Configure

Configure
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+ When configuring libstdc++, you'll have to configure the entire + gccsrcdir directory. Consider using the + toplevel gcc configuration option + --enable-languages=c++, which saves time by only + building the C++ toolchain. +

+ Here are all of the configure options specific to libstdc++. Keep + in mind that + + they + all have opposite forms as well (enable/disable and + with/without). The defaults are for the current + development sources, which may be different than those + for released versions. +

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:./configure --help. +

--enable-multilib[default]

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. +

--enable-sjlj-exceptions

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. +

--enable-version-specific-runtime-libs

Specify that run-time libraries should be installed in the + compiler-specific subdirectory (i.e., + ${libdir}/gcc-lib/${target_alias}/${gcc_version}) + instead of ${libdir}. 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 + ${libdir}/gcc-lib/${target_alias}/${gcc_version}/include/g++, + unless you also specify + --with-gxx-include-dir=dirname during configuration. +

--with-gxx-include-dir=<include-files dir>

Adds support for named libstdc++ include directory. For instance, + the following puts all the libstdc++ headers into a directory + called "4.4-20090404" instead of the usual + "c++/(version)". +

+   --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/4.4-20090404

--enable-cstdio

This is an abbreviated form of '--enable-cstdio=stdio' + (described next). +

--enable-cstdio=OPTION

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'. This option can change the library ABI. +

--enable-clocale

This is an abbreviated form of '--enable-clocale=generic' + (described next). +

--enable-clocale=OPTION

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 glibc, the GNU C + library), or 'generic' to use a generic "C" + abstraction which consists of "C" locale info. +

If not explicitly specified, the configure proccess tries + to guess the most suitable package from the choices above. The + default is 'generic'. On glibc-based systems of sufficient + vintage (2.3 and newer), 'gnu' is automatically selected. This option + can change the library ABI. +

--enable-libstdcxx-allocator

This is an abbreviated form of + '--enable-libstdcxx-allocator=auto' (described + next). +

--enable-libstdcxx-allocator=OPTION

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, + 'pool' for the SGI pooled allocator or 'bitmap' for a bitmap allocator. + See this page for more information on allocator + extensions. This option + can change the library ABI. +

--enable-cheaders=OPTION

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'. +

--enable-threads

This is an abbreviated form of '--enable-threads=yes' + (described next). +

--enable-threads=OPTION

Select a threading library. A full description is + given in the + general compiler + configuration instructions. This option can change the + library ABI. +

--enable-libstdcxx-time

This is an abbreviated form of + '--enable-libstdcxx-time=yes'(described next). +

--enable-libstdcxx-time=OPTION

Enables link-type checks for the availability of the + clock_gettime clocks, used in the implementation of [time.clock], + and of the nanosleep and sched_yield functions, used in the + implementation of [thread.thread.this] of the current C++0x draft. + The choice OPTION=yes checks for the availability of the facilities + in libc and libposix4. In case of need the latter is also linked + to libstdc++ as part of the build process. OPTION=rt also searches + (and, in case, links) librt. Note that the latter is not always + desirable because, in glibc, for example, in turn it triggers the + linking of libpthread too, which activates locking, a large overhead + for single-thread programs. OPTION=no skips the tests completely. + The default is OPTION=no. +

--enable-libstdcxx-debug

Build separate debug libraries in addition to what is normally built. + By default, the debug libraries are compiled with + CXXFLAGS='-g3 -O0 -fno-inline' + , are installed in ${libdir}/debug, and have the + same names and versioning information as the non-debug + libraries. This option is off by default. +

Note this make command, executed in + the build directory, will do much the same thing, without the + configuration difference and without building everything twice: + make CXXFLAGS='-g3 -O0 -fno-inline' all +

--enable-libstdcxx-debug-flags=FLAGS

This option is only valid when --enable-debug + 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 +

+  --enable-libstdcxx-debug-flags='-g3 -O1 -fno-inline'

--enable-cxx-flags=FLAGS

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 +

+  --enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'

+ 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. +

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. +

Fun flags to try might include combinations of +

+  -fstrict-aliasing
+  -fno-exceptions
+  -ffunction-sections
+  -fvtable-gc

and opposite forms (-fno-) of the same. Tell us (the libstdc++ + mailing list) if you discover more! +

--enable-c99

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 namespace + __gnu_cxx, 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. +

--enable-wchar_t[default]

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. +

--enable-long-long

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. +

--enable-fully-dynamic-string

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. +

--enable-concept-checks

This turns on additional compile-time checks for instantiated + library templates, in the form of specialized templates, + described here. They + can help users discover when they break the rules of the STL, before + their programs run. +

--enable-symvers[=style]

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', + 'darwin-export', and 'sun'. 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. +

--enable-visibility

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. +

--enable-libstdcxx-pch

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 + --include bits/stdc++.h to CXXFLAGS) when running the + testsuite. +

--enable-extern-template[default]

Use extern template to pre-instantiate all required + specializations for certain types defined in the standard libraries. + These types include string and dependents like + char_traits, the templateized io classes, + allocator, and others. + Disabling means that implicit + template generation will be used when compiling these types. By + default, this option is on. This option can change the library ABI. +

--disable-hosted-libstdcxx

+ By default, a complete hosted C++ library is + built. The C++ Standard also describes a + freestanding environment, in which only a + minimal set of headers are provided. This option builds such an + environment. +