Use std::size over sizeof/sizeof

[AreaZR]

This is more concise than sizeof/sizeof, and std::size is a constexpr so there shouldn't be any cost.

[StephanTLavavej]

Thanks - agreed that this is an improvement, and that there's no cost in release mode. (I'm not worried about minor consequences in debug mode.) I've pushed a pre-emptive fix for the MSVC-internal build, plus additional changes to update occurrences in stl/inc.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[CaseyCarter]

I'm not concerned with the change since none of these uses are performance-critical, but note that this change can in general pessimize debug codegen. MSVC is quite reluctant to evaluate constant expressions that are not manifestly constant (used in a context that requires a constant expression) at compiletime when not optimizing. See https://godbolt.org/z/74eEe98zP for a demonstration.

Again, I'm happy to apply this, but keep in mind if you submit future similar PRs that we may need to sometimes force constant evaluation to avoid pessimizing codegen when adding calls to constexpr functions.

[StephanTLavavej]

Thanks for this code cleanup! 😸 😸 😸 😸 😸 😸