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1 | # Check for stdalign.h that conforms to C11. |
2 | ||
dc6c21da | 3 | dnl Copyright 2011-2022 Free Software Foundation, Inc. |
725e2999 JB |
4 | dnl This file is free software; the Free Software Foundation |
5 | dnl gives unlimited permission to copy and/or distribute it, | |
6 | dnl with or without modifications, as long as this notice is preserved. | |
7 | ||
8 | # Prepare for substituting <stdalign.h> if it is not supported. | |
9 | ||
10 | AC_DEFUN([gl_STDALIGN_H], | |
11 | [ | |
12 | AC_CACHE_CHECK([for working stdalign.h], | |
13 | [gl_cv_header_working_stdalign_h], | |
14 | [AC_COMPILE_IFELSE( | |
15 | [AC_LANG_PROGRAM( | |
dc6c21da TT |
16 | [[#include <stdint.h> |
17 | #include <stdalign.h> | |
725e2999 JB |
18 | #include <stddef.h> |
19 | ||
20 | /* Test that alignof yields a result consistent with offsetof. | |
21 | This catches GCC bug 52023 | |
c0c3707f | 22 | <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. */ |
725e2999 JB |
23 | #ifdef __cplusplus |
24 | template <class t> struct alignof_helper { char a; t b; }; | |
25 | # define ao(type) offsetof (alignof_helper<type>, b) | |
26 | #else | |
27 | # define ao(type) offsetof (struct { char a; type b; }, b) | |
28 | #endif | |
29 | char test_double[ao (double) % _Alignof (double) == 0 ? 1 : -1]; | |
30 | char test_long[ao (long int) % _Alignof (long int) == 0 ? 1 : -1]; | |
31 | char test_alignof[alignof (double) == _Alignof (double) ? 1 : -1]; | |
32 | ||
33 | /* Test _Alignas only on platforms where gnulib can help. */ | |
34 | #if \ | |
35 | ((defined __cplusplus && 201103 <= __cplusplus) \ | |
dc6c21da | 36 | || (__TINYC__ && defined __attribute__) \ |
725e2999 JB |
37 | || (defined __APPLE__ && defined __MACH__ \ |
38 | ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \ | |
39 | : __GNUC__) \ | |
c0c3707f CB |
40 | || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \ |
41 | || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__ \ | |
725e2999 JB |
42 | || 1300 <= _MSC_VER) |
43 | struct alignas_test { char c; char alignas (8) alignas_8; }; | |
44 | char test_alignas[offsetof (struct alignas_test, alignas_8) == 8 | |
45 | ? 1 : -1]; | |
46 | #endif | |
47 | ]])], | |
48 | [gl_cv_header_working_stdalign_h=yes], | |
49 | [gl_cv_header_working_stdalign_h=no])]) | |
50 | ||
51 | if test $gl_cv_header_working_stdalign_h = yes; then | |
dc6c21da | 52 | GL_GENERATE_STDALIGN_H=false |
725e2999 | 53 | else |
dc6c21da | 54 | GL_GENERATE_STDALIGN_H=true |
725e2999 | 55 | fi |
725e2999 | 56 | ]) |