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[Qemu-devel] [PULL v2 03/18] compiler: rework BUG_ON using a struct
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PULL v2 03/18] compiler: rework BUG_ON using a struct |
Date: |
Thu, 26 Jan 2017 18:15:13 +0200 |
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 <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Markus Armbruster <address@hidden>
---
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
- [Qemu-devel] [PULL v2 00/18] virtio, vhost, pci: fixes, features, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 02/18] qxl: switch to constants within BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 01/18] compiler: drop ; after BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 03/18] compiler: rework BUG_ON using a struct,
Michael S. Tsirkin <=
- [Qemu-devel] [PULL v2 04/18] compiler: expression version of QEMU_BUILD_BUG_ON, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 05/18] ARRAY_SIZE: check that argument is an array, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 06/18] pci: mark ROMs read-only, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 07/18] intel_iommu: fix and simplify size calculation in process_device_iotlb_desc(), Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 08/18] hw/pcie: Introduce a base class for PCI Express Root Ports, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 09/18] hw/ioh3420: derive from PCI Express Root Port base class, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 11/18] hw/i386: check if nvdimm is enabled before plugging, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 12/18] msix: Follow CODING_STYLE, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 10/18] hw/pcie: Introduce Generic PCI Express Root Port, Michael S. Tsirkin, 2017/01/26
- [Qemu-devel] [PULL v2 13/18] hcd-xhci: check & correct param before using it, Michael S. Tsirkin, 2017/01/26