1 files changed, 40 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/associated-types-projection-in-object-type.rs b/src/test/ui/associated-types/associated-types-projection-in-object-type.rs
new file mode 100644
index 000000000..eec95a141
--- /dev/null
+++ b/src/test/ui/associated-types/associated-types-projection-in-object-type.rs
@@ -0,0 +1,40 @@
+// run-pass
+#![allow(dead_code)]
+#![allow(unused_imports)]
+// Corrected regression test for #20831. The original did not compile.
+// When fixed, it revealed another problem concerning projections that
+// appear in associated type bindings in object types, which were not
+// being properly flagged.
+
+// pretty-expanded FIXME #23616
+
+use std::ops::{Shl, Shr};
+use std::cell::RefCell;
+
+pub trait Subscriber {
+    type Input;
+
+    fn dummy(&self) { }
+}
+
+pub trait Publisher<'a> {
+    type Output;
+    fn subscribe(&mut self, _: Box<dyn Subscriber<Input=Self::Output> + 'a>);
+}
+
+pub trait Processor<'a> : Subscriber + Publisher<'a> { }
+
+impl<'a, P> Processor<'a> for P where P : Subscriber + Publisher<'a> { }
+
+struct MyStruct<'a> {
+    sub: Box<dyn Subscriber<Input=u64> + 'a>
+}
+
+impl<'a> Publisher<'a> for MyStruct<'a> {
+    type Output = u64;
+    fn subscribe(&mut self, t : Box<dyn Subscriber<Input=u64> + 'a>) {
+        self.sub = t;
+    }
+}
+
+fn main() {}