==== tests/cases/compiler/typeParameterArgumentEquivalence2.ts (2 errors) ====
    function foo<T,U>() {
        var x: (item: U) => boolean;
        var y: (item: T) => boolean;
        x = y;  // Should be an error
        ~
!!! Type '(item: T) => boolean' is not assignable to type '(item: U) => boolean':
!!!   Types of parameters 'item' and 'item' are incompatible:
!!!     Type 'T' is not assignable to type 'U'.
        y = x;  // Shound be an error
        ~
!!! Type '(item: U) => boolean' is not assignable to type '(item: T) => boolean':
!!!   Types of parameters 'item' and 'item' are incompatible:
!!!     Type 'U' is not assignable to type 'T'.
    }