Fixed LP bug #806057.

A table expression with a natural join or a USING clause is transformed
into an equivalent expression with equi-join ON conditions. If a reference
to a virtual column happened to occur only in these generated equi-join
conditions then it was not erroneously marked in the TABLE::vcol_set bitmap.
This could lead to wrong results for queries containing natural join
expressions or USING clauses. 

mysql-test/suite/vcol/r/vcol_select_myisam.result

@@ -262,3 +262,33 @@ NULL
 explain select sum(c) from t1 group by b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+#
+# Bug #806057: join with USING over a virtual column 
+#
+CREATE TABLE t1 (b int);
+INSERT INTO t1 VALUES (NULL),( 78), (185), (0), (154);
+CREATE TABLE t2 (a int, b int AS (a) VIRTUAL);
+INSERT INTO t2 VALUES (187,187), (9,9), (187,187);
+Warnings:
+Warning	1647	The value specified for computed column 'b' in table 't2' ignored
+Warning	1647	The value specified for computed column 'b' in table 't2' ignored
+Warning	1647	The value specified for computed column 'b' in table 't2' ignored
+EXPLAIN EXTENDED
+SELECT * FROM t1 JOIN t2 USING (b);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where; Using join buffer
+Warnings:
+Note	1003	select `test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`b` = `test`.`t2`.`b`)
+SELECT * FROM t1 JOIN t2 USING (b);
+b	a
+EXPLAIN EXTENDED
+SELECT * FROM t1 NATURAL JOIN t2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where; Using join buffer
+Warnings:
+Note	1003	select `test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a` from `test`.`t1` join `test`.`t2` where (`test`.`t1`.`b` = `test`.`t2`.`b`)
+SELECT * FROM t1 NATURAL JOIN t2;
+b	a
+DROP TABLE t1,t2;

mysql-test/suite/vcol/t/vcol_select_myisam.test

@@ -48,3 +48,23 @@ eval SET @@session.storage_engine = 'MyISAM';
 #------------------------------------------------------------------------------#
 # Cleanup
 --source suite/vcol/inc/vcol_cleanup.inc
+
+--echo #
+--echo # Bug #806057: join with USING over a virtual column 
+--echo #
+
+CREATE TABLE t1 (b int);
+INSERT INTO t1 VALUES (NULL),( 78), (185), (0), (154);
+
+CREATE TABLE t2 (a int, b int AS (a) VIRTUAL);
+INSERT INTO t2 VALUES (187,187), (9,9), (187,187);
+
+EXPLAIN EXTENDED
+SELECT * FROM t1 JOIN t2 USING (b);
+SELECT * FROM t1 JOIN t2 USING (b);
+
+EXPLAIN EXTENDED
+SELECT * FROM t1 NATURAL JOIN t2;
+SELECT * FROM t1 NATURAL JOIN t2;
+
+DROP TABLE t1,t2;

sql/sql_base.cc

@@ -7151,11 +7151,16 @@ mark_common_columns(THD *thd, TABLE_LIST *table_ref_1, TABLE_LIST *table_ref_2,
       if (!(eq_cond= new Item_func_eq(item_ident_1, item_ident_2)))
         goto err;                               /* Out of memory. */
 
+      if (field_1 && field_1->vcol_info)
+        field_1->table->mark_virtual_col(field_1);
+      if (field_2 && field_2->vcol_info)
+        field_2->table->mark_virtual_col(field_2);
+
       /*
         Add the new equi-join condition to the ON clause. Notice that
         fix_fields() is applied to all ON conditions in setup_conds()
         so we don't do it here.
-       */
+      */
       add_join_on((table_ref_1->outer_join & JOIN_TYPE_RIGHT ?
                    table_ref_1 : table_ref_2),
                   eq_cond);