Made a stab at has_default_constructor. Got it mostly working for g++-4.0, but only works for scalar types on clang. Ultimately this needs a compiler-supported is_constructible which clang is missing, and won't be able to use until it gets variadic templates.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@113225 91177308-0d34-0410-b5e6-96231b3b80d8

test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp

@@ -13,7 +13,58 @@
 
 #include <type_traits>
 
+template <class T, bool Result>
+void test_has_default_constructor()
+{
+    static_assert(std::has_default_constructor<T>::value == Result, "");
+    static_assert(std::has_default_constructor<const T>::value == Result, "");
+    static_assert(std::has_default_constructor<volatile T>::value == Result, "");
+    static_assert(std::has_default_constructor<const volatile T>::value == Result, "");
+}
+
+class Empty
+{
+};
+
+class NotEmpty
+{
+public:
+    virtual ~NotEmpty();
+};
+
+union Union {};
+
+struct bit_zero
+{
+    int :  0;
+};
+
+class Abstract
+{
+public:
+    virtual ~Abstract() = 0;
+};
+
+struct A
+{
+    A();
+};
+
 int main()
 {
-#error has_default_constructor not implemented
+    test_has_default_constructor<void, false>();
+    test_has_default_constructor<int&, false>();
+    test_has_default_constructor<char[], false>();
+    test_has_default_constructor<Abstract, false>();
+
+    test_has_default_constructor<A, true>();
+    test_has_default_constructor<Union, true>();
+    test_has_default_constructor<Empty, true>();
+    test_has_default_constructor<int, true>();
+    test_has_default_constructor<double, true>();
+    test_has_default_constructor<int*, true>();
+    test_has_default_constructor<const int*, true>();
+    test_has_default_constructor<char[3], true>();
+    test_has_default_constructor<NotEmpty, true>();
+    test_has_default_constructor<bit_zero, true>();
 }

test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp

@@ -37,6 +37,7 @@ class Empty
 
 class NotEmpty
 {
+public:
     virtual ~NotEmpty();
 };
 
@@ -49,6 +50,7 @@ struct bit_zero
 
 class Abstract
 {
+public:
     virtual ~Abstract() = 0;
 };