I tried the following at the Cygwin shell:<br><br>epich@laptop02 ~/sw/cedet/lisp/cedet $  emacs -batch --no-site-file --eval &#39;(setq debug-on-error t)&#39; -l &quot;../../cedet-remove-builtin.el&quot; -L . --eval &#39;(progn (require (quote cedet-compat)) (require (quote mode-local)))&#39; -L ../eieio/ -L ./ -L ./ --eval &#39;(progn  (setq generated-autoload-file &quot;/home/epich/sw/cedet/lisp/cedet/loaddefs.el&quot;) (message &quot;DEBUG: expanded file name is %s source-directory is %s&quot; (expand-file-name &quot;/home/epich/sw/cedet/lisp/cedet&quot;) source-directory))&#39; -f batch-update-autoloads /home/epich/sw/cedet/lisp/cedet<br>
DEBUG: expanded file name is c:/home/epich/sw/cedet/lisp/cedet source-directory is d:/devel/emacs/release/emacs24/emacs-24.2/<br>Debugger entered--Lisp error: (file-error &quot;Opening output file&quot; &quot;no such file or directory&quot; &quot;d:/home/epich/sw/cedet/lisp/cedet/loaddefs.el&quot;)<br>
  write-region(&quot;;;; loaddefs.el --- automatically extracted autoloads\n;;\n;;; Code:\n\n\f\n(provide &#39;loaddefs)\n;; Local Variables:\n;; version-control: never\n;; no-byte-compile: t\n;; no-update-autoloads: t\n;; coding: utf-8\n;; End:\n;;; loaddefs.el ends here\n&quot; nil &quot;d:/home/epich/sw/cedet/lisp/cedet/loaddefs.el&quot;)<br>
  autoload-ensure-default-file(&quot;d:/home/epich/sw/cedet/lisp/cedet/loaddefs.el&quot;)<br>  autoload-find-generated-file()<br>  update-directory-autoloads(&quot;/home/epich/sw/cedet/lisp/cedet&quot;)<br>  apply(update-directory-autoloads &quot;/home/epich/sw/cedet/lisp/cedet&quot;)<br>
  batch-update-autoloads()<br>  command-line-1((&quot;--eval&quot; &quot;(setq debug-on-error t)&quot; &quot;-l&quot; &quot;../../cedet-remove-builtin.el&quot; &quot;-L&quot; &quot;.&quot; &quot;--eval&quot; &quot;(progn (require (quote cedet-compat)) (require (quote mode-local)))&quot; &quot;-L&quot; &quot;../eieio/&quot; &quot;-L&quot; &quot;./&quot; &quot;-L&quot; &quot;./&quot; &quot;--eval&quot; &quot;(progn  (setq generated-autoload-file \&quot;/home/epich/sw/cedet/lisp/cedet/loaddefs.el\&quot;) (message \&quot;DEBUG: expanded file name is %s source-directory is %s\&quot; (expand-file-name \&quot;/home/epich/sw/cedet/lisp/cedet\&quot;) source-directory))&quot; &quot;-f&quot; &quot;batch-update-autoloads&quot; &quot;/home/epich/sw/cedet/lisp/cedet&quot;))<br>
  command-line()<br>  normal-top-level()<br><br>This shows c: and d: prefixes in the same message evaluation.<br><br>I haven&#39;t mentioned yet that I don&#39;t have a D drive mounted at all.<br><br>I tried C-h v source-directory in a running Emacs and found:<br>
<br>   source-directory is a variable defined in `lread.c&#39;.<br>   Its value is &quot;d:/devel/emacs/release/emacs24/emacs-24.2/&quot;<br><br>   Documentation:<br>   Directory in which Emacs sources were found when Emacs was built.<br>
   You cannot count on them to still be there!<br><br>I did not find this /devel/emacs/release/emacs24/emacs-24.2/ on my system, nor is it the kind of path I would create.  My emacs is at C:\Users\epich\sw\emacs-24.2 which appears in Cygwin at ~/sw/emacs-24.2 because ~/sw symlinks (MS console command mklink /d) to /cygdrive/c/Users/epich/sw .<br>
<br>I actually launch Emacs from the Quick Launch on Windows 7, so the C-h v evaluation has Cygwin out of the equation.  I merely use Cygwin to byte compile.<br><br><br>