Add git blame

[mrnugget]

This adds a new action to the editor: editor: toggle git blame. When used it turns on a sidebar containing git blame information for the currently open buffer.

The git blame information is updated when the buffer changes. It handles additions, deletions, modifications, changes to the underlying git data (new commits, changed commits, ...), file saves. It also handles folding and wrapping lines correctly.

When the user hovers over a commit, a tooltip displays information for the commit that introduced the line. If the repository has a remote with the name origin configured, then clicking on a blame entry opens the permalink to the commit on the code host.

Users can right-click on a blame entry to get a context menu which allows them to copy the SHA of the commit.

The feature also works on shared projects, e.g. when collaborating a peer can request git blame data.

As of this PR, Zed now comes bundled with a git binary so that users don't have to have git installed locally to use this feature.

Screenshots

TODOs

• Bundling git binary

Release Notes

Release Notes:

• Added editor: toggle git blame command that toggles a sidebar with git blame information for the current buffer.

[baldwindavid]

This will be a very handy feature. This is out of scope for now but, while I use blame in VSCode, 99% of the time it's a hover to see which PR introduced the commit and to click the link to view the PR on Github.

[JosephTLyons]

Oooooh! If this prototype goes through, this will be super awesome!

[mrnugget]

Current preview:

screenshot-2024-03-19-18.36.18.mp4

[mrnugget]

Collaboration works! Now all that's left is bundling git and incorporating more design feedback :)

screenshot-2024-03-27-19.59.35.mp4

[mrnugget]

bundled git binary also works!

[baldwindavid]

@mrnugget I've been using this in main and it's wonderful! Sorry for the unrelated, probably dumb question, but I've done a cargo run --release to get a Zed executable. Are there instructions somewhere to get a Mac "app" like you have there that I can run similarly to Preview/Stable releases?

Update: nvm, I see a bundle-mac script; I'll poke around with that.

[mmtftr]

Even though this is merged, I have a question @mrnugget. I'm curious as to why the code cannot just use git2::Blame for this. git2::Blame has Blame::blame_buffer which I believe would do the same thing as calling git blame --contents. I'm not sure what benefits we get by doing a --incremental especially since we wait for the command to exit.

[mrnugget]

@baldwindavid yep, that's the one. scripts/bundle-mac.

@mmtftr because it's very, very slow. See here: libgit2/libgit2#3027 Running git blame on crates/editor/src/editor.rs in this repository here took 40s, vs 600ms shelling out to git. --incremental in this case is only used for its machine-readable output.