1 files changed, 22 insertions, 0 deletions
diff --git a/src/test/ui/traits/issue-6128.rs b/src/test/ui/traits/issue-6128.rs
new file mode 100644
index 000000000..07d92f8f8
--- /dev/null
+++ b/src/test/ui/traits/issue-6128.rs
@@ -0,0 +1,22 @@
+// run-pass
+
+use std::collections::HashMap;
+
+trait Graph<Node, Edge> {
+    fn f(&self, _: Edge);
+    fn g(&self, _: Node);
+}
+
+impl<E> Graph<isize, E> for HashMap<isize, isize> {
+    fn f(&self, _e: E) {
+        panic!();
+    }
+    fn g(&self, _e: isize) {
+        panic!();
+    }
+}
+
+pub fn main() {
+    let g : Box<HashMap<isize,isize>> = Box::new(HashMap::new());
+    let _g2 : Box<dyn Graph<isize,isize>> = g as Box<dyn Graph<isize,isize>>;
+}