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Re: [PATCH 4/5] rebase -i: don't fork git checkout

From
Philippe Blain <levraiphilippeblain@gmail.com>
Date
Sep 9, 2021, 12:40 UTC
Message-ID
<e7224105-83c6-7f12-f63a-474bd477583a@gmail.com>
In-Reply-To
<c42d4051-59cd-094a-4570-32cf4d38ec27@gmail.com>
Hi Phillip,
Le 2021-09-09 à 06:09, Phillip Wood a écrit :
Show 37 quoted lines
> Hi Philippe
> 
> On 08/09/2021 19:14, Philippe Blain wrote:
>> Hi Phillip,
>> 
>> Le 2021-09-08 à 09:41, Phillip Wood via GitGitGadget a écrit :
>>> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>>> 
>>> The "apply" based rebase has avoided forking git checkout since 
>>> ac7f467fef ("builtin/rebase: support running "git rebase
>>> <upstream>"", 2018-08-07). The code that handles the checkout was
>>> moved into libgit by b309a97108 ("reset: extract reset_head()
>>> from rebase", 2020-04-07) so lets start using it for the "merge"
>>> based rebase as well. This opens the way for us to stop calling
>>> the post-checkout hook in the future.
>>> 
>> 
>> While in general I think it's a good thing to avoid forking, this
>> change might result in behavioral differences. Any config that
>> affects 'git checkout' but not the internal 'reset.c::reset_head'
>> function might play a role in the rebase UX.
>> 
>> One that immediately came to mind is 'submodule.recurse'. This
>> initial 'onto' checkout was pretty much the only part of 'git
>> rebase' that did something useful for submodules, so it's kind of
>> sad to see it regress.
> 
> Thanks for pointing that out. As a non-submodule user my question
> would be is it actually useful for the initial checkout to work that
> way if the rest of rebase (and the checkout for the am backend)
> ignores submodules? reset.c::reset_head() just uses unpack trees like
> checkout so if rebase read 'submodule.recurse' then reset_head()
> would work like 'git checkout' and also 'git rebase --abort' and the
> "reset" command in the todo list would start checking out submodules.
> I'm reluctant to do that until the merge backend also handles
> submodules unless there is a good reason that such partial submodule
> support would help submodule users.

Yeah, it's not that useful, I have to admit; it can also be very confusing since some parts of rebase are affected, and some not. For example, any time the rebase stops, like for 'edit', 'break', and when there are conflicts, the submodules are not updated. So I think a full solution is better than a partial solution; in the meantime I'm thinking the change you are proposing would actually be less confusing, even if it slightly changes behaviour...

As an aside, I *think* reading submodule.recurse in rebase like it's done in checkout et al., i.e. something like this:

diff --git a/builtin/rebase.c b/builtin/rebase.c
index 33e0961900..125ec907e4 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -26,6 +26,7 @@
  #include "rerere.h"
  #include "branch.h"
  #include "sequencer.h"
+#include "submodule.h"
  #include "rebase-interactive.h"
  #include "reset.h"
  
@@ -1106,6 +1107,9 @@ static int rebase_config(const char *var, const char *value, void *data)
  		return git_config_string(&opts->default_backend, var, value);
  	}
  
+	if (!strcmp(var, "submodule.recurse"))
+		return git_default_submodule_config(var, value, data);
+
  	return git_default_config(var, value, data);
  }
  

would actually also affect the merges
performed during the rebase, since that would affect the "global" state in submodule.c.
I hacked exactly that the other day but did not test extensively...

Cheers,
Philippe.
Previous: Phillip WoodNext: Phillip Wood
Message 12 of 31 in “rebase -i: a couple of small improvements”
  1. 0/5 rebase -i: a couple of small improvementsPhillip Wood via GitGitGadget, Sep 8, 2021
  2. 1/5 sequencer.c: factor out a functionPhillip Wood via GitGitGadget, Sep 8, 2021
  3. Eric SunshineSep 8, 2021
  4. Phillip WoodSep 9, 2021
  5. Johannes SchindelinSep 9, 2021
  6. 2/5 rebase: fix todo-list rereadingPhillip Wood via GitGitGadget, Sep 8, 2021
  7. Johannes SchindelinSep 9, 2021
  8. 3/5 reset_head(): mark oid parameter as constPhillip Wood via GitGitGadget, Sep 8, 2021
  9. 4/5 rebase -i: don't fork git checkoutPhillip Wood via GitGitGadget, Sep 8, 2021
  10. Philippe BlainSep 8, 2021
  11. Phillip WoodSep 9, 2021
  12. Philippe BlainSep 9, 2021
  13. Phillip WoodSep 9, 2021
  14. Elijah NewrenSep 9, 2021
  15. Philippe BlainSep 10, 2021
  16. Phillip WoodSep 15, 2021
  17. Johannes SchindelinSep 9, 2021
  18. Philippe BlainSep 9, 2021
  19. Johannes SchindelinSep 9, 2021
  20. Johannes SchindelinSep 10, 2021
  21. Philippe BlainSep 10, 2021
  22. Elijah NewrenSep 9, 2021
  23. 5/5 rebase: remove unused parameterPhillip Wood via GitGitGadget, Sep 8, 2021
  24. Johannes SchindelinSep 9, 2021
  25. Phillip WoodSep 9, 2021
  26. 0/2 rebase -i: a couple of small improvementsPhillip Wood via GitGitGadget, Sep 23, 2021
  27. 2/2 rebase: fix todo-list rereadingPhillip Wood via GitGitGadget, Sep 23, 2021
  28. Junio C HamanoSep 24, 2021
  29. Phillip WoodSep 28, 2021
  30. 1/2 sequencer.c: factor out a functionPhillip Wood via GitGitGadget, Sep 23, 2021
  31. Junio C HamanoSep 24, 2021

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