#2244 User variables collation conflict is not detected

mysql-test/r/user_var.result

@@ -120,3 +120,45 @@ select @a+0, @a:=@a+0+count(*), count(*), @a+0 from t1 group by i;
 1	3	2	0
 3	6	3	0
 drop table t1;
+set @a=_latin2'test';
+select charset(@a),collation(@a),coercibility(@a);
+charset(@a)	collation(@a)	coercibility(@a)
+latin2	latin2_general_ci	3
+select @a=_latin2'TEST';
+@a=_latin2'TEST'
+1
+select @a=_latin2'TEST' collate latin2_bin;
+@a=_latin2'TEST' collate latin2_bin
+0
+set @a=_latin2'test' collate latin2_general_ci;
+select charset(@a),collation(@a),coercibility(@a);
+charset(@a)	collation(@a)	coercibility(@a)
+latin2	latin2_general_ci	0
+select @a=_latin2'TEST';
+@a=_latin2'TEST'
+1
+select @a=_latin2'TEST' collate latin2_bin;
+ERROR HY000: Illegal mix of collations (latin2_general_ci,EXPLICIT) and (latin2_bin,EXPLICIT) for operation '='
+select charset(@a:=_latin2'test');
+charset(@a:=_latin2'test')
+latin2
+select collation(@a:=_latin2'test');
+collation(@a:=_latin2'test')
+latin2_general_ci
+select coercibility(@a:=_latin2'test');
+coercibility(@a:=_latin2'test')
+3
+select collation(@a:=_latin2'test' collate latin2_bin);
+collation(@a:=_latin2'test' collate latin2_bin)
+latin2_bin
+select coercibility(@a:=_latin2'test' collate latin2_bin);
+coercibility(@a:=_latin2'test' collate latin2_bin)
+0
+select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST';
+(@a:=_latin2'test' collate latin2_bin) = _latin2'TEST'
+0
+select charset(@a),collation(@a),coercibility(@a);
+charset(@a)	collation(@a)	coercibility(@a)
+latin2	latin2_bin	0
+select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST' collate latin2_general_ci;
+ERROR HY000: Illegal mix of collations (latin2_bin,EXPLICIT) and (latin2_general_ci,EXPLICIT) for operation '='

mysql-test/t/user_var.test

@@ -71,3 +71,31 @@ select @a:=0; select @a, @a:=@a+count(*), count(*), @a from t1 group by i;
 select @a:=0; select @a+0, @a:=@a+0+count(*), count(*), @a+0 from t1 group by i;
 drop table t1;
 
+#
+# Bug #2244: User variables didn't copy collation and derivation
+# attributes from values they were initialized to.
+#
+
+set @a=_latin2'test';
+select charset(@a),collation(@a),coercibility(@a);
+select @a=_latin2'TEST';
+select @a=_latin2'TEST' collate latin2_bin;
+
+set @a=_latin2'test' collate latin2_general_ci;
+select charset(@a),collation(@a),coercibility(@a);
+select @a=_latin2'TEST';
+--error 1266
+select @a=_latin2'TEST' collate latin2_bin;
+
+#
+# Check the same invoking Item_set_user_var
+#
+select charset(@a:=_latin2'test');
+select collation(@a:=_latin2'test');
+select coercibility(@a:=_latin2'test');
+select collation(@a:=_latin2'test' collate latin2_bin);
+select coercibility(@a:=_latin2'test' collate latin2_bin);
+select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST';
+select charset(@a),collation(@a),coercibility(@a);
+--error 1266
+select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST' collate latin2_general_ci;

sql/item_func.cc

@@ -2163,6 +2163,7 @@ bool Item_func_set_user_var::fix_fields(THD *thd, TABLE_LIST *tables,
      is different from query_id).
   */
   entry->update_query_id= thd->query_id;
+  entry->collation.set(args[0]->collation);
   cached_result_type= args[0]->result_type();
   return 0;
 }
@@ -2174,6 +2175,7 @@ Item_func_set_user_var::fix_length_and_dec()
   maybe_null=args[0]->maybe_null;
   max_length=args[0]->max_length;
   decimals=args[0]->decimals;
+  collation.set(args[0]->collation);
 }
 
 
@@ -2488,7 +2490,9 @@ void Item_func_get_user_var::fix_length_and_dec()
 
   if (!(var_entry= get_variable(&thd->user_vars, name, 0)))
     null_value= 1;
-
+  else
+    collation.set(var_entry->collation);
+  
   if (!(opt_bin_log && is_update_query(thd->lex->sql_command)))
     return;