Enable latest C# language version for Unity

enable-latest-csharp-lang-version-for-unity.md

Introduction

Follow the following steps to enable the latest C# syntax for your Unity project.

Only tested with Scripting Backend set to Mono and Api Compatibility Level set to .NET Standard 2.1.

Step 1: For Editor Player

In Edit > Project Settings... > Player > Other Settings > Additional Compiler Arguments, add /langversion:latest, then Apply.

Step 2: For Generated VS Projects

Put LangVersionPostprocessor.cs under the <project_root>/Assets/Standard Assets/Editor folder.

You may change its filename and classname.

LangVersionPostprocessor.cs

using System.Text.RegularExpressions;
using UnityEditor;

/// <remarks>
/// This class need to be placed in Assets/Standard Assets/Editor folder to be compiled before other scripts.
/// See <see href="https://docs.unity3d.com/Manual/ScriptCompileOrderFolders.html"/>.
/// </remarks>
internal sealed class LangVersionPostprocessor : AssetPostprocessor {
    private static string OnGeneratedCSProject(string path, string content) {
        var pattern = @"<LangVersion>(.*?)<\/LangVersion>";
        var replacement = "<LangVersion>latest</LangVersion>";
        content = Regex.Replace(content, pattern, replacement);
        return content;
    }
}