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std::is_poi...e_with_class(3)  C++ Standard Libary std::is_poi...e_with_class(3)

NAME
     std::is_pointer_interconvertible_with_class - std::is_pointer_interconvert-
     ible_with_class

Synopsis
	Defined in header <type_traits>
	template< class S, class M >
	constexpr  bool  is_pointer_interconvertible_with_class(  M  S::*  mp  )
     (since C++20)
	noexcept;

	Given an object s of type S, determines whether s.*mp refers to a subob-
     ject of s and
	s is pointer-interconvertible with its subobject s.*mp. The  program  is
     ill-formed if
	S is not a complete type.

	If  S  is not a StandardLayoutType, or M is not an object type, or mp is
     equal to
	nullptr, the result is always false.

Parameters
	mp - a pointer-to-member to detect

Return value
	true if s.*mp refers a subobject of s and s is	pointer-interconvertible
     with its
	subobject s.*mp, otherwise false, where s is an object of type S.

Notes
	The  type  of a pointer-to-member expression &S::m is not always M S::*,
     where m is of
	type M, because m may be a member inherited from a base class of S.  The
     template
	arguments  can be specified in order to avoid potentially surprising re-
     sults.

	If there is a value mp of type M S::* such that
	std::is_pointer_interconvertible_with_class(mp) == true, then
	reinterpret_cast<M&>(s) has well-defined result and it refers  the  same
     subobject as
	s.*mp, where s is a valid lvalue of type S.

	On common platforms, the bit pattern of mp is all zero if
	std::is_pointer_interconvertible_with_class(mp) == true.

	      Feature-test	   macro		    Value	     Std
     Feature
							   Pointer-interconvert-
     ibility traits: __cpp_lib_is_pointer_interconvertible 201907L  (C++20)    *
     std::is_pointer_interconvertible_base_of,
							     *
     std::is_pointer_interconvertible_with_class

Example
     // Run this code

      #include <type_traits>

      struct Foo { int x; };
      struct Bar { int y; };

      struct Baz : Foo, Bar {}; // not standard-layout

      static_assert( not std::is_same_v<decltype(&Baz::x), int Baz::*> );
      static_assert( std::is_pointer_interconvertible_with_class(&Baz::x) );
      static_assert(	 not	std::is_pointer_interconvertible_with_class<Baz,
     int>(&Baz::x) );

      int main() { }

See also
	is_standard_layout	 checks if a type is a standard-layout type
	(C++11) 		 (class template)
	is_member_object_pointer checks if a type is a pointer to  a  non-static
     member object
	(C++11) 		 (class template)

http://cppreference.com 	   2024.06.10	   std::is_poi...e_with_class(3)
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