==== tests/cases/compiler/returnTypeParameter.ts (2 errors) ====
    function f<T>(a: T): T { } // error, no return statement
                         ~
!!! A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
    function f2<T>(a: T): T { return T; } // bug was that this satisfied the return statement requirement
                                     ~
!!! Cannot find name 'T'.