Auto formatting with VS Code / rustfmt different from with `cargo fmt`

help
1

I'm trying to use an unstable version of rustfmt for some config options that aren't in stable yet.
When I run via cargo +nightly fmt things work as expected.
When I run via rustup run nightly -- rustfmt, I get a different (and incorrect) output.
I'm guessing there is a bug in the version of rustfmt invoked by rustup (I can describe later), but I really just want to figure out how to get VS Code to do the same thing that cargo +nightly fmt is doing but so far I haven't figured out how to do that. Any tips?

The (maybe) bug is that rustup run nightly -- rustfmt removes the leading double colon from a use line when it should not in a way that breaks the code. The use line is like use ::foo::bar, and there happens to be a submodule named foo as well, but it doesn't contain bar.
Should I try to report a bug about this? I searched briefly on GitHub and couldn't find anything.

I'm on MacOS:
➜ which cargo
/Users/garymm/.cargo/bin/cargo

➜ which rustup
/opt/homebrew/bin/rustup

➜ cargo +nightly fmt --version
rustfmt 1.8.0-nightly (28fc2ba714 2024-11-24)

➜ rustup run nightly -- rustfmt --version
rustfmt 1.8.0-nightly (28fc2ba714 2024-11-24)

2

Running verbose (-v) cargo fmt shows there’s an --edition argument you might be missing here; e.g. in an edition 2021 project, I do

$ cargo +nightly fmt -v
[bin (2021)] "/…path to project…/src/main.rs"
$ rustfmt --edition 2021 /…path to project…/src/main.rs

and see it passes --edition 2021, too. With that added to your command, the behavior should then hopefully be the same?

3

To skip the need to hardcode the 2021, it looks like another approach might be to skip the rust-analyzer.rustfmt.overrideCommand setting and instead just add something like

"rust-analyzer.rustfmt.extraArgs": [
    "+nightly"
],

at least according to this comment

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