Re: Bug: git log --numstat counts wrong

From: Tay Ray Chuan <rctay89@gmail.com>
Date: Sep 23, 2011, 16:38 UTC
Message-ID: <CALUzUxoujys1eWL6i6YJmFZZakcQx8oa8ZbRjixUzANB1Hpb3Q@mail.gmail.com>
In-Reply-To: <CALUzUxrswZ+AREq+OeqpTsnoB4J+_aExfmAA6X3cauJqj8RnpQ@mail.gmail.com>

On Fri, Sep 23, 2011 at 5:18 PM, Tay Ray Chuan <rctay89@gmail.com> wrote:

Show 28 quoted lines

> On Fri, Sep 23, 2011 at 1:51 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> [snip]
>> Applying the following patch should make the last two use the default
>> context or -U$num given from the command line to be consistent with the
>> codepath where we generate textual patches.
>>
>>  diff.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/diff.c b/diff.c
>> index 9038f19..302ef33 100644
>> --- a/diff.c
>> +++ b/diff.c
>> @@ -2251,6 +2251,8 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
>>                memset(&xpp, 0, sizeof(xpp));
>>                memset(&xecfg, 0, sizeof(xecfg));
>>                xpp.flags = o->xdl_opts;
>> +               xecfg.ctxlen = o->context;
>> +               xecfg.interhunkctxlen = o->interhunkcontext;
>>                xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
>>                              &xpp, &xecfg);
>>        }
>
> Thanks Junio.
>
> But wait, where does this patch go? Before or after 27af01d? If I'm
> understanding the situation correctly, this patch won't change the
> reporting 10/9 for --numstat, no?

I think I can answer this - on to v1.7.6, which is before 27af01d was merged in.

> Anyway, this patch looks right.

On further thought, I think the patch merely side-steps the problem - ie. that -U0 generates "incorrect" diffs.

Further digging reveals a xdiff-interface.c::trim_common_tail(); commenting its one and only call (patch below) gives back 10/9. Note that it only has effect when -U0.

I think this function is incorrect. xdl_cleanup_records() and xdl_clean_mmatch() may potentially look into common tail lines, so it may not be "safe" to drop all common tail lines.

-- >8 --

diff --git a/xdiff-interface.c b/xdiff-interface.c
index 0e2c169..da4fab6 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -131,7 +131,7 @@
        mmfile_t a = *mf1;
        mmfile_t b = *mf2;

-       trim_common_tail(&a, &b, xecfg->ctxlen);
+/*     trim_common_tail(&a, &b, xecfg->ctxlen);  */

        return xdl_diff(&a, &b, xpp, xecfg, xecb);
 }
-- >8 --

-- 
Cheers,
Ray Chuan