1 files changed, 121 insertions, 0 deletions
diff --git a/tests/ui/dropck/dropck_trait_cycle_checked.rs b/tests/ui/dropck/dropck_trait_cycle_checked.rs
new file mode 100644
index 000000000..be6ec3e4e
--- /dev/null
+++ b/tests/ui/dropck/dropck_trait_cycle_checked.rs
@@ -0,0 +1,121 @@
+// Reject mixing cyclic structure and Drop when using trait
+// objects to hide the cross-references.
+//
+// (Compare against ui/span/dropck_vec_cycle_checked.rs)
+
+use std::cell::Cell;
+use id::Id;
+
+mod s {
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    static S_COUNT: AtomicUsize = AtomicUsize::new(0);
+
+    pub fn next_count() -> usize {
+        S_COUNT.fetch_add(1, Ordering::SeqCst) + 1
+    }
+}
+
+mod id {
+    use s;
+    #[derive(Debug)]
+    pub struct Id {
+        orig_count: usize,
+        count: usize,
+    }
+
+    impl Id {
+        pub fn new() -> Id {
+            let c = s::next_count();
+            println!("building Id {}", c);
+            Id { orig_count: c, count: c }
+        }
+        pub fn count(&self) -> usize {
+            println!("Id::count on {} returns {}", self.orig_count, self.count);
+            self.count
+        }
+    }
+
+    impl Drop for Id {
+        fn drop(&mut self) {
+            println!("dropping Id {}", self.count);
+            self.count = 0;
+        }
+    }
+}
+
+trait HasId {
+    fn count(&self) -> usize;
+}
+
+#[derive(Debug)]
+struct CheckId<T:HasId> {
+    v: T
+}
+
+#[allow(non_snake_case)]
+fn CheckId<T:HasId>(t: T) -> CheckId<T> { CheckId{ v: t } }
+
+impl<T:HasId> Drop for CheckId<T> {
+    fn drop(&mut self) {
+        assert!(self.v.count() > 0);
+    }
+}
+
+trait Obj<'a> : HasId {
+    fn set0(&self, b: &'a Box<dyn Obj<'a>>);
+    fn set1(&self, b: &'a Box<dyn Obj<'a>>);
+}
+
+struct O<'a> {
+    id: Id,
+    obj0: CheckId<Cell<Option<&'a Box<dyn Obj<'a>>>>>,
+    obj1: CheckId<Cell<Option<&'a Box<dyn Obj<'a>>>>>,
+}
+
+impl<'a> HasId for O<'a> {
+    fn count(&self) -> usize { self.id.count() }
+}
+
+impl<'a> O<'a> {
+    fn new() -> Box<O<'a>> {
+        Box::new(O {
+            id: Id::new(),
+            obj0: CheckId(Cell::new(None)),
+            obj1: CheckId(Cell::new(None)),
+        })
+    }
+}
+
+impl<'a> HasId for Cell<Option<&'a Box<dyn Obj<'a>>>> {
+    fn count(&self) -> usize {
+        match self.get() {
+            None => 1,
+            Some(c) => c.count(),
+        }
+    }
+}
+
+impl<'a> Obj<'a> for O<'a> {
+    fn set0(&self, b: &'a Box<dyn Obj<'a>>) {
+        self.obj0.v.set(Some(b))
+    }
+    fn set1(&self, b: &'a Box<dyn Obj<'a>>) {
+        self.obj1.v.set(Some(b))
+    }
+}
+
+
+fn f() {
+    let (o1, o2, o3): (Box<dyn Obj>, Box<dyn Obj>, Box<dyn Obj>) = (O::new(), O::new(), O::new());
+    o1.set0(&o2); //~ ERROR `o2` does not live long enough
+    o1.set1(&o3); //~ ERROR `o3` does not live long enough
+    o2.set0(&o2); //~ ERROR `o2` does not live long enough
+    o2.set1(&o3); //~ ERROR `o3` does not live long enough
+    o3.set0(&o1); //~ ERROR `o1` does not live long enough
+    o3.set1(&o2); //~ ERROR `o2` does not live long enough
+}
+
+fn main() {
+    f();
+}