BUGFIX IDISP023 don't warn on attribute.

Fix #205

Author: JohanLarsson

IDisposableAnalyzers.Test/IDISP023ReferenceTypeInFinalizerContextTests/Valid.Finalizer.cs

@@ -1,4 +1,4 @@
-namespace IDisposableAnalyzers.Test.IDISP023ReferenceTypeInFinalizerContextTests
+namespace IDisposableAnalyzers.Test.IDISP023ReferenceTypeInFinalizerContextTests
 {
     using Gu.Roslyn.Asserts;
     using Microsoft.CodeAnalysis.Diagnostics;
@@ -157,6 +157,34 @@ public class C
 
                 RoslynAssert.Valid(Analyzer, code);
             }
+
+            [Test]
+            public static void AttributedFinalizer()
+            {
+                var code = @"
+namespace N
+{
+    using System;
+
+    [AttributeUsage(AttributeTargets.All)]
+    public class FooAttribute : Attribute { }
+
+    public sealed class C : IDisposable
+    {
+        [Foo]
+        ~C()
+        {
+        }
+
+        public void Dispose()
+        {
+            GC.SuppressFinalize(this);
+        }
+    }
+}";
+
+                RoslynAssert.Valid(Analyzer, code);
+            }
         }
     }
 }

IDisposableAnalyzers/Helpers/Walkers/FinalizerContextWalker.cs

@@ -92,7 +92,7 @@ public override void VisitIdentifierName(IdentifierNameSyntax node)
 
         internal static FinalizerContextWalker Borrow(BaseMethodDeclarationSyntax node, SemanticModel semanticModel, CancellationToken cancellationToken)
         {
-            var walker = BorrowAndVisit(node, SearchScope.Type, semanticModel, cancellationToken, () => new FinalizerContextWalker());
+            var walker = BorrowAndVisit((SyntaxNode)node.Body ?? node.ExpressionBody, SearchScope.Type, semanticModel, cancellationToken, () => new FinalizerContextWalker());
 
             foreach (var target in walker.Targets)
             {