1 files changed, 20 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-16668.rs b/tests/ui/issues/issue-16668.rs
new file mode 100644
index 00000000000..92efb42fe30
--- /dev/null
+++ b/tests/ui/issues/issue-16668.rs
@@ -0,0 +1,20 @@
+// check-pass
+#![allow(dead_code)]
+struct Parser<'a, I, O> {
+    parse: Box<dyn FnMut(I) -> Result<O, String> + 'a>
+}
+
+impl<'a, I: 'a, O: 'a> Parser<'a, I, O> {
+    fn compose<K: 'a>(mut self, mut rhs: Parser<'a, O, K>) -> Parser<'a, I, K> {
+        Parser {
+            parse: Box::new(move |x: I| {
+                match (self.parse)(x) {
+                    Ok(r) => (rhs.parse)(r),
+                    Err(e) => Err(e)
+                }
+            })
+        }
+    }
+}
+
+fn main() {}