diff options
| author | Khem Raj <raj.khem@gmail.com> | 2023-01-24 17:54:33 -0800 |
|---|---|---|
| committer | Hiroshi SHIBATA <hsbt@ruby-lang.org> | 2023-01-27 11:30:13 +0900 |
| commit | f49bb1505b854253b4f993ca9b95836bde37feb5 (patch) | |
| tree | aa420a1656bc378cdc0604ad42b3d6bb1ee80966 /ext | |
| parent | f4609b6bc442bebee7bad2ee8d4bef46b288b7ba (diff) | |
[ruby/fiddle] fiddle: Use C11 _Alignof to define ALIGN_OF when
possible
(https://github.com/ruby/fiddle/pull/120)
WG14 N2350 made very clear that it is an UB having type definitions
within "offsetof" [1]. This patch enhances the implementation of macro
ALIGN_OF to use builtin "_Alignof" to avoid undefined behavior when
using std=c11 or newer
clang 16+ has started to flag this [2]
Fixes build when using -std >= gnu11 and using clang16+
Older compilers gcc < 4.9 or clang < 8 has buggy _Alignof even though it
may support C11, exclude those compiler versions
[1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm
[2] https://reviews.llvm.org/D133574
Signed-off-by: Khem Raj <raj.khem@gmail.com>
https://github.com/ruby/fiddle/commit/ad6c9aa826
Diffstat (limited to 'ext')
| -rw-r--r-- | ext/fiddle/fiddle.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/ext/fiddle/fiddle.h b/ext/fiddle/fiddle.h index 10eb9ceedb..684b943d30 100644 --- a/ext/fiddle/fiddle.h +++ b/ext/fiddle/fiddle.h @@ -196,7 +196,17 @@ #endif #define TYPE_UINTPTR_T (-TYPE_INTPTR_T) -#define ALIGN_OF(type) offsetof(struct {char align_c; type align_x;}, align_x) +/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023 + <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. + clang versions < 8.0.0 have the same bug. */ +#if (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112 \ + || (defined(__GNUC__) && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \ + && !defined(__clang__)) \ + || (defined(__clang__) && __clang_major__ < 8)) +# define ALIGN_OF(type) offsetof(struct {char align_c; type align_x;}, align_x) +#else +# define ALIGN_OF(type) _Alignof(type) +#endif #define ALIGN_VOIDP ALIGN_OF(void*) #define ALIGN_CHAR ALIGN_OF(char) |