Item 52: Write Placement delete If You Write Placement new

Any operator new overload that accepts no just std::size_t as parameter is called a “placement new” (yeah, the name “placement new” is overloaded, too). You must define a paired overloaded version of operator delete, or you are in serious trouble, because when compiler can’t find one, it just gives up deleting the memory when a constructor fails (leak!).

Also, since it’s just an overloaded member function, it hides all other overloaded functions in the global scope (i.e., operator new defined in standard library). This is usually a problem.

(By the way, the “nothrow” form of operator new is a placement new, too. It’s one of the three operator new defined in the standard library, with the other two be the normal new and the “real” placement new.)