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Change to more conservative conditional type relationship

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This commit is contained in:
Anders Hejlsberg
2018-03-25 15:24:31 -07:00
parent d70d505e11
commit b5a39e814f
1 changed files with 9 additions and 9 deletions
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18
src/compiler/checker.ts
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@@ -10200,18 +10200,18 @@ namespace ts {
}
else if (source.flags & TypeFlags.Conditional) {
if (target.flags & TypeFlags.Conditional) {
if (isTypeIdenticalTo((<ConditionalType>source).checkType, (<ConditionalType>target).checkType) &&
isTypeIdenticalTo((<ConditionalType>source).extendsType, (<ConditionalType>target).extendsType)) {
// Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if
// one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2,
// and Y1 is related to Y2.
if (isTypeIdenticalTo((<ConditionalType>source).extendsType, (<ConditionalType>target).extendsType) &&
(isRelatedTo((<ConditionalType>source).checkType, (<ConditionalType>target).checkType) || isRelatedTo((<ConditionalType>target).checkType, (<ConditionalType>source).checkType))) {
if (result = isRelatedTo(getTrueTypeFromConditionalType(<ConditionalType>source), getTrueTypeFromConditionalType(<ConditionalType>target), reportErrors)) {
result &= isRelatedTo(getFalseTypeFromConditionalType(<ConditionalType>source), getFalseTypeFromConditionalType(<ConditionalType>target), reportErrors);
}
}
else {
result = isRelatedTo(getDefaultConstraintOfConditionalType(<ConditionalType>source), getDefaultConstraintOfConditionalType(<ConditionalType>target), reportErrors);
}
if (result) {
errorInfo = saveErrorInfo;
return result;
if (result) {
errorInfo = saveErrorInfo;
return result;
}
}
}
else if (relation !== definitelyAssignableRelation) {