view CONTRIBUTORS @ 42595:819712deac69

copies: follow copies across merge base without source file (issue6163)

As in the previous patch, consider these two histories:

  @  4 'rename x to y'
  |
  o  3 'add x again'
  |
  o  2 'remove x'
  |
  | o  1 'modify x'
  |/
  o  0 'add x'

  @  4 'rename x to y'
  |
  o  3 'add x again'
  |
  | o  2 'modify x'
  | |
  | o  1 'add x'
  |/
  o  0 'base'

We trace copies from the 'modify x' commit to commit 4 by going via
the merge base (commit 0). When tracing file 'y' (_tracefile()) in the
first case, we immediately find the rename from 'x'. We check to see
if 'x' exists in the merge base, which it does, so we consider it a
valid copy. In the second case, 'x' does not exist in the merge base,
so it's not considered a valid copy. As a workaround, this patch makes
it so we also attempt the check in mergecopies's base commit (commit 1
in the second case). That feels pretty ugly to me, but I don't have
any better ideas.

Note that we actually also check not only that the filename matches,
but also that the file's nodeid matches. I don't know why we do that,
but it was like that already before I rewrote mergecopies(). That
means that the rebase will still fail in cases like this (again, it
already failed before my rewrite):


  @  4 'rename x to y'
  |
  o  3 'add x again with content X2'
  |
  o  2 'remove x'
  |
  | o  1 'modify x to content X2'
  |/
  o  1 'modify x to content X1'
  |
  o  0 'add x with content X0'

Differential Revision: https://phab.mercurial-scm.org/D6604

[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]

Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>