Remove defaults from trait params when using them in function definition

src/expand.rs

@@ -284,6 +284,17 @@ fn transform_block(
     };
 
     let mut outer_generics = generics.clone();
+    for p in &mut outer_generics.params {
+        match p {
+            GenericParam::Type(t) => {
+                let _ = t.default.take();
+            }
+            GenericParam::Const(c) => {
+                let _ = c.default.take();
+            }
+            GenericParam::Lifetime(_) => {}
+        }
+    }
     if !has_self {
         if let Some(mut where_clause) = outer_generics.where_clause {
             where_clause.predicates = where_clause

tests/test.rs

@@ -884,7 +884,7 @@ pub mod issue92 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/104
-mod issue104 {
+pub mod issue104 {
     use async_trait::async_trait;
 
     #[async_trait]
@@ -909,7 +909,7 @@ mod issue104 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/106
-mod issue106 {
+pub mod issue106 {
     use async_trait::async_trait;
     use std::future::Future;
 
@@ -941,7 +941,7 @@ mod issue106 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/110
-mod issue110 {
+pub mod issue110 {
     #![deny(clippy::all)]
 
     use async_trait::async_trait;
@@ -963,7 +963,7 @@ mod issue110 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/120
-mod issue120 {
+pub mod issue120 {
     #![deny(clippy::trivially_copy_pass_by_ref)]
 
     use async_trait::async_trait;
@@ -978,3 +978,21 @@ mod issue120 {
         async fn f(&self) {}
     }
 }
+
+// https://github.com/dtolnay/async-trait/pulls/123
+pub mod pull123 {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    trait Trait<T = ()> {
+        async fn f(&self) -> &str
+        where
+            T: 'async_trait,
+        {
+            "default"
+        }
+    }
+
+    #[async_trait]
+    impl<T> Trait<T> for () {}
+}