Mercurial > hg
view tests/test-mq-safety.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
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | 4441705b7111 |
children |
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$ echo '[extensions]' >> $HGRCPATH $ echo 'hgext.mq =' >> $HGRCPATH $ hg init repo $ cd repo $ echo foo > foo $ hg ci -qAm 'add a file' $ hg qinit $ hg qnew foo $ echo foo >> foo $ hg qrefresh -m 'append foo' $ hg qnew bar $ echo bar >> foo $ hg qrefresh -m 'append bar' Try to operate on public mq changeset $ hg qpop popping bar now at: foo $ hg phase --public qbase $ echo babar >> foo $ hg qref abort: cannot qrefresh public revision (see 'hg help phases' for details) [255] $ hg revert -a reverting foo $ hg qpop abort: popping would remove a public revision (see 'hg help phases' for details) [255] $ hg qfold bar abort: cannot qrefresh public revision (see 'hg help phases' for details) [255] $ hg revert -a reverting foo restore state for remaining test $ hg qpush applying bar now at: bar try to commit on top of a patch $ echo quux >> foo $ hg ci -m 'append quux' abort: cannot commit over an applied mq patch [255] cheat a bit... $ mv .hg/patches .hg/patches2 $ hg ci -m 'append quux' $ mv .hg/patches2 .hg/patches qpop/qrefresh on the wrong revision $ hg qpop abort: popping would remove a revision not managed by this patch queue [255] $ hg qpop -n patches using patch queue: $TESTTMP/repo/.hg/patches abort: popping would remove a revision not managed by this patch queue [255] $ hg qrefresh abort: working directory revision is not qtip [255] $ hg up -C qtip 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg qpop abort: popping would remove a revision not managed by this patch queue [255] $ hg qrefresh abort: cannot qrefresh a revision with children [255] $ hg tip --template '{rev} {desc}\n' 3 append quux qpush warning branchheads $ cd .. $ hg init branchy $ cd branchy $ echo q > q $ hg add q $ hg qnew -f qp $ hg qpop popping qp patch queue now empty $ echo a > a $ hg ci -Ama adding a $ hg up null 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg branch b marked working directory as branch b (branches are permanent and global, did you want a bookmark?) $ echo c > c $ hg ci -Amc adding c $ hg merge default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -mmerge $ hg up default 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg log changeset: 2:65309210bf4e branch: b tag: tip parent: 1:707adb4c8ae1 parent: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: merge changeset: 1:707adb4c8ae1 branch: b parent: -1:000000000000 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a $ hg qpush applying qp now at: qp Testing applied patches, push and --force $ cd .. $ hg init forcepush $ cd forcepush $ echo a > a $ hg ci -Am adda adding a $ echo a >> a $ hg ci -m changea $ hg up 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg branch branch marked working directory as branch branch (branches are permanent and global, did you want a bookmark?) $ echo b > b $ hg ci -Am addb adding b $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg --cwd .. clone -r 0 forcepush forcepush2 adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files new changesets 07f494440405 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo a >> a $ hg qnew patch Pushing applied patch with --rev without --force $ hg push -r . ../forcepush2 pushing to ../forcepush2 abort: source has mq patches applied [255] Pushing applied patch with branchhash, without --force $ hg push ../forcepush2#default pushing to ../forcepush2 abort: source has mq patches applied [255] Pushing revs excluding applied patch $ hg push --new-branch -r 'branch(branch)' -r 2 ../forcepush2 pushing to ../forcepush2 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files Pushing applied patch with --force $ hg phase --force --secret 'mq()' $ hg push --force -r default ../forcepush2 pushing to ../forcepush2 searching for changes no changes found (ignored 1 secret changesets) [1] $ hg phase --draft 'mq()' $ hg push --force -r default ../forcepush2 pushing to ../forcepush2 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files (+1 heads) $ cd ..