Re: [PATCH] Fix a bug with XEmacs and bignum support.

[Reiner Steib <reinersteib+gmane@imap.cc>]

On Sun, Jan 11 2009, Aidan Kehoe wrote:

>  Ar an t-aonú lá déag de mí Eanair, scríobh Reiner Steib: 
>  > most-positive-fixnum is only available in Emacs 21 when requiring CL.
>
> Oops, you’re right, it was included it in C just after the release. Thanks
> for checking.
>
>  > But as CL is required (for ignore-errors), I think this change is
>  > fine, so I have installed it.
>
> It’s not, though, it needs to be something like the following in that case,
> since CL is available at compile time and not necessarily at runtime: 
>
> --- /tmp/aidan/nnfolder.el.orig	2009-01-11 15:50:39.000000000 +0000
> +++ /tmp/aidan/nnfolder.el	2009-01-11 15:50:16.000000000 +0000
> @@ -899,7 +899,9 @@
>  	      (active (or (cadr (assoc group nnfolder-group-alist))
>  			  (cons 1 0)))
>  	      (scantime (assoc group nnfolder-scantime-alist))
> -	      (minid (lsh -1 -1))
> +	      (minid (or (and (boundp 'most-positive-fixnum)
> +			      most-positive-fixnum)
> +			 134217727))

> An (eval-when-compile most-positive-fixnum) isn’t appropriate, because the
> compile-time constant could be from a 64-bit machine, which would silently
> overflow in the Lisp reader under GNU 

s/GNU/Emacs/, please. :-)

> on a 32-bit machine, and break the algorithm.

If you need to make sure that the correct runtime value is used, I
don't understand why you hard-code 134217727?  I would have
expected...

	      (minid (or (and (boundp 'most-positive-fixnum)
			      most-positive-fixnum)
			 (lsh -1 -1)))

What am I missing?

On a 64-bit machine, I get:

,----[ M-x ielm RET ]
| ELISP> (lsh -1 -1)
| 576460752303423487
| ELISP> (emacs-version)
| "GNU Emacs 21.3.1 (x86_64-suse-linux, X toolkit, Xaw3d scroll bars)\n of 2004-1\
| 0-05 on prokofjieff"
| ELISP> (when (require 'cl) most-positive-fixnum)
| 576460752303423487
`----

When I used this machine(s) some years ago, I always compiled Gnus,
AUCTeX, BBDB, emacs-w3m, etc on a 64-bit machine and ran the compiled
Lisp code on both, 64-bit and 32-bit machines
(/usr/local/share/emacs/site-lisp shared via NFS).

Bye, Reiner.
-- 
       ,,,
      (o o)
---ooO-(_)-Ooo---  |  PGP key available  |  http://rsteib.home.pages.de/