Merge pull request #289 from dtolnay/cfg

Fix lifetime bounding on generic parameters that have cfg

Author: dtolnay

src/expand.rs

@@ -192,21 +192,29 @@ fn transform_sig(
                     Some(colon_token) => colon_token.span,
                     None => param_name.span(),
                 };
-                let bounds = mem::take(&mut param.bounds);
-                where_clause_or_default(&mut sig.generics.where_clause)
-                    .predicates
-                    .push(parse_quote_spanned!(span=> #param_name: 'async_trait + #bounds));
+                if param.attrs.is_empty() {
+                    let bounds = mem::take(&mut param.bounds);
+                    where_clause_or_default(&mut sig.generics.where_clause)
+                        .predicates
+                        .push(parse_quote_spanned!(span=> #param_name: 'async_trait + #bounds));
+                } else {
+                    param.bounds.push(parse_quote!('async_trait));
+                }
             }
             GenericParam::Lifetime(param) => {
                 let param_name = &param.lifetime;
                 let span = match param.colon_token.take() {
                     Some(colon_token) => colon_token.span,
                     None => param_name.span(),
                 };
-                let bounds = mem::take(&mut param.bounds);
-                where_clause_or_default(&mut sig.generics.where_clause)
-                    .predicates
-                    .push(parse_quote_spanned!(span=> #param: 'async_trait + #bounds));
+                if param.attrs.is_empty() {
+                    let bounds = mem::take(&mut param.bounds);
+                    where_clause_or_default(&mut sig.generics.where_clause)
+                        .predicates
+                        .push(parse_quote_spanned!(span=> #param: 'async_trait + #bounds));
+                } else {
+                    param.bounds.push(parse_quote!('async_trait));
+                }
             }
             GenericParam::Const(_) => {}
         }

tests/test.rs

@@ -1705,3 +1705,24 @@ pub mod issue283 {
         }
     }
 }
+
+// https://github.com/dtolnay/async-trait/issues/288
+pub mod issue288 {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    pub trait Trait {
+        async fn f<#[cfg(any())] T: Send>(#[cfg(any())] t: T);
+        async fn g<#[cfg(all())] T: Send>(#[cfg(all())] t: T);
+    }
+
+    pub struct Struct;
+
+    #[async_trait]
+    impl Trait for Struct {
+        async fn f<#[cfg(any())] T: Send>(#[cfg(any())] t: T) {}
+        async fn g<#[cfg(all())] T: Send>(#[cfg(all())] t: T) {
+            let _ = t;
+        }
+    }
+}