Rustdoc does not hide implementations of `doc(hidden)` trait methods

[jyn514]

I tried this code:

pub trait Trait {
    #[doc(hidden)]
    fn f();
}
pub struct S;
impl Trait for S {
    fn f() {}
}

I expected to see this happen: Rustdoc does not show f in the documentation for S.

Instead, this happened:

Since f is properly hidden in the documentation for Trait, the link for f is broken.

Meta

rustc --version --verbose:

rustc 1.57.0-nightly (ac2d9fc50 2021-09-21)

Originally posted by @rust-log-analyzer in #89167 (comment)

[jyn514]

Mentoring instructions: when generating trait impls and --document-hidden-items is not passed, skip all methods where the method in the original trait was hidden. See #86513 for a similar change - the relevant code is build_impl in src/librustdoc/clean/inline.rs.

[hkmatsumoto]

@rustbot claim