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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 V1.74.0" /><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://www.gnu.org/software/autoconf/manual/autoconf-2.57/html_node/autoconf_131.html#SEC131" 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 "2.97-20001008" instead of the usual
44 </p><pre class="programlisting">
45 --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</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>
46 (described next). This option can change the library ABI.
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'.
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>
51 (described next). This option can change the library ABI.
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>As part of the configuration process, the "C" library is
60 probed both for sufficient vintage, and installed locale
61 data. If either of these elements are not present, the C++
62 locale model default to 'generic.' On glibc-based systems of
63 version 2.2.5 and above with installed locale files, 'gnu' is
64 automatically selected.
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
67 next). This option can change the library ABI.
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 This option can change the library ABI. See this page for more information on allocator
73 <a class="link" href="memory.html#allocator.ext" title="Extension Allocators">extensions</a>
74 </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
75 compatibility with C++. Options are c, c_std, and c_global.
76 These correspond to the source directory's include/c,
77 include/c_std, and include/c_global, and may also include
78 include/c_compatibility. The default is c_global.
79 </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>
80 (described next). This option can change the library ABI.
81 </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 given in the
82 general <a class="ulink" href="http://gcc.gnu.org/install/configure.html" target="_top">compiler
83 configuration instructions</a>.
84 </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.
85 By default, the debug libraries are compiled with
86 <code class="code"> CXXFLAGS='-g3 -O0 -fno-inline'</code>
87 , are installed in <code class="code">${libdir}/debug</code>, and have the
88 same names and versioning information as the non-debug
89 libraries. This option is off by default.
90 </p><p>Note this make command, executed in
91 the build directory, will do much the same thing, without the
92 configuration difference and without building everything twice:
93 <code class="code">make CXXFLAGS='-g3 -O0 -fno-inline' all</code>
94 </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>
95 is also specified, and applies to the debug builds only. With
96 this option, you can pass a specific string of flags to the
97 compiler to use when building the debug versions of libstdc++.
98 FLAGS is a quoted string of options, like
99 </p><pre class="programlisting">
100 --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)
101 flags to the compiler to use when building libstdc++. This
102 option can change the library ABI. FLAGS is a quoted string of
104 </p><pre class="programlisting">
105 --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</pre><p>
106 Note that the flags don't necessarily have to all be -f flags,
107 as shown, but usually those are the ones that will make sense
108 for experimentation and configure-time overriding.
109 </p><p>The advantage of --enable-cxx-flags over setting CXXFLAGS in
110 the 'make' environment is that, if files are automatically
111 rebuilt, the same flags will be used when compiling those files
112 as well, so that everything matches.
113 </p><p>Fun flags to try might include combinations of
114 </p><pre class="programlisting">
118 -fvtable-gc</pre><p>and opposite forms (-fno-) of the same. Tell us (the libstdc++
119 mailing list) if you discover more!
120 </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
121 with many other functions for wide characters, and math
122 classification macros, etc. If enabled, all C99 functions not
123 specified by the C++ standard will be put into <code class="code">namespace
124 __gnu_cxx</code>, and then all these names will
125 be injected into namespace std, so that C99 functions can be
126 used "as if" they were in the C++ standard (as they
127 will eventually be in some future revision of the standard,
128 without a doubt). By default, C99 support is on, assuming the
129 configure probes find all the necessary functions and bits
130 necessary. This option can change the library ABI.
131 </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
132 required for wide character conversion support. Disabling
133 wide character specializations may be expedient for initial
134 porting efforts, but builds only a subset of what is required by
135 ISO, and is not recommended. By default, this option is on.
136 This option can change the library ABI.
137 </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
138 provided as a GNU extension to C++98 in g++. This flag builds
139 support for "long long" into the library (specialized
140 templates and the like for iostreams). This option is on by default:
141 if enabled, users will have to either use the new-style "C"
142 headers by default (i.e., <cmath> not <math.h>)
143 or add appropriate compile-time flags to all compile lines to
144 allow "C" visibility of this feature (on GNU/Linux,
145 the flag is -D_ISOC99_SOURCE, which is added automatically via
146 CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE).
147 This option can change the library ABI.
148 </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
149 the optimization that allocates empty objects in static memory.
150 Mostly useful together with shared memory allocators, see PR
151 libstdc++/16612 for details.
152 </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
153 library templates, in the form of specialized templates,
154 <a class="link" href="bk01pt03ch08.html" title="Chapter 8. Concept Checking">described here</a>. They
155 can help users discover when they break the rules of the STL, before
157 </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
158 shared library (if a shared library has been
159 requested). Values for 'style' that are currently supported
160 are 'gnu', 'gnu-versioned-namespace', 'darwin', and
161 'darwin-export'. Both gnu- options require that a recent
162 version of the GNU linker be in use. Both darwin options are
163 equivalent. With no style given, the configure script will try
164 to guess correct defaults for the host system, probe to see if
165 additional requirements are necessary and present for
166 activation, and if so, will turn symbol versioning on. This
167 option can change the library ABI.
168 </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.
169 If enabled (as by default), and the compiler seems capable of
170 passing the simple sanity checks thrown at it, adjusts items
171 in namespace std, namespace std::tr1, and namespace __gnu_cxx
172 so that -fvisibility options work.
173 </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
174 stdc++.h.gch, a pre-compiled file including all the standard
175 C++ includes. If enabled (as by default), and the compiler
176 seems capable of passing the simple sanity checks thrown at
177 it, try to build stdc++.h.gch as part of the make process.
178 In addition, this generated file is used later on (by appending <code class="code">
179 --include bits/stdc++.h </code> to CXXFLAGS) when running the
181 </p></dd><dt><span class="term"><code class="code">--disable-hosted-libstdcxx</code></span></dt><dd><p>
182 By default, a complete <span class="emphasis"><em>hosted</em></span> C++ library is
183 built. The C++ Standard also describes a
184 <span class="emphasis"><em>freestanding</em></span> environment, in which only a
185 minimal set of headers are provided. This option builds such an
187 </p></dd><dt><span class="term"><code class="code">--enable-clock-gettime</code></span></dt><dd><p>This is an abbreviated form of
188 <code class="code">'--enable-clock-gettime=yes'</code>(described next).
189 </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
190 clock_gettime clocks, used in the implementation of [time.clock],
191 and of the nanosleep and sched_yield functions, used in the
192 implementation of [thread.thread.this] of the current C++0x draft.
193 The choice OPTION=yes checks for the availability of the facilities
194 in libc and libposix4. In case of need the latter is also linked
195 to libstdc++ as part of the build process. OPTION=rt also searches
196 (and, in case, links) librt. Note that the latter is not always
197 desirable because, in glibc, for example, in turn it triggers the
198 linking of libpthread too, which activates locking, a large overhead
199 for single-thread programs. OPTION=no skips the tests completely.
200 The default is OPTION=no.
201 </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>