[Bug c++/70170] [6 regression] bogus not a constant expression error comparing pointer to array to null

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70170

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #7)
> A small problem is that the second argument to POINTER_PLUS_EXPR is not
> signed, but unsigned (sizetype).  Which is why I wrote "negative", negative
> would mean having the most significant bit set or so.

This seems to cause a variety of problems.  Since it can be negative, surely it
should have ssizetype?