SecondHalf.cs

[DiagnosticAnalyzer(LanguageNames.CSharp)]
public class Analyzer1Analyzer : DiagnosticAnalyzer
{
    ...

    public override void Initialize(AnalysisContext context)
    {
        // TODO: Consider registering other actions that act on syntax instead of or in addition to symbols
        context.RegisterSymbolAction(AnalyzeSymbol, SymbolKind.NamedType);
    }

    private static void AnalyzeSymbol(SymbolAnalysisContext context)
    {
        // TODO: Replace the following code with your own analysis, generating Diagnostic objects for any issues you find
        var namedTypeSymbol = (INamedTypeSymbol)context.Symbol;

        // Find just those named type symbols with names containing lowercase letters.
        if (namedTypeSymbol.Name.ToCharArray().Any(char.IsLower))
        {
            // For all such symbols, produce a diagnostic.
            var diagnostic = Diagnostic.Create(Rule, namedTypeSymbol.Locations[0], namedTypeSymbol.Name);

            context.ReportDiagnostic(diagnostic);
        }
    }
}