ee95c7020c
Zoe Carver says: "We decided that libc++ only supports C++20 constexpr algorithms when `is_constant_evaluated` is also supported. Here's a link to the discussion." https://reviews.llvm.org/D65721#inline-735682 Remove _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED from tests, too. See Louis's 5911e6a8857f146fb5a8f23af1d768aba25e7c3e if needed to fix bots. I've applied `UNSUPPORTED: clang-8` preemptively to the altered tests; I don't know for sure that this was needed, because no clang-8 buildbots are triggered on pull requests.