…ce used to create an `IntoIter` from its parts

(suggested in the review of the previous attempt to add `ArrayChunks`)

As explained in the review of the previous attempt to add `ArrayChunks`,
adapters that shrink the length can't implement `TrustedLen`.

It doesn't seem to be used at all.

The "fallback" naming pre-dates introduction of `-Clink-self-contained`

Those intrinsics either panic or do nothing. They are safe.

…llot

Delay a span bug if we see ty/const generic params during writeback

Fixes rust-lang#99566

orphan check: rationalize our handling of constants

cc `@rust-lang/types` `@rust-lang/project-const-generics` on whether you agree with this reasoning.

r? types

Add `Iterator::array_chunks` (take N+1)

A revival of rust-lang#92393.

r? `@Mark-Simulacrum`
cc `@rossmacarthur` `@scottmcm` `@the8472`

I've tried to address most of the review comments on the previous attempt. The only thing I didn't address is `try_fold` implementation, I've left the "custom" one for now, not sure what exactly should it use.

Suggest removing `let` if `const let` or `let const` is used

Closes rust-lang#99910

rustc_target: Update some old naming around self contained linking

The "fallback" naming pre-dates introduction of `-Clink-self-contained`.
Noticed when reviewing rust-lang#99500.

This PR doesn't break any json target spec, but supporting per-linker-flavor startup objects needed by rust-lang#99500 will break them, so maybe next time I'll remove the compatibility names.

`assert_{inhabited,zero_valid,uninit_valid}` intrinsics are safe

Those intrinsics either panic or do nothing. They are safe.

Rollup of 6 pull requests

Successful merges:

 - rust-lang#99582 (Delay a span bug if we see ty/const generic params during writeback)
 - rust-lang#99861 (orphan check: rationalize our handling of constants)
 - rust-lang#100026 (Add `Iterator::array_chunks` (take N+1))
 - rust-lang#100115 (Suggest removing `let` if `const let` or `let const` is used)
 - rust-lang#100126 (rustc_target: Update some old naming around self contained linking)
 - rust-lang#100487 (`assert_{inhabited,zero_valid,uninit_valid}` intrinsics are safe)

Failed merges:

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

…ogether, r=notriddle

rustdoc: Merge source code pages HTML elements together

We realized that the HTML generated for the source code pages could be improved quite a lot. This PR is a first pass toward this goal. Some explanations: it merges similar classes elements (even when there are white characters in between).

There is an exception to this: if this is an ident, I also merged it with "unclassified" elements. This part is up to debate and can be very easily removed as the check is performed in one place (in the `can_merge` function).

EDIT: The `ident` is now only kept in the code for the `span` it contains but it is not rendered into the HTML.

So now some numbers:

For these ones, on each page, I run this JS: `document.getElementsByTagName('*').length`. The goal is to count the number of DOM elements. I took some pages that seemed big, but don't hesitate to check some others.

| file name | before this PR | with this PR | diff | without ident | diff |
|-|-|-|-|-|-|
| std/lib.rs.html (source link on std crate page) | 3455 | 2776 | 20.7% | 2387 | 31% |
| alloc/vec/mod.rs.html (source on Vec type page) | 11012 | 8084 | 26.6% | 6682 | 39.4% |
| alloc/string.rs.html (source on String type page) | 10800 | 8214 | 24% | 6712 | 37.9% |
| std/sync/mutex.rs.html (source on Mutex type page) | 2953 | 2403 | 18.7% | 2139 | 27.6% |

You can test it [here](https://rustdoc.crud.net/imperio/merge-html-elements-together/src/std/lib.rs.html).

cc `@jsha`
r? `@notriddle`

When checking `'sup: 'sub`, take placeholder elements into account.

This wasn't a problem previously (I hope!) because `eval_outlives` was
only used for type_tests, which don't have higher-ranked outlive
relations.