This adds support for having conflicting git refs in the view, but we
never create conflicts yet. The `git_refs()` revset includes all "add"
sides of any conflicts. Similarly `origin/main` (for example) resolves
to all "adds" if it's conflicted (meaning that `jj co origin/main` and
many other commands will error out if `origin/main` is
conflicted). The `git_refs` template renders the reference for all
"adds" and adds a "?" as suffix for conflicted refs.
The reason I'm adding this now is not because it's high priority on
its own (it's likely extremely uncommon to run two concurrent `jj git
refresh` and *also* update refs in the underlying git repo at the same
time) but because it's a building block for the branch support I've
planned (issue #21).
I suspect that at least one reason that I didn't make
`MutableRepo::base_repo` by an `Arc<ReadonlyRepo>` before was that I
thought that that would mean that `start_transaction()` would need be
moved off of `ReadonlyRepo` so it can be given an
`&Arc<ReadonlyRepo>`, which would make it much less convenient to
use. It turns out that a `self` argument can actually be of type
`&Arc<ReadonlyRepo>`.
With lots of callbacks replaced by iterators, we are now ready to
propagate most cases of `BrokenPipe` errors to the top-level
`dispatch()` function where it gets ignored and we exit with an error
code.
I want to keep the index updated within the transaction. I tried doing
that by adding a `trait Index`, implemented by `ReadonlyIndex` and
`MutableIndex`. However, `ReadonlyRepo::index` is of type
`Mutex<Option<Arc<IndexFile>>>` (because it is lazily initialized),
and we cannot get a `&dyn Index` that lives long enough to be returned
from a `Repo::index()` from that. It seems the best solution is to
instead create an `Index` enum (instead of a trait), with one readonly
and one mutable variant. This commit starts the migration to that
design by replacing the `Repo` trait by an enum. I never intended for
there there to be more implementations of `Repo` than `ReadonlyRepo`
and `MutableRepo` anyway.
They're rendered as a single string created by joining the refs by
spaces because we don't have any support in the template language for
rendering a list.
I'm preparing to publish an early version before someone takes the
name(s) on crates.io. "jj" has been taken by a seemingly useless
project, but "jujube" and "jujube-lib" are still available, so let's
use those.
