Can now cast all objects to [Serializable] types without custom type …

…check code (#419)

Runtime/CoreLib.Plugin/OOPEmulator.cs

@@ -508,6 +508,11 @@ private void AddClassMembers(JsClass c, string typevarName, List<JsStatement> st
 					}
 					_errorReporter.Region = oldReg;
 				}
+				else {
+						stmts.Add(JsExpression.Assign(
+						              JsExpression.Member(JsExpression.Identifier(typevarName), "isInstanceOfType"),
+						              JsExpression.FunctionDefinition(new string[0], JsStatement.Return(JsExpression.True))));
+				}
 			}
 
 			if (MetadataUtils.IsJsGeneric(c.CSharpTypeDefinition, _metadataImporter)) {

Runtime/CoreLib.TestScript/Reflection/TypeSystemLanguageSupportTests.cs

@@ -535,6 +535,26 @@ public void GetTypeOnNullInstanceThrowsException() {
 		}
 
 #pragma warning disable 219
+		private T Cast<T>(object o) {
+			return (T)o;
+		}
+
+		[Test]
+		public void CastOperatorForSerializableTypeWithoutTypeCheckCodeAlwaysSucceedsGeneric() {
+			object o = new object();
+			var b = Cast<BS>(o);
+			Assert.IsTrue(ReferenceEquals(o, b));
+		}
+
+		[Test]
+		public void CastOperatorsWorkForSerializableTypesWithCustomTypeCheckCodeGeneric() {
+			object o1 = new { x = 1 };
+			object o2 = new { x = 1, y = 2 };
+			Assert.Throws<InvalidCastException>(() => { var x = Cast<DS>(o1); });
+			var ds = Cast<DS>(o2);
+			Assert.IsTrue(ReferenceEquals(o2, ds));
+		}
+
 		[Test]
 		public void CastOperatorsWorkForSerializableTypesWithCustomTypeCheckCode() {
 			object o1 = new { x = 1 };

Runtime/CoreLib.Tests/OOPEmulatorTests/ClassTests.cs

@@ -833,6 +833,9 @@ [Serializable] public class B {}
 	var $this = {B}.$ctor();
 	return $this;
 };
+$D.isInstanceOfType = function() {
+	return true;
+};
 global.D = $D;
 -
 {Script}.initClass($D, $asm, {}, {B});
@@ -859,6 +862,9 @@ [Serializable] public interface I1 {}
 	var $this = {};
 	return $this;
 };
+$C.isInstanceOfType = function() {
+	return true;
+};
 global.C = $C;
 -
 {Script}.initClass($C, $asm, {}, null, [{I1}]);
@@ -1131,6 +1137,9 @@ [Serializable] public interface I2 {}
 var $I3 = function() {
 };
 $I3.__typeName = 'I3';
+$I3.isInstanceOfType = function() {
+	return true;
+};
 global.I3 = $I3;
 -
 {Script}.initInterface($I3, $asm, {}, [{I2}]);

history.txt

@@ -1,3 +1,4 @@
+Can now cast all objects to [Serializable] types without custom type check code (#419).
 Fixed handling of null in static string.Equals and non-static string.CompareTo and JsDate.CompareTo (#412).
 BREAKING CHANGE: Use full name instead of assembly-qualified names for generic arguments when creating generic type names in order to work around a bug regarding generic inheritance (#385, #484).
 Fixed a bug causing lifted comparisons to return the wrong value (#416).