libstdc++: Fix access issue in elements_view::_Sentinel [PR100631]

In the earlier commit r12-854 I forgot to also rewrite the other operator-
overload in terms of the split-out member function _M_distance_from.

libstdc++-v3/ChangeLog:

	PR libstdc++/100631
	* include/std/ranges (elements_view::_Sentinel::operator-): Use
	_M_distance_from in the other operator- overload too.
	* testsuite/std/ranges/adaptors/elements.cc (test06): Augment test.

diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index ca62f73..0588beb 100644 (file)
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -3687,7 +3687,7 @@ namespace views::__adaptor
            requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>>
            friend constexpr range_difference_t<_Base2>
            operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y)
-           { return __x._M_current - __y._M_end; }
+           { return -__y._M_distance_from(__x); }
 
          template<bool _Const2,
                   typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>>

diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc
index c6839e3..1322f44 100644 (file)
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc
@@ -128,7 +128,8 @@ test06()
     | views::keys;
   auto b = r.begin();
   auto e = r.end();
-  e - b;
+  VERIFY( e - b == 42 );
+  VERIFY( b - e == -42 );
 }
 
 void