classIndexer3.ts(8,5): error TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor.
classIndexer3.ts(9,5): error TS2411: Property 'y' of type 'string' is not assignable to 'string' index type 'number'.
classIndexer3.ts(9,5): error TS2564: Property 'y' has no initializer and is not definitely assigned in the constructor.


==== classIndexer3.ts (3 errors) ====
    class C123 {
        [s: string]: number;
        constructor() {
        }
    }
    
    class D123 extends C123 {
        x: number;
        ~
!!! error TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor.
        y: string;
        ~
!!! error TS2411: Property 'y' of type 'string' is not assignable to 'string' index type 'number'.
        ~
!!! error TS2564: Property 'y' has no initializer and is not definitely assigned in the constructor.
    }