std::is_trivial

Defined in header `<type_traits>`
template< class T > struct is_trivial;		(since C++11) (deprecated in C++26)

std::is_trivial is a UnaryTypeTrait.

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

If std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void, the behavior is undefined.

If the program adds specializations for std::is_trivial or std::is_trivial_v, the behavior is undefined.

Template parameters

a type to check

Helper variable template

template< class T >
constexpr bool is_trivial_v = is_trivial<T>::value;

(since C++17)
(deprecated in C++26)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is a trivial type, false otherwise
(public static member constant)

Member functions

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

Member types

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

Example

#include <type_traits>

struct A { int m; };
static_assert(std::is_trivial_v<A> == true);

struct B { B() {} };
static_assert(std::is_trivial_v<B> == false);

// The following class shows why std::is_trivial(_v) may be a pitfall.
class C
{
private:
    C() = default;
};

static_assert(std::is_trivial_v<C> == true);
static_assert(std::is_trivially_default_constructible_v<C> == false);

int main() {}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2015	C++11	`T` could be an array of incomplete class type with unknown bound	the behavior is undefined in this case

is_trivially_copyable (C++11)	checks if a type is trivially copyable (class template)
is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11)	checks if a type has a default constructor (class template)