BUG#26117 "index_merge sort-union over partitioned table crashes"

Before the fix: 
  ha_partition objects had ha_partition::m_part_info==NULL and that caused
  crash
After: 
- The new ha_partition::clone() function makes the clones use parent's
  m_part_info value.
- The parent ha_partition object remains responsible for deallocation of
  m_part_info.


mysql-test/r/partition_innodb.result:
  BUG#26117 "index_merge sort-union over partitioned table crashes"
   - Testcase
mysql-test/t/partition_innodb.test:
  BUG#26117 "index_merge sort-union over partitioned table crashes"
   - Testcase

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/ha_partition.h b/sql/ha_partition.h
index 4fdf325fa06..1069dd058d5 100644
--- a/sql/ha_partition.h
+++ b/sql/ha_partition.h
@@ -132,7 +132,13 @@ private:
   THR_LOCK_DATA lock;                   /* MySQL lock */
   PARTITION_SHARE *share;               /* Shared lock info */
 
+  /* 
+    TRUE <=> this object was created with ha_partition::clone and doesn't
+    "own" the m_part_info structure.
+  */
+  bool is_clone;
 public:
+  handler *clone(MEM_ROOT *mem_root);
   virtual void set_part_info(partition_info *part_info)
   {
      m_part_info= part_info;