tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(17,15): error TS2430: Interface 'B' incorrectly extends interface 'A'. Types of property 'bar' are incompatible. Type 'string' is not assignable to type 'Base'. Property 'foo' is missing in type 'String'. tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(27,15): error TS2430: Interface 'B2' incorrectly extends interface 'A2'. Types of property '2.0' are incompatible. Type 'string' is not assignable to type 'Base'. tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(37,15): error TS2430: Interface 'B3' incorrectly extends interface 'A3'. Types of property ''2.0'' are incompatible. Type 'string' is not assignable to type 'Base'. tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(50,15): error TS2430: Interface 'B' incorrectly extends interface 'A'. Types of property 'bar' are incompatible. Type 'string' is not assignable to type 'Base'. tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(60,15): error TS2430: Interface 'B2' incorrectly extends interface 'A2'. Types of property '2.0' are incompatible. Type 'string' is not assignable to type 'Base'. tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts(70,15): error TS2430: Interface 'B3' incorrectly extends interface 'A3'. Types of property ''2.0'' are incompatible. Type 'string' is not assignable to type 'Base'. ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithObjectMembers2.ts (6 errors) ==== interface Base { foo: string; } interface Derived extends Base { bar: string; } // N and M have the same name, same accessibility, same optionality, and N is a subtype of M // foo properties are valid, bar properties cause errors in the derived class declarations module NotOptional { interface A { foo: Base; bar: Base; } interface B extends A { ~ !!! error TS2430: Interface 'B' incorrectly extends interface 'A'. !!! error TS2430: Types of property 'bar' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. !!! error TS2430: Property 'foo' is missing in type 'String'. foo: Derived; // ok bar: string; // error } interface A2 { 1: Base; 2.0: Base; } interface B2 extends A2 { ~~ !!! error TS2430: Interface 'B2' incorrectly extends interface 'A2'. !!! error TS2430: Types of property '2.0' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. 1: Derived; // ok 2: string; // error } interface A3 { '1': Base; '2.0': Base; } interface B3 extends A3 { ~~ !!! error TS2430: Interface 'B3' incorrectly extends interface 'A3'. !!! error TS2430: Types of property ''2.0'' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. '1': Derived; // ok '2.0': string; // error } } // same cases as above but with optional module Optional { interface A { foo?: Base; bar?: Base; } interface B extends A { ~ !!! error TS2430: Interface 'B' incorrectly extends interface 'A'. !!! error TS2430: Types of property 'bar' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. foo?: Derived; // ok bar?: string; // error } interface A2 { 1?: Base; 2.0?: Base; } interface B2 extends A2 { ~~ !!! error TS2430: Interface 'B2' incorrectly extends interface 'A2'. !!! error TS2430: Types of property '2.0' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. 1?: Derived; // ok 2?: string; // error } interface A3 { '1'?: Base; '2.0'?: Base; } interface B3 extends A3 { ~~ !!! error TS2430: Interface 'B3' incorrectly extends interface 'A3'. !!! error TS2430: Types of property ''2.0'' are incompatible. !!! error TS2430: Type 'string' is not assignable to type 'Base'. '1'?: Derived; // ok '2.0'?: string; // error } }