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  1. #include <iostream>
  2. #include <utility>
  3. using namespace std;
  4.  
  5. template<typename X>
  6. struct thing {
  7. };
  8.  
  9. template<typename T>
  10. decltype (auto) f(T&& t) {
  11.  if (std::is_same<typename std::remove_reference<T>::type, T>::value) {
  12.   cout << "not ";
  13.  }
  14.  cout << "a reference" << endl;
  15.  return std::forward<T>(t);
  16. }
  17. template<
  18.  template<class> class T,
  19.  typename A>
  20. decltype (auto) g(T<A>&& t) {
  21.  return std::forward<T<A>>(t);
  22. }
  23.  
  24. int main(int, char**) {
  25.  thing<int> it {};
  26.  f(thing<int> {});
  27.  f(it);
  28.  // T = thing<int> &
  29.  // T&& = thing<int>& && = thing<int>&
  30.  g(thing<int> {});
  31.  //g(it);
  32.  // T = thing
  33.  // A = int
  34.  // T<A>&& = thing<int>&&
  35.  return 0;
  36. }
Success #stdin #stdout 0s 3412KB
comments (?)
stdin
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Standard input is empty
stdout
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not a reference
a reference
https://ideone.com/RPrPA1
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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