Patch: new function process-file (call-process with file handlers)

[Kai Grossjohann]

VC includes a function vc-do-command which invokes a version control
command.  This function uses call-process and therefore only works for
local files.

Tramp includes tramp-vc-do-command, a version of vc-do-command which
invokes shell-command instead of call-process and therefore works for
remote files, too.  Tramp then advises vc-do-command to invoke
tramp-vc-do-command on Tramp files.

Some years ago, we discussed replacing this kludge with an enhanced
call-process that also groks file handlers.  Richard didn't want to
change the behavior of call-process and proposed to provide a new
function process-file instead.

The attached patch provides the new function process-file, adds Tramp
support for this new function, and changes VC to invoke process-file
instead of call-process.  The patch also removes the ugly advice from
Tramp if process-file is available.

Beware: the Tramp implementation for process-file is far from
complete.  It appears to be sufficient for vc-do-command.  I intend to
improve the implementation somewhat if the general approach is
agreeable.

What do people think?

Kai

#!/bin/sh
what="$1"

case x$what in
        x[cm]*)
                make maintainer-clean
                autoconf257
                ./configure --prefix=$HOME/sw/emacs --with-gtk
                make bootstrap
                ;;
        xi*)
                rm -rf $HOME/sw/SAV.emacs
                mv $HOME/sw/emacs $HOME/sw/SAV.emacs
                make install tags
                ( cd $HOME/sw/emacs/share/emacs;
                  mv site-lisp site-lisp.SAV;
                  ln -s /usr/local/share/emacs/site-lisp )
                ;;
        *)
                echo "Usage: $0 <what>"
                echo "<what> can be 'make' or 'install'"
                exit 2
                ;;
esac