ctype_collate.result, ctype_collate.test, union.result, union.test:

  fixing tests accordingly
item.cc:
  Allow mixing non-binary collation and binary collation
  even if coercibility is the same. 
  For easier 4.0 -> 4.1 migrating.

mysql-test/r/ctype_collate.result

@@ -535,6 +535,19 @@ s2 CHAR(5) COLLATE latin1_swedish_ci);
 SELECT * FROM t1 WHERE s1 = s2;
 ERROR HY000: Illegal mix of collations (latin1_german1_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='
 DROP TABLE t1;
+CREATE TABLE t1
+(s1 CHAR(5) COLLATE latin1_german1_ci,
+s2 CHAR(5) COLLATE latin1_swedish_ci,
+s3 CHAR(5) COLLATE latin1_bin);
+INSERT INTO t1 VALUES ('a','A','A');
+SELECT * FROM t1 WHERE s1 = s2;
+ERROR HY000: Illegal mix of collations (latin1_german1_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='
+SELECT * FROM t1 WHERE s1 = s3;
+s1	s2	s3
+SELECT * FROM t1 WHERE s2 = s3;
+s1	s2	s3
+a	A	A
+DROP TABLE t1;
 SET NAMES latin1;
 CREATE TABLE t1 
 (s1 char(10) COLLATE latin1_german1_ci,

mysql-test/r/union.result

@@ -1103,7 +1103,7 @@ count(*)
 drop table t1;
 create table t2 (
 a char character set latin1 collate latin1_swedish_ci,
-b char character set latin1 collate latin1_bin);
+b char character set latin1 collate latin1_german1_ci);
 create table t1 as
 (select a from t2) union
 (select b from t2);

mysql-test/t/ctype_collate.test

@@ -158,6 +158,18 @@ SELECT * FROM t1 WHERE s1 = s2;
 DROP TABLE t1;
 
 
+CREATE TABLE t1
+(s1 CHAR(5) COLLATE latin1_german1_ci,
+ s2 CHAR(5) COLLATE latin1_swedish_ci,
+ s3 CHAR(5) COLLATE latin1_bin);
+INSERT INTO t1 VALUES ('a','A','A');
+--error 1267
+SELECT * FROM t1 WHERE s1 = s2;
+SELECT * FROM t1 WHERE s1 = s3;
+SELECT * FROM t1 WHERE s2 = s3;
+DROP TABLE t1;
+
+
 #
 # Test that optimizer doesn't use indexes with wrong collation
 #

mysql-test/t/union.test

@@ -641,7 +641,7 @@ drop table t1;
 
 create table t2 (
 a char character set latin1 collate latin1_swedish_ci,
-b char character set latin1 collate latin1_bin);
+b char character set latin1 collate latin1_german1_ci);
 --error 1271
 create table t1 as
 (select a from t2) union

sql/item.cc

@@ -474,8 +474,17 @@ bool DTCollation::aggregate(DTCollation &dt, uint flags)
 	set(0, DERIVATION_NONE);
 	return 1;
       }
+      if (collation->state & MY_CS_BINSORT)
+      {
+        return 0;
+      }
+      else if (dt.collation->state & MY_CS_BINSORT)
+      {
+        set(dt);
+        return 0;
+      }
       CHARSET_INFO *bin= get_charset_by_csname(collation->csname, 
-					       MY_CS_BINSORT,MYF(0));
+                                               MY_CS_BINSORT,MYF(0));
       set(bin, DERIVATION_NONE);
     }
   }