[Bug c++/78655] gcc doesn't exploit the fact that the result of pointer addition can not be nullptr

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78655

--- Comment #8 from Marc Glisse <glisse at gcc dot gnu.org> ---
(just to put this somewhere)
We have multiple ways of doing pointer arithmetic in gcc. After the recent
patch, we know that g returns nonnull, but we don't know it for f.

struct A{int a,b;};
int*f(A*p){return&p->b;}
int*g(A*p){return(int*)p+1;}