Is a nullable type not a struct or value type?

Question

I wrote the following code to determine the type of 'int?' using Roslyn:-

static void Main(string[] args)
        {
            var compilationUnit = SyntaxTree.ParseCompilationUnit(@"
class Class
{
int? a = 10;
}");
            AssemblyFileReference mscorlib = new AssemblyFileReference(typeof(object).Assembly.Location);
            Compilation compilation = Compilation.Create("RoslynExp2", null, new[] { compilationUnit }, new[] { mscorlib });
            SemanticModel semanticModel = compilation.GetSemanticModel(compilationUnit);
            FieldDeclarationSyntax fieldDecl = compilationUnit.Root.DescendentNodes().OfType<FieldDeclarationSyntax>().First();
            FieldSymbol fieldSymbol = semanticModel.GetDeclaredSymbol(fieldDecl) as FieldSymbol;
            var type = fieldSymbol.Type;
            Console.WriteLine("field name = {0}, type name = {1}, type kind = {2}", fieldSymbol.Name, type.Name, type.TypeKind);
            Console.WriteLine(String.Format("TypeKind.Struct = {0}, IsValueType = {1}", type.TypeKind == TypeKind.Struct, type.IsValueType));
        }

And I got the following output:-

 

field name = a, type name = Nullable, type kind = Error

TypeKind.Struct = False, IsValueType = False

Is this expected? Or did I make a mistake while writing the code?

 

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Nikhil Agarwal

Answer 1

The TypeKind was Error.  I doubt nullable type notation (?) is supported in the preview.

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Wayward LINQ Lacky

Answer 2

Hi Nikhil - Nullable types are not supported in the Roslyn CTP. You can find the list of known issues and not-yet-implemented features here.

 

As Matt mentioned, you can check the TypeSymbol.Kind / .TypeKind to ensure that the returned symbol is good.

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Shyam Namboodiripad | Software Development Engineer in Test | Roslyn Compilers Team