1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 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 V1.75.2" /><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" title="Configure"><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. 9</p><p> 10 Here are all of the configure options specific to libstdc++. Keep 11 in mind that 12 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 43 "c++/(version)". 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> 46 (described next). 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> 51 (described next). 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 67 next). 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> 81 (described next). 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 83 given in the 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 86 library ABI. 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 106 options, like 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"> 118 -fstrict-aliasing 119 -fno-exceptions 120 -ffunction-sections 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 159 their programs run. 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 183 testsuite. 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 189 environment. 190 </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-time</code></span></dt><dd><p>This is an abbreviated form of 191 <code class="code">'--enable-libstdcxx-time=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> 205