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Destructuring assignment removes undefined from type when default value is given #9422

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Merged
mhegazy merged 2 commits into from
Jun 30, 2016
Merged

Destructuring assignment removes undefined from type when default value is given #9422

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Destructuring assignment removes undefined from type when default val…
sandersn Jun 29, 2016
5f6e25c
Use checkExpression, not checkExpressionCached
sandersn Jun 30, 2016
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Use checkExpression, not checkExpressionCached
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@sandersn
sandersn committed Jun 30, 2016
commit 5f6e25c8d2994694cefc907e50d7ba19f1e07722
2 changes: 1 addition & 1 deletion src/compiler/checker.ts
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Expand Up @@ -12547,7 +12547,7 @@ namespace ts {
// In strict null checking mode, if a default value of a non-undefined type is specified, remove
// undefined from the final type.
if (strictNullChecks &&
!(getCombinedTypeFlags(checkExpressionCached(prop.objectAssignmentInitializer)) & TypeFlags.Undefined)) {
!(getCombinedTypeFlags(checkExpression(prop.objectAssignmentInitializer)) & TypeFlags.Undefined)) {
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@ahejlsberg ahejlsberg Jun 30, 2016

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Use checkExpression here, not checkExpressionCached. The latter should only be used (a) when you know that contextual types will never have an effect on the expression and (b) when other checks of the same expression also use the caching version. Neither are true here.

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@sandersn sandersn Jun 30, 2016

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done

sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined);
}
checkBinaryLikeExpression(prop.name, prop.equalsToken, prop.objectAssignmentInitializer, contextualMapper);
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