MDEV-20890 Illegal mix of collations with UUID()

mysql-test/main/ctype_binary.result

@@ -807,12 +807,12 @@ create table t1 as select concat(uuid()) as c1;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` varchar(36) CHARACTER SET utf8 DEFAULT NULL
+  `c1` varbinary(36) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 select coercibility(uuid()), coercibility(cast('a' as char character set latin1));
 coercibility(uuid())	coercibility(cast('a' as char character set latin1))
-4	2
+5	2
 select charset(concat(uuid(), cast('a' as char character set latin1)));
 charset(concat(uuid(), cast('a' as char character set latin1)))
 latin1

mysql-test/main/ctype_cp1251.result

@@ -1216,12 +1216,12 @@ create table t1 as select concat(uuid()) as c1;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` varchar(36) CHARACTER SET utf8 DEFAULT NULL
+  `c1` varchar(36) CHARACTER SET cp1251 DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 select coercibility(uuid()), coercibility(cast('a' as char character set latin1));
 coercibility(uuid())	coercibility(cast('a' as char character set latin1))
-4	2
+5	2
 select charset(concat(uuid(), cast('a' as char character set latin1)));
 charset(concat(uuid(), cast('a' as char character set latin1)))
 latin1

mysql-test/main/ctype_latin1.result

@@ -1525,12 +1525,12 @@ create table t1 as select concat(uuid()) as c1;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` varchar(36) CHARACTER SET utf8 DEFAULT NULL
+  `c1` varchar(36) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 select coercibility(uuid()), coercibility(cast('a' as char character set latin1));
 coercibility(uuid())	coercibility(cast('a' as char character set latin1))
-4	2
+5	2
 select charset(concat(uuid(), cast('a' as char character set latin1)));
 charset(concat(uuid(), cast('a' as char character set latin1)))
 latin1

mysql-test/main/ctype_ucs.result

@@ -2409,12 +2409,12 @@ create table t1 as select concat(uuid()) as c1;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` varchar(36) CHARACTER SET utf8 DEFAULT NULL
+  `c1` varchar(36) CHARACTER SET ucs2 DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 select coercibility(uuid()), coercibility(cast('a' as char character set latin1));
 coercibility(uuid())	coercibility(cast('a' as char character set latin1))
-4	2
+5	2
 select charset(concat(uuid(), cast('a' as char character set latin1)));
 charset(concat(uuid(), cast('a' as char character set latin1)))
 latin1

mysql-test/main/ctype_utf8.result

@@ -3281,7 +3281,7 @@ t1	CREATE TABLE `t1` (
 drop table t1;
 select coercibility(uuid()), coercibility(cast('a' as char character set latin1));
 coercibility(uuid())	coercibility(cast('a' as char character set latin1))
-4	2
+5	2
 select charset(concat(uuid(), cast('a' as char character set latin1)));
 charset(concat(uuid(), cast('a' as char character set latin1)))
 latin1
@@ -11341,5 +11341,12 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 #
+# MDEV-20890 Illegal mix of collations with UUID()
+#
+SET NAMES utf8 COLLATE utf8_unicode_ci;
+SELECT uuid()>'';
+uuid()>''
+1
+#
 # End of 10.5 tests
 #

mysql-test/main/ctype_utf8.test

@@ -2276,6 +2276,13 @@ CREATE OR REPLACE TABLE t1 AS SELECT CAST(1 AS BINARY), CAST(@a AS BINARY), CAST
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-20890 Illegal mix of collations with UUID()
+--echo #
+
+SET NAMES utf8 COLLATE utf8_unicode_ci;
+SELECT uuid()>'';
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

mysql-test/main/func_misc.result

@@ -22,7 +22,7 @@ hex(inet_aton('127.1.1'))
 7F010001
 select length(uuid()), charset(uuid()), length(unhex(replace(uuid(),_utf8'-',_utf8'')));
 length(uuid())	charset(uuid())	length(unhex(replace(uuid(),_utf8'-',_utf8'')))
-36	utf8	16
+36	latin1	16
 set @a= uuid_short();
 set @b= uuid_short();
 select @b - @a;
@@ -107,7 +107,7 @@ create table t1 as select uuid(), length(uuid());
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `uuid()` varchar(36) CHARACTER SET utf8 DEFAULT NULL,
+  `uuid()` varchar(36) DEFAULT NULL,
   `length(uuid())` int(10) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;

sql/item_strfunc.h

@@ -1663,8 +1663,7 @@ class Item_func_uuid: public Item_str_func
   Item_func_uuid(THD *thd): Item_str_func(thd) {}
   bool fix_length_and_dec()
   {
-    collation.set(system_charset_info,
-                  DERIVATION_COERCIBLE, MY_REPERTOIRE_ASCII);
+    collation.set(DTCollation_numeric());
     fix_char_length(MY_UUID_STRING_LENGTH);
     return FALSE;
   }