| Issue |
114026
|
| Summary |
Clang 17 and later rejects __attribute__ after static specifier in C++23 lambda expressions
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
johnplatts
|
Here is a snippet of C++23 code that compiles successfully with GCC 13 or later with `-std=c++23` but fails to compile with Clang 17 or later (even with the `std=c++23` option):
```
#include <stddef.h>
#include <stdint.h>
#include <immintrin.h>
__m128i __attribute__((__target__("sse4.2"))) SomeFunc(
const int32_t* src_ptr, size_t num_of_vectors) {
auto process_func = [](const int32_t* p) static __attribute__((__target__("sse4.2"))) {
__m128i v = _mm_loadu_si128(reinterpret_cast<const __m128i*>(p));
return _mm_mullo_epi32(v, _mm_set_epi32(15752961, 3969, 63, 1));
};
__m128i h = _mm_setzero_si128();
for (size_t i = 0; i < num_of_vectors; i++) {
h = _mm_add_epi32(_mm_sub_epi32(_mm_slli_epi32(h, 6), h),
process_func(src_ptr + 4 * i));
}
return h;
}
```
The results of compiling the above snippet with GCC 13, Clang 17, and Clang trunk can be found at https://godbolt.org/z/WfoqnnPqc.
Should Clang be updated to allow `__attribute__((__target__("sse4.2")))` after the `static` specifier in C++23 lambda expressions?
On the other hand, the below snippet successfully compiles with Clang 17 or later in C++23 mode but fails to compile with GCC 13 in C++23 mode:
```
#include <stddef.h>
#include <stdint.h>
#include <immintrin.h>
__m128i __attribute__((__target__("sse4.2"))) SomeFunc(
const int32_t* src_ptr, size_t num_of_vectors) {
auto process_func = [](const int32_t* p) __attribute__((__target__("sse4.2"))) static {
__m128i v = _mm_loadu_si128(reinterpret_cast<const __m128i*>(p));
return _mm_mullo_epi32(v, _mm_set_epi32(15752961, 3969, 63, 1));
};
__m128i h = _mm_setzero_si128();
for (size_t i = 0; i < num_of_vectors; i++) {
h = _mm_add_epi32(_mm_sub_epi32(_mm_slli_epi32(h, 6), h),
process_func(src_ptr + 4 * i));
}
return h;
}
```
The results of compiling the above snippet with GCC 13, Clang 17, and Clang trunk can be found at https://godbolt.org/z/9ooT8bj1f.
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