On 25.07.2024 16:54, Roger Pau Monné wrote: > On Thu, Jul 25, 2024 at 03:18:29PM +0200, Jan Beulich wrote: >> On 25.07.2024 12:56, Roger Pau Monne wrote: >>> --- a/xen/arch/x86/include/asm/alternative.h >>> +++ b/xen/arch/x86/include/asm/alternative.h >>> @@ -184,11 +184,11 @@ extern void alternative_branches(void); >>> * https://github.com/llvm/llvm-project/issues/82598 >>> */ >>> #define ALT_CALL_ARG(arg, n) \ >>> - register union { \ >>> - typeof(arg) e[sizeof(long) / sizeof(arg)]; \ >>> - unsigned long r; \ >>> + register struct { \ >>> + typeof(arg) e; \ >>> + char pad[sizeof(void *) - sizeof(arg)]; \ >> >> One thing that occurred to me only after our discussion, and I then forgot >> to mention this before you would send a patch: What if sizeof(void *) == >> sizeof(arg)? Zero-sized arrays are explicitly something we're trying to >> get rid of. > > I wondered about this, but I though it was only [] that we were trying > to get rid of, not [0].
Sadly (here) it's actually the other way around, aiui. Jan
