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[Qemu-devel] [PATCH 3/4] compiler: expression version of QEMU_BUILD_BUG_
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From: |
Michael S. Tsirkin |
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Subject: |
[Qemu-devel] [PATCH 3/4] compiler: expression version of QEMU_BUILD_BUG_ON |
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Date: |
Wed, 18 Jan 2017 22:30:34 +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 | 2 ++
1 file changed, 2 insertions(+)
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 1a9eeb9..d2b05dd 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -88,6 +88,8 @@
#define QEMU_BUILD_BUG_ON(x) \
typedef char glue(qemu_build_bug_on__,__LINE__)[(x)?-1:1]
__attribute__((unused))
+#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(int[(x)?-1:1]) - sizeof(int))
+
#if defined __GNUC__
# if !QEMU_GNUC_PREREQ(4, 4)
/* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
--
MST