view tests/test-issue522.t @ 33377:5d63e5f40bea

revset: define successors revset

This revset returns all successors, including transit nodes and the source
nodes (to be consistent with existing revsets like "ancestors").

To filter out transit nodes, use `successors(X)-obsolete()`.
To filter out divergent case, use `successors(X)-divergent()-obsolete()`.

The revset could be useful to define rebase destination, like:
`max(successors(BASE)-divergent()-obsolete())`. The `max` is to deal with
splits.

There are other implementations where `successors` returns just one level of
successors, and `allsuccessors` returns everything. I think `successors`
returning all successors by default is more user friendly. We have seen
cases in production where people use 1-level `successors` while they really
want `allsuccessors`. So it seems better to just have one single revset
returning all successors by default to avoid user errors.

In the future we might want to add `depth` keyword argument to it and for
other revsets like `ancestors` etc. Or even build some flexible indexing
syntax [1] to satisfy people having the depth limit requirement.

[1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-July/101140.html

https://bz.mercurial-scm.org/522

In the merge below, the file "foo" has the same contents in both
parents, but if we look at the file-level history, we'll notice that
the version in p1 is an ancestor of the version in p2. This test makes
sure that we'll use the version from p2 in the manifest of the merge
revision.

  $ hg init

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

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

  $ hg backout -r tip -m 'backout changed foo'
  reverting foo
  changeset 2:4d9e78aaceee backs out changeset 1:b515023e500e

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ touch bar
  $ hg ci -qAm 'add bar'

  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in local:
     bar
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: bbd179dfa0a7, local: 71766447bdbb+, remote: 4d9e78aaceee
   foo: remote is newer -> g
  getting foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg debugstate | grep foo
  m   0         -2 unset               foo

  $ hg st -A foo
  M foo

  $ hg ci -m 'merge'

  $ hg manifest --debug | grep foo
  c6fc755d7e68f49f880599da29f15add41f42f5a 644   foo

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       5  .....       0 2ed2a3912a0b 000000000000 000000000000 (re)
       1         5       9  .....       1 6f4310b00b9a 2ed2a3912a0b 000000000000 (re)
       2        14       5  .....       2 c6fc755d7e68 6f4310b00b9a 000000000000 (re)