Bugs that aren't bugs!

[+Andrew Davie]

I just spent, literally, a whole day trying to track down an obscure bug. I have some parallax stuff going on, and have been developing in emulators and on hardware. But on the hardware I've mostly been using my trusty NTSC console. Well, I switched to the PAL console as I thought I should test... and the parallax stuff wasn't happening. Just blank. I couldn't understand it, and have just about run out of options/things to check, fiddling with the code, doing all sorts of stuff. Nada. Then I suddenly realised that when I started this project I put the option of turning parallax on/off on the right difficulty switch.  Doh!  Yep, the switch was configured differently on my NTSC/PAL units.  I might move it from a switch to a menu option.

Easiest bug-fix ever - flick a switch.

 

[CapitanClassic]

The most frustrating bugs are the works-on-my-machine variety. I always feel so stupid when it turns out the bug I’m looking for isn’t even there, because I am not running the same version of source code.

[+Andrew Davie]

My latest effort was one that worked on all machines tested except for @Albert's

I'm (slowly) learning to do git checkin/push very very frequently, because if you introduce a showstopper bug you just can't find, you can use git's "bisect" to do a binary search and find exactly what bit of code change you did to cause the bug.  git bisect is the most awesome "desperate" bug-searching tool ever.

 

[+Karl G]

Yup; I've also spent lots of time before trying to debug code that was working as I originally intended it to, so I feel your pain. 

 

27 minutes ago, Andrew Davie said:

you can use git's "bisect" to do a binary search and find exactly what bit of code change you did to cause the bug.  git bisect is the most awesome "desperate" bug-searching tool ever.

Oh, I wasn't aware of this one. Binary search, but for broken code.  Brilliant!

[+Gemintronic]

More than a few years ago I had a 2600 contract for a game based off of an indie movie.  Somehow I was doing some pretty good work.  Even the high res title screen I made looked like it was done by someone who actually, er, does graphic art.

 

Trouble came around release candidate time.  Client kept asking me to adjust the high res title screen.  He would always get some pixels out of place.  Tried shifting around the code and re-re-re-checked on all the systems available at home.  Couldn't reproduce nor find a solution.

 

Turns out his 7800 had some flaky RAM.  Gave me  an excuse to test everything else more thoroughly so it ended up a win.