(thing-at-point 'filename) is broken

[Markus Rost]

(thing-at-point 'filename) is broken.  I noticed that when using
x-compilation-parse-errors.  I think the reason is the change from

(defvar thing-at-point-file-name-chars "~/A-Za-z0-9---_.${}#%,:"
    "Characters allowable in filenames.")

to 

(defvar thing-at-point-file-name-chars "-~/[:alnum:]_.${}#%,:"
  "Characters allowable in filenames.")

in thingatpt.el.  Example:  Evaluate the forms

(skip-chars-forward "~/A-Za-z0-9---_.${}#%,:").lumacs
(skip-chars-forward "-~/[:alnum:]_.${}#%,:").lumacs

The first one moves point behind ".lumacs", the second one fails to do
so.

It seems the [:alnum:] construction is the culprit.

Is there a way to use constructs like :alnum: with skip-chars-forward?
If not, it might be a good idea to implement this. ?