==== tests/cases/compiler/interfaceWithCallSignaturesThatHidesBaseSignature2.ts (1 errors) ====
    interface Foo {
        (): { a: number; b: number };
    }
    
    interface Derived extends Foo { // error
              ~~~~~~~
!!! interfaceWithCallSignaturesThatHidesBaseSignature2.ts(5,11): error TS2143: Interface 'Derived' cannot extend interface 'Foo':
!!! 	Call signatures of types 'Derived' and 'Foo' are incompatible:
!!! 		Type '{ a: number; }' is missing property 'b' from type '{ a: number; b: number; }'.
        (): { a: number };
    }
    
    var d: Derived;
    var r = d();