Re: EOL: unix/dos/mac

[Eli Zaretskii <eliz@gnu.org>]

> From: "Stephen J. Turnbull" <stephen@xemacs.org>
> Date: Tue, 26 Mar 2013 10:42:38 +0900
> Cc: Per Starbäck <per.starback@gmail.com>, emacs-devel@gnu.org
> 
> Stefan Monnier writes:
> 
>  > BTW, in this same area, it would be good to detect and indicate
>  > prominently "Unix with some CRLFs", also known as "mixed-line-ending",
>  > which is often misunderstood as "my Emacs fails to recognize my CRLF
>  > file".
> 
> Unicode doesn't care, you know: it considers all ASCII line breaks and
> terminators to be the same thing (NEW LINE FUNCTION).  I haven't read
> that part of the standard in a long time, but IIRC, although many
> people interpolate "according to platform", Unicode doesn't care about
> that, it just says "all of these sequences when encountered in text
> purporting to conform to this standard should be treated in the same
> way."  Emacsen should do the same.

That would require Emacs to store all the possible EOL sequences in
the buffer, and treat them all identically.  That's doable, but is a
non-trivial job; volunteers are welcome.

> The question then is how to deal with file comparison.  We'd like to
> avoid creating spurious diffs based on "fixing" random different line
> endings

If Emacs is to support different EOL formats in the same file, it
should not convert them at all.  Anything else _will_ introduce
spurious modifications, and could even corrupt some files, if the
exact EOL sequence here or there matters.

> I guess one could attach a text property to newlines differing from
> the file's autodetected EOL convention.

Not sure how a text property should help here.

> I've also considered switching the internal representation of newline
> to U+2028 LINE SEPARATOR

What good would that be?