Disallow type parameters to self. Closes #2422.

src/rustc/middle/typeck/astconv.rs

@@ -302,6 +302,7 @@ fn check_path_args(tcx: ty::ctxt,
             // n.b.: resolve guarantees that the self type only appears in an
             // iface, which we rely upon in various places when creating
             // substs
+            check_path_args(tcx, path, NO_TPS | NO_REGIONS);
             ty::mk_self(tcx)
           }
           _ {