Fix some glitches in recent directory-files-* changes

* doc/lispref/files.texi (Contents of Directories):
Fix description of directory-files, directory-empty-p and
directory-files-and-attributes.

* etc/NEWS: Fix entry for directory-files-and-attributes.  Fix typos.

* lisp/dired.el (directory-empty-p): Move function from here ...

* lisp/files.el (directory-empty-p): ... to here.

* lisp/net/ange-ftp.el (ange-ftp-directory-files): Call `nreverse' later.

* lisp/net/tramp.el (tramp-handle-directory-files):
* lisp/net/tramp-adb.el
(tramp-adb-handle-directory-files-and-attributes): Do not call
`nreverse'.

* src/dired.c (Fdirectory_files)
(Fdirectory_files_and_attributes): Fix docstrings.

* test/src/dired-tests.el: Removed.  Tests moved to
test/lisp/dired-tests.el.

* test/lisp/dired-tests.el (dired-test-bug27899): Tag it :unstable.
(dired-test-directory-files)
(dired-test-directory-files-and-attributes): New tests.

12 files changed, 124 insertions, 161 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index f707fde88a8..d49ac42bb46 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -2917,7 +2917,7 @@ or display the names in a buffer using the @code{ls} shell command.  In
 the latter case, it can optionally display information about each file,
 depending on the options passed to the @code{ls} command.
 
-@defun directory-files directory &optional full-name match-regexp nosort
+@defun directory-files directory &optional full-name match-regexp nosort count
 This function returns a list of the names of the files in the directory
 @var{directory}.  By default, the list is in alphabetical order.
 
@@ -2954,20 +2954,14 @@ An error is signaled if @var{directory} is not the name of a directory
 that can be read.
 @end defun
 
-@defun directory-empty-p filename
-This utility function returns t if given @var{filename} is an
-accessible directory and it does not contain any files, i.e. is an
-empty directory.  It will ignore '.' and '..' on systems that returns
-them as files in a directory.
-
-As a special case, this function will also return t if
-FILENAME is the empty string ("").  This quirk is due to Emacs
-interpreting the empty string (in some cases) as the current
-directory.
+@defun directory-empty-p directory
+This utility function returns @code{t} if given @var{directory} is an
+accessible directory and it does not contain any files, i.e., is an
+empty directory.  It will ignore @samp{.} and @samp{..} on systems
+that return them as files in a directory.
 
 Symbolic links to directories count as directories.
 See @var{file-symlink-p} to distinguish symlinks.
-
 @end defun
 
 @cindex recursive traverse of directory tree
@@ -3016,7 +3010,7 @@ is called with one argument (the file or directory) and should return
 non-@code{nil} if that directory is the one it is looking for.
 @end defun
 
-@defun directory-files-and-attributes directory &optional full-name match-regexp nosort id-format
+@defun directory-files-and-attributes directory &optional full-name match-regexp nosort id-format count
 This is similar to @code{directory-files} in deciding which files
 to report on and how to report their names.  However, instead
 of returning a list of file names, it returns for each file a
diff --git a/etc/NEWS b/etc/NEWS
index 5fbe0755fed..4ddb1924935 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1704,34 +1704,34 @@ argument 'ellipsis', will now indicate truncation using '…' when
 the selected frame can display it, and using "..." otherwise.
 
 +++
-*** New command 'make-directory-autoloads'.
+** New command 'make-directory-autoloads'.
 This does the same as the old command 'update-directory-autoloads',
 but has different semantics: Instead of passing in the output file via
 the dynamically bound 'generated-autoload-file' variable, the output
 file is now a explicit parameter.
 
 +++
-*** New function 'string-search'.
+** New function 'string-search'.
 This function takes two string parameters and returns the position of
 the first instance of the former string in the latter.
 
 +++
-*** New function 'string-replace'.
+** New function 'string-replace'.
 This function works along the line of 'replace-regexp-in-string', but
 matching on strings instead of regexps, and does not change the global
 match state.
 
 +++
-*** New function 'process-lines-ignore-status'.
+** New function 'process-lines-ignore-status'.
 This is like 'process-lines', but does not signal an error if the
 return status is non-zero.  'process-lines-handling-status' has also
 been added, and takes a callback to handle the return status.
 
 ---
-*** 'ascii' is now a coding system alias for 'us-ascii'.
+** 'ascii' is now a coding system alias for 'us-ascii'.
 
 +++
-*** New function 'file-backup-file-names'.
+** New function 'file-backup-file-names'.
 This function returns the list of file names of all the backup files
 of its file argument.
 
@@ -1744,7 +1744,8 @@ directory and whether it contains no other directories or files.
 ** 'directory-files' now takes an additional COUNT parameter.
 The parameter makes 'directory-files' return COUNT first file names
 from a directory.  If MATCH is also given, the function will return
-first COUNT file names that match the expression.
+first COUNT file names that match the expression.  The same COUNT
+parameter has been added to 'directory-files-and-attributes'.
 
 +++
 ** The 'count-lines' function now takes an optional parameter to
diff --git a/lisp/dired.el b/lisp/dired.el
index 5ac2f203347..08b19a02250 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -3016,20 +3016,6 @@ dired-buffers."
 ;; Tree Dired
 
 ;;; utility functions
-(defun directory-empty-p (filename)
-  "Return t if FILENAME names an existing directory containing no
-other files.  Return nil if FILENAME does not name a directory, or if
-there was trouble determining whether DIRECTORYNAME is a directory or empty.
-
-As a special case, this function will also return t if FILENAME is the
-empty string (\"\").  This quirk is due to Emacs interpreting the
-empty string (in some cases) as the current directory.
-
-Symbolic links to directories count as directories.
-See `file-symlink-p' to distinguish symlinks.  "
-  (and (file-directory-p filename)
-       (null (directory-files
-              filename nil directory-files-no-dot-files-regexp t 1))))
 
 (defun dired-in-this-tree-p (file dir)
   ;;"Is FILE part of the directory tree starting at DIR?"
diff --git a/lisp/files.el b/lisp/files.el
index 59bcc3e8a78..e55552a2d9a 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -888,6 +888,16 @@ recursion."
             (push (concat dir "/" file) files)))))
     (nconc result (nreverse files))))
 
+(defun directory-empty-p (dir)
+  "Return t if DIR names an existing directory containing no other files.
+Return nil if DIR does not name a directory, or if there was
+trouble determining whether DIR is a directory or empty.
+
+Symbolic links to directories count as directories.
+See `file-symlink-p' to distinguish symlinks."
+  (and (file-directory-p dir)
+       (null (directory-files dir nil directory-files-no-dot-files-regexp t 1))))
+
 (defvar module-file-suffix)
 
 (defun load-file (file)
diff --git a/lisp/net/ange-ftp.el b/lisp/net/ange-ftp.el
index 7ce90504ba3..15322219eff 100644
--- a/lisp/net/ange-ftp.el
+++ b/lisp/net/ange-ftp.el
@@ -3442,9 +3442,9 @@ system TYPE.")
             (if (or (not match) (string-match-p match f))
                 (setq files
                       (cons (if full (concat directory f) f) files))))
-          (nreverse files))
-        (when (natnump count)
-          (setq files (last files count))))
+          (when (natnump count)
+            (setq files (last files count)))
+          (nreverse files)))
     (apply 'ange-ftp-real-directory-files directory full match nosort count)))
 
 (defun ange-ftp-directory-files-and-attributes
diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index e8dbe1618d0..8ccbe412f2b 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -344,14 +344,14 @@ ARGUMENTS to pass to the OPERATION."
                      (sort result (lambda (x y) (string< (car x) (car y))))))
 
              (setq result (delq nil
-                                (mapcar (lambda (x) (if (or (not match)
-                                                            (string-match-p
-                                                             match (car x)))
-                                                        x)) result)))
+                                (mapcar
+                                 (lambda (x) (if (or (not match)
+                                                     (string-match-p
+                                                      match (car x)))
+                                                 x))
+                                 result)))
              (when (natnump count)
-               (setq result (last result count))
-               (nreverse result))
-
+               (setq result (last result count)))
              result)))))))
 
 (defun tramp-adb-get-ls-command (vec)
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 7afd6fac47d..915ce2f6a65 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -1701,6 +1701,7 @@ ID-FORMAT valid values are `string' and `integer'."
                     (tramp-get-remote-gid v 'integer)))))))))
 
 ;; Directory listings.
+
 (defun tramp-sh-handle-directory-files-and-attributes
   (directory &optional full match nosort id-format count)
   "Like `directory-files-and-attributes' for Tramp files."
@@ -1744,7 +1745,7 @@ ID-FORMAT valid values are `string' and `integer'."
           (tramp-handle-directory-files-and-attributes
            directory full match nosort id-format count)))))
 
-;; FIXME Fix function to work with count parameter.
+;; FIXME: Fix function to work with count parameter.
 (defun tramp-do-directory-files-and-attributes-with-perl
   (vec localname &optional id-format)
   "Implement `directory-files-and-attributes' for Tramp files using a Perl script."
@@ -1760,7 +1761,7 @@ ID-FORMAT valid values are `string' and `integer'."
     (when (stringp object) (tramp-error vec 'file-error object))
     object))
 
-;; FIXME Fix function to work with count parameter.
+;; FIXME: Fix function to work with count parameter.
 (defun tramp-do-directory-files-and-attributes-with-stat
   (vec localname &optional id-format)
   "Implement `directory-files-and-attributes' for Tramp files using stat(1) command."
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index b3b6a94e9cc..3220e516050 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -704,7 +704,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
                     (mapcar (lambda (x) (when (string-match-p match x) x))
                             result))))
 
-    ;; return count number of results
+    ;; Return count number of results.
     (when (and (natnump count) (> count 0))
       (setq result (nbutlast result (- (length result) count))))
 
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 25fa9754881..ce0a2b54ff5 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -3135,8 +3135,8 @@ User is always nil."
       (unless nosort
         (setq result (sort result #'string<)))
       (when (natnump count)
-        (setq result (last file count))
-        (nreverse files)))))
+        (setq result (last result count)))
+      result)))
 
 (defun tramp-handle-directory-files-and-attributes
   (directory &optional full match nosort id-format count)
diff --git a/src/dired.c b/src/dired.c
index 120934bfe74..039dd68c177 100644
--- a/src/dired.c
+++ b/src/dired.c
@@ -169,9 +169,9 @@ directory_files_internal (Lisp_Object directory, Lisp_Object full,
 {
   ptrdiff_t ind = 0, last = MOST_POSITIVE_FIXNUM;
 
-  if (!NILP(return_count))
+  if (!NILP (return_count))
     {
-      CHECK_FIXNAT(return_count);
+      CHECK_FIXNAT (return_count);
       last = XFIXNAT (return_count);
     }
 
@@ -302,7 +302,7 @@ directory_files_internal (Lisp_Object directory, Lisp_Object full,
 
 DEFUN ("directory-files", Fdirectory_files, Sdirectory_files, 1, 5, 0,
        doc: /* Return a list of names of files in DIRECTORY.
-There are three optional arguments:
+There are four optional arguments:
 If FULL is non-nil, return absolute file names.  Otherwise return names
  that are relative to the specified directory.
 If MATCH is non-nil, mention only file names whose non-directory part
@@ -338,7 +338,7 @@ Value is a list of the form:
 where each FILEn-ATTRS is the attributes of FILEn as returned
 by `file-attributes'.
 
-This function accepts four optional arguments:
+This function accepts five optional arguments:
 If FULL is non-nil, return absolute file names.  Otherwise return names
  that are relative to the specified directory.
 If MATCH is non-nil, mention only file names whose non-directory part
@@ -347,10 +347,10 @@ If NOSORT is non-nil, the list is not sorted--its order is unpredictable.
  NOSORT is useful if you plan to sort the result yourself.
 ID-FORMAT specifies the preferred format of attributes uid and gid, see
  `file-attributes' for further documentation.
-On MS-Windows, performance depends on `w32-get-true-file-attributes',
-which see.
 If COUNT is non-nil and a natural number, the function will return
- COUNT number of file names (if so many are present).  */)
+ COUNT number of file names (if so many are present).
+On MS-Windows, performance depends on `w32-get-true-file-attributes',
+which see.  */)
   (Lisp_Object directory, Lisp_Object full, Lisp_Object match,
    Lisp_Object nosort, Lisp_Object id_format, Lisp_Object count)
 {
diff --git a/test/lisp/dired-tests.el b/test/lisp/dired-tests.el
index cec533ddfaa..66f8ed95b89 100644
--- a/test/lisp/dired-tests.el
+++ b/test/lisp/dired-tests.el
@@ -293,6 +293,7 @@
 
 (ert-deftest dired-test-bug27899 ()
   "Test for https://debbugs.gnu.org/27899 ."
+  :tags '(:unstable)
   (dired (list (expand-file-name "src" source-directory)
                "cygw32.c" "alloc.c" "w32xfns.c" "xdisp.c"))
   (let ((orig dired-hide-details-mode))
@@ -440,6 +441,81 @@
        (should (= 6 (length (dired-get-marked-files)))) ; All empty dirs but zeta-empty-dir deleted.
      (advice-remove 'read-answer 'dired-test-bug27940-advice))))
 
+(ert-deftest dired-test-directory-files ()
+  "Test for `directory-files'."
+  (let ((testdir (expand-file-name
+                  "directory-files-test" (temporary-file-directory)))
+        (nod directory-files-no-dot-files-regexp))
+    (unwind-protect
+        (progn
+          (when (file-directory-p testdir)
+            (delete-directory testdir t))
+
+          (make-directory testdir)
+          (when (file-directory-p testdir)
+            ;; directory-empty-p: test non-existent dir
+            (should-not (directory-empty-p "some-imaginary-dir"))
+            (should (= 2 (length (directory-files testdir))))
+            ;; directory-empty-p: test empty dir
+            (should (directory-empty-p testdir))
+            (should-not (directory-files testdir nil nod t 1))
+            (dolist (file '(a b c d))
+              (make-empty-file (expand-file-name (symbol-name file) testdir)))
+            (should (= 6 (length (directory-files testdir))))
+            (should (equal "abcd" (mapconcat 'identity (directory-files
+                                                        testdir nil nod) "")))
+            (should (= 2 (length (directory-files testdir nil "[bc]"))))
+            (should (= 3 (length (directory-files testdir nil nod nil 3))))
+            (dolist (file '(5 4 3 2 1))
+              (make-empty-file
+               (expand-file-name (number-to-string file) testdir)))
+            ;;(should (= 0 (length (directory-files testdir nil "[0-9]" t -1))))
+            (should (= 5 (length (directory-files testdir nil "[0-9]" t))))
+            (should (= 5 (length (directory-files testdir nil "[0-9]" t 50))))
+            (should-not (directory-empty-p testdir)))
+
+          (delete-directory testdir t)))))
+
+(ert-deftest dired-test-directory-files-and-attributes ()
+  "Test for `directory-files-and-attributes'."
+  (let ((testdir (expand-file-name
+                  "directory-files-test" (temporary-file-directory)))
+        (nod directory-files-no-dot-files-regexp))
+
+    (unwind-protect
+        (progn
+          (when (file-directory-p testdir)
+            (delete-directory testdir t))
+
+          (make-directory testdir)
+          (when (file-directory-p testdir)
+            (should (= 2 (length (directory-files testdir))))
+            (should-not (directory-files-and-attributes testdir t nod t 1))
+            (dolist (file '(a b c d))
+              (make-directory (expand-file-name (symbol-name file) testdir)))
+            (should (= 6 (length (directory-files-and-attributes testdir))))
+            (dolist (dir (directory-files-and-attributes testdir t nod))
+              (should (file-directory-p (car dir)))
+              (should-not (file-regular-p (car dir))))
+            (should (= 2 (length
+                          (directory-files-and-attributes testdir nil "[bc]"))))
+            (should (= 3 (length
+                          (directory-files-and-attributes
+                           testdir nil nod nil nil 3))))
+            (dolist (file '(5 4 3 2 1))
+              (make-empty-file
+               (expand-file-name (number-to-string file) testdir)))
+            ;; (should (= 0 (length (directory-files-and-attributes testdir nil
+            ;;                                                      "[0-9]" t
+            ;;                                                      nil -1))))
+            (should (= 5 (length
+                          (directory-files-and-attributes
+                           testdir nil "[0-9]" t))))
+            (should (= 5 (length
+                          (directory-files-and-attributes
+                           testdir nil "[0-9]" t nil 50))))))
+      (when (file-directory-p testdir)
+        (delete-directory testdir t)))))
 
 (provide 'dired-tests)
 ;; dired-tests.el ends here
diff --git a/test/src/dired-tests.el b/test/src/dired-tests.el
deleted file mode 100644
index 3beb51366f7..00000000000
--- a/test/src/dired-tests.el
+++ /dev/null
@@ -1,105 +0,0 @@
-;;; dired-tests.el --- Tests for directory-files in dired.c  -*- lexical-binding: t; -*-
-
-;; Copyright (C) 2020 Free Software Foundation, Inc.
-
-;; Author: Arthur Miller <arthur.miller@live.com>
-;; Keywords:
-
-;; This program is free software; you can redistribute it and/or modify
-;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation, either version 3 of the License, or
-;; (at your option) any later version.
-
-;; This program is distributed in the hope that it will be useful,
-;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;; GNU General Public License for more details.
-
-;; You should have received a copy of the GNU General Public License
-;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-;;; Commentary:
-
-;; These tests check mostly for correct behaviour with COUNT argument.
-
-;;; Code:
-(require 'ert)
-
-(ert-deftest directory-files-tests ()
-  (let ((testdir (expand-file-name "directory-files-test"
-                                (temporary-file-directory)))
-        (nod directory-files-no-dot-files-regexp))
-    (unwind-protect
-        (progn
-          (when (file-directory-p testdir)
-            (delete-directory testdir t))
-
-          (make-directory testdir)
-          (when (file-directory-p testdir)
-            ;; directory-empty-p: test non-existent dir
-            (should-not (directory-empty-p "some-imaginary-dir"))
-            (should (= 2 (length (directory-files testdir))))
-            ;; directory-empty-p: test empty dir
-            (should (directory-empty-p testdir))
-            (should-not (directory-files testdir nil nod t 1))
-            (dolist (file '(a b c d))
-              (make-empty-file (expand-file-name (symbol-name file) testdir)))
-            (should (= 6 (length (directory-files testdir))))
-            (should (equal "abcd" (mapconcat 'identity (directory-files
-                                                        testdir nil nod) "")))
-            (should (= 2 (length (directory-files testdir nil "[bc]"))))
-            (should (= 3 (length (directory-files testdir nil nod nil 3))))
-            (dolist (file '(5 4 3 2 1))
-              (make-empty-file (expand-file-name (number-to-string
-                                                  file) testdir)))
-            ;;(should (= 0 (length (directory-files testdir nil "[0-9]" t -1))))
-            (should (= 5 (length (directory-files testdir nil "[0-9]" t))))
-            (should (= 5 (length (directory-files testdir nil "[0-9]" t 50))))
-            (should-not (directory-empty-p testdir)))
-
-          (delete-directory testdir t)))))
-
-(ert-deftest directory-files-and-attributes-tests ()
-  (let ((testdir (expand-file-name "directory-files-test"
-                                (temporary-file-directory)))
-        (nod directory-files-no-dot-files-regexp))
-
-    (unwind-protect
-        (progn
-          (when (file-directory-p testdir)
-            (delete-directory testdir t))
-
-          (make-directory testdir)
-          (when (file-directory-p testdir)
-            (should (= 2 (length (directory-files testdir))))
-            (should-not (directory-files-and-attributes testdir t nod t 1))
-            (dolist (file '(a b c d))
-              (make-directory (expand-file-name (symbol-name file) testdir)))
-            (should (= 6 (length (directory-files-and-attributes testdir))))
-            (dolist (dir (directory-files-and-attributes testdir t nod))
-              (should (file-directory-p (car dir)))
-              (should-not (file-regular-p (car dir))))
-            (should (= 2 (length
-                          (directory-files-and-attributes testdir nil
-                                                          "[bc]"))))
-            (should (= 3 (length
-                          (directory-files-and-attributes testdir nil nod
-                                                          nil nil 3))))
-            (dolist (file '(5 4 3 2 1))
-              (make-empty-file (expand-file-name (number-to-string file)
-                                                 testdir)))
-            ;; (should (= 0 (length (directory-files-and-attributes testdir nil
-            ;;                                                      "[0-9]" t
-            ;;                                                      nil -1))))
-            (should (= 5 (length
-                          (directory-files-and-attributes testdir nil
-                                                          "[0-9]" t))))
-            (should (= 5 (length
-                          (directory-files-and-attributes testdir nil
-                                                          "[0-9]" t
-                                                          nil 50))))))
-      (when (file-directory-p testdir)
-        (delete-directory testdir t)))))
-
-(provide 'dired-tests)
-;;; dired-tests.el ends here