difflame improvements

From: Edmundo Carmona Antoranz <eantoranz@gmail.com>
Date: Feb 15, 2017, 05:19 UTC
Message-ID: <CAOc6etYz6+FzDRbkLS2SB9=F9DP18=6uLKdfCN3D3yd2Gug-tw@mail.gmail.com>

Hi!

I've been working on detecting revisions where a "real" deletion was made and I think I advanced a lot in that front. I still have to work on many scenarios (renamed files, for example... also performance) but at least I'm using a few runs against git-scm history and the results are "promising":

23:05 $ git blame -s --reverse -L 25,40 HEAD~20..HEAD -- versioncmp.c 066fb0494e 25) static int initialized; 066fb0494e 26) 066fb0494e 27) /* 8ec68d1ae2 28) * p1 and p2 point to the first different character in two strings. If 8ec68d1ae2 29) * either p1 or p2 starts with a prerelease suffix, it will be forced 8ec68d1ae2 30) * to be on top. 8ec68d1ae2 31) * 8ec68d1ae2 32) * If both p1 and p2 start with (different) suffix, the order is 8ec68d1ae2 33) * determined by config file. 066fb0494e 34) * 8ec68d1ae2 35) * Note that we don't have to deal with the situation when both p1 and 8ec68d1ae2 36) * p2 start with the same suffix because the common part is already 8ec68d1ae2 37) * consumed by the caller. 066fb0494e 38) * 066fb0494e 39) * Return non-zero if *diff contains the return value for versioncmp() 066fb0494e 40) */

Lines 28-33:

23:05 $ git show --summary 8ec68d1ae2
commit 8ec68d1ae2863823b74d67c5e92297e38bbf97bc
Merge: e801be066 c48886779
Author: Junio C Hamano <>
Date:   Mon Jan 23 15:59:21 2017 -0800

    Merge branch 'vn/diff-ihc-config'

    "git diff" learned diff.interHunkContext configuration variable
    that gives the default value for its --inter-hunk-context option.

    * vn/diff-ihc-config:
      diff: add interhunk context config option

And this is not telling me the _real_ revision where the lines were _deleted_ so it's not very helpful, as Peff has already mentioned.

Running difflame:

23:06 $ time ~/proyectos/git/difflame/difflame.py -bp=-s -w HEAD~20 HEAD -- versioncmp.c

diff --git a/versioncmp.c b/versioncmp.c
index 80bfd109f..9f81dc106 100644
--- a/versioncmp.c
+++ b/versioncmp.c
@@ -24,42 +24,83 @@
.
.
.
+b17846432d  33) static void find_better_matching_suffix(const char
*tagname, const char *suffix,
+b17846432d  34)                                        int
suffix_len, int start, int conf_pos,
+b17846432d  35)                                        struct
suffix_match *match)
+b17846432d  36) {
b17846432d  37)        /*
       c026557a3 versioncmp: generalize version sort suffix reordering
-c026557a3 (SZEDER 28)  * p1 and p2 point to the first different
character in two strings. If
-c026557a3 (SZEDER 29)  * either p1 or p2 starts with a prerelease
suffix, it will be forced
-c026557a3 (SZEDER 30)  * to be on top.
-c026557a3 (SZEDER 31)  *
-c026557a3 (SZEDER 32)  * If both p1 and p2 start with (different)
suffix, the order is
-c026557a3 (SZEDER 33)  * determined by config file.
       b17846432 versioncmp: factor out helper for suffix matching
+b17846432d  38)         * A better match either starts earlier or
starts at the same offset
+b17846432d  39)         * but is longer.
+b17846432d  40)         */
+b17846432d  41)        int end = match->len < suffix_len ?
match->start : match->start-1;
.
.
.

Same range of (deleted) lines:

23:10 $ git --show --name-status c026557a3
commit c026557a37361b7019acca28f240a19f546739e9
Author: SZEDER Gábor <>
Date:   Thu Dec 8 15:24:01 2016 +0100

   versioncmp: generalize version sort suffix reordering

   The 'versionsort.prereleaseSuffix' configuration variable, as its name
   suggests, is supposed to only deal with tagnames with prerelease
.
.
.


   Signed-off-by: SZEDER Gábor <>
   Signed-off-by: Junio C Hamano <>

M       Documentation/config.txt
M       Documentation/git-tag.txt
M       t/t7004-tag.sh
M       versioncmp.c


This is the revision where the deletion happened.

That's it for the time being.