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jakebaileyjakebailey
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Disallow instantiation expressions on the right side of instanceof (microsoft#53323)
1 parent b1ef5b7 commit b7b0b52

7 files changed

+183
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‎src/compiler/checker.ts

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@@ -34353,6 +34353,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) {
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checkGrammarExpressionWithTypeArguments(node);
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forEach(node.typeArguments, checkSourceElement);
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if (node.kind === SyntaxKind.ExpressionWithTypeArguments) {
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const parent = walkUpParenthesizedExpressions(node.parent);
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if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.InstanceOfKeyword && isNodeDescendantOf(node, (parent as BinaryExpression).right)) {
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error(node, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_not_be_an_instantiation_expression);
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}
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}
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const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) :
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isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) :
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checkExpression(node.exprName);

‎src/compiler/diagnosticMessages.json

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@@ -3615,6 +3615,10 @@
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"category": "Error",
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"code": 2847
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},
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"The right-hand side of an 'instanceof' expression must not be an instantiation expression.": {
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"category": "Error",
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"code": 2848
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},
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"Import declaration '{0}' is using private name '{1}'.": {
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"category": "Error",

‎tests/baselines/reference/instanceofOnInstantiationExpression.errors.txt

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tests/cases/compiler/instanceofOnInstantiationExpression.ts(10,21): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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tests/cases/compiler/instanceofOnInstantiationExpression.ts(11,22): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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tests/cases/compiler/instanceofOnInstantiationExpression.ts(12,23): error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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==== tests/cases/compiler/instanceofOnInstantiationExpression.ts (3 errors) ====
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declare class Box<T> {
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value: T;
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}
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declare const maybeBox: unknown;
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maybeBox instanceof Box; // OK
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maybeBox instanceof Box<number>; // error
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~~~~~~~~~~~
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!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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maybeBox instanceof (Box<number>); // error
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~~~~~~~~~~~
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!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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maybeBox instanceof ((Box<number>)); // error
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~~~~~~~~~~~
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!!! error TS2848: The right-hand side of an 'instanceof' expression must not be an instantiation expression.
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Box<number> instanceof Object; // OK
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(Box<number>) instanceof Object; // OK
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((Box<number>)) instanceof Object; // OK
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‎tests/baselines/reference/instanceofOnInstantiationExpression.js

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//// [instanceofOnInstantiationExpression.ts]
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declare class Box<T> {
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value: T;
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}
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declare const maybeBox: unknown;
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maybeBox instanceof Box; // OK
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maybeBox instanceof Box<number>; // error
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maybeBox instanceof (Box<number>); // error
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maybeBox instanceof ((Box<number>)); // error
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Box<number> instanceof Object; // OK
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(Box<number>) instanceof Object; // OK
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((Box<number>)) instanceof Object; // OK
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//// [instanceofOnInstantiationExpression.js]
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maybeBox instanceof Box; // OK
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maybeBox instanceof (Box); // error
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maybeBox instanceof (Box); // error
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maybeBox instanceof ((Box)); // error
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(Box) instanceof Object; // OK
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(Box) instanceof Object; // OK
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((Box)) instanceof Object; // OK

‎tests/baselines/reference/instanceofOnInstantiationExpression.symbols

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=== tests/cases/compiler/instanceofOnInstantiationExpression.ts ===
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declare class Box<T> {
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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>T : Symbol(T, Decl(instanceofOnInstantiationExpression.ts, 0, 18))
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value: T;
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>value : Symbol(Box.value, Decl(instanceofOnInstantiationExpression.ts, 0, 22))
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>T : Symbol(T, Decl(instanceofOnInstantiationExpression.ts, 0, 18))
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}
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declare const maybeBox: unknown;
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>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
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maybeBox instanceof Box; // OK
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>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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maybeBox instanceof Box<number>; // error
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>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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maybeBox instanceof (Box<number>); // error
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>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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maybeBox instanceof ((Box<number>)); // error
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>maybeBox : Symbol(maybeBox, Decl(instanceofOnInstantiationExpression.ts, 5, 13))
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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Box<number> instanceof Object; // OK
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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(Box<number>) instanceof Object; // OK
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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((Box<number>)) instanceof Object; // OK
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>Box : Symbol(Box, Decl(instanceofOnInstantiationExpression.ts, 0, 0))
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>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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‎tests/baselines/reference/instanceofOnInstantiationExpression.types

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=== tests/cases/compiler/instanceofOnInstantiationExpression.ts ===
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declare class Box<T> {
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>Box : Box<T>
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value: T;
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>value : T
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}
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declare const maybeBox: unknown;
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>maybeBox : unknown
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maybeBox instanceof Box; // OK
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>maybeBox instanceof Box : boolean
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>maybeBox : unknown
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>Box : typeof Box
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maybeBox instanceof Box<number>; // error
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>maybeBox instanceof Box<number> : boolean
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>maybeBox : unknown
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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maybeBox instanceof (Box<number>); // error
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>maybeBox instanceof (Box<number>) : boolean
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>maybeBox : unknown
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>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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maybeBox instanceof ((Box<number>)); // error
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>maybeBox instanceof ((Box<number>)) : boolean
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>maybeBox : unknown
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>((Box<number>)) : { new (): Box<number>; prototype: Box<any>; }
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>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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Box<number> instanceof Object; // OK
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>Box<number> instanceof Object : boolean
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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>Object : ObjectConstructor
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(Box<number>) instanceof Object; // OK
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>(Box<number>) instanceof Object : boolean
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>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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>Object : ObjectConstructor
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((Box<number>)) instanceof Object; // OK
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>((Box<number>)) instanceof Object : boolean
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>((Box<number>)) : { new (): Box<number>; prototype: Box<any>; }
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>(Box<number>) : { new (): Box<number>; prototype: Box<any>; }
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>Box<number> : { new (): Box<number>; prototype: Box<any>; }
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>Box : typeof Box
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>Object : ObjectConstructor
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‎tests/cases/compiler/instanceofOnInstantiationExpression.ts

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declare class Box<T> {
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value: T;
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}
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declare const maybeBox: unknown;
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maybeBox instanceof Box; // OK
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maybeBox instanceof Box<number>; // error
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maybeBox instanceof (Box<number>); // error
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maybeBox instanceof ((Box<number>)); // error
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Box<number> instanceof Object; // OK
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(Box<number>) instanceof Object; // OK
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((Box<number>)) instanceof Object; // OK

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