* initializing `short`s with `short`s instead of `int`s to avoid narrowing warnings
* Explicitly discard the result of `value` calls to avoid `[[nodiscard]]` warnings
Drive-by: `testException` from `value` test is duplicated in `value_or` test; remove the duplicate.
Differential Review: https://reviews.llvm.org/D141108
Concepts should be supported by all supported compilers. This is
probably a left over from an older version of the expected patch.
Reviewed By: #libc, philnik
Differential Revision: https://reviews.llvm.org/D140632