use_self does not notice Self with lifetimes #12381
Description
Summary
Types where a lifetime is involved don't get noticed by use_self. Generics are no issue. Cow<'a, B> with both lifetime and generic are also not noticed.
clippy::return_self_not_must_use finds these cases.
Lint Name
clippy::use_self
Reproducer
I tried this code:
#![warn(clippy::use_self)] use std::borrow::Cow; trait Foo { type Item; fn bar(&self) -> Self::Item; } #[derive(Clone)] struct Data<'a> { value: &'a str, } impl<'a> Data<'a> { pub const fn new(value: &'a str) -> Data<'a> { Data {value} } } impl<'a> Foo for Data<'a> { type Item = Data<'a>; fn bar(&self) -> Self::Item { self.clone() } } impl<'a, T: ToOwned> Foo for Cow<'a, T> { type Item = Cow<'a, T>; fn bar(&self) -> Self::Item { self.clone() } } struct Something<T> { value: T, } impl<T> Something<T> { pub const fn new(value: T) -> Something<T> { Something { value } } } impl<T: Clone> Foo for Something<T> { type Item = Something<T>; fn bar(&self) -> Self::Item { Something { value: self.value.clone() } } } fn main() { let data = Data::new("Hello"); let first = data.bar().value; let something = Something::new("world"); let second = something.bar().value; println!("{first}, {second}!"); }I expected to see this happen:
Data<'a> should be replaced by Self for type Item = , Data {…} and -> Data<'a>.
Instead, this happened:
Only Something<T> is noticed.
Version
Both current stable and current nightly.
$ rustc -Vv rustc 1.76.0 (07dca489a 2024-02-04) binary: rustc commit-hash: 07dca489ac2d933c78d3c5158e3f43beefeb02ce commit-date: 2024-02-04 host: x86_64-unknown-linux-gnu release: 1.76.0 LLVM version: 17.0.6 rustc 1.78.0-nightly (ef324565d 2024-02-27) binary: rustc commit-hash: ef324565d071c6d7e2477a195648549e33d6a465 commit-date: 2024-02-27 host: x86_64-unknown-linux-gnu release: 1.78.0-nightly LLVM version: 18.1.0