bug#8484: 24.0.50; Dired problems with marking and hidden subdirs

[Stephen Berman]

1. emacs -Q
2. Create a directory containing a non-empty directory,
   e.g. "~/test/test0/test1". 
3. Visit "test" in Dired: `C-x d ~/test RET'
4. Put point on "test0" and type `i' to insert the subdirectory.
5. With point within the inserted subdirectory type `$' to hide it.
6. Type `% m RET' to mark all files except "." and "..".  This is what
   buffer "test" now looks like:

     /home/steve/test:
     total used in directory 12 available 24083132
     drwxr-xr-x 3 steve users 4096 2011-04-12 09:22 .
     drwxr-xr-x 6 steve users 4096 2011-04-12 09:20 ..
   * drwxr-xr-x 3 steve users 4096 2011-04-12 09:23 test0
   
   * /home/steve/test/test0:...

7. Try to operate on the marked files, e.g. `C', `R', 'D' etc.
=> Instead of the operation being executed, you get the message "Cannot
operate on `.' or `..'".
8. Now type `$' on the hidden subdirectory to unhide it.  The two marked
   lines remain marked.  Then repeat step 7.
=> Regardless of where point is, you get this error: "No file on this line"

I believe these problems are due to the hidden subdirectory being a
single line, since selective display replaces "\n" with "\r".  In the
first case, when dired-mark-if is called in dired-mark-files-regexp,
with point at the beginning of the hidden subdirectory, (looking-at
dired-re-dot) is nil but dired-get-filename finds "." inside "test0",
and this triggers the error message.  In the second case, when
dired-move-to-filename is called in dired-map-over-marks with point on
the subdirectory, it fails and raises the error.

I see two directions to go for fixing this: (a) temporarily unhide the
subdirectory (probably iteratively) and then mark as usual, so that the
dired-re-dot filter succeeds; (b) prevent any marking of (and hence
within) hidden subdirectories.  It seems that the latter is more
consistent with current Dired behavior: if you remove the marks from
"test" above, then unhide "test0", then type `% m RET', so that now
"test0" and "test1" are marked, then hide "test0" again, then invoke an
operation, e.g. `C', `R', 'D' etc. -- only "test0" gets operated on, not
"test1".  That is, the marked file in the hidden subdirectory is
ignored.  So marking the hidden subdirectory in step 6 above is the real
bug, given current Dired behavior.  One way to fix this is the below
patch to dired-get-filename: this checks whether the current line is a
hidden subdirectory and if so, unhides it, so that it isn't just a
single line and the line does not get marked, then after
dired-move-to-filename fails, hides it again, shortcutting any further
marking.

In GNU Emacs 24.0.50.1 (i686-suse-linux-gnu, GTK+ Version 2.20.1)
 of 2011-04-03 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10800000
configured using `configure  '--without-toolkit-scroll-bars' 'CFLAGS=-g -O2 
-fno-optimize-sibling-calls''

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: en_US.UTF-8
  value of $XMODIFIERS: @im=local
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t


*** /data/steve/bzr/emacs/trunk/lisp/dired.el   2011-04-03 16:10:27.000000000 
+0200
--- /data/steve/bzr/emacs/quickfixes/lisp/dired.el      2011-04-12 
12:48:02.000000000 +0200
***************
*** 2049,2058 ****
  Optional arg NO-ERROR-IF-NOT-FILEP means treat `.' and `..' as
  regular filenames and return nil if no filename on this line.
  Otherwise, an error occurs in these cases."
!   (let (case-fold-search file p1 p2 already-absolute)
      (save-excursion
        (if (setq p1 (dired-move-to-filename (not no-error-if-not-filep)))
          (setq p2 (dired-move-to-end-of-filename no-error-if-not-filep))))
      ;; nil if no file on this line, but no-error-if-not-filep is t:
      (if (setq file (and p1 p2 (buffer-substring p1 p2)))
        (progn
--- 2049,2061 ----
  Optional arg NO-ERROR-IF-NOT-FILEP means treat `.' and `..' as
  regular filenames and return nil if no filename on this line.
  Otherwise, an error occurs in these cases."
!   (let ((hidden (dired-subdir-hidden-p (dired-current-directory)))
!       case-fold-search file p1 p2 already-absolute)
!     (if hidden (dired-unhide-subdir))
      (save-excursion
        (if (setq p1 (dired-move-to-filename (not no-error-if-not-filep)))
          (setq p2 (dired-move-to-end-of-filename no-error-if-not-filep))))
+     (if hidden (dired-hide-subdir 1))
      ;; nil if no file on this line, but no-error-if-not-filep is t:
      (if (setq file (and p1 p2 (buffer-substring p1 p2)))
        (progn