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Tuples are known to be covaraint

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This commit is contained in:
Anders Hejlsberg 2019-01-28 08:58:18 -08:00
parent cd1f289129
commit 4335f4462c
1 changed files with 2 additions and 5 deletions
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7
src/compiler/checker.ts
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@ -13287,11 +13287,8 @@ namespace ts {
}
function getVariances(type: GenericType): Variance[] {
if (!strictFunctionTypes) {
return emptyArray;
}
if (type === globalArrayType || type === globalReadonlyArrayType) {
// Arrays are known to be covariant, no need to spend time computing this (emptyArray implies covariance for all parameters)
// Arrays and tuples are known to be covariant, no need to spend time computing this (emptyArray implies covariance for all parameters)
if (!strictFunctionTypes || type === globalArrayType || type === globalReadonlyArrayType || type.objectFlags & ObjectFlags.Tuple) {
return emptyArray;
}
return getVariancesWorker(type.typeParameters, type, getMarkerTypeReference);