MDEV-8675 Different results of GIS functions on NULL vs NOT NULL columns

mysql-test/r/gis.result

@@ -1816,3 +1816,15 @@ disjoint
 select ST_IsRing(NULL);
 ST_IsRing(NULL)
 -1
+#
+# MDEV-8675 Different results of GIS functions on NULL vs NOT NULL columns
+#
+CREATE TABLE t1 (g1 GEOMETRY NOT NULL,g2 GEOMETRY NULL);
+CREATE TABLE t2 AS SELECT WITHIN(g1,g1) as w1,WITHIN(g2,g2) AS w2 FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `w1` int(1) DEFAULT NULL,
+  `w2` int(1) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1,t2;

mysql-test/t/gis.test

@@ -1518,3 +1518,10 @@ select ST_Relate(ST_PointFromText('POINT(0 0)'),ST_PointFromText('POINT(0 0)'),'
 
 select ST_IsRing(NULL);
 
+--echo #
+--echo # MDEV-8675 Different results of GIS functions on NULL vs NOT NULL columns
+--echo #
+CREATE TABLE t1 (g1 GEOMETRY NOT NULL,g2 GEOMETRY NULL);
+CREATE TABLE t2 AS SELECT WITHIN(g1,g1) as w1,WITHIN(g2,g2) AS w2 FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t1,t2;

sql/item_geofunc.h

@@ -287,7 +287,9 @@ protected:
 public:
   Item_func_spatial_rel(THD *thd, Item *a, Item *b, enum Functype sp_rel):
     Item_bool_func2(thd, a, b), spatial_rel(sp_rel)
-  { }
+  {
+    maybe_null= true;
+  }
   enum Functype functype() const { return spatial_rel; }
   enum Functype rev_functype() const { return spatial_rel; }
   bool is_null() { (void) val_int(); return null_value; }