rustdoc should only include &self methods from Deref target

[Storyyeller]

Currently, if Foo impls Deref<Target=Bar>, then the generated documentation for Foo will include every method defined on Bar, regardless of receiver type. &mut self methods should only be included if DerefMut is impled, and self methods shouldn't be included at all.

It may also be worth excluding methods on the Deref target from the generated documentation if a method of the same name is defined on the original type, since that's the one that will be called under normal circumstances.

[durka]

This is a dupe of #35169 which was supposedly fixed in #36266, has it regressed?

[Storyyeller]

For example, https://docs.rs/easy_strings/0.1.0/easy_strings/struct.EZString.html#method.into_bytes

into_bytes(self) is included, despite taking self by value. Perhaps it only filters out &mut self methods, but doesn't filter self methods?

[durka]

Yeah, I guess the work in #36266 needs to be extended to also filter out methods with by-value receivers.

[ollie27]

Removing by-value methods was attempted and rejected in #33396.

[QuietMisdreavus]

The issue that's causing this is that DerefMut confuses the check that rustdoc does right here. If DerefMut is implemented, then that allows anything that's not self: Box<Self>, where it should also check that it's not a by-value self as well. Extending this to add another by_value condition (which should only be true in that _ branch, which corresponds to SelfTy::SelfValue) which further masks the bool that's handed to render_method_item in the above scope, will solve this.