Fixed bug #27848.

In a union without braces, the order by at the end is applied to the 
overall union. It therefore should not interfere with the individual
select parts of the union.

Fixed by changing our parser rules appropriately.

mysql-test/r/union.result

@@ -1389,4 +1389,55 @@ select @var;
 1
 (select 2) union (select 1 into @var);
 ERROR 42000: Result consisted of more than one row
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (10), (20);
+CREATE TABLE t2 (b int);
+INSERT INTO t2 VALUES (10), (50), (50);
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a;
+a	1
+NULL	3
+10	1
+20	1
+50	2
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a DESC;
+a	1
+50	2
+20	1
+10	1
+NULL	3
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a ASC LIMIT 3;
+a	1
+NULL	3
+10	1
+20	1
+SELECT a,1 FROM t1 
+UNION ALL 
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a DESC;
+a	1
+50	2
+20	1
+10	1
+10	1
+NULL	3
+SELECT a,1 FROM t1
+UNION 
+(SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP ORDER BY a);
+ERROR HY000: Incorrect usage of CUBE/ROLLUP and ORDER BY
+SELECT a,1 FROM t1
+UNION ALL
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP ORDER BY a
+UNION
+SELECT 1,1;
+ERROR HY000: Incorrect usage of UNION and ORDER BY
+DROP TABLE t1,t2;
 End of 5.0 tests

mysql-test/t/union.test

@@ -877,4 +877,48 @@ DROP TABLE t1;
 select @var;
 --error 1172
 (select 2) union (select 1 into @var);
+
+#
+# Bug#27848: order-by of union clashes with rollup of select part
+#
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (10), (20);
+CREATE TABLE t2 (b int);
+INSERT INTO t2 VALUES (10), (50), (50);
+
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a;
+
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a DESC;
+
+SELECT a,1 FROM t1 
+UNION
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a ASC LIMIT 3;
+
+SELECT a,1 FROM t1 
+UNION ALL 
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP
+ORDER BY a DESC;
+
+--error ER_WRONG_USAGE
+SELECT a,1 FROM t1
+UNION 
+(SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP ORDER BY a);
+
+--error ER_WRONG_USAGE
+SELECT a,1 FROM t1
+UNION ALL
+SELECT b, COUNT(*) FROM t2 GROUP BY b WITH ROLLUP ORDER BY a
+UNION
+SELECT 1,1;
+
+DROP TABLE t1,t2;
+
 --echo End of 5.0 tests

sql/sql_yacc.yy

@@ -4211,6 +4211,14 @@ select_paren:
               my_parse_error(ER(ER_SYNTAX_ERROR));
               MYSQL_YYABORT;
             }
+            if (sel->linkage == UNION_TYPE &&
+                sel->olap != UNSPECIFIED_OLAP_TYPE &&
+                sel->master_unit()->fake_select_lex)
+            {
+ 	       my_error(ER_WRONG_USAGE, MYF(0),
+                        "CUBE/ROLLUP", "ORDER BY");
+               MYSQL_YYABORT;
+            }
             /* select in braces, can't contain global parameters */
 	    if (sel->master_unit()->fake_select_lex)
               sel->master_unit()->global_parameters=
@@ -6165,7 +6173,8 @@ order_clause:
           SELECT_LEX *sel= lex->current_select;
           SELECT_LEX_UNIT *unit= sel-> master_unit();
 	  if (sel->linkage != GLOBAL_OPTIONS_TYPE &&
-	      sel->olap != UNSPECIFIED_OLAP_TYPE)
+              sel->olap != UNSPECIFIED_OLAP_TYPE &&
+              (sel->linkage != UNION_TYPE || sel->braces))
 	  {
 	    my_error(ER_WRONG_USAGE, MYF(0),
                      "CUBE/ROLLUP", "ORDER BY");