Bug#58005 utf8 + get_format causes failed assertion: !str || str != Ptr'

Problem: When GET_FORMAT() is called two times from the upper
level function (e.g. LEAST in the bug report), on the second
call "res= args[0]->val_str(...)" and str point to the same
String object.

1. Fix: changing the order from
- get val_str into tmp_value then convert to str
to
- get val_str into str then convert to tmp_value

The new order is more correct: the purpose of "str" parameter
is exactly to call val_str() for arguments.
The purpose of String class members (like tmp_value) is to do further
actions on the result.
Doing it in the other way around give unexpected surprises.

2. Using str_value instead of str to do padding, for the same reason.

1 files changed, 16 insertions, 0 deletions

diff --git a/mysql-test/t/date_formats.test b/mysql-test/t/date_formats.test
index e5dc7ffa53e..2a5de8ca9ba 100644
--- a/mysql-test/t/date_formats.test
+++ b/mysql-test/t/date_formats.test
@@ -359,3 +359,19 @@ SELECT DATE_FORMAT("0000-02-28",'%W %d %M %Y') as valid_date;
 SELECT DATE_FORMAT("2009-01-01",'%W %d %M %Y') as valid_date;
 
 --echo "End of 5.0 tests"
+
+
+--echo #
+--echo # Start of 5.1 tests
+--echo #
+
+--echo #
+--echo # Bug#58005 utf8 + get_format causes failed assertion: !str || str != Ptr'
+--echo #
+SET NAMES utf8;
+SELECT LEAST('%', GET_FORMAT(datetime, 'eur'), CAST(GET_FORMAT(datetime, 'eur') AS CHAR(65535)));
+SET NAMES latin1;
+
+--echo #
+--echo # End of 5.1 tests
+--echo #