Implement Hash for RingBuf
Implement PartialOrd for RingBuf
docs: Fix typo in container guide.
Remove an unneeded FIXME in coherence.rs

Also, let f; f = ...; is just wrong.
Hash the length of the RingBuf before hashing elements
auto merge of #16020 : nham/rust/ringbuf_hash_ord, r=alexcrichton

cc #15294
auto merge of #16026 : ruud-v-a/rust/patch-1, r=steveklabnik
auto merge of #16031 : arielb1/rust/remove_unneeded_fixme, r=kballard

The issue was fixed a month ago - remove the workaround.
rustdoc: show struct field docs when inlined

Some minor changes to the compiler to expose this information. Very
inconvenient since struct fields aren't an item. Adds (yet another) table to
metadata.

Closes #15739
rustdoc: remove extraneous .move_iter().collect()s

The impl of Clean for Vec obsoleted these long, long ago.
rustc: encode is_sugared_doc on ast::Attribute
auto merge of #16025 : cmr/rust/plugin-fields, r=alexcrichton

Some minor changes to the compiler to expose this information. Very
inconvenient since struct fields aren't an item.