#![feature(lazy_cell)] #![deny(suspicious_double_ref_op, noop_method_call)] use std::borrow::Borrow; use std::ops::Deref; struct PlainType(T); #[derive(Clone)] struct CloneType(T); pub fn clone_on_double_ref() { let x = vec![1]; let y = &&x; let z: &Vec<_> = y.clone(); //~^ ERROR using `.clone()` on a double reference, which returns `&Vec` println!("{:p} {:p}", *y, z); } use std::sync::LazyLock; pub static STRS: LazyLock<&str> = LazyLock::new(|| "First"); // https://github.com/rust-lang/rust-clippy/issues/9272 fn rust_clippy_issue_9272() { let str = STRS.clone(); println!("{str}") } fn main() { let clone_type_ref = &&CloneType(1u32); let clone_type_ref_clone: &CloneType = clone_type_ref.clone(); //~^ ERROR using `.clone()` on a double reference, which returns `&CloneType` let non_deref_type = &&PlainType(1u32); let non_deref_type_deref: &PlainType = non_deref_type.deref(); //~^ ERROR using `.deref()` on a double reference, which returns `&PlainType` let xs = ["a", "b", "c"]; let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead //~^ ERROR using `.clone()` on a double reference, which returns `&str` }