如何在Roslyn中确定FieldDeclarationSyntax的类型是否为接口？

Question

假设有一个包含接口类型私有字段的类。使用Roslyn分析上述代码时，如何确定FieldDeclarationSyntax后面的类型是否为接口？使用下面的代码检索字段声明的ISymbol，我找不到任何类似IsInterface或类似的属性。

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

public class SampleClass
{
    public static void Main()
    {
        var str =
            @"
            namespace Sample
            {
                public interface IBar
                {
                    void Do();
                }

                public class Foo
                {
                    private IBar _bar;
                }
            }";

        var syntaxTree = SyntaxFactory.ParseSyntaxTree(str);

        var compilation = CSharpCompilation.Create("Sample", new[] { syntaxTree });

        var semanticModel = compilation.GetSemanticModel(syntaxTree, true);

        var classDeclarationSyntax =
        semanticModel.SyntaxTree.GetRoot().DescendantNodes().OfType<ClassDeclarationSyntax>().First();

        var fieldDeclarationSyntax = classDeclarationSyntax.DescendantNodes().OfType<FieldDeclarationSyntax>().First();

        var declaredSymbol = semanticModel.GetDeclaredSymbol(fieldDeclarationSyntax.Declaration.Variables.First());

        // declaredSymbol (ISymbol) contains properties like IsDefinition, IsVirtual etc. but nothing like IsInterface.
    }
}

- Konstantinos Papakonstantinou

---

当询问此类问题时，请提供一个 [mcve]，以便愿意回答的人可以轻松验证其答案是否有效，而无需创建自己的测试代码。 - NineBerry

@NineBerry 谢谢，已编辑。 - Konstantinos Papakonstantinou

Answer 1

最终，调用fieldDeclarationSyntax.Declaration.Type上的GetTypeInfo解决了问题。 完整的工作示例：

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

public class SanpleClass
{
    public static void Main()
    {
        var str =
            @"
            namespace Sample
            {
                public interface IBar
                {
                    void Do();
                }

                public class Foo
                {
                    private IBar _bar;
                }
            }";

        var syntaxTree = SyntaxFactory.ParseSyntaxTree(str);

        var compilation = CSharpCompilation.Create("Sample", new[] { syntaxTree });

        var semanticModel = compilation.GetSemanticModel(syntaxTree, true);

        var classDeclarationSyntax =
            semanticModel.SyntaxTree.GetRoot().DescendantNodes().OfType<ClassDeclarationSyntax>().First();

        var fieldDeclarationSyntax = classDeclarationSyntax.DescendantNodes().OfType<FieldDeclarationSyntax>().First();

        var typeKind = semanticModel.GetTypeInfo(fieldDeclarationSyntax.Declaration.Type).Type.TypeKind;

        var isInterface = typeKind == TypeKind.Interface;

        Console.WriteLine($"Is Interface: {isInterface}");
    }
}

- Konstantinos Papakonstantinou