Re: Diffing submodule does not yield complete logs for merge commits

[Robert Dailey <rcdailey.lists@gmail.com>]

On Mon, May 4, 2015 at 2:32 PM, Jens Lehmann <Jens.Lehmann@web.de> wrote:
> Am 04.05.2015 um 17:05 schrieb Robert Dailey:
>>
>> On Fri, May 1, 2015 at 12:57 PM, Heiko Voigt <hvoigt@hvoigt.net> wrote:
>>>
>>> Hi,
>>>
>>> On Wed, Apr 29, 2015 at 03:53:11PM -0500, Robert Dailey wrote:
>>>>
>>>> I am attempting to diff a submodule modified in my working copy and
>>>> the only difference is a merge commit. However, I do not get the
>>>> "full" range of commits introduced by the merge commit when I diff it:
>>>>
>>>> $ git diff --submodule=log Core
>>>> Submodule Core 8b4ec60..def2f3b:
>>>>    > Merge remote-tracking branch 'origin/master-ah3k'
>>>>
>>>> However if I go inside my submodule and run `git log` by hand, I get
>>>> more information about the TRUE commits introduced:
>>>>
>>>> $ git log --oneline 8b4ec60..def2f3b
>>>> def2f3b Merge remote-tracking branch 'origin/master-ah3k'
>>>> 015c961 Remove log spam in FontManager
>>>> 7713ba1 Update third party submodule to latest
>>>> 10aac78 Merge pull request #9 in FE/core from
>>>> feature/FE-1348-selecting-continue-on-zero-balance to master-ah3k
>>>> 287882f FE-1376 Nedd to remain in check detail screen when selecting
>>>> donation after SBI
>>>> a5a6bed Do not overwrite the current check# within loop
>>>> dfb8547 Adding list of checks to CRspChecks before saving
>>>> 1be280a FE-1354: Guest logged out in specific multiple check scenario
>>>> de06d5a [FE-1348] Fix PATT exit while checks still open
>>>>
>>>> It's almost as if the `git diff --submodule=log` approach is passing
>>>> in --first-parent to git log, which would exclude commits in the range
>>>> that I'm seeing when I run git log manually.
>>>
>>>
>>> That is exactly the case. In prepare_submodule_summary() that option is
>>> set before doing the revision walk.
>>>
>>>> Is this by design? Is there a way to enable the full log history with
>>>> `git diff` on a submodule?
>>>
>>>
>>> This stems from the first implementation for showing submodule diffs in
>>> commit 752c0c24. I guess this was done deliberately to limit the amount
>>> of output you get for a submodule. At the moment this is hardcoded but I
>>> think there is nothing wrong with adding another option to include the
>>> full log.
>>>
>>> Cheers Heiko
>>
>>
>> I will go ahead and work on this feature. Here is what I'd like to see:
>>
>> 1. `git diff --submodule` should have the ability to display full logs
>> vs current logs (i.e. without --first-parent)
>
>
> I agree. Just recently I started missing that feature too at $DAYJOB.
>
>> 2. `git submodule summary` should have an option to display full logs
>> or "first-parent" logs.
>
>
> No objection against that. Maybe now is a good time to make `git
> submodule summary` use `git diff --submodule` internally to make
> them behave the same?
>
>> For #1, do you recommend adding a 3rd setting for `diff.submodule`
>> config? Something like "full-log" or something? Or an entirely new
>> config?
>
>
> I'd go with a 3rd setting for diff.submodule (and "full-log" would
> have been my first choice too ;-).
>
>> I noticed that in diff.h, the DIFF_OPT flags already consume
>>
>> 31 bits. If this is a 32-bit flag, there is only 1 bit left. If we go
>> with a 3rd setting for `diff.submodule` I think this might consume the
>> last bit.
>
>
> Yup. But I'm not sure we can do anything about it.
>
>> We could also make `git diff --submodule` default to the "full log"
>> type, and if users want only first parent logs in submodule summary,
>> they'd have to execute `git submodule summary` instead.
>
>
> Please do not change defaults that people lived fine with for years
> lightly. But I won't object changing that on a major version if a
> majority of users request that.

Since I am not a linux user, I have implemented this feature against
the Git for Windows fork of git. I am not able to verify changes if I
make them directly against the Git repository. Is it OK if you guys
end up getting this as an upstream patch later from that project? Also
I am not familiar with the bash unit tests, I will need help with
that.