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Validate constraint type in mapped type

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This commit is contained in:
Anders Hejlsberg
2016-11-07 09:43:01 -08:00
parent 2564e1cd26
commit 5de63a74eb
1 changed files with 16 additions and 8 deletions
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24
src/compiler/checker.ts
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@@ -5933,14 +5933,22 @@ namespace ts {
function getTypeFromMappedTypeNode(node: MappedTypeNode, aliasSymbol?: Symbol, aliasTypeArguments?: Type[]): Type {
const links = getNodeLinks(node);
if (!links.resolvedType) {
const type = <MappedType>createObjectType(ObjectFlags.Mapped, node.symbol);
type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfNode(node.typeParameter));
type.templateType = node.type ? getTypeFromTypeNode(node.type) : anyType;
type.isReadonly = !!node.readonlyToken;
type.isOptional = !!node.questionToken;
type.aliasSymbol = aliasSymbol;
type.aliasTypeArguments = aliasTypeArguments;
links.resolvedType = type;
const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfNode(node.typeParameter));
const constraintType = getConstraintOfTypeParameter(typeParameter);
const keyType = constraintType && constraintType.flags & TypeFlags.TypeParameter ? getApparentType(constraintType) : constraintType;
if (keyType && (keyType.flags & TypeFlags.Index || checkTypeAssignableTo(keyType, stringOrNumberType, node.typeParameter.constraint))) {
const type = <MappedType>createObjectType(ObjectFlags.Mapped, node.symbol);
type.typeParameter = typeParameter;
type.templateType = node.type ? getTypeFromTypeNode(node.type) : unknownType;
type.isReadonly = !!node.readonlyToken;
type.isOptional = !!node.questionToken;
type.aliasSymbol = aliasSymbol;
type.aliasTypeArguments = aliasTypeArguments;
links.resolvedType = type;
}
else {
links.resolvedType = unknownType;
}
}
return links.resolvedType;
}