Subject: Re: [PATCH v9 2/3] introduce submodule.hasSuperproject record

From: Emily Shaffer <[email-masked]>
Date: Tue, 15 Mar 2022 13:48:25 -0700

On Thu, Mar 10, 2022 at 03:53:17PM -0800, Glen Choo wrote:
> 
> Glen Choo <[email-masked]> writes:
> 
> > Junio C Hamano <[email-masked]> writes:
> >
> >>> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> >>> index bef9ab22d4..f53808d995 100644
> >>> --- a/builtin/submodule--helper.c
> >>> +++ b/builtin/submodule--helper.c
> >>> @@ -2672,6 +2677,11 @@ static int run_update_procedure(int argc, const char **argv, const char *prefix)
> >>>                                             &update_data.update_strategy);
> >>>
> >>>         free(prefixed_path);
> >>> +       /*
> >>> +        * This entry point is always called from a submodule, so this is a
> >>> +        * good place to set a hint that this repo is a submodule.
> >>> +        */
> >>> +       git_config_set("submodule.hasSuperproject", "true");
> >>>         return update_submodule2(&update_data);
> >>>  }
> >>
> >> That matched my tentative resolution I made last night, but what do
> >> you think about this part of the test added by the patch?
> >>
> >> diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
> >> index 11cccbb333..ec2397fc69 100755
> >> --- a/t/t7406-submodule-update.sh
> >> +++ b/t/t7406-submodule-update.sh
> >> @@ -1061,4 +1061,12 @@ test_expect_success 'submodule update --quiet passes quietness to fetch with a s
> >>  	)
> >>  '
> >>  
> >> +test_expect_success 'submodule update adds submodule.hasSuperproject to older repos' '
> >> +	(cd super &&
> >> +	 test_unconfig submodule.hasSuperproject &&
> >> +	 git submodule update &&
> >> +	 test_cmp_config -C submodule true --type=bool submodule.hasSuperproject
> >> +	)
> >> +'
> >> +
> >>  test_done
> >>
> >> We go to "super", make sure that superproject does not have
> >> submodule.hasSuperproject set, run "git submodule update", and see
> >> if the configuration file in "submodule" subdirectory has the
> >> variable set.  It does not clear the variable from the submodule
> >> before starting, so the variable given to the submodule when it was
> >> cloned would be there, even if "git submodule update" failed to set
> >> it.
> >>
> >> I am wondering if it should do something like the attached instead.
> >>
> >> We
> >>
> >>  * clear the variable from "super" and "super/submodule"
> >>    repositories;
> >>
> >>  * run "git submodule update";
> >>
> >>  * ensure that "git submodule update" did not touch "super/.git/config";
> >>
> >>  * ensure that "git submodule update" added the variable to
> >>    "super/submodule/.git/config".
> >>
> >> Clearing the variable from "super" is technically wrong because the
> >> repository is set up as a submodule of "recursivesuper" and if we
> >> had further tests, we should restore it in "super", but the point is
> >> that we are makng sure "git submodule update" sets the variable in
> >> the configuration file of the submodule, and not in the superproject's. 
> >
> > Yes, the test you've described is closer to what I thought the original
> > test was trying to do. Seeing this test pass gave me a false sense of
> > confidence hm..
> 
> Correction, seeing the _original_ test pass gave me false sense of
> confidence.
> 
> >> With the conflict resolution above, this "corrected" test fails and
> >> shows that superproject's configuration file is updated after "git
> >> submodule update".
> >>
> >> This series alone, without your topic, this "corrected" test fails,
> >> and that is where my "are we sure we are mucking with the
> >> configuration file in the submodule"? comes from.
> > - Set the config in the submodule even though we are running from the
> >   superproject (this is possible, ensure_core_worktree() does this).
> 
> If it helps, I was able to do this up by copying
> ensure_core_worktree(), and this passes the amended test.
> 
> ----- >8 --------- >8 --------- >8 --------- >8 --------- >8 ----
> 
> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index 4d02dd05ca..3bb7a65762 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -1838,11 +1838,6 @@ static int clone_submodule(struct module_clone_data *clone_data)
>     git_config_set_in_file(p, "submodule.alternateErrorStrategy",
>               error_strategy);
> 
> -	/*
> -	 * Teach the submodule that it's a submodule.
> -	 */
> -	git_config_set_in_file(p, "submodule.hasSuperproject", "true");
> -
>   free(sm_alternate);
>   free(error_strategy);
> 
> @@ -2560,6 +2555,20 @@ static int update_clone(int argc, const char **argv, const char *prefix)
>   return update_submodules(&suc);
> }
> 
> +static void set_hassuperproject(const char *sm_path)
> +{
> +	struct repository subrepo;
> +	char *cfg_file;
> +
> +	if (repo_submodule_init(&subrepo, the_repository, sm_path, null_oid()))
> +		die(_("could not get a repository handle for submodule '%s'"), sm_path);

Isn't the repo_submodule_init() fairly expensive? I think this is doing
a whole repo_init() call we would not otherwise be doing.... Is it good
enough to generate the config from sm_path, by using
strbuf_repo_worktree_path(), and simply be tolerant of the failure if
<sm-gitdir>/config doesn't exist?

Otherwise, this is a good workaround I think. Thanks.

 - Emily