==== tests/cases/compiler/overEagerReturnTypeSpecialization.ts (1 errors) ====
    //Note: Below simpler repro
    
    interface I1<T> {
        func<U>(callback: (value: T) => U): I1<U>;
    }
     
    declare var v1: I1<number>;
    var r1: I1<string> = v1.func(num => num.toString()) // Correctly returns an I1<string>
        ~~
!!! Type 'I1<number>' is not assignable to type 'I1<string>':
!!!   Type 'number' is not assignable to type 'string'.
               .func(str => str.length);    // should error
    
    var r2: I1<number> = v1.func(num => num.toString()) // Correctly returns an I1<string>
               .func(str => str.length);    // should be ok