Merge bk-internal.mysql.com:/home/bk/mysql-5.1-new

into  shellback.(none):/home/msvensson/mysql/mysql-5.1

mysql-test/r/subselect.result

@@ -3156,3 +3156,10 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
 2	DEPENDENT SUBQUERY	t1	index	NULL	a	8	NULL	9	Using filesort
 DROP TABLE t1;
+create table t1( f1 int,f2 int);
+insert into t1 values (1,1),(2,2);
+select tt.t from (select 'crash1' as t, f2 from t1) as tt left join t1 on tt.t = 'crash2' and tt.f2 = t1.f2 where tt.t = 'crash1';
+t
+crash1
+crash1
+drop table t1;

mysql-test/t/subselect.test

@@ -2067,3 +2067,10 @@ SELECT * FROM t1 WHERE (a,b) = ANY (SELECT a, max(b) FROM t1 GROUP BY a);
 
 DROP TABLE t1;
 
+#
+# Bug#17366: Unchecked Item_int results in server crash
+#
+create table t1( f1 int,f2 int);
+insert into t1 values (1,1),(2,2);
+select tt.t from (select 'crash1' as t, f2 from t1) as tt left join t1 on tt.t = 'crash2' and tt.f2 = t1.f2 where tt.t = 'crash1';
+drop table t1;

sql/sql_select.cc

@@ -7114,7 +7114,10 @@ static Item *eliminate_item_equal(COND *cond, COND_EQUAL *upper_levels,
   if (!cond)
     cond= new Item_cond_and(eq_list);
   else
+  {
+    DBUG_ASSERT(cond->type() == Item::COND_ITEM);
     ((Item_cond *) cond)->add_at_head(&eq_list);
+  }
 
   cond->quick_fix_field();
   cond->update_used_tables();
@@ -7199,6 +7202,11 @@ static COND* substitute_for_best_equal_field(COND *cond,
       while ((item_equal= it++))
       {
         cond= eliminate_item_equal(cond, cond_equal->upper_levels, item_equal);
+        // This occurs when eliminate_item_equal() founds that cond is
+        // always false and substitues it with Item_int 0.
+        // Due to this, value of item_equal will be 0, so just return it.
+        if (cond->type() != Item::COND_ITEM)
+          break;
       }
     }
   }