From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40730) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cW9hP-0007q6-IK for qemu-devel@nongnu.org; Tue, 24 Jan 2017 17:36:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cW9hO-0005p3-Sv for qemu-devel@nongnu.org; Tue, 24 Jan 2017 17:36:23 -0500 Received: from mail.kernel.org ([198.145.29.136]:37134) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cW9hO-0005oo-Mn for qemu-devel@nongnu.org; Tue, 24 Jan 2017 17:36:22 -0500 Date: Wed, 25 Jan 2017 00:36:18 +0200 From: "Michael S. Tsirkin" Message-ID: <1485297322-10595-3-git-send-email-mst@redhat.com> References: <1485297322-10595-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1485297322-10595-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PULL 02/16] compiler: rework BUG_ON using a struct List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Eric Blake , Markus Armbruster , Paolo Bonzini There are theoretical concerns that some compilers might not trigger build failures on attempts to define an array of size (x ? -1 : 1) where x is a variable and make it a variable sized array instead. Let rewrite using a struct with a negative bit field size instead as there are no dynamic bit field sizes. This is similar to what Linux does. Signed-off-by: Michael S. Tsirkin Reviewed-by: Eric Blake Reviewed-by: Markus Armbruster --- include/qemu/compiler.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 7512082..1da500e 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -85,9 +85,12 @@ #define typeof_field(type, field) typeof(((type *)0)->field) #define type_check(t1,t2) ((t1*)0 - (t2*)0) -#define QEMU_BUILD_BUG_ON(x) \ - typedef char glue(qemu_build_bug_on__, __LINE__)[(x) ? -1 : 1] \ - __attribute__((unused)) +#define QEMU_BUILD_BUG_ON_STRUCT(x) \ + struct { \ + int:(x) ? -1 : 1; \ + } +#define QEMU_BUILD_BUG_ON(x) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ + glue(qemu_build_bug_on__, __LINE__) __attribute__((unused)) #if defined __GNUC__ # if !QEMU_GNUC_PREREQ(4, 4) -- MST