fixed bug in cyclic reference refinition

mysql-test/r/subselect.result:
  test of cyclic reference
mysql-test/t/subselect.test:
  test of cyclic reference
sql/sql_parse.cc:
  fixed layout
  fixed bug in cyclic reference refinition

mysql-test/r/subselect.result

@@ -10,6 +10,8 @@ SELECT (SELECT (SELECT 0 UNION SELECT 0));
 0
 SELECT (SELECT 1 FROM (SELECT 1) HAVING a=1) as a;
 Cyclic reference on subqueries
+SELECT (SELECT 1 FROM (SELECT 1) HAVING b=1) as a,(SELECT 1 FROM (SELECT 1) HAVING a=1) as b;
+Cyclic reference on subqueries
 drop table if exists t1,t2,t3,t4,t5,attend,clinic,inscrit;
 create table t1 (a int);
 create table t2 (a int, b int);

mysql-test/t/subselect.test

@@ -3,6 +3,8 @@ SELECT (SELECT 1) UNION SELECT (SELECT 2);
 SELECT (SELECT (SELECT 0 UNION SELECT 0));
 -- error 1243
 SELECT (SELECT 1 FROM (SELECT 1) HAVING a=1) as a;
+-- error 1243
+SELECT (SELECT 1 FROM (SELECT 1) HAVING b=1) as a,(SELECT 1 FROM (SELECT 1) HAVING a=1) as b;
 drop table if exists t1,t2,t3,t4,t5,attend,clinic,inscrit;
 create table t1 (a int);
 create table t2 (a int, b int);

sql/item.cc

@@ -876,11 +876,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
       {
 	depended_from= last;
 	thd->lex.current_select->mark_as_dependent(last);
-	if (check_loop(thd->check_loops_counter++))
-	{
-	  my_message(ER_CYCLIC_REFERENCE, ER(ER_CYCLIC_REFERENCE), MYF(0));
-	  return 1;
-	}
+	thd->add_possible_loop(this);
       }
     }
     else if (!ref)

sql/sql_class.cc

@@ -434,6 +434,15 @@ void THD::close_active_vio()
 }
 #endif
 
+void THD::add_possible_loop (Item *item)
+{
+  if (!possible_loops)
+  {
+    possible_loops= new List<Item>;
+  }
+  possible_loops->push_back(item);
+}
+
 /*****************************************************************************
 ** Functions to provide a interface to select results
 *****************************************************************************/

sql/sql_class.h

@@ -482,6 +482,7 @@ class THD :public ilink {
   USER_CONN *user_connect;
   CHARSET_INFO *db_charset;   
   CHARSET_INFO *thd_charset;
+  List<Item> *possible_loops; // Items that may cause loops in subselects
   List	     <MYSQL_ERROR> warn_list;  
   uint	     warn_count[(uint) MYSQL_ERROR::WARN_LEVEL_END];
   uint	     total_warn_count, old_total_warn_count;
@@ -632,6 +633,7 @@ class THD :public ilink {
     net.last_errno= 0;
     net.report_error= 0;
   }
+  void add_possible_loop(Item *);
 };
 
 /*

sql/sql_parse.cc

@@ -2862,7 +2862,8 @@ mysql_init_query(THD *thd)
   lex->select_lex.init_query();
   lex->value_list.empty();
   lex->param_list.empty();
-  lex->unit.global_parameters= lex->unit.slave= lex->current_select= &lex->select_lex;
+  lex->unit.global_parameters= lex->unit.slave= lex->current_select= 
+    &lex->select_lex;
   lex->select_lex.master= &lex->unit;
   lex->select_lex.prev= &lex->unit.slave;
   lex->olap=lex->describe=0;
@@ -2875,6 +2876,7 @@ mysql_init_query(THD *thd)
   thd->sent_row_count= thd->examined_row_count= 0;
   thd->fatal_error= thd->rand_used=0;
   thd->safe_to_cache_query= 1;
+  thd->possible_loops= 0;
   DBUG_VOID_RETURN;
 }
 

sql/sql_select.cc

@@ -1087,6 +1087,23 @@ mysql_select(THD *thd, TABLE_LIST *tables, List<Item> &fields, COND *conds,
     {
       DBUG_RETURN(-1);
     }
+    if (thd->possible_loops)
+    {
+      Item *item;
+      while(thd->possible_loops->elements)
+      {
+	item= thd->possible_loops->pop();
+    	if (item->check_loop(thd->check_loops_counter++))
+	{
+	  delete thd->possible_loops;
+	  thd->possible_loops= 0;
+	  my_message(ER_CYCLIC_REFERENCE, ER(ER_CYCLIC_REFERENCE), MYF(0));
+	  return 1;
+	}
+      }
+      delete thd->possible_loops;
+      thd->possible_loops= 0;
+    }
   }
 
   switch (join->optimize())