MDEV-32555 wrong result with an index and a partially null-rejecting condition

ref->null_rejecting is a key_part_map. we need to check
the bit corresponding to the particular store_key.
Note that there are no store_key objects for const ref parts.

mysql-test/main/subselect_nulls.result

-drop table if exists x1;
-drop table if exists x2;
 set @tmp_subselect_nulls=@@optimizer_switch;
 set optimizer_switch='semijoin=off';
 create table x1(k int primary key, d1 int, d2 int);
@@ -115,9 +113,44 @@ k	d1	d2
 set optimizer_switch= @tmp_subselect_nulls;
 drop table x1;
 drop table x2;
+#
+# MDEV-7339 Server crashes in Item_func_trig_cond::val_int
+#
 select (select 1, 2) in (select 3, 4);
 (select 1, 2) in (select 3, 4)
 0
 select (select NULL, NULL) in (select 3, 4);
 (select NULL, NULL) in (select 3, 4)
 NULL
+#
+# End of 5.5 tests
+#
+#
+# MDEV-32555 wrong result with an index and a partially null-rejecting condition
+#
+create table t1 (a int primary key);
+insert t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t2 (
+b int not null,
+c int default null,
+d int not null,
+e int not null,
+unique key (d,b,c)
+);
+insert t2 values (1,null,1,1),(1,null,2,2),(1,null,3,3),(1,null,4,4),(2,null,1,2),(3,null,1,3),(4,null,2,2),(4,null,1,4);
+select (
+select sum(t2_.e) from t2 t2_ where t2_.b = a and t2_.c <=> t2.c and t2_.d = 1
+) x from t2 left join t1 on a = b;
+x
+1
+2
+3
+4
+1
+4
+1
+1
+drop table t1, t2;
+#
+# End of 10.10 tests
+#

mysql-test/main/subselect_nulls.test

-# Initialize tables for the test
-
---disable_warnings
-drop table if exists x1;
-drop table if exists x2;
---enable_warnings
-
 set @tmp_subselect_nulls=@@optimizer_switch;
 set optimizer_switch='semijoin=off';
 
@@ -98,8 +91,39 @@ set optimizer_switch= @tmp_subselect_nulls;
 drop table x1;
 drop table x2;
 
-#
-# MDEV-7339 Server crashes in Item_func_trig_cond::val_int
-#
+--echo #
+--echo # MDEV-7339 Server crashes in Item_func_trig_cond::val_int
+--echo #
 select (select 1, 2) in (select 3, 4);
 select (select NULL, NULL) in (select 3, 4);
+
+--echo #
+--echo # End of 5.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-32555 wrong result with an index and a partially null-rejecting condition
+--echo #
+
+create table t1 (a int primary key);
+insert t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9);
+
+create table t2 (
+  b int not null,
+  c int default null,
+  d int not null,
+  e int not null,
+  unique key (d,b,c)
+);
+
+insert t2 values (1,null,1,1),(1,null,2,2),(1,null,3,3),(1,null,4,4),(2,null,1,2),(3,null,1,3),(4,null,2,2),(4,null,1,4);
+
+select (
+  select sum(t2_.e) from t2 t2_ where t2_.b = a and t2_.c <=> t2.c and t2_.d = 1
+) x from t2 left join t1 on a = b;
+
+drop table t1, t2;
+
+--echo #
+--echo # End of 10.10 tests
+--echo #

sql/sql_expression_cache.cc

@@ -151,6 +151,7 @@ void Expression_cache_tmptable::init()
   }
   cache_table->s->keys= 1;
   ref.null_rejecting= 1;
+  ref.const_ref_part_map= 0;
   ref.disable_cache= FALSE;
   ref.has_record= 0;
   ref.use_count= 0;

sql/sql_select.cc

@@ -26078,12 +26078,15 @@ cp_buffer_from_ref(THD *thd, TABLE *table, TABLE_REF *ref)
   enum_check_fields org_count_cuted_fields= thd->count_cuted_fields;
   MY_BITMAP *old_map= dbug_tmp_use_all_columns(table, &table->write_set);
   bool result= 0;
+  key_part_map map= 1;
 
   thd->count_cuted_fields= CHECK_FIELD_IGNORE;
-  for (store_key **copy=ref->key_copy ; *copy ; copy++)
+  for (store_key **copy=ref->key_copy ; *copy ; copy++, map <<= 1)
   {
+    while (map & ref->const_ref_part_map) // skip const ref parts
+      map <<= 1;                          // no store_key objects for them
     if ((*copy)->copy(thd) & 1 ||
-        (ref->null_rejecting && (*copy)->null_key))
+        ((ref->null_rejecting & map) && (*copy)->null_key))
     {
       result= 1;
       break;