Git has a bug [1] whereby running multiple fetch commands at the same time
causes all of them to append their information to the .git/FETCH_HEAD file,
causing the next git pull that wants to use the information to become confused,
and show an error like "Cannot rebase onto multiple branches". This error would
occur when pressing "f" and "p" in quick succession in the files panel, but also
when pressing "p" while a background fetch happens to be running. One likely
situation for this is pressing "p" right after startup.
Since lazygit never uses the information written to .git/FETCH_HEAD, it's best
to avoid writing to it, which fixes the scenarios described above.
However, it doesn't fix the problem of repeatedly pressing "f" quickly on the
checked-out branch; since we call "git pull" in that case, the above fix doesn't
help there. We'll address this separately in another PR.
[1] See https://public-inbox.org/git/xmqqy1daffk8.fsf@gitster.g/ for more
information.
The algorithm works by blaming the deleted lines, so if a hunk contains only
added lines, we can only hope that it also belongs in the same commit. Warn the
user about this.
Note: the warning might be overly agressive, we'll have to see if this is
annoying. The reason is that it depends on the diff context size whether added
lines go into their own hunk or are grouped together with other added or deleted
lines into one hunk. However, our algorithm uses a diff context size of 0,
because that makes it easiest to parse the diff; this results in hunks having
only added lines more often than what the user sees. For example, moving a line
of code down by two lines will likely result in a single hunk for the user, but
in two hunks for our algorithm. On the other hand, being this strict makes the
warning consistent. We could consider using the user's diff context size in the
algorithm, but then it would depend on the current context size whether the
warning appears, which could be confusing. Plus, it would make the algorithm
quite a bit more complicated.
There are two possible fixes for this bug, and they differ in behavior when
rewording a commit. The one I chose here always splits at the first line feed,
which means that for an improperly formatted commit message such as this one:
This is a very long multi-line subject,
which you shouldn't really use in git.
And this is the body (we call it "description" in lazygit).
we split after the first line instead of after the first paragraph. This is
arguably not what the original author meant, but splitting after the first
paragraph doesn't really work well in lazygit, because we would try to put both
lines into the one-line subject field of the message panel, and you'd only see
the second and not even know that there are more.
The other potential fix would have been to join subject and description with two
line feeds instead of one in JoinCommitMessageAndDescription; this would have
fixed our bug in the same way, but would result in splitting the above message
after the second line instead of the first. I think that's worse, so I decided
for the first fix.
While we're at it, simplify the code a little bit; strings.Cut is documented to
return (s, "") when the separator is not found, so there's no need to do this on
our side.
We do have to trim spaces on the description now, to support the regular reword
case where subject and body are separated by a blank line.
SplitCommitMessageAndDescription splits at the first '\n\n' that it finds (if
there is one), which in this case is between the two paragraphs of the
description. This is wrong.
Use git log instead of git rev-list, this way we don't get a line "commit <sha>"
at the beginning that we then have to discard again.
The test TestGetCommitMsg is becoming a bit pointless now, since it just
compares that input and output are identical.
Closes#3187
- **PR Description**
#3187 observes that lazygit crashes with a stack trace if it's run from
a non-existent current working directory. The steps to reproduce are:
```
mkdir test
cd test
rm -r ../test
lazygit
```
(Note: I can repro this on Ubuntu, but not on macOS Sonoma, where
lazygit starts regardless of whether the current working directory
exists or not.)
Here's how the repro steps look on Ubuntu with this PR applied:
```
simon@ubuntu:/Users/simon/src/3p/lazygit$ go build .
simon@ubuntu:/Users/simon/src/3p/lazygit$ mkdir deleteme
simon@ubuntu:/Users/simon/src/3p/lazygit$ cd deleteme/
simon@ubuntu:/Users/simon/src/3p/lazygit/deleteme$ rm -r ../deleteme
simon@ubuntu:/Users/simon/src/3p/lazygit/deleteme$ ../lazygit
2024/01/02 18:40:15 Error: the current working directory does not exist
```
- **Please check if the PR fulfills these requirements**
* [x] Cheatsheets are up-to-date (run `go generate ./...`)
* [x] Code has been formatted (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#code-formatting))
* [x] Tests have been added/updated (see
[here](https://github.com/jesseduffield/lazygit/blob/master/pkg/integration/README.md)
for the integration test guide)
* [x] Text is internationalised (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#internationalisation))
* [x] Docs (specifically `docs/Config.md`) have been updated if
necessary
* [x] You've read through your own file changes for silly mistakes etc
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