[PATCH] libstdc++: Define <stacktrace> header for C++23

[Jonathan Wakely <jwakely@redhat.com>]

Add the <stacktrace> header and a new libstdc++_libbacktrace.a library
that provides the implementation. For now, the new library is only built
if --enable-libstdcxx-backtrace=yes is used. As with the Filesystem TS,
the new library is only provided as a static archive.

This should be improved during stage 3.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): New macro.
	* configure.ac: Use GLIBCXX_ENABLE_BACKTRACE.
	* include/Makefile.am: Add new header.
	* include/Makefile.in: Regenerate.
	* include/std/stacktrace: New file.
	* include/std/version (__cpp_lib_stacktrace): Define.
	* Makefile.in: Regenerate.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* doc/Makefile.in: Regenerate.
	* libsupc++/Makefile.in: Regenerate.
	* po/Makefile.in: Regenerate.
	* python/Makefile.in: Regenerate.
	* src/Makefile.am: Regenerate.
	* src/Makefile.in: Regenerate.
	* src/c++11/Makefile.in: Regenerate.
	* src/c++17/Makefile.in: Regenerate.
	* src/c++20/Makefile.in: Regenerate.
	* src/c++98/Makefile.in: Regenerate.
	* src/filesystem/Makefile.in: Regenerate.
	* testsuite/Makefile.in: Regenerate.
	* src/libbacktrace/Makefile.am: New file.
	* src/libbacktrace/Makefile.in: New file.
	* src/libbacktrace/backtrace-rename.h: New file.
	* src/libbacktrace/backtrace-supported.h.in: New file.
	* src/libbacktrace/config.h.in: New file.
---
 libstdc++-v3/Makefile.in                      |   7 +
 libstdc++-v3/acinclude.m4                     | 138 ++-
 libstdc++-v3/config.h.in                      |  10 +
 libstdc++-v3/configure                        | 317 ++++++-
 libstdc++-v3/configure.ac                     |   3 +
 libstdc++-v3/doc/Makefile.in                  |   7 +
 libstdc++-v3/include/Makefile.am              |   1 +
 libstdc++-v3/include/Makefile.in              |   8 +
 libstdc++-v3/include/std/stacktrace           | 665 ++++++++++++++
 libstdc++-v3/include/std/version              |   3 +
 libstdc++-v3/libsupc++/Makefile.in            |   7 +
 libstdc++-v3/po/Makefile.in                   |   7 +
 libstdc++-v3/python/Makefile.in               |   7 +
 libstdc++-v3/src/Makefile.am                  |  11 +-
 libstdc++-v3/src/Makefile.in                  |  14 +-
 libstdc++-v3/src/c++11/Makefile.in            |   7 +
 libstdc++-v3/src/c++17/Makefile.in            |   7 +
 libstdc++-v3/src/c++20/Makefile.in            |   7 +
 libstdc++-v3/src/c++98/Makefile.in            |   7 +
 libstdc++-v3/src/filesystem/Makefile.in       |   7 +
 libstdc++-v3/src/libbacktrace/Makefile.am     | 101 ++
 libstdc++-v3/src/libbacktrace/Makefile.in     | 859 ++++++++++++++++++
 .../src/libbacktrace/backtrace-rename.h       |  41 +
 .../src/libbacktrace/backtrace-supported.h.in |  61 ++
 libstdc++-v3/src/libbacktrace/config.h.in     | 184 ++++
 libstdc++-v3/testsuite/Makefile.in            |   7 +
 26 files changed, 2479 insertions(+), 14 deletions(-)
 create mode 100644 libstdc++-v3/include/std/stacktrace
 create mode 100644 libstdc++-v3/src/libbacktrace/Makefile.am
 create mode 100644 libstdc++-v3/src/libbacktrace/Makefile.in
 create mode 100644 libstdc++-v3/src/libbacktrace/backtrace-rename.h
 create mode 100644 libstdc++-v3/src/libbacktrace/backtrace-supported.h.in
 create mode 100644 libstdc++-v3/src/libbacktrace/config.h.in

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 30bd92d37f2..32c45ee254b 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/filesystem doc po testsuite python])
+  m4_define([glibcxx_SUBDIRS],[include libsupc++ src src/c++98 src/c++11 src/c++17 src/c++20 src/filesystem src/libbacktrace doc po testsuite python])
   SUBDIRS='glibcxx_SUBDIRS'
 
   # These need to be absolute paths, yet at the same time need to
@@ -4875,6 +4875,142 @@ AC_DEFUN([GLIBCXX_CHECK_ARC4RANDOM], [
   AC_LANG_RESTORE
 ])
 
+dnl
+dnl Check to see whether to build libstdc++_libbacktrace.a
+dnl
+dnl --enable-libstdcxx-backtrace
+dnl
+AC_DEFUN([GLIBCXX_ENABLE_BACKTRACE], [
+  GLIBCXX_ENABLE(libstdcxx-backtrace,auto,,
+    [turns on libbacktrace support],
+    [permit yes|no|auto])
+
+  # Most of this is adapted from libsanitizer/configure.ac
+
+  BACKTRACE_CPPFLAGS=
+
+  # libbacktrace only needs atomics for int, which we've already tested
+  if test "$glibcxx_cv_atomic_int" = "yes"; then
+    BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DHAVE_ATOMIC_FUNCTIONS=1"
+  fi
+
+  # Test for __sync support.
+  AC_CACHE_CHECK([__sync extensions],
+  [glibcxx_cv_sys_sync],
+  [GCC_TRY_COMPILE_OR_LINK(
+     [int i;],
+     [__sync_bool_compare_and_swap (&i, i, i);
+     __sync_lock_test_and_set (&i, 1);
+     __sync_lock_release (&i);],
+     [glibcxx_cv_sys_sync=yes],
+     [glibcxx_cv_sys_sync=no])
+  ])
+  if test "$glibcxx_cv_sys_sync" = "yes"; then
+    BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DHAVE_SYNC_FUNCTIONS=1"
+  fi
+
+  # Check for dl_iterate_phdr.
+  AC_CHECK_HEADERS(link.h)
+  if test "$ac_cv_header_link_h" = "no"; then
+    have_dl_iterate_phdr=no
+  else
+    # When built as a GCC target library, we can't do a link test.
+    AC_EGREP_HEADER([dl_iterate_phdr], [link.h], [have_dl_iterate_phdr=yes],
+		    [have_dl_iterate_phdr=no])
+  fi
+  if test "$have_dl_iterate_phdr" = "yes"; then
+    BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DHAVE_DL_ITERATE_PHDR=1"
+  fi
+
+  # Check for the fcntl function.
+  if test -n "${with_target_subdir}"; then
+     case "${host}" in
+     *-*-mingw*) have_fcntl=no ;;
+     *) have_fcntl=yes ;;
+     esac
+  else
+    AC_CHECK_FUNC(fcntl, [have_fcntl=yes], [have_fcntl=no])
+  fi
+  if test "$have_fcntl" = "yes"; then
+    BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DHAVE_FCNTL=1"
+  fi
+
+  AC_CHECK_DECLS(strnlen)
+
+  # Check for getexecname function.
+  if test -n "${with_target_subdir}"; then
+     case "${host}" in
+     *-*-solaris2*) have_getexecname=yes ;;
+     *) have_getexecname=no ;;
+     esac
+  else
+    AC_CHECK_FUNC(getexecname, [have_getexecname=yes], [have_getexecname=no])
+  fi
+  if test "$have_getexecname" = "yes"; then
+    BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DHAVE_GETEXECNAME=1"
+  fi
+
+# The library needs to be able to read the executable itself.  Compile
+# a file to determine the executable format.  The awk script
+# filetype.awk prints out the file type.
+AC_CACHE_CHECK([output filetype],
+[glibcxx_cv_sys_filetype],
+[filetype=
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([int i;], [int j;])],
+  [filetype=`${AWK} -f $srcdir/../libbacktrace/filetype.awk conftest.$ac_objext`],
+  [AC_MSG_FAILURE([compiler failed])])
+glibcxx_cv_sys_filetype=$filetype])
+
+# Match the file type to decide what files to compile.
+FORMAT_FILE=
+case "$glibcxx_cv_sys_filetype" in
+elf*) FORMAT_FILE="elf.lo" ;;
+*) AC_MSG_WARN([could not determine output file type])
+   FORMAT_FILE="unknown.lo"
+   enable_libstdcxx_backtrace=no
+   ;;
+esac
+AC_SUBST(FORMAT_FILE)
+
+# ELF defines.
+elfsize=
+case "$glibcxx_cv_sys_filetype" in
+elf32) elfsize=32 ;;
+elf64) elfsize=64 ;;
+esac
+BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DBACKTRACE_ELF_SIZE=$elfsize"
+
+  ALLOC_FILE=alloc.lo
+  AC_SUBST(ALLOC_FILE)
+  VIEW_FILE=read.lo
+  AC_SUBST(VIEW_FILE)
+
+  AC_MSG_CHECKING([whether to build libbacktrace support])
+  if test "$enable_libstdcxx_backtrace" == "auto"; then
+    enable_libstdcxx_backtrace=no
+  fi
+  if test "$enable_libstdcxx_backtrace" == "yes"; then
+    BACKTRACE_SUPPORTED=1
+    BACKTRACE_USES_MALLOC=1
+    if test "$ac_has_gthreads" = "yes"; then
+      BACKTRACE_SUPPORTS_THREADS=1
+    else
+      BACKTRACE_SUPPORTS_THREADS=0
+    fi
+    AC_SUBST(BACKTRACE_CPPFLAGS)
+    AC_SUBST(BACKTRACE_SUPPORTED)
+    AC_SUBST(BACKTRACE_USES_MALLOC)
+    AC_SUBST(BACKTRACE_SUPPORTS_THREADS)
+    AC_DEFINE(HAVE_STACKTRACE, 1, [Define if the <stacktrace> header is supported.])
+  else
+    BACKTRACE_SUPPORTED=0
+    BACKTRACE_USES_MALLOC=0
+    BACKTRACE_SUPPORTS_THREADS=0
+  fi
+  AC_MSG_RESULT($enable_libstdcxx_backtrace)
+  GLIBCXX_CONDITIONAL(ENABLE_BACKTRACE, [test "$enable_libstdcxx_backtrace" != no])
+])
 
 # Macros from the top-level gcc directory.
 m4_include([../config/gc++filt.m4])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 5b3c92f4bd7..e09ee76f10d 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -483,6 +483,8 @@ AC_CHECK_HEADERS([fcntl.h dirent.h sys/statvfs.h utime.h])
 GLIBCXX_ENABLE_FILESYSTEM_TS
 GLIBCXX_CHECK_FILESYSTEM_DEPS
 
+GLIBCXX_ENABLE_BACKTRACE
+
 # For Networking TS.
 AC_CHECK_HEADERS([fcntl.h sys/ioctl.h sys/socket.h sys/uio.h poll.h netdb.h arpa/inet.h netinet/in.h netinet/tcp.h])
 AC_CHECK_DECL(F_GETFL,,,[#include <fcntl.h>])
@@ -623,6 +625,7 @@ AC_CONFIG_FILES(Makefile)
 AC_CONFIG_FILES([scripts/testsuite_flags],[chmod +x scripts/testsuite_flags])
 AC_CONFIG_FILES([scripts/extract_symvers],[chmod +x scripts/extract_symvers])
 AC_CONFIG_FILES([doc/xsl/customization.xsl])
+AC_CONFIG_FILES([src/libbacktrace/backtrace-supported.h])
 
 # Multilibs need MULTISUBDIR defined correctly in certain makefiles so
 # that multilib installs will end up installed in the correct place.
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 25a8d9c8a41..615f30d9fec 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -80,6 +80,7 @@ std_headers = \
 	${std_srcdir}/sstream \
 	${std_srcdir}/syncstream \
 	${std_srcdir}/stack \
+	${std_srcdir}/stacktrace \
 	${std_srcdir}/stdexcept \
 	${std_srcdir}/stop_token \
 	${std_srcdir}/streambuf \
diff --git a/libstdc++-v3/include/std/stacktrace b/libstdc++-v3/include/std/stacktrace
new file mode 100644
index 00000000000..0d63a14a37c
--- /dev/null
+++ b/libstdc++-v3/include/std/stacktrace
@@ -0,0 +1,665 @@
+// <stacktrace> -*- 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.
+
+// 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/>.
+
+#ifndef _GLIBCXX_STACKTRACE
+#define _GLIBCXX_STACKTRACE 1
+
+#pragma GCC system_header
+
+#include <bits/c++config.h>
+
+#if __cplusplus > 202002L && _GLIBCXX_HAVE_STACKTRACE
+#include <compare>
+#include <string>
+#include <sstream>
+#include <bits/stl_algobase.h>
+#include <bits/stl_algo.h>
+#include <bits/stl_iterator.h>
+#include <bits/stl_uninitialized.h>
+#include <cxxabi.h>
+
+struct __glibcxx_backtrace_state;
+struct __glibcxx_backtrace_simple_data;
+
+extern "C"
+{
+__glibcxx_backtrace_state*
+__glibcxx_backtrace_create_state(const char*, int,
+				 void(*)(void*, const char*, int),
+				 void*);
+
+int
+__glibcxx_backtrace_simple(__glibcxx_backtrace_state*, int,
+			   int (*) (void*, uintptr_t),
+			   void(*)(void*, const char*, int),
+			   void*);
+int
+__glibcxx_backtrace_pcinfo(__glibcxx_backtrace_state*, uintptr_t,
+			   int (*)(void*, uintptr_t,
+				   const char*, int, const char*),
+			   void(*)(void*, const char*, int),
+			   void*);
+
+int
+__glibcxx_backtrace_syminfo(__glibcxx_backtrace_state*, uintptr_t addr,
+			    void (*) (void*, uintptr_t, const char*,
+				      uintptr_t, uintptr_t),
+			    void(*)(void*, const char*, int),
+			    void*);
+}
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+#define __cpp_lib_stacktrace 202011L
+
+  // [stacktrace.entry], class stacktrace_entry
+  class stacktrace_entry
+  {
+    using uint_least32_t = __UINT_LEAST32_TYPE__;
+    using uintptr_t = __UINTPTR_TYPE__;
+
+  public:
+    using native_handle_type = uintptr_t;
+
+    // [stacktrace.entry.ctor], constructors
+
+    constexpr
+    stacktrace_entry() noexcept = default;
+
+    constexpr
+    stacktrace_entry(const stacktrace_entry& __other) noexcept = default;
+
+    constexpr stacktrace_entry&
+    operator=(const stacktrace_entry& __other) noexcept = default;
+
+    ~stacktrace_entry() = default;
+
+    // [stacktrace.entry.obs], observers
+
+    constexpr native_handle_type
+    native_handle() const noexcept { return _M_pc; }
+
+    constexpr explicit operator bool() const noexcept { return _M_pc != -1; }
+
+    // [stacktrace.entry.query], query
+    string
+    description() const
+    {
+      string __s;
+      _M_get_info(&__s, nullptr, nullptr);
+      return __s;
+    }
+
+    string
+    source_file() const
+    {
+      string __s;
+      _M_get_info(nullptr, &__s, nullptr);
+      return __s;
+    }
+
+    uint_least32_t
+    source_line() const
+    {
+      int __line = 0;
+      _M_get_info(nullptr, nullptr, &__line);
+      return __line;
+    }
+
+    // [stacktrace.entry.cmp], comparison
+    friend constexpr bool
+    operator==(const stacktrace_entry& __x,
+	       const stacktrace_entry& __y) noexcept
+    { return __x._M_pc == __y._M_pc; }
+
+    friend constexpr strong_ordering
+    operator<=>(const stacktrace_entry& __x,
+		const stacktrace_entry& __y) noexcept
+    { return __x._M_pc <=> __y._M_pc; }
+
+  private:
+    native_handle_type _M_pc = -1;
+
+    template<typename _Allocator> friend class basic_stacktrace;
+
+    static __glibcxx_backtrace_state*
+    _S_init()
+    {
+      static __glibcxx_backtrace_state* __state
+	= __glibcxx_backtrace_create_state(nullptr, 1, nullptr, nullptr);
+      return __state;
+    }
+
+    template<typename _CharT, typename _Traits>
+      friend basic_ostream<_CharT, _Traits>&
+      operator<<(basic_ostream<_CharT, _Traits>&, const stacktrace_entry&);
+
+    bool
+    _M_get_info(string* __desc, string* __file, int* __line) const
+    {
+      if (!*this)
+	return false;
+
+      struct _Data
+      {
+	string* _M_desc;
+	string* _M_file;
+	int* _M_line;
+      } __data = { __desc, __file, __line };
+
+      auto __cb = [](void* __data, uintptr_t, const char* __filename,
+		     int __lineno, const char* __function) -> int {
+	  auto& __d = *static_cast<_Data*>(__data);
+	  if (__function && __d._M_desc)
+	    *__d._M_desc = _S_demangle(__function);
+	  if (__filename && __d._M_file)
+	    *__d._M_file = __filename;
+	  if (__d._M_line)
+	    *__d._M_line = __lineno;
+	  return __function != nullptr;
+      };
+      const auto __state = _S_init();
+      if (::__glibcxx_backtrace_pcinfo(__state, _M_pc, +__cb, nullptr, &__data))
+	return true;
+      if (__desc && __desc->empty())
+	{
+	  auto __cb2 = [](void* __data, uintptr_t, const char* __symname,
+	      uintptr_t, uintptr_t) {
+	      if (__symname)
+		*static_cast<_Data*>(__data)->_M_desc = _S_demangle(__symname);
+	  };
+	  if (::__glibcxx_backtrace_syminfo(__state, _M_pc, +__cb2, nullptr,
+					    &__data))
+	    return true;
+	}
+      return false;
+    }
+
+    static string
+    _S_demangle(const char* __name)
+    {
+      string __s;
+      int __status;
+      char* __str = __cxxabiv1::__cxa_demangle(__name, nullptr, nullptr,
+					       &__status);
+      if (__status == 0)
+	__s = __str;
+      __builtin_free(__str);
+      return __s;
+    }
+  };
+
+  // [stacktrace.basic], class template basic_stacktrace
+  template<typename _Allocator>
+    class basic_stacktrace
+    {
+      using _AllocTraits = allocator_traits<_Allocator>;
+
+    public:
+      using value_type = stacktrace_entry;
+      using const_reference = const value_type&;
+      using reference = value_type&;
+      using const_iterator
+	= __gnu_cxx::__normal_iterator<value_type*, basic_stacktrace>;
+      using iterator = const_iterator;
+      using reverse_iterator = std::reverse_iterator<iterator>;
+      using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+      using difference_type = ptrdiff_t;
+      using size_type = unsigned short;
+      using allocator_type = _Allocator;
+
+      // [stacktrace.basic.ctor], creation and assignment
+
+      static basic_stacktrace
+      current(const allocator_type& __alloc = allocator_type()) noexcept
+      {
+	return current(0, size_type(-1), __alloc);
+      }
+
+      static basic_stacktrace
+      current(size_type __skip,
+	      const allocator_type& __alloc = allocator_type()) noexcept
+      {
+	return current(__skip, size_type(-1), __alloc);
+      }
+
+      static basic_stacktrace
+      current(size_type __skip, size_type __max_depth,
+	      const allocator_type& __alloc = allocator_type()) noexcept
+      {
+	__glibcxx_assert(__skip <= (size_type(-1) - __max_depth));
+
+	auto __state = stacktrace_entry::_S_init();
+	basic_stacktrace __ret(__alloc);
+	if (!__ret._M_reserve(std::min<int>(__max_depth, 64)))
+	  return __ret;
+
+	auto __cb = [](void* __data, uintptr_t __pc) {
+	  auto& __s = *static_cast<basic_stacktrace*>(__data);
+	  stacktrace_entry __f;
+	  __f._M_pc = __pc;
+	  if (__s._M_push_back(__f))
+	    return 0;
+	  return 1;
+	};
+
+	if (__glibcxx_backtrace_simple(__state, __skip, +__cb, nullptr,
+				       std::__addressof(__ret)))
+	  {
+	    __ret._M_clear();
+	  }
+	return __ret;
+      }
+
+      basic_stacktrace()
+      noexcept(is_nothrow_default_constructible_v<allocator_type>)
+      { }
+
+      explicit
+      basic_stacktrace(const allocator_type& __alloc) noexcept
+      : _M_alloc(__alloc)
+      { }
+
+      basic_stacktrace(const basic_stacktrace& __other) noexcept
+      : basic_stacktrace(__other, __other._M_alloc)
+      { }
+
+      basic_stacktrace(basic_stacktrace&& __other) noexcept
+      : _M_alloc(std::move(__other._M_alloc)),
+	_M_impl(std::__exchange(__other._M_impl, {}))
+      { }
+
+      basic_stacktrace(const basic_stacktrace& __other,
+		       const allocator_type& __alloc) noexcept
+      : _M_alloc(__alloc)
+      {
+	if (const auto __s = __other._M_impl._M_size)
+	  if (auto __f = _M_impl._M_allocate(_M_alloc, __s))
+	    {
+	      std::uninitialized_copy_n(__other.begin(), __s, __f);
+	      _M_impl._M_size = __s;
+	    }
+      }
+
+      basic_stacktrace(basic_stacktrace&& __other,
+		       const allocator_type& __alloc) noexcept
+      : _M_alloc(__alloc)
+      {
+	if constexpr (_Allocator::is_always_equal::value)
+	  {
+	    _M_impl = std::__exchange(__other._M_impl, {});
+	  }
+	else if (_M_alloc == __other._M_alloc)
+	  {
+	    _M_impl = std::__exchange(__other._M_impl, {});
+	  }
+      }
+
+      basic_stacktrace&
+      operator=(const basic_stacktrace& __other) noexcept
+      {
+	if (std::__addressof(__other) == this)
+	  return *this;
+
+	constexpr bool __pocca
+	  = _AllocTraits::propagate_on_container_copy_assignment::value;
+	constexpr bool __always_eq = _AllocTraits::is_always_equal::value;
+
+	const auto __s = __other.size();
+
+	if constexpr (!__always_eq && __pocca)
+	  {
+	    if (_M_alloc != __other._M_alloc)
+	      {
+		// Cannot keep the same storage, so deallocate it now.
+		_M_clear();
+	      }
+	  }
+
+	if (_M_impl._M_capacity < __s)
+	  {
+	    // Need to allocate new storage.
+	    _M_clear();
+
+	    // Use the allocator we will have after this function returns.
+	    auto& __alloc = __pocca ? __other._M_alloc : _M_alloc;
+	    if (auto __f = _M_impl._M_allocate(__alloc, __s))
+	      {
+		std::uninitialized_copy_n(__other.begin(), __s, __f);
+		_M_impl._M_size = __s;
+	      }
+	  }
+	else
+	  {
+	    // Current storage is large enough and can be freed by whichever
+	    // allocator we will have after this function returns.
+	    auto __to = std::copy_n(__other.begin(), __s, begin());
+	    std::destroy(__to, end());
+	    _M_impl._M_size = __s;
+	  }
+
+	if constexpr (__pocca)
+	  _M_alloc = __other._M_alloc;
+
+	return *this;
+      }
+
+      basic_stacktrace&
+      operator=(basic_stacktrace&& __other) noexcept
+      {
+	if (std::__addressof(__other) == this)
+	  return *this;
+
+	constexpr bool __pocma
+	  = _AllocTraits::propagate_on_container_move_assignment::value;
+
+	if constexpr (_AllocTraits::is_always_equal::value)
+	  std::swap(_M_impl, __other._M_impl);
+	else if (_M_alloc == __other._M_alloc)
+	  std::swap(_M_impl, __other._M_impl);
+	else
+	  {
+	    const auto __s = __other.size();
+
+	    if constexpr (__pocma || _M_impl._M_capacity < __s)
+	      {
+		// Need to allocate new storage.
+		_M_clear();
+
+		// Use the allocator we will have after this function returns.
+		auto& __alloc = __pocma ? __other._M_alloc : _M_alloc;
+		if (auto __f = _M_impl._M_allocate(__alloc, __s))
+		  std::uninitialized_copy_n(__other.begin(), __s, __f);
+	      }
+	    else
+	      {
+		// Current storage is large enough.
+		auto __first = __other.begin();
+		auto __mid = __first + std::min(__s, _M_impl._M_size);
+		auto __last = __other.end();
+		auto __to = std::copy(__first, __mid, begin());
+		__to = std::uninitialized_copy(__mid, __last, __to);
+		std::destroy(__to, end());
+	      }
+	    _M_impl._M_size = __s;
+	  }
+
+	if constexpr (__pocma)
+	  _M_alloc = std::move(__other._M_alloc);
+
+	return *this;
+      }
+
+      constexpr ~basic_stacktrace()
+      {
+	_M_clear();
+      }
+
+      // [stacktrace.basic.obs], observers
+      allocator_type get_allocator() const noexcept { return _M_alloc; }
+
+      const_iterator
+      begin() const noexcept
+      { return const_iterator{_M_impl._M_frames}; }
+
+      const_iterator
+      end() const noexcept
+      { return begin() + size(); }
+
+      const_reverse_iterator
+      rbegin() const noexcept
+      { return std::make_reverse_iterator(end()); }
+
+      const_reverse_iterator
+      rend() const noexcept
+      { return std::make_reverse_iterator(begin()); }
+
+      const_iterator cbegin() const noexcept { return begin(); }
+      const_iterator cend() const noexcept { return end(); }
+      const_reverse_iterator crbegin() const noexcept { return rbegin(); };
+      const_reverse_iterator crend() const noexcept { return rend(); };
+
+      [[nodiscard]] bool empty() const noexcept { return size() == 0; }
+      size_type size() const noexcept { return _M_impl._M_size; }
+      size_type max_size() const noexcept { return size_type(-1); }
+
+      const_reference
+      operator[](size_type __n) const noexcept
+      {
+	__glibcxx_assert(__n < size());
+	return begin()[__n];
+      }
+
+      const_reference
+      at(size_type __n) const
+      {
+	if (__n >= size())
+	  __throw_out_of_range("basic_stack_trace::at: bad frame number");
+	return begin()[__n];
+      }
+
+      // [stacktrace.basic.cmp], comparisons
+      template<typename _Allocator2>
+	friend bool
+	operator==(const basic_stacktrace& __x,
+		   const basic_stacktrace<_Allocator2>& __y) noexcept
+	{ return std::equal(__x.begin(), __x.end(), __y.begin(), __y.end()); }
+
+      template<typename _Allocator2>
+	friend strong_ordering
+	operator<=>(const basic_stacktrace& __x,
+		    const basic_stacktrace<_Allocator2>& __y) noexcept
+	{
+	  if (auto __s = __x.size() <=> __y.size(); __s != 0)
+	    return __s;
+	  return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
+							__y.begin(), __y.end());
+	}
+
+      // [stacktrace.basic.mod], modifiers
+      void
+      swap(basic_stacktrace& __other) noexcept
+      {
+	std::swap(_M_impl. __other._M_impl);
+	if constexpr (_AllocTraits::propagate_on_container_swap::value)
+	  std::swap(_M_alloc, __other._M_alloc);
+      }
+
+    private:
+      bool
+      _M_reserve(size_type __n) noexcept
+      {
+	return _M_impl._M_allocate(_M_alloc, __n) != nullptr;
+      }
+
+      bool
+      _M_push_back(const value_type& __x) noexcept
+      {
+	return _M_impl._M_push_back(_M_alloc, __x);
+      }
+
+      void
+      _M_clear() noexcept
+      {
+	_M_impl._M_destroy();
+	_M_impl._M_deallocate(_M_alloc);
+      }
+
+      struct _Impl
+      {
+	using pointer = typename _AllocTraits::pointer;
+
+	pointer	  _M_frames   = nullptr;
+	size_type _M_size     = 0;
+	size_type _M_capacity = 0;
+
+	// Precondition: _M_frames == nullptr
+	pointer
+	_M_allocate(allocator_type& __alloc, size_type __n) noexcept
+	{
+	  __try
+	    {
+	      _M_frames = __n ? __alloc.allocate(__n) : nullptr;
+	      _M_capacity = __n;
+	    }
+	  __catch (...)
+	    {
+	      _M_frames = nullptr;
+	      _M_capacity = 0;
+	    }
+	  return _M_frames;
+	}
+
+	void
+	_M_deallocate(allocator_type& __alloc) noexcept
+	{
+	  if (_M_capacity)
+	    {
+	      __alloc.deallocate(_M_frames, _M_capacity);
+	      _M_frames = nullptr;
+	      _M_capacity = 0;
+	    }
+	}
+
+	void
+	_M_destroy() noexcept
+	{
+	  std::destroy_n(_M_frames, _M_size);
+	  _M_size = 0;
+	}
+
+	bool
+	_M_push_back(allocator_type& __alloc,
+		     const stacktrace_entry& __f) noexcept
+	{
+	  if (_M_size == _M_capacity)
+	    {
+	      _Impl __tmp;
+	      if (auto __f = __tmp._M_allocate(__alloc, _M_capacity * 2))
+		std::uninitialized_copy_n(_M_frames, _M_size, __f);
+	      else
+		return false;
+	      _M_deallocate(__alloc);
+	      std::swap(*this, __tmp);
+	    }
+	  stacktrace_entry* __addr = std::to_address(_M_frames + _M_size++);
+	  std::construct_at(__addr, __f);
+	  return true;
+	}
+
+      };
+
+      [[no_unique_address]] allocator_type  _M_alloc{};
+
+      _Impl _M_impl{};
+    };
+
+  // basic_stacktrace typedef names
+  using stacktrace = basic_stacktrace<allocator<stacktrace_entry>>;
+
+  // [stacktrace.basic.nonmem], non-member functions
+  template<typename _Allocator>
+    inline void
+    swap(basic_stacktrace<_Allocator>& __a, basic_stacktrace<_Allocator>& __b)
+    noexcept(noexcept(__a.swap(__b)))
+    { __a.swap(__b); }
+
+  template<typename _CharT, typename _Traits>
+    inline basic_ostream<_CharT, _Traits>&
+    operator<<(basic_ostream<_CharT, _Traits>& __os,
+	       const stacktrace_entry& __f)
+    {
+      string __desc, __file;
+      int __line;
+      if (__f._M_get_info(&__desc, &__file, &__line))
+	{
+	  __os.width(4);
+	  __os << __desc << " at " << __file << ':' << __line;
+	}
+      return __os;
+    }
+
+  template<typename _CharT, typename _Traits, typename _Allocator>
+    inline basic_ostream<_CharT, _Traits>&
+    operator<<(basic_ostream<_CharT, _Traits>& __os,
+	       const basic_stacktrace<_Allocator>& __st)
+    {
+      for (stacktrace::size_type __i = 0; __i < __st.size(); ++__i)
+	{
+	  __os.width(4);
+	  __os << __i << "# " << __st[__i] << '\n';
+	}
+      return __os;
+    }
+
+  inline string
+  to_string(const stacktrace_entry& __f)
+  {
+    std::ostringstream __os;
+    __os << __f;
+    return std::move(__os).str();
+  }
+
+  template<typename _Allocator>
+    string
+    to_string(const basic_stacktrace<_Allocator>& __st)
+    {
+      std::ostringstream __os;
+      __os << __st;
+      return std::move(__os).str();
+    }
+
+  // [stacktrace.basic.hash], hash support
+
+  template<>
+    struct hash<stacktrace_entry>
+    {
+      size_t
+      operator()(const stacktrace_entry& __f) const noexcept
+      {
+	using __h = hash<stacktrace_entry::native_handle_type>;
+	return __h()(__f.native_handle());
+      }
+    };
+
+  template<typename _Allocator>
+    struct hash<basic_stacktrace<_Allocator>>
+    {
+      size_t
+      operator()(const basic_stacktrace<_Allocator>& __st) const noexcept
+      {
+	hash<stacktrace_entry::native_handle_type> __h;
+	size_t __val = _Hash_impl::hash(__st.size());
+	for (const auto& __f : __st)
+	  __val = _Hash_impl::__hash_combine(__h(__f), __val);
+	return __val;
+      }
+    };
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+#endif // C++23
+
+#endif /* _GLIBCXX_STACKTRACE */
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index e8d696fa72f..0270071f33f 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -300,6 +300,9 @@
 #if __cpp_lib_span
 # define __cpp_lib_spanstream 202106L
 #endif
+#if _GLIBCXX_HAVE_STACKTRACE
+# define __cpp_lib_stacktrace 202011L
+#endif
 #define __cpp_lib_string_contains 202011L
 #if _GLIBCXX_USE_CXX11_ABI // Only supported with cxx11-abi
 # define __cpp_lib_string_resize_and_overwrite 202110L
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index f27d3f8c87e..51c82cf5446 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -28,8 +28,14 @@ else
 filesystem_dir =
 endif
 
+if ENABLE_BACKTRACE
+backtrace_dir = libbacktrace
+else
+backtrace_dir =
+endif
+
 ## Keep this list sync'd with acinclude.m4:GLIBCXX_CONFIGURE.
-SUBDIRS = c++98 c++11 c++17 c++20 $(filesystem_dir)
+SUBDIRS = c++98 c++11 c++17 c++20 $(filesystem_dir) $(backtrace_dir)
 
 # Cross compiler support.
 if VTV_CYGMIN
@@ -64,6 +70,9 @@ vpath % $(top_srcdir)/src/c++20
 if ENABLE_FILESYSTEM_TS
 vpath % $(top_srcdir)/src/filesystem
 endif
+if ENABLE_BACKTRACE
+vpath % $(top_srcdir)/src/libbacktrace
+endif
 
 if GLIBCXX_LDBL_COMPAT
 ldbl_compat_sources = compatibility-ldbl.cc
diff --git a/libstdc++-v3/src/libbacktrace/Makefile.am b/libstdc++-v3/src/libbacktrace/Makefile.am
new file mode 100644
index 00000000000..3a3195167b2
--- /dev/null
+++ b/libstdc++-v3/src/libbacktrace/Makefile.am
@@ -0,0 +1,101 @@
+# Makefile.am -- Backtrace in libstdc++ Makefile.
+# Copyright (C) 2012-2013 Free Software Foundation, Inc.
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+
+#     (1) Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer. 
+
+#     (2) Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in
+#     the documentation and/or other materials provided with the
+#     distribution.  
+
+#     (3) The name of the author may not be used to
+#     endorse or promote products derived from this software without
+#     specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+include $(top_srcdir)/fragment.am
+
+toolexeclib_LTLIBRARIES = libstdc++_libbacktrace.la
+
+ACLOCAL_AMFLAGS = -I ../.. -I ../../config
+
+AM_CPPFLAGS = -I $(top_srcdir)/../include -I $(top_srcdir)/../libgcc \
+	-I ../../../libgcc -I .. -I $(top_srcdir) \
+	-I $(top_srcdir)/../libbacktrace \
+	-include $(top_srcdir)/src/libbacktrace/backtrace-rename.h \
+	$(BACKTRACE_CPPFLAGS)
+
+WARN_FLAGS = -W -Wall -Wwrite-strings -Wmissing-format-attribute \
+	     -Wcast-qual -Werror
+C_WARN_FLAGS = $(WARN_FLAGS) -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wno-unused-but-set-variable
+CXX_WARN_FLAGS = $(WARN_FLAGS) -Wno-unused-parameter
+AM_CFLAGS = $(C_WARN_FLAGS)
+AM_CFLAGS += $(EXTRA_CFLAGS)
+AM_CXXFLAGS = $(CXX_WARN_FLAGS) -fno-rtti -fno-exceptions
+AM_CXXFLAGS += $(EXTRA_CXXFLAGS)
+
+libstdc___libbacktrace_la_SOURCES = \
+	../../../libbacktrace/backtrace.h \
+	../../../libbacktrace/atomic.c \
+	../../../libbacktrace/dwarf.c \
+	../../../libbacktrace/fileline.c \
+	../../../libbacktrace/internal.h \
+	../../../libbacktrace/posix.c \
+	../../../libbacktrace/sort.c \
+	../../../libbacktrace/simple.c \
+	../../../libbacktrace/state.c \
+	../../../libiberty/cp-demangle.c
+
+FORMAT_FILES = \
+	../../../libbacktrace/elf.c \
+	../../../libbacktrace/unknown.c
+
+VIEW_FILES = \
+	../../../libbacktrace/read.c \
+	../../../libbacktrace/mmapio.c
+
+ALLOC_FILES = \
+	../../../libbacktrace/alloc.c \
+	../../../libbacktrace/mmap.c
+
+EXTRA_libstdc___libbacktrace_la_SOURCES = \
+	$(FORMAT_FILES) \
+	$(VIEW_FILES) \
+	$(ALLOC_FILES)
+
+libstdc___libbacktrace_la_LIBADD = \
+	$(FORMAT_FILE) \
+	$(VIEW_FILE) \
+	$(ALLOC_FILE)
+
+libstdc___libbacktrace_la_DEPENDENCIES = $(libstdc___libbacktrace_la_LIBADD)
+
+LTCOMPILE = \
+	$(LIBTOOL) --tag CC --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=compile $(CC) $(TOPLEVEL_INCLUDES) \
+	$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) $(EXTRA_CFLAGS)
+
+LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
+
+LINK = \
+	$(LIBTOOL) --tag CC --tag disable-shared \
+	$(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
+	--mode=link $(CC) \
+	$(OPT_LDFLAGS) $(SECTION_LDFLAGS) $(AM_CFLAGS) $(LTLDFLAGS) -o $@
diff --git a/libstdc++-v3/src/libbacktrace/backtrace-rename.h b/libstdc++-v3/src/libbacktrace/backtrace-rename.h
new file mode 100644
index 00000000000..7a59f166e62
--- /dev/null
+++ b/libstdc++-v3/src/libbacktrace/backtrace-rename.h
@@ -0,0 +1,41 @@
+/* Ensure we don't pollute application namespace.  */
+#define backtrace_alloc __glibcxx_backtrace_alloc
+#define backtrace_close __glibcxx_backtrace_close
+#define backtrace_create_state __glibcxx_backtrace_create_state
+#define backtrace_dwarf_add __glibcxx_backtrace_dwarf_add
+#define backtrace_free __glibcxx_backtrace_free
+#define backtrace_get_view __glibcxx_backtrace_get_view
+#define backtrace_initialize __glibcxx_backtrace_initialize
+#define backtrace_open __glibcxx_backtrace_open
+#define backtrace_pcinfo __glibcxx_backtrace_pcinfo
+#define backtrace_qsort __glibcxx_backtrace_qsort
+#define backtrace_release_view __glibcxx_backtrace_release_view
+#define backtrace_simple __glibcxx_backtrace_simple
+#define backtrace_state __glibcxx_backtrace_state
+#define backtrace_syminfo __glibcxx_backtrace_syminfo
+#define backtrace_uncompress_lzma __glibcxx_backtrace_uncompress_lzma
+#define backtrace_uncompress_zdebug __glibcxx_backtrace_uncompress_zdebug
+#define backtrace_vector_finish __glibcxx_backtrace_vector_finish
+#define backtrace_vector_grow __glibcxx_backtrace_vector_grow
+#define backtrace_vector_release __glibcxx_backtrace_vector_release
+#define backtrace_syminfo_to_full_callback __glibcxx_backtrace_syminfo_to_full_callback
+#define backtrace_syminfo_to_full_error_callback __glibcxx_backtrace_syminfo_to_full_error_callback
+
+#define cplus_demangle_builtin_types __glibcxx_cplus_demangle_builtin_types
+#define cplus_demangle_fill_ctor __glibcxx_cplus_demangle_fill_ctor
+#define cplus_demangle_fill_dtor __glibcxx_cplus_demangle_fill_dtor
+#define cplus_demangle_fill_extended_operator __glibcxx_cplus_demangle_fill_extended_operator
+#define cplus_demangle_fill_name __glibcxx_cplus_demangle_fill_name
+#define cplus_demangle_init_info __glibcxx_cplus_demangle_init_info
+#define cplus_demangle_mangled_name __glibcxx_cplus_demangle_mangled_name
+#define cplus_demangle_operators __glibcxx_cplus_demangle_operators
+#define cplus_demangle_print __glibcxx_cplus_demangle_print
+#define cplus_demangle_print_callback __glibcxx_cplus_demangle_print_callback
+#define cplus_demangle_type __glibcxx_cplus_demangle_type
+#define cplus_demangle_v3 __glibcxx_cplus_demangle_v3
+#define cplus_demangle_v3_callback __glibcxx_cplus_demangle_v3_callback
+#define is_gnu_v3_mangled_ctor __glibcxx_is_gnu_v3_mangled_ctor
+#define is_gnu_v3_mangled_dtor __glibcxx_is_gnu_v3_mangled_dtor
+#define java_demangle_v3 __glibcxx_java_demangle_v3
+#define java_demangle_v3_callback __glibcxx_java_demangle_v3_callback
+
diff --git a/libstdc++-v3/src/libbacktrace/backtrace-supported.h.in b/libstdc++-v3/src/libbacktrace/backtrace-supported.h.in
new file mode 100644
index 00000000000..c615f6406ab
--- /dev/null
+++ b/libstdc++-v3/src/libbacktrace/backtrace-supported.h.in
@@ -0,0 +1,61 @@
+/* backtrace-supported.h.in -- Whether stack backtrace is supported.
+   Copyright (C) 2012-2013 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Google.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer. 
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.  
+    
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+/* The file backtrace-supported.h.in is used by configure to generate
+   the file backtrace-supported.h.  The file backtrace-supported.h may
+   be #include'd to see whether the backtrace library will be able to
+   get a backtrace and produce symbolic information.  */
+
+
+/* BACKTRACE_SUPPORTED will be #define'd as 1 if the backtrace library
+   should work, 0 if it will not.  Libraries may #include this to make
+   other arrangements.  */
+
+#define BACKTRACE_SUPPORTED @BACKTRACE_SUPPORTED@
+
+/* BACKTRACE_USES_MALLOC will be #define'd as 1 if the backtrace
+   library will call malloc as it works, 0 if it will call mmap
+   instead.  This may be used to determine whether it is safe to call
+   the backtrace functions from a signal handler.  In general this
+   only applies to calls like backtrace and backtrace_pcinfo.  It does
+   not apply to backtrace_simple, which never calls malloc.  It does
+   not apply to backtrace_print, which always calls fprintf and
+   therefore malloc.  */
+
+#define BACKTRACE_USES_MALLOC @BACKTRACE_USES_MALLOC@
+
+/* BACKTRACE_SUPPORTS_THREADS will be #define'd as 1 if the backtrace
+   library is configured with threading support, 0 if not.  If this is
+   0, the threaded parameter to backtrace_create_state must be passed
+   as 0.  */
+
+#define BACKTRACE_SUPPORTS_THREADS @BACKTRACE_SUPPORTS_THREADS@
diff --git a/libstdc++-v3/src/libbacktrace/config.h.in b/libstdc++-v3/src/libbacktrace/config.h.in
new file mode 100644
index 00000000000..cdb416e6406
--- /dev/null
+++ b/libstdc++-v3/src/libbacktrace/config.h.in
@@ -0,0 +1,184 @@
+/* config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* ELF size: 32 or 64 */
+#undef BACKTRACE_ELF_SIZE
+
+/* XCOFF size: 32 or 64 */
+#undef BACKTRACE_XCOFF_SIZE
+
+/* Define to 1 if you have the __atomic functions */
+#undef HAVE_ATOMIC_FUNCTIONS
+
+/* Define to 1 if you have the `clock_gettime' function. */
+#undef HAVE_CLOCK_GETTIME
+
+/* Define to 1 if you have the declaration of `getpagesize', and to 0 if you
+   don't. */
+#undef HAVE_DECL_GETPAGESIZE
+
+/* Define to 1 if you have the declaration of `strnlen', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRNLEN
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#undef HAVE_DLFCN_H
+
+/* Define if dl_iterate_phdr is available. */
+#undef HAVE_DL_ITERATE_PHDR
+
+/* Define to 1 if you have the fcntl function */
+#undef HAVE_FCNTL
+
+/* Define if getexecname is available. */
+#undef HAVE_GETEXECNAME
+
+/* Define if _Unwind_GetIPInfo is available. */
+#undef HAVE_GETIPINFO
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#undef HAVE_INTTYPES_H
+
+/* Define to 1 if you have KERN_PROC and KERN_PROC_PATHNAME in <sys/sysctl.h>.
+   */
+#undef HAVE_KERN_PROC
+
+/* Define to 1 if you have KERN_PROCARGS and KERN_PROC_PATHNAME in
+   <sys/sysctl.h>. */
+#undef HAVE_KERN_PROC_ARGS
+
+/* Define if -llzma is available. */
+#undef HAVE_LIBLZMA
+
+/* Define to 1 if you have the <link.h> header file. */
+#undef HAVE_LINK_H
+
+/* Define if AIX loadquery is available. */
+#undef HAVE_LOADQUERY
+
+/* Define to 1 if you have the `lstat' function. */
+#undef HAVE_LSTAT
+
+/* Define to 1 if you have the <mach-o/dyld.h> header file. */
+#undef HAVE_MACH_O_DYLD_H
+
+/* Define to 1 if you have the <memory.h> header file. */
+#undef HAVE_MEMORY_H
+
+/* Define to 1 if you have the `readlink' function. */
+#undef HAVE_READLINK
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#undef HAVE_STDINT_H
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#undef HAVE_STDLIB_H
+
+/* Define to 1 if you have the <strings.h> header file. */
+#undef HAVE_STRINGS_H
+
+/* Define to 1 if you have the <string.h> header file. */
+#undef HAVE_STRING_H
+
+/* Define to 1 if you have the __sync functions */
+#undef HAVE_SYNC_FUNCTIONS
+
+/* Define to 1 if you have the <sys/ldr.h> header file. */
+#undef HAVE_SYS_LDR_H
+
+/* Define to 1 if you have the <sys/mman.h> header file. */
+#undef HAVE_SYS_MMAN_H
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#undef HAVE_SYS_STAT_H
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#undef HAVE_SYS_TYPES_H
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#undef HAVE_UNISTD_H
+
+/* Define if -lz is available. */
+#undef HAVE_ZLIB
+
+/* Define to the sub-directory in which libtool stores uninstalled libraries.
+   */
+#undef LT_OBJDIR
+
+/* Define to the address where bug reports for this package should be sent. */
+#undef PACKAGE_BUGREPORT
+
+/* Define to the full name of this package. */
+#undef PACKAGE_NAME
+
+/* Define to the full name and version of this package. */
+#undef PACKAGE_STRING
+
+/* Define to the one symbol short name of this package. */
+#undef PACKAGE_TARNAME
+
+/* Define to the home page for this package. */
+#undef PACKAGE_URL
+
+/* Define to the version of this package. */
+#undef PACKAGE_VERSION
+
+/* The size of `char', as computed by sizeof. */
+#undef SIZEOF_CHAR
+
+/* The size of `int', as computed by sizeof. */
+#undef SIZEOF_INT
+
+/* The size of `long', as computed by sizeof. */
+#undef SIZEOF_LONG
+
+/* The size of `short', as computed by sizeof. */
+#undef SIZEOF_SHORT
+
+/* The size of `void *', as computed by sizeof. */
+#undef SIZEOF_VOID_P
+
+/* Define to 1 if you have the ANSI C header files. */
+#undef STDC_HEADERS
+
+/* Enable extensions on AIX 3, Interix.  */
+#ifndef _ALL_SOURCE
+# undef _ALL_SOURCE
+#endif
+/* Enable GNU extensions on systems that have them.  */
+#ifndef _GNU_SOURCE
+# undef _GNU_SOURCE
+#endif
+/* Enable threading extensions on Solaris.  */
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# undef _POSIX_PTHREAD_SEMANTICS
+#endif
+/* Enable extensions on HP NonStop.  */
+#ifndef _TANDEM_SOURCE
+# undef _TANDEM_SOURCE
+#endif
+/* Enable general extensions on Solaris.  */
+#ifndef __EXTENSIONS__
+# undef __EXTENSIONS__
+#endif
+
+
+/* Enable large inode numbers on Mac OS X 10.5.  */
+#ifndef _DARWIN_USE_64_BIT_INODE
+# define _DARWIN_USE_64_BIT_INODE 1
+#endif
+
+/* Number of bits in a file offset, on hosts where this is settable. */
+#undef _FILE_OFFSET_BITS
+
+/* Define for large files, on AIX-style hosts. */
+#undef _LARGE_FILES
+
+/* Define to 1 if on MINIX. */
+#undef _MINIX
+
+/* Define to 2 if the system does not provide POSIX.1 features except with
+   this defined. */
+#undef _POSIX_1_SOURCE
+
+/* Define to 1 if you need to in order for `stat' and other things to work. */
+#undef _POSIX_SOURCE