Paul Eggert wrote:
> Bruno Haible wrote:
> > +} _gl_max_align_t;
> > +#define max_align_t _gl_max_align_t
> > #endif
> >
> > # endif /* _@GUARD_PREFIX@_STDDEF_H */
> >
> >
> > This one is not brittle and is not a big change. If Paul agrees, I would
> > commit
> > this, and you (Werner) would not need to reorganize your package's
> > configuration.
>
> Sure, that works for me.
OK, here's what I'm committing: the same idiom as we use for wint_t.
2017-09-08 Bruno Haible <br...@clisp.org>
stddef: Avoid conflict with system-defined max_align_t.
The configure-determined HAVE_MAX_ALIGN_T may not always be accurate.
Reported by Werner Lemberg <w...@gnu.org> in
<https://lists.gnu.org/archive/html/bug-gnulib/2017-08/msg00185.html>.
* lib/stddef.in.h (rpl_max_align_t): Renamed from max_align_t.
(max_align_t): Define as a macro.
(GNULIB_defined_max_align_t): New macro. Guards against multiple
definitions of rpl_max_align_t in different copies of gnulib-generated
<stddef.h>.
diff --git a/lib/stddef.in.h b/lib/stddef.in.h
index 2a11d2b..a79f536 100644
--- a/lib/stddef.in.h
+++ b/lib/stddef.in.h
@@ -85,24 +85,28 @@
a hack in case the configure-time test was done with g++ even though
we are currently compiling with gcc. */
#if ! (@HAVE_MAX_ALIGN_T@ || defined _GCC_MAX_ALIGN_T)
+# if !GNULIB_defined_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
+# ifdef __GNUC__
+# define _GL_STDDEF_ALIGNAS(type) \
+ __attribute__ ((__aligned__ (__alignof__ (type))))
+# else
+# define _GL_STDDEF_ALIGNAS(type) /* */
+# endif
typedef union
{
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;
+} rpl_max_align_t;
+# define max_align_t rpl_max_align_t
+# define GNULIB_defined_max_align_t 1
+# endif
#endif
# endif /* _@GUARD_PREFIX@_STDDEF_H */
