Re: diff: bad treatment of symlinks

[Paul Eggert]

It's long been on my list of things to do to give diff
an option to either follow or not follow symlinks, like
the -H, -L, -P options of many other applications, and
contributions along that line would be welcome.  But
the default behavior of "diff FILE1 FILE2" should remain
unchanged: it should follow symlinks, as many programs
depend on this behavior.  Also, POSIX requires it.

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/diff.html