Format on save in VS Code ignores rustfmt.toml

[Benlitz]

Hi,

It seems that when I save a file in VS Code, it ignores the rustfmt.toml file and applies the default configuration for formatting. I just added a rustfmt.toml file with only max_width = 160 in it. When I save a file, it clearly applies the default 100 character width. If I run rustfmt [file] in a console it works properly.

Note: I'm working in a workspace with multiple crates in it, and some other crates have their own rustfmt.toml. I doubt this is related to the problem but still mentioning.

[lnicola]

Note: I'm working in a workspace with multiple crates in it, and some other crates have their own rustfmt.toml. I doubt this is related to the problem but still mentioning.

It might. Can you still reproduce this in a non-workspace project?

[Benlitz]

Note: I'm working in a workspace with multiple crates in it, and some other crates have their own rustfmt.toml. I doubt this is related to the problem but still mentioning.

It might. Can you still reproduce this in a non-workspace project?

So indeed, it works in that case.
I also tried to create a very simple workspace with two crates, and only one with a rustfmt.toml, and I still have the problem, so it's unlikely to be a conflict between multiple rustfmt.toml files.

(I also removed the "workaround" I initially mentioned in the description, it doesn't work - formatting isn't run with it)

[d4h0]

Unfortunately, I have the same problem.

My workaround for now, is to use the VSCode extension Run on Save with the following configuration:

"emeraldwalk.runonsave": {
	"commands": [
		{
			"match": "\\.rs$",
			"cmd": "rustfmt '${file}'"
		}
	]
}

(This needs to be added to a workspace.json or the user settings.json file)

I also have disabled the native VSCode "Format on Save" (otherwise, the rustfmt that rust-analyzer executes could lead to problems).

[lnicola]

@Benlitz just to make sure, is that a cargo or Code workspace? If you were able to reproduce it in a new project, do you mind sharing it?

[Benlitz]

it was on a cargo workspace, but actually it happens as soon as the folder you open in vscode is a folder above the crate folder.

I'm joining a simple project. Repro:

• In VS Code, Open Folder and select the (unzipped) test_issue folder
• Open my_crate/src/main.rs via the explorer panel
• Press Ctrl+S (with format on save enabled)
  → the file should be reformatted so that lines are <100
• Open a terminal in VS Code and run rustfmt my_crate/src/main.rs
  → Formatting is back to <160 as specified in the rustfmt.toml

And just in case it's a folder separator issue or something similar: I'm having this issue on Windows. I haven't tested it on Linux yet.

test_issue.zip

[d4h0]

is that a cargo or Code workspace?

I'm using a Cargo Workspace with a VSCode Workspace that is on the same directory.

I haven't tested it on Linux yet.

I use Linux, so the problem is probably not specific to Windows

[lnicola]

@Benlitz reproduced on Linux. I think the issue is that we're running rustfmt in the project directory. We can't chdir to the file because it might not exist on disk, but maybe to the Cargo.toml directory? What if there's more than one root? Which rustfmt.toml should we pick?

Any opinion, @matklad?

[matklad]

Can we set

        --config-path [Path for the configuration file]
                        Recursively searches the given path for the
                        rustfmt.toml config file. If not found reverts to the
                        input file path

[lnicola]

But what do we set it to?

[matklad]

To the path of the .rs file. I hope that "Recursively searches" part will just work then

[flodiebold]

Might be interesting to check what happens if the last part of the config path doesn't exist...

Otherwise we could also just chdir as far down as possible to the file path 🤔

[lnicola]

What happens for files that haven't been saved?

EDIT: this happens

[lnicola]

Looks like it's not as recursive as one would expect:

$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src/main.rs --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Could not parse TOML: expected an equals, found an identifier at line 1 column 4

$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src/ --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/my_crate/src/`

$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/my_crate/src`

$ rustfmt --config-path ~/Downloads/test_issue/my_crate --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
fn fjsdlkfjklsdajflksdjlfdasdsadsadsaadkjdskljflkasj_jflksjdklfjsdlkjflkdjslkfjas(a: i32, b: i32, c: i32) {
    println!("TEST");
}

fn main() {
    fjsdlkfjklsdajflksdjlfdasdsadsadsaadkjdskljflkasj_jflksjdklfjsdlkjflkdjslkfjas(1, 2, 3);
    println!("Hello, world!");
}

$ rustfmt --config-path ~/Downloads/test_issue/ --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/`