Why C# 6.0 features could be used in manual plugin (dll) but not able to compile when used as Unity Script directly?

Hi all,

For example, following code used Auto-Property Initializers which is introduced as a C# 6.0 feature.

public string Name { get; }

So when running it directly from Editor, it will throw following error:

 *Assets/Test.cs(6,30): error CS0840: `Test.Name.get' must have a body because it is not marked abstract or extern. The property can be automatically implemented when you define both accessors*

While it is built into a dll file and then used from Unity, then it could pass.

BTW, I have noticed that Unity Editor is running on Mono version 2.6.5 while MonoDevelop is on 4.0.5. My Unity version is 5.4.2f2.