| Andrew Geissler | c5535c9 | 2023-01-27 16:10:19 -0600 | [diff] [blame] | 1 | From c3e2c873ffa8e89b5f83dccc4e4e35dfcea633cb Mon Sep 17 00:00:00 2001 |
| 2 | From: Khem Raj <raj.khem@gmail.com> |
| 3 | Date: Sat, 14 Jan 2023 12:39:43 -0800 |
| 4 | Subject: [PATCH] Define _DBUS_ALIGNOF using _Alignof when using C11 or newer |
| 5 | |
| 6 | WG14 N2350 made very clear that it is an UB having type definitions |
| 7 | within "offsetof" [1]. This patch changes the implementation of macro |
| 8 | _DBUS_ALIGNOF to builtin "_Alignof" to avoid undefined behavior. |
| 9 | |
| 10 | clang 16+ has started to diagnose this [2] |
| 11 | |
| 12 | Fixes build when using -std >= gnu11 and using clang16+ |
| 13 | |
| 14 | [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm |
| 15 | [2] https://reviews.llvm.org/D133574 |
| 16 | |
| 17 | Upstream-Status: Submitted [https://gitlab.freedesktop.org/dbus/dbus/-/merge_requests/389] |
| 18 | Signed-off-by: Khem Raj <raj.khem@gmail.com> |
| 19 | --- |
| 20 | dbus/dbus-internals.h | 4 ++++ |
| 21 | 1 file changed, 4 insertions(+) |
| 22 | |
| 23 | diff --git a/dbus/dbus-internals.h b/dbus/dbus-internals.h |
| 24 | index cc98c92a..2387752d 100644 |
| 25 | --- a/dbus/dbus-internals.h |
| 26 | +++ b/dbus/dbus-internals.h |
| 27 | @@ -201,8 +201,12 @@ void _dbus_real_assert_not_reached (const char *explanation, |
| 28 | ((intptr_t) ((unsigned char*) &((struct_type*) 0)->member)) |
| 29 | #endif |
| 30 | |
| 31 | +#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && !defined(__cplusplus) |
| 32 | +#define _DBUS_ALIGNOF(type) _Alignof(type) |
| 33 | +#else |
| 34 | #define _DBUS_ALIGNOF(type) \ |
| 35 | (_DBUS_STRUCT_OFFSET (struct { char _1; type _2; }, _2)) |
| 36 | +#endif |
| 37 | |
| 38 | #if defined(DBUS_DISABLE_CHECKS) || defined(DBUS_DISABLE_ASSERT) |
| 39 | /* this is an assert and not an error, but in the typical --disable-checks case (you're trying |
| 40 | -- |
| 41 | 2.39.0 |
| 42 | |