[Interest] OT: Bug-free code (Was: QtSVG deprecated)

[Atlant Schmidt]

Andreas:

> Ok, I shouldn't have said application when I really meant: 'this
> piece of code' :). The above function is bug-free, executing it
> in a buggy environment does not mean it suddenly has a bug.

  Do you *REALLY* know that? You might even know
  that your C(++) code doesn't have any bugs, but
  what you actually execute is machine language
  produced by your compiler toolchain (etc.).

  Unless you inspect the ultimate binary code
  while loaded in execution memory, how can you
  be sure?

  (Compiler/toolchain validation is a huge area
  of very serious discussion.)

  And, as another poster to the thread pointed out,
  it's only bug-free if it meets the specs. We
  haven't seen those ;-) !

                             Atlant

-----Original Message-----
From: interest-bounces+aschmidt=dekaresearch.com at qt-project.org [mailto:interest-bounces+aschmidt=dekaresearch.com at qt-project.org] On Behalf Of Andreas Pakulat
Sent: Thursday, January 12, 2012 11:19
To: interest at qt-project.org
Subject: Re: [Interest] OT: Bug-free code (Was: QtSVG deprecated)

On 12.01.12 08:50:47, Atlant Schmidt wrote:
> > > My over 20 years experience shows that there is no bug free software,
> > > there are bugs that either have not being found yet or just ignored.
> >
> > Well, one example of a bug-free application would be
> >
> > int main()
> > {
> >   return 0;
> > }
> >
> > Sure it does not do anything useful, but its pretty much bug-free. I
> > agree though that real-world applications always have bugs :)
>
>   This piece of code *MIGHT* be bug-free considered
>   in isolation, but in a real world runtime environment
>   with dynamic linking and fancy scheduling, I'm pretty
>   sure you could detect anomalies in the execution of
>   even this simple code if you tried hard enough.

Sure, the environment might be buggy, but that does not change the fact
that this piece of software can be considered bug-free.

>   For example, what if a new process can't be created
>   so the shell can't fork-and-exec this process? What
>   if the handling of Flash memory failures delay the
>   execution of this code? Are those anomalies? And
>   remember, there's commonly in-process code that
>   executes before main() is called.

Ok, I shouldn't have said application when I really meant: 'this piece
of code' :). The above function is bug-free, executing it in a
buggy environment does not mean it suddenly has a bug.

Andreas

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