diff -u 20161017/table.R 20161017_new/table.R
--- 20161017/table.R	2016-10-17 23:02:55.890625000 +0700
+++ 20161017_new/table.R	2016-10-17 23:07:01.375000000 +0700
@@ -52,7 +52,7 @@
 	stop("nothing to tabulate")
     if (length(args) == 1L && is.list(args[[1L]])) { ## e.g. a data.frame
 	args <- args[[1L]]
-	if (length(dnn) != length(args))
+	if (missing(dnn) || length(dnn) != length(args))
 	    dnn <- if (!is.null(argn <- names(args))) argn
 		   else paste(dnn[1L], seq_along(args), sep = ".")
     }
diff -u 20161017/xtabs.R 20161017_new/xtabs.R
--- 20161017/xtabs.R	2016-10-17 23:02:41.906250000 +0700
+++ 20161017_new/xtabs.R	2016-10-17 23:05:38.203125000 +0700
@@ -1,7 +1,7 @@
 #  File src/library/stats/R/xtabs.R
 #  Part of the R package, https://www.R-project.org
 #
-#  Copyright (C) 1995-2015 The R Core Team
+#  Copyright (C) 1995-2016 The R Core Team
 #
 #  This program is free software; you can redistribute it and/or modify
 #  it under the terms of the GNU General Public License as published by
@@ -58,7 +58,7 @@
     if(!sparse) {
 	x <-
 	    if(is.null(y))
-		do.call("table", by)
+		table(by)
 	    else if(NCOL(y) == 1L)
 		tapply(y, by, sum)
 	    else {