==== tests/cases/conformance/types/objectTypeLiteral/indexSignatures/stringIndexerConstrainsPropertyDeclarations2.ts (7 errors) ====
    // String indexer providing a constraint of a user defined type
    
    class A {
        foo(): string { return ''; }
    }
    
    class B extends A {
        bar(): string { return ''; }
    }
    
    class Foo {
        [x: string]: A;
        a: A; // ok
        b: B; // ok
        c: number; // error
        ~~~~~~~~~~
!!! Property 'c' of type 'number' is not assignable to string index type 'A'.
        d: string; // error
        ~~~~~~~~~~
!!! Property 'd' of type 'string' is not assignable to string index type 'A'.
    }
    
    interface Foo2 {
        [x: string]: A;
        a: A; // ok
        b: B; // ok
        c: number; // error
        ~~~~~~~~~~
!!! Property 'c' of type 'number' is not assignable to string index type 'A'.
        d: string; // error
        ~~~~~~~~~~
!!! Property 'd' of type 'string' is not assignable to string index type 'A'.
    }
    
    var a: {
        [x: string]: A;
        a: A; // ok
        b: B; // ok
        c: number; // error
        ~~~~~~~~~~
!!! Property 'c' of type 'number' is not assignable to string index type 'A'.
        d: string; // error
        ~~~~~~~~~~
!!! Property 'd' of type 'string' is not assignable to string index type 'A'.
    };
    
    // error
    var b: { [x: string]: A } = {
        ~
!!! Type '{ [x: string]: typeof A; a: typeof A; b: typeof B; }' is not assignable to type '{ [x: string]: A; }':
!!!   Index signatures are incompatible:
!!!     Type 'typeof A' is not assignable to type 'A':
!!!       Property 'foo' is missing in type 'typeof A'.
        a: A,
        b: B
    }