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feat: add analyzer
1 parent 29f496a commit 59e7014

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Lines changed: 638 additions & 0 deletions

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‎src/Mediator.SourceGenerator/Mediator.SourceGenerator.csproj‎

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<ItemGroup>
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<PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.3" PrivateAssets="all" />
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<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.3.0" PrivateAssets="all" />
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<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.3.0" PrivateAssets="all" />
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<PackageReference Include="Nullable" Version="1.3.1" PrivateAssets="all" />
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<PackageReference Include="IsExternalInit" Version="1.0.2" PrivateAssets="all" />
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</ItemGroup>

‎src/Mediator.SourceGenerator/UseTypedSenderExtensionAnalyzer.cs‎

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using System.Collections.Immutable;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CSharp;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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using Microsoft.CodeAnalysis.Diagnostics;
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namespace Zapto.Mediator.Generator;
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[DiagnosticAnalyzer(LanguageNames.CSharp)]
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public class UseTypedSenderExtensionAnalyzer : DiagnosticAnalyzer
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{
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public const string DiagnosticId = "ZM0001";
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public const string ExtensionMethodNameProperty = "ExtensionMethodName";
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public const string HasNamespaceArgProperty = "HasNamespaceArg";
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public const string IsObjectCreationProperty = "IsObjectCreation";
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internal static readonly DiagnosticDescriptor Rule = new(
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DiagnosticId,
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title: "Use typed sender extension method",
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messageFormat: "Use '{0}' instead",
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category: "Usage",
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defaultSeverity: DiagnosticSeverity.Info,
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isEnabledByDefault: true,
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description: "Use the typed extension method generated for this request type instead of the generic Send/Publish/CreateStream overload.");
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public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
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ImmutableArray.Create(Rule);
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public override void Initialize(AnalysisContext context)
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{
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context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
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context.EnableConcurrentExecution();
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context.RegisterSyntaxNodeAction(AnalyzeInvocation, SyntaxKind.InvocationExpression);
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}
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private static void AnalyzeInvocation(SyntaxNodeAnalysisContext context)
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{
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var invocation = (InvocationExpressionSyntax)context.Node;
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if (invocation.Expression is not MemberAccessExpressionSyntax memberAccess)
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return;
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var methodIdentifier = memberAccess.Name.Identifier.ValueText;
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if (methodIdentifier is not ("Send" or "Publish" or "CreateStream"))
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return;
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if (context.SemanticModel.GetSymbolInfo(invocation).Symbol is not IMethodSymbol methodSymbol)
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return;
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var containingType = methodSymbol.ContainingType;
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if (!IsMediatorInterface(containingType))
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return;
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var args = invocation.ArgumentList.Arguments;
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if (args.Count == 0) return;
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// Named outer arguments can cause incorrect argument reordering in the code fix
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foreach (var arg in args)
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{
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if (arg.NameColon != null) return;
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}
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// The first argument might be a MediatorNamespace for namespaced calls
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var requestArgIndex = 0;
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var firstArgType = context.SemanticModel.GetTypeInfo(args[0].Expression).Type;
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if (firstArgType?.Name == "MediatorNamespace" &&
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firstArgType.ContainingNamespace?.ToDisplayString() == "Zapto.Mediator")
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{
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requestArgIndex = 1;
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}
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if (args.Count <= requestArgIndex) return;
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var requestArg = args[requestArgIndex];
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if (context.SemanticModel.GetTypeInfo(requestArg.Expression).Type is not INamedTypeSymbol requestType)
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return;
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var interfaceName = FindRequestInterface(requestType);
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if (interfaceName is null) return;
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var extensionMethodName = ComputeExtensionMethodName(interfaceName, requestType.Name, methodSymbol);
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if (!ExtensionMethodExists(context.Compilation, requestType, extensionMethodName))
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return;
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// Don't unwrap generic types (type arguments may not be inferable from ctor args alone)
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// Don't unwrap when an object initializer is also present (it would be silently dropped)
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var isObjectCreation = !requestType.IsGenericType &&
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requestArg.Expression is ObjectCreationExpressionSyntax oc &&
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oc.ArgumentList?.Arguments.Count > 0 &&
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oc.Initializer == null;
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var hasNamespaceArg = requestArgIndex > 0;
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var properties = ImmutableDictionary.CreateBuilder<string, string?>();
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properties[ExtensionMethodNameProperty] = extensionMethodName;
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properties[HasNamespaceArgProperty] = hasNamespaceArg ? "true" : "false";
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properties[IsObjectCreationProperty] = isObjectCreation ? "true" : "false";
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var diagnostic = Diagnostic.Create(
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Rule,
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memberAccess.Name.GetLocation(),
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properties.ToImmutable(),
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extensionMethodName);
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context.ReportDiagnostic(diagnostic);
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}
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private static bool IsMediatorInterface(INamedTypeSymbol type)
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{
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return type.ContainingNamespace?.ToDisplayString() == "Zapto.Mediator" &&
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type.Name is "ISender" or "IPublisher" or "IBackgroundPublisher";
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}
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internal static string? FindRequestInterface(INamedTypeSymbol requestType)
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{
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foreach (var iface in requestType.AllInterfaces)
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{
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var ns = iface.ContainingNamespace?.ToDisplayString();
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if ((ns == "Zapto.Mediator" || ns == "MediatR") &&
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iface.Name is "IRequest" or "INotification" or "IStreamRequest")
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{
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return iface.Name;
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}
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}
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return null;
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}
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internal static string ComputeExtensionMethodName(string interfaceName, string typeName, IMethodSymbol? methodSymbol = null)
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{
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// Remove the "I" prefix to get suffix: IRequest -> Request, INotification -> Notification
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var suffix = interfaceName.Substring(1);
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var baseName = typeName.EndsWith(suffix) && typeName.Length != suffix.Length
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? typeName.Substring(0, typeName.Length - suffix.Length)
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: typeName;
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// IBackgroundPublisher methods are void, so no "Async" suffix
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var isVoidReturn = methodSymbol?.ReturnType.SpecialType == SpecialType.System_Void;
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return isVoidReturn ? baseName : baseName + "Async";
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}
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internal static bool ExtensionMethodExists(Compilation compilation, INamedTypeSymbol requestType, string methodName)
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{
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var isGlobalNs = requestType.ContainingNamespace?.IsGlobalNamespace ?? true;
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var ns = isGlobalNs ? null : requestType.ContainingNamespace?.ToDisplayString();
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var fullTypeName = ns is null ? "SenderExtensions" : $"{ns}.SenderExtensions";
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var extensionsType = compilation.GetTypeByMetadataName(fullTypeName);
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if (extensionsType is null) return false;
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foreach (var member in extensionsType.GetMembers(methodName))
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{
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if (member is IMethodSymbol) return true;
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}
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return false;
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}
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}

‎src/Mediator.SourceGenerator/UseTypedSenderExtensionCodeFixProvider.cs‎

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using System.Collections.Immutable;
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using System.Composition;
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using System.Threading;
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using System.Threading.Tasks;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CodeActions;
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using Microsoft.CodeAnalysis.CodeFixes;
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using Microsoft.CodeAnalysis.CSharp;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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namespace Zapto.Mediator.Generator;
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[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(UseTypedSenderExtensionCodeFixProvider)), Shared]
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public class UseTypedSenderExtensionCodeFixProvider : CodeFixProvider
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{
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public override ImmutableArray<string> FixableDiagnosticIds =>
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ImmutableArray.Create(UseTypedSenderExtensionAnalyzer.DiagnosticId);
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public override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
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public override async Task RegisterCodeFixesAsync(CodeFixContext context)
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{
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var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
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if (root is null) return;
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var diagnostic = context.Diagnostics[0];
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if (!diagnostic.Properties.TryGetValue(UseTypedSenderExtensionAnalyzer.ExtensionMethodNameProperty, out var methodName) || methodName is null)
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return;
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var nameNode = root.FindNode(diagnostic.Location.SourceSpan) as SimpleNameSyntax;
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var memberAccess = nameNode?.Parent as MemberAccessExpressionSyntax;
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var invocation = memberAccess?.Parent as InvocationExpressionSyntax;
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if (invocation is null) return;
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context.RegisterCodeFix(
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CodeAction.Create(
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title: $"Use '{methodName}'",
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createChangedDocument: ct => ApplyFixAsync(context.Document, invocation, methodName, diagnostic.Properties, ct),
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equivalenceKey: UseTypedSenderExtensionAnalyzer.DiagnosticId),
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diagnostic);
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}
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private static async Task<Document> ApplyFixAsync(
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Document document,
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InvocationExpressionSyntax invocation,
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string methodName,
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ImmutableDictionary<string, string?> properties,
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CancellationToken cancellationToken)
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{
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var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
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if (root is null) return document;
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var hasNamespaceArg = properties.TryGetValue(UseTypedSenderExtensionAnalyzer.HasNamespaceArgProperty, out var nsStr) && nsStr == "true";
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var isObjectCreation = properties.TryGetValue(UseTypedSenderExtensionAnalyzer.IsObjectCreationProperty, out var ocStr) && ocStr == "true";
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var requestArgIndex = hasNamespaceArg ? 1 : 0;
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var args = invocation.ArgumentList.Arguments;
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var newArgs = new System.Collections.Generic.List<ArgumentSyntax>();
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// Preserve the optional namespace argument
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if (hasNamespaceArg)
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{
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newArgs.Add(args[0].WithoutTrivia().WithLeadingTrivia(args[0].GetLeadingTrivia()));
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}
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var requestArg = args[requestArgIndex];
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if (isObjectCreation && requestArg.Expression is ObjectCreationExpressionSyntax oc && oc.ArgumentList is not null)
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{
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// Unwrap constructor arguments: Send(new Req(a, b)) -> ReqAsync(a, b)
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foreach (var ctorArg in oc.ArgumentList.Arguments)
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{
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newArgs.Add(ctorArg);
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}
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}
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else
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{
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// Keep the request expression as-is: Send(req) -> ReqAsync(req)
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newArgs.Add(requestArg);
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}
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// Preserve trailing arguments (e.g. CancellationToken)
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for (var i = requestArgIndex + 1; i < args.Count; i++)
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{
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newArgs.Add(args[i]);
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}
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var memberAccess = (MemberAccessExpressionSyntax)invocation.Expression;
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var newMemberAccess = memberAccess.WithName(
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SyntaxFactory.IdentifierName(methodName)
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.WithTriviaFrom(memberAccess.Name));
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var newInvocation = invocation
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.WithExpression(newMemberAccess)
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.WithArgumentList(SyntaxFactory.ArgumentList(SyntaxFactory.SeparatedList(newArgs)));
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var newRoot = root.ReplaceNode(invocation, newInvocation);
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return document.WithSyntaxRoot(newRoot);
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}
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}

‎tests/Mediator.DependencyInjection.Tests/Mediator.DependencyInjection.Tests.csproj‎

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<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
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</PropertyGroup>
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<ItemGroup>
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<NuGetAuditSuppress Include="https://github.com/advisories/GHSA-73j8-2gch-69rq" />
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</ItemGroup>
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<ItemGroup>
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<ProjectReference Include="..\..\src\Mediator.DependencyInjection\Mediator.DependencyInjection.csproj" />
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<ProjectReference Include="..\..\src\Mediator\Mediator.csproj" />

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