From d55b6b1fa87700f3eae3a29522972d2e7be7d53e Mon Sep 17 00:00:00 2001 From: Khem Raj Date: Sat, 14 Jan 2023 10:11:35 -0800 Subject: [PATCH] use _Alignof to avoid UB in ALIGNOF WG14 N2350 clearly says that it is an UB having type definitions within "offsetof" [1]. Clang 16+ has started diagnosing it [2]. This patch changes the implementation of macro "ALIGNOF" to builtin "_Alignof" to avoid undefined behavior. _Alignof() return the ABI required minimum alignment. [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm [2] https://reviews.llvm.org/D133574 Upstream-Status: Submitted [https://gitlab.freedesktop.org/xorg/lib/libxcb/-/merge_requests/42] Signed-off-by: Khem Raj --- src/c_client.py | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/c_client.py b/src/c_client.py index fd256f0..4e48f13 100644 --- a/src/c_client.py +++ b/src/c_client.py @@ -288,7 +288,6 @@ def c_open(self): _c('#include "%s.h"', _ns.header) _c('') - _c('#define ALIGNOF(type) offsetof(struct { char dummy; type member; }, member)') if _ns.is_ext: for (n, h) in self.direct_imports: @@ -1266,7 +1265,7 @@ def _c_serialize_helper_fields(context, self, count += 1 code_lines.append( - '%s xcb_align_to = ALIGNOF(%s);' + '%s xcb_align_to = _Alignof(%s);' % (space, 'char' if field.c_field_type == 'void' or field.type.is_switch -- 2.39.0