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Subject: Re: [PATCH] rebase --autosquash: fix a potential segfault
To:     Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc:     Andrei Rybak <rybak.a.v@gmail.com>,
        Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
        git@vger.kernel.org, Paul Ganssle <paul@ganssle.io>,
        Jeff King <peff@peff.net>
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From:   Philip Oakley <philipoakley@iee.email>
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Date:   Mon, 25 May 2020 18:29:47 +0100
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Hi Dscho,

On 18/05/2020 04:27, Johannes Schindelin wrote:
> Hi Philip,
>
> On Mon, 18 May 2020, Philip Oakley wrote:
>
>> On 08/05/2020 17:57, Andrei Rybak wrote:
>>> On 2020-05-08 18:43, Philip Oakley wrote:
>>>> On 07/05/2020 15:27, Johannes Schindelin wrote:
>>>> Is this ability to have a commit message `fixup! <commit-hash>` documented?
>>>> I've looked a few times in the past and didn't find it. The docs for
>>>> `git commit --fixup=` doesn't put the oid in the commit's subject line,
>>>> rather it puts the subject of the referent commit after the "fixup! ".
>>>>
>>>> Searching from a different direction I've just seen it is mentioned in
>>>> the v1.7.4 release notes.
>>>>
>>>> Would a doc fix to clarify this be appropriate or have I missed something?
>>>>
>>>> Philip
>>> Yes, it's documented in description of --autosquash: "A commit matches the `...`
>>> if the commit subject matches, or if the `...` refers to the commit's hash."
>> The docs don't  clarify if a full oid has is required, or a unique
>> abbreviation within the repository, or just unique within the rebase
>> instruction sheet.
> It's even worse: _any_ valid reference will do. As you can see from
> https://github.com/git/git/blob/efcab5b7a3d2/sequencer.c#L5359-L5381, the
> search goes like this:
>
>   - For the remainder of the `fixup! <remainder>` line:
>
> 	1. If it is identical to the oneline of any commit mentioned in a
> 	   previously-seen `pick` line, pick that as target.
>
> 	2. Otherwise, if the remainder can be looked up as a commit
> 	   (think: `fixup! master~3`) _and_ that commit was mentioned in
> 	   a previously-seen `pick` line, pick that as target.
>
> 	3. If all else fails, and if the remainder is the _start_ of a
> 	   oneline of a commit previously seen in a `pick` line, pick that
> 	   as target (if multiple lines match, use the first one).
>
> Do feel free to put that into a native-speaker form of a patch to improve
> the documentation.
>
>
Sorry for the delay on a reply to this one.  I do have a small couple of
patches to slightly improve the docs. Hope to send soon.

I'm thinking that for the longer term it may need a section covering
fixup/squash, so as to cover all the different user interaction stages,
e.g. the commit options, and commit message; and then the initial
interactive instruction sheet, and on-going edits of the instruction
sheet when the rebase pauses.

In particular, the (assuming proper understanding) the interjection
between the almost identical 1 & 3  [identical vs start of the oneline
of a commit in the `pick` (insn) list...], of the ability to specify an
almost arbitrary rev. I still have to check the code to see what it
does/tries to do.

Philip