Re: git-p4: default behavior for handling moves?

From: Mazo, Andrey <amazo@checkvideo.com>
Date: Jan 8, 2019, 00:56 UTC
Message-ID: <20190108005634.1647-1-amazo@checkvideo.com>
In-Reply-To: <CAE5ih7987J2WXdCJvs2e3hOn3zucpE6gsr4JJtxO+XE5=K2G_Q@mail.gmail.com>

Show 13 quoted lines

> git-p4 can map a "git move" operation to a Perforce "move" operation.
> But by default this is disabled. You then end up with a P4 commit
> where the file is deleted, and a fresh file is created with the same
> contents at the new location at revision #1.
> 
> Rename detection gets enabled either with the "-M" option, or with
> some config variables, git-p4.detectCopies and git-p4.detectRenames.
> 
> I've been tripped up by this, and I actually know about it, and I know
> other people have been as well.
> 
> Should we switch the default over so that it's enabled by default? I
> can't think of any reason why you wouldn't want it enabled.

I have it enabled in my ~/.gitconfig, so enabling it by default makes total sense to me.

Regarding potential problems, I occasionally get a wrong "source" file detection. (e.g. there was `cp a b ; git add b`, but some other file "c" is selected as the source instead) Or there is a "copy/move" detected, when there was actually none. But I've only seen this with quite small files (like a trivial one line shell script) or binaries, and mostly because I have git-p4.detectCopiesHarder set as well as a pretty aggressive git-p4.detectCopies threshold. (normally 30%, but down to 10% at times to make sure a copy/move is really detected)

But anyway, enabling both git-p4.detect{Copies,Renames} with default 50% similarity index makes sense to me.

It's probably worth adding command-line options to override the new to-be defaults though.

A more conservative approach like only enabling git-p4.detectRenames = 70% is an option too.

> 
> I think the rename code was first introduced around 2011 by Vitor.
> 
> Another option is to add a warning, but people just ignore warnings!

When such a warning would be shown? Just before `p4 submit`? I think, It might be hard to notice for large changesets.

Thank you, Andrey