Re: [PATCH V2] git-apply: add --allow-empty flag

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 28, 2021, 05:08 UTC
Message-ID: <xmqqmttjate1.fsf@gitster.g>
In-Reply-To: <20210427194049.14399-1-jerry@skydio.com>

Jerry Zhang <jerry@skydio.com> writes:

Show 24 quoted lines

> Some users or scripts will pipe "git diff"
> output to "git apply" when replaying diffs
> or commits. In these cases, they will rely
> on the return value of "git apply" to know
> whether the diff was applied successfully.
>
> However, for empty commits, "git apply" will
> fail. This complicates scripts since they
> have to either buffer the diff and check
> its length, or run diff again with "exit-code",
> essentially doing the diff twice.
>
> Add the "--allow-empty" flag to "git apply"
> which allows it to handle both empty diffs
> and empty commits created by "git format-patch
> --always" by doing nothing and returning 0.
>
> Add tests for both with and without --allow-empty.
>
> Signed-off-by: Jerry Zhang <jerry@skydio.com>
> ---
> This patch applies on top of "git-apply: add --quiet flag".
> The conflict is in Documentation -> Synopsis and is
> trivial to solve.

> V1 -> V2:
> - Moved behavior under a flag
> - Added tests for both cases

When people add a flag (a boolean option), it becomes tempting to add a corresponding configuration variable.

I wonder it this step should start calling

	git apply --no-allow-empty

when "git am" drives it, so that a futre end-user configuration variable would not break it?