view tests/test-mq-qfold.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 <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [mq]
  > git = keep
  > [diff]
  > nodates = 1
  > EOF

init:

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg qnew -f p1
  $ echo b >> a
  $ hg qnew -f p2
  $ echo c >> a
  $ hg qnew -f p3

Fold in the middle of the queue:
(this tests also that editor is not invoked if '--edit' is not
specified)

  $ hg qpop p1
  popping p3
  popping p2
  now at: p1

  $ hg qdiff
  diff -r 07f494440405 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,2 @@
   a
  +a

  $ HGEDITOR=cat hg qfold p2
  $ grep git .hg/patches/p1 && echo 'git patch found!'
  [1]

  $ hg qser
  p1
  p3

  $ hg qdiff
  diff -r 07f494440405 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,3 @@
   a
  +a
  +b

Fold with local changes:

  $ echo d >> a
  $ hg qfold p3
  abort: local changes found, qrefresh first
  [255]

  $ hg diff -c .
  diff -r 07f494440405 -r ???????????? a (glob)
  --- a/a
  +++ b/a
  @@ -1,1 +1,3 @@
   a
  +a
  +b

  $ hg revert -a --no-backup
  reverting a

Fold git patch into a regular patch, expect git patch:

  $ echo a >> a
  $ hg qnew -f regular
  $ hg cp a aa
  $ hg qnew --git -f git

  $ hg qpop
  popping git
  now at: regular

  $ hg qfold git

  $ cat .hg/patches/regular
  # HG changeset patch
  # Parent  ???????????????????????????????????????? (glob)
  
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,3 +1,4 @@
   a
   a
   b
  +a
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,3 +1,4 @@
   a
   a
   b
  +a

  $ hg qpop
  popping regular
  now at: p1

  $ hg qdel regular

Fold regular patch into a git patch, expect git patch:

  $ hg cp a aa
  $ hg qnew --git -f git
  $ echo b >> aa
  $ hg qnew -f regular

  $ hg qpop
  popping regular
  now at: git

  $ hg qfold regular

  $ cat .hg/patches/git
  # HG changeset patch
  # Parent  ???????????????????????????????????????? (glob)
  
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,3 +1,4 @@
   a
   a
   b
  +b

Test saving last-message.txt:

  $ hg qrefresh -m "original message"

  $ cat > $TESTTMP/commitfailure.py <<EOF
  > from mercurial import error
  > def reposetup(ui, repo):
  >     class commitfailure(repo.__class__):
  >         def commit(self, *args, **kwargs):
  >             raise error.Abort(b'emulating unexpected abort')
  >     repo.__class__ = commitfailure
  > EOF

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > # this failure occurs before editor invocation
  > commitfailure = $TESTTMP/commitfailure.py
  > EOF

  $ cat > $TESTTMP/editor.sh << EOF
  > echo "==== before editing"
  > cat \$1
  > echo "===="
  > (echo; echo "test saving last-message.txt") >> \$1
  > EOF

  $ hg qapplied
  p1
  git
  $ hg tip --template "{files}\n"
  aa

(test that editor is not invoked before transaction starting,
and that combination of '--edit' and '--message' doesn't abort execution)

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e -m MESSAGE p3
  qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
  abort: emulating unexpected abort
  [255]
  $ test -f .hg/last-message.txt
  [1]

(reset applied patches and directory status)

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > # this failure occurs after editor invocation
  > commitfailure = !
  > EOF

  $ hg qapplied
  p1
  $ hg status -A aa
  ? aa
  $ rm aa
  $ hg status -m
  M a
  $ hg revert --no-backup -q a
  $ hg qpush -q git
  now at: git

(test that editor is invoked and commit message is saved into
"last-message.txt")

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > # this failure occurs after editor invocation
  > pretxncommit.unexpectedabort = false
  > EOF

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e p3
  ==== before editing
  original message
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to use default message.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added aa
  HG: changed a
  ====
  note: commit message saved in .hg/last-message.txt
  note: use 'hg commit --logfile .hg/last-message.txt --edit' to reuse it
  transaction abort!
  rollback completed
  qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
  abort: pretxncommit.unexpectedabort hook exited with status 1
  [40]
  $ cat .hg/last-message.txt
  original message
  
  
  
  test saving last-message.txt

(confirm whether files listed up in the commit message editing are correct)

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > pretxncommit.unexpectedabort =
  > EOF
  $ hg status -u | while read f; do rm ${f}; done
  $ hg revert --no-backup -q --all
  $ hg qpush -q git
  now at: git
  $ hg qpush -q --move p3
  now at: p3

  $ hg status --rev "git^1" --rev . -arm
  M a
  A aa

  $ cd ..