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Subject: Re: svn commit: r281721 - head/sys/sys
From: David Chisnall <theraven@FreeBSD.org>
In-Reply-To: <20150421020808.D10623@besplex.bde.org>
Date: Tue, 21 Apr 2015 08:42:41 +0100
Cc: John Baldwin <jhb@freebsd.org>, Justin Hibbits <jhibbits@freebsd.org>,
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References: <201504190033.t3J0XMDX041769@svn.freebsd.org>
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To: Bruce Evans <brde@optusnet.com.au>
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On 20 Apr 2015, at 17:19, Bruce Evans <brde@optusnet.com.au> wrote:
>=20
> Enums should never be used in ABIs, since their size can be anything
> large enough.

The rules for the size of enums also differ between C and C++, though =
clang (and, I think, gcc) support an attribute for specifying the enum =
type.

> They also cause namespace problems.  The whole enum declaration must
> be exposed in any header that uses an enum type.

Both C and C++ permit forward declarations of enums for use in function =
prototypes and so on, e.g.:

enum foo;
void
bar(enum foo);

David