Preserve the span of self argument

src/expand.rs

@@ -258,7 +258,7 @@ fn transform_block(
 
     let inner = format_ident!("__{}", sig.ident);
     let args = sig.inputs.iter().enumerate().map(|(i, arg)| match arg {
-        FnArg::Receiver(_) => quote!(self),
+        FnArg::Receiver(Receiver { self_token, .. }) => quote!(#self_token),
         FnArg::Typed(arg) => {
             if let Pat::Ident(PatIdent { ident, .. }) = &*arg.pat {
                 quote!(#ident)

tests/test.rs

@@ -556,18 +556,33 @@ pub mod issue45 {
 pub mod issue46 {
     use async_trait::async_trait;
 
-    macro_rules! implement_commands {
+    macro_rules! implement_commands_workaround {
         ($tyargs:tt : $ty:tt) => {
             #[async_trait]
-            pub trait AsyncCommands: Sized {
+            pub trait AsyncCommands1: Sized {
                 async fn f<$tyargs: $ty>(&mut self, x: $tyargs) {
                     self.f(x).await
                 }
             }
         };
     }
 
-    implement_commands!(K: Send);
+    implement_commands_workaround!(K: Send);
+
+    macro_rules! implement_commands {
+        (
+            $tyargs:ident : $ty:ident
+        ) => {
+            #[async_trait]
+            pub trait AsyncCommands2: Sized {
+                async fn f<$tyargs: $ty>(&mut self, x: $tyargs) {
+                    self.f(x).await
+                }
+            }
+        };
+    }
+
+    implement_commands! { K: Send }
 }
 
 // https://github.com/dtolnay/async-trait/issues/53
@@ -867,3 +882,27 @@ pub mod issue92 {
         }
     }
 }
+
+mod issue104 {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    trait T1 {
+        async fn id(&self) -> i32;
+    }
+
+    macro_rules! impl_t1 {
+        ($ty: ty, $id: expr) => {
+            #[async_trait]
+            impl T1 for $ty {
+                async fn id(&self) -> i32 {
+                    $id
+                }
+            }
+        };
+    }
+
+    struct Foo;
+
+    impl_t1!(Foo, 1);
+}