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

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 ..