==== tests/cases/compiler/generics5.ts (1 errors) ====
    interface A { a: string; }
    interface B extends A { b: string; }
    
    interface C extends B { c: string; }
    interface G<T, U extends B> {
    
    
    }
    
    var v3: G<A, A>;               // Error, A not valid argument for U
            ~~~~~~~
!!! Type 'A' does not satisfy the constraint 'B':
!!!   Property 'b' is missing in type 'A'.