Fix unexpected jumps of window-point in 'set-window-configuration' (Bug#31695)

* src/window.c (Fset_window_configuration): Prevent that the
fix for Bug#12208 affects restoration of window points when
using separate minibuffer frames (Bug#31695).

diff --git a/src/window.c b/src/window.c
index e6d0280d9b0024a0af18f0e64dd781692092e5a3..409b01f302e7b5129e0416241dad1bc0a5cf90ee 100644 (file)
--- a/src/window.c
+++ b/src/window.c
@@ -6610,10 +6610,10 @@ the return value is nil.  Otherwise the value is t.  */)
                               make_number (old_point),
                               XWINDOW (data->current_window)->contents);
 
-      /* In the following call to `select-window', prevent "swapping out
+      /* In the following call to select_window, prevent "swapping out
         point" in the old selected window using the buffer that has
-        been restored into it.  We already swapped out that point from
-        that window's old buffer.
+        been restored into it.  We already swapped out that point
+        from that window's old buffer.
 
         Do not record the buffer here.  We do that in a separate call
         to select_window below.  See also Bug#16207.  */
@@ -6656,10 +6656,10 @@ the return value is nil.  Otherwise the value is t.  */)
       if (WINDOW_LIVE_P (data->current_window))
        select_window (data->current_window, Qnil, false);
 
-      /* Fselect_window will have made f the selected frame, so we
-        reselect the proper frame here.  Fhandle_switch_frame will change the
-        selected window too, but that doesn't make the call to
-        Fselect_window above totally superfluous; it still sets f's
+      /* select_window will have made f the selected frame, so we
+        reselect the proper frame here.  do_switch_frame will change
+        the selected window too, but that doesn't make the call to
+        select_window above totally superfluous; it still sets f's
         selected window.  */
       if (FRAME_LIVE_P (XFRAME (data->selected_frame)))
        do_switch_frame (data->selected_frame, 0, 0, Qnil);
@@ -6696,8 +6696,21 @@ the return value is nil.  Otherwise the value is t.  */)
     {
       Fset_buffer (new_current_buffer);
       /* If the new current buffer doesn't appear in the selected
-        window, go to its old point (see bug#12208).  */
-      if (!EQ (XWINDOW (data->current_window)->contents, new_current_buffer))
+        window, go to its old point (Bug#12208).
+
+        The original fix used data->current_window below which caused
+        false positives (compare Bug#31695) when data->current_window
+        is not on data->selected_frame.  This happens, for example,
+        when read_minibuf restores the configuration of a stand-alone
+        minibuffer frame: After switching to the previously selected
+        "normal" frame, point of that frame's selected window jumped
+        unexpectedly because new_current_buffer is usually *not*
+        shown in data->current_window - the minibuffer frame's
+        selected window.  Using selected_window instead fixes this
+        because do_switch_frame has set up selected_window already to
+        the "normal" frame's selected window and that window *does*
+        show new_current_buffer.  */
+      if (!EQ (XWINDOW (selected_window)->contents, new_current_buffer))
        Fgoto_char (make_number (old_point));
     }