==== tests/cases/compiler/typeParameterArgumentEquivalence4.ts (2 errors) ====
    function foo<T,U>() {
        var x: (item) => U;
        var y: (item) => T;
        x = y;  // Should be an error
        ~
!!! Type '(item: any) => T' is not assignable to type '(item: any) => U':
!!!   Type 'T' is not assignable to type 'U'.
        y = x;  // Shound be an error
        ~
!!! Type '(item: any) => U' is not assignable to type '(item: any) => T':
!!!   Type 'U' is not assignable to type 'T'.
    }