configure.xml: Update descriptions of options affecting dual ABI and add cross-references.

	* doc/xml/manual/configure.xml: Update descriptions of options
	affecting dual ABI and add cross-references.
	* doc/xml/manual/strings.xml: Clarify that string isn't COW now.
	* doc/xml/manual/using.xml: Document ABI transition.
	* doc/html/*: Regenerate.

From-SVN: r222262

libstdc++-v3/ChangeLog

 2015-04-21  Jonathan Wakely  <jwakely@redhat.com>
 
+	* doc/xml/manual/configure.xml: Update descriptions of options
+	affecting dual ABI and add cross-references.
+	* doc/xml/manual/strings.xml: Clarify that string isn't COW now.
+	* doc/xml/manual/using.xml: Document ABI transition.
+	* doc/html/*: Regenerate.
+
 	* doc/xml/manual/abi.xml: Use uppercase for C++ Standard Library.
 	* doc/xml/manual/using.xml: Document newer -std options. Use better
 	examples of nested namespaces.

libstdc++-v3/doc/html/manual/abi.html

@@ -38,7 +38,7 @@
   documented
 <a class="link" href="configure.html" title="Configure">here</a>.
 </p><p> Putting all of these ideas together results in the C++ Standard
-library ABI, which is the compilation of a given library API by a
+Library ABI, which is the compilation of a given library API by a
 given compiler ABI. In a nutshell:
 </p><p>
   <span class="quote">“<span class="quote">

libstdc++-v3/doc/html/manual/configure.html

@@ -228,13 +228,17 @@
      when standard error is not available.  This option disables those
      messages.  This option does not change the library ABI.
    </p></dd><dt><span class="term"><code class="code">--disable-libstdcxx-dual-abi</code></span></dt><dd><p>
-     Disable support for the new, C++11-conforming <code class="code">std::string</code>
-     implementation.  This option changes the library ABI.
-   </p></dd><dt><span class="term"><code class="code">--with-default-libstdcxx-abi</code></span></dt><dd><p>
-     By default, the new <code class="code">std::string</code> implementation will be
-     declared and a macro must be defined to declare the old implementation
-     instead. That default can be reversed by configuring the library with
-     <code class="code">--with-default-libstdcxx-abi=c++98</code>.
+     Disable support for the new, C++11-conforming implementations of
+     <code class="code">std::string</code>, <code class="code">std::list</code> etc. so that the
+     library only provides definitions of types using the old ABI
+     (see <a class="xref" href="using_dual_abi.html" title="Dual ABI">Dual ABI</a>).
+     This option changes the library ABI.
+   </p></dd><dt><span class="term"><code class="code">--with-default-libstdcxx-abi=</code><em class="replaceable"><code>OPTION</code></em></span></dt><dd><p>
+     Set the default value for the <span class="symbol">_GLIBCXX_USE_CXX11_ABI</span>
+     macro (see <a class="xref" href="using_macros.html" title="Macros">Macros</a>).
+     The default is <code class="option">OPTION=c++11</code> which sets the macro to
+     <code class="literal">1</code>,
+     use <code class="option">OPTION=c++98</code> to set it to <code class="literal">0</code>.
      This option does not change the library ABI.
    </p></dd><dt><span class="term"><code class="code">--enable-vtable-verify</code>[default]</span></dt><dd><p>Use <code class="code">-fvtable-verify=std</code> to compile the C++
     runtime with instrumentation for vtable verification. All virtual

libstdc++-v3/doc/html/manual/strings.html

@@ -267,7 +267,7 @@ stringtok(Container &container, string const &in,
       a <code class="code">vector</code>'s memory usage
       (see <a class="link" href="../faq.html#faq.size_equals_capacity" title="7.8.">this FAQ
       entry</a>) but the regular copy constructor cannot be used
-      because libstdc++'s <code class="code">string</code> is Copy-On-Write.
+      because libstdc++'s <code class="code">string</code> is Copy-On-Write in GCC 3.
    </p><p>In <a class="link" href="status.html#status.iso.2011" title="C++ 2011">C++11</a> mode you can call
       <code class="code">s.shrink_to_fit()</code> to achieve the same effect as
       <code class="code">s.reserve(s.size())</code>.

libstdc++-v3/doc/html/manual/using_dual_abi.html

+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Dual ABI</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using_macros.html" title="Macros" /><link rel="next" href="using_namespaces.html" title="Namespaces" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Dual ABI</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using_macros.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.abi"></a>Dual ABI</h2></div></div></div><p> In the GCC 5.1 release libstdc++ introduced a new library ABI that
+  includes new implementations of <code class="classname">std::string</code> and
+  <code class="classname">std::list</code>. These changes were necessary to conform
+  to the 2011 C++ standard which forbids Copy-On-Write strings and requires
+  lists to keep track of their size.
+</p><p> In order to maintain backwards compatibility for existing code linked
+  to libstdc++ the library's soname has not changed and the old
+  implementations are still supported in parallel with the new ones.
+  This is achieved by defining the new implementations in an inline namespace
+  so they have different names for linkage purposes, e.g. the new version of
+  <code class="classname">std::list&lt;int&gt;</code> is actually defined as
+  <code class="classname">std::__cxx11::list&lt;int&gt;</code>. Because the symbols
+  for the new implementations have different names the definitions for both
+  versions can be present in the same library.
+</p><p> The <span class="symbol">_GLIBCXX_USE_CXX11_ABI</span> macro (see
+<a class="xref" href="using_macros.html" title="Macros">Macros</a>) controls whether
+  the declarations in the library headers use the old or new ABI.
+  So the decision of which ABI to use can be made separately for each
+  source file being compiled.
+  Using the default configuration options for GCC the default value
+  of the macro is <code class="literal">1</code> which causes the new ABI to be active,
+  so to use the old ABI you must explicitly define the macro to
+  <code class="literal">0</code> before including any library headers.
+  (Be aware that some GNU/Linux distributions configure GCC 5 differently so
+  that the default value of the macro is <code class="literal">0</code> and users must
+  define it to <code class="literal">1</code> to enable the new ABI.)
+</p><p> Although the changes were made for C++11 conformance, the choice of ABI
+  to use is independent of the <code class="option">-std</code> option used to compile
+  your code, i.e. for a given GCC build the default value of the
+  <span class="symbol">_GLIBCXX_USE_CXX11_ABI</span> macro is the same for all dialects.
+  This ensures that the <code class="option">-std</code> does not change the ABI, so
+  that it is straightforward to link C++03 and C++11 code together.
+</p><p> Because <code class="classname">std::string</code> is used extensively
+  throughout the library a number of other types are also defined twice,
+  including the stringstream classes and several facets used by
+  <code class="classname">std::locale</code>. The standard facets which are always
+  installed in a locale may be present twice, with both ABIs, to ensure that
+  code like
+  <code class="code">std::use_facet&lt;std::time_get&lt;char&gt;&gt;(locale);</code>
+  will work correctly for both <code class="classname">std::time_get</code> and
+  <code class="classname">std::__cxx11::time_get</code> (even if a user-defined
+  facet that derives from one or other version of
+  <code class="classname">time_get</code> is installed in the locale).
+</p><p> Although the standard exception types defined in
+  <code class="filename">&lt;stdexcept&gt;</code> use strings, they
+  are not defined twice, so that a <code class="classname">std::out_of_range</code>
+  exception thrown in one file can always be caught by a suitable handler in
+  another file, even if the two files are compiled with different ABIs.
+</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.abi.trouble"></a>Troubleshooting</h3></div></div></div><p> If you get linker errors about undefined references to symbols
+  that involve types in the <code class="code">std::__cxx11</code> namespace or the tag
+  <code class="code">[abi:cxx11]</code> then it probably indicates that you are trying to
+  link together object files that were compiled with different values for the
+  <span class="symbol">_GLIBCXX_USE_CXX11_ABI</span> macro. This commonly happens when
+  linking to a third-party library that was compiled with an older version
+  of GCC. If the third-party library cannot be rebuilt with the new ABI then
+  you will need to recompile your code with the old ABI.
+</p><p> Not all uses of the new ABI will cause changes in symbol names, for
+  example a class with a <code class="classname">std::string</code> member variable
+  will have the same mangled name whether compiled with the old or new ABI.
+  In order to detect such problems the new types and functions are
+  annotated with the <span class="property">abi_tag</span> attribute, allowing the
+  compiler to warn about potential ABI incompatibilities in code using them.
+  Those warnings can be enabled with the <code class="option">-Wabi-tag</code> option.
+</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_macros.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Macros </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Namespaces</td></tr></table></div></body></html>
\ No newline at end of file

libstdc++-v3/doc/html/manual/using_exceptions.html

@@ -265,7 +265,7 @@ is called.
   }
   catch(...)
   { this->_M_setstate(ios_base::badbit); }
-</pre></div></div><div class="bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="using.exceptions.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.2"></a><p><span class="title"><em>
+</pre></div></div><div class="bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="using.exceptions.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.2"></a><p><span class="title"><em>
 	<a class="link" href="http://www.opengroup.org/austin/" target="_top">
 	System Interface Definitions, Issue 7 (IEEE Std. 1003.1-2008)
 	</a>
@@ -274,39 +274,39 @@ is called.
     . </span><span class="copyright">Copyright © 2008 
 	The Open Group/The Institute of Electrical and Electronics
 	Engineers, Inc.
-      . </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.3"></a><p><span class="title"><em>
+      . </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.3"></a><p><span class="title"><em>
 	<a class="link" href="http://www.boost.org/community/error_handling.html" target="_top">
 	Error and Exception Handling
 	</a>
       </em>. </span><span class="author"><span class="firstname">David</span> <span class="surname">Abrahams </span>. </span><span class="publisher"><span class="publishername">
 	Boost
-      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.4"></a><p><span class="title"><em>
+      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.4"></a><p><span class="title"><em>
 	<a class="link" href="http://www.boost.org/community/exception_safety.html" target="_top">
 	Exception-Safety in Generic Components
 	</a>
       </em>. </span><span class="author"><span class="firstname">David</span> <span class="surname">Abrahams</span>. </span><span class="publisher"><span class="publishername">
 	Boost
-      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.5"></a><p><span class="title"><em>
+      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.5"></a><p><span class="title"><em>
 	<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1997/N1077.pdf" target="_top">
 	Standard Library Exception Policy
 	</a>
       </em>. </span><span class="author"><span class="firstname">Matt</span> <span class="surname">Austern</span>. </span><span class="publisher"><span class="publishername">
 	WG21 N1077
-      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.6"></a><p><span class="title"><em>
+      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.6"></a><p><span class="title"><em>
 	<a class="link" href="http://gcc.gnu.org/ml/gcc-patches/2001-03/msg00661.html" target="_top">
 	ia64 c++ abi exception handling
 	</a>
       </em>. </span><span class="author"><span class="firstname">Richard</span> <span class="surname">Henderson</span>. </span><span class="publisher"><span class="publishername">
 	GNU
-      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.7"></a><p><span class="title"><em>
+      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.7"></a><p><span class="title"><em>
 	<a class="link" href="http://www.research.att.com/~bs/3rd_safe.pdf" target="_top">
 	Appendix E: Standard-Library Exception Safety
 	</a>
-      </em>. </span><span class="author"><span class="firstname">Bjarne</span> <span class="surname">Stroustrup</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.8"></a><p><span class="citetitle"><em class="citetitle">
+      </em>. </span><span class="author"><span class="firstname">Bjarne</span> <span class="surname">Stroustrup</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.8"></a><p><span class="citetitle"><em class="citetitle">
       Exceptional C++
     </em>. </span><span class="pagenums">
       Exception-Safety Issues and Techniques
-    . </span><span class="author"><span class="firstname">Herb</span> <span class="surname">Sutter</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.8.9.9"></a><p><span class="title"><em>
+    . </span><span class="author"><span class="firstname">Herb</span> <span class="surname">Sutter</span>. </span></p></div><div class="biblioentry"><a id="id-1.3.3.4.9.9.9"></a><p><span class="title"><em>
 	<a class="link" href="http://gcc.gnu.org/PR25191" target="_top">
       GCC Bug 25191: exception_defines.h #defines try/catch
 	</a>

libstdc++-v3/doc/html/manual/using_macros.html

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Macros</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using_headers.html" title="Headers" /><link rel="next" href="using_namespaces.html" title="Namespaces" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Macros</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.macros"></a>Macros</h2></div></div></div><p>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Macros</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using_headers.html" title="Headers" /><link rel="next" href="using_dual_abi.html" title="Dual ABI" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Macros</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_dual_abi.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.macros"></a>Macros</h2></div></div></div><p>
      All library macros begin with <code class="code">_GLIBCXX_</code>.
    </p><p>
      Furthermore, all pre-processor macros, switches, and
@@ -50,6 +50,17 @@
 	be useful in updating old C++ code which no longer meet the
 	requirements of the language, or for checking current code
 	against new language standards.
+    </p></dd><dt><span class="term"><code class="code">_GLIBCXX_USE_CXX11_ABI</code></span></dt><dd><p>
+        Defined to the value <code class="literal">1</code> by default.
+        Configurable via  <code class="code">--disable-libstdcxx-dual-abi</code>
+        and/or <code class="code">--with-default-libstdcxx-abi</code>.
+        ABI-changing.
+        When defined to a non-zero value the library headers will use the
+        new C++11-conforming ABI introduced in GCC 5, rather than the older
+        ABI introduced in GCC 3.4. This changes the definition of several
+        class templates, including <code class="classname">std:string</code>,
+        <code class="classname">std::list</code> and some locale facets.
+        For more details see <a class="xref" href="using_dual_abi.html" title="Dual ABI">Dual ABI</a>.
     </p></dd><dt><span class="term"><code class="code">_GLIBCXX_CONCEPT_CHECKS</code></span></dt><dd><p>
 	Undefined by default.  Configurable via
 	<code class="code">--enable-concept-checks</code>.  When defined, performs
@@ -71,4 +82,4 @@
       </p></dd><dt><span class="term"><code class="code">_GLIBCXX_PROFILE</code></span></dt><dd><p>Undefined by default. When defined, compiles user code
 	using the <a class="link" href="profile_mode.html" title="Chapter 19. Profile Mode">profile
 	mode</a>.
-      </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Headers </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Namespaces</td></tr></table></div></body></html>
+      </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_dual_abi.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Headers </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Dual ABI</td></tr></table></div></body></html>
\ No newline at end of file

libstdc++-v3/doc/html/manual/using_namespaces.html

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Namespaces</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using_macros.html" title="Macros" /><link rel="next" href="using_dynamic_or_shared.html" title="Linking" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Namespaces</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using_macros.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_dynamic_or_shared.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.namespaces"></a>Namespaces</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.namespaces.all"></a>Available Namespaces</h3></div></div></div><p> There are three main namespaces.
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Namespaces</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="using.html" title="Chapter 3. Using" /><link rel="prev" href="using_dual_abi.html" title="Dual ABI" /><link rel="next" href="using_dynamic_or_shared.html" title="Linking" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Namespaces</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="using_dual_abi.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_dynamic_or_shared.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.namespaces"></a>Namespaces</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.namespaces.all"></a>Available Namespaces</h3></div></div></div><p> There are three main namespaces.
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>std</p><p>The ISO C++ standards specify that "all library entities are defined
 within namespace std." This includes namespaces nested
-within <code class="code">namespace std</code>, such as <code class="code">namespace
-std::tr1</code>.
+within namespace <code class="code">std</code>, such as namespace
+<code class="code">std::chrono</code>.
 </p></li><li class="listitem"><p>abi</p><p>Specified by the C++ ABI. This ABI specifies a number of type and
 function APIs supplemental to those required by the ISO C++ Standard,
 but necessary for interoperability.
 </p></li><li class="listitem"><p>__gnu_</p><p>Indicating one of several GNU extensions. Choices
 include <code class="code">__gnu_cxx</code>, <code class="code">__gnu_debug</code>, <code class="code">__gnu_parallel</code>,
 and <code class="code">__gnu_pbds</code>.
-</p></li></ul></div><p> A complete list of implementation namespaces (including namespace contents) is available in the generated source <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/namespaces.html" target="_top">documentation</a>.
+</p></li></ul></div><p> The library uses a number of inline namespaces as implementation
+details that are not intended for users to refer to directly, these include
+<code class="code">std::__detail</code>, <code class="code">std::__cxx11</code> and <code class="code">std::_V2</code>.
+</p><p> A complete list of implementation namespaces (including namespace contents) is available in the generated source <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/namespaces.html" target="_top">documentation</a>.
 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.namespaces.std"></a>namespace std</h3></div></div></div><p>
       One standard requirement is that the library components are defined
       in <code class="code">namespace std::</code>. Thus, in order to use these types or
@@ -57,4 +60,4 @@ namespace gtk
 	  std::string;</code> (depending on whether the system has
 	libstdc++ in <code class="code">std::</code> or not).  (ideas from
 	Llewelly and Karl Nelson)
-</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_macros.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_dynamic_or_shared.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Macros </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Linking</td></tr></table></div></body></html>
+</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_dual_abi.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_dynamic_or_shared.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Dual ABI </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Linking</td></tr></table></div></body></html>
\ No newline at end of file

libstdc++-v3/doc/xml/manual/configure.xml

@@ -385,18 +385,22 @@
 <varlistentry><term><code>--disable-libstdcxx-dual-abi</code></term>
  <listitem>
    <para>
-     Disable support for the new, C++11-conforming <code>std::string</code>
-     implementation.  This option changes the library ABI.
+     Disable support for the new, C++11-conforming implementations of
+     <code>std::string</code>, <code>std::list</code> etc. so that the
+     library only provides definitions of types using the old ABI
+     (see <xref linkend="manual.intro.using.abi"/>).
+     This option changes the library ABI.
    </para>
  </listitem></varlistentry>
 
-<varlistentry><term><code>--with-default-libstdcxx-abi</code></term>
+<varlistentry><term><code>--with-default-libstdcxx-abi=</code><replaceable>OPTION</replaceable></term>
  <listitem>
    <para>
-     By default, the new <code>std::string</code> implementation will be
-     declared and a macro must be defined to declare the old implementation
-     instead. That default can be reversed by configuring the library with
-     <code>--with-default-libstdcxx-abi=c++98</code>.
+     Set the default value for the <symbol>_GLIBCXX_USE_CXX11_ABI</symbol>
+     macro (see <xref linkend="manual.intro.using.macros"/>).
+     The default is <option>OPTION=c++11</option> which sets the macro to
+     <literal>1</literal>,
+     use <option>OPTION=c++98</option> to set it to <literal>0</literal>.
      This option does not change the library ABI.
    </para>
  </listitem></varlistentry>

libstdc++-v3/doc/xml/manual/strings.xml

@@ -353,7 +353,7 @@ stringtok(Container &container, string const &in,
       a <code>vector</code>'s memory usage
       (see <link linkend="faq.size_equals_capacity">this FAQ
       entry</link>) but the regular copy constructor cannot be used
-      because libstdc++'s <code>string</code> is Copy-On-Write.
+      because libstdc++'s <code>string</code> is Copy-On-Write in GCC 3.
    </para>
    <para>In <link linkend="status.iso.2011">C++11</link> mode you can call
       <code>s.shrink_to_fit()</code> to achieve the same effect as

libstdc++-v3/doc/xml/manual/using.xml

@@ -875,6 +875,22 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe
     </para>
     </listitem></varlistentry>
 
+    <varlistentry><term><code>_GLIBCXX_USE_CXX11_ABI</code></term>
+    <listitem>
+      <para>
+        Defined to the value <literal>1</literal> by default.
+        Configurable via  <code>--disable-libstdcxx-dual-abi</code>
+        and/or <code>--with-default-libstdcxx-abi</code>.
+        ABI-changing.
+        When defined to a non-zero value the library headers will use the
+        new C++11-conforming ABI introduced in GCC 5, rather than the older
+        ABI introduced in GCC 3.4. This changes the definition of several
+        class templates, including <classname>std:string</classname>,
+        <classname>std::list</classname> and some locale facets.
+        For more details see <xref linkend="manual.intro.using.abi"/>.
+    </para>
+    </listitem></varlistentry>
+
     <varlistentry><term><code>_GLIBCXX_CONCEPT_CHECKS</code></term>
     <listitem>
       <para>
@@ -922,6 +938,94 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe
 
   </section>
 
+<section xml:id="manual.intro.using.abi" xreflabel="Dual ABI">
+  <info><title>Dual ABI</title></info>
+  <?dbhtml filename="using_dual_abi.html"?>
+
+<para> In the GCC 5.1 release libstdc++ introduced a new library ABI that
+  includes new implementations of <classname>std::string</classname> and
+  <classname>std::list</classname>. These changes were necessary to conform
+  to the 2011 C++ standard which forbids Copy-On-Write strings and requires
+  lists to keep track of their size.
+</para>
+
+<para> In order to maintain backwards compatibility for existing code linked
+  to libstdc++ the library's soname has not changed and the old
+  implementations are still supported in parallel with the new ones.
+  This is achieved by defining the new implementations in an inline namespace
+  so they have different names for linkage purposes, e.g. the new version of
+  <classname>std::list&lt;int&gt;</classname> is actually defined as
+  <classname>std::__cxx11::list&lt;int&gt;</classname>. Because the symbols
+  for the new implementations have different names the definitions for both
+  versions can be present in the same library.
+</para>
+
+<para> The <symbol>_GLIBCXX_USE_CXX11_ABI</symbol> macro (see
+<xref linkend="manual.intro.using.macros"/>) controls whether
+  the declarations in the library headers use the old or new ABI.
+  So the decision of which ABI to use can be made separately for each
+  source file being compiled.
+  Using the default configuration options for GCC the default value
+  of the macro is <literal>1</literal> which causes the new ABI to be active,
+  so to use the old ABI you must explicitly define the macro to
+  <literal>0</literal> before including any library headers.
+  (Be aware that some GNU/Linux distributions configure GCC 5 differently so
+  that the default value of the macro is <literal>0</literal> and users must
+  define it to <literal>1</literal> to enable the new ABI.)
+</para>
+
+<para> Although the changes were made for C++11 conformance, the choice of ABI
+  to use is independent of the <option>-std</option> option used to compile
+  your code, i.e. for a given GCC build the default value of the
+  <symbol>_GLIBCXX_USE_CXX11_ABI</symbol> macro is the same for all dialects.
+  This ensures that the <option>-std</option> does not change the ABI, so
+  that it is straightforward to link C++03 and C++11 code together.
+</para>
+
+<para> Because <classname>std::string</classname> is used extensively
+  throughout the library a number of other types are also defined twice,
+  including the stringstream classes and several facets used by
+  <classname>std::locale</classname>. The standard facets which are always
+  installed in a locale may be present twice, with both ABIs, to ensure that
+  code like
+  <code>std::use_facet&lt;std::time_get&lt;char&gt;&gt;(locale);</code>
+  will work correctly for both <classname>std::time_get</classname> and
+  <classname>std::__cxx11::time_get</classname> (even if a user-defined
+  facet that derives from one or other version of
+  <classname>time_get</classname> is installed in the locale).
+</para>
+
+<para> Although the standard exception types defined in
+  <filename clas="headerfile">&lt;stdexcept&gt;</filename> use strings, they
+  are not defined twice, so that a <classname>std::out_of_range</classname>
+  exception thrown in one file can always be caught by a suitable handler in
+  another file, even if the two files are compiled with different ABIs.
+</para>
+
+<section xml:id="manual.intro.using.abi.trouble" xreflabel="Dual ABI Troubleshooting"><info><title>Troubleshooting</title></info>
+
+<para> If you get linker errors about undefined references to symbols
+  that involve types in the <code>std::__cxx11</code> namespace or the tag
+  <code>[abi:cxx11]</code> then it probably indicates that you are trying to
+  link together object files that were compiled with different values for the
+  <symbol>_GLIBCXX_USE_CXX11_ABI</symbol> macro. This commonly happens when
+  linking to a third-party library that was compiled with an older version
+  of GCC. If the third-party library cannot be rebuilt with the new ABI then
+  you will need to recompile your code with the old ABI.
+</para>
+
+<para> Not all uses of the new ABI will cause changes in symbol names, for
+  example a class with a <classname>std::string</classname> member variable
+  will have the same mangled name whether compiled with the old or new ABI.
+  In order to detect such problems the new types and functions are
+  annotated with the <property>abi_tag</property> attribute, allowing the
+  compiler to warn about potential ABI incompatibilities in code using them.
+  Those warnings can be enabled with the <option>-Wabi-tag</option> option.
+</para>
+
+</section>
+</section>
+
   <section xml:id="manual.intro.using.namespaces" xreflabel="Namespaces"><info><title>Namespaces</title></info>
     <?dbhtml filename="using_namespaces.html"?>
     
@@ -956,6 +1060,11 @@ and <code>__gnu_pbds</code>.
 </para></listitem>
 </itemizedlist>
 
+<para> The library uses a number of inline namespaces as implementation
+details that are not intended for users to refer to directly, these include
+<code>std::__detail</code>, <code>std::__cxx11</code> and <code>std::_V2</code>.
+</para>
+
 <para> A complete list of implementation namespaces (including namespace contents) is available in the generated source <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/namespaces.html">documentation</link>.
 </para>