Do not offer in C# 6.

src/EditorFeatures/CSharpTest/UsePatternMatching/CSharpIsAndCastCheckCodeRefactoringProviderTests.cs → src/EditorFeatures/CSharpTest/UsePatternMatching/CSharpIsAndCastCheckWithoutNameDiagnosticAnalyzerTests.cs

@@ -2,6 +2,7 @@
 
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.UsePatternMatching;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Diagnostics;
@@ -10,7 +11,7 @@
 
 namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.UsePatternMatching
 {
-    public partial class CSharpIsAndCastCheckCodeRefactoringProviderTests : AbstractCSharpDiagnosticProviderBasedUserDiagnosticTest
+    public partial class CSharpIsAndCastCheckWithoutNameDiagnosticAnalyzerTests : AbstractCSharpDiagnosticProviderBasedUserDiagnosticTest
     {
         internal override (DiagnosticAnalyzer, CodeFixProvider) CreateDiagnosticProviderAndFixer(Workspace workspace)
             => (new CSharpIsAndCastCheckWithoutNameDiagnosticAnalyzer(), new CSharpIsAndCastCheckWithoutNameCodeFixProvider());
@@ -27,7 +28,6 @@ bool M(object obj)
         return [||]obj is TestFile && ((TestFile)obj).i > 0;
     }
 }",
-
 @"class TestFile
 {
     int i;
@@ -38,6 +38,20 @@ bool M(object obj)
 }");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInlineTypeCheck)]
+        public async Task TestNotInCSharp6()
+        {
+            await TestMissingAsync(
+@"class TestFile
+{
+    int i;
+    bool M(object obj)
+    {
+        return [||]obj is TestFile && ((TestFile)obj).i > 0;
+    }
+}", parameters: new TestParameters(parseOptions: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp6)));
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsInlineTypeCheck)]
         public async Task TestExpressionBody()
         {

src/Features/CSharp/Portable/UsePatternMatching/CSharpIsAndCastCheckWithoutNameDiagnosticAnalyzer.cs

@@ -53,8 +53,16 @@ private void SyntaxNodeAction(SyntaxNodeAnalysisContext context)
         {
             var cancellationToken = context.CancellationToken;
             var semanticModel = context.SemanticModel;
-            var root = semanticModel.SyntaxTree.GetRoot(cancellationToken);
+            var syntaxTree = semanticModel.SyntaxTree;
+
+            // "x is Type y" is only available in C# 7.0 and above.  Don't offer this refactoring
+            // in projects targetting a lesser version.
+            if (((CSharpParseOptions)syntaxTree.Options).LanguageVersion < LanguageVersion.CSharp7)
+            {
+                return;
+            }
 
+            var root = syntaxTree.GetRoot(cancellationToken);
             var isExpression = (BinaryExpressionSyntax)context.Node;
 
             var workspace = (context.Options as WorkspaceAnalyzerOptions)?.Services.Workspace;