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Fix tuple and array comparisons during identity checking (#32089)

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This commit is contained in:
Wesley Wigham
2019-06-25 20:56:41 -07:00
committed by GitHub
parent 261952247a
commit 34eb5ddf75
2 changed files with 23 additions and 1 deletions
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9
src/compiler/checker.ts
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@@ -13321,7 +13321,14 @@ namespace ts {
}
}
else if (isReadonlyArrayType(target) ? isArrayType(source) || isTupleType(source) : isArrayType(target) && isTupleType(source) && !source.target.readonly) {
return isRelatedTo(getIndexTypeOfType(source, IndexKind.Number) || anyType, getIndexTypeOfType(target, IndexKind.Number) || anyType, reportErrors);
if (relation !== identityRelation) {
return isRelatedTo(getIndexTypeOfType(source, IndexKind.Number) || anyType, getIndexTypeOfType(target, IndexKind.Number) || anyType, reportErrors);
}
else {
// By flags alone, we know that the `target` is a readonly array while the source is a normal array or tuple
// or `target` is an array and source is a tuple - in both cases the types cannot be identical, by construction
return Ternary.False;
}
}
// Consider a fresh empty object literal type "closed" under the subtype relationship - this way `{} <- {[idx: string]: any} <- fresh({})`
// and not `{} <- fresh({}) <- {[idx: string]: any}`