1 # visibility.m4 serial 1 (gettext-0.15) 2 dnl Copyright (C) 2005 Free Software Foundation, Inc. 3 dnl This file is free software; the Free Software Foundation 4 dnl gives unlimited permission to copy and/or distribute it, 5 dnl with or without modifications, as long as this notice is preserved. 6 7 dnl From Bruno Haible. 8 9 dnl Tests whether the compiler supports the command-line option 10 dnl -fvisibility=hidden and the function and variable attributes 11 dnl __attribute__((__visibility__("hidden"))) and 12 dnl __attribute__((__visibility__("default"))). 13 dnl Does *not* test for __visibility__("protected") - which has tricky 14 dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on 15 dnl MacOS X. 16 dnl Does *not* test for __visibility__("internal") - which has processor 17 dnl dependent semantics. 18 dnl Does *not* test for #pragma GCC visibility push(hidden) - which is 19 dnl "really only recommended for legacy code". 20 dnl Set the variable CFLAG_VISIBILITY. 21 dnl Defines and sets the variable HAVE_VISIBILITY. 22 23 AC_DEFUN([gl_VISIBILITY], 24 [ 25 AC_REQUIRE([AC_PROG_CC]) 26 CFLAG_VISIBILITY= 27 HAVE_VISIBILITY=0 28 if test -n "$GCC"; then 29 AC_MSG_CHECKING([for simple visibility declarations]) 30 AC_CACHE_VAL(gl_cv_cc_visibility, [ 31 gl_save_CFLAGS="$CFLAGS" 32 CFLAGS="$CFLAGS -fvisibility=hidden" 33 AC_TRY_COMPILE( 34 [extern __attribute__((__visibility__("hidden"))) int hiddenvar; 35 extern __attribute__((__visibility__("default"))) int exportedvar; 36 extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); 37 extern __attribute__((__visibility__("default"))) int exportedfunc (void);], 38 [], 39 gl_cv_cc_visibility=yes, 40 gl_cv_cc_visibility=no) 41 CFLAGS="$gl_save_CFLAGS"]) 42 AC_MSG_RESULT([$gl_cv_cc_visibility]) 43 if test $gl_cv_cc_visibility = yes; then 44 CFLAG_VISIBILITY="-fvisibility=hidden" 45 HAVE_VISIBILITY=1 46 fi 47 fi 48 AC_SUBST([CFLAG_VISIBILITY]) 49 AC_SUBST([HAVE_VISIBILITY]) 50 AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], 51 [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) 52 ]) 53
