view tests/test-convert-hg-startrev.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]
  > convert =
  > [convert]
  > hg.saverev = yes
  > EOF

  $ glog()
  > {
  >     hg -R "$1" log -G --template '{rev} "{desc}" files: {files}\n'
  > }

  $ hg init source
  $ cd source

  $ echo a > a
  $ echo b > b
  $ echo f > f
  $ hg ci -d '0 0' -qAm '0: add a b f'
  $ echo c > c
  $ hg move f d
  $ hg ci -d '1 0' -qAm '1: add c, move f to d'
  $ hg copy a e
  $ echo b >> b
  $ hg ci -d '2 0' -qAm '2: copy e from a, change b'
  $ hg up -C 0
  2 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ echo a >> a
  $ hg ci -d '3 0' -qAm '3: change a'
  $ hg merge
  merging a and e to e
  3 files updated, 1 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -d '4 0' -qAm '4: merge 2 and 3'
  $ echo a >> a
  $ hg ci -d '5 0' -qAm '5: change a'
  $ cd ..

Convert from null revision

  $ hg convert --config convert.hg.startrev=null source full
  initializing destination full repository
  scanning source...
  sorting...
  converting...
  5 0: add a b f
  4 1: add c, move f to d
  3 2: copy e from a, change b
  2 3: change a
  1 4: merge 2 and 3
  0 5: change a

  $ glog full
  o  5 "5: change a" files: a
  |
  o    4 "4: merge 2 and 3" files: e
  |\
  | o  3 "3: change a" files: a
  | |
  o |  2 "2: copy e from a, change b" files: b e
  | |
  o |  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
  $ rm -Rf full

Convert from zero revision

  $ hg convert --config convert.hg.startrev=0 source full
  initializing destination full repository
  scanning source...
  sorting...
  converting...
  5 0: add a b f
  4 1: add c, move f to d
  3 2: copy e from a, change b
  2 3: change a
  1 4: merge 2 and 3
  0 5: change a

  $ glog full
  o  5 "5: change a" files: a
  |
  o    4 "4: merge 2 and 3" files: e
  |\
  | o  3 "3: change a" files: a
  | |
  o |  2 "2: copy e from a, change b" files: b e
  | |
  o |  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
Convert from merge parent

  $ hg convert --config convert.hg.startrev=1 source conv1
  initializing destination conv1 repository
  scanning source...
  sorting...
  converting...
  3 1: add c, move f to d
  2 2: copy e from a, change b
  1 4: merge 2 and 3
  0 5: change a

  $ glog conv1
  o  3 "5: change a" files: a
  |
  o  2 "4: merge 2 and 3" files: a e
  |
  o  1 "2: copy e from a, change b" files: b e
  |
  o  0 "1: add c, move f to d" files: a b c d
  
  $ cd conv1
  $ hg up -q

Check copy preservation

  $ hg st -C --change 2 e
  M e
  $ hg st -C --change 1 e
  A e
    a
  $ hg st -C --change 0 a
  A a

(It seems like a bug in log that the following doesn't show rev 1.)

  $ hg log --follow --copies e
  changeset:   2:8d3c3fe67bb7
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     4: merge 2 and 3
  
  changeset:   0:23c3be426dce
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     1: add c, move f to d
  
Check copy removal on missing parent

  $ hg log --follow --copies d
  changeset:   0:23c3be426dce
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     1: add c, move f to d
  
  $ hg cat -r tip a b
  a
  a
  a
  b
  b
  $ hg -q verify
  $ cd ..

Convert from merge

  $ hg convert --config convert.hg.startrev=4 source conv4
  initializing destination conv4 repository
  scanning source...
  sorting...
  converting...
  1 4: merge 2 and 3
  0 5: change a
  $ glog conv4
  o  1 "5: change a" files: a
  |
  o  0 "4: merge 2 and 3" files: a b c d e
  
  $ cd conv4
  $ hg up -C
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg cat -r tip a b
  a
  a
  a
  b
  b
  $ hg -q verify
  $ cd ..

Convert from revset in convert.hg.revs

  $ hg convert --config convert.hg.revs='3:4+0' source revsetrepo
  initializing destination revsetrepo repository
  scanning source...
  sorting...
  converting...
  2 0: add a b f
  1 3: change a
  0 4: merge 2 and 3

  $ glog revsetrepo
  o  2 "4: merge 2 and 3" files: b c d e f
  |
  o  1 "3: change a" files: a
  |
  o  0 "0: add a b f" files: a b f
  
Convert from specified revs

  $ hg convert --rev 3 --rev 2 source multiplerevs
  initializing destination multiplerevs repository
  scanning source...
  sorting...
  converting...
  3 0: add a b f
  2 1: add c, move f to d
  1 2: copy e from a, change b
  0 3: change a
  $ glog multiplerevs
  o  3 "3: change a" files: a
  |
  | o  2 "2: copy e from a, change b" files: b e
  | |
  | o  1 "1: add c, move f to d" files: c d f
  |/
  o  0 "0: add a b f" files: a b f
  
Convert in multiple steps that doesn't overlap - the link to the parent is
preserved anyway

  $ hg convert --config convert.hg.revs=::1 source multistep
  initializing destination multistep repository
  scanning source...
  sorting...
  converting...
  1 0: add a b f
  0 1: add c, move f to d
  $ hg convert --config convert.hg.revs=2 source multistep
  scanning source...
  sorting...
  converting...
  0 2: copy e from a, change b
  $ glog multistep
  o  2 "2: copy e from a, change b" files: b e
  |
  o  1 "1: add c, move f to d" files: c d f
  |
  o  0 "0: add a b f" files: a b f