…llaumeGomez

Rollup of 10 pull requests

Successful merges:

 - rust-lang#119888 (Stabilize the `#[diagnostic]` namespace and `#[diagnostic::on_unimplemented]` attribute)
 - rust-lang#121089 (Remove `feed_local_def_id`)
 - rust-lang#122004 (AST validation: Improve handling of inherent impls nested within functions and anon consts)
 - rust-lang#122087 (Add missing background color for top-level rust documentation page and increase contrast by setting text color to black)
 - rust-lang#122136 (Include all library files in artifact summary on CI)
 - rust-lang#122137 (Don't pass a break scope to `Builder::break_for_else`)
 - rust-lang#122138 (Record mtime in bootstrap's LLVM linker script)
 - rust-lang#122141 (sync (try_)instantiate_mir_and_normalize_erasing_regions implementation)
 - rust-lang#122142 (cleanup rustc_infer)
 - rust-lang#122147 (Make `std::os::unix::ucred` module private)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of rust-lang#122004 - fmease:astvalidator-min-fix, r=compiler-errors

AST validation: Improve handling of inherent impls nested within functions and anon consts

Minimal fix for issue rust-lang#121607 extracted from PR rust-lang#120698 for ease of backporting and since I'd like to improve PR rust-lang#120698 in such a way that it makes AST validator truly robust against such sort of regressions (AST validator is generally *beyond* footgun-y atm). The current version of PR rust-lang#120698 sort of does that already but there's still room for improvement.

Fixes rust-lang#89342.
Fixes [after beta-backport] rust-lang#121607.
Partially addresses rust-lang#119924 (rust-lang#120698 aims to fully fix it).

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### Explainer

The last commit of PR rust-lang#119505 regressed issue rust-lang#121607.

Previously we would reject visibilities on associated items with `visibility_not_permitted` if we were in a trait (by checking the parameter `ctxt` of `visit_assoc_item` which was 100% accurate) or if we were in a trait impl (by checking a flag called `in_trait_impl` tracked in `AstValidator` which was/is only accurate if the visitor methods correctly updated it which isn't actually the case giving rise to the old open issue rust-lang#89342).

In PR rust-lang#119505, I moved even more state into the `AstValidator` by generalizing the flag `in_trait_impl` to `trait_or_trait_impl` to be able to report more precise diagnostics (modeling *Trait | TraitImpl*). However since we/I didn't update `trait_or_trait_impl` in all places to reflect reality (similar to us not updating `in_trait_impl` before), this lead to rust-lang#121607 (comment) getting wrongfully rejected. Since PR rust-lang#119505 we reject visibilities if the “globally tracked” (wrt. to `AstValidator`) `outer_trait_or_trait_impl` is `Some`.

Crucially, when visiting an inherent impl, I never reset `outer_trait_or_trait_impl` back to `None` leading us to believe that `bar` in the stack [`trait Foo` > `fn foo` > `impl Bar` > `pub fn bar`] (from the MCVE) was an inherent associated item (we saw `trait Foo` but not `impl Bar` before it).

The old open issue rust-lang#89342 is caused by the aforementioned issue of us never updating `in_trait_impl` prior to my PR rust-lang#119505 / `outer_trait_or_trait` after my PR. Stack: [`impl Default for Foo` > `{` > `impl Foo` > `pub const X`] (we only saw `impl Default for Foo` but not the `impl Foo` before it).

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This PR is only meant to be a *hot fix*. I plan on completely *rewriting* `AstValidator` from the ground up to not rely on “globally tracked” state like this or at least make it close to impossible to forget updating it when descending into nested items (etc.). Other visitors do a way better job at that (e.g. AST lowering). I actually plan on experimenting with moving more and more logic from `AstValidator` into the AST lowering pass/stage/visitor to follow the [Parse, don't validate](https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/) “pattern”.

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r? `@compiler-errors`

[beta] backports

- AST validation: Improve handling of inherent impls nested within functions and anon consts rust-lang#122004
- Downgrade const eval dangling ptr in final to future incompat lint rust-lang#122204

r? cuviper