[Python-Dev] Compiler warnings

Sjoerd Mullender sjoerd at acm.org
Wed Feb 1 11:34:00 CET 2006

Thomas Wouters wrote:
> On Tue, Jan 31, 2006 at 08:16:21PM -0500, Tim Peters wrote:
>>Is this version of gcc broken in some way relative to other gcc versions,
>>or newer, or ... ?  We certainly don't want to see warnings under gcc,
>>since it's heavily used, but I'm not clear on why other versions of gcc
>>aren't producing these warnings (or are they, and people have been
>>ignoring that?).
> Well, I said 4.0.3, and that was wrong. It's actually a pre-release of 4.0.3
> (in Debian's 'unstable' distribution.) However, 4.0.2 (the actual release)
> behaves the same way. The normal make process shows quite a lot of output on
> systems that use gcc, so I wouldn't be surprised if people did ignore it,
> for the most part.
> My main problem with fixing the warnings is that I don't see the difference
> between, for example, the 'ssize' variable and the 'nchannels' variable in
> linuxaudio's lad_obuffree/lad_bufsize/lad_obufcount. 'ssize' gets a warning,
> 'nchannels' doesn't, yet how they are treated is not particularly different.
> The ssize output parameter gets set inside a switch, is directly followed by
> a break, and the switch is directly followed by a set of the nchannels
> output parameter. The only way through the switch is through the set of
> ssize. I understand the compiler doesn't "see" it this way, but who knows
> for how long :)
> I guess we ignore this until we're closer to a 2.5alpha1 ;P

I don't quite understand what's the big deal.  The compiler issues a
warning.  We know better (and I agree, we *do* know better in most of
these cases), but it's easy to add a "= 0" to the declaration of the
variable to shut up the compiler, hopefully with a comment saying as
much.  That's what I've been doing in my code that generated these
warnings.  It's clearly a "bug" in the compiler that it isn't smart
enough to figure out that variable do actually only get used after
they've been set.  Hence, this is Somebody Else's Problem.

Sjoerd Mullender
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