From: Linus Torvalds <torvalds@osdl.org>
To: Junio C Hamano <junkio@cox.net>
Cc: Thomas Glanzmann <sithglan@stud.uni-erlangen.de>,
Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH] The diff-raw format updates.
Date: Sun, 22 May 2005 13:24:17 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.58.0505221259110.2307@ppc970.osdl.org> (raw)
In-Reply-To: <7vy8a7cavf.fsf@assigned-by-dhcp.cox.net>
On Sun, 22 May 2005, Junio C Hamano wrote:
>
> I deliberatly chose not to record rename/copy distinction in diff-raw
> --- it is to be inferred from which entry touches the src _last_.
> Everything but the last one to touch the same path is copy, and the last
> one is rename.
My counter-example: there is no rename at all, just a copy.
The current raw-diff output simply _cannot_ distinguish this from the case
where there is a rename, as far as I can tell.
Basically, imagine doing something like this:
mkdir test-copy
cd test-copy
git-init-db
cp ~/v2.6/linux/kernel/sched.c .
git-update-cache --add sched.c
echo duh | git-commit-tree $(git-write-tree) > .git/HEAD
sed 's/sched\.c/other\.c/g' < sched.c > other.c
git-update-cache --add other.c
echo duh2 | git-commit-tree $(git-write-tree) -p HEAD
and dammit, if "other.c" doesn't show up as a copy (with small
differences) of sched.c, then the whole diff algorithm is broken and
clearly isn't doing copy-diffs right at all (right now it doesn't do it
since diff-tree doesn't even do the "check copies against old", but that's
a different issue).
In other words, how do you propose to _describe_ that copy?
The whole point to the "raw diff" format is that you should be able to
get the same output with
git-diff-tree -C HEAD | git-diff-helper
git-diff-tree -C -p HEAD
and right now I don't see how you can do that.. And if you can't do that,
then the raw diff format is pointless. It's not "raw diff" at all, it's a
"less capable diff" format.
THAT is why I think the raw diff output is broken right now. All the rest
was about just trying to also make it a bit more readable while at it.
Try it. I added in the "&& detect_rename < 2" thing to diff-tree.c, and I
get:
git-whatchanged -C --root | git-diff-helper | less -S
resulting in:
diff-tree eb773598aa29bb642d6016a0d5961c80628ce490 (from 8c63fcad1f27ceed6825110aa806349dad99d89f)
Author: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sun May 22 13:17:40 2005 -0700
duh2
diff --git a/sched.c b/other.c
--- a/sched.c
+++ b/other.c
@@ -1,5 +1,5 @@
/*
- * kernel/sched.c
+ * kernel/other.c
*
* Kernel scheduler and related syscalls
*
ie it does NOT say it is a copy, because it _cannot_ say it is a copy. It
just doesn't know. A copy and a rename look exactly the same in the raw
diff output, and that's a BUG.
Linus
next prev parent reply other threads:[~2005-05-22 20:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-21 23:12 updated design for the diff-raw format Junio C Hamano
2005-05-21 23:16 ` Junio C Hamano
2005-05-21 23:17 ` Junio C Hamano
2005-05-21 23:18 ` Junio C Hamano
2005-05-21 23:19 ` Junio C Hamano
2005-05-22 2:40 ` [PATCH] Prepare diffcore interface for diff-tree header supression Junio C Hamano
2005-05-22 2:42 ` [PATCH] The diff-raw format updates Junio C Hamano
2005-05-22 6:01 ` Linus Torvalds
2005-05-22 6:33 ` Junio C Hamano
2005-05-22 6:57 ` Junio C Hamano
2005-05-22 8:31 ` [PATCH] Fix tweak in similarity estimator Junio C Hamano
2005-05-22 18:35 ` [PATCH] The diff-raw format updates Linus Torvalds
2005-05-22 18:36 ` Niklas Hoglund
2005-05-22 19:15 ` Junio C Hamano
2005-05-22 18:42 ` Thomas Glanzmann
2005-05-22 19:05 ` Linus Torvalds
2005-05-22 19:05 ` Thomas Glanzmann
2005-05-22 19:20 ` Junio C Hamano
2005-05-22 19:35 ` Junio C Hamano
2005-05-22 20:24 ` Linus Torvalds [this message]
2005-05-22 23:01 ` Junio C Hamano
2005-05-22 23:14 ` Linus Torvalds
2005-05-23 0:35 ` Junio C Hamano
2005-05-23 1:07 ` Linus Torvalds
2005-05-23 1:33 ` Junio C Hamano
2005-05-23 4:26 ` [PATCH] Rename/copy detection fix Junio C Hamano
2005-05-23 4:38 ` Comments on "Rename/copy detection fix." Junio C Hamano
2005-05-22 19:13 ` [PATCH] The diff-raw format updates Junio C Hamano
2005-05-22 9:41 ` [PATCH] Diffcore updates Junio C Hamano
2005-05-22 16:40 ` Linus Torvalds
2005-05-22 16:47 ` Junio C Hamano
2005-05-22 17:04 ` Junio C Hamano
2005-05-23 4:24 ` [PATCH] Be careful with symlinks when detecting renames and copies Junio C Hamano
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