bug#9278: rgrep fails on grep-find-command

[Juri Linkov]

Tags: patch

With some grep default values, typing `C-u C-u M-x rgrep RET M-p RET'
fails with:

(wrong-type-argument stringp ("find . -type f -exec grep -inH -e  {} +" . 35))

because `grep-compute-defaults' computes the default value of
`grep-find-command' to ("find . -type f -exec grep -inH -e {} +" . 35)
i.e. a cons of (STRING . POSITION) for INITIAL-CONTENTS
of `read-from-minibuffer' in `rgrep' and `grep-find'.

I don't know why `grep-find-command' has such a format (that also
is not documented in its docstring), but currently I don't see
a better solution.

So unless someone can propose a better fix, I'd like to install:

=== modified file 'lisp/progmodes/grep.el'
--- lisp/progmodes/grep.el      2011-08-10 18:15:32 +0000
+++ lisp/progmodes/grep.el      2011-08-10 19:30:02 +0000
@@ -965,7 +965,9 @@ (defun rgrep (regexp &optional files dir
     (unless (and dir (file-directory-p dir) (file-readable-p dir))
       (setq dir default-directory))
     (if (null files)
-       (if (not (string= regexp grep-find-command))
+       (if (not (string= regexp (if (consp grep-find-command)
+                                    (car grep-find-command)
+                                  grep-find-command)))
            (compilation-start regexp 'grep-mode))
       (setq dir (file-name-as-directory (expand-file-name dir)))
       (require 'find-dired)            ; for `find-name-arg'