Bug#8663 cant use bgint unsigned as input to cast

Problem: cast to unsigned limited result to 
max signed bigint 9223372036854775808,
instead of max unsigned bigint 18446744073709551615.

Fix: don't use args[0]->val_int() when casting from
a floating point number, use val() instead, with range checkings,
special to unsigned data type.

item_func.cc:
  Special handling of cast from REAL_RESULT
  to unsigned int: we cannot execute args[0]->val_int()
  because it cuts max allowed value to LONGLONG_INT,
  instead of ULONGLONG_INT required.
count_distinct3.test:
  Getting rid of "Data truncated; out of range ..." warnings.
cast.test, cast.result:
  Adding test case.
ps.result:
  Fixing that cast from 6570515219.6535 
  to unsigned didn't round to 6570515220,
  and returned 6570515219 instead.


mysql-test/r/cast.result:
  Adding test case.
mysql-test/r/ps.result:
  Fixing that cast from 6570515219.6535 
  to unsigned didn't round to 6570515220,
  and returned 6570515219 instead.
mysql-test/t/cast.test:
  Adding test case.
mysql-test/t/count_distinct3.test:
  Get rid of "wring unsigned value"
  warnings.
sql/item_func.cc:
  Special handling of cast from REAL)RESULT
  to unsigned int: we cannot execute args[0]->val_int()
  because it cuts max allowed value to LONGLONG_INT,
  instead of ULONGLONG_INT required.

1 files changed, 6 insertions, 0 deletions

diff --git a/mysql-test/t/cast.test b/mysql-test/t/cast.test
index 4d73783dd52..b214cef10fa 100644
--- a/mysql-test/t/cast.test
+++ b/mysql-test/t/cast.test
@@ -148,6 +148,12 @@ select cast(repeat('1',20) as unsigned);
 select cast(repeat('1',20) as signed);
 
 #
+# Bug#8663 cant use bgint unsigned as input to cast
+#
+select cast(19999999999999999999 as unsigned);
+
+
+#
 # Bug #13344: cast of large decimal to signed int not handled correctly
 #
 select cast(1.0e+300 as signed int);