When given `struct Foo(usize)` and using it as `Foo {}` or `Foo`, point at
`Foo`'s definition in the error.

When encountering code like the following:

```rust
fn main() {
    match 3 {
        4 => 1,
        3 => {
            println!("Yep it maches.");
            2
        }
        _ => 2
    }
    println!("Bye!")
}
```

point at the enclosing `match` expression and suggest ignoring the
returned value:

```
error[E0308]: mismatched types
  --> $DIR/match-needing-semi.rs:8:13
   |
LL | /     match 3 {
LL | |         4 => 1,
LL | |         3 => {
LL | |             2
   | |             ^ expected (), found integer
LL | |         }
LL | |         _ => 2
LL | |     }
   | |     -- help: consider using a semicolon here
   | |_____|
   |       expected this to be `()`
   |
   = note: expected type `()`
              found type `{integer}
```

Fix rust-lang#40799.

Fuse parsing of `self` into `parse_param_general`.

Point at definition when misusing ADT

When given `struct Foo(usize)` and using it as `Foo {}` or `Foo`, point at `Foo`'s definition in the error.

…-E0533, r=Centril

Add long error explanation for E0533

Part of rust-lang#61137

Point at enclosing match when expecting `()` in arm

When encountering code like the following:

```rust
fn main() {
    match 3 {
        4 => 1,
        3 => {
            println!("Yep it maches.");
            2
        }
        _ => 2
    }
    println!("Bye!")
}
```

point at the enclosing `match` expression and suggest ignoring the
returned value:

```
error[E0308]: mismatched types
  --> $DIR/match-needing-semi.rs:8:13
   |
LL | /     match 3 {
LL | |         4 => 1,
LL | |         3 => {
LL | |             2
   | |             ^ expected (), found integer
LL | |         }
LL | |         _ => 2
LL | |     }
   | |     -- help: consider using a semicolon here
   | |_____|
   |       expected this to be `()`
   |
   = note: expected type `()`
              found type `{integer}
```

Fix rust-lang#40799.

Add support for relating slices in `super_relate_consts`

This allows passing strings as generic arguments.

Fixes rust-lang#63773
Fixes rust-lang#60813

r? @varkor

syntax: fix dropping of attribute on first param of non-method assocated fn

Fixes rust-lang#64682.

The general idea is that we bake parsing of `self` into `parse_param_general` and then we just use standard list parsing. Overall, this simplifies the parsing and makes it more consistent.

r? @petrochenkov cc @c410-f3r

fixed typo

Accidentally had a typo in rust-lang#64884, sorry!