applies P1207

include/range/v3/iterator/concepts.hpp

@@ -224,7 +224,8 @@ namespace ranges
 
     template<typename I>
     CPP_concept_bool weakly_incrementable =
-        semiregular<I> &&
+        default_constructible<I> &&
+        movable<I> &&
         CPP_fragment(ranges::weakly_incrementable_, I);
 
     template<typename I>

include/range/v3/iterator/counted_iterator.hpp

@@ -123,11 +123,17 @@ namespace ranges
             cnt_ = i.count();
         }
 
-        constexpr I base() const
+        constexpr auto base() const& -> CPP_ret(I)( //
+            requires copy_constructible<I>)
         {
             return current_;
         }
 
+        constexpr auto base() &&
+        {
+            return std::move(current_);
+        }
+
         constexpr iter_difference_t<I> count() const
         {
             return cnt_;

include/range/v3/iterator/move_iterators.hpp

@@ -44,7 +44,7 @@ namespace ranges
 
         constexpr move_iterator() = default;
         explicit move_iterator(I i)
-          : current_(i)
+          : current_(std::move(i))
         {}
         template<typename O>
         CPP_ctor(move_iterator)(move_iterator<O> const & i)( //
@@ -58,10 +58,15 @@ namespace ranges
             current_ = i.base();
             return *this;
         }
-        I base() const
+        auto base() const& -> CPP_ret(I)( //
+            requires copy_constructible<I>)
         {
             return current_;
         }
+        I base() &&
+        {
+            return std::move(current_);
+        }
         // clang-format off
         auto CPP_auto_fun(operator*)()(const)
         (

test/iterator/iterator.cpp

@@ -23,6 +23,7 @@
 #include <range/v3/algorithm/copy.hpp>
 #include "../simple_test.hpp"
 #include "../test_utils.hpp"
+#include "range/v3/iterator/concepts.hpp"
 
 using namespace ranges;
 
@@ -428,6 +429,23 @@ void deep_integration_test()
 
 #endif
 
+struct move_only_iterator {
+    using difference_type = std::ptrdiff_t;
+
+    move_only_iterator() = default;
+
+    move_only_iterator(move_only_iterator&&) = default;
+    move_only_iterator& operator=(move_only_iterator&&) = default;
+
+    move_only_iterator(move_only_iterator const&) = delete;
+    move_only_iterator& operator=(move_only_iterator const&) = delete;
+
+    move_only_iterator& operator++() { return *this; }
+    void operator++(int) { ++*this; }
+};
+static_assert(ranges::weakly_incrementable<move_only_iterator>, "");
+static_assert(!ranges::incrementable<move_only_iterator>, "");
+
 int main()
 {
     test_insert_iterator();