also move them next to the trait they are implementing

Co-authored-by: Ralf Jung <post@ralfj.de>

Fixes rust-lang#103460

…n_type

instead of decoding time.

Co-authored-by: Esteban Kuber <estebank@users.noreply.github.com>

CSS variables, which rustdoc now relies on, are only supported in Firefox 31 and later: https://www.mozilla.org/en-US/firefox/31.0/releasenotes/

This means it’s fine to also rely on unprefixed box-sizing, which is supported in Firefox 29 and later: https://www.mozilla.org/en-US/firefox/29.0/releasenotes/

…dditional clarity

remove redundant Send impl for references

Also explain why the other instance is not redundant, move it next to the trait they are implementing, and out of the redundant module. This seems to go back all the way to rust-lang@35ca50b, not sure why the module was added.

The instance for `&mut` is the default instance we get anyway, and we don't have anything similar for `Sync`, so IMO we should be consistent and not have the redundant instance here, either.

…r=compiler-errors

Clean up hidden type registration

work on rust-lang#101186

Actually passing down the relation and using it instead of `eq` for the hidden type comparison has *no* effect whatsoever and allows for no further improvements at the call sites. I decided the increased complexity was not worth it and thus did not include that change in this PR.

r? `@compiler-errors`

…manieu

Clarify documentation about the memory layout of `UnsafeCell`

This PR addresses a [comment](rust-lang#101717 (comment)) by `@RalfJung` in PR rust-lang#101717 to further clarify the documentation of `UnsafeCell<T>`. The previous PR was merged already before we had a chance to correct this, hence this second PR :)

To goal of this PR is:

1. Split the paragraph about the memory layout of `UnsafeCell<T>` and the usage of `UnsafeCell::(raw_)get()` into two paragraphs, so that it is easier to digest for the reader.
2. Slightly simplify the previously added examples in order to reduce redundancy between the new examples and the examples that already [existed](https://github.com/rust-lang/rust/blob/ddd119b2fed57eb6b19c44c18108de95c564a48d/library/core/src/cell.rs#L1858-L1908) before these 2 PRs (which remained untouched by both PRs).

…GuillaumeGomez

Clean return-position `impl Trait` in traits correctly in rustdoc

Fixes rust-lang#103403

…losing-tags, r=GuillaumeGomez

rustdoc: parse self-closing tags and attributes in `invalid_html_tags`

Fixes rust-lang#103460

rustc_metadata: Add struct and variant constructors to module children at encoding time

instead of decoding time.

Continuation of rust-lang#95899.
The last time it caused some ICEs from generator use, but not everything seems ok.

…ler-errors

Add flag to forbid recovery in the parser

To start the effort of fixing rust-lang#103534, this adds a new flag to the parser, which forbids the parser from doing recovery, which it shouldn't do in macros.

This doesn't add any new checks for recoveries yet and is just here to bikeshed the names for the functions here before doing more.

r? `@compiler-errors`

…, r=GuillaumeGomez

rustdoc: remove CSS workaround for Firefox 29

CSS variables, which rustdoc now relies on, are only supported in Firefox 31 and later: https://www.mozilla.org/en-US/firefox/31.0/releasenotes/

This means it’s fine to also rely on unprefixed box-sizing, which is supported in Firefox 29 and later: https://www.mozilla.org/en-US/firefox/29.0/releasenotes/