Re: [PATCH v2] diff-lib.c: adjust position of i-t-a entries in diff

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 19, 2015, 06:00 UTC
Message-ID: <xmqqlhitle5w.fsf@gitster.dls.corp.google.com>
In-Reply-To: <xmqqtwxikpz6.fsf@gitster.dls.corp.google.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 11 quoted lines

> Ah, wait.
>
> I suspect that it all cancels out.
> ...
> Now, as you mentioned, there _may_ be codepaths that uses the same
> definition of "what's in the index" as what diff-cache used to take
> before your patches, and they may be broken by removing the
> invalidation.  If we find such codepaths, we should treat their old
> behaviour as buggy and fix them, instead of reintroducing the
> invalidation and keep their current behaviour, as the new world
> order is "i-t-a entries in the index does not yet exist."

One potential negative consequence of the new world order I can immediately think of is this. In many operations, we try to be lenient to changes in the working tree as long as the index is clean. "read-tree -m" is the most visible one, where we require that the index and HEAD matches while allowing changes to working tree paths as long as they do not interfere with the paths that are involved in the merge. We need to make sure that the path dir/bar added by "add -N dir/bar", which in the new world order does not count as "index is not clean and there is a difference from HEAD", (1) does not interfere with the mergy operation that wants to touch dir (which _could_ even be expected to be a file) or dir/bar, and (2) is not lost because the mergy operation wants to touch dir or dir/bar, for example.