在C#增量源生成器（IIncrementalGenerator）中获取基类属性

我在源生成器中编写了如下Execute方法，能够获取当前类的所有属性（通过x.Item1.Members.AsEnumerable()...），但无法获取基类的属性。请问如何列出基类的所有属性？

private static void Execute(Compilation compilation, ImmutableArray<(ClassDeclarationSyntax, AttributeData)> classes, SourceProductionContext context)
{
    foreach (var (x, i) in classes.Select((x, i) => (x, i)))
    {
        TypedConstant aggregateParam = x.Item2.ConstructorArguments[0];
        if (aggregateParam.Kind == TypedConstantKind.Primitive &&
            aggregateParam.Value is string fullyQualifiedAggregateName)
        {
            var aggregateName = "Aggregate";

            var props = x.Item1.Members.AsEnumerable().Where(o => o.IsKind(SyntaxKind.PropertyDeclaration));

            var sb = new StringBuilder();

            context.AddSource(
                $"generated_{aggregateName}_{i}.g.cs",
                sb.ToString());
        }
    }
}

更新

public void Initialize(IncrementalGeneratorInitializationContext context)
{
    IncrementalValuesProvider<(ClassDeclarationSyntax, AttributeData)> classDeclarations = context.SyntaxProvider
        .ForAttributeWithMetadataName(
            EventApplyAttribute,
            predicate: static (node, _) => node is ClassDeclarationSyntax,
            transform: static (ctx, ct) => GetSemanticTargetForGeneration(ctx, ct))
        .Where(m => m.Item1 is not null && m.Item2 is not null);

    IncrementalValueProvider<(Compilation, ImmutableArray<(ClassDeclarationSyntax, AttributeData)>)> compilationAndClasses
        = context.CompilationProvider.Combine(classDeclarations.Collect());

    context.RegisterSourceOutput(compilationAndClasses,
        static (spc, source) => Execute(source.Item1, source.Item2, spc));
}

private static (ClassDeclarationSyntax, AttributeData) GetSemanticTargetForGeneration(GeneratorAttributeSyntaxContext context, CancellationToken ct)
{
    if (context.TargetNode is not ClassDeclarationSyntax classDeclaration)
    {
        return (null, null);
    }

    AttributeData? attribute = context.Attributes.FirstOrDefault(a => a.AttributeClass?.Name == "EventApplyAttribute");

    return (classDeclaration, attribute);
}

仅通过语法节点ClassDeclarationSyntax只能获取当前类定义的成员，要拿到基类属性，必须借助语义分析，通过类的符号INamedTypeSymbol遍历整个继承链。

具体实现步骤 #

1. 获取类的语义符号
   在Execute方法中，利用编译实例和语法节点获取对应的类符号：

var semanticModel = compilation.GetSemanticModel(x.Item1.SyntaxTree);
if (semanticModel.GetDeclaredSymbol(x.Item1, context.CancellationToken) is not INamedTypeSymbol classSymbol)
{
    continue;
}

2. 编写辅助方法遍历继承链
   递归或循环遍历类的基类，收集所有非编译器自动生成的属性：

static IEnumerable<IPropertySymbol> GetAllProperties(INamedTypeSymbol typeSymbol, CancellationToken ct)
{
    var currentType = typeSymbol;
    var properties = new List<IPropertySymbol>();

    while (currentType != null)
    {
        // 筛选当前类的属性，排除编译器合成的隐式成员
        properties.AddRange(currentType.GetMembers()
            .OfType<IPropertySymbol>()
            .Where(p => !p.IsImplicitlyDeclared));
        
        // 移动到下一层基类
        currentType = currentType.BaseType;
        ct.ThrowIfCancellationRequested();
    }

    return properties;
}

3. 替换原有属性获取逻辑
   在Execute中调用辅助方法，替换原来仅获取当前类属性的代码：

// 替换原props获取逻辑
var allProperties = GetAllProperties(classSymbol, context.CancellationToken);
// 可按需筛选，比如只保留公共属性：
// var publicProps = allProperties.Where(p => p.DeclaredAccessibility == Accessibility.Public);

修改后的完整Execute方法示例 #

private static void Execute(Compilation compilation, ImmutableArray<(ClassDeclarationSyntax, AttributeData)> classes, SourceProductionContext context)
{
    foreach (var (x, i) in classes.Select((x, i) => (x, i)))
    {
        TypedConstant aggregateParam = x.Item2.ConstructorArguments[0];
        if (aggregateParam.Kind == TypedConstantKind.Primitive &&
            aggregateParam.Value is string fullyQualifiedAggregateName)
        {
            var aggregateName = "Aggregate";

            // 获取语义模型与类符号
            var semanticModel = compilation.GetSemanticModel(x.Item1.SyntaxTree);
            if (semanticModel.GetDeclaredSymbol(x.Item1, context.CancellationToken) is not INamedTypeSymbol classSymbol)
            {
                continue;
            }

            // 获取当前类及所有基类的属性
            var allProperties = GetAllProperties(classSymbol, context.CancellationToken);

            var sb = new StringBuilder();
            // 此处可使用allProperties生成目标代码

            context.AddSource(
                $"generated_{aggregateName}_{i}.g.cs",
                sb.ToString());
        }
    }
}

static IEnumerable<IPropertySymbol> GetAllProperties(INamedTypeSymbol typeSymbol, CancellationToken ct)
{
    var currentType = typeSymbol;
    var properties = new List<IPropertySymbol>();

    while (currentType != null)
    {
        properties.AddRange(currentType.GetMembers()
            .OfType<IPropertySymbol>()
            .Where(p => !p.IsImplicitlyDeclared));
        
        currentType = currentType.BaseType;
        ct.ThrowIfCancellationRequested();
    }

    return properties;
}

注意事项 #

• 必须处理取消令牌CancellationToken，避免生成器运行阻塞
• 可根据需求添加筛选条件，比如仅保留公共属性、排除抽象属性等
• 继承链终点为object类，此时currentType.BaseType会返回null，循环自动终止

内容的提问来源于stack exchange，提问作者Dani