[Qt-interest] SegFaults I cannot interpret

[Andrea Franceschini]

2009/2/24 Thiago Macieira <thiago.macieira at trolltech.com>:

> When you're out of other options, you can always resort to reducing your
> code until you can no longer reproduce the problem.

Actually I did that and both cases happened:
1. I got apparently rid of the problem without reducing that much the code
2. I still got the problem after a heavy strip down.

Let me point out that the simple non-existence of this problem is
quite hard to track because if it does exist, it may not show up at a
given time and if it doesn't exist, you'll never be sure.

> You'll also have a much smaller codebase which you can send to mailing
> lists and ask for help.

For any toy example I tried to construct, I never had the problem
again so I was simply forced to send all the source I knew was faulty.

> So, my guesses are:
> 1) Doodle::Painter::paint is accessing a QList object before it is
> initialised or after it was deleted

This is the reason for which I put mutexes around the regions that
accessed those objects, and it didn't change anything.
Is there any chance I can detect such a case from the code and behave
accordingly?

> 2) you've got a memory overrun somewhere and you're writing garbage to
> QList::d

Isn't this a thing that valgrind is supposed to tell me?

-- 
Andrea