Subject: Re: [PATCH v2 2/3] diff --submodule=diff: do not fail on ever-initialied deleted submodules

From: Junio C Hamano <[email-masked]>
Date: Mon, 30 Aug 2021 23:19:11 -0700

David Turner <[email-masked]> writes:

> If you have ever initialized a submodule, open_submodule will open it.
> If you then delete the submodule's worktree directory (but don't
> remove it from .gitmodules), git diff --submodule=diff would error out
> as it attempted to chdir into the now-deleted working tree directory.
>
> Instead, we chdir into the submodule's git directory and run the diff
> from there.
>
> Signed-off-by: David Turner <[email-masked]>
> ---
>  submodule.c                                  |  10 ++
>  t/t4060-diff-submodule-option-diff-format.sh | 157 +++++++++++++++++++++++++--
>  2 files changed, 160 insertions(+), 7 deletions(-)
>
> diff --git a/submodule.c b/submodule.c
> index 0b1d9c1dde..d13d103975 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -710,6 +710,16 @@ void show_submodule_inline_diff(struct diff_options *o, const char *path,
>  		strvec_push(&cp.args, oid_to_hex(new_oid));
>  
>  	prepare_submodule_repo_env(&cp.env_array);
> +
> +	if (!is_directory(path)) {
> +		// fall back to absorbed git dir, if any

I'll locally amend this comment style.  If there is no other
comments, that would be sufficient.

> +		if (!sub)
> +			goto done;
> +		cp.dir = sub->gitdir;
> +		strvec_push(&cp.env_array, GIT_DIR_ENVIRONMENT "=.");
> +		strvec_push(&cp.env_array, GIT_WORK_TREE_ENVIRONMENT "=.");
> +	}
> +
>  	if (start_command(&cp))
>  		diff_emit_submodule_error(o, "(diff failed)\n");