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Add circularity check to getReducedTypeOfUnionType

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This commit is contained in:
Anders Hejlsberg 2015-05-13 15:26:25 -07:00
parent 57b6f0a846
commit 99ba94e577
1 changed files with 11 additions and 2 deletions
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13
src/compiler/checker.ts
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@ -88,6 +88,7 @@ module ts {
let undefinedType = createIntrinsicType(TypeFlags.Undefined | TypeFlags.ContainsUndefinedOrNull, "undefined");
let nullType = createIntrinsicType(TypeFlags.Null | TypeFlags.ContainsUndefinedOrNull, "null");
let unknownType = createIntrinsicType(TypeFlags.Any, "unknown");
let resolvingType = createIntrinsicType(TypeFlags.Any, "__resolving__");
let emptyObjectType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
let anyFunctionType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
@ -3629,9 +3630,17 @@ module ts {
}
function getReducedTypeOfUnionType(type: UnionType): Type {
// If union type was created without subtype reduction, perform the deferred reduction now
// If union type was created without subtype reduction, perform the deferred reduction now. If a circularity
// is detected, simply use the type itself.
if (!type.reducedType) {
type.reducedType = getUnionType(type.types, /*noSubtypeReduction*/ false);
type.reducedType = resolvingType;
let reducedType = getUnionType(type.types, /*noSubtypeReduction*/ false);
if (type.reducedType === resolvingType) {
type.reducedType = reducedType;
}
}
else if (type.reducedType === resolvingType) {
type.reducedType = type;
}
return type.reducedType;
}