Bug#28763: Selecting geometry fields in UNION caused server crash.

This bug was introduced by the fix for the bug#27300. In this fix a section
of code was added to the Item::tmp_table_field_from_field_type method.
This section intended to create Field_geom fields for the Item_geometry_func
class and its descendants. In order to get the geometry type of the current
item it casted "this" to the Item_geometry_func* type. But the
Item::tmp_table_field_from_field_type method is also used for creation of
fields for UNION and in this case this method is called for an object of the
Item_type_holder class and the cast to the Item_geometry_func* type causes 
a server crash.

Now the Item::tmp_table_field_from_field_type method correctly works when it's
called for both the Item_type_holder and the Item_geometry_func classes.
The new geometry_type variable is added to the Item_type_holder class.
The new method called get_geometry_type is added to the Item_field
and the Field classes. It returns geometry type from the field for the
Item_field and the Field_geom classes and fails an assert for other Field
descendants.


sql/field.h:
  Bug#28763: Selecting geometry fields in UNION caused server crash.
  The new method called get_geometry_type is added to the Field class.
  It returns geometry type of the field for the Field_geom class
  and fails an assert for other Field descendants.
sql/item.cc:
  Bug#28763: Selecting geometry fields in UNION caused server crash.
  Now the Item::tmp_table_field_from_field_type method correctly works when it's
  called for both the Item_type_holder and the Item_geometry_func classes.
mysql-test/r/gis.result:
  Added a test case for the bug#28763: Selecting geometry fields in UNION caused server crash.
mysql-test/t/gis.test:
  Added a test case for the bug#28763: Selecting geometry fields in UNION caused server crash.
sql/item.h:
  Bug#28763: Selecting geometry fields in UNION caused server crash.
  The new method called get_geometry_type is added to the Item_field class.
  It returns geometry type from the field.
  The new geometry_type variable is added to the Item_type_holder class.

1 files changed, 21 insertions, 0 deletions

diff --git a/mysql-test/r/gis.result b/mysql-test/r/gis.result
index 73e5b054f80..d1f292cda0c 100644
--- a/mysql-test/r/gis.result
+++ b/mysql-test/r/gis.result
@@ -864,4 +864,25 @@ SELECT Overlaps(@horiz1, @point2) FROM DUAL;
 Overlaps(@horiz1, @point2)
 0
 DROP TABLE t1;
+create table t1(f1 geometry, f2 point, f3 linestring);
+select f1 from t1 union select f1 from t1;
+f1
+insert into t1 (f2,f3) values (GeomFromText('POINT(1 1)'),
+GeomFromText('LINESTRING(0 0,1 1,2 2)'));
+select AsText(f2),AsText(f3) from t1;
+AsText(f2)	AsText(f3)
+POINT(1 1)	LINESTRING(0 0,1 1,2 2)
+select AsText(a) from (select f2 as a from t1 union select f3 from t1) t;
+AsText(a)
+POINT(1 1)
+LINESTRING(0 0,1 1,2 2)
+create table t2 as select f2 as a from t1 union select f3 from t1;
+desc t2;
+Field	Type	Null	Key	Default	Extra
+a	point	YES		NULL	
+select AsText(a) from t2;
+AsText(a)
+POINT(1 1)
+LINESTRING(0 0,1 1,2 2)
+drop table t1, t2;
 End of 5.0 tests