==== tests/cases/compiler/instanceSubtypeCheck2.ts (1 errors) ====
    class C1<T> {
        x: C2<T>;
    }
    
    class C2<T> extends C1<T> {
          ~~
!!! Class 'C2<T>' incorrectly extends base class 'C1<T>':
!!!   Types of property 'x' are incompatible:
!!!     Type 'string' is not assignable to type 'C2<T>':
!!!       Property 'x' is missing in type 'String'.
        x: string
    }