moved links initialization

mysql-test/r/delete.result:
  test of delete error
mysql-test/t/delete.test:
  test of delete error

mysql-test/r/delete.result

@@ -24,3 +24,12 @@ create table t1 (a bigint not null, primary key (a,a,a,a,a,a,a,a,a,a));
 insert into t1 values (2),(4),(6),(8),(10),(12),(14),(16),(18),(20),(22),(24),(26),(23),(27);
 delete from t1 where a=27;
 drop table t1;
+drop table if exists t;
+CREATE TABLE `t` (
+`i` int(10) NOT NULL default '0',
+`i2` int(10) NOT NULL default '0',
+PRIMARY KEY  (`i`)
+) TYPE=MyISAM CHARSET=latin1;
+DELETE FROM t USING t WHERE post='1';
+Unknown column 'post' in 'where clause'
+drop table if exists t;

mysql-test/t/delete.test

@@ -35,3 +35,13 @@ create table t1 (a bigint not null, primary key (a,a,a,a,a,a,a,a,a,a));
 insert into t1 values (2),(4),(6),(8),(10),(12),(14),(16),(18),(20),(22),(24),(26),(23),(27);
 delete from t1 where a=27;
 drop table t1;
+
+drop table if exists t;
+CREATE TABLE `t` (
+  `i` int(10) NOT NULL default '0',
+  `i2` int(10) NOT NULL default '0',
+  PRIMARY KEY  (`i`)
+) TYPE=MyISAM CHARSET=latin1;
+-- error 1054
+DELETE FROM t USING t WHERE post='1';
+drop table if exists t;

sql/sql_lex.cc

@@ -941,8 +941,6 @@ int yylex(void *arg, void *yythd)
 
 void st_select_lex_node::init_query()
 {
-  next= master= slave= link_next= 0;
-  prev= link_prev= 0;
   dependent= 0;
 }
 
@@ -1011,6 +1009,7 @@ void st_select_lex_node::include_down(st_select_lex_node *upper)
   prev= &upper->slave;
   upper->slave= this;
   master= upper;
+  slave= 0;
 }
 
 /* include neighbour (on same level) */
@@ -1021,6 +1020,7 @@ void st_select_lex_node::include_neighbour(st_select_lex_node *before)
   prev= &before->next;
   before->next= this;
   master= before->master;
+  slave= 0;
 }
 
 /* including in global SELECT_LEX list */

sql/sql_lex.h

@@ -194,6 +194,7 @@ enum olap_type
     Base class for st_select_lex (SELECT_LEX) & 
     st_select_lex_unit (SELECT_LEX_UNIT)
 */
+struct st_lex;
 class st_select_lex;
 class st_select_lex_unit;
 class st_select_lex_node {
@@ -252,6 +253,7 @@ public:
   void mark_as_dependent(st_select_lex *last);
 
   friend class st_select_lex_unit;
+  friend bool mysql_new_select(struct st_lex *lex, bool move_down);
 private:
   void fast_exclude();
 };

sql/sql_parse.cc

@@ -2991,11 +2991,13 @@ mysql_init_query(THD *thd)
   lex->select_lex.init_query();
   lex->value_list.empty();
   lex->param_list.empty();
+  lex->unit.next= lex->unit.master= lex->unit.link_next= 0;
+  lex->unit.prev= lex->unit.link_prev= 0;
   lex->unit.global_parameters= lex->unit.slave= lex->current_select=
     lex->all_selects_list= &lex->select_lex;
   lex->select_lex.master= &lex->unit;
   lex->select_lex.prev= &lex->unit.slave;
-  lex->select_lex.link_next= 0;
+  lex->select_lex.link_next= lex->select_lex.slave= lex->select_lex.next= 0;
   lex->select_lex.link_prev= (st_select_lex_node**)&(lex->all_selects_list);
   lex->olap=lex->describe=0;
   lex->derived_tables= false;
@@ -3045,6 +3047,8 @@ mysql_new_select(LEX *lex, bool move_down)
     unit->init_query();
     unit->init_select();
     unit->include_down(lex->current_select);
+    unit->link_next= 0;
+    unit->link_prev= 0;
     select_lex->include_down(unit);
   }
   else