From 06d18c1815639e7a84dea2819ea9ef946adfdcd2 Mon Sep 17 00:00:00 2001
From: Leonidas Zhak <70497898+LeonidasZhak@users.noreply.github.com>
Date: Sun, 7 Jun 2026 13:47:15 +0800
Subject: [PATCH] fix: col.names='none' suppresses print completely (#7735)

---
 R/print.data.table.R | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/R/print.data.table.R b/R/print.data.table.R
index 88ff4ea505..c812ba7ac6 100644
--- a/R/print.data.table.R
+++ b/R/print.data.table.R
@@ -126,8 +126,14 @@ print.data.table = function(x, topn=getOption("datatable.print.topn"),
     trunc.cols = length(not_printed) > 0L
   }
   print_default = function(x) {
-    if (col.names != "none") cut_colnames = identity
-    cut_colnames(print(x, right=TRUE, quote=quote, na.print=na.print))
+    if (col.names == "none") {
+      # #7735: blank column names in output directly instead of using cut_colnames,
+      #   which also drops data rows lacking row-number colons (row.names=FALSE)
+      colnames(x) = rep.int("", ncol(x))
+      writeLines(capture.output(print(x, right=TRUE, quote=quote, na.print=na.print)))
+    } else {
+      cut_colnames(print(x, right=TRUE, quote=quote, na.print=na.print))
+    }
     # prints names of variables not shown in the print
     if (trunc.cols) trunc_cols_message(not_printed, abbs, class, col.names)
   }
@@ -141,8 +147,6 @@ print.data.table = function(x, topn=getOption("datatable.print.topn"),
     print_default(toprint)
     return(invisible(x))
   }
-  if (col.names == "none")
-    colnames(toprint) = rep.int("", ncol(toprint))
   if (nrow(toprint)>20L && col.names == "auto")
     # repeat colnames at the bottom if over 20 rows so you don't have to scroll up to see them
     #   option to shut this off per request of Oleg Bondar on SO, #1482