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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: grischka <grishka@gmx.de>
Cc: emacs-devel@gnu.org
Subject: Re: enum may be signed
Date: Sat, 01 May 2010 13:56:40 -0400	[thread overview]
Message-ID: <jwvmxwjo6gr.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <4BDC4D04.1040102@gmx.de> (grischka's message of "Sat, 01 May 2010 17:47:16 +0200")

> +  enum symbol_redirect redirect : 3;

> Note that this breaks with compilers where enums can be signed (e.g. MSVC),
> Because value 4 doesn't fit into 3 bits (signed), it is read as -4 and
> breaks related switch statements (e.g. data.c:set_internal)

Interesting.  I didn't know about that part of the C language.  Is it
possible to specify that this is an unsigned enum somehow?
I've tried "enum symbol_redirect redirect : 3;" but at least GCC didn't
like it.
Of course we can add one more bit (we have plenty of bits left there),
but I'd first like to know how this is usually handled, since it seems
to imply that MSVC always requires one extra bit to store enums.


        Stefan




  reply	other threads:[~2010-05-01 17:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-01 15:47 enum may be signed grischka
2010-05-01 17:56 ` Stefan Monnier [this message]
2010-05-01 18:37   ` Ken Raeburn
2010-05-01 18:51   ` grischka
2010-05-03 17:04   ` Tom Tromey

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