bug#12989: 24.3.50; buffer-file-type is not buffer-local

[Eli Zaretskii]

> Date: Sun, 25 Nov 2012 12:58:01 +0900
> From: Kazuhiro Ito <kzhr@d1.dion.ne.jp>
> 
> When I evaluate below code, Emacs-23 and trunk on Windows return the
> different results.

The difference is intentional.  buffer-file-type was removed from the
C code, with the goal of removing it entirely, but there are still
traces of it in Lisp.  I'm surprised you only noticed this now.

> And, if buffer-file-type is set to t, many file coding system
> detections fail.  Docstring says that buffer-file-type autmatically
> becomes buffer-local, but that is not true on trunk.

Just don't use that variable.  You don't need it.  If you want to
force Emacs to treat certain files as binary, bind
coding-system-for-read to 'binary or modify file-coding-system-alist
accordingly.

I will work on removing the variable entirely from the sources, though
I guess it's too late for 24.3.  So I will do it on the trunk.

> Additionally, there is typo in docsstring of buffer-file-type.
> 
> > This variable is meaningful on MS-DOG and Windows NT.
>                                  ~~~~~~

It's not a typo.