fixed proccesing global LIMIT in last SELECT of UNION

mysql-test/r/subselect.result

@@ -1046,8 +1046,9 @@ t1	CREATE TABLE `t1` (
 ) TYPE=MyISAM CHARSET=latin1
 drop table t1;
 CREATE TABLE t1 SELECT (SELECT 1 as a UNION SELECT 1+1 limit 1,1) as a;
-Warnings:
-Warning	1262	Data truncated, NULL supplied to NOT NULL column 'a' at row 1
+select * from t1;
+a
+2
 SHOW CREATE TABLE t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (

mysql-test/r/union.result

@@ -409,7 +409,7 @@ found_rows()
 SELECT SQL_CALC_FOUND_ROWS * FROM t1 UNION SELECT * FROM t2 LIMIT 2,2;
 a
 3
-5
+4
 select found_rows();
 found_rows()
 6
@@ -423,7 +423,7 @@ found_rows()
 5
 SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY a desc LIMIT 1;
 a
-3
+5
 (SELECT * FROM t1 ORDER by a) UNION ALL (SELECT * FROM t2 ORDER BY a) ORDER BY A desc LIMIT 4;
 a
 5

mysql-test/t/subselect.test

@@ -606,6 +606,7 @@ CREATE TABLE t1 SELECT * FROM (SELECT 1 as a,(SELECT a+0)) a;
 SHOW CREATE TABLE t1;
 drop table t1;
 CREATE TABLE t1 SELECT (SELECT 1 as a UNION SELECT 1+1 limit 1,1) as a;
+select * from t1;
 SHOW CREATE TABLE t1;
 drop table t1;
 

sql/sql_parse.cc

@@ -1723,6 +1723,10 @@ mysql_execute_command(THD *thd)
       break;					// Error message is given
     }
 
+    /* 
+       In case of single SELECT unit->global_parameters points on first SELECT
+       TODO: move counters to SELECT_LEX
+    */
     unit->offset_limit_cnt= (ha_rows) unit->global_parameters->offset_limit;
     unit->select_limit_cnt= (ha_rows) (unit->global_parameters->select_limit+
       unit->global_parameters->offset_limit);

sql/sql_union.cc

@@ -261,9 +261,24 @@ int st_select_lex_unit::exec()
       if (optimized)
 	res= sl->join->reinit();
       else
+      {
+	if (sl != global_parameters)
 	{
 	  offset_limit_cnt= sl->offset_limit;
 	  select_limit_cnt= sl->select_limit+sl->offset_limit;
+	}
+	else
+	{
+	  offset_limit_cnt= 0;
+	  /*
+	    We can't use LIMIT at this stage if we are using ORDER BY for the
+	    whole query
+	  */
+	  if (sl->order_list.first)
+	    select_limit_cnt= HA_POS_ERROR;
+	  else
+	    select_limit_cnt= sl->select_limit+sl->offset_limit;
+	}
 	if (select_limit_cnt < sl->select_limit)
 	  select_limit_cnt= HA_POS_ERROR;		// no limit
 
@@ -352,14 +367,11 @@ int st_select_lex_unit::exec()
     {
       ulong options= thd->options;
       thd->lex.current_select= fake_select_lex;
-      if (select_cursor->braces)
-      {
       offset_limit_cnt= global_parameters->offset_limit;
       select_limit_cnt= global_parameters->select_limit +
 	global_parameters->offset_limit;
       if (select_limit_cnt < global_parameters->select_limit)
 	select_limit_cnt= HA_POS_ERROR;		// no limit
-      }
       if (select_limit_cnt == HA_POS_ERROR)
 	options&= ~OPTION_FOUND_ROWS;
       else if (found_rows_for_union && !describe)