[Bug c/37591] suppress "signed and unsigned" warnings when signed value known to be positive

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37591

--- Comment #10 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #9)
> I think this is related to bug 38470

Possibly a dup thereof? Or vice versa?