Re: [PATCH] Teach 'git-apply --whitespace=strip' to remove empty lines at end of file

From: Junio C Hamano <junkio@cox.net>
Date: May 19, 2007, 20:39 UTC
Message-ID: <7vhcq8v97k.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <464EF7D2.4030406@gmail.com>

Marco Costalba <mcostalba@gmail.com> writes:

Show 20 quoted lines

> Signed-off-by: Marco Costalba <mcostalba@gmail.com>
> ---
>   builtin-apply.c |    4 ++++
>   1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/builtin-apply.c b/builtin-apply.c
> index 0399743..f17f838 100644
> --- a/builtin-apply.c
> +++ b/builtin-apply.c
> @@ -1738,6 +1738,10 @@ static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag, i
>   		newsize--;
>   	}
>
> +	if (new_whitespace == strip_whitespace)
> +		while (newsize > 1 && !strncmp(new + newsize - 2, "\n\n", 2))
> +			newsize--;
> +
>   	oldlines = old;
>   	newlines = new;
>   	leading = frag->leading;

I agree to what you are trying to do, but this patch is wrong. You are stripping trailing newlines that were NOT introduced by the patch, but happened to be present in the preimage (and in the context).

Try it on this test vector:

cat >AAA <<\EOF a b c d

e f g h i

j k

EOF cat >P.diff <<\EOF

diff --git a/AAA b/AAA
index 59f6a9c..ffb28f5 100644
--- a/AAA
+++ b/AAA
@@ -1,4 +1,4 @@
-a
+A
 b
 c
 d
@@ -6,12 +6,11 @@ d
 
 e
 f
+
+
 g
 h
-i
-
 
-j
 k
 
 
EOF