feat: add analyzer for correct AfterAutoHandleStateEvent usage (#6117)

* feat: add analyzer for AfterAutoHandleStateEvent

* fix: correct TestOf attribute

Oopsieeeee.

Also weird newline plus unused import.

* Rerun content tests

* refactor: use ==, not .Contains

* feat: make AttributeHelper.HasAttribute looser

* refactor: use AttributeHelper.HasAttribute

* perf: cache AutoGenStateAttribute's type

* refactor: more pattern matching

ElementAtOrDefault with constant arg is bad; just use positional
matching.

RELEASE-NOTES.md

@@ -35,7 +35,9 @@ END TEMPLATE-->
 
 ### Breaking changes
 
-*None yet*
+* A new analyzer has been added that will error if you attempt to subscribe to `AfterAutoHandleStateEvent` on a
+  component that doesn't have the `AutoGenerateComponentState` attribute, or doesn't have the first argument of that
+  attribute set to `true`. In most cases you will want to set said argument to `true`.
 
 ### New features
 
@@ -43,6 +45,7 @@ END TEMPLATE-->
 * added **IConfigurationManager**.*SubscribeMultiple* ext. method to provide simpler way to unsubscribe from multiple cvar at once
 * Added `SharedMapSystem.QueueDeleteMap`, which deletes a map with the specified MapId in the next tick.
 * Added generic version of `ComponentRegistry.TryGetComponent`.
+* `AttributeHelper.HasAttribute` has had an overload's type signature loosened from `INamedTypeSymbol` to `ITypeSymbol`.
 
 ### Bugfixes
 

Robust.Analyzers.Tests/AfterAutoHandleStateAnalyzerTest.cs

@@ -0,0 +1,117 @@
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp.Testing;
+using Microsoft.CodeAnalysis.Testing;
+using NUnit.Framework;
+using VerifyCS =
+    Microsoft.CodeAnalysis.CSharp.Testing.CSharpAnalyzerVerifier<Robust.Analyzers.AfterAutoHandleStateAnalyzer,
+        Microsoft.CodeAnalysis.Testing.DefaultVerifier>;
+
+namespace Robust.Analyzers.Tests;
+
+[Parallelizable(ParallelScope.All | ParallelScope.Fixtures)]
+[TestFixture, TestOf(typeof(AfterAutoHandleStateAnalyzer))]
+public sealed class AfterAutoHandleStateAnalyzerTest
+{
+    private const string SubscribeEventDef = """
+        using System;
+        namespace Robust.Shared.GameObjects;
+
+        public readonly struct EntityUid;
+
+        public abstract class EntitySystem
+        {
+            public void SubscribeLocalEvent<T, TEvent>() where TEvent : notnull { }
+        }
+
+        public interface IComponent;
+        public interface IComponentState;
+        """;
+
+    // A rare case for block-scoped namespace, I thought. Then I realized this
+    // only needed the one type definition.
+    private const string OtherTypeDefs = """
+        using System;
+
+        namespace JetBrains.Annotations
+        {
+            public sealed class BaseTypeRequiredAttribute(Type baseType) : Attribute;
+        }
+        """;
+
+    private static Task Verifier(string code, params DiagnosticResult[] expected)
+    {
+        var test = new CSharpAnalyzerTest<AfterAutoHandleStateAnalyzer, DefaultVerifier>
+        {
+            TestState = { Sources = { code } }
+        };
+
+        TestHelper.AddEmbeddedSources(test.TestState,
+            "Robust.Shared.Analyzers.ComponentNetworkGeneratorAuxiliary.cs",
+            "Robust.Shared.GameObjects.EventBusAttributes.cs");
+
+        test.TestState.Sources.Add(("EntitySystem.Subscriptions.cs", SubscribeEventDef));
+        test.TestState.Sources.Add(("Types.cs", OtherTypeDefs));
+
+        test.TestState.ExpectedDiagnostics.AddRange(expected);
+
+        return test.RunAsync();
+    }
+
+    [Test]
+    public async Task Test()
+    {
+        const string code = """
+            using Robust.Shared.Analyzers;
+            using Robust.Shared.GameObjects;
+
+            [AutoGenerateComponentState(true)]
+            public sealed class AutoGenTrue;
+            [AutoGenerateComponentState(true, true)]
+            public sealed class AutoGenTrueTrue;
+
+            public sealed class NotAutoGen;
+            [AutoGenerateComponentState]
+            public sealed class AutoGenNoArgs;
+            [AutoGenerateComponentState(false)]
+            public sealed class AutoGenFalse;
+            [AutoGenerateComponentState(RaiseAfterAutoHandleState = true)]
+            public sealed class AutoGenIncorrectConstructorArg;
+
+            public sealed class Foo : EntitySystem
+            {
+                public void Good()
+                {
+                    // Subscribing to other events works
+                    SubscribeLocalEvent<AutoGenNoArgs, object>();
+                    // First arg true allows subscribing
+                    SubscribeLocalEvent<AutoGenTrue, AfterAutoHandleStateEvent>();
+                    SubscribeLocalEvent<AutoGenTrueTrue, AfterAutoHandleStateEvent>();
+                }
+
+                public void Bad()
+                {
+                    // Can't subscribe if AutoGenerateComponentState isn't even present
+                    SubscribeLocalEvent<NotAutoGen, AfterAutoHandleStateEvent>();
+
+                    // Can't subscribe if first arg is not specified/false
+                    SubscribeLocalEvent<AutoGenNoArgs, AfterAutoHandleStateEvent>();
+                    SubscribeLocalEvent<AutoGenFalse, AfterAutoHandleStateEvent>();
+
+                    // Can't subscribe with RaiseAfterAutoHandleState = true because that's
+                    // secretly a no-op.
+                    SubscribeLocalEvent<AutoGenIncorrectConstructorArg, AfterAutoHandleStateEvent>();
+                }
+            }
+            """;
+
+        await Verifier(code,
+            // /0/Test0.cs(31,9): error RA0040: Tried to subscribe to AfterAutoHandleStateEvent for 'NotAutoGen' which doesn't have an AutoGenerateComponentState attribute
+            VerifyCS.Diagnostic(AfterAutoHandleStateAnalyzer.MissingAttribute).WithSpan(31, 9, 31, 69).WithArguments("NotAutoGen"),
+            // /0/Test0.cs(34,9): error RA0041: Tried to subscribe to AfterAutoHandleStateEvent for 'AutoGenNoArgs' which doesn't have RaiseAfterAutoHandleState set
+            VerifyCS.Diagnostic(AfterAutoHandleStateAnalyzer.MissingAttributeParam).WithSpan(34, 9, 34, 72).WithArguments("AutoGenNoArgs"),
+            // /0/Test0.cs(35,9): error RA0041: Tried to subscribe to AfterAutoHandleStateEvent for 'AutoGenFalse' which doesn't have RaiseAfterAutoHandleState set
+            VerifyCS.Diagnostic(AfterAutoHandleStateAnalyzer.MissingAttributeParam).WithSpan(35, 9, 35, 71).WithArguments("AutoGenFalse"),
+            // /0/Test0.cs(39,9): error RA0041: Tried to subscribe to AfterAutoHandleStateEvent for 'AutoGenIncorrectConstructorArg' which doesn't have RaiseAfterAutoHandleState set
+            VerifyCS.Diagnostic(AfterAutoHandleStateAnalyzer.MissingAttributeParam).WithSpan(39, 9, 39, 89).WithArguments("AutoGenIncorrectConstructorArg")        );
+    }
+}

Robust.Analyzers.Tests/Robust.Analyzers.Tests.csproj

@@ -10,6 +10,7 @@
   <ItemGroup>
     <EmbeddedResource Include="..\Robust.Shared\Analyzers\AccessAttribute.cs" LogicalName="Robust.Shared.Analyzers.AccessAttribute.cs" LinkBase="Implementations" />
     <EmbeddedResource Include="..\Robust.Shared\Analyzers\AccessPermissions.cs" LogicalName="Robust.Shared.Analyzers.AccessPermissions.cs" LinkBase="Implementations" />
+    <EmbeddedResource Include="..\Robust.Shared\Analyzers\ComponentNetworkGeneratorAuxiliary.cs" LogicalName="Robust.Shared.Analyzers.ComponentNetworkGeneratorAuxiliary.cs" LinkBase="Implementations" />
     <EmbeddedResource Include="..\Robust.Shared\Analyzers\MustCallBaseAttribute.cs" LogicalName="Robust.Shared.IoC.MustCallBaseAttribute.cs" LinkBase="Implementations" />
     <EmbeddedResource Include="..\Robust.Shared\Analyzers\PreferNonGenericVariantForAttribute.cs" LogicalName="Robust.Shared.Analyzers.PreferNonGenericVariantForAttribute.cs" LinkBase="Implementations" />
     <EmbeddedResource Include="..\Robust.Shared\Analyzers\PreferOtherTypeAttribute.cs" LogicalName="Robust.Shared.Analyzers.PreferOtherTypeAttribute.cs" LinkBase="Implementations" />

Robust.Analyzers/AfterAutoHandleStateAnalyzer.cs

@@ -0,0 +1,85 @@
+#nullable enable
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
+using Robust.Roslyn.Shared;
+
+namespace Robust.Analyzers;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class AfterAutoHandleStateAnalyzer : DiagnosticAnalyzer
+{
+    private const string AfterAutoHandleStateEventName = "AfterAutoHandleStateEvent";
+    private const string AutoGenStateAttribute = "Robust.Shared.Analyzers.AutoGenerateComponentStateAttribute";
+    private const string SubscribeLocalEventName = "SubscribeLocalEvent";
+
+    public static readonly DiagnosticDescriptor MissingAttribute = new(
+        Diagnostics.IdAutoGenStateAttributeMissing,
+        "Unreachable AfterAutoHandleState subscription",
+        "Tried to subscribe to AfterAutoHandleStateEvent for '{0}' which doesn't have an "
+        + "AutoGenerateComponentState attribute",
+        "Usage",
+        DiagnosticSeverity.Error,
+        true,
+        // Does this even show up anywhere in Rider? >:(
+        "You must mark your component with '[AutoGenerateComponentState(true)]' to subscribe to this event."
+    );
+
+    public static readonly DiagnosticDescriptor MissingAttributeParam = new(
+        Diagnostics.IdAutoGenStateParamMissing,
+        "Unreachable AfterAutoHandleState subscription",
+        "Tried to subscribe to AfterAutoHandleStateEvent for '{0}' which doesn't have "
+        + "raiseAfterAutoHandleState set",
+        "Usage",
+        DiagnosticSeverity.Error,
+        true,
+        "The AutoGenerateComponentState attribute must be passed 'true' in order to subscribe to this event."
+    );
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
+        [MissingAttribute, MissingAttributeParam];
+
+    public override void Initialize(AnalysisContext context)
+    {
+        // This is more to stop user error rather than code generation error
+        // (Plus this shouldn't affect code gen anyway)
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+
+        context.RegisterCompilationStartAction(compilationContext =>
+        {
+            var autoGenStateAttribute = compilationContext.Compilation.GetTypeByMetadataName(AutoGenStateAttribute);
+            // No attribute, no analyzer.
+            if (autoGenStateAttribute is null)
+                return;
+
+            compilationContext.RegisterOperationAction(
+                analysisContext => CheckEventSubscription(analysisContext, autoGenStateAttribute),
+                OperationKind.Invocation);
+        });
+    }
+
+    private static void CheckEventSubscription(OperationAnalysisContext context, ITypeSymbol autoGenStateAttribute)
+    {
+        if (context.Operation is not IInvocationOperation operation)
+            return;
+
+        // Check the method has the right name and has the right type args
+        if (operation.TargetMethod is not
+            { Name: SubscribeLocalEventName, TypeArguments: [var component, { Name: AfterAutoHandleStateEventName }] })
+            return;
+
+        // Search the component's attributes for something matching autoGenStateAttribute
+        AttributeHelper.HasAttribute(component, autoGenStateAttribute, out var autoGenAttribute);
+
+        // First argument is raiseAfterAutoHandleState—note it shouldn't ever
+        // be null, since it has a default, but eh.
+        if (autoGenAttribute?.ConstructorArguments[0].Value is true)
+            return;
+
+        context.ReportDiagnostic(Diagnostic.Create(autoGenAttribute is null ? MissingAttribute : MissingAttributeParam,
+            operation.Syntax.GetLocation(),
+            component.Name));
+    }
+}

Robust.Roslyn.Shared/AttributeHelper.cs

@@ -45,8 +45,8 @@ public static class AttributeHelper
     }
 
     public static bool HasAttribute(
-        INamedTypeSymbol symbol,
-        INamedTypeSymbol attribute,
+        ITypeSymbol symbol,
+        ITypeSymbol attribute,
         [NotNullWhen(true)] out AttributeData? matchedAttribute)
     {
         matchedAttribute = null;

Robust.Roslyn.Shared/Diagnostics.cs

@@ -43,6 +43,8 @@ public static class Diagnostics
     public const string IdPrototypeNetSerializable = "RA0037";
     public const string IdPrototypeSerializable = "RA0038";
     public const string IdPrototypeInstantiation = "RA0039";
+    public const string IdAutoGenStateAttributeMissing = "RA0040";
+    public const string IdAutoGenStateParamMissing = "RA0041";
 
     public static SuppressionDescriptor MeansImplicitAssignment =>
         new SuppressionDescriptor("RADC1000", "CS0649", "Marked as implicitly assigned.");