Re: [PATCH v4] git: treat "-C <treat>" as a no-op when <path> is empty

[Junio C Hamano <gitster@pobox.com>]

Karthik Nayak <karthik.188@gmail.com> writes:

> 'git -C ""' unhelpfully dies with error "Cannot change to ''",
> whereas the shell treats `cd ""' as a no-op. Taking the shell's
> behavior as a precedent, teach git to treat `-C ""' as a no-op, as
> well.
>
> Test to check the no-op behaviour of "-C <path>" when <path> is
> empty, written by Junio C Hamano.
>
> Helped-by: Junio C Hamano <gitster@pobox.com>
> Helped-by: Eric Sunchine <sunshine@sunshineco.com>
> Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
> ---

This iteration looks sensible, except that the Subject reads
strange.  Will queue with minor tweaks to the log message,
and perhaps with a fix to unreadable *(*argv)[1] that was
mentioned elsewhere.

Thanks.

>  git.c            | 10 ++++++----
>  t/t0056-git-C.sh | 10 ++++++++++
>  2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/git.c b/git.c
> index 8c7ee9c..b062e0e 100644
> --- a/git.c
> +++ b/git.c
> @@ -204,10 +204,12 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>  				fprintf(stderr, "No directory given for -C.\n" );
>  				usage(git_usage_string);
>  			}
> -			if (chdir((*argv)[1]))
> -				die_errno("Cannot change to '%s'", (*argv)[1]);
> -			if (envchanged)
> -				*envchanged = 1;
> +			if (*(*argv)[1]) {
> +				if (chdir((*argv)[1]))
> +					die_errno("Cannot change to '%s'", (*argv)[1]);
> +				if (envchanged)
> +					*envchanged = 1;
> +			}
>  			(*argv)++;
>  			(*argc)--;
>  		} else {
> diff --git a/t/t0056-git-C.sh b/t/t0056-git-C.sh
> index 99c0377..2630e75 100755
> --- a/t/t0056-git-C.sh
> +++ b/t/t0056-git-C.sh
> @@ -14,6 +14,16 @@ test_expect_success '"git -C <path>" runs git from the directory <path>' '
>  	test_cmp expected actual
>  '
>  
> +test_expect_success '"git -C <path>" with an empty <path> is a no-op' '
> +	(
> +		mkdir -p dir1/subdir &&
> +		cd dir1/subdir &&
> +		git -C "" rev-parse --show-prefix >actual &&
> +		echo subdir/ >expect &&
> +		test_cmp expect actual
> +	)
> +'
> +
>  test_expect_success 'Multiple -C options: "-C dir1 -C dir2" is equivalent to "-C dir1/dir2"' '
>  	test_create_repo dir1/dir2 &&
>  	echo 1 >dir1/dir2/b.txt &&