rustdoc: Only show the original item for re-exported items in search results

[camelid]

Currently rustdoc will show all items that match the query string, even re-exported ones, which can be kind of frustrating when I get a bunch of results that are actually all the same thing:

I propose that instead we only index the original item, not any of the re-exports. I am not saying that we don't inline documentation from the original, just that we only store the original in the search index.

See also: #15723, #24305

[jyn514]

The original is not usually the canonical one, though :/ consider std::collections::HashMap, which is actually defined in std::collections::hash::map::HashMap.

I've been wanting #[canonical] for a while now and I think this would fit, see https://discord.com/channels/442252698964721669/459149231702278154/771465736190558258 for some discussion. Sorry I don't have a write-up anywhere.

[jyn514]

@camelid why did you open a new issue instead of using #15723? Is there something else going on?

[camelid]

My understanding was that this issue is a subset of what's talked about in #15723, and this way we have a way to track just this part of it. It looks like QuietMisdreavus commented about this at #15723 (comment), but it was long enough that I hadn't fully read it before :)

[jyn514]

I don't think there's anything in #15723 not covered here. The things listed in the description are just suggestions for fixing it, but after the discussion later in the issue it looks like they won't be the way it ends up being fixed.