Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN

The problem is that the internal variable used to specify a
transaction with consistent read was being used outside the
processing context of a START TRANSACTION WITH CONSISTENT
SNAPSHOT statement. The practical consequence was that a
consistent snapshot specification could leak to unrelated
transactions on the same session.

The solution is to ensure a consistent snapshot clause is
only relied upon for the START TRANSACTION statement.

This is already fixed in a similar way on 6.0.

mysql-test/r/consistent_snapshot.result:
  Add test case result for Bug#44664
mysql-test/t/consistent_snapshot.test:
  Add test case for Bug#44664
sql/sql_parse.cc:
  The WITH CONSISTENT SNAPSHOT clause is only valid for the
  START TRANSACTION statement.

1 files changed, 19 insertions, 0 deletions

diff --git a/mysql-test/r/consistent_snapshot.result b/mysql-test/r/consistent_snapshot.result
index 694c996a58e..3a0227b1a1a 100644
--- a/mysql-test/r/consistent_snapshot.result
+++ b/mysql-test/r/consistent_snapshot.result
@@ -1,6 +1,9 @@
 DROP TABLE IF EXISTS t1;
 # Establish connection con1 (user=root)
 # Establish connection con2 (user=root)
+### Test 1:
+### - While a consistent snapshot transaction is executed,
+###   no external inserts should be visible to the transaction.
 # Switch to connection con1
 CREATE TABLE t1 (a INT) ENGINE=innodb;
 START TRANSACTION WITH CONSISTENT SNAPSHOT;
@@ -10,6 +13,9 @@ INSERT INTO t1 VALUES(1);
 SELECT * FROM t1;
 a
 COMMIT;
+### Test 2:
+### - For any non-consistent snapshot transaction, external
+###   committed inserts should be visible to the transaction.
 DELETE FROM t1;
 START TRANSACTION;
 # Switch to connection con2
@@ -19,5 +25,18 @@ SELECT * FROM t1;
 a
 1
 COMMIT;
+### Test 3:
+### - Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN
+###   Chaining a transaction does not retain consistency level.
+START TRANSACTION WITH CONSISTENT SNAPSHOT;
+DELETE FROM t1;
+COMMIT WORK AND CHAIN;
+# Switch to connection con2
+INSERT INTO t1 VALUES(1);
+# Switch to connection con1
+SELECT * FROM t1;
+a
+1
+COMMIT;
 # Switch to connection default + close connections con1 and con2
 DROP TABLE t1;