From 1285ecd4688295c0aae28b314ef8a4c9ae3b6c14 Mon Sep 17 00:00:00 2001
From: Evgeny Potemkin <epotemkin@mysql.com>
Date: Wed, 9 Dec 2009 18:43:45 +0300
Subject: [PATCH] Bug#49489: Uninitialized cache led to a wrong result.

Arg_comparator uses Item_cache objects to store constants being compared when
they're need a type conversion. Because this cache wasn't initialized properly
Arg_comparator might produce wrong comparison result.

The Arg_comparator::cache_converted_constant function now initializes cache
prior to usage.

mysql-test/r/select.result:
  Added a test case for he bug#49489.
mysql-test/t/select.test:
  Added a test case for he bug#49489.
sql/item_cmpfunc.cc:
  Bug#49489: Uninitialized cache led to a wrong result.
  The Arg_comparator::cache_converted_constant function now initializes cache
  prior to usage.
---
 mysql-test/r/select.result | 10 ++++++++++
 mysql-test/t/select.test   |  9 +++++++++
 sql/item_cmpfunc.cc        |  2 +-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result
index d0b2a575a32..1750051289a 100644
--- a/mysql-test/r/select.result
+++ b/mysql-test/r/select.result
@@ -4609,4 +4609,14 @@ HAVING v <= 't'
 ORDER BY pk;
 v
 DROP TABLE t1;
+#
+# Bug#49489 Uninitialized cache led to a wrong result.
+#
+CREATE TABLE t1(c1 DOUBLE(5,4));
+INSERT INTO t1 VALUES (9.1234);
+SELECT * FROM t1 WHERE c1 < 9.12345;
+c1
+9.1234
+DROP TABLE t1;
+# End of test for bug#49489.
 End of 5.1 tests
diff --git a/mysql-test/t/select.test b/mysql-test/t/select.test
index ac65e5cbaf5..982aec726f7 100644
--- a/mysql-test/t/select.test
+++ b/mysql-test/t/select.test
@@ -3964,4 +3964,13 @@ ORDER BY pk;
 
 DROP TABLE t1;
 
+--echo #
+--echo # Bug#49489 Uninitialized cache led to a wrong result.
+--echo #
+CREATE TABLE t1(c1 DOUBLE(5,4));
+INSERT INTO t1 VALUES (9.1234);
+SELECT * FROM t1 WHERE c1 < 9.12345;
+DROP TABLE t1;
+--echo # End of test for bug#49489.
+
 --echo End of 5.1 tests
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 5415d6f4f8a..a3c3051d790 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1023,7 +1023,7 @@ Item** Arg_comparator::cache_converted_constant(THD *thd, Item **value,
       (*value)->const_item() && type != (*value)->result_type())
   {
     Item_cache *cache= Item_cache::get_cache(*value, type);
-    cache->store(*value);
+    cache->setup(*value);
     *cache_item= cache;
     return cache_item;
   }