wxWidgets/acinclude.m4

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dnl ---------------------------------------------------------------------------
dnl
dnl Macros for configure.in for wxWindows by Robert Roebling, Phil Blecker,
dnl Vadim Zeitlin and Ron Lee
dnl
dnl This script is under the wxWindows licence.
dnl
dnl Version: $Id$
dnl ---------------------------------------------------------------------------
dnl ===========================================================================
dnl macros to detect specialty compiler options
dnl ===========================================================================
dnl Figure out if we need to pass -ext o to compiler (MetroWerks)
AC_DEFUN([AC_WX_METROWERKS_EXTO],
[AC_CACHE_CHECK([if the _AC_LANG compiler requires -ext o], wx_cv_[]_AC_LANG_ABBREV[]_exto,
dnl First create an empty conf test
[AC_LANG_CONFTEST([AC_LANG_PROGRAM()])
dnl Now remove .o and .c.o or .cc.o
rm -f conftest.$ac_objext conftest.$ac_ext.o
dnl Now compile the test
AS_IF([AC_TRY_EVAL(ac_compile)],
dnl If the test succeeded look for conftest.c.o or conftest.cc.o
[for ac_file in `(ls conftest.* 2>/dev/null)`; do
case $ac_file in
conftest.$ac_ext.o)
wx_cv_[]_AC_LANG_ABBREV[]_exto="-ext o"
;;
*)
;;
esac
done],
[AC_MSG_FAILURE([cannot figure out if compiler needs -ext o: cannot compile])
]) dnl AS_IF
rm -f conftest.$ac_ext.o conftest.$ac_objext conftest.$ac_ext
]) dnl AC_CACHE_CHECK
if test "x$wx_cv_[]_AC_LANG_ABBREV[]_exto" '!=' "x"; then
if test "[]_AC_LANG_ABBREV[]" = "c"; then
CFLAGS="$wx_cv_[]_AC_LANG_ABBREV[]_exto $CFLAGS"
fi
if test "[]_AC_LANG_ABBREV[]" = "cxx"; then
CXXFLAGS="$wx_cv_[]_AC_LANG_ABBREV[]_exto $CXXFLAGS"
fi
fi
]) dnl AC_DEFUN
dnl Based on autoconf _AC_LANG_COMPILER_GNU
AC_DEFUN([_AC_WX_LANG_COMPILER_XLC],
[AC_CACHE_CHECK([whether we are using the IBM xlC _AC_LANG compiler],
[wx_cv_[]_AC_LANG_ABBREV[]_compiler_xlc],
[AC_TRY_COMPILE([],[#ifndef __xlC__
choke me
#endif
],
[wx_compiler_xlc=yes],
[wx_compiler_xlc=no])
wx_cv_[]_AC_LANG_ABBREV[]_compiler_xlc=$wx_compiler_xlc
])
])
dnl Loosely based on autoconf AC_PROG_CC
AC_DEFUN([AC_WX_PROG_XLCC],
[AC_LANG_PUSH(C)
_AC_WX_LANG_COMPILER_XLC
XLCC=`test $wx_compiler_xlc = yes && echo yes`
AC_LANG_POP(C)
])
dnl Loosely based on autoconf AC_PROG_CXX
AC_DEFUN([AC_WX_PROG_XLCXX],
[AC_LANG_PUSH(C++)
_AC_WX_LANG_COMPILER_XLC
XLCXX=`test $wx_compiler_xlc = yes && echo yes`
AC_LANG_POP(C++)
])
dnl ===========================================================================
dnl Objective-C(++) related macros
dnl ===========================================================================
m4_define([AC_WX_LANG_OBJECTIVEC],
[AC_LANG(C)
ac_ext=m
])
m4_define([AC_WX_LANG_OBJECTIVECPLUSPLUS],
[AC_LANG(C++)
ac_ext=mm
])
dnl ===========================================================================
dnl macros to find the a file in the list of include/lib paths
dnl ===========================================================================
dnl ---------------------------------------------------------------------------
dnl call WX_PATH_FIND_INCLUDES(search path, header name), sets ac_find_includes
dnl to the full name of the file that was found or leaves it empty if not found
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_PATH_FIND_INCLUDES],
[
ac_find_includes=
for ac_dir in $1 /usr/include;
do
if test -f "$ac_dir/$2"; then
ac_find_includes=$ac_dir
break
fi
done
])
dnl ---------------------------------------------------------------------------
dnl call WX_PATH_FIND_LIBRARIES(search path, header name), sets ac_find_libraries
dnl to the full name of the file that was found or leaves it empty if not found
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_PATH_FIND_LIBRARIES],
[
ac_find_libraries=
for ac_dir in $1 /usr/lib;
do
for ac_extension in a so sl dylib; do
if test -f "$ac_dir/lib$2.$ac_extension"; then
ac_find_libraries=$ac_dir
break 2
fi
done
done
])
dnl ---------------------------------------------------------------------------
dnl Path to include, already defined
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_INCLUDE_PATH_EXIST],
[
dnl never add -I/usr/include to the CPPFLAGS
if test "x$1" = "x/usr/include"; then
ac_path_to_include=""
else
echo "$2" | grep "\-I$1" > /dev/null
result=$?
if test $result = 0; then
ac_path_to_include=""
else
ac_path_to_include=" -I$1"
fi
fi
])
dnl ---------------------------------------------------------------------------
dnl Path to link, already defined
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_LINK_PATH_EXIST],
[
echo "$2" | grep "\-L$1" > /dev/null
result=$?
if test $result = 0; then
ac_path_to_link=""
else
ac_path_to_link=" -L$1"
fi
])
dnl ===========================================================================
dnl C++ features test
dnl ===========================================================================
dnl ---------------------------------------------------------------------------
dnl WX_CPP_NEW_HEADERS checks whether the compiler has "new" <iostream> header
dnl or only the old <iostream.h> one - it may be generally assumed that if
dnl <iostream> exists, the other "new" headers (without .h) exist too.
dnl
dnl call WX_CPP_NEW_HEADERS(actiof-if-true, action-if-false)
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_CPP_NEW_HEADERS],
[
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_CHECK_HEADERS(iostream)
if test "$ac_cv_header_iostream" = "yes" ; then
ifelse([$1], , :, [$1])
else
ifelse([$2], , :, [$2])
fi
AC_LANG_RESTORE
])
dnl ---------------------------------------------------------------------------
dnl WX_CPP_BOOL checks whether the C++ compiler has a built in bool type
dnl
dnl call WX_CPP_BOOL - will define HAVE_BOOL if the compiler supports bool
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_CPP_BOOL],
[
AC_CACHE_CHECK([if C++ compiler supports bool], wx_cv_cpp_bool,
[
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE(
[
],
[
bool b = true;
return 0;
],
[
wx_cv_cpp_bool=yes
],
[
wx_cv_cpp_bool=no
]
)
AC_LANG_RESTORE
])
if test "$wx_cv_cpp_bool" = "yes"; then
AC_DEFINE(HAVE_BOOL)
fi
])
dnl ---------------------------------------------------------------------------
dnl WX_CPP_EXPLICIT checks whether the C++ compiler support the explicit
dnl keyword and defines HAVE_EXPLICIT if this is the case
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_CPP_EXPLICIT],
[
AC_CACHE_CHECK([if C++ compiler supports the explicit keyword],
wx_cv_explicit,
[
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
dnl do the test in 2 steps: first check that the compiler knows about the
dnl explicit keyword at all and then verify that it really honours it
AC_TRY_COMPILE(
[
class Foo { public: explicit Foo(int) {} };
],
[
return 0;
],
[
AC_TRY_COMPILE(
[
class Foo { public: explicit Foo(int) {} };
static void TakeFoo(const Foo& foo) { }
],
[
TakeFoo(17);
return 0;
],
wx_cv_explicit=no,
wx_cv_explicit=yes
)
],
wx_cv_explicit=no
)
AC_LANG_RESTORE
])
if test "$wx_cv_explicit" = "yes"; then
AC_DEFINE(HAVE_EXPLICIT)
fi
])
dnl ---------------------------------------------------------------------------
dnl a slightly better AC_C_BIGENDIAN macro which allows cross-compiling
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_C_BIGENDIAN],
[AC_CACHE_CHECK([whether byte ordering is bigendian], ac_cv_c_bigendian,
[ac_cv_c_bigendian=unknown
# See if sys/param.h defines the BYTE_ORDER macro.
AC_TRY_COMPILE([#include <sys/types.h>
#include <sys/param.h>], [
#if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
bogus endian macros
#endif], [# It does; now see whether it defined to BIG_ENDIAN or not.
AC_TRY_COMPILE([#include <sys/types.h>
#include <sys/param.h>], [
#if BYTE_ORDER != BIG_ENDIAN
not big endian
#endif], ac_cv_c_bigendian=yes, ac_cv_c_bigendian=no)])
if test $ac_cv_c_bigendian = unknown; then
AC_TRY_RUN([main () {
/* Are we little or big endian? From Harbison&Steele. */
union
{
long l;
char c[sizeof (long)];
} u;
u.l = 1;
exit (u.c[sizeof (long) - 1] == 1);
}], [ac_cv_c_bigendian=no], [ac_cv_c_bigendian=yes], [ac_cv_c_bigendian=unknown])
fi])
if test $ac_cv_c_bigendian = unknown; then
AC_MSG_WARN([Assuming little-endian target machine - this may be overriden by adding the line "ac_cv_c_bigendian=${ac_cv_c_bigendian='yes'}" to config.cache file])
fi
if test $ac_cv_c_bigendian = yes; then
AC_DEFINE(WORDS_BIGENDIAN)
fi
])
dnl ---------------------------------------------------------------------------
dnl override AC_ARG_ENABLE/WITH to cache the results in .cache file
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_ARG_CACHE_INIT],
[
wx_arg_cache_file="configarg.cache"
echo "loading argument cache $wx_arg_cache_file"
rm -f ${wx_arg_cache_file}.tmp
touch ${wx_arg_cache_file}.tmp
touch ${wx_arg_cache_file}
])
AC_DEFUN([WX_ARG_CACHE_FLUSH],
[
echo "saving argument cache $wx_arg_cache_file"
mv ${wx_arg_cache_file}.tmp ${wx_arg_cache_file}
])
dnl this macro checks for a three-valued command line --with argument:
dnl possible arguments are 'yes', 'no', 'sys', or 'builtin'
dnl usage: WX_ARG_SYS_WITH(option, helpmessage, variable-name)
AC_DEFUN([WX_ARG_SYS_WITH],
[
AC_MSG_CHECKING([for --with-$1])
no_cache=0
AC_ARG_WITH($1, [$2],
[
if test "$withval" = yes; then
ac_cv_use_$1='$3=yes'
elif test "$withval" = no; then
ac_cv_use_$1='$3=no'
elif test "$withval" = sys; then
ac_cv_use_$1='$3=sys'
elif test "$withval" = builtin; then
ac_cv_use_$1='$3=builtin'
else
AC_MSG_ERROR([Invalid value for --with-$1: should be yes, no, sys, or builtin])
fi
],
[
LINE=`grep "$3" ${wx_arg_cache_file}`
if test "x$LINE" != x ; then
eval "DEFAULT_$LINE"
else
no_cache=1
fi
ac_cv_use_$1='$3='$DEFAULT_$3
])
eval "$ac_cv_use_$1"
if test "$no_cache" != 1; then
echo $ac_cv_use_$1 >> ${wx_arg_cache_file}.tmp
fi
if test "$$3" = yes; then
AC_MSG_RESULT(yes)
elif test "$$3" = no; then
AC_MSG_RESULT(no)
elif test "$$3" = sys; then
AC_MSG_RESULT([system version])
elif test "$$3" = builtin; then
AC_MSG_RESULT([builtin version])
else
AC_MSG_ERROR([Invalid value for --with-$1: should be yes, no, sys, or builtin])
fi
])
dnl this macro checks for a command line argument and caches the result
dnl usage: WX_ARG_WITH(option, helpmessage, variable-name)
AC_DEFUN([WX_ARG_WITH],
[
AC_MSG_CHECKING([for --with-$1])
no_cache=0
AC_ARG_WITH($1, [$2],
[
if test "$withval" = yes; then
ac_cv_use_$1='$3=yes'
else
ac_cv_use_$1='$3=no'
fi
],
[
LINE=`grep "$3" ${wx_arg_cache_file}`
if test "x$LINE" != x ; then
eval "DEFAULT_$LINE"
else
no_cache=1
fi
ac_cv_use_$1='$3='$DEFAULT_$3
])
eval "$ac_cv_use_$1"
if test "$no_cache" != 1; then
echo $ac_cv_use_$1 >> ${wx_arg_cache_file}.tmp
fi
if test "$$3" = yes; then
AC_MSG_RESULT(yes)
else
AC_MSG_RESULT(no)
fi
])
dnl like WX_ARG_WITH but uses AC_ARG_ENABLE instead of AC_ARG_WITH
dnl usage: WX_ARG_ENABLE(option, helpmessage, variable-name, enablestring)
dnl
dnl enablestring is a hack and allows to show "checking for --disable-foo"
dnl message when running configure instead of the default "checking for
dnl --enable-foo" one whih is useful for the options enabled by default
AC_DEFUN([WX_ARG_ENABLE],
[
enablestring=$4
AC_MSG_CHECKING([for --${enablestring:-enable}-$1])
no_cache=0
AC_ARG_ENABLE($1, [$2],
[
if test "$enableval" = yes; then
ac_cv_use_$1='$3=yes'
else
ac_cv_use_$1='$3=no'
fi
],
[
LINE=`grep "$3" ${wx_arg_cache_file}`
if test "x$LINE" != x ; then
eval "DEFAULT_$LINE"
else
no_cache=1
fi
ac_cv_use_$1='$3='$DEFAULT_$3
])
eval "$ac_cv_use_$1"
if test "$no_cache" != 1; then
echo $ac_cv_use_$1 >> ${wx_arg_cache_file}.tmp
fi
if test "$$3" = yes; then
AC_MSG_RESULT(yes)
else
AC_MSG_RESULT(no)
fi
])
dnl ===========================================================================
dnl Linker features test
dnl ===========================================================================
dnl ---------------------------------------------------------------------------
dnl WX_VERSIONED_SYMBOLS checks whether the linker can create versioned
dnl symbols. If it can, sets LDFLAGS_VERSIONING to $CXX flags needed to use
dnl version script file named versionfile
dnl
dnl call WX_VERSIONED_SYMBOLS(versionfile)
dnl ---------------------------------------------------------------------------
AC_DEFUN([WX_VERSIONED_SYMBOLS],
[
found_versioning=no
dnl FIXME - doesn't work, Solaris linker doesn't accept wildcards
dnl in the script.
dnl dnl Check for known non-gcc cases:
dnl case "${host}" in
dnl *-*-solaris2* )
dnl if test "x$GCC" != "xyes" ; then
dnl LDFLAGS_VERSIONING="-M $1"
dnl found_versioning=yes
dnl fi
dnl ;;
dnl esac
dnl Generic check for GCC or GCC-like behaviour (Intel C++, GCC):
if test $found_versioning = no ; then
AC_CACHE_CHECK([if the linker accepts --version-script], wx_cv_version_script,
[
echo "VER_1 { *; };" >conftest.sym
echo "int main() { return 0; }" >conftest.cpp
if AC_TRY_COMMAND([
$CXX -o conftest.output $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.cpp
-Wl,--version-script,conftest.sym >/dev/null 2>conftest.stderr]) ; then
if test -s conftest.stderr ; then
wx_cv_version_script=no
else
wx_cv_version_script=yes
fi
else
wx_cv_version_script=no
fi
rm -f conftest.output conftest.stderr conftest.sym conftest.cpp
])
if test $wx_cv_version_script = yes ; then
LDFLAGS_VERSIONING="-Wl,--version-script,$1"
fi
fi
])
dnl ===========================================================================
dnl "3rd party" macros included here because they are not widely available
dnl ===========================================================================
dnl ---------------------------------------------------------------------------
dnl test for availability of iconv()
dnl ---------------------------------------------------------------------------
dnl From Bruno Haible.
AC_DEFUN([AM_ICONV],
[
dnl Some systems have iconv in libc, some have it in libiconv (OSF/1 and
dnl those with the standalone portable GNU libiconv installed).
AC_ARG_WITH([libiconv-prefix],
[ --with-libiconv-prefix=DIR search for libiconv in DIR/include and DIR/lib], [
for dir in `echo "$withval" | tr : ' '`; do
if test -d $dir/include; then CPPFLAGS="$CPPFLAGS -I$dir/include"; fi
if test -d $dir/lib; then LDFLAGS="$LDFLAGS -L$dir/lib"; fi
done
])
AC_CACHE_CHECK(for iconv, am_cv_func_iconv, [
am_cv_func_iconv="no, consider installing GNU libiconv"
am_cv_lib_iconv=no
AC_TRY_LINK([#include <stdlib.h>
#include <iconv.h>],
[iconv_t cd = iconv_open("","");
iconv(cd,NULL,NULL,NULL,NULL);
iconv_close(cd);],
am_cv_func_iconv=yes)
if test "$am_cv_func_iconv" != yes; then
am_save_LIBS="$LIBS"
LIBS="$LIBS -liconv"
AC_TRY_LINK([#include <stdlib.h>
#include <iconv.h>],
[iconv_t cd = iconv_open("","");
iconv(cd,NULL,NULL,NULL,NULL);
iconv_close(cd);],
am_cv_lib_iconv=yes
am_cv_func_iconv=yes)
LIBS="$am_save_LIBS"
fi
])
if test "$am_cv_func_iconv" = yes; then
AC_DEFINE(HAVE_ICONV, 1, [Define if you have the iconv() function.])
AC_CACHE_CHECK([if iconv needs const], wx_cv_func_iconv_const,
AC_TRY_COMPILE([
#include <stdlib.h>
#include <iconv.h>
extern
#ifdef __cplusplus
"C"
#endif
#if defined(__STDC__) || defined(__cplusplus)
size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
#else
size_t iconv();
#endif
],
[],
wx_cv_func_iconv_const="no",
wx_cv_func_iconv_const="yes"
)
)
iconv_const=
if test "x$wx_cv_func_iconv_const" = "xyes"; then
iconv_const="const"
fi
AC_DEFINE_UNQUOTED(ICONV_CONST, $iconv_const,
[Define as const if the declaration of iconv() needs const.])
fi
LIBICONV=
if test "$am_cv_lib_iconv" = yes; then
LIBICONV="-liconv"
fi
AC_SUBST(LIBICONV)
])
dnl ---------------------------------------------------------------------------
dnl AC_SYS_LARGEFILE (partly based on the code from autoconf 2.5x)
dnl ---------------------------------------------------------------------------
dnl WX_SYS_LARGEFILE_TEST
dnl
dnl NB: original autoconf test was checking if compiler supported 6 bit off_t
dnl arithmetic properly but this failed miserably with gcc under Linux
dnl whereas the system still supports 64 bit files, so now simply check
dnl that off_t is big enough
define(WX_SYS_LARGEFILE_TEST,
[typedef struct {
unsigned int field: sizeof(off_t) == 8;
} wxlf;
])
dnl WX_SYS_LARGEFILE_MACRO_VALUE(C-MACRO, VALUE, CACHE-VAR)
define(WX_SYS_LARGEFILE_MACRO_VALUE,
[
AC_CACHE_CHECK([for $1 value needed for large files], [$3],
[
AC_TRY_COMPILE([#define $1 $2
#include <sys/types.h>],
WX_SYS_LARGEFILE_TEST,
[$3=$2],
[$3=no])
]
)
if test "$$3" != no; then
wx_largefile=yes
AC_DEFINE_UNQUOTED([$1], [$$3])
fi
])
dnl AC_SYS_LARGEFILE
dnl ----------------
dnl By default, many hosts won't let programs access large files;
dnl one must use special compiler options to get large-file access to work.
dnl For more details about this brain damage please see:
dnl http://www.sas.com/standards/large.file/x_open.20Mar96.html
AC_DEFUN([AC_SYS_LARGEFILE],
[AC_ARG_ENABLE(largefile,
[ --disable-largefile omit support for large files])
if test "$enable_largefile" != no; then
dnl _FILE_OFFSET_BITS==64 is needed for Linux, Solaris, ...
dnl _LARGE_FILES -- for AIX
wx_largefile=no
WX_SYS_LARGEFILE_MACRO_VALUE(_FILE_OFFSET_BITS, 64, ac_cv_sys_file_offset_bits)
if test "x$wx_largefile" != "xyes"; then
WX_SYS_LARGEFILE_MACRO_VALUE(_LARGE_FILES, 1, ac_cv_sys_large_files)
fi
AC_MSG_CHECKING(if large file support is available)
if test "x$wx_largefile" = "xyes"; then
AC_DEFINE(HAVE_LARGEFILE_SUPPORT)
fi
AC_MSG_RESULT($wx_largefile)
fi
])
dnl Available from the GNU Autoconf Macro Archive at:
dnl http://www.gnu.org/software/ac-archive/htmldoc/ac_cxx_const_cast.html
dnl
AC_DEFUN([AC_CXX_CONST_CAST],
[AC_CACHE_CHECK(whether the compiler supports const_cast<>,
ac_cv_cxx_const_cast,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE(,[int x = 0;const int& y = x;int& z = const_cast<int&>(y);return z;],
ac_cv_cxx_const_cast=yes, ac_cv_cxx_const_cast=no)
AC_LANG_RESTORE
])
if test "$ac_cv_cxx_const_cast" = yes; then
AC_DEFINE(HAVE_CONST_CAST,,[define if the compiler supports const_cast<>])
fi
])
dnl http://www.gnu.org/software/ac-archive/htmldoc/ac_cxx_reinterpret_cast.html
AC_DEFUN([AC_CXX_REINTERPRET_CAST],
[AC_CACHE_CHECK(whether the compiler supports reinterpret_cast<>,
ac_cv_cxx_reinterpret_cast,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE([#include <typeinfo>
class Base { public : Base () {} virtual void f () = 0;};
class Derived : public Base { public : Derived () {} virtual void f () {} };
class Unrelated { public : Unrelated () {} };
int g (Unrelated&) { return 0; }],[
Derived d;Base& b=d;Unrelated& e=reinterpret_cast<Unrelated&>(b);return g(e);],
ac_cv_cxx_reinterpret_cast=yes, ac_cv_cxx_reinterpret_cast=no)
AC_LANG_RESTORE
])
if test "$ac_cv_cxx_reinterpret_cast" = yes; then
AC_DEFINE(HAVE_REINTERPRET_CAST,,
[define if the compiler supports reinterpret_cast<>])
fi
])
dnl and http://www.gnu.org/software/ac-archive/htmldoc/ac_cxx_static_cast.html
AC_DEFUN([AC_CXX_STATIC_CAST],
[AC_CACHE_CHECK(whether the compiler supports static_cast<>,
ac_cv_cxx_static_cast,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE([#include <typeinfo>
class Base { public : Base () {} virtual void f () = 0; };
class Derived : public Base { public : Derived () {} virtual void f () {} };
int g (Derived&) { return 0; }],[
Derived d; Base& b = d; Derived& s = static_cast<Derived&> (b); return g (s);],
ac_cv_cxx_static_cast=yes, ac_cv_cxx_static_cast=no)
AC_LANG_RESTORE
])
if test "$ac_cv_cxx_static_cast" = yes; then
AC_DEFINE(HAVE_STATIC_CAST,, [define if the compiler supports static_cast<>])
fi
])
dnl http://autoconf-archive.cryp.to/ac_cxx_dynamic_cast.html
AC_DEFUN([AC_CXX_DYNAMIC_CAST],
[AC_CACHE_CHECK(whether the compiler supports dynamic_cast<>,
ac_cv_cxx_dynamic_cast,
[AC_LANG_SAVE
AC_LANG_CPLUSPLUS
AC_TRY_COMPILE([#include <typeinfo>
class Base { public : Base () {} virtual void f () = 0;};
class Derived : public Base { public : Derived () {} virtual void f () {} };],[
Derived d; Base& b=d; return dynamic_cast<Derived*>(&b) ? 0 : 1;],
ac_cv_cxx_dynamic_cast=yes, ac_cv_cxx_dynamic_cast=no)
AC_LANG_RESTORE
])
if test "$ac_cv_cxx_dynamic_cast" = yes; then
AC_DEFINE(HAVE_DYNAMIC_CAST,,[define if the compiler supports dynamic_cast<>])
fi
])