src/tools/clippy/tests/ui/derive.rs

#![allow(
    clippy::non_canonical_clone_impl,
    clippy::non_canonical_partial_ord_impl,
    clippy::needless_lifetimes,
    clippy::repr_packed_without_abi,
    dead_code
)]
#![warn(clippy::expl_impl_clone_on_copy)]
#![expect(incomplete_features)] // `unsafe_fields` is incomplete for the time being
#![feature(unsafe_fields)] // `clone()` cannot be derived automatically on unsafe fields

#[derive(Copy)]
struct Qux;

impl Clone for Qux {
    //~^ expl_impl_clone_on_copy

    fn clone(&self) -> Self {
        Qux
    }
}

// looks like unions don't support deriving Clone for now
#[derive(Copy)]
union Union {
    a: u8,
}

impl Clone for Union {
    fn clone(&self) -> Self {
        Union { a: 42 }
    }
}

// See #666
#[derive(Copy)]
struct Lt<'a> {
    a: &'a u8,
}

impl<'a> Clone for Lt<'a> {
    //~^ expl_impl_clone_on_copy

    fn clone(&self) -> Self {
        unimplemented!()
    }
}

#[derive(Copy)]
struct BigArray {
    a: [u8; 65],
}

impl Clone for BigArray {
    //~^ expl_impl_clone_on_copy

    fn clone(&self) -> Self {
        unimplemented!()
    }
}

#[derive(Copy)]
struct FnPtr {
    a: fn() -> !,
}

impl Clone for FnPtr {
    //~^ expl_impl_clone_on_copy

    fn clone(&self) -> Self {
        unimplemented!()
    }
}

// Ok, Clone trait impl doesn't have constrained generics.
#[derive(Copy)]
struct Generic<T> {
    a: T,
}

impl<T> Clone for Generic<T> {
    fn clone(&self) -> Self {
        unimplemented!()
    }
}

#[derive(Copy)]
struct Generic2<T>(T);
impl<T: Clone> Clone for Generic2<T> {
    //~^ expl_impl_clone_on_copy

    fn clone(&self) -> Self {
        Self(self.0.clone())
    }
}

// Ok, Clone trait impl doesn't have constrained generics.
#[derive(Copy)]
struct GenericRef<'a, T, U>(T, &'a U);
impl<T: Clone, U> Clone for GenericRef<'_, T, U> {
    fn clone(&self) -> Self {
        Self(self.0.clone(), self.1)
    }
}

// https://github.com/rust-lang/rust-clippy/issues/10188
#[repr(packed)]
#[derive(Copy)]
struct Packed<T>(T);

impl<T: Copy> Clone for Packed<T> {
    fn clone(&self) -> Self {
        *self
    }
}

fn issue14558() {
    pub struct Valid {
        pub unsafe actual: (),
    }

    unsafe impl Copy for Valid {}

    impl Clone for Valid {
        #[inline]
        fn clone(&self) -> Self {
            *self
        }
    }
}

fn main() {}

mod issue15708 {
    // Check that `allow`/`expect` attributes are recognized on the type definition node
    #[expect(clippy::expl_impl_clone_on_copy)]
    #[derive(Copy)]
    struct S;

    impl Clone for S {
        fn clone(&self) -> Self {
            S
        }
    }
}

mod issue15842 {
    #[derive(Copy)]
    struct S;

    // Check that `allow`/`expect` attributes are recognized on the `impl Clone` node
    #[expect(clippy::expl_impl_clone_on_copy)]
    impl Clone for S {
        fn clone(&self) -> Self {
            S
        }
    }
}