test: add test for #4322

Author: cowboy-bebug

tests/source/issue_4322.rs

@@ -0,0 +1,3 @@
+trait Bar {
+  type X<'a> where Self: 'a;
+}

tests/target/issue_4322.rs

@@ -0,0 +1,5 @@
+trait Bar {
+    type X<'a>
+    where
+        Self: 'a;
+}