dired-mark-suffix: New command

Now dired-mark-extension prepends '.' to extension when not present.
Add command dired-mark-suffix to preserve the previous
behaviour (Bug#25942).
* lisp/dired-x.el (dired-mark-suffix): New command;
mark files ending in a given suffix.
(dired--mark-suffix-interactive-spec): New defun.
(dired-mark-extension, dired-mark-suffix): Use it.
* doc/misc/dired-x.texi (Advanced Mark Commands): Update manual.
* test/lisp/dired-x-tests.el: New test suite; add test for these features.
; * etc/NEWS (Incompatible Lisp Changes in Emacs 26.1):
; Mention these changes.

1 files changed, 15 insertions, 3 deletions

diff --git a/doc/misc/dired-x.texi b/doc/misc/dired-x.texi
index 1e6f4b03bb0..bf103256f29 100644
--- a/doc/misc/dired-x.texi
+++ b/doc/misc/dired-x.texi
@@ -721,15 +721,27 @@ variable @code{window-min-height}.
 @item dired-mark-extension
 @findex dired-mark-extension
 Mark all files with a certain extension for use in later commands.  A @samp{.}
-is not automatically prepended to the string entered, you must type it
-explicitly.
-If invoked with prefix argument @kbd{C-u}, this command unmark files instead.
+is automatically prepended to the string entered when not present.
+If invoked with prefix argument @kbd{C-u}, this command unmarks files instead.
 If called with the @kbd{C-u C-u} prefix, asks for a character to use
 as the marker, and marks files with it.
 
 When called from Lisp, @var{extension} may also be a list of extensions
 and an optional argument @var{marker-char} specifies the marker used.
 
+@item dired-mark-suffix
+@findex dired-mark-suffix
+Mark all files with a certain suffix for use in later commands.  A @samp{.}
+is not automatically prepended to the string entered, you must type it
+explicitly.  This is different from @var{dired-mark-extension} which prepends
+a @samp{.} if not present.
+If invoked with prefix argument @kbd{C-u}, this command unmarks files instead.
+If called with the @kbd{C-u C-u} prefix, asks for a character to use
+as the marker, and marks files with it.
+
+When called from Lisp, @var{suffix} may also be a list of suffixes
+and an optional argument @var{marker-char} specifies the marker used.
+
 @item dired-flag-extension
 @findex dired-flag-extension
 Flag all files with a certain extension for deletion.  A @samp{.} is