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
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
// @strict: true
// Check that `any` is a strict supertype of `unknown`
declare const ru1: { [x: string]: unknown };
declare const ra1: { [x: string]: any };
const a1a = [ru1, ra1]; // { [x: string]: any }[]
const a1b = [ra1, ru1]; // { [x: string]: any }[]
declare const ra2: { [x: string]: any };
declare const ru2: { [x: string]: unknown };
const a2a = [ru2, ra2]; // { [x: string]: any }[]
const a2b = [ra2, ru2]; // { [x: string]: any }[]
// Check that `{}` is strict supertype of any non-empty object
const c3 = {};
declare const r3: { [x: string]: unknown }
const a3a = [c3, r3]; // {}[]
const a3b = [r3, c3]; // {}[]
declare const r4: { [x: string]: unknown }
const c4 = {};
const a4a = [c4, r4]; // {}[]
const a4b = [r4, c4]; // {}[]
// Check that {} is a strict supertype of Record<string, unknown>
declare function isObject1(value: unknown): value is Record<string, unknown>;
function gg1(x: {}) {
if (isObject1(x)) {
x; // Record<string, unknown>
}
else {
x; // {}
}
x; // {}
}
declare function isObject2(value: unknown): value is {};
function gg2(x: Record<string, unknown>) {
if (isObject2(x)) {
x; // Record<string, unknown>
}
else {
x; // never
}
x; // Record<string, unknown>
}
// Check that {} is a strict supertype of Record<string, any>
declare function isObject3(value: unknown): value is Record<string, any>;
function gg3(x: {}) {
if (isObject3(x)) {
x; // Record<string, any>
}
else {
x; // {}
}
x; // {}
}
declare function isObject4(value: unknown): value is {};
function gg4(x: Record<string, any>) {
if (isObject4(x)) {
x; // Record<string, any>
}
else {
x; // never
}
x; // Record<string, any>
}
// Repro from #50916
type Identity<T> = {[K in keyof T]: T[K]};
type Self<T> = T extends unknown ? Identity<T> : never;
function is<T>(value: T): value is Self<T> {
return true;
}
type Union = {a: number} | {b: number} | {c: number};
function example(x: Union) {
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
if (is(x)) {}
x; // Union
}
function checksArrayOrObject1(obj: Record<string, any> | Record<string, any>[]) {
// "accidentally" guards the first branch on the length
if (Array.isArray(obj) && obj.length) {
for (let key in obj) {
if (obj[key] !== undefined) {
console.log(obj[key])
}
}
}
else {
// 'obj' should probably not include an array type here.
for (let key in obj) {
if (obj[key] !== undefined) {
console.log(obj[key])
}
}
}
}
function checksArrayOrObject2(obj: Record<string, any> | Record<string, any>[]) {
if (Array.isArray(obj)) {
// obj should only be an array type here
for (let key in obj) {
if (obj[key] !== undefined) {
console.log(obj[key])
}
}
}
else {
// 'obj' should probably not include an array type here.
for (let key in obj) {
if (obj[key] !== undefined) {
console.log(obj[key])
}
}
}
}
|
