ParameterCanBeDemotedIssue no longer tries to demote arrays to ILists.

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

@@ -148,6 +148,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 					 orderby GetInheritanceDepth(type) ascending
 					 select type).ToList();
 				if (validTypes.Any()) {
+					// don't demote an array to IList
+					if (variable.Type.Kind == TypeKind.Array && validTypes.Any (t => t.Namespace == "System.Collections" && t.Name == "IList")) {
+						return;
+					}
 					AddIssue(parameter, ctx.TranslateString("Parameter can be demoted to base class"), GetActions(parameter, validTypes));
 					MembersWithIssues++;
 				}

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/ParameterCanBeDemotedIssue/ParameterCanBeDemotedTests.cs

@@ -921,6 +921,21 @@ class Test : TestBase
 	}
 }");
 		}
+
+		/// <summary>
+		/// Bug 9617 - Incorrect "parameter can be demoted to base class" warning for arrays
+		/// </summary>
+		[Test]
+		public void TestBug9617()
+		{
+			Test<ParameterCanBeDemotedIssue>(@"class Test
+{
+	object Foo (object[] arr)
+	{
+	    return arr [0];
+	}
+}", 0);
+		}
 	}
 }