[Bug sanitizer/80536] [6/7/8 Regression] UBSAN: compile time segfault

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80536

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #15)
> In C I don't think so, because we mostly call c_save_expr and c_fully_fold
> therein would fold that expression to 0.  And when we call save_expr, it's

Yeah, I know that, and I think it is a serious bug.  With the c_fully_fold in
c_save_expr the C FE is not doing anything close to delayed folding, it folds
immediately whenever we might need a save_expr, the old trees gone.
So I think it would be nice to kill c_save_expr, just use save_expr, and let
c_fully_fold fold SAVE_EXPR operand (just once, not many times).