blob: 1dff9c0f8c46a930ed355d503bbae947a3b56936 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
From 6b3c202b46b9312c5bb0789145f13d8086e70948 Mon Sep 17 00:00:00 2001
From: Khem Raj <raj.khem@gmail.com>
Date: Sun, 15 Jan 2023 02:34:17 -0800
Subject: [PATCH] fiddle: Use C11 _Alignof to define ALIGN_OF when possible
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
Upstream-Status: Submitted [https://github.com/ruby/fiddle/pull/120]
Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
ext/fiddle/fiddle.h | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/ext/fiddle/fiddle.h b/ext/fiddle/fiddle.h
index 10eb9ce..ffb395e 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)
--
2.39.0
|
