Re: C mode to hexl mode and back loses color highlighting

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> In the current CVS trunk:
>> 
>> * run emacs -Q
>> * visit a C source file - notice the comments are red
>> * M-x hexl-mode RET - switch to hexl mode
>> * C-c C-c - switch back to C mode
>> * notice the comments are no longer red

> This is not specific to the trunk, it happens with EMACS_22_BASE too.

I've installed the following fix on the 22 branch.


        Stefan


2008-02-12  Stefan Monnier  <monnier@iro.umontreal.ca>

	* font-lock.el (font-lock-set-defaults): Unset previously set variables
	when needed.

Index: lisp/font-lock.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/font-lock.el,v
retrieving revision 1.317.2.5
diff -u -r1.317.2.5 font-lock.el
--- lisp/font-lock.el	7 Jan 2008 02:44:46 -0000	1.317.2.5
+++ lisp/font-lock.el	12 Feb 2008 16:48:46 -0000
@@ -1777,13 +1777,16 @@
 	    (cdr-safe (assq major-mode font-lock-removed-keywords-alist))))
       (set (make-local-variable 'font-lock-defaults) defaults)
       ;; Syntactic fontification?
-      (when (nth 1 defaults)
-	(set (make-local-variable 'font-lock-keywords-only) t))
+      (if (nth 1 defaults)
+          (set (make-local-variable 'font-lock-keywords-only) t)
+        (kill-local-variable 'font-lock-keywords-only))
       ;; Case fold during regexp fontification?
-      (when (nth 2 defaults)
-	(set (make-local-variable 'font-lock-keywords-case-fold-search) t))
+      (if (nth 2 defaults)
+          (set (make-local-variable 'font-lock-keywords-case-fold-search) t)
+        (kill-local-variable 'font-lock-keywords-case-fold-search))
       ;; Syntax table for regexp and syntactic fontification?
-      (when (nth 3 defaults)
+      (if (null (nth 3 defaults))
+          (kill-local-variable 'font-lock-syntax-table)
 	(set (make-local-variable 'font-lock-syntax-table)
 	     (copy-syntax-table (syntax-table)))
 	(dolist (selem (nth 3 defaults))
@@ -1794,9 +1797,10 @@
 			    (mapcar 'identity (car selem))))
 	      (modify-syntax-entry char syntax font-lock-syntax-table)))))
       ;; Syntax function for syntactic fontification?
-      (when (nth 4 defaults)
+      (if (nth 4 defaults)
 	(set (make-local-variable 'font-lock-beginning-of-syntax-function)
-	     (nth 4 defaults)))
+               (nth 4 defaults))
+        (kill-local-variable 'font-lock-beginning-of-syntax-function))
       ;; Variable alist?
       (dolist (x (nthcdr 5 defaults))
 	(set (make-local-variable (car x)) (cdr x)))