> should've explored a rule that required the compiler to emit a diagnostic or error for trivial loops (whether as defined by C11 or otherwise), requiring the programmer to explicitly insert ::yield or similar

It wouldn't work when this kind of loop is generated by macros/templates in some unreachable case left after const folding.

If it's truly unreachable then it's not likely to be a problem. If it is reachable and it's emerging from some macros and templates then I would be more inclined want a warning for it.

Yeah, but then you need compiler to somehow know if it's truly unreachable to know when to emit the warning and when to not do that.

If it's a warning and not an error then emit it whether it's unreachable or not