From d757573e69f2ef58a4a7b41f6c55d65fa1e1c5c2 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 18 Jan 2017 22:05:15 +0200 Subject: [PATCH] compiler: expression version of QEMU_BUILD_BUG_ON 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 Reviewed-by: Eric Blake Reviewed-by: Markus Armbruster --- include/qemu/compiler.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 057639af43..e0ce9ffb28 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -97,6 +97,9 @@ #define QEMU_BUILD_BUG_ON(x) #endif +#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. */