Implement LWG-3865 Sorting a range of pairs (#3476)

Co-authored-by: Casey Carter <Casey@Carter.net>
microsoft · Feb 23, 2023 · 9fb8168 · 9fb8168
1 parent f91eba5
commit 9fb8168
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Showing 3 changed files with 41 additions and 15 deletions.
diff --git a/stl/inc/utility b/stl/inc/utility
@@ -480,45 +480,46 @@ constexpr void swap(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Righ
 }
 #endif // _HAS_CXX23
 
-_EXPORT_STD template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator==(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+_EXPORT_STD template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator==(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return _Left.first == _Right.first && _Left.second == _Right.second;
 }
 
 #ifdef __cpp_lib_concepts
-_EXPORT_STD template <class _Ty1, class _Ty2>
-_NODISCARD constexpr common_comparison_category_t<_Synth_three_way_result<_Ty1>, _Synth_three_way_result<_Ty2>>
-    operator<=>(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+_EXPORT_STD template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr common_comparison_category_t<_Synth_three_way_result<_Ty1, _Uty1>,
+    _Synth_three_way_result<_Ty2, _Uty2>>
+    operator<=>(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     if (auto _Result = _Synth_three_way{}(_Left.first, _Right.first); _Result != 0) {
         return _Result;
     }
     return _Synth_three_way{}(_Left.second, _Right.second);
 }
 #else // ^^^ defined(__cpp_lib_concepts) / !defined(__cpp_lib_concepts) vvv
 #if !_HAS_CXX20
-template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator!=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator!=(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return !(_Left == _Right);
 }
 #endif // !_HAS_CXX20
 
-template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator<(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator<(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return _Left.first < _Right.first || (!(_Right.first < _Left.first) && _Left.second < _Right.second);
 }
 
-template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator>(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator>(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return _Right < _Left;
 }
 
-template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator<=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator<=(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return !(_Right < _Left);
 }
 
-template <class _Ty1, class _Ty2>
-_NODISCARD constexpr bool operator>=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
+template <class _Ty1, class _Ty2, class _Uty1, class _Uty2>
+_NODISCARD constexpr bool operator>=(const pair<_Ty1, _Ty2>& _Left, const pair<_Uty1, _Uty2>& _Right) {
     return !(_Left < _Right);
 }
 #endif // ^^^ !defined(__cpp_lib_concepts) ^^^

diff --git a/tests/libcxx/expected_results.txt b/tests/libcxx/expected_results.txt
@@ -138,6 +138,9 @@ std/ranges/range.access/rbegin.pass.cpp FAIL
 std/ranges/range.access/rend.pass.cpp FAIL
 std/ranges/range.access/size.pass.cpp FAIL
 
+# libc++ doesn't implement LWG-3865 Sorting a range of pairs
+std/utilities/tuple/tuple.tuple/tuple.apply/make_from_tuple.pass.cpp FAIL
+
 
 # *** INTERACTIONS WITH CONTEST / C1XX THAT UPSTREAM LIKELY WON'T FIX ***
 # Tracked by VSO-593630 "<filesystem> Enable libcxx filesystem tests"

diff --git a/tests/std/tests/Dev11_1140665_unique_ptr_array_conversions/test.cpp b/tests/std/tests/Dev11_1140665_unique_ptr_array_conversions/test.cpp
@@ -183,6 +183,25 @@ void my_swap(unique_ptr<incomplete>& lhs, unique_ptr<incomplete>& rhs) {
     swap(lhs, rhs);
 }
 
+// also test LWG-3865 Sorting a range of pairs
+constexpr bool test_lwg3865() {
+    const pair<int, int> a{1, 2};
+    const pair<long, long> b{1, 2};
+    const pair<long, long> c{2, 2};
+    assert(a == b);
+    assert(a != c);
+    assert(c >= a);
+    assert(b >= a);
+    assert(c > a);
+    assert(!(b > a));
+    assert(a < c);
+    assert(!(a < b));
+    assert(a <= c);
+    assert(a <= b);
+
+    return true;
+}
+
 int main() {
     {
         assert(g_objects == 0);
@@ -271,4 +290,7 @@ int main() {
         };
         (void) make_unique<unique_ptr<S>[]>(42);
     }
+
+    test_lwg3865();
+    STATIC_ASSERT(test_lwg3865());
 }