Re: More C type errors by default for GCC 14

[Jakub Jelinek <jakub@redhat.com>]

On Fri, May 12, 2023 at 11:33:01AM +0200, Martin Jambor wrote:
> > One fairly big GCC-internal task is to clear up the C test suite so that
> > it passes with the new compiler defaults.  I already have an offer of
> > help for that, so I think we can complete this work in a reasonable time
> > frame.

I'd prefer to keep at least significant portion of those tests as is with
-fpermissive added (plus of course we need new tests that verify the errors
are emitted), so that we have some testsuite coverage for those.

> So, a note to all users of cvise, creduce, delta etc.: Add appropriate
> -Werror flags to your checking scripts so that we don't add more of this :-)

While it is true that for C cvise/creduce/delta often end up with the
implicit ints/implicit function declarations/int-conversions because it
happens to still compile without errors, I and others routinely fix up those
testcases back to valid C provided they still reproduce the reported
problem, so I think it isn't that bad in our testsuite.
But for cvise/creduce/delta reduced testcases with GCC 14 the nice things is
that most of the time these constructs will be gone ;)

Note, using -Werror for all warnings for testsuite reduction often results
in much slower reduction process and larger end result compared to allowing
some warnings but then fixing them up by hand where possible if it still
reproduces.

	Jakub