[cfe-commits] [PATCH] Fix random crasher

[Richard Smith]

On Wed, Jul 18, 2012 at 4:51 PM, Richard Smith <richard at metafoo.co.uk>wrote:

> On Wed, Jul 18, 2012 at 3:55 PM, Robinson, Paul <Paul.Robinson at am.sony.com
> > wrote:
>
>> Guard use of a possibly uninitialized field.
>>
>> This was causing very unpredictable compiler crashes. I have not
>> provided a test because even our most reliable reproducer still failed
>> less than 10% of the time.
>>
>> I really really really don't like sometimes-uninitialized fields
>> guarded by flags. It is not a robust practice and took us a couple of
>> weeks of poking at it to find the root cause. But it is how the rest
>> of SemaOverload handles this field, so we fixed it using the
>> prevailing practice in the module.
>>
>
> Do you know where the uninitialized OverloadCandidate is coming from? The
> only place I can see one being created is in
> OverloadCandidateSet::addCandidate, which says:
>
>       Candidates.push_back(OverloadCandidate());
>
> This zero-initializes the OverloadCandidate object.
>

I've checked in a variant on your change in r160470: it seems correct and
appropriate even if FailureKind is always initialized, since we were
previously implicitly and accidentally relying on ovl_fail_bad_deduction
being nonzero.
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