==== tests/cases/compiler/overloadOnConstNoStringImplementation2.ts (4 errors) ====
    interface I {
        x1(a: number, callback: (x: 'hi') => number);
                                ~~~~~~~~~~~~~~~~~~~
!!! Specialized overload signature is not assignable to any non-specialized signature.
    }
    
    class C implements I {
        x1(a: number, callback: (x: 'hi') => number);
                                ~~~~~~~~~~~~~~~~~~~
!!! Specialized overload signature is not assignable to any non-specialized signature.
        x1(a: number, callback: (x: any) => number) {
            callback('hi');
            callback('bye');
            var hm = "hm";
            callback(hm);
            callback(1);
        }
    }
    
    var c: C;
    c.x1(1, (x: 'hi') => { return 1; } );
            ~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! A signature with an implementation cannot use a string literal type.
    c.x1(1, (x: 'bye') => { return 1; } ); 
            ~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! A signature with an implementation cannot use a string literal type.
    c.x1(1, (x: string) => { return 1; } );
    c.x1(1, (x: number) => { return 1; } );