Mixing operator new[] and placement new with ordinary delete[]

Question

Just out of curiosity, is the following legal?

X* p = static_cast(operator new[](3 * sizeof(X)));
new(p + 0) X();
new(p + 1) X();
new(p + 2) X();

         


        

Answer 1

I think that cannot be legal. Because that implies these equations:

new-expression    = allocation-function  +  constructor
delete-expression = destructor  +  deallocation-function

Nothing more, nothing less. But the Standard does not say exactly that, as far as I know. It might be possible that new-expression does more than allocation-function + constructor together do. That is, the actual equations could be this, and the Standard doesn't forbid it explicitly anywhere:

new-expression    = allocation-function  +  constructor   +  some-other-work
delete-expression = destructor  +  deallocation-function  +  some-other-work