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Re: -Wuninitialized issues


On Tuesday 01 November 2005 13:17, Jeffrey A Law wrote:

> Possibly a useful thing to have, but I don't think we want to put
> the burden of detecting uninitialized variables onto each
> optimizer :-)
>
Heh.  Indeed.

> I think false positives are inevitable if we attempt to solve the
> problems Mark is complaining about.  That's part of the reason why
> I think this needs to be switch controlled.
>
Agreed.

> Your example is probably derived from C code which looks something
> like this:
>
Yeah, it's gcc.dg/m-un-1.c, IIRC.

> Clearly the message could be better, but it's easy to see how this
> warning distinguishes itself from the "blah may be used uninitialized in
> this function" warning we give in other cases.  We clearly state that
> it appeared to be used uninitialized, but optimizations changed that
> assessment.
>
Sounds good.

We won't get perfect answers, which is fine given the nature of the 
problem.  However, I would like, to get *consistent* answers.  If we 
decide to re-organize the optimization pipeline, we should not be getting 
different -Wuninitialized behaviour.  Perhaps that's an easier problem to 
solve.  For instance, for GCC bootstraps we could ignore the warning when 
it's from "... but was later optimized away ...".


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