https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78501
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Even for Fortran and other non-C FEs I think ptrdiff_type_node isn't what you expect it to be. Wouldn't it be better to use signed_type_for (type) as the type instead (where type is the type of strlen's lhs, i.e. usually size_t)?
