C＃方法重载分辨率不选择具体的泛型覆盖(C# Method overload resolution not selecting concrete generic override)

 这个完整的C＃程序说明了这个问题： 
 
public abstract class Executor<T>
{
    public abstract void Execute(T item);
}

class StringExecutor : Executor<string>
{
    public void Execute(object item)
    {
        // why does this method call back into itself instead of binding
        // to the more specific "string" overload.
        this.Execute((string)item);
    }

    public override void Execute(string item) { }
}

class Program
{
    static void Main(string[] args)
    {
        object item = "value";
        new StringExecutor()
            // stack overflow
            .Execute(item); 
    }
}
 
 我碰到一个StackOverlowException，我追溯到这个调用模式，我试图将呼叫转移到更具体的重载。 令我吃惊的是，调用并没有选择更具体的重载，而是回调本身。 它显然与基本类型是通用的有关，但我不明白为什么它不会选择Execute（string）重载。 
 
 有人有任何洞察力吗？ 
 
 上面的代码被简化为显示模式，实际结构有点复杂，但问题是一样的。 

This complete C# program illustrates the issue:
 
public abstract class Executor<T>
{
    public abstract void Execute(T item);
}

class StringExecutor : Executor<string>
{
    public void Execute(object item)
    {
        // why does this method call back into itself instead of binding
        // to the more specific "string" overload.
        this.Execute((string)item);
    }

    public override void Execute(string item) { }
}

class Program
{
    static void Main(string[] args)
    {
        object item = "value";
        new StringExecutor()
            // stack overflow
            .Execute(item); 
    }
}
 
I ran into a StackOverlowException that I traced back to this call pattern where I was trying to forward calls to a more specific overload. To my surprise, the invocation was not selecting the more specific overload however, but calling back into itself. It clearly has something to do with the base type being generic, but I don't understand why it wouldn't select the Execute(string) overload.
 
Does anyone have any insight into this?
 
The above code was simplified to show the pattern, the actual structure is a bit more complicated, but the issue is the same.

原文：https://stackoverflow.com/questions/43105763