tests/test-merge-remove.t

filelog: wrap revlog instead of inheriting it (API)

The revlog base class exposes a ton of methods. Inheriting the
revlog class for filelog will make it difficult to expose a
clean interface. There will be abstraction violations.

This commit breaks the inheritance of revlog by the filelog
class. Filelog instances now contain a reference to a revlog
instance. Various properties and methods are now proxied to
that instance.

There is precedence for doing this: manifestlog does something
similar. Although, manifestlog has a cleaner interface than
filelog. We'll get there with filelog...

The new filelog class exposes a handful of extra properties and
methods that aren't part of the declared filelog interface.
Every extra item was added in order to get a test to pass. The
set of tests that failed without these extra proxies has
significant overlap with the set of tests that don't work with
the simple store repo. There should be no surprise there.

Hopefully the hardest part about this commit to review are the
changes to bundlerepo and unionrepo. Both repository types
define a custom revlog or revlog-like class and then have a
custom filelog that inherits from both filelog and their custom
revlog. This code has been changed so the filelog types don't
inherit from revlog. Instead, they replace the revlog instance
on the created filelog. This is super hacky. I plan to fix this
in a future commit by parameterizing filelog.__init__.

Because Python function call overhead is a thing, this change
could impact performance by introducing a nearly empty proxy
function for various methods and properties. I would gladly
measure the performance impact of it, but I'm not sure what
operations have tight loops over filelog attribute lookups
or function calls. I know some of the DAG traversal code can
be sensitive about the performance of e.g. parentrevs(). However,
many of these functions are implemented on the revlog class and
therefore have direct access to self.parentrevs() and aren't
going through a proxy.

.. api::

   filelog.filelog is now a standalone class and doesn't inherit
   from revlog. Instead, it wraps a revlog instance at self._revlog.
   This change was made in an attempt to formalize storage APIs and
   prevent revlog implementation details leaking through to callers.

Differential Revision: https://phab.mercurial-scm.org/D3154

  $ hg init

  $ echo foo > foo
  $ echo bar > bar
  $ hg ci -qAm 'add foo bar'

  $ echo foo2 >> foo
  $ echo bleh > bar
  $ hg ci -m 'change foo bar'

  $ hg up -qC 0
  $ hg mv foo foo1
  $ echo foo1 > foo1
  $ hg cat foo >> foo1
  $ hg ci -m 'mv foo foo1'
  created new head

  $ hg merge
  merging foo1 and foo to foo1
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg debugstate --nodates
  m   0         -2 unset               bar
  m   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -q
  M bar
  M foo1


Removing foo1 and bar:

  $ cp foo1 F
  $ cp bar B
  $ hg rm -f foo1 bar

  $ hg debugstate --nodates
  r   0         -1 set                 bar
  r   0         -1 set                 foo1
  copy: foo -> foo1

  $ hg st -qC
  R bar
  R foo1


Re-adding foo1 and bar:

  $ cp F foo1
  $ cp B bar
  $ hg add -v foo1 bar
  adding bar
  adding foo1

  $ hg debugstate --nodates
  n   0         -2 unset               bar
  n   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -qC
  M bar
  M foo1
    foo


Reverting foo1 and bar:

  $ hg revert -vr . foo1 bar
  saving current version of bar as bar.orig
  reverting bar
  saving current version of foo1 as foo1.orig
  reverting foo1

  $ hg debugstate --nodates
  n   0         -2 unset               bar
  n   0         -2 unset               foo1
  copy: foo -> foo1

  $ hg st -qC
  M bar
  M foo1
    foo

  $ hg diff

Merge should not overwrite local file that is untracked after remove

  $ rm *
  $ hg up -qC
  $ hg rm bar
  $ hg ci -m 'remove bar'
  $ echo 'memories of buried pirate treasure' > bar
  $ hg merge
  bar: untracked file differs
  abort: untracked files in working directory differ from files in requested revision
  [255]
  $ cat bar
  memories of buried pirate treasure

Those who use force will lose

  $ hg merge -f
  other [merge rev] changed bar which local [working copy] deleted
  use (c)hanged version, leave (d)eleted, or leave (u)nresolved? u
  merging foo1 and foo to foo1
  0 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]
  $ cat bar
  bleh
  $ hg st
  M bar
  M foo1