| Defined in header <type_traits> | ||
|---|---|---|
| template< class T > struct is_literal_type; | (since C++11) (deprecated in C++17) (removed in C++20) | 
(This type trait has been deprecated[1] and removed[2] as offering negligible value to generic code.).
If T satisfies all requirements of LiteralType, provides the member constant value equal true. For any other type, value is false.
The behavior is undefined if std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void.
The behavior of a program that adds specializations for is_literal_type or is_literal_type_v (since C++17) is undefined.
| T | - | a type to check | 
| template< class T > inline constexpr bool is_literal_type_v = is_literal_type<T>::value; | (since C++17) (deprecated) (removed in C++20) | 
| value [static] | trueifTis a literal type,falseotherwise(public static member constant) | 
| operator bool | converts the object to bool, returns value(public member function) | 
| operator() (C++14) | returns value(public member function) | 
| Type | Definition | 
|---|---|
| value_type | bool | 
| type | std::integral_constant<bool, value> | 
Only literal types may be used as parameters to or returned from constexpr functions. Only literal classes may have constexpr member functions.
#include <iostream>
#include <type_traits>
 
struct A
{
    int m;
};
 
struct B
{
    virtual ~B();
};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_literal_type<A>::value << '\n';
    std::cout << std::is_literal_type<B>::value << '\n';
}Output:
true false
| 
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    https://en.cppreference.com/w/cpp/types/is_literal_type