Merge branch 'mysql-5.5' into mysql-5.6

Author: Tor Didriksen

mysql-test/r/case.result

@@ -224,3 +224,19 @@ CREATE TABLE t1(a YEAR);
 SELECT 1 FROM t1 WHERE a=1 AND CASE 1 WHEN a THEN 1 ELSE 1 END;
 1
 DROP TABLE t1;
+#
+# Bug#19875294 ASSERTION `SRC' FAILED IN MY_STRNXFRM_UNICODE
+#              (SIG 6 -STRINGS/CTYPE-UTF8.C:5151)
+#
+set @@sql_mode='';
+CREATE TABLE t1(c1 SET('','')CHARACTER SET ucs2) engine=innodb;
+Warnings:
+Note	1291	Column 'c1' has duplicated value '' in SET
+INSERT INTO t1 VALUES(990101.102);
+Warnings:
+Warning	1265	Data truncated for column 'c1' at row 1
+SELECT COALESCE(c1)FROM t1 ORDER BY 1;
+COALESCE(c1)
+
+DROP TABLE t1;
+set @@sql_mode=default;

mysql-test/t/case.test

@@ -182,3 +182,15 @@ drop table t1, t2;
 CREATE TABLE t1(a YEAR);
 SELECT 1 FROM t1 WHERE a=1 AND CASE 1 WHEN a THEN 1 ELSE 1 END;
 DROP TABLE t1;
+
+--echo #
+--echo # Bug#19875294 ASSERTION `SRC' FAILED IN MY_STRNXFRM_UNICODE
+--echo #              (SIG 6 -STRINGS/CTYPE-UTF8.C:5151)
+--echo #
+
+set @@sql_mode='';
+CREATE TABLE t1(c1 SET('','')CHARACTER SET ucs2) engine=innodb;
+INSERT INTO t1 VALUES(990101.102);
+SELECT COALESCE(c1)FROM t1 ORDER BY 1;
+DROP TABLE t1;
+set @@sql_mode=default;

sql/field.cc

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -8691,13 +8691,13 @@ String *Field_set::val_str(String *val_buffer,
   ulonglong tmp=(ulonglong) Field_enum::val_int();
   uint bitnr=0;
 
+  /*
+    Some callers expect *val_buffer to contain the result,
+    so we assign to it, rather than doing 'return &empty_set_string.
+  */
+  *val_buffer= empty_set_string;
   if (tmp == 0)
   {
-    /*
-      Some callers expect *val_buffer to contain the result,
-      so we assign to it, rather than doing 'return &empty_set_string.
-     */
-    *val_buffer= empty_set_string;
     return val_buffer;
   }