CastExpressionOfIncompatibleTypeIssue: don't produce an issue when the source or target type is unknown.

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/CastExpressionOfIncompatibleTypeIssue.cs

@@ -71,6 +71,8 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 
 			void VisitTypeCastExpression (Expression expression, IType exprType, IType castToType)
 			{
+				if (exprType.Kind == TypeKind.Unknown || castToType.Kind == TypeKind.Unknown)
+					return;
 				var foundConversion = conversion.ExplicitConversion(exprType, castToType);
 				if (foundConversion == Conversion.None)
 					AddIssue (expression, ctx.TranslateString ("Type cast expression of incompatible type"));

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/CastExpressionOfIncompatibleTypeIssueTests.cs

@@ -56,7 +56,39 @@ class TestClass
 	void TestMethod ()
 	{
 		var x1 = (int)123;
-		var x2 = (int)System.ConsoleKey.A;
+		var x2 = (short)123;
+		var x3 = (int)System.ConsoleKey.A;
+	}
+}";
+			Test<CastExpressionOfIncompatibleTypeIssue> (input, 0);
+		}
+		
+		[Test]
+		public void UnknownIdentifierDoesNotCauseIncompatibleCastIssue ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod ()
+	{
+		var x1 = unknown as string;
+		var x2 = (string)unknown;
+	}
+}";
+
+			Test<CastExpressionOfIncompatibleTypeIssue> (input, 0);
+		}
+		
+		[Test]
+		public void UnknownTargetTypeDoesNotCauseIncompatibleCastIssue ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (int p)
+	{
+		var x1 = (unknown)p;
+		var x2 = p as unknown;
 	}
 }";