Generate valid C# for r-values to void pointers

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

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -556,7 +556,8 @@ namespace CppSharp.Generators.CSharp
                     Context.ArgumentPrefix.Write("&");
 
                 bool isVoid = primitive == PrimitiveType.Void &&
-                    pointee.IsAddress() && pointer.IsReference();
+                    pointee.IsAddress() && pointer.IsReference() &&
+                    pointer.GetFinalQualifiedPointee().Qualifiers.IsConst;
                 if (pointer.Pointee.Desugar(false) is TemplateParameterSubstitutionType ||
                     isVoid)
                 {

tests/CSharp/CSharp.Tests.cs

@@ -95,6 +95,7 @@ public unsafe class CSharpTests : GeneratorTestFixture
         }
 
         CSharp.CSharp.ReturnCharPointer();
+        CSharp.CSharp.RValueReferenceToPointer(null);
 
 #pragma warning restore 0168
 #pragma warning restore 0219

tests/CSharp/CSharp.cpp

@@ -1565,6 +1565,10 @@ const char*& takeConstCharStarRef(const char*& c)
     return c;
 }
 
+void rValueReferenceToPointer(void*&& v)
+{
+}
+
 boolean_t takeTypemapTypedefParam(boolean_t b)
 {
     return b;

tests/CSharp/CSharp.h

@@ -1307,6 +1307,7 @@ public:
 DLL_API void va_listFunction(va_list v);
 DLL_API char* returnCharPointer();
 DLL_API const char*& takeConstCharStarRef(const char*& c);
+DLL_API void rValueReferenceToPointer(void*&& v);
 
 struct {
     struct {