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https://github.com/vercel-labs/scriptc.git
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Chris Tate
a0d2ce24f5
- recordWidthPlan narrows index-signature sources into declared-only targets (declared fields copy off their struct slots, the overflow drops with the width); absent-field completion declines there — the overflow could hold the key at runtime, and a completed undefined would drop the value Node keeps - the overflow capture initializes same-named declared target fields directly off the source, admitting REQUIRED declared members; literal writes to names the target does not declare go overflowOnly, and a dispatch-writes gate keeps the validator's collision rule for the rest - widthLiftPlan gains dynIn (a typed field into an 'unknown' slot — the static→DOM deep copy), upcast (derived into base, the prefix-layout reinterpret), and funcAdapt (funcCoerceAdapter's CLEAN subset — the stranded trap-only dispositions stay top-level, never inside a width plan) - SC2002 now names the first blocking rule per record pair (describeRecordWidthBlocker mirrors the planners' gates) and its message/hint/registry entry speak the width-copy truth — the manifest flips the one entry name - corpus 2556/2557 pin both hybrid directions and the new lifts byte-identical vs Node on both backends; diagnostics fixture record-width pins the residue's pointed messages
42 lines
1.5 KiB
TypeScript
42 lines
1.5 KiB
TypeScript
// SC2002: the RESIDUE of the width-copy family — record shapes that
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// neither match exactly nor width-coerce. Each fence names the first
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// blocking rule. (The width copies themselves — field-subset narrowing,
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// hybrid captures, per-field lifts — are differential corpus.)
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// An index-signature source cannot complete an absent optional field:
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// the overflow could hold the key at runtime, and a completed undefined
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// would drop that value.
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type Loose = { [k: string]: number };
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type PickedA = { a?: number };
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const loose: Loose = { a: 1 };
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const picked: PickedA = loose;
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console.log(picked);
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// A method field whose parameter shapes relate only BIVARIANTLY: neither
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// parameter type converts into the other mechanically, so the field does
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// not lift.
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type SrcM = { m(x: { a: number }): void; extra: number };
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type DstM = { m(x: { a: number; b: number }): void };
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const srcM: SrcM = {
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m: (x) => {
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console.log(x.a);
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},
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extra: 1,
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};
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const dstM: DstM = srcM;
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console.log(dstM);
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// A source field that cannot enter the target's value slot (a Map has no
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// DOM conversion into an 'unknown' signature slot).
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type WithMap = { m: Map<string, number>; n: number };
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const withMap: WithMap = { m: new Map(), n: 1 };
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const bag: Record<string, unknown> = withMap;
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console.log(bag);
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// A declared target field that cannot take a runtime key collision from
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// the signature slot (its type is narrower than the slot's).
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type Odd = { a?: boolean; [k: string]: boolean | string | undefined };
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const plain = { b: "hi" };
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const odd: Odd = plain;
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console.log(odd);
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