base() const &&

owning::base() const && = delete to sometimes avoid accidental copy.
For presumably cheap to copy cases, we want to always return by value from rvalue object, even if it is const

view/move.h

@@ -48,6 +48,7 @@ class _moveView
 		OEL_REQUIRES(iter_is_random_access< iterator_t<View> >)   OEL_ALWAYS_INLINE { return begin()[index]; }
 
 	constexpr View         base() &&                { return std::move(_base); }
+	constexpr View         base() const &&          { return _base; }
 	constexpr const View & base() const & noexcept  { return _base; }
 };
 

view/owning.h

@@ -49,8 +49,9 @@ class owning
 	constexpr decltype(auto) operator[](difference_type index)
 		OEL_REQUIRES(iter_is_random_access< iterator_t<Range> >)   { return adl_begin(_r)[index]; }
 
-	constexpr Range &&      base() && noexcept       { return std::move(_r); }
-	constexpr const Range & base() const & noexcept  { return _r; }
+	constexpr Range         base() &&                 { return std::move(_r); }
+	constexpr const Range & base() const & noexcept   { return _r; }
+	void                    base() const && = delete;
 };
 
 }

view/transform.h

@@ -75,6 +75,7 @@ class _transformView
 	constexpr bool empty()   { return _m.first.empty(); }
 
 	constexpr View         base() &&                { return std::move(_m.first); }
+	constexpr View         base() const &&          { return _m.first; }
 	constexpr const View & base() const & noexcept  { return _m.first; }
 };
 

view/transform_iterator.h

@@ -49,6 +49,7 @@ class transform_iterator
 	constexpr transform_iterator(UnaryFunc f, Iterator it)   : _m{std::move(it), std::move(f)} {}
 
 	constexpr Iterator         base() &&                       { return std::move(_m.first); }
+	constexpr Iterator         base() const &&                            { return _m.first; }
 	constexpr const Iterator & base() const & noexcept  OEL_ALWAYS_INLINE { return _m.first; }
 
 	constexpr reference operator*() const