rustfmt deletes derived traits in #[derive(...)]

[ente76]

Describe the bug

Running cargo fmt on my project takes all #[derive(Debug, Clone, PartialEq, Eq)] and deletes exactly the last letter on each execution. It does not matter how many traits I derive. If I run it multiple times, it will stop at an empty derive().

To Reproduce

Setup a new library and add the following lines:

#[derive(Debug)]
pub enum Case {
    Upper,
    Lower
}

run cargo fmt

Expected behavior

cargo fmt finishes my project while I watch funny cat videos on youtube. At least rustfmt does not make my life harder than it is.

Meta

• rustfmt version: rustfmt 1.4.29-nightly (70ce182 2020-12-04)
• From where did you install rustfmt?: rustup nightly version: rustc 1.50.0-nightly (d32c320 2020-12-10)
• How do you run rustfmt: cargo fmt (manually to test), usually via rust-analyzer during file saving

[ente76]

rustfmt 1.4.27-nightly (580d826 2020-11-16) works without the error.

[calebcartwright]

I'm unable to reproduce this locally. Can you provide some additional information so that we can be better equipped to assist?

Do you have a public repo or a CI run where we can observe the described behavior?

[ente76]

Please do run:

mkdir test
cd test
git clone https://gitlab.com/systemd.rs/sd-sys.git
git clone https://gitlab.com/systemd.rs/sd-id128.git
cd sd-id128
cargo fmt

file lib.rs in test/sd-id128/src/lib.rs has multiple derives that should be lacking the last letter now. I tested above process using rustup provided by arch linux (rustup 1.23.0-1).
rustup update has been executed approx. every day since Monday (that's approximately been the first time I hit the error).
rustup default nightly is been activated. I will go back to the working version now (currently I use nightly-20-11-2020).

[calebcartwright]

Thanks! This can be reproduced when indent_style is changed to Visual

[calebcartwright]

Backported in v1.4.30

[karyon]

backported in #4605