std::is_literal_type
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Defined in header
<type_traits> |
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template< class T >
struct is_literal_type; |
(since C++11) (deprecated in C++17) (removed in C++20) |
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std::is_literal_type is an UnaryTypeTrait.
(This type trait has been deprecated[1] and removed[2] as offering negligible value to generic code.)
If T satisfies all requirements of LiteralType, the base characteristic is std::true_type. For any other type, the base characteristic is std::false_type.
If std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void, the behavior is undefined.
The behavior of a program that adds specializations for std::is_literal_type or std::is_literal_type_v (since C++17) is undefined.
Template parameters
| T | - | a type to check |
Helper variable template
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template< class T >
inline constexpr bool is_literal_type_v = is_literal_type<T>::value; |
(since C++17) (deprecated) (removed in C++20) |
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Inherited from std::integral_constant
Member constants
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value
[static]
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true if T is a literal type, false otherwise(public static member constant) |
Member functions
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operator bool
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converts the object to bool, returns value (public member function) |
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operator()
(C++14)
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returns value (public member function) |
Member types
| Type | Definition |
value_type |
bool |
type |
std::integral_constant<bool, value> |
Notes
Only literal types may be used as parameters to or returned from constexpr functions. Only literal classes may have constexpr member functions.
Example
#include <type_traits> struct A { int m; }; static_assert(std::is_literal_type_v<A> == true); struct B { virtual ~B(); }; static_assert(std::is_literal_type_v<B> == 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 incompleteclass type with unknown bound |
the behavior is undefined in this case |
External links
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