Re: [PATCH v2] git-prompt: preserve value of $? inside shell prompt

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 22, 2014, 19:58 UTC
Message-ID: <xmqqsig78nim.fsf@gitster.dls.corp.google.com>
In-Reply-To: <alpine.LSU.2.00.1412221808110.2546@hermes-1.csi.cam.ac.uk>

Tony Finch <dot@dotat.at> writes:

Show 26 quoted lines

> If you have a prompt which displays the command exit status,
> __git_ps1 without this change corrupts it, although it has
> the correct value in the parent shell:
>
> 	~/src/git (master) 0 $ set | grep ^PS1
> 	PS1='\w$(__git_ps1) $? \$ '
> 	~/src/git (master) 0 $ false
> 	~/src/git (master) 0 $ echo $?
> 	1
> 	~/src/git (master) 0 $
>
> There is a slightly ugly workaround:
>
> 	~/src/git (master) 0 $ set | grep ^PS1
> 	PS1='\w$(x=$?; __git_ps1; exit $x) $? \$ '
> 	~/src/git (master) 0 $ false
> 	~/src/git (master) 1 $
>
> This change makes the workaround unnecessary.
>
> Signed-off-by: Tony Finch <dot@dotat.at>
> ---
>  contrib/completion/git-prompt.sh | 4 ++++
>  1 file changed, 4 insertions(+)
>
> I hope that explains it properly :-)

Yes. I wouldn't have spent 20 minutes experimenting with various hypothetical use cases if the above were there in the first place.

Thanks.  Will queue.

Show 20 quoted lines

> diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
> index c5473dc..5fe69d0 100644
> --- a/contrib/completion/git-prompt.sh
> +++ b/contrib/completion/git-prompt.sh
> @@ -288,6 +288,7 @@ __git_eread ()
>  # In this mode you can request colored hints using GIT_PS1_SHOWCOLORHINTS=true
>  __git_ps1 ()
>  {
> +	local exit=$?
>  	local pcmode=no
>  	local detached=no
>  	local ps1pc_start='\u@\h:\w '
> @@ -511,4 +512,7 @@ __git_ps1 ()
>  	else
>  		printf -- "$printf_format" "$gitstring"
>  	fi
> +
> +	# preserve exit status
> +	return $exit
>  }