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fix(schema): merge index-derived props with a declared key of the same name #1659

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Merged
ssalbdivad merged 1 commit into from
Sep 19, 2026
Merged

fix(schema): merge index-derived props with a declared key of the same name #1659

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34 changes: 9 additions & 25 deletions ark/schema/structure/structure.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -227,6 +227,10 @@ const implementation: nodeImplementationOf<Structure.Declaration> =
const lInner = { ...l.inner }
const rInner = { ...r.inner }
const disjointResult = new Disjoint()
// props an index signature narrows to once the other side's keys
// are known. they can't be added to the side they came from, where
// a prop with the same key would never be merged with them
const derived: nodeOfKind<Prop.Kind>[] = []
if (l.undeclared) {
const lKey = l.keyof()
for (const k of r.requiredKeys) {
Expand All @@ -250,18 +254,8 @@ const implementation: nodeImplementationOf<Structure.Declaration> =
const indexOverlap = intersectNodesRoot(lKey, n.signature, ctx.$)
if (indexOverlap instanceof Disjoint) return []
const normalized = normalizeIndex(indexOverlap, n.value, ctx.$)
if (normalized.required) {
rInner.required = conflatenate(
rInner.required,
normalized.required
)
}
if (normalized.optional) {
rInner.optional = conflatenate(
rInner.optional,
normalized.optional
)
}
derived.push(...(normalized.required ?? []))
derived.push(...(normalized.optional ?? []))
return normalized.index ?? []
})
}
Expand Down Expand Up @@ -289,18 +283,8 @@ const implementation: nodeImplementationOf<Structure.Declaration> =
const indexOverlap = intersectNodesRoot(rKey, n.signature, ctx.$)
if (indexOverlap instanceof Disjoint) return []
const normalized = normalizeIndex(indexOverlap, n.value, ctx.$)
if (normalized.required) {
lInner.required = conflatenate(
lInner.required,
normalized.required
)
}
if (normalized.optional) {
lInner.optional = conflatenate(
lInner.optional,
normalized.optional
)
}
derived.push(...(normalized.required ?? []))
derived.push(...(normalized.optional ?? []))

return normalized.index ?? []
})
Expand All @@ -320,7 +304,7 @@ const implementation: nodeImplementationOf<Structure.Declaration> =
kind: "structure",
baseInner,
l: flattenConstraints(lInner),
r: flattenConstraints(rInner),
r: [...flattenConstraints(rInner), ...derived],
roots: [],
ctx
})
Expand Down
9 changes: 9 additions & 0 deletions ark/type/__tests__/objects/onUndeclaredKey.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,15 @@ contextualize(() => {
})
})

it("merges a narrowed index signature with a declared key", () => {
const L = type({ a: "number", "[string]": "number" })
const R = type({ a: "number", b: "number", "+": "reject" })
attest(L.and(R).expression).snap(
"{ a: number, b: number, + (undeclared): reject }"
)
attest(R.and(L).expression).equals(L.and(R).expression)
})

describe("traversal", () => {
const getExtraneousB = () => ({ a: "ok", b: "why?" })

Expand Down
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