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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
=== tests/cases/compiler/one.ts ===
export {};
// When the non-readonly type is declared first, the unioned type of `three` in `doSomething` is never treated as readonly
const two: { a: string } = { a: 'two' };
>two : { a: string; }
>a : string
>{ a: 'two' } : { a: string; }
>a : string
>'two' : "two"
const one: { readonly a: string } = { a: 'one' };
>one : { readonly a: string; }
>a : string
>{ a: 'one' } : { a: string; }
>a : string
>'one' : "one"
function doSomething(condition: boolean) {
>doSomething : (condition: boolean) => { readonly a: string; }
>condition : boolean
// when `one` comes first in the conditional check, the return type of `doSomething` is inferred as `a` is readonly, but `a` is
// only treated as readonly (i.e. it will produce a diagnostic if you try to assign to it) based on the order of declarations of `one` and `two` above
const three = (condition) ? one : two;
>three : { readonly a: string; }
>(condition) ? one : two : { readonly a: string; }
>(condition) : boolean
>condition : boolean
>one : { readonly a: string; }
>two : { a: string; }
three.a = 'foo';
>three.a = 'foo' : "foo"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo' : "foo"
// the inferred (displayed?) type of `a` also depends on the order of the condition above. When `one` comes first, the displayed type is `any`
// when `two` comes first, the displayed type is `string`, but the diagnostic will always correctly find that it's string
three.a = 'foo2';
>three.a = 'foo2' : "foo2"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo2' : "foo2"
return three;
>three : { readonly a: string; }
}
=== tests/cases/compiler/two.ts ===
export {};
// When the non-readonly type is declared first, the unioned type of `three` in `doSomething` is never treated as readonly
const two: { a: string } = { a: 'two' };
>two : { a: string; }
>a : string
>{ a: 'two' } : { a: string; }
>a : string
>'two' : "two"
const one: { readonly a: string } = { a: 'one' };
>one : { readonly a: string; }
>a : string
>{ a: 'one' } : { a: string; }
>a : string
>'one' : "one"
function doSomething(condition: boolean) {
>doSomething : (condition: boolean) => { readonly a: string; }
>condition : boolean
// when `two` comes first in the conditional check, the return type of `doSomething` is inferred as not readonly but produces the same diagnostics as above
// based on the declaration order of `one` and `two`
const three = (condition) ? two : one;
>three : { readonly a: string; }
>(condition) ? two : one : { readonly a: string; }
>(condition) : boolean
>condition : boolean
>two : { a: string; }
>one : { readonly a: string; }
three.a = 'foo';
>three.a = 'foo' : "foo"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo' : "foo"
// the inferred (displayed?) type of `a` also depends on the order of the condition above. When `one` comes first, the displayed type is `any`
// when `two` comes first, the displayed type is `string`, but the diagnostic will always correctly find that it's string
three.a = 'foo2';
>three.a = 'foo2' : "foo2"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo2' : "foo2"
return three;
>three : { readonly a: string; }
}
=== tests/cases/compiler/three.ts ===
export {};
// When the readonly type is declared first, the unioned type of `three` in `doSomething` is always treated as readonly by the compiler
const one: { readonly a: string } = { a: 'one' };
>one : { readonly a: string; }
>a : string
>{ a: 'one' } : { a: string; }
>a : string
>'one' : "one"
const two: { a: string } = { a: 'two' };
>two : { a: string; }
>a : string
>{ a: 'two' } : { a: string; }
>a : string
>'two' : "two"
function doSomething(condition: boolean) {
>doSomething : (condition: boolean) => { readonly a: string; }
>condition : boolean
// when `one` comes first in the conditional check, the return type of `doSomething` is inferred as `a` is readonly, but `a` is
// only treated as readonly (i.e. it will produce a diagnostic if you try to assign to it) based on the order of declarations of `one` and `two` above
const three = (condition) ? one : two;
>three : { readonly a: string; }
>(condition) ? one : two : { readonly a: string; }
>(condition) : boolean
>condition : boolean
>one : { readonly a: string; }
>two : { a: string; }
three.a = 'foo';
>three.a = 'foo' : "foo"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo' : "foo"
// the inferred (displayed?) type of `a` also depends on the order of the condition above. When `one` comes first, the displayed type is `any`
// when `two` comes first, the displayed type is `string`, but the diagnostic will always correctly find that it's string
three.a = 'foo2';
>three.a = 'foo2' : "foo2"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo2' : "foo2"
return three;
>three : { readonly a: string; }
}
=== tests/cases/compiler/four.ts ===
export {};
// When the readonly type is declared first, the unioned type of `three` in `doSomething` is always treated as readonly by the compiler
const one: { readonly a: string } = { a: 'one' };
>one : { readonly a: string; }
>a : string
>{ a: 'one' } : { a: string; }
>a : string
>'one' : "one"
const two: { a: string } = { a: 'two' };
>two : { a: string; }
>a : string
>{ a: 'two' } : { a: string; }
>a : string
>'two' : "two"
function doSomething(condition: boolean) {
>doSomething : (condition: boolean) => { readonly a: string; }
>condition : boolean
// when `two` comes first in the conditional check, the return type of `doSomething` is inferred as not readonly but produces the same diagnostics as above
// based on the declaration order of `one` and `two`
const three = (condition) ? two : one;
>three : { readonly a: string; }
>(condition) ? two : one : { readonly a: string; }
>(condition) : boolean
>condition : boolean
>two : { a: string; }
>one : { readonly a: string; }
three.a = 'foo';
>three.a = 'foo' : "foo"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo' : "foo"
// the inferred (displayed?) type of `a` also depends on the order of the condition above. When `one` comes first, the displayed type is `any`
// when `two` comes first, the displayed type is `string`, but the diagnostic will always correctly find that it's string
three.a = 'foo2';
>three.a = 'foo2' : "foo2"
>three.a : any
>three : { readonly a: string; }
>a : any
>'foo2' : "foo2"
return three;
>three : { readonly a: string; }
}
|
