Add parenthesis around query expressions within type tests "(from a in b select c) is D"

ICSharpCode.NRefactory.Tests/CSharp/InsertParenthesesVisitorTests.cs

@@ -181,6 +181,27 @@ namespace ICSharpCode.NRefactory.CSharp
 			                "select a)", InsertReadable(expr));
 		}
 		
+		[Test]
+		public void QueryInTypeTest()
+		{
+			Expression expr = new QueryExpression {
+				Clauses = new QueryClause[] {
+					new QueryFromClause {
+						Identifier = "a",
+						Expression = new IdentifierExpression("b")
+					},
+					new QuerySelectClause {
+						Expression = new IdentifierExpression("a")
+					}
+				}
+			}.IsType(new PrimitiveType("int"));
+			
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) is int", InsertRequired(expr));
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) is int", InsertReadable(expr));
+		}
+		
 		[Test]
 		public void PrePost()
 		{

ICSharpCode.NRefactory/CSharp/OutputVisitor/InsertParenthesesVisitor.cs

@@ -257,11 +257,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		{
 			// Query expressions are strange beasts:
 			// "var a = -from b in c select d;" is valid, so queries bind stricter than unary expressions.
-			// However, the end of the query is greedy. So their start sort of have a high precedence,
+			// However, the end of the query is greedy. So their start sort of has a high precedence,
 			// while their end has a very low precedence. We handle this by checking whether a query is used
 			// as left part of a binary operator, and parenthesize it if required.
 			if (queryExpression.Role == BinaryOperatorExpression.LeftRole)
 				Parenthesize(queryExpression);
+			if (queryExpression.Parent is IsExpression || queryExpression.Parent is AsExpression)
+				Parenthesize(queryExpression);
 			if (InsertParenthesesForReadability) {
 				// when readability is desired, always parenthesize query expressions within unary or binary operators
 				if (queryExpression.Parent is UnaryOperatorExpression || queryExpression.Parent is BinaryOperatorExpression)