Weird trigger condition for wrong_self_convention

[crumblingstatue]

Description

The following code triggers wrong_self_convention

mod foo {
    #[derive(Clone, Copy)]
    pub struct Foo<T>(std::marker::PhantomData<T>);

    impl<T> Foo<T> {
        pub fn to_bar(self) -> i32 {
            42
        }
    }
}

warning: methods with the following characteristics: (`to_*` and `self` type is not `Copy`) usually take `self` by reference
 --> src/lib.rs:6:23
  |
6 |         pub fn to_bar(self) -> i32 {
  |                       ^^^^

However, if it's not in a module, or the module is public, the lint doesn't trigger.

Version

rustc 1.63.0-nightly (10f4ce324 2022-06-22)
binary: rustc
commit-hash: 10f4ce324baf7cfb7ce2b2096662b82b79204944
commit-date: 2022-06-22
host: x86_64-unknown-linux-gnu
release: 1.63.0-nightly
LLVM version: 14.0.5

[tamaroning]

This is not a bug because if fn to_bar in first comment is exported, changing its argument causes breakages for other crates. If you want to lint it despite that, please try add avoid_breaking_exported_api = true to your clippy.toml. (false by default)

Ref: #7187