libstdc++: Remove operator!= overloads for unordered containers

Some more C++20 changes from P1614R2, "The Mothership has Landed".

	* include/bits/unordered_map.h (unordered_map, unordered_multimap):
	Remove redundant operator!= for C++20.
	* include/bits/unordered_set.h (unordered_set, unordered_multiset):
	Likewise.
	* include/debug/unordered_map (unordered_map, unordered_multimap):
	Likewise.
	* include/debug/unordered_set (unordered_set, unordered_multiset):
	Likewise.

libstdc++-v3/ChangeLog

 2020-04-19  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/unordered_map.h (unordered_map, unordered_multimap):
+	Remove redundant operator!= for C++20.
+	* include/bits/unordered_set.h (unordered_set, unordered_multiset):
+	Likewise.
+	* include/debug/unordered_map (unordered_map, unordered_multimap):
+	Likewise.
+	* include/debug/unordered_set (unordered_set, unordered_multiset):
+	Likewise.
+
 	PR other/94629
 	* include/debug/formatter.h (_Error_formatter::_Parameter): Fix
 	redundant assignment in constructor.

libstdc++-v3/include/bits/unordered_map.h

@@ -2092,11 +2092,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	       const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_h._M_equal(__y._M_h); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
     inline bool
     operator!=(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
   template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
     inline bool
@@ -2104,11 +2106,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	       const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_h._M_equal(__y._M_h); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
     inline bool
     operator!=(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
 _GLIBCXX_END_NAMESPACE_CONTAINER
 

libstdc++-v3/include/bits/unordered_set.h

@@ -1704,11 +1704,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	       const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_h._M_equal(__y._M_h); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<class _Value, class _Hash, class _Pred, class _Alloc>
     inline bool
     operator!=(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
   template<class _Value, class _Hash, class _Pred, class _Alloc>
     inline bool
@@ -1716,11 +1718,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	       const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_h._M_equal(__y._M_h); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<class _Value, class _Hash, class _Pred, class _Alloc>
     inline bool
     operator!=(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
 _GLIBCXX_END_NAMESPACE_CONTAINER
 

libstdc++-v3/include/debug/unordered_map

@@ -741,13 +741,14 @@ namespace __debug
 	       const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_base() == __y._M_base(); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<typename _Key, typename _Tp, typename _Hash,
 	   typename _Pred, typename _Alloc>
     inline bool
     operator!=(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
-
+#endif
 
   /// Class std::unordered_multimap with safety/checking/debug instrumentation.
   template<typename _Key, typename _Tp,
@@ -1347,12 +1348,14 @@ namespace __debug
 	       const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_base() == __y._M_base(); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<typename _Key, typename _Tp, typename _Hash,
 	   typename _Pred, typename _Alloc>
     inline bool
     operator!=(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
 } // namespace __debug
 } // namespace std

libstdc++-v3/include/debug/unordered_set

@@ -612,12 +612,13 @@ namespace __debug
 	       const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_base() == __y._M_base(); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<typename _Value, typename _Hash, typename _Pred, typename _Alloc>
     inline bool
     operator!=(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
-
+#endif
 
   /// Class std::unordered_multiset with safety/checking/debug instrumentation.
   template<typename _Value,
@@ -1176,11 +1177,13 @@ namespace __debug
 	       const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
     { return __x._M_base() == __y._M_base(); }
 
+#if __cpp_impl_three_way_comparison < 201907L
   template<typename _Value, typename _Hash, typename _Pred, typename _Alloc>
     inline bool
     operator!=(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
 	       const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
     { return !(__x == __y); }
+#endif
 
 } // namespace __debug
 } // namespace std