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Propegate saved variance flags from cached comparisons

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This commit is contained in:
Wesley Wigham
2019-05-30 19:01:10 -07:00
parent 22348d8a0c
commit 20c928eb77
1 changed files with 21 additions and 0 deletions
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src/compiler/checker.ts
+21
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@@ -12981,6 +12981,17 @@ namespace ts {
return result;
}
function propegateSidebandVarianceFlags(variances: VarianceFlags[]) {
if (outofbandVarianceMarkerHandler) {
if (some(variances, v => !!(v & VarianceFlags.Unmeasurable))) {
outofbandVarianceMarkerHandler(/*onlyUnreliable*/ false);
}
if (some(variances, v => !!(v & VarianceFlags.Unreliable))) {
outofbandVarianceMarkerHandler(/*onlyUnreliable*/ true);
}
}
}
// Determine if possibly recursive types are related. First, check if the result is already available in the global cache.
// Second, check if we have already started a comparison of the given two types in which case we assume the result to be true.
// Third, check if both types are part of deeply nested chains of generic type instantiations and if so assume the types are
@@ -12998,6 +13009,16 @@ namespace ts {
// as a failure, and should be updated as a reported failure by the bottom of this function.
}
else {
if (outofbandVarianceMarkerHandler) {
// We're in the middle of variance checking - integrate any unmeasurable/unreliable flags from this cached component
if (source.flags & (TypeFlags.Object | TypeFlags.Conditional) && source.aliasSymbol &&
source.aliasTypeArguments && source.aliasSymbol === target.aliasSymbol) {
propegateSidebandVarianceFlags(getAliasVariances(source.aliasSymbol));
}
if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
propegateSidebandVarianceFlags(getVariances((<TypeReference>source).target));
}
}
return related === RelationComparisonResult.Succeeded ? Ternary.True : Ternary.False;
}
}