view tests/test-merge-halt.t @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > [phases]
  > publish=False
  > [merge]
  > EOF

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ echo b > b
  $ hg commit -qAm ab
  $ echo c >> a
  $ echo c >> b
  $ hg commit -qAm c
  $ hg up -q ".^"
  $ echo d >> a
  $ echo d >> b
  $ hg commit -qAm d

Testing on-failure=continue
  $ echo on-failure=continue >> $HGRCPATH
  $ hg rebase -s 1 -d 2 --tool false
  rebasing 1:1f28a51c3c9b "c"
  merging a
  merging a failed!
  merging b
  merging b failed!
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  U a
  U b

  $ hg rebase --abort
  rebase aborted

Testing on-failure=halt
  $ echo on-failure=halt >> $HGRCPATH
  $ hg rebase -s 1 -d 2 --tool false
  rebasing 1:1f28a51c3c9b "c"
  merging a
  merging a failed!
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  U a
  U b

  $ hg rebase --abort
  rebase aborted

Testing on-failure=prompt
  $ cat <<EOS >> $HGRCPATH
  > [merge]
  > on-failure=prompt
  > [ui]
  > interactive=1
  > EOS
  $ cat <<EOS | hg rebase -s 1 -d 2 --tool false
  > y
  > n
  > EOS
  rebasing 1:1f28a51c3c9b "c"
  merging a
  merging a failed!
  continue merge operation (yn)? y
  merging b
  merging b failed!
  continue merge operation (yn)? n
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  U a
  U b

  $ hg rebase --abort
  rebase aborted

Check that successful tool with failed post-check halts the merge
  $ cat <<EOS >> $HGRCPATH
  > [merge-tools]
  > true.check=changed
  > EOS
  $ cat <<EOS | hg rebase -s 1 -d 2 --tool true
  > y
  > n
  > n
  > EOS
  rebasing 1:1f28a51c3c9b "c"
  merging a
   output file a appears unchanged
  was merge successful (yn)? y
  merging b
   output file b appears unchanged
  was merge successful (yn)? n
  merging b failed!
  continue merge operation (yn)? n
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  R a
  U b

  $ hg rebase --abort
  rebase aborted

Check that conflicts with conflict check also halts the merge
  $ cat <<EOS >> $HGRCPATH
  > [merge-tools]
  > true.check=conflicts
  > true.premerge=keep
  > [merge]
  > on-failure=halt
  > EOS
  $ hg rebase -s 1 -d 2 --tool true
  rebasing 1:1f28a51c3c9b "c"
  merging a
  merging a failed!
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  U a
  U b

  $ hg rebase --abort
  rebase aborted

Check that always-prompt also can halt the merge
  $ cat <<EOS | hg rebase -s 1 -d 2 --tool true --config merge-tools.true.check=prompt
  > y
  > n
  > EOS
  rebasing 1:1f28a51c3c9b "c"
  merging a
  was merge of 'a' successful (yn)? y
  merging b
  was merge of 'b' successful (yn)? n
  merging b failed!
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg resolve --list
  R a
  U b

  $ hg rebase --abort
  rebase aborted

Check that successful tool otherwise allows the merge to continue
  $ hg rebase -s 1 -d 2 --tool echo --keep --config merge-tools.echo.premerge=keep
  rebasing 1:1f28a51c3c9b "c"
  merging a
  $TESTTMP/repo/a *a~base* *a~other* (glob)
  merging b
  $TESTTMP/repo/b *b~base* *b~other* (glob)

Check that unshelve isn't broken by halting the merge
  $ cat <<EOS >> $HGRCPATH
  > [extensions]
  > shelve =
  > [merge-tools]
  > false.check=conflicts
  > false.premerge=false
  > EOS
  $ echo foo > shelve_file1
  $ echo foo > shelve_file2
  $ hg ci -qAm foo
  $ echo bar >> shelve_file1
  $ echo bar >> shelve_file2
  $ hg shelve --list
  $ hg shelve
  shelved as default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo baz >> shelve_file1
  $ echo baz >> shelve_file2
  $ hg ci -m baz
  $ hg unshelve --tool false --config merge-tools.false.premerge=keep
  unshelving change 'default'
  rebasing shelved changes
  merging shelve_file1
  merging shelve_file1 failed!
  unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
  [240]
  $ hg status --config commands.status.verbose=True
  M shelve_file1
  M shelve_file2
  ? shelve_file1.orig
  # The repository is in an unfinished *unshelve* state.
  
  # Unresolved merge conflicts:
  # 
  #     shelve_file1
  #     shelve_file2
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  
  # To continue:    hg unshelve --continue
  # To abort:       hg unshelve --abort
  
  $ hg resolve --tool false --all --re-merge
  merging shelve_file1
  merging shelve_file1 failed!
  merge halted after failed merge (see hg resolve)
  [240]
  $ hg shelve --list
  default         (* ago)    changes to: foo (glob)
  $ hg unshelve --abort
  unshelve of 'default' aborted