This makes all tower subcrates have the following lints as warn (rather
than allow): `missing_docs`, `rust_2018_idioms`, `unreachable_pub`, and
`missing_debug_implementations`. In addition, it consistently applies
`deny(warning)` *only* under CI so that deprecations and macro changes in minor
version bumps in dependencies will never cause `tower` crates to stop
compiling, and so that tests can be run even if not all warnings have been
dealt with. See also https://github.com/rust-unofficial/patterns/blob/master/anti_patterns/deny-warnings.md
Note that `tower-reconnect` has the `missing_docs` lint disabled for now
since it contained _no_ documentation previously. Also note that this
patch does not add documentation to the various `new` methods, as they
are considered self-explanatory. They are instead marked as
`#[allow(missing_docs)]`.
This change introduces the new `tower-layer` crate and the foundational `Layer` trait to go along with it. This trait allows one to easily compose a set of `Service`s that take an inner service. These services only modify the request/response. This also provides the `Layer` implementation for many of the tower crates.
Steven Fackler
Lucio Franco
David Barsky
Jon Gjengset
Taiki Endo
Carl Lerche