Subject: Re: [PATCHv3 1/2] Make xdi_diff_outf interface for running xdiff_outf diffs

From: [email-masked] (Brian Downing)
Date: Wed, 20 Aug 2008 22:37:57 -0500

On Wed, Aug 13, 2008 at 11:18:22PM -0700, Junio C Hamano wrote:
> Much nicer.  xdi_diff() is just a performance thing that only kicks in
> when you are running -U0 diff, so it is unsurprising that you did not see
> any test failures.

Interesting point here.  In playing with trying to cache the diff hashes
to speed up blame, I had to basically disable the xdi_diff tail trimming
when building the hash the first time, because it needed to see the
whole file.  In doing this, I discovered that just changing from
xdi_diff to xdl_diff /does/ change the blame -M -C -C --incremental
result for my test case.  (Unfortunately, my test case is proprietary
code...)

Is this expected, or some kind of serious bug with xdi_diff?

    :; diff proper-output other-output
    980c980
    < dee86dd25736e1778122cfde7d7455a3ef85e37d 173 173 2
    ---
    > dee86dd25736e1778122cfde7d7455a3ef85e37d 172 172 3
    982c982
    < dee86dd25736e1778122cfde7d7455a3ef85e37d 183 183 2
    ---
    > dee86dd25736e1778122cfde7d7455a3ef85e37d 184 184 1
    1509c1509
    < c6966941ebfaa1dc9b29489e53d6d7f41e52d357 287 384 1
    ---
    > c6966941ebfaa1dc9b29489e53d6d7f41e52d357 284 381 1
    1511c1511
    < c6966941ebfaa1dc9b29489e53d6d7f41e52d357 301 399 2
    ---
    > c6966941ebfaa1dc9b29489e53d6d7f41e52d357 286 383 2
    1513c1513
    < c6966941ebfaa1dc9b29489e53d6d7f41e52d357 304 402 1
    ---
    > c6966941ebfaa1dc9b29489e53d6d7f41e52d357 301 399 1
    1608c1608
    < ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 252 381 1
    ---
    > ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 252 385 1
    1610c1610
    < ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 255 383 1
    ---
    > ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 255 400 1
    1612c1612
    < ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 257 385 1
    ---
    > ecebfe8121dfd9c5836d47bbeb910fbb8f96f35c 257 402 1
    1945c1945
    < a325ab86914b15107bf0211550c7d0568fb0854c 138 172 1
    ---
    > a325ab86914b15107bf0211550c7d0568fb0854c 138 183 1

-bcd