mercurial/node.py

copies: filter invalid copies only at end of pathcopies() (issue6163)

copies._filter() filters out copies whose source file does not exist
in the start commit or whose target file does not exist in the end
commit. We do that after chaining copies with dirstate copies or
backward renames from another branch. We also do at the end of the
changeset-centric copy tracing. The filtering means that we will
remove copies to/from files that did not exist in some intermediate
commit. That is inconsistent with what we do if a file has been
deleted and then re-added (we allow updating across that).

Copying the two first examples from issue6163:

  @  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'

When doing `hg rebase -r 1 -d 4` in the first case, it succeeds, but
`hg rebase -r 2 -d 4` in the second case does not. That's because we
chain and filter via commit 0, which does not have file 'x' in the
second case. IMO, that's clearly inconsistent. So this patch removes
the filtering step so it only happens at the end. If a file was
temporarily removed, whether via a merge base or not, it will now
still be considered the same file. That fixes issue6163 for the
changeset-centric case.

Differential Revision: https://phab.mercurial-scm.org/D6603

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import binascii

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
# Adapt to Python 3 API changes. If this ends up showing up in
# profiles, we can use this version only on Python 3, and forward
# binascii.unhexlify like we used to on Python 2.
def bin(s):
    try:
        return binascii.unhexlify(s)
    except binascii.Error as e:
        raise TypeError(e)

nullrev = -1
# In hex, this is '0000000000000000000000000000000000000000'
nullid = b"\0" * 20
nullhex = hex(nullid)

# Phony node value to stand-in for new files in some uses of
# manifests.
# In hex, this is '2121212121212121212121212121212121212121'
newnodeid = '!!!!!!!!!!!!!!!!!!!!'
# In hex, this is '3030303030303030303030303030306164646564'
addednodeid = '000000000000000added'
# In hex, this is '3030303030303030303030306d6f646966696564'
modifiednodeid = '000000000000modified'

wdirfilenodeids = {newnodeid, addednodeid, modifiednodeid}

# pseudo identifiers for working directory
# (they are experimental, so don't add too many dependencies on them)
wdirrev = 0x7fffffff
# In hex, this is 'ffffffffffffffffffffffffffffffffffffffff'
wdirid = b"\xff" * 20
wdirhex = hex(wdirid)

def short(node):
    return hex(node[:6])