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3 <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 Stylesheets V1.74.3" /><meta name="keywords" content=" ISO C++ , configure , options " /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><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="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.setup.configure"></a>Configure</h2></div></div></div><p>
4 When configuring libstdc++, you'll have to configure the entire
5 <span class="emphasis"><em>gccsrcdir</em></span> directory. Consider using the
6 toplevel gcc configuration option
7 <code class="literal">--enable-languages=c++</code>, which saves time by only
8 building the C++ toolchain.
10 Here are all of the configure options specific to libstdc++. Keep
13 <a class="ulink" href="http://sourceware.org/autobook/autobook/autobook_14.html" target="_top">they
14 all have opposite forms as well</a> (enable/disable and
15 with/without). The defaults are for the <span class="emphasis"><em>current
16 development sources</em></span>, which may be different than those
17 for released versions.
18 </p><p>The canonical way to find out the configure options that are
19 available for a given set of libstdc++ sources is to go to the
20 source directory and then type:<span class="command"><strong>./configure --help</strong></span>.
21 </p><div class="variablelist"><dl><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
22 compilers. As such, targets like "powerpc-elf" will have
23 libstdc++ built many different ways: "-msoft-float"
24 and not, etc. A different libstdc++ will be built for each of
25 the different multilib versions. This option is on by default.
26 </p></dd><dt><span class="term"><code class="code">--enable-sjlj-exceptions</code></span></dt><dd><p>Forces old, set-jump/long-jump exception handling model. If
27 at all possible, the new, frame unwinding exception handling routines
28 should be used instead, as they significantly reduce both
29 runtime memory usage and executable size. This option can
30 change the library ABI.
31 </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
32 compiler-specific subdirectory (i.e.,
33 <code class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>)
34 instead of <code class="code">${libdir}</code>. This option is useful if you
35 intend to use several versions of gcc in parallel. In addition,
36 libstdc++'s include files will be installed in
37 <code class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>,
38 unless you also specify
39 <code class="literal">--with-gxx-include-dir=<code class="filename">dirname</code></code> during configuration.
40 </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,
41 the following puts all the libstdc++ headers into a directory
42 called "4.4-20090404" instead of the usual
44 </p><pre class="programlisting">
45 --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>
47 </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
48 choice is to use 'stdio', a generic "C" abstraction.
49 The default is 'stdio'. This option can change the library ABI.
50 </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>
52 </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
53 choices are 'ieee_1003.1-2001' to specify an X/Open, Standard Unix
54 (IEEE Std. 1003.1-2001) model based on langinfo/iconv/catgets,
55 'gnu' to specify a model based on functionality from the GNU C
56 library (langinfo/iconv/gettext) (from <a class="ulink" href="http://sources.redhat.com/glibc/" target="_top">glibc</a>, the GNU C
57 library), or 'generic' to use a generic "C"
58 abstraction which consists of "C" locale info.
59 </p><p>If not explicitly specified, the configure proccess tries
60 to guess the most suitable package from the choices above. The
61 default is 'generic'. On glibc-based systems of sufficient
62 vintage (2.2.5 and newer) and capability (with installed DE and
63 FR locale data), 'gnu' is automatically selected. This option
64 can change the library ABI.
65 </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-allocator</code></span></dt><dd><p>This is an abbreviated form of
66 <code class="code">'--enable-libstdcxx-allocator=auto'</code> (described
68 </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
69 choices are 'new' to specify a wrapper for new, 'malloc' to
70 specify a wrapper for malloc, 'mt' for a fixed power of two allocator,
71 'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator.
72 See this page for more information on allocator
73 <a class="link" href="memory.html#allocator.ext" title="Extension Allocators">extensions</a>. This option
74 can change the library ABI.
75 </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
76 compatibility with C++. Options are c, c_std, and c_global.
77 These correspond to the source directory's include/c,
78 include/c_std, and include/c_global, and may also include
79 include/c_compatibility. The default is 'c_global'.
80 </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>
82 </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
84 general <a class="ulink" href="http://gcc.gnu.org/install/configure.html" target="_top">compiler
85 configuration instructions</a>. This option can change the
87 </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.
88 By default, the debug libraries are compiled with
89 <code class="code"> CXXFLAGS='-g3 -O0 -fno-inline'</code>
90 , are installed in <code class="code">${libdir}/debug</code>, and have the
91 same names and versioning information as the non-debug
92 libraries. This option is off by default.
93 </p><p>Note this make command, executed in
94 the build directory, will do much the same thing, without the
95 configuration difference and without building everything twice:
96 <code class="code">make CXXFLAGS='-g3 -O0 -fno-inline' all</code>
97 </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>
98 is also specified, and applies to the debug builds only. With
99 this option, you can pass a specific string of flags to the
100 compiler to use when building the debug versions of libstdc++.
101 FLAGS is a quoted string of options, like
102 </p><pre class="programlisting">
103 --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)
104 flags to the compiler to use when building libstdc++. This
105 option can change the library ABI. FLAGS is a quoted string of
107 </p><pre class="programlisting">
108 --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</pre><p>
109 Note that the flags don't necessarily have to all be -f flags,
110 as shown, but usually those are the ones that will make sense
111 for experimentation and configure-time overriding.
112 </p><p>The advantage of --enable-cxx-flags over setting CXXFLAGS in
113 the 'make' environment is that, if files are automatically
114 rebuilt, the same flags will be used when compiling those files
115 as well, so that everything matches.
116 </p><p>Fun flags to try might include combinations of
117 </p><pre class="programlisting">
121 -fvtable-gc</pre><p>and opposite forms (-fno-) of the same. Tell us (the libstdc++
122 mailing list) if you discover more!
123 </p></dd><dt><span class="term"><code class="code">--enable-c99</code></span></dt><dd><p>The "long long" type was introduced in C99, along
124 with many other functions for wide characters, and math
125 classification macros, etc. If enabled, all C99 functions not
126 specified by the C++ standard will be put into <code class="code">namespace
127 __gnu_cxx</code>, and then all these names will
128 be injected into namespace std, so that C99 functions can be
129 used "as if" they were in the C++ standard (as they
130 will eventually be in some future revision of the standard,
131 without a doubt). By default, C99 support is on, assuming the
132 configure probes find all the necessary functions and bits
133 necessary. This option can change the library ABI.
134 </p></dd><dt><span class="term"><code class="code">--enable-wchar_t</code>[default]</span></dt><dd><p>Template specializations for the "wchar_t" type are
135 required for wide character conversion support. Disabling
136 wide character specializations may be expedient for initial
137 porting efforts, but builds only a subset of what is required by
138 ISO, and is not recommended. By default, this option is on.
139 This option can change the library ABI.
140 </p></dd><dt><span class="term"><code class="code">--enable-long-long </code></span></dt><dd><p>The "long long" type was introduced in C99. It is
141 provided as a GNU extension to C++98 in g++. This flag builds
142 support for "long long" into the library (specialized
143 templates and the like for iostreams). This option is on by default:
144 if enabled, users will have to either use the new-style "C"
145 headers by default (i.e., <cmath> not <math.h>)
146 or add appropriate compile-time flags to all compile lines to
147 allow "C" visibility of this feature (on GNU/Linux,
148 the flag is -D_ISOC99_SOURCE, which is added automatically via
149 CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE).
150 This option can change the library ABI.
151 </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
152 the optimization that allocates empty objects in static memory.
153 Mostly useful together with shared memory allocators, see PR
154 libstdc++/16612 for details.
155 </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
156 library templates, in the form of specialized templates,
157 <a class="link" href="bk01pt03ch08.html" title="Chapter 8. Concept Checking">described here</a>. They
158 can help users discover when they break the rules of the STL, before
160 </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
161 shared library (if a shared library has been
162 requested). Values for 'style' that are currently supported
163 are 'gnu', 'gnu-versioned-namespace', 'darwin', and
164 'darwin-export'. Both gnu- options require that a recent
165 version of the GNU linker be in use. Both darwin options are
166 equivalent. With no style given, the configure script will try
167 to guess correct defaults for the host system, probe to see if
168 additional requirements are necessary and present for
169 activation, and if so, will turn symbol versioning on. This
170 option can change the library ABI.
171 </p></dd><dt><span class="term"><code class="code">--enable-visibility</code></span></dt><dd><p> In 4.2 and later, enables or disables visibility attributes.
172 If enabled (as by default), and the compiler seems capable of
173 passing the simple sanity checks thrown at it, adjusts items
174 in namespace std, namespace std::tr1, and namespace __gnu_cxx
175 so that -fvisibility options work.
176 </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
177 stdc++.h.gch, a pre-compiled file including all the standard
178 C++ includes. If enabled (as by default), and the compiler
179 seems capable of passing the simple sanity checks thrown at
180 it, try to build stdc++.h.gch as part of the make process.
181 In addition, this generated file is used later on (by appending <code class="code">
182 --include bits/stdc++.h </code> to CXXFLAGS) when running the
184 </p></dd><dt><span class="term"><code class="code">--disable-hosted-libstdcxx</code></span></dt><dd><p>
185 By default, a complete <span class="emphasis"><em>hosted</em></span> C++ library is
186 built. The C++ Standard also describes a
187 <span class="emphasis"><em>freestanding</em></span> environment, in which only a
188 minimal set of headers are provided. This option builds such an
190 </p></dd><dt><span class="term"><code class="code">--enable-clock-gettime</code></span></dt><dd><p>This is an abbreviated form of
191 <code class="code">'--enable-clock-gettime=yes'</code>(described next).
192 </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
193 clock_gettime clocks, used in the implementation of [time.clock],
194 and of the nanosleep and sched_yield functions, used in the
195 implementation of [thread.thread.this] of the current C++0x draft.
196 The choice OPTION=yes checks for the availability of the facilities
197 in libc and libposix4. In case of need the latter is also linked
198 to libstdc++ as part of the build process. OPTION=rt also searches
199 (and, in case, links) librt. Note that the latter is not always
200 desirable because, in glibc, for example, in turn it triggers the
201 linking of libpthread too, which activates locking, a large overhead
202 for single-thread programs. OPTION=no skips the tests completely.
203 The default is OPTION=no.
204 </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="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Make</td></tr></table></div></body></html>