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Remove unnecessary restrictions in property access narrowing

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This commit is contained in:
Anders Hejlsberg
2016-06-03 17:30:49 -07:00
parent 3aaa4ea833
commit 39c4e8ad1f
1 changed files with 5 additions and 15 deletions
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src/compiler/checker.ts
+5 -15
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@@ -9991,24 +9991,14 @@ namespace ts {
}
const propType = getTypeOfSymbol(prop);
// Only compute control flow type if this is a property access expression that isn't an
// assignment target, and the referenced property was declared as a variable, property,
// accessor, or optional method.
if (node.kind !== SyntaxKind.PropertyAccessExpression || isAssignmentTarget(node) ||
!(propType.flags & TypeFlags.Union) && !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor))) {
!(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) &&
!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
}
const leftmostNode = getLeftmostIdentifierOrThis(node);
if (!leftmostNode) {
return propType;
}
if (leftmostNode.kind === SyntaxKind.Identifier) {
const leftmostSymbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(<Identifier>leftmostNode));
if (!leftmostSymbol) {
return propType;
}
const declaration = leftmostSymbol.valueDeclaration;
if (!declaration || declaration.kind !== SyntaxKind.VariableDeclaration && declaration.kind !== SyntaxKind.Parameter && declaration.kind !== SyntaxKind.BindingElement) {
return propType;
}
}
return getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*includeOuterFunctions*/ false);
}