MDEV-9690 concurrent queries with virtual columns crash in temporal code

Item_func_le included Arg_comparator. Arg_comparator remembered
the current_thd during fix_fields and used that value during
execution to allocate Item_cache in get_datetime_value().
But for vcols fix_fields and val_int can happen in different threads.

Same bug for Item_func_in using in_datetime or cmp_item_datetime,
both also remembered current_thd at fix_fields() to use it later
for get_datetime_value().

As a fix, these objects no longer remember the current_thd,
and get_datetime_value() uses current_thd at run time. This
should not increase the number of current_thd calls much, as
Item_cache is created only once anyway.

2 files changed, 61 insertions, 0 deletions

diff --git a/mysql-test/suite/vcol/r/wrong_arena.result b/mysql-test/suite/vcol/r/wrong_arena.result
new file mode 100644
index 00000000000..d542c82458e
--- /dev/null
+++ b/mysql-test/suite/vcol/r/wrong_arena.result
@@ -0,0 +1,39 @@
+create table t1 (a datetime,
+# get_datetime_value
+b int as (a > 1),                             # Arg_comparator
+c int as (a in (1,2,3)),                      # in_datetime
+d int as ((a,a) in ((1,1),(2,1),(NULL,1)))    # cmp_item_datetime
+);
+Warnings:
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '2'
+Warning	1292	Incorrect datetime value: '3'
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` datetime DEFAULT NULL,
+  `b` int(11) AS (a > 1) VIRTUAL,
+  `c` int(11) AS (a in (1,2,3)) VIRTUAL,
+  `d` int(11) AS ((a,a) in ((1,1),(2,1),(NULL,1))) VIRTUAL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+Warnings:
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '2'
+Warning	1292	Incorrect datetime value: '3'
+insert t1 (a) values ('2010-10-10 10:10:10');
+select * from t1;
+a	b	c	d
+2010-10-10 10:10:10	1	0	0
+Warnings:
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '2'
+Warning	1292	Incorrect datetime value: '1'
+select * from t1;
+a	b	c	d
+2010-10-10 10:10:10	1	0	0
+Warnings:
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '2'
+Warning	1292	Incorrect datetime value: '1'
+drop table t1;
diff --git a/mysql-test/suite/vcol/t/wrong_arena.test b/mysql-test/suite/vcol/t/wrong_arena.test
new file mode 100644
index 00000000000..8bf06bdb9bd
--- /dev/null
+++ b/mysql-test/suite/vcol/t/wrong_arena.test
@@ -0,0 +1,22 @@
+#
+# This tests various issues when vcol items allocate memory (e.g. more items)
+# not in the TABLE::expr_arena.
+#
+
+#
+# MDEV-9690 concurrent queries with virtual columns crash in temporal code
+#
+create table t1 (a datetime,
+  # get_datetime_value
+  b int as (a > 1),                             # Arg_comparator
+  c int as (a in (1,2,3)),                      # in_datetime
+  d int as ((a,a) in ((1,1),(2,1),(NULL,1)))    # cmp_item_datetime
+);
+show create table t1;
+connect con1, localhost, root;
+insert t1 (a) values ('2010-10-10 10:10:10');
+select * from t1;
+disconnect con1;
+connection default;
+select * from t1;
+drop table t1;