int_traits
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  /**
+   * @brief An interface for accessing the IANA Character Sets registry.
+   * @ingroup locales
+   * @since C++23
+   */
+  struct text_encoding
+  {
+  private:
+    struct _Rep
+    {
+      using id = __INT_LEAST32_TYPE__;
+      id _M_id;
+      const char* _M_name;
+
+      friend constexpr bool
+      operator<(const _Rep& __r, id __m) noexcept
+      { return __r._M_id < __m; }
+
+      friend constexpr bool
+      operator==(const _Rep& __r, string_view __name) noexcept
+      { return __r._M_name == __name; }
+    };
+
+  public:
+    static constexpr size_t max_name_length = 63;
+
+    enum class id : _Rep::id
+    {
+      other = 1,
+      unknown = 2,
+      ASCII = 3,
+      ISOLatin1 = 4,
+      ISOLatin2 = 5,
+      ISOLatin3 = 6,
+      ISOLatin4 = 7,
+      ISOLatinCyrillic = 8,
+      ISOLatinArabic = 9,
+      ISOLatinGreek = 10,
+      ISOLatinHebrew = 11,
+      ISOLatin5 = 12,
+      ISOLatin6 = 13,
+      ISOTextComm = 14,
+      HalfWidthKatakana = 15,
+      JISEncoding = 16,
+      ShiftJIS = 17,
+      EUCPkdFmtJapanese = 18,
+      EUCFixWidJapanese = 19,
+      ISO4UnitedKingdom = 20,
+      ISO11SwedishForNames = 21,
+      ISO15Italian = 22,
+      ISO17Spanish = 23,
+      ISO21German = 24,
+      ISO60DanishNorwegian = 25,
+      ISO69French = 26,
+      ISO10646UTF1 = 27,
+      ISO646basic1983 = 28,
+      INVARIANT = 29,
+      ISO2IntlRefVersion = 30,
+      NATSSEFI = 31,
+      NATSSEFIADD = 32,
+      ISO10Swedish = 35,
+      KSC56011987 = 36,
+      ISO2022KR = 37,
+      EUCKR = 38,
+      ISO2022JP = 39,
+      ISO2022JP2 = 40,
+      ISO13JISC6220jp = 41,
+      ISO14JISC6220ro = 42,
+      ISO16Portuguese = 43,
+      ISO18Greek7Old = 44,
+      ISO19LatinGreek = 45,
+      ISO25French = 46,
+      ISO27LatinGreek1 = 47,
+      ISO5427Cyrillic = 48,
+      ISO42JISC62261978 = 49,
+      ISO47BSViewdata = 50,
+      ISO49INIS = 51,
+      ISO50INIS8 = 52,
+      ISO51INISCyrillic = 53,
+      ISO54271981 = 54,
+      ISO5428Greek = 55,
+      ISO57GB1988 = 56,
+      ISO58GB231280 = 57,
+      ISO61Norwegian2 = 58,
+      ISO70VideotexSupp1 = 59,
+      ISO84Portuguese2 = 60,
+      ISO85Spanish2 = 61,
+      ISO86Hungarian = 62,
+      ISO87JISX0208 = 63,
+      ISO88Greek7 = 64,
+      ISO89ASMO449 = 65,
+      ISO90 = 66,
+      ISO91JISC62291984a = 67,
+      ISO92JISC62991984b = 68,
+      ISO93JIS62291984badd = 69,
+      ISO94JIS62291984hand = 70,
+      ISO95JIS62291984handadd = 71,
+      ISO96JISC62291984kana = 72,
+      ISO2033 = 73,
+      ISO99NAPLPS = 74,
+      ISO102T617bit = 75,
+      ISO103T618bit = 76,
+      ISO111ECMACyrillic = 77,
+      ISO121Canadian1 = 78,
+      ISO122Canadian2 = 79,
+      ISO123CSAZ24341985gr = 80,
+      ISO88596E = 81,
+      ISO88596I = 82,
+      ISO128T101G2 = 83,
+      ISO88598E = 84,
+      ISO88598I = 85,
+      ISO139CSN369103 = 86,
+      ISO141JUSIB1002 = 87,
+      ISO143IECP271 = 88,
+      ISO146Serbian = 89,
+      ISO147Macedonian = 90,
+      ISO150 = 91,
+      ISO151Cuba = 92,
+      ISO6937Add = 93,
+      ISO153GOST1976874 = 94,
+      ISO8859Supp = 95,
+      ISO10367Box = 96,
+      ISO158Lap = 97,
+      ISO159JISX02121990 = 98,
+      ISO646Danish = 99,
+      USDK = 100,
+      DKUS = 101,
+      KSC5636 = 102,
+      Unicode11UTF7 = 103,
+      ISO2022CN = 104,
+      ISO2022CNEXT = 105,
+      UTF8 = 106,
+      ISO885913 = 109,
+      ISO885914 = 110,
+      ISO885915 = 111,
+      ISO885916 = 112,
+      GBK = 113,
+      GB18030 = 114,
+      OSDEBCDICDF0415 = 115,
+      OSDEBCDICDF03IRV = 116,
+      OSDEBCDICDF041 = 117,
+      ISO115481 = 118,
+      KZ1048 = 119,
+      UCS2 = 1000,
+      UCS4 = 1001,
+      UnicodeASCII = 1002,
+      UnicodeLatin1 = 1003,
+      UnicodeJapanese = 1004,
+      UnicodeIBM1261 = 1005,
+      UnicodeIBM1268 = 1006,
+      UnicodeIBM1276 = 1007,
+      UnicodeIBM1264 = 1008,
+      UnicodeIBM1265 = 1009,
+      Unicode11 = 1010,
+      SCSU = 1011,
+      UTF7 = 1012,
+      UTF16BE = 1013,
+      UTF16LE = 1014,
+      UTF16 = 1015,
+      CESU8 = 1016,
+      UTF32 = 1017,
+      UTF32BE = 1018,
+      UTF32LE = 1019,
+      BOCU1 = 1020,
+      UTF7IMAP = 1021,
+      Windows30Latin1 = 2000,
+      Windows31Latin1 = 2001,
+      Windows31Latin2 = 2002,
+      Windows31Latin5 = 2003,
+      HPRoman8 = 2004,
+      AdobeStandardEncoding = 2005,
+      VenturaUS = 2006,
+      VenturaInternational = 2007,
+      DECMCS = 2008,
+      PC850Multilingual = 2009,
+      PC8DanishNorwegian = 2012,
+      PC862LatinHebrew = 2013,
+      PC8Turkish = 2014,
+      IBMSymbols = 2015,
+      IBMThai = 2016,
+      HPLegal = 2017,
+      HPPiFont = 2018,
+      HPMath8 = 2019,
+      HPPSMath = 2020,
+      HPDesktop = 2021,
+      VenturaMath = 2022,
+      MicrosoftPublishing = 2023,
+      Windows31J = 2024,
+      GB2312 = 2025,
+      Big5 = 2026,
+      Macintosh = 2027,
+      IBM037 = 2028,
+      IBM038 = 2029,
+      IBM273 = 2030,
+      IBM274 = 2031,
+      IBM275 = 2032,
+      IBM277 = 2033,
+      IBM278 = 2034,
+      IBM280 = 2035,
+      IBM281 = 2036,
+      IBM284 = 2037,
+      IBM285 = 2038,
+      IBM290 = 2039,
+      IBM297 = 2040,
+      IBM420 = 2041,
+      IBM423 = 2042,
+      IBM424 = 2043,
+      PC8CodePage437 = 2011,
+      IBM500 = 2044,
+      IBM851 = 2045,
+      PCp852 = 2010,
+      IBM855 = 2046,
+      IBM857 = 2047,
+      IBM860 = 2048,
+      IBM861 = 2049,
+      IBM863 = 2050,
+      IBM864 = 2051,
+      IBM865 = 2052,
+      IBM868 = 2053,
+      IBM869 = 2054,
+      IBM870 = 2055,
+      IBM871 = 2056,
+      IBM880 = 2057,
+      IBM891 = 2058,
+      IBM903 = 2059,
+      IBM904 = 2060,
+      IBM905 = 2061,
+      IBM918 = 2062,
+      IBM1026 = 2063,
+      IBMEBCDICATDE = 2064,
+      EBCDICATDEA = 2065,
+      EBCDICCAFR = 2066,
+      EBCDICDKNO = 2067,
+      EBCDICDKNOA = 2068,
+      EBCDICFISE = 2069,
+      EBCDICFISEA = 2070,
+      EBCDICFR = 2071,
+      EBCDICIT = 2072,
+      EBCDICPT = 2073,
+      EBCDICES = 2074,
+      EBCDICESA = 2075,
+      EBCDICESS = 2076,
+      EBCDICUK = 2077,
+      EBCDICUS = 2078,
+      Unknown8BiT = 2079,
+      Mnemonic = 2080,
+      Mnem = 2081,
+      VISCII = 2082,
+      VIQR = 2083,
+      KOI8R = 2084,
+      HZGB2312 = 2085,
+      IBM866 = 2086,
+      PC775Baltic = 2087,
+      KOI8U = 2088,
+      IBM00858 = 2089,
+      IBM00924 = 2090,
+      IBM01140 = 2091,
+      IBM01141 = 2092,
+      IBM01142 = 2093,
+      IBM01143 = 2094,
+      IBM01144 = 2095,
+      IBM01145 = 2096,
+      IBM01146 = 2097,
+      IBM01147 = 2098,
+      IBM01148 = 2099,
+      IBM01149 = 2100,
+      Big5HKSCS = 2101,
+      IBM1047 = 2102,
+      PTCP154 = 2103,
+      Amiga1251 = 2104,
+      KOI7switched = 2105,
+      BRF = 2106,
+      TSCII = 2107,
+      CP51932 = 2108,
+      windows874 = 2109,
+      windows1250 = 2250,
+      windows1251 = 2251,
+      windows1252 = 2252,
+      windows1253 = 2253,
+      windows1254 = 2254,
+      windows1255 = 2255,
+      windows1256 = 2256,
+      windows1257 = 2257,
+      windows1258 = 2258,
+      TIS620 = 2259,
+      CP50220 = 2260
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+
+    constexpr explicit
+    text_encoding(string_view __enc) noexcept
+    : _M_rep(_S_find_name(__enc))
+    {
+      __enc.copy(_M_name, max_name_length);
+    }
+
+    // @pre i has the value of one of the enumerators of id.
+    constexpr
+    text_encoding(id __i) noexcept
+    : _M_rep(_S_find_id(__i))
+    {
+      if (string_view __name(_M_rep->_M_name); !__name.empty())
+	__name.copy(_M_name, max_name_length);
+    }
+
+    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
+
+    constexpr const char* name() const noexcept { return _M_name; }
+
+    struct aliases_view : ranges::view_interface<aliases_view>
+    {
+    private:
+      class _Iterator;
+      struct _Sentinel { };
+
+    public:
+      constexpr _Iterator begin() const noexcept;
+      constexpr _Sentinel end() const noexcept { return {}; }
+
+    private:
+      friend struct text_encoding;
+
+      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
+
+      const _Rep* _M_begin = nullptr;
+    };
+
+    constexpr aliases_view
+    aliases() const noexcept
+    {
+      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __a,
+	       const text_encoding& __b) noexcept
+    {
+      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
+	return _S_comp(__a._M_name, __b._M_name);
+      else
+	return __a.mib() == __b.mib();
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __encoding, id __i) noexcept
+    { return __encoding.mib() == __i; }
+
+#if __CHAR_BIT__ == 8
+    static consteval text_encoding
+    literal() noexcept
+    {
+#ifdef __GNUC_EXECUTION_CHARSET_NAME
+      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
+#elif defined __clang_literal_encoding__
+      return text_encoding(__clang_literal_encoding__);
+#else
+      return text_encoding();
+#endif
+    }
+
+    static text_encoding
+    environment();
+
+    template<id _Id>
+      static bool
+      environment_is()
+      { return text_encoding(_Id)._M_is_environment(); }
+#else
+    static text_encoding literal() = delete;
+    static text_encoding environment() = delete;
+    template<id> static bool environment_is() = delete;
+#endif
+
+  private:
+    const _Rep* _M_rep = _S_reps + 1; // id::unknown
+    char _M_name[max_name_length + 1] = {0};
+
+    bool
+    _M_is_environment() const;
+
+    static inline constexpr _Rep _S_reps[] = {
+      { 1, "" }, { 2, "" },
+#define _GLIBCXX_GET_ENCODING_DATA
+#include <bits/text_encoding-data.h>
+#ifdef _GLIBCXX_GET_ENCODING_DATA
+# error "Invalid text_encoding data"
+#endif
+      { 9999, nullptr }, // sentinel
+    };
+
+    static constexpr bool
+    _S_comp(string_view __a, string_view __b)
+    { return __unicode::__charset_alias_match(__a, __b); }
+
+    static constexpr const _Rep*
+    _S_find_name(string_view __name) noexcept
+    {
+#ifdef _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET
+      // Optimize the common UTF-8 case to avoid a linear search through all
+      // strings in the table using the _S_comp function.
+      if (__name == "UTF-8")
+	return _S_reps + 2 + _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET;
+#endif
+
+      // The first two array elements (other and unknown) don't have names.
+      // The last element is a sentinel that can never match anything.
+      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
+      for (auto __r = __first; __r != __end; ++__r)
+	if (_S_comp(__r->_M_name, __name))
+	  {
+	    // Might have matched an alias. Find the first entry for this ID.
+	    const auto __id = __r->_M_id;
+	    while (__r[-1]._M_id == __id)
+	      --__r;
+	    return __r;
+	  }
+      return _S_reps; // id::other
+    }
+
+    static constexpr const _Rep*
+    _S_find_id(id __id) noexcept
+    {
+      const auto __i = (_Rep::id)__id;
+      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
+      if (__r->_M_id == __i) [[likely]]
+	return __r;
+      else
+	{
+	  // Preconditions: i has the value of one of the enumerators of id.
+	  __glibcxx_assert(__r->_M_id == __i);
+	  return _S_reps + 1; // id::unknown
+	}
+    }
+  };
+
+  template<>
+    struct hash<text_encoding>
+    {
+      size_t
+      operator()(const text_encoding& __enc) const noexcept
+      { return std::hash<text_encoding::id>()(__enc.mib()); }
+    };
+
+  class text_encoding::aliases_view::_Iterator
+  {
+  public:
+    using value_type = const char*;
+    using reference = const char*;
+    using difference_type = int;
+
+    constexpr _Iterator() = default;
+
+    constexpr value_type
+    operator*() const
+    {
+      if (_M_dereferenceable()) [[likely]]
+	return _M_rep->_M_name;
+      else
+	{
+	  __glibcxx_assert(_M_dereferenceable());
+	  return "";
+	}
+    }
+
+    constexpr _Iterator&
+    operator++()
+    {
+      if (_M_dereferenceable()) [[likely]]
+      ++_M_rep;
+      else
+	{
+	  __glibcxx_assert(_M_dereferenceable());
+	  *this = _Iterator{};
+	}
+      return *this;
+    }
+
+    constexpr _Iterator&
+    operator--()
+    {
+      const bool __decrementable
+	= _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
+      if (__decrementable) [[likely]]
+      --_M_rep;
+      else
+	{
+	  __glibcxx_assert(__decrementable);
+	  *this = _Iterator{};
+	}
+      return *this;
+    }
+
+    constexpr _Iterator
+    operator++(int)
+    {
+      auto __it = *this;
+      ++*this;
+      return __it;
+    }
+
+    constexpr _Iterator
+    operator--(int)
+    {
+      auto __it = *this;
+      --*this;
+      return __it;
+    }
+
+    constexpr value_type
+    operator[](difference_type __n) const
+    { return *(*this + __n); }
+
+    constexpr _Iterator&
+    operator+=(difference_type __n)
+    {
+      if (_M_rep != nullptr)
+	{
+	  if (__n > 0)
+	    {
+	      if (__n < (std::end(_S_reps) - _M_rep)
+			  && _M_rep[__n - 1]._M_id == _M_id) [[likely]]
+		 _M_rep += __n;
+	      else
+		*this == _Iterator{};
+	    }
+	  else if (__n < 0)
+	    {
+	      if (__n > (_S_reps - _M_rep)
+		    && _M_rep[__n]._M_id == _M_id) [[likely]]
+		 _M_rep += __n;
+	      else
+		*this == _Iterator{};
+	    }
+	}
+      __glibcxx_assert(_M_rep != nullptr);
+      return *this;
+    }
+
+    constexpr _Iterator&
+    operator-=(difference_type __n)
+    {
+      using _Traits = __gnu_cxx::__int_traits<difference_type>;
+      if (__n == _Traits::__min) [[unlikely]]
+	return operator+=(_Traits::__max);
+      return operator+=(-__n);
+    }
+
+    constexpr difference_type
+    operator-(const _Iterator& __i) const
+    {
+      if (_M_id == __i._M_id)
+	return _M_rep - __i._M_rep;
+      __glibcxx_assert(_M_id == __i._M_id);
+      return __gnu_cxx::__int_traits<difference_type>::__max;
+    }
+
+    constexpr bool
+    operator==(const _Iterator&) const = default;
+
+    constexpr bool
+    operator==(_Sentinel) const noexcept
+    { return !_M_dereferenceable(); }
+
+    constexpr strong_ordering
+    operator<=>(const _Iterator& __i) const
+    {
+      __glibcxx_assert(_M_id == __i._M_id);
+      return _M_rep <=> __i._M_rep;
+    }
+
+    friend constexpr _Iterator
+    operator+(_Iterator __i, difference_type __n)
+    {
+      __i += __n;
+      return __i;
+    }
+
+    friend constexpr _Iterator
+    operator+(difference_type __n, _Iterator __i)
+    {
+      __i += __n;
+      return __i;
+    }
+
+    friend constexpr _Iterator
+    operator-(_Iterator __i, difference_type __n)
+    {
+      __i -= __n;
+      return __i;
+    }
+
+  private:
+    friend class text_encoding;
+
+    constexpr explicit
+    _Iterator(const _Rep* __r) noexcept
+    : _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
+    { }
+
+    constexpr bool
+    _M_dereferenceable() const noexcept
+    { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
+
+    const _Rep* _M_rep = nullptr;
+    _Rep::id _M_id = 0;
+  };
+
+  constexpr auto
+  text_encoding::aliases_view::begin() const noexcept
+  -> _Iterator
+  { return _Iterator(_M_begin); }
+
+namespace ranges
+{
+  // Opt-in to borrowed_range concept
+  template<>
+    inline constexpr bool
+    enable_borrowed_range<std::text_encoding::aliases_view> = true;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cpp_lib_text_encoding
+#endif // _GLIBCXX_TEXT_ENCODING
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 032a7aa58a2..a6c2ed4599f 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
         typename = strip_versioned_namespace(self._typename)
         return "{}<{}, {}>".format(typename, value_type, value)
 
+class StdTextEncodingPrinter(printer_base):
+    """Print a std::text_encoding."""
+
+    def __init__(self, typename, val):
+        self._val = val
+        self._typename = typename
+
+    def to_string(self):
+        rep = self._val['_M_rep'].dereference()
+        if rep['_M_id'] == 1:
+            return self._val['_M_name']
+        if rep['_M_id'] == 2:
+            return 'unknown'
+        return rep['_M_name']
+
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
 class RxPrinter(object):
@@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
 
     libstdcxx_printer.add_version('std::', 'integral_constant',
                                   StdIntegralConstantPrinter)
+    libstdcxx_printer.add_version('std::', 'text_encoding',
+                                  StdTextEncodingPrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
new file mode 100755
index 00000000000..2d6f3e4077a
--- /dev/null
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+#
+# Script to generate tables for libstdc++ std::text_encoding.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+#
+# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
+# the latest:
+# https://www.iana.org/assignments/character-sets/character-sets-1.csv
+# Then run this script and save the output to
+# include/bits/text_encoding-data.h
+
+import sys
+import csv
+
+if len(sys.argv) != 2:
+    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
+    sys.exit(1)
+
+print("// Generated by gen_text_encoding_data.py, do not edit.\n")
+print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
+print('# error "This is not a public header, do not include it directly"')
+print("#endif\n")
+
+
+charsets = {}
+with open(sys.argv[1], newline='') as f:
+    reader = csv.reader(f)
+    next(reader) # skip header row
+    for row in reader:
+        mib = int(row[2])
+        if mib in charsets:
+            raise ValueError("Multiple rows for mibEnum={}".format(mib))
+        name = row[1]
+        aliases = row[5].split()
+        # Ensure primary name comes first
+        if name in aliases:
+            aliases.remove(name)
+        charsets[mib] = [name] + aliases
+
+# Remove "NATS-DANO" and "NATS-DANO-ADD"
+charsets.pop(33, None)
+charsets.pop(34, None)
+
+count = 0
+for mib in sorted(charsets.keys()):
+    names = charsets[mib]
+    if names[0] == "UTF-8":
+        print("#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET {}".format(count))
+    for name in names:
+        print('  {{ {:4}, "{}" }},'.format(mib, name))
+    count += len(names)
+
+# <text_encoding> gives an error if this macro is left defined.
+# Do this last, so that the generated output is not usable unless we reach here.
+print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 7292ae70f81..37ba1491dea 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -43,7 +43,7 @@ experimental_dir =
 endif
 
 ## Keep this list sync'd with acinclude.m4:GLIBCXX_CONFIGURE.
-SUBDIRS = c++98 c++11 c++17 c++20 c++23 \
+SUBDIRS = c++98 c++11 c++17 c++20 c++23 c++26 \
 	$(filesystem_dir) $(backtrace_dir) $(experimental_dir)
 
 # Cross compiler support.
@@ -77,6 +77,7 @@ vpath % $(top_srcdir)/src/c++11
 vpath % $(top_srcdir)/src/c++17
 vpath % $(top_srcdir)/src/c++20
 vpath % $(top_srcdir)/src/c++23
+vpath % $(top_srcdir)/src/c++26
 if ENABLE_FILESYSTEM_TS
 vpath % $(top_srcdir)/src/filesystem
 endif
diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
new file mode 100644
index 00000000000..000ced1f501
--- /dev/null
+++ b/libstdc++-v3/src/c++26/Makefile.am
@@ -0,0 +1,109 @@
+## Makefile for the C++26 sources of the GNU C++ Standard library.
+##
+## Copyright (C) 1997-2023 Free Software Foundation, Inc.
+##
+## This file is part of the libstdc++ version 3 distribution.
+## Process this file with automake to produce Makefile.in.
+
+## This file is part of the GNU ISO C++ Library.  This library is free
+## software; you can redistribute it and/or modify it under the
+## terms of the GNU General Public License as published by the
+## Free Software Foundation; either version 3, or (at your option)
+## any later version.
+
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+## You should have received a copy of the GNU General Public License along
+## with this library; see the file COPYING3.  If not see
+## <http://www.gnu.org/licenses/>.
+
+include $(top_srcdir)/fragment.am
+
+# Convenience library for C++26 runtime.
+noinst_LTLIBRARIES = libc++26convenience.la
+
+headers =
+
+if ENABLE_EXTERN_TEMPLATE
+# XTEMPLATE_FLAGS = -fno-implicit-templates
+inst_sources =
+else
+# XTEMPLATE_FLAGS =
+inst_sources =
+endif
+
+sources = text_encoding.cc
+
+vpath % $(top_srcdir)/src/c++26
+
+
+if GLIBCXX_HOSTED
+libc__26convenience_la_SOURCES = $(sources)  $(inst_sources)
+else
+libc__26convenience_la_SOURCES =
+endif
+
+# AM_CXXFLAGS needs to be in each subdirectory so that it can be
+# modified in a per-library or per-sub-library way.  Need to manually
+# set this option because CONFIG_CXXFLAGS has to be after
+# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
+# as the occasion calls for it.
+AM_CXXFLAGS = \
+	-std=gnu++26 \
+	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
+	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
+	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
+	-fimplicit-templates
+
+AM_MAKEFLAGS = \
+	"gxx_include_dir=$(gxx_include_dir)"
+
+# Libtool notes
+
+# 1) In general, libtool expects an argument such as `--tag=CXX' when
+# using the C++ compiler, because that will enable the settings
+# detected when C++ support was being configured.  However, when no
+# such flag is given in the command line, libtool attempts to figure
+# it out by matching the compiler name in each configuration section
+# against a prefix of the command line.  The problem is that, if the
+# compiler name and its initial flags stored in the libtool
+# configuration file don't match those in the command line, libtool
+# can't decide which configuration to use, and it gives up.  The
+# correct solution is to add `--tag CXX' to LTCXXCOMPILE and maybe
+# CXXLINK, just after $(LIBTOOL), so that libtool doesn't have to
+# attempt to infer which configuration to use.
+#
+# The second tag argument, `--tag disable-shared` means that libtool
+# only compiles each source once, for static objects. In actuality,
+# glibcxx_lt_pic_flag and glibcxx_compiler_shared_flag are added to
+# the libtool command that is used create the object, which is
+# suitable for shared libraries.  The `--tag disable-shared` must be
+# placed after --tag CXX lest things CXX undo the affect of
+# disable-shared.
+
+# 2) Need to explicitly set LTCXXCOMPILE so that EXTRA_CXX_FLAGS is
+# last. (That way, things like -O2 passed down from the toplevel can
+# be overridden by --enable-debug.)
+LTCXXCOMPILE = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=compile $(CXX) $(TOPLEVEL_INCLUDES) \
+	$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CXXFLAGS) $(CXXFLAGS) $(EXTRA_CXX_FLAGS)
+
+LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
+
+# 3) We'd have a problem when building the shared libstdc++ object if
+# the rules automake generates would be used.  We cannot allow g++ to
+# be used since this would add -lstdc++ to the link line which of
+# course is problematic at this point.  So, we get the top-level
+# directory to configure libstdc++-v3 to use gcc as the C++
+# compilation driver.
+CXXLINK = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=link $(CXX) \
+	$(VTV_CXXLINKFLAGS) \
+	$(OPT_LDFLAGS) $(SECTION_LDFLAGS) $(AM_CXXFLAGS) $(LTLDFLAGS) -o $@
diff --git a/libstdc++-v3/src/c++26/Makefile.in b/libstdc++-v3/src/c++26/Makefile.in
new file mode 100644
index 00000000000..77e73b2b265
diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
new file mode 100644
index 00000000000..9a7df07db29
--- /dev/null
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -0,0 +1,91 @@
+// Definitions for <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <text_encoding>
+#include <locale>
+
+#ifdef _GLIBCXX_USE_NL_LANGINFO_L
+#include <locale.h>
+#include <langinfo.h>
+
+#if __CHAR_BIT__ == 8
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+text_encoding
+__locale_encoding(const char* name)
+{
+  text_encoding enc;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view s(codeset);
+	  if (s.size() < text_encoding::max_name_length)
+	    enc = text_encoding(s);
+	}
+      ::freelocale(loc);
+    }
+  return enc;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+std::text_encoding
+std::text_encoding::environment()
+{
+  return std::__locale_encoding("");
+}
+
+bool
+std::text_encoding::_M_is_environment() const
+{
+  bool matched = false;
+  if (locale_t loc = ::newlocale(LC_ALL_MASK, "", (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view sv(codeset);
+	  for (auto alias : aliases())
+	    if (__unicode::__charset_alias_match(alias, sv))
+	      {
+		matched = true;
+		break;
+	      }
+	}
+      ::freelocale(loc);
+    }
+  return matched;
+}
+
+std::text_encoding
+std::locale::encoding() const
+{
+  return std::__locale_encoding(name().c_str());
+}
+#endif // CHAR_BIT == 8
+
+#endif // _GLIBCXX_USE_NL_LANGINFO_L
diff --git a/libstdc++-v3/src/experimental/Makefile.am b/libstdc++-v3/src/experimental/Makefile.am
index 8259f986d95..6241430988e 100644
--- a/libstdc++-v3/src/experimental/Makefile.am
+++ b/libstdc++-v3/src/experimental/Makefile.am
@@ -47,10 +47,12 @@ libstdc__exp_la_SOURCES = $(sources)
 
 libstdc__exp_la_LIBADD = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 libstdc__exp_la_DEPENDENCIES = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 # AM_CXXFLAGS needs to be in each subdirectory so that it can be
diff --git a/libstdc++-v3/testsuite/22_locale/locale/encoding.cc b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
new file mode 100644
index 00000000000..18825fb88b9
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
@@ -0,0 +1,36 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <locale>
+#include <testsuite_hooks.h>
+
+void
+test_encoding()
+{
+  const std::locale c = std::locale::classic();
+  std::text_encoding c_enc = c.encoding();
+  VERIFY( c_enc == std::text_encoding::ASCII );
+
+  const std::locale fr = std::locale(ISO_8859(15, fr_FR));
+  std::text_encoding fr_enc = fr.encoding();
+  VERIFY( fr_enc == std::text_encoding::ISO885915 );
+
+  const std::locale en = std::locale(ISO_8859(1, en_US));
+  std::text_encoding en_enc = en.encoding();
+  VERIFY( en_enc == std::text_encoding::ISOLatin1 );
+
+#if __cpp_exceptions
+  try {
+    const std::locale c_utf8 = std::locale("C.UTF-8");
+    VERIFY( c_utf8.encoding() == std::text_encoding::UTF8 );
+  } catch (...) {
+  }
+#endif
+}
+
+int main()
+{
+  test_encoding();
+}
diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
new file mode 100644
index 00000000000..f6272ae998b
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+#include <format>
+
+using std::__unicode::__charset_alias_match;
+static_assert( __charset_alias_match("UTF-8", "utf8") == true );
+static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
+static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
+static_assert( __charset_alias_match("UTF-8", "ut8") == false );
+
+static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
+
+static_assert( __charset_alias_match("", "") == true );
+static_assert( __charset_alias_match("", ".") == true );
+static_assert( __charset_alias_match("--", "...") == true );
+static_assert( __charset_alias_match("--a", "a...") == true );
+static_assert( __charset_alias_match("--a010", "a..10.") == true );
+static_assert( __charset_alias_match("--a010", "a..1.0") == false );
+static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
new file mode 100644
index 00000000000..b9d93641de4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
@@ -0,0 +1,113 @@
+// { dg-do run { target c++26 } }
+
+#include <text_encoding>
+#include <string_view>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+constexpr void
+test_default_construct()
+{
+  std::text_encoding e0;
+  VERIFY( e0.mib() == std::text_encoding::unknown );
+  VERIFY( e0.name()[0] == '\0' ); // P2862R1 name() should never return null
+  VERIFY( e0.aliases().empty() );
+}
+
+constexpr void
+test_construct_by_name()
+{
+  std::string_view s;
+  std::text_encoding e0(s);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == s );
+  VERIFY( e0.aliases().empty() );
+
+  s = "not a real encoding";
+  std::text_encoding e1(s);
+  VERIFY( e1.mib() == std::text_encoding::other );
+  VERIFY( e1.name() == s );
+  VERIFY( e1.aliases().empty() );
+
+  VERIFY( e1 != e0 );
+  VERIFY( e1 == e0.mib() );
+
+  s = "utf8";
+  std::text_encoding e2(s);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == s );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == "UTF-8"sv );
+
+  s = "Latin-1"; // matches "latin1"
+  std::text_encoding e3(s);
+  VERIFY( e3.mib() == std::text_encoding::ISOLatin1 );
+  VERIFY( e3.name() == s );
+  VERIFY( ! e3.aliases().empty() );
+  VERIFY( e3.aliases().front() == "ISO_8859-1:1987"sv ); // primary name
+
+  s = "U.S."; // matches "us"
+  std::text_encoding e4(s);
+  VERIFY( e4.mib() == std::text_encoding::ASCII );
+  VERIFY( e4.name() == s );
+  VERIFY( ! e4.aliases().empty() );
+  VERIFY( e4.aliases().front() == "US-ASCII"sv ); // primary name
+}
+
+constexpr void
+test_construct_by_id()
+{
+  std::text_encoding e0(std::text_encoding::other);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == ""sv );
+  VERIFY( e0.aliases().empty() );
+
+  std::text_encoding e1(std::text_encoding::unknown);
+  VERIFY( e1.mib() == std::text_encoding::unknown );
+  VERIFY( e1.name() == ""sv );
+  VERIFY( e1.aliases().empty() );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == "UTF-8"sv );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == std::string_view(e2.name()) );
+  bool found = false;
+  for (auto alias : e2.aliases())
+    if (alias == "csUTF8"sv)
+    {
+      found = true;
+      break;
+    }
+  VERIFY( found );
+}
+
+constexpr void
+test_copy_construct()
+{
+  std::text_encoding e0;
+  std::text_encoding e1 = e0;
+  VERIFY( e1 == e0 );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  auto e3 = e2;
+  VERIFY( e3 == e2 );
+
+  e1 = e3;
+  VERIFY( e1 == e2 );
+}
+
+int main()
+{
+  auto run_tests = [] {
+    test_default_construct();
+    test_construct_by_name();
+    test_construct_by_id();
+    test_copy_construct();
+    return true;
+  };
+
+  run_tests();
+  static_assert( run_tests() );
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/members.cc b/libstdc++-v3/testsuite/std/text_encoding/members.cc
new file mode 100644
index 00000000000..0b0d6bd0c96
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/members.cc
@@ -0,0 +1,41 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <text_encoding>
+#include <string_view>
+#include <locale.h>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+void
+test_literal()
+{
+  const std::text_encoding lit = std::text_encoding::literal();
+  VERIFY( lit.name() == std::string_view(__GNUC_EXECUTION_CHARSET_NAME) );
+}
+
+void
+test_env()
+{
+  const std::text_encoding env = std::text_encoding::environment();
+
+  if (env.mib() == std::text_encoding::UTF8)
+    VERIFY( std::text_encoding::environment_is<std::text_encoding::UTF8>() );
+
+  ::setlocale(LC_ALL, ISO_8859(1, en_US));
+  const std::text_encoding env1 = std::text_encoding::environment();
+  VERIFY( env1 == env );
+
+  ::setlocale(LC_ALL, ISO_8859(15, fr_FR));
+  const std::text_encoding env2 = std::text_encoding::environment();
+  VERIFY( env2 == env );
+}
+
+int main()
+{
+  test_literal();
+  test_env();
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
new file mode 100644
index 00000000000..e22ab729d4f
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -0,0 +1,72 @@
+// { dg-do compile { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <text_encoding>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <text_encoding>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
+#endif
+
+#undef __cpp_lib_expected
+#include <version>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <version>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <version>"
+#endif
+
+#include <concepts>
+#include <ranges>
+static_assert( std::is_trivially_copyable_v<std::text_encoding> );
+
+using aliases_view = std::text_encoding::aliases_view;
+static_assert( std::copyable<aliases_view> );
+static_assert( std::ranges::view<aliases_view> );
+static_assert( std::ranges::random_access_range<aliases_view> );
+static_assert( std::ranges::borrowed_range<aliases_view> );
+static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
+			    const char*> );
+static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
+			    const char*> );
+
+#include <testsuite_hooks.h>
+
+constexpr bool
+test_constexpr_iterator()
+{
+  // This encoding has two aliases, "UTF-8" and "csUTF8".
+  const auto a = std::text_encoding(std::text_encoding::UTF8).aliases();
+  const auto begin = a.begin();
+  const auto end = a.end();
+  auto iter = begin;
+  VERIFY( *iter == *begin );
+  VERIFY( *iter == iter[0] );
+  VERIFY( iter[1] == begin[1] );
+  --++iter;
+  VERIFY( iter == begin );
+  auto iter2 = iter++;
+  VERIFY( iter2 == begin );
+  VERIFY( iter != begin );
+  iter2 = iter--;
+  VERIFY( iter2 != begin );
+  VERIFY( iter == begin );
+  iter++++; // Increments prvalue returned by operator++(int) instead of iter.
+  VERIFY( iter == iter2 );
+  iter----; // Decrements prvalue returned by operator++(int) instead of iter.
+  VERIFY( iter == begin );
+  const auto d = std::ranges::distance(a);
+  iter += d;
+  VERIFY( iter == end );
+  VERIFY( (iter - begin) == d );
+  VERIFY( (begin + 2) == iter );
+  VERIFY( (2 + begin) == iter );
+  VERIFY( iter[-1] == begin[1] );
+  iter -= d;
+  VERIFY( iter == begin );
+  VERIFY( *(iter + 1) == iter[1] );
+  VERIFY( (1 + iter - 1) == begin );
+  VERIFY( (-1 + (iter - -2) + -1) == begin );
+  return true;
+}
+static_assert( test_constexpr_iterator() );

^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH v4] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-16 14:06       ` [PATCH v4] " Jonathan Wakely
@ 2024-01-16 15:39         ` Jonathan Wakely
  2024-01-16 16:17           ` Jonathan Wakely
  0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-16 15:39 UTC (permalink / raw)
  To: Patrick Palka; +Cc: libstdc++, gcc-patches

On Tue, 16 Jan 2024 at 14:07, Jonathan Wakely wrote:
>
> On 15/01/24 19:09 -0500, Patrick Palka wrote:
> >> +    friend _Iterator
> >> +    operator+(_Iterator __i, difference_type __n)
> >
> >constexpr?
>
> Fixed. I've added tests that all iterator ops are usable in constant
> expressions, which found a bug in operator+= (it didn't let you
> increment one past the end of the range).

I found another bug in operator+= which is fixed and tested like so:

--- a/libstdc++-v3/include/std/text_encoding
+++ b/libstdc++-v3/include/std/text_encoding
@@ -584,7 +584,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
               *this == _Iterator{};
           }
       }
-      __glibcxx_assert(_M_rep != nullptr);
+      if (__n != 0)
+       __glibcxx_assert(_M_rep != nullptr);
      return *this;
    }

--- a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -67,6 +67,11 @@ test_constexpr_iterator()
  VERIFY( *(iter + 1) == iter[1] );
  VERIFY( (1 + iter - 1) == begin );
  VERIFY( (-1 + (iter - -2) + -1) == begin );
+
+  std::ranges::iterator_t<std::text_encoding::aliases_view> singular;
+  VERIFY( (singular + 0) == singular );
+  VERIFY( (singular - 0) == singular );
+
  return true;
}
static_assert( test_constexpr_iterator() );


^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH v4] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-16 15:39         ` Jonathan Wakely
@ 2024-01-16 16:17           ` Jonathan Wakely
  2024-01-17 12:14             ` [committed v5] " Jonathan Wakely
  0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-16 16:17 UTC (permalink / raw)
  To: Patrick Palka; +Cc: libstdc++, gcc-patches

On Tue, 16 Jan 2024 at 15:39, Jonathan Wakely <jwakely@redhat.com> wrote:
>
> On Tue, 16 Jan 2024 at 14:07, Jonathan Wakely wrote:
> >
> > On 15/01/24 19:09 -0500, Patrick Palka wrote:
> > >> +    friend _Iterator
> > >> +    operator+(_Iterator __i, difference_type __n)
> > >
> > >constexpr?
> >
> > Fixed. I've added tests that all iterator ops are usable in constant
> > expressions, which found a bug in operator+= (it didn't let you
> > increment one past the end of the range).
>
> I found another bug in operator+= which is fixed and tested like so:
>
> --- a/libstdc++-v3/include/std/text_encoding
> +++ b/libstdc++-v3/include/std/text_encoding
> @@ -584,7 +584,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>                *this == _Iterator{};
>            }
>        }
> -      __glibcxx_assert(_M_rep != nullptr);
> +      if (__n != 0)
> +       __glibcxx_assert(_M_rep != nullptr);
>       return *this;
>     }
>
> --- a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
> +++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
> @@ -67,6 +67,11 @@ test_constexpr_iterator()
>   VERIFY( *(iter + 1) == iter[1] );
>   VERIFY( (1 + iter - 1) == begin );
>   VERIFY( (-1 + (iter - -2) + -1) == begin );
> +
> +  std::ranges::iterator_t<std::text_encoding::aliases_view> singular;
> +  VERIFY( (singular + 0) == singular );
> +  VERIFY( (singular - 0) == singular );
> +
>   return true;
> }
> static_assert( test_constexpr_iterator() );


I'll also change this, after a suggestion from one of the paper
authors (Corentin):

--- a/libstdc++-v3/src/c++26/text_encoding.cc
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -38,7 +38,7 @@ text_encoding
__locale_encoding(const char* name)
{
  text_encoding enc;
-  if (locale_t loc = ::newlocale(LC_ALL_MASK, name, (locale_t)0))
+  if (locale_t loc = ::newlocale(LC_CTYPE_MASK, name, (locale_t)0))
    {
      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
       {
@@ -64,7 +64,7 @@ bool
std::text_encoding::_M_is_environment() const
{
  bool matched = false;
-  if (locale_t loc = ::newlocale(LC_ALL_MASK, "", (locale_t)0))
+  if (locale_t loc = ::newlocale(LC_CTYPE_MASK, "", (locale_t)0))
    {
      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
       {


^ permalink raw reply	[flat|nested] 9+ messages in thread
* [committed v5] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
  2024-01-16 16:17           ` Jonathan Wakely
@ 2024-01-17 12:14             ` Jonathan Wakely
  0 siblings, 0 replies; 9+ messages in thread
From: Jonathan Wakely @ 2024-01-17 12:14 UTC (permalink / raw)
  To: Patrick Palka; +Cc: libstdc++, gcc Patches, Ulrich Drepper

[-- Attachment #1: Type: text/plain, Size: 77 bytes --]

Here's the final version that I pushed.

Tested aarch64-linux, x86_64-linux.

[-- Attachment #2: patch.txt --]
[-- Type: text/plain, Size: 78095 bytes --]

commit df0a668b784556fe4317317d58961652d93d53de
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Jan 15 15:42:50 2024

    libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318]
    
    This is another C++26 change, approved in Varna 2023. We require a new
    static array of data that is extracted from the IANA Character Sets
    database. A new Python script to generate a header from the IANA CSV
    file is added.
    
    The text_encoding class is basically just a pointer to an {ID,name} pair
    in the static array. The aliases view is also just the same pointer (or
    empty), and the view's iterator moves forwards and backwards in the
    array while the array elements have the same ID (or to one element
    further, for a past-the-end iterator).
    
    Because those iterators refer to a global array that never goes out of
    scope, there's no reason they should every produce undefined behaviour
    or indeterminate values.  They should either have well-defined
    behaviour, or abort. The overhead of ensuring those properties is pretty
    low, so seems worth it.
    
    This means that an aliases_view iterator should never be able to access
    out-of-bounds. A non-value-initialized iterator always points to an
    element of the static array even when not dereferenceable (the array has
    unreachable entries at the start and end, which means that even a
    past-the-end iterator for the last encoding in the array still points to
    valid memory).  Dereferencing an iterator can always return a valid
    array element, or "" for a non-dereferenceable iterator (but doing so
    will abort when assertions are enabled).  In the language being proposed
    for C++26, dereferencing an invalid iterator erroneously returns "".
    Attempting to increment/decrement past the last/first element in the
    view is erroneously a no-op, so aborts when assertions are enabled, and
    doesn't change value otherwise.
    
    Similarly, constructing a std::text_encoding with an invalid id (one
    that doesn't have the value of an enumerator) erroneously behaves the
    same as constructing with id::unknown, or aborts with assertions
    enabled.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/113318
            * acinclude.m4 (GLIBCXX_CONFIGURE): Add c++26 directory.
            (GLIBCXX_CHECK_TEXT_ENCODING): Define.
            * config.h.in: Regenerate.
            * configure: Regenerate.
            * configure.ac: Use GLIBCXX_CHECK_TEXT_ENCODING.
            * include/Makefile.am: Add new headers.
            * include/Makefile.in: Regenerate.
            * include/bits/locale_classes.h (locale::encoding): Declare new
            member function.
            * include/bits/unicode.h (__charset_alias_match): New function.
            * include/bits/text_encoding-data.h: New file.
            * include/bits/version.def (text_encoding): Define.
            * include/bits/version.h: Regenerate.
            * include/std/text_encoding: New file.
            * src/Makefile.am: Add new subdirectory.
            * src/Makefile.in: Regenerate.
            * src/c++26/Makefile.am: New file.
            * src/c++26/Makefile.in: New file.
            * src/c++26/text_encoding.cc: New file.
            * src/experimental/Makefile.am: Include c++26 convenience
            library.
            * src/experimental/Makefile.in: Regenerate.
            * python/libstdcxx/v6/printers.py (StdTextEncodingPrinter): New
            printer.
            * scripts/gen_text_encoding_data.py: New file.
            * testsuite/22_locale/locale/encoding.cc: New test.
            * testsuite/ext/unicode/charset_alias_match.cc: New test.
            * testsuite/std/text_encoding/cons.cc: New test.
            * testsuite/std/text_encoding/members.cc: New test.
            * testsuite/std/text_encoding/requirements.cc: New test.
    
    Reviewed-by: Ulrich Drepper <drepper.fsp@gmail.com>
    Reviewed-by: Patrick Palka <ppalka@redhat.com>

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index e7cbf0fcf96..f9ba7ef744b 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -49,7 +49,7 @@ AC_DEFUN([GLIBCXX_CONFIGURE], [
   # Keep these sync'd with the list in Makefile.am.  The first provides an
   # expandable list at autoconf time; the second provides an expandable list
   # (i.e., shell variable) at configure time.
-  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
+  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/c++23 src/c++26 src/filesystem src/libbacktrace src/experimental doc po testsuite python])
   SUBDIRS='glibcxx_SUBDIRS'
 
   # These need to be absolute paths, yet at the same time need to
@@ -5821,6 +5821,34 @@ AC_LANG_SAVE
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check whether the dependencies for std::text_encoding are available.
+dnl
+dnl Defines:
+dnl   _GLIBCXX_USE_NL_LANGINFO_L if nl_langinfo_l is in <langinfo.h>.
+dnl
+AC_DEFUN([GLIBCXX_CHECK_TEXT_ENCODING], [
+AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  AC_MSG_CHECKING([whether nl_langinfo_l is defined in <langinfo.h>])
+  AC_TRY_COMPILE([
+  #include <locale.h>
+  #include <langinfo.h>
+  ],[
+    locale_t loc = newlocale(LC_ALL_MASK, "", (locale_t)0);
+    const char* enc = nl_langinfo_l(CODESET, loc);
+    freelocale(loc);
+  ], [ac_nl_langinfo_l=yes], [ac_nl_langinfo_l=no])
+  AC_MSG_RESULT($ac_nl_langinfo_l)
+  if test "$ac_nl_langinfo_l" = yes; then
+    AC_DEFINE_UNQUOTED(_GLIBCXX_USE_NL_LANGINFO_L, 1,
+      [Define if nl_langinfo_l should be used for std::text_encoding.])
+  fi
+
+  AC_LANG_RESTORE
+])
+
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
 m4_include([../config/tls.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index c8b36333019..c68cac4f345 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -557,6 +557,9 @@ GLIBCXX_CHECK_INIT_PRIORITY
 # For __basic_file::native_handle()
 GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
 
+# For std::text_encoding
+GLIBCXX_CHECK_TEXT_ENCODING
+
 # Define documentation rules conditionally.
 
 # See if makeinfo has been installed and is modern enough
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index c6d6a24eb9e..64152351ed0 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -104,6 +104,7 @@ std_headers = \
 	${std_srcdir}/streambuf \
 	${std_srcdir}/string \
 	${std_srcdir}/system_error \
+	${std_srcdir}/text_encoding \
 	${std_srcdir}/thread \
 	${std_srcdir}/unordered_map \
 	${std_srcdir}/unordered_set \
@@ -159,6 +160,7 @@ bits_freestanding = \
 	${bits_srcdir}/stl_raw_storage_iter.h \
 	${bits_srcdir}/stl_relops.h \
 	${bits_srcdir}/stl_uninitialized.h \
+	${bits_srcdir}/text_encoding-data.h \
 	${bits_srcdir}/version.h \
 	${bits_srcdir}/string_view.tcc \
 	${bits_srcdir}/unicode.h \
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 621f2a29f50..a2e94217006 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -40,6 +40,10 @@
 #include <string>
 #include <ext/atomicity.h>
 
+#ifdef __glibcxx_text_encoding
+#include <text_encoding>
+#endif
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -248,6 +252,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     string
     name() const;
 
+#ifdef __glibcxx_text_encoding
+# if __CHAR_BIT__ == 8
+    text_encoding
+    encoding() const;
+# else
+    text_encoding
+    encoding() const = delete;
+# endif
+#endif
+
     /**
      *  @brief  Locale equality.
      *
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
new file mode 100644
index 00000000000..7ac2e9dc3d9
--- /dev/null
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -0,0 +1,902 @@
+// Generated by gen_text_encoding_data.py, do not edit.
+
+#ifndef _GLIBCXX_GET_ENCODING_DATA
+# error "This is not a public header, do not include it directly"
+#endif
+
+  {    3, "US-ASCII" },
+  {    3, "iso-ir-6" },
+  {    3, "ANSI_X3.4-1968" },
+  {    3, "ANSI_X3.4-1986" },
+  {    3, "ISO_646.irv:1991" },
+  {    3, "ISO646-US" },
+  {    3, "us" },
+  {    3, "IBM367" },
+  {    3, "cp367" },
+  {    3, "csASCII" },
+  {    4, "ISO_8859-1:1987" },
+  {    4, "iso-ir-100" },
+  {    4, "ISO_8859-1" },
+  {    4, "ISO-8859-1" },
+  {    4, "latin1" },
+  {    4, "l1" },
+  {    4, "IBM819" },
+  {    4, "CP819" },
+  {    4, "csISOLatin1" },
+  {    5, "ISO_8859-2:1987" },
+  {    5, "iso-ir-101" },
+  {    5, "ISO_8859-2" },
+  {    5, "ISO-8859-2" },
+  {    5, "latin2" },
+  {    5, "l2" },
+  {    5, "csISOLatin2" },
+  {    6, "ISO_8859-3:1988" },
+  {    6, "iso-ir-109" },
+  {    6, "ISO_8859-3" },
+  {    6, "ISO-8859-3" },
+  {    6, "latin3" },
+  {    6, "l3" },
+  {    6, "csISOLatin3" },
+  {    7, "ISO_8859-4:1988" },
+  {    7, "iso-ir-110" },
+  {    7, "ISO_8859-4" },
+  {    7, "ISO-8859-4" },
+  {    7, "latin4" },
+  {    7, "l4" },
+  {    7, "csISOLatin4" },
+  {    8, "ISO_8859-5:1988" },
+  {    8, "iso-ir-144" },
+  {    8, "ISO_8859-5" },
+  {    8, "ISO-8859-5" },
+  {    8, "cyrillic" },
+  {    8, "csISOLatinCyrillic" },
+  {    9, "ISO_8859-6:1987" },
+  {    9, "iso-ir-127" },
+  {    9, "ISO_8859-6" },
+  {    9, "ISO-8859-6" },
+  {    9, "ECMA-114" },
+  {    9, "ASMO-708" },
+  {    9, "arabic" },
+  {    9, "csISOLatinArabic" },
+  {   10, "ISO_8859-7:1987" },
+  {   10, "iso-ir-126" },
+  {   10, "ISO_8859-7" },
+  {   10, "ISO-8859-7" },
+  {   10, "ELOT_928" },
+  {   10, "ECMA-118" },
+  {   10, "greek" },
+  {   10, "greek8" },
+  {   10, "csISOLatinGreek" },
+  {   11, "ISO_8859-8:1988" },
+  {   11, "iso-ir-138" },
+  {   11, "ISO_8859-8" },
+  {   11, "ISO-8859-8" },
+  {   11, "hebrew" },
+  {   11, "csISOLatinHebrew" },
+  {   12, "ISO_8859-9:1989" },
+  {   12, "iso-ir-148" },
+  {   12, "ISO_8859-9" },
+  {   12, "ISO-8859-9" },
+  {   12, "latin5" },
+  {   12, "l5" },
+  {   12, "csISOLatin5" },
+  {   13, "ISO-8859-10" },
+  {   13, "iso-ir-157" },
+  {   13, "l6" },
+  {   13, "ISO_8859-10:1992" },
+  {   13, "csISOLatin6" },
+  {   13, "latin6" },
+  {   14, "ISO_6937-2-add" },
+  {   14, "iso-ir-142" },
+  {   14, "csISOTextComm" },
+  {   15, "JIS_X0201" },
+  {   15, "X0201" },
+  {   15, "csHalfWidthKatakana" },
+  {   16, "JIS_Encoding" },
+  {   16, "csJISEncoding" },
+  {   17, "Shift_JIS" },
+  {   17, "MS_Kanji" },
+  {   17, "csShiftJIS" },
+  {   18, "Extended_UNIX_Code_Packed_Format_for_Japanese" },
+  {   18, "csEUCPkdFmtJapanese" },
+  {   18, "EUC-JP" },
+  {   19, "Extended_UNIX_Code_Fixed_Width_for_Japanese" },
+  {   19, "csEUCFixWidJapanese" },
+  {   20, "BS_4730" },
+  {   20, "iso-ir-4" },
+  {   20, "ISO646-GB" },
+  {   20, "gb" },
+  {   20, "uk" },
+  {   20, "csISO4UnitedKingdom" },
+  {   21, "SEN_850200_C" },
+  {   21, "iso-ir-11" },
+  {   21, "ISO646-SE2" },
+  {   21, "se2" },
+  {   21, "csISO11SwedishForNames" },
+  {   22, "IT" },
+  {   22, "iso-ir-15" },
+  {   22, "ISO646-IT" },
+  {   22, "csISO15Italian" },
+  {   23, "ES" },
+  {   23, "iso-ir-17" },
+  {   23, "ISO646-ES" },
+  {   23, "csISO17Spanish" },
+  {   24, "DIN_66003" },
+  {   24, "iso-ir-21" },
+  {   24, "de" },
+  {   24, "ISO646-DE" },
+  {   24, "csISO21German" },
+  {   25, "NS_4551-1" },
+  {   25, "iso-ir-60" },
+  {   25, "ISO646-NO" },
+  {   25, "no" },
+  {   25, "csISO60DanishNorwegian" },
+  {   25, "csISO60Norwegian1" },
+  {   26, "NF_Z_62-010" },
+  {   26, "iso-ir-69" },
+  {   26, "ISO646-FR" },
+  {   26, "fr" },
+  {   26, "csISO69French" },
+  {   27, "ISO-10646-UTF-1" },
+  {   27, "csISO10646UTF1" },
+  {   28, "ISO_646.basic:1983" },
+  {   28, "ref" },
+  {   28, "csISO646basic1983" },
+  {   29, "INVARIANT" },
+  {   29, "csINVARIANT" },
+  {   30, "ISO_646.irv:1983" },
+  {   30, "iso-ir-2" },
+  {   30, "irv" },
+  {   30, "csISO2IntlRefVersion" },
+  {   31, "NATS-SEFI" },
+  {   31, "iso-ir-8-1" },
+  {   31, "csNATSSEFI" },
+  {   32, "NATS-SEFI-ADD" },
+  {   32, "iso-ir-8-2" },
+  {   32, "csNATSSEFIADD" },
+  {   35, "SEN_850200_B" },
+  {   35, "iso-ir-10" },
+  {   35, "FI" },
+  {   35, "ISO646-FI" },
+  {   35, "ISO646-SE" },
+  {   35, "se" },
+  {   35, "csISO10Swedish" },
+  {   36, "KS_C_5601-1987" },
+  {   36, "iso-ir-149" },
+  {   36, "KS_C_5601-1989" },
+  {   36, "KSC_5601" },
+  {   36, "korean" },
+  {   36, "csKSC56011987" },
+  {   37, "ISO-2022-KR" },
+  {   37, "csISO2022KR" },
+  {   38, "EUC-KR" },
+  {   38, "csEUCKR" },
+  {   39, "ISO-2022-JP" },
+  {   39, "csISO2022JP" },
+  {   40, "ISO-2022-JP-2" },
+  {   40, "csISO2022JP2" },
+  {   41, "JIS_C6220-1969-jp" },
+  {   41, "JIS_C6220-1969" },
+  {   41, "iso-ir-13" },
+  {   41, "katakana" },
+  {   41, "x0201-7" },
+  {   41, "csISO13JISC6220jp" },
+  {   42, "JIS_C6220-1969-ro" },
+  {   42, "iso-ir-14" },
+  {   42, "jp" },
+  {   42, "ISO646-JP" },
+  {   42, "csISO14JISC6220ro" },
+  {   43, "PT" },
+  {   43, "iso-ir-16" },
+  {   43, "ISO646-PT" },
+  {   43, "csISO16Portuguese" },
+  {   44, "greek7-old" },
+  {   44, "iso-ir-18" },
+  {   44, "csISO18Greek7Old" },
+  {   45, "latin-greek" },
+  {   45, "iso-ir-19" },
+  {   45, "csISO19LatinGreek" },
+  {   46, "NF_Z_62-010_(1973)" },
+  {   46, "iso-ir-25" },
+  {   46, "ISO646-FR1" },
+  {   46, "csISO25French" },
+  {   47, "Latin-greek-1" },
+  {   47, "iso-ir-27" },
+  {   47, "csISO27LatinGreek1" },
+  {   48, "ISO_5427" },
+  {   48, "iso-ir-37" },
+  {   48, "csISO5427Cyrillic" },
+  {   49, "JIS_C6226-1978" },
+  {   49, "iso-ir-42" },
+  {   49, "csISO42JISC62261978" },
+  {   50, "BS_viewdata" },
+  {   50, "iso-ir-47" },
+  {   50, "csISO47BSViewdata" },
+  {   51, "INIS" },
+  {   51, "iso-ir-49" },
+  {   51, "csISO49INIS" },
+  {   52, "INIS-8" },
+  {   52, "iso-ir-50" },
+  {   52, "csISO50INIS8" },
+  {   53, "INIS-cyrillic" },
+  {   53, "iso-ir-51" },
+  {   53, "csISO51INISCyrillic" },
+  {   54, "ISO_5427:1981" },
+  {   54, "iso-ir-54" },
+  {   54, "ISO5427Cyrillic1981" },
+  {   54, "csISO54271981" },
+  {   55, "ISO_5428:1980" },
+  {   55, "iso-ir-55" },
+  {   55, "csISO5428Greek" },
+  {   56, "GB_1988-80" },
+  {   56, "iso-ir-57" },
+  {   56, "cn" },
+  {   56, "ISO646-CN" },
+  {   56, "csISO57GB1988" },
+  {   57, "GB_2312-80" },
+  {   57, "iso-ir-58" },
+  {   57, "chinese" },
+  {   57, "csISO58GB231280" },
+  {   58, "NS_4551-2" },
+  {   58, "ISO646-NO2" },
+  {   58, "iso-ir-61" },
+  {   58, "no2" },
+  {   58, "csISO61Norwegian2" },
+  {   59, "videotex-suppl" },
+  {   59, "iso-ir-70" },
+  {   59, "csISO70VideotexSupp1" },
+  {   60, "PT2" },
+  {   60, "iso-ir-84" },
+  {   60, "ISO646-PT2" },
+  {   60, "csISO84Portuguese2" },
+  {   61, "ES2" },
+  {   61, "iso-ir-85" },
+  {   61, "ISO646-ES2" },
+  {   61, "csISO85Spanish2" },
+  {   62, "MSZ_7795.3" },
+  {   62, "iso-ir-86" },
+  {   62, "ISO646-HU" },
+  {   62, "hu" },
+  {   62, "csISO86Hungarian" },
+  {   63, "JIS_C6226-1983" },
+  {   63, "iso-ir-87" },
+  {   63, "x0208" },
+  {   63, "JIS_X0208-1983" },
+  {   63, "csISO87JISX0208" },
+  {   64, "greek7" },
+  {   64, "iso-ir-88" },
+  {   64, "csISO88Greek7" },
+  {   65, "ASMO_449" },
+  {   65, "ISO_9036" },
+  {   65, "arabic7" },
+  {   65, "iso-ir-89" },
+  {   65, "csISO89ASMO449" },
+  {   66, "iso-ir-90" },
+  {   66, "csISO90" },
+  {   67, "JIS_C6229-1984-a" },
+  {   67, "iso-ir-91" },
+  {   67, "jp-ocr-a" },
+  {   67, "csISO91JISC62291984a" },
+  {   68, "JIS_C6229-1984-b" },
+  {   68, "iso-ir-92" },
+  {   68, "ISO646-JP-OCR-B" },
+  {   68, "jp-ocr-b" },
+  {   68, "csISO92JISC62991984b" },
+  {   69, "JIS_C6229-1984-b-add" },
+  {   69, "iso-ir-93" },
+  {   69, "jp-ocr-b-add" },
+  {   69, "csISO93JIS62291984badd" },
+  {   70, "JIS_C6229-1984-hand" },
+  {   70, "iso-ir-94" },
+  {   70, "jp-ocr-hand" },
+  {   70, "csISO94JIS62291984hand" },
+  {   71, "JIS_C6229-1984-hand-add" },
+  {   71, "iso-ir-95" },
+  {   71, "jp-ocr-hand-add" },
+  {   71, "csISO95JIS62291984handadd" },
+  {   72, "JIS_C6229-1984-kana" },
+  {   72, "iso-ir-96" },
+  {   72, "csISO96JISC62291984kana" },
+  {   73, "ISO_2033-1983" },
+  {   73, "iso-ir-98" },
+  {   73, "e13b" },
+  {   73, "csISO2033" },
+  {   74, "ANSI_X3.110-1983" },
+  {   74, "iso-ir-99" },
+  {   74, "CSA_T500-1983" },
+  {   74, "NAPLPS" },
+  {   74, "csISO99NAPLPS" },
+  {   75, "T.61-7bit" },
+  {   75, "iso-ir-102" },
+  {   75, "csISO102T617bit" },
+  {   76, "T.61-8bit" },
+  {   76, "T.61" },
+  {   76, "iso-ir-103" },
+  {   76, "csISO103T618bit" },
+  {   77, "ECMA-cyrillic" },
+  {   77, "iso-ir-111" },
+  {   77, "KOI8-E" },
+  {   77, "csISO111ECMACyrillic" },
+  {   78, "CSA_Z243.4-1985-1" },
+  {   78, "iso-ir-121" },
+  {   78, "ISO646-CA" },
+  {   78, "csa7-1" },
+  {   78, "csa71" },
+  {   78, "ca" },
+  {   78, "csISO121Canadian1" },
+  {   79, "CSA_Z243.4-1985-2" },
+  {   79, "iso-ir-122" },
+  {   79, "ISO646-CA2" },
+  {   79, "csa7-2" },
+  {   79, "csa72" },
+  {   79, "csISO122Canadian2" },
+  {   80, "CSA_Z243.4-1985-gr" },
+  {   80, "iso-ir-123" },
+  {   80, "csISO123CSAZ24341985gr" },
+  {   81, "ISO_8859-6-E" },
+  {   81, "csISO88596E" },
+  {   81, "ISO-8859-6-E" },
+  {   82, "ISO_8859-6-I" },
+  {   82, "csISO88596I" },
+  {   82, "ISO-8859-6-I" },
+  {   83, "T.101-G2" },
+  {   83, "iso-ir-128" },
+  {   83, "csISO128T101G2" },
+  {   84, "ISO_8859-8-E" },
+  {   84, "csISO88598E" },
+  {   84, "ISO-8859-8-E" },
+  {   85, "ISO_8859-8-I" },
+  {   85, "csISO88598I" },
+  {   85, "ISO-8859-8-I" },
+  {   86, "CSN_369103" },
+  {   86, "iso-ir-139" },
+  {   86, "csISO139CSN369103" },
+  {   87, "JUS_I.B1.002" },
+  {   87, "iso-ir-141" },
+  {   87, "ISO646-YU" },
+  {   87, "js" },
+  {   87, "yu" },
+  {   87, "csISO141JUSIB1002" },
+  {   88, "IEC_P27-1" },
+  {   88, "iso-ir-143" },
+  {   88, "csISO143IECP271" },
+  {   89, "JUS_I.B1.003-serb" },
+  {   89, "iso-ir-146" },
+  {   89, "serbian" },
+  {   89, "csISO146Serbian" },
+  {   90, "JUS_I.B1.003-mac" },
+  {   90, "macedonian" },
+  {   90, "iso-ir-147" },
+  {   90, "csISO147Macedonian" },
+  {   91, "greek-ccitt" },
+  {   91, "iso-ir-150" },
+  {   91, "csISO150" },
+  {   91, "csISO150GreekCCITT" },
+  {   92, "NC_NC00-10:81" },
+  {   92, "cuba" },
+  {   92, "iso-ir-151" },
+  {   92, "ISO646-CU" },
+  {   92, "csISO151Cuba" },
+  {   93, "ISO_6937-2-25" },
+  {   93, "iso-ir-152" },
+  {   93, "csISO6937Add" },
+  {   94, "GOST_19768-74" },
+  {   94, "ST_SEV_358-88" },
+  {   94, "iso-ir-153" },
+  {   94, "csISO153GOST1976874" },
+  {   95, "ISO_8859-supp" },
+  {   95, "iso-ir-154" },
+  {   95, "latin1-2-5" },
+  {   95, "csISO8859Supp" },
+  {   96, "ISO_10367-box" },
+  {   96, "iso-ir-155" },
+  {   96, "csISO10367Box" },
+  {   97, "latin-lap" },
+  {   97, "lap" },
+  {   97, "iso-ir-158" },
+  {   97, "csISO158Lap" },
+  {   98, "JIS_X0212-1990" },
+  {   98, "x0212" },
+  {   98, "iso-ir-159" },
+  {   98, "csISO159JISX02121990" },
+  {   99, "DS_2089" },
+  {   99, "DS2089" },
+  {   99, "ISO646-DK" },
+  {   99, "dk" },
+  {   99, "csISO646Danish" },
+  {  100, "us-dk" },
+  {  100, "csUSDK" },
+  {  101, "dk-us" },
+  {  101, "csDKUS" },
+  {  102, "KSC5636" },
+  {  102, "ISO646-KR" },
+  {  102, "csKSC5636" },
+  {  103, "UNICODE-1-1-UTF-7" },
+  {  103, "csUnicode11UTF7" },
+  {  104, "ISO-2022-CN" },
+  {  104, "csISO2022CN" },
+  {  105, "ISO-2022-CN-EXT" },
+  {  105, "csISO2022CNEXT" },
+#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
+  {  106, "UTF-8" },
+  {  106, "csUTF8" },
+  {  109, "ISO-8859-13" },
+  {  109, "csISO885913" },
+  {  110, "ISO-8859-14" },
+  {  110, "iso-ir-199" },
+  {  110, "ISO_8859-14:1998" },
+  {  110, "ISO_8859-14" },
+  {  110, "latin8" },
+  {  110, "iso-celtic" },
+  {  110, "l8" },
+  {  110, "csISO885914" },
+  {  111, "ISO-8859-15" },
+  {  111, "ISO_8859-15" },
+  {  111, "Latin-9" },
+  {  111, "csISO885915" },
+  {  112, "ISO-8859-16" },
+  {  112, "iso-ir-226" },
+  {  112, "ISO_8859-16:2001" },
+  {  112, "ISO_8859-16" },
+  {  112, "latin10" },
+  {  112, "l10" },
+  {  112, "csISO885916" },
+  {  113, "GBK" },
+  {  113, "CP936" },
+  {  113, "MS936" },
+  {  113, "windows-936" },
+  {  113, "csGBK" },
+  {  114, "GB18030" },
+  {  114, "csGB18030" },
+  {  115, "OSD_EBCDIC_DF04_15" },
+  {  115, "csOSDEBCDICDF0415" },
+  {  116, "OSD_EBCDIC_DF03_IRV" },
+  {  116, "csOSDEBCDICDF03IRV" },
+  {  117, "OSD_EBCDIC_DF04_1" },
+  {  117, "csOSDEBCDICDF041" },
+  {  118, "ISO-11548-1" },
+  {  118, "ISO_11548-1" },
+  {  118, "ISO_TR_11548-1" },
+  {  118, "csISO115481" },
+  {  119, "KZ-1048" },
+  {  119, "STRK1048-2002" },
+  {  119, "RK1048" },
+  {  119, "csKZ1048" },
+  { 1000, "ISO-10646-UCS-2" },
+  { 1000, "csUnicode" },
+  { 1001, "ISO-10646-UCS-4" },
+  { 1001, "csUCS4" },
+  { 1002, "ISO-10646-UCS-Basic" },
+  { 1002, "csUnicodeASCII" },
+  { 1003, "ISO-10646-Unicode-Latin1" },
+  { 1003, "csUnicodeLatin1" },
+  { 1003, "ISO-10646" },
+  { 1004, "ISO-10646-J-1" },
+  { 1004, "csUnicodeJapanese" },
+  { 1005, "ISO-Unicode-IBM-1261" },
+  { 1005, "csUnicodeIBM1261" },
+  { 1006, "ISO-Unicode-IBM-1268" },
+  { 1006, "csUnicodeIBM1268" },
+  { 1007, "ISO-Unicode-IBM-1276" },
+  { 1007, "csUnicodeIBM1276" },
+  { 1008, "ISO-Unicode-IBM-1264" },
+  { 1008, "csUnicodeIBM1264" },
+  { 1009, "ISO-Unicode-IBM-1265" },
+  { 1009, "csUnicodeIBM1265" },
+  { 1010, "UNICODE-1-1" },
+  { 1010, "csUnicode11" },
+  { 1011, "SCSU" },
+  { 1011, "csSCSU" },
+  { 1012, "UTF-7" },
+  { 1012, "csUTF7" },
+  { 1013, "UTF-16BE" },
+  { 1013, "csUTF16BE" },
+  { 1014, "UTF-16LE" },
+  { 1014, "csUTF16LE" },
+  { 1015, "UTF-16" },
+  { 1015, "csUTF16" },
+  { 1016, "CESU-8" },
+  { 1016, "csCESU8" },
+  { 1016, "csCESU-8" },
+  { 1017, "UTF-32" },
+  { 1017, "csUTF32" },
+  { 1018, "UTF-32BE" },
+  { 1018, "csUTF32BE" },
+  { 1019, "UTF-32LE" },
+  { 1019, "csUTF32LE" },
+  { 1020, "BOCU-1" },
+  { 1020, "csBOCU1" },
+  { 1020, "csBOCU-1" },
+  { 1021, "UTF-7-IMAP" },
+  { 1021, "csUTF7IMAP" },
+  { 2000, "ISO-8859-1-Windows-3.0-Latin-1" },
+  { 2000, "csWindows30Latin1" },
+  { 2001, "ISO-8859-1-Windows-3.1-Latin-1" },
+  { 2001, "csWindows31Latin1" },
+  { 2002, "ISO-8859-2-Windows-Latin-2" },
+  { 2002, "csWindows31Latin2" },
+  { 2003, "ISO-8859-9-Windows-Latin-5" },
+  { 2003, "csWindows31Latin5" },
+  { 2004, "hp-roman8" },
+  { 2004, "roman8" },
+  { 2004, "r8" },
+  { 2004, "csHPRoman8" },
+  { 2005, "Adobe-Standard-Encoding" },
+  { 2005, "csAdobeStandardEncoding" },
+  { 2006, "Ventura-US" },
+  { 2006, "csVenturaUS" },
+  { 2007, "Ventura-International" },
+  { 2007, "csVenturaInternational" },
+  { 2008, "DEC-MCS" },
+  { 2008, "dec" },
+  { 2008, "csDECMCS" },
+  { 2009, "IBM850" },
+  { 2009, "cp850" },
+  { 2009, "850" },
+  { 2009, "csPC850Multilingual" },
+  { 2010, "IBM852" },
+  { 2010, "cp852" },
+  { 2010, "852" },
+  { 2010, "csPCp852" },
+  { 2011, "IBM437" },
+  { 2011, "cp437" },
+  { 2011, "437" },
+  { 2011, "csPC8CodePage437" },
+  { 2012, "PC8-Danish-Norwegian" },
+  { 2012, "csPC8DanishNorwegian" },
+  { 2013, "IBM862" },
+  { 2013, "cp862" },
+  { 2013, "862" },
+  { 2013, "csPC862LatinHebrew" },
+  { 2014, "PC8-Turkish" },
+  { 2014, "csPC8Turkish" },
+  { 2015, "IBM-Symbols" },
+  { 2015, "csIBMSymbols" },
+  { 2016, "IBM-Thai" },
+  { 2016, "csIBMThai" },
+  { 2017, "HP-Legal" },
+  { 2017, "csHPLegal" },
+  { 2018, "HP-Pi-font" },
+  { 2018, "csHPPiFont" },
+  { 2019, "HP-Math8" },
+  { 2019, "csHPMath8" },
+  { 2020, "Adobe-Symbol-Encoding" },
+  { 2020, "csHPPSMath" },
+  { 2021, "HP-DeskTop" },
+  { 2021, "csHPDesktop" },
+  { 2022, "Ventura-Math" },
+  { 2022, "csVenturaMath" },
+  { 2023, "Microsoft-Publishing" },
+  { 2023, "csMicrosoftPublishing" },
+  { 2024, "Windows-31J" },
+  { 2024, "csWindows31J" },
+  { 2025, "GB2312" },
+  { 2025, "csGB2312" },
+  { 2026, "Big5" },
+  { 2026, "csBig5" },
+  { 2027, "macintosh" },
+  { 2027, "mac" },
+  { 2027, "csMacintosh" },
+  { 2028, "IBM037" },
+  { 2028, "cp037" },
+  { 2028, "ebcdic-cp-us" },
+  { 2028, "ebcdic-cp-ca" },
+  { 2028, "ebcdic-cp-wt" },
+  { 2028, "ebcdic-cp-nl" },
+  { 2028, "csIBM037" },
+  { 2029, "IBM038" },
+  { 2029, "EBCDIC-INT" },
+  { 2029, "cp038" },
+  { 2029, "csIBM038" },
+  { 2030, "IBM273" },
+  { 2030, "CP273" },
+  { 2030, "csIBM273" },
+  { 2031, "IBM274" },
+  { 2031, "EBCDIC-BE" },
+  { 2031, "CP274" },
+  { 2031, "csIBM274" },
+  { 2032, "IBM275" },
+  { 2032, "EBCDIC-BR" },
+  { 2032, "cp275" },
+  { 2032, "csIBM275" },
+  { 2033, "IBM277" },
+  { 2033, "EBCDIC-CP-DK" },
+  { 2033, "EBCDIC-CP-NO" },
+  { 2033, "csIBM277" },
+  { 2034, "IBM278" },
+  { 2034, "CP278" },
+  { 2034, "ebcdic-cp-fi" },
+  { 2034, "ebcdic-cp-se" },
+  { 2034, "csIBM278" },
+  { 2035, "IBM280" },
+  { 2035, "CP280" },
+  { 2035, "ebcdic-cp-it" },
+  { 2035, "csIBM280" },
+  { 2036, "IBM281" },
+  { 2036, "EBCDIC-JP-E" },
+  { 2036, "cp281" },
+  { 2036, "csIBM281" },
+  { 2037, "IBM284" },
+  { 2037, "CP284" },
+  { 2037, "ebcdic-cp-es" },
+  { 2037, "csIBM284" },
+  { 2038, "IBM285" },
+  { 2038, "CP285" },
+  { 2038, "ebcdic-cp-gb" },
+  { 2038, "csIBM285" },
+  { 2039, "IBM290" },
+  { 2039, "cp290" },
+  { 2039, "EBCDIC-JP-kana" },
+  { 2039, "csIBM290" },
+  { 2040, "IBM297" },
+  { 2040, "cp297" },
+  { 2040, "ebcdic-cp-fr" },
+  { 2040, "csIBM297" },
+  { 2041, "IBM420" },
+  { 2041, "cp420" },
+  { 2041, "ebcdic-cp-ar1" },
+  { 2041, "csIBM420" },
+  { 2042, "IBM423" },
+  { 2042, "cp423" },
+  { 2042, "ebcdic-cp-gr" },
+  { 2042, "csIBM423" },
+  { 2043, "IBM424" },
+  { 2043, "cp424" },
+  { 2043, "ebcdic-cp-he" },
+  { 2043, "csIBM424" },
+  { 2044, "IBM500" },
+  { 2044, "CP500" },
+  { 2044, "ebcdic-cp-be" },
+  { 2044, "ebcdic-cp-ch" },
+  { 2044, "csIBM500" },
+  { 2045, "IBM851" },
+  { 2045, "cp851" },
+  { 2045, "851" },
+  { 2045, "csIBM851" },
+  { 2046, "IBM855" },
+  { 2046, "cp855" },
+  { 2046, "855" },
+  { 2046, "csIBM855" },
+  { 2047, "IBM857" },
+  { 2047, "cp857" },
+  { 2047, "857" },
+  { 2047, "csIBM857" },
+  { 2048, "IBM860" },
+  { 2048, "cp860" },
+  { 2048, "860" },
+  { 2048, "csIBM860" },
+  { 2049, "IBM861" },
+  { 2049, "cp861" },
+  { 2049, "861" },
+  { 2049, "cp-is" },
+  { 2049, "csIBM861" },
+  { 2050, "IBM863" },
+  { 2050, "cp863" },
+  { 2050, "863" },
+  { 2050, "csIBM863" },
+  { 2051, "IBM864" },
+  { 2051, "cp864" },
+  { 2051, "csIBM864" },
+  { 2052, "IBM865" },
+  { 2052, "cp865" },
+  { 2052, "865" },
+  { 2052, "csIBM865" },
+  { 2053, "IBM868" },
+  { 2053, "CP868" },
+  { 2053, "cp-ar" },
+  { 2053, "csIBM868" },
+  { 2054, "IBM869" },
+  { 2054, "cp869" },
+  { 2054, "869" },
+  { 2054, "cp-gr" },
+  { 2054, "csIBM869" },
+  { 2055, "IBM870" },
+  { 2055, "CP870" },
+  { 2055, "ebcdic-cp-roece" },
+  { 2055, "ebcdic-cp-yu" },
+  { 2055, "csIBM870" },
+  { 2056, "IBM871" },
+  { 2056, "CP871" },
+  { 2056, "ebcdic-cp-is" },
+  { 2056, "csIBM871" },
+  { 2057, "IBM880" },
+  { 2057, "cp880" },
+  { 2057, "EBCDIC-Cyrillic" },
+  { 2057, "csIBM880" },
+  { 2058, "IBM891" },
+  { 2058, "cp891" },
+  { 2058, "csIBM891" },
+  { 2059, "IBM903" },
+  { 2059, "cp903" },
+  { 2059, "csIBM903" },
+  { 2060, "IBM904" },
+  { 2060, "cp904" },
+  { 2060, "904" },
+  { 2060, "csIBBM904" },
+  { 2061, "IBM905" },
+  { 2061, "CP905" },
+  { 2061, "ebcdic-cp-tr" },
+  { 2061, "csIBM905" },
+  { 2062, "IBM918" },
+  { 2062, "CP918" },
+  { 2062, "ebcdic-cp-ar2" },
+  { 2062, "csIBM918" },
+  { 2063, "IBM1026" },
+  { 2063, "CP1026" },
+  { 2063, "csIBM1026" },
+  { 2064, "EBCDIC-AT-DE" },
+  { 2064, "csIBMEBCDICATDE" },
+  { 2065, "EBCDIC-AT-DE-A" },
+  { 2065, "csEBCDICATDEA" },
+  { 2066, "EBCDIC-CA-FR" },
+  { 2066, "csEBCDICCAFR" },
+  { 2067, "EBCDIC-DK-NO" },
+  { 2067, "csEBCDICDKNO" },
+  { 2068, "EBCDIC-DK-NO-A" },
+  { 2068, "csEBCDICDKNOA" },
+  { 2069, "EBCDIC-FI-SE" },
+  { 2069, "csEBCDICFISE" },
+  { 2070, "EBCDIC-FI-SE-A" },
+  { 2070, "csEBCDICFISEA" },
+  { 2071, "EBCDIC-FR" },
+  { 2071, "csEBCDICFR" },
+  { 2072, "EBCDIC-IT" },
+  { 2072, "csEBCDICIT" },
+  { 2073, "EBCDIC-PT" },
+  { 2073, "csEBCDICPT" },
+  { 2074, "EBCDIC-ES" },
+  { 2074, "csEBCDICES" },
+  { 2075, "EBCDIC-ES-A" },
+  { 2075, "csEBCDICESA" },
+  { 2076, "EBCDIC-ES-S" },
+  { 2076, "csEBCDICESS" },
+  { 2077, "EBCDIC-UK" },
+  { 2077, "csEBCDICUK" },
+  { 2078, "EBCDIC-US" },
+  { 2078, "csEBCDICUS" },
+  { 2079, "UNKNOWN-8BIT" },
+  { 2079, "csUnknown8BiT" },
+  { 2080, "MNEMONIC" },
+  { 2080, "csMnemonic" },
+  { 2081, "MNEM" },
+  { 2081, "csMnem" },
+  { 2082, "VISCII" },
+  { 2082, "csVISCII" },
+  { 2083, "VIQR" },
+  { 2083, "csVIQR" },
+  { 2084, "KOI8-R" },
+  { 2084, "csKOI8R" },
+  { 2085, "HZ-GB-2312" },
+  { 2086, "IBM866" },
+  { 2086, "cp866" },
+  { 2086, "866" },
+  { 2086, "csIBM866" },
+  { 2087, "IBM775" },
+  { 2087, "cp775" },
+  { 2087, "csPC775Baltic" },
+  { 2088, "KOI8-U" },
+  { 2088, "csKOI8U" },
+  { 2089, "IBM00858" },
+  { 2089, "CCSID00858" },
+  { 2089, "CP00858" },
+  { 2089, "PC-Multilingual-850+euro" },
+  { 2089, "csIBM00858" },
+  { 2090, "IBM00924" },
+  { 2090, "CCSID00924" },
+  { 2090, "CP00924" },
+  { 2090, "ebcdic-Latin9--euro" },
+  { 2090, "csIBM00924" },
+  { 2091, "IBM01140" },
+  { 2091, "CCSID01140" },
+  { 2091, "CP01140" },
+  { 2091, "ebcdic-us-37+euro" },
+  { 2091, "csIBM01140" },
+  { 2092, "IBM01141" },
+  { 2092, "CCSID01141" },
+  { 2092, "CP01141" },
+  { 2092, "ebcdic-de-273+euro" },
+  { 2092, "csIBM01141" },
+  { 2093, "IBM01142" },
+  { 2093, "CCSID01142" },
+  { 2093, "CP01142" },
+  { 2093, "ebcdic-dk-277+euro" },
+  { 2093, "ebcdic-no-277+euro" },
+  { 2093, "csIBM01142" },
+  { 2094, "IBM01143" },
+  { 2094, "CCSID01143" },
+  { 2094, "CP01143" },
+  { 2094, "ebcdic-fi-278+euro" },
+  { 2094, "ebcdic-se-278+euro" },
+  { 2094, "csIBM01143" },
+  { 2095, "IBM01144" },
+  { 2095, "CCSID01144" },
+  { 2095, "CP01144" },
+  { 2095, "ebcdic-it-280+euro" },
+  { 2095, "csIBM01144" },
+  { 2096, "IBM01145" },
+  { 2096, "CCSID01145" },
+  { 2096, "CP01145" },
+  { 2096, "ebcdic-es-284+euro" },
+  { 2096, "csIBM01145" },
+  { 2097, "IBM01146" },
+  { 2097, "CCSID01146" },
+  { 2097, "CP01146" },
+  { 2097, "ebcdic-gb-285+euro" },
+  { 2097, "csIBM01146" },
+  { 2098, "IBM01147" },
+  { 2098, "CCSID01147" },
+  { 2098, "CP01147" },
+  { 2098, "ebcdic-fr-297+euro" },
+  { 2098, "csIBM01147" },
+  { 2099, "IBM01148" },
+  { 2099, "CCSID01148" },
+  { 2099, "CP01148" },
+  { 2099, "ebcdic-international-500+euro" },
+  { 2099, "csIBM01148" },
+  { 2100, "IBM01149" },
+  { 2100, "CCSID01149" },
+  { 2100, "CP01149" },
+  { 2100, "ebcdic-is-871+euro" },
+  { 2100, "csIBM01149" },
+  { 2101, "Big5-HKSCS" },
+  { 2101, "csBig5HKSCS" },
+  { 2102, "IBM1047" },
+  { 2102, "IBM-1047" },
+  { 2102, "csIBM1047" },
+  { 2103, "PTCP154" },
+  { 2103, "csPTCP154" },
+  { 2103, "PT154" },
+  { 2103, "CP154" },
+  { 2103, "Cyrillic-Asian" },
+  { 2104, "Amiga-1251" },
+  { 2104, "Ami1251" },
+  { 2104, "Amiga1251" },
+  { 2104, "Ami-1251" },
+  { 2104, "csAmiga1251" },
+  { 2104, "(Aliases" },
+  { 2104, "are" },
+  { 2104, "provided" },
+  { 2104, "for" },
+  { 2104, "historical" },
+  { 2104, "reasons" },
+  { 2104, "and" },
+  { 2104, "should" },
+  { 2104, "not" },
+  { 2104, "be" },
+  { 2104, "used)" },
+  { 2104, "[Malyshev]" },
+  { 2105, "KOI7-switched" },
+  { 2105, "csKOI7switched" },
+  { 2106, "BRF" },
+  { 2106, "csBRF" },
+  { 2107, "TSCII" },
+  { 2107, "csTSCII" },
+  { 2108, "CP51932" },
+  { 2108, "csCP51932" },
+  { 2109, "windows-874" },
+  { 2109, "cswindows874" },
+  { 2250, "windows-1250" },
+  { 2250, "cswindows1250" },
+  { 2251, "windows-1251" },
+  { 2251, "cswindows1251" },
+  { 2252, "windows-1252" },
+  { 2252, "cswindows1252" },
+  { 2253, "windows-1253" },
+  { 2253, "cswindows1253" },
+  { 2254, "windows-1254" },
+  { 2254, "cswindows1254" },
+  { 2255, "windows-1255" },
+  { 2255, "cswindows1255" },
+  { 2256, "windows-1256" },
+  { 2256, "cswindows1256" },
+  { 2257, "windows-1257" },
+  { 2257, "cswindows1257" },
+  { 2258, "windows-1258" },
+  { 2258, "cswindows1258" },
+  { 2259, "TIS-620" },
+  { 2259, "csTIS620" },
+  { 2259, "ISO-8859-11" },
+  { 2260, "CP50220" },
+  { 2260, "csCP50220" },
+
+#undef _GLIBCXX_GET_ENCODING_DATA
diff --git a/libstdc++-v3/include/bits/unicode.h b/libstdc++-v3/include/bits/unicode.h
index d35c83d0090..d025d21f3dd 100644
--- a/libstdc++-v3/include/bits/unicode.h
+++ b/libstdc++-v3/include/bits/unicode.h
@@ -32,7 +32,8 @@
 
 #if __cplusplus >= 202002L
 #include <array>
-#include <bit>
+#include <bit>      // bit_width
+#include <charconv> // __detail::__from_chars_alnum_to_val_table
 #include <cstdint>
 #include <bits/stl_algo.h>
 #include <bits/stl_iterator.h>
@@ -986,7 +987,7 @@ inline namespace __v15_1_0
       return __n;
     }
 
-    template<typename _CharT>
+  template<typename _CharT>
     consteval bool
     __literal_encoding_is_unicode()
     {
@@ -1056,6 +1057,53 @@ inline namespace __v15_1_0
   __literal_encoding_is_utf8()
   { return __literal_encoding_is_unicode<char>(); }
 
+  consteval bool
+  __literal_encoding_is_extended_ascii()
+  {
+    return '0' == 0x30 && 'A' == 0x41 && 'Z' == 0x5a
+	     && 'a' == 0x61 && 'z' == 0x7a;
+  }
+
+  // https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching
+  constexpr bool
+  __charset_alias_match(string_view __a, string_view __b)
+  {
+    // Map alphanumeric chars to their base 64 value, everything else to 127.
+    auto __map = [](char __c, bool& __num) -> unsigned char {
+      if (__c == '0') [[unlikely]]
+	return __num ? 0 : 127;
+      const auto __v = __detail::__from_chars_alnum_to_val(__c);
+      __num = __v < 10;
+      return __v;
+    };
+
+    auto __ptr_a = __a.begin(), __end_a = __a.end();
+    auto __ptr_b = __b.begin(), __end_b = __b.end();
+    bool __num_a = false, __num_b = false;
+
+    while (true)
+      {
+	// Find the value of the next alphanumeric character in each string.
+	unsigned char __val_a, __val_b;
+	while (__ptr_a != __end_a
+		 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
+	  ++__ptr_a;
+	while (__ptr_b != __end_b
+		 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
+	  ++__ptr_b;
+	// Stop when we reach the end of a string, or get a mismatch.
+	if (__ptr_a == __end_a)
+	  return __ptr_b == __end_b;
+	else if (__ptr_b == __end_b)
+	  return false;
+	else if (__val_a != __val_b)
+	  return false; // Found non-matching characters.
+	++__ptr_a;
+	++__ptr_b;
+      }
+    return true;
+  }
+
 } // namespace __unicode
 
 namespace ranges
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index afbec6c3e6a..8fb8a2877ee 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1751,6 +1751,16 @@ ftms = {
   };
 };
 
+ftms = {
+  name = text_encoding;
+  values = {
+    v = 202306;
+    cxxmin = 26;
+    hosted = yes;
+    extra_cond = "_GLIBCXX_USE_NL_LANGINFO_L";
+  };
+};
+
 ftms = {
   name = to_string;
   values = {
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 9688b246ef4..9ba99deeda6 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2137,6 +2137,17 @@
 #undef __glibcxx_want_saturation_arithmetic
 
 // from version.def line 1755
+#if !defined(__cpp_lib_text_encoding)
+# if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (_GLIBCXX_USE_NL_LANGINFO_L)
+#  define __glibcxx_text_encoding 202306L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_text_encoding)
+#   define __cpp_lib_text_encoding 202306L
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_text_encoding) && defined(__glibcxx_want_text_encoding) */
+#undef __glibcxx_want_text_encoding
+
+// from version.def line 1765
 #if !defined(__cpp_lib_to_string)
 # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
 #  define __glibcxx_to_string 202306L
@@ -2147,7 +2158,7 @@
 #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
 #undef __glibcxx_want_to_string
 
-// from version.def line 1765
+// from version.def line 1775
 #if !defined(__cpp_lib_generator)
 # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
 #  define __glibcxx_generator 202207L
diff --git a/libstdc++-v3/include/std/text_encoding b/libstdc++-v3/include/std/text_encoding
new file mode 100644
index 00000000000..83d023bc71b
--- /dev/null
+++ b/libstdc++-v3/include/std/text_encoding
@@ -0,0 +1,678 @@
+// <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file include/text_encoding
+ *  This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TEXT_ENCODING
+#define _GLIBCXX_TEXT_ENCODING
+
+#pragma GCC system_header
+
+#include <bits/requires_hosted.h>
+
+#define __glibcxx_want_text_encoding
+#include <bits/version.h>
+
+#ifdef __cpp_lib_text_encoding
+#include <compare>
+#include <string_view>
+#include <bits/functional_hash.h> // hash
+#include <bits/ranges_util.h>     // view_interface
+#include <bits/unicode.h>         // __charset_alias_match
+#include <ext/numeric_traits.h>   // __int_traits
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  /**
+   * @brief An interface for accessing the IANA Character Sets registry.
+   * @ingroup locales
+   * @since C++23
+   */
+  struct text_encoding
+  {
+  private:
+    struct _Rep
+    {
+      using id = __INT_LEAST32_TYPE__;
+      id _M_id;
+      const char* _M_name;
+
+      friend constexpr bool
+      operator<(const _Rep& __r, id __m) noexcept
+      { return __r._M_id < __m; }
+
+      friend constexpr bool
+      operator==(const _Rep& __r, string_view __name) noexcept
+      { return __r._M_name == __name; }
+    };
+
+  public:
+    static constexpr size_t max_name_length = 63;
+
+    enum class id : _Rep::id
+    {
+      other = 1,
+      unknown = 2,
+      ASCII = 3,
+      ISOLatin1 = 4,
+      ISOLatin2 = 5,
+      ISOLatin3 = 6,
+      ISOLatin4 = 7,
+      ISOLatinCyrillic = 8,
+      ISOLatinArabic = 9,
+      ISOLatinGreek = 10,
+      ISOLatinHebrew = 11,
+      ISOLatin5 = 12,
+      ISOLatin6 = 13,
+      ISOTextComm = 14,
+      HalfWidthKatakana = 15,
+      JISEncoding = 16,
+      ShiftJIS = 17,
+      EUCPkdFmtJapanese = 18,
+      EUCFixWidJapanese = 19,
+      ISO4UnitedKingdom = 20,
+      ISO11SwedishForNames = 21,
+      ISO15Italian = 22,
+      ISO17Spanish = 23,
+      ISO21German = 24,
+      ISO60DanishNorwegian = 25,
+      ISO69French = 26,
+      ISO10646UTF1 = 27,
+      ISO646basic1983 = 28,
+      INVARIANT = 29,
+      ISO2IntlRefVersion = 30,
+      NATSSEFI = 31,
+      NATSSEFIADD = 32,
+      ISO10Swedish = 35,
+      KSC56011987 = 36,
+      ISO2022KR = 37,
+      EUCKR = 38,
+      ISO2022JP = 39,
+      ISO2022JP2 = 40,
+      ISO13JISC6220jp = 41,
+      ISO14JISC6220ro = 42,
+      ISO16Portuguese = 43,
+      ISO18Greek7Old = 44,
+      ISO19LatinGreek = 45,
+      ISO25French = 46,
+      ISO27LatinGreek1 = 47,
+      ISO5427Cyrillic = 48,
+      ISO42JISC62261978 = 49,
+      ISO47BSViewdata = 50,
+      ISO49INIS = 51,
+      ISO50INIS8 = 52,
+      ISO51INISCyrillic = 53,
+      ISO54271981 = 54,
+      ISO5428Greek = 55,
+      ISO57GB1988 = 56,
+      ISO58GB231280 = 57,
+      ISO61Norwegian2 = 58,
+      ISO70VideotexSupp1 = 59,
+      ISO84Portuguese2 = 60,
+      ISO85Spanish2 = 61,
+      ISO86Hungarian = 62,
+      ISO87JISX0208 = 63,
+      ISO88Greek7 = 64,
+      ISO89ASMO449 = 65,
+      ISO90 = 66,
+      ISO91JISC62291984a = 67,
+      ISO92JISC62991984b = 68,
+      ISO93JIS62291984badd = 69,
+      ISO94JIS62291984hand = 70,
+      ISO95JIS62291984handadd = 71,
+      ISO96JISC62291984kana = 72,
+      ISO2033 = 73,
+      ISO99NAPLPS = 74,
+      ISO102T617bit = 75,
+      ISO103T618bit = 76,
+      ISO111ECMACyrillic = 77,
+      ISO121Canadian1 = 78,
+      ISO122Canadian2 = 79,
+      ISO123CSAZ24341985gr = 80,
+      ISO88596E = 81,
+      ISO88596I = 82,
+      ISO128T101G2 = 83,
+      ISO88598E = 84,
+      ISO88598I = 85,
+      ISO139CSN369103 = 86,
+      ISO141JUSIB1002 = 87,
+      ISO143IECP271 = 88,
+      ISO146Serbian = 89,
+      ISO147Macedonian = 90,
+      ISO150 = 91,
+      ISO151Cuba = 92,
+      ISO6937Add = 93,
+      ISO153GOST1976874 = 94,
+      ISO8859Supp = 95,
+      ISO10367Box = 96,
+      ISO158Lap = 97,
+      ISO159JISX02121990 = 98,
+      ISO646Danish = 99,
+      USDK = 100,
+      DKUS = 101,
+      KSC5636 = 102,
+      Unicode11UTF7 = 103,
+      ISO2022CN = 104,
+      ISO2022CNEXT = 105,
+      UTF8 = 106,
+      ISO885913 = 109,
+      ISO885914 = 110,
+      ISO885915 = 111,
+      ISO885916 = 112,
+      GBK = 113,
+      GB18030 = 114,
+      OSDEBCDICDF0415 = 115,
+      OSDEBCDICDF03IRV = 116,
+      OSDEBCDICDF041 = 117,
+      ISO115481 = 118,
+      KZ1048 = 119,
+      UCS2 = 1000,
+      UCS4 = 1001,
+      UnicodeASCII = 1002,
+      UnicodeLatin1 = 1003,
+      UnicodeJapanese = 1004,
+      UnicodeIBM1261 = 1005,
+      UnicodeIBM1268 = 1006,
+      UnicodeIBM1276 = 1007,
+      UnicodeIBM1264 = 1008,
+      UnicodeIBM1265 = 1009,
+      Unicode11 = 1010,
+      SCSU = 1011,
+      UTF7 = 1012,
+      UTF16BE = 1013,
+      UTF16LE = 1014,
+      UTF16 = 1015,
+      CESU8 = 1016,
+      UTF32 = 1017,
+      UTF32BE = 1018,
+      UTF32LE = 1019,
+      BOCU1 = 1020,
+      UTF7IMAP = 1021,
+      Windows30Latin1 = 2000,
+      Windows31Latin1 = 2001,
+      Windows31Latin2 = 2002,
+      Windows31Latin5 = 2003,
+      HPRoman8 = 2004,
+      AdobeStandardEncoding = 2005,
+      VenturaUS = 2006,
+      VenturaInternational = 2007,
+      DECMCS = 2008,
+      PC850Multilingual = 2009,
+      PC8DanishNorwegian = 2012,
+      PC862LatinHebrew = 2013,
+      PC8Turkish = 2014,
+      IBMSymbols = 2015,
+      IBMThai = 2016,
+      HPLegal = 2017,
+      HPPiFont = 2018,
+      HPMath8 = 2019,
+      HPPSMath = 2020,
+      HPDesktop = 2021,
+      VenturaMath = 2022,
+      MicrosoftPublishing = 2023,
+      Windows31J = 2024,
+      GB2312 = 2025,
+      Big5 = 2026,
+      Macintosh = 2027,
+      IBM037 = 2028,
+      IBM038 = 2029,
+      IBM273 = 2030,
+      IBM274 = 2031,
+      IBM275 = 2032,
+      IBM277 = 2033,
+      IBM278 = 2034,
+      IBM280 = 2035,
+      IBM281 = 2036,
+      IBM284 = 2037,
+      IBM285 = 2038,
+      IBM290 = 2039,
+      IBM297 = 2040,
+      IBM420 = 2041,
+      IBM423 = 2042,
+      IBM424 = 2043,
+      PC8CodePage437 = 2011,
+      IBM500 = 2044,
+      IBM851 = 2045,
+      PCp852 = 2010,
+      IBM855 = 2046,
+      IBM857 = 2047,
+      IBM860 = 2048,
+      IBM861 = 2049,
+      IBM863 = 2050,
+      IBM864 = 2051,
+      IBM865 = 2052,
+      IBM868 = 2053,
+      IBM869 = 2054,
+      IBM870 = 2055,
+      IBM871 = 2056,
+      IBM880 = 2057,
+      IBM891 = 2058,
+      IBM903 = 2059,
+      IBM904 = 2060,
+      IBM905 = 2061,
+      IBM918 = 2062,
+      IBM1026 = 2063,
+      IBMEBCDICATDE = 2064,
+      EBCDICATDEA = 2065,
+      EBCDICCAFR = 2066,
+      EBCDICDKNO = 2067,
+      EBCDICDKNOA = 2068,
+      EBCDICFISE = 2069,
+      EBCDICFISEA = 2070,
+      EBCDICFR = 2071,
+      EBCDICIT = 2072,
+      EBCDICPT = 2073,
+      EBCDICES = 2074,
+      EBCDICESA = 2075,
+      EBCDICESS = 2076,
+      EBCDICUK = 2077,
+      EBCDICUS = 2078,
+      Unknown8BiT = 2079,
+      Mnemonic = 2080,
+      Mnem = 2081,
+      VISCII = 2082,
+      VIQR = 2083,
+      KOI8R = 2084,
+      HZGB2312 = 2085,
+      IBM866 = 2086,
+      PC775Baltic = 2087,
+      KOI8U = 2088,
+      IBM00858 = 2089,
+      IBM00924 = 2090,
+      IBM01140 = 2091,
+      IBM01141 = 2092,
+      IBM01142 = 2093,
+      IBM01143 = 2094,
+      IBM01144 = 2095,
+      IBM01145 = 2096,
+      IBM01146 = 2097,
+      IBM01147 = 2098,
+      IBM01148 = 2099,
+      IBM01149 = 2100,
+      Big5HKSCS = 2101,
+      IBM1047 = 2102,
+      PTCP154 = 2103,
+      Amiga1251 = 2104,
+      KOI7switched = 2105,
+      BRF = 2106,
+      TSCII = 2107,
+      CP51932 = 2108,
+      windows874 = 2109,
+      windows1250 = 2250,
+      windows1251 = 2251,
+      windows1252 = 2252,
+      windows1253 = 2253,
+      windows1254 = 2254,
+      windows1255 = 2255,
+      windows1256 = 2256,
+      windows1257 = 2257,
+      windows1258 = 2258,
+      TIS620 = 2259,
+      CP50220 = 2260
+    };
+    using enum id;
+
+    constexpr text_encoding() = default;
+
+    constexpr explicit
+    text_encoding(string_view __enc) noexcept
+    : _M_rep(_S_find_name(__enc))
+    {
+      __enc.copy(_M_name, max_name_length);
+    }
+
+    // @pre i has the value of one of the enumerators of id.
+    constexpr
+    text_encoding(id __i) noexcept
+    : _M_rep(_S_find_id(__i))
+    {
+      if (string_view __name(_M_rep->_M_name); !__name.empty())
+	__name.copy(_M_name, max_name_length);
+    }
+
+    constexpr id mib() const noexcept { return id(_M_rep->_M_id); }
+
+    constexpr const char* name() const noexcept { return _M_name; }
+
+    struct aliases_view : ranges::view_interface<aliases_view>
+    {
+    private:
+      class _Iterator;
+      struct _Sentinel { };
+
+    public:
+      constexpr _Iterator begin() const noexcept;
+      constexpr _Sentinel end() const noexcept { return {}; }
+
+    private:
+      friend struct text_encoding;
+
+      constexpr explicit aliases_view(const _Rep* __r) : _M_begin(__r) { }
+
+      const _Rep* _M_begin = nullptr;
+    };
+
+    constexpr aliases_view
+    aliases() const noexcept
+    {
+      return _M_rep->_M_name[0] ? aliases_view(_M_rep) : aliases_view{nullptr};
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __a,
+	       const text_encoding& __b) noexcept
+    {
+      if (__a.mib() == id::other && __b.mib() == id::other) [[unlikely]]
+	return _S_comp(__a._M_name, __b._M_name);
+      else
+	return __a.mib() == __b.mib();
+    }
+
+    friend constexpr bool
+    operator==(const text_encoding& __encoding, id __i) noexcept
+    { return __encoding.mib() == __i; }
+
+#if __CHAR_BIT__ == 8
+    static consteval text_encoding
+    literal() noexcept
+    {
+#ifdef __GNUC_EXECUTION_CHARSET_NAME
+      return text_encoding(__GNUC_EXECUTION_CHARSET_NAME);
+#elif defined __clang_literal_encoding__
+      return text_encoding(__clang_literal_encoding__);
+#else
+      return text_encoding();
+#endif
+    }
+
+    static text_encoding
+    environment();
+
+    template<id _Id>
+      static bool
+      environment_is()
+      { return text_encoding(_Id)._M_is_environment(); }
+#else
+    static text_encoding literal() = delete;
+    static text_encoding environment() = delete;
+    template<id> static bool environment_is() = delete;
+#endif
+
+  private:
+    const _Rep* _M_rep = _S_reps + 1; // id::unknown
+    char _M_name[max_name_length + 1] = {0};
+
+    bool
+    _M_is_environment() const;
+
+    static inline constexpr _Rep _S_reps[] = {
+      { 1, "" }, { 2, "" },
+#define _GLIBCXX_GET_ENCODING_DATA
+#include <bits/text_encoding-data.h>
+#ifdef _GLIBCXX_GET_ENCODING_DATA
+# error "Invalid text_encoding data"
+#endif
+      { 9999, nullptr }, // sentinel
+    };
+
+    static constexpr bool
+    _S_comp(string_view __a, string_view __b)
+    { return __unicode::__charset_alias_match(__a, __b); }
+
+    static constexpr const _Rep*
+    _S_find_name(string_view __name) noexcept
+    {
+#ifdef _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET
+      // Optimize the common UTF-8 case to avoid a linear search through all
+      // strings in the table using the _S_comp function.
+      if (__name == "UTF-8")
+	return _S_reps + 2 + _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET;
+#endif
+
+      // The first two array elements (other and unknown) don't have names.
+      // The last element is a sentinel that can never match anything.
+      const auto __first = _S_reps + 2, __end = std::end(_S_reps) - 1;
+      for (auto __r = __first; __r != __end; ++__r)
+	if (_S_comp(__r->_M_name, __name))
+	  {
+	    // Might have matched an alias. Find the first entry for this ID.
+	    const auto __id = __r->_M_id;
+	    while (__r[-1]._M_id == __id)
+	      --__r;
+	    return __r;
+	  }
+      return _S_reps; // id::other
+    }
+
+    static constexpr const _Rep*
+    _S_find_id(id __id) noexcept
+    {
+      const auto __i = (_Rep::id)__id;
+      const auto __r = std::lower_bound(_S_reps, std::end(_S_reps) - 1, __i);
+      if (__r->_M_id == __i) [[likely]]
+	return __r;
+      else
+	{
+	  // Preconditions: i has the value of one of the enumerators of id.
+	  __glibcxx_assert(__r->_M_id == __i);
+	  return _S_reps + 1; // id::unknown
+	}
+    }
+  };
+
+  template<>
+    struct hash<text_encoding>
+    {
+      size_t
+      operator()(const text_encoding& __enc) const noexcept
+      { return std::hash<text_encoding::id>()(__enc.mib()); }
+    };
+
+  class text_encoding::aliases_view::_Iterator
+  {
+  public:
+    using value_type = const char*;
+    using reference = const char*;
+    using difference_type = int;
+
+    constexpr _Iterator() = default;
+
+    constexpr value_type
+    operator*() const
+    {
+      if (_M_dereferenceable()) [[likely]]
+	return _M_rep->_M_name;
+      else
+	{
+	  __glibcxx_assert(_M_dereferenceable());
+	  return "";
+	}
+    }
+
+    constexpr _Iterator&
+    operator++()
+    {
+      if (_M_dereferenceable()) [[likely]]
+      ++_M_rep;
+      else
+	{
+	  __glibcxx_assert(_M_dereferenceable());
+	  *this = _Iterator{};
+	}
+      return *this;
+    }
+
+    constexpr _Iterator&
+    operator--()
+    {
+      const bool __decrementable
+	= _M_rep != nullptr && _M_rep[-1]._M_id == _M_id;
+      if (__decrementable) [[likely]]
+      --_M_rep;
+      else
+	{
+	  __glibcxx_assert(__decrementable);
+	  *this = _Iterator{};
+	}
+      return *this;
+    }
+
+    constexpr _Iterator
+    operator++(int)
+    {
+      auto __it = *this;
+      ++*this;
+      return __it;
+    }
+
+    constexpr _Iterator
+    operator--(int)
+    {
+      auto __it = *this;
+      --*this;
+      return __it;
+    }
+
+    constexpr value_type
+    operator[](difference_type __n) const
+    { return *(*this + __n); }
+
+    constexpr _Iterator&
+    operator+=(difference_type __n)
+    {
+      if (_M_rep != nullptr)
+	{
+	  if (__n > 0)
+	    {
+	      if (__n < (std::end(_S_reps) - _M_rep)
+			  && _M_rep[__n - 1]._M_id == _M_id) [[likely]]
+		 _M_rep += __n;
+	      else
+		*this == _Iterator{};
+	    }
+	  else if (__n < 0)
+	    {
+	      if (__n > (_S_reps - _M_rep)
+		    && _M_rep[__n]._M_id == _M_id) [[likely]]
+		 _M_rep += __n;
+	      else
+		*this == _Iterator{};
+	    }
+	}
+      if (__n != 0)
+	__glibcxx_assert(_M_rep != nullptr);
+      return *this;
+    }
+
+    constexpr _Iterator&
+    operator-=(difference_type __n)
+    {
+      using _Traits = __gnu_cxx::__int_traits<difference_type>;
+      if (__n == _Traits::__min) [[unlikely]]
+	return operator+=(_Traits::__max);
+      return operator+=(-__n);
+    }
+
+    constexpr difference_type
+    operator-(const _Iterator& __i) const
+    {
+      if (_M_id == __i._M_id)
+	return _M_rep - __i._M_rep;
+      __glibcxx_assert(_M_id == __i._M_id);
+      return __gnu_cxx::__int_traits<difference_type>::__max;
+    }
+
+    constexpr bool
+    operator==(const _Iterator&) const = default;
+
+    constexpr bool
+    operator==(_Sentinel) const noexcept
+    { return !_M_dereferenceable(); }
+
+    constexpr strong_ordering
+    operator<=>(const _Iterator& __i) const
+    {
+      __glibcxx_assert(_M_id == __i._M_id);
+      return _M_rep <=> __i._M_rep;
+    }
+
+    friend constexpr _Iterator
+    operator+(_Iterator __i, difference_type __n)
+    {
+      __i += __n;
+      return __i;
+    }
+
+    friend constexpr _Iterator
+    operator+(difference_type __n, _Iterator __i)
+    {
+      __i += __n;
+      return __i;
+    }
+
+    friend constexpr _Iterator
+    operator-(_Iterator __i, difference_type __n)
+    {
+      __i -= __n;
+      return __i;
+    }
+
+  private:
+    friend class text_encoding;
+
+    constexpr explicit
+    _Iterator(const _Rep* __r) noexcept
+    : _M_rep(__r), _M_id(__r ? __r->_M_id : 0)
+    { }
+
+    constexpr bool
+    _M_dereferenceable() const noexcept
+    { return _M_rep != nullptr && _M_rep->_M_id == _M_id; }
+
+    const _Rep* _M_rep = nullptr;
+    _Rep::id _M_id = 0;
+  };
+
+  constexpr auto
+  text_encoding::aliases_view::begin() const noexcept
+  -> _Iterator
+  { return _Iterator(_M_begin); }
+
+namespace ranges
+{
+  // Opt-in to borrowed_range concept
+  template<>
+    inline constexpr bool
+    enable_borrowed_range<std::text_encoding::aliases_view> = true;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cpp_lib_text_encoding
+#endif // _GLIBCXX_TEXT_ENCODING
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 032a7aa58a2..a6c2ed4599f 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2324,6 +2324,21 @@ class StdIntegralConstantPrinter(printer_base):
         typename = strip_versioned_namespace(self._typename)
         return "{}<{}, {}>".format(typename, value_type, value)
 
+class StdTextEncodingPrinter(printer_base):
+    """Print a std::text_encoding."""
+
+    def __init__(self, typename, val):
+        self._val = val
+        self._typename = typename
+
+    def to_string(self):
+        rep = self._val['_M_rep'].dereference()
+        if rep['_M_id'] == 1:
+            return self._val['_M_name']
+        if rep['_M_id'] == 2:
+            return 'unknown'
+        return rep['_M_name']
+
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
 class RxPrinter(object):
@@ -2807,6 +2822,8 @@ def build_libstdcxx_dictionary():
 
     libstdcxx_printer.add_version('std::', 'integral_constant',
                                   StdIntegralConstantPrinter)
+    libstdcxx_printer.add_version('std::', 'text_encoding',
+                                  StdTextEncodingPrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
new file mode 100755
index 00000000000..2d6f3e4077a
--- /dev/null
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+#
+# Script to generate tables for libstdc++ std::text_encoding.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 3, or (at your option) any later
+# version.
+#
+# GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# To update the Libstdc++ static data in <bits/text_encoding-data.h> download
+# the latest:
+# https://www.iana.org/assignments/character-sets/character-sets-1.csv
+# Then run this script and save the output to
+# include/bits/text_encoding-data.h
+
+import sys
+import csv
+
+if len(sys.argv) != 2:
+    print("Usage: %s <character sets csv>" % sys.argv[0], file=sys.stderr)
+    sys.exit(1)
+
+print("// Generated by gen_text_encoding_data.py, do not edit.\n")
+print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
+print('# error "This is not a public header, do not include it directly"')
+print("#endif\n")
+
+
+charsets = {}
+with open(sys.argv[1], newline='') as f:
+    reader = csv.reader(f)
+    next(reader) # skip header row
+    for row in reader:
+        mib = int(row[2])
+        if mib in charsets:
+            raise ValueError("Multiple rows for mibEnum={}".format(mib))
+        name = row[1]
+        aliases = row[5].split()
+        # Ensure primary name comes first
+        if name in aliases:
+            aliases.remove(name)
+        charsets[mib] = [name] + aliases
+
+# Remove "NATS-DANO" and "NATS-DANO-ADD"
+charsets.pop(33, None)
+charsets.pop(34, None)
+
+count = 0
+for mib in sorted(charsets.keys()):
+    names = charsets[mib]
+    if names[0] == "UTF-8":
+        print("#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET {}".format(count))
+    for name in names:
+        print('  {{ {:4}, "{}" }},'.format(mib, name))
+    count += len(names)
+
+# <text_encoding> gives an error if this macro is left defined.
+# Do this last, so that the generated output is not usable unless we reach here.
+print("\n#undef _GLIBCXX_GET_ENCODING_DATA")
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 7292ae70f81..37ba1491dea 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -43,7 +43,7 @@ experimental_dir =
 endif
 
 ## Keep this list sync'd with acinclude.m4:GLIBCXX_CONFIGURE.
-SUBDIRS = c++98 c++11 c++17 c++20 c++23 \
+SUBDIRS = c++98 c++11 c++17 c++20 c++23 c++26 \
 	$(filesystem_dir) $(backtrace_dir) $(experimental_dir)
 
 # Cross compiler support.
@@ -77,6 +77,7 @@ vpath % $(top_srcdir)/src/c++11
 vpath % $(top_srcdir)/src/c++17
 vpath % $(top_srcdir)/src/c++20
 vpath % $(top_srcdir)/src/c++23
+vpath % $(top_srcdir)/src/c++26
 if ENABLE_FILESYSTEM_TS
 vpath % $(top_srcdir)/src/filesystem
 endif
diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am
new file mode 100644
index 00000000000..000ced1f501
--- /dev/null
+++ b/libstdc++-v3/src/c++26/Makefile.am
@@ -0,0 +1,109 @@
+## Makefile for the C++26 sources of the GNU C++ Standard library.
+##
+## Copyright (C) 1997-2023 Free Software Foundation, Inc.
+##
+## This file is part of the libstdc++ version 3 distribution.
+## Process this file with automake to produce Makefile.in.
+
+## This file is part of the GNU ISO C++ Library.  This library is free
+## software; you can redistribute it and/or modify it under the
+## terms of the GNU General Public License as published by the
+## Free Software Foundation; either version 3, or (at your option)
+## any later version.
+
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+## You should have received a copy of the GNU General Public License along
+## with this library; see the file COPYING3.  If not see
+## <http://www.gnu.org/licenses/>.
+
+include $(top_srcdir)/fragment.am
+
+# Convenience library for C++26 runtime.
+noinst_LTLIBRARIES = libc++26convenience.la
+
+headers =
+
+if ENABLE_EXTERN_TEMPLATE
+# XTEMPLATE_FLAGS = -fno-implicit-templates
+inst_sources =
+else
+# XTEMPLATE_FLAGS =
+inst_sources =
+endif
+
+sources = text_encoding.cc
+
+vpath % $(top_srcdir)/src/c++26
+
+
+if GLIBCXX_HOSTED
+libc__26convenience_la_SOURCES = $(sources)  $(inst_sources)
+else
+libc__26convenience_la_SOURCES =
+endif
+
+# AM_CXXFLAGS needs to be in each subdirectory so that it can be
+# modified in a per-library or per-sub-library way.  Need to manually
+# set this option because CONFIG_CXXFLAGS has to be after
+# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
+# as the occasion calls for it.
+AM_CXXFLAGS = \
+	-std=gnu++26 \
+	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
+	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
+	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
+	-fimplicit-templates
+
+AM_MAKEFLAGS = \
+	"gxx_include_dir=$(gxx_include_dir)"
+
+# Libtool notes
+
+# 1) In general, libtool expects an argument such as `--tag=CXX' when
+# using the C++ compiler, because that will enable the settings
+# detected when C++ support was being configured.  However, when no
+# such flag is given in the command line, libtool attempts to figure
+# it out by matching the compiler name in each configuration section
+# against a prefix of the command line.  The problem is that, if the
+# compiler name and its initial flags stored in the libtool
+# configuration file don't match those in the command line, libtool
+# can't decide which configuration to use, and it gives up.  The
+# correct solution is to add `--tag CXX' to LTCXXCOMPILE and maybe
+# CXXLINK, just after $(LIBTOOL), so that libtool doesn't have to
+# attempt to infer which configuration to use.
+#
+# The second tag argument, `--tag disable-shared` means that libtool
+# only compiles each source once, for static objects. In actuality,
+# glibcxx_lt_pic_flag and glibcxx_compiler_shared_flag are added to
+# the libtool command that is used create the object, which is
+# suitable for shared libraries.  The `--tag disable-shared` must be
+# placed after --tag CXX lest things CXX undo the affect of
+# disable-shared.
+
+# 2) Need to explicitly set LTCXXCOMPILE so that EXTRA_CXX_FLAGS is
+# last. (That way, things like -O2 passed down from the toplevel can
+# be overridden by --enable-debug.)
+LTCXXCOMPILE = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=compile $(CXX) $(TOPLEVEL_INCLUDES) \
+	$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CXXFLAGS) $(CXXFLAGS) $(EXTRA_CXX_FLAGS)
+
+LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
+
+# 3) We'd have a problem when building the shared libstdc++ object if
+# the rules automake generates would be used.  We cannot allow g++ to
+# be used since this would add -lstdc++ to the link line which of
+# course is problematic at this point.  So, we get the top-level
+# directory to configure libstdc++-v3 to use gcc as the C++
+# compilation driver.
+CXXLINK = \
+	$(LIBTOOL) --tag CXX --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=link $(CXX) \
+	$(VTV_CXXLINKFLAGS) \
+	$(OPT_LDFLAGS) $(SECTION_LDFLAGS) $(AM_CXXFLAGS) $(LTLDFLAGS) -o $@
diff --git a/libstdc++-v3/src/c++26/Makefile.in b/libstdc++-v3/src/c++26/Makefile.in
new file mode 100644
index 00000000000..77e73b2b265
diff --git a/libstdc++-v3/src/c++26/text_encoding.cc b/libstdc++-v3/src/c++26/text_encoding.cc
new file mode 100644
index 00000000000..33c6c07820c
--- /dev/null
+++ b/libstdc++-v3/src/c++26/text_encoding.cc
@@ -0,0 +1,91 @@
+// Definitions for <text_encoding> -*- C++ -*-
+
+// Copyright The GNU Toolchain Authors.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <text_encoding>
+#include <locale>
+
+#ifdef _GLIBCXX_USE_NL_LANGINFO_L
+#include <locale.h>
+#include <langinfo.h>
+
+#if __CHAR_BIT__ == 8
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+text_encoding
+__locale_encoding(const char* name)
+{
+  text_encoding enc;
+  if (locale_t loc = ::newlocale(LC_CTYPE_MASK, name, (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view s(codeset);
+	  if (s.size() < text_encoding::max_name_length)
+	    enc = text_encoding(s);
+	}
+      ::freelocale(loc);
+    }
+  return enc;
+}
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+std::text_encoding
+std::text_encoding::environment()
+{
+  return std::__locale_encoding("");
+}
+
+bool
+std::text_encoding::_M_is_environment() const
+{
+  bool matched = false;
+  if (locale_t loc = ::newlocale(LC_CTYPE_MASK, "", (locale_t)0))
+    {
+      if (const char* codeset = ::nl_langinfo_l(CODESET, loc))
+	{
+	  string_view sv(codeset);
+	  for (auto alias : aliases())
+	    if (__unicode::__charset_alias_match(alias, sv))
+	      {
+		matched = true;
+		break;
+	      }
+	}
+      ::freelocale(loc);
+    }
+  return matched;
+}
+
+std::text_encoding
+std::locale::encoding() const
+{
+  return std::__locale_encoding(name().c_str());
+}
+#endif // CHAR_BIT == 8
+
+#endif // _GLIBCXX_USE_NL_LANGINFO_L
diff --git a/libstdc++-v3/src/experimental/Makefile.am b/libstdc++-v3/src/experimental/Makefile.am
index 8259f986d95..6241430988e 100644
--- a/libstdc++-v3/src/experimental/Makefile.am
+++ b/libstdc++-v3/src/experimental/Makefile.am
@@ -47,10 +47,12 @@ libstdc__exp_la_SOURCES = $(sources)
 
 libstdc__exp_la_LIBADD = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 libstdc__exp_la_DEPENDENCIES = \
 	$(top_builddir)/src/c++23/libc++23convenience.la \
+	$(top_builddir)/src/c++26/libc++26convenience.la \
 	$(filesystem_lib) $(backtrace_lib)
 
 # AM_CXXFLAGS needs to be in each subdirectory so that it can be
diff --git a/libstdc++-v3/testsuite/22_locale/locale/encoding.cc b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
new file mode 100644
index 00000000000..18825fb88b9
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/locale/encoding.cc
@@ -0,0 +1,36 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <locale>
+#include <testsuite_hooks.h>
+
+void
+test_encoding()
+{
+  const std::locale c = std::locale::classic();
+  std::text_encoding c_enc = c.encoding();
+  VERIFY( c_enc == std::text_encoding::ASCII );
+
+  const std::locale fr = std::locale(ISO_8859(15, fr_FR));
+  std::text_encoding fr_enc = fr.encoding();
+  VERIFY( fr_enc == std::text_encoding::ISO885915 );
+
+  const std::locale en = std::locale(ISO_8859(1, en_US));
+  std::text_encoding en_enc = en.encoding();
+  VERIFY( en_enc == std::text_encoding::ISOLatin1 );
+
+#if __cpp_exceptions
+  try {
+    const std::locale c_utf8 = std::locale("C.UTF-8");
+    VERIFY( c_utf8.encoding() == std::text_encoding::UTF8 );
+  } catch (...) {
+  }
+#endif
+}
+
+int main()
+{
+  test_encoding();
+}
diff --git a/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
new file mode 100644
index 00000000000..f6272ae998b
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/unicode/charset_alias_match.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+#include <format>
+
+using std::__unicode::__charset_alias_match;
+static_assert( __charset_alias_match("UTF-8", "utf8") == true );
+static_assert( __charset_alias_match("UTF-8", "u.t.f-008") == true );
+static_assert( __charset_alias_match("UTF-8", "utf-80") == false );
+static_assert( __charset_alias_match("UTF-8", "ut8") == false );
+
+static_assert( __charset_alias_match("iso8859_1", "ISO-8859-1") == true );
+
+static_assert( __charset_alias_match("", "") == true );
+static_assert( __charset_alias_match("", ".") == true );
+static_assert( __charset_alias_match("--", "...") == true );
+static_assert( __charset_alias_match("--a", "a...") == true );
+static_assert( __charset_alias_match("--a010", "a..10.") == true );
+static_assert( __charset_alias_match("--a010", "a..1.0") == false );
+static_assert( __charset_alias_match("aaaa", "000.00.0a0a)0aa...") == true );
diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
new file mode 100644
index 00000000000..b9d93641de4
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
@@ -0,0 +1,113 @@
+// { dg-do run { target c++26 } }
+
+#include <text_encoding>
+#include <string_view>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+constexpr void
+test_default_construct()
+{
+  std::text_encoding e0;
+  VERIFY( e0.mib() == std::text_encoding::unknown );
+  VERIFY( e0.name()[0] == '\0' ); // P2862R1 name() should never return null
+  VERIFY( e0.aliases().empty() );
+}
+
+constexpr void
+test_construct_by_name()
+{
+  std::string_view s;
+  std::text_encoding e0(s);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == s );
+  VERIFY( e0.aliases().empty() );
+
+  s = "not a real encoding";
+  std::text_encoding e1(s);
+  VERIFY( e1.mib() == std::text_encoding::other );
+  VERIFY( e1.name() == s );
+  VERIFY( e1.aliases().empty() );
+
+  VERIFY( e1 != e0 );
+  VERIFY( e1 == e0.mib() );
+
+  s = "utf8";
+  std::text_encoding e2(s);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == s );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == "UTF-8"sv );
+
+  s = "Latin-1"; // matches "latin1"
+  std::text_encoding e3(s);
+  VERIFY( e3.mib() == std::text_encoding::ISOLatin1 );
+  VERIFY( e3.name() == s );
+  VERIFY( ! e3.aliases().empty() );
+  VERIFY( e3.aliases().front() == "ISO_8859-1:1987"sv ); // primary name
+
+  s = "U.S."; // matches "us"
+  std::text_encoding e4(s);
+  VERIFY( e4.mib() == std::text_encoding::ASCII );
+  VERIFY( e4.name() == s );
+  VERIFY( ! e4.aliases().empty() );
+  VERIFY( e4.aliases().front() == "US-ASCII"sv ); // primary name
+}
+
+constexpr void
+test_construct_by_id()
+{
+  std::text_encoding e0(std::text_encoding::other);
+  VERIFY( e0.mib() == std::text_encoding::other );
+  VERIFY( e0.name() == ""sv );
+  VERIFY( e0.aliases().empty() );
+
+  std::text_encoding e1(std::text_encoding::unknown);
+  VERIFY( e1.mib() == std::text_encoding::unknown );
+  VERIFY( e1.name() == ""sv );
+  VERIFY( e1.aliases().empty() );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  VERIFY( e2.mib() == std::text_encoding::UTF8 );
+  VERIFY( e2.name() == "UTF-8"sv );
+  VERIFY( ! e2.aliases().empty() );
+  VERIFY( e2.aliases().front() == std::string_view(e2.name()) );
+  bool found = false;
+  for (auto alias : e2.aliases())
+    if (alias == "csUTF8"sv)
+    {
+      found = true;
+      break;
+    }
+  VERIFY( found );
+}
+
+constexpr void
+test_copy_construct()
+{
+  std::text_encoding e0;
+  std::text_encoding e1 = e0;
+  VERIFY( e1 == e0 );
+
+  std::text_encoding e2(std::text_encoding::UTF8);
+  auto e3 = e2;
+  VERIFY( e3 == e2 );
+
+  e1 = e3;
+  VERIFY( e1 == e2 );
+}
+
+int main()
+{
+  auto run_tests = [] {
+    test_default_construct();
+    test_construct_by_name();
+    test_construct_by_id();
+    test_copy_construct();
+    return true;
+  };
+
+  run_tests();
+  static_assert( run_tests() );
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/members.cc b/libstdc++-v3/testsuite/std/text_encoding/members.cc
new file mode 100644
index 00000000000..adbd74ab85e
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/members.cc
@@ -0,0 +1,86 @@
+// { dg-options "-lstdc++exp" }
+// { dg-do run { target c++26 } }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+
+#include <text_encoding>
+#include <string_view>
+#include <locale.h>
+#include <testsuite_hooks.h>
+
+using namespace std::string_view_literals;
+
+void
+test_literal()
+{
+  const std::text_encoding lit = std::text_encoding::literal();
+  VERIFY( lit.name() == std::string_view(__GNUC_EXECUTION_CHARSET_NAME) );
+}
+
+void
+test_env()
+{
+  const std::text_encoding env = std::text_encoding::environment();
+
+  if (env.mib() == std::text_encoding::UTF8)
+    VERIFY( std::text_encoding::environment_is<std::text_encoding::UTF8>() );
+
+  ::setlocale(LC_ALL, ISO_8859(1, en_US));
+  const std::text_encoding env1 = std::text_encoding::environment();
+  VERIFY( env1 == env );
+
+  ::setlocale(LC_ALL, ISO_8859(15, fr_FR));
+  const std::text_encoding env2 = std::text_encoding::environment();
+  VERIFY( env2 == env );
+}
+
+void
+test_every_id()
+{
+  for (int i = 0; i <= 2260; ++i)
+  {
+    std::text_encoding::id mib{i};
+    switch (i)
+    {
+    case 0:
+    case 33 ... 34:
+    case 107 ... 108:
+    case 120 ... 999:
+    case 1022 ... 1999:
+    case 2110 ... 2249:
+      // These do not correspond to an enumerator of std::text_encoding::id
+      // so are not valid arguments to the constructor. Without assertions
+      // enabled, we map bad IDs to id::unknown as a libstdc++ extension.
+#ifndef _GLIBCXX_ASSERTIONS
+      {
+        std::text_encoding bad{mib};
+        VERIFY( bad.mib() == std::text_encoding::unknown );
+        VERIFY( bad.name() == ""sv );
+      }
+#endif
+      continue;
+    }
+    std::text_encoding enc{mib};
+    auto aliases = enc.aliases();
+    if (i == 1 || i == 2)
+      VERIFY( enc.name() == ""sv );
+    else
+      VERIFY( enc.name() == std::string_view(aliases.front()) );
+    auto begin = aliases.begin();
+    auto end = aliases.end();
+    VERIFY( (begin + std::ranges::distance(aliases)) == end );
+#ifndef _GLIBCXX_ASSERTIONS
+    // This is an error, but with assertions disabled is guaranteed safe:
+    VERIFY( begin[std::ranges::distance(aliases)] == ""sv );
+    // Likewise:
+    VERIFY( begin[999999] == *begin );
+#endif
+  }
+}
+
+int main()
+{
+  test_literal();
+  test_env();
+  test_every_id();
+}
diff --git a/libstdc++-v3/testsuite/std/text_encoding/requirements.cc b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
new file mode 100644
index 00000000000..a1d5d6baee1
--- /dev/null
+++ b/libstdc++-v3/testsuite/std/text_encoding/requirements.cc
@@ -0,0 +1,77 @@
+// { dg-do compile { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <text_encoding>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <text_encoding>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <text_encoding>"
+#endif
+
+#undef __cpp_lib_expected
+#include <version>
+#ifndef __cpp_lib_text_encoding
+# error "Feature-test macro for text_encoding missing in <version>"
+#elif __cpp_lib_text_encoding != 202306L
+# error "Feature-test macro for text_encoding has wrong value in <version>"
+#endif
+
+#include <concepts>
+#include <ranges>
+static_assert( std::is_trivially_copyable_v<std::text_encoding> );
+
+using aliases_view = std::text_encoding::aliases_view;
+static_assert( std::copyable<aliases_view> );
+static_assert( std::ranges::view<aliases_view> );
+static_assert( std::ranges::random_access_range<aliases_view> );
+static_assert( std::ranges::borrowed_range<aliases_view> );
+static_assert( std::same_as<std::ranges::range_value_t<aliases_view>,
+			    const char*> );
+static_assert( std::same_as<std::ranges::range_reference_t<aliases_view>,
+			    const char*> );
+
+#include <testsuite_hooks.h>
+
+constexpr bool
+test_constexpr_iterator()
+{
+  // This encoding has two aliases, "UTF-8" and "csUTF8".
+  const auto a = std::text_encoding(std::text_encoding::UTF8).aliases();
+  const auto begin = a.begin();
+  const auto end = a.end();
+  auto iter = begin;
+  VERIFY( *iter == *begin );
+  VERIFY( *iter == iter[0] );
+  VERIFY( iter[1] == begin[1] );
+  --++iter;
+  VERIFY( iter == begin );
+  auto iter2 = iter++;
+  VERIFY( iter2 == begin );
+  VERIFY( iter != begin );
+  iter2 = iter--;
+  VERIFY( iter2 != begin );
+  VERIFY( iter == begin );
+  iter++++; // Increments prvalue returned by operator++(int) instead of iter.
+  VERIFY( iter == iter2 );
+  iter----; // Decrements prvalue returned by operator++(int) instead of iter.
+  VERIFY( iter == begin );
+  const auto d = std::ranges::distance(a);
+  iter += d;
+  VERIFY( iter == end );
+  VERIFY( (iter - begin) == d );
+  VERIFY( (begin + 2) == iter );
+  VERIFY( (2 + begin) == iter );
+  VERIFY( iter[-1] == begin[1] );
+  iter -= d;
+  VERIFY( iter == begin );
+  VERIFY( *(iter + 1) == iter[1] );
+  VERIFY( (1 + iter - 1) == begin );
+  VERIFY( (-1 + (iter - -2) + -1) == begin );
+
+  std::ranges::iterator_t<std::text_encoding::aliases_view> singular{};
+  VERIFY( (singular + 0) == singular );
+  VERIFY( (singular - 0) == singular );
+
+  return true;
+}
+static_assert( test_constexpr_iterator() );

^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2024-01-17 12:15 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-01-12 22:29 [WIP] libstdc++: Implement C++26 std::text_encoding [PR113318] Jonathan Wakely
2024-01-13 12:44 ` [PATCH v2] " Jonathan Wakely
2024-01-15 20:45   ` [PATCH v3] libstdc++: Implement C++26 std::text_encoding (P1885R12) [PR113318] Jonathan Wakely
2024-01-15 22:24     ` Ulrich Drepper
2024-01-16  0:09     ` Patrick Palka
2024-01-16 14:06       ` [PATCH v4] " Jonathan Wakely
2024-01-16 15:39         ` Jonathan Wakely
2024-01-16 16:17           ` Jonathan Wakely
2024-01-17 12:14             ` [committed v5] " Jonathan Wakely

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