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bug#6490: 24.0.50; src/lread.c: old style backquote bug?
From: |
Stefan Monnier |
Subject: |
bug#6490: 24.0.50; src/lread.c: old style backquote bug? |
Date: |
Sun, 04 Jul 2010 23:50:26 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) |
>> > Attached patch for Emacs fixes this error.
>> I'm glad the patch fixes things for you, since this patch indeed looks
>> perfectly harmless, but I'm a bit puzzled because it doesn't just look
>> harmless: it looks to me like the patch does change anything to the way
>> the code works. So could you explain to me how&why the patch fixes
>> the problem? I'm probably just overlooking some "obvious" detail,
> The changes committed in rev:100605 reassigns the next character to
> the variable `c'. When the next character is SPC (32, #o40, #x20),
> old style backquote is detected.
> if (first_in_list && (c = READCHAR, UNREAD (c), c == ' '))
> {
> Vold_style_backquotes = Qt;
> goto default_label;
> }
> But backquote handling is skipped because `c' is SPC.
> default_label:
> if (c <= 040) goto retry;
> ... old style backquote handling ...
> My patch avoids reassignment of `c' not to skip old style
> backquote handling.
Thanks, that makes perfect sense now. I've installed it now.
> To keep more compatibility with released Emacs, it is preferable to
> allow a character such as \r or \n after the old style backquote.
I haven't seen any such situation yet, and since old-style backquotes are
on the way out (effectively obsolete since something like Emacs-20, and
officially obsolete since Emacs-22.1), I'll wait to see actual cases
before adding such exceptions,
Stefan