libstdc++: Add Filesystem TS and std::stacktrace symbols to libstdc++exp.a

This consolidates the three static archives for extensions into one, so
that -lstdc++exp can be used to provide the definitions of all unstable
library features.

The libstdc++_libbacktrace.a archive is now just a "noinst" convenience
library that is only used during the build, not installed. Its contents
are added to libstdc++exp.a, along with the new non-inline definitions
of std::stacktrace symbols.

The libstdc++fs.a archive is still installed, but its contents are
duplicated in libstdc++exp.a now. This means -lstdc++exp can be used
instead of -lstdc++fs. For targets using the GNU linker we should
consider replacing libstdc++fs.a with a linker script that does
INPUT(libstdc++exp.a).

The tests for <experimental/filesystem> could be changed to use
-lstdc++exp instead of -lstdc++fs, which would allow removing
src/filesystem/.libs from the LDFLAGS in scripts/testsuite_flags.in,
but that can be done at a later date.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_CONFIGURE): Add c++23 directory.
	* configure: Regenerate.
	* doc/html/manual/*: Regenerate.
	* doc/xml/manual/using.xml: Update documentation on linking.
	* include/std/stacktrace: Remove declarations of libbacktrace
	APIs.
	(stacktrace_entry::_S_err_handler, stacktrace_entry::_S_init):
	Remove.
	(stacktrace_entry::_Info): New class.
	(stacktrace_entry::_M_get_info): Use _Info.
	(__stacktrace_impl): New class.
	(basic_stacktrace): Derive from __stacktrace_impl.
	(basic_stacktrace::current): Use __stacktrace_impl::_S_current.
	* scripts/testsuite_flags.in: Adjust LDFLAGS to find
	libstdc++exp instead of libstdc++_libbacktrace.
	* src/Makefile.am (SUBDIRS): Add c++23 directory.
	* src/Makefile.in: Regenerate.
	* src/c++20/Makefile.am: Fix comment.
	* src/c++20/Makefile.in: Regenerate.
	* src/c++23/Makefile.am: New file.
	* src/c++23/Makefile.in: New file.
	* src/c++23/stacktrace.cc: New file with definitions of
	stacktrace_entry::_Info and __stacktrace_impl members.
	* src/experimental/Makefile.am: Use LIBADD to include other
	libraries.
	* src/experimental/Makefile.in: Regenerate.
	* src/libbacktrace/Makefile.am: Use noinst_LTLIBRARIES.
	* src/libbacktrace/Makefile.in: Regenerate.
	* testsuite/19_diagnostics/stacktrace/current.cc: Adjust
	dg-options to use -lstdc++exp.
	* testsuite/19_diagnostics/stacktrace/entry.cc: Likewise.
	* testsuite/19_diagnostics/stacktrace/stacktrace.cc: Likewise.
	* testsuite/23_containers/vector/debug/assign4_backtrace_neg.cc:
	Likewise.

3 files changed, 37 insertions, 30 deletions

diff --git a/libstdc++-v3/doc/html/manual/using.html b/libstdc++-v3/doc/html/manual/using.html
index eebb35d..e8e0c6c 100644
--- a/libstdc++-v3/doc/html/manual/using.html
+++ b/libstdc++-v3/doc/html/manual/using.html
@@ -28,18 +28,20 @@
       </td></tr><tr><td align="left"><code class="literal">-latomic</code></td><td align="left">Linking to <code class="filename">libatomic</code>
         is required for some uses of ISO C++11
         <code class="filename">&lt;atomic&gt;</code>.
-      </td></tr><tr><td align="left"><code class="literal">-lstdc++fs</code></td><td align="left">Linking to <code class="filename">libstdc++fs</code>
-        is required for use of the Filesystem library extensions in
-        <code class="filename">&lt;experimental/filesystem&gt;</code>.
-      </td></tr><tr><td align="left"><code class="literal">-lstdc++exp</code></td><td align="left">Linking to <code class="filename">libstdc++exp</code>
-        is required for use of the C++ Contracts extensions enabled by
-        <code class="literal">-fcontracts</code>.
-      </td></tr><tr><td align="left"><code class="literal">-lstdc++_libbacktrace</code></td><td align="left">Until C++23 support is non-experimental, linking to
-	<code class="filename">libstdc++_libbacktrace.a</code>
-	is required for use of the C++23 type
-	<code class="classname">std::stacktrace</code>
-	and related types in
-	<code class="filename">&lt;stacktrace&gt;</code>.
+      </td></tr><tr><td align="left"><code class="literal">-lstdc++exp</code></td><td align="left">Linking to <code class="filename">libstdc++exp.a</code>
+        is required for use of experimental C++ library features.
+        This currently provides support for the C++23 types defined in the
+        <code class="filename">&lt;stacktrace&gt;</code> header,
+        the Filesystem library extensions defined in the
+        <code class="filename">&lt;experimental/filesystem&gt;</code>
+        header,
+        and the Contracts extensions enabled by <code class="literal">-fcontracts</code>.
+      </td></tr><tr><td align="left"><code class="literal">-lstdc++fs</code></td><td align="left">Linking to <code class="filename">libstdc++fs.a</code>
+        is another way to use the Filesystem library extensions defined in the
+        <code class="filename">&lt;experimental/filesystem&gt;</code>
+        header.
+        The <code class="filename">libstdc++exp.a</code> library
+        also provides all the symbols contained in this library.
       </td></tr><tr><td align="left"><code class="literal">-fopenmp</code></td><td align="left">For <a class="link" href="parallel_mode.html" title="Chapter 18. Parallel Mode">parallel</a> mode.</td></tr><tr><td align="left"><code class="literal">-ltbb</code></td><td align="left">Linking to tbb (Thread Building Blocks) is required for use of the
         Parallel Standard Algorithms and execution policies in
         <code class="filename">&lt;execution&gt;</code>.
diff --git a/libstdc++-v3/doc/html/manual/using_dynamic_or_shared.html b/libstdc++-v3/doc/html/manual/using_dynamic_or_shared.html
index 46ccbc5..f1e7278 100644
--- a/libstdc++-v3/doc/html/manual/using_dynamic_or_shared.html
+++ b/libstdc++-v3/doc/html/manual/using_dynamic_or_shared.html
@@ -138,6 +138,10 @@ A quick read of the relevant part of the GCC
       and link with <code class="option">-lstdc++fs</code>. The library implementation
       is incomplete on non-POSIX platforms, specifically Windows is only
       partially supported.
+      Since GCC 14, <code class="filename">libstdc++exp.a</code>
+      also contains the definitions for this library,
+      so <code class="option">-lstdc++exp</code> can be used instead of
+      <code class="option">-lstdc++fs</code>.
     </p><p>
       GCC 13 includes an implementation of the C++ Contracts library defined by
       <a class="link" href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1429r3.pdf" target="_top">P1429R3</a>.
diff --git a/libstdc++-v3/doc/xml/manual/using.xml b/libstdc++-v3/doc/xml/manual/using.xml
index 3a507fc..7276cad 100644
--- a/libstdc++-v3/doc/xml/manual/using.xml
+++ b/libstdc++-v3/doc/xml/manual/using.xml
@@ -101,29 +101,26 @@
     </row>
 
     <row>
-      <entry><literal>-lstdc++fs</literal></entry>
-      <entry>Linking to <filename class="libraryfile">libstdc++fs</filename>
-        is required for use of the Filesystem library extensions in
-        <filename class="headerfile">&lt;experimental/filesystem&gt;</filename>.
-      </entry>
-    </row>
-
-    <row>
       <entry><literal>-lstdc++exp</literal></entry>
-      <entry>Linking to <filename class="libraryfile">libstdc++exp</filename>
-        is required for use of the C++ Contracts extensions enabled by
-        <literal>-fcontracts</literal>.
+      <entry>Linking to <filename class="libraryfile">libstdc++exp.a</filename>
+        is required for use of experimental C++ library features.
+        This currently provides support for the C++23 types defined in the
+        <filename class="headerfile">&lt;stacktrace&gt;</filename> header,
+        the Filesystem library extensions defined in the
+        <filename class="headerfile">&lt;experimental/filesystem&gt;</filename>
+        header,
+        and the Contracts extensions enabled by <literal>-fcontracts</literal>.
       </entry>
     </row>
 
     <row>
-      <entry><literal>-lstdc++_libbacktrace</literal></entry>
-      <entry>Until C++23 support is non-experimental, linking to
-	<filename class="libraryfile">libstdc++_libbacktrace.a</filename>
-	is required for use of the C++23 type
-	<classname>std::stacktrace</classname>
-	and related types in
-	<filename class="headerfile">&lt;stacktrace&gt;</filename>.
+      <entry><literal>-lstdc++fs</literal></entry>
+      <entry>Linking to <filename class="libraryfile">libstdc++fs.a</filename>
+        is another way to use the Filesystem library extensions defined in the
+        <filename class="headerfile">&lt;experimental/filesystem&gt;</filename>
+        header.
+        The <filename class="libraryfile">libstdc++exp.a</filename> library
+        also provides all the symbols contained in this library.
       </entry>
     </row>
 
@@ -1710,6 +1707,10 @@ A quick read of the relevant part of the GCC
       and link with <option>-lstdc++fs</option>. The library implementation
       is incomplete on non-POSIX platforms, specifically Windows is only
       partially supported.
+      Since GCC 14, <filename class="libraryfile">libstdc++exp.a</filename>
+      also contains the definitions for this library,
+      so <option>-lstdc++exp</option> can be used instead of
+      <option>-lstdc++fs</option>.
     </para>
 
     <para>