Add #[must_use] to types and methods (#3395)

Co-authored-by: Theodore Bjernhed <[email protected]>

axum-core/src/body.rs

@@ -34,6 +34,7 @@ where
 }
 
 /// The body type used in axum requests and responses.
+#[must_use]
 #[derive(Debug)]
 pub struct Body(BoxBody);
 
@@ -135,6 +136,7 @@ impl http_body::Body for Body {
 /// A stream of data frames.
 ///
 /// Created with [`Body::into_data_stream`].
+#[must_use]
 #[derive(Debug)]
 pub struct BodyDataStream {
     inner: Body,

axum-core/src/error.rs

@@ -16,6 +16,7 @@ impl Error {
     }
 
     /// Convert an `Error` back into the underlying boxed trait object.
+    #[must_use]
     pub fn into_inner(self) -> BoxError {
         self.inner
     }

axum-core/src/macros.rs

@@ -106,11 +106,13 @@ macro_rules! __define_rejection {
             }
 
             /// Get the response body text used for this rejection.
+            #[must_use]
             pub fn body_text(&self) -> String {
                 self.to_string()
             }
 
             /// Get the status code used for this rejection.
+            #[must_use]
             pub fn status(&self) -> http::StatusCode {
                 http::StatusCode::$status
             }
@@ -179,6 +181,7 @@ macro_rules! __composite_rejection {
 
         impl $name {
             /// Get the response body text used for this rejection.
+            #[must_use]
             pub fn body_text(&self) -> String {
                 match self {
                     $(
@@ -188,6 +191,7 @@ macro_rules! __composite_rejection {
             }
 
             /// Get the status code used for this rejection.
+            #[must_use]
             pub fn status(&self) -> http::StatusCode {
                 match self {
                     $(