From a4a3668c455fe87f731803e4d0b3abfbc4f22198 Mon Sep 17 00:00:00 2001
From: Javier Calvarro Nelson <jacalvar@microsoft.com>
Date: Fri, 16 Apr 2021 19:03:55 +0200
Subject: [PATCH] [Blazor] Adds support for specifying generic type constraints
 in Razor files (#31800)

Adds support for specifying generic type constraints in the @typeparam directive.

The constraints are specified after the identifier for the type parameter using the same syntax used in c#. For example:
@typeparam TParameter where TParameter : Base, ISomeInterface, class, new()
---
 .../CodeGeneration/CodeWriterExtensions.cs    |  20 ++-
 .../CodeGeneration/DefaultDocumentWriter.cs   |   2 +-
 .../src/ComponentResources.resx               |   6 +
 .../ComponentDocumentClassifierPass.cs        |   6 +-
 .../Components/ComponentTypeParamDirective.cs |  42 ++++--
 .../DirectiveDescriptorBuilderExtensions.cs   |  19 ++-
 .../src/DirectiveTokenKind.cs                 |   5 +-
 .../DesignTimeDirectiveTargetExtension.cs     |  41 +++++-
 .../src/Intermediate/TypeParameter.cs         |   3 +-
 .../src/Legacy/CSharpCodeParser.cs            |  64 ++++++++-
 .../src/Legacy/CSharpKeyword.cs               |   3 +-
 .../Legacy/CSharpLanguageCharacteristics.cs   |   3 +-
 .../src/Legacy/CSharpTokenizer.cs             |   3 +-
 .../src/PublicAPI.Unshipped.txt               |   5 +
 .../src/RazorDiagnosticFactory.cs             |  20 +++
 .../src/RazorLanguageVersion.cs               |   6 +-
 .../src/RazorProjectEngine.cs                 |   8 +-
 .../src/Resources.resx                        |   6 +
 .../CodeGeneration/CSharpCodeWriterTest.cs    |   4 +-
 .../DefaultDocumentWriterTest.cs              |  50 +++++++-
 ...irectiveDescriptorBuilderExtensionsTest.cs |  16 ++-
 .../ComponentCodeGenerationTestBase.cs        |  30 +++++
 .../test/Legacy/RazorDirectivesTest.cs        |  73 +++++++++++
 .../test/RazorLanguageVersionTest.cs          |   2 +-
 .../TestComponent.codegen.cs                  | 121 ++++++++++++++++++
 .../TestComponent.ir.txt                      |  44 +++++++
 .../TestComponent.mappings.txt                |  59 +++++++++
 .../TestComponent.codegen.cs                  |  66 ++++++++++
 .../TestComponent.ir.txt                      |  21 +++
 .../TestComponent.mappings.txt                |  29 +++++
 ...ansitionsInAttributeValue_Throws.stree.txt |   4 +-
 .../HandlesQuotesAfterTransition.stree.txt    |   2 +-
 ...NotIdentifierStartOrParenOrBrace.stree.txt |   2 +-
 ...erTransitionInEmbeddedExpression.stree.txt |   2 +-
 ...sErrorIfNewlineFollowsTransition.stree.txt |   2 +-
 ...itionAndBlockStartInEmbeddedExpr.stree.txt |   2 +-
 ...deSpanIfEOFOccursAfterTransition.stree.txt |   2 +-
 ...nvalidCharacterFollowsTransition.stree.txt |   2 +-
 ...seBlockIgnoresSingleSlashAtStart.stree.txt |   2 +-
 ...licitExprDoesNotAcceptDotAfterAt.stree.txt |   2 +-
 ...SingleSpaceOrNewlineAtDesignTime.stree.txt |   2 +-
 ...ingleAtOutputsZeroLengthCodeSpan.stree.txt |   2 +-
 ...FileAndOutputsZeroLengthCodeSpan.stree.txt |   2 +-
 ...EmitsAtSignAsMarkupIfAtEndOfFile.stree.txt |   2 +-
 ...ansitionsInAttributeValue_Throws.stree.txt |   4 +-
 ...ConstraintIdentifierIsDifferent.cspans.txt |   8 ++
 ...enConstraintIdentifierIsDifferent.diag.txt |   1 +
 ...nConstraintIdentifierIsDifferent.stree.txt |  27 ++++
 ...WhenFirstTokenIsNotWhereKeyword.cspans.txt |   7 +
 ...orWhenFirstTokenIsNotWhereKeyword.diag.txt |   1 +
 ...rWhenFirstTokenIsNotWhereKeyword.stree.txt |  26 ++++
 ...traintTokenWorksWhenAtEndOfFile.cspans.txt |   8 ++
 ...straintTokenWorksWhenAtEndOfFile.stree.txt |  28 ++++
 ...erstandsGenericConstraintsToken.cspans.txt |   9 ++
 ...derstandsGenericConstraintsToken.stree.txt |  30 +++++
 ...Descriptor_WorksWhenAtEndOfFile.cspans.txt |   8 ++
 ...eDescriptor_WorksWhenAtEndOfFile.stree.txt |  28 ++++
 .../CanHandleSymbolBoundAttributes1.stree.txt |   2 +-
 .../CanHandleSymbolBoundAttributes2.stree.txt |   2 +-
 .../CanHandleSymbolBoundAttributes3.stree.txt |   2 +-
 .../CanHandleSymbolBoundAttributes4.stree.txt |   2 +-
 ...orEmptyTagHelperBoundAttributes1.stree.txt |   2 +-
 ...rEmptyTagHelperBoundAttributes10.stree.txt |   2 +-
 ...rEmptyTagHelperBoundAttributes11.stree.txt |   4 +-
 ...rEmptyTagHelperBoundAttributes12.stree.txt |   2 +-
 ...rEmptyTagHelperBoundAttributes13.stree.txt |   8 +-
 ...rEmptyTagHelperBoundAttributes14.stree.txt |  12 +-
 ...orEmptyTagHelperBoundAttributes2.stree.txt |   2 +-
 ...orEmptyTagHelperBoundAttributes3.stree.txt |   2 +-
 ...orEmptyTagHelperBoundAttributes4.stree.txt |   4 +-
 ...orEmptyTagHelperBoundAttributes5.stree.txt |   4 +-
 ...orEmptyTagHelperBoundAttributes6.stree.txt |   4 +-
 ...orEmptyTagHelperBoundAttributes7.stree.txt |   2 +-
 ...orEmptyTagHelperBoundAttributes8.stree.txt |   2 +-
 ...orEmptyTagHelperBoundAttributes9.stree.txt |   4 +-
 ...ForNonStringTagHelperAttributes1.stree.txt |   2 +-
 ...orNonStringTagHelperAttributes10.stree.txt |   4 +-
 ...orNonStringTagHelperAttributes11.stree.txt |  16 +--
 ...ForNonStringTagHelperAttributes2.stree.txt |   2 +-
 ...ForNonStringTagHelperAttributes3.stree.txt |   2 +-
 ...ForNonStringTagHelperAttributes4.stree.txt |   6 +-
 ...ForNonStringTagHelperAttributes7.stree.txt |  36 +++---
 ...ForNonStringTagHelperAttributes8.stree.txt |   4 +-
 ...ForNonStringTagHelperAttributes9.stree.txt |   4 +-
 ...tes_ComponentDirectiveAttributes.stree.txt |   2 +-
 ...tandsMinimizedAttributes_Block12.stree.txt |   2 +-
 ...tandsMinimizedAttributes_Block14.stree.txt |   2 +-
 ...dsMinimizedAttributes_Document12.stree.txt |   2 +-
 ...dsMinimizedAttributes_Document14.stree.txt |   2 +-
 ...partNonStringTagHelperAttributes.stree.txt |   2 +-
 .../AllowsPrefixedTagHelpers11.stree.txt      |   2 +-
 91 files changed, 1010 insertions(+), 134 deletions(-)
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.cspans.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.diag.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.stree.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.cspans.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.diag.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.stree.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.cspans.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.stree.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.cspans.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.stree.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.cspans.txt
 create mode 100644 src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.stree.txt

diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs
index 227f8d2ae3a4..52391af09061 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/CodeWriterExtensions.cs
@@ -297,7 +297,7 @@ public static CodeWriter WriteMethodInvocation(this CodeWriter writer, string me
 
         public static CodeWriter WriteMethodInvocation(this CodeWriter writer, string methodName, bool endLine, params string[] parameters)
         {
-            return 
+            return
                 WriteStartMethodInvocation(writer, methodName)
                 .Write(string.Join(", ", parameters))
                 .WriteEndMethodInvocation(endLine);
@@ -377,7 +377,7 @@ public static CSharpCodeWritingScope BuildClassDeclaration(
             string name,
             string baseType,
             IList<string> interfaces,
-            IList<string> typeParameters)
+            IList<(string name, string constraint)> typeParameters)
         {
             for (var i = 0; i < modifiers.Count; i++)
             {
@@ -391,7 +391,7 @@ public static CSharpCodeWritingScope BuildClassDeclaration(
             if (typeParameters != null && typeParameters.Count > 0)
             {
                 writer.Write("<");
-                writer.Write(string.Join(", ", typeParameters));
+                writer.Write(string.Join(", ", typeParameters.Select(tp => tp.name)));
                 writer.Write(">");
             }
 
@@ -419,6 +419,18 @@ public static CSharpCodeWritingScope BuildClassDeclaration(
             }
 
             writer.WriteLine();
+            if (typeParameters != null)
+            {
+                for (var i = 0; i < typeParameters.Count; i++)
+                {
+                    var constraint = typeParameters[i].constraint;
+                    if (constraint != null)
+                    {
+                        writer.Write(constraint);
+                        writer.WriteLine();
+                    }
+                }
+            }
 
             return new CSharpCodeWritingScope(writer);
         }
@@ -605,7 +617,7 @@ private class LinePragmaWriter : IDisposable
             private readonly string _sourceFilePath;
 
             public LinePragmaWriter(
-                CodeWriter writer, 
+                CodeWriter writer,
                 SourceSpan span,
                 CodeRenderingContext context)
             {
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/DefaultDocumentWriter.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/DefaultDocumentWriter.cs
index e23a3030e940..0c2d584e3487 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/DefaultDocumentWriter.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/CodeGeneration/DefaultDocumentWriter.cs
@@ -150,7 +150,7 @@ public override void VisitClassDeclaration(ClassDeclarationIntermediateNode node
                     node.ClassName,
                     node.BaseType,
                     node.Interfaces,
-                    node.TypeParameters.Select(p => p.ParameterName).ToArray()))
+                    node.TypeParameters.Select(p => (p.ParameterName, p.Constraints)).ToArray()))
                 {
                     VisitDefault(node);
                 }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/ComponentResources.resx b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/ComponentResources.resx
index cbadc7ee10de..86084bc5b020 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/ComponentResources.resx
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/ComponentResources.resx
@@ -216,6 +216,12 @@
   <data name="SplatTagHelper_Documentation" xml:space="preserve">
     <value>Merges a collection of attributes into the current element or component.</value>
   </data>
+  <data name="TypeParamDirective_Constraint_Description" xml:space="preserve">
+    <value>The constraints applied to the type parameter.</value>
+  </data>
+  <data name="TypeParamDirective_Constraint_Name" xml:space="preserve">
+    <value>type parameter constraint</value>
+  </data>
   <data name="TypeParamDirective_Description" xml:space="preserve">
     <value>Declares a generic type parameter for the generated component class.</value>
   </data>
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDocumentClassifierPass.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDocumentClassifierPass.cs
index d1828ca044a2..6f7ef8ab3694 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDocumentClassifierPass.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDocumentClassifierPass.cs
@@ -109,7 +109,11 @@ protected override void OnDocumentStructureCreated(
                         continue;
                     }
 
-                    @class.TypeParameters.Add(new TypeParameter() { ParameterName = typeParamNode.Tokens.First().Content, });
+                    @class.TypeParameters.Add(new TypeParameter()
+                    {
+                        ParameterName = typeParamNode.Tokens.First().Content,
+                        Constraints = typeParamNode.Tokens.Skip(1).FirstOrDefault()?.Content
+                    });
                 }
 
                 method.ReturnType = "void";
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentTypeParamDirective.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentTypeParamDirective.cs
index d37f84a0df8c..ff513d1df68d 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentTypeParamDirective.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentTypeParamDirective.cs
@@ -7,23 +7,45 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
 {
     internal class ComponentTypeParamDirective
     {
-        public static readonly DirectiveDescriptor Directive = DirectiveDescriptor.CreateDirective(
-            "typeparam",
-            DirectiveKind.SingleLine,
-            builder =>
-            {
-                builder.AddMemberToken(ComponentResources.TypeParamDirective_Token_Name, ComponentResources.TypeParamDirective_Token_Description);
-                builder.Usage = DirectiveUsage.FileScopedMultipleOccurring;
-                builder.Description = ComponentResources.TypeParamDirective_Description;
-            });
+        public static DirectiveDescriptor Directive = null;
 
-        public static RazorProjectEngineBuilder Register(RazorProjectEngineBuilder builder)
+        public static RazorProjectEngineBuilder Register(RazorProjectEngineBuilder builder, bool supportConstraints)
         {
             if (builder == null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
+            if (Directive == null)
+            {
+                // Do nothing and assume the first registration wins. In real life this directive is only ever registered once.
+                if (supportConstraints)
+                {
+                    Directive = DirectiveDescriptor.CreateDirective(
+                        "typeparam",
+                        DirectiveKind.SingleLine,
+                        builder =>
+                        {
+                            builder.AddMemberToken(ComponentResources.TypeParamDirective_Token_Name, ComponentResources.TypeParamDirective_Token_Description);
+                            builder.AddOptionalGenericTypeConstraintToken(ComponentResources.TypeParamDirective_Constraint_Name, ComponentResources.TypeParamDirective_Constraint_Description);
+                            builder.Usage = DirectiveUsage.FileScopedMultipleOccurring;
+                            builder.Description = ComponentResources.TypeParamDirective_Description;
+                        });
+                }
+                else
+                {
+                    Directive = DirectiveDescriptor.CreateDirective(
+                        "typeparam",
+                        DirectiveKind.SingleLine,
+                        builder =>
+                        {
+                            builder.AddMemberToken(ComponentResources.TypeParamDirective_Token_Name, ComponentResources.TypeParamDirective_Token_Description);
+                            builder.Usage = DirectiveUsage.FileScopedMultipleOccurring;
+                            builder.Description = ComponentResources.TypeParamDirective_Description;
+                        });
+                }
+            }
+
             builder.AddDirective(Directive, FileKinds.Component, FileKinds.ComponentImport);
             return builder;
         }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveDescriptorBuilderExtensions.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveDescriptorBuilderExtensions.cs
index 3e9c14b46f99..321e56b2ccd5 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveDescriptorBuilderExtensions.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveDescriptorBuilderExtensions.cs
@@ -1,4 +1,4 @@
-// Copyright(c) .NET Foundation.All rights reserved.
+// Copyright(c) .NET Foundation.All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -248,5 +248,22 @@ public static IDirectiveDescriptorBuilder AddOptionalAttributeToken(this IDirect
 
             return builder;
         }
+
+        public static IDirectiveDescriptorBuilder AddOptionalGenericTypeConstraintToken(this IDirectiveDescriptorBuilder builder, string name, string description)
+        {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            builder.Tokens.Add(
+                DirectiveTokenDescriptor.CreateToken(
+                    DirectiveTokenKind.GenericTypeConstraint,
+                    optional: true,
+                    name: name,
+                    description: description));
+
+            return builder;
+        }
     }
 }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveTokenKind.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveTokenKind.cs
index 88b214071c9e..e315df37f764 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveTokenKind.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DirectiveTokenKind.cs
@@ -1,4 +1,4 @@
-// Copyright(c) .NET Foundation.All rights reserved.
+// Copyright(c) .NET Foundation.All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 namespace Microsoft.AspNetCore.Razor.Language
@@ -11,5 +11,6 @@ public enum DirectiveTokenKind
         String,
         Attribute,
         Boolean,
+        GenericTypeConstraint,
     }
-}
\ No newline at end of file
+}
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Extensions/DesignTimeDirectiveTargetExtension.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Extensions/DesignTimeDirectiveTargetExtension.cs
index 6e5a87f47c46..dcb5e34b9d01 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Extensions/DesignTimeDirectiveTargetExtension.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Extensions/DesignTimeDirectiveTargetExtension.cs
@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -12,17 +12,17 @@ internal class DesignTimeDirectiveTargetExtension : IDesignTimeDirectiveTargetEx
         private const string DirectiveTokenHelperMethodName = "__RazorDirectiveTokenHelpers__";
         private const string TypeHelper = "__typeHelper";
 
-        public void WriteDesignTimeDirective(CodeRenderingContext context, DesignTimeDirectiveIntermediateNode node)
+        public void WriteDesignTimeDirective(CodeRenderingContext context, DesignTimeDirectiveIntermediateNode directiveNode)
         {
             context.CodeWriter
                 .WriteLine("#pragma warning disable 219")
                 .WriteLine($"private void {DirectiveTokenHelperMethodName}() {{");
 
-            for (var i = 0; i < node.Children.Count; i++)
+            for (var i = 0; i < directiveNode.Children.Count; i++)
             {
-                if (node.Children[i] is DirectiveTokenIntermediateNode n)
+                if (directiveNode.Children[i] is DirectiveTokenIntermediateNode directiveTokenNode)
                 {
-                    WriteDesignTimeDirectiveToken(context, n);
+                    WriteDesignTimeDirectiveToken(context, directiveNode, directiveTokenNode, currentIndex: i);
                 }
             }
 
@@ -31,7 +31,7 @@ public void WriteDesignTimeDirective(CodeRenderingContext context, DesignTimeDir
                 .WriteLine("#pragma warning restore 219");
         }
 
-        private void WriteDesignTimeDirectiveToken(CodeRenderingContext context, DirectiveTokenIntermediateNode node)
+        private void WriteDesignTimeDirectiveToken(CodeRenderingContext context, DesignTimeDirectiveIntermediateNode parent, DirectiveTokenIntermediateNode node, int currentIndex)
         {
             var tokenKind = node.DirectiveToken.Kind;
             if (!node.Source.HasValue ||
@@ -192,6 +192,35 @@ private void WriteDesignTimeDirectiveToken(CodeRenderingContext context, Directi
                             context.CodeWriter.WriteLine(";");
                         }
                         break;
+                    case DirectiveTokenKind.GenericTypeConstraint:
+                        // We generate a generic local function with a generic parameter using the
+                        // same name and apply the constraints, like below.
+                        // The two warnings that we disable are:
+                        // * Hiding the class type parameter with the parameter on the method
+                        // * The function is defined but not used.
+                        // static void TypeConstraints_TParamName<TParamName>() where TParamName ...;
+                        context.CodeWriter.WriteLine("#pragma warning disable CS0693");
+                        context.CodeWriter.WriteLine("#pragma warning disable CS8321");
+                        using (context.CodeWriter.BuildLinePragma(node.Source, context))
+                        {
+                            // It's OK to do this since a GenericTypeParameterConstraint token is always preceded by a member token.
+                            var genericTypeParamName = (DirectiveTokenIntermediateNode)parent.Children[currentIndex - 1];
+                            context.CodeWriter
+                                .Write("void __TypeConstraints_")
+                                .Write(genericTypeParamName.Content)
+                                .Write("<")
+                                .Write(genericTypeParamName.Content)
+                                .Write(">() ");
+
+                            context.AddSourceMappingFor(node);
+                            context.CodeWriter.Write(node.Content);
+                            context.CodeWriter.WriteLine();
+                            context.CodeWriter.WriteLine("{");
+                            context.CodeWriter.WriteLine("}");
+                            context.CodeWriter.WriteLine("#pragma warning restore CS0693");
+                            context.CodeWriter.WriteLine("#pragma warning restore CS8321");
+                        }
+                        break;
                 }
                 context.CodeWriter.CurrentIndent = originalIndent;
             }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Intermediate/TypeParameter.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Intermediate/TypeParameter.cs
index 08f953e23aeb..1b2b71650f19 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Intermediate/TypeParameter.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Intermediate/TypeParameter.cs
@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
@@ -6,5 +6,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
     public sealed class TypeParameter
     {
         public string ParameterName { get; set; }
+        public string Constraints { get; set; }
     }
 }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
index 510a89a511a7..7f967ea31fa2 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
@@ -66,6 +66,7 @@ internal class CSharpCodeParser : TokenizerBackedParser<CSharpTokenizer>
             "using",
             "namespace",
             "class",
+            "where"
         };
 
         private readonly ISet<string> CurrentKeywords = new HashSet<string>(DefaultKeywords);
@@ -1306,6 +1307,15 @@ private void ParseExtensibleDirective(in SyntaxListBuilder<RazorSyntaxNode> buil
                     // Even if an error was logged do not bail out early. If a directive was used incorrectly it doesn't mean it can't be parsed.
                     ValidateDirectiveUsage(descriptor, directiveStart);
 
+                    // Capture the last member for validating generic type constraints.
+                    // Generic type parameters are described by a member token followed by a generic constraint token.
+                    // The generic constraint token includes the 'where' keyword, the identifier it applies and the constraint list and is represented as a token list.
+                    // For the directive to be valid we need to check that the identifier for the member token matches the identifier in the generic constraint token.
+                    // Once we are parsing the constraint token we have lost "easy" access to the identifier for the member. To avoid having complex logic in the generic
+                    // constraint token parsing code, we instead keep track of the last identifier we've seen on a member token and use that information to check the
+                    // identifier for the constraint an emit a diagnostic in case they are not the same.
+                    string lastSeenMemberIdentifier = null;
+
                     for (var i = 0; i < descriptor.Tokens.Count; i++)
                     {
                         if (!At(SyntaxKind.Whitespace) &&
@@ -1327,14 +1337,16 @@ private void ParseExtensibleDirective(in SyntaxListBuilder<RazorSyntaxNode> buil
                         {
                             AcceptWhile(IsSpacingTokenIncludingComments);
 
+                            SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
+                            SpanContext.EditHandler.AcceptedCharacters = AcceptedCharactersInternal.Whitespace;
+
                             if (tokenDescriptor.Kind == DirectiveTokenKind.Member ||
                                 tokenDescriptor.Kind == DirectiveTokenKind.Namespace ||
                                 tokenDescriptor.Kind == DirectiveTokenKind.Type ||
                                 tokenDescriptor.Kind == DirectiveTokenKind.Attribute ||
+                                tokenDescriptor.Kind == DirectiveTokenKind.GenericTypeConstraint ||
                                 tokenDescriptor.Kind == DirectiveTokenKind.Boolean)
                             {
-                                SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
-                                SpanContext.EditHandler.AcceptedCharacters = AcceptedCharactersInternal.Whitespace;
                                 directiveBuilder.Add(OutputTokensAsStatementLiteral());
 
                                 if (EndOfFile || At(SyntaxKind.NewLine))
@@ -1350,8 +1362,6 @@ private void ParseExtensibleDirective(in SyntaxListBuilder<RazorSyntaxNode> buil
                             }
                             else
                             {
-                                SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
-                                SpanContext.EditHandler.AcceptedCharacters = AcceptedCharactersInternal.Whitespace;
                                 directiveBuilder.Add(OutputAsMarkupEphemeralLiteral());
                             }
                         }
@@ -1400,6 +1410,7 @@ private void ParseExtensibleDirective(in SyntaxListBuilder<RazorSyntaxNode> buil
                             case DirectiveTokenKind.Member:
                                 if (At(SyntaxKind.Identifier))
                                 {
+                                    lastSeenMemberIdentifier = CurrentToken.Content;
                                     AcceptAndMoveNext();
                                 }
                                 else
@@ -1459,6 +1470,51 @@ private void ParseExtensibleDirective(in SyntaxListBuilder<RazorSyntaxNode> buil
                                     return;
                                 }
 
+                                break;
+                            case DirectiveTokenKind.GenericTypeConstraint:
+                                if (At(SyntaxKind.Keyword) &&
+                                    string.Equals(CurrentToken.Content, CSharpLanguageCharacteristics.GetKeyword(CSharpKeyword.Where), StringComparison.Ordinal))
+                                {
+                                    // Consume the 'where' keyword plus any aditional whitespace
+                                    AcceptAndMoveNext();
+                                    AcceptWhile(SyntaxKind.Whitespace);
+                                    // Check that the type name matches the type name before the where clause.
+                                    // Find a better way to do this
+                                    if (!string.Equals(CurrentToken.Content, lastSeenMemberIdentifier, StringComparison.Ordinal))
+                                    {
+                                        // @typeparam TKey where TValue : ...
+                                        // The type parameter in the generic type constraint 'TValue' does not match the type parameter 'TKey' defined in the directive '@typeparam'.
+                                        Context.ErrorSink.OnError(
+                                            RazorDiagnosticFactory.CreateParsing_GenericTypeParameterIdentifierMismatch(
+                                                new SourceSpan(CurrentStart, CurrentToken.Content.Length), descriptor.Directive, CurrentToken.Content, lastSeenMemberIdentifier));
+                                        builder.Add(BuildDirective());
+                                        return;
+                                    }
+                                    else
+                                    {
+                                        while (!At(SyntaxKind.NewLine))
+                                        {
+                                            AcceptAndMoveNext();
+                                            if (EndOfFile)
+                                            {
+                                                // We've reached the end of the file, which is unusual but can happen, for example if we start typing in a new file.
+                                                break;
+                                            }
+                                        }
+                                    }
+                                }
+                                else
+                                {
+                                    Context.ErrorSink.OnError(
+                                        RazorDiagnosticFactory.CreateParsing_UnexpectedIdentifier(
+                                            new SourceSpan(CurrentStart, CurrentToken.Content.Length),
+                                            CurrentToken.Content,
+                                            CSharpLanguageCharacteristics.GetKeyword(CSharpKeyword.Where)));
+
+                                    builder.Add(BuildDirective());
+                                    return;
+                                }
+
                                 break;
                         }
 
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpKeyword.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpKeyword.cs
index b37807377ba1..f1ba9911d2d0 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpKeyword.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpKeyword.cs
@@ -83,6 +83,7 @@ internal enum CSharpKeyword
         Break,
         Checked,
         Namespace,
-        When
+        When,
+        Where
     }
 }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpLanguageCharacteristics.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpLanguageCharacteristics.cs
index febc9f649312..50a07886a687 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpLanguageCharacteristics.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpLanguageCharacteristics.cs
@@ -145,6 +145,7 @@ internal class CSharpLanguageCharacteristics : LanguageCharacteristics<CSharpTok
             { CSharpKeyword.Checked, "checked" },
             { CSharpKeyword.Namespace, "namespace" },
             { CSharpKeyword.When,  "when" },
+            { CSharpKeyword.Where,  "where" },
         };
 
         private static readonly CSharpLanguageCharacteristics _instance = new CSharpLanguageCharacteristics();
@@ -277,4 +278,4 @@ public static string GetKeyword(CSharpKeyword keyword)
             return value;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpTokenizer.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpTokenizer.cs
index 6f613675804c..765f63e38892 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpTokenizer.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpTokenizer.cs
@@ -93,7 +93,8 @@ internal class CSharpTokenizer : Tokenizer
             { "break", CSharpKeyword.Break },
             { "checked", CSharpKeyword.Checked },
             { "namespace", CSharpKeyword.Namespace },
-            { "when", CSharpKeyword.When }
+            { "when", CSharpKeyword.When },
+            { "where", CSharpKeyword.Where }
         };
 
         public CSharpTokenizer(ITextDocument source)
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/PublicAPI.Unshipped.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/PublicAPI.Unshipped.txt
index 8f38fcd0813c..d117adf7a59e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/PublicAPI.Unshipped.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/PublicAPI.Unshipped.txt
@@ -1,6 +1,7 @@
 #nullable enable
 Microsoft.AspNetCore.Razor.Language.CodeGeneration.CodeWriter.IndentWithTabs.get -> bool
 Microsoft.AspNetCore.Razor.Language.CodeGeneration.CodeWriter.TabSize.get -> int
+Microsoft.AspNetCore.Razor.Language.DirectiveTokenKind.GenericTypeConstraint = 6 -> Microsoft.AspNetCore.Razor.Language.DirectiveTokenKind
 Microsoft.AspNetCore.Razor.Language.Intermediate.CascadingGenericTypeParameter
 Microsoft.AspNetCore.Razor.Language.Intermediate.CascadingGenericTypeParameter.CascadingGenericTypeParameter() -> void
 ~Microsoft.AspNetCore.Razor.Language.CodeGeneration.CodeWriter.CodeWriter(string newLine, Microsoft.AspNetCore.Razor.Language.RazorCodeGenerationOptions options) -> void
@@ -13,4 +14,8 @@ Microsoft.AspNetCore.Razor.Language.Intermediate.CascadingGenericTypeParameter.C
 ~Microsoft.AspNetCore.Razor.Language.Intermediate.ComponentTypeInferenceMethodIntermediateNode.ReceivesCascadingGenericTypes.set -> void
 abstract Microsoft.AspNetCore.Razor.Language.RazorConfiguration.UseConsolidatedMvcViews.get -> bool
 *REMOVED*~static Microsoft.AspNetCore.Razor.Language.RazorConfiguration.Create(Microsoft.AspNetCore.Razor.Language.RazorLanguageVersion languageVersion, string configurationName, System.Collections.Generic.IEnumerable<Microsoft.AspNetCore.Razor.Language.RazorExtension> extensions) -> Microsoft.AspNetCore.Razor.Language.RazorConfiguration
+~Microsoft.AspNetCore.Razor.Language.Intermediate.TypeParameter.Constraints.get -> string
+~Microsoft.AspNetCore.Razor.Language.Intermediate.TypeParameter.Constraints.set -> void
+~static Microsoft.AspNetCore.Razor.Language.DirectiveDescriptorBuilderExtensions.AddOptionalGenericTypeConstraintToken(this Microsoft.AspNetCore.Razor.Language.IDirectiveDescriptorBuilder builder, string name, string description) -> Microsoft.AspNetCore.Razor.Language.IDirectiveDescriptorBuilder
 ~static Microsoft.AspNetCore.Razor.Language.RazorConfiguration.Create(Microsoft.AspNetCore.Razor.Language.RazorLanguageVersion languageVersion, string configurationName, System.Collections.Generic.IEnumerable<Microsoft.AspNetCore.Razor.Language.RazorExtension> extensions, bool useConsolidatedMvcViews = false) -> Microsoft.AspNetCore.Razor.Language.RazorConfiguration
+~static readonly Microsoft.AspNetCore.Razor.Language.RazorLanguageVersion.Version_6_0 -> Microsoft.AspNetCore.Razor.Language.RazorLanguageVersion
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorDiagnosticFactory.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorDiagnosticFactory.cs
index 9bef04b5bc24..d88879c15960 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorDiagnosticFactory.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorDiagnosticFactory.cs
@@ -436,6 +436,26 @@ public static RazorDiagnostic CreateParsing_DirectiveExpectsBooleanLiteral(Sourc
         {
             return RazorDiagnostic.Create(Parsing_DirectiveExpectsBooleanLiteral, location, directiveName);
         }
+
+        internal static readonly RazorDiagnosticDescriptor Parsing_GenericTypeParameterIdentifierMismatch =
+            new RazorDiagnosticDescriptor(
+                $"{DiagnosticPrefix}1039",
+                () => Resources.DirectiveGenericTypeParameterIdentifierMismatch,
+                RazorDiagnosticSeverity.Error);
+        public static RazorDiagnostic CreateParsing_GenericTypeParameterIdentifierMismatch(SourceSpan location, string directiveName, string constraintIdentifier, string originalMember)
+        {
+            return RazorDiagnostic.Create(Parsing_GenericTypeParameterIdentifierMismatch, location, directiveName, constraintIdentifier, originalMember);
+        }
+
+        internal static readonly RazorDiagnosticDescriptor Parsing_UnexpectedIdentifier =
+            new RazorDiagnosticDescriptor(
+                $"{DiagnosticPrefix}1040",
+                () => Resources.ParseError_Unexpected_Identifier_At_Position,
+                RazorDiagnosticSeverity.Error);
+        public static RazorDiagnostic CreateParsing_UnexpectedIdentifier(SourceSpan location, string content, params string [] options)
+        {
+            return RazorDiagnostic.Create(Parsing_UnexpectedIdentifier, location, content, string.Join(", ", options));
+        }
         #endregion
 
         #region Semantic Errors
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorLanguageVersion.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorLanguageVersion.cs
index 7913dac29bc2..f2e00b3f9e9e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorLanguageVersion.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorLanguageVersion.cs
@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -22,7 +22,9 @@ public sealed class RazorLanguageVersion : IEquatable<RazorLanguageVersion>, ICo
 
         public static readonly RazorLanguageVersion Version_5_0 = new RazorLanguageVersion(5, 0);
 
-        public static readonly RazorLanguageVersion Latest = Version_5_0;
+        public static readonly RazorLanguageVersion Version_6_0 = new RazorLanguageVersion(6, 0);
+
+        public static readonly RazorLanguageVersion Latest = Version_6_0;
 
         public static readonly RazorLanguageVersion Experimental = new RazorLanguageVersion(1337, 1337);
 
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorProjectEngine.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorProjectEngine.cs
index 9d074110dc2a..2b2e79923d12 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorProjectEngine.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/RazorProjectEngine.cs
@@ -221,7 +221,13 @@ private static void AddComponentFeatures(RazorProjectEngineBuilder builder, Razo
             ComponentInjectDirective.Register(builder);
             ComponentLayoutDirective.Register(builder);
             ComponentPageDirective.Register(builder);
-            ComponentTypeParamDirective.Register(builder);
+
+            // Unconditionally enable the feature for the time being until we flow the SDK with the flow version
+            // into the repository.
+            ComponentTypeParamDirective.Register(
+                builder,
+                supportConstraints: true);
+                //supportConstraints: razorLanguageVersion.CompareTo(RazorLanguageVersion.Version_6_0) >= 0);
 
             if (razorLanguageVersion.CompareTo(RazorLanguageVersion.Version_5_0) >= 0)
             {
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Resources.resx b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Resources.resx
index a6fe1ab23554..8fa60e30c6e6 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Resources.resx
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Resources.resx
@@ -565,4 +565,10 @@
   <data name="CssRewriter_ImportNotAllowed" xml:space="preserve">
     <value>@import rules are not supported within scoped CSS files because the loading order would be undefined. @import may only be placed in non-scoped CSS files.</value>
   </data>
+  <data name="DirectiveGenericTypeParameterIdentifierMismatch" xml:space="preserve">
+    <value>The type parameter in the generic type constraint '{1}' does not match the type parameter '{2}' defined in the directive '{0}'.</value>
+  </data>
+  <data name="ParseError_Unexpected_Identifier_At_Position" xml:space="preserve">
+    <value>'{0}' is not valid in this position. Valid options are '{1}'</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/CSharpCodeWriterTest.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/CSharpCodeWriterTest.cs
index 88f4447eda61..9f5e7a0f10c5 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/CSharpCodeWriterTest.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/CSharpCodeWriterTest.cs
@@ -373,7 +373,7 @@ public void CSharpCodeWriter_RespectTabSetting()
             var writer = new CodeWriter(Environment.NewLine, options);
 
             // Act
-            writer.BuildClassDeclaration(Array.Empty<string>(), "C", "", Array.Empty<string>(), Array.Empty<string>());
+            writer.BuildClassDeclaration(Array.Empty<string>(), "C", "", Array.Empty<string>(), Array.Empty<(string,string)>());
             writer.WriteField(Array.Empty<string>(), Array.Empty<string>(), "int", "f");
 
             // Assert
@@ -394,7 +394,7 @@ public void CSharpCodeWriter_RespectSpaceSetting()
             var writer = new CodeWriter(Environment.NewLine, options);
 
             // Act
-            writer.BuildClassDeclaration(Array.Empty<string>(), "C", "", Array.Empty<string>(), Array.Empty<string>());
+            writer.BuildClassDeclaration(Array.Empty<string>(), "C", "", Array.Empty<string>(), Array.Empty<(string, string)>());
             writer.WriteField(Array.Empty<string>(), Array.Empty<string>(), "int", "f");
 
             // Assert
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/DefaultDocumentWriterTest.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/DefaultDocumentWriterTest.cs
index 3537eea4f61a..72271025d8f1 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/DefaultDocumentWriterTest.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/DefaultDocumentWriterTest.cs
@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -250,6 +250,54 @@ internal class TestClass<TKey, TValue> : TestBase, IFoo, IBar
                 ignoreLineEndingDifferences: true);
         }
 
+        [Fact]
+        public void WriteDocument_WritesClass_ConstrainedGenericTypeParameters()
+        {
+            // Arrange
+            var document = new DocumentIntermediateNode();
+            var builder = IntermediateNodeBuilder.Create(document);
+            builder.Add(new ClassDeclarationIntermediateNode()
+            {
+                Modifiers =
+                {
+                    "internal"
+                },
+                BaseType = "TestBase",
+                Interfaces = new List<string> { "IFoo", "IBar", },
+                TypeParameters = new List<TypeParameter>
+                {
+                    new TypeParameter() { ParameterName = "TKey", Constraints = "where TKey : class" },
+                    new TypeParameter() { ParameterName = "TValue", Constraints = "where TValue : class" },
+                },
+                ClassName = "TestClass",
+            });
+
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+            var options = RazorCodeGenerationOptions.CreateDefault();
+
+            var target = CodeTarget.CreateDefault(codeDocument, options);
+            var writer = new DefaultDocumentWriter(target, options);
+
+            // Act
+            var result = writer.WriteDocument(codeDocument, document);
+
+            // Assert
+            var csharp = result.GeneratedCode;
+            Assert.Equal(
+@"#pragma checksum ""test.cshtml"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""da39a3ee5e6b4b0d3255bfef95601890afd80709""
+// <auto-generated/>
+#pragma warning disable 1591
+internal class TestClass<TKey, TValue> : TestBase, IFoo, IBar
+where TKey : class
+where TValue : class
+{
+}
+#pragma warning restore 1591
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
         [Fact]
         public void WriteDocument_WritesMethod()
         {
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/DirectiveDescriptorBuilderExtensionsTest.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/DirectiveDescriptorBuilderExtensionsTest.cs
index 6e78ea1eec62..6bc388d93e4f 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/DirectiveDescriptorBuilderExtensionsTest.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/DirectiveDescriptorBuilderExtensionsTest.cs
@@ -1,4 +1,4 @@
-// Copyright(c) .NET Foundation.All rights reserved.
+// Copyright(c) .NET Foundation.All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Xunit;
@@ -146,5 +146,19 @@ public void AddOptionalAttributeToken_AddsToken()
             Assert.Null(token.Name);
             Assert.Null(token.Description);
         }
+
+        [Fact]
+        public void AddOptionalGenericTypeConstraintToken_AddsToken()
+        {
+            // Arrange & Act
+            var descriptor = DirectiveDescriptor.CreateDirective("custom", DirectiveKind.SingleLine, b => b.AddOptionalGenericTypeConstraintToken("Name", "Description"));
+
+            // Assert
+            var token = Assert.Single(descriptor.Tokens);
+            Assert.Equal(DirectiveTokenKind.GenericTypeConstraint, token.Kind);
+            Assert.True(token.Optional);
+            Assert.Equal("Name", token.Name);
+            Assert.Equal("Description", token.Description);
+        }
     }
 }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
index c06fc20f3d1a..c25d030ef099 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
@@ -211,6 +211,36 @@ public void ComponentWithTypeParameters()
 @typeparam TItem1
 @typeparam TItem2
 
+<h1>Item1</h1>
+@foreach (var item2 in Items2)
+{
+    <p>
+    @ChildContent(item2);
+    </p>
+}
+@code {
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+}");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
+        [Fact]
+        public void ComponentWithConstrainedTypeParameters()
+        {
+            // Arrange
+
+            // Act
+            var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components;
+@typeparam TItem1 where TItem1 : class
+@typeparam TItem2 where TItem2 : struct
+
 <h1>Item1</h1>
 @foreach (var item2 in Items2)
 {
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/Legacy/RazorDirectivesTest.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/Legacy/RazorDirectivesTest.cs
index 946fea9b51af..e70766d8382e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/Legacy/RazorDirectivesTest.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/Legacy/RazorDirectivesTest.cs
@@ -907,6 +907,79 @@ public void Directives_ReservedWordInsideCodeBlock()
             ParseDocumentTest("@{ class }");
         }
 
+        [Fact]
+        public void DirectiveDescriptor_UnderstandsGenericConstraintsToken()
+        {
+            // Arrange
+            var descriptor = DirectiveDescriptor.CreateDirective(
+                "custom",
+                DirectiveKind.SingleLine,
+                b => {
+                    b.AddMemberToken();
+                    b.AddOptionalGenericTypeConstraintToken("name", "description");
+                });
+
+            // Act & Assert
+            ParseDocumentTest(@"
+@custom TSomething where TSomething : class
+",
+                new[] { descriptor });
+        }
+
+        [Fact]
+        public void DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile()
+        {
+            // Arrange
+            var descriptor = DirectiveDescriptor.CreateDirective(
+                "custom",
+                DirectiveKind.SingleLine,
+                b => {
+                    b.AddMemberToken();
+                    b.AddOptionalGenericTypeConstraintToken("name", "description");
+                });
+
+            // Act & Assert
+            ParseDocumentTest(@"
+@custom TSomething where TSomething : class",
+                directives: new[] { descriptor });
+        }
+
+        [Fact]
+        public void DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword()
+        {
+            // Arrange
+            var descriptor = DirectiveDescriptor.CreateDirective(
+                "custom",
+                DirectiveKind.SingleLine,
+                b => {
+                    b.AddMemberToken();
+                    b.AddOptionalGenericTypeConstraintToken("name", "description");
+                });
+
+            // Act & Assert
+            ParseDocumentTest(@"
+@custom TSomething maybe TSomething : class",
+                directives: new[] { descriptor });
+        }
+
+        [Fact]
+        public void DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent()
+        {
+            // Arrange
+            var descriptor = DirectiveDescriptor.CreateDirective(
+                "custom",
+                DirectiveKind.SingleLine,
+                b => {
+                    b.AddMemberToken();
+                    b.AddOptionalGenericTypeConstraintToken("name", "description");
+                });
+
+            // Act & Assert
+            ParseDocumentTest(@"
+@custom TSomething where TElse : class",
+                directives: new[] { descriptor });
+        }
+
         [Fact]
         public void DirectiveDescriptor_UnderstandsAttributeTokens()
         {
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/RazorLanguageVersionTest.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/RazorLanguageVersionTest.cs
index 4542300aac43..9eb3bc526c33 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/RazorLanguageVersionTest.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/RazorLanguageVersionTest.cs
@@ -118,7 +118,7 @@ public void TryParseLatest()
 
             // Assert
             Assert.True(result);
-            Assert.Same(RazorLanguageVersion.Version_5_0, version);
+            Assert.Same(RazorLanguageVersion.Version_6_0, version);
         }
 
         [Fact]
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
new file mode 100644
index 000000000000..2389f9b83f94
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
@@ -0,0 +1,121 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+using Microsoft.AspNetCore.Components;
+
+#line default
+#line hidden
+#nullable disable
+    public partial class TestComponent<TItem1, TItem2> : Microsoft.AspNetCore.Components.ComponentBase
+    where TItem1 : class
+    where TItem2 : struct
+    {
+        #pragma warning disable 219
+        private void __RazorDirectiveTokenHelpers__() {
+        ((System.Action)(() => {
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+global::System.Object TItem1 = null!;
+
+#line default
+#line hidden
+#nullable disable
+        }
+        ))();
+        ((System.Action)(() => {
+#pragma warning disable CS0693
+#pragma warning disable CS8321
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+void __TypeConstraints_TItem1<TItem1>() where TItem1 : class
+{
+}
+#pragma warning restore CS0693
+#pragma warning restore CS8321
+
+#line default
+#line hidden
+#nullable disable
+        }
+        ))();
+        ((System.Action)(() => {
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+global::System.Object TItem2 = null!;
+
+#line default
+#line hidden
+#nullable disable
+        }
+        ))();
+        ((System.Action)(() => {
+#pragma warning disable CS0693
+#pragma warning disable CS8321
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+void __TypeConstraints_TItem2<TItem2>() where TItem2 : struct
+{
+}
+#pragma warning restore CS0693
+#pragma warning restore CS8321
+
+#line default
+#line hidden
+#nullable disable
+        }
+        ))();
+        }
+        #pragma warning restore 219
+        #pragma warning disable 0414
+        private static System.Object __o = null;
+        #pragma warning restore 0414
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 6 "x:\dir\subdir\Test\TestComponent.cshtml"
+ foreach (var item2 in Items2)
+{
+    
+
+#line default
+#line hidden
+#nullable disable
+#nullable restore
+#line 9 "x:\dir\subdir\Test\TestComponent.cshtml"
+__o = ChildContent(item2);
+
+#line default
+#line hidden
+#nullable disable
+#nullable restore
+#line 10 "x:\dir\subdir\Test\TestComponent.cshtml"
+        
+}
+
+#line default
+#line hidden
+#nullable disable
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 12 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
new file mode 100644
index 000000000000..7a154d09616b
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
@@ -0,0 +1,44 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [12] ) - System
+        UsingDirective - (18:2,1 [32] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [17] ) - System.Linq
+        UsingDirective - (73:4,1 [28] ) - System.Threading.Tasks
+        UsingDirective - (1:0,1 [38] x:\dir\subdir\Test\TestComponent.cshtml) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase -  - TItem1, TItem2
+            DesignTimeDirective - 
+                DirectiveToken - (52:1,11 [6] x:\dir\subdir\Test\TestComponent.cshtml) - TItem1
+                DirectiveToken - (59:1,18 [20] x:\dir\subdir\Test\TestComponent.cshtml) - where TItem1 : class
+                DirectiveToken - (92:2,11 [6] x:\dir\subdir\Test\TestComponent.cshtml) - TItem2
+                DirectiveToken - (99:2,18 [21] x:\dir\subdir\Test\TestComponent.cshtml) - where TItem2 : struct
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning disable 0414
+            CSharpCode - 
+                IntermediateToken -  - CSharp - private static System.Object __o = null;
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning restore 0414
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                HtmlContent - (39:0,39 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (39:0,39 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+                HtmlContent - (122:3,0 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (122:3,0 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+                MarkupElement - (124:4,0 [14] x:\dir\subdir\Test\TestComponent.cshtml) - h1
+                    HtmlContent - (128:4,4 [5] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (128:4,4 [5] x:\dir\subdir\Test\TestComponent.cshtml) - Html - Item1
+                HtmlContent - (138:4,14 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (138:4,14 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+                CSharpCode - (141:5,1 [38] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (141:5,1 [38] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - foreach (var item2 in Items2)\n{\n    
+                MarkupElement - (179:7,4 [40] x:\dir\subdir\Test\TestComponent.cshtml) - p
+                    HtmlContent - (182:7,7 [6] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (182:7,7 [6] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n    
+                    CSharpExpression - (189:8,5 [19] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (189:8,5 [19] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ChildContent(item2)
+                    HtmlContent - (208:8,24 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (208:8,24 [7] x:\dir\subdir\Test\TestComponent.cshtml) - Html - ;\n    
+                CSharpCode - (219:9,8 [3] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (219:9,8 [3] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n}
+                HtmlContent - (222:10,1 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (222:10,1 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+            CSharpCode - (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml)
+                LazyIntermediateToken - (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    [Parameter] public TItem1 Item1 { get; set; }\n    [Parameter] public List<TItem2> Items2 { get; set; }\n    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }\n
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
new file mode 100644
index 000000000000..e23ccef64ac8
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
@@ -0,0 +1,59 @@
+Source Location: (1:0,1 [38] x:\dir\subdir\Test\TestComponent.cshtml)
+|using Microsoft.AspNetCore.Components;|
+Generated Location: (276:11,0 [38] )
+|using Microsoft.AspNetCore.Components;|
+
+Source Location: (52:1,11 [6] x:\dir\subdir\Test\TestComponent.cshtml)
+|TItem1|
+Generated Location: (750:25,22 [6] )
+|TItem1|
+
+Source Location: (59:1,18 [20] x:\dir\subdir\Test\TestComponent.cshtml)
+|where TItem1 : class|
+Generated Location: (1051:37,40 [20] )
+|where TItem1 : class|
+
+Source Location: (92:2,11 [6] x:\dir\subdir\Test\TestComponent.cshtml)
+|TItem2|
+Generated Location: (1345:51,22 [6] )
+|TItem2|
+
+Source Location: (99:2,18 [21] x:\dir\subdir\Test\TestComponent.cshtml)
+|where TItem2 : struct|
+Generated Location: (1646:63,40 [21] )
+|where TItem2 : struct|
+
+Source Location: (141:5,1 [38] x:\dir\subdir\Test\TestComponent.cshtml)
+|foreach (var item2 in Items2)
+{
+    |
+Generated Location: (2229:84,1 [38] )
+|foreach (var item2 in Items2)
+{
+    |
+
+Source Location: (189:8,5 [19] x:\dir\subdir\Test\TestComponent.cshtml)
+|ChildContent(item2)|
+Generated Location: (2395:93,6 [19] )
+|ChildContent(item2)|
+
+Source Location: (219:9,8 [3] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+}|
+Generated Location: (2546:100,8 [3] )
+|
+}|
+
+Source Location: (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+|
+Generated Location: (2728:110,7 [185] )
+|
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+|
+
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
new file mode 100644
index 000000000000..ad841383def5
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.codegen.cs
@@ -0,0 +1,66 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+using Microsoft.AspNetCore.Components;
+
+#line default
+#line hidden
+#nullable disable
+    public partial class TestComponent<TItem1, TItem2> : Microsoft.AspNetCore.Components.ComponentBase
+    where TItem1 : class
+    where TItem2 : struct
+    {
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+            __builder.AddMarkupContent(0, "<h1>Item1</h1>");
+#nullable restore
+#line 6 "x:\dir\subdir\Test\TestComponent.cshtml"
+ foreach (var item2 in Items2)
+{
+
+#line default
+#line hidden
+#nullable disable
+            __builder.OpenElement(1, "p");
+            __builder.AddContent(2, 
+#nullable restore
+#line 9 "x:\dir\subdir\Test\TestComponent.cshtml"
+     ChildContent(item2)
+
+#line default
+#line hidden
+#nullable disable
+            );
+            __builder.AddMarkupContent(3, ";\r\n    ");
+            __builder.CloseElement();
+#nullable restore
+#line 11 "x:\dir\subdir\Test\TestComponent.cshtml"
+}
+
+#line default
+#line hidden
+#nullable disable
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 12 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
new file mode 100644
index 000000000000..335b2b246d8d
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.ir.txt
@@ -0,0 +1,21 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [14] ) - System
+        UsingDirective - (18:2,1 [34] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [19] ) - System.Linq
+        UsingDirective - (73:4,1 [30] ) - System.Threading.Tasks
+        UsingDirective - (1:0,1 [40] x:\dir\subdir\Test\TestComponent.cshtml) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase -  - TItem1, TItem2
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                MarkupBlock -  - <h1>Item1</h1>
+                CSharpCode - (141:5,1 [34] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (141:5,1 [34] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - foreach (var item2 in Items2)\n{\n
+                MarkupElement - (179:7,4 [40] x:\dir\subdir\Test\TestComponent.cshtml) - p
+                    CSharpExpression - (189:8,5 [19] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (189:8,5 [19] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ChildContent(item2)
+                    HtmlContent - (208:8,24 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (208:8,24 [7] x:\dir\subdir\Test\TestComponent.cshtml) - Html - ;\n    
+                CSharpCode - (221:10,0 [3] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (221:10,0 [3] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - }\n
+            CSharpCode - (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml)
+                LazyIntermediateToken - (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    [Parameter] public TItem1 Item1 { get; set; }\n    [Parameter] public List<TItem2> Items2 { get; set; }\n    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }\n
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
new file mode 100644
index 000000000000..243bbbe5303e
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/ComponentWithConstrainedTypeParameters/TestComponent.mappings.txt
@@ -0,0 +1,29 @@
+Source Location: (141:5,1 [34] x:\dir\subdir\Test\TestComponent.cshtml)
+|foreach (var item2 in Items2)
+{
+|
+Generated Location: (832:26,1 [34] )
+|foreach (var item2 in Items2)
+{
+|
+
+Source Location: (221:10,0 [3] x:\dir\subdir\Test\TestComponent.cshtml)
+|}
+|
+Generated Location: (1327:48,0 [3] )
+|}
+|
+
+Source Location: (231:11,7 [185] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+|
+Generated Location: (1507:57,7 [185] )
+|
+    [Parameter] public TItem1 Item1 { get; set; }
+    [Parameter] public List<TItem2> Items2 { get; set; }
+    [Parameter] public RenderFragment<TItem2> ChildContent { get; set; }
+|
+
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
index b869f2663202..92dd67f994c2 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
@@ -32,7 +32,7 @@ RazorDocument - [0..21)::21 - [@{<span foo='@ @' />}]
                                                                 Transition;[@];
                                                             CSharpImplicitExpressionBody - [14..14)::0
                                                                 CSharpCodeBlock - [14..14)::0
-                                                                    CSharpExpressionLiteral - [14..14)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                                                                    CSharpExpressionLiteral - [14..14)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                                                                         Marker;[];
                                             MarkupDynamicAttributeValue - [14..16)::2 - [ @]
                                                 MarkupTextLiteral - [14..15)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
@@ -44,7 +44,7 @@ RazorDocument - [0..21)::21 - [@{<span foo='@ @' />}]
                                                                 Transition;[@];
                                                             CSharpImplicitExpressionBody - [16..16)::0
                                                                 CSharpCodeBlock - [16..16)::0
-                                                                    CSharpExpressionLiteral - [16..16)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                                                                    CSharpExpressionLiteral - [16..16)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                                                                         Marker;[];
                                         MarkupTextLiteral - [16..17)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                                             SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/HandlesQuotesAfterTransition.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/HandlesQuotesAfterTransition.stree.txt
index 585e50aec9f0..4abc1a1b9801 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/HandlesQuotesAfterTransition.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/HandlesQuotesAfterTransition.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..2)::2 - [@"]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..2)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
             DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodParsesNothingIfFirstCharacterIsNotIdentifierStartOrParenOrBrace.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodParsesNothingIfFirstCharacterIsNotIdentifierStartOrParenOrBrace.stree.txt
index 80bf05811cb9..5c2408197a86 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodParsesNothingIfFirstCharacterIsNotIdentifierStartOrParenOrBrace.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodParsesNothingIfFirstCharacterIsNotIdentifierStartOrParenOrBrace.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..4)::4 - [@!!!]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..4)::3 - [!!!] - Gen<Markup> - SpanEditHandler;Accepts:Any
             Bang;[!];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfEOFAfterTransitionInEmbeddedExpression.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfEOFAfterTransitionInEmbeddedExpression.stree.txt
index 7d98cc9690e1..be4cee4726ee 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfEOFAfterTransitionInEmbeddedExpression.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfEOFAfterTransitionInEmbeddedExpression.stree.txt
@@ -19,7 +19,7 @@ RazorDocument - [0..9)::9 - [@{LF    @]
                                     Transition;[@];
                                 CSharpImplicitExpressionBody - [9..9)::0
                                     CSharpCodeBlock - [9..9)::0
-                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K14
+                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K15
                                             Marker;[];
                         CSharpStatementLiteral - [9..9)::0 - [] - Gen<Stmt> - SpanEditHandler;Accepts:Any
                             Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfNewlineFollowsTransition.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfNewlineFollowsTransition.stree.txt
index 178b2eab31f7..d62dfa1f5755 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfNewlineFollowsTransition.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfNewlineFollowsTransition.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..3)::3 - [@LF]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..3)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
             NewLine;[LF];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfWhitespaceBetweenTransitionAndBlockStartInEmbeddedExpr.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfWhitespaceBetweenTransitionAndBlockStartInEmbeddedExpr.stree.txt
index 5dbe63612f69..dad6b39ebdbc 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfWhitespaceBetweenTransitionAndBlockStartInEmbeddedExpr.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpErrorTest/MethodProducesErrorIfWhitespaceBetweenTransitionAndBlockStartInEmbeddedExpr.stree.txt
@@ -19,7 +19,7 @@ RazorDocument - [0..17)::17 - [@{LF    @   {}LF}]
                                     Transition;[@];
                                 CSharpImplicitExpressionBody - [9..9)::0
                                     CSharpCodeBlock - [9..9)::0
-                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K14
+                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K15
                                             Marker;[];
                         CSharpStatementLiteral - [9..16)::7 - [   {}LF] - Gen<Stmt> - SpanEditHandler;Accepts:Any
                             Whitespace;[   ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfEOFOccursAfterTransition.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfEOFOccursAfterTransition.stree.txt
index 1b3a186cb62c..2d9fcfaf18dd 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfEOFOccursAfterTransition.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfEOFOccursAfterTransition.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..1)::1 - [@]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..1)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
             Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfInvalidCharacterFollowsTransition.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfInvalidCharacterFollowsTransition.stree.txt
index b5a86255d77b..f7a445e6eec6 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfInvalidCharacterFollowsTransition.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpImplicitExpressionTest/OutputsZeroLengthCodeSpanIfInvalidCharacterFollowsTransition.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..2)::2 - [@/]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..2)::1 - [/] - Gen<Markup> - SpanEditHandler;Accepts:Any
             ForwardSlash;[/];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpSpecialBlockTest/ParseBlockIgnoresSingleSlashAtStart.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpSpecialBlockTest/ParseBlockIgnoresSingleSlashAtStart.stree.txt
index f83ce55634af..cbc51176f201 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpSpecialBlockTest/ParseBlockIgnoresSingleSlashAtStart.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpSpecialBlockTest/ParseBlockIgnoresSingleSlashAtStart.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..6)::6 - [@/ foo]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..6)::5 - [/ foo] - Gen<Markup> - SpanEditHandler;Accepts:Any
             ForwardSlash;[/];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprDoesNotAcceptDotAfterAt.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprDoesNotAcceptDotAfterAt.stree.txt
index 6efc85bc1834..3e0900524c3e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprDoesNotAcceptDotAfterAt.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprDoesNotAcceptDotAfterAt.stree.txt
@@ -18,7 +18,7 @@ RazorDocument - [0..5)::5 - [@{@.}]
                                     Transition;[@];
                                 CSharpImplicitExpressionBody - [3..3)::0
                                     CSharpCodeBlock - [3..3)::0
-                                        CSharpExpressionLiteral - [3..3)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K14
+                                        CSharpExpressionLiteral - [3..3)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K15
                                             Marker;[];
                         CSharpStatementLiteral - [3..4)::1 - [.] - Gen<Stmt> - SpanEditHandler;Accepts:Any
                             Dot;[.];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.stree.txt
index a83496ddd11a..23c654a99f60 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtAcceptsSingleSpaceOrNewlineAtDesignTime.stree.txt
@@ -19,7 +19,7 @@ RazorDocument - [0..12)::12 - [@{LF    @LF}]
                                     Transition;[@];
                                 CSharpImplicitExpressionBody - [9..9)::0
                                     CSharpCodeBlock - [9..9)::0
-                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K14
+                                        CSharpExpressionLiteral - [9..9)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K15
                                             Marker;[];
                         CSharpStatementLiteral - [9..11)::2 - [LF] - Gen<Stmt> - SpanEditHandler;Accepts:Any
                             NewLine;[LF];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtOutputsZeroLengthCodeSpan.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtOutputsZeroLengthCodeSpan.stree.txt
index 7d2bc1804c70..90f7b384f599 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtOutputsZeroLengthCodeSpan.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpVerbatimBlockTest/InnerImplicitExprWithOnlySingleAtOutputsZeroLengthCodeSpan.stree.txt
@@ -18,7 +18,7 @@ RazorDocument - [0..4)::4 - [@{@}]
                                     Transition;[@];
                                 CSharpImplicitExpressionBody - [3..3)::0
                                     CSharpCodeBlock - [3..3)::0
-                                        CSharpExpressionLiteral - [3..3)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K14
+                                        CSharpExpressionLiteral - [3..3)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[ATD];K15
                                             Marker;[];
                         CSharpStatementLiteral - [3..3)::0 - [] - Gen<Stmt> - SpanEditHandler;Accepts:Any
                             Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/AcceptsSwapTokenAtEndOfFileAndOutputsZeroLengthCodeSpan.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/AcceptsSwapTokenAtEndOfFileAndOutputsZeroLengthCodeSpan.stree.txt
index 1b3a186cb62c..2d9fcfaf18dd 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/AcceptsSwapTokenAtEndOfFileAndOutputsZeroLengthCodeSpan.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/AcceptsSwapTokenAtEndOfFileAndOutputsZeroLengthCodeSpan.stree.txt
@@ -8,7 +8,7 @@ RazorDocument - [0..1)::1 - [@]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [1..1)::0
                     CSharpCodeBlock - [1..1)::0
-                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [1..1)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [1..1)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
             Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/EmitsAtSignAsMarkupIfAtEndOfFile.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/EmitsAtSignAsMarkupIfAtEndOfFile.stree.txt
index 5f52cafebab2..9fa94aea12db 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/EmitsAtSignAsMarkupIfAtEndOfFile.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/EmitsAtSignAsMarkupIfAtEndOfFile.stree.txt
@@ -9,7 +9,7 @@ RazorDocument - [0..5)::5 - [foo @]
                     Transition;[@];
                 CSharpImplicitExpressionBody - [5..5)::0
                     CSharpCodeBlock - [5..5)::0
-                        CSharpExpressionLiteral - [5..5)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                        CSharpExpressionLiteral - [5..5)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                             Marker;[];
         MarkupTextLiteral - [5..5)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
             Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
index 9c85cd9623f8..be97c431f1a8 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/HtmlDocumentTest/WithUnexpectedTransitionsInAttributeValue_Throws.stree.txt
@@ -21,7 +21,7 @@ RazorDocument - [0..18)::18 - [<span foo='@ @' />]
                                             Transition;[@];
                                         CSharpImplicitExpressionBody - [12..12)::0
                                             CSharpCodeBlock - [12..12)::0
-                                                CSharpExpressionLiteral - [12..12)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                                                CSharpExpressionLiteral - [12..12)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                                                     Marker;[];
                         MarkupDynamicAttributeValue - [12..14)::2 - [ @]
                             MarkupTextLiteral - [12..13)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
@@ -33,7 +33,7 @@ RazorDocument - [0..18)::18 - [<span foo='@ @' />]
                                             Transition;[@];
                                         CSharpImplicitExpressionBody - [14..14)::0
                                             CSharpCodeBlock - [14..14)::0
-                                                CSharpExpressionLiteral - [14..14)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
+                                                CSharpExpressionLiteral - [14..14)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15
                                                     Marker;[];
                     MarkupTextLiteral - [14..15)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.cspans.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.cspans.txt
new file mode 100644
index 000000000000..a62e3ad18de8
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.cspans.txt
@@ -0,0 +1,8 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [40] )
+Transition span at (2:1,0 [1] ) (Accepts:None) - Parent: Directive block at (2:1,0 [25] )
+MetaCode span at (3:1,1 [6] ) (Accepts:None) - Parent: Directive block at (2:1,0 [25] )
+Code span at (9:1,7 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [25] )
+Code span at (10:1,8 [10] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [25] )
+Code span at (20:1,18 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [25] )
+Code span at (21:1,19 [6] ) (Accepts:Any) - Parent: Directive block at (2:1,0 [25] )
+Markup span at (27:1,25 [13] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [40] )
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.diag.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.diag.txt
new file mode 100644
index 000000000000..e3e68f61912f
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.diag.txt
@@ -0,0 +1 @@
+(2,26): Error RZ1039: The type parameter in the generic type constraint 'TElse' does not match the type parameter 'TSomething' defined in the directive 'custom'.
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.stree.txt
new file mode 100644
index 000000000000..392682888b84
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintErrorsWhenConstraintIdentifierIsDifferent.stree.txt
@@ -0,0 +1,27 @@
+RazorDocument - [0..40)::40 - [LF@custom TSomething where TElse : class]
+    MarkupBlock - [0..40)::40
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        CSharpCodeBlock - [2..27)::25
+            RazorDirective - [2..27)::25 - Directive:{custom;SingleLine;Unrestricted} [RZ1039(27:1,25 [5] )]
+                CSharpTransition - [2..3)::1 - Gen<None> - SpanEditHandler;Accepts:None
+                    Transition;[@];
+                RazorDirectiveBody - [3..27)::24
+                    RazorMetaCode - [3..9)::6 - Gen<None> - SpanEditHandler;Accepts:None
+                        Identifier;[custom];
+                    CSharpCodeBlock - [9..27)::18
+                        CSharpStatementLiteral - [9..10)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [10..20)::10 - [TSomething] - Gen<DirectiveToken {;Member;Opt:False}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Identifier;[TSomething];
+                        CSharpStatementLiteral - [20..21)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [21..27)::6 - [where ] - Gen<Stmt> - SpanEditHandler;Accepts:Any
+                            Keyword;[where];
+                            Whitespace;[ ];
+        MarkupTextLiteral - [27..40)::13 - [TElse : class] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            Text;[TElse];
+            Whitespace;[ ];
+            Text;[:];
+            Whitespace;[ ];
+            Text;[class];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.cspans.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.cspans.txt
new file mode 100644
index 000000000000..c6f68172985d
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.cspans.txt
@@ -0,0 +1,7 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
+Transition span at (2:1,0 [1] ) (Accepts:None) - Parent: Directive block at (2:1,0 [19] )
+MetaCode span at (3:1,1 [6] ) (Accepts:None) - Parent: Directive block at (2:1,0 [19] )
+Code span at (9:1,7 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [19] )
+Code span at (10:1,8 [10] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [19] )
+Code span at (20:1,18 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [19] )
+Markup span at (21:1,19 [24] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.diag.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.diag.txt
new file mode 100644
index 000000000000..cda0afecf823
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.diag.txt
@@ -0,0 +1 @@
+(2,20): Error RZ1040: 'maybe' is not valid in this position. Valid options are 'where'
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.stree.txt
new file mode 100644
index 000000000000..b22b0e7bb8bd
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenProducesErrorWhenFirstTokenIsNotWhereKeyword.stree.txt
@@ -0,0 +1,26 @@
+RazorDocument - [0..45)::45 - [LF@custom TSomething maybe TSomething : class]
+    MarkupBlock - [0..45)::45
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        CSharpCodeBlock - [2..21)::19
+            RazorDirective - [2..21)::19 - Directive:{custom;SingleLine;Unrestricted} [RZ1040(21:1,19 [5] )]
+                CSharpTransition - [2..3)::1 - Gen<None> - SpanEditHandler;Accepts:None
+                    Transition;[@];
+                RazorDirectiveBody - [3..21)::18
+                    RazorMetaCode - [3..9)::6 - Gen<None> - SpanEditHandler;Accepts:None
+                        Identifier;[custom];
+                    CSharpCodeBlock - [9..21)::12
+                        CSharpStatementLiteral - [9..10)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [10..20)::10 - [TSomething] - Gen<DirectiveToken {;Member;Opt:False}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Identifier;[TSomething];
+                        CSharpStatementLiteral - [20..21)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+        MarkupTextLiteral - [21..45)::24 - [maybe TSomething : class] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            Text;[maybe];
+            Whitespace;[ ];
+            Text;[TSomething];
+            Whitespace;[ ];
+            Text;[:];
+            Whitespace;[ ];
+            Text;[class];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.cspans.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.cspans.txt
new file mode 100644
index 000000000000..7028f82b1f32
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.cspans.txt
@@ -0,0 +1,8 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
+Transition span at (2:1,0 [1] ) (Accepts:None) - Parent: Directive block at (2:1,0 [43] )
+MetaCode span at (3:1,1 [6] ) (Accepts:None) - Parent: Directive block at (2:1,0 [43] )
+Code span at (9:1,7 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (10:1,8 [10] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (20:1,18 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (21:1,19 [24] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [43] )
+Markup span at (45:1,43 [0] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.stree.txt
new file mode 100644
index 000000000000..21bf4bab3c62
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_GenericConstraintTokenWorksWhenAtEndOfFile.stree.txt
@@ -0,0 +1,28 @@
+RazorDocument - [0..45)::45 - [LF@custom TSomething where TSomething : class]
+    MarkupBlock - [0..45)::45
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        CSharpCodeBlock - [2..45)::43
+            RazorDirective - [2..45)::43 - Directive:{custom;SingleLine;Unrestricted}
+                CSharpTransition - [2..3)::1 - Gen<None> - SpanEditHandler;Accepts:None
+                    Transition;[@];
+                RazorDirectiveBody - [3..45)::42
+                    RazorMetaCode - [3..9)::6 - Gen<None> - SpanEditHandler;Accepts:None
+                        Identifier;[custom];
+                    CSharpCodeBlock - [9..45)::36
+                        CSharpStatementLiteral - [9..10)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [10..20)::10 - [TSomething] - Gen<DirectiveToken {;Member;Opt:False}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Identifier;[TSomething];
+                        CSharpStatementLiteral - [20..21)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [21..45)::24 - [where TSomething : class] - Gen<DirectiveToken {name;GenericTypeConstraint;Opt:True}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Keyword;[where];
+                            Whitespace;[ ];
+                            Identifier;[TSomething];
+                            Whitespace;[ ];
+                            Colon;[:];
+                            Whitespace;[ ];
+                            Keyword;[class];
+        MarkupTextLiteral - [45..45)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.cspans.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.cspans.txt
new file mode 100644
index 000000000000..8373166431f7
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.cspans.txt
@@ -0,0 +1,9 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [47] )
+Transition span at (2:1,0 [1] ) (Accepts:None) - Parent: Directive block at (2:1,0 [45] )
+MetaCode span at (3:1,1 [6] ) (Accepts:None) - Parent: Directive block at (2:1,0 [45] )
+Code span at (9:1,7 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [45] )
+Code span at (10:1,8 [10] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [45] )
+Code span at (20:1,18 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [45] )
+Code span at (21:1,19 [24] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [45] )
+Markup span at (45:1,43 [2] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [45] )
+Markup span at (47:2,0 [0] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [47] )
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.stree.txt
new file mode 100644
index 000000000000..05706a1cbef0
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_UnderstandsGenericConstraintsToken.stree.txt
@@ -0,0 +1,30 @@
+RazorDocument - [0..47)::47 - [LF@custom TSomething where TSomething : classLF]
+    MarkupBlock - [0..47)::47
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        CSharpCodeBlock - [2..47)::45
+            RazorDirective - [2..47)::45 - Directive:{custom;SingleLine;Unrestricted}
+                CSharpTransition - [2..3)::1 - Gen<None> - SpanEditHandler;Accepts:None
+                    Transition;[@];
+                RazorDirectiveBody - [3..47)::44
+                    RazorMetaCode - [3..9)::6 - Gen<None> - SpanEditHandler;Accepts:None
+                        Identifier;[custom];
+                    CSharpCodeBlock - [9..47)::38
+                        CSharpStatementLiteral - [9..10)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [10..20)::10 - [TSomething] - Gen<DirectiveToken {;Member;Opt:False}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Identifier;[TSomething];
+                        CSharpStatementLiteral - [20..21)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [21..45)::24 - [where TSomething : class] - Gen<DirectiveToken {name;GenericTypeConstraint;Opt:True}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Keyword;[where];
+                            Whitespace;[ ];
+                            Identifier;[TSomething];
+                            Whitespace;[ ];
+                            Colon;[:];
+                            Whitespace;[ ];
+                            Keyword;[class];
+                        MarkupEphemeralTextLiteral - [45..47)::2 - [LF] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            NewLine;[LF];
+        MarkupTextLiteral - [47..47)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.cspans.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.cspans.txt
new file mode 100644
index 000000000000..7028f82b1f32
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.cspans.txt
@@ -0,0 +1,8 @@
+Markup span at (0:0,0 [2] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
+Transition span at (2:1,0 [1] ) (Accepts:None) - Parent: Directive block at (2:1,0 [43] )
+MetaCode span at (3:1,1 [6] ) (Accepts:None) - Parent: Directive block at (2:1,0 [43] )
+Code span at (9:1,7 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (10:1,8 [10] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (20:1,18 [1] ) (Accepts:Whitespace) - Parent: Directive block at (2:1,0 [43] )
+Code span at (21:1,19 [24] ) (Accepts:NonWhitespace) - Parent: Directive block at (2:1,0 [43] )
+Markup span at (45:1,43 [0] ) (Accepts:Any) - Parent: Markup block at (0:0,0 [45] )
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.stree.txt
new file mode 100644
index 000000000000..21bf4bab3c62
--- /dev/null
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/RazorDirectivesTest/DirectiveDescriptor_WorksWhenAtEndOfFile.stree.txt
@@ -0,0 +1,28 @@
+RazorDocument - [0..45)::45 - [LF@custom TSomething where TSomething : class]
+    MarkupBlock - [0..45)::45
+        MarkupTextLiteral - [0..2)::2 - [LF] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            NewLine;[LF];
+        CSharpCodeBlock - [2..45)::43
+            RazorDirective - [2..45)::43 - Directive:{custom;SingleLine;Unrestricted}
+                CSharpTransition - [2..3)::1 - Gen<None> - SpanEditHandler;Accepts:None
+                    Transition;[@];
+                RazorDirectiveBody - [3..45)::42
+                    RazorMetaCode - [3..9)::6 - Gen<None> - SpanEditHandler;Accepts:None
+                        Identifier;[custom];
+                    CSharpCodeBlock - [9..45)::36
+                        CSharpStatementLiteral - [9..10)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [10..20)::10 - [TSomething] - Gen<DirectiveToken {;Member;Opt:False}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Identifier;[TSomething];
+                        CSharpStatementLiteral - [20..21)::1 - [ ] - Gen<None> - SpanEditHandler;Accepts:Whitespace
+                            Whitespace;[ ];
+                        CSharpStatementLiteral - [21..45)::24 - [where TSomething : class] - Gen<DirectiveToken {name;GenericTypeConstraint;Opt:True}> - DirectiveTokenEditHandler;Accepts:NonWhitespace
+                            Keyword;[where];
+                            Whitespace;[ ];
+                            Identifier;[TSomething];
+                            Whitespace;[ ];
+                            Colon;[:];
+                            Whitespace;[ ];
+                            Keyword;[class];
+        MarkupTextLiteral - [45..45)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
+            Marker;[];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes1.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes1.stree.txt
index 8ce5207ab419..545aa38c38e3 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes1.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes1.stree.txt
@@ -20,7 +20,7 @@ RazorDocument - [0..30)::30 - [<ul bound [item]='items'></ul>]
                     MarkupTextLiteral - [17..18)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [18..23)::5
-                        CSharpExpressionLiteral - [18..23)::5 - [items] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [18..23)::5 - [items] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[items];
                     MarkupTextLiteral - [23..24)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes2.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes2.stree.txt
index 84a9a3756385..94bcb5a0c411 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes2.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes2.stree.txt
@@ -20,7 +20,7 @@ RazorDocument - [0..32)::32 - [<ul bound [(item)]='items'></ul>]
                     MarkupTextLiteral - [19..20)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [20..25)::5
-                        CSharpExpressionLiteral - [20..25)::5 - [items] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [20..25)::5 - [items] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[items];
                     MarkupTextLiteral - [25..26)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes3.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes3.stree.txt
index 0acd0c5753a1..aebea3355912 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes3.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes3.stree.txt
@@ -18,7 +18,7 @@ RazorDocument - [0..55)::55 - [<button bound (click)='doSomething()'>Click Me</b
                     MarkupTextLiteral - [22..23)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [23..36)::13
-                        CSharpExpressionLiteral - [23..36)::13 - [doSomething()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [23..36)::13 - [doSomething()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[doSomething()];
                     MarkupTextLiteral - [36..37)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes4.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes4.stree.txt
index d2ab596a3f33..ba557ff7d3dd 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes4.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CanHandleSymbolBoundAttributes4.stree.txt
@@ -18,7 +18,7 @@ RazorDocument - [0..56)::56 - [<button bound (^click)='doSomething()'>Click Me</
                     MarkupTextLiteral - [23..24)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [24..37)::13
-                        CSharpExpressionLiteral - [24..37)::13 - [doSomething()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [24..37)::13 - [doSomething()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[doSomething()];
                     MarkupTextLiteral - [37..38)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes1.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes1.stree.txt
index 6937a24def9f..ff9b8b62b52c 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes1.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes1.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..17)::17 - [<myth bound='' />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..13)::0
-                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [13..14)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                 MarkupMiscAttributeContent - [14..15)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes10.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes10.stree.txt
index f788e585311d..039cb9f23f02 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes10.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes10.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..17)::17 - [<myth BouND='' />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..13)::0
-                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [13..14)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                 MarkupMiscAttributeContent - [14..15)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes11.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes11.stree.txt
index 6b645d8c86f9..2daeddb849c5 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes11.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes11.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..29)::29 - [<myth BOUND=''    bOUnd="" />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..13)::0
-                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [13..14)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                 MarkupTagHelperAttribute - [14..26)::12 - bOUnd - DoubleQuotes - Bound - [    bOUnd=""]
@@ -25,7 +25,7 @@ RazorDocument - [0..29)::29 - [<myth BOUND=''    bOUnd="" />]
                     MarkupTextLiteral - [24..25)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [25..25)::0
-                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [25..26)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                 MarkupMiscAttributeContent - [26..27)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes12.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes12.stree.txt
index a88f2f766b49..2631ef8045b2 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes12.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes12.stree.txt
@@ -11,7 +11,7 @@ RazorDocument - [0..32)::32 - [<myth BOUND= nAMe='john'></myth>]
                         Text;[BOUND];
                     Equals;[=];
                     MarkupTagHelperAttributeValue - [12..12)::0
-                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                 MarkupTagHelperAttribute - [12..24)::12 - nAMe - SingleQuotes - Bound - [ nAMe='john']
                     MarkupTextLiteral - [12..13)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         Whitespace;[ ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes13.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes13.stree.txt
index a481acc89833..20218dfc5f5c 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes13.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes13.stree.txt
@@ -14,7 +14,7 @@ RazorDocument - [0..28)::28 - [<myth bound='    @true  ' />]
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..24)::11
                         MarkupBlock - [13..22)::9
-                            CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[    ];
                             CSharpCodeBlock - [17..22)::5
                                 CSharpImplicitExpression - [17..22)::5
@@ -22,11 +22,11 @@ RazorDocument - [0..28)::28 - [<myth bound='    @true  ' />]
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [17..22)::5
                                         CSharpCodeBlock - [17..22)::5
-                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [18..22)::4 - [true] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [18..22)::4 - [true] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Keyword;[true];
-                        CSharpExpressionLiteral - [22..24)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [22..24)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[  ];
                     MarkupTextLiteral - [24..25)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes14.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes14.stree.txt
index b258c86d3156..5379ffe94a6e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes14.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes14.stree.txt
@@ -14,7 +14,7 @@ RazorDocument - [0..30)::30 - [<myth bound='    @(true)  ' />]
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..26)::13
                         MarkupBlock - [13..24)::11
-                            CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[    ];
                             CSharpCodeBlock - [17..24)::7
                                 CSharpImplicitExpression - [17..24)::7
@@ -22,15 +22,15 @@ RazorDocument - [0..30)::30 - [<myth bound='    @(true)  ' />]
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [17..24)::7
                                         CSharpCodeBlock - [17..24)::7
-                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [18..19)::1 - [(] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [18..19)::1 - [(] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 LeftParenthesis;[(];
-                                            CSharpExpressionLiteral - [19..23)::4 - [true] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [19..23)::4 - [true] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Keyword;[true];
-                                            CSharpExpressionLiteral - [23..24)::1 - [)] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [23..24)::1 - [)] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 RightParenthesis;[)];
-                        CSharpExpressionLiteral - [24..26)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [24..26)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[  ];
                     MarkupTextLiteral - [26..27)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes2.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes2.stree.txt
index 062be46ba292..7d0126c049b2 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes2.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes2.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..25)::25 - [<myth bound='    true' />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..21)::8
-                        CSharpExpressionLiteral - [13..21)::8 - [    true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..21)::8 - [    true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[    ];
                             Text;[true];
                     MarkupTextLiteral - [21..22)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes3.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes3.stree.txt
index e0945db0f423..47de61391d48 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes3.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes3.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..21)::21 - [<myth bound='    ' />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..17)::4
-                        CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..17)::4 - [    ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[    ];
                     MarkupTextLiteral - [17..18)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes4.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes4.stree.txt
index b1a4d9090c91..3007074fd70f 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes4.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes4.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..27)::27 - [<myth bound=''  bound="" />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..13)::0
-                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..13)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [13..14)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                 MarkupTagHelperAttribute - [14..24)::10 - bound - DoubleQuotes - Bound - [  bound=""]
@@ -25,7 +25,7 @@ RazorDocument - [0..27)::27 - [<myth bound=''  bound="" />]
                     MarkupTextLiteral - [22..23)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [23..23)::0
-                        CSharpExpressionLiteral - [23..23)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [23..23)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [23..24)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                 MarkupMiscAttributeContent - [24..25)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes5.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes5.stree.txt
index 4d4340f5e80f..ed23af2e2204 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes5.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes5.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..30)::30 - [<myth bound=' '  bound="  " />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..14)::1
-                        CSharpExpressionLiteral - [13..14)::1 - [ ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..14)::1 - [ ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                     MarkupTextLiteral - [14..15)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
@@ -26,7 +26,7 @@ RazorDocument - [0..30)::30 - [<myth bound=' '  bound="  " />]
                     MarkupTextLiteral - [23..24)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [24..26)::2
-                        CSharpExpressionLiteral - [24..26)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [24..26)::2 - [  ] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[  ];
                     MarkupTextLiteral - [26..27)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes6.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes6.stree.txt
index cc21cab40559..1bae86698e49 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes6.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes6.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..29)::29 - [<myth bound='true' bound=  />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..17)::4
-                        CSharpExpressionLiteral - [13..17)::4 - [true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..17)::4 - [true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[true];
                     MarkupTextLiteral - [17..18)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
@@ -24,7 +24,7 @@ RazorDocument - [0..29)::29 - [<myth bound='true' bound=  />]
                         Text;[bound];
                     Equals;[=];
                     MarkupTagHelperAttributeValue - [25..25)::0
-                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                 MarkupMiscAttributeContent - [25..27)::2
                     MarkupTextLiteral - [25..27)::2 - [  ] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         Whitespace;[  ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes7.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes7.stree.txt
index 52b638b1fa22..caee885cc17a 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes7.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes7.stree.txt
@@ -11,7 +11,7 @@ RazorDocument - [0..23)::23 - [<myth bound= name='' />]
                         Text;[bound];
                     Equals;[=];
                     MarkupTagHelperAttributeValue - [12..12)::0
-                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                 MarkupTagHelperAttribute - [12..20)::8 - name - SingleQuotes - Bound - [ name='']
                     MarkupTextLiteral - [12..13)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         Whitespace;[ ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes8.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes8.stree.txt
index c05ed296bd59..c3ddd1837e35 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes8.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes8.stree.txt
@@ -11,7 +11,7 @@ RazorDocument - [0..25)::25 - [<myth bound= name='  ' />]
                         Text;[bound];
                     Equals;[=];
                     MarkupTagHelperAttributeValue - [12..12)::0
-                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [12..12)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                 MarkupTagHelperAttribute - [12..22)::10 - name - SingleQuotes - Bound - [ name='  ']
                     MarkupTextLiteral - [12..13)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         Whitespace;[ ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes9.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes9.stree.txt
index a09c2c8a6d57..7a7bc5077b68 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes9.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesErrorForEmptyTagHelperBoundAttributes9.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..46)::46 - [<myth bound='true' name='john' bound= name= />]
                     MarkupTextLiteral - [12..13)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [13..17)::4
-                        CSharpExpressionLiteral - [13..17)::4 - [true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..17)::4 - [true] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[true];
                     MarkupTextLiteral - [17..18)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
@@ -37,7 +37,7 @@ RazorDocument - [0..46)::46 - [<myth bound='true' name='john' bound= name= />]
                         Text;[bound];
                     Equals;[=];
                     MarkupTagHelperAttributeValue - [37..37)::0
-                        CSharpExpressionLiteral - [37..37)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [37..37)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                 MarkupTagHelperAttribute - [37..43)::6 - name - DoubleQuotes - Bound - [ name=]
                     MarkupTextLiteral - [37..38)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         Whitespace;[ ];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes1.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes1.stree.txt
index 1afdbe7e75e9..8abcac182d1e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes1.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes1.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..19)::19 - [<person age="12" />]
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..15)::2
-                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[12];
                     MarkupTextLiteral - [15..16)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes10.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes10.stree.txt
index dbc9614a2197..483b3182137f 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes10.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes10.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..73)::73 - [<person age="12" birthday="DateTime.Now" name="@@
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..15)::2
-                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[12];
                     MarkupTextLiteral - [15..16)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
@@ -26,7 +26,7 @@ RazorDocument - [0..73)::73 - [<person age="12" birthday="DateTime.Now" name="@@
                     MarkupTextLiteral - [26..27)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [27..39)::12
-                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime.Now];
                     MarkupTextLiteral - [39..40)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes11.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes11.stree.txt
index b4d98fbb97fb..c21574e0d31e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes11.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes11.stree.txt
@@ -14,12 +14,12 @@ RazorDocument - [0..77)::77 - [<person age="@@@(11+1)" birthday="DateTime.Now" n
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..22)::9
                         MarkupBlock - [13..15)::2
-                            CSharpExpressionLiteral - [13..14)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [13..14)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Transition;[@];
-                            CSharpEphemeralTextLiteral - [14..15)::1 - [@] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpEphemeralTextLiteral - [14..15)::1 - [@] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Transition;[@];
                         MarkupBlock - [15..22)::7
-                            CSharpExpressionLiteral - [15..15)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [15..15)::0 - [] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Marker;[];
                             CSharpCodeBlock - [15..22)::7
                                 CSharpImplicitExpression - [15..22)::7
@@ -27,15 +27,15 @@ RazorDocument - [0..77)::77 - [<person age="@@@(11+1)" birthday="DateTime.Now" n
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [15..22)::7
                                         CSharpCodeBlock - [15..22)::7
-                                            CSharpExpressionLiteral - [15..16)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [15..16)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [16..17)::1 - [(] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [16..17)::1 - [(] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 LeftParenthesis;[(];
-                                            CSharpExpressionLiteral - [17..21)::4 - [11+1] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [17..21)::4 - [11+1] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 IntegerLiteral;[11];
                                                 Plus;[+];
                                                 IntegerLiteral;[1];
-                                            CSharpExpressionLiteral - [21..22)::1 - [)] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [21..22)::1 - [)] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 RightParenthesis;[)];
                     MarkupTextLiteral - [22..23)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
@@ -48,7 +48,7 @@ RazorDocument - [0..77)::77 - [<person age="@@@(11+1)" birthday="DateTime.Now" n
                     MarkupTextLiteral - [33..34)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [34..46)::12
-                        CSharpExpressionLiteral - [34..46)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [34..46)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime.Now];
                     MarkupTextLiteral - [46..47)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes2.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes2.stree.txt
index 0af2d73896de..d09b36459b5e 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes2.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes2.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..34)::34 - [<person birthday="DateTime.Now" />]
                     MarkupTextLiteral - [17..18)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [18..30)::12
-                        CSharpExpressionLiteral - [18..30)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [18..30)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime.Now];
                     MarkupTextLiteral - [30..31)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes3.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes3.stree.txt
index 517ad1d2d242..654e89a58b1d 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes3.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes3.stree.txt
@@ -20,7 +20,7 @@ RazorDocument - [0..35)::35 - [<person age="@DateTime.Now.Year" />]
                                         Transition;[@];
                                     CSharpImplicitExpressionBody - [14..31)::17
                                         CSharpCodeBlock - [14..31)::17
-                                            CSharpExpressionLiteral - [14..31)::17 - [DateTime.Now.Year] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [14..31)::17 - [DateTime.Now.Year] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[DateTime];
                                                 Dot;[.];
                                                 Identifier;[Now];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes4.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes4.stree.txt
index 5322ea7a7e57..3e19db33863b 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes4.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes4.stree.txt
@@ -14,7 +14,7 @@ RazorDocument - [0..36)::36 - [<person age=" @DateTime.Now.Year" />]
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..32)::19
                         MarkupBlock - [13..32)::19
-                            CSharpExpressionLiteral - [13..14)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [13..14)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[ ];
                             CSharpCodeBlock - [14..32)::18
                                 CSharpImplicitExpression - [14..32)::18
@@ -22,9 +22,9 @@ RazorDocument - [0..36)::36 - [<person age=" @DateTime.Now.Year" />]
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [14..32)::18
                                         CSharpCodeBlock - [14..32)::18
-                                            CSharpExpressionLiteral - [14..15)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [14..15)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [15..32)::17 - [DateTime.Now.Year] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [15..32)::17 - [DateTime.Now.Year] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[DateTime];
                                                 Dot;[.];
                                                 Identifier;[Now];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes7.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes7.stree.txt
index 9d01bdafaaa1..9f68923abe17 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes7.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes7.stree.txt
@@ -13,13 +13,13 @@ RazorDocument - [0..88)::88 - [<person age="1 + @value + 2" birthday='(bool)@Bag
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..27)::14
-                        CSharpExpressionLiteral - [13..14)::1 - [1] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..14)::1 - [1] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[1];
-                        CSharpExpressionLiteral - [14..16)::2 - [ +] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [14..16)::2 - [ +] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                             Text;[+];
                         MarkupBlock - [16..23)::7
-                            CSharpExpressionLiteral - [16..17)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [16..17)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[ ];
                             CSharpCodeBlock - [17..23)::6
                                 CSharpImplicitExpression - [17..23)::6
@@ -27,14 +27,14 @@ RazorDocument - [0..88)::88 - [<person age="1 + @value + 2" birthday='(bool)@Bag
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [17..23)::6
                                         CSharpCodeBlock - [17..23)::6
-                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [17..18)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [18..23)::5 - [value] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [18..23)::5 - [value] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[value];
-                        CSharpExpressionLiteral - [23..25)::2 - [ +] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [23..25)::2 - [ +] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                             Text;[+];
-                        CSharpExpressionLiteral - [25..27)::2 - [ 2] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [25..27)::2 - [ 2] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                             Text;[2];
                     MarkupTextLiteral - [27..28)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
@@ -48,7 +48,7 @@ RazorDocument - [0..88)::88 - [<person age="1 + @value + 2" birthday='(bool)@Bag
                     MarkupTextLiteral - [38..39)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [39..85)::46
-                        CSharpExpressionLiteral - [39..45)::6 - [(bool)] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [39..45)::6 - [(bool)] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[(bool)];
                         MarkupBlock - [45..56)::11
                             CSharpCodeBlock - [45..56)::11
@@ -57,29 +57,29 @@ RazorDocument - [0..88)::88 - [<person age="1 + @value + 2" birthday='(bool)@Bag
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [45..56)::11
                                         CSharpCodeBlock - [45..56)::11
-                                            CSharpExpressionLiteral - [45..46)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [45..46)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [46..56)::10 - [Bag["val"]] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [46..56)::10 - [Bag["val"]] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[Bag];
                                                 LeftBracket;[[];
                                                 StringLiteral;["val"];
                                                 RightBracket;[]];
-                        CSharpExpressionLiteral - [56..58)::2 - [ ?] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [56..58)::2 - [ ?] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                             QuestionMark;[?];
                         MarkupBlock - [58..61)::3
-                            CSharpExpressionLiteral - [58..60)::2 - [ @] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [58..60)::2 - [ @] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[ ];
                                 Transition;[@];
-                            CSharpEphemeralTextLiteral - [60..61)::1 - [@] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpEphemeralTextLiteral - [60..61)::1 - [@] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Transition;[@];
-                        CSharpExpressionLiteral - [61..69)::8 - [DateTime] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [61..69)::8 - [DateTime] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime];
-                        CSharpExpressionLiteral - [69..71)::2 - [ :] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [69..71)::2 - [ :] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Whitespace;[ ];
                             Text;[:];
                         MarkupBlock - [71..85)::14
-                            CSharpExpressionLiteral - [71..72)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                            CSharpExpressionLiteral - [71..72)::1 - [ ] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                 Whitespace;[ ];
                             CSharpCodeBlock - [72..85)::13
                                 CSharpImplicitExpression - [72..85)::13
@@ -87,9 +87,9 @@ RazorDocument - [0..88)::88 - [<person age="1 + @value + 2" birthday='(bool)@Bag
                                         Transition;[<Missing>];
                                     CSharpImplicitExpressionBody - [72..85)::13
                                         CSharpCodeBlock - [72..85)::13
-                                            CSharpExpressionLiteral - [72..73)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [72..73)::1 - [@] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Transition;[@];
-                                            CSharpExpressionLiteral - [73..85)::12 - [DateTime.Now] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [73..85)::12 - [DateTime.Now] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[DateTime];
                                                 Dot;[.];
                                                 Identifier;[Now];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes8.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes8.stree.txt
index 9f5cd21e9dc6..b6ab5044ed39 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes8.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes8.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..70)::70 - [<person age="12" birthday="DateTime.Now" name="Ti
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..15)::2
-                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[12];
                     MarkupTextLiteral - [15..16)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
@@ -26,7 +26,7 @@ RazorDocument - [0..70)::70 - [<person age="12" birthday="DateTime.Now" name="Ti
                     MarkupTextLiteral - [26..27)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [27..39)::12
-                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime.Now];
                     MarkupTextLiteral - [39..40)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes9.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes9.stree.txt
index 5bbee2317048..378e800ce345 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes9.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/CreatesMarkupCodeSpansForNonStringTagHelperAttributes9.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..73)::73 - [<person age="12" birthday="DateTime.Now" name="Ti
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..15)::2
-                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..15)::2 - [12] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[12];
                     MarkupTextLiteral - [15..16)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
@@ -26,7 +26,7 @@ RazorDocument - [0..73)::73 - [<person age="12" birthday="DateTime.Now" name="Ti
                     MarkupTextLiteral - [26..27)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [27..39)::12
-                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [27..39)::12 - [DateTime.Now] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[DateTime.Now];
                     MarkupTextLiteral - [39..40)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/Rewrites_ComponentDirectiveAttributes.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/Rewrites_ComponentDirectiveAttributes.stree.txt
index 9118b9908d7a..8d9246655333 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/Rewrites_ComponentDirectiveAttributes.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/Rewrites_ComponentDirectiveAttributes.stree.txt
@@ -15,7 +15,7 @@ RazorDocument - [0..60)::60 - [<input @bind-value="Message" @bind-value:event="o
                     MarkupTextLiteral - [19..20)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [20..27)::7
-                        CSharpExpressionLiteral - [20..27)::7 - [Message] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [20..27)::7 - [Message] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[Message];
                     MarkupTextLiteral - [27..28)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block12.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block12.stree.txt
index 3635da96ebca..8ecc603ec232 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block12.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block12.stree.txt
@@ -24,7 +24,7 @@ RazorDocument - [0..32)::32 - [@{<input int-prefix-value='' />}]
                                         MarkupTextLiteral - [26..27)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                                             SingleQuote;['];
                                         MarkupTagHelperAttributeValue - [27..27)::0
-                                            CSharpExpressionLiteral - [27..27)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [27..27)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                         MarkupTextLiteral - [27..28)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                                             SingleQuote;['];
                                     MarkupMiscAttributeContent - [28..29)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block14.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block14.stree.txt
index e9db26a2d239..b229b5dc3735 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block14.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Block14.stree.txt
@@ -24,7 +24,7 @@ RazorDocument - [0..32)::32 - [@{<input int-prefix-value='3'/>}]
                                         MarkupTextLiteral - [26..27)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                                             SingleQuote;['];
                                         MarkupTagHelperAttributeValue - [27..28)::1
-                                            CSharpExpressionLiteral - [27..28)::1 - [3] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [27..28)::1 - [3] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Text;[3];
                                         MarkupTextLiteral - [28..29)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                                             SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document12.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document12.stree.txt
index 2fdaa0868a5c..265d9b624fac 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document12.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document12.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..29)::29 - [<input int-prefix-value='' />]
                     MarkupTextLiteral - [24..25)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [25..25)::0
-                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [25..25)::0 - [] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                     MarkupTextLiteral - [25..26)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                 MarkupMiscAttributeContent - [26..27)::1
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document14.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document14.stree.txt
index 11c35e9738c2..9a014eabd398 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document14.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMinimizedAttributes_Document14.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..29)::29 - [<input int-prefix-value='3'/>]
                     MarkupTextLiteral - [24..25)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
                     MarkupTagHelperAttributeValue - [25..26)::1
-                        CSharpExpressionLiteral - [25..26)::1 - [3] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [25..26)::1 - [3] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[3];
                     MarkupTextLiteral - [26..27)::1 - ['] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         SingleQuote;['];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMultipartNonStringTagHelperAttributes.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMultipartNonStringTagHelperAttributes.stree.txt
index 5a116dae22ea..4ec9f1aaa943 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMultipartNonStringTagHelperAttributes.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperBlockRewriterTest/UnderstandsMultipartNonStringTagHelperAttributes.stree.txt
@@ -13,7 +13,7 @@ RazorDocument - [0..30)::30 - [<person age="(() => 123)()" />]
                     MarkupTextLiteral - [12..13)::1 - ["] - Gen<Markup> - SpanEditHandler;Accepts:Any
                         DoubleQuote;["];
                     MarkupTagHelperAttributeValue - [13..26)::13
-                        CSharpExpressionLiteral - [13..26)::13 - [(() => 123)()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                        CSharpExpressionLiteral - [13..26)::13 - [(() => 123)()] - Gen<None> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                             Text;[(()];
                             Whitespace;[ ];
                             Equals;[=];
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperParseTreeRewriterTest/AllowsPrefixedTagHelpers11.stree.txt b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperParseTreeRewriterTest/AllowsPrefixedTagHelpers11.stree.txt
index 59b74555a0d0..6e332281a506 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperParseTreeRewriterTest/AllowsPrefixedTagHelpers11.stree.txt
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/TagHelperParseTreeRewriterTest/AllowsPrefixedTagHelpers11.stree.txt
@@ -20,7 +20,7 @@ RazorDocument - [0..34)::34 - [<th:myth2 bound="@DateTime.Now" />]
                                         Transition;[@];
                                     CSharpImplicitExpressionBody - [18..30)::12
                                         CSharpCodeBlock - [18..30)::12
-                                            CSharpExpressionLiteral - [18..30)::12 - [DateTime.Now] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K14
+                                            CSharpExpressionLiteral - [18..30)::12 - [DateTime.Now] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:AnyExceptNewline;ImplicitExpression[ATD];K15
                                                 Identifier;[DateTime];
                                                 Dot;[.];
                                                 Identifier;[Now];