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
35
36
37
38
39
40
41
42
43
44
45
46
47
|
tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndConstraints3.ts(18,10): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
Type argument candidate 'Derived' is not a valid type argument because it is not a supertype of candidate 'Derived2'.
Property 'y' is missing in type 'Derived2'.
==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndConstraints3.ts (1 errors) ====
// Generic call with constraints infering type parameter from object member properties
class Base {
x: string;
}
class Derived extends Base {
y: string;
}
class Derived2 extends Base {
z: string;
}
function f<T extends Base>(a: { x: T; y: T }) {
var r: T;
return r;
}
var r1 = f({ x: new Derived(), y: new Derived2() }); // error because neither is supertype of the other
~
!!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
!!! error TS2453: Type argument candidate 'Derived' is not a valid type argument because it is not a supertype of candidate 'Derived2'.
!!! error TS2453: Property 'y' is missing in type 'Derived2'.
function f2<T extends Base, U extends { x: T; y: T }>(a: U) {
var r: T;
return r;
}
var r2 = f2({ x: new Derived(), y: new Derived2() }); // ok
var r3 = f2({ x: new Derived(), y: new Derived2() }); // ok
function f3<T extends Base>(y: (a: T) => T, x: T) {
return y(null);
}
// all ok - second argument is processed before x is fixed
var r4 = f3(x => x, new Base());
var r5 = f3(x => x, new Derived());
var r6 = f3(x => x, null);
|
