https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79687
--- Comment #13 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Uh. (sizetype) q is folded to -1 in constant_value_1. DECL_INITIAL of "q" is -1, that's what build_zero_init_1 did: 177 else if (TYPE_PTR_OR_PTRMEM_P (type)) 178 init = fold (convert (type, nullptr_node)); type is offset_type. Why is nullptr_node converted to offset_type -1?!
