rust-analyzer.rustfmt.overrideCommand value format isn't documented

[jplatte]

The current documentation on this setting is not very clear:

Advanced option, fully override the command rust-analyzer uses for formatting.

From #10826 I gathered that I should be able to set it to an array containing an absolute path to a rustfmt executable, but this just caused rust-analyzer to not format files at all anymore (I set it to my nightly toolchain's rustfmt binary).

Could it be documented how this option is meant to be used? Alternatively, it would be great if I could just tell rust-analyzer to use rustfmt from a different toolchain than what's used for everything else.

[Veykril]

can you check the logs for errors? For rustfmt that command really only needs to point to a binary, though the rustc devguide passes an edition as well, you might need to do that too.
Example from the rustc devguide:

   "rust-analyzer.rustfmt.overrideCommand": [
        "./build/$TARGET_TRIPLE/stage0/bin/rustfmt",
        "--edition=2021"
    ],

[jplatte]

Well, now I tried again and it just worked (regardless of whether the edition was passed or not). Can I leave this open as a documentation improvement request?

[jplatte]

Hm no, it's back to not functioning. No logs to be found other than some initialization logs in the Rust Analyzer Client section.

[Veykril]

Do you have the RA_LOG env var overwritten? If not this should at least log an error ... does running rustfmt manually work on the file you are trying to format?

[jplatte]

No, I haven't set RA_LOG. I'll try with manual rustfmt invocation in a bit.

[Veykril]

Iirc there is still a bug where very weird whitespace can make rustfmt spit out a warning, exiting successfully without formatting anything. This might be what you are running into, at least I hope that's it 😬.

[jplatte]

Seems to work more reliable now I've enabled it again. So only the documentation is left.

Edit: So it was the edition that sometimes causes rustfmt to fail. I tried it manually, it's async move blocks that are not syntactically valid in Rust 2015.

[andrewbaxter]

Just landed here. Yeah, the documentation isn't very informative, I assume since this is only intended to work with rustfmt also.

In short

• args are an array, or null/absent to use default rustfmt
• first element is binary
• other elements are arguments to the binary
• the source code is passed in via stdin
• the formatted code is taken from stdout

If this were in the docs it would be awesome.

[andrewbaxter]

FWIW all error messages refer to rustfmt even if you're not using rustfmt, which can be confusing.