Bug#16172 DECIMAL data type processed incorrectly

issue an 'overflow warning' if result value is bigger than max possible value

include/decimal.h

@@ -48,6 +48,7 @@ int decimal_bin_size(int precision, int scale);
 int decimal_result_size(decimal_t *from1, decimal_t *from2, char op,
                         int param);
 
+int decimal_intg(decimal_t *from);
 int decimal_add(decimal_t *from1, decimal_t *from2, decimal_t *to);
 int decimal_sub(decimal_t *from1, decimal_t *from2, decimal_t *to);
 int decimal_cmp(decimal_t *from1, decimal_t *from2);

mysql-test/r/cast.result

@@ -103,7 +103,7 @@ Warnings:
 Warning	1292	Truncated incorrect DOUBLE value: 'a'
 select 10.0+cast('a' as decimal);
 10.0+cast('a' as decimal)
-10.00
+10.0
 Warnings:
 Warning	1292	Truncated incorrect DECIMAL value: 'a'
 select 10E+0+'a';
@@ -368,7 +368,9 @@ create table t1(s1 time);
 insert into t1 values ('11:11:11');
 select cast(s1 as decimal(7,2)) from t1;
 cast(s1 as decimal(7,2))
-111111.00
+99999.99
+Warnings:
+Error	1264	Out of range value for column 'cast(s1 as decimal(7,2))' at row 1
 drop table t1;
 CREATE TABLE t1 (v varchar(10), tt tinytext, t text,
 mt mediumtext, lt longtext);
@@ -376,7 +378,7 @@ INSERT INTO t1 VALUES ('1.01', '2.02', '3.03', '4.04', '5.05');
 SELECT CAST(v AS DECIMAL), CAST(tt AS DECIMAL), CAST(t AS DECIMAL),
 CAST(mt AS DECIMAL), CAST(lt AS DECIMAL) from t1;
 CAST(v AS DECIMAL)	CAST(tt AS DECIMAL)	CAST(t AS DECIMAL)	CAST(mt AS DECIMAL)	CAST(lt AS DECIMAL)
-1.01	2.02	3.03	4.04	5.05
+1	2	3	4	5
 DROP TABLE t1;
 select cast(NULL as decimal(6)) as t1;
 t1

mysql-test/r/type_newdecimal.result

@@ -1418,3 +1418,30 @@ i2	count(distinct j)
 1.0	2
 2.0	2
 drop table t1;
+select cast(143.481 as decimal(4,1));
+cast(143.481 as decimal(4,1))
+143.5
+select cast(143.481 as decimal(4,0));
+cast(143.481 as decimal(4,0))
+143
+select cast(143.481 as decimal(2,1));
+cast(143.481 as decimal(2,1))
+9.9
+Warnings:
+Error	1264	Out of range value for column 'cast(143.481 as decimal(2,1))' at row 1
+select cast(-3.4 as decimal(2,1));
+cast(-3.4 as decimal(2,1))
+-3.4
+select cast(99.6 as decimal(2,0));
+cast(99.6 as decimal(2,0))
+99
+Warnings:
+Error	1264	Out of range value for column 'cast(99.6 as decimal(2,0))' at row 1
+select cast(-13.4 as decimal(2,1));
+cast(-13.4 as decimal(2,1))
+-9.9
+Warnings:
+Error	1264	Out of range value for column 'cast(-13.4 as decimal(2,1))' at row 1
+select cast(98.6 as decimal(2,0));
+cast(98.6 as decimal(2,0))
+99

mysql-test/r/view.result

@@ -1787,7 +1787,7 @@ drop table t1;
 create view v1 as select cast(1 as decimal);
 select * from v1;
 cast(1 as decimal)
-1.00
+1
 drop view v1;
 create table t1(f1 int);
 create table t2(f2 int);

mysql-test/t/type_newdecimal.test

@@ -1115,3 +1115,14 @@ insert into t1 values (1,1), (1,2), (2,3), (2,4);
 select i, count(distinct j) from t1 group by i;
 select i+0.0 as i2, count(distinct j) from t1 group by i2;
 drop table t1;
+
+#
+# Bug#16172 DECIMAL data type processed incorrectly
+#
+select cast(143.481 as decimal(4,1));
+select cast(143.481 as decimal(4,0));
+select cast(143.481 as decimal(2,1));
+select cast(-3.4 as decimal(2,1));
+select cast(99.6 as decimal(2,0));
+select cast(-13.4 as decimal(2,1));
+select cast(98.6 as decimal(2,0));

sql/item_create.cc

@@ -463,7 +463,7 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
   case ITEM_CAST_TIME:		res= new Item_time_typecast(a); break;
   case ITEM_CAST_DATETIME:	res= new Item_datetime_typecast(a); break;
   case ITEM_CAST_DECIMAL:
-    res= new Item_decimal_typecast(a, (len>0) ? len : 10, dec ? dec : 2);
+    res= new Item_decimal_typecast(a, (len > 0) ? len : 10, dec);
     break;
   case ITEM_CAST_CHAR:
     res= new Item_char_typecast(a, len, cs ? cs : 

sql/item_func.cc

@@ -955,9 +955,32 @@ longlong Item_decimal_typecast::val_int()
 my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
 {
   my_decimal tmp_buf, *tmp= args[0]->val_decimal(&tmp_buf);
+  bool sign;
   if ((null_value= args[0]->null_value))
     return NULL;
   my_decimal_round(E_DEC_FATAL_ERROR, tmp, decimals, FALSE, dec);
+  sign= dec->sign();
+  if (unsigned_flag)
+  {
+    if (sign)
+    {
+      my_decimal_set_zero(dec);
+      goto err;
+    }
+  }
+  if (max_length - 2 - decimals < (uint) my_decimal_intg(dec))
+  {
+    max_my_decimal(dec, max_length - 2, decimals);
+    dec->sign(sign);
+    goto err;
+  }
+  return dec;
+
+err:
+  push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_ERROR,
+                      ER_WARN_DATA_OUT_OF_RANGE,
+                      ER(ER_WARN_DATA_OUT_OF_RANGE),
+                      name, 1);
   return dec;
 }
 

sql/my_decimal.h

@@ -383,5 +383,13 @@ int my_decimal_cmp(const my_decimal *a, const my_decimal *b)
   return decimal_cmp((decimal_t*) a, (decimal_t*) b);
 }
 
+
+inline
+int my_decimal_intg(const my_decimal *a)
+{
+  return decimal_intg((decimal_t*) a);
+}
+
+
 #endif /*my_decimal_h*/
 

strings/decimal.c

@@ -1896,6 +1896,14 @@ static int do_sub(decimal_t *from1, decimal_t *from2, decimal_t *to)
   return error;
 }
 
+int decimal_intg(decimal_t *from)
+{
+  int res;
+  dec1 *tmp_res;
+  tmp_res= remove_leading_zeroes(from, &res);
+  return res;
+}
+
 int decimal_add(decimal_t *from1, decimal_t *from2, decimal_t *to)
 {
   if (likely(from1->sign == from2->sign))