[GHC DevOps Group] CircleCI job accounting question

[Ben Gamari]

Simon Marlow <marlowsd at gmail.com> writes:

> On 22 November 2017 at 15:31, Ben Gamari <ben at well-typed.com> wrote:
>
>> Manuel M T Chakravarty <manuel.chakravarty at tweag.io> writes:
>> > Why do we need the intermediate builds exactly? Wouldn’t they usually
>> > fail? (When I do PRs with multiple commits, the state of the tree
>> > between this commits will usually not be well-defined.)
>>
>> No, every commit should build. This is in part a difference between
>> Phabricator's patch-based model and GitHub's feature branch model.
>> However, many projects using the latter also demand that all
>> intermediate commits must be atomic, buildable changes. Sacrificing this
>> property greatly complicates bisection.
>>
>> Building all intermediates is desireable as ultimately we would like to
>> preserve per-commit build artifacts for the last few months of commits
>> to enable easy bisection.
>>
>
> I don't quite understand this. Yes building all commits is desirable, but
> in the case of Phabricator each revision is going to be a single commit,
> no? So why is this an issue? Or is it an issue only for github PRs?

The problem is that many contributors, including Simon PJ, Richard, and
me, tend to push batches of work. For instance, when I land
contributors' differentials I first apply a batch, then validate
locally, and then push as a chunk. We can change this if necessary, but
it will need to be via social convention which hasn't worked very well
historically.

> I thought we had decided (somewhere, I forget where) that we were going to
> require PRs to be squashed before pushing?
>
Please correct me if I'm forgetting something but I do not believe we
have even decided that we would start accepting PRs for larger patches.
I had said during ICFP that I was open to the idea, but experience
with GitHub's reviewing tools has since led me to view the proposal with
a bit more skepticism. Since this was prior to the creation of this
mailing list I summarised these concerns in a private email to Manuel; I
will forward this message to the list in a moment.

Cheers,

- Ben

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