Use text properties for color escape highlighting in Shell mode.

* ansi-color.el: Don't set comint-output-filter-functions; it is
now in the initial value defined in comint.el.
(ansi-color-apply-face-function): New variable.
(ansi-color-apply-on-region): Use it.
(ansi-color-apply-overlay-face): New function.

* comint.el: Require ansi-color.
(comint-output-filter-functions): Add ansi-color-process-output.

* shell.el (shell): No need to require ansi-color.
(shell-mode): Use ansi-color-apply-face-function to highlight
color escapes using font-lock-face property.

Fixes: debbugs:10835

1 files changed, 2 insertions, 1 deletions

diff --git a/lisp/comint.el b/lisp/comint.el
index 975291471df..4c2229f2f83 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -103,6 +103,7 @@
 
 (eval-when-compile (require 'cl))
 (require 'ring)
+(require 'ansi-color)
 
 ;; Buffer Local Variables:
 ;;============================================================================
@@ -385,7 +386,7 @@ history list.  Default is to save anything that isn't all whitespace.")
 These functions get one argument, a string containing the text to send.")
 
 ;;;###autoload
-(defvar comint-output-filter-functions '(comint-postoutput-scroll-to-bottom comint-watch-for-password-prompt)
+(defvar comint-output-filter-functions '(ansi-color-process-output comint-postoutput-scroll-to-bottom comint-watch-for-password-prompt)
   "Functions to call after output is inserted into the buffer.
 One possible function is `comint-postoutput-scroll-to-bottom'.
 These functions get one argument, a string containing the text as originally