Fixed the generated C# for default arguments of type pointer to a function.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/Generator/Passes/HandleDefaultParamValuesPass.cs

@@ -69,7 +69,8 @@ namespace CppSharp.Passes
             if (!desugared.IsPrimitiveTypeConvertibleToRef() &&
                 (expression.String == "0" || expression.String == "nullptr"))
             {
-                result = $"default({desugared})";
+                result = desugared.GetPointee()?.Desugar() is FunctionType ?
+                    "null" : $"default({desugared})";
                 return true;
             }
 
@@ -122,13 +123,6 @@ namespace CppSharp.Passes
             if (!desugared.IsPointer())
                 return false;
 
-            // IntPtr.Zero is not a constant
-            if (desugared.IsPointerToPrimitiveType(PrimitiveType.Void))
-            {
-                result = "new global::System.IntPtr()";
-                return true;
-            }
-
             if (desugared.IsPrimitiveTypeConvertibleToRef())
                 return false;
 

tests/CSharp/CSharp.Tests.cs

@@ -215,6 +215,7 @@ public unsafe class CSharpTests : GeneratorTestFixture
         {
             methodsWithDefaultValues.DefaultPointer();
             methodsWithDefaultValues.DefaultVoidStar();
+            methodsWithDefaultValues.DefaultFunctionPointer();
             methodsWithDefaultValues.DefaultValueType();
             methodsWithDefaultValues.DefaultChar();
             methodsWithDefaultValues.DefaultEmptyChar();

tests/CSharp/CSharp.cpp

@@ -556,6 +556,10 @@ void MethodsWithDefaultValues::defaultVoidStar(void* ptr)
 {
 }
 
+void MethodsWithDefaultValues::defaultFunctionPointer(void(*functionPtr)(int p))
+{
+}
+
 void MethodsWithDefaultValues::defaultValueType(QGenericArgument valueType)
 {
 }

tests/CSharp/CSharp.h

@@ -393,6 +393,7 @@ public:
     ~MethodsWithDefaultValues();
     void defaultPointer(Foo* ptr1 = 0, Foo* ptr2 = nullptr);
     void defaultVoidStar(void* ptr = 0);
+    void defaultFunctionPointer(void(*functionPtr)(int p) = nullptr);
     void defaultValueType(QGenericArgument valueType = QGenericArgument());
     void defaultChar(char c = 'a');
     void defaultEmptyChar(char c = 0);