Fixed LP bug #793386.

Auto-generated names for view field items must be allocated in
the statement memory, not in the execution memory of the statement.

mysql-test/r/view.result

@@ -4277,3 +4277,21 @@ Warnings:
 Note	1003	select `v2`.`b` AS `b` from `test`.`v2` where 0
 DROP VIEW v1,v2;
 DROP TABLE t1;
+#
+# LP bug #793386: unexpected 'Duplicate column name ''' error
+#                 at the second execution of a PS using a view 
+#
+CREATE TABLE t1 (f1 int, f2 int, f3 int, f4 int);
+CREATE VIEW v1 AS
+SELECT t.f1, t.f2, s.f3, s.f4 FROM t1 t, t1 s
+WHERE t.f4 >= s.f2 AND s.f3 < 0;
+PREPARE stmt1 FROM 
+"SELECT s.f1 AS f1, s.f2 AS f2, s.f3 AS f3, t.f4 AS f4
+    FROM v1 AS t LEFT JOIN v1 AS s ON t.f4=s.f4 WHERE t.f2 <> 1225";
+EXECUTE stmt1;
+f1	f2	f3	f4
+EXECUTE stmt1;
+f1	f2	f3	f4
+DEALLOCATE PREPARE stmt1;
+DROP VIEW v1;
+DROP TABLE t1;

mysql-test/t/view.test

@@ -4213,3 +4213,25 @@ SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b;
 
 DROP VIEW v1,v2;
 DROP TABLE t1;
+
+--echo #
+--echo # LP bug #793386: unexpected 'Duplicate column name ''' error
+--echo #                 at the second execution of a PS using a view 
+--echo #
+
+CREATE TABLE t1 (f1 int, f2 int, f3 int, f4 int);
+
+CREATE VIEW v1 AS
+  SELECT t.f1, t.f2, s.f3, s.f4 FROM t1 t, t1 s
+    WHERE t.f4 >= s.f2 AND s.f3 < 0;
+
+PREPARE stmt1 FROM 
+ "SELECT s.f1 AS f1, s.f2 AS f2, s.f3 AS f3, t.f4 AS f4
+    FROM v1 AS t LEFT JOIN v1 AS s ON t.f4=s.f4 WHERE t.f2 <> 1225";
+EXECUTE stmt1;
+EXECUTE stmt1;
+
+DEALLOCATE PREPARE stmt1;
+
+DROP VIEW v1;
+DROP TABLE t1;

sql/sql_base.cc

@@ -5861,10 +5861,15 @@ find_field_in_view(THD *thd, TABLE_LIST *table_list,
       */
       if (*ref && !(*ref)->is_autogenerated_name)
       {
+        if (register_tree_change &&
+            thd->stmt_arena->is_stmt_prepare_or_first_stmt_execute())
+          arena= thd->activate_stmt_arena_if_needed(&backup);
         item->set_name((*ref)->name, (*ref)->name_length,
                        system_charset_info);
         item->real_item()->set_name((*ref)->name, (*ref)->name_length,
                        system_charset_info);
+        if (arena)
+          thd->restore_active_arena(arena, &backup);
       }
       if (register_tree_change)
         thd->change_item_tree(ref, item);