1 # visibility.m4 serial 4 (gettext-0.18.2) 2 dnl Copyright (C) 2005, 2008, 2010-2011 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 dnl Modified to fit with PCRE build environment by Cristian Rodrguez. 24 25 AC_DEFUN([PCRE_VISIBILITY], 26 [ 27 AC_REQUIRE([AC_PROG_CC]) 28 VISIBILITY_CFLAGS= 29 VISIBILITY_CXXFLAGS= 30 HAVE_VISIBILITY=0 31 if test -n "$GCC"; then 32 dnl First, check whether -Werror can be added to the command line, or 33 dnl whether it leads to an error because of some other option that the 34 dnl user has put into $CC $CFLAGS $CPPFLAGS. 35 AC_MSG_CHECKING([whether the -Werror option is usable]) 36 AC_CACHE_VAL([pcre_cv_cc_vis_werror], [ 37 pcre_save_CFLAGS="$CFLAGS" 38 CFLAGS="$CFLAGS -Werror" 39 AC_COMPILE_IFELSE( 40 [AC_LANG_PROGRAM([[]], [[]])], 41 [pcre_cv_cc_vis_werror=yes], 42 [pcre_cv_cc_vis_werror=no]) 43 CFLAGS="$pcre_save_CFLAGS"]) 44 AC_MSG_RESULT([$pcre_cv_cc_vis_werror]) 45 dnl Now check whether visibility declarations are supported. 46 AC_MSG_CHECKING([for simple visibility declarations]) 47 AC_CACHE_VAL([pcre_cv_cc_visibility], [ 48 pcre_save_CFLAGS="$CFLAGS" 49 CFLAGS="$CFLAGS -fvisibility=hidden" 50 dnl We use the option -Werror and a function dummyfunc, because on some 51 dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning 52 dnl "visibility attribute not supported in this configuration; ignored" 53 dnl at the first function definition in every compilation unit, and we 54 dnl don't want to use the option in this case. 55 if test $pcre_cv_cc_vis_werror = yes; then 56 CFLAGS="$CFLAGS -Werror" 57 fi 58 AC_COMPILE_IFELSE( 59 [AC_LANG_PROGRAM( 60 [[extern __attribute__((__visibility__("hidden"))) int hiddenvar; 61 extern __attribute__((__visibility__("default"))) int exportedvar; 62 extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); 63 extern __attribute__((__visibility__("default"))) int exportedfunc (void); 64 void dummyfunc (void) {} 65 ]], 66 [[]])], 67 [pcre_cv_cc_visibility=yes], 68 [pcre_cv_cc_visibility=no]) 69 CFLAGS="$pcre_save_CFLAGS"]) 70 AC_MSG_RESULT([$pcre_cv_cc_visibility]) 71 if test $pcre_cv_cc_visibility = yes; then 72 VISIBILITY_CFLAGS="-fvisibility=hidden" 73 VISIBILITY_CXXFLAGS="-fvisibility=hidden -fvisibility-inlines-hidden" 74 HAVE_VISIBILITY=1 75 AC_DEFINE(PCRE_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 76 AC_DEFINE(PCRE_EXP_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible]) 77 AC_DEFINE(PCRE_EXP_DATA_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible]) 78 AC_DEFINE(PCREPOSIX_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 79 AC_DEFINE(PCREPOSIX_EXP_DEFN, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 80 AC_DEFINE(PCRECPP_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 81 AC_DEFINE(PCRECPP_EXP_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible]) 82 fi 83 fi 84 AC_SUBST([VISIBILITY_CFLAGS]) 85 AC_SUBST([VISIBILITY_CXXFLAGS]) 86 AC_SUBST([HAVE_VISIBILITY]) 87 AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], 88 [Define to 1 if the compiler supports simple visibility declarations.]) 89 ]) 90
