Auto merge of #145300 - Zalathar:rollup-0eqbt6a, r=Zalathar

Rollup of 17 pull requests

Successful merges:

 - rust-lang/rust#131477 (Apple: Always pass SDK root when linking with `cc`, and pass it via `SDKROOT` env var)
 - rust-lang/rust#139806 (std: sys: pal: uefi: Overhaul Time)
 - rust-lang/rust#144386 (Extract TraitImplHeader in AST/HIR)
 - rust-lang/rust#144921 (Don't emit `rustdoc::broken_intra_doc_links` for GitHub-flavored Markdown admonitions like `[!NOTE]`)
 - rust-lang/rust#145155 (Port `#[allow_internal_unsafe]` to the new attribute system (attempt 2))
 - rust-lang/rust#145214 (fix: re-enable self-assignment)
 - rust-lang/rust#145216 (rustdoc: correct negative-to-implicit discriminant display)
 - rust-lang/rust#145238 (Tweak invalid builtin attribute output)
 - rust-lang/rust#145249 (Rename entered trace span variables from `_span` to  `_trace`)
 - rust-lang/rust#145251 (Support using #[unstable_feature_bound] on trait)
 - rust-lang/rust#145253 (Document compiler and stdlib in stage1 in `pr-check-2` CI job)
 - rust-lang/rust#145260 (Make explicit guarantees about `Vec`’s allocator)
 - rust-lang/rust#145263 (Update books)
 - rust-lang/rust#145273 (Account for new `assert!` desugaring in `!condition` suggestion)
 - rust-lang/rust#145283 (Make I-miscompile imply I-prioritize)
 - rust-lang/rust#145291 (bootstrap: Only warn about `rust.debug-assertions` if downloading rustc)
 - rust-lang/rust#145292 (Fix a typo in range docs)

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

Author: bors

src/stability.md

@@ -182,6 +182,11 @@ of the standard library raises it to a warning with
 `#![warn(deprecated_in_future)]`.
 
 ## unstable_feature_bound
-The `#[unstable_feature_bound(foo)]` attribute can be used together with `#[unstable]` attribute to mark an `impl` of stable type and stable trait as unstable. In std/core, an item annotated with `#[unstable_feature_bound(foo)]` can only be used by another item that is also annotated with `#[unstable_feature_bound(foo)]`. Outside of std/core, using an item with `#[unstable_feature_bound(foo)]` requires the feature to be enabled with `#![feature(foo)]` attribute on the crate. Currently, only `impl`s and free functions can be annotated with `#[unstable_feature_bound]`.
+The `#[unstable_feature_bound(foo)]` attribute can be used together with `#[unstable]` attribute to mark an `impl` of stable type and stable trait as unstable. In std/core, an item annotated with `#[unstable_feature_bound(foo)]` can only be used by another item that is also annotated with `#[unstable_feature_bound(foo)]`. Outside of std/core, using an item with `#[unstable_feature_bound(foo)]` requires the feature to be enabled with `#![feature(foo)]` attribute on the crate.
+
+Currently, the items that can be annotated with `#[unstable_feature_bound]` are:
+- `impl`
+- free function
+- trait
 
 [blog]: https://www.ralfj.de/blog/2018/07/19/const.html