[FFmpeg-devel] [PATCH] Fix MSVC warnings about possible value truncation.

wm4 nfxjfg at googlemail.com
Wed Sep 3 02:10:05 CEST 2014

On Tue, 2 Sep 2014 16:57:02 -0700
Peter Kasting <pkasting at google.com> wrote:

> On Tue, Sep 2, 2014 at 4:46 PM, wm4 <nfxjfg at googlemail.com> wrote:
> > > I tried not to "just plaster things with casts", but as I said, I was
> > > counting on review feedback to help me understand where changes would be
> > > fixing real problems or hiding real problems, as opposed to just
> > silencing
> > > warnings.  The ultimate goal, of both this patch and of enabling these
> > > sorts of warnings in general, is to find and fix the real problems, hide
> > no
> > > problems, and hopefully not cost too much in terms of additional code
> > noise
> > > to "silence" non-problem cases.
> >
> > That is perfectly fine. I just wanted to express my opinion that
> > silencing compiler warnings for the sake of silencing compiler warnings
> > by adding casts is not a good idea. (And in general, compiler warnings
> > that produce large amounts of false positives are a bad idea, because
> > they just drain developer time, or encourage bad practices.)
> I fully agree on all counts.
> In the end, if we do decide to enable this warning, we will have to insert
> some casts that are clearly safe, e.g.
>   if (x > INT_MAX)
>     return;
>   int y = (int)x;
> Indeed, if all of the nontrivial issues are fixed, those sorts of casts are
> presumably the majority of the trivial changes we'd have to introduce.

And here is exactly where we disagree.

(And at this point I'm also just speaking for myself - other FFmpeg devs
are invited to state their opinion.)

> However, on reaching that point, I'll be able to more clearly say, "here
> are the patches needed to enable this warning, and here are the functional
> code changes we made based on what this warning originally pointed out",
> and it will be clearer what the cost/benefit ratio is.
> Thanks again for the time you took to review, I appreciate it very much.
> PK
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