bug#22982: 25.0.92; Forms Mode seems to fail to open data file

[John Mastro <john.b.mastro@gmail.com>]

N. Jackson <nljlistbox2@gmail.com> wrote:
> I get the error "Wrong-type-argument: stringp, nil" when I try to start
> Forms Mode with
>
>     M-x forms-find-file RET ~/Documents/test-forms.el RET
>
> The backtrace is:
>
>     Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>       expand-file-name(nil)
>       find-file-noselect(nil)
>       forms-mode(t)
>       forms-find-file("~/Documents/test-forms.el")
>       funcall-interactively(forms-find-file "~/Documents/test-forms.el")
>       call-interactively(forms-find-file record nil)
>       command-execute(forms-find-file record)
>       execute-extended-command(nil "forms-find-file" nil)
>       funcall-interactively(execute-extended-command nil "forms-find-file" nil)
>       call-interactively(execute-extended-command nil nil)
>       command-execute(execute-extended-command)

Confirmed on Emacs 25.

This seems to be caused by the call ‘(set-visited-file-name nil)’ in
‘forms-mode’. Before that call, ‘forms-file’ is "/etc/passwd";
afterward, it is nil.

-- 
john