This avoids a subtle layout shift when switching from the crate page
to all items.

+ Add some information to the README.md

After removing the `map_in_place` method, which isn't much use because
modifying every element in a collection such as a `Vec` can be done
trivially with iteration.

rustdoc: include link on all.html location header

This avoids a subtle layout shift when switching from the crate page to all items.

## Before

| index.html | all.html |
|------------|----------|
| ![image](https://user-images.githubusercontent.com/1593513/222607866-4eac3f55-314c-4273-9664-503f2a79ad0a.png) | ![image](https://user-images.githubusercontent.com/1593513/222607895-2d6bac3b-f66a-47d4-b234-360f6f8e1ee3.png) |

## After

| index.html | all.html |
|------------|----------|
| ![image](https://user-images.githubusercontent.com/1593513/222607866-4eac3f55-314c-4273-9664-503f2a79ad0a.png) | ![image](https://user-images.githubusercontent.com/1593513/222607997-e72c48a0-02c7-42a7-80c2-cd6bed48bd15.png) |

StableMIR: Proof-of-concept implementation + test

This PR is part of the [project Stable MIR](https://github.com/rust-lang/project-stable-mir). The PR deletes old re-exports from rustc_smir and introduces a proof-of-concept implementation for APIs to retrieve crate information.

The implementation follows the [design described here](https://hackmd.io/XhnYHKKuR6-LChhobvlT-g?view), but instead of using separate crates for the implementation, it uses separate modules inside `rustc_smir`.

The API introduced at this point should be seen just as an example on how we are planning to structure the communication between tools and the compiler.

I have not explored yet what should be the right granularity, the best starting point for users, neither the best way to implement it.

r? ``````@oli-obk``````

Simplify `sort_by` calls

small cleanup

…, r=BoxyUwU

Suppress copy impl error when post-normalized type references errors

Suppress spurious errors from the `Copy` impl validity check when fields have bad types *post*-normalization, instead of just pre-normalization.

----

The const-generics test regressed recently due to rust-lang#107965, cc `````@BoxyUwU.`````
 * I think it's because `[_; 0u32]: Copy` now fails to hold because a nested obligation `ConstArgHasType(0u32, usize)` fails.
 * It's interesting that `[const_error]` shows up in the type only after normalization, though, but I'm pretty sure that it's due to the evaluate call that happens when normalizing unevaluated consts.

…-impl-message, r=WaffleLapkin

Tweak illegal `Copy` impl message

The phrase "may not" can both mean "is not able to" and "possibly does not". Disambiguate this by just using "cannot".
``@Lokathor`` expressed being annoyed by this [here](https://twitter.com/Lokathor/status/1633200313544089602?s=20).

Also drive-by fix for this extremely noisy message: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6a37275bc810f7846bfe191845b7d11d.

r? diagnostics

Rename `MapInPlace` as `FlatMapInPlace`.

After removing the `map_in_place` method, which isn't much use because modifying every element in a collection such as a `Vec` can be done trivially with iteration.

r? ``@lqd``

fix: evaluate with wrong obligation stack

fix rust-lang#108897
r? ``@lcnr``

…lip1995

Move Clippy tests back to their intended directory

See rust-lang#108674 (comment).

r? `@flip1995`