Run buffer-local window change functions in their buffers now

The buffer-local-versions of 'window-buffer-change-functions',
'window-size-change-functions',
'window-selection-change-functions' and
'window-state-change-functions' are now run with the respective
buffer temporarily current.  Also, the local version of
'window-buffer-change-functions' is run for the buffer removed
from the window too.

* src/window.c (run_window_change_functions_locally)
(run_window_change_functions_globally): New functions replacing
'run_window_change_functions_1'.
(run_window_change_functions): Run the buffer local versions of
these hooks in their respective buffers.  Run
'window-buffer-change-functions' for the buffer removed from the
window too.
(Vwindow_buffer_change_functions, Vwindow_size_change_functions)
(Vwindow_selection_change_functions)
(Vwindow_state_change_functions): Mention that the buffer-local
versions are run with their buffer temporarily current.
* doc/lispref/windows.texi (Window Hooks): Mention that
buffer-local-versions of window change functions are run with
their buffer temporarily current.  Also say that
'window-buffer-change-functions' will be run for removed buffer
too.
* etc/NEWS: Advertise changes for the buffer-local versions of
window change functions.

1 files changed, 79 insertions, 50 deletions

diff --git a/src/window.c b/src/window.c
index 1ac004af5e0..dee17ae445a 100644
--- a/src/window.c
+++ b/src/window.c
@@ -3991,47 +3991,56 @@ window_change_record (void)
 }
 
 
-/**
- * run_window_change_functions_1:
- *
- * Run window change functions specified by SYMBOL with argument
- * WINDOW_OR_FRAME.  If BUFFER is nil, WINDOW_OR_FRAME specifies a
- * frame.  In this case, run the default value of SYMBOL.  Otherwise,
- * WINDOW_OR_FRAME denotes a window showing BUFFER.  In this case, run
- * the buffer local value of SYMBOL in BUFFER, if any.
+/** Run the buffer local value of SYMBOL in BUFFER, if any, with
+    argument WINDOW.  WINDOW must specify a live window that shows or
+    recently has shown BUFFER.
  */
 static void
-run_window_change_functions_1 (Lisp_Object symbol, Lisp_Object buffer,
-                               Lisp_Object window_or_frame)
+run_window_change_functions_locally (Lisp_Object symbol, Lisp_Object buffer,
+                                     Lisp_Object window)
 {
-  Lisp_Object funs = Qnil;
 
-  if (NILP (buffer))
-    funs = Fdefault_value (symbol);
-  else if (!NILP (Fassoc (symbol, BVAR (XBUFFER (buffer), local_var_alist),
-                          Qnil)))
-    /* Don't run global value buffer-locally.  */
-    funs = buffer_local_value (symbol, buffer);
-
-  while (CONSP (funs))
+  if (!NILP (assq_no_quit (symbol, BVAR (XBUFFER (buffer), local_var_alist))))
     {
-      if (!EQ (XCAR (funs), Qt)
-          && (NILP (buffer)
-              ? FRAME_LIVE_P (XFRAME (window_or_frame))
-              : WINDOW_LIVE_P (window_or_frame)))
+      Lisp_Object funs = buffer_local_value (symbol, buffer);
+
+      Fset_buffer (buffer);
+
+      while (CONSP (funs))
         {
-          /* Any function called here may change the state of any
-             frame.  Make sure to record changes for each live frame
-             in window_change_record later.  */
-          window_change_record_frames = true;
-          safe_calln (XCAR (funs), window_or_frame);
-        }
+          if (!EQ (XCAR (funs), Qt))
+            {
+              window_change_record_frames = true;
+              safe_calln (XCAR (funs), window);
+            }
 
-      funs = XCDR (funs);
+          funs = XCDR (funs);
+        }
     }
 }
 
 
+/** Run the default value of SYMBOL, if any, with argument FRAME.  */
+static void
+run_window_change_functions_globally (Lisp_Object symbol, Lisp_Object frame)
+{
+  Lisp_Object funs = Fdefault_value (symbol);
+
+  if (!NILP (funs))
+    {
+      while (CONSP (funs))
+        {
+          if (!EQ (XCAR (funs), Qt))
+            {
+              window_change_record_frames = true;
+              safe_calln (XCAR (funs), frame);
+            }
+
+          funs = XCDR (funs);
+        }
+    }
+}
+
 /**
  * run_window_change_functions:
  *
@@ -4149,6 +4158,7 @@ run_window_change_functions (void)
           Lisp_Object window = XCAR (windows);
           struct window *w = XWINDOW (window);
           Lisp_Object buffer = WINDOW_BUFFER (w);
+          specpdl_ref count1 = SPECPDL_INDEX ();
 
           /* Count this window even if it has been deleted while
              running a hook.  */
@@ -4188,12 +4198,22 @@ run_window_change_functions (void)
           frame_buffer_change = frame_buffer_change || window_buffer_change;
           frame_size_change = frame_size_change || window_size_change;
 
+          /* Prepare for running local hooks in their buffers.  */
+          record_unwind_current_buffer ();
+
           if (window_buffer_change)
-            run_window_change_functions_1
-              (Qwindow_buffer_change_functions, buffer, window);
+            {
+              if (BUFFERP (w->old_buffer)
+                  && BUFFER_LIVE_P (XBUFFER (w->old_buffer)))
+                run_window_change_functions_locally
+                  (Qwindow_buffer_change_functions, w->old_buffer, window);
+
+              run_window_change_functions_locally
+                (Qwindow_buffer_change_functions, buffer, window);
+            }
 
           if (window_size_change && WINDOW_LIVE_P (window))
-            run_window_change_functions_1
+            run_window_change_functions_locally
               (Qwindow_size_change_functions, buffer, window);
 
           /* This window's selection has changed when it was
@@ -4206,7 +4226,7 @@ run_window_change_functions (void)
                    && (EQ (window, FRAME_OLD_SELECTED_WINDOW (f))
                        || EQ (window, FRAME_SELECTED_WINDOW (f)))))
               && WINDOW_LIVE_P (window))
-            run_window_change_functions_1
+            run_window_change_functions_locally
               (Qwindow_selection_change_functions, buffer, window);
 
           /* This window's state has changed when its buffer or size
@@ -4221,8 +4241,11 @@ run_window_change_functions (void)
                        && (EQ (window, FRAME_OLD_SELECTED_WINDOW (f))
                            || EQ (window, FRAME_SELECTED_WINDOW (f))))))
               && WINDOW_LIVE_P (window))
-            run_window_change_functions_1
+            run_window_change_functions_locally
               (Qwindow_state_change_functions, buffer, window);
+
+          /* Restore current buffer for running the global hooks.  */
+          unbind_to (count1, Qnil);
         }
 
       /* When the number of windows on a frame has decreased, at least
@@ -4236,21 +4259,21 @@ run_window_change_functions (void)
       /* A frame changed buffers when one of its windows has changed
          its buffer or at least one window was deleted.  */
       if ((frame_buffer_change || window_deleted) && FRAME_LIVE_P (f))
-        run_window_change_functions_1
-          (Qwindow_buffer_change_functions, Qnil, frame);
+        run_window_change_functions_globally
+          (Qwindow_buffer_change_functions, frame);
 
       /* A size change occurred when at least one of the frame's
          windows has changed size.  */
       if (frame_size_change && FRAME_LIVE_P (f))
-        run_window_change_functions_1
-          (Qwindow_size_change_functions, Qnil, frame);
+        run_window_change_functions_globally
+          (Qwindow_size_change_functions, frame);
 
       /* A frame has changed its window selection when its selected
          window has changed or when it was (de-)selected.  */
       if ((frame_selected_change || frame_selected_window_change)
           && FRAME_LIVE_P (f))
-        run_window_change_functions_1
-          (Qwindow_selection_change_functions, Qnil, frame);
+        run_window_change_functions_globally
+          (Qwindow_selection_change_functions, frame);
 
 #if defined HAVE_TEXT_CONVERSION
 
@@ -4272,8 +4295,8 @@ run_window_change_functions (void)
            || frame_size_change || frame_window_state_change)
           && FRAME_LIVE_P (f))
         {
-          run_window_change_functions_1
-            (Qwindow_state_change_functions, Qnil, frame);
+          run_window_change_functions_globally
+            (Qwindow_state_change_functions, frame);
           /* Make sure to run 'window-state-change-hook' later.  */
           run_window_state_change_hook = true;
           /*  Make sure to record changes for each live frame in
@@ -8959,8 +8982,12 @@ The value should be a list of functions that take one argument.
 
 Functions specified buffer-locally are called for each window showing
 the corresponding buffer if and only if that window has been added or
-changed its buffer since the last redisplay.  In this case the window
-is passed as argument.
+changed its buffer since the last redisplay.  This means that functions
+may be run twice for such a window: Once for the buffer shown in the
+window at the time of the last redisplay (provided that buffer is still
+live) and once for the buffer currently shown in the window.  In either
+case the window is passed as argument and the respective buffer is made
+temporarily current.
 
 Functions specified by the default value are called for each frame if
 at least one window on that frame has been added, deleted or changed
@@ -8975,7 +9002,8 @@ The value should be a list of functions that take one argument.
 Functions specified buffer-locally are called for each window showing
 the corresponding buffer if and only if that window has been added or
 changed its buffer or its total or body size since the last redisplay.
-In this case the window is passed as argument.
+In this case the window is passed as argument and the respective buffer
+is temporarily made current.
 
 Functions specified by the default value are called for each frame if
 at least one window on that frame has been added or changed its buffer
@@ -8991,9 +9019,9 @@ can add `frame-hide-title-bar-when-maximized' to this variable.  */);
 The value should be a list of functions that take one argument.
 
 Functions specified buffer-locally are called for each window showing
-the corresponding buffer if and only if that window has been selected
-or deselected since the last redisplay.  In this case the window is
-passed as argument.
+the corresponding buffer if and only if that window has been selected or
+deselected since the last redisplay.  In this case the window is passed
+as argument and the respective buffer is temporarily made current.
 
 Functions specified by the default value are called for each frame if
 the frame's selected window has changed since the last redisplay.  In
@@ -9007,7 +9035,8 @@ The value should be a list of functions that take one argument.
 Functions specified buffer-locally are called for each window showing
 the corresponding buffer if and only if that window has been added,
 resized, changed its buffer or has been (de-)selected since the last
-redisplay.  In this case the window is passed as argument.
+redisplay.  In this case the window is passed as argument and the
+respective buffer is temporarily made current.
 
 Functions specified by the default value are called for each frame if
 at least one window on that frame has been added, deleted, changed its