kc3-lang/libiconv/libcharset/m4/visibility.m4

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• Hash : 05b4c440
  Author :
  Date : 2005-07-25T12:02:41
  

  Support for controlling the exported symbols of the shared library.
  

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• libcharset/m4/visibility.m4

• # visibility.m4 serial 1 (gettext-0.15)
  dnl Copyright (C) 2005 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
  dnl with or without modifications, as long as this notice is preserved.
  
  dnl From Bruno Haible.
  
  dnl Tests whether the compiler supports the command-line option
  dnl -fvisibility=hidden and the function and variable attributes
  dnl __attribute__((__visibility__("hidden"))) and
  dnl __attribute__((__visibility__("default"))).
  dnl Does *not* test for __visibility__("protected") - which has tricky
  dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
  dnl MacOS X.
  dnl Does *not* test for __visibility__("internal") - which has processor
  dnl dependent semantics.
  dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
  dnl "really only recommended for legacy code".
  dnl Set the variable CFLAG_VISIBILITY.
  dnl Defines and sets the variable HAVE_VISIBILITY.
  
  AC_DEFUN([gl_VISIBILITY],
  [
    AC_REQUIRE([AC_PROG_CC])
    CFLAG_VISIBILITY=
    HAVE_VISIBILITY=0
    if test -n "$GCC"; then
      AC_MSG_CHECKING([for simple visibility declarations])
      AC_CACHE_VAL(gl_cv_cc_visibility, [
        gl_save_CFLAGS="$CFLAGS"
        CFLAGS="$CFLAGS -fvisibility=hidden"
        AC_TRY_COMPILE(
          [extern __attribute__((__visibility__("hidden"))) int hiddenvar;
           extern __attribute__((__visibility__("default"))) int exportedvar;
           extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
           extern __attribute__((__visibility__("default"))) int exportedfunc (void);],
          [],
          gl_cv_cc_visibility=yes,
          gl_cv_cc_visibility=no)
        CFLAGS="$gl_save_CFLAGS"])
      AC_MSG_RESULT([$gl_cv_cc_visibility])
      if test $gl_cv_cc_visibility = yes; then
        CFLAG_VISIBILITY="-fvisibility=hidden"
        HAVE_VISIBILITY=1
      fi
    fi
    AC_SUBST([CFLAG_VISIBILITY])
    AC_SUBST([HAVE_VISIBILITY])
    AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY],
      [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])
  ])
  

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