Install and use an existing analyzer or source generator

This example uses the ErrorProne.NET.CoreAnalyzers library to demonstrate how to install code analyzers or source generators from NuGet:

1. Download the library as a .zip file with the Download package button.
2. Extract the contents of the .zip file.
3. Inside the extracted folder, locate the .dll files that contain the analyzers. In this example, navigate to errorprone.net.coreanalyzers<version-number>\analyzers\dotnet\cs. The required files should be in this folder, named ErrorProne.NET.Core.dll, ErrorProne.Net.CoreAnalyzers.dll, and RuntimeContracts.dll.
4. Move these files into the Assets folder, or any folder nested inside of the Assets folder, in your Unity project. To do this, either go to Assets > Import new asset and select the .dll for each of the three files, or copy them into your project’s Assets folder through your device’s file browser.
5. Click on the .dll file inside the Asset Browser inside Unity to open the Plugin Inspector window.
6. Inside the Plugin InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
   See in Glossary window:
   • Under the Select platforms for plugin heading, disable Any Platform.
   • Under the Include Platforms heading, disable Editor and Standalone.
7. Under the Asset Labels heading in the Plugin Inspector window, click on the blue label icon to open the Asset Labels sub-menu.
8. Create and assign a new label called RoslynAnalyzer. To do this, type RoslynAnalyzer into the text input window in the Asset Labels sub-menu and press Return. This label must exactly match the example and is case sensitive. After you create the label for the first analyzer, it appears on the list of available labels in the Asset Labels sub-menu. You can click on the name of the label in the menu to assign it to other analyzers.

Unity recognizes the RoslynAnalyzer label and treats assets with this label as Roslyn Analyzers or source generators. When you assign the label to an analyzer, Unity recompiles scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary within the scope of the analyzer and analyzes the code in those scripts according to the rules in the analyzer. Any scripts that are within the same assembly definition as an analyzer are in that analyzer’s scope. For analyzers in the root level of the Assets folder, Unity considers all files in the project to be in scope. For more information about scope, refer to Analyzer scope and diagnostics.

To test that your analyzers work correctly, follow the example below. If you have installed the analyzers correctly, the ErrorProne.NET analyzer raises warnings when it analyzes the code in the example.

Create a new script file named RethrowError.cs. Copy the following code into this script and save the file:

using System;
using UnityEngine;

public class RethrowError : MonoBehaviour
{
    void Update()
    {
        try
        {
            DoSomethingInteresting();
        }
        catch (Exception e)
        {
            Debug.Log(e.Message);
            throw e;
        }
    }

    private void DoSomethingInteresting()
    {
        throw new System.NotImplementedException();
    }
}

When you save the file, Unity recompiles the script and runs any applicable analyzers on the script’s code. When the ErrorProne.NET analyzer is correctly installed, it raises the following warnings in the Console windowA Unity Editor window that shows errors, warnings and other messages generated by Unity, or your own scripts. More info
See in Glossary about the above code:

Assets\RethrowError.cs(14,23): warning EPC12: Suspicious exception handling: only e.Message is observed in exception block.

Assets\RethrowError.cs(15,19): warning ERP021: Incorrect exception propagation. Use throw; instead.

Additional resources

• Create and use a source generator
• Create rule set files