Rustdoc should emit [src] link for "Implementors" section also for traits.

[vi]

It should work a bit like IDE's feature that finds everything that implements a given interface.

@QuietMisdreavus

[QuietMisdreavus]

This should be a fairly small change (the most annoying part has already been done) so i'll open this up as a mentored issue.

The bit that writes out the "Implementors" section is at the bottom of the item_trait function in src/librustdoc/html/render.rs. This is where the known implementors for a given trait are pulled out of the global context and listed out onto the rendered page.

The bit that's responsible for creating [src] links is the src_href method, implemented on a local Item type. This kind of Item is easily made from the kind of Item that's otherwise worked on in render.rs, but there's a catch: The entries in the Implementors list aren't clean::Items. They're clean::Impls, which are only a subset of the things you get on an Item. This is the "most annoying part" i mentioned earlier.

Fortunately, i ran into this when creating the "Implementations on Foreign Types" section, so if you scroll up a little in item_trait, you can see where i pulled out an Item for "foreign" impls so i could render the full impl block for them. The task for anyone who wants to take this on is to pull that up a little so that it's used for all the implementors, not just the foreign ones.

With a clean::Item in hand, combine it with the Context to create a render::Item and call src_href to generate the link. (Here's an example doing that for associated methods. This also helpfully includes the extra HTML bits that will flush the [src] link to the right edge, which is really the final step.)

And... that's it! The link should probably go between the fmt_impl_for_trait_page and the where clause underneath it, so that it's aligned with the impl line and not the where clause. You may need to also close/open the <code> that's wrapping the whole line to make sure the [src] link itself isn't monospace.

If you have any questions, let me know! Either comment here, or hop onto IRC in #rust-dev-tools, or the impl period Gitter under WG-docs-rustdoc.