revert

  revid:georgi.kodinov@oracle.com-20120309130449-82e3bs5v3et1x0ef
  committer: Georgi Kodinov <Georgi.Kodinov@Oracle.com>
  timestamp: Fri 2012-03-09 15:04:49 +0200
  message:
    Bug #12408412: GROUP_CONCAT + ORDER BY + INPUT/OUTPUT SAME 
    USER VARIABLE = CRASH
    Moved the preparation of the variables that receive the output from 
    SELECT INTO from execution time (JOIN:execute) to compile time 
    (JOIN::prepare). This ensures that if the same variable is used in the
    SELECT part of SELECT INTO it will be properly marked as non-const
    for this query.
    Test case added.
    Used proper fast iterator.

a better fix (much smaller and without regressions) is coming from 5.1

mysql-test/t/user_var.test

@@ -416,14 +416,6 @@ DROP TRIGGER trg1;
 DROP TABLE t1;
 
 
---echo #
---echo # Bug #12408412: GROUP_CONCAT + ORDER BY + INPUT/OUTPUT
---echo #   SAME USER VARIABLE = CRASH
---echo #
-
-SET @bug12408412=1;
-SELECT GROUP_CONCAT(@bug12408412 ORDER BY 1) INTO @bug12408412;
-
 #
 # MDEV-616 LP BUG#1002126
 # Bug #11764371 57196: MORE FUN WITH ASSERTION: !TABLE->FILE ||

sql/sql_class.cc

@@ -3110,42 +3110,13 @@ int select_exists_subselect::send_data(List<Item> &items)
 int select_dumpvar::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
 {
   unit= u;
-  List_iterator_fast<my_var> var_li(var_list);
-  List_iterator_fast<Item> it(list);
-  Item *item;
-  my_var *mv;
-  Item_func_set_user_var **suv;
   
   if (var_list.elements != list.elements)
   {
     my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
                ER(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT), MYF(0));
     return 1;
-  }
-
-  /*
-    Iterate over the destination variables and mark them as being
-    updated in this query.
-    We need to do this at JOIN::prepare time to ensure proper
-    const detection of Item_func_get_user_var that is determined
-    by the presence of Item_func_set_user_vars
-  */
-
-  suv= set_var_items= (Item_func_set_user_var **) 
-    sql_alloc(sizeof(Item_func_set_user_var *) * list.elements);
-
-  while ((mv= var_li++) && (item= it++))
-  {
-    if (!mv->local)
-    {
-      *suv= new Item_func_set_user_var(mv->s, item);
-      (*suv)->fix_fields(thd, 0);
-    }
-    else
-      *suv= NULL;
-    suv++;
-  }
-
+  }               
   return 0;
 }
 
@@ -3465,7 +3436,6 @@ int select_dumpvar::send_data(List<Item> &items)
   List_iterator<Item> it(items);
   Item *item;
   my_var *mv;
-  Item_func_set_user_var **suv;
   DBUG_ENTER("select_dumpvar::send_data");
 
   if (unit->offset_limit_cnt)
@@ -3478,19 +3448,20 @@ int select_dumpvar::send_data(List<Item> &items)
     my_message(ER_TOO_MANY_ROWS, ER(ER_TOO_MANY_ROWS), MYF(0));
     DBUG_RETURN(1);
   }
-  for (suv= set_var_items; ((mv= var_li++) && (item= it++)); suv++)
+  while ((mv= var_li++) && (item= it++))
   {
     if (mv->local)
     {
-      DBUG_ASSERT(!*suv);
       if (thd->spcont->set_variable(thd, mv->offset, &item))
 	    DBUG_RETURN(1);
     }
     else
     {
-      DBUG_ASSERT(*suv);
-      (*suv)->save_item_result(item);
-      if ((*suv)->update())
+      Item_func_set_user_var *suv= new Item_func_set_user_var(mv->s, item);
+      if (suv->fix_fields(thd, 0))
+        DBUG_RETURN (1);
+      suv->save_item_result(item);
+      if (suv->update())
         DBUG_RETURN (1);
     }
   }

sql/sql_class.h

@@ -4025,7 +4025,6 @@ class my_var : public Sql_alloc  {
 
 class select_dumpvar :public select_result_interceptor {
   ha_rows row_count;
-  Item_func_set_user_var **set_var_items;
 public:
   List<my_var> var_list;
   select_dumpvar()  { var_list.empty(); row_count= 0;}