Analyzer to warn about using a boxing variant (#3564)

Robust.Analyzers/Diagnostics.cs

@@ -9,6 +9,9 @@ public static class Diagnostics
     public const string IdAccess = "RA0002";
     public const string IdExplicitVirtual = "RA0003";
     public const string IdTaskResult = "RA0004";
+    public const string IdUseGenericVariant = "RA0005";
+    public const string IdUseGenericVariantInvalidUsage = "RA0006";
+    public const string IdUseGenericVariantAttributeValueError = "RA0007";
 
     public static SuppressionDescriptor MeansImplicitAssignment =>
         new SuppressionDescriptor("RADC1000", "CS0649", "Marked as implicitly assigned.");

Robust.Analyzers/PreferGenericVariantAnalyzer.cs

@@ -0,0 +1,238 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
+
+namespace Robust.Analyzers;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class PreferGenericVariantAnalyzer : DiagnosticAnalyzer
+{
+    private const string AttributeType = "Robust.Shared.Analyzers.PreferGenericVariantAttribute";
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(
+        UseGenericVariantDescriptor, UseGenericVariantInvalidUsageDescriptor,
+        UseGenericVariantAttributeValueErrorDescriptor);
+
+    private static readonly DiagnosticDescriptor UseGenericVariantDescriptor = new(
+        Diagnostics.IdUseGenericVariant,
+        "Consider using the generic variant of this method",
+        "Consider using the generic variant of this method to avoid potential allocations",
+        "Usage",
+        DiagnosticSeverity.Warning,
+        true,
+        "Consider using the generic variant of this method to avoid potential allocations.");
+
+    private static readonly DiagnosticDescriptor UseGenericVariantInvalidUsageDescriptor = new(
+        Diagnostics.IdUseGenericVariantInvalidUsage,
+        "Invalid generic variant provided",
+        "Generic variant provided mismatches the amount of type parameters of non-generic variant",
+        "Usage",
+        DiagnosticSeverity.Error,
+        true,
+        "The non-generic variant should have at least as many type parameter at the beginning of the method as there are generic type parameters on the generic variant.");
+
+    private static readonly DiagnosticDescriptor UseGenericVariantAttributeValueErrorDescriptor = new(
+        Diagnostics.IdUseGenericVariantAttributeValueError,
+        "Failed resolving generic variant value",
+        "Failed resolving generic variant value: {0}",
+        "Usage",
+        DiagnosticSeverity.Error,
+        true,
+        "Consider using nameof to avoid any typos.");
+
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.ReportDiagnostics | GeneratedCodeAnalysisFlags.Analyze);
+        context.EnableConcurrentExecution();
+        context.RegisterOperationAction(CheckForGenericVariant, OperationKind.Invocation);
+    }
+
+    private void CheckForGenericVariant(OperationAnalysisContext obj)
+    {
+        if(obj.Operation is not IInvocationOperation invocationOperation) return;
+
+        var preferGenericAttribute = obj.Compilation.GetTypeByMetadataName(AttributeType);
+
+        string genericVariant = null;
+        AttributeData foundAttribute = null;
+        foreach (var attribute in invocationOperation.TargetMethod.GetAttributes())
+        {
+            if (!SymbolEqualityComparer.Default.Equals(attribute.AttributeClass, preferGenericAttribute))
+                continue;
+
+            genericVariant = attribute.ConstructorArguments[0].Value as string ?? invocationOperation.TargetMethod.Name;
+            foundAttribute = attribute;
+            break;
+        }
+
+        if(genericVariant == null) return;
+
+        var maxTypeParams = 0;
+        var typeTypeSymbol = obj.Compilation.GetTypeByMetadataName("System.Type");
+        foreach (var parameter in invocationOperation.TargetMethod.Parameters)
+        {
+            if(!SymbolEqualityComparer.Default.Equals(parameter.Type, typeTypeSymbol)) break;
+
+            maxTypeParams++;
+        }
+
+        if (maxTypeParams == 0)
+        {
+            obj.ReportDiagnostic(
+                Diagnostic.Create(UseGenericVariantInvalidUsageDescriptor,
+                    foundAttribute.ApplicationSyntaxReference?.GetSyntax().GetLocation()));
+            return;
+        }
+
+        IMethodSymbol genericVariantMethod = null;
+        foreach (var member in invocationOperation.TargetMethod.ContainingType.GetMembers())
+        {
+            if (member is not IMethodSymbol methodSymbol
+                || methodSymbol.Name != genericVariant
+                || !methodSymbol.IsGenericMethod
+                || methodSymbol.TypeParameters.Length > maxTypeParams
+                || methodSymbol.Parameters.Length > invocationOperation.TargetMethod.Parameters.Length - methodSymbol.TypeParameters.Length
+                ) continue;
+
+            var typeParamCount = methodSymbol.TypeParameters.Length;
+            var failedParamComparison = false;
+            var objType = obj.Compilation.GetSpecialType(SpecialType.System_Object);
+            for (int i = 0; i < methodSymbol.Parameters.Length; i++)
+            {
+                if (methodSymbol.Parameters[i].Type is ITypeParameterSymbol && SymbolEqualityComparer.Default.Equals(invocationOperation.TargetMethod.Parameters[i + typeParamCount].Type, objType))
+                    continue;
+
+                if (!SymbolEqualityComparer.Default.Equals(methodSymbol.Parameters[i].Type,
+                        invocationOperation.TargetMethod.Parameters[i + typeParamCount].Type))
+                {
+                    failedParamComparison = true;
+                    break;
+                }
+            }
+
+            if(failedParamComparison) continue;
+
+            genericVariantMethod = methodSymbol;
+        }
+
+        if (genericVariantMethod == null)
+        {
+            obj.ReportDiagnostic(Diagnostic.Create(
+                UseGenericVariantAttributeValueErrorDescriptor,
+                foundAttribute.ApplicationSyntaxReference?.GetSyntax().GetLocation(),
+                genericVariant));
+            return;
+        }
+
+        var typeOperands = new string[genericVariantMethod.TypeParameters.Length];
+        for (var i = 0; i < genericVariantMethod.TypeParameters.Length; i++)
+        {
+            switch (invocationOperation.Arguments[i].Value)
+            {
+                //todo figure out if ILocalReferenceOperation, IPropertyReferenceOperation or IFieldReferenceOperation is referencing static typeof assignments
+                case ITypeOfOperation typeOfOperation:
+                    typeOperands[i] = typeOfOperation.TypeOperand.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
+                    continue;
+                default:
+                    return;
+            }
+        }
+
+        obj.ReportDiagnostic(Diagnostic.Create(
+            UseGenericVariantDescriptor,
+            invocationOperation.Syntax.GetLocation(),
+            ImmutableDictionary.CreateRange(new Dictionary<string, string>()
+            {
+                {"typeOperands", string.Join(",", typeOperands)}
+            })));
+    }
+}
+
+[ExportCodeFixProvider(LanguageNames.CSharp)]
+public class PreferGenericVariantCodeFixProvider : CodeFixProvider
+{
+    private static string Title(string method, string[] types) => $"Use {method}<{string.Join(",", types)}>.";
+
+    public override FixAllProvider GetFixAllProvider()
+    {
+        return WellKnownFixAllProviders.BatchFixer;
+    }
+
+    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        var root = await context.Document.GetSyntaxRootAsync();
+        if(root == null) return;
+
+        foreach (var diagnostic in context.Diagnostics)
+        {
+            if (!diagnostic.Properties.TryGetValue("typeOperands", out var typeOperandsRaw)
+                || typeOperandsRaw == null) continue;
+
+            var node = root.FindNode(diagnostic.Location.SourceSpan);
+            if (node is ArgumentSyntax argumentSyntax)
+                node = argumentSyntax.Expression;
+
+            if(node is not InvocationExpressionSyntax invocationExpression)
+                continue;
+
+            var typeOperands = typeOperandsRaw.Split(',');
+
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    Title(invocationExpression.Expression.ToString(), typeOperands),
+                    c => FixAsync(context.Document, invocationExpression, typeOperands, c),
+                    Title(invocationExpression.Expression.ToString(), typeOperands)),
+                diagnostic);
+        }
+    }
+
+    private async Task<Document> FixAsync(
+        Document contextDocument,
+        InvocationExpressionSyntax invocationExpression,
+        string[] typeOperands,
+        CancellationToken cancellationToken)
+    {
+        var memberAccess = (MemberAccessExpressionSyntax)invocationExpression.Expression;
+
+        var root = (CompilationUnitSyntax) await contextDocument.GetSyntaxRootAsync(cancellationToken);
+
+        var arguments = new ArgumentSyntax[invocationExpression.ArgumentList.Arguments.Count - typeOperands.Length];
+        var types = new TypeSyntax[typeOperands.Length];
+
+        for (int i = 0; i < typeOperands.Length; i++)
+        {
+            types[i] = ((TypeOfExpressionSyntax)invocationExpression.ArgumentList.Arguments[i].Expression).Type;
+        }
+
+
+
+        Array.Copy(
+            invocationExpression.ArgumentList.Arguments.ToArray(),
+            typeOperands.Length,
+            arguments,
+            0,
+            arguments.Length);
+
+        memberAccess = memberAccess.WithName(SyntaxFactory.GenericName(memberAccess.Name.Identifier,
+            SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(types))));
+
+        root = root!.ReplaceNode(invocationExpression,
+            invocationExpression.WithArgumentList(invocationExpression.ArgumentList.WithArguments(SyntaxFactory.SeparatedList(arguments)))
+                .WithExpression(memberAccess));
+
+        return contextDocument.WithSyntaxRoot(root);
+    }
+
+    public override ImmutableArray<string> FixableDiagnosticIds =>
+        ImmutableArray.Create(Diagnostics.IdUseGenericVariant);
+}

Robust.Analyzers/Robust.Analyzers.csproj

@@ -17,4 +17,9 @@
     <Compile Include="..\Robust.Shared\Analyzers\AccessPermissions.cs" />
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- Needed for PreferGenericVariantAnalyzer. -->
+    <Compile Include="..\Robust.Shared\Analyzers\PreferGenericVariantAttribute.cs" />
+  </ItemGroup>
+
 </Project>

Robust.Server/Serialization/ServerSpriteSpecifierSerializer.cs

@@ -33,7 +33,7 @@ public sealed class ServerSpriteSpecifierSerializer : SpriteSpecifierSerializer
             return new ErrorNode(node, "Sprite specifier has missing/invalid state node");
         }
 
-        var path = serializationManager.ValidateNode(typeof(ResourcePath),
+        var path = serializationManager.ValidateNode<ResourcePath>(
             new ValueDataNode($"{SharedSpriteComponent.TextureRoot / valuePathNode.Value}"), context);
 
         if (path is ErrorNode) return path;
@@ -43,8 +43,9 @@ public sealed class ServerSpriteSpecifierSerializer : SpriteSpecifierSerializer
         // the state exists. So lets just check if the state .png exists, without properly validating the RSI's
         // meta.json
 
-        var statePath = serializationManager.ValidateNode(typeof(ResourcePath),
-            new ValueDataNode($"{SharedSpriteComponent.TextureRoot / valuePathNode.Value / valueStateNode.Value}.png"), context);
+        var statePath = serializationManager.ValidateNode<ResourcePath>(
+            new ValueDataNode($"{SharedSpriteComponent.TextureRoot / valuePathNode.Value / valueStateNode.Value}.png"),
+            context);
 
         if (statePath is ErrorNode) return statePath;
 

Robust.Shared/Analyzers/PreferGenericVariantAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+
+#if NETSTANDARD2_0
+namespace Robust.Shared.Analyzers.Implementation;
+#else
+namespace Robust.Shared.Analyzers;
+#endif
+
+[AttributeUsage(AttributeTargets.Method)]
+public sealed class PreferGenericVariantAttribute : Attribute
+{
+    public readonly string GenericVariant;
+
+    public PreferGenericVariantAttribute(string genericVariant = null!)
+    {
+        GenericVariant = genericVariant;
+    }
+}

Robust.Shared/Serialization/Manager/Definition/DataDefinition.cs

@@ -275,7 +275,7 @@ namespace Robust.Shared.Serialization.Manager.Definition
                     continue;
                 }
 
-                var keyValidated = serialization.ValidateNode(typeof(string), key, context);
+                var keyValidated = serialization.ValidateNode<string>(key, context);
 
                 ValidationNode valNode;
                 if (IsNull(val))

Robust.Shared/Serialization/Manager/ISerializationManager.cs

@@ -35,6 +35,7 @@ namespace Robust.Shared.Serialization.Manager
         ///     A node with whether or not <see cref="node"/> is valid and which of its fields
         ///     are invalid, if any.
         /// </returns>
+        [PreferGenericVariant]
         ValidationNode ValidateNode(Type type, DataNode node, ISerializationContext? context = null);
 
         /// <summary>
@@ -224,23 +225,9 @@ namespace Robust.Shared.Serialization.Manager
         ///     A serialized datanode created from the given <see cref="value"/>
         ///     of type <see cref="type"/>.
         /// </returns>
+        [PreferGenericVariant]
         DataNode WriteValue(Type type, object? value, bool alwaysWrite = false, ISerializationContext? context = null, bool notNullableOverride = false);
 
-        /// <summary>
-        ///     Serializes a value into a node.
-        /// </summary>
-        /// <param name="value">The value to serialize.</param>
-        /// <param name="alwaysWrite">
-        ///     Whether or not to always write the given values into the resulting node,
-        ///     even if they are the default.
-        /// </param>
-        /// <param name="context">The context to use, if any.</param>
-        /// <param name="notNullableOverride">Set true if a reference Type should not allow null. Not necessary for value types.</param>
-        /// <returns>
-        ///     A serialized datanode created from the given <see cref="value"/>.
-        /// </returns>
-        DataNode WriteValue(object? value, bool alwaysWrite = false, ISerializationContext? context = null, bool notNullableOverride = false);
-
         #endregion
 
         #region Copy

Robust.Shared/Serialization/Manager/SerializationManager.Writing.cs

@@ -253,18 +253,6 @@ public sealed partial class SerializationManager
         return WriteValue(GetOrCreateCustomTypeSerializer<TWriter>(), value, alwaysWrite, context, notNullableOverride);
     }
 
-    public DataNode WriteValue(object? value, bool alwaysWrite = false,
-        ISerializationContext? context = null, bool notNullableOverride = false)
-    {
-        if (value == null)
-        {
-            if (notNullableOverride) throw new NullNotAllowedException();
-            return NullNode();
-        }
-
-        return WriteValue(value.GetType(), value, alwaysWrite, context);
-    }
-
     public DataNode WriteValue(Type type, object? value, bool alwaysWrite = false, ISerializationContext? context = null, bool notNullableOverride = false)
     {
         if (value == null)

Robust.Shared/Serialization/TypeSerializers/Implementations/Custom/Prototype/Dictionary/PrototypeIdDictionarySerializer.cs

@@ -34,11 +34,11 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Pro
             {
                 if (key is not ValueDataNode value)
                 {
-                    mapping.Add(new ErrorNode(key, $"Cannot cast node {key} to ValueDataNode."), serializationManager.ValidateNode(typeof(TValue), val, context));
+                    mapping.Add(new ErrorNode(key, $"Cannot cast node {key} to ValueDataNode."), serializationManager.ValidateNode<TValue>(val, context));
                     continue;
                 }
 
-                mapping.Add(PrototypeSerializer.Validate(serializationManager, value, dependencies, context), serializationManager.ValidateNode(typeof(TValue), val, context));
+                mapping.Add(PrototypeSerializer.Validate(serializationManager, value, dependencies, context), serializationManager.ValidateNode<TValue>(val, context));
             }
 
             return new ValidatedMappingNode(mapping);

Robust.Shared/Serialization/TypeSerializers/Implementations/Custom/Prototype/Dictionary/PrototypeIdValueDictionarySerializer.cs

@@ -34,11 +34,11 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Pro
             {
                 if (val is not ValueDataNode value)
                 {
-                    mapping.Add(new ErrorNode(val, $"Cannot cast node {val} to ValueDataNode."), serializationManager.ValidateNode(typeof(TValue), key, context));
+                    mapping.Add(new ErrorNode(val, $"Cannot cast node {val} to ValueDataNode."), serializationManager.ValidateNode<TValue>(key, context));
                     continue;
                 }
 
-                mapping.Add(PrototypeSerializer.Validate(serializationManager, value, dependencies, context), serializationManager.ValidateNode(typeof(TValue), key, context));
+                mapping.Add(PrototypeSerializer.Validate(serializationManager, value, dependencies, context), serializationManager.ValidateNode<TValue>(key, context));
             }
 
             return new ValidatedMappingNode(mapping);

Robust.Shared/Serialization/TypeSerializers/Implementations/Generic/DictionarySerializer.cs

@@ -33,7 +33,7 @@ public sealed class DictionarySerializer<TKey, TValue> :
         {
             mappingNode.Add(
                 serializationManager.WriteValue(key, alwaysWrite, context),
-                serializationManager.WriteValue(typeof(TValue), val, alwaysWrite, context));
+                serializationManager.WriteValue(val, alwaysWrite, context));
         }
 
         return mappingNode;
@@ -81,8 +81,8 @@ public sealed class DictionarySerializer<TKey, TValue> :
         var mapping = new Dictionary<ValidationNode, ValidationNode>();
         foreach (var (key, val) in node.Children)
         {
-            mapping.Add(serializationManager.ValidateNode(typeof(TKey), key, context),
-                serializationManager.ValidateNode(typeof(TValue), val, context));
+            mapping.Add(serializationManager.ValidateNode<TKey>(key, context),
+                serializationManager.ValidateNode<TValue>(val, context));
         }
 
         return new ValidatedMappingNode(mapping);

Robust.Shared/Serialization/TypeSerializers/Implementations/Generic/ListSerializers.cs

@@ -30,7 +30,7 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Generic
 
             foreach (var elem in value)
             {
-                sequence.Add(serializationManager.WriteValue(typeof(T), elem, alwaysWrite, context));
+                sequence.Add(serializationManager.WriteValue<T>(elem, alwaysWrite, context));
             }
 
             return sequence;
@@ -115,7 +115,7 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Generic
             var list = new List<ValidationNode>();
             foreach (var elem in sequenceDataNode.Sequence)
             {
-                list.Add(serializationManager.ValidateNode(typeof(T), elem, context));
+                list.Add(serializationManager.ValidateNode<T>(elem, context));
             }
 
             return new ValidatedSequenceNode(list);

Robust.Shared/Serialization/TypeSerializers/Implementations/Generic/ValueTupleSerializer.cs

@@ -39,8 +39,8 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Generic
             var dict = new Dictionary<ValidationNode, ValidationNode>
             {
                 {
-                    serializationManager.ValidateNode(typeof(T1), entry.Key, context),
-                    serializationManager.ValidateNode(typeof(T2), entry.Value, context)
+                    serializationManager.ValidateNode<T1>(entry.Key, context),
+                    serializationManager.ValidateNode<T2>(entry.Value, context)
                 }
             };
 
@@ -54,9 +54,8 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations.Generic
             var mapping = new MappingDataNode();
 
             mapping.Add(
-                serializationManager.WriteValue(typeof(T1), value.Item1, alwaysWrite, context),
-                serializationManager.WriteValue(typeof(T2), value.Item2, alwaysWrite, context)
-            );
+                serializationManager.WriteValue<T1>(value.Item1, alwaysWrite, context),
+                serializationManager.WriteValue<T2>(value.Item2, alwaysWrite, context));
 
             return mapping;
         }

Robust.Shared/Serialization/TypeSerializers/Implementations/SpriteSpecifierSerializer.cs

@@ -108,7 +108,7 @@ namespace Robust.Shared.Serialization.TypeSerializers.Implementations
             IDependencyCollection dependencies,
             ISerializationContext? context)
         {
-            return serializationManager.ValidateNode(typeof(ResourcePath), new ValueDataNode($"{SharedSpriteComponent.TextureRoot / node.Value}"), context);
+            return serializationManager.ValidateNode<ResourcePath>(new ValueDataNode($"{SharedSpriteComponent.TextureRoot / node.Value}"), context);
         }
 
         ValidationNode ITypeValidator<SpriteSpecifier, MappingDataNode>.Validate(