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Merge pull request #22850 from Microsoft/tupleTypeInference

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Only make inferences from tuple types of right arity
This commit is contained in:
Anders Hejlsberg
2018-03-26 09:35:45 -07:00
committed by GitHub
parent fdc468976e 63f98de813
commit d7df84d641
5 changed files with 275 additions and 3 deletions
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12
src/compiler/checker.ts
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@@ -11603,6 +11603,13 @@ namespace ts {
return undefined;
}
function typesDefinitelyUnrelated(source: Type, target: Type) {
// Two tuple types with different arity are definitely unrelated.
// Two object types that each have a property that is unmatched in the other are definitely unrelated.
return isTupleType(source) && isTupleType(target) && getTypeReferenceArity(<TypeReference>source) !== getTypeReferenceArity(<TypeReference>target) ||
!!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false) && !!getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false);
}
function getTypeFromInference(inference: InferenceInfo) {
return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) :
inference.contraCandidates ? getIntersectionType(inference.contraCandidates) :
@@ -11873,9 +11880,8 @@ namespace ts {
return;
}
}
// Infer from the members of source and target only if the two types are possibly related. We check
// in both directions because we may be inferring for a co-variant or a contra-variant position.
if (!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false) || !getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false)) {
// Infer from the members of source and target only if the two types are possibly related
if (!typesDefinitelyUnrelated(source, target)) {
inferFromProperties(source, target);
inferFromSignatures(source, target, SignatureKind.Call);
inferFromSignatures(source, target, SignatureKind.Construct);