Re: [PATCH 2/2] Avoid default-initializing auto_vec<T, N> storage, fix vec<vl_embed>

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Feb 24, 2023 at 12:15:04PM +0000, Richard Biener wrote:
> > > Also, I think it needs to be MAX (N, 2) instead of N, because auto_vec
> > > ctors use MAX (N, 2).  We could also change all those to MAX (N, 1)
> > > now, but it can't be N because m_data[sizeof (T) * 0] is invalid in
> > > standard C.
> 
> I've removed the MAX (N, 2) now, I think that N == 0 cannot happen
> because we have a specialization covering that.  So we know N is
> at least 1.

I think you're right.

> > > Anyway, I wonder if you get the -Werror=stringop-overflow= errors during
> > > bootstrap that I got with my version or not.
> 
> Yes, I get this as well, not sure how to suppress it.  I guess there's
> no standard way to get at the address after some object without going
> through uintptr obfuscation - and obviously we do not want to have
> that (and if we optimize it away that doesn't help the diagnostic ...)

I think we need to look at the exact IL on which it warns and see what
our options are.

	Jakub