Proposed resolution (approved by CWG 2023-10-20):

1. Change in 7.5.8.3 [expr.prim.req.type] paragraph 1 as follows:

   A type-requirement asserts the validity of a type. The component names of a type-requirement are those of its nested-name-specifier (if any) and type-name. [Note 1: The enclosing requires-expression will evaluate to false if substitution of template arguments fails. —end note]

2. Change in 13.8.1 [temp.res.general] paragraph 4 as follows:

   A qualified or unqualified name is said to be in a type-only context if it is the terminal name of

   • a typename-specifier, type-requirement, nested-name-specifier, elaborated-type-specifier, class-or-decltype, or
   • ...

[Accepted as a DR at the November, 2023 meeting.]

Consider:

  template <typename T>
  concept C = requires {
    typename T::type<void>;   // template required?
  };

There is implementation divergence: gcc accepts, clang and MSVC reject.

A type-requirement ought to be a type-only context.