33 Thread support library [thread]

33.2 Requirements [thread.req]

33.2.6 decay_­copy [thread.decaycopy]

In several places in this Clause the operation DECAY_­COPY(x) is used.
All such uses mean call the function decay_­copy(x) and use the result, where decay_­copy is defined as follows:
template<class T> decay_t<T> decay_copy(T&& v)
  { return std::forward<T>(v); }