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Fix handling of index signatures in discriminated unions

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This commit is contained in:
Anders Hejlsberg
2018-12-10 16:30:21 -08:00
parent bc59582c7d
commit 9479353d5c
1 changed files with 5 additions and 1 deletions
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6
src/compiler/checker.ts
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@@ -4715,6 +4715,10 @@ namespace ts {
return prop ? getTypeOfSymbol(prop) : undefined;
}
function getTypeOfPropertyOrIndexSignature(type: Type, name: __String): Type {
return getTypeOfPropertyOfType(type, name) || isNumericLiteralName(name) && getIndexTypeOfType(type, IndexKind.Number) || getIndexTypeOfType(type, IndexKind.String) || unknownType;
}
function isTypeAny(type: Type | undefined) {
return type && (type.flags & TypeFlags.Any) !== 0;
}
@@ -15657,7 +15661,7 @@ namespace ts {
}
const propType = getTypeOfPropertyOfType(type, propName);
const narrowedPropType = propType && narrowType(propType);
return propType === narrowedPropType ? type : filterType(type, t => isTypeComparableTo(getTypeOfPropertyOfType(t, propName)!, narrowedPropType!));
return propType === narrowedPropType ? type : filterType(type, t => isTypeComparableTo(getTypeOfPropertyOrIndexSignature(t, propName), narrowedPropType!));
}
function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type {