also start deduplicating the docs that are getting moved to this
section.

It requires no additonal changes to these crates, but will prevent
unnecessary `pub`s in the future.

But explain why.

Prevents reporting labels or diagnostics on spans that are produced
multiple times.

Documents that `BikeshedIntrinsicFrom` models transmute-via-union,
which is slightly more expressive than the transmute-via-cast
implemented by `transmute_copy`. Additionally, we provide an
implementation of transmute-via-union as a method on the
`BikeshedIntrinsicFrom` trait with additional documentation on
the boundary between trait invariants and caller obligations.

Whether or not transmute-via-union is the right kind of transmute
to model remains up for discussion [1]. Regardless, it seems wise
to document the present behavior.

[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967

When looking for multiple versions of the same crate, do not blindly construct the receiver type.

Follow up to rust-lang#128786. Fix rust-lang#129205.

Add `#[warn(unreachable_pub)]` to a bunch of compiler crates

By default `unreachable_pub` identifies things that need not be `pub` and tells you to make them `pub(crate)`. But sometimes those things don't need any kind of visibility. So they way I did these was to remove the visibility entirely for each thing the lint identifies, and then add `pub(crate)` back in everywhere the compiler said it was necessary. (Or occasionally `pub(super)` when context suggested that was appropriate.) Tedious, but results in more `pub` removal.

There are plenty more crates to do but this seems like enough for a first PR.

r? `@compiler-errors`

…=cuviper

deduplicate and clarify rules for converting pointers to references

part of rust-lang#124669

…er-errors

Document & implement the transmutation modeled by `BikeshedIntrinsicFrom`

Documents that `BikeshedIntrinsicFrom` models transmute-via-union, which is slightly more expressive than the transmute-via-cast implemented by `transmute_copy`. Additionally, we provide an implementation of transmute-via-union as a method on the `BikeshedIntrinsicFrom` trait with additional documentation on the boundary between trait invariants and caller obligations.

Whether or not transmute-via-union is the right kind of transmute to model remains up for discussion [1]. Regardless, it seems wise to document the present behavior.

[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967

Tracking Issue: rust-lang#99571

r? `@compiler-errors`

cc `@scottmcm,` `@Lokathor`

…errors

Do not ICE on non-ADT rcvr type when looking for crate version collision

When looking for multiple versions of the same crate, do not blindly construct the receiver type.

Follow up to rust-lang#128786.
Fixes rust-lang#129205
Fixes rust-lang#129216

…274, r=compiler-errors

Remove Duplicate E0381 Label

Aims to resolve rust-lang#129274, and adds a test for the case.

Essentially, we are duplicating this span for some reason. For now, I'm just using a set to collect the spans rather than the vec. I imagine there's probably no real reason to inspect duplicates in this area, but if I'm wrong I can adjust to collect "seen spans" in just the point where this label is applied.

I'm not sure why it's producing duplicate spans. Looks like this has been this way for a while? I think it gives the duplicate label on 1.75.0 for example.

…rce-link, r=notriddle

[rustdoc] Generate source link on impl associated types

Currently, impl associated types are generated but don't get a source link. This PR fixes that.

Before:

![image](https://github.com/user-attachments/assets/3a22adb5-8b66-4124-9267-7c26eed1aa5e)

After:

![Screenshot from 2024-08-25 16-31-36](https://github.com/user-attachments/assets/6e9b35e7-4357-4ecf-8c49-1d8294051283)

r? `@notriddle`

Remove a couple of unused feature enables

… r=fmease

Rename `ParenthesizedGenericArgs` to `GenericArgsMode`

A bit easier to digest name. Broken out of a PR implementing return type notation.

…fmease

Remove `ParamMode::ExplicitNamed`

This was introduced as a hack to improve a diagnostics suggestion in rust-lang#61679. It was subsequently broken, but also it was an incomplete hack that I don't believe we need to support, so let's just remove it.