[gcc.git] / libstdc++-v3 / docs / html / configopts.html

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<H1 CLASS="centered"><A NAME="top">Interesting <TT>configure</TT>
options</A></H1>

<P>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>.


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<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
   all have opposite forms as well</A>
   (enable/disable and with/without).  The defaults are for current
   development sources.
</P>
<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:<TT>  ./configure --help</TT>

<DL>
 <DT><TT>--enable-multilib  </TT>[default]
 <DD><P>This is part of the generic multilib support for building cross
        compilers.  As such, targets like &quot;powerpc-elf&quot; will have
        libstdc++ built many different ways:  &quot;-msoft-float&quot;
        and not, etc.  A different libstdc++ will be built for each of
        the different multilib versions.  This option is on by default.
     </P>

 <DT><TT>--enable-debug  </TT>
 <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 <TT>-O2</TT> 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.
     </P>

 <DT><TT>--enable-cstdio  </TT>
 <DD><P>This is an abbreviated form of <TT>'--enable-cstdio=stdio'</TT>
        (described next).
     </P>

 <DT><TT>--enable-cstdio=LIB  </TT>
 <DD><P>Select a target-specific I/O package.  As of libstdc++-v3
        snapshot 2.91, 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 &quot;C&quot;
	abstraction.  The default is 'stdio'.
     </P>

 <DT><TT>--enable-clocale  </TT>
 <DD><P>This is an abbreviated form of <TT>'--enable-clocale=generic'</TT>
        (described next).
     </P>

 <DT><TT>--enable-clocale=MODEL  </TT>
 <DD><P>Select a target-specific underlying locale package. The
        choices are 'gnu' to specify an X/Open (IEEE Std. 1003.1-200x)
        model based on langinfo/iconv (from <A
        HREF="http://sources.redhat.com/glibc/">glibc</A>, the GNU C
        library), or 'generic' to use a generic &quot;C&quot;
        abstraction which consists of "C" locale info.  The default is
        'generic'.
     </P>

 <DT><TT>--enable-long-long  </TT>
 <DD><P>The &quot;long long&quot; type was introduced in C99.  It is
        provided as a GNU extension to C++98 in g++.  This flag builds
        support for &quot;long long&quot; into the library
        (specialized templates and the like). This option is off by
        default:  if enabled, users will have to either use the
        new-style &quot;C&quot; headers by default (ie cmath not math.h)
        or add appropriate compile-time flags to all compile lines to
        allow &quot;C&quot; visibility of this feature (on GNU/Linux,
        the flag is -D_ISOC99_SOURCE).
     </P>

 <DT><TT>--enable-cheaders=OPTION  </TT>
 <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>

 <DT><TT>--enable-threads  </TT>
 <DD><P>This is an abbreviated form of <TT>'--enable-threads=yes'</TT>
        (described next).
     </P>

 <DT><TT>--enable-threads=LIB  </TT>
 <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.
     </P>

 <DT><TT>--enable-version-specific-runtime-libs  </TT>
 <DD><P>Specify that run-time libraries should be installed in the
       compiler-specific subdirectory (i.e.,
       <TT>$(libdir)/gcc-lib/$(target_alias)/$(gcc_version)</TT>)
       instead of <TT>$(libdir)</TT>.  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
       <TT>$(libdir)/gcc-lib/$(target_alias)/$(gcc_version)/include/g++</TT>,
       unless you also specify
       <TT>--with-gxx-include-dir=_dirname_</TT> during configuration.
     </P>


 <DT><TT>--with-gxx-include-dir=&lt;include-files dir&gt;</TT>
 <DD><P>Adds support for named libstdc++ include directory.  For instance,
        the following puts all the libstdc++ headers into a directory
        called &quot;2.97-20001008&quot; instead of the usual
        &quot;g++-v3&quot;.
        <PRE>
   --with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</PRE>
     </P>

 <DT><TT>--enable-cxx-flags=FLAGS</TT>
 <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
        <PRE>
  --enable-cxx-flags='-fsquangle -fvtable-gc -ansi'</PRE>
        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.
     </P>
     <P>The advantage of --enable-cxx-flags over setting CXXFLAGS in
        the 'make' environment is that, if libgcc is automatically
        rebuilt, the same flags will be used when compiling those files
        as well, so that everything matches.
     </P>
     <P>Fun flags to try might include combinations of
        <PRE>
  -fstrict-aliasing
  -fnew-abi
  -fnew-exceptions
  -ffunction-sections
  -fvtable-gc</PRE>
        and -fno- forms of the same.  Tell us (the mailing list) if
        you discover more!
     </P>

 <DT><TT>--enable-c-mbchar  </TT>[default]
 <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. Default is on, but the <TT>--enable-c_stdio=stdio </TT>
        option currently turns it off.
     </P>
</DL>
</P>
<P>Return <A HREF="#top">to the top of the page</A> or
   <A HREF="http://gcc.gnu.org/libstdc++/">to the homepage</A>.
</P>


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$Id: configopts.html,v 1.4 2001/01/21 09:36:09 pme Exp $
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b2dad0e3 BK	1	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
	2	<HTML>
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c0ed1dea	4	<META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)">
d73b0bcf	5	<META NAME="KEYWORDS" CONTENT="libstdc++, libstdc++-v3, GCC, g++">
b2dad0e3 BK	6	<META NAME="DESCRIPTION" CONTENT="Configuration options for libstdc++-v3.">
	7	<META NAME="GENERATOR" CONTENT="vi and eight fingers">
	8	<TITLE>libstdc++-v3 configure options</TITLE>
b2dad0e3	9	<LINK REL=StyleSheet HREF="lib3styles.css">
0214010c	10	<!-- $Id: configopts.html,v 1.4 2001/01/21 09:36:09 pme Exp $ -->
b2dad0e3 BK	11	</HEAD>
	12	<BODY>
	13
	14	<H1 CLASS="centered"><A NAME="top">Interesting <TT>configure</TT>
	15	options</A></H1>
	16
	17	<P>The latest version of this document is always available at
bfcafa4f PE	18	<A HREF="http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html">
bfcafa4f PE	19	http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html</A>.
b2dad0e3 BK	20	</P>
b2dad0e3 BK	21
bfcafa4f	22	<P>To the <A HREF="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</A>.
b2dad0e3 BK	23
	24
	25	<!-- ####################################################### -->
	26	<HR>
	27	<P>Here are some of the non-obvious options to libstdc++'s configure.
	28	Keep in mind that
dcfa0bc8	29	<!-- This SECnn should be the "Choosing Package Options" section. -->
c0ed1dea	30	<A HREF="http://sources.redhat.com/autoconf/autoconf.html#SEC74">they
b2dad0e3	31	all have opposite forms as well</A>
bfcafa4f PE	32	(enable/disable and with/without). The defaults are for current
bfcafa4f PE	33	development sources.
60ade935 PE	34	</P>
60ade935 PE	35	<P>The canonical way to find out the configure options that are
8901ac21	36	available for a given set of libstdc++ sources is to go to the
60ade935	37	source directory and then type:<TT> ./configure --help</TT>
8901ac21	38
b2dad0e3 BK	39	<DL>
b2dad0e3 BK	40	<DT><TT>--enable-multilib </TT>[default]
60ade935 PE	41	<DD><P>This is part of the generic multilib support for building cross
	42	compilers. As such, targets like "powerpc-elf" will have
	43	libstdc++ built many different ways: "-msoft-float"
	44	and not, etc. A different libstdc++ will be built for each of
	45	the different multilib versions. This option is on by default.
b2dad0e3 BK	46	</P>
	47
	48	<DT><TT>--enable-debug </TT>
	49	<DD><P>The configure script will automatically detect the highest level
	50	of optimization that the compiler in use can use (certain
	51	versions of g++ will ICE if given the <TT>-O2</TT> option, but
	52	this is fixed in later versions of the compiler). This --enable
	53	flag will disable all optimizations and instruct the compiler to
	54	emit as much extra debugging information as it can, for use
	55	inside GDB.
	56	</P>
	57
0505b046	58	<DT><TT>--enable-cstdio </TT>
36e40658	59	<DD><P>This is an abbreviated form of <TT>'--enable-cstdio=stdio'</TT>
b2dad0e3 BK	60	(described next).
	61	</P>
	62
	63	<DT><TT>--enable-cstdio=LIB </TT>
	64	<DD><P>Select a target-specific I/O package. As of libstdc++-v3
36e40658	65	snapshot 2.91, the choices are 'libio' to specify the GNU
b2dad0e3	66	I/O package (from
c0ed1dea	67	<A HREF="http://sources.redhat.com/glibc/">glibc</A>, the
0505b046 PE	68	GNU C library), or 'stdio' to use a generic "C"
0505b046 PE	69	abstraction. The default is 'stdio'.
b2dad0e3 BK	70	</P>
b2dad0e3 BK	71
0214010c BK	72	<DT><TT>--enable-clocale </TT>
	73	<DD><P>This is an abbreviated form of <TT>'--enable-clocale=generic'</TT>
	74	(described next).
	75	</P>
	76
	77	<DT><TT>--enable-clocale=MODEL </TT>
	78	<DD><P>Select a target-specific underlying locale package. The
	79	choices are 'gnu' to specify an X/Open (IEEE Std. 1003.1-200x)
	80	model based on langinfo/iconv (from <A
	81	HREF="http://sources.redhat.com/glibc/">glibc</A>, the GNU C
	82	library), or 'generic' to use a generic "C"
	83	abstraction which consists of "C" locale info. The default is
	84	'generic'.
	85	</P>
	86
8bd636c5	87	<DT><TT>--enable-long-long </TT>
b2dad0e3 BK	88	<DD><P>The "long long" type was introduced in C99. It is
b2dad0e3 BK	89	provided as a GNU extension to C++98 in g++. This flag builds
36e40658 BK	90	support for "long long" into the library
36e40658 BK	91	(specialized templates and the like). This option is off by
0505b046 PE	92	default: if enabled, users will have to either use the
	93	new-style "C" headers by default (ie cmath not math.h)
	94	or add appropriate compile-time flags to all compile lines to
	95	allow "C" visibility of this feature (on GNU/Linux,
	96	the flag is -D_ISOC99_SOURCE).
b2dad0e3	97	</P>
b2dad0e3	98
e3123ab3 BK	99	<DT><TT>--enable-cheaders=OPTION </TT>
	100	<DD><P>This allows the user to define what kind of C headers are
	101	used. Options are: c, c_std, and c_shadow. These correspond
	102	to the source directory's include/c, include/c_std, and
	103	include/c_shadow directories.
	104	The default is c_std.
99246c90 PE	105	</P>
99246c90 PE	106
b2dad0e3 BK	107	<DT><TT>--enable-threads </TT>
	108	<DD><P>This is an abbreviated form of <TT>'--enable-threads=yes'</TT>
	109	(described next).
	110	</P>
	111
	112	<DT><TT>--enable-threads=LIB </TT>
36e40658	113	<DD><P>Select a threading library. As of libstdc++-v3 snapshot 2.91,
b2dad0e3 BK	114	the choices are:
	115	'yes' for some kind of default (hmmmmm);
	116	'decosf1', 'irix', 'mach', 'os2', 'posix'/'pthreads'
	117	(same thing),
	118	'solaris', 'win32', 'dce', or 'vxworks' to select the
	119	corresponding interface;
	120	and 'single', 'no', or 'none' for the null-case,
	121	single-threaded library.
	122	</P>
	123	<P>All of this is currently undergoing a lot of changes. As of
36e40658	124	2.91, 'single' and 'posix' are the only implemented
0505b046	125	models. Default is single.
b2dad0e3 BK	126	</P>
b2dad0e3 BK	127
1ac41449 MH	128	<DT><TT>--enable-version-specific-runtime-libs </TT>
	129	<DD><P>Specify that run-time libraries should be installed in the
	130	compiler-specific subdirectory (i.e.,
	131	<TT>$(libdir)/gcc-lib/$(target_alias)/$(gcc_version)</TT>)
	132	instead of <TT>$(libdir)</TT>. This option is useful if you
	133	intend to use several versions of gcc in parallel. In addition,
	134	libstdc++'s include files will be installed in
	135	<TT>$(libdir)/gcc-lib/$(target_alias)/$(gcc_version)/include/g++</TT>,
	136	unless you also specify
	137	<TT>--with-gxx-include-dir=_dirname_</TT> during configuration.
1fd2f510 BK	138	</P>
1fd2f510 BK	139
1ac41449	140
60ade935 PE	141	<DT><TT>--with-gxx-include-dir=<include-files dir></TT>
	142	<DD><P>Adds support for named libstdc++ include directory. For instance,
	143	the following puts all the libstdc++ headers into a directory
	144	called "2.97-20001008" instead of the usual
	145	"g++-v3".
	146	<PRE>
	147	--with-gxx-include-dir=/foo/H-x86-gcc-3-c-gxx-inc/include/2.97-20001008</PRE>
1fd2f510 BK	148	</P>
1fd2f510 BK	149
dcfa0bc8	150	<DT><TT>--enable-cxx-flags=FLAGS</TT>
b2dad0e3 BK	151	<DD><P>With this option, you can pass a string of -f (functionality)
	152	flags to the compiler to use when building libstdc++. FLAGS
	153	is a quoted string of options, like
	154	<PRE>
dcfa0bc8	155	--enable-cxx-flags='-fsquangle -fvtable-gc -ansi'</PRE>
b2dad0e3 BK	156	Note that the flags don't necessarily have to all be -f flags,
	157	as shown, but usually those are the ones that will make sense
	158	for experimentation and configure-time overriding.
	159	</P>
dcfa0bc8	160	<P>The advantage of --enable-cxx-flags over setting CXXFLAGS in
b2dad0e3 BK	161	the 'make' environment is that, if libgcc is automatically
	162	rebuilt, the same flags will be used when compiling those files
	163	as well, so that everything matches.
	164	</P>
	165	<P>Fun flags to try might include combinations of
	166	<PRE>
	167	-fstrict-aliasing
	168	-fnew-abi
	169	-fnew-exceptions
	170	-ffunction-sections
	171	-fvtable-gc</PRE>
	172	and -fno- forms of the same. Tell us (the mailing list) if
	173	you discover more!
	174	</P>
58fdec72	175
36e40658 BK	176	<DT><TT>--enable-c-mbchar </TT>[default]
	177	<DD><P>Certain template specializations are required for wide
	178	character conversion support. This is tricky and currently
	179	changing rapidly, and can cause problems on new platforms.
	180	Disabling wide character specializations is useful for initial
	181	porting steps, but builds only a subset of what is required by
	182	ISO. Default is on, but the <TT>--enable-c_stdio=stdio </TT>
	183	option currently turns it off.
58fdec72	184	</P>
b2dad0e3 BK	185	</DL>
b2dad0e3 BK	186	</P>
c0ed1dea	187	<P>Return <A HREF="#top">to the top of the page</A> or
bfcafa4f	188	<A HREF="http://gcc.gnu.org/libstdc++/">to the homepage</A>.
b2dad0e3 BK	189	</P>
	190
	191
	192	<!-- ####################################################### -->
	193
	194	<HR>
	195	<P CLASS="fineprint"><EM>
0214010c	196	$Id: configopts.html,v 1.4 2001/01/21 09:36:09 pme Exp $
b2dad0e3 BK	197	</EM></P>
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