Re: [RFC/PATCH 1/3] apply: Allow blank context lines to match beyond EOF

> "git apply --whitespace=fix" will not always succeed when used
> on a series of patches in the following circumstances:
>
> * One patch adds a blank line at the end of a file. (Since
>   --whitespace=fix is used, the blank line will *not* be added.)
>
> * The next patch adds non-blanks lines after the blank line
>   introduced in the first patch. That patch will not apply
>   because the blank line that is expected to be found at end
>   of the file is no longer there.
>
> Fix this problem by allowing a blank context line at the beginning
> of a hunk to match if parts of it falls beyond end of the file
> (i.e. at least one context line must match an existing line in
> the file).
>
> TODO: We should probably require that at least one *non-blank*
> context line should fall within the boundaries of the file.

> @@ -2002,11 +2071,17 @@ static int find_pos(struct image *img,
>  	unsigned long backwards, forwards, try;
>  	int backwards_lno, forwards_lno, try_lno;
>  
> -	if (preimage->nr > img->nr)
> -		return -1;
> +	/*
> +	 * There used to be a quick reject here in case preimage
> +	 * had more lines than img. We must let match_fragment()
> +	 * handle that case because a hunk is now allowed to
> +	 * extend beyond the end of img when --whitespace=fix
> +	 * has been given (and core.whitespace.blanks-at-eof is
> +	 * enabled).
> +	 */