BUG#19067: Alter table add partition for subpartitioned table crashes

Changed variable name for improved clarity and debugging possibilities
Fixed bug in not assigning subpart_type


mysql-test/t/partition.test:
  Added new test case
sql/partition_info.cc:
  Changed variable name for improved clarity and debugging possibilities
  Fixed bug in not assigning subpart_type
sql/sql_partition.cc:
  Changed variable name for improved clarity and debugging possibilities
  Fixed bug in not assigning subpart_type

mysql-test/t/partition.test

@@ -1009,4 +1009,15 @@ select auto_increment from information_schema.tables where table_name='t1';
 select * from t1;
 drop table t1;
 
+#
+# BUG 19067 ALTER TABLE .. ADD PARTITION for subpartitioned table crashes
+#
+create table t1 (a int)
+partition by range (a)
+subpartition by key (a)
+(partition p0 values less than (1));
+alter table t1 add partition (partition p1 values less than (2));
+alter table t1 reorganize partition p1 into (partition p1 values less than (3));
+drop table t1;
+
 --echo End of 5.1 tests

sql/partition_info.cc

@@ -714,18 +714,18 @@ bool partition_info::check_partition_info(handlerton **eng_type,
         List_iterator<partition_element> sub_it(part_elem->subpartitions);
         do
         {
-          part_elem= sub_it++;
-          if (check_table_name(part_elem->partition_name,
-                               strlen(part_elem->partition_name)))
+          partition_element *sub_elem= sub_it++;
+          if (check_table_name(sub_elem->partition_name,
+                               strlen(sub_elem->partition_name)))
           {
             my_error(ER_WRONG_PARTITION_NAME, MYF(0));
             goto end;
           }
-          if (part_elem->engine_type == NULL)
-            part_elem->engine_type= default_engine_type;
+          if (sub_elem->engine_type == NULL)
+            sub_elem->engine_type= default_engine_type;
           DBUG_PRINT("info", ("engine = %u",
-                     ha_legacy_type(part_elem->engine_type)));
-          engine_array[part_count++]= part_elem->engine_type;
+                     ha_legacy_type(sub_elem->engine_type)));
+          engine_array[part_count++]= sub_elem->engine_type;
         } while (++j < no_subparts);
       }
     } while (++i < no_parts);

sql/sql_partition.cc

@@ -3949,6 +3949,7 @@ uint prep_alter_part_table(THD *thd, TABLE *table, ALTER_INFO *alter_info,
         DBUG_RETURN(TRUE);
       }
       alt_part_info->part_type= tab_part_info->part_type;
+      alt_part_info->subpart_type= tab_part_info->subpart_type;
       if (alt_part_info->set_up_defaults_for_partitioning(table->file,
                                                           ULL(0), 
                                                           tab_part_info->no_parts))