1dnl Copyright (C) 2005, 2008 Free Software Foundation, Inc. 2dnl Copyright (C) 2009 Monty Taylor 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7dnl From Bruno Haible. 8 9dnl Tests whether the compiler supports the command-line option 10dnl -fvisibility=hidden and the function and variable attributes 11dnl __attribute__((__visibility__("hidden"))) and 12dnl __attribute__((__visibility__("default"))). 13dnl Does *not* test for __visibility__("protected") - which has tricky 14dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on 15dnl MacOS X. 16dnl Does *not* test for __visibility__("internal") - which has processor 17dnl dependent semantics. 18dnl Does *not* test for #pragma GCC visibility push(hidden) - which is 19dnl "really only recommended for legacy code". 20dnl Set the variable CFLAG_VISIBILITY. 21dnl Defines and sets the variable HAVE_VISIBILITY. 22 23AC_DEFUN([PANDORA_VISIBILITY], 24[ 25 AC_REQUIRE([AC_PROG_CC]) 26 AC_REQUIRE([PANDORA_PLATFORM]) 27 CFLAG_VISIBILITY= 28 HAVE_VISIBILITY=0 29 AS_IF([test -n "$GCC"],[ 30 AC_MSG_CHECKING([for simple visibility declarations]) 31 AC_CACHE_VAL([gl_cv_cc_visibility], [ 32 gl_save_CFLAGS="$CFLAGS" 33 CFLAGS="$CFLAGS -fvisibility=hidden" 34 AC_TRY_COMPILE( 35 [extern __attribute__((__visibility__("hidden"))) int hiddenvar; 36 extern __attribute__((__visibility__("default"))) int exportedvar; 37 extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); 38 extern __attribute__((__visibility__("default"))) int exportedfunc (void);], 39 [], 40 [gl_cv_cc_visibility=yes], 41 [gl_cv_cc_visibility=no]) 42 CFLAGS="$gl_save_CFLAGS"]) 43 AC_MSG_RESULT([$gl_cv_cc_visibility]) 44 if test $gl_cv_cc_visibility = yes; then 45 CFLAG_VISIBILITY="-fvisibility=hidden" 46 HAVE_VISIBILITY=1 47 fi 48 ]) 49 AS_IF([test "x$SUNCC" = "xyes"],[ 50 CFLAG_VISIBILITY="-xldscope=hidden" 51 HAVE_VISIBILITY=1 52 ]) 53 AC_SUBST([CFLAG_VISIBILITY]) 54 AC_SUBST([HAVE_VISIBILITY]) 55 AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], 56 [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) 57]) 58