1<sect1 id="manual.intro.setup.configure" xreflabel="Configuring"> 2<?dbhtml filename="configure.html"?> 3 4<sect1info> 5 <keywordset> 6 <keyword> 7 ISO C++ 8 </keyword> 9 <keyword> 10 configure 11 </keyword> 12 <keyword> 13 options 14 </keyword> 15 </keywordset> 16</sect1info> 17 18<title>Configure</title> 19 20<para> 21 When configuring libstdc++, you'll have to configure the entire 22 <emphasis>gccsrcdir</emphasis> directory. Consider using the 23 toplevel gcc configuration option 24 <literal>--enable-languages=c++</literal>, which saves time by only 25 building the C++ toolchain. 26</para> 27 28<para> 29 Here are all of the configure options specific to libstdc++. Keep 30 in mind that 31 <!-- This SECnn should be the "Choosing Package Options" section. --> 32 <ulink url="http://sourceware.org/autobook/autobook/autobook_14.html">they 33 all have opposite forms as well</ulink> (enable/disable and 34 with/without). The defaults are for the <emphasis>current 35 development sources</emphasis>, which may be different than those 36 for released versions. 37</para> 38<para>The canonical way to find out the configure options that are 39 available for a given set of libstdc++ sources is to go to the 40 source directory and then type:<command>./configure --help</command>. 41</para> 42 43<variablelist> 44 <varlistentry><term><code>--enable-multilib</code>[default]</term> 45 <listitem><para>This is part of the generic multilib support for building cross 46 compilers. As such, targets like "powerpc-elf" will have 47 libstdc++ built many different ways: "-msoft-float" 48 and not, etc. A different libstdc++ will be built for each of 49 the different multilib versions. This option is on by default. 50 </para> 51 </listitem></varlistentry> 52 53 <varlistentry><term><code>--enable-sjlj-exceptions</code></term> 54 <listitem><para>Forces old, set-jump/long-jump exception handling model. If 55 at all possible, the new, frame unwinding exception handling routines 56 should be used instead, as they significantly reduce both 57 runtime memory usage and executable size. This option can 58 change the library ABI. 59 </para> 60 </listitem></varlistentry> 61 62 <varlistentry><term><code>--enable-version-specific-runtime-libs</code></term> 63 <listitem><para>Specify that run-time libraries should be installed in the 64 compiler-specific subdirectory (i.e., 65 <code>${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>) 66 instead of <code>${libdir}</code>. This option is useful if you 67 intend to use several versions of gcc in parallel. In addition, 68 libstdc++'s include files will be installed in 69 <code>${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>, 70 unless you also specify 71 <literal>--with-gxx-include-dir=<filename class="directory">dirname</filename></literal> during configuration. 72 </para> 73 </listitem></varlistentry> 74 75 <varlistentry><term><code>--with-gxx-include-dir=<include-files dir></code></term> 76 <listitem><para>Adds support for named libstdc++ include directory. For instance, 77 the following puts all the libstdc++ headers into a directory 78 called "4.4-20090404" instead of the usual 79 "c++/(version)". 80 </para> 81 <programlisting> 82 --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/4.4-20090404</programlisting> </listitem></varlistentry> 83 84 <varlistentry><term><code>--enable-cstdio</code></term> 85 <listitem><para>This is an abbreviated form of <code>'--enable-cstdio=stdio'</code> 86 (described next). 87 </para> 88 </listitem></varlistentry> 89 90 <varlistentry><term><code>--enable-cstdio=OPTION</code></term> 91 <listitem><para>Select a target-specific I/O package. At the moment, the only 92 choice is to use 'stdio', a generic "C" abstraction. 93 The default is 'stdio'. This option can change the library ABI. 94 </para> 95 </listitem></varlistentry> 96 97 <varlistentry><term><code>--enable-clocale</code></term> 98 <listitem><para>This is an abbreviated form of <code>'--enable-clocale=generic'</code> 99 (described next). 100 </para> 101 </listitem></varlistentry> 102 103 <varlistentry><term><code>--enable-clocale=OPTION</code></term> 104 <listitem><para>Select a target-specific underlying locale package. The 105 choices are 'ieee_1003.1-2001' to specify an X/Open, Standard Unix 106 (IEEE Std. 1003.1-2001) model based on langinfo/iconv/catgets, 107 'gnu' to specify a model based on functionality from the GNU C 108 library (langinfo/iconv/gettext) (from <ulink url="http://sources.redhat.com/glibc/">glibc</ulink>, the GNU C 109 library), or 'generic' to use a generic "C" 110 abstraction which consists of "C" locale info. 111 </para> 112 113 <para>If not explicitly specified, the configure proccess tries 114 to guess the most suitable package from the choices above. The 115 default is 'generic'. On glibc-based systems of sufficient 116 vintage (2.2.5 and newer) and capability (with installed DE and 117 FR locale data), 'gnu' is automatically selected. This option 118 can change the library ABI. 119 </para> 120 </listitem></varlistentry> 121 122 <varlistentry><term><code>--enable-libstdcxx-allocator</code></term> 123 <listitem><para>This is an abbreviated form of 124 <code>'--enable-libstdcxx-allocator=auto'</code> (described 125 next). 126 </para> 127 </listitem></varlistentry> 128 129 <varlistentry><term><code>--enable-libstdcxx-allocator=OPTION </code></term> 130 <listitem><para>Select a target-specific underlying std::allocator. The 131 choices are 'new' to specify a wrapper for new, 'malloc' to 132 specify a wrapper for malloc, 'mt' for a fixed power of two allocator, 133 'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator. 134 See this page for more information on allocator 135 <link linkend="allocator.ext">extensions</link>. This option 136 can change the library ABI. 137 </para> 138 </listitem></varlistentry> 139 140 <varlistentry><term><code>--enable-cheaders=OPTION</code></term> 141 <listitem><para>This allows the user to define the approach taken for C header 142 compatibility with C++. Options are c, c_std, and c_global. 143 These correspond to the source directory's include/c, 144 include/c_std, and include/c_global, and may also include 145 include/c_compatibility. The default is 'c_global'. 146 </para> 147 </listitem></varlistentry> 148 149 <varlistentry><term><code>--enable-threads</code></term> 150 <listitem><para>This is an abbreviated form of <code>'--enable-threads=yes'</code> 151 (described next). 152 </para> 153 </listitem></varlistentry> 154 155 <varlistentry><term><code>--enable-threads=OPTION</code></term> 156 <listitem><para>Select a threading library. A full description is 157 given in the 158 general <ulink url="http://gcc.gnu.org/install/configure.html">compiler 159 configuration instructions</ulink>. This option can change the 160 library ABI. 161 </para> 162 </listitem></varlistentry> 163 164 <varlistentry><term><code>--enable-libstdcxx-debug</code></term> 165 <listitem><para>Build separate debug libraries in addition to what is normally built. 166 By default, the debug libraries are compiled with 167 <code> CXXFLAGS='-g3 -O0 -fno-inline'</code> 168 , are installed in <code>${libdir}/debug</code>, and have the 169 same names and versioning information as the non-debug 170 libraries. This option is off by default. 171 </para> 172 <para>Note this make command, executed in 173 the build directory, will do much the same thing, without the 174 configuration difference and without building everything twice: 175 <code>make CXXFLAGS='-g3 -O0 -fno-inline' all</code> 176 </para> 177 </listitem></varlistentry> 178 179 <varlistentry><term><code>--enable-libstdcxx-debug-flags=FLAGS</code></term> 180 181 <listitem><para>This option is only valid when <code> --enable-debug </code> 182 is also specified, and applies to the debug builds only. With 183 this option, you can pass a specific string of flags to the 184 compiler to use when building the debug versions of libstdc++. 185 FLAGS is a quoted string of options, like 186 </para> 187 <programlisting> 188 --enable-libstdcxx-debug-flags='-g3 -O1 -fno-inline'</programlisting> 189 </listitem></varlistentry> 190 191 <varlistentry><term><code>--enable-cxx-flags=FLAGS</code></term> 192 <listitem><para>With this option, you can pass a string of -f (functionality) 193 flags to the compiler to use when building libstdc++. This 194 option can change the library ABI. FLAGS is a quoted string of 195 options, like 196 </para> 197 <programlisting> 198 --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</programlisting> 199 <para> 200 Note that the flags don't necessarily have to all be -f flags, 201 as shown, but usually those are the ones that will make sense 202 for experimentation and configure-time overriding. 203 </para> 204 <para>The advantage of --enable-cxx-flags over setting CXXFLAGS in 205 the 'make' environment is that, if files are automatically 206 rebuilt, the same flags will be used when compiling those files 207 as well, so that everything matches. 208 </para> 209 <para>Fun flags to try might include combinations of 210 </para> 211 <programlisting> 212 -fstrict-aliasing 213 -fno-exceptions 214 -ffunction-sections 215 -fvtable-gc</programlisting> 216 <para>and opposite forms (-fno-) of the same. Tell us (the libstdc++ 217 mailing list) if you discover more! 218 </para> 219 </listitem></varlistentry> 220 221 <varlistentry><term><code>--enable-c99</code></term> 222 <listitem><para>The "long long" type was introduced in C99, along 223 with many other functions for wide characters, and math 224 classification macros, etc. If enabled, all C99 functions not 225 specified by the C++ standard will be put into <code>namespace 226 __gnu_cxx</code>, and then all these names will 227 be injected into namespace std, so that C99 functions can be 228 used "as if" they were in the C++ standard (as they 229 will eventually be in some future revision of the standard, 230 without a doubt). By default, C99 support is on, assuming the 231 configure probes find all the necessary functions and bits 232 necessary. This option can change the library ABI. 233 </para> 234 </listitem></varlistentry> 235 236 <varlistentry><term><code>--enable-wchar_t</code>[default]</term> 237 <listitem><para>Template specializations for the "wchar_t" type are 238 required for wide character conversion support. Disabling 239 wide character specializations may be expedient for initial 240 porting efforts, but builds only a subset of what is required by 241 ISO, and is not recommended. By default, this option is on. 242 This option can change the library ABI. 243 </para> 244 </listitem></varlistentry> 245 246 <varlistentry><term><code>--enable-long-long </code></term> 247 <listitem><para>The "long long" type was introduced in C99. It is 248 provided as a GNU extension to C++98 in g++. This flag builds 249 support for "long long" into the library (specialized 250 templates and the like for iostreams). This option is on by default: 251 if enabled, users will have to either use the new-style "C" 252 headers by default (i.e., <cmath> not <math.h>) 253 or add appropriate compile-time flags to all compile lines to 254 allow "C" visibility of this feature (on GNU/Linux, 255 the flag is -D_ISOC99_SOURCE, which is added automatically via 256 CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE). 257 This option can change the library ABI. 258 </para> 259 </listitem></varlistentry> 260 261 <varlistentry><term><code>--enable-fully-dynamic-string</code></term> 262 <listitem><para>This option enables a special version of basic_string avoiding 263 the optimization that allocates empty objects in static memory. 264 Mostly useful together with shared memory allocators, see PR 265 libstdc++/16612 for details. 266 </para> 267 </listitem></varlistentry> 268 269 <varlistentry><term><code>--enable-concept-checks</code></term> 270 <listitem><para>This turns on additional compile-time checks for instantiated 271 library templates, in the form of specialized templates, 272 <link linkend="std.diagnostics.concept_checking">described here</link>. They 273 can help users discover when they break the rules of the STL, before 274 their programs run. 275 </para> 276 </listitem></varlistentry> 277 278 <varlistentry><term><code>--enable-symvers[=style]</code></term> 279 280 <listitem><para>In 3.1 and later, tries to turn on symbol versioning in the 281 shared library (if a shared library has been 282 requested). Values for 'style' that are currently supported 283 are 'gnu', 'gnu-versioned-namespace', 'darwin', and 284 'darwin-export'. Both gnu- options require that a recent 285 version of the GNU linker be in use. Both darwin options are 286 equivalent. With no style given, the configure script will try 287 to guess correct defaults for the host system, probe to see if 288 additional requirements are necessary and present for 289 activation, and if so, will turn symbol versioning on. This 290 option can change the library ABI. 291 </para> 292 293 </listitem></varlistentry> 294 295 <varlistentry><term><code>--enable-visibility</code></term> 296 <listitem><para> In 4.2 and later, enables or disables visibility attributes. 297 If enabled (as by default), and the compiler seems capable of 298 passing the simple sanity checks thrown at it, adjusts items 299 in namespace std, namespace std::tr1, and namespace __gnu_cxx 300 so that -fvisibility options work. 301 </para> 302 </listitem></varlistentry> 303 304 <varlistentry><term><code>--enable-libstdcxx-pch</code></term> 305 <listitem><para>In 3.4 and later, tries to turn on the generation of 306 stdc++.h.gch, a pre-compiled file including all the standard 307 C++ includes. If enabled (as by default), and the compiler 308 seems capable of passing the simple sanity checks thrown at 309 it, try to build stdc++.h.gch as part of the make process. 310 In addition, this generated file is used later on (by appending <code> 311 --include bits/stdc++.h </code> to CXXFLAGS) when running the 312 testsuite. 313 </para> 314 </listitem></varlistentry> 315 316 <varlistentry><term><code>--disable-hosted-libstdcxx</code></term> 317 <listitem> 318 <para> 319 By default, a complete <emphasis>hosted</emphasis> C++ library is 320 built. The C++ Standard also describes a 321 <emphasis>freestanding</emphasis> environment, in which only a 322 minimal set of headers are provided. This option builds such an 323 environment. 324 </para> 325 </listitem></varlistentry> 326 327 <varlistentry><term><code>--enable-libstdcxx-time</code></term> 328 <listitem><para>This is an abbreviated form of 329 <code>'--enable-libstdcxx-time=yes'</code>(described next). 330 </para> 331 </listitem></varlistentry> 332 333 <varlistentry><term><code>--enable-libstdcxx-time=OPTION</code></term> 334 <listitem><para>Enables link-type checks for the availability of the 335 clock_gettime clocks, used in the implementation of [time.clock], 336 and of the nanosleep and sched_yield functions, used in the 337 implementation of [thread.thread.this] of the current C++0x draft. 338 The choice OPTION=yes checks for the availability of the facilities 339 in libc and libposix4. In case of need the latter is also linked 340 to libstdc++ as part of the build process. OPTION=rt also searches 341 (and, in case, links) librt. Note that the latter is not always 342 desirable because, in glibc, for example, in turn it triggers the 343 linking of libpthread too, which activates locking, a large overhead 344 for single-thread programs. OPTION=no skips the tests completely. 345 The default is OPTION=no. 346 </para> 347 </listitem></varlistentry> 348 349</variablelist> 350 351</sect1> 352