Merge gleb.loc:/home/uchum/work/bk/5.0-opt-29360

into  gleb.loc:/home/uchum/work/bk/5.0-opt

mysql-test/r/type_enum.result

@@ -1809,3 +1809,23 @@ f1
 
 
 drop table t1;
+CREATE TABLE t1 (c1 ENUM('a', '', 'b'));
+INSERT INTO t1 (c1) VALUES ('b');
+INSERT INTO t1 (c1) VALUES ('');
+INSERT INTO t1 (c1) VALUES (0);
+Warnings:
+Warning	1265	Data truncated for column 'c1' at row 1
+INSERT INTO t1 (c1) VALUES ('');
+SELECT c1 + 0, COUNT(c1) FROM t1 GROUP BY c1;
+c1 + 0	COUNT(c1)
+0	1
+2	2
+3	1
+CREATE TABLE t2 SELECT * FROM t1;
+SELECT c1 + 0 FROM t2;
+c1 + 0
+3
+2
+0
+2
+DROP TABLE t1,t2;

mysql-test/r/type_ranges.result

@@ -208,10 +208,6 @@ options	flags
 one	one
 drop table t2;
 create table t2 select * from t1;
-Warnings:
-Warning	1265	Data truncated for column 'options' at row 4
-Warning	1265	Data truncated for column 'options' at row 5
-Warning	1265	Data truncated for column 'options' at row 6
 update t2 set string="changed" where auto=16;
 show full columns from t1;
 Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment

mysql-test/t/type_enum.test

@@ -182,3 +182,21 @@ create table t1(f1 set('a','b'), index(f1));
 insert into t1 values(''),(''),('a'),('b');
 select * from t1 where f1='';
 drop table t1;
+
+#
+# Bug#29360: Confluence of the special 0 enum value with the normal empty string
+# value during field to field copy.
+#
+
+CREATE TABLE t1 (c1 ENUM('a', '', 'b'));
+INSERT INTO t1 (c1) VALUES ('b');
+INSERT INTO t1 (c1) VALUES ('');
+INSERT INTO t1 (c1) VALUES (0);
+INSERT INTO t1 (c1) VALUES ('');
+
+SELECT c1 + 0, COUNT(c1) FROM t1 GROUP BY c1;
+
+CREATE TABLE t2 SELECT * FROM t1;
+SELECT c1 + 0 FROM t2;
+
+DROP TABLE t1,t2;

sql/field_conv.cc

@@ -790,7 +790,13 @@ int field_conv(Field *to,Field *from)
       blob->value.copy();
     return blob->store(blob->value.ptr(),blob->value.length(),from->charset());
   }
-  if ((from->result_type() == STRING_RESULT &&
+  if (from->real_type() == FIELD_TYPE_ENUM &&
+      to->real_type() == FIELD_TYPE_ENUM &&
+      from->val_int() == 0)
+  {
+    ((Field_enum *)(to))->store_type(0);
+  }
+  else if ((from->result_type() == STRING_RESULT &&
             (to->result_type() == STRING_RESULT ||
              (from->real_type() != FIELD_TYPE_ENUM &&
               from->real_type() != FIELD_TYPE_SET))) ||