feat(client): expose connect types without proto feature (#2377)

Make it possible to refer to Connected, Connection, HttpConnector, etc.
without enabling either of the http1/http2 features. This makes feature
selection work better for downstream libraries like hyper-openssl, which
don't want to commit to any particular protocol.

Fix #2376.

src/client/connect/http.rs

@@ -27,6 +27,7 @@ use super::{Connected, Connection};
 ///
 /// Sets the [`HttpInfo`](HttpInfo) value on responses, which includes
 /// transport information such as the remote socket address used.
+#[cfg_attr(docsrs, doc(cfg(feature = "tcp")))]
 #[derive(Clone)]
 pub struct HttpConnector<R = GaiResolver> {
     config: Arc<Config>,

src/client/connect/mod.rs

@@ -83,13 +83,20 @@ use std::fmt;
 
 use ::http::Extensions;
 
-#[cfg(feature = "tcp")]
-pub mod dns;
-#[cfg(feature = "tcp")]
-mod http;
-#[cfg(feature = "tcp")]
-pub use self::http::{HttpConnector, HttpInfo};
-pub use self::sealed::Connect;
+cfg_feature! {
+    #![feature = "tcp"]
+
+    pub use self::http::{HttpConnector, HttpInfo};
+
+    pub mod dns;
+    mod http;
+}
+
+cfg_feature! {
+    #![any(feature = "http1", feature = "http2")]
+
+    pub use self::sealed::Connect;
+}
 
 /// Describes a type returned by a connector.
 pub trait Connection {
@@ -260,6 +267,7 @@ where
     }
 }
 
+#[cfg(any(feature = "http1", feature = "http2"))]
 pub(super) mod sealed {
     use std::error::Error as StdError;
 

src/client/pool.rs

@@ -10,7 +10,7 @@ use futures_channel::oneshot;
 #[cfg(feature = "runtime")]
 use tokio::time::{Duration, Instant, Interval};
 
-use super::Ver;
+use super::client::Ver;
 use crate::common::{task, exec::Exec, Future, Pin, Poll, Unpin};
 
 // FIXME: allow() required due to `impl Trait` leaking types to this lint

src/lib.rs

@@ -58,7 +58,11 @@
 
 #[doc(hidden)]
 pub use http;
-#[cfg(any(feature = "http1", feature = "http2"))]
+#[cfg(any(
+    feature = "http1",
+    feature = "http2",
+    all(feature = "client", feature = "tcp")
+))]
 #[macro_use]
 extern crate tracing;
 
@@ -89,9 +93,11 @@ cfg_proto! {
 }
 
 cfg_feature! {
-    #![all(feature = "client", any(feature = "http1", feature = "http2"))]
+    #![all(feature = "client")]
 
     pub mod client;
+    #[cfg(any(feature = "http1", feature = "http2"))]
+    #[doc(no_inline)]
     pub use crate::client::Client;
 }
 

src/proto/h1/io.rs

@@ -91,6 +91,7 @@ where
         self.read_buf_strategy = ReadStrategy::Exact(sz);
     }
 
+    #[cfg(feature = "server")]
     pub fn set_write_strategy_flatten(&mut self) {
         // this should always be called only at construction time,
         // so this assert is here to catch myself
@@ -475,6 +476,7 @@ impl<B> WriteBuf<B>
 where
     B: Buf,
 {
+    #[cfg(feature = "server")]
     fn set_strategy(&mut self, strategy: WriteStrategy) {
         self.strategy = strategy;
     }