view relnotes/5.2 @ 50682:2cc5de261d76

rust-hg-core: move from `ouroboros` to `self_cell`

`ouroboros` has a fundamental soundness problem that, while not applicable
today, could become applicable given new compiler optimizations.¹

`self_cell` is a crate that accomplishes a lot of the same things that
`ouroboros` did while remaining sound (that is, unless a new soundness issue
is discovered) by not assuming as much about the memory layout of the program.
`self_cell` has been scrutinized heavily in the past few months by very
competent people, some from the compiler team and has shown no weaknesses
for a while, with a 1.0 stable release coming out a couple months ago.

Our internal API is exactly the same, this is just an implementation detail.
To reiterate, no actual soundness issue was found with our use of `ouroboros`,
but there might be evolutions of `rustc` (or even a future separate compiler)
that could generate unsound code.

[1] https://github.com/joshua-maros/ouroboros/issues/88

== New Features ==

 * The amend extension supports the `--currentuser` argument.

 * The amend extension supports the `--close-branch` argument.

 * The amend extension supports the `--secret` argument.

 * The uncommit extension supports the `rewrite.update-timestamp` config option.

== New Experimental Features ==


== Bug Fixes  ==


== Backwards Compatibility Changes ==

 * A shell that supports `$(command)`` syntax for command substitution is now
   required for running the test suite. The test runner normally uses
   `sh`, so if that is a shell that doesn't support `$(command)` syntax,
   you can override it by setting `$HGTEST_SHELL` or by passing it to
   `run-tests.py --shell <shell>`.

 * The (experimental) narrow extension's wire protocol changed. If
   you're using it, you'll need to make sure to upgrade server and
   client at the same time.

== Internal API Changes ==