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Disallow instantiation expressions on the right side of instanceof #53323

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Merged
merged 3 commits into from
Mar 17, 2023
Merged

Disallow instantiation expressions on the right side of instanceof #53323

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c5d76d6
Add test
jakebailey Mar 17, 2023
3478a4c
Disallow instantiation expressions on the right side of instanceof
jakebailey Mar 17, 2023
337071c
Fix bad rebase
jakebailey Mar 17, 2023
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6 changes: 6 additions & 0 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -34353,6 +34353,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) {
checkGrammarExpressionWithTypeArguments(node);
forEach(node.typeArguments, checkSourceElement);
if (node.kind === SyntaxKind.ExpressionWithTypeArguments) {
const parent = walkUpParenthesizedExpressions(node.parent);
if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.InstanceOfKeyword && isNodeDescendantOf(node, (parent as BinaryExpression).right)) {
error(node, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_not_be_an_instantiation_expression);
}
}
const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) :
isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) :
checkExpression(node.exprName);
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4 changes: 4 additions & 0 deletions src/compiler/diagnosticMessages.json
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Expand Up @@ -3615,6 +3615,10 @@
"category": "Error",
"code": 2847
},
"The right-hand side of an 'instanceof' expression must not be an instantiation expression.": {
"category": "Error",
"code": 2848
},

"Import declaration '{0}' is using private name '{1}'.": {
"category": "Error",
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29 changes: 29 additions & 0 deletions tests/baselines/reference/instanceofOnInstantiationExpression.errors.txt
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@@ -0,0 +1,29 @@
tests/cases/compiler/instanceofOnInstantiationExpression.ts(10,21): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
tests/cases/compiler/instanceofOnInstantiationExpression.ts(11,22): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
tests/cases/compiler/instanceofOnInstantiationExpression.ts(12,23): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.


==== tests/cases/compiler/instanceofOnInstantiationExpression.ts (3 errors) ====
declare class Box<T> {
value: T;
}


declare const maybeBox: unknown;

maybeBox instanceof Box; // OK

maybeBox instanceof Box<number>; // error
~~~~~~~~~~~
!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
maybeBox instanceof (Box<number>); // error
~~~~~~~~~~~
!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
maybeBox instanceof ((Box<number>)); // error
~~~~~~~~~~~
!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.

Box<number> instanceof Object; // OK
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I am checking only the right side here, but, should these even be legal? They seem useless in another way.

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Is the instantiation expression pointless? Yes. Is it harmful? No. Is it misleading? Probably not really on the LHS, since the only reason I can think of why you'd want one on the LHS is to "satisfy" the RHS, but the RHS forbids them now, soooo...

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Yeah. I don't really care either way. I guess this PR is fine as-is.

(Box<number>) instanceof Object; // OK
((Box<number>)) instanceof Object; // OK

27 changes: 27 additions & 0 deletions tests/baselines/reference/instanceofOnInstantiationExpression.js
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//// [instanceofOnInstantiationExpression.ts]
declare class Box<T> {
value: T;
}


declare const maybeBox: unknown;

maybeBox instanceof Box; // OK

maybeBox instanceof Box<number>; // error
maybeBox instanceof (Box<number>); // error
maybeBox instanceof ((Box<number>)); // error

Box<number> instanceof Object; // OK
(Box<number>) instanceof Object; // OK
((Box<number>)) instanceof Object; // OK


//// [instanceofOnInstantiationExpression.js]
maybeBox instanceof Box; // OK
maybeBox instanceof (Box); // error
maybeBox instanceof (Box); // error
maybeBox instanceof ((Box)); // error
(Box) instanceof Object; // OK
(Box) instanceof Object; // OK
((Box)) instanceof Object; // OK
42 changes: 42 additions & 0 deletions tests/baselines/reference/instanceofOnInstantiationExpression.symbols
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=== tests/cases/compiler/instanceofOnInstantiationExpression.ts ===
declare class Box<T> {
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
>T : Symbol(T, Decl(instanceofOnInstantiationExpression.ts, 0, 18))

value: T;
>value : Symbol(Box.value, Decl(instanceofOnInstantiationExpression.ts, 0, 22))
>T : Symbol(T, Decl(instanceofOnInstantiationExpression.ts, 0, 18))
}


declare const maybeBox: unknown;
>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))

maybeBox instanceof Box; // OK
>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))

maybeBox instanceof Box<number>; // error
>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))

maybeBox instanceof (Box<number>); // error
>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))

maybeBox instanceof ((Box<number>)); // error
>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))

Box<number> instanceof Object; // OK
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

(Box<number>) instanceof Object; // OK
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

((Box<number>)) instanceof Object; // OK
>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

59 changes: 59 additions & 0 deletions tests/baselines/reference/instanceofOnInstantiationExpression.types
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=== tests/cases/compiler/instanceofOnInstantiationExpression.ts ===
declare class Box<T> {
>Box : Box<T>

value: T;
>value : T
}


declare const maybeBox: unknown;
>maybeBox : unknown

maybeBox instanceof Box; // OK
>maybeBox instanceof Box : boolean
>maybeBox : unknown
>Box : typeof Box

maybeBox instanceof Box<number>; // error
>maybeBox instanceof Box<number> : boolean
>maybeBox : unknown
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box

maybeBox instanceof (Box<number>); // error
>maybeBox instanceof (Box<number>) : boolean
>maybeBox : unknown
>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box

maybeBox instanceof ((Box<number>)); // error
>maybeBox instanceof ((Box<number>)) : boolean
>maybeBox : unknown
>((Box<number>)) : { new (): Box<number>; prototype: Box<any>; }
>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box

Box<number> instanceof Object; // OK
>Box<number> instanceof Object : boolean
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box
>Object : ObjectConstructor

(Box<number>) instanceof Object; // OK
>(Box<number>) instanceof Object : boolean
>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box
>Object : ObjectConstructor

((Box<number>)) instanceof Object; // OK
>((Box<number>)) instanceof Object : boolean
>((Box<number>)) : { new (): Box<number>; prototype: Box<any>; }
>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
>Box<number> : { new (): Box<number>; prototype: Box<any>; }
>Box : typeof Box
>Object : ObjectConstructor

16 changes: 16 additions & 0 deletions tests/cases/compiler/instanceofOnInstantiationExpression.ts
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declare class Box<T> {
value: T;
}


declare const maybeBox: unknown;

maybeBox instanceof Box; // OK

maybeBox instanceof Box<number>; // error
maybeBox instanceof (Box<number>); // error
maybeBox instanceof ((Box<number>)); // error

Box<number> instanceof Object; // OK
(Box<number>) instanceof Object; // OK
((Box<number>)) instanceof Object; // OK