[gcc r13-8048] libstdc++: Add pretty printer for std::locale

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:a3dfc6fc487c593f6a336e940e06ede57fb10e36

commit r13-8048-ga3dfc6fc487c593f6a336e940e06ede57fb10e36
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Aug 23 12:10:16 2023 +0100

    libstdc++: Add pretty printer for std::locale
    
    Print the locale's name, except when it uses the same named C locale for
    all categories except one, in which case print something like:
    std::locale = "en_GB.UTF-8" with "LC_CTYPE=en_US.UTF-8"
    
    libstdc++-v3/ChangeLog:
    
            * python/libstdcxx/v6/printers.py (StdLocalePrinter): New
            printer class.
            * testsuite/libstdc++-prettyprinters/locale.cc: New test.
    
    (cherry picked from commit 3d2e240af7704b7c4fc15fb3c8b282556841108d)

Diff:
---
 libstdc++-v3/python/libstdcxx/v6/printers.py       | 45 ++++++++++++++++++++++
 .../testsuite/libstdc++-prettyprinters/locale.cc   | 36 +++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 1a8017adb22..37a447b514b 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2131,6 +2131,50 @@ class StdChronoTimeZoneRulePrinter:
         return 'time_zone rule {} from {} to {} starting on {}'.format(
                 self.val['name'], self.val['from'], self.val['to'], start)
 
+class StdLocalePrinter:
+    "Print a std::locale"
+
+    def __init__(self, typename, val):
+        self.val = val
+        self.typename = typename
+
+    def to_string(self):
+        names = self.val['_M_impl']['_M_names']
+        mod = ''
+        if names[0] == 0:
+            name = '*'
+        else:
+            cats = gdb.parse_and_eval(self.typename + '::_S_categories')
+            ncat = gdb.parse_and_eval(self.typename + '::_S_categories_size')
+            n = names[0].string();
+            cat = cats[0].string()
+            name = '{}={}'.format(cat, n)
+            cat_names = {cat: n}
+            i = 1
+            while i < ncat and names[i] != 0:
+                n = names[i].string()
+                cat = cats[i].string()
+                name = '{};{}={}'.format(name, cat, n)
+                cat_names[cat] = n
+                i = i + 1
+            uniq_names = set(cat_names.values())
+            if len(uniq_names) == 1:
+                name = n
+            elif len(uniq_names) == 2:
+                n1, n2 = (uniq_names)
+                name_list = list(cat_names.values())
+                other = None
+                if name_list.count(n1) == 1:
+                    name = n2
+                    other = n1
+                elif name_list.count(n2) == 1:
+                    name = n1
+                    other = n2
+                if other is not None:
+                    cat = next(c for c,n in cat_names.items() if n == other)
+                    mod = ' with "{}={}"'.format(cat, other)
+        return 'std::locale = "{}"{}'.format(name, mod)
+
 
 # A "regular expression" printer which conforms to the
 # "SubPrettyPrinter" protocol from gdb.printing.
@@ -2585,6 +2629,7 @@ def build_libstdcxx_dictionary ():
     libstdcxx_printer.add_version('std::', 'unique_ptr', UniquePointerPrinter)
     libstdcxx_printer.add_container('std::', 'vector', StdVectorPrinter)
     # vector<bool>
+    libstdcxx_printer.add_version('std::', 'locale', StdLocalePrinter)
 
     if hasattr(gdb.Value, 'dynamic_type'):
         libstdcxx_printer.add_version('std::', 'error_code',
diff --git a/libstdc++-v3/testsuite/libstdc++-prettyprinters/locale.cc b/libstdc++-v3/testsuite/libstdc++-prettyprinters/locale.cc
new file mode 100644
index 00000000000..66d42f99432
--- /dev/null
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/locale.cc
@@ -0,0 +1,36 @@
+// { dg-do run }
+// { dg-options "-g -O0" }
+// { dg-require-namedlocale "fr_FR.ISO8859-15" }
+// { dg-require-namedlocale "de_DE.ISO8859-15" }
+// { dg-require-namedlocale "en_US.ISO8859-1" }
+
+#include <locale>
+#include <testsuite_hooks.h> // for ISO_8859 macro
+
+int main()
+{
+  std::locale l1 = std::locale::classic();
+// { dg-final { note-test l1 {std::locale = "C"} } }
+
+  std::locale l2(ISO_8859(15,fr_FR));
+// { dg-final { regexp-test l2 {std::locale = "fr_FR.ISO8859-15(@euro)?"} } }
+
+  std::locale l3(l2, ISO_8859(15,de_DE), std::locale::time);
+// { dg-final { regexp-test l3 {std::locale = "fr_FR.ISO8859-15(@euro)?" with "LC_TIME=de_DE.ISO8859-15(@euro)?"} } }
+
+  std::locale l4(l3, ISO_8859(1,en_US), std::locale::monetary);
+// We don't know which order the categories will occur in the string,
+// so test three times, checking for the required substring each time:
+// { dg-final { regexp-test l4 {std::locale = "(.*;)?LC_CTYPE=fr_FR.ISO8859-15(@euro)?(;.*)?"} } }
+  std::locale l5 = l4;
+// { dg-final { regexp-test l5 {std::locale = "(.*;)?LC_TIME=de_DE.ISO8859-15(@euro)?(;.*)?"} } }
+  std::locale l6 = l5;
+// { dg-final { regexp-test l6 {std::locale = "(.*;)?LC_MONETARY=en_US.ISO8859-1(;.*)?"} } }
+
+  std::locale l7(l1, &std::use_facet<std::ctype<char> >(l1));
+// { dg-final { regexp-test l7 {std::locale = "\*"} } }
+
+  return 0;			// Mark SPOT
+}
+
+// { dg-final { gdb-test SPOT } }