//// [subtypingWithObjectMembersOptionality.ts] // Derived member is not optional but base member is, should be ok interface Base { foo: string; } interface Derived extends Base { bar: string; } interface Derived2 extends Derived { baz: string; } // S is a subtype of a type T, and T is a supertype of S, if one of the following is true, where S' denotes the apparent type (section 3.8.1) of S: // - S' and T are object types and, for each member M in T, one of the following is true: // - M is a property and S' contains a property N where // M and N have the same name, // the type of N is a subtype of that of M, // M and N are both public or both private, and // if M is a required property, N is also a required property. // - M is an optional property and S' contains no property of the same name as M. interface T { Foo?: Base; } interface S extends T { Foo: Derived } interface T2 { 1?: Base; } interface S2 extends T2 { 1: Derived; } interface T3 { '1'?: Base; } interface S3 extends T3 { '1.': Derived; } // object literal case var a: { Foo?: Base; }; var b = { Foo: null }; var r = true ? a : b; module TwoLevels { interface T { Foo?: Base; } interface S extends T { Foo: Derived2 } interface T2 { 1?: Base; } interface S2 extends T2 { 1: Derived2; } interface T3 { '1'?: Base; } interface S3 extends T3 { '1.': Derived2; } // object literal case var a: { Foo?: Base; }; var b = { Foo: null }; var r = true ? a : b; } //// [subtypingWithObjectMembersOptionality.js] // Derived member is not optional but base member is, should be ok // object literal case var a; var b = { Foo: null }; var r = true ? a : b; var TwoLevels; (function (TwoLevels) { // object literal case var a; var b = { Foo: null }; var r = true ? a : b; })(TwoLevels || (TwoLevels = {}));