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- From e649db1664af981cc87f966aef6c5365ae234547 Mon Sep 17 00:00:00 2001
- From: Khem Raj <raj.khem@gmail.com>
- Date: Sun, 15 Jan 2023 00:16:25 -0800
- Subject: [PATCH] Define alignof using _Alignof when using C11 or newer
- WG14 N2350 made very clear that it is an UB having type definitions
- within "offsetof" [1]. This patch enhances the implementation of macro
- alignof to use builtin "_Alignof" to avoid undefined behavior on
- 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 compilers too
- [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm
- [2] https://reviews.llvm.org/D133574
- Upstream-Status: Pending
- Signed-off-by: Khem Raj <raj.khem@gmail.com>
- ---
- libiberty/sha1.c | 10 ++++++++++
- 1 file changed, 10 insertions(+)
- diff --git a/libiberty/sha1.c b/libiberty/sha1.c
- index 504f06d3b9b..790ada82443 100644
- --- a/libiberty/sha1.c
- +++ b/libiberty/sha1.c
- @@ -229,7 +229,17 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx)
- if (len >= 64)
- {
- #if !_STRING_ARCH_unaligned
- +/* 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 alignof(type) offsetof (struct { char c; type x; }, x)
- +#else
- +# define alignof(type) _Alignof(type)
- +#endif
- # define UNALIGNED_P(p) (((size_t) p) % alignof (sha1_uint32) != 0)
- if (UNALIGNED_P (buffer))
- while (len > 64)
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