Allow catchers to be async fn.

core/codegen/src/attribute/catch.rs

@@ -54,7 +54,7 @@ pub fn _catch(args: TokenStream, input: TokenStream) -> Result<TokenStream> {
     define_vars_and_mods!(req, catcher, Request, Response, ErrorHandlerFuture);
 
     // Determine the number of parameters that will be passed in.
-    let (fn_sig, inputs) = match catch.function.sig.inputs.len() {
+    let (_fn_sig, inputs) = match catch.function.sig.inputs.len() {
         0 => (quote!(fn() -> _), quote!()),
         1 => (quote!(fn(&#Request) -> _), quote!(#req)),
         _ => return Err(catch.function.sig.inputs.span()
@@ -71,10 +71,22 @@ pub fn _catch(args: TokenStream, input: TokenStream) -> Result<TokenStream> {
         .map(|ty| ty.span().into())
         .unwrap_or(Span::call_site().into());
 
+    let responder_stmt = if catch.function.sig.asyncness.is_some() {
+        quote_spanned! { return_type_span =>
+            let ___responder = #catcher(#inputs).await;
+        }
+    } else {
+        quote_spanned! { return_type_span =>
+            let ___responder = #catcher(#inputs);
+        }
+    };
+
     let catcher_response = quote_spanned!(return_type_span => {
-        // Emit this to force a type signature check.
-        let #catcher: #fn_sig = #user_catcher_fn_name;
-        let ___responder = #catcher(#inputs);
+        // TODO.async: fix this
+        // // Emit this to force a type signature check.
+        // let #catcher: #fn_sig = #user_catcher_fn_name;
+        let #catcher = #user_catcher_fn_name;
+        #responder_stmt
         ::rocket::response::Responder::respond_to(___responder, #req).await?
     });
 

core/codegen/tests/ui-fail/catch_type_errors.stderr

@@ -15,15 +15,23 @@ error[E0277]: the trait bound `bool: rocket::response::Responder<'_>` is not sat
    = note: required by `rocket::response::Responder::respond_to`
 
 error[E0308]: mismatched types
-  --> $DIR/catch_type_errors.rs:18:7
+  --> $DIR/catch_type_errors.rs:17:1
+   |
+17 | #[catch(404)]
+   | ^^^^^^^^^^^^^ expected bool, found reference
+   |
+   = note: expected type `bool`
+              found type `&'_b rocket::Request<'_>`
+
+error[E0277]: the trait bound `usize: rocket::response::Responder<'_>` is not satisfied
+  --> $DIR/catch_type_errors.rs:18:26
    |
 17 | #[catch(404)]
    | ------------- expected due to this
 18 | fn f3(_request: bool) -> usize {
-   |       ^^^^^^^^^^^^^^ expected `&rocket::Request<'_>`, found `bool`
+   |                          ^^^^^ the trait `rocket::response::Responder<'_>` is not implemented for `usize`
    |
-   = note: expected fn pointer `for<'r, 's> fn(&'r rocket::Request<'s>) -> _`
-                 found fn item `fn(bool) -> usize {f3}`
+   = note: required by `rocket::response::Responder::respond_to`
 
 error[E0277]: the trait bound `usize: rocket::response::Responder<'_>` is not satisfied
   --> $DIR/catch_type_errors.rs:24:12
@@ -33,7 +41,7 @@ error[E0277]: the trait bound `usize: rocket::response::Responder<'_>` is not sa
    |
    = note: required by `rocket::response::Responder::respond_to`
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0277, E0308.
 For more information about an error, try `rustc --explain E0277`.