TODO: https://github.com/marketplace/actions/python-setup-rye

The goal is to have the new item type know if it represent a copy, a
rename, a deleted rename source, or a regular copy-unrelated item.

I plan to provide a richer version of `TreeDiffEntry` with copy info
(and to make `TreeDiffEntry` itself "poorer"). Most callers want to
know about copies/renames, but at least working copy implementations
probably don't. This patch adds separate `diff_stream()` and
`diff_stream_with_copies()` so we can provide the simpler interface
for callers that don't need copy info.

We now have only one caller, and it's in a different module, so it
makes more sense to move it there.

The support for copy tracing is already simply added to the stream
just before yielding the item, so we can easily implement it as a
stream adapter. That ensures that we use the same logic for the
iterator- and stream-based versions. More importantly, it enables
further cleanups and a simpler interface.

Copy/rename handling is complicated. It seems worth having a module
for it. I'm going to add more content to it next.

There are no callers other than tests and benches.

Diff::default_refinement() will be removed.

So that more tests can leverage diff::diff() helper.

I also removed the fast path for identical inputs. This function is only used by
tests and benches, and production code usually compares content hashes first.

The tree-level conflicts have worked well in practice and we don't
want to allow users to use legacy trees for new commits. We don't
really support legacy trees very well since 0590f8beceb8 anyway.

* Derive a bunch of standard and useful traits for `movement_util::Direction`
as it is a simple type. Importantly `Copy`.
* Return `&'static str` from Direction.cmd()
* Refactor out `MovementArgs` to reduce the number of arguments
to `movement_util::move_to_commit`.
* Implement `From<&NextArgs/&PrevArgs>` for MovementArgs

Part of #3947

This appears to fix redundant " ..." line for empty diffs.

This allows us to select rendering function hunk by hunk. For example, a hunk
with lots of small changes could be rendered without interleaving left/right
words. Another good thing is that context line handling can be simplified as
the whole context hunk is available.

The added functions will be used in order to iterate middle hunks which don't
start from line_number = 1.

I'm going to split color-words diffs to by_line() and by_word() stages.

Perhaps, Diff::default_refinement() can be removed once all non-test callers
are migrated.

This ensures consistency between the commands `jj rebase -r a::` and `jj
rebase -s a`.

We don't currently use the `path()` method. Not all working copies
even have a relevant path. For example, working copies on Google's
server don't.

The code in both cli/src/commands/{next,prev}.rs is identical except
for the direction of movement. This commit pull the parts that make
sense out into cli/src/movement_util.rs so it's easier to see the
differences.

Part of #3947

Add gratuitous `jj log` output to more points in the tests.
This makes it easier to understand the intended changes
by literally visualizing the commit tree we are after each movement.

This is at least useful for me since I find the new+squash workflow
confusing.

Test behaviour is not changed.

Part of #3947

We all noticed that x86 macOS binaries are no longer being provided on release,
due to `macos-11` runners going the way of the Dodo a while back. Nobody
alterted us to this, funny enough.

After some quick discussion, we concluded some things:

- x86 macOS runners are likely oversubscribed, and hurt CI latency badly
- `macos-12` is also deprecated; `macos-13` is the best x86 runner available
- GitHub probably isn't going to expand macOS runner capacity; `macos-13` will
one day go away
- Some people are still using `jj` on Intel Macs. We didn't get alerted because
they do their own builds for now, but may not always do that.
- We can just try to build on `macos-13` and make it optional for merges.

So that's what this does. It might be mergeable outright, but we can also use it
to measure build latency impacts.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

Bumps the cargo-dependencies group with 4 updates in the / directory: [clap](https://github.com/clap-rs/clap), [libc](https://github.com/rust-lang/libc), [serde](https://github.com/serde-rs/serde) and [serde_json](https://github.com/serde-rs/json).


Updates `clap` from 4.5.15 to 4.5.16
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/clap_complete-v4.5.15...clap_complete-v4.5.16)

Updates `libc` from 0.2.155 to 0.2.156
- [Release notes](https://github.com/rust-lang/libc/releases)
- [Changelog](https://github.com/rust-lang/libc/blob/0.2.156/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/libc/compare/0.2.155...0.2.156)

Updates `serde` from 1.0.207 to 1.0.208
- [Release notes](https://github.com/serde-rs/serde/releases)
- [Commits](https://github.com/serde-rs/serde/compare/v1.0.207...v1.0.208)

Updates `serde_json` from 1.0.124 to 1.0.125
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](https://github.com/serde-rs/json/compare/v1.0.124...1.0.125)

---
updated-dependencies:
- dependency-name: clap
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: libc
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: serde
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: serde_json
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

test_diff_basic() is now testing file-level changes such as renames.

Bumps the github-dependencies group with 1 update: [github/codeql-action](https://github.com/github/codeql-action).


Updates `github/codeql-action` from 3.26.1 to 3.26.2
- [Release notes](https://github.com/github/codeql-action/releases)
- [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md)
- [Commits](https://github.com/github/codeql-action/compare/29d86d22a34ea372b1bbf3b2dced2e25ca6b3384...429e1977040da7a23b6822b13c129cd1ba93dbb2)

---
updated-dependencies:
- dependency-name: github/codeql-action
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: github-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

I don't think the iteration cost would matter here, and it doesn't make sense
that has_left/right_content are cached whereas is_unmodified() isn't.

This will simplify users of line.hunks[] which I'm going to add.

I've made the constructor public, so let's add more sanity checks.

Bumps the github-dependencies group with 1 update: [github/codeql-action](https://github.com/github/codeql-action).


Updates `github/codeql-action` from 3.26.0 to 3.26.1
- [Release notes](https://github.com/github/codeql-action/releases)
- [Changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md)
- [Commits](https://github.com/github/codeql-action/compare/eb055d739abdc2e8de2e5f4ba1a8b246daa779aa...29d86d22a34ea372b1bbf3b2dced2e25ca6b3384)

---
updated-dependencies:
- dependency-name: github/codeql-action
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: github-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

I'm thinking of adding some heuristics to render hunks containing lots of
small word changes differently, in a similar manner to the unified diffs. This
patch might help add some pre/post-processing at consumer.

files::diff() is inlined to caller to get around 'self borrowing.

unchanged_ranges() already has the fast path for empty content, but we can
also disable tokenization.

When rebasing a new child commit on top of the moved commit(s), the
order of the new child commit's parent commits is now correctly
preserved if the original parent commit is now a parent of the moved
commit(s).

Closes #3969.

I think they were adding too much noise to commit diffs. Only the tests
focused on skipping rebasing will include the commit and change IDs,
other tests will omit them.

Bumps the cargo-dependencies group with 1 update: [indexmap](https://github.com/indexmap-rs/indexmap).


Updates `indexmap` from 2.3.0 to 2.4.0
- [Changelog](https://github.com/indexmap-rs/indexmap/blob/master/RELEASES.md)
- [Commits](https://github.com/indexmap-rs/indexmap/compare/2.3.0...2.4.0)

---
updated-dependencies:
- dependency-name: indexmap
dependency-type: direct:production
update-type: version-update:semver-minor
dependency-group: cargo-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

This allow `jj show --summary` and other commands to include copy
tracking information.

* Add `builtin_immutable_heads()` in the `revsets.toml`.
* Redefine `immutable_heads()` in terms of `builtin_immutable_heads()`
* Warn if user redefines `builtin_immutable_heads()`, `mutable()` or
`immutable()`.
* Update module constant in revset_util.rs from BUILTIN_IMMUTABLE_HEADS
to USER_IMMUTABLE_HEADS to avoid confusion since it points at
`immutable_heads()` **and** we now have a revset-alias
literally named `builtin_immutable_heads()`.
* Add unittest
* Update CHANGELOG
* Update documentation.

Fixes: #4162

- add support for copy tracking to `diff --stat`
- switch `--summary` to match git's output more closely
- rework `show_diff_summary` signature to be more consistent

Bumps the cargo-dependencies group with 2 updates: [clap_complete](https://github.com/clap-rs/clap) and [serde](https://github.com/serde-rs/serde).


Updates `clap_complete` from 4.5.14 to 4.5.16
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/clap_complete-v4.5.14...clap_complete-v4.5.16)

Updates `serde` from 1.0.206 to 1.0.207
- [Release notes](https://github.com/serde-rs/serde/releases)
- [Commits](https://github.com/serde-rs/serde/compare/v1.0.206...v1.0.207)

---
updated-dependencies:
- dependency-name: clap_complete
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: serde
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

Add home directory expansion for SSH key filepaths. This allows the
`signing.key` configuration value to work more universally across both
Linux and macOS without requiring an absolute path.

This moved and renamed the previous `expand_git_path` function to a more
generic location, and the prior use was updated accordingly.

Perhaps, we should also cache merged trees, but this patch saves time until
we implement the bookkeeping. Even if we had a cache, it wouldn't be ideal to
calculate uncached merged trees during revset evaluation.

```
% hyperfine --sort command --warmup 3 --runs 10 -L bin jj-1,jj-2 \
'target/release-with-debug/{bin} -R ~/mirrors/git --ignore-working-copy \
log -r "::@ & file(root:builtin)" --no-graph -n50'
Benchmark 1: target/release-with-debug/jj-1 ..
Time (mean ± σ): 3.512 s ± 0.014 s [User: 3.391 s, System: 0.119 s]
Range (min … max): 3.489 s … 3.528 s 10 runs

Benchmark 2: target/release-with-debug/jj-2 ..
Time (mean ± σ): 1.351 s ± 0.010 s [User: 1.275 s, System: 0.074 s]
Range (min … max): 1.332 s … 1.366 s 10 runs

Relative speed comparison
2.60 ± 0.02 target/release-with-debug/jj-1 ..
1.00 target/release-with-debug/jj-2 ..
```

I'll add conflict resolution there.

This change adds more synchronization points, which is probably bad for
concurrency. However, this module is a revset engine for the default index,
so the store backends are supposed to be fast local disks.

Conflict resolution is expensive, so I'm going to make file()/diff_contains()
revsets not resolve the whole parent trees.

I'll add a public function that resolves file conflicts. This function will
take owned MergedTreeValue, and that's why the extracted function returns
None instead of cloning the passed value.

This includes a bump of `libgit2` to v1.8.1.

Bumps the cargo-dependencies group with 5 updates:

| Package | From | To |
| --- | --- | --- |
| [clap](https://github.com/clap-rs/clap) | `4.5.14` | `4.5.15` |
| [clap_complete](https://github.com/clap-rs/clap) | `4.5.13` | `4.5.14` |
| [serde](https://github.com/serde-rs/serde) | `1.0.205` | `1.0.206` |
| [serde_json](https://github.com/serde-rs/json) | `1.0.122` | `1.0.124` |
| [syn](https://github.com/dtolnay/syn) | `2.0.72` | `2.0.74` |


Updates `clap` from 4.5.14 to 4.5.15
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/clap_complete-v4.5.14...v4.5.15)

Updates `clap_complete` from 4.5.13 to 4.5.14
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/clap_complete-v4.5.13...clap_complete-v4.5.14)

Updates `serde` from 1.0.205 to 1.0.206
- [Release notes](https://github.com/serde-rs/serde/releases)
- [Commits](https://github.com/serde-rs/serde/compare/v1.0.205...v1.0.206)

Updates `serde_json` from 1.0.122 to 1.0.124
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](https://github.com/serde-rs/json/compare/v1.0.122...v1.0.124)

Updates `syn` from 2.0.72 to 2.0.74
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/2.0.72...2.0.74)

---
updated-dependencies:
- dependency-name: clap
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: clap_complete
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: serde
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: serde_json
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
- dependency-name: syn
dependency-type: direct:production
update-type: version-update:semver-patch
dependency-group: cargo-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

MergedTreeVal was roughly equivalent to Merge<Option<Cow<_>>. As we've dropped
support for the legacy trees, it can be simplified to Merge<Option<&_>>.