Type alias ident checking
diff --git a/syntax/ident.rs b/syntax/ident.rs
index 41eef3b..7545e92 100644
--- a/syntax/ident.rs
+++ b/syntax/ident.rs
@@ -42,7 +42,9 @@
                     check(cx, &arg.ident);
                 }
             }
-            Api::TypeAlias(_alias) => unimplemented!(),
+            Api::TypeAlias(alias) => {
+                check(cx, &alias.ident);
+            }
         }
     }
 }