protected RuntimeException fallback(Object fobj) { String name = null; if (fobj instanceof RList) { name = lookupName((RList) fobj); name = name == UNKNOWN_EXTERNAL_BUILTIN ? null : name; if (name != null && lookupBuiltin((RList) fobj) != null) { /* * if we reach this point, then the cache saw a different value for f. the lists * that contain the information about native calls are never expected to change. */ throw RInternalError.shouldNotReachHere( "fallback reached for " + getRBuiltin().name() + " " + name); } } throw RError.nyi( this, getRBuiltin().name() + " specialization failure: " + (name == null ? "<unknown>" : name)); }