From 999f6e049b6d5158a3061afde47c3ff95c56ec37 Mon Sep 17 00:00:00 2001
From: Jonathan Algar <93204286+jonathanalgar@users.noreply.github.com>
Date: Sun, 23 Feb 2025 00:48:15 +0000
Subject: [PATCH 1/2] first shot

---
 src/CustomCode-Analyzer/Analyzer.cs           |  8 +++++++
 .../AnalyzerTests.cs                          | 24 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/CustomCode-Analyzer/Analyzer.cs b/src/CustomCode-Analyzer/Analyzer.cs
index 9e3ff44..7226235 100644
--- a/src/CustomCode-Analyzer/Analyzer.cs
+++ b/src/CustomCode-Analyzer/Analyzer.cs
@@ -1373,6 +1373,14 @@ private static bool IsValidParameterType(ITypeSymbol typeSymbol, Compilation com
                 return false;
             }
 
+            // If the type is nullable, unwrap it and check the underlying type
+            if (typeSymbol is INamedTypeSymbol named &&
+                named.OriginalDefinition.SpecialType == SpecialType.System_Nullable_T &&
+                named.TypeArguments.Length == 1)
+            {
+                typeSymbol = named.TypeArguments[0];
+            }
+
             // Check for primitive or special types
             if (ValidParameterSpecialTypes.Contains(typeSymbol.SpecialType))
             {
diff --git a/tests/CustomCode-Analyzer.Tests/AnalyzerTests.cs b/tests/CustomCode-Analyzer.Tests/AnalyzerTests.cs
index 9036836..d72db78 100644
--- a/tests/CustomCode-Analyzer.Tests/AnalyzerTests.cs
+++ b/tests/CustomCode-Analyzer.Tests/AnalyzerTests.cs
@@ -1136,6 +1136,30 @@ await CSharpAnalyzerVerifier<Analyzer>.VerifyAnalyzerAsync(
             );
         }
 
+        [TestMethod]
+        public async Task UnsupportedParameterTypeRule_InGlobalScope_PublicField_NullableStruct_NoWarning()
+        {
+            var test =
+                @"
+[OSStructure]
+public struct NestedStructure
+{
+    public int Value;
+}
+
+[OSStructure]
+public struct MyStructure
+{
+    public NestedStructure? NullableNested;    // Nullable struct OK
+}
+";
+            await CSharpAnalyzerVerifier<Analyzer>.VerifyAnalyzerAsync(
+                test,
+                TestContext,
+                skipSDKreference: false
+            );
+        }
+
         // --------------- ParameterByReferenceRule (OS-ELG-MODL-05016) ------------
         [TestMethod]
         public async Task ParameterByReferenceRule_InGlobalScope_ReportsWarning()

From 5d313072d941e136be201f137add74fea4cc6deb Mon Sep 17 00:00:00 2001
From: Jonathan Algar <93204286+jonathanalgar@users.noreply.github.com>
Date: Sun, 23 Feb 2025 00:52:10 +0000
Subject: [PATCH 2/2] format

---
 src/CustomCode-Analyzer/Analyzer.cs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/CustomCode-Analyzer/Analyzer.cs b/src/CustomCode-Analyzer/Analyzer.cs
index 7226235..f272e10 100644
--- a/src/CustomCode-Analyzer/Analyzer.cs
+++ b/src/CustomCode-Analyzer/Analyzer.cs
@@ -1374,9 +1374,11 @@ private static bool IsValidParameterType(ITypeSymbol typeSymbol, Compilation com
             }
 
             // If the type is nullable, unwrap it and check the underlying type
-            if (typeSymbol is INamedTypeSymbol named &&
-                named.OriginalDefinition.SpecialType == SpecialType.System_Nullable_T &&
-                named.TypeArguments.Length == 1)
+            if (
+                typeSymbol is INamedTypeSymbol named
+                && named.OriginalDefinition.SpecialType == SpecialType.System_Nullable_T
+                && named.TypeArguments.Length == 1
+            )
             {
                 typeSymbol = named.TypeArguments[0];
             }