Avalonia/XamlNameReferenceGenerator/NameReferenceSyntaxReceiver.cs

using System.Collections.Generic;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace XamlNameReferenceGenerator
{
    internal class NameReferenceSyntaxReceiver : ISyntaxReceiver
    {
        public List<ClassDeclarationSyntax> CandidateClasses { get; } = new List<ClassDeclarationSyntax>();

        public void OnVisitSyntaxNode(SyntaxNode syntaxNode)
        {
            if (syntaxNode is ClassDeclarationSyntax classDeclarationSyntax &&
                classDeclarationSyntax.AttributeLists.Count > 0)
                CandidateClasses.Add(classDeclarationSyntax);
        }
    }
}