| <sect1 id="manual.intro.setup.configure" xreflabel="Configuring"> |
| <?dbhtml filename="configure.html"?> |
| |
| <sect1info> |
| <keywordset> |
| <keyword> |
| ISO C++ |
| </keyword> |
| <keyword> |
| configure |
| </keyword> |
| <keyword> |
| options |
| </keyword> |
| </keywordset> |
| </sect1info> |
| |
| <title>Configure</title> |
| |
| <para> |
| Here are some of the non-obvious options to libstdc++'s configure. |
| Keep in mind that |
| <!-- This SECnn should be the "Choosing Package Options" section. --> |
| <ulink url="http://www.gnu.org/software/autoconf/manual/autoconf-2.57/html_node/autoconf_131.html#SEC131">they |
| all have opposite forms as well</ulink> |
| (enable/disable and with/without). The defaults are for <emphasis>current |
| development sources</emphasis>, which may be different than those for |
| released versions. |
| </para> |
| <para>The canonical way to find out the configure options that are |
| available for a given set of libstdc++ sources is to go to the |
| source directory and then type:<code> ./configure --help</code> |
| </para> |
| |
| <variablelist> |
| <varlistentry><term><code>--enable-multilib</code>[default]</term> |
| <listitem><para>This is part of the generic multilib support for building cross |
| compilers. As such, targets like "powerpc-elf" will have |
| libstdc++ built many different ways: "-msoft-float" |
| and not, etc. A different libstdc++ will be built for each of |
| the different multilib versions. This option is on by default. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-sjlj-exceptions</code></term> |
| <listitem><para>Forces old, set-jump/long-jump exception handling model. If |
| at all possible, the new, frame unwinding exception handling routines |
| should be used instead, as they significantly reduce both |
| runtime memory usage and executable size. This option can |
| change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-version-specific-runtime-libs</code></term> |
| <listitem><para>Specify that run-time libraries should be installed in the |
| compiler-specific subdirectory (i.e., |
| <code>${libdir}/gcc-lib/${target_alias}/${gcc_version}</code>) |
| instead of <code>${libdir}</code>. This option is useful if you |
| intend to use several versions of gcc in parallel. In addition, |
| libstdc++'s include files will be installed in |
| <code>${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++</code>, |
| unless you also specify |
| <literal>--with-gxx-include-dir=<filename class="directory">dirname</filename></literal> during configuration. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--with-gxx-include-dir=<include-files dir></code></term> |
| <listitem><para>Adds support for named libstdc++ include directory. For instance, |
| the following puts all the libstdc++ headers into a directory |
| called "2.97-20001008" instead of the usual |
| "c++/(version)". |
| </para> |
| <programlisting> |
| --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</programlisting> </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-cstdio</code></term> |
| <listitem><para>This is an abbreviated form of <code>'--enable-cstdio=stdio'</code> |
| (described next). This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-cstdio=OPTION</code></term> |
| <listitem><para>Select a target-specific I/O package. At the moment, the only |
| choice is to use 'stdio', a generic "C" abstraction. |
| The default is 'stdio'. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-clocale</code></term> |
| <listitem><para>This is an abbreviated form of <code>'--enable-clocale=generic'</code> |
| (described next). This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-clocale=OPTION</code></term> |
| <listitem><para>Select a target-specific underlying locale package. The |
| choices are 'ieee_1003.1-2001' to specify an X/Open, Standard Unix |
| (IEEE Std. 1003.1-2001) model based on langinfo/iconv/catgets, |
| 'gnu' to specify a model based on functionality from the GNU C |
| library (langinfo/iconv/gettext) (from <ulink url="http://sources.redhat.com/glibc/">glibc</ulink>, the GNU C |
| library), or 'generic' to use a generic "C" |
| abstraction which consists of "C" locale info. |
| </para> |
| |
| <para>As part of the configuration process, the "C" library is |
| probed both for sufficient vintage, and installed locale |
| data. If either of these elements are not present, the C++ |
| locale model default to 'generic.' On glibc-based systems of |
| version 2.2.5 and above with installed locale files, 'gnu' is |
| automatically selected. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-libstdcxx-allocator</code></term> |
| <listitem><para>This is an abbreviated form of |
| <code>'--enable-libstdcxx-allocator=auto'</code> (described |
| next). This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-libstdcxx-allocator=OPTION </code></term> |
| <listitem><para>Select a target-specific underlying std::allocator. The |
| choices are 'new' to specify a wrapper for new, 'malloc' to |
| specify a wrapper for malloc, 'mt' for a fixed power of two allocator |
| (<ulink url="ext/mt_allocator.html">documented</ulink> under extensions), |
| 'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator. |
| This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-cheaders=OPTION</code></term> |
| <listitem><para>This allows the user to define the approach taken for C header |
| compatibility with C++. Options are c, c_std, and c_global. |
| These correspond to the source directory's include/c, |
| include/c_std, and include/c_global, and may also include |
| include/c_compatibility. The default is c_global. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-threads</code></term> |
| <listitem><para>This is an abbreviated form of <code>'--enable-threads=yes'</code> |
| (described next). This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-threads=OPTION</code></term> |
| <listitem><para>Select a threading library. A full description is given in the |
| general <ulink url="http://gcc.gnu.org/install/configure.html">compiler |
| configuration instructions</ulink>. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-libstdcxx-debug</code></term> |
| <listitem><para>Build separate debug libraries in addition to what is normally built. |
| By default, the debug libraries are compiled with |
| <code> CXXFLAGS='-g3 -O0'</code> |
| , are installed in <code>${libdir}/debug</code>, and have the |
| same names and versioning information as the non-debug |
| libraries. This option is off by default. |
| </para> |
| <para>Note this make command, executed in |
| the build directory, will do much the same thing, without the |
| configuration difference and without building everything twice: |
| <code>make CXXFLAGS='-g3 -O0' all</code> |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-libstdcxx-debug-flags=FLAGS</code></term> |
| |
| <listitem><para>This option is only valid when <code> --enable-debug </code> |
| is also specified, and applies to the debug builds only. With |
| this option, you can pass a specific string of flags to the |
| compiler to use when building the debug versions of libstdc++. |
| FLAGS is a quoted string of options, like |
| </para> |
| <programlisting> |
| --enable-libstdcxx-debug-flags='-g3 -O1 -gdwarf-2'</programlisting> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-cxx-flags=FLAGS</code></term> |
| <listitem><para>With this option, you can pass a string of -f (functionality) |
| flags to the compiler to use when building libstdc++. This |
| option can change the library ABI. FLAGS is a quoted string of |
| options, like |
| </para> |
| <programlisting> |
| --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</programlisting> |
| <para> |
| Note that the flags don't necessarily have to all be -f flags, |
| as shown, but usually those are the ones that will make sense |
| for experimentation and configure-time overriding. |
| </para> |
| <para>The advantage of --enable-cxx-flags over setting CXXFLAGS in |
| the 'make' environment is that, if files are automatically |
| rebuilt, the same flags will be used when compiling those files |
| as well, so that everything matches. |
| </para> |
| <para>Fun flags to try might include combinations of |
| </para> |
| <programlisting> |
| -fstrict-aliasing |
| -fno-exceptions |
| -ffunction-sections |
| -fvtable-gc</programlisting> |
| <para>and opposite forms (-fno-) of the same. Tell us (the libstdc++ |
| mailing list) if you discover more! |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-c99</code></term> |
| <listitem><para>The "long long" type was introduced in C99, along |
| with many other functions for wide characters, and math |
| classification macros, etc. If enabled, all C99 functions not |
| specified by the C++ standard will be put into <code>namespace |
| __gnu_cxx</code>, and then all these names will |
| be injected into namespace std, so that C99 functions can be |
| used "as if" they were in the C++ standard (as they |
| will eventually be in some future revision of the standard, |
| without a doubt). By default, C99 support is on, assuming the |
| configure probes find all the necessary functions and bits |
| necessary. This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-wchar_t</code>[default]</term> |
| <listitem><para>Template specializations for the "wchar_t" type are |
| required for wide character conversion support. Disabling |
| wide character specializations may be expedient for initial |
| porting efforts, but builds only a subset of what is required by |
| ISO, and is not recommended. By default, this option is on. |
| This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-long-long </code></term> |
| <listitem><para>The "long long" type was introduced in C99. It is |
| provided as a GNU extension to C++98 in g++. This flag builds |
| support for "long long" into the library (specialized |
| templates and the like for iostreams). This option is on by default: |
| if enabled, users will have to either use the new-style "C" |
| headers by default (i.e., <cmath> not <math.h>) |
| or add appropriate compile-time flags to all compile lines to |
| allow "C" visibility of this feature (on GNU/Linux, |
| the flag is -D_ISOC99_SOURCE, which is added automatically via |
| CPLUSPLUS_CPP_SPEC's addition of _GNU_SOURCE). |
| This option can change the library ABI. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-fully-dynamic-string</code></term> |
| <listitem><para>This option enables a special version of basic_string avoiding |
| the optimization that allocates empty objects in static memory. |
| Mostly useful together with shared memory allocators, see PR |
| libstdc++/16612 for details. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-concept-checks</code></term> |
| <listitem><para>This turns on additional compile-time checks for instantiated |
| library templates, in the form of specialized templates, |
| <ulink url="19_diagnostics/howto.html#3">described here</ulink>. They |
| can help users discover when they break the rules of the STL, before |
| their programs run. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-symvers[=style]</code></term> |
| |
| <listitem><para>In 3.1 and later, tries to turn on symbol versioning in the |
| shared library (if a shared library has been |
| requested). Values for 'style' that are currently supported |
| are 'gnu', 'gnu-versioned-namespace', 'darwin', and |
| 'darwin-export'. Both gnu- options require that a recent |
| version of the GNU linker be in use. Both darwin options are |
| equivalent. With no style given, the configure script will try |
| to guess correct defaults for the host system, probe to see if |
| additional requirements are necessary and present for |
| activation, and if so, will turn symbol versioning on. This |
| option can change the library ABI. |
| </para> |
| |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-visibility</code></term> |
| <listitem><para> In 4.2 and later, enables or disables visibility attributes. |
| If enabled (as by default), and the compiler seems capable of |
| passing the simple sanity checks thrown at it, adjusts items |
| in namespace std, namespace std::tr1, and namespace __gnu_cxx |
| so that -fvisibility options work. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--enable-libstdcxx-pch</code></term> |
| <listitem><para>In 3.4 and later, tries to turn on the generation of |
| stdc++.h.gch, a pre-compiled file including all the standard |
| C++ includes. If enabled (as by default), and the compiler |
| seems capable of passing the simple sanity checks thrown at |
| it, try to build stdc++.h.gch as part of the make process. |
| In addition, this generated file is used later on (by appending <code> |
| --include bits/stdc++.h </code> to CXXFLAGS) when running the |
| testsuite. |
| </para> |
| </listitem></varlistentry> |
| |
| <varlistentry><term><code>--disable-hosted-libstdcxx</code></term> |
| <listitem> |
| <para> |
| By default, a complete <emphasis>hosted</emphasis> C++ library is |
| built. The C++ Standard also describes a |
| <emphasis>freestanding</emphasis> environment, in which only a |
| minimal set of headers are provided. This option builds such an |
| environment. |
| </para> |
| </listitem></varlistentry> |
| </variablelist> |
| |
| |
| </sect1> |