collapsible_if false positive

[piscisaureus]

A #[cfg(unix)] attribute can make an if statement non-collapsible, but its presence is ignored by clippy.
cargo clippy --fix drops the attribute altogether.

Lint name

collapsible-if

Example

fn test() {
  if condition() {
    // ...
  } else {
    #[cfg(unix)]
    if let Some(unix_only) = resource.downcast::<UnixOnlyType>() {
      // ...
    }
  }
}

Meta

~🦕 cargo clippy -V
clippy 0.1.51 (e38fb30 2021-01-14)

~🦕 rustc -Vv
rustc 1.51.0-nightly (e38fb306b 2021-01-14)
binary: rustc
commit-hash: e38fb306b7f5e65cca34df2dab1f0db15e1defb4
commit-date: 2021-01-14
host: x86_64-unknown-linux-gnu
release: 1.51.0-nightly
LLVM version: 11.0