From nobody Fri Dec 19 20:33:09 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1490816913241859.9120230937953; Wed, 29 Mar 2017 12:48:33 -0700 (PDT) Received: from localhost ([::1]:60642 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ctJa4-0005pB-56 for importer@patchew.org; Wed, 29 Mar 2017 15:48:32 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44771) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ctJV6-0001xE-9P for qemu-devel@nongnu.org; Wed, 29 Mar 2017 15:43:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ctJV4-000089-W1 for qemu-devel@nongnu.org; Wed, 29 Mar 2017 15:43:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42332) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ctJV4-00007m-Oq for qemu-devel@nongnu.org; Wed, 29 Mar 2017 15:43:22 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C3AF27E9EE for ; Wed, 29 Mar 2017 19:43:21 +0000 (UTC) Received: from localhost (ovpn-116-7.gru2.redhat.com [10.97.116.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 51FA818996; Wed, 29 Mar 2017 19:43:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com C3AF27E9EE Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=ehabkost@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com C3AF27E9EE From: Eduardo Habkost To: qemu-devel@nongnu.org Date: Wed, 29 Mar 2017 16:41:42 -0300 Message-Id: <20170329194148.19015-4-ehabkost@redhat.com> In-Reply-To: <20170329194148.19015-1-ehabkost@redhat.com> References: <20170329194148.19015-1-ehabkost@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 29 Mar 2017 19:43:21 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [RFC v2 3/9] qom: QUALIFIED_CAST helper macro X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The new helper will help us write macros that keep const-ness of the input arguments, using C11's _Generic keyword. If _Generic is not supported by the compiler, QUALIFIED_CAST becomes a regular non-const cast. Signed-off-by: Eduardo Habkost --- include/qom/object.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/include/qom/object.h b/include/qom/object.h index cd0f412ce9..6829735f99 100644 --- a/include/qom/object.h +++ b/include/qom/object.h @@ -474,6 +474,52 @@ struct TypeInfo ((Object *)(obj)) =20 /** + * REFERENCED_TYPE: + * @t: a pointer type + * + * Returns the referenced type of a pointer type. + */ +#define REFERENCED_TYPE(t) \ + typeof(*((t)0)) + +/** + * QUALIFIED_CAST: + * @orig_type: Original type (a pointer type) + * @type: A pointer type to which an expression will be cast to. + * + * Helper to cast an expression to another pointer type while + * keeping the 'const' qualifier if it was present in + * @orig_type. If the compiler doesn't support _Generic, it + * becomes a regular non-const cast. + * + * Usage examples: + * QUALIFIED_CAST(AType *, BType *)(expr) + * equivalent to (BType *)(expr) + * + * QUALIFIED_CAST(const AType *, BType *)(expr) + * If supported, equivalent to: (const BType *)(expr) + * otherwise, equivalent to: (BType *)(expr) + * + * AType *a; + * QUALIFIED_CAST(typeof(a), BType *)(b) + * equivalent to (BType *)(b) + * + * const AType *a; + * QUALIFIED_CAST(typeof(a), BType *)(b) + * If supported, equivalent to: (const BType *)(expr) + * otherwise, equivalent to: (BType *)(expr) + */ +#ifdef HAVE_C11_GENERIC +#define QUALIFIED_CAST(orig_type, type) \ + (typeof(_Generic((const REFERENCED_TYPE(orig_type) *)0, \ + orig_type: (const type)(0), \ + default: (type)(0)))) +#else +#define QUALIFIED_CAST(orig_type, type) \ + (type) +#endif + +/** * OBJECT_CLASS: * @class: A derivative of #ObjectClass. * --=20 2.11.0.259.g40922b1