[FFmpeg-devel] [RFC] Remove use of av_uninit

[Nicolas George]

Zhao Zhili (HE12025-04-11):
> Background:
> 
> 1. There is a av_uninit macro which suppress uninitialized variable warning
> 
> #if (defined(__GNUC__) || defined(__clang__)) && !defined(__INTEL_COMPILER)
> #    define av_uninit(x) x=x
> #else
> #    define av_uninit(x) x
> #endif

Yes.

> 2. Declaration after statement coding style is allowed now

I fail to see the connection. Oh, reading further, I guess you think
moving the declaration of the variable will be enough to let the
compiler know the variable is not used and silence the warning. I
strongly doubt it might have that effect.

> 3. There is a crash fixed by ab792634197 which is related to av_uninit, and I have confronted it again recently

So, what does it prove? It proves that 16 years ago (e658657528d) Diego
silenced a warning without making sure the logic itself was sound.

Which is exactly what you are proposing to do right now in a different
way.

> 1. Deprecated av_uninit and removed it in the future
> 
> 2. Remove usage in current code

Not before or without 3.

> 3. When there is uninitiated variable warning
> 
> a. Declare variable when need if it’s possible, so it can be initiated at the same time
> b. Use valid default value if there is
> c. If there is no valid default value, or you think the variable never being used uninitialized, assign an insane value and add assert before use if
> 
> av_assert1(value != invalid_value);

Are you volunteering to do that huge work?

Running FATE with valgrind and no optimization seems like a quicker way
of finding the real bugs.

Regards,

-- 
  Nicolas George