[Fact]
        public void AssignmentToInt()
        {
            string source = @"
class C
{
    static void Main()
    {
        int x = default;
        System.Console.Write(x);
    }
}
";
            var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_1, options: TestOptions.DebugExe);
...

            var tree = comp.SyntaxTrees.First();
            var model = comp.GetSemanticModel(tree);
            var nodes = tree.GetCompilationUnitRoot().DescendantNodes();

            var def = nodes.OfType<LiteralExpressionSyntax>().Single();
            Assert.Equal("System.Int32", model.GetTypeInfo(def).Type.ToTestDisplayString()); // should be null
            Assert.Equal("System.Int32", model.GetTypeInfo(def).ConvertedType.ToTestDisplayString());
...
        }