[Bug sanitizer/63806] #UBSAN ignores signed char possible overflow

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63806

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
No, narrowing conversion is implementation defined, and gcc defines that to the
modulo 2^N wrapping, so this is not undefined behavior, and furthermore,
something you'd complain about in pretty much all the code (there is no
difference between implicit and explicit narrowing cast).