[FFmpeg-devel] [PATCH/RFC] Constify src in av_fifo_generic_write()

Tomas Härdin tomas.hardin
Tue Feb 23 13:41:49 CET 2010

On Tue, 2010-02-23 at 13:14 +0100, Michael Niedermayer wrote:
> On Tue, Feb 23, 2010 at 10:50:03AM +0100, Tomas H?rdin wrote:
> > Good morning
> > 
> > This is a rather simple patch that merely makes av_fifo_generic_write()
> > take const void *src instead of just void *src. It causes no warnings
> > and regression tests pass.
> > 
> > The reason is simple: guarantee the user that the function does not
> > modify src.
> > 
> > One small issue though: this necessitated changing func to int(*)(const
> > void*,void*,int), which is OK for all code within FFmpeg. However, this
> > seems to count as a minor API change since g++ (and gcc I presume) won't
> > allow implicitly casting int(*)(void*,void*,int) to int(*)(const
> > void*,void*,int). I presume that part requires a bit of discussion,
> > which is why I marked this thread "RFC".
> > 
> > Patch attached.
> ive added a comment explaining why src cannot be const as you are at
> least the 2nd person trying to introduce this bug

Ah, ok. Might I suggest that you put a comment in fifo.h? That way users
can see it too (especially if only the headers are installed), and there
is less chance anyone else gets confused about this :o


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