Remove pin-project dependency

The only thing it was generating is written out into the source instead.

Author: jplatte

tower/Cargo.toml

@@ -64,7 +64,7 @@ retry = ["__common", "tokio/time"]
 spawn-ready = ["__common", "futures-util", "tokio/sync", "tokio/rt", "util", "tracing"]
 steer = []
 timeout = ["pin-project-lite", "tokio/time"]
-util = ["__common", "futures-util", "pin-project"]
+util = ["__common", "futures-util"]
 
 [dependencies]
 tower-layer = { version = "0.3.1", path = "../tower-layer" }
@@ -80,7 +80,6 @@ tokio = { version = "1", optional = true, features = ["sync"] }
 tokio-stream = { version = "0.1.0", optional = true }
 tokio-util = { version = "0.6.3", default-features = false, optional = true }
 tracing = { version = "0.1.2", optional = true }
-pin-project = { version = "1", optional = true }
 pin-project-lite = { version = "0.2.7", optional = true }
 
 [dev-dependencies]

tower/src/util/either.rs

@@ -3,7 +3,6 @@
 //! See [`Either`] documentation for more details.
 
 use futures_core::ready;
-use pin_project::pin_project;
 use std::{
     future::Future,
     pin::Pin,
@@ -17,13 +16,28 @@ use tower_service::Service;
 /// Both services must be of the same request, response, and error types.
 /// [`Either`] is useful for handling conditional branching in service middleware
 /// to different inner service types.
-#[pin_project(project = EitherProj)]
 #[derive(Clone, Debug)]
 pub enum Either<A, B> {
     /// One type of backing [`Service`].
-    A(#[pin] A),
+    A(A),
     /// The other type of backing [`Service`].
-    B(#[pin] B),
+    B(B),
+}
+
+impl<A, B> Either<A, B> {
+    fn project(self: Pin<&mut Self>) -> EitherProj<'_, A, B> {
+        unsafe {
+            match self.get_unchecked_mut() {
+                Self::A(a) => EitherProj::A(Pin::new_unchecked(a)),
+                Self::B(b) => EitherProj::B(Pin::new_unchecked(b)),
+            }
+        }
+    }
+}
+
+enum EitherProj<'p, A: 'p, B: 'p> {
+    A(Pin<&'p mut A>),
+    B(Pin<&'p mut B>),
 }
 
 impl<A, B, Request> Service<Request> for Either<A, B>