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d9a9e182 AW |
1 | # visibility.m4 serial 2 (gettext-0.18) |
2 | dnl Copyright (C) 2005, 2008 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 | AC_DEFUN([gl_VISIBILITY], | |
24 | [ | |
25 | AC_REQUIRE([AC_PROG_CC]) | |
26 | CFLAG_VISIBILITY= | |
27 | HAVE_VISIBILITY=0 | |
28 | if test -n "$GCC"; then | |
29 | AC_MSG_CHECKING([for simple visibility declarations]) | |
30 | AC_CACHE_VAL([gl_cv_cc_visibility], [ | |
31 | gl_save_CFLAGS="$CFLAGS" | |
32 | CFLAGS="$CFLAGS -fvisibility=hidden" | |
33 | AC_TRY_COMPILE( | |
34 | [extern __attribute__((__visibility__("hidden"))) int hiddenvar; | |
35 | extern __attribute__((__visibility__("default"))) int exportedvar; | |
36 | extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); | |
37 | extern __attribute__((__visibility__("default"))) int exportedfunc (void);], | |
38 | [], | |
39 | [gl_cv_cc_visibility=yes], | |
40 | [gl_cv_cc_visibility=no]) | |
41 | CFLAGS="$gl_save_CFLAGS"]) | |
42 | AC_MSG_RESULT([$gl_cv_cc_visibility]) | |
43 | if test $gl_cv_cc_visibility = yes; then | |
44 | CFLAG_VISIBILITY="-fvisibility=hidden" | |
45 | HAVE_VISIBILITY=1 | |
46 | fi | |
47 | fi | |
48 | AC_SUBST([CFLAG_VISIBILITY]) | |
49 | AC_SUBST([HAVE_VISIBILITY]) | |
50 | AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], | |
51 | [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) | |
52 | ]) |