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Date:      Fri, 21 Oct 2016 23:50:02 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r307756 - in head: include sys/sys
Message-ID:  <201610212350.u9LNo2PT031675@repo.freebsd.org>
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Author: jhb
Date: Fri Oct 21 23:50:02 2016
New Revision: 307756
URL: https://svnweb.freebsd.org/changeset/base/307756

Log:
  Define max_align_t for C11.
  
  libc++'s stddef.h includes an existing definition of max_align_t for
  C++11, but it is only defined for C++, not for C.  In addition, GCC and
  clang both define an alternate version of max_align_t that uses a
  union of multiple types rather than a plain long double as in libc++.
  This adds a __max_align_t to <sys/_types.h> that matches the GCC and
  clang definition that is mapped to max_align_t in <stddef.h>.
  
  PR:		210890
  Reviewed by:	dim
  MFC after:	1 month
  Differential Revision:	https://reviews.freebsd.org/D8194

Modified:
  head/include/stddef.h
  head/sys/sys/_types.h

Modified: head/include/stddef.h
==============================================================================
--- head/include/stddef.h	Fri Oct 21 21:55:50 2016	(r307755)
+++ head/include/stddef.h	Fri Oct 21 23:50:02 2016	(r307756)
@@ -62,6 +62,14 @@ typedef	___wchar_t	wchar_t;
 #endif
 #endif
 
+#if __STDC_VERSION__ >= 201112L || __cplusplus >= 201103L
+#ifndef __CLANG_MAX_ALIGN_T_DEFINED
+typedef	__max_align_t	max_align_t;
+#define __CLANG_MAX_ALIGN_T_DEFINED
+#define __GCC_MAX_ALIGN_T
+#endif
+#endif
+
 #define	offsetof(type, member)	__offsetof(type, member)
 
 #endif /* _STDDEF_H_ */

Modified: head/sys/sys/_types.h
==============================================================================
--- head/sys/sys/_types.h	Fri Oct 21 21:55:50 2016	(r307755)
+++ head/sys/sys/_types.h	Fri Oct 21 23:50:02 2016	(r307756)
@@ -100,6 +100,11 @@ typedef	__uint_least32_t __char32_t;
 #define	_CHAR32_T_DECLARED
 #endif
 
+typedef struct {
+	long long __max_align1 __aligned(_Alignof(long long));
+	long double __max_align2 __aligned(_Alignof(long double));
+} __max_align_t;
+
 typedef	__uint32_t	__dev_t;	/* device number */
 
 typedef	__uint32_t	__fixpt_t;	/* fixed point number */

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