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`{ A, B }` where `B` is a class declaration failed: the shorthand path
resolved locals, globals and functions but not class names, so a class
extending EventEmitter (and, in JavaScript, a plain class declaration)
reported "the reference to 'B' (a binding form with no lowering)" or a
deferred SC2002 shape mismatch, breaking `module.exports = { A, B }`.
The shorthand now lowers a class name exactly like the identifier
(shared classNameValue), so the property holds the class value.
A statically decided instanceof with computed operands
(`new o.B() instanceof B`, `p instanceof lib.Plain`) was refused because
folding dropped the operands' evaluation; it now evaluates both
operands, left then right, and answers the folded result.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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| // A class declaration's name (`{ Name }`): the class value, exactly | ||
| // like the long form `{ Name: Name }`. | ||
| const classValue = classNameValue(lowerer, resolved, propName, loc); | ||
| if (classValue) return classValue; |
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Reading a class through shorthand before its declaration runs returns the class value instead of throwing the required ReferenceError.
| answer: IrExpr, | ||
| ): IrExpr { | ||
| const stmts: IrStmt[] = []; | ||
| if (left.kind !== "varRef") stmts.push({ kind: "exprStmt", expr: left, loc: left.loc }); |
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When a folded instanceof has an uninitialized binding on the left and a computed constructor on the right, skipping the varRef suppresses the ReferenceError and evaluates the constructor instead.
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{ A, B }whereBis a class declaration failed. The shorthand property path resolved locals, globals and functions but not class names, so a class extending EventEmitter (and, in JavaScript, a plain class declaration) reported "the reference to 'B' (a binding form with no lowering)", or in JavaScript a deferred SC2002 shape mismatch at run time. This brokemodule.exports = { Channel, Plain }and similar exports.The shorthand now lowers a class name exactly like the identifier
B(the class-name branch oflowerIdentifierExpris factored intoclassNameValueand shared), so the property holds the class value: construction through it,name, identity with the binding, andinstanceof.A statically decided
instanceofwith computed operands (new o.B() instanceof B,p instanceof lib.Plain) was refused with SC1090 because folding dropped the operands' evaluation. It now evaluates both operands, left then right, and then answers the folded result. Theinheritance.tsdiagnostics fixture no longer expects that refusal.Evidence:
Overlap: #1544 (
opt/ee-class-value-crash) also editsrelational.ts, in different hunks oflowerInstanceOf(untyped EventEmitter constructor values).🤖 Generated with Claude Code