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Annotation of embedaddon/pcre/m4/pcre_visibility.m4, revision 1.1.1.1

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: ])