Look at this beauty:

```rust
error: unresolved link to `S::h`
  --> intra-link-errors.rs:51:6
   |
51 | /// [type@S::h]
   |      ^^^^^^^^^ help: to link to the associated function, use its disambiguator: `S::h()`
   |
   = note: this link resolves to the associated function `h`, which is not in the type namespace
```

…space

Before:
```
   = note: this link partially resolves to the struct `S`
   = note: no `fmt` in `S`
```

After:
```
   = note: the struct `S` has no field or associated item named `fmt`
```

Previously, when looking for the associated items for primitives,
rustdoc would look for primitives in the current namespace.
But all primitives are in the type namespace. To fix this, rustdoc now
always looks for primitives in the namespace when considering them as a
stepping stone to the associated item.

However, fixing that bug caused several duplicate errors because rustdoc
now reports the same error in each namespace. To avoid this, rustdoc now
ignores all duplicate errors when issuing them.

…sambiguator

Before:

```
warning: unresolved link to `m`
 --> m.rs:1:6
  |
1 | /// [value@m]
  |      ^^^^^^^
  |
  = note: `#[warn(broken_intra_doc_links)]` on by default
  = note: no item named `m` is in scope
  = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
```

After:

```
warning: unresolved link to `m`
 --> m.rs:1:6
  |
1 | /// [value@m]
  |      ^^^^^^^ help: to link to the macro, use its disambiguator: `m!`
  |
  = note: `#[warn(broken_intra_doc_links)]` on by default
  = note: this link resolves to the macro `m`, which is not in the value namespace
```

- Remove unneeded lifetime parameter
- Comment why some code doesn't use `check_full_res`

Before, it would arbitrarily pick the third-to-last if the last three or
more did not resolve.

This is both more specific and easier to read.

Previously, this called `check_full_res` for values and types, but not
macros. This would result in not showing when there was a partial
resolution for a parent of the item.

This now calls `check_full_res`. Additionally, it checks if there was a
disambiguator, and if so, says that specific kind wasn't found instead
of saying generically 'associated item'.

Moves this detection into `resolution_failure` to avoid doing
unnecessary work and make the control flow a little easier to work with.

This decreases the size of the `Result`s being returned,
improving performance in the common case.

This puts the error message closer to the link, making it easier to see
what went wrong.

'not in scope' -> 'not in `module`'