bug#12792: 24.2.50; shell-mode renders all its output in a yellow face

[Wolfgang Jenkner]

On Tue, Nov 06 2012, Dima Kogan wrote:

>> So, I'd say that the issue at hand is solved.  I'll just try to
>> rewrite the new ansi-color-apply-sequence in a less ugly way.
>
> Sounds good. Thanks a lot.

I hope the patch below is less ugly and also correct.  Perhaps you could
try it.

Note to the maintainers:  This fixes a regression for a feature not
actually present in previous versions of emacs ;-)


2012-11-08  Wolfgang Jenkner  <wjenkner@inode.at>

        * ansi-color.el (ansi-color-apply-sequence): Implement SGR codes
        39 and 49 (bug#12792).  Also, restore the behavior of revisions
        prior to 109621, where unimplemented codes are treated like code 0.


=== modified file 'lisp/ansi-color.el'
--- lisp/ansi-color.el  2012-09-25 04:13:02 +0000
+++ lisp/ansi-color.el  2012-11-09 00:19:00 +0000
@@ -534,34 +534,39 @@
 
 ESCAPE-SEQ is an escape sequence parsed by `ansi-color-parse-sequence'.
 
-If the new codes resulting from ESCAPE-SEQ start with 0, then the
-old codes are discarded and the remaining new codes are
-processed.  Otherwise, for each new code: if it is 21-25 or 27-29
-delete appropriate parameters from the list of codes; any other
-code that makes sense is added to the list of codes.  Finally,
-the so changed list of codes is returned."
+For each new code, the following happens: if it is 1-7, add it to
+the list of codes; if it is 21-25 or 27, delete appropriate
+parameters from the list of codes; if it is 30-37 resp. 39, the
+foreground color code is replaced or added resp. deleted; if it
+is 40-47 resp. 49, the background color code is replaced or added
+resp. deleted; any other code is discarded together with the old
+codes. Finally, the so changed list of codes is returned."
   (let ((new-codes (ansi-color-parse-sequence escape-sequence)))
     (while new-codes
-      (setq codes
-           (let ((new (pop new-codes)))
-             (cond ((zerop new)
-                    nil)
-                   ((or (<= new 20)
-                        (>= new 30))
-                    (if (memq new codes)
-                        codes
-                      (cons new codes)))
-                   ;; The standard says `21 doubly underlined' while
-                   ;; http://en.wikipedia.org/wiki/ANSI_escape_code claims
-                   ;; `21 Bright/Bold: off or Underline: Double'.
-                   ((/= new 26)
-                    (remq (- new 20)
-                          (cond ((= new 22)
-                                 (remq 1 codes))
-                                ((= new 25)
-                                 (remq 6 codes))
-                                (t codes))))
-                   (t codes)))))
+      (let* ((new (pop new-codes))
+            (q (/ new 10)))
+       (setq codes
+             (pcase q
+               (0 (unless (memq new '(0 8 9))
+                    (cons new (remq new codes))))
+               (2 (unless (memq new '(20 26 28 29))
+                    ;; The standard says `21 doubly underlined' while
+                    ;; http://en.wikipedia.org/wiki/ANSI_escape_code claims
+                    ;; `21 Bright/Bold: off or Underline: Double'.
+                    (remq (- new 20) (pcase new
+                                       (22 (remq 1 codes))
+                                       (25 (remq 6 codes))
+                                       (_ codes)))))
+               ((or 3 4) (let ((r (mod new 10)))
+                           (unless (= r 8)
+                             (let (beg)
+                               (while (and codes (/= q (/ (car codes) 10)))
+                                 (push (pop codes) beg))
+                               (setq codes (nconc (nreverse beg) (cdr codes)))
+                               (if (= r 9)
+                                   codes
+                                 (cons new codes))))))
+               (_ nil)))))
     codes))
 
 (defun ansi-color-make-color-map ()