From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35764) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cUJvm-00076w-Bo for qemu-devel@nongnu.org; Thu, 19 Jan 2017 16:07:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cUJvl-00053M-Fr for qemu-devel@nongnu.org; Thu, 19 Jan 2017 16:07:38 -0500 Received: from mail.kernel.org ([198.145.29.136]:56240) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cUJvl-00051l-9I for qemu-devel@nongnu.org; Thu, 19 Jan 2017 16:07:37 -0500 Date: Thu, 19 Jan 2017 23:07:32 +0200 From: "Michael S. Tsirkin" Message-ID: <1484859998-25074-4-git-send-email-mst@redhat.com> References: <1484859998-25074-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1484859998-25074-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH v3 3/4] compiler: expression version of QEMU_BUILD_BUG_ON List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Paolo Bonzini , Eric Blake , Richard Henderson QEMU_BUILD_BUG_ON uses a typedef in order to be safe to use outside functions, but sometimes it's useful to have a version that can be used within an expression. Following what Linux does, introduce QEMU_BUILD_BUG_ON_ZERO that return zero after checking condition at build time. Signed-off-by: Michael S. Tsirkin --- include/qemu/compiler.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index c6f673e..8271eab 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -92,6 +92,9 @@ #define QEMU_BUILD_BUG_ON(x) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ glue(qemu_build_bug_on__, __LINE__) __attribute__((unused)) +#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \ + sizeof(QEMU_BUILD_BUG_ON_STRUCT(x))) + #if defined __GNUC__ # if !QEMU_GNUC_PREREQ(4, 4) /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */ -- MST