… access

Co-authored-by: Andrew Hickman <andrew.hickman1@sky.com>

It is not always obvious that people could see the docs for `&`
especially for beginners, it also helps learnability.

This removes the incorrect error, but doesn't show the documentation
anywhere.

…r around documenting re-exports

Now this actually tests the links are generated correctly

…brary

Related to rust-lang#65354

- Pass through the replacement text to `markdown.rs`
- Add some tests
- Add a state machine that actually replaces the text when parsing Markdown

- Preserve suffixes when displaying
- Rename test file to match `intra-link*`
- Remove unnecessary .clone()s
- Improve comments and naming
- Fix more bugs and add tests
- Escape intra-doc link example in public documentation

Upgrade Chalk to 0.21

Two commits here. First commit actually does the upgrade. Second commit has some changes to make more tests in compare-mode=chalk pass.

The `PlaceholdersCollector` and `RegionsSubstitutor` bits are bit a hacky, but only insomuch as `ParamsSubstitutor` is. These won't be needed eventually.

r? @nikomatsakis

…crum

 BTreeMap: introduce marker::ValMut and reserve Mut for unique access

The mutable BTreeMap iterators (apart from `DrainFilter`) are double-ended, meaning they have to rely on a front and a back handle that each represent a reference into the tree. Reserve a type category `marker::ValMut` for them, so that we guarantee that they cannot reach operations on handles with borrow type `marker::Mut`and that these operations can assume unique access to the tree.

Including rust-lang#75195, benchmarks report no genuine change:
```
benchcmp old new --threshold 5
 name                                 old ns/iter  new ns/iter  diff ns/iter   diff %  speedup
 btree::map::iter_100                 3,333        3,023                -310   -9.30%   x 1.10
 btree::map::range_unbounded_vs_iter  36,624       31,569             -5,055  -13.80%   x 1.16
```

r? @Mark-Simulacrum

…asper

do not apply DerefMut on union field

This implements the part of [RFC 2514](https://github.com/rust-lang/rfcs/blob/master/text/2514-union-initialization-and-drop.md) about `DerefMut`. Unlike described in the RFC, we only apply this warning specifically when doing `DerefMut` of a `ManuallyDrop` field; that is really the case we are worried about here.

@matthewjasper suggested I patch `convert_place_derefs_to_mutable` and `convert_place_op_to_mutable` for this, but I could not find anything to do in `convert_place_op_to_mutable` and this is sufficient to make the test pass. However, maybe there are some other cases this misses? I have no familiarity with this code.

This is a breaking change *in theory*, if someone used `ManuallyDrop<T>` in a union field and relied on automatic `DerefMut`. But on stable this means `T: Copy`, so the `ManuallyDrop` is rather pointless.

Cc rust-lang#55149

Add a regression test for issue-72793

Adds a regression test for rust-lang#72793, which is fixed by rust-lang#75443. Note that this won't close the issue as the snippet still shows ICE with `-Zmir-opt-level=2`. But it makes sense to add a test anyway.

Enable some of profiler tests on Windows-gnu

CC rust-lang#61266

Because of force-push GitHub didn't let me reopen rust-lang#75184

Because of the GCC miscompilation, generated binaries either segfault or `.profraw` is malformed. Clang works fine but we can't use it on the CI.
However we can still test the IR for the proper instrumentation so let's do it.

…st-doc-alias, r=ollie27

Add check for doc alias on assoc const in trait impl

Fixes rust-lang#73721.

r? @ollie27

…ing_issues, r=steveklabnik

Unstable Book: add links to tracking issues for FFI features

`impl Rc::new_cyclic`

References rust-lang#75861

r? @Dylan-DPC

Link vec doc to & reference

It is not always obvious that people could see the docs for `&`
especially for beginners, it also helps learnability.

Remove disambiguators from intra doc link text

Closes rust-lang#65354.
r? @Manishearth

The commits are mostly atomic, but there might be some mix between them here and there. I recommend reading 'refactor ItemLink' and 'refactor RenderedLink' on their own though, lots of churn without any logic changes.

…uillaumeGomez

Fix intra-doc links on pub re-exports

Partial fix for rust-lang#76073 - This removes the incorrect error, but doesn't show the documentation anywhere.
r? @GuillaumeGomez

…odrAus

Use Arc::clone and Rc::clone in documentation

This PR replaces uses of `x.clone()` by `Rc::clone(&x)` (or `Arc::clone(&x)`) to better match the documentation for those types.

@rustbot modify labels: T-doc

Add missing link in README

Move some Vec UI tests into alloc unit tests

A bit of work towards rust-lang#76268, makes a number of the Vec UI tests that are simply running code into unit tests. Ensured that they are being run when testing liballoc locally.