2020-12-12 16:33:22 -08:00
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# ============================================================================
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# https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html
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# ============================================================================
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2014-10-14 14:31:16 -07:00
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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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# flatten
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# format
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# format_arg
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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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# 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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2020-04-17 07:46:15 -07:00
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# Unsupported function attributes will be tested with a prototype returning
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2014-10-14 14:31:16 -07:00
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# an int and not accepting any arguments and the result of the check might
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# 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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2016-03-19 00:24:00 -07:00
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#serial 3
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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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[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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[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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[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([test -s 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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