From 36496b1446554143a16b9fc717de0c63cc335ef7 Mon Sep 17 00:00:00 2001
From: Sherlock Holo <sherlockya@gmail.com>
Date: Sun, 4 Feb 2024 17:18:08 +0800
Subject: [PATCH 1/2] feat: support default implement method

---
 trait-variant/examples/variant.rs |  8 ++++++++
 trait-variant/src/variant.rs      | 13 +++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/trait-variant/examples/variant.rs b/trait-variant/examples/variant.rs
index 04bcc6a..48c9c33 100644
--- a/trait-variant/examples/variant.rs
+++ b/trait-variant/examples/variant.rs
@@ -20,12 +20,20 @@ pub trait LocalIntFactory {
     fn stream(&self) -> impl Iterator<Item = i32>;
     fn call(&self) -> u32;
     fn another_async(&self, input: Result<(), &str>) -> Self::MyFut<'_>;
+    async fn default_method(&self) -> u32 {
+        1
+    }
+    fn sync_default_method(&self) -> u32 {
+        1
+    }
 }
 
 #[allow(dead_code)]
 fn spawn_task(factory: impl IntFactory + 'static) {
     tokio::spawn(async move {
         let _int = factory.make(1, "foo").await;
+        let _default_int = factory.default_method().await;
+        let _sync_default_int = factory.sync_default_method();
     });
 }
 
diff --git a/trait-variant/src/variant.rs b/trait-variant/src/variant.rs
index f7f0d27..3fb1933 100644
--- a/trait-variant/src/variant.rs
+++ b/trait-variant/src/variant.rs
@@ -150,12 +150,25 @@ fn transform_item(item: &TraitItem, bounds: &Vec<TypeParamBound>) -> TraitItem {
             ReturnType::Default => return item.clone(),
         }
     };
+
+    let default_impl = fn_item.default.as_ref().map(|default_impl| {
+        syn::parse2(quote! {
+            {
+                async move {
+                    #default_impl
+                }
+            }
+        })
+        .unwrap()
+    });
+
     TraitItem::Fn(TraitItemFn {
         sig: Signature {
             asyncness: None,
             output: ReturnType::Type(arrow, Box::new(output)),
             ..sig.clone()
         },
+        default: default_impl,
         ..fn_item.clone()
     })
 }

From 19765448beffe6afd775d66fbe448b8aeb5507af Mon Sep 17 00:00:00 2001
From: Sherlock Holo <sherlockya@gmail.com>
Date: Sun, 4 Feb 2024 19:52:35 +0800
Subject: [PATCH 2/2] fix: only wrap async fn body block

---
 trait-variant/examples/variant.rs |  4 ++++
 trait-variant/src/variant.rs      | 19 ++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/trait-variant/examples/variant.rs b/trait-variant/examples/variant.rs
index 48c9c33..6971ca6 100644
--- a/trait-variant/examples/variant.rs
+++ b/trait-variant/examples/variant.rs
@@ -20,6 +20,9 @@ pub trait LocalIntFactory {
     fn stream(&self) -> impl Iterator<Item = i32>;
     fn call(&self) -> u32;
     fn another_async(&self, input: Result<(), &str>) -> Self::MyFut<'_>;
+    fn default_stream(&self) -> impl Iterator<Item = i32> {
+        [1].into_iter()
+    }
     async fn default_method(&self) -> u32 {
         1
     }
@@ -33,6 +36,7 @@ fn spawn_task(factory: impl IntFactory + 'static) {
     tokio::spawn(async move {
         let _int = factory.make(1, "foo").await;
         let _default_int = factory.default_method().await;
+        let _default_stream = factory.default_stream();
         let _sync_default_int = factory.sync_default_method();
     });
 }
diff --git a/trait-variant/src/variant.rs b/trait-variant/src/variant.rs
index 3fb1933..1af07fe 100644
--- a/trait-variant/src/variant.rs
+++ b/trait-variant/src/variant.rs
@@ -152,14 +152,19 @@ fn transform_item(item: &TraitItem, bounds: &Vec<TypeParamBound>) -> TraitItem {
     };
 
     let default_impl = fn_item.default.as_ref().map(|default_impl| {
-        syn::parse2(quote! {
-            {
-                async move {
-                    #default_impl
+        // only wrap async fn block with async move {}
+        if sig.asyncness.is_some() {
+            syn::parse2(quote! {
+                {
+                    async move {
+                        #default_impl
+                    }
                 }
-            }
-        })
-        .unwrap()
+            })
+            .unwrap()
+        } else {
+            default_impl.clone()
+        }
     });
 
     TraitItem::Fn(TraitItemFn {