From f3e82ab6d29dc0b673704dafd7e8c8c636bf0407 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <address@hidden>
Date: Sat, 21 Nov 2015 17:02:42 -0500
Subject: [PATCH 3/3] Ensure redisplay using variable watchers

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

* lisp/frame.el: Replace redisplay--variables with add-variable-watcher
  calls.
* src/data.c (set_internal): Remove maybe_set_redisplay call.
* src/xdisp.c (Fset_redisplay): Rename from maybe_set_redisplay, set the
  redisplay flag unconditionally.
---
 lisp/frame.el |  3 +--
 src/data.c    |  2 --
 src/window.h  |  1 -
 src/xdisp.c   | 19 ++++++++-----------
 4 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/lisp/frame.el b/lisp/frame.el
index f024065..95c514f 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))
       '(line-spacing
         overline-margin
         line-prefix
diff --git a/src/data.c b/src/data.c
index 7c6fc2c..a411cf5 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1260,8 +1260,6 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
   default: ;
   }
 
-  maybe_set_redisplay (symbol);
-
  start:
   switch (sym->redirect)
     {
diff --git a/src/window.h b/src/window.h
index 135f5de..eaff57e 100644
--- a/src/window.h
+++ b/src/window.h
@@ -1056,7 +1056,6 @@ 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);
 /* 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..705f352 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -620,15 +620,14 @@ bset_update_mode_line (struct buffer *b)
   b->text->redisplay = true;
 }
 
-void
-maybe_set_redisplay (Lisp_Object symbol)
+DEFUN ("set-redisplay", Fset_redisplay, Sset_redisplay,
+       0, MANY, 0,
+       doc: /* Cause a full redisplay to happen.
+       usage: () */)
+  (ptrdiff_t nargs, Lisp_Object* rest)
 {
-  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
@@ -31478,9 +31477,7 @@ or t (meaning all windows).  */);
 	       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;
+  defsubr (&Sset_redisplay);
 }
 
 
-- 
2.6.2