Fix the getting of references to pointers in C#

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

Author: ddobrev

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -146,13 +146,25 @@ public override bool VisitPointerType(PointerType pointer, TypeQualifiers quals)
 
             var pointee = pointer.Pointee.Desugar();
             var finalPointee = pointer.GetFinalPointee().Desugar();
-            var type = Context.ReturnType.Type.Desugar(
+            var returnType = Context.ReturnType.Type.Desugar(
                 resolveTemplateSubstitution: false);
-            PrimitiveType primitive;
-            if ((pointee.IsConstCharString() && (isRefParam || type.IsReference())) ||
-                (!finalPointee.IsPrimitiveType(out primitive) &&
+            if ((pointee.IsConstCharString() && (isRefParam || returnType.IsReference())) ||
+                (!finalPointee.IsPrimitiveType(out PrimitiveType primitive) &&
                  !finalPointee.IsEnumType()))
+            {
+                if (Context.MarshalKind != MarshalKind.NativeField &&
+                    pointee.IsPointerTo(out Type type) &&
+                    type.Desugar().TryGetClass(out Class c))
+                {
+                    string ret = Generator.GeneratedIdentifier(Context.ReturnVarName);
+                    Context.Before.WriteLine($@"{typePrinter.IntPtrType} {ret} = {
+                        Context.ReturnVarName} == {typePrinter.IntPtrType}.Zero ? {
+                        typePrinter.IntPtrType}.Zero : new {
+                        typePrinter.IntPtrType}(*(void**) {Context.ReturnVarName});");
+                    Context.ReturnVarName = ret;
+                }
                 return pointer.QualifiedPointee.Visit(this);
+            }
 
             if (isRefParam)
             {
@@ -167,7 +179,7 @@ public override bool VisitPointerType(PointerType pointer, TypeQualifiers quals)
             if (Context.Function != null &&
                 Context.Function.OperatorKind == CXXOperatorKind.Subscript)
             {
-                if (type.IsPrimitiveType(primitive))
+                if (returnType.IsPrimitiveType(primitive))
                 {
                     Context.Return.Write("*");
                 }
@@ -517,7 +529,7 @@ public override bool VisitPointerType(PointerType pointer, TypeQualifiers quals)
                 if (param.IsOut)
                 {
                     MarshalString(pointee);
-                    Context.Return.Write("IntPtr.Zero");
+                    Context.Return.Write($"{typePrinter.IntPtrType}.Zero");
                     Context.ArgumentPrefix.Write("&");
                     return true;
                 }
@@ -604,7 +616,7 @@ public override bool VisitPointerType(PointerType pointer, TypeQualifiers quals)
                         arg, Context.Parameter.Name, Helpers.InstanceIdentifier);
                 }
 
-                Context.Return.Write($"new global::System.IntPtr(&{arg})");
+                Context.Return.Write($"new {typePrinter.IntPtrType}(&{arg})");
                 return true;
             }
 
@@ -614,7 +626,7 @@ public override bool VisitPointerType(PointerType pointer, TypeQualifiers quals)
                 pointer.QualifiedPointee.Visit(this);
                 Context.Before.WriteLine($"var {arg} = {Context.Return};");
                 Context.Return.StringBuilder.Clear();
-                Context.Return.Write($"new global::System.IntPtr(&{arg})");
+                Context.Return.Write($"new {typePrinter.IntPtrType}(&{arg})");
                 return true;
             }
 

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -1741,15 +1741,16 @@ private void GenerateVTableManagedCall(Method method)
                 }
             }
 
-            bool isVoid = method.OriginalReturnType.Type.Desugar().IsPrimitiveType(
-                PrimitiveType.Void);
+            Type returnType = method.OriginalReturnType.Type.Desugar();
+            bool isPrimitive = returnType.IsPrimitiveType();
+            bool isVoid = returnType.IsPrimitiveType(PrimitiveType.Void);
             var property = ((Class) method.Namespace).Properties.Find(
                 p => p.GetMethod == method || p.SetMethod == method);
             bool isSetter = property != null && property.SetMethod == method;
             var hasReturn = !isVoid && !isSetter;
 
             if (hasReturn)
-                Write($"var {Helpers.ReturnIdentifier} = ");
+                Write(isPrimitive && !isSetter ? "return " : $"var {Helpers.ReturnIdentifier} = ");
 
             Write($"{Helpers.TargetIdentifier}.");
             string marshalsCode = string.Join(", ", marshals);
@@ -1764,6 +1765,8 @@ private void GenerateVTableManagedCall(Method method)
                     Write($" = {marshalsCode}");
             }
             WriteLine(";");
+            if (isPrimitive && !isSetter)
+                return;
 
             if (hasReturn)
             {

tests/CSharp/CSharp.Tests.cs

@@ -1285,8 +1285,12 @@ public void TakeRefToPointerToObject()
     {
         using (Foo foo = new Foo { A = 25  })
         {
-            Foo returnedFoo = CSharp.CSharp.TakeRefToPointerToObject(foo);
+            Foo returnedFoo = CSharp.CSharp.TakeReturnReferenceToPointer(foo);
             Assert.That(returnedFoo.A, Is.EqualTo(foo.A));
+            using (Qux qux = new Qux())
+            {
+                Assert.That(qux.TakeReferenceToPointer(foo), Is.EqualTo(foo.A));
+            }
         }
     }
 

tests/CSharp/CSharp.cpp

@@ -225,6 +225,11 @@ void Qux::makeClassDynamic()
 {
 }
 
+int Qux::takeReferenceToPointer(Foo*& ret)
+{
+    return ret->A;
+}
+
 Bar::Bar(Qux qux)
 {
 }
@@ -1623,7 +1628,7 @@ const void*& rValueReferenceToPointer(void*&& v)
     return (const void*&) v;
 }
 
-const Foo* takeRefToPointerToObject(const Foo*& foo)
+const Foo*& takeReturnReferenceToPointer(const Foo*& foo)
 {
     return foo;
 }

tests/CSharp/CSharp.h

@@ -84,6 +84,7 @@ class DLL_API Qux
     Qux* getInterface();
     void setInterface(Qux* qux);
     virtual void makeClassDynamic();
+    virtual int takeReferenceToPointer(Foo*& ret);
 };
 
 class DLL_API Bar : public Qux
@@ -1325,7 +1326,7 @@ DLL_API char* returnCharPointer();
 DLL_API char* takeConstCharRef(const char& c);
 DLL_API const char*& takeConstCharStarRef(const char*& c);
 DLL_API const void*& rValueReferenceToPointer(void*&& v);
-DLL_API const Foo* takeRefToPointerToObject(const Foo*& foo);
+DLL_API const Foo*& takeReturnReferenceToPointer(const Foo*& foo);
 
 struct {
     struct {