feature request: cargo doc should create an index page and doc pages should link to the index page

[andrewrk]

When I read online documentation, the docs are for the library assuming all the features are turned on. When I search with s I see traits, modules, and functions which are only available for certain features. If I have those features turned off in Cargo.toml then this documentation is at best distracting and at worst misleading. So, the generated documentation UI should provide checkboxes or some other way to toggle features on/off so that you can remove the features that you don't have on when browsing documentation.

I understand that this may require changes in rustdoc.

[andrewrk]

I think there is a better solution to this, and it is already part way implemented.

When you run cargo doc it creates documentation for all dependencies and takes into account features, which is great. But the generated documentation is missing an index page that lists all the crates.

I tried running cargo doc --open to see what page it defaulted to, but that feature appears to be broken for me.

The search functionality works with all the dependencies' docs together, which is great. I think additionally each doc page should link back to the index. (And there should be an index).

[huonw]

cc rust-lang/rust#16103 (cargo doc basically just calls rustdoc on the various crates.)

[alexcrichton]

Closing as a dupe of #1016