Manual merge, fix for bug #7672

mysql-test/r/select.result:
  Manual merge
mysql-test/t/select.test:
  Manual merge
sql/item.cc:
  Manual merge
sql/sql_lex.cc:
  Manual merge
sql/sql_lex.h:
  Manual merge
sql/sql_select.cc:
  Manual merge

mysql-test/r/select.result

@@ -2617,3 +2617,13 @@ select found_rows();
 found_rows()
 1
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT);
+(SELECT a, b AS c FROM t1) ORDER BY c+1;
+a	c
+(SELECT a, b AS c FROM t1) ORDER BY b+1;
+a	c
+SELECT a, b AS c FROM t1 ORDER BY c+1;
+a	c
+SELECT a, b AS c FROM t1 ORDER BY b+1;
+a	c
+drop table t1;

mysql-test/t/select.test

@@ -2052,6 +2052,7 @@ AND FK_firma_id = 2;
 
 drop table t1;
 
+#
 #
 # Test for Bug#8009, SELECT failed on bigint unsigned when using HEX
 #
@@ -2165,3 +2166,11 @@ select found_rows();
 DROP TABLE t1;
 
 # End of 4.1 tests
+# Bug 7672 Unknown column error in order clause
+#
+CREATE TABLE t1 (a INT, b INT);
+(SELECT a, b AS c FROM t1) ORDER BY c+1;
+(SELECT a, b AS c FROM t1) ORDER BY b+1;
+SELECT a, b AS c FROM t1 ORDER BY c+1;
+SELECT a, b AS c FROM t1 ORDER BY b+1;
+drop table t1;

sql/item.cc

@@ -1760,6 +1760,16 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     if ((tmp= find_field_in_tables(thd, this, tables, &where, 0)) ==
 	not_found_field)
     {
+      if (thd->lex.select_lex.is_item_list_lookup)
+      {
+        Item** res= find_item_in_list(this, thd->lex.select_lex.item_list);
+        if (res && *res && (*res)->type() == Item::FIELD_ITEM)
+        {
+          set_field((*((Item_field**)res))->field);
+          return 0;
+        }
+      }
+
       /*
 	We can't find table field in table list of current select,
 	consequently we have to find it in outer subselect(s).

sql/sql_lex.cc

@@ -160,6 +160,7 @@ void lex_start(THD *thd, uchar *buf,uint length)
   lex->duplicates= DUP_ERROR;
   lex->ignore= 0;
   lex->proc_list.first= 0;
+  lex->select_lex.is_item_list_lookup= 0;
 }
 
 void lex_end(LEX *lex)

sql/sql_lex.h

@@ -426,6 +426,7 @@ public:
   List<Item>          item_list; /* list of fields & expressions */
   List<String>        interval_list, use_index, *use_index_ptr,
 		      ignore_index, *ignore_index_ptr;
+  bool	              is_item_list_lookup;
   /* 
     Usualy it is pointer to ftfunc_list_alloc, but in union used to create fake
     select_lex for calling mysql_select under results of union