I think it doesn't work in this case because If the strictest (largest) alignas on a declaration is weaker than the alignment it would have without any alignas

I think it doesn't work in this case because If the strictest (largest) alignas on a declaration is weaker than the alignment it would have without any alignas specifiers (that is, weaker than its natural alignment or weaker than alignas on another declaration of the same object or type), the program is ill-formed. Also, using alignas on pointer variable will probably specify alignment of the pointer itself, not the pointed object. I suppose you can create a wrapper class around int with alignas(32) and specify the pointer as pointing to that, but this is going to be nasty given that you can't derive from int and have to write all those operators by hand.