Proposed resolution:

This wording is relative to N4296.

1. Change [func.require] as depicted [Editorial remark: This simply adds "A simple call wrapper is a forwarding call wrapper", then moves the sentence. — end of remark]:

   -4- Every call wrapper (20.9.1) shall be MoveConstructible. A simple call wrapper is a call wrapper that is CopyConstructible and CopyAssignable and whose copy constructor, move constructor, and assignment operator do not throw exceptions. A forwarding call wrapper is a call wrapper that can be called with an arbitrary argument list and delivers the arguments to the wrapped callable object as references. This forwarding step shall ensure that rvalue arguments are delivered as rvalue-references and lvalue arguments are delivered as lvalue-references. A simple call wrapper is a forwarding call wrapper that is CopyConstructible and CopyAssignable and whose copy constructor, move constructor, and assignment operator do not throw exceptions. [Note: In a typical implementation […] — end note]