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Fix the logic for defining away __extension__, it was reversed.
Noticed by espie@

/*	$OpenBSD: cdefs.h,v 1.13 2004/01/28 03:33:29 millert Exp $	*/
/*	$NetBSD: cdefs.h,v 1.16 1996/04/03 20:46:39 christos Exp $	*/

/*
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Berkeley Software Design, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)cdefs.h	8.7 (Berkeley) 1/21/94
 */

#ifndef	_CDEFS_H_
#define	_CDEFS_H_

#include <machine/cdefs.h>

#if defined(__cplusplus)
#define	__BEGIN_DECLS	extern "C" {
#define	__END_DECLS	}
#else
#define	__BEGIN_DECLS
#define	__END_DECLS
#endif

/*
 * Macro to test if we're using a specific version of gcc or later.
 */
#ifdef __GNUC__
#define __GNUC_PREREQ__(ma, mi) \
	((__GNUC__ > (ma)) || (__GNUC__ == (ma) && __GNUC_MINOR__ >= (mi)))
#else
#define __GNUC_PREREQ__(ma, mi) 0
#endif

/*
 * The __CONCAT macro is used to concatenate parts of symbol names, e.g.
 * with "#define OLD(foo) __CONCAT(old,foo)", OLD(foo) produces oldfoo.
 * The __CONCAT macro is a bit tricky -- make sure you don't put spaces
 * in between its arguments.  __CONCAT can also concatenate double-quoted
 * strings produced by the __STRING macro, but this only works with ANSI C.
 */
#if defined(__STDC__) || defined(__cplusplus)
#define	__P(protos)	protos		/* full-blown ANSI C */
#define	__CONCAT(x,y)	x ## y
#define	__STRING(x)	#x

#define	__const		const		/* define reserved names to standard */
#define	__signed	signed
#define	__volatile	volatile
#if defined(__cplusplus)
#define	__inline	inline		/* convert to C++ keyword */
#else
#if !defined(__GNUC__) && !defined(lint)
#define	__inline			/* delete GCC keyword */
#endif /* !__GNUC__ && !lint */
#endif /* !__cplusplus */

#else	/* !(__STDC__ || __cplusplus) */
#define	__P(protos)	()		/* traditional C preprocessor */
#define	__CONCAT(x,y)	x/**/y
#define	__STRING(x)	"x"

#if !defined(__GNUC__) && !defined(lint)
#define	__const				/* delete pseudo-ANSI C keywords */
#define	__inline
#define	__signed
#define	__volatile
#endif	/* !__GNUC__ && !lint */

/*
 * In non-ANSI C environments, new programs will want ANSI-only C keywords
 * deleted from the program and old programs will want them left alone.
 * Programs using the ANSI C keywords const, inline etc. as normal
 * identifiers should define -DNO_ANSI_KEYWORDS.
 */
#ifndef	NO_ANSI_KEYWORDS
#define	const		__const		/* convert ANSI C keywords */
#define	inline		__inline
#define	signed		__signed
#define	volatile	__volatile
#endif /* !NO_ANSI_KEYWORDS */
#endif	/* !(__STDC__ || __cplusplus) */

/*
 * GCC1 and some versions of GCC2 declare dead (non-returning) and
 * pure (no side effects) functions using "volatile" and "const";
 * unfortunately, these then cause warnings under "-ansi -pedantic".
 * GCC >= 2.5 uses the __attribute__((attrs)) style.  All of these
 * work for GNU C++ (modulo a slight glitch in the C++ grammar in
 * the distribution version of 2.5.5).
 */

#if !__GNUC_PREREQ__(2, 5)
#define	__attribute__(x)	/* delete __attribute__ if non-gcc or gcc1 */
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
#define	__dead		__volatile
#define	__pure		__const
#endif
#elif !defined(__STRICT_ANSI__)
#define __dead		__attribute__((__noreturn__))
#define __pure		__attribute__((__const__))
#endif

/*
 * GNU C version 2.96 adds explicit branch prediction so that
 * the CPU back-end can hint the processor and also so that
 * code blocks can be reordered such that the predicted path
 * sees a more linear flow, thus improving cache behavior, etc.
 *
 * The following two macros provide us with a way to utilize this
 * compiler feature.  Use __predict_true() if you expect the expression
 * to evaluate to true, and __predict_false() if you expect the
 * expression to evaluate to false.
 *
 * A few notes about usage:
 *
 *	* Generally, __predict_false() error condition checks (unless
 *	  you have some _strong_ reason to do otherwise, in which case
 *	  document it), and/or __predict_true() `no-error' condition
 *	  checks, assuming you want to optimize for the no-error case.
 *
 *	* Other than that, if you don't know the likelihood of a test
 *	  succeeding from empirical or other `hard' evidence, don't
 *	  make predictions.
 *
 *	* These are meant to be used in places that are run `a lot'.
 *	  It is wasteful to make predictions in code that is run
 *	  seldomly (e.g. at subsystem initialization time) as the
 *	  basic block reordering that this affects can often generate
 *	  larger code.
 */
#if __GNUC_PREREQ__(2, 96)
#define __predict_true(exp)	__builtin_expect(((exp) != 0), 1)
#define __predict_false(exp)	__builtin_expect(((exp) != 0), 0)
#else
#define __predict_true(exp)	((exp) != 0)
#define __predict_false(exp)	((exp) != 0)
#endif

/* Delete pseudo-keywords wherever they are not available or needed. */
#ifndef __dead
#define	__dead
#define	__pure
#endif

#if __GNUC_PREREQ__(2, 7)
#define	__packed	__attribute__((__packed__))
#elif defined(lint)
#define	__packed
#endif

#if !__GNUC_PREREQ__(2, 8)
#define	__extension__
#endif

#endif /* !_CDEFS_H_ */