Re: [committed 2/3] libstdc++: Add remaining C++20 changes to iterator adaptors

[Jonathan Wakely via Gcc-patches]

On 27/03/20 23:29 +0000, Jonathan Wakely wrote:

@@ -403,6 +428,49 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    operator>=(const reverse_iterator<_IteratorL>& __x,
               const reverse_iterator<_IteratorR>& __y)
    { return !(__x < __y); }
+#else // C++20
+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator==(const reverse_iterator<_IteratorL>& __x,
+              const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() == __y.base()))
+    { return __x.base() == __y.base(); }
+
+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator!=(const reverse_iterator<_IteratorL>& __x,
+              const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() != __y.base()))
+    { return __x.base() != __y.base(); }
+
+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator<(const reverse_iterator<_IteratorL>& __x,
+             const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() < __y.base()))
+    { return __x.base() < __y.base(); }

Drat, these relational operators use the wrong operator. The sense
needs to be flipped because they're reverse_iterators.

Looks like I lost an edit to this file that I made on another machine,
and committed the wrong version. I'll fix it ASAP.

+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator>(const reverse_iterator<_IteratorL>& __x,
+             const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() > __y.base()))
+    { return __x.base() > __y.base(); }
+
+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator<=(const reverse_iterator<_IteratorL>& __x,
+              const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() <= __y.base()))
+    { return __x.base() <= __y.base(); }
+
+  template<typename _IteratorL, typename _IteratorR>
+    constexpr auto
+    operator>=(const reverse_iterator<_IteratorL>& __x,
+              const reverse_iterator<_IteratorR>& __y)
+    -> decltype(__detail::__convbool(__x.base() >= __y.base()))
+    { return __x.base() >= __y.base(); }
+#endif // C++20
  //@}

#if __cplusplus < 201103L