Proposed resolution:

This wording is relative to N4640.

1. Change [functional.syn], header <functional> synopsis, as indicated:

   // 20.14.4, invoke
   template <class F, class... Args>
     invoke_result_t<F, Args...>result_of_t<F&&(Args&&...)> invoke(F&& f, Args&&... args) noexcept(is_nothrow_invocable_v<F, Args...>);
   

2. Change [func.invoke] as indicated:

   template <class F, class... Args>
     invoke_result_t<F, Args...>result_of_t<F&&(Args&&...)> invoke(F&& f, Args&&... args) noexcept(is_nothrow_invocable_v<F, Args...>);