成员访问运算符(.)的优先级是否高于空条件成员访问运算符(?)?

我想我们都同意空条件成员访问操作符 ?.

using System.Collections.Generic;

public class MyClass
{
    public void DoSomething(Foo foo)
    {
        var knownIndices = new[] { 42 };
        bool overlaps;

        // might throw a null reference exception
        overlaps = foo.Indices.Overlaps(knownIndices);

        // how I used to do it
        overlaps = foo != null && foo.Indices != null && foo.Indices.Overlaps(knownIndices);

        // with null conditional member access (won't compile)
        //overlaps = foo?.Indices?.Overlaps(knownIndices).GetValueOrDefault();

        // with null conditional member access (using local variable)
        bool? overlapsOrIsIndeterminable = foo?.Indices?.Overlaps(knownIndices);
        overlaps = overlapsOrIsIndeterminable.GetValueOrDefault();

        // with null conditional member access (inlined)
        overlaps = (foo?.Indices?.Overlaps(knownIndices)).GetValueOrDefault();

        // with null conditional member access and null-coalescing
        overlaps = foo?.Indices?.Overlaps(knownIndices) ?? false;
    }

    public class Foo
    {
        public HashSet<int> Indices;
    }
}

为什么要在链式表达式中使用括号? ?.Overlaps() 很明显,计算结果是一个可为null的bool,正如我们在使用局部变量的示例中所看到的,所以我希望 .GetValueOrDefault()

The C# language reference 声明成员访问运算符 . ?.

做 . ?. ?