CliFx/CliFx.Analyzers/OptionMustHaveValidShortNameAnalyzer.cs

using CliFx.Analyzers.ObjectModel;
using CliFx.Analyzers.Utils.Extensions;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;

namespace CliFx.Analyzers;

[DiagnosticAnalyzer(LanguageNames.CSharp)]
public class OptionMustHaveValidShortNameAnalyzer : AnalyzerBase
{
    public OptionMustHaveValidShortNameAnalyzer()
        : base(
            "Option short names must be letter characters",
            "This option's short name must be a single letter character. " +
            "Specified short name: `{0}`.")
    {
    }

    private void Analyze(
        SyntaxNodeAnalysisContext context,
        PropertyDeclarationSyntax propertyDeclaration,
        IPropertySymbol property)
    {
        var option = CommandOptionSymbol.TryResolve(property);
        if (option is null)
            return;

        if (option.ShortName is null)
            return;

        if (!char.IsLetter(option.ShortName.Value))
        {
            context.ReportDiagnostic(
                CreateDiagnostic(
                    propertyDeclaration.Identifier.GetLocation(),
                    option.ShortName
                )
            );
        }
    }

    public override void Initialize(AnalysisContext context)
    {
        base.Initialize(context);
        context.HandlePropertyDeclaration(Analyze);
    }
}