Re: Score in diff-format

[Junio C Hamano <gitster@pobox.com>]

Michael J Gruber <git@drmicha.warpmail.net> writes:

> I'd say it depends on the definition of "so". The documentation is
> correct if you read "so" as "*always* followed by a score". I guess you
> read it as "followed by a score".

I read it so as well ;-)

> Percentages with M are not mentioned in diff-format, but they are a
> consequence of "-B" processing. Maybe we could mention that?

-- >8 --
Subject: diff-format doc: a score can follow M for rewrite

b6d8f309 (diff-raw format update take #2., 2005-05-23) started
documenting the diff format, and it said

 ...
 (8) sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
 (9) status, followed by similarlity index number only for C and R.
 (10) a tab or a NUL when '-z' option is used.
 ...

because C and R _were_ the only ones that came with a number back
then.  This was corrected by ddafa7e9 (diff-helper: Fix R/C score
parsing under -z flag., 2005-05-29) and we started saying "score"
instead of "similarlity index" (because we can have other kind of
score there), and stopped saying "only for C and R" (because Git is
an ever evolving system).  Later f345b0a0 ([PATCH] Add -B flag to
diff-* brothers., 2005-05-30) introduced a new concept,
"dissimilarity" score and it did not have to fix any documentation.

The current text that says only C and R can have scores came
independently from a5a323f3 (Add reference for status letters in
documentation., 2008-11-02) and it was wrong from the day one.

Noticed-by: Mike Hommey
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 Documentation/diff-format.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/diff-format.txt b/Documentation/diff-format.txt
index 15c7e79..e6cfc9b 100644
--- a/Documentation/diff-format.txt
+++ b/Documentation/diff-format.txt
@@ -66,7 +66,8 @@ be committed)
 
 Status letters C and R are always followed by a score (denoting the
 percentage of similarity between the source and target of the move or
-copy), and are the only ones to be so.
+copy).  M may show how completely the modification rewrites the file
+with a score (denoting the percentage of dissimilarity).
 
 <sha1> is shown as all 0's if a file is new on the filesystem
 and it is out of sync with the index.