On Tue, Nov 3, 2015 at 5:53 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> You mean, ref doesn't know that some strings are file names and some
> aren't?  Then how does it know they are strings and not symbols or
> something else?  This is Lisp, not C.

I meant a general-purpose comparison function. You cannot look at a struct
and know which strings are intended as filenames and which ones do not. But
xref-specific comparison functions obviously would.