Roslyn EndOfFile

DiagnosticAnalyzer

[DiagnosticAnalyzer]
[ExportDiagnosticAnalyzer(DiagnosticId, LanguageNames.CSharp)]
public class DiagnosticAnalyzer : ISyntaxTreeAnalyzer
{
    internal const string DiagnosticId = "EndOfFile";
    internal const string Description = "No blank lines at the end of the file please.";
    internal const string MessageFormat = "No blank lines at the end of the file please.";
    internal const string Category = "Naming";

    internal static DiagnosticDescriptor Rule = new DiagnosticDescriptor(DiagnosticId, Description, MessageFormat, Category, DiagnosticSeverity.Warning);

    public ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get { return ImmutableArray.Create(Rule); } }

    public void AnalyzeSyntaxTree(SyntaxTree tree, Action<Diagnostic> addDiagnostic, CancellationToken cancellationToken)
    {
        var root = tree.GetRoot();

        var eofToken = root.DescendantTokens().Where(x => x.IsKind(SyntaxKind.EndOfFileToken)).First();

        var leadingTrivia = eofToken.LeadingTrivia;
        var leadingBlankLines = eofToken.LeadingTrivia.Where(x => x.IsKind(SyntaxKind.EndOfLineTrivia));

        foreach (var blankline in leadingBlankLines)
        {
            addDiagnostic(Diagnostic.Create(Rule, blankline.GetLocation()));
        }
    }
}