nexmon – Blame information for rev 1
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1 | office | 1 | # visibility.m4 serial 4 (gettext-0.18.2) |
2 | dnl Copyright (C) 2005, 2008, 2010-2011 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 | |||
7 | dnl From Bruno Haible. |
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8 | |||
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 | |||
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 | dnl First, check whether -Werror can be added to the command line, or |
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30 | dnl whether it leads to an error because of some other option that the |
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31 | dnl user has put into $CC $CFLAGS $CPPFLAGS. |
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32 | AC_MSG_CHECKING([whether the -Werror option is usable]) |
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33 | AC_CACHE_VAL([gl_cv_cc_vis_werror], [ |
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34 | gl_save_CFLAGS="$CFLAGS" |
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35 | CFLAGS="$CFLAGS -Werror" |
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36 | AC_COMPILE_IFELSE( |
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37 | [AC_LANG_PROGRAM([[]], [[]])], |
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38 | [gl_cv_cc_vis_werror=yes], |
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39 | [gl_cv_cc_vis_werror=no]) |
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40 | CFLAGS="$gl_save_CFLAGS"]) |
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41 | AC_MSG_RESULT([$gl_cv_cc_vis_werror]) |
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42 | dnl Now check whether visibility declarations are supported. |
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43 | AC_MSG_CHECKING([for simple visibility declarations]) |
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44 | AC_CACHE_VAL([gl_cv_cc_visibility], [ |
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45 | gl_save_CFLAGS="$CFLAGS" |
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46 | CFLAGS="$CFLAGS -fvisibility=hidden" |
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47 | dnl We use the option -Werror and a function dummyfunc, because on some |
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48 | dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning |
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49 | dnl "visibility attribute not supported in this configuration; ignored" |
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50 | dnl at the first function definition in every compilation unit, and we |
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51 | dnl don't want to use the option in this case. |
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52 | if test $gl_cv_cc_vis_werror = yes; then |
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53 | CFLAGS="$CFLAGS -Werror" |
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54 | fi |
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55 | AC_COMPILE_IFELSE( |
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56 | [AC_LANG_PROGRAM( |
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57 | [[extern __attribute__((__visibility__("hidden"))) int hiddenvar; |
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58 | extern __attribute__((__visibility__("default"))) int exportedvar; |
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59 | extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void); |
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60 | extern __attribute__((__visibility__("default"))) int exportedfunc (void); |
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61 | void dummyfunc (void) {} |
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62 | ]], |
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63 | [[]])], |
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64 | [gl_cv_cc_visibility=yes], |
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65 | [gl_cv_cc_visibility=no]) |
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66 | CFLAGS="$gl_save_CFLAGS"]) |
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67 | AC_MSG_RESULT([$gl_cv_cc_visibility]) |
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68 | if test $gl_cv_cc_visibility = yes; then |
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69 | CFLAG_VISIBILITY="-fvisibility=hidden" |
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70 | HAVE_VISIBILITY=1 |
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71 | fi |
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72 | fi |
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73 | AC_SUBST([CFLAG_VISIBILITY]) |
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74 | AC_SUBST([HAVE_VISIBILITY]) |
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75 | AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY], |
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76 | [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.]) |
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77 | ]) |