fixed bug in Item_func_div::val_int() that broke all functions that

do val_int() on their arguments before starting the computation. 
Similar fixes are need for +-* and probably several other but I want
to make sure Monty is fine with my fix approach before changing a lot
of code. 

Amazingly,
this bug is not as critical as you would expect since very few functions do val_int()
on their arguments ( from_unixtime(), sec_to_time()), and those not
very frequently perform a computation on their floating point arguments.
which is probably why no one has yet reported this bug. Another 
possibility is that the result is usually wrong by no more than 5%,
which makes it hard to catch it. I found it when trying to compute mile
splits for 30:47 10K - it told me 5:07, and I knew it was wrong because
5:00 mile gives you 31:08. However, if I had not run as many 10K races,
I would have easily believed that 30:47 10K is a 5:07 mile pace and 
would not have noticed the bug.


mysql-test/r/func_time.result:
  another test for sec_to_time that exposes a long outstanding bug
mysql-test/t/func_time.test:
  another test for sec_to_time that exposes a long outstanding bug
sql/item_func.cc:
  fixed bug in Item_func_div::val_int()

1 files changed, 2 insertions, 1 deletions

diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index a91844ab986..cb021d25ae3 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -7,7 +7,8 @@ select from_days(to_days("960101")),to_days(960201)-to_days("19960101"),to_days(
 select period_add("9602",-12),period_diff(199505,"9404") ;
 select now()-now(),weekday(curdate())-weekday(now()),unix_timestamp()-unix_timestamp(now());
 select from_unixtime(unix_timestamp("1994-03-02 10:11:12")),from_unixtime(unix_timestamp("1994-03-02 10:11:12"),"%Y-%m-%d %h:%i:%s"),from_unixtime(unix_timestamp("1994-03-02 10:11:12"))+0;
-select sec_to_time(9001),sec_to_time(9001)+0,time_to_sec("15:12:22");
+select sec_to_time(9001),sec_to_time(9001)+0,time_to_sec("15:12:22"),
+  sec_to_time(time_to_sec("0:30:47")/6.21);
 select now()-curdate()*1000000-curtime();
 select strcmp(current_timestamp(),concat(current_date()," ",current_time()));
 select date_format("1997-01-02 03:04:05", "%M %W %D %Y %y %m %d %h %i %s %w");