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| author | Paul Eggert <eggert@cs.ucla.edu> | 2012-01-27 22:17:42 -0800 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2012-01-27 22:18:35 -0800 |
| commit | ba7b7388f820b620ad4f92d263f7037dd7c89bfc (patch) | |
| tree | caa4995abb5aa77676613a42b9629a502f59a350 /m4/stdalign.m4 | |
| parent | 1d99767ae56e5f7694fa9b036934ef7f27330f7e (diff) | |
| download | gnulib-ba7b7388f820b620ad4f92d263f7037dd7c89bfc.tar.gz | |
stdalign: relax _Alignof and tighten _Alignas test
* m4/stdalign.m4 (gl_STDALIGN_H): Relax the _Alignof test,
as it was too strict: alignof must divide offsetof, but it need
not equal offsetof. Inspired by Joseph S. Myers's comment
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023#c10>.
Conversely, tighten the _Alignas test a bit, as the resulting
alignment must be exactly 8.
Diffstat (limited to 'm4/stdalign.m4')
| -rw-r--r-- | m4/stdalign.m4 | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/m4/stdalign.m4 b/m4/stdalign.m4 index d78a589808..6659c9c3ec 100644 --- a/m4/stdalign.m4 +++ b/m4/stdalign.m4 @@ -25,15 +25,16 @@ AC_DEFUN([gl_STDALIGN_H], #else # define ao(type) offsetof (struct { char a; type b; }, b) #endif - char test1[_Alignof (double) == ao (double) ? 1 : -1]; - char test2[alignof (long int) == ao (long int) ? 1 : -1]; + char test_double[ao (double) % _Alignof (double) == 0 ? 1 : -1]; + char test_long[ao (long int) % _Alignof (long int) == 0 ? 1 : -1]; + char test_alignof[alignof (double) == _Alignof (double) ? 1 : -1]; /* Test _Alignas only on platforms where gnulib can help. */ #if \ (__GNUC__ || __IBMC__ || __IBMCPP__ \ || 0x5110 <= __SUNPRO_C || 1300 <= _MSC_VER) int alignas (8) alignas_int = 1; - char test3[8 <= _Alignof (alignas_int) ? 1 : -1]; + char test_alignas[_Alignof (alignas_int) == 8 ? 1 : -1]; #endif ]])], [gl_cv_header_working_stdalign_h=yes], |