+
+;; If we are building w3 in a different directory than the source
+;; directory, we must read *.el from source directory and write *.elc
+;; into the building directory. For that, we define this function
+;; before loading bytecomp. Bytecomp doesn't overwrite this function.
+(defun byte-compile-dest-file (filename)
+ "Convert an Emacs Lisp source file name to a compiled file name.
+ In addition, remove directory name part from FILENAME."
+ (setq filename (byte-compiler-base-file-name filename))
+ (setq filename (file-name-sans-versions filename))
+ (setq filename (file-name-nondirectory filename))
+ (if (memq system-type '(win32 w32 mswindows windows-nt))
+ (setq filename (downcase filename)))
+ (cond ((eq system-type 'vax-vms)
+ (concat (substring filename 0 (string-match ";" filename)) "c"))
+ ((string-match emacs-lisp-file-regexp filename)
+ (concat (substring filename 0 (match-beginning 0)) ".elc"))
+ (t (concat filename ".elc"))))
+