std::type_identity (3) Linux Manual Page

std::type_identity – std::type_identity

Synopsis

Defined in header<type_traits>

    template <class T>
    (since C++ 20)

        struct type_identity;

Provides the member typedef type that names T (i.e., the identity transformation).

Member types

Name Definition
type T

Helper types

template< class T > (since C++20)
using type_identity_t = typename type_identity<T>::type;

Possible implementation

  template< class T >
  struct type_identity {
      using type = T;
  };

Notes

type_identity can be used to block template_argument_deduction:

template <class T>

void f(T, T);
template <class T>

void g(T, std::type_identity_t<T>);

  f(4.2, 0); // error, deduced conflicting types for ‘T’
  g(4.2, 0); // OK, calls g<double>

Example

 This section is incomplete
 Reason: no example