Subject: Re: [PATCH] git-submodule.sh: shorten submodule SHA-1s using rev-parse

From: Junio C Hamano <[email-masked]>
Date: Tue, 22 Jan 2019 12:22:45 -0800

Sven van Haastregt <[email-masked]> writes:

> Until now, `git submodule summary` was always emitting 7-character
> SHA-1s that have a higher chance of being ambiguous for larger
> repositories.  Use `git rev-parse --short` instead, which will
> determine suitable short SHA-1 lengths.

In general I think it is a good idea to scale as the repository
grows by asking "rev-parse --short" to do the job.

One thing it is not clear to me is that this codepath is prepared to
handle sha1_src and sha1_dst referring to an object that does not
exist (i.e. $missing_(src|dst)=t); the original code will still give
us 7 hexdigit to show on the headline, but does the updated code
that uses "rev-parse --short" give us a reasonable output?

>
> Signed-off-by: Sven van Haastregt <[email-masked]>
> ---
>  git-submodule.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/git-submodule.sh b/git-submodule.sh
> index 5e608f8bad..a422b0728d 100755
> --- a/git-submodule.sh
> +++ b/git-submodule.sh
> @@ -850,8 +850,8 @@ cmd_summary() {
>  			;;
>  		esac
>  
> -		sha1_abbr_src=$(echo $sha1_src | cut -c1-7)
> -		sha1_abbr_dst=$(echo $sha1_dst | cut -c1-7)
> +		sha1_abbr_src=$(GIT_DIR="$name/.git" git rev-parse --short $sha1_src)
> +		sha1_abbr_dst=$(GIT_DIR="$name/.git" git rev-parse --short $sha1_dst)
>  		if test $status = T
>  		then
>  			blob="$(gettext "blob")"