MDEV-18153 Assertion 0' or Assertion btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL

Conversion to a temporal data type resulting into a lower precision
depends on TIME_ROUND_FRACTIONAL. Taking into account this dependency in:
- indexed generated virtual column expressions
- persistent virtual column expressions

A warning is now issued if conversion from the generation expression
to the column data type depends on TIME_ROUND_FRACTIONAL.

The warning will be changed to error in 10.5

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

@@ -549,8 +549,13 @@ a BLOB GENERATED ALWAYS AS ('') VIRTUAL,
 b TIMESTAMP(4) GENERATED ALWAYS AS ('') VIRTUAL,
 KEY (a(183),b)
 );
+Warnings:
+Warning	1901	Function or expression '''' cannot be used in the GENERATED ALWAYS AS clause of `b`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
 INSERT IGNORE INTO t VALUES(), (), ();
 Warnings:
+Warning	1901	Function or expression '''' cannot be used in the GENERATED ALWAYS AS clause of `b`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
 Warning	1265	Data truncated for column 'b' at row 1
 Warning	1265	Data truncated for column 'b' at row 2
 Warning	1265	Data truncated for column 'b' at row 3

mysql-test/suite/vcol/r/vcol_keys_innodb.result

@@ -257,6 +257,11 @@ insert into t1 (col_varchar,col_int,col_datetime,col_time,col_blob,col_bit,col_y
 ('foo',1,'2010-05-08 13:08:12.034783','18:32:14','foo',b'0111110101001001',1992,'f',0.2,'','1994-12-26','2019-01-11 00:00:00'),
 ('bar',6,'1900-01-01 00:00:00','00:00:00','bar',b'10011000001101011000101',1985,'b',0.7,'','2028-04-06','1971-01-01 00:00:00');
 alter table t1 add index(vcol_datetime);
+Warnings:
+Warning	1901	Function or expression '`col_datetime`' cannot be used in the GENERATED ALWAYS AS clause of `vcol_datetime`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+Warning	1901	Function or expression '`col_datetime`' cannot be used in the GENERATED ALWAYS AS clause of `vcol_datetime`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
 drop table t1;
 create table t1 (
 pk int,

mysql-test/suite/vcol/r/vcol_sql_mode.result

@@ -26,6 +26,9 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 CREATE TABLE t1 (a CHAR(5), v TIME AS (a) VIRTUAL, KEY(v));
+Warnings:
+Warning	1901	Function or expression '`a`' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
 DROP TABLE t1;
 CREATE TABLE t1 (c CHAR(8), v BINARY(8) AS (c), KEY(v));
 Warnings:

mysql-test/suite/vcol/r/vcol_sql_mode_datetime.result

@@ -0,0 +1,101 @@
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+#
+SET sql_mode=DEFAULT;
+# OK: same FSP + virtual index
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(4) AS (t) VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(4) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+# OK: lower FSP + no virtual index
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+# NOT OK: lower FSP + virtual index
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS (t) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression '`t`' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS (COALESCE(t)) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression 'coalesce(`t`)' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression ''2001-01-01 10:20:30.1234'' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+# OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS (ROUND(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+t	d	v
+2006-03-01 12:44:34.0496	2029-10-10 21:27:53	2006-03-01 12:44:34.050
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+# OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t DATETIME(4),
+d DATETIME,
+v DATETIME(3) AS (TRUNCATE(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+t	d	v
+2006-03-01 12:44:34.0496	2029-10-10 21:27:53	2006-03-01 12:44:34.049
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+#
+# End of 10.4 tests
+#

mysql-test/suite/vcol/r/vcol_sql_mode_time.result

@@ -0,0 +1,101 @@
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+#
+SET sql_mode=DEFAULT;
+# OK: same FSP + virtual index
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(4) AS (t) VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(4) AS ('10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+# OK: lower FSP + no virtual index
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+# NOT OK: lower FSP + virtual index
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS (t) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression '`t`' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS (COALESCE(t)) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression 'coalesce(`t`)' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression ''2001-01-01 10:20:30.1234'' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+# OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS (ROUND(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('12:44:34.0496','21:27:53');
+SELECT * FROM t1;
+t	d	v
+12:44:34.0496	21:27:53	12:44:34.050
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = CURRENT_TIME;
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+# OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t TIME(4),
+d TIME,
+v TIME(3) AS (TRUNCATE(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('12:44:34.0496','21:27:53');
+SELECT * FROM t1;
+t	d	v
+12:44:34.0496	21:27:53	12:44:34.049
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = CURRENT_TIME;
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+#
+# End of 10.4 tests
+#

mysql-test/suite/vcol/r/vcol_sql_mode_timestamp.result

@@ -0,0 +1,101 @@
+#
+# Start of 10.4 tests
+#
+#
+# MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+#
+SET sql_mode=DEFAULT;
+# OK: same FSP + virtual index
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(4) AS (t) VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(4) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+DROP TABLE t1;
+# OK: lower FSP + no virtual index
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+# NOT OK: lower FSP + virtual index
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS (t) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression '`t`' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS (COALESCE(t)) VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression 'coalesce(`t`)' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+KEY(v,d)
+);
+Warnings:
+Warning	1901	Function or expression ''2001-01-01 10:20:30.1234'' cannot be used in the GENERATED ALWAYS AS clause of `v`
+Warning	1105	Expression depends on the @@sql_mode value TIME_ROUND_FRACTIONAL
+DROP TABLE t1;
+# OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS (ROUND(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+t	d	v
+2006-03-01 12:44:34.0496	2029-10-10 21:27:53	2006-03-01 12:44:34.050
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+# OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+t TIMESTAMP(4),
+d DATETIME,
+v TIMESTAMP(3) AS (TRUNCATE(t,3)) VIRTUAL,
+KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+t	d	v
+2006-03-01 12:44:34.0496	2029-10-10 21:27:53	2006-03-01 12:44:34.049
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+#
+# End of 10.4 tests
+#

mysql-test/suite/vcol/t/vcol_sql_mode_datetime.test

@@ -0,0 +1,112 @@
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+--echo #
+
+SET sql_mode=DEFAULT;
+
+--echo # OK: same FSP + virtual index
+
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(4) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(4) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + no virtual index
+
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+
+
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+
+
+--echo # NOT OK: lower FSP + virtual index
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS (COALESCE(t)) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS (ROUND(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo # OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t DATETIME(4),
+  d DATETIME,
+  v DATETIME(3) AS (TRUNCATE(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo #
+--echo # End of 10.4 tests
+--echo #

mysql-test/suite/vcol/t/vcol_sql_mode_time.test

@@ -0,0 +1,112 @@
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+--echo #
+
+SET sql_mode=DEFAULT;
+
+--echo # OK: same FSP + virtual index
+
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(4) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(4) AS ('10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + no virtual index
+
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+
+
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+
+
+--echo # NOT OK: lower FSP + virtual index
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS (COALESCE(t)) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS (ROUND(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('12:44:34.0496','21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = CURRENT_TIME;
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo # OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t TIME(4),
+  d TIME,
+  v TIME(3) AS (TRUNCATE(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('12:44:34.0496','21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = CURRENT_TIME;
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo #
+--echo # End of 10.4 tests
+--echo #

mysql-test/suite/vcol/t/vcol_sql_mode_timestamp.test

@@ -0,0 +1,112 @@
+--echo #
+--echo # Start of 10.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-18153 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIME_ROUND_FRACTIONAL
+--echo #
+
+SET sql_mode=DEFAULT;
+
+--echo # OK: same FSP + virtual index
+
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(4) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(4) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + no virtual index
+
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS (t) VIRTUAL
+);
+DROP TABLE t1;
+
+
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL
+);
+DROP TABLE t1;
+
+
+--echo # NOT OK: lower FSP + virtual index
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS (t) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS (COALESCE(t)) VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+#--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS ('2001-01-01 10:20:30.1234') VIRTUAL,
+  KEY(v,d)
+);
+DROP TABLE t1;
+
+
+--echo # OK: lower FSP + ROUND + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS (ROUND(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo # OK: lower FSP + TRUNCATE + virtual index
+SET sql_mode=DEFAULT;
+CREATE TABLE t1 (
+  t TIMESTAMP(4),
+  d DATETIME,
+  v TIMESTAMP(3) AS (TRUNCATE(t,3)) VIRTUAL,
+  KEY(v,d)
+);
+INSERT IGNORE INTO t1 (t,d) VALUES ('2006-03-01 12:44:34.0496','2029-10-10 21:27:53');
+SELECT * FROM t1;
+SET SQL_MODE= 'TIME_ROUND_FRACTIONAL';
+UPDATE IGNORE t1 SET d = NOW();
+DROP TABLE t1;
+SET sql_mode=DEFAULT;
+
+
+--echo #
+--echo # End of 10.4 tests
+--echo #

sql/field.cc

@@ -1407,8 +1407,10 @@ bool Field::check_vcol_sql_mode_dependency(THD *thd, vcol_init_mode mode) const
   DBUG_ASSERT(vcol_info);
   if ((flags & PART_KEY_FLAG) != 0 || stored_in_db())
   {
+    Sql_mode_dependency valdep= vcol_info->expr->value_depends_on_sql_mode();
+    sql_mode_t cnvdep= conversion_depends_on_sql_mode(thd, vcol_info->expr);
     Sql_mode_dependency dep=
-        vcol_info->expr->value_depends_on_sql_mode() &
+        (valdep | Sql_mode_dependency(0, cnvdep)) &
         Sql_mode_dependency(~0, ~can_handle_sql_mode_dependency_on_store());
     if (dep)
     {
@@ -5062,6 +5064,14 @@ Field_timestamp::Field_timestamp(uchar *ptr_arg, uint32 len_arg,
 }
 
 
+sql_mode_t
+Field_timestamp::conversion_depends_on_sql_mode(THD *thd, Item *expr) const
+{
+  return expr->datetime_precision(thd) > decimals() ?
+         MODE_TIME_ROUND_FRACTIONAL : 0;
+}
+
+
 int Field_timestamp::save_in_field(Field *to)
 {
   ulong sec_part;
@@ -5823,6 +5833,14 @@ Item *Field_temporal::get_equal_const_item_datetime(THD *thd,
 ** In number context: HHMMSS
 ** Stored as a 3 byte unsigned int
 ****************************************************************************/
+sql_mode_t
+Field_time::conversion_depends_on_sql_mode(THD *thd, Item *expr) const
+{
+  return expr->time_precision(thd) > decimals() ?
+         MODE_TIME_ROUND_FRACTIONAL : 0;
+}
+
+
 int Field_time::store_TIME_with_warning(const Time *t,
                                         const ErrConv *str, int warn)
 {
@@ -6727,6 +6745,15 @@ void Field_datetime::store_TIME(const MYSQL_TIME *ltime)
   int8store(ptr,tmp);
 }
 
+
+sql_mode_t
+Field_datetime::conversion_depends_on_sql_mode(THD *thd, Item *expr) const
+{
+  return expr->datetime_precision(thd) > decimals() ?
+         MODE_TIME_ROUND_FRACTIONAL : 0;
+}
+
+
 bool Field_datetime::send_binary(Protocol *protocol)
 {
   MYSQL_TIME tm;

sql/field.h

@@ -1215,6 +1215,11 @@ public:
   {
     return 0;
   }
+  virtual sql_mode_t conversion_depends_on_sql_mode(THD *thd,
+                                                    Item *expr) const
+  {
+    return (sql_mode_t) 0;
+  }
   virtual sql_mode_t can_handle_sql_mode_dependency_on_store() const
   {
     return 0;
@@ -2827,6 +2832,7 @@ public:
   const Type_handler *type_handler() const { return &type_handler_timestamp; }
   enum ha_base_keytype key_type() const { return HA_KEYTYPE_ULONG_INT; }
   Copy_func *get_copy_func(const Field *from) const;
+  sql_mode_t conversion_depends_on_sql_mode(THD *, Item *) const;
   int  store(const char *to,size_t length,CHARSET_INFO *charset);
   int  store(double nr);
   int  store(longlong nr, bool unsigned_val);
@@ -3185,6 +3191,7 @@ public:
     return real_type() == from->real_type() &&
            decimals() == from->decimals();
   }
+  sql_mode_t conversion_depends_on_sql_mode(THD *, Item *) const;
   int store_time_dec(const MYSQL_TIME *ltime, uint dec);
   int store(const char *to,size_t length,CHARSET_INFO *charset);
   int store(double nr);
@@ -3329,6 +3336,7 @@ public:
     }
   const Type_handler *type_handler() const { return &type_handler_datetime; }
   enum ha_base_keytype key_type() const { return HA_KEYTYPE_ULONGLONG; }
+  sql_mode_t conversion_depends_on_sql_mode(THD *, Item *) const;
   int  store(const char *to, size_t length, CHARSET_INFO *charset);
   int  store(double nr);
   int  store(longlong nr, bool unsigned_val);

sql/sql_mode.cc

@@ -17,7 +17,7 @@
 #include "mariadb.h"
 #include "set_var.h"
 
-void Sql_mode_dependency::push_dependency_warnings(THD *thd)
+void Sql_mode_dependency::push_dependency_warnings(THD *thd) const
 {
   sql_mode_t all= m_hard | m_soft;
   for (uint i= 0; all ; i++, all >>= 1)

sql/sql_mode.h

@@ -155,7 +155,7 @@ public:
     m_soft= 0;
     return *this;
   }
-  void push_dependency_warnings(THD *thd);
+  void push_dependency_warnings(THD *thd) const;
 };