clean up

src/Compilers/CSharp/Portable/Parser/LanguageParser.cs

@@ -5895,11 +5895,6 @@ private ScanTypeFlags ScanNonArrayType(ParseTypeMode mode, out SyntaxToken lastT
                     this.EatToken();
                 }
             }
-            else if (this.CurrentToken.Kind == SyntaxKind.InKeyword)
-            {
-                // Start of a lambda parameter
-                this.EatToken();
-            }
 
             if (this.CurrentToken.Kind == SyntaxKind.IdentifierToken)
             {
@@ -9815,6 +9810,7 @@ private bool ScanExplicitlyTypedLambda(Precedence precedence)
                             }
                             break;
                         case SyntaxKind.OutKeyword:
+                        case SyntaxKind.InKeyword:
                         case SyntaxKind.ParamsKeyword:
                             this.EatToken();
                             foundParameterModifier = true;

src/EditorFeatures/CSharpTest2/Recommendations/InKeywordRecommenderTests.cs

@@ -422,5 +422,14 @@ class Program
     public $$ int Test { get; set; }
 }");
         }
+
+        [Test.Utilities.CompilerTrait(Test.Utilities.CompilerFeature.ReadOnlyReferences)]
+        [Fact, Trait(Traits.Feature, Traits.Features.KeywordRecommending)]
+        public async Task TestNotAfterThis()
+        {
+            await VerifyAbsenceAsync(
+@"static class C {
+    static void Goo(this $$");
+        }
     }
 }

src/EditorFeatures/CSharpTest2/Recommendations/ThisKeywordRecommenderTests.cs

@@ -120,6 +120,14 @@ public async Task TestNotAfterRef()
     void Goo(ref $$");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.KeywordRecommending)]
+        public async Task TestNotAfterIn()
+        {
+            await VerifyAbsenceAsync(
+@"class C {
+    void Goo(in $$");
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.KeywordRecommending)]
         public async Task TestNotAfterThis_InBogusMethod()
         {
@@ -647,7 +655,22 @@ public static class Extensions
     public static void Extension(ref $$ object obj, int x) { }
 }");
         }
-        
+
+        [Fact]
+        public async Task TestExtensionMethods_FirstParameter_AfterInKeyword_InClass()
+        {
+            await VerifyKeywordAsync(@"
+public static class Extensions
+{
+    public static void Extension(in $$");
+
+            await VerifyKeywordAsync(@"
+public static class Extensions
+{
+    public static void Extension(in $$ object obj, int x) { }
+}");
+        }
+
         [Fact]
         public async Task TestExtensionMethods_SecondParameter_AfterRefKeyword_InClass()
         {
@@ -664,17 +687,17 @@ public static class Extensions
         }
 
         [Fact]
-        public async Task TestExtensionMethods_SecondParameter_AfterRefReadonlyKeywords_InClass()
+        public async Task TestExtensionMethods_SecondParameter_AfterInKeywords_InClass()
         {
             await VerifyAbsenceAsync(@"
 public static class Extensions
 {
-    public static void Extension(int x, ref readonly $$");
+    public static void Extension(int x, in $$");
 
             await VerifyAbsenceAsync(@"
 public static class Extensions
 {
-    public static void Extension(int x, ref readonly $$ object obj) { }
+    public static void Extension(int x, in $$ object obj) { }
 }");
         }
 
@@ -687,11 +710,11 @@ public async Task TestExtensionMethods_FirstParameter_AfterRefKeyword_OutsideCla
         }
 
         [Fact]
-        public async Task TestExtensionMethods_FirstParameter_AfterRefReadOnlyKeywords_OutsideClass()
+        public async Task TestExtensionMethods_FirstParameter_AfterInKeywords_OutsideClass()
         {
-            await VerifyAbsenceAsync("public static void Extension(ref readonly $$");
+            await VerifyAbsenceAsync("public static void Extension(in $$");
 
-            await VerifyAbsenceAsync("public static void Extension(ref readonly $$ object obj, int x) { }");
+            await VerifyAbsenceAsync("public static void Extension(in $$ object obj, int x) { }");
         }
 
         [Fact]
@@ -710,17 +733,17 @@ public class Extensions
         }
 
         [Fact]
-        public async Task TestExtensionMethods_FirstParameter_AfterRefReadOnlyKeywords_NonStaticClass()
+        public async Task TestExtensionMethods_FirstParameter_AfterInKeywords_NonStaticClass()
         {
             await VerifyAbsenceAsync(@"
 public class Extensions
 {
-    public static void Extension(ref readonly $$");
+    public static void Extension(in $$");
 
             await VerifyAbsenceAsync(@"
 public class Extensions
 {
-    public static void Extension(ref readonly $$ object obj, int x) { }
+    public static void Extension(in $$ object obj, int x) { }
 }");
         }
 
@@ -740,17 +763,17 @@ public static class Extensions
         }
 
         [Fact]
-        public async Task TestExtensionMethods_FirstParameter_AfterRefReadOnlyKeywords_NonStaticMethod()
+        public async Task TestExtensionMethods_FirstParameter_AfterInKeywords_NonStaticMethod()
         {
             await VerifyAbsenceAsync(@"
 public static class Extensions
 {
-    public void Extension(ref readonly $$");
+    public void Extension(in $$");
 
             await VerifyAbsenceAsync(@"
 public static class Extensions
 {
-    public void Extension(ref readonly $$ object obj, int x) { }
+    public void Extension(in $$ object obj, int x) { }
 }");
         }
     }

src/Workspaces/CSharp/Portable/Extensions/ContextQuery/SyntaxTreeExtensions.cs

@@ -1025,7 +1025,7 @@ public static bool IsDefaultExpressionContext(this SyntaxTree syntaxTree, int po
             }
 
             if (isThisKeyword &&
-                token.IsKind(SyntaxKind.RefKeyword) &&
+                (token.IsKind(SyntaxKind.RefKeyword) || token.IsKind(SyntaxKind.InKeyword)) &&
                 token.Parent.GetParent().IsDelegateOrConstructorOrLocalFunctionOrMethodParameterList())
             {
                 var parameter = token.GetAncestor<ParameterSyntax>();