| 1 | # visibility.m4 serial 2 (gettext-0.18) |
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| 2 | dnl Copyright (C) 2005, 2008 Free Software Foundation, Inc. |
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| 3 | dnl This file is free software; the Free Software Foundation |
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| 4 | dnl gives unlimited permission to copy and/or distribute it, |
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| 5 | dnl with or without modifications, as long as this notice is preserved. |
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| 6 | |
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| 7 | dnl From Bruno Haible. |
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| 8 | |
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| 9 | dnl Tests whether the compiler supports the command-line option |
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| 10 | dnl -fvisibility=hidden and the function and variable attributes |
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| 11 | dnl __attribute__((__visibility__("hidden"))) and |
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| 12 | dnl __attribute__((__visibility__("default"))). |
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| 13 | dnl Does *not* test for __visibility__("protected") - which has tricky |
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| 14 | dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on |
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| 15 | dnl MacOS X. |
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| 16 | dnl Does *not* test for __visibility__("internal") - which has processor |
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| 17 | dnl dependent semantics. |
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| 18 | dnl Does *not* test for #pragma GCC visibility push(hidden) - which is |
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| 19 | dnl "really only recommended for legacy code". |
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| 20 | dnl Set the variable CFLAG_VISIBILITY. |
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| 21 | dnl Defines and sets the variable HAVE_VISIBILITY. |
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| 22 | |
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| 23 | AC_DEFUN([gl_VISIBILITY], |
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| 24 | [ |
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| 25 | AC_REQUIRE([AC_PROG_CC]) |
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| 26 | CFLAG_VISIBILITY= |
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| 27 | HAVE_VISIBILITY=0 |
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| 28 | if test -n "$GCC"; then |
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| 29 | AC_MSG_CHECKING([for simple visibility declarations]) |
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| 30 | AC_CACHE_VAL([gl_cv_cc_visibility], [ |
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| 31 | gl_save_CFLAGS="$CFLAGS" |
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| 32 | CFLAGS="$CFLAGS -fvisibility=hidden" |
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| 33 | AC_TRY_COMPILE( |
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| 34 | [extern __attribute__((__visibility__("hidden"))) int hiddenvar; |
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| 35 | extern __attribute__((__visibility__("default"))) int exportedvar; |
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| 36 | extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); |
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| 37 | extern __attribute__((__visibility__("default"))) int exportedfunc (void);], |
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| 38 | [], |
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| 39 | [gl_cv_cc_visibility=yes], |
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| 40 | [gl_cv_cc_visibility=no]) |
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| 41 | CFLAGS="$gl_save_CFLAGS"]) |
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| 42 | AC_MSG_RESULT([$gl_cv_cc_visibility]) |
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| 43 | if test $gl_cv_cc_visibility = yes; then |
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| 44 | CFLAG_VISIBILITY="-fvisibility=hidden" |
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| 45 | HAVE_VISIBILITY=1 |
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| 46 | fi |
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| 47 | fi |
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| 48 | AC_SUBST([CFLAG_VISIBILITY]) |
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| 49 | AC_SUBST([HAVE_VISIBILITY]) |
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| 50 | AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], |
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| 51 | [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) |
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| 52 | ]) |
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