83 lines
3.4 KiB
Plaintext
83 lines
3.4 KiB
Plaintext
# visibility.m4 serial 8
|
|
dnl Copyright (C) 2005, 2008, 2010-2022 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 $CPPFLAGS.
|
|
AC_CACHE_CHECK([whether the -Werror option is usable],
|
|
[gl_cv_cc_vis_werror],
|
|
[gl_save_CFLAGS="$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"
|
|
])
|
|
dnl Now check whether visibility declarations are supported.
|
|
AC_CACHE_CHECK([for simple visibility declarations],
|
|
[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);
|
|
int hiddenvar;
|
|
int exportedvar;
|
|
int hiddenfunc (void) { return 51; }
|
|
int exportedfunc (void) { return 1225736919; }
|
|
void dummyfunc (void) {}
|
|
]],
|
|
[[]])],
|
|
[gl_cv_cc_visibility=yes],
|
|
[gl_cv_cc_visibility=no])
|
|
CFLAGS="$gl_save_CFLAGS"
|
|
])
|
|
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.])
|
|
])
|