Criteria for a warning to be in -Wall? (was: Re: a warning to implement)

[Robert Dewar]

<<I'd have a strong preference for something that doesn't rely on GCC
extension.   __attribute((unused)) is just as icky in a portable project
as magic /* ARGSUNUSED */ comments recognized by others.
>>

Sure, that's understandable, but using

 int a = a;

on the grounds that, even though there is no guarantee, it just happens
to work, is to me the antithesis of writing clean portable code!