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			426 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			XML
		
	
	
	
			
		
		
	
	
			426 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			XML
		
	
	
	
<section xmlns="http://docbook.org/ns/docbook" version="5.0" 
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	 xml:id="manual.intro.setup.configure" xreflabel="Configuring">
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<?dbhtml filename="configure.html"?>
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<info><title>Configure</title>
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  <keywordset>
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    <keyword>ISO C++</keyword>
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    <keyword>configure</keyword>
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    <keyword>options</keyword>
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  </keywordset>
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</info>
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<para>
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  When configuring libstdc++, you'll have to configure the entire
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  <emphasis>gccsrcdir</emphasis> directory. Consider using the
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  toplevel gcc configuration option
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  <literal>--enable-languages=c++</literal>, which saves time by only
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  building the C++ toolchain.
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</para>
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<para>
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  Here are all of the configure options specific to libstdc++.  Keep
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  in mind that
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   <!-- This SECnn should be the "Choosing Package Options" section. -->
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   <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://sourceware.org/autobook/autobook/autobook_14.html">they
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   all have opposite forms as well</link> (enable/disable and
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   with/without).  The defaults are for the <emphasis>current
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   development sources</emphasis>, which may be different than those
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   for released versions.
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</para>
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<para>The canonical way to find out the configure options that are
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   available for a given set of libstdc++ sources is to go to the
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   source directory and then type: <command>./configure --help</command>.
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</para>
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<variablelist>
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 <varlistentry><term><code>--enable-multilib</code>[default]</term>
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 <listitem><para>This is part of the generic multilib support for building cross
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	compilers.  As such, targets like "powerpc-elf" will have
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	libstdc++ built many different ways:  "-msoft-float"
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	and not, etc.  A different libstdc++ will be built for each of
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	the different multilib versions.  This option is on by default.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-version-specific-runtime-libs</code></term>
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 <listitem><para>Specify that run-time libraries should be installed in the
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	compiler-specific subdirectory (i.e.,
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	<code>${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>)
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	instead of <code>${libdir}</code>.  This option is useful if you
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	intend to use several versions of gcc in parallel.  In addition,
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	libstdc++'s include files will be installed in
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	<code>${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>,
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	unless you also specify
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       <literal>--with-gxx-include-dir=</literal><filename class="directory">dirname</filename> during configuration.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--with-gxx-include-dir=<include-files dir></code></term>
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 <listitem><para>Adds support for named libstdc++ include directory.  For instance,
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	the following puts all the libstdc++ headers into a directory
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	called "4.4-20090404" instead of the usual
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	"c++/(version)".
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     </para>
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	<programlisting>
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   --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/4.4-20090404</programlisting> </listitem></varlistentry>
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 <varlistentry><term><code>--enable-cstdio</code></term>
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 <listitem><para>This is an abbreviated form of <code>'--enable-cstdio=stdio'</code>
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	(described next).
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-cstdio=OPTION</code></term>
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 <listitem><para>Select a target-specific I/O package. At the moment, the only
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	choice is to use 'stdio', a generic "C" abstraction.
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	The default is 'stdio'. This option can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-clocale</code></term>
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 <listitem><para>This is an abbreviated form of <code>'--enable-clocale=generic'</code>
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	(described next).
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-clocale=OPTION</code></term>
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 <listitem><para>Select a target-specific underlying locale package.  The
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	choices are 'ieee_1003.1-2001' to specify an X/Open, Standard Unix
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	(IEEE Std. 1003.1-2001) model based on langinfo/iconv/catgets,
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	'gnu' to specify a model based on functionality from the GNU C
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	library (langinfo/iconv/gettext) (from <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.gnu.org/software/libc/">glibc</link>, the GNU C
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	library), 'generic' to use a generic "C" abstraction which consists
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	of "C" locale info, 'newlib' to specify the Newlib C library model
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	which only differs from the 'generic' model in the handling of
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	ctype, or 'darwin' which omits the <type>wchar_t</type> specializations
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	needed by the 'generic' model.
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     </para>
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     <para>If not explicitly specified, the configure process tries
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      to guess the most suitable package from the choices above. The
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      default is 'generic'. On glibc-based systems of sufficient
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      vintage (2.3 and newer), 'gnu' is automatically selected. On newlib-based
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      systems (<code>'--with_newlib=yes'</code>) and OpenBSD, 'newlib' is
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      automatically selected. On Mac OS X 'darwin' is automatically selected.
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      This option can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-allocator</code></term>
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 <listitem><para>This is an abbreviated form of
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	<code>'--enable-libstdcxx-allocator=auto'</code> (described
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	next).
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-allocator=OPTION  </code></term>
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 <listitem><para>Select a target-specific underlying std::allocator.  The
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	choices are 'new' to specify a wrapper for new, 'malloc' to
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	specify a wrapper for malloc, 'mt' for a fixed power of two allocator,
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	'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator.
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	See this page for more information on allocator
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	<link linkend="allocator.ext">extensions</link>. This option
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	can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-cheaders=OPTION</code></term>
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 <listitem><para>This allows the user to define the approach taken for C header
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	compatibility with C++. Options are c, c_std, and c_global.
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	These correspond to the source directory's include/c,
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	include/c_std, and include/c_global, and may also include
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	include/c_compatibility.  The default is 'c_global'.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-threads</code></term>
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 <listitem><para>This is an abbreviated form of <code>'--enable-threads=yes'</code>
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	(described next).
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-threads=OPTION</code></term>
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 <listitem><para>Select a threading library.  A full description is
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	given in the
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	general <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://gcc.gnu.org/install/configure.html">compiler
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	configuration instructions</link>. This option can change the
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	library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-threads</code></term>
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 <listitem><para>Enable C++11 threads support.  If not explicitly specified,
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        the  configure process enables it if possible.  This
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	option can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-time</code></term>
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 <listitem><para>This is an abbreviated form of
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	<code>'--enable-libstdcxx-time=yes'</code>(described next).
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-time=OPTION</code></term>
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 <listitem><para>Enables link-type checks for the availability of the
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	clock_gettime clocks, used in the implementation of [time.clock],
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	and of the nanosleep and sched_yield functions, used in the
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	implementation of [thread.thread.this] of the 2011 ISO C++ standard.
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	The choice OPTION=yes checks for the availability of the facilities
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	in libc and libposix4.  In case it's needed the latter is also linked
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	to libstdc++ as part of the build process.  OPTION=rt also searches
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	(and, if needed, links) librt.   Note that the latter is not always
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	desirable because, in glibc, for example, in turn it triggers the
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	linking of libpthread too, which activates locking, a large overhead
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	for single-thread programs.  OPTION=no skips the tests completely.
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	The default is OPTION=auto, which skips the checks and enables the
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	features only for targets known to support them.
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    </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-debug</code></term>
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 <listitem><para>Build separate debug libraries in addition to what is normally built.
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	By default, the debug libraries are compiled with
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	<code> CXXFLAGS='-g3 -O0 -fno-inline'</code>
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	, are installed in <code>${libdir}/debug</code>, and have the
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	same names and versioning information as the non-debug
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	libraries. This option is off by default.
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     </para>
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     <para>Note this make command, executed in
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	the build directory, will do much the same thing, without the
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	configuration difference and without building everything twice:
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	<code>make CXXFLAGS='-g3 -O0 -fno-inline' all</code>
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-libstdcxx-debug-flags=FLAGS</code></term>
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 <listitem><para>This option is only valid when <code> --enable-debug </code>
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	is also specified, and applies to the debug builds only. With
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	this option, you can pass a specific string of flags to the
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	compiler to use when building the debug versions of libstdc++.
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	FLAGS is a quoted string of options, like
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     </para>
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	<programlisting>
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  --enable-libstdcxx-debug-flags='-g3 -O1 -fno-inline'</programlisting>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-cxx-flags=FLAGS</code></term>
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 <listitem><para>With this option, you can pass a string of -f (functionality)
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	flags to the compiler to use when building libstdc++. This
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	option can change the library ABI. FLAGS is a quoted string of
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	options, like
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     </para>
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	<programlisting>
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  --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</programlisting>
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     <para>
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	Note that the flags don't necessarily have to all be -f flags,
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	as shown, but usually those are the ones that will make sense
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	for experimentation and configure-time overriding.
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     </para>
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     <para>The advantage of --enable-cxx-flags over setting CXXFLAGS in
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	the 'make' environment is that, if files are automatically
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	rebuilt, the same flags will be used when compiling those files
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	as well, so that everything matches.
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     </para>
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     <para>Fun flags to try might include combinations of
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     </para>
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	<programlisting>
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  -fstrict-aliasing
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  -fno-exceptions
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  -ffunction-sections
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  -fvtable-gc</programlisting>
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     <para>and opposite forms (-fno-) of the same.  Tell us (the libstdc++
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	mailing list) if you discover more!
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-c99</code></term>
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 <listitem><para>The <type>long long</type> type was introduced in C99, along
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	with many other functions for wide characters, and math
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	classification macros, etc.  If enabled, all C99 functions not
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	specified by the C++ standard will be put into <code>namespace
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	__gnu_cxx</code>, and then all these names will
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	be injected into namespace std, so that C99 functions can be
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	used "as if" they were in the C++ standard (as they
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	will eventually be in some future revision of the standard,
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	without a doubt).  By default, C99 support is on, assuming the
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	configure probes find all the necessary functions and bits
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	necessary. This option can change the library ABI.
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    </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-wchar_t</code>[default]</term>
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 <listitem><para>Template specializations for the <type>wchar_t</type> type are
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	required for wide character conversion support.  Disabling
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	wide character specializations may be expedient for initial
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	porting efforts, but builds only a subset of what is required by
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	ISO, and is not recommended.  By default, this option is on.
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	This option can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-long-long  </code></term>
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 <listitem><para>The <type>long long</type> type was introduced in C99.  It is
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	provided as a GNU extension to C++98 in g++.  This flag builds
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	support for "long long" into the library (specialized
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	templates and the like for iostreams).  This option is on by default:
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	if enabled, users will have to either use the new-style "C"
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	headers by default (i.e., <cmath> not <math.h>)
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	or add appropriate compile-time flags to all compile lines to
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	allow "C" visibility of this feature (on GNU/Linux,
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	the flag is -D_ISOC99_SOURCE, which is added automatically via
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	CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE).
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	This option can change the library ABI.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-fully-dynamic-string</code></term>
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 <listitem><para>This option enables a special version of basic_string avoiding
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	the optimization that allocates empty objects in static memory.
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	Mostly useful together with shared memory allocators, see PR
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	libstdc++/16612 for details.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-concept-checks</code></term>
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 <listitem><para>This turns on additional compile-time checks for instantiated
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	library templates, in the form of specialized templates described in
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        the <link linkend="std.diagnostics.concept_checking">Concept
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        Checking</link> section.  They
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	can help users discover when they break the rules of the STL, before
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	their programs run. These checks are based on C++03 rules and some of
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	them are not compatible with correct C++11 code.
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     </para>
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 </listitem></varlistentry>
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 <varlistentry><term><code>--enable-symvers[=style]</code></term>
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 <listitem><para>In 3.1 and later, tries to turn on symbol versioning in the
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	shared library (if a shared library has been
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	requested). Values for 'style' that are currently supported
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	are 'gnu', 'gnu-versioned-namespace', 'darwin',
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	'darwin-export', and 'sun'. Both gnu- options require that a recent
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	version of the GNU linker be in use. Both darwin options are
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	equivalent. With no style given, the configure script will try
 | 
						|
	to guess correct defaults for the host system, probe to see if
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	additional requirements are necessary and present for
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	activation, and if so, will turn symbol versioning on. This
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	option can change the library ABI.
 | 
						|
     </para>
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						|
 | 
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 </listitem></varlistentry>
 | 
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 <varlistentry><term><code>--enable-libstdcxx-visibility</code></term>
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 <listitem><para> In 4.2 and later, enables or disables visibility 
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        attributes. If enabled (as by default), and the compiler seems
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        capable of passing the simple sanity checks thrown at it, adjusts
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        items in namespace std, namespace std::tr1, namespace std::tr2,
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        and namespace __gnu_cxx to have <code>visibility ("default")</code>
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        so that -fvisibility options can be used without affecting the
 | 
						|
        normal external-visibility of namespace std entities.
 | 
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        Prior to 4.7 this option was spelled <code>--enable-visibility</code>.
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						|
    </para>
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						|
 </listitem></varlistentry>
 | 
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 | 
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 <varlistentry><term><code>--enable-libstdcxx-pch</code></term>
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						|
 <listitem><para>In 3.4 and later, tries to turn on the generation of
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	stdc++.h.gch, a pre-compiled file including all the standard
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	C++ includes. If enabled (as by default), and the compiler
 | 
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	seems capable of passing the simple sanity checks thrown at
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	it, try to build stdc++.h.gch as part of the make process.
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						|
	In addition, this generated file is used later on (by appending <code>
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	--include bits/stdc++.h </code> to CXXFLAGS) when running the
 | 
						|
	testsuite.
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						|
     </para>
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						|
 </listitem></varlistentry>
 | 
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 | 
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 | 
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 <varlistentry><term><code>--enable-extern-template</code>[default]</term>
 | 
						|
 <listitem><para>Use extern template to pre-instantiate all required
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 	specializations for certain types defined in the standard libraries. 
 | 
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	These types include <classname>string</classname> and dependents like
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	<classname>char_traits</classname>, the templatized IO classes,
 | 
						|
	<classname>allocator</classname>, and others.  
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	Disabling means that implicit
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	template generation will be used when compiling these types.  By
 | 
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	default, this option is on. This option can change the library ABI.
 | 
						|
     </para>
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						|
 </listitem></varlistentry>
 | 
						|
 | 
						|
 <varlistentry><term><code>--disable-hosted-libstdcxx</code></term>
 | 
						|
 <listitem>
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						|
   <para>
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						|
     By default, a complete <emphasis>hosted</emphasis> C++ library is
 | 
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     built.  The C++ Standard also describes a
 | 
						|
     <emphasis>freestanding</emphasis> environment, in which only a
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						|
     minimal set of headers are provided.  This option builds such an
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						|
     environment.
 | 
						|
     </para>
 | 
						|
 </listitem></varlistentry>
 | 
						|
 | 
						|
<varlistentry><term><code>--disable-libstdcxx-verbose</code></term>
 | 
						|
 <listitem>
 | 
						|
   <para>
 | 
						|
     By default, the library is configured to write descriptive messages
 | 
						|
     to standard error for certain events such as calling a pure virtual
 | 
						|
     function or the invocation of the standard terminate handler.  Those
 | 
						|
     messages cause the library to depend on the demangler and standard I/O
 | 
						|
     facilities, which might be undesirable in a low-memory environment or
 | 
						|
     when standard error is not available.  This option disables those
 | 
						|
     messages.  This option does not change the library ABI.
 | 
						|
   </para>
 | 
						|
 </listitem></varlistentry>
 | 
						|
 | 
						|
<varlistentry><term><code>--disable-libstdcxx-dual-abi</code></term>
 | 
						|
 <listitem>
 | 
						|
   <para>
 | 
						|
     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><replaceable>OPTION</replaceable></term>
 | 
						|
 <listitem>
 | 
						|
   <para>
 | 
						|
     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=new</option> which sets the macro to
 | 
						|
     <literal>1</literal>,
 | 
						|
     use <option>OPTION=gcc4-compatible</option> to set it to
 | 
						|
     <literal>0</literal>.
 | 
						|
     This option does not change the library ABI.
 | 
						|
   </para>
 | 
						|
 </listitem></varlistentry>
 | 
						|
 | 
						|
 <varlistentry><term><code>--enable-vtable-verify</code>[default]</term>
 | 
						|
 <listitem>
 | 
						|
    <para>Use <code>-fvtable-verify=std</code> to compile the C++
 | 
						|
    runtime with instrumentation for vtable verification. All virtual
 | 
						|
    functions in the standard library will be verified at runtime.
 | 
						|
    Types impacted include <classname>locale</classname> and
 | 
						|
    <classname>iostream</classname>, and others.  Disabling means that
 | 
						|
    the C++ runtime is compiled without support for vtable
 | 
						|
    verification. By default, this option is off.
 | 
						|
     </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>
 |