Merge of the fix for bug #9681 4.1->5.0

mysql-test/r/olap.result:
  Auto merged
mysql-test/t/olap.test:
  Auto merged
sql/sql_select.cc:
  Auto merged

mysql-test/r/olap.result

@@ -437,3 +437,16 @@ SELECT SQL_CALC_FOUND_ROWS a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 a	SUM(b)
 1	4
 DROP TABLE t1;
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP;
+a	m
+1	1
+2	2
+NULL	3
+SELECT * FROM ( SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP ) t2;
+a	m
+1	1
+2	2
+NULL	3
+DROP TABLE t1;

mysql-test/t/olap.test

@@ -178,3 +178,16 @@ SELECT a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 SELECT SQL_CALC_FOUND_ROWS a, SUM(b) FROM t1 GROUP BY a WITH ROLLUP LIMIT 1;
 
 DROP TABLE t1;
+
+#
+# Tests for bug #9681: ROLLUP in subquery for derived table wiht 
+#                      a group by field declared as NOT NULL
+#
+
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+
+SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP;
+SELECT * FROM ( SELECT a, SUM(a) m FROM  t1 GROUP BY a WITH ROLLUP ) t2;
+
+DROP TABLE t1;

sql/sql_select.cc

@@ -7772,7 +7772,7 @@ Field* create_tmp_field_from_field(THD *thd, Field* org_field,
       item->result_field= new_field;
     else
       new_field->field_name= name;
-    if (org_field->maybe_null())
+    if (org_field->maybe_null() || (item && item->maybe_null))
       new_field->flags&= ~NOT_NULL_FLAG;	// Because of outer join
     if (org_field->type() == MYSQL_TYPE_VAR_STRING ||
         org_field->type() == MYSQL_TYPE_VARCHAR)
@@ -12753,7 +12753,19 @@ bool JOIN::rollup_init()
     for (j=0 ; j < fields_list.elements ; j++)
       rollup.fields[i].push_back(rollup.null_items[i]);
   }
+  List_iterator_fast<Item> it(fields_list);
+  Item *item;
+  while ((item= it++))
+  {
+    ORDER *group_tmp;
+    for (group_tmp= group_list; group_tmp; group_tmp= group_tmp->next)
+    {
+      if (*group_tmp->item == item)
+        item->maybe_null= 1;
+    }
+  }
   return 0;
+
 }