libstdc++: Implement LWG 3580 change to ranges::iota_view

libstdc++-v3/ChangeLog:

	* include/std/ranges (iota_view::_Iterator::operator+): Adjust
	definition as per LWG 3580.
	(iota_view::_Iterator::operator-): Likewise.

(cherry picked from commit 5566f3c6b46cf053ae4b918513e318561b7af053)

diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 70f571f74fd61ab3208bc15b0f2ce5abecda3ffa..99404acda3d81403d6dea5d3bbda8b0bb17cbe7f 100644 (file)
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -461,7 +461,10 @@ namespace ranges
        friend constexpr _Iterator
        operator+(_Iterator __i, difference_type __n)
          requires __detail::__advanceable<_Winc>
-       { return __i += __n; }
+       {
+         __i += __n;
+         return __i;
+       }
 
        friend constexpr _Iterator
        operator+(difference_type __n, _Iterator __i)
@@ -471,7 +474,10 @@ namespace ranges
        friend constexpr _Iterator
        operator-(_Iterator __i, difference_type __n)
          requires __detail::__advanceable<_Winc>
-       { return __i -= __n; }
+       {
+         __i -= __n;
+         return __i;
+       }
 
        friend constexpr difference_type
        operator-(const _Iterator& __x, const _Iterator& __y)