Fix for BUG#13597 - columns in ON condition not resolved if references a table in a nested right join.

The problem was in that when finding the last table reference in a nested join tree,
the procedure doing the iteration over the right-most branches of a join tree
was testing for RIGHT JOINs the table reference that represents the join, and not
the second operand of the JOIN. Currently the information whether a join is LEFT/RIGHT
is stored not on the join object itself, but on one of its operands.


mysql-test/r/select.result:
  Added test for BUG#13597
mysql-test/t/select.test:
  Added test for BUG#13597
sql/table.cc:
  - test whether a table reference is a right join by testing the
    rigth join operand (first in the list of operands), and not
    the table reference that represents the join itself.
  - clearer comments

mysql-test/r/select.result

@@ -3038,3 +3038,26 @@ id
 102
 drop table t1, t2;
 drop view v1, v2, v3;
+create table a (
+id int(11) not null default '0'
+) engine=myisam default charset=latin1;
+insert into a values (123),(191),(192);
+create table b (
+id char(16) character set utf8 not null default ''
+) engine=myisam default charset=latin1;
+insert into b values ('58013'),('58014'),('58015'),('58016');
+create table c (
+a_id int(11) not null default '0',
+b_id char(16) character set utf8 default null
+) engine=myisam default charset=latin1;
+insert into c values
+(123,null),(123,null),(123,null),(123,null),(123,null),(123,'58013');
+select count(*)
+from a inner join (c left join b on b.id = c.b_id) on a.id = c.a_id;
+count(*)
+6
+select count(*)
+from a inner join (b right join c on b.id = c.b_id) on a.id = c.a_id;
+count(*)
+6
+drop table a, b, c;

mysql-test/t/select.test

@@ -2575,3 +2575,37 @@ select * from v1 left join v3 using (id);
 
 drop table t1, t2;
 drop view v1, v2, v3;
+
+#
+# Bug #13597 Column in ON condition not resolved if references a table in
+# nested right join.
+#
+
+create table a (
+  id int(11) not null default '0'
+) engine=myisam default charset=latin1;
+
+insert into a values (123),(191),(192);
+
+create table b (
+  id char(16) character set utf8 not null default ''
+) engine=myisam default charset=latin1;
+
+insert into b values ('58013'),('58014'),('58015'),('58016');
+
+create table c (
+  a_id int(11) not null default '0',
+  b_id char(16) character set utf8 default null
+) engine=myisam default charset=latin1;
+
+insert into c values
+(123,null),(123,null),(123,null),(123,null),(123,null),(123,'58013');
+
+-- both queries are equivalent
+select count(*)
+from a inner join (c left join b on b.id = c.b_id) on a.id = c.a_id;
+
+select count(*)
+from a inner join (b right join c on b.id = c.b_id) on a.id = c.a_id;
+
+drop table a, b, c;

sql/table.cc

@@ -2291,8 +2291,10 @@ TABLE_LIST *st_table_list::first_leaf_for_name_resolution()
     List_iterator_fast<TABLE_LIST> it(cur_nested_join->join_list);
     cur_table_ref= it++;
     /*
-      If 'this' is a RIGHT JOIN, the operands in 'join_list' are in reverse
+      If the current nested join is a RIGHT JOIN, the operands in
-      order, thus the first operand is already at the front of the list.
+      'join_list' are in reverse order, thus the first operand is
+      already at the front of the list. Otherwise the first operand
+      is in the end of the list of join operands.
     */
     if (!(cur_table_ref->outer_join & JOIN_TYPE_RIGHT))
     {
@@ -2343,9 +2345,11 @@ TABLE_LIST *st_table_list::last_leaf_for_name_resolution()
        cur_nested_join;
        cur_nested_join= cur_table_ref->nested_join)
   {
+    cur_table_ref= cur_nested_join->join_list.head();
     /*
-      If 'this' is a RIGHT JOIN, the operands in 'join_list' are in reverse
+      If the current nested is a RIGHT JOIN, the operands in
-      order, thus the last operand is in the end of the list.
+      'join_list' are in reverse order, thus the last operand is in the
+      end of the list.
     */
     if ((cur_table_ref->outer_join & JOIN_TYPE_RIGHT))
     {
@@ -2355,8 +2359,6 @@ TABLE_LIST *st_table_list::last_leaf_for_name_resolution()
       while ((next= it++))
         cur_table_ref= next;
     }
-    else
-      cur_table_ref= cur_nested_join->join_list.head();
     if (cur_table_ref->is_leaf_for_name_resolution())
       break;
   }