Merge pull request #32748 from mavasani/Issue32727

Tweak bail out approach from unused member analyzer for struct layout types

src/EditorFeatures/CSharpTest/RemoveUnusedMembers/RemoveUnusedMembersTests.cs

@@ -2084,6 +2084,26 @@ class C
 }}");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnusedMembers)]
+        [WorkItem(32727, "https://github.com/dotnet/roslyn/issues/32727")]
+        public async Task NestedStructLayoutTypeWithReference()
+        {
+            await TestDiagnosticMissingAsync(
+@"using System.Runtime.InteropServices;
+
+class Program
+{
+    private const int [|MAX_PATH|] = 260;
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct ProcessEntry32
+    {
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_PATH)]
+        public string szExeFile;
+    }
+}");
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnusedMembers)]
         public async Task FixAllFields_Document()
         {

src/Features/Core/Portable/RemoveUnusedMembers/AbstractRemoveUnusedMembersDiagnosticAnalyzer.cs

@@ -154,13 +154,6 @@ private void RegisterActions(CompilationStartAnalysisContext compilationStartCon
                 Action<ISymbol, ValueUsageInfo> onSymbolUsageFound = OnSymbolUsage;
                 compilationStartContext.RegisterSymbolStartAction(symbolStartContext =>
                 {
-                    if (symbolStartContext.Symbol.GetAttributes().Any(a => a.AttributeClass == _structLayoutAttributeType))
-                    {
-                        // Bail out for types with 'StructLayoutAttribute' as the ordering of the members is critical,
-                        // and removal of unused members might break semantics.
-                        return;
-                    }
-
                     var hasInvalidOrDynamicOperation = false;
                     symbolStartContext.RegisterOperationAction(AnalyzeMemberReferenceOperation, OperationKind.FieldReference, OperationKind.MethodReference, OperationKind.PropertyReference, OperationKind.EventReference);
                     symbolStartContext.RegisterOperationAction(AnalyzeFieldInitializer, OperationKind.FieldInitializer);
@@ -351,6 +344,13 @@ private void OnSymbolEnd(SymbolAnalysisContext symbolEndContext, bool hasInvalid
                     return;
                 }
 
+                if (symbolEndContext.Symbol.GetAttributes().Any(a => a.AttributeClass == _structLayoutAttributeType))
+                {
+                    // Bail out for types with 'StructLayoutAttribute' as the ordering of the members is critical,
+                    // and removal of unused members might break semantics.
+                    return;
+                }
+
                 // Report diagnostics for unused candidate members.
                 var first = true;
                 PooledHashSet<ISymbol> symbolsReferencedInDocComments = null;