Fix generation for fields of type const reference

Fixes https://github.com/mono/CppSharp/issues/1323.

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

src/AST/Property.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using CppSharp.AST.Extensions;
 
 namespace CppSharp.AST
 {
@@ -86,7 +87,8 @@ namespace CppSharp.AST
                 return (SetMethod != null && 
                         SetMethod.GenerationKind != GenerationKind.None) ||
                        (Field != null && 
-                        !Field.QualifiedType.Qualifiers.IsConst && 
+                        (!Field.QualifiedType.IsConst() ||
+                         Field.Type.IsConstCharString()) &&
                         Field.GenerationKind != GenerationKind.None);
             }
         }

src/AST/TypeExtensions.cs

@@ -349,8 +349,6 @@
         public static bool IsConstRef(this QualifiedType type)
         {
             Type desugared = type.Type.Desugar();
-            Type pointee = desugared.GetFinalPointee().Desugar();
-            pointee = (pointee.GetFinalPointee() ?? pointee).Desugar();
             return desugared.IsReference() && type.IsConst();
         }
 
@@ -363,7 +361,7 @@
                 (pointee.IsPrimitiveType() || pointee.IsEnum()) && type.IsConst();
         }
 
-        private static bool IsConst(this QualifiedType type)
+        public static bool IsConst(this QualifiedType type)
         {
             return type.Type != null && (type.Qualifiers.IsConst ||
                 type.Type.GetQualifiedPointee().IsConst());

src/Generator/Generators/CLI/CLITypePrinter.cs

@@ -140,7 +140,8 @@ namespace CppSharp.Generators.CLI
                     return "::System::IntPtr";
 
                 var result = pointer.QualifiedPointee.Visit(this).ToString();
-                return !isRefParam && result == "::System::IntPtr" ? "void**" : result + "*";
+                return !isRefParam && result == "::System::IntPtr" ? "void**" :
+                    result + (pointer.IsReference ? "" : "*");
             }
 
             Enumeration @enum;

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -201,6 +201,8 @@ namespace CppSharp.Generators.CSharp
                     return true;
                 }
                 Context.Return.Write("*");
+                if (Context.MarshalKind == MarshalKind.NativeField)
+                    Context.Return.Write($"({pointer.QualifiedPointee.Visit(typePrinter)}*) ");
             }
 
             Context.Return.Write(Context.ReturnVarName);

tests/Common/Common.Tests.cs

@@ -559,6 +559,7 @@ public class CommonTests : GeneratorTestFixture
             Assert.That(prop.nestedEnum(55), Is.EqualTo(55));
 
             Assert.That(prop.Get32Bit, Is.EqualTo(10));
+            Assert.That(prop.ConstRefField, Is.EqualTo(prop.Field));
             Assert.That(prop.IsEmpty, Is.EqualTo(prop.Empty));
 
             Assert.That(prop.VirtualGetter, Is.EqualTo(15));

tests/Common/Common.cpp

@@ -542,7 +542,8 @@ SomeNamespace::AbstractClass::~AbstractClass()
 
 TestProperties::TestProperties() : Field(0), _refToPrimitiveInSetter(0),
     _getterAndSetterWithTheSameName(0), _setterReturnsBoolean(0),
-    _virtualSetterReturnsBoolean(0), _conflict(Conflict::Value1)
+    _virtualSetterReturnsBoolean(0), _conflict(Conflict::Value1),
+    ConstRefField(Field)
 {
 }
 
@@ -552,10 +553,22 @@ TestProperties::TestProperties(const TestProperties& other) : Field(other.Field)
     _getterAndSetterWithTheSameName(other._getterAndSetterWithTheSameName),
     _setterReturnsBoolean(other._setterReturnsBoolean),
     _virtualSetterReturnsBoolean(other._virtualSetterReturnsBoolean),
-    _conflict(other._conflict)
+    _conflict(other._conflict), ConstRefField(other.ConstRefField)
 {
 }
 
+TestProperties& TestProperties::operator=(const TestProperties& other)
+{
+    Field = other.Field;
+    FieldValue = other.FieldValue;
+    _refToPrimitiveInSetter = other._refToPrimitiveInSetter;
+    _getterAndSetterWithTheSameName = other._getterAndSetterWithTheSameName;
+    _setterReturnsBoolean = other._setterReturnsBoolean;
+    _virtualSetterReturnsBoolean = other._virtualSetterReturnsBoolean;
+    _conflict = other._conflict;
+    return *this;
+}
+
 int TestProperties::getFieldValue()
 {
     return Field;

tests/Common/Common.h

@@ -598,7 +598,9 @@ public:
 
     TestProperties();
     TestProperties(const TestProperties& other);
+    TestProperties& operator=(const TestProperties& other);
     int Field;
+    const int& ConstRefField;
 
     int getFieldValue();
     void setFieldValue(int Value);