`k' in Dired with inserted subdirectories.

[Luc Teirlinck <teirllm@dms.auburn.edu>]

There are inconsistencies regarding the behavior of `k' for subdirectories.
Also, `dired-do-kill-lines' contains several lines of code that can
_never_ be executed.

First problem:

Doc string:

  To kill an entire subdirectory, go to its directory header line and
  use this command with a prefix argument (the value does not matter).

No other way to kill a subdirectory is mentioned.

Emacs manual:

     If you kill the line for a file that is a directory, the directory's
  contents are also deleted from the buffer.  Typing `C-u k' on the
  header line for a subdirectory is another way to delete a subdirectory
  from the Dired buffer.

The fact that C-u k on a subdirectory header line kills that
subdirectory is uncontested.  But what for `k' on a line for a file
that is a directory (but _not_ a directory header line)?

Actual behavior:

If a numeric prefix argument is used and if the directory is inserted in
the buffer, it _is_ removed.  But if marks are used, it is _not_ removed.
What _should_ the behavior be?  Or is the current behavior for some
reason OK, but just not correctly documented?

Second problem with `dired-do-kill-lines':

There is some code in `dired-do-kill-lines' that attempts to delete
all lines that are _not_ marked if a numeric prefix argument is given.
This conflicts with the standard meaning of a numeric prefix argument
in Dired, which `dired-do-kill-lines' _also_ implements.  As a result the
`delete-if-not-marked' with numeric prefix argument code will _never_ be
executed.  So why is it there?  It will never cause bugs, but it is
confusing:

  (if arg
      (if (dired-get-subdir)
        (dired-kill-subdir)
	(dired-kill-line arg))
    ;; Pesonal remark: arg is nil now.
    (save-excursion
      (goto-char (point-min))
      (let (buffer-read-only (count 0))
      ;; Personal remark:  This is equivalent with:
      ;; (if t                          ; kill marked lies
      (if (not arg)			; kill marked lines
 

   ;; else kill unmarked lines
   ;; Personal remark: who cares, `else' _never_ happens.
     (while (not (eobp))         

Sincerely,

Luc.