Re: [PATCH 2/2] format-patch: fix leak of rev_info in prepare_bases()

[Jeff King <peff@peff.net>]

On Fri, Jul 03, 2026 at 01:45:15PM -0700, Junio C Hamano wrote:

> Patrick Steinhardt <ps@pks.im> writes:
> 
> >> Likewise I find the dual clang/gcc jobs to be overkill. Compiling with
> >> both is useful, as they have different warnings. But have we ever seen a
> >> case where running the tests showed a different result with different
> >> compilers?
> >
> > Not that I'd know of. As you say, I think it makes sense to use
> > different compilers in general. But I don't really think we need to have
> > this as a full "compiler x tests" matrix.
> 
> Very true.  Different configurations with TEST-vars are great
> combination to test, but we are not in the business of hunting bugs
> in clang/gcc so we long as they compile (instead of warning "hey,
> that construct gives you undefined behaviour"), we shouldn't have to
> run the test suite with the same configuration for both.

I don't care about finding bugs in clang vs gcc. I'm more concerned with
a case where we have undefined behavior, both compile it fine, but the
bad behavior is revealed in the tests only by one of them.

I can think offhand of only one case where I saw that happen[1]. IIRC it
had to do with integer sizes being passed to a variadic function. But it
also changed behavior within the same compiler using different
optimization levels. So it feels like kind of a scattershot way of
trying to flush out UB, and we are probably better off with UBSan and
friends.

-Peff

[1] I mentioned it in:

      https://lore.kernel.org/git/20251130134625.GA199421@coredump.intra.peff.net/

    but didn't give enough details for it to be useful here. I mention
    it merely as the only anecdote I could call to mind. :)