1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity3.ts(18,1): error TS2322: Type 'E<string>' is not assignable to type 'C<string>'.
Types of property 'foo' are incompatible.
Type '(x: string, y?: number) => void' is not assignable to type '(x: string, y: string) => void'.
Types of parameters 'y' and 'y' are incompatible.
Type 'string' is not assignable to type 'number'.
==== tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity3.ts (1 errors) ====
// subclassing is not transitive when you can remove required parameters and add optional parameters
class C<T> {
foo(x: T, y: T) { }
}
class D<T> extends C<T> {
foo(x: T) { } // ok to drop parameters
}
class E<T> extends D<T> {
foo(x: T, y?: number) { } // ok to add optional parameters
}
var c: C<string>;
var d: D<string>;
var e: E<string>;
c = e;
~
!!! error TS2322: Type 'E<string>' is not assignable to type 'C<string>'.
!!! error TS2322: Types of property 'foo' are incompatible.
!!! error TS2322: Type '(x: string, y?: number) => void' is not assignable to type '(x: string, y: string) => void'.
!!! error TS2322: Types of parameters 'y' and 'y' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type 'number'.
var r = c.foo('', '');
var r2 = e.foo('', 1);
|
