Re: [RFC/PATCH] align D/F handling of "diff --no-index" with that of normal Git

> When a commit changes a path P that used to be a file to a directory
> and create a new path P/X in it, "git show" would say that file P
> was removed and file P/X was created for such a commit.
> 
> However, if we compare two directories, D1 and D2, where D1 has a
> file D1/P in it and D2 has a directory D2/P under which there is a
> file D2/P/X, and ask "git diff --no-index D1 D2" to show their
> differences, we simply get a refusal "file/directory conflict".
> 
> The "diff --no-index" implementation has an underlying machinery
> that can make it more in line with the normal Git if it wanted to,
> but somehow it is not being exercised.  The only thing we need to
> do, when we see a file P and a directory P/ (or the other way
> around) is to show the removal of a file P and then pretend as if we
> are comparing nothing with a whole directory P/, as the code is
> fully prepared to express a creation of everything in a directory
> (and if the comparison is between a directory P/ and a file P, then
> show the creation of the file and then let the existing code remove
> everything in P/).
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  diff-no-index.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/diff-no-index.c b/diff-no-index.c
> index 265709b..52e9546 100644
> --- a/diff-no-index.c
> +++ b/diff-no-index.c
> @@ -97,8 +97,27 @@ static int queue_diff(struct diff_options *o,
>  	if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
>  		return -1;
>  
> -	if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
> -		return error("file/directory conflict: %s, %s", name1, name2);
> +	if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2)) {
> +		struct diff_filespec *d1, *d2;
> +
> +		if (S_ISDIR(mode1)) {
> +			/* 2 is file that is created */
> +			d1 = noindex_filespec(NULL, 0);
> +			d2 = noindex_filespec(name2, mode2);
> +			name2 = NULL;
> +			mode2 = 0;
> +		} else {
> +			/* 1 is file that is deleted */
> +			d1 = noindex_filespec(name1, mode2);

> +			d2 = noindex_filespec(NULL, 0);
> +			name1 = NULL;
> +			mode1 = 0;
> +		}
> +		/* emit that file */
> +		diff_queue(&diff_queued_diff, d1, d2);
> +
> +		/* and then let the entire directory created or deleted */
> +	}
>  
>  	if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
>  		struct strbuf buffer1 = STRBUF_INIT;