Fixed review notes.

src/EditorFeatures/CSharpTest/Diagnostics/RemoveUnnecessaryCast/RemoveUnnecessaryCastTests.cs

@@ -3972,9 +3972,9 @@ private static void TakesParams(params object[] foo)
 
         [WorkItem(18510, "https://github.com/dotnet/roslyn/issues/18510")]
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnnecessaryCast)]
-        public async Task DontRemoveCastOnNegatingEnumValue()
+        public async Task DontRemoveCastOnNegatingEnumValue1()
         {
-            await TestInRegularAndScriptAsync(
+            await TestMissingInRegularAndScriptAsync(
 @"
 enum Sign
     {
@@ -3987,9 +3987,16 @@ class T
         void Foo()
         {
             Sign mySign = Sign.Positive;
-            Sign invertedSign = (Sign) ( |-(int) mySign| );
+            Sign invertedSign = (Sign) ( [|-(int) mySign|] );
         }
-    }",
+    }");
+        }
+
+        [WorkItem(18510, "https://github.com/dotnet/roslyn/issues/18510")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnnecessaryCast)]
+        public async Task DontRemoveCastOnNegatingEnumValue2()
+        {
+            await TestMissingInRegularAndScriptAsync(
 @"
 enum Sign
     {
@@ -4002,7 +4009,7 @@ class T
         void Foo()
         {
             Sign mySign = Sign.Positive;
-            Sign invertedSign = (Sign) ( -(int) mySign );
+            Sign invertedSign = (Sign) ( [|+(int) mySign|] );
         }
     }");
         }

src/Workspaces/CSharp/Portable/Extensions/CastExpressionSyntaxExtensions.cs

@@ -312,10 +312,9 @@ public static bool IsUnnecessaryCast(this CastExpressionSyntax cast, SemanticMod
             var expressionTypeInfo = semanticModel.GetTypeInfo(cast.Expression, cancellationToken);
             var expressionType = expressionTypeInfo.Type;
 
-            if (expressionType != null &&
-                expressionType.IsEnumType() 
-                && cast?.Parent is PrefixUnaryExpressionSyntax prefixUnaryExpression 
-                && prefixUnaryExpression.Kind() == SyntaxKind.UnaryMinusE xpression)
+            if (expressionType != null 
+                && expressionType.IsEnumType() 
+                && (cast.IsParentKind(SyntaxKind.UnaryMinusExpression) || cast.IsParentKind(SyntaxKind.UnaryPlusExpression)))
             {
                 return false;
             }