From 8b25c0e4dc6cb18de7ce4be25eb49c44eeab35cf Mon Sep 17 00:00:00 2001
From: Georgi Kodinov <Georgi.Kodinov@Oracle.com>
Date: Fri, 13 Aug 2010 16:05:46 +0300
Subject: [PATCH] Bug #55565: debug assertion when ordering by expressions with
 user variable assignments

The assert() that is firing is checking if expressions that can't be
null return a NULL when evaluated.
MAKEDATE() function can return NULL if the second argument is
less then or equal to 0. Thus its nullability depends not only on
the nullability of its arguments but also on their values.
Fixed by (overoptimistically) setting MAKEDATE() to be nullable
despite the nullability of its arguments.
Test added.
Had to update one test result to reflect the metadata change.
---
 mysql-test/r/func_sapdb.result |  2 +-
 mysql-test/r/func_time.result  |  8 ++++++++
 mysql-test/t/func_time.test    | 11 +++++++++++
 sql/item_timefunc.h            |  2 ++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/func_sapdb.result b/mysql-test/r/func_sapdb.result
index bbc5390895b..87b88692a34 100644
--- a/mysql-test/r/func_sapdb.result
+++ b/mysql-test/r/func_sapdb.result
@@ -194,7 +194,7 @@ date("1997-12-31 23:59:59.000001") as f8,
 time("1997-12-31 23:59:59.000001") as f9;
 describe t1;
 Field	Type	Null	Key	Default	Extra
-f1	date	NO		0000-00-00	
+f1	date	YES		NULL	
 f2	datetime	YES		NULL	
 f3	time	YES		NULL	
 f4	time	YES		NULL	
diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index 93317020c5b..4ff4cfa586b 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -1335,4 +1335,12 @@ date_sub("0069-01-01 00:00:01",INTERVAL 2 SECOND)
 select date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND);
 date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND)
 0168-12-31 23:59:59
+CREATE TABLE t1(a DOUBLE NOT NULL);
+INSERT INTO t1 VALUES (0),(9.216e-096);
+# should not crash
+SELECT 1 FROM t1 ORDER BY @x:=makedate(a,a);
+1
+1
+1
+DROP TABLE t1;
 End of 5.1 tests
diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index b9da946a55f..e764906c374 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -838,4 +838,15 @@ select date_sub("0069-01-01 00:00:01",INTERVAL 2 SECOND);
 select date_sub("0169-01-01 00:00:01",INTERVAL 2 SECOND);
 
 
+#
+# Bug #55565: debug assertion when ordering by expressions with user
+# variable assignments
+#
+
+CREATE TABLE t1(a DOUBLE NOT NULL);
+INSERT INTO t1 VALUES (0),(9.216e-096);
+--echo # should not crash
+SELECT 1 FROM t1 ORDER BY @x:=makedate(a,a);
+DROP TABLE t1;
+
 --echo End of 5.1 tests
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index a7a64090f6c..11eed70f399 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -881,6 +881,8 @@ public:
   { 
     decimals=0;
     max_length=MAX_DATE_WIDTH*MY_CHARSET_BIN_MB_MAXLEN;
+    /* It returns NULL when the second argument is less or equal to 0 */
+    maybe_null= 1;
   }
   longlong val_int();
 };