为什么此C＃代码具有未声明的get主体构建？ 以及如何使编译器对此产生错误？

Question

To my surprise, the following code builds and runs fine:

private abstract class MyParent
{
    public abstract bool MyBool { get; }
}

private class MyChild : MyParent
{
    public override bool MyBool { get; } //no body declared
}

[TestMethod]
public void MyTestMethod()
{
    var mc = new MyChild();
    Assert.IsFalse(mc.MyBool);
}

I don't get any warnings either. The test even passes. I wouldn't expect this to compile because the MyChild class doesn't declare a body for the overridden MyBool getter. I tried marking the MyChild class sealed , but it still compiled. My first question is simply, why is the MyChild class not required to provide a body for the MyBool getter?

I found that I had a problem like this in my code because my build server reported a compiler error that said:

'MyChild.MyBool.get' must declare a body because it is not marked abstract or extern. Automatically implemented properties must define both get and set accessors.

The build server must be using some settings that prevented this same code from compiling. My second question is: what settings can I check to ensure that the compiler gives me this warning when I try to compile this code?

Answer 1

I wouldn't expect this to compile because the MyChild class doesn't declare a body for the overridden MyBool getter.

That is because it is perfectly fine. The MyBool property has an (implicit) setter, but that is only available to the constructor. This is a new feature to the C# 6 compiler, so your build server needs the same version of the compiler to make this work.

There is no need to throw an exception, or anything like that. If you want a set to be declared, just make sure to add it to the property definition in the base class.