[Bug c/68120] can't easily deal with integer overflow at compile time

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68120

--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
Patch posted for review:
https://gcc.gnu.org/ml/gcc-patches/2016-05/msg00013.html