tests/cases/compiler/contextualTypingOfLambdaReturnExpression.ts(5,16): error TS2339: Property 'length' does not exist on type 'number'. tests/cases/compiler/contextualTypingOfLambdaReturnExpression.ts(6,18): error TS2339: Property 'length' does not exist on type 'number'. ==== tests/cases/compiler/contextualTypingOfLambdaReturnExpression.ts (2 errors) ==== function callb(lam: (l: number) => void); function callb(lam: (n: string) => void); function callb(a) { } callb((a) => a.length); // Ok, we choose the second overload because the first one gave us an error when trying to resolve the lambda return type ~~~~~~ !!! error TS2339: Property 'length' does not exist on type 'number'. callb((a) => { a.length; }); // Error, we picked the first overload and errored when type checking the lambda body ~~~~~~ !!! error TS2339: Property 'length' does not exist on type 'number'.