tests/cases/compiler/contextualTypingOfObjectLiterals2.ts(5,18): error TS2339: Property 'hmm' does not exist on type 'string'. ==== tests/cases/compiler/contextualTypingOfObjectLiterals2.ts (1 errors) ==== interface Foo { foo: (t: string) => string; } function f2(args: Foo) { } f2({ foo: s => s.hmm }) // 's' should be 'string', so this should be an error ~~~ !!! error TS2339: Property 'hmm' does not exist on type 'string'.