75a87c54d0
Prohibit patterns in trait methods without bodies They are not properly type checked ```rust trait Tr { fn f(&a: u8); // <- This compiles } ``` , mostly rejected by the parser already and generally don't make much sense. This PR is kind of a missing part of https://github.com/rust-lang/rust/pull/35015. Given the [statistics from crater](https://github.com/rust-lang/rust/pull/37378#issuecomment-256154994), the effect of this PR is mostly equivalent to improving `unused_mut` lint. cc https://github.com/rust-lang/rust/issues/35078#issuecomment-255707355 https://github.com/rust-lang/rust/pull/35015 https://github.com/rust-lang/rfcs/pull/1685 https://github.com/rust-lang/rust/issues/35203 r? @eddyb