Bug#45263 utf32_general_ci, bad effects around CREATE TABLE AS SELECT

Problem: Item_func_hex::val_str() returned data in ASCII format,
which did not match collation.collation pointing to my_charset_utf32_general_ci.
Fix: changing parent class of Item_func_hex to Item_str_ascii_func,
as val_str() implementation is heavily ASCII-oriented.

  mysql-test/r/ctype_utf32.result
  mysql-test/t/ctype_utf32.test
  Adding test case


  sql/item_strfunc.cc
  sql/item_strfunc.h
  - Changing parent class to Item_str_ascii_func
  - Clean-up in Item_func_hex::fix_length_and_dec()
    Using fix_char_length() instead of setting max_length directly.

mysql-test/r/ctype_utf32.result

@@ -1091,5 +1091,14 @@ t2	CREATE TABLE `t2` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1, t2;
 #
+# Bug#45263 utf32_general_ci, bad effects around CREATE TABLE AS SELECT
+#
+SET collation_connection=utf32_general_ci;
+CREATE TABLE t1 AS SELECT HEX(0x00) AS my_col;
+SELECT * FROM t1;
+my_col
+00
+DROP TABLE t1;
+#
 # End of 5.5 tests
 #

mysql-test/t/ctype_utf32.test

@@ -800,6 +800,15 @@ CREATE TABLE t2 AS SELECT CONCAT(s1) FROM t1;
 SHOW CREATE TABLE t2;
 DROP TABLE t1, t2;
 
+
+--echo #
+--echo # Bug#45263 utf32_general_ci, bad effects around CREATE TABLE AS SELECT
+--echo #
+SET collation_connection=utf32_general_ci;
+CREATE TABLE t1 AS SELECT HEX(0x00) AS my_col;
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo #
 --echo # End of 5.5 tests
 --echo #

sql/item_strfunc.cc

@@ -3081,7 +3081,7 @@ String *Item_func_collation::val_str(String *str)
 }
 
 
-String *Item_func_hex::val_str(String *str)
+String *Item_func_hex::val_str_ascii(String *str)
 {
   String *res;
   DBUG_ASSERT(fixed == 1);
@@ -3120,6 +3120,7 @@ String *Item_func_hex::val_str(String *str)
   }
   null_value=0;
   tmp_value.length(res->length()*2);
+  tmp_value.set_charset(&my_charset_latin1);
 
   octet2hex((char*) tmp_value.ptr(), res->ptr(), res->length());
   return &tmp_value;

sql/item_strfunc.h

@@ -622,18 +622,18 @@ public:
 };
 
 
-class Item_func_hex :public Item_str_func
+class Item_func_hex :public Item_str_ascii_func
 {
   String tmp_value;
 public:
-  Item_func_hex(Item *a) :Item_str_func(a) {}
+  Item_func_hex(Item *a) :Item_str_ascii_func(a) {}
   const char *func_name() const { return "hex"; }
-  String *val_str(String *);
+  String *val_str_ascii(String *);
   void fix_length_and_dec()
   {
     collation.set(default_charset());
     decimals=0;
-    max_length=args[0]->max_length*2*collation.collation->mbmaxlen;
+    fix_char_length(args[0]->max_length * 2);
   }
 };