[libcxx-commits] [libcxx] [libc++] Make `constexpr std::variant`. Implement P2231R1 (PR #83335)

[via libcxx-commits]

================
@@ -224,265 +204,293 @@ void test_swap_valueless_by_exception() {
 #endif
 }
 
-void test_swap_same_alternative() {
+TEST_CONSTEXPR_CXX20 void test_swap_same_alternative() {
   {
-    using T = ThrowingTypeWithNothrowSwap;
-    using V = std::variant<T, int>;
-    T::reset();
-    V v1(std::in_place_index<0>, 42);
-    V v2(std::in_place_index<0>, 100);
+    using V                = std::variant<ThrowingTypeWithNothrowSwap, int>;
+    int move_called        = 0;
+    int move_assign_called = 0;
+    int swap_called        = 0;
+    V v1(std::in_place_index<0>, 42, &move_called, &move_assign_called, &swap_called);
+    V v2(std::in_place_index<0>, 100, &move_called, &move_assign_called, &swap_called);
     v1.swap(v2);
-    assert(T::swap_called == 1);
+    assert(swap_called == 1);
     assert(std::get<0>(v1).value == 100);
     assert(std::get<0>(v2).value == 42);
     swap(v1, v2);
-    assert(T::swap_called == 2);
+    assert(swap_called == 2);
     assert(std::get<0>(v1).value == 42);
     assert(std::get<0>(v2).value == 100);
+
+    assert(move_called == 0);
+    assert(move_assign_called == 0);
   }
   {
-    using T = NothrowMoveable;
-    using V = std::variant<T, int>;
-    T::reset();
-    V v1(std::in_place_index<0>, 42);
-    V v2(std::in_place_index<0>, 100);
+    using V                = std::variant<NothrowMoveable, int>;
+    int move_called        = 0;
+    int move_assign_called = 0;
+    int swap_called        = 0;
+    V v1(std::in_place_index<0>, 42, &move_called, &move_assign_called, &swap_called);
+    V v2(std::in_place_index<0>, 100, &move_called, &move_assign_called, &swap_called);
     v1.swap(v2);
-    assert(T::swap_called == 0);
-    assert(T::move_called == 1);
-    assert(T::move_assign_called == 2);
+    assert(swap_called == 0);
+    assert(move_called == 1);
+    assert(move_assign_called == 2);
     assert(std::get<0>(v1).value == 100);
     assert(std::get<0>(v2).value == 42);
-    T::reset();
+
+    move_called        = 0;
+    move_assign_called = 0;
+    swap_called        = 0;
+
     swap(v1, v2);
-    assert(T::swap_called == 0);
-    assert(T::move_called == 1);
-    assert(T::move_assign_called == 2);
+    assert(swap_called == 0);
+    assert(move_called == 1);
+    assert(move_assign_called == 2);
     assert(std::get<0>(v1).value == 42);
     assert(std::get<0>(v2).value == 100);
   }
+}
+
+void test_swap_same_alternative_throws(){
----------------
huixie90 wrote:

https://github.com/llvm/llvm-project/issues/84674

https://github.com/llvm/llvm-project/pull/83335