Coalesce inherent implementations with the same parameters

ec8d12e
Opened by Jacob Hoffman-Andrews at 2021-10-23 17:41:29

Some types have multiple inherent impls that don't differ in terms of type parameters, but are just ways of organizing the code. For instance, NonZeroU16 and friends:

image

Vec has some impls that are different from each other, but also impl<T, A> Vec<T, A> shows up two separate times:

image

We should coalesce these into a single impl block for each set of distinct parameters.

This came up while working on #85492: When I added sub-headings in the sidebar for multiple impls, I realized many more types than I thought had multiple impls.

  1. Some types have multiple inherent impls that don't differ in terms of type parameters, but are just ways of organizing the code. For instance, NonZeroU16 and friends:

    image

    Vec has some impls that are different from each other, but also impl<T, A: Allocator> Vec<T, A> shows up two separate times:

    image

    We should coalesce these into a single impl block for each set of distinct parameters.

    This came up while working on #85492: When I added sub-headings in the sidebar for multiple impls, I realized many more types than I thought had multiple impls.

    Jacob Hoffman-Andrews at 2021-10-20 06:53:00

  2. I agree. I've been wanting to fix this for a while :)

    Noah Lev at 2021-10-20 17:23:33

  3. FWIW I currently (ab?)use this to provide docs for groups of related inherent methods: https://docs.rs/hexavalent/0.1.7/hexavalent/struct.PluginHandle.html#impl-2 https://github.com/notdijon/hexavalent/blob/1b72806b761fe8c9cfdefc50018f4e16f26867a1/src/plugin.rs#L803-L901

    notdijon at 2021-10-23 17:01:30

  4. Great feedback @notdijon, thanks! I've been thinking that it would be useful for rustdoc to have some notion of explicit grouping, aside from the implicit grouping that happens with different implementations. That could be used, for instance, to group related functions together on a single page. Right now functions always have their own page, which means it's harder to see relationships. It also means for some crates that are extremely function-heavy, we generate huge numbers of pages.

    Jacob Hoffman-Andrews at 2021-10-23 17:41:29