- Make clear that the `Pointer` trait is related to formatting
- Make clear that `&T` (shared reference) implements `Send` (if `T: Send + Sync`)

Co-authored-by: fmease <liehr.exchange@gmx.net>

Use h3 and h4 for the variant name and the "Fields" subheading.
Remove the "of T" part of the "Fields" subheading.
Remove border-bottom from "Fields" subheading.
Move docblock below "Fields" listing.

This is a revert of e950d22 which is no
longer needed since Clang now does normalization and handles all triple
spellings.

Be more thorough in using `ItemObligation` and `BindingObligation` when
evaluating obligations so that we can point at trait bounds that
introduced unfulfilled obligations. We no longer incorrectly point at
unrelated trait bounds (`substs-ppaux.verbose.stderr`).

In particular, we now point at trait bounds on method calls.

We no longer point at "obvious" obligation sources (we no longer have a
note pointing at `Trait` saying "required by a bound in `Trait`", like
in `associated-types-no-suitable-supertrait*`).

Address part of rust-lang#89418.

`predicates_of` no longer changes when changing a trait's front matter
because we no longer include the trait's span in the identity trait
obligation.

Group obligations by `impl` block that introduced them.

The basic problem with this is that rustdoc, when hunting for `fn main`, will stop
parsing after it reaches a fatal error. This unexpected semicolon was a fatal error,
so in `src/test/rustdoc-ui/failed-doctest-extra-semicolon-on-item.rs`, it would wrap
the doctest in an implied main function, turning it into this:

    fn main() {
        struct S {};
        fn main() {
            assert_eq!(0, 1);
        }
    }

This, as it turns out, is totally valid, and it executes no assertions, so *it passes,*
even though the user wanted it to execute the assertion.

The Rust parser already has the ability to recover from these unexpected semicolons,
but to do so, it needs to use the `parse_mod` function, so this commit changes it to do that.

Makes docs for references a little less confusing

- Make clear that the `Pointer` trait is related to formatting
- Make clear that the `Pointer` trait is implemented for references (previously it was confusing to first see that it's implemented and then see it in "expect")
- Make clear that `&T` (shared reference) implements `Send` (if `T: Send + Sync`)

…=nagisa

Point at source of trait bound obligations in more places

Be more thorough in using `ItemObligation` and `BindingObligation` when
evaluating obligations so that we can point at trait bounds that
introduced unfulfilled obligations. We no longer incorrectly point at
unrelated trait bounds (`substs-ppaux.verbose.stderr`).

In particular, we now point at trait bounds on method calls.

We no longer point at "obvious" obligation sources (we no longer have a
note pointing at `Trait` saying "required by a bound in `Trait`", like
in `associated-types-no-suitable-supertrait*`).

We no longer point at associated items (`ImplObligation`), as they didn't
add any user actionable information, they just added noise.

Address part of rust-lang#89418.

…d,GuillaumeGomez

Improve display of enum variants

Use h3 and h4 for the variant name and the "Fields" subheading.
Remove the "of T" part of the "Fields" subheading.
Remove border-bottom from "Fields" subheading.
Move docblock below "Fields" listing.

Fixes rust-lang#90061

Demo:

https://jacob.hoffman-andrews.com/rust/xmlparser-updated/xmlparser/enum.Token.html#variants
https://jacob.hoffman-andrews.com/rust/fix-enum-variants/std/io/enum.ErrorKind.html#variants
https://jacob.hoffman-andrews.com/rust/fix-enum-variants/std/result/enum.Result.html#variants

r? `@camelid`

…ebank

Switch to normalized triples for Fuchsia

This is a revert of e950d22 which is no
longer needed since Clang now does normalization and handles all triple
spellings.

…ents, r=estebank

Improve suggestions for compatible variants on type mismatch.

Fixes rust-lang#90553.

Before:
![image](https://user-images.githubusercontent.com/783247/140385675-6ff41090-eca2-41bc-b161-99c5dabfec61.png)

After:
![image](https://user-images.githubusercontent.com/783247/140385748-20cf26b5-ea96-4e56-8af2-5fe1ab16fd3b.png)

r? ````@estebank````

fix CTFE/Miri simd_insert/extract on array-style repr(simd) types

The changed test would previously fail since `place_index` would just return the only field of `f32x4`, i.e., the array -- rather than *indexing into* the array which is what we have to do.

The new helper methods will also be needed for rust-lang/miri#1912.

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

…-semicolon, r=jyn514

rustdoc doctest: detect `fn main` after an unexpected semicolon

Fixes rust-lang#91014

The basic problem with this is that rustdoc, when hunting for `fn main`, will stop parsing after it reaches a fatal error. This unexpected semicolon was a fatal error, so in `src/test/rustdoc-ui/failed-doctest-extra-semicolon-on-item.rs`, it would wrap the doctest in an implied main function, turning it into this:

    fn main() {
        struct S {};
        fn main() {
            assert_eq!(0, 1);
        }
    }

This, as it turns out, is totally valid, and it executes no assertions, so *it passes,* even though the user wanted it to execute the assertion.

The Rust parser already has the ability to recover from these unexpected semicolons, but to do so, it needs to use the `parse_mod` function, so this PR changes it to do that.

…ty-line, r=camelid

Put back removed empty line

Fixes comment from rust-lang#90438 (comment).

r? `@camelid`

Turn all 0x1b_u8 into '\x1b' or b'\x1b'

Supersedes rust-lang#91040