std::out_ptr_t<Smart,Pointer,Args...>::operator Pointer*, std::out_ptr_t<Smart,Pointer,Args...>::operator void**

operator Pointer*() const noexcept;
(1) (since C++23)
operator void**() const noexcept;
(2) (since C++23)

Exposes the address of a Pointer or void* object to a foreign function which will generally re-initialize it.

1) Converts *this to the address of stored Pointer object.
2) Converts *this to the address of a void* object. This conversion function participates in overload resolution only if Pointer is not same as void*, and the program is ill-formed if Pointer is not a pointer type.
The initial value of the void* object is equal the value of the stored Pointer object converted to void*, and any modification to it affects the Pointer value used in the destructor. Accessing the void* object outside the lifetime of *this has undefined behavior.

Once one of these two conversion functions has been called on an out_ptr_t object, the other shall not be called on it, otherwise, the behavior is undefined.



Return value

1) The address of stored Pointer object.
2) The address of the void* object that satisfies aforementioned requirements.


If the object pointed by the return value has not been rewritten, it is equal to nullptr.

On common implementations, the object representation of every Pointer that is a pointer type is compatible with that of void*, and therefore these implementations typically store the void* object within the storage for the Pointer object, no additional storage needed:

  • If the implementation enables type-based alias analysis (which relies on the strict aliasing rule), a properly aligned std::byte[sizeof(void*)] member subobject may be used, and both conversion functions return the address of objects implicitly created within the array.
  • Otherwise, a Pointer member subobject may be used for both conversion functions, and (2) may directly returns its address reinterpret_cast to void**.

If Pointer is a pointer type whose object representation is incompatible with that of void*, an additional bool flag may be needed for recording whether (1) (or (2)) has been called.


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