VMS Help CC, Messages, INCOMPRETURN  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        In the definition of the function "<name>", the
                return type is an incomplete type other than void.

 Description    A function definition cannot specify a return type
                that is an incomplete type except for the void type.

 User Action    Complete the type before the function definition.