[Fact]
        public void InStringInterpolation()
        {
            string source = @"
class C
{
    static void Main()
    {
        System.Console.Write($""({default}) ({null})"");
    }
}
";

            var comp = CreateCompilationWithMscorlib(source, parseOptions: TestOptions.Regular7_1, options: TestOptions.DebugExe);
            comp.VerifyDiagnostics();
            CompileAndVerify(comp, expectedOutput: "() ()");

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

            var def = nodes.OfType<LiteralExpressionSyntax>().ElementAt(0);
            Assert.Equal("default", def.ToString());
            Assert.Null(model.GetTypeInfo(def).Type); // Should be given a type. Follow-up issue: https://github.com/dotnet/roslyn/issues/18609
            Assert.Null(model.GetTypeInfo(def).ConvertedType);
            Assert.Null(model.GetSymbolInfo(def).Symbol);
            Assert.False(model.GetConstantValue(def).HasValue);
            Assert.False(model.GetConversion(def).IsNullLiteral);

            var nullSyntax = nodes.OfType<LiteralExpressionSyntax>().ElementAt(1);
            Assert.Equal("null", nullSyntax.ToString());
            Assert.Null(model.GetTypeInfo(nullSyntax).Type);
            Assert.Null(model.GetTypeInfo(nullSyntax).ConvertedType); // Should be given a type. Follow-up issue: https://github.com/dotnet/roslyn/issues/18609
            Assert.Null(model.GetSymbolInfo(nullSyntax).Symbol);
        }

        [Fact]
        public void InUsing()
        {
            string source = @"
class C
{
    static void Main()
    {
        using (default)
        {
            System.Console.Write(""ok"");
        }
        using (null) { }
    }
}
";

            var comp = CreateCompilationWithMscorlib(source, parseOptions: TestOptions.Regular7_1, options: TestOptions.DebugExe);
            comp.VerifyDiagnostics(); 
            CompileAndVerify(comp, expectedOutput: "ok");

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

            var def = nodes.OfType<LiteralExpressionSyntax>().ElementAt(0);
            Assert.Equal("default", def.ToString());
            Assert.Null(model.GetTypeInfo(def).Type);
            Assert.Null(model.GetTypeInfo(def).ConvertedType); // Should get a type. Follow-up issue: https://github.com/dotnet/roslyn/issues/18609
            Assert.Null(model.GetSymbolInfo(def).Symbol);
            Assert.False(model.GetConstantValue(def).HasValue);
            Assert.False(model.GetConversion(def).IsNullLiteral);

            var nullSyntax = nodes.OfType<LiteralExpressionSyntax>().ElementAt(2);
            Assert.Equal("null", nullSyntax.ToString());
            Assert.Null(model.GetTypeInfo(nullSyntax).Type);
            Assert.Null(model.GetTypeInfo(nullSyntax).ConvertedType); // Should get a type. Follow-up issue: https://github.com/dotnet/roslyn/issues/18609
        }