From 06df77af4794cc94e534aa695da06ff064e47e76 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <address@hidden>
Date: Sat, 21 Nov 2015 17:02:42 -0500
Subject: [PATCH v2 3/3] Ensure redisplay using variable watcher

Instead of looking up the variable name in redisplay--variables when
setting.

* lisp/frame.el: Replace redisplay--variables with add-variable-watcher
  calls.
* src/xdisp.c (set_redisplay): Rename from maybe_set_redisplay, set the
  redisplay flag unconditionally.
* src/data.c (watcher_table): Add set_resdisplay.
  (syms_of_data): New var set-redisplay-internal-watcher-number.
  (set_internal): Remove maybe_set_redisplay call.
---
 lisp/emacs-lisp/debug.el |  2 +-
 lisp/frame.el            |  3 +--
 src/data.c               | 11 +++++++++--
 src/window.h             |  2 +-
 src/xdisp.c              | 15 ++++-----------
 5 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/lisp/emacs-lisp/debug.el b/lisp/emacs-lisp/debug.el
index 68be115..e20654e 100644
--- a/lisp/emacs-lisp/debug.el
+++ b/lisp/emacs-lisp/debug.el
@@ -864,7 +864,7 @@ (defun debugger-list-functions ()
           (princ "Note: if you have redefined a function, then it may no longer\n")
           (princ "be set to debug on entry, even if it is in the list."))))))
 
-(defun debug--implement-debug-watch (op where symbol newval)
+(defun debug--implement-debug-watch (symbol newval op where)
   "Conditionally call the debugger.
 This function is called when SYMBOL's value is modified."
   (if (or inhibit-debug-on-entry debugger-jumping-flag)
diff --git a/lisp/frame.el b/lisp/frame.el
index f024065..79c954a 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -2232,9 +2232,8 @@ (make-obsolete-variable
  'window-system-version "it does not give useful information." "24.3")
 
 ;; Variables which should trigger redisplay of the current buffer.
-(setq redisplay--variables (make-hash-table :test 'eq :size 10))
 (mapc (lambda (var)
-        (puthash var 1 redisplay--variables))
+        (add-variable-watcher var set-redisplay-internal-watcher-number))
       '(line-spacing
         overline-margin
         line-prefix
diff --git a/src/data.c b/src/data.c
index 1576280..a1ceeec 100644
--- a/src/data.c
+++ b/src/data.c
@@ -33,6 +33,7 @@
 #include "keyboard.h"
 #include "frame.h"
 #include "keymap.h"
+#include "window.h"
 
 static void notify_variable_watchers (Lisp_Object symbol,
                                       Lisp_Object newval,
@@ -1262,8 +1263,6 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
     default: ;
     }
 
-  maybe_set_redisplay (symbol);
-
  start:
   switch (sym->redirect)
     {
@@ -1435,9 +1434,11 @@ DEFUN ("remove-variable-watcher", Fremove_variable_watcher, Sremove_variable_wat
 typedef void (*WATCHER_FUNCTION) (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object);
 static const WATCHER_FUNCTION watcher_table[] =
   {
+    &set_redisplay
   };
 enum
   {
+    WATCHER_NUMBER_SET_REDISPLAY
   };
 
 static void
@@ -3825,4 +3826,10 @@ syms_of_data (void)
   DEFSYM (Qset_default, "Qset_default");
   defsubr (&Sadd_variable_watcher);
   defsubr (&Sremove_variable_watcher);
+
+  DEFVAR_INT ("set-redisplay-internal-watcher-number",
+              Vset_redisplay_internal_watcher_number,
+              doc: /* Internal watch function constant.  */);
+  Vset_redisplay_internal_watcher_number = WATCHER_NUMBER_SET_REDISPLAY;
+  make_symbol_constant (intern_c_string ("set-redisplay-internal-watcher-number"));
 }
diff --git a/src/window.h b/src/window.h
index 135f5de..ebf5ef7 100644
--- a/src/window.h
+++ b/src/window.h
@@ -1056,7 +1056,7 @@ extern void wset_redisplay (struct window *w);
 extern void fset_redisplay (struct frame *f);
 extern void bset_redisplay (struct buffer *b);
 extern void bset_update_mode_line (struct buffer *b);
-extern void maybe_set_redisplay (Lisp_Object);
+extern void set_redisplay (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object);
 /* Call this to tell redisplay to look for other windows than selected-window
    that need to be redisplayed.  Calling one of the *set_redisplay functions
    above already does it, so it's only needed in unusual cases.  */
diff --git a/src/xdisp.c b/src/xdisp.c
index 30dfac5..5c5c4d2 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -621,14 +621,11 @@ bset_update_mode_line (struct buffer *b)
 }
 
 void
-maybe_set_redisplay (Lisp_Object symbol)
+set_redisplay (Lisp_Object symbol, Lisp_Object newval,
+               Lisp_Object op, Lisp_Object where)
 {
-  if (HASH_TABLE_P (Vredisplay__variables)
-      && hash_lookup (XHASH_TABLE (Vredisplay__variables), symbol, NULL) >= 0)
-    {
-      bset_update_mode_line (current_buffer);
-      current_buffer->prevent_redisplay_optimizations_p = true;
-    }
+  bset_update_mode_line (current_buffer);
+  current_buffer->prevent_redisplay_optimizations_p = true;
 }
 
 #ifdef GLYPH_DEBUG
@@ -31477,10 +31474,6 @@ or t (meaning all windows).  */);
   DEFVAR_LISP ("redisplay--mode-lines-cause", Vredisplay__mode_lines_cause,
 	       doc: /*  */);
   Vredisplay__mode_lines_cause = Fmake_hash_table (0, NULL);
-
-  DEFVAR_LISP ("redisplay--variables", Vredisplay__variables,
-     doc: /* A hash-table of variables changing which triggers a thorough redisplay.  */);
-  Vredisplay__variables = Qnil;
 }
 
 
-- 
2.6.2