merging fixes

mysql-test/r/type_datetime.result:
  result fixed
mysql-test/t/type_datetime.test:
  testcase fixed
sql/item_func.cc:
  my_decimal_length_to_precision used
sql/my_decimal.h:
  merging fix

mysql-test/r/type_datetime.result

@@ -328,8 +328,8 @@ least(cast('01-01-01' as datetime), '01-01-02') + 0
 select cast(least(cast('01-01-01' as datetime), '01-01-02') as signed);
 cast(least(cast('01-01-01' as datetime), '01-01-02') as signed)
 20010101000000
-select cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal);
-cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal)
+select cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal(20,2));
+cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal(20,2))
 20010101000000.00
 DROP PROCEDURE IF EXISTS test27759 ;
 CREATE PROCEDURE test27759()

mysql-test/t/type_datetime.test

@@ -207,7 +207,7 @@ select least(cast('01-01-01' as date), '01-01-02') + 0;
 select greatest(cast('01-01-01' as date), '01-01-02') + 0;
 select least(cast('01-01-01' as datetime), '01-01-02') + 0;
 select cast(least(cast('01-01-01' as datetime), '01-01-02') as signed);
-select cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal);
+select cast(least(cast('01-01-01' as datetime), '01-01-02') as decimal(20,2));
 --disable_warnings
 DROP PROCEDURE IF EXISTS test27759 ;
 --enable_warnings

sql/item_func.cc

@@ -1051,6 +1051,8 @@ my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
 {
   my_decimal tmp_buf, *tmp= args[0]->val_decimal(&tmp_buf);
   bool sign;
+  uint precision;
+
   if ((null_value= args[0]->null_value))
     return NULL;
   my_decimal_round(E_DEC_FATAL_ERROR, tmp, decimals, FALSE, dec);
@@ -1063,9 +1065,11 @@ my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
       goto err;
     }
   }
-  if (max_length - 2 - decimals < (uint) my_decimal_intg(dec))
+  precision= my_decimal_length_to_precision(max_length,
+                                            decimals, unsigned_flag);
+  if (precision - decimals < (uint) my_decimal_intg(dec))
   {
-    max_my_decimal(dec, max_length - 2, decimals);
+    max_my_decimal(dec, precision, decimals);
     dec->sign(sign);
     goto err;
   }
@@ -1084,7 +1088,6 @@ void Item_decimal_typecast::print(String *str)
 {
   char len_buf[20*3 + 1];
   char *end;
-  CHARSET_INFO *cs= str->charset();
 
   uint precision= my_decimal_length_to_precision(max_length, decimals,
                                                  unsigned_flag);

sql/my_decimal.h

@@ -395,6 +395,7 @@ int my_decimal_intg(const my_decimal *a)
 }
 
 
+inline
 void my_decimal_trim(ulong *precision, uint *scale)
 {
   if (!(*precision) && !(*scale))