CSharpExpressionPrinter: Wrap expression in parenthesis (mono#1741)

Wrap default parameter expressions in parentheses to ensure whole expressions are casted instead of only the first operand.

Author: trungnt2910

src/Generator/Generators/CSharp/CSharpExpressionPrinter.cs

@@ -27,11 +27,11 @@ public string VisitParameter(Parameter parameter)
             if (desugared.IsPrimitiveType() &&
                 (parameter.DefaultArgument.Declaration != null ||
                  parameter.DefaultArgument.Class == StatementClass.BinaryOperator))
-                return $"({desugared.Visit(typePrinter)}) {expression}";
+                return $"({desugared.Visit(typePrinter)}) ({expression})";
             var finalType = (desugared.GetFinalPointee() ?? desugared).Desugar();
             if (finalType.TryGetClass(out var @class) && @class.IsInterface)
                 return $@"({@class.Visit(typePrinter)}) ({
-                    @class.OriginalClass.Visit(typePrinter)}) {expression}";
+                    @class.OriginalClass.Visit(typePrinter)}) ({expression})";
             return expression;
         }
 
@@ -88,4 +88,4 @@ public string ToString(Type type)
 
         private readonly TypePrinter typePrinter;
     }
-}
+}

tests/dotnet/Common/Common.cpp

@@ -1273,4 +1273,8 @@ extern "C"
         s.field2 = 10;
         return s;
     }
-} // extern "C"
+} // extern "C"
+
+void DLL_API FunctionWithFlagsAsDefaultParameter(int defaultParam)
+{
+}

tests/dotnet/Common/Common.h

@@ -1567,3 +1567,5 @@ extern "C"
     DLL_API void takeConflictName(struct system* self);
     DLL_API struct system freeFunctionReturnByValue();
 } // extern "C"
+
+void DLL_API FunctionWithFlagsAsDefaultParameter(int defaultParam = A | B);