Documentation comments shouldn't affect the diagnostic derive in any
way, but explicit support has to be added for ignoring the `doc`
attribute.

Signed-off-by: David Wood <david.wood@huawei.com>

Sometimes it is convenient to return a subdiagnostic enum where one or
more of the variants don't add anything to the diagnostic.

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

Signed-off-by: David Wood <david.wood@huawei.com>

…tions

…rait

This commit changes things so that the search bar is exactly centered between
the top of the page and the top of the source code content area.

…so-supertrait, r=fee1-dead

Elaborate supertrait bounds when triggering `unused_must_use` on `impl Trait`

Given `impl Trait`, if one of its supertraits has a `#[must_use]`, then trigger the lint. This means that, for example, `-> impl ExactSizeIterator` also triggers the `must_use` on `trait Iterator`, which fixes rust-lang#102183.

This might need `@rust-lang/lang` sign-off, since it changes the behavior of the lint, so cc'ing them.

… r=oli-obk

Filtering spans when emitting json

According to the issue rust-lang#102902, we shouldn't emit spans which have an empty span and no suggested replacement.

…r=compiler-errors

translation: doc comments with derives, subdiagnostic-less enum variants, more derive use

- Adds support for `doc` attributes in the diagnostic derives so that documentation comments don't result in the derive failing.
- Adds support for enum variants in the subdiagnostic derive to not actually correspond to an addition to a diagnostic.
- Made use of the derive in more places in the `rustc_ast_lowering`, `rustc_ast_passes`, `rustc_lint`, `rustc_session`, `rustc_infer` - taking advantage of recent additions like eager subdiagnostics, multispan suggestions, etc.

cc rust-lang#100717

Account for hygiene in typo suggestions, and use them to point to shadowed names

Fixes rust-lang#97459

r? `@estebank`

…dead

Fixup a few tests needing asm support

…p-bar-layout, r=GuillaumeGomez

rustdoc: improve appearance of source page navigation bar

This commit changes things so that the search bar is exactly centered between the top of the page and the top of the source code content area.

Preview: https://notriddle.com/notriddle-rustdoc-demos/source-page-header/src/std/lib.rs.html

## Before

![image](https://user-images.githubusercontent.com/1593513/197053420-02a64627-48ed-4bb6-9363-a1863d47b092.png)

## After

![image](https://user-images.githubusercontent.com/1593513/197053355-bd6149f9-0f5c-47da-aeb7-590b5eecb5da.png)