address review comments

actix-http/src/body/boxed.rs

@@ -8,12 +8,13 @@ use std::{
 use bytes::Bytes;
 
 use super::{BodySize, MessageBody, MessageBodyMapErr};
+use crate::body;
 
 /// A boxed message body with boxed errors.
 pub struct BoxBody(BoxBodyInner);
 
 enum BoxBodyInner {
-    None,
+    None(body::None),
     Bytes(Bytes),
     Stream(Pin<Box<dyn MessageBody<Error = Box<dyn StdError>>>>),
 }
@@ -29,7 +30,7 @@ impl BoxBody {
         B: MessageBody + 'static,
     {
         match body.size() {
-            BodySize::None => Self(BoxBodyInner::None),
+            BodySize::None => Self(BoxBodyInner::None(body::None)),
             _ => match body.try_into_bytes() {
                 Ok(bytes) => Self(BoxBodyInner::Bytes(bytes)),
                 Err(body) => {
@@ -60,8 +61,8 @@ impl MessageBody for BoxBody {
     #[inline]
     fn size(&self) -> BodySize {
         match &self.0 {
-            BoxBodyInner::None => BodySize::None,
-            BoxBodyInner::Bytes(bytes) => BodySize::Sized(bytes.len() as u64),
+            BoxBodyInner::None(none) => none.size(),
+            BoxBodyInner::Bytes(bytes) => bytes.size(),
             BoxBodyInner::Stream(stream) => stream.size(),
         }
     }
@@ -72,7 +73,7 @@ impl MessageBody for BoxBody {
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<Bytes, Self::Error>>> {
         match &mut self.0 {
-            BoxBodyInner::None => Poll::Ready(None),
+            BoxBodyInner::None(_) => Poll::Ready(None),
             BoxBodyInner::Bytes(bytes) => Pin::new(bytes).poll_next(cx).map_err(Into::into),
             BoxBodyInner::Stream(stream) => Pin::new(stream).poll_next(cx),
         }
@@ -81,7 +82,8 @@ impl MessageBody for BoxBody {
     #[inline]
     fn try_into_bytes(self) -> Result<Bytes, Self> {
         match self.0 {
-            BoxBodyInner::Bytes(bytes) => Ok(bytes),
+            BoxBodyInner::None(none) => Ok(none.try_into_bytes().unwrap()),
+            BoxBodyInner::Bytes(bytes) => Ok(bytes.try_into_bytes().unwrap()),
             _ => Err(self),
         }
     }

actix-http/src/body/message_body.rs

@@ -31,6 +31,9 @@ pub trait MessageBody {
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<Bytes, Self::Error>>>;
 
+    /// Convert this body into `Bytes`.
+    ///
+    /// Bodies with `BodySize::None` are allowed to return empty `Bytes`.
     fn try_into_bytes(self) -> Result<Bytes, Self>
     where
         Self: Sized,
@@ -369,7 +372,7 @@ mod tests {
     use bytes::{Bytes, BytesMut};
 
     use super::*;
-    use crate::body::{BoxBody, EitherBody};
+    use crate::body::{self, EitherBody};
 
     macro_rules! assert_poll_next {
         ($pin:expr, $exp:expr) => {
@@ -497,6 +500,21 @@ mod tests {
         assert_poll_next_none!(Pin::new(&mut body));
     }
 
+    #[actix_rt::test]
+    async fn none_body_combinators() {
+        fn none_body() -> BoxBody {
+            let body = body::None;
+            let body = BoxBody::new(body);
+            let body = EitherBody::<_, ()>::left(body);
+            let body = EitherBody::<(), _>::right(body);
+            body.boxed()
+        }
+
+        assert_eq!(none_body().size(), BodySize::None);
+        assert_eq!(none_body().try_into_bytes().unwrap(), Bytes::new());
+        assert_poll_next_none!(Pin::new(&mut none_body()));
+    }
+
     // down-casting used to be done with a method on MessageBody trait
     // test is kept to demonstrate equivalence of Any trait
     #[actix_rt::test]

actix-http/src/body/none.rs

@@ -40,4 +40,9 @@ impl MessageBody for None {
     ) -> Poll<Option<Result<Bytes, Self::Error>>> {
         Poll::Ready(Option::None)
     }
+
+    #[inline]
+    fn try_into_bytes(self) -> Result<Bytes, Self> {
+        Ok(Bytes::new())
+    }
 }

actix-http/src/encoding/encoder.rs

@@ -136,6 +136,7 @@ where
         Self: Sized,
     {
         match self {
+            EncoderBody::None => Ok(Bytes::new()),
             EncoderBody::Full { body } => Ok(body),
             _ => Err(self),
         }