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 dnl Adjusted for PCRE2 by PH 25 26 AC_DEFUN([PCRE2_VISIBILITY], 27 [ 28 AC_REQUIRE([AC_PROG_CC]) 29 VISIBILITY_CFLAGS= 30 VISIBILITY_CXXFLAGS= 31 HAVE_VISIBILITY=0 32 if test -n "$GCC"; then 33 dnl First, check whether -Werror can be added to the command line, or 34 dnl whether it leads to an error because of some other option that the 35 dnl user has put into $CC $CFLAGS $CPPFLAGS. 36 AC_MSG_CHECKING([whether the -Werror option is usable]) 37 AC_CACHE_VAL([pcre2_cv_cc_vis_werror], [ 38 pcre2_save_CFLAGS="$CFLAGS" 39 CFLAGS="$CFLAGS -Werror" 40 AC_COMPILE_IFELSE( 41 [AC_LANG_PROGRAM([[]], [[]])], 42 [pcre2_cv_cc_vis_werror=yes], 43 [pcre2_cv_cc_vis_werror=no]) 44 CFLAGS="$pcre2_save_CFLAGS"]) 45 AC_MSG_RESULT([$pcre2_cv_cc_vis_werror]) 46 dnl Now check whether visibility declarations are supported. 47 AC_MSG_CHECKING([for simple visibility declarations]) 48 AC_CACHE_VAL([pcre2_cv_cc_visibility], [ 49 pcre2_save_CFLAGS="$CFLAGS" 50 CFLAGS="$CFLAGS -fvisibility=hidden" 51 dnl We use the option -Werror and a function dummyfunc, because on some 52 dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning 53 dnl "visibility attribute not supported in this configuration; ignored" 54 dnl at the first function definition in every compilation unit, and we 55 dnl don't want to use the option in this case. 56 if test $pcre2_cv_cc_vis_werror = yes; then 57 CFLAGS="$CFLAGS -Werror" 58 fi 59 AC_COMPILE_IFELSE( 60 [AC_LANG_PROGRAM( 61 [[extern __attribute__((__visibility__("hidden"))) int hiddenvar; 62 extern __attribute__((__visibility__("default"))) int exportedvar; 63 extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); 64 extern __attribute__((__visibility__("default"))) int exportedfunc (void); 65 void dummyfunc (void) {} 66 ]], 67 [[]])], 68 [pcre2_cv_cc_visibility=yes], 69 [pcre2_cv_cc_visibility=no]) 70 CFLAGS="$pcre2_save_CFLAGS"]) 71 AC_MSG_RESULT([$pcre2_cv_cc_visibility]) 72 if test $pcre2_cv_cc_visibility = yes; then 73 VISIBILITY_CFLAGS="-fvisibility=hidden" 74 VISIBILITY_CXXFLAGS="-fvisibility=hidden -fvisibility-inlines-hidden" 75 HAVE_VISIBILITY=1 76 AC_DEFINE(PCRE2_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 77 AC_DEFINE(PCRE2_EXP_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible]) 78 AC_DEFINE(PCRE2POSIX_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 79 AC_DEFINE(PCRE2POSIX_EXP_DEFN, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible]) 80 fi 81 fi 82 AC_SUBST([VISIBILITY_CFLAGS]) 83 AC_SUBST([VISIBILITY_CXXFLAGS]) 84 AC_SUBST([HAVE_VISIBILITY]) 85 AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], 86 [Define to 1 if the compiler supports simple visibility declarations.]) 87 ]) 88
