Re: [PATCH 2/2] submodule: use submodule repository when preparing summary

[Derrick Stolee <stolee@gmail.com>]

On 6/23/2020 4:56 PM, Michael Forney wrote:
> In show_submodule_header(), we gather the left and right commits
> of the submodule repository, as well as the merge bases. However,
> prepare_submodule_summary() initializes the rev_info with the_repository,
> so we end up parsing the commit in the wrong repository.
> 
> This results in a fatal error in parse_commit_in_graph(), since the
> passed item does not belong to the repository's commit graph.
> 
> Signed-off-by: Michael Forney <mforney@mforney.org>
> ---
>  submodule.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/submodule.c b/submodule.c
> index e2ef5698c8..785ab47629 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -438,13 +438,13 @@ void handle_ignore_submodules_arg(struct diff_options *diffopt,
>  	 */
>  }
>  
> -static int prepare_submodule_summary(struct rev_info *rev, const char *path,
> -		struct commit *left, struct commit *right,
> +static int prepare_submodule_summary(struct repository *r, struct rev_info *rev,
> +		const char *path, struct commit *left, struct commit *right,
>  		struct commit_list *merge_bases)
>  {
>  	struct commit_list *list;
>  
> -	repo_init_revisions(the_repository, rev, NULL);
> +	repo_init_revisions(r, rev, NULL);

This is how we properly initialize the repository in the rev_info.
It's unfortunate that this use of the_repository was pretty clearly
incorrect. This is submodule.c, so every instance of the_repository
should be examined carefully. Taking a brief look right now, the
rest seem to be correct in that they are finding submodules within
the super-repo. The only issue will arise when recursing into
submodules, which is known to be broken in-process and are handled
with subprocesses instead.

>  	setup_revisions(0, NULL, rev, NULL);
>  	rev->left_right = 1;
>  	rev->first_parent_only = 1;
> @@ -632,7 +632,7 @@ void show_submodule_summary(struct diff_options *o, const char *path,
>  		goto out;
>  
>  	/* Treat revision walker failure the same as missing commits */
> -	if (prepare_submodule_summary(&rev, path, left, right, merge_bases)) {
> +	if (prepare_submodule_summary(sub, &rev, path, left, right, merge_bases)) {
>  		diff_emit_submodule_error(o, "(revision walker failed)\n");
>  		goto out;
>  	}

Perhaps the test I requested in patch 1 is only appropriate
here? Or, maybe the test should be test_expect_failure in the
first patch and switched to test_expect_success here?

Thanks,
-Stolee