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Malte UblandClaude Opus 5.5
bb0e0a79d5
An unpinned generic declaration compared with `===`/`!==` takes its signature from the other operand (`held === ident`), which clears the pi `agent-session.ts:590` shape. That pin alone would answer `false` where JavaScript answers `true` when the program also holds the declaration at another signature, so a whole-program check refuses the comparison instead. It covers the direct form and values compared through `unknown` (the g5 silent divergence: two instances of one declaration compared unequal), resolving dynamic operands' provenance only when some declaration is held at more than one signature. - generic-functions: `identityComparisonPin` and `checkGenericIdentityPins` (runs once at the end of lowering, when every value instance is known); `GenericFnInfo.valueInstances` records the instances value references produced. - Corpus: `generic-identity-pin.ts`, `generic-identity-unknown.ts`. - Diagnostics: `generic-identity-multiple-pins.ts`, `generic-identity-unknown.ts`. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
13 lines
419 B
TypeScript
13 lines
419 B
TypeScript
// One generic declaration held at two signatures compares unequal through
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// `unknown` today (one closure per signature, one function object in
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// JavaScript). Refuse it instead of answering silently wrong.
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type Fn = (x: number) => number;
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function ident<T>(x: T): T {
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return x;
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}
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const a: Fn = ident;
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const b: (x: string) => string = ident;
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const ua = a as unknown;
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const ub = b as unknown;
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console.log(ua === ub);
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