c# - C# 泛型协方差

Question

我在 DerivedFileInfo 类声明中遇到错误。

错误：类型“StorageManager.Test.DerivedStorageProvider”不能用作泛型类型或方法“StorageManager.Test.BaseFileInfo”中的类型参数“TStorageProvider”。没有从“StorageManager.Test.DerivedStorageProvider”到“StorageManager.Test.IStorageProvider”的隐式引用转换。

通用约束是否缺少某些东西，或者我需要通用协变？

public interface ICacheProvider
{
}

public class BaseCacheProvider : ICacheProvider
{
}

public class DerivedCacheProvider : BaseCacheProvider
{

}

public interface IStorageProvider<TCacheProvider> where TCacheProvider : ICacheProvider
{
}

public abstract class BaseStorageProvider<TCacheProvider> : IStorageProvider<TCacheProvider> where TCacheProvider : ICacheProvider
{
}

public class DerivedStorageProvider : BaseStorageProvider<DerivedCacheProvider>
{
}

public interface IResourceInfo<TStorageProvider> where TStorageProvider : IStorageProvider<ICacheProvider>
{
}

public abstract class ResourceInfo<TStorageProvider> : IResourceInfo<TStorageProvider>
    where TStorageProvider : IStorageProvider<ICacheProvider>
{
}

public abstract class BaseFileInfo<TStorageProvider> : ResourceInfo<TStorageProvider> where TStorageProvider : IStorageProvider<ICacheProvider>
{
}

public class DerivedFileInfo : BaseFileInfo<DerivedStorageProvider>
{ 
}