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| <?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>Configure</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, configure, options" /><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="setup.html" title="Chapter 2. Setup" /><link rel="prev" href="setup.html" title="Chapter 2. Setup" /><link rel="next" href="make.html" title="Make" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Configure</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="setup.html">Prev</a> </td><th width="60%" align="center">Chapter 2. Setup</th><td width="20%" align="right"> <a accesskey="n" href="make.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.setup.configure"></a>Configure</h2></div></div></div><p>
 | ||
|   When configuring libstdc++, you'll have to configure the entire
 | ||
|   <span class="emphasis"><em>gccsrcdir</em></span> directory. Consider using the
 | ||
|   toplevel gcc configuration option
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|   <code class="literal">--enable-languages=c++</code>, which saves time by only
 | ||
|   building the C++ toolchain.
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| </p><p>
 | ||
|   Here are all of the configure options specific to libstdc++.  Keep
 | ||
|   in mind that
 | ||
|    
 | ||
|    <a class="link" href="http://sourceware.org/autobook/autobook/autobook_14.html" target="_top">they
 | ||
|    all have opposite forms as well</a> (enable/disable and
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|    with/without).  The defaults are for the <span class="emphasis"><em>current
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|    development sources</em></span>, which may be different than those
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|    for released versions.
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| </p><p>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: <span class="command"><strong>./configure --help</strong></span>.
 | ||
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">--enable-multilib</code>[default]</span></dt><dd><p>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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|      </p></dd><dt><span class="term"><code class="code">--enable-version-specific-runtime-libs</code></span></dt><dd><p>Specify that run-time libraries should be installed in the
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| 	compiler-specific subdirectory (i.e.,
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| 	<code class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>)
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| 	instead of <code class="code">${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 class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>,
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| 	unless you also specify
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|        <code class="literal">--with-gxx-include-dir=</code><code class="filename">dirname</code> during configuration.
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|      </p></dd><dt><span class="term"><code class="code">--with-gxx-include-dir=<include-files dir></code></span></dt><dd><p>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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|      </p><pre class="programlisting">
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|    --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/4.4-20090404</pre></dd><dt><span class="term"><code class="code">--enable-cstdio</code></span></dt><dd><p>This is an abbreviated form of <code class="code">'--enable-cstdio=stdio'</code>
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| 	(described next).
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|      </p></dd><dt><span class="term"><code class="code">--enable-cstdio=OPTION</code></span></dt><dd><p>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.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-clocale</code></span></dt><dd><p>This is an abbreviated form of <code class="code">'--enable-clocale=generic'</code>
 | ||
| 	(described next).
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|      </p></dd><dt><span class="term"><code class="code">--enable-clocale=OPTION</code></span></dt><dd><p>Select a target-specific underlying locale package.  The
 | ||
| 	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 <a class="link" href="https://www.gnu.org/software/libc/" target="_top">glibc</a>, 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 <span class="type">wchar_t</span> specializations
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| 	needed by the 'generic' model.
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|      </p><p>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 class="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.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-allocator</code></span></dt><dd><p>This is an abbreviated form of
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| 	<code class="code">'--enable-libstdcxx-allocator=auto'</code> (described
 | ||
| 	next).
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-allocator=OPTION  </code></span></dt><dd><p>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.
 | ||
| 	See this page for more information on allocator
 | ||
| 	<a class="link" href="memory.html#allocator.ext" title="Extension Allocators">extensions</a>. This option
 | ||
| 	can change the library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-cheaders=OPTION</code></span></dt><dd><p>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'.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-threads</code></span></dt><dd><p>This is an abbreviated form of <code class="code">'--enable-threads=yes'</code>
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| 	(described next).
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-threads=OPTION</code></span></dt><dd><p>Select a threading library.  A full description is
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| 	given in the
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| 	general <a class="link" href="http://gcc.gnu.org/install/configure.html" target="_top">compiler
 | ||
| 	configuration instructions</a>. This option can change the
 | ||
| 	library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-threads</code></span></dt><dd><p>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.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-time</code></span></dt><dd><p>This is an abbreviated form of
 | ||
| 	<code class="code">'--enable-libstdcxx-time=yes'</code>(described next).
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-time=OPTION</code></span></dt><dd><p>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
 | ||
| 	desirable because, in glibc, for example, in turn it triggers the
 | ||
| 	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.
 | ||
|     </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-debug</code></span></dt><dd><p>Build separate debug libraries in addition to what is normally built.
 | ||
| 	By default, the debug libraries are compiled with
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| 	<code class="code"> CXXFLAGS='-g3 -O0 -fno-inline'</code>
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| 	, are installed in <code class="code">${libdir}/debug</code>, and have the
 | ||
| 	same names and versioning information as the non-debug
 | ||
| 	libraries. This option is off by default.
 | ||
|      </p><p>Note this make command, executed in
 | ||
| 	the build directory, will do much the same thing, without the
 | ||
| 	configuration difference and without building everything twice:
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| 	<code class="code">make CXXFLAGS='-g3 -O0 -fno-inline' all</code>
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-debug-flags=FLAGS</code></span></dt><dd><p>This option is only valid when <code class="code"> --enable-debug </code>
 | ||
| 	is also specified, and applies to the debug builds only. With
 | ||
| 	this option, you can pass a specific string of flags to the
 | ||
| 	compiler to use when building the debug versions of libstdc++.
 | ||
| 	FLAGS is a quoted string of options, like
 | ||
|      </p><pre class="programlisting">
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|   --enable-libstdcxx-debug-flags='-g3 -O1 -fno-inline'</pre></dd><dt><span class="term"><code class="code">--enable-cxx-flags=FLAGS</code></span></dt><dd><p>With this option, you can pass a string of -f (functionality)
 | ||
| 	flags to the compiler to use when building libstdc++. This
 | ||
| 	option can change the library ABI. FLAGS is a quoted string of
 | ||
| 	options, like
 | ||
|      </p><pre class="programlisting">
 | ||
|   --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</pre><p>
 | ||
| 	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
 | ||
| 	for experimentation and configure-time overriding.
 | ||
|      </p><p>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.
 | ||
|      </p><p>Fun flags to try might include combinations of
 | ||
|      </p><pre class="programlisting">
 | ||
|   -fstrict-aliasing
 | ||
|   -fno-exceptions
 | ||
|   -ffunction-sections
 | ||
|   -fvtable-gc</pre><p>and opposite forms (-fno-) of the same.  Tell us (the libstdc++
 | ||
| 	mailing list) if you discover more!
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-c99</code></span></dt><dd><p>The <span class="type">long long</span> type was introduced in C99, along
 | ||
| 	with many other functions for wide characters, and math
 | ||
| 	classification macros, etc.  If enabled, all C99 functions not
 | ||
| 	specified by the C++ standard will be put into <code class="code">namespace
 | ||
| 	__gnu_cxx</code>, and then all these names will
 | ||
| 	be injected into namespace std, so that C99 functions can be
 | ||
| 	used "as if" they were in the C++ standard (as they
 | ||
| 	will eventually be in some future revision of the standard,
 | ||
| 	without a doubt).  By default, C99 support is on, assuming the
 | ||
| 	configure probes find all the necessary functions and bits
 | ||
| 	necessary. This option can change the library ABI.
 | ||
|     </p></dd><dt><span class="term"><code class="code">--enable-wchar_t</code>[default]</span></dt><dd><p>Template specializations for the <span class="type">wchar_t</span> type are
 | ||
| 	required for wide character conversion support.  Disabling
 | ||
| 	wide character specializations may be expedient for initial
 | ||
| 	porting efforts, but builds only a subset of what is required by
 | ||
| 	ISO, and is not recommended.  By default, this option is on.
 | ||
| 	This option can change the library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-long-long  </code></span></dt><dd><p>The <span class="type">long long</span> type was introduced in C99.  It is
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| 	provided as a GNU extension to C++98 in g++.  This flag builds
 | ||
| 	support for "long long" into the library (specialized
 | ||
| 	templates and the like for iostreams).  This option is on by default:
 | ||
| 	if enabled, users will have to either use the new-style "C"
 | ||
| 	headers by default (i.e., <cmath> not <math.h>)
 | ||
| 	or add appropriate compile-time flags to all compile lines to
 | ||
| 	allow "C" visibility of this feature (on GNU/Linux,
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| 	the flag is -D_ISOC99_SOURCE, which is added automatically via
 | ||
| 	CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE).
 | ||
| 	This option can change the library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-fully-dynamic-string</code></span></dt><dd><p>This option enables a special version of basic_string avoiding
 | ||
| 	the optimization that allocates empty objects in static memory.
 | ||
| 	Mostly useful together with shared memory allocators, see PR
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| 	libstdc++/16612 for details.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-concept-checks</code></span></dt><dd><p>This turns on additional compile-time checks for instantiated
 | ||
| 	library templates, in the form of specialized templates described in
 | ||
|         the <a class="link" href="concept_checking.html" title="Concept Checking">Concept
 | ||
|         Checking</a> section.  They
 | ||
| 	can help users discover when they break the rules of the STL, before
 | ||
| 	their programs run. These checks are based on C++03 rules and some of
 | ||
| 	them are not compatible with correct C++11 code.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-symvers[=style]</code></span></dt><dd><p>In 3.1 and later, tries to turn on symbol versioning in the
 | ||
| 	shared library (if a shared library has been
 | ||
| 	requested). Values for 'style' that are currently supported
 | ||
| 	are 'gnu', 'gnu-versioned-namespace', 'darwin',
 | ||
| 	'darwin-export', and 'sun'. Both gnu- options require that a recent
 | ||
| 	version of the GNU linker be in use. Both darwin options are
 | ||
| 	equivalent. With no style given, the configure script will try
 | ||
| 	to guess correct defaults for the host system, probe to see if
 | ||
| 	additional requirements are necessary and present for
 | ||
| 	activation, and if so, will turn symbol versioning on. This
 | ||
| 	option can change the library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-visibility</code></span></dt><dd><p> In 4.2 and later, enables or disables visibility 
 | ||
|         attributes. If enabled (as by default), and the compiler seems
 | ||
|         capable of passing the simple sanity checks thrown at it, adjusts
 | ||
|         items in namespace std, namespace std::tr1, namespace std::tr2,
 | ||
|         and namespace __gnu_cxx to have <code class="code">visibility ("default")</code>
 | ||
|         so that -fvisibility options can be used without affecting the
 | ||
|         normal external-visibility of namespace std entities.
 | ||
|         Prior to 4.7 this option was spelled <code class="code">--enable-visibility</code>.
 | ||
|     </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-pch</code></span></dt><dd><p>In 3.4 and later, tries to turn on the generation of
 | ||
| 	stdc++.h.gch, a pre-compiled file including all the standard
 | ||
| 	C++ includes. If enabled (as by default), and the compiler
 | ||
| 	seems capable of passing the simple sanity checks thrown at
 | ||
| 	it, try to build stdc++.h.gch as part of the make process.
 | ||
| 	In addition, this generated file is used later on (by appending <code class="code">
 | ||
| 	--include bits/stdc++.h </code> to CXXFLAGS) when running the
 | ||
| 	testsuite.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-extern-template</code>[default]</span></dt><dd><p>Use extern template to pre-instantiate all required
 | ||
|  	specializations for certain types defined in the standard libraries. 
 | ||
| 	These types include <code class="classname">string</code> and dependents like
 | ||
| 	<code class="classname">char_traits</code>, the templatized IO classes,
 | ||
| 	<code class="classname">allocator</code>, and others.  
 | ||
| 	Disabling means that implicit
 | ||
| 	template generation will be used when compiling these types.  By
 | ||
| 	default, this option is on. This option can change the library ABI.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--disable-hosted-libstdcxx</code></span></dt><dd><p>
 | ||
|      By default, a complete <span class="emphasis"><em>hosted</em></span> C++ library is
 | ||
|      built.  The C++ Standard also describes a
 | ||
|      <span class="emphasis"><em>freestanding</em></span> environment, in which only a
 | ||
|      minimal set of headers are provided.  This option builds such an
 | ||
|      environment.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--disable-libstdcxx-verbose</code></span></dt><dd><p>
 | ||
|      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.
 | ||
|    </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 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=new</code> which sets the macro to
 | ||
|      <code class="literal">1</code>,
 | ||
|      use <code class="option">OPTION=gcc4-compatible</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
 | ||
|     functions in the standard library will be verified at runtime.
 | ||
|     Types impacted include <code class="classname">locale</code> and
 | ||
|     <code class="classname">iostream</code>, and others.  Disabling means that
 | ||
|     the C++ runtime is compiled without support for vtable
 | ||
|     verification. By default, this option is off.
 | ||
|      </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-filesystem-ts</code>[default]</span></dt><dd><p>Build <code class="filename">libstdc++fs.a</code> 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.
 | ||
|     </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="setup.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="setup.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="make.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 2. Setup </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Make</td></tr></table></div></body></html> |