tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesA.ts(2,15): error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => number'.
==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesA.ts (1 errors) ====
declare function foo3(cb: (x: number) => number): typeof cb;
var r5 = foo3((x: number) => ''); // error
~~~~~~~~~~~~~~~~~
!!! error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => number'.