EIrwin

public bool CheckUserCredentials(){...}
public bool CheckUserCredentials(string username,string password){...}
public bool CheckUserCredentials(string username,string password,IInternalUser internalUser){...}

EIrwin

public bool CheckUserCredentials(IInternalUser internalUser){...}
public bool CheckUserCredentials(IInternalUser internalUser,string username,string password){...}

EIrwin

public void AnalyzeSymbol(ISymbol symbol, Compilation compilation, Action<Diagnostic> addDiagnostic, CancellationToken cancellationToken)
{
	var methodSymbol = (IMethodSymbol)symbol;

	//Check if any method parameters are of type IInternalUser
	if (methodSymbol.Parameters.Any(p => p.Type.Name.Contains("IInternalUser")))
	{
		var paramter = methodSymbol.Parameters.First();

		//Check if IInerternalUser type is first parameter and there is more than one expected parameters

EIrwin

public ImmutableArray<SymbolKind> SymbolKindsOfInterest { get { return ImmutableArray.Create(SymbolKind.Method); } }

EIrwin

internal const string Description = "IInternalUser parameter needs to be first in method signature";
internal const string MessageFormat = "IInternalUser parameter needs to be first in method signature";

EIrwin

public async Task<IEnumerable<CodeAction>> GetFixesAsync(Document document, TextSpan span, IEnumerable<Diagnostic> diagnostics, CancellationToken cancellationToken)
{
	SyntaxNode root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);

	SyntaxToken token = root.FindToken(span.Start);

	TextSpan diagnosticSpan = diagnostics.First().Location.SourceSpan;

	// Find the method declaration identified by the diagnostic.
	MethodDeclarationSyntax declaration = root.FindToken(diagnosticSpan.Start).Parent.AncestorsAndSelf().OfType<MethodDeclarationSyntax>().First();

EIrwin

private async Task<Document> FixIInternalUserOrdinal(Document document,MethodDeclarationSyntax methodDeclaration,CancellationToken cancellationToken)
{
	//Document to return;
	Document newDocument = null;

	//Retrieve original paramater list syntax node from method declaration
	ParameterListSyntax originalParameterListSyntax = methodDeclaration.ParameterList;

	//Retrieve original paramater list from paramater list syntax nodes
	IEnumerable <SyntaxNode> parameters = originalParameterListSyntax.ChildNodes();

EIrwin

private static void ChangeAge(ref Person person,int newAge)
{
    person = new Person(); //We CAN do this!
    person.Age = newAge;
}

EIrwin

private static void ChangeAge(Person person,int newAge)
{
    person = new Person();  //We CAN'T do this!
    person.Age = newAge;
}

EIrwin

public static void Main(string[] args)
{
    Person person = new Person();
    person.Age = 5;

    //Attempt to change 'Age' to 10
    ChangeAge(person,10);

    Console.WriteLine(person.Age);