(grep-default-command): Catch errors from wildcard-to-regexp.

diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 1c29bfe9cc87e3eff604c1480a7c2baa52b74dab..a939d54b3c9fb8457d51718f405271b06ec8654e 100644 (file)
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -465,28 +465,38 @@ Set up `compilation-exit-message-function' and run `grep-setup-hook'."
       ""))
 
 (defun grep-default-command ()
+  "Compute the default grep command for C-u M-x grep to offer."
   (let ((tag-default (shell-quote-argument (grep-tag-default)))
+       ;; This a regexp to match single shell arguments.
+       ;; Could someone please add comments explaining it?
        (sh-arg-re "\\(\\(?:\"\\(?:[^\"]\\|\\\\\"\\)+\"\\|'[^']+'\\|[^\"' \t\n]\\)+\\)")
        (grep-default (or (car grep-history) grep-command)))
-    ;; Replace the thing matching for with that around cursor.
+    ;; In the default command, find the arg that specifies the pattern.
     (when (or (string-match
               (concat "[^ ]+\\s +\\(?:-[^ ]+\\s +\\)*"
                       sh-arg-re "\\(\\s +\\(\\S +\\)\\)?")
               grep-default)
              ;; If the string is not yet complete.
              (string-match "\\(\\)\\'" grep-default))
-      (unless (or (not (stringp buffer-file-name))
-                 (when (match-beginning 2)
-                   (save-match-data
-                     (string-match
-                      (wildcard-to-regexp
-                       (file-name-nondirectory
-                        (match-string 3 grep-default)))
-                      (file-name-nondirectory buffer-file-name)))))
-       (setq grep-default (concat (substring grep-default
-                                             0 (match-beginning 2))
-                                  " *."
-                                  (file-name-extension buffer-file-name))))
+      ;; Maybe we will replace the pattern with the default tag.
+      ;; But first, maybe replace the file name pattern.
+      (condition-case nil
+         (unless (or (not (stringp buffer-file-name))
+                     (when (match-beginning 2)
+                       (save-match-data
+                         (string-match
+                          (wildcard-to-regexp
+                           (file-name-nondirectory
+                            (match-string 3 grep-default)))
+                          (file-name-nondirectory buffer-file-name)))))
+           (setq grep-default (concat (substring grep-default
+                                                 0 (match-beginning 2))
+                                      " *."
+                                      (file-name-extension buffer-file-name))))
+       ;; In case wildcard-to-regexp gets an error
+       ;; from invalid data.
+       (error nil))
+      ;; Now replace the pattern with the default tag.
       (replace-match tag-default t t grep-default 1))))