Mercurial > hg
view tests/test-mq-merge.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 | 4152183acedd |
children |
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Setup extension: $ cat <<EOF >> $HGRCPATH > [extensions] > mq = > [mq] > git = keep > EOF Test merge with mq changeset as the second parent: $ hg init m $ cd m $ touch a b c $ hg add a $ hg commit -m a $ hg add b $ hg qnew -d "0 0" b $ hg update 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg add c $ hg commit -m c created new head $ hg merge 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -m merge abort: cannot commit over an applied mq patch [255] $ cd .. Issue529: mq aborts when merging patch deleting files $ checkundo() > { > if [ -f .hg/store/undo ]; then > echo ".hg/store/undo still exists" > fi > } Commit two dummy files in "init" changeset: $ hg init t $ cd t $ echo a > a $ echo b > b $ hg ci -Am init adding a adding b $ hg tag -l init Create a patch removing a: $ hg qnew rm_a $ hg rm a $ hg qrefresh -m "rm a" Save the patch queue so we can merge it later: $ hg qsave -c -e copy $TESTTMP/t/.hg/patches to $TESTTMP/t/.hg/patches.1 $ checkundo Update b and commit in an "update" changeset: $ hg up -C init 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo b >> b $ hg st M b $ hg ci -m update created new head # Here, qpush used to abort with : # The system cannot find the file specified => a $ hg manifest a b $ hg qpush -a -m merging with queue at: $TESTTMP/t/.hg/patches.1 applying rm_a now at: rm_a $ checkundo $ hg manifest b Ensure status is correct after merge: $ hg qpop -a popping rm_a popping .hg.patches.merge.marker patch queue now empty $ cd .. Classic MQ merge sequence *with an explicit named queue*: $ hg init t2 $ cd t2 $ echo '[diff]' > .hg/hgrc $ echo 'nodates = 1' >> .hg/hgrc $ echo a > a $ hg ci -Am init adding a $ echo b > a $ hg ci -m changea $ hg up -C 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg cp a aa $ echo c >> a $ hg qnew --git -f -e patcha $ echo d >> a $ hg qnew -d '0 0' -f -e patcha2 Create the reference queue: $ hg qsave -c -e -n refqueue copy $TESTTMP/t2/.hg/patches to $TESTTMP/t2/.hg/refqueue $ hg up -C 1 1 files updated, 0 files merged, 1 files removed, 0 files unresolved Merge: $ HGMERGE=internal:other hg qpush -a -m -n refqueue merging with queue at: $TESTTMP/t2/.hg/refqueue applying patcha patching file a Hunk #1 succeeded at 2 with fuzz 1 (offset 0 lines). fuzz found when applying patch, stopping patch didn't work out, merging patcha 1 files updated, 0 files merged, 1 files removed, 0 files unresolved 0 files updated, 2 files merged, 0 files removed, 0 files unresolved applying patcha2 now at: patcha2 Check patcha is still a git patch: $ cat .hg/patches/patcha # HG changeset patch # Parent d3873e73d99ef67873dac33fbcc66268d5d2b6f4 diff --git a/a b/a --- a/a +++ b/a @@ -1,1 +1,2 @@ -b +a +c diff --git a/a b/aa copy from a copy to aa --- a/a +++ b/aa @@ -1,1 +1,1 @@ -b +a Check patcha2 is still a regular patch: $ cat .hg/patches/patcha2 # HG changeset patch # Date 0 0 # Parent ???????????????????????????????????????? (glob) diff -r ???????????? -r ???????????? a (glob) --- a/a +++ b/a @@ -1,2 +1,3 @@ a c +d $ cd ..