From 7099578f18b1ea6a168b1883fa7a4ac7f49fc08f Mon Sep 17 00:00:00 2001
From: Peter Oliver <git@mavit.org.uk>
Date: Sun, 14 Jul 2024 20:47:14 +0100
Subject: [PATCH 2/2] Fall back to the terminal from pure GTK when no display
 is available
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* src/dispnew.c (init_display_interactive): Only use PGTK windowing if
at least one of the environment variables WAYLAND_DISPLAY, DISPLAY,
BROADWAY_DISPLAY is set.  (Bug#63555)

This patch is not suitable for merging, because it doesn’t consider
what happens if you try to use PGTK on Windows or MacOS.
---
 src/dispnew.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/dispnew.c b/src/dispnew.c
index 7cf2b49273c..481d33a7302 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -6557,10 +6557,33 @@ init_display_interactive (void)
 #endif
 
 #ifdef HAVE_PGTK
-  if (!inhibit_window_system && !will_dump_p ())
+  if (!inhibit_window_system)
     {
-      Vinitial_window_system = Qpgtk;
-      return;
+      if (!display_arg && !will_dump_p ())
+	{
+	  int i;
+	  const char *gdk_display_variables[] = {
+	    "WAYLAND_DISPLAY",
+	    "DISPLAY",
+	    "BROADWAY_DISPLAY",
+	  };
+	  size_t n = ARRAYELTS (gdk_display_variables);
+
+	  for (i = 0; i < n; i++)
+	    {
+	      char *display;
+	      display = getenv (gdk_display_variables[i]);
+	      if (display != 0 && *display != 0)
+		{
+		  display_arg = 1;
+		  break;
+		}
+	    }
+	}
+      if (display_arg) {
+	Vinitial_window_system = Qpgtk;
+	return;
+      }
     }
 #endif
 
-- 
2.45.2