fe588fef09
* configure.ac: Add -fvisibility=hidden to GPGME_CPP_CFLAGS if gcc supports the flag. * lang/cpp/src/Makefile.am (AM_CPPFLAGS): Add GPGME_CPP_CFLAGS. * m4/ax_gcc_func_attribute.m4: New. -- With this change all defined symbols are hidden by default, so that they are not exported anymore. All symbols that are part of the ABI and that shall still be exported are already marked as having default visibility. The m4 macro was taken from the website mentioned in the License header of the file. GnuPG-bug-id: 5906
243 lines
8.3 KiB
Plaintext
243 lines
8.3 KiB
Plaintext
# ===========================================================================
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# https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html
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# ===========================================================================
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#
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# SYNOPSIS
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#
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# AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE)
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#
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# DESCRIPTION
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#
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# This macro checks if the compiler supports one of GCC's function
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# attributes; many other compilers also provide function attributes with
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# the same syntax. Compiler warnings are used to detect supported
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# attributes as unsupported ones are ignored by default so quieting
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# warnings when using this macro will yield false positives.
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#
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# The ATTRIBUTE parameter holds the name of the attribute to be checked.
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#
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# If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>.
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#
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# The macro caches its result in the ax_cv_have_func_attribute_<attribute>
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# variable.
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#
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# The macro currently supports the following function attributes:
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#
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# alias
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# aligned
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# alloc_size
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# always_inline
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# artificial
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# cold
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# const
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# constructor
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# constructor_priority for constructor attribute with priority
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# deprecated
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# destructor
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# dllexport
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# dllimport
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# error
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# externally_visible
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# fallthrough
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# flatten
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# format
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# format_arg
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# gnu_format
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# gnu_inline
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# hot
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# ifunc
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# leaf
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# malloc
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# noclone
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# noinline
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# nonnull
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# noreturn
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# nothrow
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# optimize
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# pure
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# sentinel
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# sentinel_position
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# unused
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# used
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# visibility
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# warning
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# warn_unused_result
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# weak
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# weakref
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#
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# Unsupported function attributes will be tested with a prototype
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# returning an int and not accepting any arguments and the result of the
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# check might be wrong or meaningless so use with care.
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#
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# LICENSE
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#
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# Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com>
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#
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# Copying and distribution of this file, with or without modification, are
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# permitted in any medium without royalty provided the copyright notice
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# and this notice are preserved. This file is offered as-is, without any
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# warranty.
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#serial 13
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AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [
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AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1])
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AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
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AC_LINK_IFELSE([AC_LANG_PROGRAM([
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m4_case([$1],
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[alias], [
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int foo( void ) { return 0; }
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int bar( void ) __attribute__(($1("foo")));
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],
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[aligned], [
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int foo( void ) __attribute__(($1(32)));
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],
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[alloc_size], [
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void *foo(int a) __attribute__(($1(1)));
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],
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[always_inline], [
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inline __attribute__(($1)) int foo( void ) { return 0; }
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],
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[artificial], [
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inline __attribute__(($1)) int foo( void ) { return 0; }
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],
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[cold], [
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int foo( void ) __attribute__(($1));
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],
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[const], [
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int foo( void ) __attribute__(($1));
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],
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[constructor_priority], [
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int foo( void ) __attribute__((__constructor__(65535/2)));
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],
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[constructor], [
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int foo( void ) __attribute__(($1));
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],
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[deprecated], [
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int foo( void ) __attribute__(($1("")));
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],
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[destructor], [
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int foo( void ) __attribute__(($1));
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],
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[dllexport], [
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__attribute__(($1)) int foo( void ) { return 0; }
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],
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[dllimport], [
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int foo( void ) __attribute__(($1));
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],
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[error], [
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int foo( void ) __attribute__(($1("")));
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],
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[externally_visible], [
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int foo( void ) __attribute__(($1));
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],
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[fallthrough], [
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void foo( int x ) {switch (x) { case 1: __attribute__(($1)); case 2: break ; }};
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],
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[flatten], [
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int foo( void ) __attribute__(($1));
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],
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[format], [
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int foo(const char *p, ...) __attribute__(($1(printf, 1, 2)));
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],
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[gnu_format], [
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int foo(const char *p, ...) __attribute__((format(gnu_printf, 1, 2)));
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],
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[format_arg], [
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char *foo(const char *p) __attribute__(($1(1)));
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],
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[gnu_inline], [
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inline __attribute__(($1)) int foo( void ) { return 0; }
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],
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[hot], [
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int foo( void ) __attribute__(($1));
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],
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[ifunc], [
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int my_foo( void ) { return 0; }
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static int (*resolve_foo(void))(void) { return my_foo; }
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int foo( void ) __attribute__(($1("resolve_foo")));
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],
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[leaf], [
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__attribute__(($1)) int foo( void ) { return 0; }
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],
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[malloc], [
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void *foo( void ) __attribute__(($1));
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],
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[noclone], [
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int foo( void ) __attribute__(($1));
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],
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[noinline], [
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__attribute__(($1)) int foo( void ) { return 0; }
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],
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[nonnull], [
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int foo(char *p) __attribute__(($1(1)));
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],
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[noreturn], [
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void foo( void ) __attribute__(($1));
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],
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[nothrow], [
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int foo( void ) __attribute__(($1));
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],
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[optimize], [
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__attribute__(($1(3))) int foo( void ) { return 0; }
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],
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[pure], [
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int foo( void ) __attribute__(($1));
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],
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[sentinel], [
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int foo(void *p, ...) __attribute__(($1));
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],
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[sentinel_position], [
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int foo(void *p, ...) __attribute__(($1(1)));
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],
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[returns_nonnull], [
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void *foo( void ) __attribute__(($1));
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],
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[unused], [
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int foo( void ) __attribute__(($1));
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],
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[used], [
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int foo( void ) __attribute__(($1));
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],
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[visibility], [
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int foo_def( void ) __attribute__(($1("default")));
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int foo_hid( void ) __attribute__(($1("hidden")));
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int foo_int( void ) __attribute__(($1("internal")));
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int foo_pro( void ) __attribute__(($1("protected")));
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],
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[warning], [
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int foo( void ) __attribute__(($1("")));
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],
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[warn_unused_result], [
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int foo( void ) __attribute__(($1));
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],
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[weak], [
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int foo( void ) __attribute__(($1));
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],
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[weakref], [
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static int foo( void ) { return 0; }
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static int bar( void ) __attribute__(($1("foo")));
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],
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[
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m4_warn([syntax], [Unsupported attribute $1, the test may fail])
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int foo( void ) __attribute__(($1));
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]
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)], [])
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],
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dnl GCC doesn't exit with an error if an unknown attribute is
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dnl provided but only outputs a warning, so accept the attribute
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dnl only if no warning were issued.
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[AS_IF([grep -- -Wattributes conftest.err],
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[AS_VAR_SET([ac_var], [no])],
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[AS_VAR_SET([ac_var], [yes])])],
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[AS_VAR_SET([ac_var], [no])])
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])
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AS_IF([test yes = AS_VAR_GET([ac_var])],
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[AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1,
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[Define to 1 if the system has the `$1' function attribute])], [])
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AS_VAR_POPDEF([ac_var])
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])
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