view tests/test-narrow-merge-outside.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

===================================================================
Test merge behavior with narrow for item outside of the narrow spec
===================================================================

This test currently check for  simple "outside of narrow" merge case. I suspect
there might be more corner case that need testing, so extending this tests, or
replacing it by a more "generative" version, comparing behavior with and without narow.

This the feature is currently working with flat manifest only. This is the only
case tested. Consider using test-case if tree start supporting this case of
merge.

Create some initial setup

  $ . "$TESTDIR/narrow-library.sh"

  $ hg init server
  $ echo root > server/root
  $ mkdir server/inside
  $ mkdir server/outside
  $ echo babar > server/inside/inside-change
  $ echo pom > server/outside/outside-changing
  $ echo arthur > server/outside/outside-removed
  $ hg -R server add server/
  adding server/inside/inside-change
  adding server/outside/outside-changing
  adding server/outside/outside-removed
  adding server/root
  $ hg -R server commit -m root



  $ hg clone ssh://user@dummy/server client --narrow --include inside
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets a0c415d360e5
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

"trivial" change outside of narrow spec on the server

  $ echo zephir > server/outside/outside-added
  $ hg -R server add server/outside/outside-added
  $ echo flore > server/outside/outside-changing
  $ hg -R server remove server/outside/outside-removed
  $ hg -R server commit -m "outside change"

Merge them with some unrelated local change

  $ echo celeste > client/inside/inside-change
  $ hg -R client commit -m "inside change"
  $ hg -R client pull
  pulling from ssh://user@dummy/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets f9ec5453023e
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg -R client merge
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg -R client ci -m 'merge changes'
  $ hg -R client push -r .
  pushing to ssh://user@dummy/server
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 2 changesets with 1 changes to 1 files

Checking result
---------------

general sentry of all output

  $ hg --repository server manifest --debug --rev 0
  360afd990eeff79e4a7f9f3ded5ecd7bc2fd3b59 644   inside/inside-change
  7db95ce5cd8e734ad12e3f5f37779a08070a1399 644   outside/outside-changing
  1591f6db41a30b68bd94ddccf4a4ce4f4fbe2a44 644   outside/outside-removed
  50ecbc31c0e82dd60c2747c434d1f11b85c0e178 644   root
  $ hg --repository server manifest --debug --rev 1
  360afd990eeff79e4a7f9f3ded5ecd7bc2fd3b59 644   inside/inside-change
  486c008d6dddcaeb5e5f99556a121800cdcfb149 644   outside/outside-added
  153d7af5e4f53f44475bc0ff2b806c86f019eda4 644   outside/outside-changing
  50ecbc31c0e82dd60c2747c434d1f11b85c0e178 644   root

  $ hg --repository server manifest --debug --rev 2
  1b3ab69c6c847abc8fd25537241fedcd4d188668 644   inside/inside-change
  7db95ce5cd8e734ad12e3f5f37779a08070a1399 644   outside/outside-changing
  1591f6db41a30b68bd94ddccf4a4ce4f4fbe2a44 644   outside/outside-removed
  50ecbc31c0e82dd60c2747c434d1f11b85c0e178 644   root
  $ hg --repository server manifest --debug --rev 3
  1b3ab69c6c847abc8fd25537241fedcd4d188668 644   inside/inside-change
  486c008d6dddcaeb5e5f99556a121800cdcfb149 644   outside/outside-added
  153d7af5e4f53f44475bc0ff2b806c86f019eda4 644   outside/outside-changing
  50ecbc31c0e82dd60c2747c434d1f11b85c0e178 644   root

The file changed outside should be changed by the merge

  $ hg --repository server manifest --debug --rev 'desc("inside change")' | grep outside-changing
  7db95ce5cd8e734ad12e3f5f37779a08070a1399 644   outside/outside-changing

  $ hg --repository server manifest --debug --rev 'desc("outside change")' | grep outside-changing
  153d7af5e4f53f44475bc0ff2b806c86f019eda4 644   outside/outside-changing
  $ hg --repository server manifest --debug --rev 'desc("merge")' | grep outside-changing
  153d7af5e4f53f44475bc0ff2b806c86f019eda4 644   outside/outside-changing