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- <meta name="AUTHOR" content="pme@gcc.gnu.org (Phil Edwards)">
- <meta name="KEYWORDS" content="libstdc++, libstdc++-v3, GCC, g++">
- <meta name="DESCRIPTION" content="Configuration options for libstdc++-v3.">
- <meta name="GENERATOR" content="vi and eight fingers">
+ <meta name="AUTHOR" content="pme@gcc.gnu.org (Phil Edwards)" />
+ <meta name="KEYWORDS" content="libstdc++, libstdc++-v3, GCC, g++" />
+ <meta name="DESCRIPTION" content="Configuration options for libstdc++-v3." />
+ <meta name="GENERATOR" content="vi and eight fingers" />
<title>libstdc++-v3 configure options</title>
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<body>
<h1 class="centered"><a name="top">Interesting <code>configure</code>
options</a></h1>
-<p>The latest version of this document is always available at
+<p class="fineprint"><em>
+ The latest version of this document is always available at
<a href="http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html">
http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html</a>.
-</p>
-
-<p>To the <a href="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</a>.
+</em></p>
+<p><em>
+ To the <a href="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</a>.
+</em></p>
<!-- ####################################################### -->
-<hr>
+<hr />
<p>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. -->
- <a href="http://sources.redhat.com/autoconf/autoconf.html#SEC74">they
+ <a href="http://www.gnu.org/manual/autoconf/html_node/Package-Options.html#Package%20Options">they
all have opposite forms as well</a>
(enable/disable and with/without). The defaults are for current
development sources.
<p>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>
+</p>
<dl>
- <dt><code>--enable-multilib </code>[default]
+ <dt><code>--enable-multilib </code>[default]</dt>
<dd><p>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.
</p>
+ </dd>
- <dt><code>--enable-debug </code>
- <dd><p>The configure script will automatically detect the highest
- level of optimization that the compiler in use can use
- (certain versions of g++ will ICE if given the <code>-O2</code>
- option, but this is fixed in later versions of the compiler).
- This --enable flag will disable all optimizations and instruct
- the compiler to emit as much extra debugging information as it
- can, for use inside GDB. Note this make command, executed in
- the build directory, will do much the same thing, without the
- configuration difference:<code>make CXXFLAGS='-g -O0' all</code>
+ <dt><code>--enable-sjlj-exceptions </code></dt>
+ <dd><p>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.
+ </p>
+ </dd>
+
+ <dt><code>--enable-version-specific-runtime-libs </code></dt>
+ <dd><p>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
+ <code>--with-gxx-include-dir=<em>dirname</em></code> during configuration.
</p>
+ </dd>
- <dt><code>--enable-cstdio </code>
+ <dt><code>--with-gxx-include-dir=<include-files dir></code></dt>
+ <dd><p>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)".
+ </p>
+ <pre>
+ --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</pre> </dd>
+
+ <dt><code>--enable-cstdio </code></dt>
<dd><p>This is an abbreviated form of <code>'--enable-cstdio=stdio'</code>
- (described next).
+ (described next). This option can change the library ABI.
</p>
+ </dd>
- <dt><code>--enable-cstdio=LIB </code>
+ <dt><code>--enable-cstdio=OPTION </code></dt>
<dd><p>Select a target-specific I/O package. As of libstdc++-v3
- snapshot 2.91, the choices are 'libio' to specify the GNU
+ snapshot 3.0.96, the choices are 'libio' to specify the GNU
I/O package (from
<a href="http://sources.redhat.com/glibc/">glibc</a>, the
GNU C library), or 'stdio' to use a generic "C"
abstraction. The default is 'stdio'. A longer explanation
is <a href="explanations.html#cstdio">here</a>.
</p>
+ </dd>
- <dt><code>--enable-sjlj-exceptions </code>
- <dd><p>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.
- </p>
-
- <dt><code>--enable-clocale </code>
+ <dt><code>--enable-clocale </code></dt>
<dd><p>This is an abbreviated form of <code>'--enable-clocale=generic'</code>
- (described next).
+ (described next). This option can change the library ABI.
</p>
+ </dd>
- <dt><code>--enable-clocale=MODEL </code>
+ <dt><code>--enable-clocale=OPTION </code></dt>
<dd><p>Select a target-specific underlying locale package. The
- choices are 'ieee_1003.1' to specify an X/Open, Standard Unix
- (IEEE Std. 1003.1-200x) model based on langinfo/iconv/catgets,
+ 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 <A
+ library (langinfo/iconv/gettext) (from <a
href="http://sources.redhat.com/glibc/">glibc</a>, the GNU C
library), or 'generic' to use a generic "C"
- abstraction which consists of "C" locale info. The
- default is 'generic'.
+ abstraction which consists of "C" locale info.
</p>
- <dt><code>--enable-c99 </code>
- <dd><p>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.
- </p>
-
- <dt><code>--enable-long-long </code>
- <dd><p>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).
+ <p>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.
</p>
+ </dd>
- <dt><code>--enable-cheaders=OPTION </code>
+ <dt><code>--enable-cheaders=OPTION </code></dt>
<dd><p>This allows the user to define what kind of C headers are
used. Options are: c, c_std, and c_shadow. These correspond
to the source directory's include/c, include/c_std, and
include/c_shadow directories. The default is c_std.
</p>
+ </dd>
- <dt><code>--enable-threads </code>
+ <dt><code>--enable-threads </code></dt>
<dd><p>This is an abbreviated form of <code>'--enable-threads=yes'</code>
- (described next).
+ (described next). This option can change the library ABI.
</p>
+ </dd>
- <dt><code>--enable-threads=LIB </code>
- <dd><p>Select a threading library. As of libstdc++-v3 snapshot 2.91,
- the choices are:
- 'yes' for some kind of default (hmmmmm);
- 'decosf1', 'irix', 'mach', 'os2', 'posix'/'pthreads'
- (same thing),
- 'solaris', 'win32', 'dce', or 'vxworks' to select the
- corresponding interface;
- and 'single', 'no', or 'none' for the null-case,
- single-threaded library.
- </p>
- <p>All of this is currently undergoing a lot of changes. As of
- 2.91, 'single' and 'posix' are the only implemented
- models. Default is single.
+ <dt><code>--enable-threads=OPTION </code></dt>
+ <dd><p>Select a threading library. A full description is given in the
+ general <a href="http://gcc.gnu.org/install/configure.html">compiler
+ configuration instructions</a>.
</p>
+ </dd>
- <dt><code>--enable-version-specific-runtime-libs </code>
- <dd><p>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
- <code>--with-gxx-include-dir=<em>dirname</em></code> during configuration.
+ <dt><code>--enable-debug </code></dt>
+ <dd><p>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.
+ </p>
+ <p>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>
</p>
+ </dd>
- <dt><code>--with-gxx-include-dir=<include-files dir></code>
- <dd><p>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
- "g++-v3".
- <pre>
- --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</pre>
+ <dt><code>--enable-debug-flags=FLAGS</code></dt>
+
+ <dd><p>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
</p>
+ <pre>
+ --enable-debug-flags='-g3 -O1 -gdwarf-2'</pre>
+ </dd>
- <dt><code>--enable-cxx-flags=FLAGS</code>
+ <dt><code>--enable-cxx-flags=FLAGS</code></dt>
<dd><p>With this option, you can pass a string of -f (functionality)
- flags to the compiler to use when building libstdc++. FLAGS
- is a quoted string of options, like
+ flags to the compiler to use when building libstdc++. This
+ option can change the library ABI. FLAGS is a quoted string of
+ options, like
+ </p>
<pre>
--enable-cxx-flags='-fvtable-gc -fomit-frame-pointer -ansi'</pre>
+ <p>
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.
as well, so that everything matches.
</p>
<p>Fun flags to try might include combinations of
+ </p>
<pre>
-fstrict-aliasing
-fno-exceptions
-ffunction-sections
-fvtable-gc</pre>
- and opposite forms (-fno-) of the same. Tell us (the libstdc++
+ <p>and opposite forms (-fno-) of the same. Tell us (the libstdc++
mailing list) if you discover more!
</p>
+ </dd>
- <dt><code>--enable-c-mbchar </code>[default]
+ <dt><code>--enable-c99 </code></dt>
+ <dd><p>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.
+ </p>
+ </dd>
+
+ <dt><code>--enable-c-mbchar </code>[default]</dt>
<dd><p>Certain template specializations are required for wide
character conversion support. This is tricky and currently
changing rapidly, and can cause problems on new platforms.
Disabling wide character specializations is useful for initial
porting steps, but builds only a subset of what is required by
- ISO. By default, this option is on.
+ ISO. By default, this option is on. This option can change
+ the library ABI.
</p>
+ </dd>
+
+ <dt><code>--enable-long-long </code></dt>
+ <dd><p>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.
+ </p>
+ </dd>
+
+ <dt><code>--enable-concept-checks </code></dt>
+ <dd><p>This turns on additional compile-time checks for instantiated
+ library templates, in the form of specialized templates,
+ <a href="19_diagnostics/howto.html#3">described here</a>. They
+ can help users discover when they break the rules of the STL, before
+ their programs run.
+ </p>
+ </dd>
+
+ <dt><code>--enable-symvers[=style] </code></dt>
+ <dd><p>In 3.1 and later, tries to turn on symbol versioning in the
+ shared library (if a shared library has been requested). The
+ only 'style' currently supported is 'gnu' which requires that
+ a recent version of the GNU linker be in use. With no style
+ given, the configure script will try to guess if the 'gnu'
+ style can be used, and if so, will turn it on. Hopefully
+ people will volunteer to do other 'style' options.
+ </p>
+ </dd>
</dl>
-</p>
<p>Return <a href="#top">to the top of the page</a> or
<a href="http://gcc.gnu.org/libstdc++/">to the libstdc++ homepage</a>.
</p>
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