Handle removal of selected tty child frame

* src/dispextern.h (root_frame):
* src/frame.h (root_frame): Move declaration from dispextern.h
to frame.h.
(SET_FRAME_VISIBLE): Whend making the selected tty child frame
invisible, use mru_rooted_frame to find a frame to switch to.
* src/dispnew.c (root_frame): Move root_frame to frame.c.
* src/frame.c (do_switch_frame): On ttys don't change the
top frame when switching from a child frame to another frame
with the same root.
(root_frame): Move here from dispnew.c.
(Fframe_root_frame): New Lisp function.
(delete_frame): Whend deleting the selected tty child frame use,
mru_rooted_frame to find a frame to switch to.
* src/window.c (mru_rooted_frame): New function.
* src/window.h (mru_rooted_frame): Declare it.
* doc/lispref/frames.texi (Child Frames): Describe new function
'frame-root-frame'.

6 files changed, 141 insertions, 75 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index e3e621e7318..1d90022a9bc 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3949,7 +3949,6 @@ extern void gui_redo_mouse_highlight (Display_Info *);
 
 #endif /* HAVE_WINDOW_SYSTEM */
 
-struct frame *root_frame (struct frame *f);
 Lisp_Object frames_in_reverse_z_order (struct frame *f, bool visible);
 bool is_tty_frame (struct frame *f);
 bool is_tty_child_frame (struct frame *f);
diff --git a/src/dispnew.c b/src/dispnew.c
index 5bc6958622d..cb57edcec0f 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3334,18 +3334,6 @@ frame_rect_abs (struct frame *f)
 
 #endif /* !HAVE_ANDROID */
 
-/* Return the root frame of frame F.  Follow the parent_frame chain
-   until we reach a frame that has no parent.  That is the root frame.
-   Note that the root of a root frame is itself. */
-
-struct frame *
-root_frame (struct frame *f)
-{
-  while (FRAME_PARENT_FRAME (f))
-    f = FRAME_PARENT_FRAME (f);
-  return f;
-}
-
 int
 max_child_z_order (struct frame *parent)
 {
diff --git a/src/frame.c b/src/frame.c
index 212331c0b3a..4559bc41ab8 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -1775,7 +1775,7 @@ do_switch_frame (Lisp_Object frame, int track, int for_deletion, Lisp_Object nor
 
       /* Don't mark the frame garbaged if we are switching to the frame
          that is already the top frame of that TTY.  */
-      if (!EQ (frame, top_frame))
+      if (!EQ (frame, top_frame) && root_frame (f) != XFRAME (top_frame))
         {
           struct frame *new_root = root_frame (f);
           SET_FRAME_VISIBLE (new_root, true);
@@ -2021,6 +2021,39 @@ frame.  */)
   return frame_ancestor_p (af, df) ? Qt : Qnil;
 }
 
+
+/* Return the root frame of frame F.  Follow the parent_frame chain
+   until we reach a frame that has no parent.  That is the root frame.
+   Note that the root of a root frame is itself. */
+
+struct frame *
+root_frame (struct frame *f)
+{
+  while (FRAME_PARENT_FRAME (f))
+    f = FRAME_PARENT_FRAME (f);
+  return f;
+}
+
+
+DEFUN ("frame-root-frame", Fframe_root_frame, Sframe_root_frame,
+       0, 1, 0,
+       doc: /* Return root frame of specified FRAME.
+FRAME must be a live frame and defaults to the selected one.  The root
+frame of FRAME is the frame obtained by following the chain of parent
+frames starting with FRAME until a frame is reached that has no parent.
+If FRAME has no parent, its root frame is FRAME.  */)
+     (Lisp_Object frame)
+{
+  struct frame *f = decode_live_frame (frame);
+  struct frame *r = root_frame (f);
+  Lisp_Object root;
+
+  XSETFRAME (root, r);
+
+  return root;
+}
+
+
 /* Return CANDIDATE if it can be used as 'other-than-FRAME' frame on the
    same tty (for tty frames) or among frames which uses FRAME's keyboard.
    If MINIBUF is nil, do not consider minibuffer-only candidate.
@@ -2433,61 +2466,68 @@ delete_frame (Lisp_Object frame, Lisp_Object force)
   /* Don't let the frame remain selected.  */
   if (f == sf)
     {
-      Lisp_Object tail;
-      Lisp_Object frame1 UNINIT;  /* This line works around GCC bug 85563.  */
-      eassume (CONSP (Vframe_list));
-
-      /* Look for another visible frame on the same terminal.
-         Do not call next_frame here because it may loop forever.
-         See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=15025.  */
-      FOR_EACH_FRAME (tail, frame1)
+      if (is_tty_child_frame (f))
+        /* If F is a child frame on a tty and is the selected frame, try
+           to re-select the frame that was selected before F.  */
+        do_switch_frame (mru_rooted_frame (f), 0, 1, Qnil);
+      else
         {
-          struct frame *f1 = XFRAME (frame1);
-
-          if (!EQ (frame, frame1)
-              && !FRAME_TOOLTIP_P (f1)
-              && FRAME_TERMINAL (f) == FRAME_TERMINAL (f1)
-              && FRAME_VISIBLE_P (f1))
-            break;
-        }
+          Lisp_Object tail;
+          Lisp_Object frame1 UNINIT;  /* This line works around GCC bug 85563.  */
+          eassume (CONSP (Vframe_list));
 
-      /* If there is none, find *some* other frame.  */
-      if (NILP (frame1) || EQ (frame1, frame))
-        {
+          /* Look for another visible frame on the same terminal.
+             Do not call next_frame here because it may loop forever.
+             See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=15025.  */
           FOR_EACH_FRAME (tail, frame1)
             {
               struct frame *f1 = XFRAME (frame1);
 
               if (!EQ (frame, frame1)
-                  && FRAME_LIVE_P (f1)
-                  && !FRAME_TOOLTIP_P (f1))
+                  && !FRAME_TOOLTIP_P (f1)
+                  && FRAME_TERMINAL (f) == FRAME_TERMINAL (f1)
+                  && FRAME_VISIBLE_P (f1))
+                break;
+            }
+
+          /* If there is none, find *some* other frame.  */
+          if (NILP (frame1) || EQ (frame1, frame))
+            {
+              FOR_EACH_FRAME (tail, frame1)
                 {
-                  if (FRAME_TERMCAP_P (f1) || FRAME_MSDOS_P (f1))
-                    {
-                      Lisp_Object top_frame = FRAME_TTY (f1)->top_frame;
+                  struct frame *f1 = XFRAME (frame1);
 
-                      if (!EQ (top_frame, frame))
-                        frame1 = top_frame;
+                  if (!EQ (frame, frame1)
+                      && FRAME_LIVE_P (f1)
+                      && !FRAME_TOOLTIP_P (f1))
+                    {
+                      if (FRAME_TERMCAP_P (f1) || FRAME_MSDOS_P (f1))
+                        {
+                          Lisp_Object top_frame = FRAME_TTY (f1)->top_frame;
+
+                          if (!EQ (top_frame, frame))
+                            frame1 = top_frame;
+                        }
+                      break;
                     }
-                  break;
                 }
             }
-        }
 #ifdef NS_IMPL_COCOA
-      else
-        {
-          /* Under NS, there is no system mechanism for choosing a new
-             window to get focus -- it is left to application code.
-             So the portion of THIS application interfacing with NS
-             needs to make the frame we switch to the key window.  */
-          struct frame *f1 = XFRAME (frame1);
-          if (FRAME_NS_P (f1))
-            ns_make_frame_key_window (f1);
-        }
+          else
+            {
+              /* Under NS, there is no system mechanism for choosing a new
+                 window to get focus -- it is left to application code.
+                 So the portion of THIS application interfacing with NS
+                 needs to make the frame we switch to the key window.  */
+              struct frame *f1 = XFRAME (frame1);
+              if (FRAME_NS_P (f1))
+                ns_make_frame_key_window (f1);
+            }
 #endif
 
-      do_switch_frame (frame1, 0, 1, Qnil);
-      sf = SELECTED_FRAME ();
+          do_switch_frame (frame1, 0, 1, Qnil);
+          sf = SELECTED_FRAME ();
+        }
     }
   else
     /* Ensure any minibuffers on FRAME are moved onto the selected
@@ -2583,11 +2623,11 @@ delete_frame (Lisp_Object frame, Lisp_Object force)
     f->terminal = 0;             /* Now the frame is dead.  */
     unblock_input ();
 
-  /* Clear markers and overlays set by F on behalf of an input
-     method.  */
+    /* Clear markers and overlays set by F on behalf of an input
+       method.  */
 #ifdef HAVE_TEXT_CONVERSION
-  if (FRAME_WINDOW_P (f))
-    reset_frame_state (f);
+    if (FRAME_WINDOW_P (f))
+      reset_frame_state (f);
 #endif
 
     /* If needed, delete the terminal that this frame was on.
@@ -7146,6 +7186,7 @@ iconify the top level frame instead.  */);
   defsubr (&Sframe_list);
   defsubr (&Sframe_parent);
   defsubr (&Sframe_ancestor_p);
+  defsubr (&Sframe_root_frame);
   defsubr (&Snext_frame);
   defsubr (&Sprevious_frame);
   defsubr (&Slast_nonminibuf_frame);
diff --git a/src/frame.h b/src/frame.h
index bff610472c0..fea8baa7332 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -1428,23 +1428,6 @@ FRAME_PARENT_FRAME (struct frame *f)
 /* False means there are no visible garbaged frames.  */
 extern bool frame_garbaged;
 
-/* Set visibility of frame F.
-   We call redisplay_other_windows to make sure the frame gets redisplayed
-   if some changes were applied to it while it wasn't visible (and hence
-   wasn't redisplayed).  */
-INLINE void
-SET_FRAME_VISIBLE (struct frame *f, bool v)
-{
-  if (v)
-    {
-      if (v == 1 && f->visible != 1)
-        redisplay_other_windows ();
-      if (FRAME_GARBAGED_P (f))
-        frame_garbaged = true;
-    }
-  f->visible = v;
-}
-
 /* Set iconified status of frame F.  */
 INLINE void
 SET_FRAME_ICONIFIED (struct frame *f, int i)
@@ -1518,6 +1501,7 @@ void check_tty (struct frame *f);
 struct frame *decode_tty_frame (Lisp_Object frame);
 extern void frame_make_pointer_invisible (struct frame *);
 extern void frame_make_pointer_visible (struct frame *);
+extern struct frame *root_frame (struct frame *f);
 extern Lisp_Object delete_frame (Lisp_Object, Lisp_Object);
 extern bool frame_inhibit_resize (struct frame *, bool, Lisp_Object);
 extern void adjust_frame_size (struct frame *, int, int, int, bool,
@@ -1541,6 +1525,27 @@ extern Lisp_Object Vframe_list;
       ? XFRAME (selected_frame)                         \
       : (emacs_abort (), (struct frame *) 0))
 
+/* Set visibility of frame F.
+   We call redisplay_other_windows to make sure the frame gets redisplayed
+   if some changes were applied to it while it wasn't visible (and hence
+   wasn't redisplayed).  */
+INLINE void
+SET_FRAME_VISIBLE (struct frame *f, bool v)
+{
+  if (v)
+    {
+      if (v == 1 && f->visible != 1)
+        redisplay_other_windows ();
+      if (FRAME_GARBAGED_P (f))
+        frame_garbaged = true;
+    }
+  /* If F is a child frame on a tty and is the selected frame, try to
+     re-select the frame that was selected before F.  */
+  else if (is_tty_child_frame (f) && f == XFRAME (selected_frame))
+    do_switch_frame (mru_rooted_frame (f), 0, 0, Qnil);
+
+  f->visible = v;
+}
 
 /***********************************************************************
                         Display-related Macros
diff --git a/src/window.c b/src/window.c
index ff58eb12ee0..d7e6cd00c99 100644
--- a/src/window.c
+++ b/src/window.c
@@ -3097,6 +3097,38 @@ be listed first but no error is signaled.  */)
 {
   return window_list_1 (window, minibuf, all_frames);
 }
+
+/** Return most recently selected frame that has the same root as a
+    given frame.  It's defined here because the static window_list_1 is
+    here too but in fact it's only needed in the frame code.  */
+Lisp_Object
+mru_rooted_frame (struct frame *f)
+{
+  Lisp_Object windows = window_list_1 (FRAME_SELECTED_WINDOW (f), Qnil, Qt);
+  struct frame *r = root_frame (f);
+  struct window *b = NULL;
+
+  for (; CONSP (windows); windows = XCDR (windows))
+    {
+      struct window *w = XWINDOW (XCAR (windows));
+      struct frame *wf = WINDOW_XFRAME (w);
+
+      if (wf != f && root_frame (wf) == r && FRAME_VISIBLE_P (wf)
+          && (!b || w->use_time > b->use_time))
+        b = w;
+    }
+
+  if (b)
+    return WINDOW_FRAME (b);
+  else
+    {
+      Lisp_Object root;
+
+      XSETFRAME (root, r);
+
+      return root;
+    }
+}
 
 /* Look at all windows, performing an operation specified by TYPE
    with argument OBJ.
diff --git a/src/window.h b/src/window.h
index 39356f80df7..a48c370b198 100644
--- a/src/window.h
+++ b/src/window.h
@@ -1227,6 +1227,7 @@ extern void wset_buffer (struct window *, Lisp_Object);
 extern bool window_outdated (struct window *);
 extern ptrdiff_t window_point (struct window *w);
 extern void window_discard_buffer_from_dead_windows (Lisp_Object);
+extern Lisp_Object mru_rooted_frame (struct frame *);
 extern void init_window_once (void);
 extern void init_window (void);
 extern void syms_of_window (void);