message: clippy lints: redundant_clone is on by default, allow clippy::collapsible_if
diff: #![allow(clippy::wrong_self_convention)] // perhaps `Rc` should be special-cased in Clippy?
  #![allow(clippy::write_with_newline)] // too pedantic
  #![allow(clippy::inefficient_to_string)] // this causes suggestions that result in `(*s).to_string()`
  +#![allow(clippy::collapsible_if)] // too pedantic
  #![warn(clippy::needless_borrow)]
  -#![warn(clippy::redundant_clone)]
  // Unit is now interned, and would probably be better as pass-by-copy, but
  // doing so causes a lot of & and * shenanigans that makes the code arguably
  // less clear and harder to read.
  