joerg marked 2 inline comments as done. joerg added inline comments.
================ Comment at: libcxx/test/std/utilities/meta/meta.trans/meta.trans.other/aligned_storage.pass.cpp:275 +#if TEST_STD_VER >= 11 + const size_t alignment = TEST_ALIGNOF(std::max_align_t) > 16 ? + 16 : TEST_ALIGNOF(std::max_align_t); ---------------- ldionne wrote: > joerg wrote: > > ldionne wrote: > > > Can you walk me through why the check for `> 16` is required? > > If max_align_t is 256bit, we still only expect 128bit alignment (long > > double). This test is still checking more than it should, e.g. in principle > > a target could legitimately have no natural type larger than 64bit, but > > support 256bit vector types and set max_align_t accordingly. The condition > > is here because std::min in C++11 is not constexpr. > Naively, I would have expected the test to be: > > ``` > #if TEST_STD_VER >= 11 // we know max_align_t is provided > static_assert(std::alignment_of<T1>::value == > TEST_ALIGNOF(std::max_align_t), ""); > #else > static_assert(std::alignment_of<T1>::value >= > TEST_ALIGNOF(natural_alignment), ""); > #endif > ``` > > To make sure I understand, you're saying we can't do that because the > `std::alignment_of<T1>::value == TEST_ALIGNOF(std::max_align_t)` test would > sometimes fail if `alignof(std::max_align_t)` is larger than the natural > alignment used by `std::aligned_storage`. This also highlights that there's a > change in the value of `alignof(std::max_align_t)` with this change. Is that > correct? Yes, the test would have failed before when `max_align_t > 16`. There is no change of value in `alignof(max_align_t)`, just seen by review. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D73245/new/ https://reviews.llvm.org/D73245 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
