From 979f27ee4ab978d6f634f444b8e377cf45dc7a59 Mon Sep 17 00:00:00 2001
From: "bell@sanja.is.com.ua" <>
Date: Thu, 14 Nov 2002 09:43:24 +0200
Subject: [PATCH] fixed bug in cyclic reference refinition

---
 mysql-test/r/subselect.result |  2 ++
 mysql-test/t/subselect.test   |  2 ++
 sql/item.cc                   |  6 +-----
 sql/sql_class.cc              |  9 +++++++++
 sql/sql_class.h               |  2 ++
 sql/sql_parse.cc              |  4 +++-
 sql/sql_select.cc             | 17 +++++++++++++++++
 7 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index 1b799a6cb63..d1a3056d8e9 100644
--- a/mysql-test/r/subselect.result
+++ b/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);
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index f690a823f85..63f689d2608 100644
--- a/mysql-test/t/subselect.test
+++ b/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);
diff --git a/sql/item.cc b/sql/item.cc
index f317759553b..48ec11d02c2 100644
--- a/sql/item.cc
+++ b/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)
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index f33d0f2ca28..e6acab6a244 100644
--- a/sql/sql_class.cc
+++ b/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
 *****************************************************************************/
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 6f6547a358c..a619e8e3aff 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -482,6 +482,7 @@ public:
   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 @@ public:
     net.last_errno= 0;
     net.report_error= 0;
   }
+  void add_possible_loop(Item *);
 };
 
 /*
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 1586469de42..8df74f332eb 100644
--- a/sql/sql_parse.cc
+++ b/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;
 }
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index dd84b2a46c8..b3838628d35 100644
--- a/sql/sql_select.cc
+++ b/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())