Fixed range optimzier bug (Bug #1828)

mysql-test/r/range.result:
  test for range optimzier bug
mysql-test/t/range.test:
  test for range optimzier bug

mysql-test/r/range.result

@@ -290,3 +290,13 @@ t1	range	a,b	a	5	NULL	2	Using where
 SELECT * FROM t1 WHERE a IN(1,2) AND b=5;
 a	b
 DROP TABLE t1;
+CREATE TABLE t1 (a int, b int, c int, INDEX (c,a,b));
+INSERT INTO t1 VALUES (1,0,0),(1,0,0),(1,0,0);
+INSERT INTO t1 VALUES (0,1,0),(0,1,0),(0,1,0);
+SELECT COUNT(*) FROM t1 WHERE (c=0 and a=1) or (c=0 and b=1);
+COUNT(*)
+6
+SELECT COUNT(*) FROM t1 WHERE (c=0 and b=1) or (c=0 and a=1);
+COUNT(*)
+6
+DROP TABLE t1;

mysql-test/t/range.test

@@ -231,9 +231,20 @@ INSERT INTO t1 VALUES
 (21,4),(22,5),(23,5),(24,5),(25,5),(26,5),(30,5),(31,5),(32,5),(33,5),
 (33,5),(33,5),(33,5),(33,5),(34,5),(35,5);
 
+# we expect that optimizer will choose index on A
 EXPLAIN SELECT * FROM t1 WHERE a IN(1,2) AND b=5;
 SELECT * FROM t1 WHERE a IN(1,2) AND b=5;
 
 DROP TABLE t1;
 
-# we expect that optimizer will choose index on A
+#
+# Test error with 
+#
+
+CREATE TABLE t1 (a int, b int, c int, INDEX (c,a,b));
+INSERT INTO t1 VALUES (1,0,0),(1,0,0),(1,0,0);
+INSERT INTO t1 VALUES (0,1,0),(0,1,0),(0,1,0);
+# -- First reports 3; second reports 6
+SELECT COUNT(*) FROM t1 WHERE (c=0 and a=1) or (c=0 and b=1);
+SELECT COUNT(*) FROM t1 WHERE (c=0 and b=1) or (c=0 and a=1);
+DROP TABLE t1;

sql/opt_range.cc

@@ -70,7 +70,7 @@ public:
   {}
   inline bool is_same(SEL_ARG *arg)
   {
-    if (type != arg->type)
+    if (type != arg->type || part != arg->part)
       return 0;
     if (type != KEY_RANGE)
       return 1;