If you try to run clone-buffer on a file-visiting buffer, it won't
happen, and you get the error message "Cannot clone a file-visiting
buffer."
I think I understand why -- if you clone a file-visiting buffer, both
buffers are visiting the same file -- and this is more a situation for
an indirect buffer. Is this correct?
But what about situations where you want the entire text of the file-
visiting buffer, the same major mode, but not have it be visiting a
file? Is there any easier way to do this other than copying the entire
buffer and starting from scratch?