File: visibility.m4

package info (click to toggle)
lpe 1.2.8-2
  • links: PTS
  • area: main
  • in suites: bullseye, buster, sid, stretch
  • size: 4,244 kB
  • ctags: 2,848
  • sloc: ansic: 27,612; sh: 12,468; makefile: 689; yacc: 291; cs: 137; perl: 111; sed: 16
file content (77 lines) | stat: -rw-r--r-- 3,351 bytes parent folder | download | duplicates (7)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
# visibility.m4 serial 5 (gettext-0.18.2)
dnl Copyright (C) 2005, 2008, 2010-2015 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 Mac OS 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
    dnl First, check whether -Werror can be added to the command line, or
    dnl whether it leads to an error because of some other option that the
    dnl user has put into $CC $CFLAGS $CPPFLAGS.
    AC_MSG_CHECKING([whether the -Werror option is usable])
    AC_CACHE_VAL([gl_cv_cc_vis_werror], [
      gl_save_CFLAGS="$CFLAGS"
      CFLAGS="$CFLAGS -Werror"
      AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM([[]], [[]])],
        [gl_cv_cc_vis_werror=yes],
        [gl_cv_cc_vis_werror=no])
      CFLAGS="$gl_save_CFLAGS"])
    AC_MSG_RESULT([$gl_cv_cc_vis_werror])
    dnl Now check whether visibility declarations are supported.
    AC_MSG_CHECKING([for simple visibility declarations])
    AC_CACHE_VAL([gl_cv_cc_visibility], [
      gl_save_CFLAGS="$CFLAGS"
      CFLAGS="$CFLAGS -fvisibility=hidden"
      dnl We use the option -Werror and a function dummyfunc, because on some
      dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning
      dnl "visibility attribute not supported in this configuration; ignored"
      dnl at the first function definition in every compilation unit, and we
      dnl don't want to use the option in this case.
      if test $gl_cv_cc_vis_werror = yes; then
        CFLAGS="$CFLAGS -Werror"
      fi
      AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
           [[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);
             void dummyfunc (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.])
])