view tests/test-mq-pull-from-bundle.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

#require repobundlerepo

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq=
  > [alias]
  > tlog = log --template "{rev}: {node|short} {desc}\\n"
  > theads = heads --template "{rev}: {desc}\\n"
  > tincoming = incoming --template "{rev}: {desc}\\n"
  > EOF

Setup main:

  $ hg init base
  $ cd base
  $ echo "One" > one
  $ hg add
  adding one
  $ hg ci -m "main: one added"
  $ echo "++" >> one
  $ hg ci -m "main: one updated"

Bundle main:

  $ hg bundle --base=null ../main.hg
  2 changesets found

  $ cd ..

Incoming to fresh repo:

  $ hg init fresh

  $ hg -R fresh tincoming main.hg
  comparing with main.hg
  0: main: one added
  1: main: one updated
  $ test -f ./fresh/.hg/hg-bundle* && echo 'temp. bundle file remained' || true

  $ hg -R fresh tincoming bundle:fresh+main.hg
  comparing with bundle:fresh+main.hg
  0: main: one added
  1: main: one updated


Setup queue:

  $ cd base
  $ hg qinit -c
  $ hg qnew -m "patch: two added" two.patch
  $ echo two > two
  $ hg add
  adding two
  $ hg qrefresh
  $ hg qcommit -m "queue: two.patch added"
  $ hg qpop -a
  popping two.patch
  patch queue now empty

Bundle queue:

  $ hg -R .hg/patches bundle --base=null ../queue.hgq
  1 changesets found
  $ test -f ./fresh/.hg/hg-bundle* && echo 'temp. bundle file remained' || true

  $ cd ..


Clone base:

  $ hg clone base copy
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd copy
  $ hg qinit -c

Incoming queue bundle:

  $ hg -R .hg/patches tincoming ../queue.hgq
  comparing with ../queue.hgq
  0: queue: two.patch added
  $ test -f .hg/hg-bundle* && echo 'temp. bundle file remained' || true

Pull queue bundle:

  $ hg -R .hg/patches pull --update ../queue.hgq
  pulling from ../queue.hgq
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets d7553909353d (1 drafts)
  merging series
  2 files updated, 1 files merged, 0 files removed, 0 files unresolved
  $ test -f .hg/patches/hg-bundle* && echo 'temp. bundle file remained' || true

  $ hg -R .hg/patches theads
  0: queue: two.patch added

  $ hg -R .hg/patches tlog
  0: d7553909353d queue: two.patch added

  $ hg qseries
  two.patch

  $ cd ..


Clone base again:

  $ hg clone base copy2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd copy2
  $ hg qinit -c

Unbundle queue bundle:

  $ hg -R .hg/patches unbundle --update ../queue.hgq
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets d7553909353d (1 drafts)
  merging series
  2 files updated, 1 files merged, 0 files removed, 0 files unresolved

  $ hg -R .hg/patches theads
  0: queue: two.patch added

  $ hg -R .hg/patches tlog
  0: d7553909353d queue: two.patch added

  $ hg qseries
  two.patch

  $ cd ..