[Bug target/79366] wrong result in cast to unsigned int

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79366

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Clang's ubsan diagnoses this, but ours doesn't:

u.cc:4:25: runtime error: value -1 is outside the range of representable values
of type 'unsigned int'