Bright green really pops on my screen, and I don't think there is a reason
for the root commit to be attention-grabbing.
This follows up on https://github.com/martinvonz/jj/pull/2084.
The syntax is slightly different from Mercurial. In Mercurial, a pattern must
be quoted like "<kind>:<needle>". In JJ, <kind> is a separate parsing node, and
it must not appear in a quoted string. This allows us to report unknown prefix
as an error.
There's another subtle behavior difference. In Mercurial, branch(unknown) is
an error, whereas our branches(literal:unknown) is resolved to an empty set.
I think erroring out doesn't make sense for JJ since branches() by default
performs substring matching, so its behavior is more like a filter.
The parser abuses DAG range syntax for now. It can be rewritten once we remove
the deprecated x:y range syntax.
One use case for `jj split` is when creating a new commit from some of
the changes in the working copy. If there's no description on the
working-copy commit in that case, it seems better to not ask the user
to provide one when they're splitting the commit either.
I've extracted the `builtin_log_root` template for users to customize the
default templates without fully overriding them, for example I would remove
the change_id/commit_id for myself - and we discussed in Discord that leaving
those makes sense for the user to be reminded/teached that the root commit has
a change id made from z's.
This basically means that heads in a filtered graph appear in reverse
chronological order. Before, "jj log -r 'tags()'" in linux-stable repo would
look randomly sorted once you ran "jj debug reindex" in it.
With this change, indexing is more like breadth-first search, and BFS is
known to be bad at rendering nice graph (because branches run in parallel.)
However, we have a post process to group topological branches, so we don't
have this problem. For serialization formats like Mercurial's revlog iirc,
BFS leads to bad compression ratio, but our index isn't that kind of data.
Reindexing gets slightly slower, but I think this is negligible.
(in Git repository)
% hyperfine --warmup 3 --runs 10 "jj debug reindex --ignore-working-copy"
(original)
Time (mean ± σ): 1.521 s ± 0.027 s [User: 1.307 s, System: 0.211 s]
Range (min … max): 1.486 s … 1.573 s 10 runs
(new)
Time (mean ± σ): 1.568 s ± 0.027 s [User: 1.368 s, System: 0.197 s]
Range (min … max): 1.531 s … 1.625 s 10 runs
Another idea is to sort heads chronologically and run DFS-based topological
sorting. It's ad-hoc, but worked surprisingly well for my local repositories.
For repositories with lots of long-running branches, this commit will provide
more predictable result than DFS-based one.
`jj chmod` won't operate on conflicts involving non-files on the
positive sides. However, the error message says "None of the sides of
the conflict are files", which is not correct.
That is, jj will use ui.default_description as a starting point when
user is about to describe an empty change.
I think it might be confusing to do this with -m / --stdin (violates
WYSIWYG), so I'm only doing this when jj invokes an editor.
Also, this could evolve into a proper template in the future instead of
just plain text, to allow inheriting from parent change(s), for example.
Partially addresses #1354.
We anyway trim the newlines eventually and this just does that eagerly
so we output the "correct" description back to stdout (on describe for
example, we'd now print the first non empty line).
Empty files can be confusing in diff output. For example:
```
Added regular file file1:
Added regular file file2:
1: foo
```
This commit adds an "(empty)" placeholder instead. Since it's not
colored, and doesn't have line numbers, it will hopefully not be
mistaken for a file with the contents "(empty)".
AFAIK, we can't make HEAD detached in an empty Git repository, so we need
to temporarily switch to the new default branch before checking out.
Fixes#2047
They are shown next to the change and commit id, since they are other names the
commit can be referred by.
The description is separated from the branches by a ` | ` when there are
branches, so that one can tell the branches from the description without color.
The result looks like this: 
Maybe we could load GitBackend without resolving .git symlink, but that would
introduce more subtle bugs. Instead, we calculate the expected Git workdir path
from the canonical ".git" path.
Fixes#2011
