相关疑难解决方法(0)

我有一个场景,我想使用方法组语法而不是匿名方法(或lambda语法)来调用函数.

该函数有两个重载,一个需要一个Action,另一个需要一个Func<string>.

我可以愉快地使用匿名方法(或lambda语法)调用两个重载,但如果我使用方法组语法,则会获得Ambiguous调用的编译器错误.我可以明确的解决方法铸造到Action或Func<string>,但不认为这应该是必要的.

任何人都可以解释为什么应该要求显式演员表.

代码示例如下.

class Program
{
    static void Main(string[] args)
    {
        ClassWithSimpleMethods classWithSimpleMethods = new ClassWithSimpleMethods();
        ClassWithDelegateMethods classWithDelegateMethods = new ClassWithDelegateMethods();

        // These both compile (lambda syntax)
        classWithDelegateMethods.Method(() => classWithSimpleMethods.GetString());
        classWithDelegateMethods.Method(() => classWithSimpleMethods.DoNothing());

        // These also compile (method group with explicit cast)
        classWithDelegateMethods.Method((Func<string>)classWithSimpleMethods.GetString);
        classWithDelegateMethods.Method((Action)classWithSimpleMethods.DoNothing);

        // These both error with "Ambiguous invocation" (method group)
        classWithDelegateMethods.Method(classWithSimpleMethods.GetString);
        classWithDelegateMethods.Method(classWithSimpleMethods.DoNothing);
    }
}

class ClassWithDelegateMethods
{
    public void Method(Func<string> func) { /* do something …

我偶然发现了这种（在我看来是错误的）奇怪的行为，如果有人能告诉我为什么编译器会这样，或者也许我很幸运并发现了编译器错误，我将不胜感激;-)

全部都是针对 .net6.0 编译的（使用 VS 2022）

这是代码的第一个版本：

internal class Program
{

    private static void Main(string[] args)
    {
        long longValue = 0;
        string stringValue = "";
        bool boolValue = false;
        DateTime dateTimeValue = DateTime.Now;
        double doubleValue = 0;

        Console.Write("expect long => ");
        SetValue(val => longValue = val);

        Console.Write("expect string => ");
        SetValue(val => stringValue = val);

        Console.Write("expect bool => ");
        SetValue(val => boolValue = val);

        Console.Write("expect DateTime => ");
        SetValue(val => dateTimeValue = val);

        Console.ReadKey();
    }

    private static void SetValue(Action<long> setter) …