MDEV-21555 Assertion secondary index is out of sync on delete from versioned table

Delete-marked record is on the secondary index and the clustered index
already purged the corresponding record. We cannot detect if such
record is historical and we should not: the algorithm of
row_ins_check_foreign_constraint() skips such record anyway.

mysql-test/suite/versioning/r/foreign.result

@@ -443,3 +443,16 @@ pk	f1	f2	left(f3, 4)	check_row_ts(row_start, row_end)
 1	8	8	SHOR	HISTORICAL ROW
 2	8	8	LONG	HISTORICAL ROW
 drop table t1;
+#
+# MDEV-21555 Assertion secondary index is out of sync on delete from versioned table
+#
+create table t1 (a int, b int as (a + 1) virtual, key(a)) engine=innodb with system versioning;
+set foreign_key_checks= off;
+insert into t1 (a) values (1), (2);
+alter table t1 add foreign key (b) references t1 (a), algorithm=copy;
+update t1 set a= null where a = 1;
+delete from t1 where a is null;
+set foreign_key_checks= on;
+delete history from t1;
+delete from t1;
+drop table t1;

mysql-test/suite/versioning/t/foreign.test

@@ -476,4 +476,22 @@ select pk, f1, f2, left(f3, 4), check_row_ts(row_start, row_end) from t1 for sys
 # cleanup
 drop table t1;
 
+--echo #
+--echo # MDEV-21555 Assertion secondary index is out of sync on delete from versioned table
+--echo #
+create table t1 (a int, b int as (a + 1) virtual, key(a)) engine=innodb with system versioning;
+
+set foreign_key_checks= off;
+insert into t1 (a) values (1), (2);
+alter table t1 add foreign key (b) references t1 (a), algorithm=copy;
+update t1 set a= null where a = 1;
+delete from t1 where a is null;
+set foreign_key_checks= on;
+
+delete history from t1;
+delete from t1;
+
+# cleanup
+drop table t1;
+
 --source suite/versioning/common_finish.inc

storage/innobase/row/row0ins.cc

@@ -1666,23 +1666,6 @@ row_ins_check_foreign_constraint(
 		cmp = cmp_dtuple_rec(entry, rec, offsets);
 
 		if (cmp == 0) {
-			if (check_table->versioned()) {
-				bool history_row = false;
-
-				if (check_index->is_primary()) {
-					history_row = check_index->
-						vers_history_row(rec, offsets);
-				} else if (check_index->
-					vers_history_row(rec, history_row))
-				{
-					break;
-				}
-
-				if (history_row) {
-					continue;
-				}
-			}
-
 			if (rec_get_deleted_flag(rec,
 						 rec_offs_comp(offsets))) {
 				/* In delete-marked records, DB_TRX_ID must
@@ -1704,6 +1687,23 @@ row_ins_check_foreign_constraint(
 					goto end_scan;
 				}
 			} else {
+				if (check_table->versioned()) {
+					bool history_row = false;
+
+					if (check_index->is_primary()) {
+						history_row = check_index->
+							vers_history_row(rec,
+									 offsets);
+					} else if (check_index->
+						vers_history_row(rec,
+								 history_row)) {
+						break;
+					}
+
+					if (history_row) {
+						continue;
+					}
+				}
 				/* Found a matching record. Lock only
 				a record because we can allow inserts
 				into gaps */