view tests/test-issue612.t @ 41188:006c9ce486fa

rust-cpython: bindings for MissingAncestors

The exposition is rather straightforward, except for the
remove_ancestors_from() method, which forces us to an inefficient
conversion between Python sets and Rust HashSets.

Two alternatives are proposed in comments:

- changing the inner API to "emit" the revision numbers to discard
  this would be a substantial change, and it would be better only in the
  cases where there are more to retain than to discard
- mutating the Python set directly: this would force us to define an abstract
  `RevisionSet` trait, and implement it both for plain `HashSet` and for
  a struct enclosing a Python set with the GIL marker `Python<'p>`, also a non
  trivial effort.

The main (and seemingly only) caller of this method being
`mercurial.setdiscovery`, which is currently undergoing serious refactoring,
it's not clear whether these improvements would be worth the effort right now,
so we're leaving it as-is.

Also, in `get_bases()` (will also be used by `setdiscovery`), we'd prefer
to build a Python set directly, but we resort to returning a tuple, waiting
to hear back from our PR onto rust-cpython about that

Differential Revision: https://phab.mercurial-scm.org/D5550

https://bz.mercurial-scm.org/612

  $ hg init
  $ mkdir src
  $ echo a > src/a.c
  $ hg ci -Ama
  adding src/a.c

  $ hg mv src source
  moving src/a.c to source/a.c

  $ hg ci -Ammove

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

  $ echo new > src/a.c
  $ echo compiled > src/a.o
  $ hg ci -mupdate
  created new head

  $ hg status
  ? src/a.o

  $ hg merge
  merging src/a.c and source/a.c to source/a.c
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status
  M source/a.c
  R src/a.c
  ? src/a.o