(grep-compute-defaults): Don't set

grep-command/grep-find-command when it is already non-nil.
(grep-command): Make it a user option.
(grep-find-command): Likewise.

lisp/progmodes/compile.el

 ;;; compile.el --- run compiler as inferior of Emacs, parse error messages
 
-;; Copyright (C) 1985, 86, 87, 93, 94, 95, 96, 97, 98, 1999 Free Software Foundation, Inc.
+;; Copyright (C) 1985, 86, 87, 93, 94, 95, 96, 97, 98, 1999, 2001 Free Software Foundation, Inc.
 
 ;; Author: Roland McGrath <roland@gnu.org>
 ;; Maintainer: FSF
@@ -65,6 +65,26 @@ will be parsed and highlighted as soon as you try to move to them."
 		 (integer :tag "First N lines"))
   :group 'compilation)
 
+(defcustom grep-command nil
+  "The default grep command for \\[grep].
+The default value of this variable is set up by `grep-compute-defaults';
+call that function before using this variable in your program."
+  :type 'string
+  :get '(lambda (symbol)
+	  (or grep-command
+	      (progn (grep-compute-defaults) grep-command)))
+  :group 'compilation)
+
+(defcustom grep-find-command nil
+  "The default find command for \\[grep-find].
+The default value of this variable is set up by `grep-compute-defaults';
+call that function before using this variable in your program."
+  :type 'string
+  :get (lambda (symbol)
+	 (or grep-find-command
+	     (progn (grep-compute-defaults) grep-find-command)))
+  :group 'compilation)
+
 (defvar compilation-error-list nil
   "List of error message descriptors for visiting erring functions.
 Each error descriptor is a cons (or nil).  Its car is a marker pointing to
@@ -417,13 +437,6 @@ Otherwise, it saves all modified buffers without asking."
   "The default grep program for `grep-command' and `grep-find-command'.
 This variable's value takes effect when `grep-compute-defaults' is called.")
 
-;; Use -e if grep supports it,
-;; because that avoids lossage if the pattern starts with `-'.
-(defvar grep-command nil
-  "The default grep command for \\[grep].
-The real default value of this variable is set up by `grep-compute-defaults';
-call that function before using this variable.")
-
 (defvar grep-find-use-xargs nil
   "Whether \\[grep-find] uses the `xargs' utility by default.
 
@@ -432,11 +445,6 @@ if not nil and not `gnu', it uses `find -print' and `xargs'.
 
 This variable's value takes effect when `grep-compute-defaults' is called.")
 
-(defvar grep-find-command nil
-  "The default find command for \\[grep-find].
-The default value of this variable is set up by `grep-compute-defaults';
-call that function before using this variable.")
-
 ;;;###autoload
 (defcustom compilation-search-path '(nil)
   "*List of directories to search for source files named in error messages.
@@ -562,14 +570,15 @@ to a function that generates a unique name."
 	   (cons msg code)))))
 
 (defun grep-compute-defaults ()
-  (setq grep-command
-	(if (equal (condition-case nil	; in case "grep" isn't in exec-path
-		       (call-process grep-program nil nil nil
-				     "-e" "foo" null-device)
-		     (error nil))
-		   1)
-	    (format "%s -n -e " grep-program)
-	  (format "%s -n " grep-program)))
+  (unless grep-command
+    (setq grep-command
+	  (if (equal (condition-case nil ; in case "grep" isn't in exec-path
+			 (call-process grep-program nil nil nil
+				       "-e" "foo" null-device)
+		       (error nil))
+		     1)
+	      (format "%s -n -e " grep-program)
+	    (format "%s -n " grep-program))))
   (unless grep-find-use-xargs
     (setq grep-find-use-xargs
 	  (if (and
@@ -580,15 +589,16 @@ to a function that generates a unique name."
                                     "-0" "-e" "echo")
 		     0))
 	      'gnu)))
-  (setq grep-find-command
-	(cond ((eq grep-find-use-xargs 'gnu)
-	       (format "find . -type f -print0 | xargs -0 -e %s"
-		       grep-command))
-	      (grep-find-use-xargs
-	       (format "find . -type f -print | xargs %s" grep-command))
-	      (t (cons (format "find . -type f -exec %s {} %s \\;"
-			       grep-command null-device)
-		       (+ 22 (length grep-command)))))))
+  (unless grep-find-command
+    (setq grep-find-command
+	  (cond ((eq grep-find-use-xargs 'gnu)
+		 (format "find . -type f -print0 | xargs -0 -e %s"
+			 grep-command))
+		(grep-find-use-xargs
+		 (format "find . -type f -print | xargs %s" grep-command))
+		(t (cons (format "find . -type f -exec %s {} %s \\;"
+				 grep-command null-device)
+			 (+ 22 (length grep-command))))))))
 
 ;;;###autoload
 (defun grep (command-args)