use boxed trait method where appropriate

actix-http/src/response.rs

@@ -194,7 +194,7 @@ impl<B> Response<B> {
     where
         B: MessageBody + 'static,
     {
-        self.map_body(|_, body| BoxBody::new(body))
+        self.map_body(|_, body| body.boxed())
     }
 
     /// Returns body, consuming this response.

awc/src/any_body.rs

@@ -45,9 +45,7 @@ impl AnyBody {
     where
         B: MessageBody + 'static,
     {
-        Self::Body {
-            body: BoxBody::new(body),
-        }
+        Self::Body { body: body.boxed() }
     }
 
     /// Constructs new `AnyBody` instance from a slice of bytes by copying it.

src/response/response.rs

@@ -244,8 +244,7 @@ impl<B> HttpResponse<B> {
     where
         B: MessageBody + 'static,
     {
-        // TODO: avoid double boxing with down-casting, if it improves perf
-        self.map_body(|_, body| BoxBody::new(body))
+        self.map_body(|_, body| body.boxed())
     }
 
     /// Extract response body

src/service.rs

@@ -451,7 +451,7 @@ impl<B> ServiceResponse<B> {
     where
         B: MessageBody + 'static,
     {
-        self.map_body(|_, body| BoxBody::new(body))
+        self.map_body(|_, body| body.boxed())
     }
 }