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Support custom 'Symbol.hasInstance' methods when narrowing 'instanceof' (#55052)
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34 files changed

+5091
-63
lines changed

34 files changed

+5091
-63
lines changed

‎src/compiler/checker.ts

Lines changed: 137 additions & 18 deletions
Large diffs are not rendered by default.

‎src/compiler/diagnosticMessages.json

Lines changed: 9 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1920,7 +1920,7 @@
19201920
"category": "Error",
19211921
"code": 2358
19221922
},
1923-
"The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.": {
1923+
"The right-hand side of an 'instanceof' expression must be either of type 'any', a class, function, or other type assignable to the 'Function' interface type, or an object type with a 'Symbol.hasInstance' method.": {
19241924
"category": "Error",
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"code": 2359
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},
@@ -3691,6 +3691,14 @@
36913691
"category": "Error",
36923692
"code": 2859
36933693
},
3694+
"The left-hand side of an 'instanceof' expression must be assignable to the first argument of the right-hand side's '[Symbol.hasInstance]' method.": {
3695+
"category": "Error",
3696+
"code": 2860
3697+
},
3698+
"An object's '[Symbol.hasInstance]' method must return a boolean value for it to be used on the right-hand side of an 'instanceof' expression.": {
3699+
"category": "Error",
3700+
"code": 2861
3701+
},
36943702

36953703
"Import declaration '{0}' is using private name '{1}'.": {
36963704
"category": "Error",

‎src/compiler/types.ts

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3053,12 +3053,17 @@ export interface TaggedTemplateExpression extends MemberExpression {
30533053
/** @internal */ questionDotToken?: QuestionDotToken; // NOTE: Invalid syntax, only used to report a grammar error.
30543054
}
30553055

3056+
export interface InstanceofExpression extends BinaryExpression {
3057+
readonly operatorToken: Token<SyntaxKind.InstanceOfKeyword>;
3058+
}
3059+
30563060
export type CallLikeExpression =
30573061
| CallExpression
30583062
| NewExpression
30593063
| TaggedTemplateExpression
30603064
| Decorator
3061-
| JsxOpeningLikeElement;
3065+
| JsxOpeningLikeElement
3066+
| InstanceofExpression;
30623067

30633068
export interface AsExpression extends Expression {
30643069
readonly kind: SyntaxKind.AsExpression;

‎src/compiler/utilities.ts

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -231,6 +231,7 @@ import {
231231
IndexSignatureDeclaration,
232232
InitializedVariableDeclaration,
233233
insertSorted,
234+
InstanceofExpression,
234235
InterfaceDeclaration,
235236
InternalEmitFlags,
236237
isAccessor,
@@ -3120,6 +3121,8 @@ export function getInvokedExpression(node: CallLikeExpression): Expression | Jsx
31203121
case SyntaxKind.JsxOpeningElement:
31213122
case SyntaxKind.JsxSelfClosingElement:
31223123
return node.tagName;
3124+
case SyntaxKind.BinaryExpression:
3125+
return node.right;
31233126
default:
31243127
return node.expression;
31253128
}
@@ -7235,6 +7238,15 @@ export function isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName(node
72357238
|| isPropertyAccessExpression(node.parent) && node.parent.name === node
72367239
|| isJSDocMemberName(node.parent) && node.parent.right === node;
72377240
}
7241+
/** @internal */
7242+
export function isInstanceOfExpression(node: Node): node is InstanceofExpression {
7243+
return isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.InstanceOfKeyword;
7244+
}
7245+
7246+
/** @internal */
7247+
export function isRightSideOfInstanceofExpression(node: Node) {
7248+
return isInstanceOfExpression(node.parent) && node === node.parent.right;
7249+
}
72387250

72397251
/** @internal */
72407252
export function isEmptyObjectLiteral(expression: Node): boolean {

‎tests/baselines/reference/api/typescript.d.ts

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5646,7 +5646,10 @@ declare namespace ts {
56465646
readonly typeArguments?: NodeArray<TypeNode>;
56475647
readonly template: TemplateLiteral;
56485648
}
5649-
type CallLikeExpression = CallExpression | NewExpression | TaggedTemplateExpression | Decorator | JsxOpeningLikeElement;
5649+
interface InstanceofExpression extends BinaryExpression {
5650+
readonly operatorToken: Token<SyntaxKind.InstanceOfKeyword>;
5651+
}
5652+
type CallLikeExpression = CallExpression | NewExpression | TaggedTemplateExpression | Decorator | JsxOpeningLikeElement | InstanceofExpression;
56505653
interface AsExpression extends Expression {
56515654
readonly kind: SyntaxKind.AsExpression;
56525655
readonly expression: Expression;

‎tests/baselines/reference/controlFlowInstanceofWithSymbolHasInstance.symbols

Lines changed: 293 additions & 0 deletions
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‎tests/baselines/reference/controlFlowInstanceofWithSymbolHasInstance.types

Lines changed: 293 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,293 @@
1+
//// [tests/cases/compiler/controlFlowInstanceofWithSymbolHasInstance.ts] ////
2+
3+
=== controlFlowInstanceofWithSymbolHasInstance.ts ===
4+
interface PromiseConstructor {
5+
[Symbol.hasInstance](value: any): value is Promise<any>;
6+
>[Symbol.hasInstance] : (value: any) => value is Promise<any>
7+
>Symbol.hasInstance : unique symbol
8+
>Symbol : SymbolConstructor
9+
>hasInstance : unique symbol
10+
>value : any
11+
}
12+
13+
interface SetConstructor {
14+
[Symbol.hasInstance](value: any): value is Set<any>;
15+
>[Symbol.hasInstance] : (value: any) => value is Set<any>
16+
>Symbol.hasInstance : unique symbol
17+
>Symbol : SymbolConstructor
18+
>hasInstance : unique symbol
19+
>value : any
20+
}
21+
22+
function f1(s: Set<string> | Set<number>) {
23+
>f1 : (s: Set<string> | Set<number>) => void
24+
>s : Set<string> | Set<number>
25+
26+
s = new Set<number>();
27+
>s = new Set<number>() : Set<number>
28+
>s : Set<string> | Set<number>
29+
>new Set<number>() : Set<number>
30+
>Set : SetConstructor
31+
32+
s; // Set<number>
33+
>s : Set<number>
34+
35+
if (s instanceof Set) {
36+
>s instanceof Set : boolean
37+
>s : Set<number>
38+
>Set : SetConstructor
39+
40+
s; // Set<number>
41+
>s : Set<number>
42+
}
43+
s; // Set<number>
44+
>s : Set<number>
45+
46+
s.add(42);
47+
>s.add(42) : Set<number>
48+
>s.add : (value: number) => Set<number>
49+
>s : Set<number>
50+
>add : (value: number) => Set<number>
51+
>42 : 42
52+
}
53+
54+
function f2(s: Set<string> | Set<number>) {
55+
>f2 : (s: Set<string> | Set<number>) => void
56+
>s : Set<string> | Set<number>
57+
58+
s = new Set<number>();
59+
>s = new Set<number>() : Set<number>
60+
>s : Set<string> | Set<number>
61+
>new Set<number>() : Set<number>
62+
>Set : SetConstructor
63+
64+
s; // Set<number>
65+
>s : Set<number>
66+
67+
if (s instanceof Promise) {
68+
>s instanceof Promise : boolean
69+
>s : Set<number>
70+
>Promise : PromiseConstructor
71+
72+
s; // Set<number> & Promise<any>
73+
>s : Set<number> & Promise<any>
74+
}
75+
s; // Set<number>
76+
>s : Set<number>
77+
78+
s.add(42);
79+
>s.add(42) : Set<number>
80+
>s.add : (value: number) => Set<number>
81+
>s : Set<number>
82+
>add : (value: number) => Set<number>
83+
>42 : 42
84+
}
85+
86+
function f3(s: Set<string> | Set<number>) {
87+
>f3 : (s: Set<string> | Set<number>) => void
88+
>s : Set<string> | Set<number>
89+
90+
s; // Set<string> | Set<number>
91+
>s : Set<string> | Set<number>
92+
93+
if (s instanceof Set) {
94+
>s instanceof Set : boolean
95+
>s : Set<string> | Set<number>
96+
>Set : SetConstructor
97+
98+
s; // Set<string> | Set<number>
99+
>s : Set<string> | Set<number>
100+
}
101+
else {
102+
s; // never
103+
>s : never
104+
}
105+
}
106+
107+
function f4(s: Set<string> | Set<number>) {
108+
>f4 : (s: Set<string> | Set<number>) => void
109+
>s : Set<string> | Set<number>
110+
111+
s = new Set<number>();
112+
>s = new Set<number>() : Set<number>
113+
>s : Set<string> | Set<number>
114+
>new Set<number>() : Set<number>
115+
>Set : SetConstructor
116+
117+
s; // Set<number>
118+
>s : Set<number>
119+
120+
if (s instanceof Set) {
121+
>s instanceof Set : boolean
122+
>s : Set<number>
123+
>Set : SetConstructor
124+
125+
s; // Set<number>
126+
>s : Set<number>
127+
}
128+
else {
129+
s; // never
130+
>s : never
131+
}
132+
}
133+
134+
// More tests
135+
136+
class A {
137+
>A : A
138+
139+
a: string;
140+
>a : string
141+
142+
static [Symbol.hasInstance]<T>(this: T, value: unknown): value is (
143+
>[Symbol.hasInstance] : <T>(this: T, value: unknown) => value is T extends abstract new (...args: any) => infer U ? U : never
144+
>Symbol.hasInstance : unique symbol
145+
>Symbol : SymbolConstructor
146+
>hasInstance : unique symbol
147+
>this : T
148+
>value : unknown
149+
150+
T extends (abstract new (...args: any) => infer U) ? U :
151+
>args : any
152+
153+
never
154+
) {
155+
return Function.prototype[Symbol.hasInstance].call(this, value);
156+
>Function.prototype[Symbol.hasInstance].call(this, value) : any
157+
>Function.prototype[Symbol.hasInstance].call : (this: Function, thisArg: any, ...argArray: any[]) => any
158+
>Function.prototype[Symbol.hasInstance] : (value: any) => boolean
159+
>Function.prototype : Function
160+
>Function : FunctionConstructor
161+
>prototype : Function
162+
>Symbol.hasInstance : unique symbol
163+
>Symbol : SymbolConstructor
164+
>hasInstance : unique symbol
165+
>call : (this: Function, thisArg: any, ...argArray: any[]) => any
166+
>this : T
167+
>value : unknown
168+
}
169+
}
170+
class B extends A { b: string }
171+
>B : B
172+
>A : A
173+
>b : string
174+
175+
class C extends A { c: string }
176+
>C : C
177+
>A : A
178+
>c : string
179+
180+
function foo(x: A | undefined) {
181+
>foo : (x: A | undefined) => void
182+
>x : A | undefined
183+
184+
x; // A | undefined
185+
>x : A | undefined
186+
187+
if (x instanceof B || x instanceof C) {
188+
>x instanceof B || x instanceof C : boolean
189+
>x instanceof B : boolean
190+
>x : A | undefined
191+
>B : typeof B
192+
>x instanceof C : boolean
193+
>x : A | undefined
194+
>C : typeof C
195+
196+
x; // B | C
197+
>x : B | C
198+
}
199+
x; // A | undefined
200+
>x : A | undefined
201+
202+
if (x instanceof B && x instanceof C) {
203+
>x instanceof B && x instanceof C : boolean
204+
>x instanceof B : boolean
205+
>x : A | undefined
206+
>B : typeof B
207+
>x instanceof C : boolean
208+
>x : B
209+
>C : typeof C
210+
211+
x; // B & C
212+
>x : B & C
213+
}
214+
x; // A | undefined
215+
>x : A | undefined
216+
217+
if (!x) {
218+
>!x : boolean
219+
>x : A | undefined
220+
221+
return;
222+
}
223+
x; // A
224+
>x : A
225+
226+
if (x instanceof B) {
227+
>x instanceof B : boolean
228+
>x : A
229+
>B : typeof B
230+
231+
x; // B
232+
>x : B
233+
234+
if (x instanceof C) {
235+
>x instanceof C : boolean
236+
>x : B
237+
>C : typeof C
238+
239+
x; // B & C
240+
>x : B & C
241+
}
242+
else {
243+
x; // B
244+
>x : B
245+
}
246+
x; // B
247+
>x : B
248+
}
249+
else {
250+
x; // A
251+
>x : A
252+
}
253+
x; // A
254+
>x : A
255+
}
256+
257+
// X is neither assignable to Y nor a subtype of Y
258+
// Y is assignable to X, but not a subtype of X
259+
260+
interface X {
261+
x?: string;
262+
>x : string | undefined
263+
}
264+
265+
class Y {
266+
>Y : Y
267+
268+
y: string;
269+
>y : string
270+
}
271+
272+
function goo(x: X) {
273+
>goo : (x: X) => void
274+
>x : X
275+
276+
x;
277+
>x : X
278+
279+
if (x instanceof Y) {
280+
>x instanceof Y : boolean
281+
>x : X
282+
>Y : typeof Y
283+
284+
x.y;
285+
>x.y : string
286+
>x : X & Y
287+
>y : string
288+
}
289+
x;
290+
>x : X
291+
}
292+
293+

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