How to run cargo fmt on save in vscode?

Question

Is it possible to make Visual Studio Code run cargo fmt on file save?

Admass

Answer 1

Install the extension rust-analyzer (the officially recommended vscode extension), and add the following to settings.json:

"[rust]": {
    "editor.defaultFormatter": "rust-lang.rust-analyzer",
    "editor.formatOnSave": true
}

Thelma

Answer 2

1. Install rust-analyzer, if you have not already.
2. In Visual Studio Code's settings, enable Editor: Format On Save (editor.formatOnSave).

Jeanene

I'll also add that you should ensure you don't have "editor.defaultFormatter" set globally. If you have, say, "editor.defaultFormatter": "esbenp.prettier-vscode" (or some other formatter) enabled globally rather than on a per-language basis, VSCode will attempt to use that formatter in lieu of rust-analyzer's on Rust code. I've seen a few JS devs lost 10 or 15 minutes to this when transitioning to a Rust project. – Magda

Answer 3

This is what worked for me. In the file settings.json somewhere inside the curly braces insert the following :

    "editor.formatOnSave": true,
    "editor.formatOnType": true,
    "rust-analyzer.rustfmt.enableRangeFormatting": true,
    "[rust]": {
        "editor.defaultFormatter": "rust-lang.rust-analyzer", 
        "editor.formatOnSave": true 
    },

Morbidity

Answer 4

If you have formatOnSaveMode is set to modifications or modificationsIfAvailable, you may need to change it to file. This is probably a small issue with the analyzer.

And if you want to leave the default settings unchanged, do it for only rust;

"[rust]": {
    "editor.defaultFormatter": "rust-lang.rust-analyzer",
    "editor.formatOnSave": true,
    "editor.formatOnSaveMode": "file"
  },

Nominal

i just need to add: "editor.formatOnSaveMode": "file" it's the working answer! thank you! – Lengthy

This was it for me, thanks! With modifications set it silently did nothing. – Lapidate

Answer 5

Current version of the Rust extension > 0.7.8 requires nothing else to be installed. Enable formatOnSave in VS Code settings.json file:

  "[rust]": {
        "editor.formatOnSave": true
    }

Backer

Answer 6

Posting on behalf of @Stacks. Here's a more complete set of steps that will identify any problems with steps 1-2. Just enabling "format on save" may not always be enough:

1. Install rust-analyzer
2. Enable Editor: Format On Save (as in the other answers)
3. Test Formatting your code by manually selecting a section of code and either right clicking “Format Code..” or pressing the “Format Code” shortcut (Cntrl-Shift-F or Alt-Shift-F)
4. Follow any prompts to select a different formatter if necessary.

The last steps 3-4 are important, because if your formatting preferences are incorrect or if there are duplicate formatters installed, it will fail and prompt you to select the correct one to use.

Acute

Answer 7

Install rust-analyzer and add this to your settings.json

"[rust]": {
    "editor.defaultFormatter": "rust-lang.rust-analyzer",
    "editor.formatOnSave": true
}

Pitchblack

This is a duplicate of Delta Kapp's answer above. – Ethel