Subject: Re: [PATCH 3/4] completion: reflog with implicit "show"

From: Junio C Hamano <[email-masked]>
Date: Fri, 26 Jan 2024 09:57:25 -0800

Rubén Justo <[email-masked]> writes:

> When no subcommand is specified to "reflog", we assume "show" [1]:
>
>     $ git reflog -h
>     usage: git reflog [show] [<log-options>] [<ref>]
>     ...
>
> We are not completing correctly this implicit uses of "show":
>
> With ...
>
>     $ git checkout -b default
>
> ... we are not completing "default":
>
>     $ git reflog def<TAB><TAB>
>
> And we are incorrectly returning the "subcommands" when:
>
>     $ git reflog default <TAB><TAB>
>     delete expire show
>
> Let's use __gitcomp_subcommand to correctly handle implicit
> subcommands.

As with a good bug report, if you are showing an "incorrect"
behaviour, you should also illustrate what you think is the
"correct" behaviour (see below).

>   1. cf39f54efc (git reflog show, 2007-02-08)
>
> Signed-off-by: Rubén Justo <[email-masked]>
> ---
>  contrib/completion/git-completion.bash | 9 ++++-----
>  t/t9902-completion.sh                  | 8 ++++++++
>  2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index 5f2e904b56..c41f25aa80 100644
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -2448,13 +2448,12 @@ _git_rebase ()
>  _git_reflog ()
>  {
>  	local subcommands="show delete expire"
> -	local subcommand="$(__git_find_on_cmdline "$subcommands")"
>  
> -	if [ -z "$subcommand" ]; then
> -		__gitcomp "$subcommands"
> -	else
> -		__git_complete_refs
> +	if __gitcomp_subcommand "$subcommands"; then
> +		return
>  	fi
> +
> +	__git_complete_refs
>  }

So, when we see something that could be a subcommand we complete it
as a subcommand and return.  In your example, how should

    $ git reflog def<TAB>

work?  We try to see if there is a subcommand that begins with
"def", we see nothing matching, and then run __git_complete_refs?
What if the branch you created earlier were not named "default" but,
say, "delmonte", and you did "git reflog del<TAB>"?  Shouldn't the
user be offered "delete" and "delmonte" as potential completions?

>  __git_send_email_confirm_options="always never auto cc compose"
> diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
> index aa9a614de3..231e17f378 100755
> --- a/t/t9902-completion.sh
> +++ b/t/t9902-completion.sh
> @@ -2618,6 +2618,14 @@ test_expect_success 'git clone --config= - value' '
>  	EOF
>  '
>  
> +test_expect_success 'git reflog show' '
> +	test_when_finished "git checkout -" &&
> +	git checkout -b shown &&
> +	test_completion "git reflog sho" "show " &&

IOW, shouldn't this offer both show and shown?

> +	test_completion "git reflog show sho" "shown " &&
> +	test_completion "git reflog shown sho" "shown "
> +'
> +
>  test_expect_success 'options with value' '
>  	test_completion "git merge -X diff-algorithm=" <<-\EOF