Fix documentation and implementation of 'directory-name-p'

* lisp/files.el (directory-name-p): Modify to recognize
backslashes on MS-Windows and MS-DOS.  Adjust the doc string
accordingly.  Use '=', not char-equal, for comparison, as
letter-case cannot possibly be an issue here.

* doc/lispref/files.texi (Directory Names): Move the documentation
of directory-name-p here from "Relative File Names".  Update the
description per the changes in implementation.

* etc/NEWS: Move the entry for 'directory-name-p' to its proper
place and mark it documented.

1 files changed, 7 insertions, 5 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index e8ed7ccd9f7..918bf5becbd 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -2030,11 +2030,6 @@ form.
 @end example
 @end defun
 
-@defun directory-name-p filename
-This function returns non-@code{nil} if @var{filename} ends with a
-forward slash (@samp{/}) character.
-@end defun
-
 @node Directory Names
 @subsection Directory Names
 @cindex directory name
@@ -2076,6 +2071,13 @@ string (if it does not already end in one).
 @end example
 @end defun
 
+@defun directory-name-p filename
+This function returns non-@code{nil} if @var{filename} ends with a
+directory separator character.  This is the forward slash @samp{/} on
+Unix and GNU systems; MS-Windows and MS-DOS recognize both the forward
+slash and the backslash @samp{\} as directory separators.
+@end defun
+
 @defun directory-file-name dirname
 This function returns a string representing @var{dirname} in a form
 that the operating system will interpret as the name of a file (a