pcomplete filename on unregistered commands

[Carlos Pita]

Hi all,

in shell-mode there are a number of c-a-p functions registered:

   comint-c-a-p-replace-by-expanded-history
   shell-environment-variable-completion
   shell-command-completion
   shell-c-a-p-replace-by-expanded-directory
   pcomplete-completions-at-point
   shell-filename-completion
   comint-filename-completion

Most of the time it is pcomplete-completions-at-point the one which
returns the completion candidates, and this works great as long as the
there is a pcomplete/xxx function registered for the command xxx.

Now, many usual commands like cp don't have a pcomplete handler so they
behave very poorly regarding completion, take for example:

     cp <TAB>

this doesn't give me any completion candidate! If I instead do:

     cp ./<TAB>

I then get filename completions (although not from pcomplete).

I find this behavior very inconvenient since often commands take
filenames as arguments and I would prefer filename completion to be
triggered by default for commands not known by pcomplete.

So what can I do? Is there a way to tell pcomplete to return filename
candidates by default? Or perhaps filename completion functions to
return candidates even upon an empty prefix?

Thank you in advance,
Carlos