Re: [PATCH] apply: clarify description of --index

Johannes Sixt [off-list ref] writes:

Am 23.10.20 um 16:38 schrieb Junio C Hamano:

quoted

Johannes Sixt [off-list ref] writes:

quoted

quoted

-	Apply the patch to both the index and the working tree (or
-	merely check that it would apply cleanly to both if `--check` is
-	in effect). Note that `--index` expects index entries and
-	working tree copies for relevant paths to be identical (their
-	contents and metadata such as file mode must match), and will
-	raise an error if they are not, even if the patch would apply
-	cleanly to both the index and the working tree in isolation.
+	After making sure the paths the patch touches in the working
+	tree have no modifications relative to their index entries,
+	apply the patch both to the index entries and to the working
+	tree files or see if it applies	cleanly, when `--check` is in
+	effect.

I don't think that this is an improvement. The purpose of --index *is*
to apply the patch to both index and worktree, and that should be
mentioned first. The check that both are identical, is a prerequisite
and not the primary objective of the option.

Yeah, but this was an attempt to clarify what that "apply to both",
which is the central part of the operation, exactly means.

The only mode of operation we offer is that we start from identical
index and working tree, and make the same change so that we arrive
at the same outcome.  It is not like you can have some changes in
the working tree file as long as they do not overlap and collide
with the incoming patch, make the same change with the patch to
arrive at different contents as the outcome.  We explicitly forbid
that, but "apply to both" does not exactly tell it to the readers.

Your have point that the original text muddies the preconditions a bit,
but I still think that "what it does" must be the first thing to be
mentioned, and the preconditions the second.

Yeah.  I offhand do not think of a better phrasing within the
constraint that "apply to only identical state" must be said after
saying "to both the index and the working tree", though, so I'll
leave it up to the list's wisdom ;-)

Thanks.