Add test/variant_default_construct_cx_2. Refs #53.

Author: pdimov

test/Jamfile

@@ -157,3 +157,5 @@ for local list-size in $(list-sizes)
 {
     run variant_index_type.cpp : : : $(index-type-reqs) <define>LIST_SIZE=$(list-size) : variant_index_type_$(list-size) ;
 }
+
+compile variant_default_construct_cx_2.cpp ;

test/variant_default_construct_cx_2.cpp

@@ -0,0 +1,51 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if !defined(__cpp_constexpr_dynamic_alloc) || __cpp_constexpr_dynamic_alloc < 201907L
+
+BOOST_PRAGMA_MESSAGE("Skipping constexpr destructor test because __cpp_constexpr_dynamic_alloc < 201907L")
+int main() {}
+
+#else
+
+using namespace boost::variant2;
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+struct X
+{
+};
+
+struct Y
+{
+	constexpr ~Y() {}
+};
+
+struct Z
+{
+	~Z() {}
+};
+
+int main()
+{
+    {
+        constexpr variant<X> v;
+        STATIC_ASSERT( v.index() == 0 );
+    }
+
+    {
+        constexpr variant<X, Y> v;
+        STATIC_ASSERT( v.index() == 0 );
+    }
+
+    {
+        constexpr variant<X, Y, Z> v;
+        STATIC_ASSERT( v.index() == 0 );
+    }
+}
+
+#endif