view tests/test-convert-datesort.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=
  > EOF
  $ hg init t
  $ cd t
  $ echo a >> a
  $ hg ci -Am a0 -d '1 0'
  adding a
  $ hg branch brancha
  marked working directory as branch brancha
  (branches are permanent and global, did you want a bookmark?)
  $ echo a >> a
  $ hg ci -m a1 -d '2 0'
  $ echo a >> a
  $ hg ci -m a2 -d '3 0'
  $ echo a >> a
  $ hg ci -m a3 -d '4 0'
  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch branchb
  marked working directory as branch branchb
  $ echo b >> b
  $ hg ci -Am b0 -d '6 0'
  adding b
  $ hg up -C brancha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a >> a
  $ hg ci -m a4 -d '5 0'
  $ echo a >> a
  $ hg ci -m a5 -d '7 0'
  $ echo a >> a
  $ hg ci -m a6 -d '8 0'
  $ hg up -C branchb
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b >> b
  $ hg ci -m b1 -d '9 0'
  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c >> c
  $ hg branch branchc
  marked working directory as branch branchc
  $ hg ci -Am c0 -d '10 0'
  adding c
  $ hg up -C brancha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg ci --close-branch -m a7x -d '11 0'
  $ hg up -C branchb
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg ci --close-branch -m b2x -d '12 0'
  $ hg up -C branchc
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge branchb
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m c1 -d '13 0'
  $ cd ..

convert with datesort

  $ hg convert --datesort t t-datesort
  initializing destination t-datesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 a4
  7 b0
  6 a5
  5 a6
  4 b1
  3 c0
  2 a7x
  1 b2x
  0 c1

graph converted repo

  $ hg -R t-datesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | _  11 "b2x"
  | |
  | | _  10 "a7x"
  | | |
  o | |  9 "c0"
  | | |
  | o |  8 "b1"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | o |  5 "b0"
  |/ /
  | o  4 "a4"
  | |
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"
  

convert with datesort (default mode)

  $ hg convert t t-sourcesort
  initializing destination t-sourcesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 b0
  7 a4
  6 a5
  5 a6
  4 b1
  3 c0
  2 a7x
  1 b2x
  0 c1

graph converted repo

  $ hg -R t-sourcesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | _  11 "b2x"
  | |
  | | _  10 "a7x"
  | | |
  o | |  9 "c0"
  | | |
  | o |  8 "b1"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | | o  5 "a4"
  | | |
  | o |  4 "b0"
  |/ /
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"
  

convert with closesort

  $ hg convert --closesort t t-closesort
  initializing destination t-closesort repository
  scanning source...
  sorting...
  converting...
  12 a0
  11 a1
  10 a2
  9 a3
  8 b0
  7 a4
  6 a5
  5 a6
  4 a7x
  3 b1
  2 b2x
  1 c0
  0 c1

graph converted repo

  $ hg -R t-closesort log -G --template '{rev} "{desc}"\n'
  o    12 "c1"
  |\
  | o  11 "c0"
  | |
  _ |  10 "b2x"
  | |
  o |  9 "b1"
  | |
  | | _  8 "a7x"
  | | |
  | | o  7 "a6"
  | | |
  | | o  6 "a5"
  | | |
  | | o  5 "a4"
  | | |
  o | |  4 "b0"
  |/ /
  | o  3 "a3"
  | |
  | o  2 "a2"
  | |
  | o  1 "a1"
  |/
  o  0 "a0"