Subject: Re: [RESEND PATCH 2/3] git-completion.bash: fix `git <args>... stash branch` bug

From: Junio C Hamano <[email-masked]>
Date: Thu, 18 Mar 2021 13:30:38 -0700

Denton Liu <[email-masked]> writes:

> When completions are offered for `git stash branch<TAB>`, the user is
> supposed to receive refs. This works in the case where the main git
> command is called without arguments but if options are provided, such as
> `git -C dir stash branch<TAB>`, then the `$cword -eq 3` provides
> incorrect results.
>
> Count the words relative to the first instance of "stash" so that we
> ignore arguments to the main git command.
>
> Unfortunately, this still does not work 100% correctly. For example, in
> the case of something like `git -C stash stash branch<TAB>`, this will
> incorrectly identify the first "stash" as the command. This seems to be
> an edge-case that we can ignore, though, as other functions, such as
> _git_worktree(), suffer from the same problem.

I am not familiar with how the completion support works, but doing
this inside _git_stash() and still not being able to tell which
"stash" on the command line is supposed to be the git subcommand
smells quite fishy to me.  

How did the caller decide to invoke _git_stash helper function in
the first place?

When it is given "git -C push --paginate stash branch<TAB>", it must
have parsed the command line, past the options given to the "git"
potty, to find "stash" on the command line that it is _git_stash and
not _git_push that needs to be called, no?  If it were possible to
propagate that information without losing it, then we do not have to
recompute where the subcommand name is at all, do we?

> Signed-off-by: Denton Liu <[email-masked]>
> ---
>  contrib/completion/git-completion.bash | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index fe79f6b71c..da46f46e3c 100644
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -3016,6 +3016,9 @@ _git_stash ()
>  	local save_opts='--all --keep-index --no-keep-index --quiet --patch --include-untracked'
>  	local subcommands='push list show apply clear drop pop create branch'
>  	local subcommand="$(__git_find_on_cmdline "$subcommands save")"
> +	local stash_idx="$(__git_find_on_cmdline --show-idx stash)"
> +	stash_idx="${stash_idx% *}"
> +
>  	if [ -z "$subcommand" -a -n "$(__git_find_on_cmdline "-p")" ]; then
>  		subcommand="push"
>  	fi
> @@ -3060,7 +3063,7 @@ _git_stash ()
>  	branch,--*)
>  		;;
>  	branch,*)
> -		if [ $cword -eq 3 ]; then
> +		if [ $((cword - stash_idx)) -eq 2 ]; then
>  			__git_complete_refs
>  		else
>  			__gitcomp_nl "$(__git stash list \