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[Qemu-devel] [PATCH v3 3/4] compiler: expression version of QEMU_BUILD_B
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PATCH v3 3/4] compiler: expression version of QEMU_BUILD_BUG_ON |
Date: |
Thu, 19 Jan 2017 23:07:32 +0200 |
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 <address@hidden>
---
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
Re: [Qemu-devel] [PATCH v3 0/4] ARRAY_SIZE fixups, Markus Armbruster, 2017/01/20
Re: [Qemu-devel] [PATCH v3 0/4] ARRAY_SIZE fixups, no-reply, 2017/01/20
Re: [Qemu-devel] [PATCH v3 0/4] ARRAY_SIZE fixups, no-reply, 2017/01/20