bug#40573: 27.0.90; flymake-mode broken in scratch buffer

[Eli Zaretskii]

> From: João Távora <joaotavora@gmail.com>
> Date: Tue, 14 Apr 2020 09:48:43 +0100
> Cc: Juri Linkov <juri@linkov.net>, 40573@debbugs.gnu.org, 
>       Stefan Monnier <monnier@iro.umontreal.ca>, Dmitry Gutov 
> <dgutov@yandex.ru>
> 
> > How would you propose to identify these files for turning on this
> > special mode?  They don't seem to have a clear-cut set of extensions
> > and/or file names.
> 
> One thing I don't understand is why is this important at all.

It is only important if we want this new mode to be turned on
automatically in such files.  If we want these files to be visited in
Fundamental mode, or some other random mode due to their extensions,
then this is indeed not important.  But then .dir-locals.el, for
example, will be visited in emacs-lisp-mode, something I thought we
wanted to prevent?

> Examples such as recentf, tramp, and ido files had already been given.
> Again please don't base any implementation on those "details": they are
> just an example.  The universe of lisp data files is much greater than
> that.

We must have some body of common traits of these files to program a
mode that is suitable for them.