tests/cases/compiler/interfaceMemberValidation.ts(2,11): error TS2430: Interface 'i2' incorrectly extends interface 'i1'. Types of property 'name' are incompatible. Type 'number' is not assignable to type 'string'. tests/cases/compiler/interfaceMemberValidation.ts(5,2): error TS2411: Property 'bar' of type '{ (): any; (): any; }' is not assignable to string index type 'number'. tests/cases/compiler/interfaceMemberValidation.ts(10,2): error TS2374: Duplicate string index signature. ==== tests/cases/compiler/interfaceMemberValidation.ts (3 errors) ==== interface i1 { name: string; } interface i2 extends i1 { name: number; yo: string; } ~~ !!! error TS2430: Interface 'i2' incorrectly extends interface 'i1'. !!! error TS2430: Types of property 'name' are incompatible. !!! error TS2430: Type 'number' is not assignable to type 'string'. interface foo { bar():any; ~~~~~~~~~~ !!! error TS2411: Property 'bar' of type '{ (): any; (): any; }' is not assignable to string index type 'number'. bar():any; new():void; new():void; [s:string]:number; [s:string]:number; ~~~~~~~~~~~~~~~~~~ !!! error TS2374: Duplicate string index signature. }