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+# visibility.m4 serial 3 (gettext-0.18)
+dnl Copyright (C) 2005, 2008-2010 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl From Bruno Haible.
+dnl Tests whether the compiler supports the command-line option
+dnl -fvisibility=hidden and the function and variable attributes
+dnl __attribute__((__visibility__("hidden"))) and
+dnl __attribute__((__visibility__("default"))).
+dnl Does *not* test for __visibility__("protected") - which has tricky
+dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
+dnl MacOS X.
+dnl Does *not* test for __visibility__("internal") - which has processor
+dnl dependent semantics.
+dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
+dnl "really only recommended for legacy code".
+dnl Set the variable CFLAG_VISIBILITY.
+dnl Defines and sets the variable HAVE_VISIBILITY.
+ if test -n "$GCC"; then
+ dnl First, check whether -Werror can be added to the command line, or
+ dnl whether it leads to an error because of some other option that the
+ dnl user has put into $CC $CFLAGS $CPPFLAGS.
+ AC_MSG_CHECKING([whether the -Werror option is usable])
+ AC_CACHE_VAL([gl_cv_cc_vis_werror], [
+ gl_save_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS -Werror"
+ AC_TRY_COMPILE([], [],
+ [gl_cv_cc_vis_werror=yes],
+ [gl_cv_cc_vis_werror=no])
+ CFLAGS="$gl_save_CFLAGS"])
+ AC_MSG_RESULT([$gl_cv_cc_vis_werror])
+ dnl Now check whether visibility declarations are supported.
+ AC_MSG_CHECKING([for simple visibility declarations])
+ AC_CACHE_VAL([gl_cv_cc_visibility], [
+ gl_save_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS -fvisibility=hidden"
+ dnl We use the option -Werror and a function dummyfunc, because on some
+ dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning
+ dnl "visibility attribute not supported in this configuration; ignored"
+ dnl at the first function definition in every compilation unit, and we
+ dnl don't want to use the option in this case.
+ if test $gl_cv_cc_vis_werror = yes; then
+ CFLAGS="$CFLAGS -Werror"
+ fi
+ [extern __attribute__((__visibility__("hidden"))) int hiddenvar;
+ extern __attribute__((__visibility__("default"))) int exportedvar;
+ extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
+ extern __attribute__((__visibility__("default"))) int exportedfunc (void);
+ void dummyfunc (void) {}],
+ [],
+ [gl_cv_cc_visibility=yes],
+ [gl_cv_cc_visibility=no])
+ CFLAGS="$gl_save_CFLAGS"])
+ AC_MSG_RESULT([$gl_cv_cc_visibility])
+ if test $gl_cv_cc_visibility = yes; then
+ CFLAG_VISIBILITY="-fvisibility=hidden"
+ fi
+ fi
+ [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])