On 03/25/2015 11:49 AM, Jonathan Wakely wrote: > On 25/03/15 11:36 -0700, Richard Henderson wrote: >> On 03/25/2015 09:22 AM, Jonathan Wakely wrote: > On 25/03/15 11:39 -0700, Richard Henderson wrote: >> On 03/25/2015 09:22 AM, Jonathan Wakely wrote: >>> +static_assert( alignof(std::atomic<twoints>) > alignof(int), >>> + "std::atomic not suitably aligned" ); >> >> This is only true if int64_t has alignment larger than int32_t, >> which is unfortunately not always the case. > > Huh, didn't realise that. I could change the tests to check it's > alignof(std::int64_t) as the next assertion does, but is it safe to > assume that struct twoints { int a; int b; } is exactly 64 bits > everywhere?
Certainly not. But if you're going to explicitly use int64_t elsewhere, you might as well explicitly use int32_t as well. Then I believe you can reasonably assert alignof(twoint32) == alignof(int64_t) r~