代码在视觉工作室2015上编译但在2013年失败

Question

I have this method in a class

public static DataTable ConvertCellSetToDataTable(CellSet cellSet)
{
    return new DataTable();
}

I have Microsoft.AnalysisServices.AdomdClient in my packages.config as a nuget package and I DON'T have System.Xml as a project reference.

  <package id="Microsoft.AnalysisServices.AdomdClient" version="12.0.2000.8" targetFramework="net452" />

This project fails to compile with Visual Studio 2013 Pro but the same solution file complies in Visual Stuido 2015 Pro on the same machine.

Error message from VS2013 as below:

error CS0012: The type 'System.Xml.Serialization.IXmlSerializable' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

I'm OK with this failure but why does it compile with Visual Studio 2015? What's new here?

Gist with all my files here:

https://gist.github.com/atwayne/ad8fdc06ee831626361609cfb5935638

Answer 1

It has been a while, I am quoting comment from @Hans Passant as an answer:

Roslyn is new. The C# compiler, somewhere around version 4.5, got a lot more strict about wanting to know types that are indirectly referenced. Some kind of method overloading issue, a detail that the C# language specification does not mention.