How can I use C# 8 with Visual Studio 2017?

Question

I\'d like to use C# 8.0 (especially ranges and non-nullable reference types) in Visual Studio 2017. Is it possible?

Answer 1

Going forward, Microsoft want to tie C# language versions more closely to framework versions than they have in the past. They really only want you to be using C# 8 with .NET Core 3.x and .NET Standard 2.1 projects, and that means using Visual Studio 2019. My answer to Does C# 8 support the .NET Framework? has all the gory details.

However, if you really want to you can now use C# 8 in Visual Studio 2017 by using the same trick that brings C# 7 to Visual Studio 2015: install the latest version of the Microsoft.Net.Compilers Nuget package into the project. It works, but of course VS 2017 doesn't know about C# 8 syntax so it doesn't look very pretty. Here's a screenshot showing that VS 2017 is able to compile a small test library using nullable reference types and a static local method (both of which are C# 8 features):

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Here's the .csproj and code if you want to try it:

  
    netstandard2.0;net452
    8.0    
    enable
  
  
    
      all
      runtime; build; native; contentfiles; analyzers
    
  

-

using System;

namespace CSharp8Test
{
    public class Class1
    {
        public string? NullableString { get; } = "Test";

        public static void Test()
        {
            Console.WriteLine(Test2());
            static int Test2() => 5;
        }
    }
}