LWG3737 take_view::sentinel should provide operator-

Partially fixes NB US 109 (C++23 CD).

Author: burblebee

source/ranges.tex

@@ -5746,6 +5746,10 @@
           auto sz = range_difference_t<V>(size());
           return counted_iterator(ranges::begin(@\exposid{base_}@), sz);
         }
+      } else if constexpr (@\libconcept{sized_sentinel_for}@<sentinel_t<V>, iterator_t<V>>) {
+        auto it = ranges::begin(@\exposid{base_}@);
+        auto sz = std::min(@\exposid{count_}@, ranges::end(@\exposid{base_}@) - it);
+        return counted_iterator(std::move(it), sz);
       } else {
         return counted_iterator(ranges::begin(@\exposid{base_}@), @\exposid{count_}@);
       }
@@ -5759,6 +5763,10 @@
           auto sz = range_difference_t<const V>(size());
           return counted_iterator(ranges::begin(@\exposid{base_}@), sz);
         }
+      } else if constexpr (@\libconcept{sized_sentinel_for}@<sentinel_t<const V>, iterator_t<const V>>) {
+        auto it = ranges::begin(@\exposid{base_}@);
+        auto sz = std::min(@\exposid{count_}@, ranges::end(@\exposid{base_}@) - it);
+        return counted_iterator(std::move(it), sz);
       } else {
         return counted_iterator(ranges::begin(@\exposid{base_}@), @\exposid{count_}@);
       }
@@ -5770,6 +5778,8 @@
           return ranges::begin(@\exposid{base_}@) + range_difference_t<V>(size());
         else
           return default_sentinel;
+      } else if constexpr (@\libconcept{sized_sentinel_for}@<sentinel_t<V>, iterator_t<V>>) {
+        return default_sentinel;
       } else {
         return @\exposid{sentinel}@<false>{ranges::end(@\exposid{base_}@)};
       }
@@ -5781,6 +5791,8 @@
           return ranges::begin(@\exposid{base_}@) + range_difference_t<const V>(size());
         else
           return default_sentinel;
+      } else if constexpr (@\libconcept{sized_sentinel_for}@<sentinel_t<const V>, iterator_t<const V>>) {
+        return default_sentinel;
       } else {
         return @\exposid{sentinel}@<true>{ranges::end(@\exposid{base_}@)};
       }