bug#40407: [PATCH] slow ENCODE_FILE and DECODE_FILE

[handa]

In article <83wo6sr0s2.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:

> > > I don't think 'charset' is the right type for this encoding (any
> > > reason why you've chosen it?), but I will let Handa-san comment.
> > 
> > We could use 'raw-text' as well but that implies that any byte value could 
> > be part of an utf-7[-imap] text, which is incorrect.
> > In fact, utf-7-imap only uses codes 0x20-0x7e (utf-7 is allowed to use a 
> > few C0 controls too, as mentioned).

I don't remember why utf-7 has coding type utf-8.  As main
decoding/encoding routines of utf-7 are by Lisp (in utf-7.el which was
contributed not by me), perhaps, any other ASCII transparent types was
ok.  It seems that we should introduce a new type for such a coding
system.

> > Arguably the heuristics of define-coding-system-internal are somewhat 
> > inscrutable. There seems to be leaks between layers -- ascii-compatible-p 
> > is an end-to-end property and cannot really be set the way it is by that 
> > function. But since it is, fixing it afterwards should be the correct way.

> I prefer to wait for Handa-san's response, and meanwhile install the
> least disruptive change, which just fixes the one aspect that got
> broken.  Call me a coward, if you wish.

I think Mattias' patch is good.

---
K. Handa
handa@gnu.org