func_convert_file_cygwin_to_w32 woes

[Dan McMahill]

I am trying to build a program under cygwin but using the mingw tool
chain in a fake cross build way.  In my configure environment, I have:

 export lt_cv_to_tool_file_cmd=func_convert_file_cygwin_to_w32

as suggested by the libtool manual.  I'm using libtool 2.4.

Everything goes smoothly until install time when libtool calls ranlib
(the mingw one) on an absolute path and of course the cygwin absolute
path doesn't make sense to the mingw ranlib.  I thought that's what the
func_convert... bit was for.

A full understanding of libtool internals escapes me.  Is there
something else I should be doing or can anyone suggest good ways to
troubleshoot this?

Thanks
-Dan