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Use object identity check instead of IsTypeIdenticalTo

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This commit is contained in:
Anders Hejlsberg
2019-04-11 16:14:21 -10:00
parent 42302705f6
commit 2ee2ffb8e7
1 changed files with 2 additions and 2 deletions
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4
src/compiler/checker.ts
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@@ -10210,7 +10210,7 @@ namespace ts {
function getConditionalTypeWorker(root: ConditionalRoot, mapper: TypeMapper | undefined, checkType: Type, extendsType: Type, trueType: Type, falseType: Type) {
// Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`.
if (falseType.flags & TypeFlags.Never && isTypeIdenticalTo(getActualTypeVariable(trueType), getActualTypeVariable(checkType))) {
if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) {
if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true
return trueType;
}
@@ -10218,7 +10218,7 @@ namespace ts {
return neverType;
}
}
else if (trueType.flags & TypeFlags.Never && isTypeIdenticalTo(getActualTypeVariable(falseType), getActualTypeVariable(checkType))) {
else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) {
if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true
return neverType;
}