hf's fix for bug #9060 (FORMAT returns incorrect result)

we need proper rounding there


mysql-test/r/func_math.result:
  test result fixed
mysql-test/t/func_math.test:
  test case added
sql/item_func.cc:
  my_double_round implementation added
sql/item_strfunc.cc:
  my_double_round used
sql/mysql_priv.h:
  my_double_round interface

mysql-test/r/func_math.result

@@ -120,6 +120,9 @@ ASIN(0.8+0.2)
 SELECT ASIN(1.2-0.2);
 ASIN(1.2-0.2)
 1.5707963267949
+select format(4.55, 1), format(4.551, 1);
+format(4.55, 1)	format(4.551, 1)
+4.6	4.6
 explain extended select degrees(pi()),radians(360);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

mysql-test/t/func_math.test

@@ -54,6 +54,11 @@ SELECT ASIN(1.2-0.2);
 #select floor(log(8)/log(2));
 #select floor(log(16)/log(2));
 
+#
+# Bug #9060 (format returns incorrect result)
+#
+select format(4.55, 1), format(4.551, 1);
+
 explain extended select degrees(pi()),radians(360);
 
 #

sql/item_func.cc

@@ -1880,22 +1880,16 @@ void Item_func_round::fix_length_and_dec()
   }
 }
 
-double Item_func_round::real_op()
+double my_double_round(double value, int dec, bool truncate)
 {
-  double value= args[0]->val_real();
-  int dec=(int) args[1]->val_int();
-  if (dec > 0)
-    decimals= dec; // to get correct output
-  uint abs_dec=abs(dec);
   double tmp;
+  uint abs_dec= abs(dec);
   /*
     tmp2 is here to avoid return the value with 80 bit precision
     This will fix that the test round(0.1,1) = round(0.1,1) is true
   */
   volatile double tmp2;
 
-  if ((null_value=args[0]->null_value || args[1]->null_value))
-    return 0.0;
   tmp=(abs_dec < array_elements(log_10) ?
        log_10[abs_dec] : pow(10.0,(double) abs_dec));
 
@@ -1912,6 +1906,18 @@ double Item_func_round::real_op()
 }
 
 
+double Item_func_round::real_op()
+{
+  double value= args[0]->val_real();
+  int dec= (int) args[1]->val_int();
+
+  if (!(null_value= args[0]->null_value || args[1]->null_value))
+    return my_double_round(value, dec, truncate);
+
+  return 0.0;
+}
+
+
 longlong Item_func_round::int_op()
 {
   longlong value= args[0]->val_int();

sql/item_strfunc.cc

@@ -1673,6 +1673,7 @@ String *Item_func_format::val_str(String *str)
   int diff;
   if ((null_value=args[0]->null_value))
     return 0; /* purecov: inspected */
+  nr= my_double_round(nr, decimals, FALSE);
   dec= decimals ? decimals+1 : 0;
   /* Here default_charset() is right as this is not an automatic conversion */
   str->set(nr,decimals, default_charset());

sql/mysql_priv.h

@@ -1251,6 +1251,7 @@ ha_rows filesort(THD *thd, TABLE *form,struct st_sort_field *sortorder,
 		 ha_rows max_rows, ha_rows *examined_rows);
 void filesort_free_buffers(TABLE *table);
 void change_double_for_sort(double nr,byte *to);
+double my_double_round(double value, int dec, bool truncate);
 int get_quick_record(SQL_SELECT *select);
 int calc_weekday(long daynr,bool sunday_first_day_of_week);
 uint calc_week(TIME *l_time, uint week_behaviour, uint *year);