Add after-delete-frame-functions

Instead of working around the behavior delete-frame-functions, just
add an after-delete-frame-functions hook.

* doc/lispref/frames.texi (Deleting Frames): Document
`after-delete-frame-functions'.

* etc/NEWS: Mention `after-delete-frame-functions'.

* lisp/frame.el (blink-cursor--should-blink):
(blink-cursor--rescan-frames, blink-frame-mode): Get rid of the
ugly ignored-frame parameter and switch from
`delete-frame-functions' to `after-delete-frame-functions'.

* src/frame.c (syms_of_frame): New variable
`after-delete-frame-functions'.
(delete_frame): Use it.

4 files changed, 38 insertions, 18 deletions

diff --git a/doc/lispref/frames.texi b/doc/lispref/frames.texi
index 3a97ec01384..5e8b5b46d5d 100644
--- a/doc/lispref/frames.texi
+++ b/doc/lispref/frames.texi
@@ -2530,6 +2530,7 @@ it.
 
 @deffn Command delete-frame &optional frame force
 @vindex delete-frame-functions
+@vindex after-delete-frame-functions
 This function deletes the frame @var{frame}.  The argument @var{frame}
 must specify a live frame (see below) and defaults to the selected
 frame.
@@ -2541,7 +2542,9 @@ performed recursively; so this step makes sure that no other frames with
 @var{frame} as their ancestor will exist.  Then, unless @var{frame}
 specifies a tooltip, this function runs the hook
 @code{delete-frame-functions} (each function getting one argument,
-@var{frame}) before actually killing the frame.
+@var{frame}) before actually killing the frame.  After actually killing
+the frame and removing the frame from the frame list, @code{delete-frame}
+runs @code{after-delete-frame-functions}.
 
 Note that a frame cannot be deleted as long as its minibuffer serves as
 surrogate minibuffer for another frame (@pxref{Minibuffers and Frames}).
diff --git a/etc/NEWS b/etc/NEWS
index 7b14b9f8960..402dcb13c7f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -583,6 +583,12 @@ manual for more details.
 * Lisp Changes in Emacs 27.1
 
 +++
+** New hook `after-delete-frame-functions'.  Works like
+   `delete-frame-functions', but runs after the frame to be deleted
+   has been made dead and removed from the frame list, simplifying
+   some kinds of code.
+
++++
 ** New focus state inspection interface: `focus-in-hook' and
    `focus-out-hook' are marked obsolete.  Instead, attach to
    `after-focus-change-function' using `add-function' and inspect the
diff --git a/lisp/frame.el b/lisp/frame.el
index a0e7b35a138..38f785901e7 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -2416,40 +2416,33 @@ frame receives focus."
     (cancel-timer blink-cursor-idle-timer)
     (setq blink-cursor-idle-timer nil)))
 
-(defun blink-cursor--should-blink (&optional ignored-frame)
+(defun blink-cursor--should-blink ()
   "Determine whether we should be blinking.
-Returns whether we have any focused non-TTY frame.  IGNORED-FRAME
-is a frame to ignore during the scan, used when we want to ignore
-a frame about to be deleted."
+Returns whether we have any focused non-TTY frame."
   (and blink-cursor-mode
        (let ((frame-list (frame-list))
              (any-graphical-focused nil))
          (while frame-list
            (let ((frame (pop frame-list)))
-             (when (and (not (eq frame ignored-frame))
-                        (display-graphic-p frame)
-                        (frame-focus-state frame))
+             (when (and (display-graphic-p frame) (frame-focus-state frame))
                (setf any-graphical-focused t)
                (setf frame-list nil))))
          any-graphical-focused)))
 
-(defun blink-cursor-check (&optional ignored-frame)
+(defun blink-cursor-check ()
   "Check if cursor blinking shall be restarted.
 This is done when a frame gets focus.  Blink timers may be
 stopped by `blink-cursor-suspend'.  Internally calls
 `blink-cursor--should-blink' and returns its result."
-  (let ((should-blink (blink-cursor--should-blink ignored-frame)))
+  (let ((should-blink (blink-cursor--should-blink)))
     (when (and should-blink (not blink-cursor-idle-timer))
       (remove-hook 'post-command-hook 'blink-cursor-check)
       (blink-cursor--start-idle-timer))
     should-blink))
 
-(defun blink-cursor--rescan-frames (&optional ignored-frame)
-  "Called when the set of focused frames changes or when we
-delete a frame.  Re-check whether we want to enable blinking.
-IGNORED-FRAME is there so we ignore a frame about to be deleted
-when we're called under via `delete-frame-functions'."
-  (unless (blink-cursor-check ignored-frame)
+(defun blink-cursor--rescan-frames (&optional _ign)
+  "Called when the set of focused frames changes or when we delete a frame."
+  (unless (blink-cursor-check)
     (blink-cursor-suspend)))
 
 (define-minor-mode blink-cursor-mode
@@ -2474,11 +2467,11 @@ terminals, cursor blinking is controlled by the terminal."
   :group 'cursor
   :global t
   (blink-cursor-suspend)
-  (remove-hook 'delete-frame-functions #'blink-cursor--rescan-frames)
+  (remove-hook 'after-delete-frame-functions #'blink-cursor--rescan-frames)
   (remove-function after-focus-change-function #'blink-cursor--rescan-frames)
   (when blink-cursor-mode
     (add-function :after after-focus-change-function #'blink-cursor--rescan-frames)
-    (add-hook 'delete-frame-functions #'blink-cursor--rescan-frames)
+    (add-hook 'after-delete-frame-functions #'blink-cursor--rescan-frames)
     (blink-cursor--start-idle-timer)))
 
 
diff --git a/src/frame.c b/src/frame.c
index bf0269292d6..d477c1acc3f 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -2161,6 +2161,16 @@ delete_frame (Lisp_Object frame, Lisp_Object force)
   if (!is_tooltip_frame)
     update_mode_lines = 15;
 
+  /* Now run the post-deletion hooks.  */
+  if (NILP (Vrun_hooks) || is_tooltip_frame)
+    ;
+  else if (EQ (force, Qnoelisp))
+    pending_funcalls
+      = Fcons (list3 (Qrun_hook_with_args, Qafter_delete_frame_functions, frame),
+               pending_funcalls);
+  else
+      safe_call2 (Qrun_hook_with_args, Qafter_delete_frame_functions, frame);
+
   return Qnil;
 }
 
@@ -5897,6 +5907,14 @@ recursively).  */);
   Vdelete_frame_functions = Qnil;
   DEFSYM (Qdelete_frame_functions, "delete-frame-functions");
 
+  DEFVAR_LISP ("after-delete-frame-functions",
+               Vafter_delete_frame_functions,
+               doc: /* Functions run after deleting a frame.
+The functions are run with one arg, the frame that was deleted and
+which is now dead.  */);
+  Vafter_delete_frame_functions = Qnil;
+  DEFSYM (Qafter_delete_frame_functions, "after-delete-frame-functions");
+
   DEFVAR_LISP ("menu-bar-mode", Vmenu_bar_mode,
                doc: /* Non-nil if Menu-Bar mode is enabled.
 See the command `menu-bar-mode' for a description of this minor mode.