Check assignability: rest destructuring assignment

sandersn · sandersn · commit 074014e03989 · 2016-11-16T13:41:25.000-08:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -14188,12 +14188,13 @@ namespace ts {
         function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type): Type {
             const properties = node.properties;
             for (const p of properties) {
-                checkObjectLiteralDestructuringPropertyAssignment(sourceType, p);
+                checkObjectLiteralDestructuringPropertyAssignment(sourceType, p, properties);
             }
             return sourceType;
         }
 
-        function checkObjectLiteralDestructuringPropertyAssignment(objectLiteralType: Type, property: ObjectLiteralElementLike) {
+        /** Note: If property cannot be a SpreadAssignment, then allProperties does not need to be provided */
+        function checkObjectLiteralDestructuringPropertyAssignment(objectLiteralType: Type, property: ObjectLiteralElementLike, allProperties?: ObjectLiteralElementLike[]) {
             if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) {
                 const name = <PropertyName>(<PropertyAssignment>property).name;
                 if (name.kind === SyntaxKind.ComputedPropertyName) {
@@ -14223,7 +14224,14 @@ namespace ts {
                 }
             }
             else if (property.kind === SyntaxKind.SpreadAssignment) {
-                checkReferenceExpression(property.expression, Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access);
+                const nonRestNames: PropertyName[] = [];
+                if (allProperties) {
+                    for (let i = 0; i < allProperties.length - 1; i++) {
+                        nonRestNames.push(allProperties[i].name);
+                    }
+                }
+                const type = getRestType(objectLiteralType, nonRestNames, objectLiteralType.symbol);
+                return checkDestructuringAssignment(property.expression, type);
             }
             else {
                 error(property, Diagnostics.Property_assignment_expected);
@@ -14321,7 +14329,10 @@ namespace ts {
 
         function checkReferenceAssignment(target: Expression, sourceType: Type, contextualMapper?: TypeMapper): Type {
             const targetType = checkExpression(target, contextualMapper);
-            if (checkReferenceExpression(target, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access)) {
+            const error = target.parent.kind === SyntaxKind.SpreadAssignment ?
+                Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access :
+                Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access;
+            if (checkReferenceExpression(target, error)) {
                 checkTypeAssignableTo(sourceType, targetType, target, /*headMessage*/ undefined);
             }
             return sourceType;
