bug#54844: 29.0.50; pgtk: with --daemon, DISPLAY gets set to "wayland-0"

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Po Lu <luangruo@yahoo.com> writes:

> Yep, this is in the multi-TTY code.  I'll fix that.

Does this fix the problem?

diff --git a/src/callproc.c b/src/callproc.c
index 0922e10f01..1e74836682 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -85,6 +85,10 @@ #define _P_NOWAIT 1	/* from process.h */
 #include "nsterm.h"
 #endif
 
+#ifdef HAVE_PGTK
+#include "pgtkterm.h"
+#endif
+
 /* Pattern used by call-process-region to make temp files.  */
 static Lisp_Object Vtemp_file_name_pattern;
 
@@ -1812,6 +1816,18 @@ make_environment_block (Lisp_Object current_dir)
     if (NILP (display))
       {
 	Lisp_Object tmp = Fframe_parameter (selected_frame, Qdisplay);
+
+#ifdef HAVE_PGTK
+	/* The only time GDK actually returns correct information is
+	   when it's running under X Windows.  DISPLAY shouldn't be
+	   set to a Wayland display either, since that's an X specific
+	   variable.  */
+	if (FRAME_WINDOW_P (SELECTED_FRAME ())
+	    && strcmp (G_OBJECT_TYPE_NAME (FRAME_X_DISPLAY (SELECTED_FRAME ())),
+		       "GdkX11Display"))
+	  tmp = Qnil;
+#endif
+
 	if (!STRINGP (tmp) && CONSP (Vinitial_environment))
 	  /* If still not found, Look for DISPLAY in Vinitial_environment.  */
 	  tmp = Fgetenv_internal (build_string ("DISPLAY"),