[libcxx-commits] [libcxx] [libcxx][test] Stop testing signaling NaN in the constexpr comparison functions (PR #222542)

[Cyrus Ding via libcxx-commits]

dingcyrus wrote:

Thanks for the detailed explanation, @frederick-vs-ja — that makes sense, and I misread P3899's scope. Since it doesn't touch the comparison functions and was accepted as a DR (thus applying retroactively), version-gated re-enabling via `TEST_STD_AT_LEAST_26_OR_RUNTIME_EVALUATED` is indeed the wrong model. `if (!TEST_IS_CONSTANT_EVALUATED)` sounds like the right guard: it keeps runtime coverage while staying agnostic about whether sNaN should be accepted during constant evaluation — implementations agree on the return values at runtime, and that's the part the standards discussion hasn't settled anyway.

I'll leave this as a draft for now and can switch to that approach quickly once there's a clearer direction on the constant-evaluation question.

https://github.com/llvm/llvm-project/pull/222542