[Bug sanitizer/71962] error: ‘((& x) != 0u)’ is not a constant expression

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71962

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
If we do that, the question is when to (temporarily) enable the null pointer
check deletion (unless disabled explicitly with -fno-delete-null-pointer-checks
or from the target defaults, like AVR ...).
Because I think there should be a difference between when some constant
expression is being evaluated in constexpr contexts (then -fsanitize=undefined
should not make a difference on those), and when it is just evaluated as
constant expression as an optimization only (maybe_constant_value and the like
for warning purposes, or during cp_fully_fold etc.).  In the latter case, I
think we should just not fold it if there are the sanitizations etc.
Is ctx->quiet what is relevant, or something different?
Perhaps even the UBSAN_* ifns should not be ignored if just in optimization?