Search for contextual keywords with Roslyn

Question

Search for contextual keywords with Roslyn

It's hard for me to define contextual keywords (var, yield, async, etc.) with Roslyn. I inherited from CSharpSyntaxWalkerand overrode VisitToken. SyntaxTokenprovides an extension method IsContextualKeyword(), but it always returns false.

Here is a sample that should display all contextual keywords in the syntax tree:

public class TokenWalker : CSharpSyntaxWalker
{
    public TokenWalker() : base(SyntaxWalkerDepth.Token) { }

    public override void VisitToken(SyntaxToken token)
    {
        //Trying to determine if we're visiting a contextual keyword
        if (token.IsContextualKeyword())
        {
            Console.WriteLine(token.ToString());
        }
        base.VisitToken(token);
    }
}

And using this class as follows:

public static void TaggingVarKeyword()
{
    var tree = CSharpSyntaxTree.ParseText(@"
    public class MyClass
    {
        public void MyMethod()
        {
            var var = 4;
        }
    }
    ");

    var walker = new TokenWalker();
    walker.Visit(tree.GetRoot());
}