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Annotation of embedaddon/pcre/m4/pcre_visibility.m4, revision 1.1

1.1     ! misho       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 Rodríguez.
        !            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: ])