//// [subtypingWithObjectMembersOptionality4.ts] // Base has required property, derived adds an optional property, no errors interface Base { foo: string; } interface Derived extends Base { bar: string; } interface T { Foo: Base; } interface S extends T { Foo2?: Derived // ok } interface T2 { 1: Base; } interface S2 extends T2 { 2?: Derived; // ok } interface T3 { '1': Base; } interface S3 extends T3 { '1.0'?: Derived; // ok } // object literal case var a: { Foo: Base; } var b: { Foo2?: Derived; } var r = true ? a : b; // ok //// [subtypingWithObjectMembersOptionality4.js] // object literal case var a; var b; var r = true ? a : b; // ok