Mercurial > hg
view tests/test-eol-clone.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 | 95a615dd77bf |
children | dcaa2df1f688 |
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Testing cloning with the EOL extension $ cat >> $HGRCPATH <<EOF > [extensions] > eol = > > [eol] > native = CRLF > EOF setup repository $ hg init repo $ cd repo $ cat > .hgeol <<EOF > [patterns] > **.txt = native > EOF $ printf "first\r\nsecond\r\nthird\r\n" > a.txt $ hg commit --addremove -m 'checkin' adding .hgeol adding a.txt Test commit of removed .hgeol and how it immediately makes the automatic changes explicit and committable. $ cd .. $ hg clone repo repo-2 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd repo-2 $ cat a.txt first\r (esc) second\r (esc) third\r (esc) $ hg cat a.txt first second third $ hg remove .hgeol $ touch a.txt * # ensure consistent st dirtyness checks, ignoring dirstate timing $ hg st -v --debug M a.txt R .hgeol $ hg commit -m 'remove eol' $ hg exp # HG changeset patch # User test # Date 0 0 # Thu Jan 01 00:00:00 1970 +0000 # Node ID 3c20c2d90333b6ecdc8f7aa8f9b73223c7c7a608 # Parent 90f94e2cf4e24628afddd641688dfe4cd476d6e4 remove eol diff -r 90f94e2cf4e2 -r 3c20c2d90333 .hgeol --- a/.hgeol Thu Jan 01 00:00:00 1970 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,2 +0,0 @@ -[patterns] -**.txt = native diff -r 90f94e2cf4e2 -r 3c20c2d90333 a.txt --- a/a.txt Thu Jan 01 00:00:00 1970 +0000 +++ b/a.txt Thu Jan 01 00:00:00 1970 +0000 @@ -1,3 +1,3 @@ -first -second -third +first\r (esc) +second\r (esc) +third\r (esc) $ hg push --quiet $ cd .. Test clone of repo with .hgeol in working dir, but no .hgeol in default checkout revision tip. The repo is correctly updated to be consistent and have the exact content checked out without filtering, ignoring the current .hgeol in the source repo: $ cat repo/.hgeol [patterns] **.txt = native $ hg clone repo repo-3 -v --debug linked 7 files updating to branch default resolving manifests branchmerge: False, force: False, partial: False ancestor: 000000000000, local: 000000000000+, remote: 3c20c2d90333 calling hook preupdate.eol: hgext.eol.preupdate a.txt: remote created -> g getting a.txt 1 files updated, 0 files merged, 0 files removed, 0 files unresolved updating the branch cache $ cd repo-3 $ cat a.txt first\r (esc) second\r (esc) third\r (esc) Test clone of revision with .hgeol $ cd .. $ hg clone -r 0 repo repo-4 adding changesets adding manifests adding file changes added 1 changesets with 2 changes to 2 files new changesets 90f94e2cf4e2 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd repo-4 $ cat .hgeol [patterns] **.txt = native $ cat a.txt first\r (esc) second\r (esc) third\r (esc) $ cd ..