[FFmpeg-devel] [PATCH] make sure initialization happens even after goto fires

[Erik Hovland]

On Thu, Jul 17, 2008 at 05:57:04PM +0100, M?ns Rullg?rd wrote:
> 
> Erik Hovland wrote:
> > The goto in ff_h264_find_frame_end() is inside an else clause. The
> > initialization for v happens in the if clause elsewhere. That means that
> > it is possible for the goto to fire without the initialization of v
> > happening. Normally this isn't a problem. But gcc recognizes this and
> > throws an internal parse warning. It then has to go through a special
> > code branch to take care of this. If the initialization of v always
> > happens before either clause this does not happen. The attached patch
> > does just that.
> 
> The gcc internals are irrelevant.  Only two things matter: 1) whether
> it is valid C code, and 2) whether gcc issues a warning.  As far as
> I can tell, it is valid C.  The question is thus, does it trigger a
> warning with gcc?

It triggers a warning with gcc that the user never sees. I do
agree. It is valid C. But it is playing a bit loose with its validity.

A static analysis tool can see the warning because it can see what gcc
emits. There are a few parse warnings that are valid C, but are a bit
iffy. This happens to be one of them. Parameter hiding is another
example.

But hey, the reason I post these patches is to get this kind of
feedback.

E

-- 
Erik Hovland
mail: erik at hovland.org
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