MDEV-28566 Assertion `!expr->is_fixed()' failed in bool virtual_column_info::fix_session_expr(THD*)

The problem was that table->vcol_cleanup_expr() was not called in case
of error in open_table().

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

@@ -745,3 +745,41 @@ SELECT id, ts, vc INTO OUTFILE 'load_t1' FROM t1;
 LOAD DATA INFILE 'load_t1' REPLACE INTO TABLE t1 (id, ts, vc);
 INSERT IGNORE INTO t1 (id) VALUES (2);
 DROP TABLE t1;
+#
+# MDEV-28566 Assertion `!expr->is_fixed()' failed in bool
+#            Virtual_column_info::fix_session_expr(THD*)
+#
+CREATE TABLE t1 (c1 CHAR(1));
+FLUSH TABLES WITH READ LOCK;
+UPDATE t1 SET c1=1;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+unlock tables;
+SELECT * FROM t1;
+c1
+DROP TABLE t1;
+CREATE TABLE t1 (c1 CHAR AS (CONCAT (0,DAYNAME (0))));
+FLUSH TABLES WITH READ LOCK;
+UPDATE t1 SET c1=1;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+unlock tables;
+UPDATE t1 SET c1=1;
+SELECT * FROM t1;
+c1
+DROP TABLE t1;
+CREATE TABLE t1 (a int primary key, c1 CHAR AS (CONCAT (0,DAYNAME (0))));
+insert into t1 (a) values (1);
+FLUSH TABLES WITH READ LOCK;
+UPDATE t1 SET c1=1;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+UPDATE t1 SET a=2;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+unlock tables;
+UPDATE t1 SET a=2;
+UPDATE t1 SET c1=1;
+ERROR HY000: The value specified for generated column 'c1' in table 't1' has been ignored
+SELECT * FROM t1;
+a	c1
+2	NULL
+Warnings:
+Warning	1292	Incorrect datetime value: '0'
+DROP TABLE t1;

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

@@ -724,3 +724,38 @@ DROP TABLE t1;
 --remove_file $datadir/test/load_t1
 
 
+--echo #
+--echo # MDEV-28566 Assertion `!expr->is_fixed()' failed in bool
+--echo #            Virtual_column_info::fix_session_expr(THD*)
+--echo #
+
+CREATE TABLE t1 (c1 CHAR(1));
+FLUSH TABLES WITH READ LOCK;
+--error ER_CANT_UPDATE_WITH_READLOCK
+UPDATE t1 SET c1=1;
+unlock tables;
+SELECT * FROM t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 (c1 CHAR AS (CONCAT (0,DAYNAME (0))));
+FLUSH TABLES WITH READ LOCK;
+--error ER_CANT_UPDATE_WITH_READLOCK
+UPDATE t1 SET c1=1;
+unlock tables;
+UPDATE t1 SET c1=1;
+SELECT * FROM t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 (a int primary key, c1 CHAR AS (CONCAT (0,DAYNAME (0))));
+insert into t1 (a) values (1);
+FLUSH TABLES WITH READ LOCK;
+--error ER_CANT_UPDATE_WITH_READLOCK
+UPDATE t1 SET c1=1;
+--error ER_CANT_UPDATE_WITH_READLOCK
+UPDATE t1 SET a=2;
+unlock tables;
+UPDATE t1 SET a=2;
+--error ER_WARNING_NON_DEFAULT_VALUE_FOR_GENERATED_COLUMN
+UPDATE t1 SET c1=1;
+SELECT * FROM t1;
+DROP TABLE t1;

sql/sql_base.cc

@@ -2191,6 +2191,7 @@ bool open_table(THD *thd, TABLE_LIST *table_list, Open_table_context *ot_ctx)
       if (thd->has_read_only_protection())
       {
         MYSQL_UNBIND_TABLE(table->file);
+        table->vcol_cleanup_expr(thd);
         tc_release_table(table);
         DBUG_RETURN(TRUE);
       }
@@ -2210,6 +2211,7 @@ bool open_table(THD *thd, TABLE_LIST *table_list, Open_table_context *ot_ctx)
       if (result)
       {
         MYSQL_UNBIND_TABLE(table->file);
+        table->vcol_cleanup_expr(thd);
         tc_release_table(table);
         DBUG_RETURN(TRUE);
       }