typeParameterConstraintInstantiation.ts(8,9): error TS2454: Variable 'm' is used before being assigned.


==== typeParameterConstraintInstantiation.ts (1 errors) ====
    // Check that type parameter constraints are properly instantiated
    
    interface Mapper<T> {
        map<U extends T, V extends U[]>(f: (item: T) => U): V;
    }
    
    var m: Mapper<string>;
    var a = m.map((x: string) => x);  // string[]
            ~
!!! error TS2454: Variable 'm' is used before being assigned.
    