HashingStorage-s clear has to return new storage instance on .clear

Author: tomasstupka

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/DynamicObjectStorage.java

@@ -341,9 +341,7 @@ private static Object runNode(DynamicObjectStorage self, Object key, Object acc,
     @ExportMessage
     @TruffleBoundary
     public HashingStorage clear() {
-        store.setShapeAndResize(store.getShape(), EMPTY_SHAPE);
-        store.updateShape();
-        return this;
+        return new DynamicObjectStorage();
     }
 
     @Override

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/EconomicMapStorage.java

@@ -372,17 +372,16 @@ static HashingStorage delItemWithStateWithSideEffect(EconomicMapStorage self, Ob
     static class Clear {
 
         @Specialization(guards = "!hasSideEffect(self)")
-        static HashingStorage clear(EconomicMapStorage self) {
-            self.map.clear();
-            return self;
+        static HashingStorage clear(@SuppressWarnings("unused") EconomicMapStorage self) {
+            return create();
         }
 
         @Specialization
         static HashingStorage clearWithSideEffect(EconomicMapStorage self,
                         @Exclusive @Cached LookupInheritedAttributeNode.Dynamic lookup,
                         @Exclusive @Cached CallUnaryMethodNode callNode) {
             if (self.map.size() == 0) {
-                return self;
+                return create();
             }
             Object[] entries = new Object[self.map.size() * 2];
             MapCursor<DictKey, Object> cursor = self.map.getEntries();
@@ -399,7 +398,7 @@ static HashingStorage clearWithSideEffect(EconomicMapStorage self,
                     callNode.executeObject(lookup.execute(o, __DEL__), o);
                 }
             }
-            return self;
+            return create();
         }
 
     }