tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(1,5): error TS2322: Type '() => void' is not assignable to type '() => boolean'. Type 'void' is not assignable to type 'boolean'. tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement. ==== tests/cases/compiler/errorOnContextuallyTypedReturnType.ts (2 errors) ==== var n1: () => boolean = function () { }; // expect an error here ~~ !!! error TS2322: Type '() => void' is not assignable to type '() => boolean'. !!! error TS2322: Type 'void' is not assignable to type 'boolean'. var n2: () => boolean = function ():boolean { }; // expect an error here ~~~~~~~ !!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.