wrong_self_convention triggers in trait method implementations

[kangalio]

Lint name: wrong_self_convention

I tried this code:

struct Error {}

trait FromMeta: Sized {
    fn from_char(_value: char) -> Result<Self, Error> { Err(Error {}) }
    fn from_bool(_value: bool) -> Result<Self, Error> { Err(Error {}) }
}

impl FromMeta for char {
    fn from_char(value: Self) -> Result<Self, Error> { Ok(value) }
}

impl FromMeta for bool {
    fn from_bool(value: Self) -> Result<Self, Error> { Ok(value) }
}

I expected to see this happen: nothing is linted

Instead, this happened: the from_char implementation for char and from_bool implementation for bool were linted because Clippy thinks the value: Self parameter is a self parameter and from_* methods shouldn't take self parameters.

However, FromMeta is a trait and will be implemented by lots of different types. On some types, the trait names may seem slightly awkward, but I think there is not much the programmer can realistically do about that. I think it would be beneficial if this lint weren't triggered in trait implementations.

Context: the FromMeta trait is similar in spirit to serde's Deserialize. It comes from the darling crate, a proc-macro attribute parser. Links for the offending trait implementations: bool and char.

Meta

• cargo clippy -V: clippy 0.1.53 (b849326 2021-04-21)
• rustc -Vv:

rustc 1.53.0-nightly (b84932674 2021-04-21)
binary: rustc
commit-hash: b849326744a8eec939e592f0ab13bff85cc865d3
commit-date: 2021-04-21
host: x86_64-unknown-linux-gnu
release: 1.53.0-nightly
LLVM version: 12.0.0

[kangalio]

This seems to be a duplicate of #7032. Sorry for not searching for duplicates before posting