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diff --git a/gcc/text-art/box-drawing.cc b/gcc/text-art/box-drawing.cc
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+/* Procedural lookup of box drawing characters.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#define INCLUDE_VECTOR
+#include "system.h"
+#include "coretypes.h"
+#include "text-art/box-drawing.h"
+#include "selftest.h"
+#include "text-art/selftests.h"
+
+
+/* According to
+     https://en.wikipedia.org/wiki/Box-drawing_character#Character_code
+   "DOS line- and box-drawing characters are not ordered in any programmatic
+   manner, so calculating a particular character shape needs to use a look-up
+   table. "
+   Hence this array.  */
+static const cppchar_t box_drawing_chars[] = {
+#include "text-art/box-drawing-chars.inc"
+};
+
+cppchar_t
+text_art::get_box_drawing_char (directions line_dirs)
+{
+  const size_t idx = line_dirs.as_index ();
+  gcc_assert (idx < 16);
+  return box_drawing_chars[idx];
+}
+
+#if CHECKING_P
+
+namespace selftest {
+
+/* Run all selftests in this file.  */
+
+void
+text_art_box_drawing_cc_tests ()
+{
+  ASSERT_EQ (text_art::get_box_drawing_char
+	      (text_art::directions (false, false, false, false)),
+	     ' ');
+  ASSERT_EQ (text_art::get_box_drawing_char
+	       (text_art::directions (false, false, true, true)),
+	     0x2500); /* BOX DRAWINGS LIGHT HORIZONTAL */
+  ASSERT_EQ (text_art::get_box_drawing_char
+	       (text_art::directions (true, true, false, false)),
+	     0x2502); /* BOX DRAWINGS LIGHT VERTICAL */
+  ASSERT_EQ (text_art::get_box_drawing_char
+	       (text_art::directions (true, false, true, false)),
+	     0x2518); /* BOX DRAWINGS LIGHT UP AND LEFT */
+}
+
+} // namespace selftest
+
+#endif /* #if CHECKING_P */