Fixed bug #20108.

Any default value for a enum fields over UCS2 charsets was corrupted
when we put it into the frm file, as it had been overwritten by its
HEX representation.
To fix it now we save a copy of structure that represents the enum
type and when putting the default values we use this copy. 

mysql-test/r/ctype_ucs.result

@@ -747,6 +747,27 @@ select export_set(5, name, upper(name), ",", 5) from bug20536;
 export_set(5, name, upper(name), ",", 5)
 test1,TEST1,test1,TEST1,TEST1
 'test\_2','TEST\_2','test\_2','TEST\_2','TEST\_2'
+CREATE TABLE t1 (
+status enum('active','passive') collate latin1_general_ci 
+NOT NULL default 'passive'
+);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `status` enum('active','passive') character set latin1 collate latin1_general_ci NOT NULL default 'passive'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ALTER TABLE t1 ADD a int NOT NULL AFTER status;
+CREATE TABLE t2 (
+status enum('active','passive') collate ucs2_turkish_ci 
+NOT NULL default 'passive'
+);
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `status` enum('active','passive') character set ucs2 collate ucs2_turkish_ci NOT NULL default 'passive'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ALTER TABLE t2 ADD a int NOT NULL AFTER status;
+DROP TABLE t1,t2;
 select password(name) from bug20536;
 password(name)
 ????????????????????

mysql-test/t/ctype_ucs.test

@@ -482,6 +482,27 @@ select make_set(3, name, upper(name)) from bug20536;
 select export_set(5, name, upper(name)) from bug20536;
 select export_set(5, name, upper(name), ",", 5) from bug20536;
 
+#
+# Bug #20108: corrupted default enum value for a ucs2 field              
+#
+
+CREATE TABLE t1 (
+  status enum('active','passive') collate latin1_general_ci 
+    NOT NULL default 'passive'
+);
+SHOW CREATE TABLE t1;
+ALTER TABLE t1 ADD a int NOT NULL AFTER status; 
+
+CREATE TABLE t2 (
+  status enum('active','passive') collate ucs2_turkish_ci 
+    NOT NULL default 'passive'
+);
+SHOW CREATE TABLE t2;
+ALTER TABLE t2 ADD a int NOT NULL AFTER status; 
+
+DROP TABLE t1,t2;
+
+
 # Some broken functions:  add these tests just to document current behavior.
 
 # PASSWORD and OLD_PASSWORD don't work with UCS2 strings, but to fix it would

sql/field.h

@@ -1192,6 +1192,8 @@ public:
   uint decimals,flags,pack_length;
   Field::utype unireg_check;
   TYPELIB *interval;			// Which interval to use
+  TYPELIB *save_interval;               // Temporary copy for the above
+                                        // Used only for UCS2 intervals
   List<String> interval_list;
   CHARSET_INFO *charset;
   Field::geometry_type geom_type;

sql/unireg.cc

@@ -190,13 +190,19 @@ bool mysql_create_frm(THD *thd, my_string file_name,
     goto err3;
 
   {
-    /* Unescape all UCS2 intervals: were escaped in pack_headers */
+    /* 
+      Restore all UCS2 intervals.
+      HEX representation of them is not needed anymore.
+    */
     List_iterator<create_field> it(create_fields);
     create_field *field;
     while ((field=it++))
     {
-      if (field->interval && field->charset->mbminlen > 1)
-        unhex_type2(field->interval);
+      if (field->save_interval)
+      {
+        field->interval= field->save_interval;
+        field->save_interval= 0;
+      }
     }
   }
   DBUG_RETURN(0);
@@ -452,18 +458,36 @@ static bool pack_header(uchar *forminfo, enum db_type table_type,
       reclength=(uint) (field->offset+ data_offset + length);
     n_length+= (ulong) strlen(field->field_name)+1;
     field->interval_id=0;
+    field->save_interval= 0;
     if (field->interval)
     {
       uint old_int_count=int_count;
 
       if (field->charset->mbminlen > 1)
       {
-        /* Escape UCS2 intervals using HEX notation */
+        /* 
+          Escape UCS2 intervals using HEX notation to avoid
+          problems with delimiters between enum elements.
+          As the original representation is still needed in 
+          the function make_empty_rec to create a record of
+          filled with default values it is saved in save_interval
+          The HEX representation is created from this copy.
+        */
+        field->save_interval= field->interval;
+        field->interval= (TYPELIB*) sql_alloc(sizeof(TYPELIB));
+        *field->interval= *field->save_interval; 
+        field->interval->type_names= 
+          (const char **) sql_alloc(sizeof(char*) * 
+				    (field->interval->count+1));
+        field->interval->type_names[field->interval->count]= 0;
+        field->interval->type_lengths=
+          (uint *) sql_alloc(sizeof(uint) * field->interval->count);
+ 
         for (uint pos= 0; pos < field->interval->count; pos++)
         {
           char *dst;
-          uint length= field->interval->type_lengths[pos], hex_length;
-          const char *src= field->interval->type_names[pos];
+          uint length= field->save_interval->type_lengths[pos], hex_length;
+          const char *src= field->save_interval->type_names[pos];
           const char *srcend= src + length;
           hex_length= length * 2;
           field->interval->type_lengths[pos]= hex_length;
@@ -715,7 +739,8 @@ static bool make_empty_rec(File file,enum db_type table_type,
 			       field->charset,
 			       field->geom_type,
 			       field->unireg_check,
-			       field->interval,
+			       field->save_interval ? field->save_interval :
+                               field->interval, 
 			       field->field_name,
 			       &table);