rustdoc: Fix sidebar heading order

[tyilo]

Makes sidebar heading order match the order of the headings in the main content.

[rustbot]

r? @lolbinarycat

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[lolbinarycat]

please provide before/after screenshots, as well as your reasoning for why you believe the previous behavior to be incorrect.

[tyilo]

Before

Order in sidebar:

1. Provided Methods
2. Implementations on Foreign Types
3. Dyn Compatibility
4. Implementors

Order in content:

1. Provided Methods
2. Dyn Compatibility
3. Implementations on Foreign Types
4. Implementors

After

Order in sidebar & content:

1. Provided Methods
2. Dyn Compatibility
3. Implementations on Foreign Types
4. Implementors

---

Code used:

#![feature(associated_type_defaults)]

pub trait Foo {
    const REQUIRED: bool;
    const PROVIDED: bool = true;

    type REQUIRED;
    type PROVIDED = ();

    fn required() -> Self;
    fn provided() {}
}

// Foreign impl
impl Foo for () {
    const REQUIRED: bool = true;
    type REQUIRED = ();

    fn required() -> Self {
        ()
    }
}

pub struct Bar;

// Impl
impl Foo for Bar {
    const REQUIRED: bool = true;
    type REQUIRED = ();

    fn required() -> Self {
        Self
    }
}

fn main() {
    println!("Hello, world!");
}

[tyilo]

Hi @lolbinarycat do you think the explanation is satisfactory?

[lolbinarycat]

The explanation makes sense. The implementation is a bit finicky (adding, then removing and re-adding), but I can't easily think of a nicer way of doing it, so I suppose it's fine.

The one thing I would like to see is a rustdoc-html regression test.

[lolbinarycat]

I think it's worth moving this along and just adding the regression test in a followup.

@bors r+ rollup

[rust-bors]

📌 Commit 2d79bb6 has been approved by lolbinarycat

It is now in the queue for this repository.