view tests/test-rename-rev.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

  $ hg init
  $ mkdir d1 d1/d11 d2
  $ echo d1/a > d1/a
  $ echo d1/ba > d1/ba
  $ echo d1/a1 > d1/d11/a1
  $ echo d1/b > d1/b
  $ echo d2/b > d2/b
  $ hg add d1/a d1/b d1/ba d1/d11/a1 d2/b
  $ hg commit -m "intial"


Test single file

# One recorded copy, one copy to record after commit
  $ hg cp d1/b d1/c
  $ cp d1/b d1/d
  $ hg add d1/d
  $ hg ci -m 'copy d1/b to d1/c and d1/d'
  $ hg st -C --change .
  A d1/c
    d1/b
  A d1/d
# Errors out without --after for now
  $ hg cp --at-rev . d1/b d1/d
  abort: --at-rev requires --after
  [10]
# Errors out with non-existent source
  $ hg cp -A --at-rev . d1/non-existent d1/d
  d1/non-existent: no such file in rev 55d1fd85ef0a
  abort: no files to copy
  [10]
# Errors out with non-existent destination
  $ hg cp -A --at-rev . d1/b d1/non-existent
  abort: d1/non-existent: copy destination does not exist in 8a9d70fa20c9
  [10]
# Successful invocation
  $ hg cp -A --at-rev . d1/b d1/d
  saved backup bundle to $TESTTMP/.hg/strip-backup/8a9d70fa20c9-973ae357-copy.hg
# New copy is recorded, and previously recorded copy is also still there
  $ hg st -C --change .
  A d1/c
    d1/b
  A d1/d
    d1/b
# Should get helpful message if we try to copy or rename after commit
  $ hg cp --forget --at-rev . d1/d
  saved backup bundle to $TESTTMP/.hg/strip-backup/3f7c325d3f9e-46f377bb-uncopy.hg
  $ hg cp d1/b d1/d
  d1/d: not overwriting - file already committed
  ('hg copy --at-rev .' to record the copy in the parent of the working copy)
  [1]
  $ hg mv d1/b d1/d
  d1/d: not overwriting - file already committed
  ('hg rename --at-rev .' to record the rename in the parent of the working copy)
  [1]

Test moved file (not copied) using 'hg cp' command

  $ hg co 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mv d1/b d1/d
  $ hg rm -A d1/b
  $ hg add d1/d
  $ hg ci -m 'move d1/b to d1/d'
  created new head
  $ hg cp -A --at-rev . d1/b d1/d
  saved backup bundle to $TESTTMP/.hg/strip-backup/519850c3ea27-153c8fbb-copy.hg
  $ hg st -C --change .
  A d1/d
    d1/b
  R d1/b

Test moved file (not copied) using 'hg mv' command

  $ hg co 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mv d1/b d1/d
  $ hg rm -A d1/b
  $ hg add d1/d
  $ hg ci -m 'move d1/b to d1/d'
  created new head
  $ hg mv -A --at-rev . d1/b d1/d
  saved backup bundle to $TESTTMP/.hg/strip-backup/519850c3ea27-153c8fbb-copy.hg
  $ hg st -C --change .
  A d1/d
    d1/b
  R d1/b

Test moved file (not copied) for which source still exists

  $ hg co 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cp d1/b d1/d
  $ hg add d1/d
  $ hg ci -m 'copy d1/b to d1/d'
  created new head
  $ hg mv -A --at-rev . d1/b d1/d
  saved backup bundle to $TESTTMP/.hg/strip-backup/c8d0f6bcf7ca-1c9bb53e-copy.hg
  $ hg st -C --change .
  A d1/d
    d1/b

Test using directory as destination

  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cp -R d1 d3
  $ hg add d3
  adding d3/a
  adding d3/b
  adding d3/ba
  adding d3/d11/a1
  $ hg ci -m 'copy d1/ to d3/'
  created new head
  $ hg cp -A --at-rev . d1 d3
  abort: d3: --at-rev does not support a directory as destination
  [10]