Subject: Re: [PATCH v4 1/2] diff: move no-index detection to builtin/diff.c

From: Jonathan Nieder <[email-masked]>
Date: Fri, 13 Dec 2013 16:43:47 -0800

Hi,

Thomas Gummerer wrote:

> Signed-off-by: Thomas Gummerer <[email-masked]>

Thanks, and sorry for the slow follow-up.

[...]
> --- a/builtin/diff.c
> +++ b/builtin/diff.c
> @@ -16,6 +16,9 @@
[...]
> @@ -283,14 +286,57 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
>  	 * Other cases are errors.
>  	 */
>  
> +	/* Were we asked to do --no-index explicitly? */
> +	for (i = 1; i < argc; i++) {
> +		if (!strcmp(argv[i], "--")) {
> +			i++;
> +			break;
> +		}
> +		if (!strcmp(argv[i], "--no-index"))
> +			no_index = DIFF_NO_INDEX_EXPLICIT;

Neat.

[...]
> +	/*
> +	 * Treat git diff with at least one path outside of the
> +	 * repo the same as if the command would have been executed
> +	 * outside of a git repository.  In this case it behaves
> +	 * the same way as "git diff --no-index <a> <b>", which acts
> +	 * as a colourful "diff" replacement.
> +	 */
> +	if (nongit || ((argc == i + 2) &&
> +		       (!path_inside_repo(prefix, argv[i]) ||
> +			!path_inside_repo(prefix, argv[i + 1]))))
> +		no_index = DIFF_NO_INDEX_IMPLICIT;

What happens if I run 'git diff --no-index /tmp git.c git.c' from
within a git repository?  With this, I fear I will get

	Not a git repository
	To compare two paths outside a working tree:
	usage: git diff [--no-index] <path> <path>

instead of the expected

	usage: git diff --no-index <path> <path>

Something like

	if (no_index)
		;
	else if (nongit)
		no_index = DIFF_NO_INDEX_IMPLICIT;
	else if (argc != i + 2)
		;
	else if (!path_inside_repo(prefix, argv[i]) ||
		 !path_inside_repo(prefix, argv[i + 1]))
		no_index = DIFF_NO_INDEX_IMPLICIT;

should work.  Or:

	if (!no_index) {
		/*
		 * Treat git diff with ...
		 */
		if (nongit || ...)
			no_index = DIFF_NO_INDEX_IMPLICIT;
	}

Or the '!no_index &&' condition inserted some other way.

> -	/* If this is a no-index diff, just run it and exit there. */
> -	diff_no_index(&rev, argc, argv, nongit, prefix);
> +	if (no_index) {
> +		if (argc != i + 2) {
[...]
> +			/* Give the usage message for non-repository usage and exit. */
> +			usagef("git diff %s <path> <path>",
> +			       no_index == DIFF_NO_INDEX_EXPLICIT ?
> +					"--no-index" : "[--no-index]");
> +
> +		}
> +		/* If this is a no-index diff, just run it and exit there. */
> +		diff_no_index(&rev, argc, argv, prefix);
> +	}

Perhaps, to avoid some nesting:

	/* A no-index diff takes exactly two path arguments. */
	if (no_index && argc != i + 2) {
		...
		usagef(...);
	}

	if (no_index)
		/* Just run the diff and exit. */
		diff_no_index(...);

Jonathan