std::ranges::sized_range,std::ranges::disable_sized_range(3)

NAME
std::ranges::sized_range,std::ranges::disable_sized_range - std::ranges::sized_range,std::ranges::disable_sized_range

Synopsis
   Defined in header <ranges>
   template< class T >
   concept sized_range = ranges::range<T> &&
       requires(T& t) { (1) (since C++20)
           ranges::size(t);
       };
   template< class > (2) (since C++20)
   inline constexpr bool disable_sized_range = false;
   1) The sized_range concept specifies the requirements of a range type that knows its
   size in constant time with the size function.
   2) disable_sized_range exists to allow use of range types that provide a size
   function (either as a member or as a non-member) but do not in fact model
   sized_range. Users may specialize disable_sized_range for cv-unqualified
   program-defined types. Such specializations shall be usable in constant expressions
   and have type const bool.

Notes
   disable_sized_range cannot be used to opt-out a range whose iterator and sentinel
   satisfy sized_sentinel_for; std::disable_sized_sentinel_for must be used instead.
   disable_sized_range cannot be specialized for array types or reference types.

Example
// Run this code
 #include <forward_list>
 #include <list>
 #include <ranges>
 static_assert
 (
     std::ranges::sized_range<std::list<int>> and
     not std::ranges::sized_range<std::forward_list<int>>
 );
 int main() {}

See also
   ranges::random_access_range specifies a range whose iterator type satisfies
   (C++20) random_access_iterator
                        (concept)
   ranges::contiguous_range specifies a range whose iterator type satisfies
   (C++20) contiguous_iterator
                        (concept)