tracing: Replace pin-project with pin-project-lite (#1185)

* futures: Replace pin-project by pin-project-lite
* tower: Replace pin-project by pin-project-lite

Co-authored-by: Eliza Weisman <eliza@buoyant.io>
Co-authored-by: David Barsky <me@davidbarsky.com>

tracing-futures/Cargo.toml

@@ -21,14 +21,14 @@ license = "MIT"
 default = ["std-future", "std"]
 futures-01 = ["futures_01", "std"]
 futures-03 = ["std-future", "futures", "futures-task", "std"]
-std-future = ["pin-project"]
+std-future = ["pin-project-lite"]
 std = ["tracing/std"]
 
 [dependencies]
 futures_01 = { package = "futures", version = "0.1", optional = true }
 futures = { version = "0.3.0", optional = true }
 futures-task = { version = "0.3", optional = true }
-pin-project = { version = "1.0", optional = true }
+pin-project-lite = { version = "0.2.4", optional = true }
 tracing = { path = "../tracing", version = "0.1", default-features = false }
 tokio-executor = { version = "0.1", optional = true }
 tokio = { version = "0.1", optional = true }

tracing-futures/src/lib.rs

@@ -103,7 +103,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(docsrs, feature(doc_cfg), deny(broken_intra_doc_links))]
 #[cfg(feature = "std-future")]
-use pin_project::pin_project;
+use pin_project_lite::pin_project;
 
 pub(crate) mod stdlib;
 
@@ -242,30 +242,44 @@ pub trait WithSubscriber: Sized {
     }
 }
 
+#[cfg(feature = "std-future")]
+pin_project! {
+    /// A future, stream, sink, or executor that has been instrumented with a `tracing` span.
+    #[derive(Debug, Clone)]
+    pub struct Instrumented<T> {
+        #[pin]
+        inner: T,
+        span: Span,
+    }
+}
+
 /// A future, stream, sink, or executor that has been instrumented with a `tracing` span.
-#[cfg_attr(feature = "std-future", pin_project)]
+#[cfg(not(feature = "std-future"))]
 #[derive(Debug, Clone)]
 pub struct Instrumented<T> {
-    #[cfg(feature = "std-future")]
-    #[pin]
-    inner: T,
-    #[cfg(not(feature = "std-future"))]
     inner: T,
     span: Span,
 }
 
+#[cfg(all(feature = "std", feature = "std-future"))]
+pin_project! {
+    /// A future, stream, sink, or executor that has been instrumented with a
+    /// `tracing` subscriber.
+    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+    #[derive(Clone, Debug)]
+    pub struct WithDispatch<T> {
+        #[pin]
+        inner: T,
+        dispatch: Dispatch,
+    }
+}
+
 /// A future, stream, sink, or executor that has been instrumented with a
 /// `tracing` subscriber.
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", not(feature = "std-future")))]
 #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
-#[cfg_attr(feature = "std-future", pin_project)]
 #[derive(Clone, Debug)]
 pub struct WithDispatch<T> {
-    // cfg_attr doesn't work inside structs, apparently...
-    #[cfg(feature = "std-future")]
-    #[pin]
-    inner: T,
-    #[cfg(not(feature = "std-future"))]
     inner: T,
     dispatch: Dispatch,
 }

tracing-tower/Cargo.toml

@@ -20,7 +20,7 @@ license = "MIT"
 default = ["tower-layer", "tower-make", "http"]
 tower-make = [
     "tower_make",
-    "pin-project",
+    "pin-project-lite",
 ]
 
 [dependencies]
@@ -30,7 +30,7 @@ futures = "0.3"
 tower-service = "0.3"
 tower-layer = { version = "0.3", optional = true }
 tower_make = { package = "tower-make", version = "0.3", optional = true }
-pin-project = { version = "1.0", optional = true }
+pin-project-lite = { version = "0.2.4", optional = true }
 http = { version = "0.2", optional = true }
 
 [badges]

tracing-tower/src/request_span.rs

@@ -79,7 +79,7 @@ pub use self::make::MakeService;
 #[cfg_attr(docsrs, doc(cfg(feature = "tower-make")))]
 pub mod make {
     use super::*;
-    use pin_project::pin_project;
+    use pin_project_lite::pin_project;
 
     #[derive(Debug)]
     pub struct MakeService<S, R, G = fn(&R) -> tracing::Span> {
@@ -99,13 +99,14 @@ pub mod make {
         _p: PhantomData<fn(T, R)>,
     }
 
-    #[pin_project]
+    pin_project! {
-    #[derive(Debug)]
+        #[derive(Debug)]
-    pub struct MakeFuture<F, R, G = fn(&R) -> tracing::Span> {
+        pub struct MakeFuture<F, R, G = fn(&R) -> tracing::Span> {
-        get_span: Option<G>,
+            get_span: Option<G>,
-        #[pin]
+            #[pin]
-        inner: F,
+            inner: F,
-        _p: PhantomData<fn(R)>,
+            _p: PhantomData<fn(R)>,
+        }
     }
 
     #[cfg(feature = "tower-layer")]

tracing-tower/src/service_span.rs

@@ -79,7 +79,7 @@ mod layer {
 #[cfg_attr(docsrs, doc(cfg(feature = "tower-layer")))]
 pub mod make {
     use super::*;
-    use pin_project::pin_project;
+    use pin_project_lite::pin_project;
 
     #[derive(Debug)]
     pub struct MakeService<M, T, R, G = fn(&T) -> tracing::Span>
@@ -91,12 +91,13 @@ pub mod make {
         _p: PhantomData<fn(T, R)>,
     }
 
-    #[pin_project]
+    pin_project! {
-    #[derive(Debug)]
+        #[derive(Debug)]
-    pub struct MakeFuture<F> {
+        pub struct MakeFuture<F> {
-        #[pin]
+            #[pin]
-        inner: F,
+            inner: F,
-        span: Option<tracing::Span>,
+            span: Option<tracing::Span>,
+        }
     }
 
     #[derive(Debug)]