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Improved error messages for invalid assignments to properties

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This commit is contained in:
Anders Hejlsberg
2016-10-30 18:08:43 -07:00
parent 550be9c8cd
commit 6c205330a1
2 changed files with 17 additions and 4 deletions
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15
src/compiler/checker.ts
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@@ -11459,16 +11459,25 @@ namespace ts {
}
const propType = getTypeOfSymbol(prop);
const assignmentKind = getAssignmentTargetKind(node);
if (assignmentKind) {
if (isReferenceToReadonlyEntity(<Expression>node, prop) || isReferenceThroughNamespaceImport(<Expression>node)) {
error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant_or_a_read_only_property, right.text);
return unknownType;
}
}
// 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) ||
if (node.kind !== SyntaxKind.PropertyAccessExpression || assignmentKind === AssignmentKind.Definite ||
!(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) &&
!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
}
return getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
const flowType = getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType;
}
function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName, propertyName: string): boolean {
@@ -13515,7 +13524,7 @@ namespace ts {
error(expr, invalidReferenceMessage);
return false;
}
if (node.kind === SyntaxKind.Identifier) {
if (node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.PropertyAccessExpression) {
return true;
}
// Because we get the symbol from the resolvedSymbol property, it might be of kind

6
src/compiler/utilities.ts
View File

@@ -1649,8 +1649,12 @@ namespace ts {
case SyntaxKind.SpreadElementExpression:
node = parent;
break;
case SyntaxKind.PropertyAssignment:
case SyntaxKind.ShorthandPropertyAssignment:
if ((<ShorthandPropertyAssignment>parent).name !== node) {
return AssignmentKind.None;
}
// Fall through
case SyntaxKind.PropertyAssignment:
node = parent.parent;
break;
default: