Format changed code?

[davidhewitt]

Do you think it would be possible to add a flag/mode to format the changed code? This would be really helpful alongside clippy warnings to keep PRs high quality.

(A lot of projects would pick up a lot of changes that would be irrelevant to the PR if I run cargo fmt, so formatting just my diff would be great.)

[o0Ignition0o]

Hey @davidhewitt :)

I think it would be a great idea, it has raised concerns in the fmt project rust-lang/rustfmt#1324 , and it seems like it would be a bit hard to do.

Other trade offs would include running fmt only on the files that are part of a diff, or maybe try to work on a way to get the shortest part of the AST and apply rust fmt on it.

I wonder if that would be possible, but it would definitely be a great thing to try to figure out!

I would gladly try to work on the ast idea if someone could mentor me, I’m not really sure who I could refer to.
Maybe that would be something @nrc could mentor me on. I’ll try to send the team a message :)

[nrc]

Maybe that would be something @nrc could mentor me on. I’ll try to send the team a message :)

Sorry, I am not working on Rustfmt anymore. If you comment on an issue on their repo, there should be somebody who can mentor you. Good luck!

[o0Ignition0o]

Hey and thanks for your reply, I’ll send a message over :)

[o0Ignition0o]

There might be a way to use an unstable feature to do it:

If you want to restrict reformatting to specific sets of lines, you can use the --file-lines option. 
Its argument is a JSON array of objects with file and range properties, where file is a file name, and range is an array representing a range of lines like [7,13].
Ranges are 1-based and inclusive of both end points.

rustfmt --file-lines '[
    {"file":"src/lib.rs","range":[7,13]},
    {"file":"src/lib.rs","range":[21,29]},
    {"file":"src/foo.rs","range":[10,11]},
    {"file":"src/foo.rs","range":[15,15]}]'

Let's try to play around with that :D

[o0Ignition0o]

It starts looking pretty good:

[VCS] - Getting diff with target master
[RustFmt] - checking format for directory /home/ignition/projects/oss/cargo-scout/cargo-scout
[RustFmt] - checking format for directory /home/ignition/projects/oss/cargo-scout/cargo-scout-lib
[Scout] - checking for intersections
Diff in /home/ignition/projects/oss/cargo-scout/cargo-scout-lib/src/lib.rs at line 7: 
-            pub use error::Error;
+pub use error::Error;

Cargo scout found 1 warnings
Error: NotClean

For now it only checks for formatting, but we can start working on a --fix command as soon as this gets merged.

[davidhewitt]

Awesome, many thanks for implementing this!

[o0Ignition0o]

Whoops, I'm going to reopen this ^^'

For now cargo-scout fmt can find the lints. We need to add a --fix option so we can apply the suggestions!

[o0Ignition0o]

might be able to revive this one soon : https://twitter.com/yaahc_/status/1250842702242910208?s=20 :D

[cecton]

Hey @o0Ignition0o do you have any update on that issue? I'm still very interested