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 serve
creating 'remote
$ hg init remote
$ cd remote
$ hg unbundle "$TESTDIR/bundles/remote.hg"
adding changesets
adding manifests
adding file changes
added 9 changesets with 7 changes to 4 files (+1 heads)
new changesets bfaf4b5cbf01:916f1afdef90 (9 drafts)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg up tip
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Starting server
$ hg serve -p $HGPORT -E ../error.log -d --pid-file=../hg1.pid
$ cd ..
$ cat hg1.pid >> $DAEMON_PIDS
clone remote via stream
$ for i in 0 1 2 3 4 5 6 7 8; do
> hg clone -r "$i" http://localhost:$HGPORT/ test-"$i"
> if cd test-"$i"; then
> hg verify
> cd ..
> fi
> done
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets bfaf4b5cbf01
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 1 changesets with 1 changes to 1 files
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets bfaf4b5cbf01:21f32785131f
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 2 changes to 1 files
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files
new changesets bfaf4b5cbf01:4ce51a113780
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 3 changes to 1 files
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files
new changesets bfaf4b5cbf01:93ee6ab32777
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 4 changesets with 4 changes to 1 files
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets bfaf4b5cbf01:c70afb1ee985
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 2 changes to 1 files
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files
new changesets bfaf4b5cbf01:f03ae5a9b979
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 3 changes to 1 files
adding changesets
adding manifests
adding file changes
added 4 changesets with 5 changes to 2 files
new changesets bfaf4b5cbf01:095cb14b1b4d
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 4 changesets with 5 changes to 2 files
adding changesets
adding manifests
adding file changes
added 5 changesets with 6 changes to 3 files
new changesets bfaf4b5cbf01:faa2e4234c7a
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 5 changesets with 6 changes to 3 files
adding changesets
adding manifests
adding file changes
added 5 changesets with 5 changes to 2 files
new changesets bfaf4b5cbf01:916f1afdef90
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 5 changesets with 5 changes to 2 files
$ cd test-8
$ hg pull ../test-7
pulling from ../test-7
searching for changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 2 changes to 3 files (+1 heads)
new changesets c70afb1ee985:faa2e4234c7a
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 9 changesets with 7 changes to 4 files
$ cd ..
$ cd test-1
$ hg pull -r 4 http://localhost:$HGPORT/
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files (+1 heads)
new changesets c70afb1ee985
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 3 changesets with 2 changes to 1 files
$ hg pull http://localhost:$HGPORT/
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 6 changesets with 5 changes to 4 files
new changesets 4ce51a113780:916f1afdef90
(run 'hg update' to get a working copy)
$ cd ..
$ cd test-2
$ hg pull -r 5 http://localhost:$HGPORT/
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 0 changes to 0 files (+1 heads)
new changesets c70afb1ee985:f03ae5a9b979
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 5 changesets with 3 changes to 1 files
$ hg pull http://localhost:$HGPORT/
pulling from http://localhost:$HGPORT/
searching for changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 4 files
new changesets 93ee6ab32777:916f1afdef90
(run 'hg update' to get a working copy)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 9 changesets with 7 changes to 4 files
$ cd ..
no default destination if url has no path:
$ hg clone http://localhost:$HGPORT/
abort: empty destination path is not valid
[10]
$ cat error.log