Rustdoc: allow submodule navigation from crate-level index

[bstrie]

An excerpt from the Rust stdlib crate index page ( http://doc.rust-lang.org/doc/std/index.html ):

• Module net
• Module os
• Module os_fs

The os and os_fs modules both have submodules with their own pages, but currently the only way to access these pages (or even know they exist) is to visit the os or os_fs pages themselves and notice the links at the bottom of the table of contents. Showing submodules on the index page would ease navigation and exploration:

• Module net
• Module os
  • Module os::libc_constants
  • Native module os::libc
  • Native module os::rustrt
• Module os_fs
  • Native module os_fs::rustrt

[catamorphism]

Nominating for milestone 4, well-covered (having documentation tools work the way we expect is helpful in making sure the documentation covers everything...)

[graydon]

we have an attribute to force documentation already, this is a nice feature but should not block a milestone

[graydon]

just a bug, removing milestone/nomination.

[emberian]

#8125

/cc @Seldaek

[emberian]

@Seldaek to implement this would it be possible to have a tree browser of the entire module tree? Along the lines of http://docs.sencha.com/extjs/4.2.1/#!/api, over on the left

[Seldaek]

Sounds feasible on the main crate page yes, since we only show the other
crates on the left, there is room for a module tree there. I'll add to
the TODOs but not as release critical.

[alexcrichton]

I actually think that the search performs and excellent job of solving this problem. There are already a large number of modules listed at the top of the std/extra crates, so I'm not sure we'd want to clutter it more.

Seeing a mock of this though would be kinda cool to see what it'd be like.

[emberian]

ping @bstrie

[alexcrichton]

Closing, this bug is specific to the quite old rustdoc now, and the new rustdoc handles this much differently. I think at this point this bug should be reopened to retarget the new rustdoc if it's still an issue.