[Xamain.Android.Tools.Bytecode] Hide private Kotlin default constructors.

src/Xamarin.Android.Tools.Bytecode/Kotlin/KotlinUtilities.cs

@@ -97,8 +97,7 @@ public static string GetMethodNameWithoutUnsignedSuffix (string name)
 
 		public static bool IsDefaultConstructorMarker (this MethodInfo method)
 		{
-			// A default constructor is synthetic and always has an int and a
-			// DefaultConstructorMarker as its final 2 parameters.
+			// A default constructor is synthetic and has a DefaultConstructorMarker as its final parameter.
 			if (method.Name != "<init>")
 				return false;
 
@@ -107,12 +106,11 @@ public static bool IsDefaultConstructorMarker (this MethodInfo method)
 
 			var parameters = method.GetParameters ();
 
-			if (parameters.Length < 2)
+			if (parameters.Length < 1)
 				return false;
 
-			// Parameter list ends with `int, DefaultConstructorMarker`.
-			return parameters [parameters.Length - 2].Type.TypeSignature == "I" &&
-				parameters [parameters.Length - 1].Type.TypeSignature == "Lkotlin/jvm/internal/DefaultConstructorMarker;";
+			// Parameter list ends with `DefaultConstructorMarker`.
+			return parameters [parameters.Length - 1].Type.TypeSignature == "Lkotlin/jvm/internal/DefaultConstructorMarker;";
 		}
 
 		// Sometimes the Kotlin provided JvmSignature is null (or unhelpful), so we need to construct one ourselves

tests/Xamarin.Android.Tools.Bytecode-Tests/KotlinFixupsTests.cs

@@ -92,6 +92,28 @@ public void HideDefaultConstructorMarker ()
 			Assert.False (ctor_3p.AccessFlags.HasFlag (MethodAccessFlags.Public));
 		}
 
+		[Test]
+		public void HidePrivateDefaultConstructorMarker ()
+		{
+			var klass = LoadClassFile ("PrivateDefaultConstructor.class");
+
+			// init (int isFoo)
+			var ctor_1p = klass.Methods.Single (m => m.Name == "<init>" && m.GetParameters ().Length == 1);
+
+			// init (int isFoo, DefaultConstructorMarker p1)
+			var ctor_2p = klass.Methods.Single (m => m.Name == "<init>" && m.GetParameters ().Length == 2);
+
+			Assert.True (ctor_2p.AccessFlags.HasFlag (MethodAccessFlags.Public));
+
+			KotlinFixups.Fixup ([klass]);
+
+			// Assert that the normal constructor is still public
+			Assert.False (ctor_1p.AccessFlags.HasFlag (MethodAccessFlags.Public));
+
+			// Assert that the synthetic "DefaultConstructorMarker" constructor has been marked private
+			Assert.False (ctor_2p.AccessFlags.HasFlag (MethodAccessFlags.Public));
+		}
+
 		[Test]
 		public void HideImplementationMethod ()
 		{

tests/Xamarin.Android.Tools.Bytecode-Tests/kotlin/PrivateDefaultConstructor.kt

@@ -0,0 +1,5 @@
+public open class PrivateDefaultConstructor private constructor (internal val isFoo: Boolean) {
+	init { }
+
+	public companion object Default : PrivateDefaultConstructor (isFoo = false) { }
+}