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std::is_trivially_copyable(3) C++ Standard Libarystd::is_trivially_copyable(3)

NAME
       std::is_trivially_copyable - std::is_trivially_copyable

Synopsis
	  Defined in header <type_traits>
	  template< class T >		   (since C++11)
	  struct is_trivially_copyable;

	  If  T	 is  a	trivially  copyable type, provides the member constant
       value equal to true.
	  For any other	type, value is false.

	  The behavior is undefined if std::remove_all_extents_t<T> is an  in-
       complete	type and
	  not (possibly	cv-qualified) void.

	  The  behavior	 of  a	program	that adds specializations for is_triv-
       ially_copyable
	  or is_trivially_copyable_v
	  (since C++17)	is undefined.

Template parameters
	  T - a	type to	check

	 Helper	variable template

	  template< class T >
	  inline      constexpr	     bool      is_trivially_copyable_v	     =
       (since C++17)
	  is_trivially_copyable<T>::value;

       Inherited from std::integral_constant

Member constants
	  value	   true	if T is	a trivially copyable type , false otherwise
	  [static] (public static member constant)

Member functions
	  operator bool	converts the object to bool, returns value
			(public	member function)
	  operator()	returns	value
	  (C++14)	(public	member function)

Member types
	  Type	     Definition
	  value_type bool
	  type	     std::integral_constant<bool, value>

Notes
	  Objects  of  trivially-copyable types	that are not potentially-over-
       lapping subobjects
	  are the only C++ objects that	may be safely copied with  std::memcpy
       or serialized
	  to/from    binary    files	with   std::ofstream::write()/std::if-
       stream::read().

Example
       // Run this code

	#include <iostream>
	#include <type_traits>

	struct A
	{
	    int	m;
	};

	struct B
	{
	    B(B	const&)	{}
	};

	struct C
	{
	    virtual void foo();
	};

	struct D
	{
	    int	m;

	    D(D	const&)	= default; // -> trivially copyable
	    D(int x): m(x+1) {}
	};

	int main()
	{
	    std::cout << std::boolalpha;
	    std::cout << std::is_trivially_copyable<A>::value << '\n';
	    std::cout << std::is_trivially_copyable<B>::value << '\n';
	    std::cout << std::is_trivially_copyable<C>::value << '\n';
	    std::cout << std::is_trivially_copyable<D>::value << '\n';
	}

Output:
	true
	false
	false
	true

See also
	  is_trivial checks if a type is trivial
	  (C++11)    (class template)

http://cppreference.com		  2022.07.31	 std::is_trivially_copyable(3)

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