On Fri, 28 Jul 2023 at 15:28, Thomas Huth <th...@redhat.com> wrote: > > Clang on Windows does not seem to know the "gcc_struct" attribute > and emits a warning when we try to use it. Add an additional check > here with __has_attribute() to avoid this problem. > > Signed-off-by: Thomas Huth <th...@redhat.com> > --- > include/qemu/compiler.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h > index a309f90c76..5065b4447c 100644 > --- a/include/qemu/compiler.h > +++ b/include/qemu/compiler.h > @@ -22,7 +22,7 @@ > #define QEMU_EXTERN_C extern > #endif > > -#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) > +#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) && > !defined(__clang__) > # define QEMU_PACKED __attribute__((gcc_struct, packed)) > #else > # define QEMU_PACKED __attribute__((packed))
I'm not sure about this. The idea of QEMU_PACKED is that it's supposed to give you the same struct layout regardless of compiler. With this change it no longer does that, and there's no compile-time guard against using something in a packed struct that has a different layout on Windows clang vs everything else. If it was OK to use plain attribute(packed) we wouldn't need the ifdef at all because we could use it on GCC too. thanks -- PMM
