Fix ambiguous conversion functions (#1458)

src/Generator/Passes/CheckAmbiguousFunctions.cs

@@ -42,18 +42,19 @@ namespace CppSharp.Passes
 
             foreach (var overload in overloads)
             {
-                if (function.OperatorKind == CXXOperatorKind.Conversion)
-                    continue;
-                if (function.OperatorKind == CXXOperatorKind.ExplicitConversion)
-                    continue;
-
                 if (overload == function) continue;
 
                 if (!overload.IsGenerated) continue;
 
-                if (CheckConstnessForAmbiguity(function, overload) ||
+                var ambiguous = 
+                    function.OperatorKind == CXXOperatorKind.Conversion ||
+                    function.OperatorKind == CXXOperatorKind.ExplicitConversion
+                    ? CheckConversionAmbiguity(function, overload)
+                    : CheckConstnessForAmbiguity(function, overload) ||
                       CheckDefaultParametersForAmbiguity(function, overload) ||
-                    CheckParametersPointerConstnessForAmbiguity(function, overload))
+                      CheckParametersPointerConstnessForAmbiguity(function, overload);
+
+                if (ambiguous)
                 {
                     function.IsAmbiguous = true;
                     overload.IsAmbiguous = true;
@@ -172,6 +173,35 @@ namespace CppSharp.Passes
             return false;
         }
 
+        private bool CheckConversionAmbiguity(Function function, Function overload)
+        {
+            var method1 = function as Method;
+            var method2 = overload as Method;
+            if (method1 == null || method2 == null)
+                return false;
+
+            var type1 = method1.ReturnType.Type.Desugar();
+            var type2 = method2.ReturnType.Type.Desugar();
+
+            if (type1 is PointerType pointerType1 && 
+                type2 is PointerType pointerType2)
+            {
+                type1 = pointerType1.GetPointee();
+                type2 = pointerType2.GetPointee();
+            }
+
+            var mappedType1 = type1.GetMappedType(TypeMaps, Options.GeneratorKind);
+            var mappedType2 = type2.GetMappedType(TypeMaps, Options.GeneratorKind);
+
+            if (mappedType1.Equals(mappedType2))
+            {
+                method2.ExplicitlyIgnore();
+                return true;
+            }
+
+            return false;
+        }
+
         private static bool CheckParametersPointerConstnessForAmbiguity(
             Function function, Function overload)
         {

tests/CSharp/CSharp.Tests.cs

@@ -1538,4 +1538,14 @@ public unsafe class CSharpTests : GeneratorTestFixture
             Assert.That(out32, Is.EqualTo(cs));
         }
     }
+
+    [Test]
+    public void TestConversionFunction()
+    {
+        using (var c = new ConversionFunctions())
+        {
+            Assert.That(*(short*)c, Is.EqualTo(100));
+            Assert.That((short)c, Is.EqualTo(100));
+        }
+    }
 }

tests/CSharp/CSharp.cpp

@@ -1814,3 +1814,11 @@ const char32_t* TestCSharpString32(const char32_t* in, const char32_t** out)
     *out = ret.data();
     return ret.data();
 }
+
+ConversionFunctions::ConversionFunctions() = default;
+ConversionFunctions::operator short* () { return &field; }
+ConversionFunctions::operator short& () { return field; }
+ConversionFunctions::operator short() { return field; }
+ConversionFunctions::operator const short*() const { return &field; }
+ConversionFunctions::operator const short&() const { return field; }
+ConversionFunctions::operator const short() const { return field; }

tests/CSharp/CSharp.h

@@ -1495,6 +1495,19 @@ struct TestVariableWithoutType
     static constexpr auto variable = create(n...);
 };
 
+struct DLL_API ConversionFunctions
+{
+    ConversionFunctions();
+    operator short* ();
+    operator short& ();
+    operator short();
+    operator const short*() const;
+    operator const short&() const;
+    operator const short() const;
+
+    short field = 100;
+};
+
 DLL_API const char* TestCSharpString(const char* in, CS_OUT const char** out);
 DLL_API const wchar_t* TestCSharpStringWide(const wchar_t* in, CS_OUT const wchar_t** out);
 DLL_API const char16_t* TestCSharpString16(const char16_t* in, CS_OUT const char16_t** out);