add diagnostic for missing lambdafunction attribute

Author: GarrettBeatty

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/AnalyzerReleases.Unshipped.md

@@ -13,3 +13,4 @@ AWSLambda0124 | AWSLambdaCSharpGenerator | Error | Authorizer Type Mismatch
 AWSLambda0125 | AWSLambdaCSharpGenerator | Error | Duplicate Authorizer Name
 AWSLambda0127 | AWSLambdaCSharpGenerator | Error | Invalid Result TTL
 AWSLambda0128 | AWSLambdaCSharpGenerator | Warning | Authorizer Payload Version Mismatch
+AWSLambda0129 | AWSLambdaCSharpGenerator | Error | Missing LambdaFunction Attribute

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs

@@ -218,5 +218,13 @@ public static class DiagnosticDescriptors
             category: "AWSLambdaCSharpGenerator",
             DiagnosticSeverity.Warning,
             isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor MissingLambdaFunctionAttribute = new DiagnosticDescriptor(
+            id: "AWSLambda0129",
+            title: "Missing LambdaFunction Attribute",
+            messageFormat: "Method has [{0}] attribute but is missing the required [LambdaFunction] attribute. Add [LambdaFunction] to this method.",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
     }
 }

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Generator.cs

@@ -151,6 +151,17 @@ public void Execute(GeneratorExecutionContext context)
                     configureMethodSymbol = configureHostBuilderMethodSymbol;
                 }
 
+                // Check for methods that have secondary attributes (HttpApi, RestApi, HttpApiAuthorizer, etc.)
+                // but are missing the required [LambdaFunction] attribute
+                foreach (var (method, attributeName) in receiver.MethodsWithMissingLambdaFunction)
+                {
+                    diagnosticReporter.Report(Diagnostic.Create(
+                        DiagnosticDescriptors.MissingLambdaFunctionAttribute,
+                        Location.Create(method.SyntaxTree, method.Span),
+                        attributeName));
+                    foundFatalError = true;
+                }
+
                 var annotationReport = new AnnotationReport();
 
                 var templateHandler = new CloudFormationTemplateHandler(_fileManager, _directoryManager);

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/SyntaxReceiver.cs

@@ -11,12 +11,31 @@ namespace Amazon.Lambda.Annotations.SourceGenerator
 
     internal class SyntaxReceiver : ISyntaxContextReceiver
     {
+        /// <summary>
+        /// Secondary attribute names that require the [LambdaFunction] attribute to also be present.
+        /// The key is the attribute class name, the value is the user-friendly name for diagnostics.
+        /// </summary>
+        private static readonly Dictionary<string, string> _secondaryAttributeNames = new Dictionary<string, string>
+        {
+            { "HttpApiAuthorizerAttribute", "HttpApiAuthorizer" },
+            { "RestApiAuthorizerAttribute", "RestApiAuthorizer" },
+            { "HttpApiAttribute", "HttpApi" },
+            { "RestApiAttribute", "RestApi" },
+            { "SQSEventAttribute", "SQSEvent" }
+        };
+
         public List<MethodDeclarationSyntax> LambdaMethods { get; } = new List<MethodDeclarationSyntax>();
 
         public List<ClassDeclarationSyntax> StartupClasses { get; private set; } = new List<ClassDeclarationSyntax>();
 
         public List<MethodDeclarationSyntax> MethodDeclarations { get; } = new List<MethodDeclarationSyntax>();
 
+        /// <summary>
+        /// Methods that have a secondary Lambda annotation attribute but are missing [LambdaFunction].
+        /// Each entry is a tuple of the method syntax, its location, and the friendly name of the secondary attribute found.
+        /// </summary>
+        public List<(MethodDeclarationSyntax Method, string AttributeName)> MethodsWithMissingLambdaFunction { get; } = new List<(MethodDeclarationSyntax, string)>();
+
         /// <summary>
         /// Path to the directory containing the .csproj file
         /// </summary>
@@ -57,10 +76,24 @@ public void OnVisitSyntaxNode(GeneratorSyntaxContext context)
                 var methodSymbol = ModelExtensions.GetDeclaredSymbol(
                     context.SemanticModel,
                     methodDeclarationSyntax);
-                if (methodSymbol.GetAttributes().Any(attr => attr.AttributeClass.Name == nameof(LambdaFunctionAttribute)))
+                var attributes = methodSymbol.GetAttributes();
+                if (attributes.Any(attr => attr.AttributeClass.Name == nameof(LambdaFunctionAttribute)))
                 {
                     LambdaMethods.Add(methodDeclarationSyntax);
                 }
+                else
+                {
+                    // Check if the method has a secondary attribute without [LambdaFunction]
+                    foreach (var attr in attributes)
+                    {
+                        var attrName = attr.AttributeClass?.Name;
+                        if (attrName != null && _secondaryAttributeNames.TryGetValue(attrName, out var friendlyName))
+                        {
+                            MethodsWithMissingLambdaFunction.Add((methodDeclarationSyntax, friendlyName));
+                            break; // Only report once per method
+                        }
+                    }
+                }
             }
 
             // any class with at least one attribute is a candidate of Startup class

Libraries/test/Amazon.Lambda.Annotations.SourceGenerators.Tests/SourceGeneratorTests.cs

@@ -1756,6 +1756,36 @@ public async Task CustomAuthorizerAppAuthorizerDefinitionsTest()
             Assert.Equal(expectedTemplateContent, actualTemplateContent);
         }
 
+        [Fact]
+        public async Task VerifyMissingLambdaFunctionWithAuthorizerAttribute()
+        {
+            var test = new VerifyCS.Test()
+            {
+                TestState =
+                {
+                    Sources =
+                    {
+                        (Path.Combine("TestServerlessApp", "FromScratch", "MissingLambdaFunctionWithAuthorizer.cs"), await File.ReadAllTextAsync(Path.Combine("TestServerlessApp", "FromScratch", "MissingLambdaFunctionWithAuthorizer.cs"))),
+                        (Path.Combine("Amazon.Lambda.Annotations", "LambdaFunctionAttribute.cs"), await File.ReadAllTextAsync(Path.Combine("Amazon.Lambda.Annotations", "LambdaFunctionAttribute.cs"))),
+                        (Path.Combine("Amazon.Lambda.Annotations", "LambdaStartupAttribute.cs"), await File.ReadAllTextAsync(Path.Combine("Amazon.Lambda.Annotations", "LambdaStartupAttribute.cs"))),
+                        (Path.Combine("Amazon.Lambda.Annotations", "APIGateway", "HttpApiAuthorizerAttribute.cs"), await File.ReadAllTextAsync(Path.Combine("Amazon.Lambda.Annotations", "APIGateway", "HttpApiAuthorizerAttribute.cs"))),
+                        (Path.Combine("Amazon.Lambda.Annotations", "APIGateway", "AuthorizerPayloadFormatVersion.cs"), await File.ReadAllTextAsync(Path.Combine("Amazon.Lambda.Annotations", "APIGateway", "AuthorizerPayloadFormatVersion.cs"))),
+                    },
+                    GeneratedSources =
+                    {
+                    },
+                    ExpectedDiagnostics =
+                    {
+                        new DiagnosticResult("AWSLambda0129", DiagnosticSeverity.Error)
+                            .WithSpan($"TestServerlessApp{Path.DirectorySeparatorChar}FromScratch{Path.DirectorySeparatorChar}MissingLambdaFunctionWithAuthorizer.cs", 10, 9, 21, 10)
+                            .WithMessage("Method has [HttpApiAuthorizer] attribute but is missing the required [LambdaFunction] attribute. Add [LambdaFunction] to this method."),
+                    },
+                },
+            };
+
+            await test.RunAsync();
+        }
+
         public void Dispose()
         {
             File.Delete(Path.Combine("TestServerlessApp", "serverless.template"));

Libraries/test/TestCustomAuthorizerApp/aws-lambda-tools-defaults.json

@@ -8,8 +8,8 @@
   "configuration": "Release",
   "template": "serverless.template",
   "template-parameters": "",
-"s3-bucket" : "test-custom-authorizer-112e1ec1",
+  "s3-bucket": "test-custom-authorizer-app",
   "s3-prefix": "TestCustomAuthorizerApp/",
-"stack-name" : "test-custom-authorizer-112e1ec1",
-"function-architecture" : "x86_64"
-}
+  "stack-name": "test-custom-authorizer",
+  "function-architecture": "x86_64"
+}

Libraries/test/TestServerlessApp/FromScratch/MissingLambdaFunctionWithAuthorizer.cs

@@ -0,0 +1,23 @@
+using Amazon.Lambda.Annotations;
+using Amazon.Lambda.Annotations.APIGateway;
+using Amazon.Lambda.APIGatewayEvents;
+using Amazon.Lambda.Core;
+
+namespace TestServerlessApp.FromScratch
+{
+    public class MissingLambdaFunctionWithAuthorizer
+    {
+        [HttpApiAuthorizer(
+            Name = "MyAuthorizer",
+            AuthorizerPayloadFormatVersion = AuthorizerPayloadFormatVersion.V2)]
+        public APIGatewayCustomAuthorizerV2SimpleResponse Authorize(
+            APIGatewayCustomAuthorizerV2Request request,
+            ILambdaContext context)
+        {
+            return new APIGatewayCustomAuthorizerV2SimpleResponse
+            {
+                IsAuthorized = true
+            };
+        }
+    }
+}