Re: Segfault in master due to 4fbcca4eff

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Fri, Sep 21 2018, Jeff King wrote:

> On Sat, Sep 22, 2018 at 01:37:17AM +0200, Ævar Arnfjörð Bjarmason wrote:
>
>> > Thanks, both of you ;-).  I was aware of the issue and proposed fix
>> > but forgot about it when merging things down to 'master'.  Sorry
>> > about that.
>> 
>> Just a follow-up question, in your merge commit you just pushed to
>> "next" you say:
>> 
>>     Recent update broke the reachability algorithm when tags pointing
>>     at objects that are not commit were involved, which has been fixed.
>> 
>> And in Derrick's commit message it says:
>> 
>>     [...]but incorrectly assumed that all objects provided were commits[...]
>> 
>> I just wanted to double check (without having the time to dig myself at
>> this point) whether this bug was understood & tested for, or whether the
>> case I had was just /also/ fixed for unexpected reasons.
>> 
>> I.e. in my upthread test case I have two annotated tags pointing at
>> commits, whereas the merge to "next" says "when tags pointing at objects
>> that are not commit were involved", which I I assume means say annotated
>> tags pointing at blobs..., but that's not what I had.
>> 
>> Wasn't this just a bug fix that had nothing to do with tags not pointing
>> to commits, but just ones where we had the simple case of tags pointing
>> to commits, but they just weren't peeled?
>> 
>> I'm hoping for a "Junio skimmed the fix and wrote a merge message that
>> wasn't quite accurate" here, but maybe that's not the case and something
>> might be missing (e.g. missing test code).
>
> I think it's a combination of the merge message being slightly
> inaccurate, and you slightly misreading it. :)
>
> I think by "tags pointing", Junio meant "tag refs". Which of course,
> often point at tag objects, but can also point at trees, etc.
>
> But the problem is not limited to tag refs. I think it's a problem with
> any "want" that is a non-commit. So really any ref pointing to a
> non-commit is a problem. But of course tags are the likely way for that
> to happen, since refs/heads is generally limited to commits.
>
> So in short, yeah, the bug was triggered by fetching any annotated tag.

Thanks for clearing that up.