From f291887e8eef5d37d31484638f6e62401b4b99a2 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 19 Jan 2017 22:56:14 +0200 Subject: [PATCH] compiler: rework BUG_ON using a struct 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 Reviewed-by: Eric Blake Reviewed-by: Markus Armbruster --- include/qemu/compiler.h | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 77b9ce3979..057639af43 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -85,10 +85,14 @@ #define typeof_field(type, field) typeof(((type *)0)->field) #define type_check(t1,t2) ((t1*)0 - (t2*)0) +#define QEMU_BUILD_BUG_ON_STRUCT(x) \ + struct { \ + int:(x) ? -1 : 1; \ + } + #ifdef __COUNTER__ -#define QEMU_BUILD_BUG_ON(x) \ - typedef char glue(qemu_build_bug_on__, __COUNTER__)[(x) ? -1 : 1] \ - __attribute__((unused)) +#define QEMU_BUILD_BUG_ON(x) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \ + glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused)) #else #define QEMU_BUILD_BUG_ON(x) #endif