[llvm-dev] [cfe-dev] Phabricator -> GitHub PRs?

Jonas Devlieghere via llvm-dev llvm-dev at lists.llvm.org
Tue Jan 7 19:08:43 PST 2020

On Tue, Jan 7, 2020 at 5:56 PM Bill Wendling <isanbard at gmail.com> wrote:
> On Tue, Jan 7, 2020 at 5:35 PM Jonas Devlieghere <jonas at devlieghere.com> wrote:
>> On Tue, Jan 7, 2020 at 5:16 PM Bill Wendling via cfe-dev
>> <cfe-dev at lists.llvm.org> wrote:
>> >
>> > On Tue, Jan 7, 2020 at 4:59 PM Doerfert, Johannes <jdoerfert at anl.gov> wrote:
>> >>
>> >> Hi Bill,
>> >>
>> >> On 01/07, Bill Wendling via llvm-dev wrote:
>> >> > Then perhaps those opposed could suggest how to use Phabricator/Arcanist so
>> >> > that I don't throw my keyboard through my monitor?
>> >>
>> >> Please explain your problems, w/o the hyperbole, so people can actually do that.
>> >>
>> > It's not hyperbole, but fine.  How do you use it to keep multiple, related changes in order?
>> You can use parent/child revisions. Phabricator encourages a
>> patches-based approach with small changes. For me that corresponds to
>> one commit per code review. When I address code review feedback in a
>> parent revision I use git's interactive rebase.
> What's your workflow for doing this? My current workflow is:
> $ vim ...
> $ git commit -a -m f
> $ git rebase -i
> <move the commit I want to upload to the top of the change list>
> $ arc diff --update <update ID> --head <sha1 of the commit>
> Of course, that doesn't work if the patch relies upon other patches. However, if I keep the patches in order in git, then arc will upload all of the parent changes to that Phab revision.

My workflow is similar, although I upload the patches manually through
the web interface. If it's a single patch I use an alias for `show
HEAD -U999999 ` which I then copy/paste in Phabricator. If I'm working
on a say a set of 3 changes and I need to update the oldest one, I use
git rebase -i HEAD~3 on the feature branch, edit the last commit and
use `git show -U999999 <sha>`. Most of the time I don't bother
updating the child revisions unless it really matters. I land the
changes from the commits (by cherry-picking them to master) rather
than the phabricator diffs and then rebase the feature branch.

>> > The interface for reviewing and responding to reviews is horrific, e.g. quoting text from a review is rather bad, the email it sends is badly formatted and hard to read. How do you make it reasonably useful?
>> Inline comments are super useful, they can be marked as done and
>> hidden. I agree that sometimes there's a lot of context when quoting
>> text, but the format is very simple (similar to e-mail) so it's easy
>> to trim.
> FWIW, the inline comments are fine, but I don't see a way to quote text easily.

Do you mean quoting text in inline comments? Non-inline comments you
can quote by using the dropdown at the top right of a comment and
selecting "Quote Comment" which just puts the plaintext in the form.
Like I said earlier I usually trim the history to keep things on

>> > Why can't I *easily* relate changes to each other?
>> What issues do you experience with parent/child revisions?
> It was difficult to find out how to do it. I would expect it to have suggested revisions in the list, but it didn't. It would also be nice to do it through the "arc" tool, but there's no option to do that.
I'm not sure how many open revisions you have, but the Edit Child
Revision window is pretty easy to use imho. If you upload the patches
one by one, the most recent one is always at the top. I also really
like the open stack view. It's much more explicit than mentioning one
PR in another.
>> > Why can't I submit through the Phabricator interface, but have to go to the command line, place the change in a new branch, pull to top-of-tree, rebase, and only then push while hoping it doesn't give fail because the tree became out of date? How can I do a rebase through Phabricator?
>> You can upload patches through
>> https://reviews.llvm.org/differential/diff/create/. I personally don't
>> use arcanist even though I found it pretty useful in the past.
> This is part of my issue. The arcanist tool is meant to be used with Phabricator, especially if you develop in a terminal, but people seem to actively avoid using it. I personally find it far too easy to push the wrong changes to a revision.

Like I said I don't use arcanist. I think it works great if you have a
one-off patch and know how to spell the name of your reviewers but
otherwise I prefer the web interface.

> -bw

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