Rollup of 5 pull requests

Successful merges:

 - rust-lang#97366 (Stabilize `{slice,array}::from_ref`)
 - rust-lang#97653 (add cast kind of from_exposed_addr (int-to-ptr casts))
 - rust-lang#97663 (take back half-baked noaliasing check in Assignment)
 - rust-lang#97664 (On E0204 suggest missing type param bounds)
 - rust-lang#97668 (rustdoc: clean up primitive.slice.html links)

Failed merges:

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

Since rust-lang#97668 was merged, the slice::get function now looks like this:

![image](https://user-images.githubusercontent.com/1593513/173430685-1dd2b275-2439-4392-b7d4-96bcb355a377.png)

That whole thing, `[T]`, is a single link to `primitive.slice.html`. This
definitely fixes it for this case, but it's not obvious what we should do for
slices of concrete types:

![image](https://user-images.githubusercontent.com/1593513/173430968-7eed1aec-b688-4f84-a492-9210aff0037a.png)

There are actually three links in that `[u8]`: the opening brace `[` is a
link to `primitive.slice.html`, the `u8` is a link to `primitive.u8.html`,
and the final `]` is a link to `primitive.slice.html`. This is a serious
[usability bug](https://usability.yale.edu/web-accessibility/articles/links):
the square braces are much too small for anyone who doesn't have perfect
motor control using mouse or touch, provide an excessive number of tab stops
for anyone using keyboard, and no visual indication whatsoever that they're
separate links.

Now that slices of generic types are linked, it seems reasonable to err on
the side of less clutter and stop linking concrete slices to the slice page.

…, r=jsha

rustdoc:  remove link on slice brackets

This is rust-lang#91778, take two.

Fixes rust-lang#91173

The reason I'm reevaluating this change is rust-lang#97668, which makes fully-generic slices link to the slice docs page. This fixes some downsides in the original PR, where `Box<[T]>`, for example, was not linked to the primitive.slice.html page. In this PR, the `[T]` inside is still a link.

The other major reason for wanting to reevaluate this is the changed color scheme. When this feature was first introduced in rustdoc, primitives were a different color from structs and enums. This way, eagle-eyed users could figure out that the square brackets were separate links from the structs inside. Now, all types have the same color, so a significant fraction of users won't even know the links are there unless they pay close attention to the status bar or use an accessibility tool that lists all links on the page.

…, r=jsha

rustdoc:  remove link on slice brackets

This is rust-lang#91778, take two.

Fixes rust-lang#91173

The reason I'm reevaluating this change is rust-lang#97668, which makes fully-generic slices link to the slice docs page. This fixes some downsides in the original PR, where `Box<[T]>`, for example, was not linked to the primitive.slice.html page. In this PR, the `[T]` inside is still a link.

The other major reason for wanting to reevaluate this is the changed color scheme. When this feature was first introduced in rustdoc, primitives were a different color from structs and enums. This way, eagle-eyed users could figure out that the square brackets were separate links from the structs inside. Now, all types have the same color, so a significant fraction of users won't even know the links are there unless they pay close attention to the status bar or use an accessibility tool that lists all links on the page.