What about by default throwing an error or warning only in cases where it is "obvious"? (i.e. only in cases where the check was explicitly stated, so no macros

What about by default throwing an error or warning only in cases where it is "obvious"? (i.e. only in cases where the check was explicitly stated, so no macros / function boundaries / etc) Ditto, if you have an explicit block (i.e. no macros / etc) that always causes undefined behavior, warn or throw an error by default.