generalize impl Responder for HttpResponse (#2567)

Co-authored-by: Rob Ede <robjtede@icloud.com>

CHANGES.md

@@ -1,6 +1,10 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+### Changed
+- `HttpResponse` can now be used as a `Responder` with any body type.
+
+[#2501]: https://github.com/actix/actix-web/pull/2501
 
 
 ## 4.0.0-beta.19 - 2022-01-04

Cargo.toml

@@ -118,6 +118,7 @@ futures-util = { version = "0.3.7", default-features = false, features = ["std"]
 rand = "0.8"
 rcgen = "0.8"
 rustls-pemfile = "0.2"
+static_assertions = "1"
 tls-openssl = { package = "openssl", version = "0.10.9" }
 tls-rustls = { package = "rustls", version = "0.20.0" }
 zstd = "0.9"

src/response/builder.rs

@@ -23,7 +23,7 @@ use cookie::{Cookie, CookieJar};
 
 use crate::{
     error::{Error, JsonPayloadError},
-    BoxError, HttpResponse,
+    BoxError, HttpRequest, HttpResponse, Responder,
 };
 
 /// An HTTP response builder.
@@ -424,6 +424,15 @@ impl Future for HttpResponseBuilder {
     }
 }
 
+impl Responder for HttpResponseBuilder {
+    type Body = BoxBody;
+
+    #[inline]
+    fn respond_to(mut self, _: &HttpRequest) -> HttpResponse<Self::Body> {
+        self.finish()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use actix_http::body;

src/response/customize_responder.rs

@@ -1,12 +1,9 @@
 use actix_http::{
-    body::{EitherBody, MessageBody},
+    body::EitherBody, error::HttpError, header::HeaderMap, header::TryIntoHeaderPair,
-    error::HttpError,
-    header::HeaderMap,
-    header::TryIntoHeaderPair,
     StatusCode,
 };
 
-use crate::{BoxError, HttpRequest, HttpResponse, Responder};
+use crate::{HttpRequest, HttpResponse, Responder};
 
 /// Allows overriding status code and headers for a [`Responder`].
 ///
@@ -143,7 +140,6 @@ impl<R: Responder> CustomizeResponder<R> {
 impl<T> Responder for CustomizeResponder<T>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
 {
     type Body = EitherBody<T::Body>;
 

src/response/responder.rs

@@ -7,7 +7,7 @@ use actix_http::{
 };
 use bytes::{Bytes, BytesMut};
 
-use crate::{BoxError, Error, HttpRequest, HttpResponse, HttpResponseBuilder};
+use crate::{Error, HttpRequest, HttpResponse};
 
 use super::CustomizeResponder;
 
@@ -57,15 +57,6 @@ pub trait Responder {
     }
 }
 
-impl Responder for HttpResponse {
-    type Body = BoxBody;
-
-    #[inline]
-    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
-        self
-    }
-}
-
 impl Responder for actix_http::Response<BoxBody> {
     type Body = BoxBody;
 
@@ -75,15 +66,6 @@ impl Responder for actix_http::Response<BoxBody> {
     }
 }
 
-impl Responder for HttpResponseBuilder {
-    type Body = BoxBody;
-
-    #[inline]
-    fn respond_to(mut self, _: &HttpRequest) -> HttpResponse<Self::Body> {
-        self.finish()
-    }
-}
-
 impl Responder for actix_http::ResponseBuilder {
     type Body = BoxBody;
 
@@ -96,7 +78,6 @@ impl Responder for actix_http::ResponseBuilder {
 impl<T> Responder for Option<T>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
 {
     type Body = EitherBody<T::Body>;
 
@@ -111,7 +92,6 @@ where
 impl<T, E> Responder for Result<T, E>
 where
     T: Responder,
-    <T::Body as MessageBody>::Error: Into<BoxError>,
     E: Into<Error>,
 {
     type Body = EitherBody<T::Body>;

src/response/response.rs

@@ -22,7 +22,7 @@ use {
     cookie::Cookie,
 };
 
-use crate::{error::Error, HttpResponseBuilder};
+use crate::{error::Error, HttpRequest, HttpResponseBuilder, Responder};
 
 /// An outgoing response.
 pub struct HttpResponse<B = BoxBody> {
@@ -311,6 +311,18 @@ impl Future for HttpResponse<BoxBody> {
     }
 }
 
+impl<B> Responder for HttpResponse<B>
+where
+    B: MessageBody + 'static,
+{
+    type Body = B;
+
+    #[inline]
+    fn respond_to(self, _: &HttpRequest) -> HttpResponse<Self::Body> {
+        self
+    }
+}
+
 #[cfg(feature = "cookies")]
 pub struct CookieIter<'a> {
     iter: std::slice::Iter<'a, HeaderValue>,
@@ -333,9 +345,16 @@ impl<'a> Iterator for CookieIter<'a> {
 
 #[cfg(test)]
 mod tests {
+    use static_assertions::assert_impl_all;
+
     use super::*;
     use crate::http::header::{HeaderValue, COOKIE};
 
+    assert_impl_all!(HttpResponse: Responder);
+    assert_impl_all!(HttpResponse<String>: Responder);
+    assert_impl_all!(HttpResponse<&'static str>: Responder);
+    assert_impl_all!(HttpResponse<crate::body::None>: Responder);
+
     #[test]
     fn test_debug() {
         let resp = HttpResponse::Ok()