Add 5.0 part of fix for bug 17047.

mysql-test/r/func_str.result:
  Add result for bug#17047: CHAR() and IN() can return NULL without
  signaling NULL result.
mysql-test/t/func_str.test:
  Add test case for bug#17047: CHAR() and IN() can return NULL without
  signaling NULL result.
sql/item_strfunc.cc:
  Add Item_str_func::fix_fields() implementation, and set maybe_null to
  TRUE if we are in the SQL mode that requires some functions to return
  null even if they normally do not.
sql/item_strfunc.h:
  Add declaration of Item_str_func::fix_fields().
  Do not reset maybe_null in Item_func_char::fix_length_and_dec().

1 files changed, 14 insertions, 0 deletions

diff --git a/mysql-test/t/func_str.test b/mysql-test/t/func_str.test
index 45415882ac7..9255669f6e3 100644
--- a/mysql-test/t/func_str.test
+++ b/mysql-test/t/func_str.test
@@ -780,4 +780,18 @@ SELECT * FROM t1 INNER JOIN t2 ON code=id
 
 DROP TABLE t1,t2;
 
+
+#
+# BUG#17047: CHAR() and IN() can return NULL without signaling NULL
+# result
+#
+SET @orig_sql_mode = @@SQL_MODE;
+SET SQL_MODE=traditional;
+
+SELECT CHAR(0xff,0x8f USING utf8);
+SELECT CHAR(0xff,0x8f USING utf8) IS NULL;
+
+SET SQL_MODE=@orig_sql_mode;
+
+
 --echo End of 5.0 tests