The `wrong_self_convention` lint should be applied to traits too

[stanislav-tkach]

In the following code the wrong_self_convention is triggered for the S struct only (the to_a method), but not for the trait declaration (the to_b method):

struct S {}

impl S {
    fn to_a(self) {}
}

trait T: Sized {
    fn to_b(self) {}
}

Meta

• cargo clippy -V: clippy 0.0.212 (18bf6b4 2020-10-07)
• rustc -Vv:

  rustc 1.47.0 (18bf6b4f0 2020-10-07)
  binary: rustc
  commit-hash: 18bf6b4f01a6feaf7259ba7cdae58031af1b7b39
  commit-date: 2020-10-07
  host: x86_64-unknown-linux-gnu
  release: 1.47.0
  LLVM version: 11.0
  

[giraffate]

@rustbot modify labels: +L-enhancement