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1 | # visibility.m4 serial 3 (gettext-0.18) |
2 | dnl Copyright (C) 2005, 2008-2010 Free Software Foundation, Inc. | |
d9a9e182 AW |
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 | |
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29 | dnl First, check whether -Werror can be added to the command line, or |
30 | dnl whether it leads to an error because of some other option that the | |
31 | dnl user has put into $CC $CFLAGS $CPPFLAGS. | |
32 | AC_MSG_CHECKING([whether the -Werror option is usable]) | |
33 | AC_CACHE_VAL([gl_cv_cc_vis_werror], [ | |
34 | gl_save_CFLAGS="$CFLAGS" | |
35 | CFLAGS="$CFLAGS -Werror" | |
36 | AC_TRY_COMPILE([], [], | |
37 | [gl_cv_cc_vis_werror=yes], | |
38 | [gl_cv_cc_vis_werror=no]) | |
39 | CFLAGS="$gl_save_CFLAGS"]) | |
40 | AC_MSG_RESULT([$gl_cv_cc_vis_werror]) | |
41 | dnl Now check whether visibility declarations are supported. | |
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42 | AC_MSG_CHECKING([for simple visibility declarations]) |
43 | AC_CACHE_VAL([gl_cv_cc_visibility], [ | |
44 | gl_save_CFLAGS="$CFLAGS" | |
45 | CFLAGS="$CFLAGS -fvisibility=hidden" | |
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46 | dnl We use the option -Werror and a function dummyfunc, because on some |
47 | dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning | |
48 | dnl "visibility attribute not supported in this configuration; ignored" | |
49 | dnl at the first function definition in every compilation unit, and we | |
50 | dnl don't want to use the option in this case. | |
51 | if test $gl_cv_cc_vis_werror = yes; then | |
52 | CFLAGS="$CFLAGS -Werror" | |
53 | fi | |
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54 | AC_TRY_COMPILE( |
55 | [extern __attribute__((__visibility__("hidden"))) int hiddenvar; | |
56 | extern __attribute__((__visibility__("default"))) int exportedvar; | |
57 | extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); | |
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58 | extern __attribute__((__visibility__("default"))) int exportedfunc (void); |
59 | void dummyfunc (void) {}], | |
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60 | [], |
61 | [gl_cv_cc_visibility=yes], | |
62 | [gl_cv_cc_visibility=no]) | |
63 | CFLAGS="$gl_save_CFLAGS"]) | |
64 | AC_MSG_RESULT([$gl_cv_cc_visibility]) | |
65 | if test $gl_cv_cc_visibility = yes; then | |
66 | CFLAG_VISIBILITY="-fvisibility=hidden" | |
67 | HAVE_VISIBILITY=1 | |
68 | fi | |
69 | fi | |
70 | AC_SUBST([CFLAG_VISIBILITY]) | |
71 | AC_SUBST([HAVE_VISIBILITY]) | |
72 | AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], | |
73 | [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) | |
74 | ]) |