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"><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 Vsnapshot" /><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> 3 When configuring libstdc++, you'll have to configure the entire 4 <span class="emphasis"><em>gccsrcdir</em></span> directory. Consider using the 5 toplevel gcc configuration option 6 <code class="literal">--enable-languages=c++</code>, which saves time by only 7 building the C++ toolchain. 8</p><p> 9 Here are all of the configure options specific to libstdc++. Keep 10 in mind that 11 12 <a class="link" href="http://sourceware.org/autobook/autobook/autobook_14.html" target="_top">they 13 all have opposite forms as well</a> (enable/disable and 14 with/without). The defaults are for the <span class="emphasis"><em>current 15 development sources</em></span>, which may be different than those 16 for released versions. 17</p><p>The canonical way to find out the configure options that are 18 available for a given set of libstdc++ sources is to go to the 19 source directory and then type: <span class="command"><strong>./configure --help</strong></span>. 20</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 21 compilers. As such, targets like "powerpc-elf" will have 22 libstdc++ built many different ways: "-msoft-float" 23 and not, etc. A different libstdc++ will be built for each of 24 the different multilib versions. This option is on by default. 25 </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 26 compiler-specific subdirectory (i.e., 27 <code class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>) 28 instead of <code class="code">${libdir}</code>. This option is useful if you 29 intend to use several versions of gcc in parallel. In addition, 30 libstdc++'s include files will be installed in 31 <code class="code">${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>, 32 unless you also specify 33 <code class="literal">--with-gxx-include-dir=</code><code class="filename">dirname</code> during configuration. 34 </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, 35 the following puts all the libstdc++ headers into a directory 36 called "4.4-20090404" instead of the usual 37 "c++/(version)". 38 </p><pre class="programlisting"> 39 --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> 40 (described next). 41 </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 42 choice is to use 'stdio', a generic "C" abstraction. 43 The default is 'stdio'. This option can change the library ABI. 44 </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> 45 (described next). 46 </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 47 choices are 'ieee_1003.1-2001' to specify an X/Open, Standard Unix 48 (IEEE Std. 1003.1-2001) model based on langinfo/iconv/catgets, 49 'gnu' to specify a model based on functionality from the GNU C 50 library (langinfo/iconv/gettext) (from <a class="link" href="https://www.gnu.org/software/libc/" target="_top">glibc</a>, the GNU C 51 library), 'generic' to use a generic "C" abstraction which consists 52 of "C" locale info, 'newlib' to specify the Newlib C library model 53 which only differs from the 'generic' model in the handling of 54 ctype, or 'darwin' which omits the <span class="type">wchar_t</span> specializations 55 needed by the 'generic' model. 56 </p><p>If not explicitly specified, the configure process tries 57 to guess the most suitable package from the choices above. The 58 default is 'generic'. On glibc-based systems of sufficient 59 vintage (2.3 and newer), 'gnu' is automatically selected. On newlib-based 60 systems (<code class="code">'--with_newlib=yes'</code>) and OpenBSD, 'newlib' is 61 automatically selected. On Mac OS X 'darwin' is automatically selected. 62 This option can change the library ABI. 63 </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-allocator</code></span></dt><dd><p>This is an abbreviated form of 64 <code class="code">'--enable-libstdcxx-allocator=auto'</code> (described 65 next). 66 </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 67 choices are 'new' to specify a wrapper for new, 'malloc' to 68 specify a wrapper for malloc, 'mt' for a fixed power of two allocator, 69 'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator. 70 See this page for more information on allocator 71 <a class="link" href="memory.html#allocator.ext" title="Extension Allocators">extensions</a>. This option 72 can change the library ABI. 73 </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 74 compatibility with C++. Options are c, c_std, and c_global. 75 These correspond to the source directory's include/c, 76 include/c_std, and include/c_global, and may also include 77 include/c_compatibility. The default is 'c_global'. 78 </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> 79 (described next). 80 </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 81 given in the 82 general <a class="link" href="http://gcc.gnu.org/install/configure.html" target="_top">compiler 83 configuration instructions</a>. This option can change the 84 library ABI. 85 </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, 86 the configure process enables it if possible. This 87 option can change the library ABI. 88 </p></dd><dt><span class="term"><code class="code">--enable-libstdcxx-time</code></span></dt><dd><p>This is an abbreviated form of 89 <code class="code">'--enable-libstdcxx-time=yes'</code>(described next). 90 </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 91 clock_gettime clocks, used in the implementation of [time.clock], 92 and of the nanosleep and sched_yield functions, used in the 93 implementation of [thread.thread.this] of the 2011 ISO C++ standard. 94 The choice OPTION=yes checks for the availability of the facilities 95 in libc and libposix4. In case it's needed the latter is also linked 96 to libstdc++ as part of the build process. OPTION=rt also searches 97 (and, if needed, links) librt. Note that the latter is not always 98 desirable because, in glibc, for example, in turn it triggers the 99 linking of libpthread too, which activates locking, a large overhead 100 for single-thread programs. OPTION=no skips the tests completely. 101 The default is OPTION=auto, which skips the checks and enables the 102 features only for targets known to support them. 103 </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. 104 By default, the debug libraries are compiled with 105 <code class="code"> CXXFLAGS='-g3 -O0 -fno-inline'</code> 106 , are installed in <code class="code">${libdir}/debug</code>, and have the 107 same names and versioning information as the non-debug 108 libraries. This option is off by default. 109 </p><p>Note this make command, executed in 110 the build directory, will do much the same thing, without the 111 configuration difference and without building everything twice: 112 <code class="code">make CXXFLAGS='-g3 -O0 -fno-inline' all</code> 113 </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> 114 is also specified, and applies to the debug builds only. With 115 this option, you can pass a specific string of flags to the 116 compiler to use when building the debug versions of libstdc++. 117 FLAGS is a quoted string of options, like 118 </p><pre class="programlisting"> 119 --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) 120 flags to the compiler to use when building libstdc++. This 121 option can change the library ABI. FLAGS is a quoted string of 122 options, like 123 </p><pre class="programlisting"> 124 --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</pre><p> 125 Note that the flags don't necessarily have to all be -f flags, 126 as shown, but usually those are the ones that will make sense 127 for experimentation and configure-time overriding. 128 </p><p>The advantage of --enable-cxx-flags over setting CXXFLAGS in 129 the 'make' environment is that, if files are automatically 130 rebuilt, the same flags will be used when compiling those files 131 as well, so that everything matches. 132 </p><p>Fun flags to try might include combinations of 133 </p><pre class="programlisting"> 134 -fstrict-aliasing 135 -fno-exceptions 136 -ffunction-sections 137 -fvtable-gc</pre><p>and opposite forms (-fno-) of the same. Tell us (the libstdc++ 138 mailing list) if you discover more! 139 </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 140 with many other functions for wide characters, and math 141 classification macros, etc. If enabled, all C99 functions not 142 specified by the C++ standard will be put into <code class="code">namespace 143 __gnu_cxx</code>, and then all these names will 144 be injected into namespace std, so that C99 functions can be 145 used "as if" they were in the C++ standard (as they 146 will eventually be in some future revision of the standard, 147 without a doubt). By default, C99 support is on, assuming the 148 configure probes find all the necessary functions and bits 149 necessary. This option can change the library ABI. 150 </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 151 required for wide character conversion support. Disabling 152 wide character specializations may be expedient for initial 153 porting efforts, but builds only a subset of what is required by 154 ISO, and is not recommended. By default, this option is on. 155 This option can change the library ABI. 156 </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 157 provided as a GNU extension to C++98 in g++. This flag builds 158 support for "long long" into the library (specialized 159 templates and the like for iostreams). This option is on by default: 160 if enabled, users will have to either use the new-style "C" 161 headers by default (i.e., <cmath> not <math.h>) 162 or add appropriate compile-time flags to all compile lines to 163 allow "C" visibility of this feature (on GNU/Linux, 164 the flag is -D_ISOC99_SOURCE, which is added automatically via 165 CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE). 166 This option can change the library ABI. 167 </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 168 the optimization that allocates empty objects in static memory. 169 Mostly useful together with shared memory allocators, see PR 170 libstdc++/16612 for details. 171 </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 172 library templates, in the form of specialized templates described in 173 the <a class="link" href="concept_checking.html" title="Concept Checking">Concept 174 Checking</a> section. They 175 can help users discover when they break the rules of the STL, before 176 their programs run. These checks are based on C++03 rules and some of 177 them are not compatible with correct C++11 code. 178 </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 179 shared library (if a shared library has been 180 requested). Values for 'style' that are currently supported 181 are 'gnu', 'gnu-versioned-namespace', 'darwin', 182 'darwin-export', and 'sun'. Both gnu- options require that a recent 183 version of the GNU linker be in use. Both darwin options are 184 equivalent. With no style given, the configure script will try 185 to guess correct defaults for the host system, probe to see if 186 additional requirements are necessary and present for 187 activation, and if so, will turn symbol versioning on. This 188 option can change the library ABI. 189 </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 190 attributes. If enabled (as by default), and the compiler seems 191 capable of passing the simple sanity checks thrown at it, adjusts 192 items in namespace std, namespace std::tr1, namespace std::tr2, 193 and namespace __gnu_cxx to have <code class="code">visibility ("default")</code> 194 so that -fvisibility options can be used without affecting the 195 normal external-visibility of namespace std entities. 196 Prior to 4.7 this option was spelled <code class="code">--enable-visibility</code>. 197 </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 198 stdc++.h.gch, a pre-compiled file including all the standard 199 C++ includes. If enabled (as by default), and the compiler 200 seems capable of passing the simple sanity checks thrown at 201 it, try to build stdc++.h.gch as part of the make process. 202 In addition, this generated file is used later on (by appending <code class="code"> 203 --include bits/stdc++.h </code> to CXXFLAGS) when running the 204 testsuite. 205 </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 206 specializations for certain types defined in the standard libraries. 207 These types include <code class="classname">string</code> and dependents like 208 <code class="classname">char_traits</code>, the templatized IO classes, 209 <code class="classname">allocator</code>, and others. 210 Disabling means that implicit 211 template generation will be used when compiling these types. By 212 default, this option is on. This option can change the library ABI. 213 </p></dd><dt><span class="term"><code class="code">--disable-hosted-libstdcxx</code></span></dt><dd><p> 214 By default, a complete <span class="emphasis"><em>hosted</em></span> C++ library is 215 built. The C++ Standard also describes a 216 <span class="emphasis"><em>freestanding</em></span> environment, in which only a 217 minimal set of headers are provided. This option builds such an 218 environment. 219 </p></dd><dt><span class="term"><code class="code">--disable-libstdcxx-verbose</code></span></dt><dd><p> 220 By default, the library is configured to write descriptive messages 221 to standard error for certain events such as calling a pure virtual 222 function or the invocation of the standard terminate handler. Those 223 messages cause the library to depend on the demangler and standard I/O 224 facilities, which might be undesirable in a low-memory environment or 225 when standard error is not available. This option disables those 226 messages. This option does not change the library ABI. 227 </p></dd><dt><span class="term"><code class="code">--disable-libstdcxx-dual-abi</code></span></dt><dd><p> 228 Disable support for the new, C++11-conforming implementations of 229 <code class="code">std::string</code>, <code class="code">std::list</code> etc. so that the 230 library only provides definitions of types using the old ABI 231 (see <a class="xref" href="using_dual_abi.html" title="Dual ABI">Dual ABI</a>). 232 This option changes the library ABI. 233 </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> 234 Set the default value for the <span class="symbol">_GLIBCXX_USE_CXX11_ABI</span> 235 macro (see <a class="xref" href="using_macros.html" title="Macros">Macros</a>). 236 The default is <code class="option">OPTION=new</code> which sets the macro to 237 <code class="literal">1</code>, 238 use <code class="option">OPTION=gcc4-compatible</code> to set it to 239 <code class="literal">0</code>. 240 This option does not change the library ABI. 241 </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++ 242 runtime with instrumentation for vtable verification. All virtual 243 functions in the standard library will be verified at runtime. 244 Types impacted include <code class="classname">locale</code> and 245 <code class="classname">iostream</code>, and others. Disabling means that 246 the C++ runtime is compiled without support for vtable 247 verification. By default, this option is off. 248 </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 249 as the usual libstdc++ and libsupc++ libraries. This is enabled by 250 default on select POSIX targets where it is known to work and disabled 251 otherwise. 252 </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>