Getting the fully qualified name of a type from a TypeInfo object

Question

Is it somehow possible to get the fully qualified name of the type contained in a TypeInfo object?

In the debugger many of these values nicely show up as

Answer 1

I couldn't find something built-in either and I'm quite sure this isn't the most elegant way, but it worked for me to construct a qualified type name like this:

private static string GetQualifiedTypeName(ISymbol symbol)
{
    return symbol.ContainingNamespace 
        + "." + symbol.Name 
        + ", " + symbol.ContainingAssembly;
}

If you don't need an assembly qualified type name don't concatenate ContainingAssembly at the end of the last line.

Answer 2

Using the semantic model you can also do it like i did it here:

var typeInfo = context.SemanticModel.GetTypeInfo(identifierNameSyntax);
var namedType = typeInfo.Type as INamedTypeSymbol;
if (namedType != null && namedType.Name == nameof(ConfiguredTaskAwaitable) && GetFullNamespace(namedType) == typeof(ConfiguredTaskAwaitable).Namespace)
    return true;

where "GetFullNamespace" works like this:

    public static IEnumerable<string> GetNamespaces(INamedTypeSymbol symbol)
    {
        var current = symbol.ContainingNamespace;
        while (current != null)
        {
            if (current.IsGlobalNamespace)
                break;
            yield return current.Name;
            current = current.ContainingNamespace;
        }
    }

    public static string GetFullNamespace(INamedTypeSymbol symbol)
    {
        return string.Join(".", GetNamespaces(symbol).Reverse());
    }

    public static string GetFullTypeName(INamedTypeSymbol symbol)
    {
        return string.Join(".", GetNamespaces(symbol).Reverse().Concat(new []{ symbol.Name }));
    }

Obviously Jason Malinowski's answer is more convenient for simple cases

Answer 3

The ToDisplayString method lets you pass in a "format" object which has a huge number of options for controlling how you want to format stuff:

var symbolDisplayFormat = new SymbolDisplayFormat(
    typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypesAndNamespaces);

string fullyQualifiedName = typeSymbol.ToDisplayString(symbolDisplayFormat);

The reason your getting keywords like "int" is the default format is including the SymbolDisplayMiscellaneousOptions.UseSpecialTypes flag which specifies to use the language keywords for special types vs. the regular name.