dnl @synopsis FANG_CXX_ATTRIBUTE_VISIBILITY
dnl
dnl Checking for visibility attributes, "hidden" and "default"
dnl New since gcc-4.0.
dnl Define HAVE_ATTRIBUTE_VISIBILITY_HIDDEN if supported.  
dnl Define HAVE_ATTRIBUTE_VISIBILITY_DEFAULT if supported.  
dnl
dnl @category Cxx
dnl @version 2006-05-08
dnl @author David Fang <address@hidden>
dnl @license AllPermissive
dnl
AC_DEFUN([FANG_CXX_ATTRIBUTE_VISIBILITY],
[
AC_LANG_PUSH(C++)
saved_CXXFLAGS=$CXXFLAGS
CXXFLAGS="$saved_CXXFLAGS -Werror"
dnl check for __visibility__(("hidden"))
AC_CACHE_CHECK([whether compiler accepts __attribute__((visibility("hidden")))],
[fang_cv_cxx_attribute_visibility_hidden],
	AC_COMPILE_IFELSE(
		AC_LANG_PROGRAM(
		[struct __attribute__((visibility("hidden"))) foo {
			foo() { }
			~foo() { }
		};],
		[foo bar;]),
		[fang_cv_cxx_attribute_visibility_hidden=yes],
		[fang_cv_cxx_attribute_visibility_hidden=no]
	)
)
if test "$fang_cv_cxx_attribute_visibility_hidden" = "yes"; then
AC_DEFINE(HAVE_ATTRIBUTE_VISIBILITY_HIDDEN, [],
        [True if compiler supports __attribute__((visibility("hidden"))) ])
fi
dnl check for __visibility__(("default"))
AC_CACHE_CHECK([whether compiler accepts __attribute__((visibility("default")))],
[fang_cv_cxx_attribute_visibility_default],
	AC_COMPILE_IFELSE(
		AC_LANG_PROGRAM(
		[struct __attribute__((visibility("default"))) foo {
			foo() { }
			~foo() { }
		};],
		[foo bar;]),
		[fang_cv_cxx_attribute_visibility_default=yes],
		[fang_cv_cxx_attribute_visibility_default=no]
	)
)
if test "$fang_cv_cxx_attribute_visibility_default" = "yes"; then
AC_DEFINE(HAVE_ATTRIBUTE_VISIBILITY_DEFAULT, [],
        [True if compiler supports __attribute__((visibility("default"))) ])
fi
dnl restore flags and language
CXXFLAGS=$saved_CXXFLAGS
AC_LANG_POP(C++)
])dnl