#include <compare>
#include <initializer_list>
namespace std {
template<class T, class Allocator = allocator<T>> class forward_list;
template<class T, class Allocator>
bool operator==(const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);
template<class T, class Allocator>
synth-three-way-result<T> operator<=>(const forward_list<T, Allocator>& x,
const forward_list<T, Allocator>& y);
template<class T, class Allocator>
void swap(forward_list<T, Allocator>& x, forward_list<T, Allocator>& y)
noexcept(noexcept(x.swap(y)));
template<class T, class Allocator, class U>
typename forward_list<T, Allocator>::size_type
erase(forward_list<T, Allocator>& c, const U& value);
template<class T, class Allocator, class Predicate>
typename forward_list<T, Allocator>::size_type
erase_if(forward_list<T, Allocator>& c, Predicate pred);
namespace pmr {
template<class T>
using forward_list = std::forward_list<T, polymorphic_allocator<T>>;
}
}