Hidden traits missing implementors when documented via `--document-hidden-items`

[steffahn]

You can see --document-private-items --document-hidden-items docs of the standard library here:

https://stdrs.dev/nightly/x86_64-unknown-linux-gnu/std/iter/trait.InPlaceIterable.html

as you can see, the implementors are missing though (which is incredibly annoying if you ever want to work on those traits). Also reproducible locally by building RUSTDOCFLAGS='--document-private-items --document-hidden-items -A rustdoc::broken-intra-doc-links' ./x.py doc library/std --open

@rustbot label T-rustdoc

[jyn514]

@steffahn can you reproduce this on anything smaller than the standard library?

[steffahn]

I haven't tried it on anything else yet. I can do that tomorrow, when I'm back at a computer.

I also haven't checked whether this is a regression.

[hellow554]

I did the full circle and wrote this:

pub trait T {}

pub struct VisPub;
struct VisPriv;
#[doc(hidden)]
pub struct HidPub;
#[doc(hidden)]
struct HidPriv;

impl T for VisPub {}
impl T for VisPriv {}
impl T for HidPub {}
impl T for HidPriv {}

Output is this:

so hidden items won't get displayed as Implementors, although displayed as structs on the "homepage":

@rustbot modify labels: -E-needs-mcve

[steffahn]

@hellow554 it's actually the trait that's hidden in the standard library, not the structs. Though your case not displaying the implementation is problematic, too.

[hellow554]

I see :) thanks for pointing it out:

Rust code

pub trait TPubVis {}
#[doc(hidden)]
pub trait TPubHidden {}
trait TPrivVis {}
#[doc(hidden)]
trait TPrivHidden {}

pub struct VisPub;
struct VisPriv;
#[doc(hidden)]
pub struct HidPub;
#[doc(hidden)]
struct HidPriv;

macro_rules! implement {
    ($trait:ident - $($struct:ident)+) => {
        $(
            impl $trait for $struct {}
        )+
    }
}


implement!(TPubVis - VisPub VisPriv HidPub HidPriv);
implement!(TPubHidden - VisPub VisPriv HidPub HidPriv);
implement!(TPrivVis - VisPub VisPriv HidPub HidPriv);
implement!(TPrivHidden - VisPub VisPriv HidPub HidPriv);

No implementors for a #[doc(hidden)] trait:

Only implementors that are not #[doc(hidden)]:

[lolbinarycat]

triage: this issue has been fixed, adding a regression test for it