Add a test case for issue rust-lang#446

Author: fitzgen

tests/expectations/tests/issue-446.rs

@@ -0,0 +1,16 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(non_snake_case)]
+
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct List<Elem> {
+    pub next: *mut List<Elem>,
+}
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct PersistentRooted<GcThing> {
+    pub root_list: List<PersistentRooted<GcThing>>,
+}

tests/headers/issue-446.hpp

@@ -0,0 +1,11 @@
+// bindgen-flags: -- -std=c++14
+
+template <typename Elem>
+class List {
+    List<Elem> *next;
+};
+
+template <typename GcThing>
+class PersistentRooted {
+    List<PersistentRooted<GcThing>> root_list;
+};