From 1cd6f2ea178d590db3a7a3d9122cf7a463412698 Mon Sep 17 00:00:00 2001
From: Steve Dunn <steve@dunnhq.com>
Date: Sun, 10 May 2026 18:26:49 +0100
Subject: [PATCH] fix: handle semicolon-bodied types when adding methods

- Add regression test for semicolon-bodied types.
- Adjust `AddMethodCodeFixProvider` to convert semicolon-bodied types to braces before adding members.

Fixes #742
---
 .../AddMethodCodeFixProvider.cs               | 12 +++-
 .../AddMethodCodeFixProvider.cs               | 12 +++-
 .../ValidationMethodAnalyzerTests.cs          | 55 +++++++++++++++++++
 3 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/src/Vogen.CodeFixers/Rules/NormalizeInputMethodFixers/AddMethodCodeFixProvider.cs b/src/Vogen.CodeFixers/Rules/NormalizeInputMethodFixers/AddMethodCodeFixProvider.cs
index 3d8996e0311..0b2ade1d582 100644
--- a/src/Vogen.CodeFixers/Rules/NormalizeInputMethodFixers/AddMethodCodeFixProvider.cs
+++ b/src/Vogen.CodeFixers/Rules/NormalizeInputMethodFixers/AddMethodCodeFixProvider.cs
@@ -60,7 +60,17 @@ private static async Task<Document> GenerateMethodAsync(Document document,
 
             var newMember = GenerateMethod(returnType);
 
-            var newTypeDecl = typeDecl.AddMembers(newMember);
+            // If the type has no body (ends with ';'), convert it to have braces before adding members,
+            // otherwise AddMembers produces malformed output.
+            TypeDeclarationSyntax typeDeclWithBody = typeDecl.OpenBraceToken.IsKind(SyntaxKind.None)
+                ? typeDecl
+                    .WithSemicolonToken(SyntaxFactory.Token(SyntaxKind.None))
+                    .WithOpenBraceToken(SyntaxFactory.Token(SyntaxKind.OpenBraceToken))
+                    .WithCloseBraceToken(SyntaxFactory.Token(SyntaxKind.CloseBraceToken))
+                    .WithAdditionalAnnotations(Formatter.Annotation)
+                : typeDecl;
+
+            var newTypeDecl = typeDeclWithBody.AddMembers(newMember);
 
             var newRoot = root.ReplaceNode(typeDecl, newTypeDecl);
 
diff --git a/src/Vogen.CodeFixers/Rules/ValidateMethodFixers/AddMethodCodeFixProvider.cs b/src/Vogen.CodeFixers/Rules/ValidateMethodFixers/AddMethodCodeFixProvider.cs
index 5ca15d3ae04..01a7e40383f 100644
--- a/src/Vogen.CodeFixers/Rules/ValidateMethodFixers/AddMethodCodeFixProvider.cs
+++ b/src/Vogen.CodeFixers/Rules/ValidateMethodFixers/AddMethodCodeFixProvider.cs
@@ -60,7 +60,17 @@ private static async Task<Document> GenerateValidationMethodAsync(Document docum
 
             var newMember = GenerateMethod(returnType);
 
-            var newTypeDecl = typeDecl.AddMembers(newMember);
+            // If the type has no body (ends with ';'), convert it to have braces before adding members,
+            // otherwise AddMembers produces malformed output.
+            TypeDeclarationSyntax typeDeclWithBody = typeDecl.OpenBraceToken.IsKind(SyntaxKind.None)
+                ? typeDecl
+                    .WithSemicolonToken(SyntaxFactory.Token(SyntaxKind.None))
+                    .WithOpenBraceToken(SyntaxFactory.Token(SyntaxKind.OpenBraceToken))
+                    .WithCloseBraceToken(SyntaxFactory.Token(SyntaxKind.CloseBraceToken))
+                    .WithAdditionalAnnotations(Formatter.Annotation)
+                : typeDecl;
+
+            var newTypeDecl = typeDeclWithBody.AddMembers(newMember);
 
             var newRoot = root.ReplaceNode(typeDecl, newTypeDecl);
 
diff --git a/tests/AnalyzerTests/ValidationMethodAnalysis/ValidationMethodAnalyzerTests.cs b/tests/AnalyzerTests/ValidationMethodAnalysis/ValidationMethodAnalyzerTests.cs
index 54265135559..2abcf9529c0 100644
--- a/tests/AnalyzerTests/ValidationMethodAnalysis/ValidationMethodAnalyzerTests.cs
+++ b/tests/AnalyzerTests/ValidationMethodAnalysis/ValidationMethodAnalyzerTests.cs
@@ -301,6 +301,61 @@ private static Validation Validate(int input)
         await test.RunAsync();
     }
 
+    // Regression test for https://github.com/SteveDunn/Vogen/issues/742
+    [Fact]
+    public async Task Triggered_when_method_is_missing_and_type_has_semicolon_body()
+    {
+        var input = LineEndingsHelper.Normalize(
+            """
+            using System;
+            using Vogen;
+
+            namespace ConsoleApplication1;
+
+            [ValueObject<string>]
+            public readonly partial struct {|#0:RedemptionId|};
+            """);
+
+        var expectedOutput = LineEndingsHelper.Normalize(
+            """
+            using System;
+            using Vogen;
+
+            namespace ConsoleApplication1;
+
+            [ValueObject<string>]
+            public readonly partial struct RedemptionId
+            {
+                private static Validation Validate(string input)
+                {
+                    bool isValid = true; // todo: your validation
+                    return isValid ? Validation.Ok : Validation.Invalid("[todo: describe the validation]");
+                }
+            }
+            """);
+
+        var expectedDiagnostic =
+            VerifyCS.Diagnostic("AddValidationMethod").WithSeverity(DiagnosticSeverity.Info).WithLocation(0).WithArguments("RedemptionId");
+
+        var test = new VerifyCS.Test
+        {
+            TestState =
+            {
+                Sources = { input },
+                ReferenceAssemblies = References.Net90AndOurs.Value
+            },
+
+            CompilerDiagnostics = CompilerDiagnostics.Suggestions,
+            ReferenceAssemblies = References.Net90AndOurs.Value,
+            FixedCode = expectedOutput,
+            ExpectedDiagnostics = { expectedDiagnostic },
+        };
+
+        test.DisabledDiagnostics.Add("CS1591");
+
+        await test.RunAsync();
+    }
+
     //Diagnostic and CodeFix both triggered and checked for
     [Fact]
     public async Task Trigged_for_missing_method_and_vo_is_decorated_with_generic_attribute()