Wrong documentation is generated for types that only implement Deref, but not DerefMut. It inherits methods from both Deref and DerefMut. Steps to reproduce: `cargo new deref-doc-bug` ``` /// lib.rs pub struct Foo; impl std::ops::Deref for Foo { type Target = [char]; fn deref(&self) -> &[char] { &[] } } ``` `cargo doc --open` Generated documentation has methods for both `&[char]` and `&mut [char]`, for example`fn get_mut`. ## Version ``` rustc 1.12.0-nightly (1225e122f 2016-07-30) rustdoc 1.12.0-nightly (1225e122f 2016-07-30) ```