It appears that the released version of clang that supports constexpr
destructors is clang 10 and the oldest one that accepts -std=c++2a is 5,
so mark these as UNSUPPORTED for clang-5 to clang-9.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D89704
We're technically not allowed by the Standard to call ::operator new in
constexpr functions like __libcpp_allocate. Clang doesn't seem to complain
about it, but GCC does.
This commit adds std::construct_at, and marks various members of
std::allocator_traits and std::allocator as constexpr. It also adds
tests and turns the existing tests into hybrid constexpr/runtime tests.
Thanks to Richard Smith for initial work on this, and to Michael Park
for D69803, D69132 and D69134, which are superseded by this patch.
Differential Revision: https://reviews.llvm.org/D68364
Alex Richardson