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| author | Simon McVittie <smcv@collabora.com> | 2021-12-10 15:12:59 +0000 |
|---|---|---|
| committer | Simon McVittie <smcv@collabora.com> | 2021-12-17 12:57:42 +0000 |
| commit | b44e0cc9f456449e1378e4b03bcb7ad3db094725 (patch) | |
| tree | 4e8035518087193942d0d32ba6e8620339f15698 | |
| parent | d13349f25ce6160695237cb1715bc3a8e2fa8985 (diff) | |
| download | dbus-b44e0cc9f456449e1378e4b03bcb7ad3db094725.tar.gz | |
internals: Use Standard C offsetof macro if available
clang 13 fails to compile our current implementation with:
.../dbus/dbus-message.c:2070:3: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant]
_DBUS_STATIC_ASSERT (_DBUS_ALIGNOF (DBusMessageRealIter) <=
^
.../dbus/dbus-internals.h:460:25: note: expanded from macro '_DBUS_STATIC_ASSERT'
typedef struct { char _assertion[(expr) ? 1 : -1]; } \
This appears to be because the "traditional" definition of
offsetof(), which we're hard-coding here, does not qualify as a constant
expression under C rules due to its use of pointer casts.
Modern compilers like gcc and clang have a built-in implementation
of offsetof that *is* a constant expression.
Signed-off-by: Simon McVittie <smcv@collabora.com>
(cherry picked from commit a24cf746e2a8191070efd1300a15d37284aaf2fa)
| -rw-r--r-- | dbus/dbus-internals.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/dbus/dbus-internals.h b/dbus/dbus-internals.h index e7649e1d..281d6af2 100644 --- a/dbus/dbus-internals.h +++ b/dbus/dbus-internals.h @@ -192,8 +192,13 @@ void _dbus_real_assert_not_reached (const char *explanation, #define _DBUS_ZERO(object) (memset (&(object), '\0', sizeof ((object)))) +#ifdef offsetof +#define _DBUS_STRUCT_OFFSET(struct_type, member) \ + (offsetof (struct_type, member)) +#else #define _DBUS_STRUCT_OFFSET(struct_type, member) \ ((intptr_t) ((unsigned char*) &((struct_type*) 0)->member)) +#endif #define _DBUS_ALIGNOF(type) \ (_DBUS_STRUCT_OFFSET (struct { char _1; type _2; }, _2)) |