deductionguidesforstd::set(3)

NAME
deductionguidesforstd::set - deductionguidesforstd::set

Synopsis
   Defined in header <set>
   template<
       class InputIt,
       class Comp = std::less<typename
   std::iterator_traits<InputIt>::value_type>,
       class Alloc = std::allocator<typename (1) (since C++17)
   std::iterator_traits<InputIt>::value_type>>
   set( InputIt, InputIt, Comp = Comp(), Alloc = Alloc() )
       -> set<typename std::iterator_traits<InputIt>::value_type,
   Comp, Alloc>;
   template<
       class Key, class Comp = std::less<Key>,
       class Alloc = std::allocator<Key> > (2) (since C++17)
   set( std::initializer_list<Key>, Comp = Comp(), Alloc = Alloc() )
       -> set<Key, Comp, Alloc>;
   template< class InputIt, class Alloc >
   set( InputIt, InputIt, Alloc )
       -> set<typename std::iterator_traits<InputIt>::value_type, (3) (since C++17)
              std::less<typename
   std::iterator_traits<InputIt>::value_type>, Alloc>;
   template< class Key, class Alloc >
   set( std::initializer_list<Key>, Alloc ) (4) (since C++17)
       -> set<Key, std::less<Key>, Alloc>;
   template< ranges::input_range R, class Compare =
   less<ranges::range_value_t<R>>,
             class Alloc = std::allocator<ranges::range_value_t<R>> > (5) (since C++23)
   set( std::from_range_t, R&&, Compare = Compare(), Alloc = Alloc()
   )
       -> set<ranges::range_value_t<R>, Compare, Alloc>;
   template< ranges::input_range R, class Alloc >
   set( std::from_range_t, R&&, Alloc ) (6) (since C++23)
       -> set<ranges::range_value_t<R>,
   std::less<ranges::range_value_t<R>>, Alloc>;
   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)).
   5,6) These deduction guides are provided for set to allow deduction from a
   std::from_range_t tag and an input_range.
   These overloads participate in overload resolution only if InputIt satisfies
   LegacyInputIterator, Alloc satisfies Allocator, and Comp does not satisfy Allocator.
   Note: the extent to which the library determines that a type does not satisfy
   LegacyInputIterator is unspecified, except that as a minimum integral types do not
   qualify as input iterators. Likewise, the extent to which it determines that a type
   does not satisfy Allocator is unspecified, except that as a minimum the member type
   Alloc::value_type must exist and the expression
   std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as
   an unevaluated operand.

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

Example
// Run this code
 #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());
 }