GNU bug report logs - #77985
31.0.50; infinite loop in `make-frame-names-alist`

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From: martin rudalics <rudalics <at> gmx.at>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: abdo.haji.ali <at> gmail.com, 77985 <at> debbugs.gnu.org
Subject: bug#77985: 31.0.50; infinite loop in `make-frame-names-alist`
Date: Sat, 26 Apr 2025 20:51:42 +0200

> What about detecting when we made a full circle through all the
> candidate frames, and stopping at that point?  Is that feasible?

Hard to tell.  next_frame itself already fails to do that.

  while (passed < 2)
    FOR_EACH_FRAME (tail, f)
      {
	if (passed)
	  {
	    f = candidate_frame (f, frame, minibuf);
	    if (!NILP (f))
	      return f;
	  }
	if (EQ (frame, f))
	  passed++;
      }
  return frame;

If candidate_frame returns nil for FRAME, f is never set to FRAME and
passed is never incremented.  This could be fixed as

--- a/src/frame.c
+++ b/src/frame.c
@@ -2205,7 +2205,7 @@ candidate_frame (Lisp_Object candidate, Lisp_Object frame, Lisp_Object minibuf)
 static Lisp_Object
 next_frame (Lisp_Object frame, Lisp_Object minibuf)
 {
-  Lisp_Object f, tail;
+  Lisp_Object f, f1, tail;
   int passed = 0;

   eassume (CONSP (Vframe_list));
@@ -2215,9 +2215,9 @@ next_frame (Lisp_Object frame, Lisp_Object minibuf)
       {
 	if (passed)
 	  {
-	    f = candidate_frame (f, frame, minibuf);
-	    if (!NILP (f))
-	      return f;
+	    f1 = candidate_frame (f, frame, minibuf);
+	    if (!NILP (f1))
+	      return f1;
 	  }
 	if (EQ (frame, f))
 	  passed++;

But 'make-frame-names-alist', since it never sees frame set to
current-frame here,

    (while (not (eq frame current-frame))
      (progn
	(push (cons (frame-parameter frame 'name) frame) falist)
	(setq frame (next-frame frame 0))))

endlessly pushes the other frame to falist.

martin

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