bug fixed for issue #2114

src/main/java/com/alibaba/druid/sql/ast/expr/SQLVariantRefExpr.java

@@ -20,7 +20,9 @@ import com.alibaba.druid.sql.ast.SQLObject;
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class SQLVariantRefExpr extends SQLExprImpl {
 
@@ -128,6 +130,21 @@ public class SQLVariantRefExpr extends SQLExprImpl {
     public SQLVariantRefExpr clone() {
         SQLVariantRefExpr var =  new SQLVariantRefExpr(name, global);
         var.index = index;
+
+        if (attributes != null) {
+            var.attributes = new HashMap<String, Object>(attributes.size());
+            for (Map.Entry<String, Object> entry : attributes.entrySet()) {
+                String k = entry.getKey();
+                Object v = entry.getValue();
+
+                if (v instanceof SQLObject) {
+                    var.attributes.put(k, ((SQLObject) v).clone());
+                } else {
+                    var.attributes.put(k, v);
+                }
+            }
+        }
+
         return var;
     }