Format on auto-saving doesn't work

[djc]

I have formatOnSave enabled and autoSave set. Yet automatic saving does not seem to trigger formatting as manual saving does. Is this a rust-analyzer issue?

[Veetaha]

This is interesting, I don't know where this formatting comes at all... @matklad do you know where the Rust formatter comes from?

[zshift]

I just really started getting into rust, so excuse my ignorance. Same for vscode plugins.

I ran into rustfmt just a few min ago. It's installed with rustup component add rustfmt.

Usage is rustfmt [options] <file>.

[blitzerr]

This isn't working for me either. I have the latest version.

[tbmreza]

@blitzerr running rustfmt from the command line works for me. Have you tried overriding the default formatter?

1. Install https://marketplace.visualstudio.com/items?itemName=statiolake.vscode-rustfmt
2. Ctrl+Shift+P, Format Document With... Configure Default Formatter...
3. Format on save now works on single rs file.

[matthiaskrgr]

Had the same problem, had
"editor.formatOnSave": true,
and
"files.autoSave": "afterDelay", but files did not get formatted.

I looked into my settings.json and found this

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

and removing this fixed the auto-formatting for me :)

[lnicola]

@djc, @blitzerr is this working for you now?

(Marking S-actionable, if you look at this in the future and the OP hasn't answered, ping me so we can close it.)

[djc]

No, this is still not working for me. I have formatOnSave set to true, files.autoSave set to afterDelay (300ms) but files are not getting formatted automatically. I don't have the defaultFormatter config that Matthias found.

[Veykril]

Actually, it seems that this is a vscode specific problem... microsoft/vscode#45997
The docs for formatOnSave state:

  // Format a file on save. A formatter must be available, the file must not be saved after delay, and the editor must not be shutting down.
  "editor.formatOnSave": false,

https://code.visualstudio.com/docs/getstarted/settings
So autosaving after a delay does not trigger the formatter.

[mukundbhudia]

Maybe it should be this:

"[rust]": {
  "editor.defaultFormatter": "matklad.rust-analyzer"
}

with

"editor.formatOnSave": true,

all of which go in settings.json

[Oyami-Srk]

Perhaps "editor.formatOnSaveMode": "modificationsIfAvailable" or "editor.formatOnSaveMode": "modifications" has a conflict with auto-format of rust-analyzer. Setting it to file on rust specified settings solved this problem for me.

[bjorn3]

"editor.formatOnSaveMode": "modifications"

That one will definitively not work. Only nightly rustfmt supports range formatting and rust-analyzer doesn't implement support for using this mode.