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[Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_B
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON |
Date: |
Wed, 18 Jan 2017 22:55:52 +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 2882470..f4cf13b 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -89,6 +89,8 @@
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
[Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Markus Armbruster, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Paolo Bonzini, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Markus Armbruster, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Eric Blake, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/19
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Markus Armbruster, 2017/01/20
- Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/20
Re: [Qemu-devel] [PATCH v2 3/4] compiler: expression version of QEMU_BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/19
[Qemu-devel] [PATCH v2 4/4] ARRAY_SIZE: check that argument is an array, Michael S. Tsirkin, 2017/01/18