Type alias type info
diff --git a/syntax/types.rs b/syntax/types.rs
index 2ab8cbd..987d618 100644
--- a/syntax/types.rs
+++ b/syntax/types.rs
@@ -96,7 +96,13 @@
                         visit(&mut all, ret);
                     }
                 }
-                Api::TypeAlias(_alias) => unimplemented!(),
+                Api::TypeAlias(alias) => {
+                    let ident = &alias.ident;
+                    if !type_names.insert(ident) {
+                        duplicate_name(cx, alias, ident);
+                    }
+                    cxx.insert(ident);
+                }
             }
         }