Implement IntoResponse for Response<()> and response::Parts (#950)

* feat(axum-core): add IntoResponse for `http::response` types

* chore: narrow impl to `Response<()>`

* include extensions

* changelog

Co-authored-by: David Pedersen <david.pdrsn@gmail.com>

axum-core/CHANGELOG.md

@@ -8,7 +8,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 # Unreleased
 
 - **added:** Implement `IntoResponse` and `IntoResponseParts` for `http::Extensions` ([#975])
+- **added:** Implement `IntoResponse` for `(http::response::Parts, impl IntoResponse)` ([#950])
+- **added:** Implement `IntoResponse` for `(http::response::Response<()>, impl IntoResponse)` ([#950])
 
+[#950]: https://github.com/tokio-rs/axum/pull/950
 [#975]: https://github.com/tokio-rs/axum/pull/975
 
 # 0.2.3 (25. April, 2022)

axum-core/src/response/into_response.rs

@@ -404,6 +404,27 @@ where
     }
 }
 
+impl<R> IntoResponse for (http::response::Parts, R)
+where
+    R: IntoResponse,
+{
+    fn into_response(self) -> Response {
+        let (parts, res) = self;
+        (parts.status, parts.headers, parts.extensions, res).into_response()
+    }
+}
+
+impl<R> IntoResponse for (http::response::Response<()>, R)
+where
+    R: IntoResponse,
+{
+    fn into_response(self) -> Response {
+        let (template, res) = self;
+        let (parts, ()) = template.into_parts();
+        (parts, res).into_response()
+    }
+}
+
 macro_rules! impl_into_response {
     ( $($ty:ident),* $(,)? ) => {
         #[allow(non_snake_case)]