1 files changed, 13 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-8398.rs b/tests/ui/issues/issue-8398.rs
new file mode 100644
index 000000000..0ef39b6a6
--- /dev/null
+++ b/tests/ui/issues/issue-8398.rs
@@ -0,0 +1,13 @@
+// check-pass
+#![allow(dead_code)]
+// pretty-expanded FIXME #23616
+
+pub trait Writer {
+    fn write(&mut self, b: &[u8]) -> Result<(), ()>;
+}
+
+fn foo(a: &mut dyn Writer) {
+    a.write(&[]).unwrap();
+}
+
+pub fn main(){}