[patch] Document options for building and linking to libstdc++fs.a

[Jonathan Wakely <jwakely at redhat dot com>]

This documents how to use the Filsystem TS library.

Committed to trunk.


commit 2d8dfef4311b51a2743f5ab722d467792c7c32dd
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Oct 16 14:53:46 2015 +0100

    Document options for Filesystem TS library
    
    	* doc/xml/manual/configure.xml: Document
    	--enable-libstdcxx-filesystem-ts option.
    	* doc/xml/manual/status_cxx2014.xml: Document libstdc++fs.a.
    	* doc/xml/manual/using.xml: Likewise.
    	* doc/html/*: Regenerate.

diff --git a/libstdc++-v3/doc/xml/manual/configure.xml b/libstdc++-v3/doc/xml/manual/configure.xml
index 2f558d2..ac383cf 100644
--- a/libstdc++-v3/doc/xml/manual/configure.xml
+++ b/libstdc++-v3/doc/xml/manual/configure.xml
@@ -411,6 +411,15 @@
      </para>
  </listitem></varlistentry>
 
+ <varlistentry><term><code>--enable-libstdcxx-filesystem-ts</code>[default]</term>
+ <listitem>
+    <para>Build <filename class="libraryfile">libstdc++fs.a</filename> as well
+      as the usual libstdc++ and libsupc++ libraries. This is enabled by
+      default on select POSIX targets where it is known to work and disabled
+      otherwise.
+    </para>
+ </listitem></varlistentry>
+
 </variablelist>
 
 </section>
diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2014.xml b/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
index d022ea4..6f1fbe5 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2014.xml
@@ -402,7 +402,11 @@ not in any particular release.
       </entry>
       <entry>File System</entry>
       <entry>Y</entry>
-      <entry></entry>
+      <entry>
+	Link with
+	<link linkend="manual.intro.using.linkage.experimental">
+	<option>-lstdc++fs</option></link>
+      </entry>
     </row>
 
 
diff --git a/libstdc++-v3/doc/xml/manual/using.xml b/libstdc++-v3/doc/xml/manual/using.xml
index 2c8d179..96ae686 100644
--- a/libstdc++-v3/doc/xml/manual/using.xml
+++ b/libstdc++-v3/doc/xml/manual/using.xml
@@ -96,6 +96,14 @@
     </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>-fopenmp</literal></entry>
       <entry>For <link linkend="manual.ext.parallel_mode">parallel</link> mode.</entry>
     </row>
@@ -1361,8 +1369,31 @@ A quick read of the relevant part of the GCC
       you.
     </para>
     </section>
-  </section>
 
+    <section xml:id="manual.intro.using.linkage.experimental" xreflabel="Library Extensions"><info><title>Experimental Library Extensions</title></info>
+
+    <para>
+      GCC 5.3 includes an implementation of the Filesystem library defined
+      by the technical specification ISO/IEC TS 18822:2015. Because this is
+      an experimental library extension, not part of the C++ standard, it
+      is implemented in a separate library,
+      <filename class="libraryfile">libstdc++fs.a</filename>, and there is
+      no shared library for it. To use the library you should include
+      <filename class="headerfile">&lt;experimental/filesystem&gt;</filename>
+      and link with <option>-lstdc++fs</option>. The library implementation
+      is incomplete on non-POSIX platforms, specifically Windows support is
+      rudimentary.
+    </para>
+
+    <para>
+      Due to the experimental nature of the Filesystem library the usual
+      guarantees about ABI stability and backwards compatibility do not apply
+      to it. There is no guarantee that the components in any
+      <filename class="headerfile">&lt;experimental/xxx&gt;</filename>
+      header will remain compatible between different GCC releases.
+    </para>
+    </section>
+  </section>
 
   <section xml:id="manual.intro.using.concurrency" xreflabel="Concurrency"><info><title>Concurrency</title></info>
     <?dbhtml filename="using_concurrency.html"?>