HCoop / bpt / emacs.git / blame
| Commit | Line | Data |
|---|---|---|
| caf8a9b2 PE |
1 | # Check for stdalign.h that conforms to C11. |
| 2 | ||
| ab422c4d | 3 | dnl Copyright 2011-2013 Free Software Foundation, Inc. |
| caf8a9b2 PE |
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( | |
| 16 | [[#include <stdalign.h> | |
| 17 | #include <stddef.h> | |
| 18 | ||
| 19 | /* Test that alignof yields a result consistent with offsetof. | |
| 20 | This catches GCC bug 52023 | |
| 21 | <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. */ | |
| 22 | #ifdef __cplusplus | |
| 23 | template <class t> struct alignof_helper { char a; t b; }; | |
| 24 | # define ao(type) offsetof (alignof_helper<type>, b) | |
| 25 | #else | |
| 26 | # define ao(type) offsetof (struct { char a; type b; }, b) | |
| 27 | #endif | |
| 28 | char test_double[ao (double) % _Alignof (double) == 0 ? 1 : -1]; | |
| 29 | char test_long[ao (long int) % _Alignof (long int) == 0 ? 1 : -1]; | |
| 30 | char test_alignof[alignof (double) == _Alignof (double) ? 1 : -1]; | |
| 31 | ||
| 32 | /* Test _Alignas only on platforms where gnulib can help. */ | |
| 33 | #if \ | |
| 34 | (__GNUC__ || __IBMC__ || __IBMCPP__ \ | |
| 35 | || 0x5110 <= __SUNPRO_C || 1300 <= _MSC_VER) | |
| 119b2d43 PE |
36 | struct alignas_test { char c; char alignas (8) alignas_8; }; |
| 37 | char test_alignas[offsetof (struct alignas_test, alignas_8) == 8 | |
| 38 | ? 1 : -1]; | |
| caf8a9b2 PE |
39 | #endif |
| 40 | ]])], | |
| 41 | [gl_cv_header_working_stdalign_h=yes], | |
| 42 | [gl_cv_header_working_stdalign_h=no])]) | |
| 43 | ||
| 44 | if test $gl_cv_header_working_stdalign_h = yes; then | |
| 45 | STDALIGN_H='' | |
| 46 | else | |
| 47 | STDALIGN_H='stdalign.h' | |
| 48 | fi | |
| 49 | ||
| 50 | AC_SUBST([STDALIGN_H]) | |
| 51 | AM_CONDITIONAL([GL_GENERATE_STDALIGN_H], [test -n "$STDALIGN_H"]) | |
| 52 | ]) |