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
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(20,1): error TS2322: Type 'MyList<string>' is not assignable to type 'List<number>'.
Types of property 'data' are incompatible.
Type 'string' is not assignable to type 'number'.
tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(22,1): error TS2322: Type 'MyList<number>' is not assignable to type 'List<string>'.
Types of property 'data' are incompatible.
Type 'number' is not assignable to type 'string'.
tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(30,5): error TS2322: Type 'U' is not assignable to type 'T'.
Type 'MyList<number>' is not assignable to type 'T'.
tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(31,5): error TS2322: Type 'T' is not assignable to type 'U'.
Type 'List<number>' is not assignable to type 'U'.
tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(42,5): error TS2322: Type 'U' is not assignable to type 'T'.
Type 'MyList<number>' is not assignable to type 'T'.
==== tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts (5 errors) ====
// Types with infinitely expanding recursive types are type checked nominally
class List<T> {
data: T;
next: List<List<T>>;
}
class MyList<T> {
data: T;
next: MyList<MyList<T>>;
}
var list1 = new List<number>();
var list2 = new List<string>();
var myList1 = new MyList<number>();
var myList2 = new MyList<string>();
list1 = myList1; // error, not nominally equal
list1 = myList2; // error, type mismatch
~~~~~
!!! error TS2322: Type 'MyList<string>' is not assignable to type 'List<number>'.
!!! error TS2322: Types of property 'data' are incompatible.
!!! error TS2322: Type 'string' is not assignable to type 'number'.
list2 = myList1; // error, not nominally equal
~~~~~
!!! error TS2322: Type 'MyList<number>' is not assignable to type 'List<string>'.
!!! error TS2322: Types of property 'data' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
list2 = myList2; // error, type mismatch
var rList1 = new List<List<number>>();
var rMyList1 = new List<MyList<number>>();
rList1 = rMyList1; // error, not nominally equal
function foo<T extends List<number>, U extends MyList<number>>(t: T, u: U) {
t = u; // error
~
!!! error TS2322: Type 'U' is not assignable to type 'T'.
!!! error TS2322: Type 'MyList<number>' is not assignable to type 'T'.
u = t; // error
~
!!! error TS2322: Type 'T' is not assignable to type 'U'.
!!! error TS2322: Type 'List<number>' is not assignable to type 'U'.
var a: List<number>;
var b: MyList<number>;
a = t; // ok
a = u; // error
b = t; // error
b = u; // ok
}
function foo2<T extends U, U extends MyList<number>>(t: T, u: U) {
t = u; // error
~
!!! error TS2322: Type 'U' is not assignable to type 'T'.
!!! error TS2322: Type 'MyList<number>' is not assignable to type 'T'.
u = t; // was error, ok after constraint made illegal, doesn't matter
var a: List<number>;
var b: MyList<number>;
a = t; // error
a = u; // error
b = t; // ok
b = u; // ok
}
|
