Create and use a Roslyn analyzer

1. In your IDE, create a C# class library project that targets .NET Standard 2.0 and name the project

   ExampleAnalyzer

   .
2. Install the

   Microsoft.CodeAnalysis.Csharp

   NuGet package for the project. Your analyzer must use Microsoft.CodeAnalysis.Csharp 4.3 to work with Unity.
3. In your IDE project, create a new C# file and add the following code:

   using System.Collections.Immutable;using Microsoft.CodeAnalysis;using Microsoft.CodeAnalysis.CSharp;using Microsoft.CodeAnalysis.CSharp.Syntax;using Microsoft.CodeAnalysis.Diagnostics;namespace ExampleAnalyzer{[DiagnosticAnalyzer(LanguageNames.CSharp)]public class DebugLogAnalyzer : DiagnosticAnalyzer{    public const string DiagnosticId = "EX0001";    private static readonly LocalizableString Title =        "Avoid using Debug.Log";    private static readonly LocalizableString MessageFormat =        "Debug.Log call detected - consider removing it before shipping";    private static readonly LocalizableString Description =        "Debug.Log calls can impact performance and clutter the console in production builds.";    private const string Category = "Usage";    private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(        DiagnosticId,        Title,        MessageFormat,        Category,        DiagnosticSeverity.Warning,        isEnabledByDefault: true,        description: Description);    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>        ImmutableArray.Create(Rule);    public override void Initialize(AnalysisContext context)    {        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);        context.EnableConcurrentExecution();        context.RegisterSyntaxNodeAction(AnalyzeInvocation, SyntaxKind.InvocationExpression);    }    private static void AnalyzeInvocation(SyntaxNodeAnalysisContext context)    {        var invocation = (InvocationExpressionSyntax)context.Node;        if (!(invocation.Expression is MemberAccessExpressionSyntax memberAccess))            return;        // Match calls where the method name is "Log"        if (memberAccess.Name.Identifier.Text != "Log")            return;        // Verify the symbol belongs to UnityEngine.Debug        var symbolInfo = context.SemanticModel.GetSymbolInfo(memberAccess);        if (!(symbolInfo.Symbol is IMethodSymbol methodSymbol))            return;        var containingType = methodSymbol.ContainingType;        if (containingType?.ToDisplayString() != "UnityEngine.Debug")            return;        var diagnostic = Diagnostic.Create(Rule, memberAccess.GetLocation());        context.ReportDiagnostic(diagnostic);    }}}

4. Build your analyzer with a release build configuration.
5. In your analyzer's project folder, find the

   bin/Release/netstandard2.0/ExampleAnalyzer.dll

   file.
6. Copy this file into your Unity project, inside the

   Assets

   folder.
7. Inside the Asset Browser, click on the .dll file to open the Plugin Inspector window.
8. Under Select platforms for plugin, uncheck Any Platform.
9. Under Include Platforms, uncheck Editor and Standalone and any other checked platforms.
10. Under Asset Labels, click on the label icon to open the Asset labels sub-menu.
11. Create and assign a new label called RoslynAnalyzer. To do this, type

    RoslynAnalyzer

    in the text input field of the Asset labels sub-menu and press Enter. This label must match exactly and is case sensitive. Once created, the label appears in the Asset labels sub-menu from then on. You can click on the name of the label in the menu to assign it to other analyzers.
12. To test the analyzer is working, create a new MonoBehaviour script in the Editor with the following code:

    using UnityEngine;public class TestScript : MonoBehaviour{    void Start()    {        Debug.Log("Hello world"); // Should trigger EX0001 warning    }}

TestScript.cs(8,9): warning EX0001: Debug.Log call detected - consider removing it before shipping

Report analyzer diagnostics

Additional resources

• Install and use an existing analyzer or source generator
• Create and use a source generator