deduction guides for std::set

Since C++17

Header: <set>

1-4) These deduction guides are provided for set to allow deduction from an iterator range (overloads (1,3)) and std::initializer_list (overloads (2,4)).

# Declarations

template<
class InputIt,
class Comp = std::less<typename std::iterator_traits<InputIt>::value_type>,
class Alloc = std::allocator<typename std::iterator_traits<InputIt>::value_type>>
set( InputIt, InputIt, Comp = Comp(), Alloc = Alloc() )
-> set<typename std::iterator_traits<InputIt>::value_type, Comp, Alloc>;

(since C++17)

template<
class Key, class Comp = std::less<Key>,
class Alloc = std::allocator<Key> >
set( std::initializer_list<Key>, Comp = Comp(), Alloc = Alloc() )
-> set<Key, Comp, Alloc>;

(since C++17)

template< class InputIt, class Alloc >
set( InputIt, InputIt, Alloc )
-> set<typename std::iterator_traits<InputIt>::value_type,
std::less<typename std::iterator_traits<InputIt>::value_type>, Alloc>;

(since C++17)

template< class Key, class Alloc >
set( std::initializer_list<Key>, Alloc )
-> set<Key, std::less<Key>, Alloc>;

(since C++17)

template< ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
class Alloc = std::allocator<ranges::range_value_t<R>> >
set( std::from_range_t, R&&, Compare = Compare(), Alloc = Alloc() )
-> set<ranges::range_value_t<R>, Compare, Alloc>;

(since C++23)

template< ranges::input_range R, class Alloc >
set( std::from_range_t, R&&, Alloc )
-> set<ranges::range_value_t<R>, std::less<ranges::range_value_t<R>>, Alloc>;

(since C++23)

# Notes

Feature-test macro Value Std Feature __cpp_lib_containers_ranges 202202L (C++23) Ranges-aware construction and insertion; overload (5,6)

# Example

#include <set>
 
int main()
{
    // guide #2 deduces std::set<int>
    std::set s = {1, 2, 3, 4};
 
    // guide #1 deduces std::set<int>
    std::set s2(s.begin(), s.end());
}