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Only defer aliased array and tuple types

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This commit is contained in:
Anders Hejlsberg 2019-08-27 16:18:20 -04:00
parent b18c70f8c0
commit c2d0aa8931
1 changed files with 30 additions and 5 deletions
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35
src/compiler/checker.ts
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@ -9614,15 +9614,40 @@ namespace ts {
return getTupleTypeOfArity(node.elementTypes.length, minLength, !!restElement, readonly, /*associatedNames*/ undefined);
}
function isAliasedType(node: Node): boolean {
const parent = node.parent;
switch (parent.kind) {
case SyntaxKind.ParenthesizedType:
case SyntaxKind.ArrayType:
case SyntaxKind.TupleType:
case SyntaxKind.RestType:
case SyntaxKind.UnionType:
case SyntaxKind.IntersectionType:
case SyntaxKind.IndexedAccessType:
return isAliasedType(parent);
case SyntaxKind.TypeAliasDeclaration:
return true;
}
return false;
}
function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type {
const links = getNodeLinks(node);
if (!links.resolvedType) {
const target = getArrayOrTupleTargetType(node);
const aliasSymbol = getAliasSymbolForTypeNode(node);
const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol);
links.resolvedType = target === emptyGenericType ? emptyObjectType :
node.kind === SyntaxKind.TupleType && node.elementTypes.length === 0 ? target :
createDeferredTypeReference(target, node, /*mapper*/ undefined, aliasSymbol, aliasTypeArguments);
if (target === emptyGenericType) {
links.resolvedType = emptyObjectType;
}
else if (isAliasedType(node)) {
const aliasSymbol = getAliasSymbolForTypeNode(node);
const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol);
links.resolvedType = node.kind === SyntaxKind.TupleType && node.elementTypes.length === 0 ? target :
createDeferredTypeReference(target, node, /*mapper*/ undefined, aliasSymbol, aliasTypeArguments);
}
else {
const elementTypes = node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elementTypes, getTypeFromTypeNode);
links.resolvedType = createTypeReference(target, elementTypes);
}
}
return links.resolvedType;
}