rustfmt deletes derived traits in #[derive(...)] #4584
Description
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