On DOS/Windows, unnecessary load of tramp by `file-relative-name'

[David PONCE]

Hi All,

Since the following change to files.el:

2003-03-29  Kai Großjohann  <address@hidden>

        * files.el (file-relative-name): If FILENAME and DIRECTORY are
        on different drives (on DOS/Windows) or use different
        handlers, do like `expand-file-name' on FILENAME and return an
        absolute name.
        From Lars Hansen <address@hidden>.

I noticed that each time `file-relative-name' is called, tramp.el is
auto loaded, even if I don't access to remote files.

After some investigation, I found that `file-relative-name' put a
leading slash on file and directory names before comparing them to
find the relative name.  On DOS/Windows, when the name begins with a
drive letter, for example "c:/emacs", `file-relative-name' actually
use this form internally: "/c:/emacs".  Unfortunately that form
matches `tramp-file-name-regexp', which causes "tramp.el" to be loaded
when `file-relative-name' then calls `file-name-as-directory'.

To fix that, I propose the following patch to files.el:

Index: lisp/files.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/files.el,v
retrieving revision 1.653
diff -c -r1.653 files.el
*** lisp/files.el       24 Apr 2003 01:58:40 -0000      1.653
--- lisp/files.el       24 Apr 2003 09:45:22 -0000
***************
*** 2884,2899 ****
                                                        default-directory))))
      (setq filename (expand-file-name filename))
      (let ((hf (find-file-name-handler filename 'file-local-copy))
!           (hd (find-file-name-handler directory 'file-local-copy)))
        (when (and hf (not (get hf 'file-remote-p))) (setq hf nil))
        (when (and hd (not (get hd 'file-remote-p))) (setq hd nil))
        (if ;; Conditions for separate trees
          (or
           ;; Test for different drives on DOS/Windows
!          (and
!           (memq system-type '(ms-dos cygwin windows-nt))
!           (not (string-equal (substring filename  0 2)
!                              (substring directory 0 2))))
           ;; Test for different remote file handlers
           (not (eq hf hd))
           ;; Test for different remote file system identification
--- 2884,2899 ----
                                                        default-directory))))
      (setq filename (expand-file-name filename))
      (let ((hf (find-file-name-handler filename 'file-local-copy))
!           (hd (find-file-name-handler directory 'file-local-copy))
!           (test-drive (memq system-type '(ms-dos cygwin windows-nt))))
        (when (and hf (not (get hf 'file-remote-p))) (setq hf nil))
        (when (and hd (not (get hd 'file-remote-p))) (setq hd nil))
        (if ;; Conditions for separate trees
          (or
           ;; Test for different drives on DOS/Windows
!          (and test-drive
!                 (not (string-equal (substring filename  0 2)
!                                    (substring directory 0 2))))
           ;; Test for different remote file handlers
           (not (eq hf hd))
           ;; Test for different remote file system identification
***************
*** 2909,2917 ****
                 (string-match re directory)
                 (substring directory 0 (match-end 0))))))))
          filename
!         (unless (eq (aref filename 0) ?/)
          (setq filename (concat "/" filename)))
!         (unless (eq (aref directory 0) ?/)
          (setq directory (concat "/" directory)))
          (let ((ancestor ".")
              (filename-dir (file-name-as-directory filename)))
--- 2909,2922 ----
                 (string-match re directory)
                 (substring directory 0 (match-end 0))))))))
          filename
!         ;; On DOS/Windows, don't prefix filename with / if it starts
!         ;; with a drive letter.  That prevents unecessary loading of
!         ;; "tramp", because "/C:" matches `tramp-file-name-regexp'!
!         (unless (or (eq (aref filename 0) ?/)
!                     (and test-drive (string-match "^[A-Za-z]:" filename)))
          (setq filename (concat "/" filename)))
!         (unless (or (eq (aref directory 0) ?/)
!                     (and test-drive (string-match "^[A-Za-z]:" directory)))
          (setq directory (concat "/" directory)))
          (let ((ancestor ".")
              (filename-dir (file-name-as-directory filename)))

Maybe is there a better way to fix that?
What do you think?

Sincerely,
David

In GNU Emacs 21.3.50.1 (i386-mingw-nt4.0.1381)
 of 2003-04-24 on EBAT311
configured using `configure --with-gcc (3.2)'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ENU
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t