Re: [PATCH 4/7] log: add --rename-notes to correct renames per commit

From: Duy Nguyen <pclouds@gmail.com>
Date: Jan 22, 2016, 01:00 UTC
Message-ID: <CACsJy8BZtr_2e-LyGpdQ52R1TBDL7x3ZZQPu+G3-tphBfrmAaw@mail.gmail.com>
In-Reply-To: <xmqqoacf3k3v.fsf@gitster.mtv.corp.google.com>

On Thu, Jan 21, 2016 at 6:29 AM, Junio C Hamano <gitster@pobox.com> wrote:

Show 10 quoted lines

> Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:
>
>> For simplicity, the note of commit A implies rename correction between
>> A^ and A. If parents are manipulated (e.g. "git log --reflog") then
>> the rename output may surprise people.
>
> I do not think "git log --reflog" attempts to show changes to bring
> the tree of @{2} into the shape of @{1}, even though for traversal
> purposes it pretends as if @{1}'s parent is @{2}.  So I am not sure
> what you are trying to say in the above sentence.

Hazy memory about hierarchy manipulation by reflog, maybe I'm wrong.

Show 12 quoted lines

> A path limited "git log -- path1/ path2/..." also manipulates the
> commit->parents for traversal purposes, but I think the patch is
> still produced against the true parents (there is a call to
> get_saved_parents() in log_tree_diff() that shows the change for a
> given commit), and in that context, commit A that has notes about
> the change to bring the tree of commit A^ to its tree still makes
> sense.
>
> I'd be more worried about "git log -m -p"--the diff against the
> second and subsequent parents would not want to use the notes that
> describes the change between the first parent and the resulting
> merge.

I "fix" this by providing the tools and let the user go wild. The line "A => B" says rename A to B for a diff between any source or target. But they can also say rename A to B only if diff source is X, or diff target is Y, or both. The syntax I'm having for that is something like this

.source X # X can be anything that resolves to a tree SHA-1 with get_sha1() .target Y A => B

-- 
Duy