This follows up on https://github.com/martinvonz/jj/pull/3459 and adds a
label to the closing delimeter of each conflict, e.g. "Conflict 1 of 3
ends".
I didn't initially put any label at the ending delimeter since the
starting delimeter is already marked with "Conflict 1 of 3". However,
I'm now realizing that when I resolve conflicts, I usually go from top
to bottom. The first thing I do is delete the starting conflict
delimeter. It is when I get to the *end* of the conflict that I wonder
whether there are any more conflicts left in the file.
For example,
```
<<<<<<< Conflict 1 of 3
+++++++ Contents of side #1
left 3.1
left 3.2
left 3.3
%%%%%%% Changes from base to side #2
-line 3
+right 3.1
>>>>>>>
```
or
```
<<<<<<< Conflict 1 of 1
%%%%%%% Changes from base to side #1
-line 3
+right 3.1
+++++++ Contents of side #2
left 3.1
left 3.2
left 3.3
>>>>>>>
```
Currently, there is no way to disable these, this is TODO for a future
PR. Other TODOs for future PRs: make these labels configurable. After
that, we could support a `diff3/git`-like conflict format as well, in
principle.
Counting conflicts helps with knowing whether you fixed all the
conflicts while you are in the editor.
While labeling "side #1", etc, does not tell you the commit id or
description as requested in #1176, I still think it's an improvement.
Most importantly, I hope this will make `jj`'s conflict format less
scary-looking for new users.
I've used this for a bit, and I like it. Without the labels, I would see
that the two conflicts have a different order of conflict markers, but I
wouldn't be able to remember what that means. For longer diffs, it can
be tricky for me to quickly tell that it's a diff as opposed to one of
the sides. This also creates some hope of being able to navigate a
conflict with more than 2 sides.
Another not-so-secret goal for this is explained in
https://github.com/martinvonz/jj/pull/3109#issuecomment-2014140627. The
idea is a little weird, but I *think* it could be helpful, and I'd like
to experiment with it.
this greatly speeds up the time to run all tests, at the cost of slightly larger recompile times for individual tests.
this unfortunately adds the requirement that all tests are listed in `runner.rs` for the crate.
to avoid forgetting, i've added a new test that ensures the directory is in sync with the file.
## benchmarks
before this change, recompiling all tests took 32-50 seconds and running a single test took 3.5 seconds:
```
; hyperfine 'touch lib/src/lib.rs && cargo t --test test_working_copy'
Time (mean ± σ): 3.543 s ± 0.168 s [User: 2.597 s, System: 1.262 s]
Range (min … max): 3.400 s … 3.847 s 10 runs
```
after this change, recompiling all tests take 4 seconds:
```
; hyperfine 'touch lib/src/lib.rs ; cargo t --test runner --no-run'
Time (mean ± σ): 4.055 s ± 0.123 s [User: 3.591 s, System: 1.593 s]
Range (min … max): 3.804 s … 4.159 s 10 runs
```
and running a single test takes about the same:
```
; hyperfine 'touch lib/src/lib.rs && cargo t --test runner -- test_working_copy'
Time (mean ± σ): 4.129 s ± 0.120 s [User: 3.636 s, System: 1.593 s]
Range (min … max): 3.933 s … 4.346 s 10 runs
```
about 1.4 seconds of that is the time for the runner, of which .4 is the time for the linker. so
there may be room for further improving the times.
This switches the whole `diff_util` module to working with
`MergedTree`, `Merge<Option<TreeValue>>` etc., so it can support
tree-level conflicts.
Since we want to avoid using `ConflictId`s, I switched the hash we use
for conflicts in `--git` style diffs to use an all-'0' id instead of
using the conflict id.
