From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 7 Apr 2015 04:47:08 +0000 (-0700)
Subject: Merge from gnulib
X-Git-Tag: emacs-25.0.90~2540
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=9d56a21e6a696ad19ac65c4b405aeca44785884a;p=emacs.git

Merge from gnulib

* lib/stddef.in.h: Update from gnulib, incorporating:
2015-04-02 stddef: port to pre-C11 GCC on x86
---

diff --git a/ChangeLog b/ChangeLog
index 70ab50cd443..6e2b4fc19d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-04-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Merge from gnulib
+	* lib/stddef.in.h: Update from gnulib, incorporating:
+	2015-04-02 stddef: port to pre-C11 GCC on x86
+
 2015-04-03  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Port 'configure' to clang 3.5
diff --git a/lib/stddef.in.h b/lib/stddef.in.h
index 44db24173c4..698307bc955 100644
--- a/lib/stddef.in.h
+++ b/lib/stddef.in.h
@@ -83,12 +83,23 @@
 
 /* Some platforms lack max_align_t.  */
 #if !@HAVE_MAX_ALIGN_T@
+/* On the x86, the maximum storage alignment of double, long, etc. is 4,
+   but GCC's C11 ABI for x86 says that max_align_t has an alignment of 8,
+   and the C11 standard allows this.  Work around this problem by
+   using __alignof__ (which returns 8 for double) rather than _Alignof
+   (which returns 4), and align each union member accordingly.  */
+# ifdef __GNUC__
+#  define _GL_STDDEF_ALIGNAS(type) \
+     __attribute__ ((__aligned__ (__alignof__ (type))))
+# else
+#  define _GL_STDDEF_ALIGNAS(type) /* */
+# endif
 typedef union
 {
-  char *__p;
-  double __d;
-  long double __ld;
-  long int __i;
+  char *__p _GL_STDDEF_ALIGNAS (char *);
+  double __d _GL_STDDEF_ALIGNAS (double);
+  long double __ld _GL_STDDEF_ALIGNAS (long double);
+  long int __i _GL_STDDEF_ALIGNAS (long int);
 } max_align_t;
 #endif