Hmm.  I see your point.  It's difficult to determine the cutoff between
things that ANSI doesn't cover that you can't warn about, and things you
can.

For instance, you obviously can't generically warn for %qd, without
printf having a flag, set at link or compile time, which indicates whether
there should be a warning there.

I guess I was interpreting the bug report to indicate that there was
a required diagnostic missing... and I see no required diagnostic here.
I agree, it is a bug otherwise.

-s