[unord.hash]p5.4 ends with "shall not throw an exception unless hash<Key> is a program-defined specialization that depends on at least one program-defined type."

"that depends on at least one program-defined type" is redundant given [namespace.std]p2: "Unless explicitly prohibited, a program may add a template specialization for any standard library class template to namespace std provided that (a) the added declaration depends on at least one program-defined type ..."