Bugfix/simple method with parameter (#83)

* Added SimpleMethodWithParameterTest

* WIP

* Enforce MSGH007 for simple generators with parameters and finish SimpleMethodWithParameter test (#82)

* Initial plan

* Add MSGH007 validation for simple generators with parameters

Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

---------

Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dex3r <3155725+dex3r@users.noreply.github.com>

Author: dex3r

EasySourceGenerators.GeneratorTests/SimpleMethodWithParameter.cs

@@ -0,0 +1,41 @@
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
+
+namespace EasySourceGenerators.GeneratorTests;
+
+public class SimpleMethodWithParameterTests
+{
+    [Test]
+    public void SimpleMethodWithParameterTests_Test()
+    {
+        string source = """
+                        using EasySourceGenerators.Abstractions;
+
+                        namespace TestNamespace;
+
+                        public partial class SimpleMethodWithParameterClass
+                        {
+                            public partial int SimpleMethodWithParameter(int someIntParameter);
+
+                            [GeneratesMethod(sameClassMethodName: nameof(SimpleMethodWithParameter))]
+                            private static int SimpleMethodWithParameter_Generator(int someIntParameter)
+                            {
+                                return 5;
+                            }
+                        }
+                        """;
+
+        ImmutableArray<Diagnostic> diagnostics = GeneratorTestHelper.GetGeneratorOnlyDiagnostics(source);
+
+        Diagnostic? msgh007 = diagnostics.FirstOrDefault(diagnostic => diagnostic.Id == "MSGH007");
+        Assert.That(msgh007, Is.Not.Null, "Expected MSGH007 for simple generator method with runtime parameter.");
+        Assert.That(msgh007!.Location.IsInSource, Is.True, "MSGH007 should point to generator source.");
+
+        TextSpan span = msgh007.Location.SourceSpan;
+        string highlightedCode = source.Substring(span.Start, span.Length);
+        Assert.That(highlightedCode, Does.Contain("SimpleMethodWithParameter_Generator(int someIntParameter)"));
+        Assert.That(highlightedCode, Does.Not.Contain("return 5;"),
+            "MSGH007 should highlight the generator method signature, not the method body.");
+    }
+}

EasySourceGenerators.Generators/AnalyzerReleases.Unshipped.md

@@ -7,4 +7,5 @@ MSGH002 | GeneratesMethodGenerator | Error | GeneratesMethodGenerator
 MSGH003 | GeneratesMethodGenerator | Disabled | GeneratesMethodGenerator
 MSGH004 | GeneratesMethodGenerator | Error | GeneratesMethodGenerator
 MSGH005 | GeneratesMethodGenerator | Error | GeneratesMethodGenerator
-MSGH006 | GeneratesMethodGenerator | Error | GeneratesMethodGenerator
+MSGH006 | GeneratesMethodGenerator | Error | GeneratesMethodGenerator
+MSGH007 | GeneratesMethodGenerator | Error | GeneratesMethodGeneratorDiagnostics

EasySourceGenerators.Generators/GeneratesMethodGenerationPipeline.cs

@@ -1,5 +1,6 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
 using System.Collections.Immutable;
 using static EasySourceGenerators.Generators.Consts;
 
@@ -71,6 +72,21 @@ private static string GenerateSourceForGroup(
                 compilation);
         }
 
+        List<GeneratesMethodGenerationTarget> methodsWithParameters = methods
+            .Where(method => method.Symbol.Parameters.Length > 0)
+            .ToList();
+        if (methodsWithParameters.Count > 0)
+        {
+            foreach (GeneratesMethodGenerationTarget methodWithParameters in methodsWithParameters)
+            {
+                context.ReportDiagnostic(Diagnostic.Create(
+                    GeneratesMethodGeneratorDiagnostics.CannotUseRuntimeParameterForCompileTimeGeneratorError,
+                    GetMethodSignatureLocation(methodWithParameters.Syntax)));
+            }
+
+            return string.Empty;
+        }
+
         return GenerateFromSimplePattern(context, firstMethod, compilation);
     }
 
@@ -105,4 +121,10 @@ private static bool HasAttribute(IMethodSymbol methodSymbol, string fullAttribut
         return methodSymbol.GetAttributes()
             .Any(attribute => attribute.AttributeClass?.ToDisplayString() == fullAttributeTypeName);
     }
+
+    private static Location GetMethodSignatureLocation(MethodDeclarationSyntax methodSyntax)
+    {
+        TextSpan signatureSpan = TextSpan.FromBounds(methodSyntax.SpanStart, methodSyntax.ParameterList.Span.End);
+        return Location.Create(methodSyntax.SyntaxTree, signatureSpan);
+    }
 }

EasySourceGenerators.Generators/GeneratesMethodGenerator.Diagnostics.cs

@@ -53,4 +53,12 @@ internal static class GeneratesMethodGeneratorDiagnostics
         category: Category,
         defaultSeverity: DiagnosticSeverity.Error,
         isEnabledByDefault: true);
+    
+    internal static readonly DiagnosticDescriptor CannotUseRuntimeParameterForCompileTimeGeneratorError = new(
+        id: "MSGH007",
+        title: "Cannot use runtime parameter for compile-time generator",
+        messageFormat: "Method generators cannot have any parameters, as they will be run at compile time to generate the method output value. Use MethodTemplate if you want to emit method body instead of single value.",
+        category: Category,
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true);
 }