Add an annotation to redundant ParenthesizedExpressions for PushNegation transform

ICSharpCode.Decompiler/Ast/Annotations.cs

@@ -12,4 +12,11 @@ namespace ICSharpCode.Decompiler.Ast
 			this.InferredType = inferredType;
 		}
 	}
+
+	sealed class InvisibleParenthesis
+	{
+		InvisibleParenthesis() { }
+
+		public static readonly InvisibleParenthesis Value = new InvisibleParenthesis();
+	}
 }

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -809,7 +809,7 @@ namespace ICSharpCode.Decompiler.Ast
 				case ILCode.InitializedObject:
 					return new InitializedObjectExpression();
 				case ILCode.Wrap:
-					return new ParenthesizedExpression(arg1);
+					return new ParenthesizedExpression(arg1).WithAnnotation(InvisibleParenthesis.Value);
 				case ILCode.AddressOf:
 					return MakeRef(arg1);
 				case ILCode.NullableOf:

ICSharpCode.Decompiler/Ast/Transforms/PushNegation.cs

@@ -150,9 +150,12 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 		public override object VisitParenthesizedExpression(ParenthesizedExpression expr, object data)
 		{
 			// extra parentheses are redundant after this transformation
-			var res = expr.Expression;
-			expr.ReplaceWith(res);
-			return res.AcceptVisitor(this, data);
+			if(expr.Annotation<InvisibleParenthesis>() != null)	{
+				var res = expr.Expression;
+				expr.ReplaceWith(res);
+				return res.AcceptVisitor(this, data);
+			}
+			return base.VisitParenthesizedExpression(expr, data);
 		}
 	}
 }