This change updates the future and task API as discussed in the stabilization RFC at rust-lang/rfcs#2592.

Changes:
- Replacing UnsafeWake with RawWaker and RawWakerVtable
- Removal of LocalWaker
- Removal of Arc-based Wake trait

Co-Authored-By: Matthias247 <matthias.einwag@live.com>

- Point at the body expression of the match arm with the type error.
- Point at the prior match arms explicitely stating the evaluated type.
- Point at the entire match expr in a secondary span, instead of primary.
- For type errors in the first match arm, the cause is outside of the
  match, treat as implicit block error to give a more appropriate error.

Use footnote style to bypass the tidy check

Improve the code snippet suggested in suggestion-diagnostics when
suggesting the use of as_ref.

From 104 bytes to 72 bytes on x86-64. This slightly reduces instruction
counts.

Also add an assertion about the size.

…stebank

suggestion-diagnostics: as_ref improve snippet

Improve the code snippet suggested in suggestion-diagnostics when
suggesting the use of as_ref.

Given:

```rust
fn test(x: &usize) {}
fn main() {
    Some(42).map(|x| test(x));
}
```

Suggest

```
  help: consider using `as_ref` instead: `as_ref().map`
```

Instead of

```
  help: consider using `as_ref` instead: `as_ref().`
```

…veklabnik

Convert old first edition links to current edition one

r? @steveklabnik

Update the future/task API

This change updates the future and task API as discussed in the stabilization RFC at rust-lang/rfcs#2592.

Changes:
- Replacing UnsafeWake with RawWaker and RawWakerVtable
- Removal of LocalWaker
- Removal of Arc-based Wake trait

…aelwoerister

Reduce the size of `hir::Expr`.

From 104 bytes to 72 bytes on x86-64. This slightly reduces instruction
counts.

Also add an assertion about the size.

Tweak "incompatible match arms" error

- Point at the body expression of the match arm with the type error.
- Point at the prior match arms explicitly stating the evaluated type.
- Point at the entire match expr in a secondary span, instead of primary.
- For type errors in the first match arm, the cause is outside of the
  match, treat as implicit block error to give a more appropriate error.

Fix rust-lang#46776, fix rust-lang#57206.
CC rust-lang#24157, rust-lang#38234.

Hidden suggestion support

Add way to hide suggestion snippet window from cli output to avoid cluttered spans that don't enhance understanding.

r? @pietroalbini CC @zackmdavis

Enable comparing fat pointers

Also refactor our binops a bit to make that happen more easily.

r? @oli-obk

Extract block to insert an intrinsic into its own function

r? @eddyb