CliFx/CliFx.Analyzers/OptionMustHaveValidConverterAnalyzer.cs

using System.Linq;
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 OptionMustHaveValidConverterAnalyzer : AnalyzerBase
{
    public OptionMustHaveValidConverterAnalyzer()
        : base(
            $"Option converters must derive from `{SymbolNames.CliFxBindingConverterClass}`",
            $"Converter specified for this option must derive from `{SymbolNames.CliFxBindingConverterClass}`.")
    {
    }

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

        if (option.ConverterType is null)
            return;

        // We check against an internal interface because checking against a generic class is a pain
        var converterImplementsInterface = option
            .ConverterType
            .AllInterfaces
            .Any(s => s.DisplayNameMatches(SymbolNames.CliFxBindingConverterInterface));

        if (!converterImplementsInterface)
        {
            context.ReportDiagnostic(CreateDiagnostic(propertyDeclaration.GetLocation()));
        }
    }

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