Merge #64

64: Pinned drop bounds bug r=taiki-e a=Michael-J-Ward

The bug brought up in [this conversation](tower-rs/tower#594 (comment))

Simple fix, the parsing grammar wasn't handling trailing commas.

Co-authored-by: Michael J Ward <ward.michael.j@gmail.com>

src/lib.rs

@@ -1216,7 +1216,7 @@ macro_rules! __pin_project_internal {
                 $(: $where_clause_bound:path)?
                 $(: ?$where_clause_unsized_bound:path)?
                 $(: $where_clause_lifetime_bound:lifetime)?
-            ),*
+            ),* $(,)?
         )?
         {
             fn drop($($arg:ident)+: Pin<&mut Self>) {

tests/test.rs

@@ -665,4 +665,31 @@ fn pinned_drop() {
             }
         }
     }
+
+    trait Service<Request> {
+        type Error;
+    }
+
+    pin_project! {
+        struct Struct3<'a, T, Request>
+        where
+            T: Service<Request>,
+            T::Error: std::error::Error,
+        {
+            was_dropped: &'a mut bool,
+            #[pin]
+            field: T,
+            req: Request,
+        }
+
+        impl<T, Request> PinnedDrop for Struct3<'_, T, Request>
+        where
+            T: Service<Request>,
+            T::Error: std::error::Error,
+        {
+            fn drop(mut this: Pin<&mut Self>) {
+                **this.as_mut().project().was_dropped = true;
+            }
+        }
+    }
 }