Re: [PATCH 1/3] docs: explain why squash merges are broken with long-running branches

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Sep 13, 2020, 17:12 UTC
Message-ID: <20200913171206.GO241078@camp.crustytoothpaste.net>
In-Reply-To: <CAN0heSo8XsToRm1st4PqPp8PNwc98Csx-+o78J-mh3bbYoneWQ@mail.gmail.com>

On 2020-09-13 at 15:05:31, Martin Ågren wrote:

Show 11 quoted lines

> On Sat, 12 Sep 2020 at 22:52, brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
> >
> > In many projects, squash merges are commonly used, primarily to keep a
> > tidy history in the face of developers who do not use logically
> > independent, bisectable commits.  As common as this is, this tends to
> > cause significant problems when squash merges are used to merge
> > long-running branches due to the lack of any new merge bases.  Even very
> > experienced developers may make this mistakes, so let's add a FAQ entry
> 
> s/mistakes/mistake/

Will fix.

Show 12 quoted lines

> Very well-written, as always.
> 
> I grepped around a little and couldn't find that we're using this "long-
> running branch" notion anywhere. I think it might make sense to
> define/explain that somewhere early, e.g., with something like "...
> merged repeatedly ... more development...".
> 
> So in particular, a "long-running" branch is not something like
> 
>   I branched off a long time ago, I've been hacking on this feature for
>   a long time and the branch has run quite long with lots of commits.
>   Now it's time to merge it and be done with it!

Correct. By "long-running branch", I mean a branch into which code routinely gets integrated from feature branches. For example, the branches master and develop in a Git Flow workflow, or per-version release branches if you use that workflow. I didn't mean an otherwise divergent branch which has persisted for a long time.

The problem happens, essentially, if you have two branches and you merge one of them into another repeatedly with squash merges, so I'll be sure to make that clear. That will probably help with intelligibility for non-native speakers as well.

> Once that piece of background is in place, what you have here reads very
> well to me. It was only somewhere halfway through the second paragraph
> that I got what you meant by "long-running branch".

Thanks, this is helpful feedback.

-- 
brian m. carlson: Houston, Texas, US