MDEV-40480 LOAD DATA leaves a stale STORED generated column after a B…

mysql-test/suite/gcol/r/gcol_bugfixes.result

@@ -782,3 +782,21 @@ a	c1
 Warnings:
 Warning	1292	Incorrect datetime value: '0'
 DROP TABLE t1;
+#
+# MDEV-40480 LOAD DATA leaves a stale STORED generated column after a
+#            BEFORE INSERT trigger changes its base column
+#
+create table t (
+id   int primary key,
+v    int not null,
+g    int generated always as (v * 2) stored,
+note varchar(20)
+) engine=innodb;
+create trigger t_bi before insert on t for each row set new.v = 20;
+select 2, 12, 'new' into outfile 'load_40480';
+load data infile 'load_40480' into table t (id, v, note);
+# The trigger sets v=20, so the STORED column g must be v*2 = 40, not 24.
+select * from t;
+id	v	g	note
+2	20	40	new
+drop table t;

mysql-test/suite/gcol/t/gcol_bugfixes.test

@@ -753,3 +753,28 @@ UPDATE t1 SET a=2;
 UPDATE t1 SET c1=1;
 SELECT * FROM t1;
 DROP TABLE t1;
+
+
+--echo #
+--echo # MDEV-40480 LOAD DATA leaves a stale STORED generated column after a
+--echo #            BEFORE INSERT trigger changes its base column
+--echo #
+
+create table t (
+  id   int primary key,
+  v    int not null,
+  g    int generated always as (v * 2) stored,
+  note varchar(20)
+) engine=innodb;
+
+create trigger t_bi before insert on t for each row set new.v = 20;
+
+select 2, 12, 'new' into outfile 'load_40480';
+load data infile 'load_40480' into table t (id, v, note);
+
+--echo # The trigger sets v=20, so the STORED column g must be v*2 = 40, not 24.
+select * from t;
+
+drop table t;
+--let $datadir= `select @@datadir`
+--remove_file $datadir/test/load_40480

sql/sql_base.cc

@@ -9372,17 +9372,9 @@ fill_record_n_invoke_before_triggers(THD *thd, TABLE *table,
       Re-calculate virtual fields to cater for cases when base columns are
       updated by the triggers.
     */
-    if (table->vfield && fields.elements)
-    {
-      Item *fld= (Item_field*) fields.head();
-      Item_field *item_field= fld->field_for_view_update();
-      if (item_field)
-      {
-        DBUG_ASSERT(table == item_field->field->table);
-        result|= table->update_virtual_fields(table->file,
-                                              VCOL_UPDATE_FOR_WRITE);
-      }
-    }
+    if (table->vfield)
+      result|= table->update_virtual_fields(table->file,
+                                            VCOL_UPDATE_FOR_WRITE);
   }
   return result;
 }