From 6c135e301290b6809288bf40eabd7b1d86373f8e Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 17 Aug 2023 16:27:57 +0100
Subject: [PATCH] W

---
 Cargo.toml  |  1 +
 src/main.rs | 36 ++++++++++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 00c5180..c68f178 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ edition = "2021"
 downcast-rs = "1"
 dumpster = "0.1.1"
 futures = "0.3.28"
+#parking_lot = "0.12.1"
 #tokio = { version = "1", features = ["full"] }
 #serde-value = "0.7"
 #serde = { version="1", features=["derive"] }
diff --git a/src/main.rs b/src/main.rs
index 9ce70ab..73a1024 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,36 @@
-use futures::channel::oneshot;
 
-enum Void {}
+use std::cell::RefCell;
+
+use dumpster::{Collectable, unsync::Gc};
+
+#[derive(Collectable, Debug)]
+struct Loopy {
+    value: u32,
+    loopy: RefCell<Option<Gc<Loopy>>>,
+}
+
+impl Drop for Loopy {
+    fn drop(&mut self) {
+        eprintln!(
+            "drop {:?} {:?}",
+            self.value,
+            self.loopy.borrow().as_ref().map(|gcl| gcl.value),
+        );
+    }
+}
 
 fn main() {
-    type F = futures::future::Shared<oneshot::Receiver<Void>>;
-    println!("{:?}", std::alloc::Layout::new::<F>());
+    let a = Gc::new(Loopy {
+        value: 42,
+        loopy: None.into(),
+    });
+    let b = Gc::new(Loopy {
+        value: 66,
+        loopy: None.into(),
+    });
+    *a.loopy.borrow_mut() = Some(b.clone());
+    *b.loopy.borrow_mut() = Some(a.clone());
+    drop(a);
+    drop(b);
+    
 }
-- 
2.30.2