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From: Glen Choo <chooglen@google.com>
To: Philippe Blain <levraiphilippeblain@gmail.com>,
	Glen Choo via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: Huang Zou <huang.zou@schrodinger.com>,
	Josh Steadmon <steadmon@google.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH] pull: only pass '--recurse-submodules' to subcommands
Date: Tue, 10 May 2022 11:43:51 -0700	[thread overview]
Message-ID: <kl6lzgjp6xeg.fsf@chooglen-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <3234941c-5190-819f-fe3a-f528942c6b44@gmail.com>

Philippe Blain <levraiphilippeblain@gmail.com> writes:

> Hi Glen,
>
> Le 2022-05-09 à 19:27, Glen Choo via GitGitGadget a écrit :
>> From: Glen Choo <chooglen@google.com>
>
> First, regarding the commit message title (I never know where to comment
> on that since I can't quote it :P)
>
>> Re: [PATCH] pull: only pass '--recurse-submodules' to subcommands
>
> I understand the intent, i.e. "only pass the CLI flag, not any config, to subcommands"
> but only because I already know what the patch is about. It could be
> read to mean "pass --recurse-submodules only to subcommands, and not to 
> something else". Since this is really a bug that affects the underlying 
> 'git fetch', maybe something like this ?
>
>     pull: pass '--recurse-submodules' to 'fetch' from CLI, not config
>
>> 
>> Fix a bug in "git pull" where `submodule.recurse` is preferred over
>> `fetch.recurseSubmodules` 
>
> here I would add "for the underlying 'git fetch'"
>
> (Documentation/config/fetch.txt says that
>> `fetch.recurseSubmodules` should be preferred.). Do this by passing the
>> value of the "--recurse-submodules" CLI option to the underlying fetch,
>> instead of passing a value that combines the CLI option and config
>> variables.
>> 
>> In other words, this bug occurred because builtin/pull.c is conflating
>> two similar-sounding, but different concepts:
>> 
>> - Whether "git pull" itself should care about submodules e.g. whether it
>>   should update the submodule worktrees after performing a merge.
>
> nit: "or rebase".
>
>> - The value of "--recurse-submodules" to pass to the underlying "git
>>   fetch".
>> 
>> Thus, when `submodule.recurse` is set, the underlying "git fetch" gets
>> invoked with "--recurse-submodules", overriding the value of
>> `fetch.recurseSubmodules`.
>
> the wording is a litlle bit misleading here, as submodule.recurse could
> be set to 'false', and then 'git fetch' will be invoked with '--recurse-submodules=false'.

Thanks for the wording suggestions :) I'll see what I can incorporate.
 
>> An alternative (and more obvious) approach to fix the bug would be to
>> teach "git pull" to understand `fetch.recurseSubmodules`, but the
>> proposed solution works better because:
>> 
>> - We don't maintain two identical config-parsing implementions in "git
>>   pull" and "git fetch".
>> - It works better with other commands invoked by "git pull" e.g. "git
>>   merge" won't accidentally respect `fetch.recurseSubmodules`.
>
> I'm not sure of the meaning of the second bullet, since "git merge" should
> never perform a fetch ?... 

Ah, I'm describing a hypothetical issue with the 'obvious' (aka a
literal reading of the docs) approach of teaching "git pull" to handle
`fetch.recurseSubmodules`.

You are correct, "git merge" should never perform a fetch, so it
shouldn't care about `fetch.recurseSubmodules`. But a careless 'fix'
might be to copy what "git fetch" does with its config, e.g.


	if (!strcmp(k, "submodule.recurse")) {
		int r = git_config_bool(k, v) ?
			RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
		recurse_submodules = r;
	} else if (!strcmp(k, "fetch.recursesubmodules")) {
		recurse_submodules = parse_fetch_recurse_submodules_arg(k, v);
		return 0;
	}

which might make the internal "git merge" suddenly recurse into
submodules. Of course, this can be fixed by using a fetch-specific
variable, like:

	if (!strcmp(k, "submodule.recurse")) {
		int r = git_config_bool(k, v) ?
			RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
		recurse_submodules = r;
	}
  if (!strcmp(k, "fetch.recursesubmodules")) {
		fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(k, v);
		return 0;
	}

  static int run_fetch(const char *repo, const char **refspecs)
  {
    /* ... */
    if (fetch_recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
       /* This is actually wrong wrt the docs, but assume that we could
       combine the two values here correctly. */
       recurse_submodules = fetch_recurse_submodules;
    if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
      switch (recurse_submodules) {
  }

but then we'd have to add more variables if we have
`merge.recurseSubmodules`, or `rebase.recurseSubmodules` etc.

So the easiest way is to just tell "git pull" to stop assuming that it
knows what the subcommands want :)

  parent reply	other threads:[~2022-05-10 18:43 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-09 23:27 Glen Choo via GitGitGadget
2022-05-10  0:09 ` Junio C Hamano
2022-05-10  0:44 ` Junio C Hamano
2022-05-10 13:28 ` Philippe Blain
2022-05-10 18:27   ` Glen Choo
2022-05-10 18:43   ` Glen Choo [this message]
2022-05-10 19:25 ` [PATCH v2] " Glen Choo via GitGitGadget
2022-05-11 22:30   ` Philippe Blain
2022-05-11 22:34     ` Junio C Hamano
2022-05-11 22:35       ` Philippe Blain
2022-05-11 23:21         ` Glen Choo
2022-05-12 20:37           ` Junio C Hamano
2022-05-11 23:42   ` [PATCH v3] pull: do not let submodule.recurse override fetch.recurseSubmodules Glen Choo via GitGitGadget
2022-05-12 20:38     ` Junio C Hamano
2022-05-12 23:35       ` Philippe Blain

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