(grep-process-setup) [windows-nt msdos]: Use "--color=always".

2 files changed, 10 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 41e7f1753ba..5bd2e9d3835 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2009-02-28  Eli Zaretskii  <eliz@gnu.org>
+
+        * progmodes/grep.el (grep-process-setup) [windows-nt msdos]: Use
+        "--color=always".
+
 2009-02-28  Glenn Morris  <rgm@gnu.org>
 
         * mail/rmailout.el (rmail-output-as-seen): Add autoload cookie.
diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index b4bcc5c88a5..fa73f7f777a 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -407,7 +407,11 @@ Set up `compilation-exit-message-function' and run `grep-setup-hook'."
     ;; `--color=auto' emits escape sequences on a tty rather than on a pipe,
     ;; thus allowing to use multiple grep filters on the command line
     ;; and to output escape sequences only on the final grep output
-    (setenv "GREP_OPTIONS" (concat (getenv "GREP_OPTIONS") " --color=auto"))
+    (setenv "GREP_OPTIONS"
+            (concat (getenv "GREP_OPTIONS")
+                    ;; Windows and DOS pipes fail `isatty' detection in Grep.
+                    " --color=" (if (memq system-type '(windows-nt ms-dos))
+                                    "always" "auto")))
     ;; GREP_COLOR is used in GNU grep 2.5.1, but deprecated in later versions
     (setenv "GREP_COLOR" "01;31")
     ;; GREP_COLORS is used in GNU grep 2.5.2 and later versions