These functions are reserved; a C++ program may not define functions that displace the versions in the C++ standard library ([constraints]). The provisions of [basic.stc.dynamic] do not apply to these reserved placement forms of operator new and operator delete.
void* operator new(std::size_t size, void* ptr) noexcept;
[ Example: This can be useful for constructing an object at a known address:
void* place = operator new(sizeof(Something)); Something* p = new (place) Something();
— end example ]
void* operator new[](std::size_t size, void* ptr) noexcept;
void operator delete(void* ptr, void*) noexcept;
Requires: If an implementation has strict pointer safety then ptr shall be a safely-derived pointer.
Remarks: Default function called when any part of the initialization in a placement new-expression that invokes the library's non-array placement operator new terminates by throwing an exception ([expr.new]).
void operator delete[](void* ptr, void*) noexcept;
Requires: If an implementation has strict pointer safety then ptr shall be a safely-derived pointer.
Remarks: Default function called when any part of the initialization in a placement new-expression that invokes the library's array placement operator new terminates by throwing an exception ([expr.new]).