Fixed bug #21646.

Presence of a subquery in the ON expression of a join 
should not block merging the view that contains this join.
Before this patch the such views were converted into 
into temporary table views.

mysql-test/r/view.result

@@ -2935,4 +2935,18 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
 DROP VIEW v1;
 DROP TABLE t1;
+CREATE TABLE t1(pk int PRIMARY KEY);
+CREATE TABLE t2(pk int PRIMARY KEY, fk int, ver int, org int);
+CREATE ALGORITHM=MERGE VIEW v1 AS 
+SELECT t1.*
+FROM t1 JOIN t2 
+ON t2.fk = t1.pk AND 
+t2.ver = (SELECT MAX(t.ver) FROM t2 t WHERE t.org = t2.org);
+SHOW WARNINGS;
+Level	Code	Message
+SHOW CREATE VIEW v1;
+View	Create View
+v1	CREATE ALGORITHM=MERGE DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select `t1`.`pk` AS `pk` from (`t1` join `t2` on(((`t2`.`fk` = `t1`.`pk`) and (`t2`.`ver` = (select max(`t`.`ver`) AS `MAX(t.ver)` from `t2` `t` where (`t`.`org` = `t2`.`org`))))))
+DROP VIEW v1;
+DROP TABLE t1, t2;
 End of 5.0 tests.

mysql-test/t/view.test

@@ -2850,4 +2850,22 @@ EXPLAIN SELECT * FROM v1 t WHERE t.s1+1 < (SELECT MAX(t1.s1) FROM t1);
 
 DROP VIEW v1;
 DROP TABLE t1;
+
+#
+# Bug #21646: view qith a subquery in ON expression 
+#
+
+CREATE TABLE t1(pk int PRIMARY KEY); 
+CREATE TABLE t2(pk int PRIMARY KEY, fk int, ver int, org int);
+
+CREATE ALGORITHM=MERGE VIEW v1 AS 
+SELECT t1.*
+  FROM t1 JOIN t2 
+       ON t2.fk = t1.pk AND 
+          t2.ver = (SELECT MAX(t.ver) FROM t2 t WHERE t.org = t2.org);
+SHOW WARNINGS;
+SHOW CREATE VIEW v1;
+
+DROP VIEW v1;
+DROP TABLE t1, t2;
 --echo End of 5.0 tests.

sql/mysql_priv.h

@@ -446,7 +446,8 @@ enum enum_parsing_place
   NO_MATTER,
   IN_HAVING,
   SELECT_LIST,
-  IN_WHERE
+  IN_WHERE,
+  IN_ON
 };
 
 struct st_table;

sql/sql_lex.cc

@@ -1710,7 +1710,8 @@ bool st_lex::can_be_merged()
          unit= unit->next_unit())
     {
       if (unit->first_select()->parent_lex == this &&
-          (unit->item == 0 || unit->item->place() != IN_WHERE))
+          (unit->item == 0 ||
+           (unit->item->place() != IN_WHERE && unit->item->place() != IN_ON)))
       {
         selects_allow_merge= 0;
         break;

sql/sql_yacc.yy

@@ -5212,11 +5212,13 @@ join_table:
             /* Change the current name resolution context to a local context. */
             if (push_new_name_resolution_context(YYTHD, $1, $3))
               YYABORT;
+            Select->parsing_place= IN_ON;
           }
           expr
 	  {
             add_join_on($3,$6);
             Lex->pop_context();
+            Select->parsing_place= NO_MATTER;
           }
         | table_ref STRAIGHT_JOIN table_factor
           ON
@@ -5225,12 +5227,14 @@ join_table:
             /* Change the current name resolution context to a local context. */
             if (push_new_name_resolution_context(YYTHD, $1, $3))
               YYABORT;
+            Select->parsing_place= IN_ON;
           }
           expr
           {
             $3->straight=1;
             add_join_on($3,$6);
             Lex->pop_context();
+            Select->parsing_place= NO_MATTER;
           }
 	| table_ref normal_join table_ref
 	  USING
@@ -5254,6 +5258,7 @@ join_table:
             /* Change the current name resolution context to a local context. */
             if (push_new_name_resolution_context(YYTHD, $1, $5))
               YYABORT;
+            Select->parsing_place= IN_ON;
           }
           expr
 	  {
@@ -5261,6 +5266,7 @@ join_table:
             Lex->pop_context();
             $5->outer_join|=JOIN_TYPE_LEFT;
             $$=$5;
+            Select->parsing_place= NO_MATTER;
           }
 	| table_ref LEFT opt_outer JOIN_SYM table_factor
 	  {
@@ -5285,6 +5291,7 @@ join_table:
             /* Change the current name resolution context to a local context. */
             if (push_new_name_resolution_context(YYTHD, $1, $5))
               YYABORT;
+            Select->parsing_place= IN_ON;
           }
           expr
           {
@@ -5293,6 +5300,7 @@ join_table:
               YYABORT;
             add_join_on($$, $8);
             Lex->pop_context();
+            Select->parsing_place= NO_MATTER;
           }
 	| table_ref RIGHT opt_outer JOIN_SYM table_factor
 	  {