https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61182
--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> --- 8.3.5/6 says, A function type with a cv-qualifier-seq or a ref-qualifier ... shall appear only as: — the function type for a non-static member function, — the function type to which a pointer to member refers, — the top-level function type of a function typedef declaration or alias-declaration, — the type-id in the default argument of a type-parameter (14.1), or — the type-id of a template-argument for a type-parameter (14.3.1). Which I read as meaning no (non-member) pointers to such a type.
