MDEV-29169 Using MATCH returns NULL for Virtual Column

Virtual column values are updated in handler in reading commands,
like ha_index_next, etc. This was missing for ha_ft_read.

handler::ha_ft_read: add table->update_virtual_fields() call

mysql-test/suite/innodb_fts/r/fulltext2.result

@@ -278,3 +278,20 @@ ALTER TABLE t1 ADD d INT NULL;
 ALTER TABLE t1 ADD FULLTEXT(b);
 ERROR HY000: Index 'FTS_DOC_ID_INDEX' is of wrong type for an InnoDB FULLTEXT index
 DROP TABLE t1;
+#
+# MDEV-29169 Using MATCH returns NULL for Virtual Column
+#
+CREATE TABLE t (a TEXT DEFAULT NULL,
+b TEXT AS (a),
+c TEXT AS (concat(a, '1')),
+d int AS (111) VIRTUAL,
+FULLTEXT KEY `a` (`a`)
+) ENGINE=InnoDB;
+INSERT INTO t (a) VALUES ('test');
+SELECT * FROM t;
+a	b	c	d
+test	test	test1	111
+SELECT * FROM t WHERE MATCH(a) AGAINST('test');
+a	b	c	d
+test	test	test1	111
+DROP TABLE t;

mysql-test/suite/innodb_fts/t/fulltext2.test

@@ -268,3 +268,19 @@ ALTER TABLE t1 ADD d INT NULL;
 --error ER_INNODB_FT_WRONG_DOCID_INDEX
 ALTER TABLE t1 ADD FULLTEXT(b);
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-29169 Using MATCH returns NULL for Virtual Column
+--echo #
+CREATE TABLE t (a TEXT DEFAULT NULL,
+                b TEXT AS (a),
+                c TEXT AS (concat(a, '1')),
+                d int AS (111) VIRTUAL,
+                FULLTEXT KEY `a` (`a`)
+) ENGINE=InnoDB;
+
+INSERT INTO t (a) VALUES ('test');
+SELECT * FROM t;
+SELECT * FROM t WHERE MATCH(a) AGAINST('test');
+
+DROP TABLE t;

sql/sql_class.h

@@ -6513,8 +6513,13 @@ inline int handler::ha_ft_read(uchar *buf)
 {
   int error= ft_read(buf);
   if (!error)
+  {
     update_rows_read();
 
+    if (table->vfield && buf == table->record[0])
+      table->update_virtual_fields(this, VCOL_UPDATE_FOR_READ);
+  }
+
   table->status=error ? STATUS_NOT_FOUND: 0;
   return error;
 }