@@ -20,7 +20,14 @@
#include <type_traits>
struct A { };
-struct B : A { };
+struct B : A {
+#if __cpp_aggregate_bases && __cpp_aggregate_paren_init
+ // A user-declared constructor prevents B from being an aggregate.
+ // Otherwise 'B&& b{A{}};' becomes valid in C++17 (__cpp_aggregate_bases),
+ // and 'B&& b(A{});' becomes valid in C++17 (__cpp_aggregate_paren_init).
+ B();
+#endif
+};
// libstdc++/51185
void f()
@@ -216,12 +216,20 @@ static_assert(std::is_constructible<const B&&, D&&>::value, "Error");
static_assert(!std::is_constructible<B&, const D&>::value, "Error");
static_assert(!std::is_constructible<B&&, const D&&>::value, "Error");
+#if __cpp_aggregate_bases && __cpp_aggregate_paren_init
+// In C++20 an rvalue reference or const lvalue reference can bind to a
+// temporary of aggregate type that is initialized from a base class value.
+constexpr bool v = true;
+#else
+constexpr bool v = false;
+#endif
+
static_assert(!std::is_constructible<D&, B&>::value, "Error");
-static_assert(!std::is_constructible<D&&, B&&>::value, "Error");
+static_assert(v == std::is_constructible<D&&, B&&>::value, "Error");
static_assert(!std::is_constructible<D&, const B&>::value, "Error");
-static_assert(!std::is_constructible<D&&, const B&&>::value, "Error");
-static_assert(!std::is_constructible<const D&, B&>::value, "Error");
-static_assert(!std::is_constructible<const D&&, B&&>::value, "Error");
+static_assert(v == std::is_constructible<D&&, const B&&>::value, "Error");
+static_assert(v == std::is_constructible<const D&, B&>::value, "Error");
+static_assert(v == std::is_constructible<const D&&, B&&>::value, "Error");
static_assert(!std::is_constructible<B&&, B&>::value, "Error");
static_assert(!std::is_constructible<B&&, D&>::value, "Error");
@@ -754,14 +762,21 @@ static_assert(!std::is_constructible<FromArgs<std::initializer_list<int>&,
std::initializer_list<B>&>, std::initializer_list<int>,
std::initializer_list<B>>::value, "Error");
+#if __cpp_aggregate_paren_init
+// In C++20 arrays can be initialized using parentheses.
+constexpr bool w = true;
+#else
+constexpr bool w = false;
+#endif
+
static_assert(!std::is_constructible<FromArgs<std::initializer_list<int>>,
int, int>::value, "Error");
static_assert(!std::is_constructible<const
FromArgs<std::initializer_list<int>>, int, int>::value, "Error");
-static_assert(!std::is_constructible<B[2], B, B>::value, "Error");
-static_assert(!std::is_constructible<const B[2], B, B>::value, "Error");
-static_assert(!std::is_constructible<U[2], U, U>::value, "Error");
-static_assert(!std::is_constructible<const U[2], U, U>::value, "Error");
+static_assert(w == std::is_constructible<B[2], B, B>::value, "Error");
+static_assert(w == std::is_constructible<const B[2], B, B>::value, "Error");
+static_assert(w == std::is_constructible<U[2], U, U>::value, "Error");
+static_assert(w == std::is_constructible<const U[2], U, U>::value, "Error");
static_assert(!std::is_constructible<E, E, E>::value, "Error");
static_assert(!std::is_constructible<const E, E, E>::value, "Error");