Redesign tag helper codegen

src/Microsoft.AspNetCore.Mvc.Razor.Extensions/InstrumentationPass.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Globalization;
 using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
@@ -103,17 +104,16 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                     Items.Add(new InstrumentationItem(node, Parent, isLiteral: false, source: node.Source.Value));
                 }
 
-                VisitDefault(node);
-            }
-
-            public override void VisitAddTagHelperHtmlAttribute(AddTagHelperHtmlAttributeIntermediateNode node)
-            {
-                // We don't want to instrument TagHelper attributes. Do nothing.
-            }
-
-            public override void VisitSetTagHelperProperty(SetTagHelperPropertyIntermediateNode node)
-            {
-                // We don't want to instrument TagHelper attributes. Do nothing.
+                // Inside a tag helper we only want to visit inside of the body (skip all of the attributes and properties).
+                for (var i = 0; i < node.Children.Count; i++)
+                {
+                    var child = node.Children[i];
+                    if (child is TagHelperBodyIntermediateNode || 
+                        child is DefaultTagHelperBodyIntermediateNode)
+                    {
+                        VisitDefault(child);
+                    }
+                }
             }
         }
     }

src/Microsoft.AspNetCore.Mvc.Razor.Extensions/ModelExpressionPass.cs

@@ -23,11 +23,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
         {
             public List<TagHelperIntermediateNode> TagHelpers { get; } = new List<TagHelperIntermediateNode>();
 
-            public override void VisitSetTagHelperProperty(SetTagHelperPropertyIntermediateNode node)
+            public override void VisitTagHelperProperty(TagHelperPropertyIntermediateNode node)
             {
-                if (string.Equals(node.Descriptor.TypeName, ModelExpressionTypeName, StringComparison.Ordinal) ||
+                if (string.Equals(node.BoundAttribute.TypeName, ModelExpressionTypeName, StringComparison.Ordinal) ||
                     (node.IsIndexerNameMatch &&
-                     string.Equals(node.Descriptor.IndexerTypeName, ModelExpressionTypeName, StringComparison.Ordinal)))
+                     string.Equals(node.BoundAttribute.IndexerTypeName, ModelExpressionTypeName, StringComparison.Ordinal)))
                 {
                     var expression = new CSharpExpressionIntermediateNode();
 

src/Microsoft.AspNetCore.Mvc.Razor.Extensions/ViewComponentTagHelperPass.cs

@@ -1,106 +1,168 @@
 // 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;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 {
     public class ViewComponentTagHelperPass : IntermediateNodePassBase, IRazorOptimizationPass
     {
+        // Run after the default taghelper pass
+        public override int Order => IntermediateNodePassBase.DefaultFeatureOrder + 2000;
+
         private static readonly string[] PublicModifiers = new[] { "public" };
 
         protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIntermediateNode documentNode)
         {
-            var visitor = new Visitor();
-            visitor.Visit(documentNode);
-
-            if (visitor.Class == null || visitor.TagHelpers.Count == 0)
+            var @namespace = documentNode.FindPrimaryNamespace();
+            var @class = documentNode.FindPrimaryClass();
+            if (@namespace == null || @class == null)
             {
-                // Nothing to do, bail.
+                // Nothing to do, bail. We can't function without the standard structure.
                 return;
             }
 
-            foreach (var tagHelper in visitor.TagHelpers)
-            {
-                GenerateVCTHClass(visitor.Class, tagHelper.Value);
+            var context = new Context(@namespace, @class);
 
-                var tagHelperTypeName = tagHelper.Value.GetTypeName();
-                if (visitor.Fields.UsedTagHelperTypeNames.Remove(tagHelperTypeName))
+            // For each VCTH *usage* we need to rewrite the tag helper node to use the tag helper runtime to construct
+            // and set properties on the the correct field, and using the name of the type we will generate.
+            var nodes = documentNode.FindDescendantNodes<TagHelperIntermediateNode>();
+            for (var i = 0; i < nodes.Count; i++)
+            {
+                var node = nodes[i];
+                foreach (var tagHelper in node.TagHelpers)
                 {
-                    visitor.Fields.UsedTagHelperTypeNames.Add(GetVCTHFullName(visitor.Namespace, visitor.Class, tagHelper.Value));
+                    RewriteUsage(context, node, tagHelper);
                 }
             }
 
-            foreach (var (parent, node) in visitor.CreateTagHelpers)
+            // Then for each VCTH *definition* that we've seen we need to generate the class that implements
+            // ITagHelper and the field that will hold it.
+            foreach (var tagHelper in context.TagHelpers)
             {
-                RewriteCreateNode(visitor.Namespace, visitor.Class, (CreateTagHelperIntermediateNode)node, parent);
+                AddField(context, tagHelper);
+                AddTagHelperClass(context, tagHelper);
             }
         }
 
-        private void GenerateVCTHClass(ClassDeclarationIntermediateNode @class, TagHelperDescriptor tagHelper)
+        private void RewriteUsage(Context context, TagHelperIntermediateNode node, TagHelperDescriptor tagHelper)
+        {
+            if (!tagHelper.IsViewComponentKind())
+            {
+                return;
+            }
+
+            context.Add(tagHelper);
+
+            // Now we need to insert a create node using the default tag helper runtime. This is similar to
+            // code in DefaultTagHelperOptimizationPass.
+            //
+            // Find the body node.
+            var i = 0;
+            while (i < node.Children.Count && node.Children[i] is TagHelperBodyIntermediateNode)
+            {
+                i++;
+            }
+            while (i < node.Children.Count && node.Children[i] is DefaultTagHelperBodyIntermediateNode)
+            {
+                i++;
+            }
+
+            // Now find the last create node.
+            while (i < node.Children.Count && node.Children[i] is DefaultTagHelperCreateIntermediateNode)
+            {
+                i++;
+            }
+
+            // Now i has the right insertion point.
+            node.Children.Insert(i, new DefaultTagHelperCreateIntermediateNode()
+            {
+                Field = context.GetFieldName(tagHelper),
+                TagHelper = tagHelper,
+                Type = context.GetFullyQualifiedName(tagHelper),
+            });
+
+            // Now we need to rewrite any set property nodes to use the default runtime.
+            for (i = 0; i < node.Children.Count; i++)
+            {
+                if (node.Children[i] is TagHelperPropertyIntermediateNode propertyNode &&
+                    propertyNode.TagHelper == tagHelper)
+                {
+                    // This is a set property for this VCTH - we need to replace it with a node
+                    // that will use our field and property name.
+                    node.Children[i] = new DefaultTagHelperPropertyIntermediateNode(propertyNode)
+                    {
+                        Field = context.GetFieldName(tagHelper),
+                        Property = propertyNode.BoundAttribute.GetPropertyName(),
+                    };
+                }
+            }
+        }
+
+        private void AddField(Context context, TagHelperDescriptor tagHelper)
+        {
+            // We need to insert a node for the field that will hold the tag helper. We've already generated a field name
+            // at this time and use it for all uses of the same tag helper type.
+            //
+            // We also want to preserve the ordering of the nodes for testability. So insert at the end of any existing
+            // field nodes.
+            var i = 0;
+            while (i < context.Class.Children.Count && context.Class.Children[i] is DefaultTagHelperRuntimeIntermediateNode)
+            {
+                i++;
+            }
+
+            while (i < context.Class.Children.Count && context.Class.Children[i] is FieldDeclarationIntermediateNode)
+            {
+                i++;
+            }
+
+            context.Class.Children.Insert(i, new FieldDeclarationIntermediateNode()
+            {
+                Annotations =
+                {
+                    { CommonAnnotations.DefaultTagHelperExtension.TagHelperField, bool.TrueString },
+                },
+                Modifiers =
+                {
+                    "private",
+                },
+                Name = context.GetFieldName(tagHelper),
+                Type = "global::" + context.GetFullyQualifiedName(tagHelper),
+            });
+        }
+
+        private void AddTagHelperClass(Context context, TagHelperDescriptor tagHelper)
         {
             var writer = new CodeWriter();
-            WriteClass(writer, tagHelper);
+            WriteClass(context, writer, tagHelper);
 
-            var statement = new CSharpCodeIntermediateNode();
-            statement.Children.Add(new IntermediateToken()
+            var code = new CSharpCodeIntermediateNode();
+            code.Children.Add(new IntermediateToken()
             {
                 Kind = IntermediateToken.TokenKind.CSharp,
                 Content = writer.GenerateCode()
             });
 
-            @class.Children.Add(statement);
+            context.Class.Children.Add(code);
         }
 
-        private void RewriteCreateNode(
-            NamespaceDeclarationIntermediateNode @namespace,
-            ClassDeclarationIntermediateNode @class,
-            CreateTagHelperIntermediateNode node,
-            IntermediateNode parent)
-        {
-            var newTypeName = GetVCTHFullName(@namespace, @class, node.Descriptor);
-            for (var i = 0; i < parent.Children.Count; i++)
-            {
-                if (parent.Children[i] is SetTagHelperPropertyIntermediateNode setProperty &&
-                    node.Descriptor.BoundAttributes.Contains(setProperty.Descriptor))
-                {
-                    setProperty.TagHelperTypeName = newTypeName;
-                }
-            }
-
-            node.TagHelperTypeName = newTypeName;
-        }
-
-        private static string GetVCTHFullName(
-            NamespaceDeclarationIntermediateNode @namespace,
-            ClassDeclarationIntermediateNode @class,
-            TagHelperDescriptor tagHelper)
-        {
-            var vcName = tagHelper.GetViewComponentName();
-            return $"{@namespace.Content}.{@class.Name}.__Generated__{vcName}ViewComponentTagHelper";
-        }
-
-        private static string GetVCTHClassName(
-            TagHelperDescriptor tagHelper)
-        {
-            var vcName = tagHelper.GetViewComponentName();
-            return $"__Generated__{vcName}ViewComponentTagHelper";
-        }
-
-        private void WriteClass(CodeWriter writer, TagHelperDescriptor descriptor)
+        private void WriteClass(Context context, CodeWriter writer, TagHelperDescriptor tagHelper)
         {
             // Add target element.
-            BuildTargetElementString(writer, descriptor);
+            BuildTargetElementString(writer, tagHelper);
 
             // Initialize declaration.
             var tagHelperTypeName = "Microsoft.AspNetCore.Razor.TagHelpers.TagHelper";
-            var className = GetVCTHClassName(descriptor);
+            var className = context.GetClassName(tagHelper);
 
             using (writer.BuildClassDeclaration(PublicModifiers, className, tagHelperTypeName, interfaces: null))
             {
@@ -114,10 +176,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                 BuildConstructorString(writer, className);
 
                 // Add attributes.
-                BuildAttributeDeclarations(writer, descriptor);
+                BuildAttributeDeclarations(writer, tagHelper);
 
                 // Add process method.
-                BuildProcessMethodString(writer, descriptor);
+                BuildProcessMethodString(writer, tagHelper);
             }
         }
 
@@ -136,7 +198,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             }
         }
 
-        private void BuildAttributeDeclarations(CodeWriter writer, TagHelperDescriptor descriptor)
+        private void BuildAttributeDeclarations(CodeWriter writer, TagHelperDescriptor tagHelper)
         {
             writer.Write("[")
               .Write("Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeNotBoundAttribute")
@@ -149,7 +211,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                 $"global::Microsoft.AspNetCore.Mvc.Rendering.ViewContext",
                 "ViewContext");
 
-            foreach (var attribute in descriptor.BoundAttributes)
+            foreach (var attribute in tagHelper.BoundAttributes)
             {
                 writer.WriteAutoPropertyDeclaration(
                     PublicModifiers,
@@ -165,7 +227,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             }
         }
 
-        private void BuildProcessMethodString(CodeWriter writer, TagHelperDescriptor descriptor)
+        private void BuildProcessMethodString(CodeWriter writer, TagHelperDescriptor tagHelper)
         {
             var contextVariable = "context";
             var outputVariable = "output";
@@ -185,7 +247,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                     "Contextualize",
                     new[] { "ViewContext" });
 
-                var methodParameters = GetMethodParameters(descriptor);
+                var methodParameters = GetMethodParameters(tagHelper);
                 var contentVariable = "content";
                 writer.Write("var ")
                     .WriteStartAssignment(contentVariable)
@@ -199,22 +261,21 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             }
         }
 
-        private string[] GetMethodParameters(TagHelperDescriptor descriptor)
+        private string[] GetMethodParameters(TagHelperDescriptor tagHelper)
         {
-            var propertyNames = descriptor.BoundAttributes.Select(attribute => attribute.GetPropertyName());
+            var propertyNames = tagHelper.BoundAttributes.Select(attribute => attribute.GetPropertyName());
             var joinedPropertyNames = string.Join(", ", propertyNames);
             var parametersString = $"new {{ { joinedPropertyNames } }}";
-
-            var viewComponentName = descriptor.GetViewComponentName();
+            var viewComponentName = tagHelper.GetViewComponentName();
             var methodParameters = new[] { $"\"{viewComponentName}\"", parametersString };
             return methodParameters;
         }
 
-        private void BuildTargetElementString(CodeWriter writer, TagHelperDescriptor descriptor)
+        private void BuildTargetElementString(CodeWriter writer, TagHelperDescriptor tagHelper)
         {
-            Debug.Assert(descriptor.TagMatchingRules.Count() == 1);
+            Debug.Assert(tagHelper.TagMatchingRules.Count() == 1);
 
-            var rule = descriptor.TagMatchingRules.First();
+            var rule = tagHelper.TagMatchingRules.First();
 
             writer.Write("[")
                 .WriteStartMethodInvocation("Microsoft.AspNetCore.Razor.TagHelpers.HtmlTargetElementAttribute")
@@ -222,59 +283,59 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                 .WriteLine(")]");
         }
 
-        private class Visitor : IntermediateNodeWalker
+        private struct Context
         {
-            public ClassDeclarationIntermediateNode Class { get; private set; }
+            private Dictionary<TagHelperDescriptor, (string className, string fullyQualifiedName, string fieldName)> _tagHelpers;
 
-            public DeclareTagHelperFieldsIntermediateNode Fields { get; private set; }
-
-            public NamespaceDeclarationIntermediateNode Namespace { get; private set; }
-
-            public List<IntermediateNodeReference> CreateTagHelpers { get; } = new List<IntermediateNodeReference>();
-
-            public Dictionary<string, TagHelperDescriptor> TagHelpers { get; } = new Dictionary<string, TagHelperDescriptor>();
-
-            public override void VisitCreateTagHelper(CreateTagHelperIntermediateNode node)
+            public Context(NamespaceDeclarationIntermediateNode @namespace, ClassDeclarationIntermediateNode @class)
             {
-                var tagHelper = node.Descriptor;
-                if (tagHelper.IsViewComponentKind())
-                {
-                    // Capture all the VCTagHelpers (unique by type name) so we can generate a class for each one.
-                    var vcName = tagHelper.GetViewComponentName();
-                    TagHelpers[vcName] = tagHelper;
+                Namespace = @namespace;
+                Class = @class;
 
-                    CreateTagHelpers.Add(new IntermediateNodeReference(Parent, node));
-                }
+                _tagHelpers = new Dictionary<TagHelperDescriptor, (string, string, string)>();
             }
 
-            public override void VisitNamespaceDeclaration(NamespaceDeclarationIntermediateNode node)
+            public ClassDeclarationIntermediateNode Class { get; }
+
+            public NamespaceDeclarationIntermediateNode Namespace { get; }
+
+
+            public IEnumerable<TagHelperDescriptor> TagHelpers => _tagHelpers.Keys;
+
+            public bool Add(TagHelperDescriptor tagHelper)
             {
-                if (Namespace == null)
+                if (_tagHelpers.ContainsKey(tagHelper))
                 {
-                    Namespace = node;
+                    return false;
                 }
 
-                base.VisitNamespaceDeclaration(node);
+                var className = $"__Generated__{tagHelper.GetViewComponentName()}ViewComponentTagHelper";
+                var fullyQualifiedName = $"{Namespace.Content}.{Class.Name}.{className}";
+                var fieldName = GenerateFieldName(tagHelper);
+
+                _tagHelpers.Add(tagHelper, (className, fullyQualifiedName, fieldName));
+
+                return true;
             }
 
-            public override void VisitClassDeclaration(ClassDeclarationIntermediateNode node)
+            public string GetClassName(TagHelperDescriptor taghelper)
             {
-                if (Class == null)
-                {
-                    Class = node;
-                }
-
-                base.VisitClassDeclaration(node);
+                return _tagHelpers[taghelper].className;
             }
 
-            public override void VisitDeclareTagHelperFields(DeclareTagHelperFieldsIntermediateNode node)
+            public string GetFullyQualifiedName(TagHelperDescriptor taghelper)
             {
-                if (Fields == null)
-                {
-                    Fields = node;
-                }
+                return _tagHelpers[taghelper].fullyQualifiedName;
+            }
 
-                base.VisitDeclareTagHelperFields(node);
+            public string GetFieldName(TagHelperDescriptor taghelper)
+            {
+                return _tagHelpers[taghelper].fieldName;
+            }
+
+            private static string GenerateFieldName(TagHelperDescriptor tagHelper)
+            {
+                return $"__{tagHelper.GetViewComponentName()}ViewComponentTagHelper";
             }
         }
     }

src/Microsoft.AspNetCore.Razor.Language/BoundAttributeDescriptorExtensions.cs

@@ -7,16 +7,25 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     public static class BoundAttributeDescriptorExtensions
     {
-        public static string GetPropertyName(this BoundAttributeDescriptor descriptor)
+        public static string GetPropertyName(this BoundAttributeDescriptor attribute)
         {
-            descriptor.Metadata.TryGetValue(TagHelperMetadata.Common.PropertyName, out var propertyName);
+            if (attribute == null)
+            {
+                throw new ArgumentNullException(nameof(attribute));
+            }
 
+            attribute.Metadata.TryGetValue(TagHelperMetadata.Common.PropertyName, out var propertyName);
             return propertyName;
         }
 
-        public static bool IsDefaultKind(this BoundAttributeDescriptor descriptor)
+        public static bool IsDefaultKind(this BoundAttributeDescriptor attribute)
         {
-            return string.Equals(descriptor.Kind, TagHelperConventions.DefaultKind, StringComparison.Ordinal);
+            if (attribute == null)
+            {
+                throw new ArgumentNullException(nameof(attribute));
+            }
+
+            return string.Equals(attribute.Kind, TagHelperConventions.DefaultKind, StringComparison.Ordinal);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/CodeWriter.cs

@@ -582,15 +582,15 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
             return new CSharpCodeWritingScope(this);
         }
 
-        public IDisposable BuildLinePragma(SourceSpan documentLocation)
+        public IDisposable BuildLinePragma(SourceSpan? span)
         {
-            if (string.IsNullOrEmpty(documentLocation.FilePath))
+            if (string.IsNullOrEmpty(span?.FilePath))
             {
                 // Can't build a valid line pragma without a file path.
                 return NullDisposable.Default;
             }
 
-            return new LinePragmaWriter(this, documentLocation);
+            return new LinePragmaWriter(this, span.Value);
         }
 
         private void WriteVerbatimStringLiteral(string literal)

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/DefaultDocumentWriter.cs

@@ -203,11 +203,6 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
                 Context.NodeWriter.WriteHtmlContent(Context, node);
             }
 
-            public override void VisitDeclareTagHelperFields(DeclareTagHelperFieldsIntermediateNode node)
-            {
-                Context.TagHelperWriter.WriteDeclareTagHelperFields(Context, node);
-            }
-
             public override void VisitTagHelper(TagHelperIntermediateNode node)
             {
                 var tagHelperRenderingContext = new TagHelperRenderingContext()
@@ -218,30 +213,10 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
 
                 using (Context.Push(tagHelperRenderingContext))
                 {
-                    Context.TagHelperWriter.WriteTagHelper(Context, node);
+                    RenderChildren(node);
                 }
             }
 
-            public override void VisitTagHelperBody(TagHelperBodyIntermediateNode node)
-            {
-                Context.TagHelperWriter.WriteTagHelperBody(Context, node);
-            }
-
-            public override void VisitCreateTagHelper(CreateTagHelperIntermediateNode node)
-            {
-                Context.TagHelperWriter.WriteCreateTagHelper(Context, node);
-            }
-
-            public override void VisitAddTagHelperHtmlAttribute(AddTagHelperHtmlAttributeIntermediateNode node)
-            {
-                Context.TagHelperWriter.WriteAddTagHelperHtmlAttribute(Context, node);
-            }
-
-            public override void VisitSetTagHelperProperty(SetTagHelperPropertyIntermediateNode node)
-            {
-                Context.TagHelperWriter.WriteSetTagHelperProperty(Context, node);
-            }
-
             public override void VisitDefault(IntermediateNode node)
             {
                 Context.RenderChildren(node);

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/DesignTimeTagHelperWriter.cs

@@ -12,209 +12,5 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
 {
     internal class DesignTimeTagHelperWriter : TagHelperWriter
     {
-        public string CreateTagHelperMethodName { get; set; } = "CreateTagHelper";
-
-        public override void WriteDeclareTagHelperFields(CodeRenderingContext context, DeclareTagHelperFieldsIntermediateNode node)
-        {
-            foreach (var tagHelperTypeName in node.UsedTagHelperTypeNames)
-            {
-                var tagHelperVariableName = GetTagHelperVariableName(tagHelperTypeName);
-                context.CodeWriter
-                    .Write("private global::")
-                    .WriteVariableDeclaration(
-                        tagHelperTypeName,
-                        tagHelperVariableName,
-                        value: null);
-            }
-        }
-
-        public override void WriteTagHelper(CodeRenderingContext context, TagHelperIntermediateNode node)
-        {
-            context.RenderChildren(node);
-        }
-
-        public override void WriteTagHelperBody(CodeRenderingContext context, TagHelperBodyIntermediateNode node)
-        {
-            context.RenderChildren(node);
-        }
-
-        public override void WriteCreateTagHelper(CodeRenderingContext context, CreateTagHelperIntermediateNode node)
-        {
-            var tagHelperVariableName = GetTagHelperVariableName(node.TagHelperTypeName);
-
-            context.CodeWriter
-                .WriteStartAssignment(tagHelperVariableName)
-                .Write(CreateTagHelperMethodName)
-                .WriteLine($"<global::{node.TagHelperTypeName}>();");
-        }
-
-        public override void WriteAddTagHelperHtmlAttribute(CodeRenderingContext context, AddTagHelperHtmlAttributeIntermediateNode node)
-        {
-            context.RenderChildren(node);
-        }
-
-        public override void WriteSetTagHelperProperty(CodeRenderingContext context, SetTagHelperPropertyIntermediateNode node)
-        {
-            var tagHelperVariableName = GetTagHelperVariableName(node.TagHelperTypeName);
-            var tagHelperRenderingContext = context.TagHelperRenderingContext;
-            var propertyValueAccessor = GetTagHelperPropertyAccessor(node.IsIndexerNameMatch, tagHelperVariableName, node.AttributeName, node.Descriptor);
-
-            if (tagHelperRenderingContext.RenderedBoundAttributes.TryGetValue(node.AttributeName, out string previousValueAccessor))
-            {
-                context.CodeWriter
-                    .WriteStartAssignment(propertyValueAccessor)
-                    .Write(previousValueAccessor)
-                    .WriteLine(";");
-
-                return;
-            }
-            else
-            {
-                tagHelperRenderingContext.RenderedBoundAttributes[node.AttributeName] = propertyValueAccessor;
-            }
-
-            if (node.Descriptor.IsStringProperty || (node.IsIndexerNameMatch && node.Descriptor.IsIndexerStringProperty))
-            {
-                context.RenderChildren(node);
-
-                context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
-                if (node.Children.Count == 1 && node.Children.First() is HtmlContentIntermediateNode htmlNode)
-                {
-                    var content = GetContent(htmlNode);
-                    context.CodeWriter.WriteStringLiteral(content);
-                }
-                else
-                {
-                    context.CodeWriter.Write("string.Empty");
-                }
-                context.CodeWriter.WriteLine(";");
-            }
-            else
-            {
-                var firstMappedChild = node.Children.FirstOrDefault(child => child.Source != null) as IntermediateNode;
-                var valueStart = firstMappedChild?.Source;
-
-                using (context.CodeWriter.BuildLinePragma(node.Source.Value))
-                {
-                    var assignmentPrefixLength = propertyValueAccessor.Length + " = ".Length;
-                    if (node.Descriptor.IsEnum &&
-                        node.Children.Count == 1 &&
-                        node.Children.First() is IntermediateToken token &&
-                        token.IsCSharp)
-                    {
-                        assignmentPrefixLength += $"global::{node.Descriptor.TypeName}.".Length;
-
-                        if (valueStart != null)
-                        {
-                            context.CodeWriter.WritePadding(assignmentPrefixLength, node.Source.Value, context);
-                        }
-
-                        context.CodeWriter
-                            .WriteStartAssignment(propertyValueAccessor)
-                            .Write("global::")
-                            .Write(node.Descriptor.TypeName)
-                            .Write(".");
-                    }
-                    else
-                    {
-                        if (valueStart != null)
-                        {
-                            context.CodeWriter.WritePadding(assignmentPrefixLength, node.Source.Value, context);
-                        }
-
-                        context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
-                    }
-
-                    RenderTagHelperAttributeInline(context, node, node.Source.Value);
-
-                    context.CodeWriter.WriteLine(";");
-                }
-            }
-        }
-
-        private void RenderTagHelperAttributeInline(
-            CodeRenderingContext context,
-            SetTagHelperPropertyIntermediateNode property,
-            SourceSpan documentLocation)
-        {
-            for (var i = 0; i < property.Children.Count; i++)
-            {
-                RenderTagHelperAttributeInline(context, property, property.Children[i], documentLocation);
-            }
-        }
-
-        private void RenderTagHelperAttributeInline(
-            CodeRenderingContext context,
-            SetTagHelperPropertyIntermediateNode property,
-            IntermediateNode node,
-            SourceSpan documentLocation)
-        {
-            if (node is CSharpExpressionIntermediateNode || node is HtmlContentIntermediateNode)
-            {
-                for (var i = 0; i < node.Children.Count; i++)
-                {
-                    RenderTagHelperAttributeInline(context, property, node.Children[i], documentLocation);
-                }
-            }
-            else if (node is IntermediateToken token)
-            {
-                if (node.Source != null)
-                {
-                    context.AddLineMappingFor(node);
-                }
-
-                context.CodeWriter.Write(token.Content);
-            }
-            else if (node is CSharpCodeIntermediateNode)
-            {
-                var error = new RazorError(
-                    LegacyResources.TagHelpers_CodeBlocks_NotSupported_InAttributes,
-                    new SourceLocation(documentLocation.AbsoluteIndex, documentLocation.CharacterIndex, documentLocation.Length),
-                    documentLocation.Length);
-                context.Diagnostics.Add(RazorDiagnostic.Create(error));
-            }
-            else if (node is TemplateIntermediateNode)
-            {
-                var expectedTypeName = property.IsIndexerNameMatch ? property.Descriptor.IndexerTypeName : property.Descriptor.TypeName;
-                var error = new RazorError(
-                    LegacyResources.FormatTagHelpers_InlineMarkupBlocks_NotSupported_InAttributes(expectedTypeName),
-                    new SourceLocation(documentLocation.AbsoluteIndex, documentLocation.CharacterIndex, documentLocation.Length),
-                    documentLocation.Length);
-                context.Diagnostics.Add(RazorDiagnostic.Create(error));
-            }
-        }
-
-        private string GetContent(HtmlContentIntermediateNode node)
-        {
-            var builder = new StringBuilder();
-            for (var i = 0; i < node.Children.Count; i++)
-            {
-                if (node.Children[i] is IntermediateToken token && token.IsHtml)
-                {
-                    builder.Append(token.Content);
-                }
-            }
-
-            return builder.ToString();
-        }
-
-        private static string GetTagHelperVariableName(string tagHelperTypeName) => "__" + tagHelperTypeName.Replace('.', '_');
-
-        private static string GetTagHelperPropertyAccessor(
-            bool isIndexerNameMatch,
-            string tagHelperVariableName,
-            string attributeName,
-            BoundAttributeDescriptor descriptor)
-        {
-            var propertyAccessor = $"{tagHelperVariableName}.{descriptor.GetPropertyName()}";
-
-            if (isIndexerNameMatch)
-            {
-                var dictionaryKey = attributeName.Substring(descriptor.IndexerNamePrefix.Length);
-                propertyAccessor += $"[\"{dictionaryKey}\"]";
-            }
-
-            return propertyAccessor;
-        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/RuntimeNodeWriter.cs

@@ -142,7 +142,7 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
             var suffixLocation = node.Source.Value.AbsoluteIndex + node.Source.Value.Length - node.Suffix.Length;
             context.CodeWriter
                 .WriteStartMethodInvocation(BeginWriteAttributeMethod)
-                .WriteStringLiteral(node.Name)
+                .WriteStringLiteral(node.AttributeName)
                 .WriteParameterSeparator()
                 .WriteStringLiteral(node.Prefix)
                 .WriteParameterSeparator()

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/RuntimeTagHelperWriter.cs

@@ -12,484 +12,5 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
 {
     internal class RuntimeTagHelperWriter : TagHelperWriter
     {
-        public virtual string WriteTagHelperOutputMethod { get; set; } = "Write";
-
-        public string StringValueBufferVariableName { get; set; } = "__tagHelperStringValueBuffer";
-
-        public string ExecutionContextTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext";
-
-        public string ExecutionContextVariableName { get; set; } = "__tagHelperExecutionContext";
-
-        public string ExecutionContextAddMethodName { get; set; } = "Add";
-
-        public string ExecutionContextOutputPropertyName { get; set; } = "Output";
-
-        public string ExecutionContextSetOutputContentAsyncMethodName { get; set; } = "SetOutputContentAsync";
-
-        public string ExecutionContextAddHtmlAttributeMethodName { get; set; } = "AddHtmlAttribute";
-
-        public string ExecutionContextAddTagHelperAttributeMethodName { get; set; } = "AddTagHelperAttribute";
-
-        public string RunnerTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner";
-
-        public string RunnerVariableName { get; set; } = "__tagHelperRunner";
-
-        public string RunnerRunAsyncMethodName { get; set; } = "RunAsync";
-
-        public string ScopeManagerTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager";
-
-        public string ScopeManagerVariableName { get; set; } = "__tagHelperScopeManager";
-
-        public string ScopeManagerBeginMethodName { get; set; } = "Begin";
-
-        public string ScopeManagerEndMethodName { get; set; } = "End";
-
-        public string StartTagHelperWritingScopeMethodName { get; set; } = "StartTagHelperWritingScope";
-
-        public string EndTagHelperWritingScopeMethodName { get; set; } = "EndTagHelperWritingScope";
-
-        public string TagModeTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode";
-
-        public string HtmlAttributeValueStyleTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle";
-
-        public string CreateTagHelperMethodName { get; set; } = "CreateTagHelper";
-
-        public string TagHelperOutputIsContentModifiedPropertyName { get; set; } = "IsContentModified";
-
-        public string BeginAddHtmlAttributeValuesMethodName { get; set; } = "BeginAddHtmlAttributeValues";
-
-        public string EndAddHtmlAttributeValuesMethodName { get; set; } = "EndAddHtmlAttributeValues";
-
-        public string BeginWriteTagHelperAttributeMethodName { get; set; } = "BeginWriteTagHelperAttribute";
-
-        public string EndWriteTagHelperAttributeMethodName { get; set; } = "EndWriteTagHelperAttribute";
-
-        public string MarkAsHtmlEncodedMethodName { get; set; } = "Html.Raw";
-
-        public string FormatInvalidIndexerAssignmentMethodName { get; set; } = "InvalidTagHelperIndexerAssignment";
-
-        public override void WriteDeclareTagHelperFields(CodeRenderingContext context, DeclareTagHelperFieldsIntermediateNode node)
-        {
-            context.CodeWriter.WriteLine("#line hidden");
-
-            // Need to disable the warning "X is assigned to but never used." for the value buffer since
-            // whether it's used depends on how a TagHelper is used.
-            context.CodeWriter
-                .WriteLine("#pragma warning disable 0414")
-                .Write("private ")
-                .WriteVariableDeclaration("string", StringValueBufferVariableName, value: null)
-                .WriteLine("#pragma warning restore 0414");
-
-            context.CodeWriter
-            .Write("private ")
-            .WriteVariableDeclaration(
-                ExecutionContextTypeName,
-                ExecutionContextVariableName,
-                value: null);
-
-            context.CodeWriter
-            .Write("private ")
-            .Write(RunnerTypeName)
-            .Write(" ")
-            .Write(RunnerVariableName)
-            .Write(" = new ")
-            .Write(RunnerTypeName)
-            .WriteLine("();");
-
-            var backedScopeManageVariableName = "__backed" + ScopeManagerVariableName;
-            context.CodeWriter
-                .Write("private ")
-                .WriteVariableDeclaration(
-                    ScopeManagerTypeName,
-                    backedScopeManageVariableName,
-                    value: null);
-
-            context.CodeWriter
-            .Write("private ")
-            .Write(ScopeManagerTypeName)
-            .Write(" ")
-            .WriteLine(ScopeManagerVariableName);
-
-            using (context.CodeWriter.BuildScope())
-            {
-                context.CodeWriter.WriteLine("get");
-                using (context.CodeWriter.BuildScope())
-                {
-                    context.CodeWriter
-                        .Write("if (")
-                        .Write(backedScopeManageVariableName)
-                        .WriteLine(" == null)");
-
-                    using (context.CodeWriter.BuildScope())
-                    {
-                        context.CodeWriter
-                            .WriteStartAssignment(backedScopeManageVariableName)
-                            .WriteStartNewObject(ScopeManagerTypeName)
-                            .Write(StartTagHelperWritingScopeMethodName)
-                            .WriteParameterSeparator()
-                            .Write(EndTagHelperWritingScopeMethodName)
-                            .WriteEndMethodInvocation();
-                    }
-
-                    context.CodeWriter
-                        .Write("return ")
-                        .Write(backedScopeManageVariableName)
-                        .WriteLine(";");
-                }
-            }
-
-            foreach (var tagHelperTypeName in node.UsedTagHelperTypeNames)
-            {
-                var tagHelperVariableName = GetTagHelperVariableName(tagHelperTypeName);
-                context.CodeWriter
-                    .Write("private global::")
-                    .WriteVariableDeclaration(
-                        tagHelperTypeName,
-                        tagHelperVariableName,
-                        value: null);
-            }
-        }
-
-        public override void WriteTagHelper(CodeRenderingContext context, TagHelperIntermediateNode node)
-        {
-            context.RenderChildren(node);
-
-            // Execute tag helpers
-            context.CodeWriter
-                .Write("await ")
-                .WriteStartInstanceMethodInvocation(
-                    RunnerVariableName,
-                    RunnerRunAsyncMethodName)
-                .Write(ExecutionContextVariableName)
-                .WriteEndMethodInvocation();
-
-            var tagHelperOutputAccessor = $"{ExecutionContextVariableName}.{ExecutionContextOutputPropertyName}";
-
-            context.CodeWriter
-                .Write("if (!")
-                .Write(tagHelperOutputAccessor)
-                .Write(".")
-                .Write(TagHelperOutputIsContentModifiedPropertyName)
-                .WriteLine(")");
-
-            using (context.CodeWriter.BuildScope())
-            {
-                context.CodeWriter
-                    .Write("await ")
-                    .WriteInstanceMethodInvocation(
-                        ExecutionContextVariableName,
-                        ExecutionContextSetOutputContentAsyncMethodName);
-            }
-
-            context.CodeWriter
-                .WriteStartMethodInvocation(WriteTagHelperOutputMethod)
-                .Write(tagHelperOutputAccessor)
-                .WriteEndMethodInvocation()
-                .WriteStartAssignment(ExecutionContextVariableName)
-                .WriteInstanceMethodInvocation(
-                    ScopeManagerVariableName,
-                    ScopeManagerEndMethodName);
-        }
-
-        public override void WriteTagHelperBody(CodeRenderingContext context, TagHelperBodyIntermediateNode node)
-        {
-            // Call into the tag helper scope manager to start a new tag helper scope.
-            // Also capture the value as the current execution context.
-            context.CodeWriter
-                .WriteStartAssignment(ExecutionContextVariableName)
-                .WriteStartInstanceMethodInvocation(
-                    ScopeManagerVariableName,
-                    ScopeManagerBeginMethodName);
-
-            var uniqueId = context.Items[CodeRenderingContext.SuppressUniqueIds]?.ToString();
-            if (uniqueId == null)
-            {
-                uniqueId = Guid.NewGuid().ToString("N");
-            }
-
-            // Assign a unique ID for this instance of the source HTML tag. This must be unique
-            // per call site, e.g. if the tag is on the view twice, there should be two IDs.
-            context.CodeWriter.WriteStringLiteral(context.TagHelperRenderingContext.TagName)
-                .WriteParameterSeparator()
-                .Write(TagModeTypeName)
-                .Write(".")
-                .Write(context.TagHelperRenderingContext.TagMode.ToString())
-                .WriteParameterSeparator()
-                .WriteStringLiteral(uniqueId)
-                .WriteParameterSeparator();
-
-            // We remove and redirect writers so TagHelper authors can retrieve content.
-            using (context.Push(new RuntimeNodeWriter()))
-            using (context.Push(new RuntimeTagHelperWriter()))
-            {
-                using (context.CodeWriter.BuildAsyncLambda())
-                {
-                    context.RenderChildren(node);
-                }
-            }
-
-            context.CodeWriter.WriteEndMethodInvocation();
-        }
-
-        public override void WriteCreateTagHelper(CodeRenderingContext context, CreateTagHelperIntermediateNode node)
-        {
-            var tagHelperVariableName = GetTagHelperVariableName(node.TagHelperTypeName);
-
-            context.CodeWriter
-                .WriteStartAssignment(tagHelperVariableName)
-                .Write(CreateTagHelperMethodName)
-                .WriteLine($"<global::{node.TagHelperTypeName}>();");
-
-            context.CodeWriter.WriteInstanceMethodInvocation(
-                ExecutionContextVariableName,
-                ExecutionContextAddMethodName,
-                tagHelperVariableName);
-        }
-
-        public override void WriteAddTagHelperHtmlAttribute(CodeRenderingContext context, AddTagHelperHtmlAttributeIntermediateNode node)
-        {
-            var attributeValueStyleParameter = $"{HtmlAttributeValueStyleTypeName}.{node.AttributeStructure}";
-            var isConditionalAttributeValue = node.Children.Any(
-                child => child is CSharpExpressionAttributeValueIntermediateNode || child is CSharpCodeAttributeValueIntermediateNode);
-
-            // All simple text and minimized attributes will be pre-allocated.
-            if (isConditionalAttributeValue)
-            {
-                // Dynamic attribute value should be run through the conditional attribute removal system. It's
-                // unbound and contains C#.
-
-                // TagHelper attribute rendering is buffered by default. We do not want to write to the current
-                // writer.
-                var valuePieceCount = node.Children.Count(
-                    child =>
-                        child is HtmlAttributeValueIntermediateNode ||
-                        child is CSharpExpressionAttributeValueIntermediateNode ||
-                        child is CSharpCodeAttributeValueIntermediateNode ||
-                        child is ExtensionIntermediateNode);
-
-                context.CodeWriter
-                    .WriteStartMethodInvocation(BeginAddHtmlAttributeValuesMethodName)
-                    .Write(ExecutionContextVariableName)
-                    .WriteParameterSeparator()
-                    .WriteStringLiteral(node.Name)
-                    .WriteParameterSeparator()
-                    .Write(valuePieceCount.ToString(CultureInfo.InvariantCulture))
-                    .WriteParameterSeparator()
-                    .Write(attributeValueStyleParameter)
-                    .WriteEndMethodInvocation();
-
-                using (context.Push(new TagHelperHtmlAttributeRuntimeNodeWriter()))
-                {
-                    context.RenderChildren(node);
-                }
-
-                context.CodeWriter
-                    .WriteMethodInvocation(
-                        EndAddHtmlAttributeValuesMethodName,
-                        ExecutionContextVariableName);
-            }
-            else
-            {
-                // This is a data-* attribute which includes C#. Do not perform the conditional attribute removal or
-                // other special cases used when IsDynamicAttributeValue(). But the attribute must still be buffered to
-                // determine its final value.
-
-                // Attribute value is not plain text, must be buffered to determine its final value.
-                context.CodeWriter.WriteMethodInvocation(BeginWriteTagHelperAttributeMethodName);
-
-                // We're building a writing scope around the provided chunks which captures everything written from the
-                // page. Therefore, we do not want to write to any other buffer since we're using the pages buffer to
-                // ensure we capture all content that's written, directly or indirectly.
-                using (context.Push(new RuntimeNodeWriter()))
-                using (context.Push(new RuntimeTagHelperWriter()))
-                {
-                    context.RenderChildren(node);
-                }
-
-                context.CodeWriter
-                    .WriteStartAssignment(StringValueBufferVariableName)
-                    .WriteMethodInvocation(EndWriteTagHelperAttributeMethodName)
-                    .WriteStartInstanceMethodInvocation(
-                        ExecutionContextVariableName,
-                        ExecutionContextAddHtmlAttributeMethodName)
-                    .WriteStringLiteral(node.Name)
-                    .WriteParameterSeparator()
-                    .WriteStartMethodInvocation(MarkAsHtmlEncodedMethodName)
-                    .Write(StringValueBufferVariableName)
-                    .WriteEndMethodInvocation(endLine: false)
-                    .WriteParameterSeparator()
-                    .Write(attributeValueStyleParameter)
-                    .WriteEndMethodInvocation();
-            }
-        }
-
-        public override void WriteSetTagHelperProperty(CodeRenderingContext context, SetTagHelperPropertyIntermediateNode node)
-        {
-            var tagHelperVariableName = GetTagHelperVariableName(node.TagHelperTypeName);
-            var tagHelperRenderingContext = context.TagHelperRenderingContext;
-            var propertyName = node.Descriptor.GetPropertyName();
-
-            // Ensure that the property we're trying to set has initialized its dictionary bound properties.
-            if (node.IsIndexerNameMatch &&
-                tagHelperRenderingContext.VerifiedPropertyDictionaries.Add($"{node.TagHelperTypeName}.{propertyName}"))
-            {
-                // Throw a reasonable Exception at runtime if the dictionary property is null.
-                context.CodeWriter
-                    .Write("if (")
-                    .Write(tagHelperVariableName)
-                    .Write(".")
-                    .Write(propertyName)
-                    .WriteLine(" == null)");
-                using (context.CodeWriter.BuildScope())
-                {
-                    // System is in Host.NamespaceImports for all MVC scenarios. No need to generate FullName
-                    // of InvalidOperationException type.
-                    context.CodeWriter
-                        .Write("throw ")
-                        .WriteStartNewObject(nameof(InvalidOperationException))
-                        .WriteStartMethodInvocation(FormatInvalidIndexerAssignmentMethodName)
-                        .WriteStringLiteral(node.AttributeName)
-                        .WriteParameterSeparator()
-                        .WriteStringLiteral(node.TagHelperTypeName)
-                        .WriteParameterSeparator()
-                        .WriteStringLiteral(propertyName)
-                        .WriteEndMethodInvocation(endLine: false)   // End of method call
-                        .WriteEndMethodInvocation();   // End of new expression / throw statement
-                }
-            }
-
-            var propertyValueAccessor = GetTagHelperPropertyAccessor(node.IsIndexerNameMatch, tagHelperVariableName, node.AttributeName, node.Descriptor);
-
-            if (tagHelperRenderingContext.RenderedBoundAttributes.TryGetValue(node.AttributeName, out var previousValueAccessor))
-            {
-                context.CodeWriter
-                    .WriteStartAssignment(propertyValueAccessor)
-                    .Write(previousValueAccessor)
-                    .WriteLine(";");
-
-                return;
-            }
-            else
-            {
-                tagHelperRenderingContext.RenderedBoundAttributes[node.AttributeName] = propertyValueAccessor;
-            }
-
-            if (node.Descriptor.IsStringProperty || (node.IsIndexerNameMatch && node.Descriptor.IsIndexerStringProperty))
-            {
-                context.CodeWriter.WriteMethodInvocation(BeginWriteTagHelperAttributeMethodName);
-
-                using (context.Push(new LiteralRuntimeNodeWriter()))
-                {
-                    context.RenderChildren(node);
-                }
-
-                context.CodeWriter
-                    .WriteStartAssignment(StringValueBufferVariableName)
-                    .WriteMethodInvocation(EndWriteTagHelperAttributeMethodName)
-                    .WriteStartAssignment(propertyValueAccessor)
-                    .Write(StringValueBufferVariableName)
-                    .WriteLine(";");
-            }
-            else
-            {
-                using (context.CodeWriter.BuildLinePragma(node.Source.Value))
-                {
-                    context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
-
-                    if (node.Descriptor.IsEnum &&
-                        node.Children.Count == 1 &&
-                        node.Children.First() is IntermediateToken token &&
-                        token.IsCSharp)
-                    {
-                        context.CodeWriter
-                            .Write("global::")
-                            .Write(node.Descriptor.TypeName)
-                            .Write(".");
-                    }
-
-                    RenderTagHelperAttributeInline(context, node, node.Source.Value);
-
-                    context.CodeWriter.WriteLine(";");
-                }
-            }
-
-            // We need to inform the context of the attribute value.
-            context.CodeWriter
-                .WriteStartInstanceMethodInvocation(
-                    ExecutionContextVariableName,
-                    ExecutionContextAddTagHelperAttributeMethodName)
-                .WriteStringLiteral(node.AttributeName)
-                .WriteParameterSeparator()
-                .Write(propertyValueAccessor)
-                .WriteParameterSeparator()
-                .Write($"global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.{node.AttributeStructure}")
-                .WriteEndMethodInvocation();
-        }
-
-        private void RenderTagHelperAttributeInline(
-            CodeRenderingContext context,
-            SetTagHelperPropertyIntermediateNode property,
-            SourceSpan documentLocation)
-        {
-            for (var i = 0; i < property.Children.Count; i++)
-            {
-                RenderTagHelperAttributeInline(context, property, property.Children[i], documentLocation);
-            }
-        }
-
-        private void RenderTagHelperAttributeInline(
-            CodeRenderingContext context,
-            SetTagHelperPropertyIntermediateNode property,
-            IntermediateNode node,
-            SourceSpan documentLocation)
-        {
-            if (node is CSharpExpressionIntermediateNode || node is HtmlContentIntermediateNode)
-            {
-                for (var i = 0; i < node.Children.Count; i++)
-                {
-                    RenderTagHelperAttributeInline(context, property, node.Children[i], documentLocation);
-                }
-            }
-            else if (node is IntermediateToken token)
-            {
-                context.CodeWriter.Write(token.Content);
-            }
-            else if (node is CSharpCodeIntermediateNode)
-            {
-                var error = new RazorError(
-                    LegacyResources.TagHelpers_CodeBlocks_NotSupported_InAttributes,
-                    new SourceLocation(documentLocation.AbsoluteIndex, documentLocation.CharacterIndex, documentLocation.Length),
-                    documentLocation.Length);
-                context.Diagnostics.Add(RazorDiagnostic.Create(error));
-            }
-            else if (node is TemplateIntermediateNode)
-            {
-                var expectedTypeName = property.IsIndexerNameMatch ? property.Descriptor.IndexerTypeName : property.Descriptor.TypeName;
-                var error = new RazorError(
-                    LegacyResources.FormatTagHelpers_InlineMarkupBlocks_NotSupported_InAttributes(expectedTypeName),
-                    new SourceLocation(documentLocation.AbsoluteIndex, documentLocation.CharacterIndex, documentLocation.Length),
-                    documentLocation.Length);
-                context.Diagnostics.Add(RazorDiagnostic.Create(error));
-            }
-        }
-
-        protected static string GetTagHelperPropertyAccessor(
-            bool isIndexerNameMatch,
-            string tagHelperVariableName,
-            string attributeName,
-            BoundAttributeDescriptor descriptor)
-        {
-            var propertyAccessor = $"{tagHelperVariableName}.{descriptor.GetPropertyName()}";
-
-            if (isIndexerNameMatch)
-            {
-                var dictionaryKey = attributeName.Substring(descriptor.IndexerNamePrefix.Length);
-                propertyAccessor += $"[\"{dictionaryKey}\"]";
-            }
-
-            return propertyAccessor;
-        }
-
-        private static string GetTagHelperVariableName(string tagHelperTypeName) => "__" + tagHelperTypeName.Replace('.', '_');
     }
 }

src/Microsoft.AspNetCore.Razor.Language/CodeGeneration/TagHelperWriter.cs

@@ -7,16 +7,5 @@ namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
 {
     internal abstract class TagHelperWriter
     {
-        public abstract void WriteDeclareTagHelperFields(CodeRenderingContext context, DeclareTagHelperFieldsIntermediateNode node);
-
-        public abstract void WriteTagHelper(CodeRenderingContext context, TagHelperIntermediateNode node);
-
-        public abstract void WriteTagHelperBody(CodeRenderingContext context, TagHelperBodyIntermediateNode node);
-
-        public abstract void WriteCreateTagHelper(CodeRenderingContext context, CreateTagHelperIntermediateNode node);
-
-        public abstract void WriteAddTagHelperHtmlAttribute(CodeRenderingContext context, AddTagHelperHtmlAttributeIntermediateNode node);
-
-        public abstract void WriteSetTagHelperProperty(CodeRenderingContext context, SetTagHelperPropertyIntermediateNode node);
     }
 }

src/Microsoft.AspNetCore.Razor.Language/DefaultItemCollection.cs

@@ -44,6 +44,16 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public override bool IsReadOnly => false;
 
+        public override void Add(object key, object value)
+        {
+            if (key == null)
+            {
+                throw new ArgumentNullException(nameof(key));
+            }
+
+            _items.Add(key, value);
+        }
+
         public override void Add(KeyValuePair<object, object> item)
         {
             if (item.Key == null)

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorIntermediateNodeLoweringPhase.cs

@@ -362,7 +362,6 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         private class MainSourceVisitor : LoweringVisitor
         {
-            private DeclareTagHelperFieldsIntermediateNode _tagHelperFields;
             private readonly string _tagHelperPrefix;
 
             public MainSourceVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces, string tagHelperPrefix)
@@ -380,7 +379,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             {
                 _builder.Push(new HtmlAttributeIntermediateNode()
                 {
-                    Name = chunkGenerator.Name,
+                    AttributeName = chunkGenerator.Name,
                     Prefix = chunkGenerator.Prefix,
                     Suffix = chunkGenerator.Suffix,
                     Source = BuildSourceSpanFromNode(block),
@@ -619,8 +618,6 @@ namespace Microsoft.AspNetCore.Razor.Language
                     return;
                 }
 
-                DeclareTagHelperFields(tagHelperBlock);
-
                 var tagName = tagHelperBlock.TagName;
                 if (_tagHelperPrefix != null)
                 {
@@ -647,7 +644,6 @@ namespace Microsoft.AspNetCore.Razor.Language
 
                 _builder.Pop(); // Pop InitializeTagHelperStructureIntermediateNode
 
-                AddTagHelperCreation(tagHelperBlock.Binding);
                 AddTagHelperAttributes(tagHelperBlock.Attributes, tagHelperBlock.Binding);
 
                 _builder.Pop(); // Pop TagHelperIntermediateNode
@@ -675,37 +671,6 @@ namespace Microsoft.AspNetCore.Razor.Language
                 }
             }
 
-            private void DeclareTagHelperFields(TagHelperBlock block)
-            {
-                if (_tagHelperFields == null)
-                {
-                    _tagHelperFields = new DeclareTagHelperFieldsIntermediateNode();
-                    _document.Children.Add(_tagHelperFields);
-                }
-
-                foreach (var descriptor in block.Binding.Descriptors)
-                {
-                    var typeName = descriptor.GetTypeName();
-                    _tagHelperFields.UsedTagHelperTypeNames.Add(typeName);
-                }
-            }
-
-            private void AddTagHelperCreation(TagHelperBinding tagHelperBinding)
-            {
-                var descriptors = tagHelperBinding.Descriptors;
-                foreach (var descriptor in descriptors)
-                {
-                    var typeName = descriptor.GetTypeName();
-                    var createTagHelper = new CreateTagHelperIntermediateNode()
-                    {
-                        TagHelperTypeName = typeName,
-                        Descriptor = descriptor
-                    };
-
-                    _builder.Add(createTagHelper);
-                }
-            }
-
             private void AddTagHelperAttributes(IList<TagHelperAttributeNode> attributes, TagHelperBinding tagHelperBinding)
             {
                 var descriptors = tagHelperBinding.Descriptors;
@@ -727,18 +692,16 @@ namespace Microsoft.AspNetCore.Razor.Language
 
                         foreach (var associatedDescriptor in associatedDescriptors)
                         {
-                            var associatedAttributeDescriptor = associatedDescriptor.BoundAttributes.First(
-                                attributeDescriptor => TagHelperMatchingConventions.CanSatisfyBoundAttribute(attribute.Name, attributeDescriptor));
-                            var tagHelperTypeName = associatedDescriptor.GetTypeName();
-                            var attributePropertyName = associatedAttributeDescriptor.GetPropertyName();
-
-                            var setTagHelperProperty = new SetTagHelperPropertyIntermediateNode()
+                            var associatedAttributeDescriptor = associatedDescriptor.BoundAttributes.First(a =>
+                            {
+                                return TagHelperMatchingConventions.CanSatisfyBoundAttribute(attribute.Name, a);
+                            });
+
+                            var setTagHelperProperty = new TagHelperPropertyIntermediateNode()
                             {
-                                PropertyName = attributePropertyName,
                                 AttributeName = attribute.Name,
-                                TagHelperTypeName = tagHelperTypeName,
-                                Descriptor = associatedAttributeDescriptor,
-                                Binding = tagHelperBinding,
+                                BoundAttribute = associatedAttributeDescriptor,
+                                TagHelper = associatedDescriptor,
                                 AttributeStructure = attribute.AttributeStructure,
                                 Source = BuildSourceSpanFromNode(attributeValueNode),
                                 IsIndexerNameMatch = TagHelperMatchingConventions.SatisfiesBoundAttributeIndexer(attribute.Name, associatedAttributeDescriptor),
@@ -751,9 +714,9 @@ namespace Microsoft.AspNetCore.Razor.Language
                     }
                     else
                     {
-                        var addHtmlAttribute = new AddTagHelperHtmlAttributeIntermediateNode()
+                        var addHtmlAttribute = new TagHelperHtmlAttributeIntermediateNode()
                         {
-                            Name = attribute.Name,
+                            AttributeName = attribute.Name,
                             AttributeStructure = attribute.AttributeStructure
                         };
 

src/Microsoft.AspNetCore.Razor.Language/DefaultTagHelperDescriptorBuilder.cs

@@ -24,6 +24,10 @@ namespace Microsoft.AspNetCore.Razor.Language
             AssemblyName = assemblyName;
 
             _metadata = new Dictionary<string, string>(StringComparer.Ordinal);
+
+            // Tells code generation that these tag helpers are compatible with ITagHelper.
+            // For now that's all we support.
+            _metadata.Add(TagHelperMetadata.Runtime.Name, TagHelperConventions.DefaultKind);
         }
 
         public override string Name { get; }

src/Microsoft.AspNetCore.Razor.Language/DocumentClassifierPassBase.cs

@@ -139,11 +139,6 @@ namespace Microsoft.AspNetCore.Razor.Language
                 _namespace.Insert(i + 1, node);
             }
 
-            public override void VisitDeclareTagHelperFields(DeclareTagHelperFieldsIntermediateNode node)
-            {
-                _class.Insert(0, node);
-            }
-
             public override void VisitDefault(IntermediateNode node)
             {
                 if (node is MemberDeclarationIntermediateNode)

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperBodyIntermediateNode.cs

@@ -0,0 +1,70 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperBodyIntermediateNode : ExtensionIntermediateNode
+    {
+        public override IntermediateNodeCollection Children { get; } = new DefaultIntermediateNodeCollection();
+
+        public DefaultTagHelperBodyIntermediateNode()
+        {
+        }
+
+        public DefaultTagHelperBodyIntermediateNode(TagHelperBodyIntermediateNode bodyNode)
+        {
+            if (bodyNode == null)
+            {
+                throw new ArgumentNullException(nameof(bodyNode));
+            }
+
+            Source = bodyNode.Source;
+
+            for (var i = 0; i < bodyNode.Children.Count; i++)
+            {
+                Children.Add(bodyNode.Children[i]);
+            }
+
+            for (var i = 0; i < bodyNode.Diagnostics.Count; i++)
+            {
+                Diagnostics.Add(bodyNode.Diagnostics[i]);
+            }
+        }
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperBodyIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperBody(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperCreateIntermediateNode.cs

@@ -0,0 +1,52 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperCreateIntermediateNode : ExtensionIntermediateNode
+    {
+        public override IntermediateNodeCollection Children { get; } = ReadOnlyIntermediateNodeCollection.Instance;
+
+        public string Field { get; set; }
+
+        public TagHelperDescriptor TagHelper { get; set; }
+
+        public string Type { get; set; }
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperCreateIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperCreate(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperExecuteIntermediateNode.cs

@@ -0,0 +1,46 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperExecuteIntermediateNode : ExtensionIntermediateNode
+    {
+        public override IntermediateNodeCollection Children { get; } = ReadOnlyIntermediateNodeCollection.Instance;
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperExecuteIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperExecute(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperHtmlAttributeIntermediateNode.cs

@@ -0,0 +1,76 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperHtmlAttributeIntermediateNode : ExtensionIntermediateNode
+    {
+        public DefaultTagHelperHtmlAttributeIntermediateNode()
+        {
+        }
+
+        public DefaultTagHelperHtmlAttributeIntermediateNode(TagHelperHtmlAttributeIntermediateNode htmlAttributeNode)
+        {
+            if (htmlAttributeNode == null)
+            {
+                throw new ArgumentNullException(nameof(htmlAttributeNode));
+            }
+
+            AttributeName = htmlAttributeNode.AttributeName;
+            AttributeStructure = htmlAttributeNode.AttributeStructure;
+            Source = htmlAttributeNode.Source;
+
+            for (var i = 0; i < htmlAttributeNode.Children.Count; i++)
+            {
+                Children.Add(htmlAttributeNode.Children[i]);
+            }
+
+            for (var i = 0; i < htmlAttributeNode.Diagnostics.Count; i++)
+            {
+                Diagnostics.Add(htmlAttributeNode.Diagnostics[i]);
+            }
+        }
+
+        public string AttributeName { get; set; }
+
+        public AttributeStructure AttributeStructure { get; set; }
+
+        public override IntermediateNodeCollection Children { get; } = new DefaultIntermediateNodeCollection();
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperHtmlAttributeIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperHtmlAttribute(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperOptimizationPass.cs

@@ -0,0 +1,255 @@
+// 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.Collections.Generic;
+using System.Linq;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    internal class DefaultTagHelperOptimizationPass : IntermediateNodePassBase, IRazorOptimizationPass
+    {
+        // Run later than default order for user code so other passes have a chance to modify the
+        // tag helper nodes.
+        public override int Order => DefaultFeatureOrder + 1000;
+
+        protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIntermediateNode documentNode)
+        {
+            var @class = documentNode.FindPrimaryClass();
+            if (@class == null)
+            {
+                // Bail if we can't find a class node, we need to be able to create fields.
+                return;
+            }
+
+            var context = new Context(@class);
+
+            // First find all tag helper nodes that require the default tag helper runtime.
+            //
+            // This phase lowers the conceptual nodes to default runtime nodes we only care about those.
+            var tagHelperNodes = documentNode
+                .FindDescendantNodes<TagHelperIntermediateNode>()
+                .Where(IsTagHelperRuntimeNode)
+                .ToArray();
+
+            if (tagHelperNodes.Length == 0)
+            {
+                // If nothing uses the default runtime then we're done.
+                return;
+            }
+
+            AddDefaultRuntime(context);
+
+            // Each tagHelperNode should be rewritten to use the default tag helper runtime. That doesn't necessarily
+            // mean that all of these tag helpers are the default kind, just that them are compatible with ITagHelper.
+            for (var i = 0; i < tagHelperNodes.Length; i++)
+            {
+                var tagHelperNode = tagHelperNodes[i];
+
+                RewriteBody(tagHelperNode);
+                RewriteHtmlAttributes(tagHelperNode);
+                AddExecute(tagHelperNode);
+
+                // We need to find all of the 'default' kind tag helpers and rewrite their usage site to use the 
+                // extension nodes for the default tag helper runtime (ITagHelper).
+                foreach (var tagHelper in tagHelperNode.TagHelpers)
+                {
+                    RewriteUsage(context, tagHelperNode, tagHelper);
+                }
+            }
+
+            // Then for each 'default' kind tag helper we need to generate the field that will hold it.
+            foreach (var tagHelper in context.TagHelpers)
+            {
+                AddField(context, tagHelper);
+            }
+        }
+
+        private void AddDefaultRuntime(Context context)
+        {
+            // We need to insert a node for the field that will hold the tag helper. We've already generated a field name
+            // at this time and use it for all uses of the same tag helper type.
+            //
+            // We also want to preserve the ordering of the nodes for testability. So insert at the end of any existing
+            // field nodes.
+            var i = 0;
+            while (i < context.Class.Children.Count && context.Class.Children[i] is FieldDeclarationIntermediateNode)
+            {
+                i++;
+            }
+
+            context.Class.Children.Insert(i, new DefaultTagHelperRuntimeIntermediateNode());
+        }
+
+        private void RewriteBody(TagHelperIntermediateNode node)
+        {
+            for (var i = 0; i < node.Children.Count; i++)
+            {
+                if (node.Children[i] is TagHelperBodyIntermediateNode bodyNode)
+                {
+                    // We only expect one body node.
+                    node.Children[i] = new DefaultTagHelperBodyIntermediateNode(bodyNode);
+                    break;
+                }
+            }
+        }
+
+        private void AddExecute(TagHelperIntermediateNode node)
+        {
+            // Execute the tag helpers at the end, before leaving scope.
+            node.Children.Add(new DefaultTagHelperExecuteIntermediateNode());
+        }
+
+        private void RewriteHtmlAttributes(TagHelperIntermediateNode node)
+        {
+            // We need to rewrite each html attribute, so that it will get added to the execution context.
+            for (var i = 0; i < node.Children.Count; i++)
+            {
+                if (node.Children[i] is TagHelperHtmlAttributeIntermediateNode htmlAttributeNode)
+                {
+                    node.Children[i] = new DefaultTagHelperHtmlAttributeIntermediateNode(htmlAttributeNode);
+                }
+            }
+        }
+
+        private void RewriteUsage(Context context, TagHelperIntermediateNode node, TagHelperDescriptor tagHelper)
+        {
+            if (!tagHelper.IsDefaultKind())
+            {
+                return;
+            }
+
+            context.Add(tagHelper);
+
+            // First we need to insert a node for the creation of the tag helper, and the hook up to the execution
+            // context. This should come after the body node and any existing create nodes.
+            //
+            // If we're dealing with something totally malformed, then we'll end up just inserting at the end, and that's not
+            // so bad.
+            var i = 0;
+
+            // Find the body node.
+            while (i < node.Children.Count && node.Children[i] is TagHelperBodyIntermediateNode)
+            {
+                i++;
+            }
+            while (i < node.Children.Count && node.Children[i] is DefaultTagHelperBodyIntermediateNode)
+            {
+                i++;
+            }
+
+            // Now find the last create node.
+            while (i < node.Children.Count && node.Children[i] is DefaultTagHelperCreateIntermediateNode)
+            {
+                i++;
+            }
+
+            // Now i has the right insertion point.
+            node.Children.Insert(i, new DefaultTagHelperCreateIntermediateNode()
+            {
+                Field = context.GetFieldName(tagHelper),
+                TagHelper = tagHelper,
+                Type = tagHelper.GetTypeName(),
+            });
+
+            // Next we need to rewrite any property nodes to use the field and property name for this
+            // tag helper.
+            for (i = 0; i < node.Children.Count; i++)
+            {
+                if (node.Children[i] is TagHelperPropertyIntermediateNode propertyNode &&
+                    propertyNode.TagHelper == tagHelper)
+                {
+                    // This belongs to the current tag helper, replace it.
+                    node.Children[i] = new DefaultTagHelperPropertyIntermediateNode(propertyNode)
+                    {
+                        Field = context.GetFieldName(tagHelper),
+                        Property = propertyNode.BoundAttribute.GetPropertyName(),
+                    };
+                }
+            }
+        }
+
+        private void AddField(Context context, TagHelperDescriptor tagHelper)
+        {
+            // We need to insert a node for the field that will hold the tag helper. We've already generated a field name
+            // at this time and use it for all uses of the same tag helper type.
+            //
+            // We also want to preserve the ordering of the nodes for testability. So insert at the end of any existing
+            // field nodes.
+            var i = 0;
+            while (i < context.Class.Children.Count && context.Class.Children[i] is DefaultTagHelperRuntimeIntermediateNode)
+            {
+                i++;
+            }
+
+            while (i < context.Class.Children.Count && context.Class.Children[i] is FieldDeclarationIntermediateNode)
+            {
+                i++;
+            }
+
+            context.Class.Children.Insert(i, new FieldDeclarationIntermediateNode()
+            {
+                Annotations =
+                {
+                    { CommonAnnotations.DefaultTagHelperExtension.TagHelperField, bool.TrueString },
+                },
+                Modifiers =
+                {
+                    "private",
+                },
+                Name = context.GetFieldName(tagHelper),
+                Type = "global::" + tagHelper.GetTypeName(),
+            });
+        }
+
+        private bool IsTagHelperRuntimeNode(TagHelperIntermediateNode node)
+        {
+            foreach (var tagHelper in node.TagHelpers)
+            {
+                if (tagHelper.KindUsesDefaultTagHelperRuntime())
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        private struct Context
+        {
+            private readonly Dictionary<TagHelperDescriptor, string> _tagHelpers;
+
+            public Context(ClassDeclarationIntermediateNode @class)
+            {
+                Class = @class;
+
+                _tagHelpers = new Dictionary<TagHelperDescriptor, string>(TagHelperDescriptorComparer.Default);
+            }
+
+            public ClassDeclarationIntermediateNode Class { get; }
+
+            public IEnumerable<TagHelperDescriptor> TagHelpers => _tagHelpers.Keys;
+
+            public bool Add(TagHelperDescriptor tagHelper)
+            {
+                if (_tagHelpers.ContainsKey(tagHelper))
+                {
+                    return false;
+                }
+
+                _tagHelpers.Add(tagHelper, GenerateFieldName(tagHelper));
+                return true;
+            }
+
+            public string GetFieldName(TagHelperDescriptor tagHelper)
+            {
+                return _tagHelpers[tagHelper];
+            }
+
+            private static string GenerateFieldName(TagHelperDescriptor tagHelper)
+            {
+                return "__" + tagHelper.GetTypeName().Replace('.', '_');
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperPropertyIntermediateNode.cs

@@ -0,0 +1,89 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperPropertyIntermediateNode : ExtensionIntermediateNode
+    {
+        public DefaultTagHelperPropertyIntermediateNode()
+        {
+        }
+
+        public DefaultTagHelperPropertyIntermediateNode(TagHelperPropertyIntermediateNode propertyNode)
+        {
+            if (propertyNode == null)
+            {
+                throw new ArgumentNullException(nameof(propertyNode));
+            }
+
+            AttributeName = propertyNode.AttributeName;
+            AttributeStructure = propertyNode.AttributeStructure;
+            BoundAttribute = propertyNode.BoundAttribute;
+            IsIndexerNameMatch = propertyNode.IsIndexerNameMatch;
+            Source = propertyNode.Source;
+            TagHelper = propertyNode.TagHelper;
+
+            for (var i = 0; i < propertyNode.Children.Count; i++)
+            {
+                Children.Add(propertyNode.Children[i]);
+            }
+
+            for (var i = 0; i < propertyNode.Diagnostics.Count; i++)
+            {
+                Diagnostics.Add(propertyNode.Diagnostics[i]);
+            }
+        }
+
+        public override IntermediateNodeCollection Children { get; } = new DefaultIntermediateNodeCollection();
+
+        public string AttributeName { get; set; }
+
+        public AttributeStructure AttributeStructure { get; set; }
+
+        public BoundAttributeDescriptor BoundAttribute { get; set; }
+
+        public string Field { get; set; }
+
+        public bool IsIndexerNameMatch { get; set; }
+
+        public string Property { get; set; }
+
+        public TagHelperDescriptor TagHelper { get; set; }
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperPropertyIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperProperty(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperRuntimeIntermediateNode.cs

@@ -0,0 +1,46 @@
+// 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;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public sealed class DefaultTagHelperRuntimeIntermediateNode : ExtensionIntermediateNode
+    {
+        public override IntermediateNodeCollection Children { get; } = new DefaultIntermediateNodeCollection();
+
+        public override void Accept(IntermediateNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            AcceptExtensionNode<DefaultTagHelperRuntimeIntermediateNode>(this, visitor);
+        }
+
+        public override void WriteNode(CodeTarget target, CodeRenderingContext context)
+        {
+            if (target == null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var extension = target.GetExtension<IDefaultTagHelperTargetExtension>();
+            if (extension == null)
+            {
+                ReportMissingCodeTargetExtension<IDefaultTagHelperTargetExtension>(context);
+                return;
+            }
+
+            extension.WriteTagHelperRuntime(context, this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperTargetExtension.cs

@@ -0,0 +1,584 @@
+// 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;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+using Microsoft.AspNetCore.Razor.Language.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    internal sealed class DefaultTagHelperTargetExtension : IDefaultTagHelperTargetExtension
+    {
+        private static readonly string[] PrivateModifiers = new string[] { "private" };
+
+        public bool DesignTime { get; set; }
+
+        public string RunnerVariableName { get; set; } = "__tagHelperRunner";
+
+        public string StringValueBufferVariableName { get; set; } = "__tagHelperStringValueBuffer";
+
+        public string CreateTagHelperMethodName { get; set; } = "CreateTagHelper";
+
+        public string ExecutionContextTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext";
+
+        public string ExecutionContextVariableName { get; set; } = "__tagHelperExecutionContext";
+
+        public string ExecutionContextAddMethodName { get; set; } = "Add";
+
+        public string TagHelperRunnerTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner";
+
+        public string ExecutionContextOutputPropertyName { get; set; } = "Output";
+
+        public string ExecutionContextSetOutputContentAsyncMethodName { get; set; } = "SetOutputContentAsync";
+
+        public string ExecutionContextAddHtmlAttributeMethodName { get; set; } = "AddHtmlAttribute";
+
+        public string ExecutionContextAddTagHelperAttributeMethodName { get; set; } = "AddTagHelperAttribute";
+
+        public string RunnerRunAsyncMethodName { get; set; } = "RunAsync";
+
+        public string ScopeManagerTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager";
+
+        public string ScopeManagerVariableName { get; set; } = "__tagHelperScopeManager";
+
+        public string ScopeManagerBeginMethodName { get; set; } = "Begin";
+
+        public string ScopeManagerEndMethodName { get; set; } = "End";
+
+        public string StartTagHelperWritingScopeMethodName { get; set; } = "StartTagHelperWritingScope";
+
+        public string EndTagHelperWritingScopeMethodName { get; set; } = "EndTagHelperWritingScope";
+
+        public string TagModeTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode";
+
+        public string HtmlAttributeValueStyleTypeName { get; set; } = "global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle";
+
+        public string TagHelperOutputIsContentModifiedPropertyName { get; set; } = "IsContentModified";
+
+        public string BeginAddHtmlAttributeValuesMethodName { get; set; } = "BeginAddHtmlAttributeValues";
+
+        public string EndAddHtmlAttributeValuesMethodName { get; set; } = "EndAddHtmlAttributeValues";
+
+        public string BeginWriteTagHelperAttributeMethodName { get; set; } = "BeginWriteTagHelperAttribute";
+
+        public string EndWriteTagHelperAttributeMethodName { get; set; } = "EndWriteTagHelperAttribute";
+
+        public string MarkAsHtmlEncodedMethodName { get; set; } = "Html.Raw";
+
+        public string FormatInvalidIndexerAssignmentMethodName { get; set; } = "InvalidTagHelperIndexerAssignment";
+
+        public string WriteTagHelperOutputMethod { get; set; } = "Write";
+
+        public void WriteTagHelperBody(CodeRenderingContext context, DefaultTagHelperBodyIntermediateNode node)
+        {
+            if (DesignTime)
+            {
+                context.RenderChildren(node);
+            }
+            else
+            {
+                // Call into the tag helper scope manager to start a new tag helper scope.
+                // Also capture the value as the current execution context.
+                context.CodeWriter
+                    .WriteStartAssignment(ExecutionContextVariableName)
+                    .WriteStartInstanceMethodInvocation(
+                        ScopeManagerVariableName,
+                        ScopeManagerBeginMethodName);
+
+                // Assign a unique ID for this instance of the source HTML tag. This must be unique
+                // per call site, e.g. if the tag is on the view twice, there should be two IDs.
+                var uniqueId = (string)context.Items[CodeRenderingContext.SuppressUniqueIds];
+                if (uniqueId == null)
+                {
+                    uniqueId = Guid.NewGuid().ToString("N");
+                }
+
+                context.CodeWriter.WriteStringLiteral(context.TagHelperRenderingContext.TagName)
+                    .WriteParameterSeparator()
+                    .Write(TagModeTypeName)
+                    .Write(".")
+                    .Write(context.TagHelperRenderingContext.TagMode.ToString())
+                    .WriteParameterSeparator()
+                    .WriteStringLiteral(uniqueId)
+                    .WriteParameterSeparator();
+
+                // We remove and redirect writers so TagHelper authors can retrieve content.
+                using (context.Push(new RuntimeNodeWriter()))
+                using (context.Push(new RuntimeTagHelperWriter()))
+                {
+                    using (context.CodeWriter.BuildAsyncLambda())
+                    {
+                        context.RenderChildren(node);
+                    }
+                }
+
+                context.CodeWriter.WriteEndMethodInvocation();
+            }
+        }
+
+        public void WriteTagHelperCreate(CodeRenderingContext context, DefaultTagHelperCreateIntermediateNode node)
+        {
+            context.CodeWriter
+                .WriteStartAssignment(node.Field)
+                .Write(CreateTagHelperMethodName)
+                .WriteLine("<global::" + node.Type + ">();");
+
+            if (!DesignTime)
+            {
+                context.CodeWriter.WriteInstanceMethodInvocation(
+                    ExecutionContextVariableName,
+                    ExecutionContextAddMethodName,
+                    node.Field);
+            }
+        }
+
+        public void WriteTagHelperExecute(CodeRenderingContext context, DefaultTagHelperExecuteIntermediateNode node)
+        {
+            if (!DesignTime)
+            {
+                context.CodeWriter
+                    .Write("await ")
+                    .WriteStartInstanceMethodInvocation(
+                        RunnerVariableName,
+                        RunnerRunAsyncMethodName)
+                    .Write(ExecutionContextVariableName)
+                    .WriteEndMethodInvocation();
+
+                var tagHelperOutputAccessor = $"{ExecutionContextVariableName}.{ExecutionContextOutputPropertyName}";
+
+                context.CodeWriter
+                    .Write("if (!")
+                    .Write(tagHelperOutputAccessor)
+                    .Write(".")
+                    .Write(TagHelperOutputIsContentModifiedPropertyName)
+                    .WriteLine(")");
+
+                using (context.CodeWriter.BuildScope())
+                {
+                    context.CodeWriter
+                        .Write("await ")
+                        .WriteInstanceMethodInvocation(
+                            ExecutionContextVariableName,
+                            ExecutionContextSetOutputContentAsyncMethodName);
+                }
+
+                context.CodeWriter
+                    .WriteStartMethodInvocation(WriteTagHelperOutputMethod)
+                    .Write(tagHelperOutputAccessor)
+                    .WriteEndMethodInvocation()
+                    .WriteStartAssignment(ExecutionContextVariableName)
+                    .WriteInstanceMethodInvocation(
+                        ScopeManagerVariableName,
+                        ScopeManagerEndMethodName);
+            }
+        }
+
+        public void WriteTagHelperHtmlAttribute(CodeRenderingContext context, DefaultTagHelperHtmlAttributeIntermediateNode node)
+        {
+            if (DesignTime)
+            {
+                context.RenderChildren(node);
+            }
+            else
+            {
+                var attributeValueStyleParameter = $"{HtmlAttributeValueStyleTypeName}.{node.AttributeStructure}";
+                var isConditionalAttributeValue = node.Children.Any(
+                    child => child is CSharpExpressionAttributeValueIntermediateNode || child is CSharpCodeAttributeValueIntermediateNode);
+
+                // All simple text and minimized attributes will be pre-allocated.
+                if (isConditionalAttributeValue)
+                {
+                    // Dynamic attribute value should be run through the conditional attribute removal system. It's
+                    // unbound and contains C#.
+
+                    // TagHelper attribute rendering is buffered by default. We do not want to write to the current
+                    // writer.
+                    var valuePieceCount = node.Children.Count(
+                        child =>
+                            child is HtmlAttributeValueIntermediateNode ||
+                            child is CSharpExpressionAttributeValueIntermediateNode ||
+                            child is CSharpCodeAttributeValueIntermediateNode ||
+                            child is ExtensionIntermediateNode);
+
+                    context.CodeWriter
+                        .WriteStartMethodInvocation(BeginAddHtmlAttributeValuesMethodName)
+                        .Write(ExecutionContextVariableName)
+                        .WriteParameterSeparator()
+                        .WriteStringLiteral(node.AttributeName)
+                        .WriteParameterSeparator()
+                        .Write(valuePieceCount.ToString(CultureInfo.InvariantCulture))
+                        .WriteParameterSeparator()
+                        .Write(attributeValueStyleParameter)
+                        .WriteEndMethodInvocation();
+
+                    using (context.Push(new TagHelperHtmlAttributeRuntimeNodeWriter()))
+                    {
+                        context.RenderChildren(node);
+                    }
+
+                    context.CodeWriter
+                        .WriteMethodInvocation(
+                            EndAddHtmlAttributeValuesMethodName,
+                            ExecutionContextVariableName);
+                }
+                else
+                {
+                    // This is a data-* attribute which includes C#. Do not perform the conditional attribute removal or
+                    // other special cases used when IsDynamicAttributeValue(). But the attribute must still be buffered to
+                    // determine its final value.
+
+                    // Attribute value is not plain text, must be buffered to determine its final value.
+                    context.CodeWriter.WriteMethodInvocation(BeginWriteTagHelperAttributeMethodName);
+
+                    // We're building a writing scope around the provided chunks which captures everything written from the
+                    // page. Therefore, we do not want to write to any other buffer since we're using the pages buffer to
+                    // ensure we capture all content that's written, directly or indirectly.
+                    using (context.Push(new RuntimeNodeWriter()))
+                    using (context.Push(new RuntimeTagHelperWriter()))
+                    {
+                        context.RenderChildren(node);
+                    }
+
+                    context.CodeWriter
+                        .WriteStartAssignment(StringValueBufferVariableName)
+                        .WriteMethodInvocation(EndWriteTagHelperAttributeMethodName)
+                        .WriteStartInstanceMethodInvocation(
+                            ExecutionContextVariableName,
+                            ExecutionContextAddHtmlAttributeMethodName)
+                        .WriteStringLiteral(node.AttributeName)
+                        .WriteParameterSeparator()
+                        .WriteStartMethodInvocation(MarkAsHtmlEncodedMethodName)
+                        .Write(StringValueBufferVariableName)
+                        .WriteEndMethodInvocation(endLine: false)
+                        .WriteParameterSeparator()
+                        .Write(attributeValueStyleParameter)
+                        .WriteEndMethodInvocation();
+                }
+            }
+        }
+
+        public void WriteTagHelperProperty(CodeRenderingContext context, DefaultTagHelperPropertyIntermediateNode node)
+        {
+            var tagHelperRenderingContext = context.TagHelperRenderingContext;
+            var propertyName = node.BoundAttribute.GetPropertyName();
+            var propertyValueAccessor = GetTagHelperPropertyAccessor(node.IsIndexerNameMatch, node.Field, node.AttributeName, node.BoundAttribute);
+
+            if (!DesignTime)
+            {
+                // Ensure that the property we're trying to set has initialized its dictionary bound properties.
+                if (node.IsIndexerNameMatch &&
+                    tagHelperRenderingContext.VerifiedPropertyDictionaries.Add($"{node.TagHelper.GetTypeName()}.{propertyName}"))
+                {
+                    // Throw a reasonable Exception at runtime if the dictionary property is null.
+                    context.CodeWriter
+                        .Write("if (")
+                        .Write(node.Field)
+                        .Write(".")
+                        .Write(propertyName)
+                        .WriteLine(" == null)");
+                    using (context.CodeWriter.BuildScope())
+                    {
+                        // System is in Host.NamespaceImports for all MVC scenarios. No need to generate FullName
+                        // of InvalidOperationException type.
+                        context.CodeWriter
+                            .Write("throw ")
+                            .WriteStartNewObject(nameof(InvalidOperationException))
+                            .WriteStartMethodInvocation(FormatInvalidIndexerAssignmentMethodName)
+                            .WriteStringLiteral(node.AttributeName)
+                            .WriteParameterSeparator()
+                            .WriteStringLiteral(node.TagHelper.GetTypeName())
+                            .WriteParameterSeparator()
+                            .WriteStringLiteral(propertyName)
+                            .WriteEndMethodInvocation(endLine: false)   // End of method call
+                            .WriteEndMethodInvocation();   // End of new expression / throw statement
+                    }
+                }
+            }
+
+            if (tagHelperRenderingContext.RenderedBoundAttributes.TryGetValue(node.AttributeName, out var previousValueAccessor))
+            {
+                context.CodeWriter
+                    .WriteStartAssignment(propertyValueAccessor)
+                    .Write(previousValueAccessor)
+                    .WriteLine(";");
+
+                return;
+            }
+            else
+            {
+                tagHelperRenderingContext.RenderedBoundAttributes[node.AttributeName] = propertyValueAccessor;
+            }
+
+            if (node.BoundAttribute.IsStringProperty || (node.IsIndexerNameMatch && node.BoundAttribute.IsIndexerStringProperty))
+            {
+                if (DesignTime)
+                {
+                    context.RenderChildren(node);
+
+                    context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
+                    if (node.Children.Count == 1 && node.Children.First() is HtmlContentIntermediateNode htmlNode)
+                    {
+                        var content = GetContent(htmlNode);
+                        context.CodeWriter.WriteStringLiteral(content);
+                    }
+                    else
+                    {
+                        context.CodeWriter.Write("string.Empty");
+                    }
+                    context.CodeWriter.WriteLine(";");
+                }
+                else
+                {
+                    context.CodeWriter.WriteMethodInvocation(BeginWriteTagHelperAttributeMethodName);
+
+                    using (context.Push(new LiteralRuntimeNodeWriter()))
+                    {
+                        context.RenderChildren(node);
+                    }
+
+                    context.CodeWriter
+                        .WriteStartAssignment(StringValueBufferVariableName)
+                        .WriteMethodInvocation(EndWriteTagHelperAttributeMethodName)
+                        .WriteStartAssignment(propertyValueAccessor)
+                        .Write(StringValueBufferVariableName)
+                        .WriteLine(";");
+                }
+            }
+            else
+            {
+                if (DesignTime)
+                {
+                    var firstMappedChild = node.Children.FirstOrDefault(child => child.Source != null) as IntermediateNode;
+                    var valueStart = firstMappedChild?.Source;
+
+                    using (context.CodeWriter.BuildLinePragma(node.Source))
+                    {
+                        var assignmentPrefixLength = propertyValueAccessor.Length + " = ".Length;
+                        if (node.BoundAttribute.IsEnum &&
+                            node.Children.Count == 1 &&
+                            node.Children.First() is IntermediateToken token &&
+                            token.IsCSharp)
+                        {
+                            assignmentPrefixLength += $"global::{node.BoundAttribute.TypeName}.".Length;
+
+                            if (valueStart != null)
+                            {
+                                context.CodeWriter.WritePadding(assignmentPrefixLength, node.Source, context);
+                            }
+
+                            context.CodeWriter
+                                .WriteStartAssignment(propertyValueAccessor)
+                                .Write("global::")
+                                .Write(node.BoundAttribute.TypeName)
+                                .Write(".");
+                        }
+                        else
+                        {
+                            if (valueStart != null)
+                            {
+                                context.CodeWriter.WritePadding(assignmentPrefixLength, node.Source, context);
+                            }
+
+                            context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
+                        }
+
+                        RenderTagHelperAttributeInline(context, node, node.Source);
+
+                        context.CodeWriter.WriteLine(";");
+                    }
+                }
+                else
+                {
+                    using (context.CodeWriter.BuildLinePragma(node.Source))
+                    {
+                        context.CodeWriter.WriteStartAssignment(propertyValueAccessor);
+
+                        if (node.BoundAttribute.IsEnum &&
+                            node.Children.Count == 1 &&
+                            node.Children.First() is IntermediateToken token &&
+                            token.IsCSharp)
+                        {
+                            context.CodeWriter
+                                .Write("global::")
+                                .Write(node.BoundAttribute.TypeName)
+                                .Write(".");
+                        }
+
+                        RenderTagHelperAttributeInline(context, node, node.Source);
+
+                        context.CodeWriter.WriteLine(";");
+                    }
+                }
+            }
+
+            if (!DesignTime)
+            {
+                // We need to inform the context of the attribute value.
+                context.CodeWriter
+                    .WriteStartInstanceMethodInvocation(
+                        ExecutionContextVariableName,
+                        ExecutionContextAddTagHelperAttributeMethodName)
+                    .WriteStringLiteral(node.AttributeName)
+                    .WriteParameterSeparator()
+                    .Write(propertyValueAccessor)
+                    .WriteParameterSeparator()
+                    .Write($"global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.{node.AttributeStructure}")
+                    .WriteEndMethodInvocation();
+            }
+        }
+
+        public void WriteTagHelperRuntime(CodeRenderingContext context, DefaultTagHelperRuntimeIntermediateNode node)
+        {
+            if (!DesignTime)
+            {
+                context.CodeWriter.WriteLine("#line hidden");
+
+                // Need to disable the warning "X is assigned to but never used." for the value buffer since
+                // whether it's used depends on how a TagHelper is used.
+                context.CodeWriter.WriteLine("#pragma warning disable 0414");
+                context.CodeWriter.WriteField(PrivateModifiers, "string", StringValueBufferVariableName);
+                context.CodeWriter.WriteLine("#pragma warning restore 0414");
+
+                context.CodeWriter.WriteField(PrivateModifiers, ExecutionContextTypeName, ExecutionContextVariableName);
+
+                context.CodeWriter
+                    .Write("private ")
+                    .Write(TagHelperRunnerTypeName)
+                    .Write(" ")
+                    .Write(RunnerVariableName)
+                    .Write(" = new ")
+                    .Write(TagHelperRunnerTypeName)
+                    .WriteLine("();");
+
+                var backedScopeManageVariableName = "__backed" + ScopeManagerVariableName;
+                context.CodeWriter
+                    .Write("private ")
+                    .WriteVariableDeclaration(
+                        ScopeManagerTypeName,
+                        backedScopeManageVariableName,
+                        value: null);
+
+                context.CodeWriter
+                .Write("private ")
+                .Write(ScopeManagerTypeName)
+                .Write(" ")
+                .WriteLine(ScopeManagerVariableName);
+
+                using (context.CodeWriter.BuildScope())
+                {
+                    context.CodeWriter.WriteLine("get");
+                    using (context.CodeWriter.BuildScope())
+                    {
+                        context.CodeWriter
+                            .Write("if (")
+                            .Write(backedScopeManageVariableName)
+                            .WriteLine(" == null)");
+
+                        using (context.CodeWriter.BuildScope())
+                        {
+                            context.CodeWriter
+                                .WriteStartAssignment(backedScopeManageVariableName)
+                                .WriteStartNewObject(ScopeManagerTypeName)
+                                .Write(StartTagHelperWritingScopeMethodName)
+                                .WriteParameterSeparator()
+                                .Write(EndTagHelperWritingScopeMethodName)
+                                .WriteEndMethodInvocation();
+                        }
+
+                        context.CodeWriter
+                            .Write("return ")
+                            .Write(backedScopeManageVariableName)
+                            .WriteLine(";");
+                    }
+                }
+            }
+        }
+
+        private void RenderTagHelperAttributeInline(
+            CodeRenderingContext context,
+            DefaultTagHelperPropertyIntermediateNode property,
+            SourceSpan? span)
+        {
+            for (var i = 0; i < property.Children.Count; i++)
+            {
+                RenderTagHelperAttributeInline(context, property, property.Children[i], span);
+            }
+        }
+
+        private void RenderTagHelperAttributeInline(
+            CodeRenderingContext context,
+            DefaultTagHelperPropertyIntermediateNode property,
+            IntermediateNode node,
+            SourceSpan? span)
+        {
+            if (node is CSharpExpressionIntermediateNode || node is HtmlContentIntermediateNode)
+            {
+                for (var i = 0; i < node.Children.Count; i++)
+                {
+                    RenderTagHelperAttributeInline(context, property, node.Children[i], span);
+                }
+            }
+            else if (node is IntermediateToken token)
+            {
+                if (DesignTime && node.Source != null)
+                {
+                    context.AddLineMappingFor(node);
+                }
+
+                context.CodeWriter.Write(token.Content);
+            }
+            else if (node is CSharpCodeIntermediateNode)
+            {
+                var error = new RazorError(
+                    LegacyResources.TagHelpers_CodeBlocks_NotSupported_InAttributes,
+                    SourceLocation.FromSpan(span),
+                    span == null ? -1 : span.Value.Length);
+                context.Diagnostics.Add(RazorDiagnostic.Create(error));
+            }
+            else if (node is TemplateIntermediateNode)
+            {
+                var expectedTypeName = property.IsIndexerNameMatch ? property.BoundAttribute.IndexerTypeName : property.BoundAttribute.TypeName;
+                var error = new RazorError(
+                    LegacyResources.FormatTagHelpers_InlineMarkupBlocks_NotSupported_InAttributes(expectedTypeName),
+                    SourceLocation.FromSpan(span),
+                    span == null ? -1 : span.Value.Length);
+                context.Diagnostics.Add(RazorDiagnostic.Create(error));
+            }
+        }
+
+        private string GetContent(HtmlContentIntermediateNode node)
+        {
+            var builder = new StringBuilder();
+            for (var i = 0; i < node.Children.Count; i++)
+            {
+                if (node.Children[i] is IntermediateToken token && token.IsHtml)
+                {
+                    builder.Append(token.Content);
+                }
+            }
+
+            return builder.ToString();
+        }
+
+        private static string GetTagHelperPropertyAccessor(
+            bool isIndexerNameMatch,
+            string tagHelperVariableName,
+            string attributeName,
+            BoundAttributeDescriptor descriptor)
+        {
+            var propertyAccessor = $"{tagHelperVariableName}.{descriptor.GetPropertyName()}";
+
+            if (isIndexerNameMatch)
+            {
+                var dictionaryKey = attributeName.Substring(descriptor.IndexerNamePrefix.Length);
+                propertyAccessor += $"[\"{dictionaryKey}\"]";
+            }
+
+            return propertyAccessor;
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/IDefaultTagHelperTargetExtension.cs

@@ -0,0 +1,22 @@
+// 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 Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public interface IDefaultTagHelperTargetExtension : ICodeTargetExtension
+    {
+        void WriteTagHelperBody(CodeRenderingContext context, DefaultTagHelperBodyIntermediateNode node);
+
+        void WriteTagHelperCreate(CodeRenderingContext context, DefaultTagHelperCreateIntermediateNode node);
+
+        void WriteTagHelperExecute(CodeRenderingContext context, DefaultTagHelperExecuteIntermediateNode node);
+
+        void WriteTagHelperHtmlAttribute(CodeRenderingContext context, DefaultTagHelperHtmlAttributeIntermediateNode node);
+
+        void WriteTagHelperProperty(CodeRenderingContext context, DefaultTagHelperPropertyIntermediateNode node);
+
+        void WriteTagHelperRuntime(CodeRenderingContext context, DefaultTagHelperRuntimeIntermediateNode node);
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/Extensions/IPreallocatedAttributeTargetExtension.cs

@@ -2,18 +2,17 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
-using Microsoft.AspNetCore.Razor.Language.Extensions;
 
 namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
     internal interface IPreallocatedAttributeTargetExtension : ICodeTargetExtension
     {
-        void WriteDeclarePreallocatedTagHelperHtmlAttribute(CodeRenderingContext context, DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode node);
+        void WriteTagHelperHtmlAttribute(CodeRenderingContext context, PreallocatedTagHelperHtmlAttributeIntermediateNode node);
 
-        void WriteAddPreallocatedTagHelperHtmlAttribute(CodeRenderingContext context, AddPreallocatedTagHelperHtmlAttributeIntermediateNode node);
+        void WriteTagHelperHtmlAttributeValue(CodeRenderingContext context, PreallocatedTagHelperHtmlAttributeValueIntermediateNode node);
 
-        void WriteDeclarePreallocatedTagHelperAttribute(CodeRenderingContext context, DeclarePreallocatedTagHelperAttributeIntermediateNode node);
+        void WriteTagHelperProperty(CodeRenderingContext context, PreallocatedTagHelperPropertyIntermediateNode node);
 
-        void WriteSetPreallocatedTagHelperProperty(CodeRenderingContext context, SetPreallocatedTagHelperPropertyIntermediateNode node);
+        void WriteTagHelperPropertyValue(CodeRenderingContext context, PreallocatedTagHelperPropertyValueIntermediateNode node);
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedAttributeTargetExtension.cs

@@ -20,7 +20,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
 
         public string FormatInvalidIndexerAssignmentMethodName { get; set; } = "InvalidTagHelperIndexerAssignment";
 
-        public void WriteDeclarePreallocatedTagHelperHtmlAttribute(CodeRenderingContext context, DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode node)
+        public void WriteTagHelperHtmlAttributeValue(CodeRenderingContext context, PreallocatedTagHelperHtmlAttributeValueIntermediateNode node)
         {
             context.CodeWriter
                 .Write("private static readonly global::")
@@ -29,7 +29,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 .Write(node.VariableName)
                 .Write(" = ")
                 .WriteStartNewObject("global::" + TagHelperAttributeTypeName)
-                .WriteStringLiteral(node.Name);
+                .WriteStringLiteral(node.AttributeName);
 
             if (node.AttributeStructure == AttributeStructure.Minimized)
             {
@@ -48,7 +48,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             }
         }
 
-        public void WriteAddPreallocatedTagHelperHtmlAttribute(CodeRenderingContext context, AddPreallocatedTagHelperHtmlAttributeIntermediateNode node)
+        public void WriteTagHelperHtmlAttribute(CodeRenderingContext context, PreallocatedTagHelperHtmlAttributeIntermediateNode node)
         {
             context.CodeWriter
                 .WriteStartInstanceMethodInvocation(ExecutionContextVariableName, ExecutionContextAddHtmlAttributeMethodName)
@@ -56,7 +56,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 .WriteEndMethodInvocation();
         }
 
-        public void WriteDeclarePreallocatedTagHelperAttribute(CodeRenderingContext context, DeclarePreallocatedTagHelperAttributeIntermediateNode node)
+        public void WriteTagHelperPropertyValue(CodeRenderingContext context, PreallocatedTagHelperPropertyValueIntermediateNode node)
         {
             context.CodeWriter
                 .Write("private static readonly global::")
@@ -65,7 +65,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 .Write(node.VariableName)
                 .Write(" = ")
                 .WriteStartNewObject("global::" + TagHelperAttributeTypeName)
-                .WriteStringLiteral(node.Name)
+                .WriteStringLiteral(node.AttributeName)
                 .WriteParameterSeparator()
                 .WriteStringLiteral(node.Value)
                 .WriteParameterSeparator()
@@ -73,21 +73,20 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 .WriteEndMethodInvocation();
         }
 
-        public void WriteSetPreallocatedTagHelperProperty(CodeRenderingContext context, SetPreallocatedTagHelperPropertyIntermediateNode node)
+        public void WriteTagHelperProperty(CodeRenderingContext context, PreallocatedTagHelperPropertyIntermediateNode node)
         {
-            var tagHelperVariableName = GetTagHelperVariableName(node.TagHelperTypeName);
-            var propertyName = node.Descriptor.GetPropertyName();
-            var propertyValueAccessor = GetTagHelperPropertyAccessor(node.IsIndexerNameMatch, tagHelperVariableName, node.AttributeName, node.Descriptor);
+            var propertyName = node.BoundAttribute.GetPropertyName();
+            var propertyValueAccessor = GetTagHelperPropertyAccessor(node.IsIndexerNameMatch, node.Field, node.AttributeName, node.BoundAttribute);
             var attributeValueAccessor = $"{node.VariableName}.Value" /* ORIGINAL: TagHelperAttributeValuePropertyName */;
 
             // Ensure that the property we're trying to set has initialized its dictionary bound properties.
             if (node.IsIndexerNameMatch &&
-                context.TagHelperRenderingContext.VerifiedPropertyDictionaries.Add($"{node.TagHelperTypeName}.{propertyName}"))
+                context.TagHelperRenderingContext.VerifiedPropertyDictionaries.Add($"{node.TagHelper.GetTypeName()}.{propertyName}"))
             {
                 // Throw a reasonable Exception at runtime if the dictionary property is null.
                 context.CodeWriter
                     .Write("if (")
-                    .Write(tagHelperVariableName)
+                    .Write(node.Field)
                     .Write(".")
                     .Write(propertyName)
                     .WriteLine(" == null)");
@@ -101,7 +100,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                         .WriteStartMethodInvocation(FormatInvalidIndexerAssignmentMethodName)
                         .WriteStringLiteral(node.AttributeName)
                         .WriteParameterSeparator()
-                        .WriteStringLiteral(node.TagHelperTypeName)
+                        .WriteStringLiteral(node.TagHelper.GetTypeName())
                         .WriteParameterSeparator()
                         .WriteStringLiteral(propertyName)
                         .WriteEndMethodInvocation(endLine: false)   // End of method call
@@ -119,8 +118,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 .WriteEndMethodInvocation();
         }
 
-        private static string GetTagHelperVariableName(string tagHelperTypeName) => "__" + tagHelperTypeName.Replace('.', '_');
-
         private static string GetTagHelperPropertyAccessor(
             bool isIndexerNameMatch,
             string tagHelperVariableName,

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedTagHelperAttributeOptimizationPass.cs

@@ -10,7 +10,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
     internal class PreallocatedTagHelperAttributeOptimizationPass : IntermediateNodePassBase, IRazorOptimizationPass
     {
-        public override int Order => DefaultFeatureOrder;
+        // We want to run after the passes that 'lower' tag helpers.
+        public override int Order => DefaultFeatureOrder + 1000;
 
         protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIntermediateNode documentNode)
         {
@@ -18,7 +19,10 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             walker.VisitDocument(documentNode);
         }
 
-        internal class PreallocatedTagHelperWalker : IntermediateNodeWalker
+        internal class PreallocatedTagHelperWalker : 
+            IntermediateNodeWalker,
+            IExtensionIntermediateNodeVisitor<DefaultTagHelperHtmlAttributeIntermediateNode>,
+            IExtensionIntermediateNodeVisitor<DefaultTagHelperPropertyIntermediateNode>
         {
             private const string PreAllocatedAttributeVariablePrefix = "__tagHelperAttribute_";
 
@@ -34,7 +38,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 VisitDefault(node);
             }
 
-            public override void VisitAddTagHelperHtmlAttribute(AddTagHelperHtmlAttributeIntermediateNode node)
+            public void VisitExtension(DefaultTagHelperHtmlAttributeIntermediateNode node)
             {
                 if (node.Children.Count != 1 || !(node.Children.First() is HtmlContentIntermediateNode))
                 {
@@ -44,15 +48,15 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 var htmlContentNode = node.Children.First() as HtmlContentIntermediateNode;
                 var plainTextValue = GetContent(htmlContentNode);
 
-                DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode declaration = null;
+                PreallocatedTagHelperHtmlAttributeValueIntermediateNode declaration = null;
 
                 for (var i = 0; i < _classDeclaration.Children.Count; i++)
                 {
                     var current = _classDeclaration.Children[i];
 
-                    if (current is DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode existingDeclaration)
+                    if (current is PreallocatedTagHelperHtmlAttributeValueIntermediateNode existingDeclaration)
                     {
-                        if (string.Equals(existingDeclaration.Name, node.Name, StringComparison.Ordinal) &&
+                        if (string.Equals(existingDeclaration.AttributeName, node.AttributeName, StringComparison.Ordinal) &&
                             string.Equals(existingDeclaration.Value, plainTextValue, StringComparison.Ordinal) &&
                             existingDeclaration.AttributeStructure == node.AttributeStructure)
                         {
@@ -66,17 +70,17 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 {
                     var variableCount = _classDeclaration.Children.Count - _variableCountOffset;
                     var preAllocatedAttributeVariableName = PreAllocatedAttributeVariablePrefix + variableCount;
-                    declaration = new DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode
+                    declaration = new PreallocatedTagHelperHtmlAttributeValueIntermediateNode
                     {
                         VariableName = preAllocatedAttributeVariableName,
-                        Name = node.Name,
+                        AttributeName = node.AttributeName,
                         Value = plainTextValue,
                         AttributeStructure = node.AttributeStructure,
                     };
                     _classDeclaration.Children.Insert(_preallocatedDeclarationCount++, declaration);
                 }
 
-                var addPreAllocatedAttribute = new AddPreallocatedTagHelperHtmlAttributeIntermediateNode
+                var addPreAllocatedAttribute = new PreallocatedTagHelperHtmlAttributeIntermediateNode
                 {
                     VariableName = declaration.VariableName,
                 };
@@ -85,9 +89,9 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 Parent.Children[nodeIndex] = addPreAllocatedAttribute;
             }
 
-            public override void VisitSetTagHelperProperty(SetTagHelperPropertyIntermediateNode node)
+            public void VisitExtension(DefaultTagHelperPropertyIntermediateNode node)
             {
-                if (!(node.Descriptor.IsStringProperty || (node.IsIndexerNameMatch && node.Descriptor.IsIndexerStringProperty)) ||
+                if (!(node.BoundAttribute.IsStringProperty || (node.IsIndexerNameMatch && node.BoundAttribute.IsIndexerStringProperty)) ||
                     node.Children.Count != 1 ||
                     !(node.Children.First() is HtmlContentIntermediateNode))
                 {
@@ -97,15 +101,15 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 var htmlContentNode = node.Children.First() as HtmlContentIntermediateNode;
                 var plainTextValue = GetContent(htmlContentNode);
 
-                DeclarePreallocatedTagHelperAttributeIntermediateNode declaration = null;
+                PreallocatedTagHelperPropertyValueIntermediateNode declaration = null;
 
                 for (var i = 0; i < _classDeclaration.Children.Count; i++)
                 {
                     var current = _classDeclaration.Children[i];
 
-                    if (current is DeclarePreallocatedTagHelperAttributeIntermediateNode existingDeclaration)
+                    if (current is PreallocatedTagHelperPropertyValueIntermediateNode existingDeclaration)
                     {
-                        if (string.Equals(existingDeclaration.Name, node.AttributeName, StringComparison.Ordinal) &&
+                        if (string.Equals(existingDeclaration.AttributeName, node.AttributeName, StringComparison.Ordinal) &&
                             string.Equals(existingDeclaration.Value, plainTextValue, StringComparison.Ordinal) &&
                             existingDeclaration.AttributeStructure == node.AttributeStructure)
                         {
@@ -119,25 +123,19 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 {
                     var variableCount = _classDeclaration.Children.Count - _variableCountOffset;
                     var preAllocatedAttributeVariableName = PreAllocatedAttributeVariablePrefix + variableCount;
-                    declaration = new DeclarePreallocatedTagHelperAttributeIntermediateNode
+                    declaration = new PreallocatedTagHelperPropertyValueIntermediateNode()
                     {
                         VariableName = preAllocatedAttributeVariableName,
-                        Name = node.AttributeName,
+                        AttributeName = node.AttributeName,
                         Value = plainTextValue,
                         AttributeStructure = node.AttributeStructure,
                     };
                     _classDeclaration.Children.Insert(_preallocatedDeclarationCount++, declaration);
                 }
 
-                var setPreallocatedProperty = new SetPreallocatedTagHelperPropertyIntermediateNode
+                var setPreallocatedProperty = new PreallocatedTagHelperPropertyIntermediateNode(node)
                 {
                     VariableName = declaration.VariableName,
-                    AttributeName = node.AttributeName,
-                    TagHelperTypeName = node.TagHelperTypeName,
-                    PropertyName = node.PropertyName,
-                    Descriptor = node.Descriptor,
-                    Binding = node.Binding,
-                    IsIndexerNameMatch = node.IsIndexerNameMatch,
                 };
 
                 var nodeIndex = Parent.Children.IndexOf(node);

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedTagHelperHtmlAttributeIntermediateNode.cs

@@ -7,10 +7,10 @@ using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
-    internal sealed class AddPreallocatedTagHelperHtmlAttributeIntermediateNode : ExtensionIntermediateNode
+    internal sealed class PreallocatedTagHelperHtmlAttributeIntermediateNode : ExtensionIntermediateNode
     {
         public override RazorDiagnosticCollection Diagnostics { get; } = ReadOnlyDiagnosticCollection.Instance;
-        
+
         public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
 
         public override bool HasDiagnostics => false;
@@ -24,7 +24,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            AcceptExtensionNode<AddPreallocatedTagHelperHtmlAttributeIntermediateNode>(this, visitor);
+            AcceptExtensionNode<PreallocatedTagHelperHtmlAttributeIntermediateNode>(this, visitor);
         }
 
         public override void WriteNode(CodeTarget target, CodeRenderingContext context)
@@ -46,7 +46,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 return;
             }
 
-            extension.WriteAddPreallocatedTagHelperHtmlAttribute(context, this);
+            extension.WriteTagHelperHtmlAttribute(context, this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedTagHelperHtmlAttributeValueIntermediateNode.cs

@@ -7,17 +7,41 @@ using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
-    internal sealed class DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode : ExtensionIntermediateNode
+    internal sealed class PreallocatedTagHelperHtmlAttributeValueIntermediateNode : ExtensionIntermediateNode
     {
+        public PreallocatedTagHelperHtmlAttributeValueIntermediateNode()
+        {
+        }
+
+        public PreallocatedTagHelperHtmlAttributeValueIntermediateNode(DefaultTagHelperHtmlAttributeIntermediateNode htmlAttributeNode)
+        {
+            if (htmlAttributeNode == null)
+            {
+                throw new ArgumentNullException(nameof(htmlAttributeNode));
+            }
+
+            Source = htmlAttributeNode.Source;
+
+            for (var i = 0; i < htmlAttributeNode.Children.Count; i++)
+            {
+                Children.Add(htmlAttributeNode.Children[i]);
+            }
+
+            for (var i = 0; i < htmlAttributeNode.Diagnostics.Count; i++)
+            {
+                Diagnostics.Add(htmlAttributeNode.Diagnostics[i]);
+            }
+        }
+
         public override RazorDiagnosticCollection Diagnostics { get; } = ReadOnlyDiagnosticCollection.Instance;
-        
+
         public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
 
         public override bool HasDiagnostics => false;
 
         public string VariableName { get; set; }
 
-        public string Name { get; set; }
+        public string AttributeName { get; set; }
 
         public string Value { get; set; }
 
@@ -30,7 +54,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            AcceptExtensionNode<DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode>(this, visitor);
+            AcceptExtensionNode<PreallocatedTagHelperHtmlAttributeValueIntermediateNode>(this, visitor);
         }
 
         public override void WriteNode(CodeTarget target, CodeRenderingContext context)
@@ -52,7 +76,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 return;
             }
 
-            extension.WriteDeclarePreallocatedTagHelperHtmlAttribute(context, this);
+            extension.WriteTagHelperHtmlAttributeValue(context, this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedTagHelperPropertyIntermediateNode.cs

@@ -7,28 +7,51 @@ using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
-    internal sealed class SetPreallocatedTagHelperPropertyIntermediateNode : ExtensionIntermediateNode
+    internal sealed class PreallocatedTagHelperPropertyIntermediateNode : ExtensionIntermediateNode
     {
+        public PreallocatedTagHelperPropertyIntermediateNode()
+        {
+        }
+
+        public PreallocatedTagHelperPropertyIntermediateNode(DefaultTagHelperPropertyIntermediateNode propertyNode)
+        {
+            if (propertyNode == null)
+            {
+                throw new ArgumentNullException(nameof(propertyNode));
+            }
+
+            AttributeName = propertyNode.AttributeName;
+            AttributeStructure = propertyNode.AttributeStructure;
+            BoundAttribute = propertyNode.BoundAttribute;
+            Field = propertyNode.Field;
+            IsIndexerNameMatch = propertyNode.IsIndexerNameMatch;
+            Property = propertyNode.Property;
+            Source = propertyNode.Source;
+            TagHelper = propertyNode.TagHelper;
+        }
+
         public override RazorDiagnosticCollection Diagnostics => ReadOnlyDiagnosticCollection.Instance;
-        
+
         public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
 
         public override bool HasDiagnostics => false;
 
-        public string VariableName { get; set; }
-
         public string AttributeName { get; set; }
 
-        public string TagHelperTypeName { get; set; }
+        public AttributeStructure AttributeStructure { get; set; }
 
-        public string PropertyName { get; set; }
+        public BoundAttributeDescriptor BoundAttribute { get; set; }
 
-        public BoundAttributeDescriptor Descriptor { get; set; }
-
-        public TagHelperBinding Binding { get; set; }
+        public string Field { get; set; }
 
         public bool IsIndexerNameMatch { get; set; }
 
+        public string Property { get; set; }
+
+        public TagHelperDescriptor TagHelper { get; set; }
+
+        public string VariableName { get; set; }
+
         public override void Accept(IntermediateNodeVisitor visitor)
         {
             if (visitor == null)
@@ -36,7 +59,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            AcceptExtensionNode<SetPreallocatedTagHelperPropertyIntermediateNode>(this, visitor);
+            AcceptExtensionNode<PreallocatedTagHelperPropertyIntermediateNode>(this, visitor);
         }
 
         public override void WriteNode(CodeTarget target, CodeRenderingContext context)
@@ -58,7 +81,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 return;
             }
 
-            extension.WriteSetPreallocatedTagHelperProperty(context, this);
+            extension.WriteTagHelperProperty(context, this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Extensions/PreallocatedTagHelperPropertyValueIntermediateNode.cs

@@ -7,17 +7,17 @@ using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 namespace Microsoft.AspNetCore.Razor.Language.Extensions
 {
-    internal sealed class DeclarePreallocatedTagHelperAttributeIntermediateNode : ExtensionIntermediateNode
+    internal sealed class PreallocatedTagHelperPropertyValueIntermediateNode : ExtensionIntermediateNode
     {
         public override RazorDiagnosticCollection Diagnostics { get; } = ReadOnlyDiagnosticCollection.Instance;
-        
+
         public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
 
         public override bool HasDiagnostics => false;
 
         public string VariableName { get; set; }
 
-        public string Name { get; set; }
+        public string AttributeName { get; set; }
 
         public string Value { get; set; }
 
@@ -30,7 +30,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            AcceptExtensionNode<DeclarePreallocatedTagHelperAttributeIntermediateNode>(this, visitor);
+            AcceptExtensionNode<PreallocatedTagHelperPropertyValueIntermediateNode>(this, visitor);
         }
 
         public override void WriteNode(CodeTarget target, CodeRenderingContext context)
@@ -52,7 +52,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                 return;
             }
 
-            extension.WriteDeclarePreallocatedTagHelperAttribute(context, this);
+            extension.WriteTagHelperPropertyValue(context, this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Extensions/TemplateIntermediateNode.cs

@@ -10,7 +10,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
     public sealed class TemplateIntermediateNode : ExtensionIntermediateNode
     {
         public override IntermediateNodeCollection Children { get; } = new DefaultIntermediateNodeCollection();
-        
+
         public override void Accept(IntermediateNodeVisitor visitor)
         {
             if (visitor == null)

src/Microsoft.AspNetCore.Razor.Language/Intermediate/CommonAnnotations.cs

@@ -3,7 +3,7 @@
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    internal static class CommonAnnotations
+    public static class CommonAnnotations
     {
         public static readonly object Imported = "Imported";
 
@@ -12,5 +12,10 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
         public static readonly object PrimaryMethod = "PrimaryMethod";
 
         public static readonly object PrimaryNamespace = "PrimaryNamespace";
+
+        public static class DefaultTagHelperExtension
+        {
+            public static readonly object TagHelperField = "TagHelperField";
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Intermediate/CreateTagHelperIntermediateNode.cs

@@ -1,59 +0,0 @@
-// 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;
-
-namespace Microsoft.AspNetCore.Razor.Language.Intermediate
-{
-    public sealed class CreateTagHelperIntermediateNode : IntermediateNode
-    {
-        private RazorDiagnosticCollection _diagnostics;
-        private ItemCollection _annotations;
-
-        public override ItemCollection Annotations
-        {
-            get
-            {
-                if (_annotations == null)
-                {
-                    _annotations = new DefaultItemCollection();
-                }
-
-                return _annotations;
-            }
-        }
-
-        public override RazorDiagnosticCollection Diagnostics
-        {
-            get
-            {
-                if (_diagnostics == null)
-                {
-                    _diagnostics = new DefaultRazorDiagnosticCollection();
-                }
-
-                return _diagnostics;
-            }
-        }
-
-        public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
-
-        public override SourceSpan? Source { get; set; }
-
-        public override bool HasDiagnostics => _diagnostics != null && _diagnostics.Count > 0;
-
-        public string TagHelperTypeName { get; set; }
-
-        public TagHelperDescriptor Descriptor { get; set; }
-
-        public override void Accept(IntermediateNodeVisitor visitor)
-        {
-            if (visitor == null)
-            {
-                throw new ArgumentNullException(nameof(visitor));
-            }
-
-            visitor.VisitCreateTagHelper(this);
-        }
-    }
-}

src/Microsoft.AspNetCore.Razor.Language/Intermediate/DeclareTagHelperFieldsIntermediateNode.cs

@@ -1,58 +0,0 @@
-// 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;
-using System.Collections.Generic;
-
-namespace Microsoft.AspNetCore.Razor.Language.Intermediate
-{
-    public sealed class DeclareTagHelperFieldsIntermediateNode : IntermediateNode
-    {
-        private RazorDiagnosticCollection _diagnostics;
-        private ItemCollection _annotations;
-
-        public override ItemCollection Annotations
-        {
-            get
-            {
-                if (_annotations == null)
-                {
-                    _annotations = new DefaultItemCollection();
-                }
-
-                return _annotations;
-            }
-        }
-
-        public override RazorDiagnosticCollection Diagnostics
-        {
-            get
-            {
-                if (_diagnostics == null)
-                {
-                    _diagnostics = new DefaultRazorDiagnosticCollection();
-                }
-
-                return _diagnostics;
-            }
-        }
-
-        public override IntermediateNodeCollection Children => ReadOnlyIntermediateNodeCollection.Instance;
-
-        public override SourceSpan? Source { get; set; }
-
-        public override bool HasDiagnostics => _diagnostics != null && _diagnostics.Count > 0;
-
-        public ISet<string> UsedTagHelperTypeNames { get; set; } = new HashSet<string>(StringComparer.Ordinal);
-
-        public override void Accept(IntermediateNodeVisitor visitor)
-        {
-            if (visitor == null)
-            {
-                throw new ArgumentNullException(nameof(visitor));
-            }
-
-            visitor.VisitDeclareTagHelperFields(this);
-        }
-    }
-}

src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeIntermediateNode.cs

@@ -42,7 +42,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 
         public override bool HasDiagnostics => _diagnostics != null && _diagnostics.Count > 0;
 
-        public string Name { get; set; }
+        public string AttributeName { get; set; }
 
         public string Prefix { get; set; }
 

src/Microsoft.AspNetCore.Razor.Language/Intermediate/HtmlAttributeValueIntermediateNode.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {

src/Microsoft.AspNetCore.Razor.Language/Intermediate/IntermediateNodeExtensions.cs

@@ -42,5 +42,35 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
                 }
             }
         }
+
+        public static IReadOnlyList<TNode> FindDescendantNodes<TNode>(this IntermediateNode node)
+            where TNode : IntermediateNode
+        {
+            var visitor = new Visitor<TNode>();
+            visitor.Visit(node);
+
+            if (visitor.Results.Count > 0 && visitor.Results[0] == node)
+            {
+                // Don't put the node itself in the results
+                visitor.Results.Remove((TNode)node);
+            }
+
+            return visitor.Results;
+        }
+
+        private class Visitor<TNode> : IntermediateNodeWalker where TNode : IntermediateNode
+        {
+            public List<TNode> Results { get; } = new List<TNode>();
+
+            public override void VisitDefault(IntermediateNode node)
+            {
+                if (node is TNode match)
+                {
+                    Results.Add(match);
+                }
+
+                base.VisitDefault(node);
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Intermediate/IntermediateNodeVisitor.cs

@@ -109,11 +109,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
             VisitDefault(node);
         }
 
-        public virtual void VisitDeclareTagHelperFields(DeclareTagHelperFieldsIntermediateNode node)
-        {
-            VisitDefault(node);
-        }
-
         public virtual void VisitTagHelper(TagHelperIntermediateNode node)
         {
             VisitDefault(node);
@@ -124,17 +119,12 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
             VisitDefault(node);
         }
 
-        public virtual void VisitCreateTagHelper(CreateTagHelperIntermediateNode node)
+        public virtual void VisitTagHelperProperty(TagHelperPropertyIntermediateNode node)
         {
             VisitDefault(node);
         }
 
-        public virtual void VisitSetTagHelperProperty(SetTagHelperPropertyIntermediateNode node)
-        {
-            VisitDefault(node);
-        }
-
-        public virtual void VisitAddTagHelperHtmlAttribute(AddTagHelperHtmlAttributeIntermediateNode node)
+        public virtual void VisitTagHelperHtmlAttribute(TagHelperHtmlAttributeIntermediateNode node)
         {
             VisitDefault(node);
         }

src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperHtmlAttributeIntermediateNode.cs

@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public sealed class AddTagHelperHtmlAttributeIntermediateNode : IntermediateNode
+    public sealed class TagHelperHtmlAttributeIntermediateNode : IntermediateNode
     {
         private RazorDiagnosticCollection _diagnostics;
         private ItemCollection _annotations;
@@ -42,7 +42,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 
         public override bool HasDiagnostics => _diagnostics != null && _diagnostics.Count > 0;
 
-        public string Name { get; set; }
+        public string AttributeName { get; set; }
 
         public AttributeStructure AttributeStructure { get; set; }
 
@@ -53,7 +53,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            visitor.VisitAddTagHelperHtmlAttribute(this);
+            visitor.VisitTagHelperHtmlAttribute(this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperIntermediateNode.cs

@@ -47,24 +47,24 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
         public string TagName { get; set; }
 
         public TagMode TagMode { get; set; }
-
+        
         public ICollection<TagHelperDescriptor> TagHelpers { get; } = new List<TagHelperDescriptor>();
 
         public TagHelperBodyIntermediateNode Body => Children.OfType<TagHelperBodyIntermediateNode>().SingleOrDefault();
 
-        public IEnumerable<SetTagHelperPropertyIntermediateNode> SetTagHelperProperties
+        public IEnumerable<TagHelperPropertyIntermediateNode> Properties
         {
             get
             {
-                return Children.OfType<SetTagHelperPropertyIntermediateNode>();
+                return Children.OfType<TagHelperPropertyIntermediateNode>();
             }
         }
 
-        public IEnumerable<AddTagHelperHtmlAttributeIntermediateNode> AddTagHelperHtmlAttributes
+        public IEnumerable<TagHelperHtmlAttributeIntermediateNode> HtmlAttributes
         {
             get
             {
-                return Children.OfType<AddTagHelperHtmlAttributeIntermediateNode>();
+                return Children.OfType<TagHelperHtmlAttributeIntermediateNode>();
             }
         }
 

src/Microsoft.AspNetCore.Razor.Language/Intermediate/TagHelperPropertyIntermediateNode.cs

@@ -5,7 +5,7 @@ using System;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
-    public sealed class SetTagHelperPropertyIntermediateNode : IntermediateNode
+    public sealed class TagHelperPropertyIntermediateNode : IntermediateNode
     {
         private RazorDiagnosticCollection _diagnostics;
         private ItemCollection _annotations;
@@ -42,17 +42,13 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 
         public override bool HasDiagnostics => _diagnostics != null && _diagnostics.Count > 0;
 
-        public string TagHelperTypeName { get; set; }
-
-        public string PropertyName { get; set; }
-
         public string AttributeName { get; set; }
 
         public AttributeStructure AttributeStructure { get; set; }
 
-        public BoundAttributeDescriptor Descriptor { get; set; }
+        public BoundAttributeDescriptor BoundAttribute { get; set; }
 
-        public TagHelperBinding Binding { get; set; }
+        public TagHelperDescriptor TagHelper { get; set; }
 
         public bool IsIndexerNameMatch { get; set; }
 
@@ -63,7 +59,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
                 throw new ArgumentNullException(nameof(visitor));
             }
 
-            visitor.VisitSetTagHelperProperty(this);
+            visitor.VisitTagHelperProperty(this);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/ItemCollection.cs

@@ -14,6 +14,8 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public abstract bool IsReadOnly { get; }
 
+        public abstract void Add(object key, object value);
+
         public abstract void Add(KeyValuePair<object, object> item);
 
         public abstract void Clear();

src/Microsoft.AspNetCore.Razor.Language/RazorCodeGenerationOptions.cs

@@ -15,6 +15,11 @@ namespace Microsoft.AspNetCore.Razor.Language
             return new DefaultRazorCodeGenerationOptions(indentWithTabs: false, indentSize: 4, designTime: false, suppressChecksum: false);
         }
 
+        public static RazorCodeGenerationOptions CreateDesignTimeDefault()
+        {
+            return new DefaultRazorCodeGenerationOptions(indentWithTabs: false, indentSize: 4, designTime: true, suppressChecksum: false);
+        }
+
         public abstract bool DesignTime { get; }
 
         public abstract bool IndentWithTabs { get; }

src/Microsoft.AspNetCore.Razor.Language/RazorDiagnosticFactory.cs

@@ -66,6 +66,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 $"{DiagnosticPrefix}3000",
                 () => Resources.TagHelper_InvalidRestrictedChildNullOrWhitespace,
                 RazorDiagnosticSeverity.Error);
+
         public static RazorDiagnostic CreateTagHelper_InvalidRestrictedChildNullOrWhitespace(string tagHelperDisplayName)
         {
             var diagnostic = RazorDiagnostic.Create(

src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs

@@ -72,9 +72,10 @@ namespace Microsoft.AspNetCore.Razor.Language
             // Intermediate Node Passes
             builder.Features.Add(new DefaultDocumentClassifierPass());
             builder.Features.Add(new DirectiveRemovalOptimizationPass());
+            builder.Features.Add(new DefaultTagHelperOptimizationPass());
 
-            // Default Runtime Targets
-            builder.AddTargetExtension(new PreallocatedAttributeTargetExtension());
+            // Default Code Target Extensions
+            // (currently none)
 
             // Default configuration
             var configurationFeature = new DefaultDocumentClassifierPassFeature();
@@ -104,7 +105,12 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         internal static void AddRuntimeDefaults(IRazorEngineBuilder builder)
         {
+            // Intermediate Node Passes
             builder.Features.Add(new PreallocatedTagHelperAttributeOptimizationPass());
+
+            // Code Target Extensions
+            builder.AddTargetExtension(new DefaultTagHelperTargetExtension() { DesignTime = false });
+            builder.AddTargetExtension(new PreallocatedAttributeTargetExtension());
         }
 
         internal static void AddDesignTimeDefaults(IRazorEngineBuilder builder)
@@ -115,7 +121,8 @@ namespace Microsoft.AspNetCore.Razor.Language
             // Intermediate Node Passes
             builder.Features.Add(new DesignTimeDirectivePass());
 
-            // DesignTime Runtime Targets
+            // Code Target Extensions
+            builder.AddTargetExtension(new DefaultTagHelperTargetExtension() { DesignTime = true });
             builder.AddTargetExtension(new DesignTimeDirectiveTargetExtension());
         }
 

src/Microsoft.AspNetCore.Razor.Language/ReadOnlyItemCollection.cs

@@ -21,6 +21,16 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public override bool IsReadOnly => true;
 
+        public override void Add(object key, object value)
+        {
+            if (key == null)
+            {
+                throw new ArgumentNullException(nameof(key));
+            }
+
+            throw new NotSupportedException();
+        }
+
         public override void Add(KeyValuePair<object, object> item)
         {
             if (item.Key == null)

src/Microsoft.AspNetCore.Razor.Language/SourceLocation.cs

@@ -71,6 +71,20 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// <remarks>Set property is only accessible for deserialization purposes.</remarks>
         public int CharacterIndex { get; set; }
 
+        /// <summary>
+        /// Creates a new instance of <see cref="SourceLocation"/> from the provided span.
+        /// </summary>
+        /// <param name="span">
+        /// The souce span. If <c>null</c>, <see cref="SourceLocation.Undefined"/> will be returned.
+        /// </param>
+        /// <remarks>A <see cref="SourceLocation"/> that corresponds to the beginning of the span.</remarks>
+        public static SourceLocation FromSpan(SourceSpan? span)
+        {
+            return span == null ? 
+                SourceLocation.Undefined : 
+                new SourceLocation(span.Value.FilePath, span.Value.AbsoluteIndex, span.Value.LineIndex, span.Value.CharacterIndex);
+        }
+
         /// <inheritdoc />
         public override string ToString()
         {

src/Microsoft.AspNetCore.Razor.Language/TagHelperConventions.cs

@@ -3,8 +3,8 @@
 
 namespace Microsoft.AspNetCore.Razor.Language
 {
-    internal static class TagHelperConventions
+    public static class TagHelperConventions
     {
-        internal const string DefaultKind = "ITagHelper";
+        public static readonly string DefaultKind = "ITagHelper";
     }
 }

src/Microsoft.AspNetCore.Razor.Language/TagHelperDescriptorExtensions.cs

@@ -7,16 +7,36 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     public static class TagHelperDescriptorExtensions
     {
-        public static string GetTypeName(this TagHelperDescriptor descriptor)
+        public static string GetTypeName(this TagHelperDescriptor tagHelper)
         {
-            descriptor.Metadata.TryGetValue(TagHelperMetadata.Common.TypeName, out var typeName);
+            if (tagHelper == null)
+            {
+                throw new ArgumentNullException(nameof(tagHelper));
+            }
 
+            tagHelper.Metadata.TryGetValue(TagHelperMetadata.Common.TypeName, out var typeName);
             return typeName;
         }
 
-        public static bool IsDefaultKind(this TagHelperDescriptor descriptor)
+        public static bool IsDefaultKind(this TagHelperDescriptor tagHelper)
         {
-            return string.Equals(descriptor.Kind, TagHelperConventions.DefaultKind, StringComparison.Ordinal);
+            if (tagHelper == null)
+            {
+                throw new ArgumentNullException(nameof(tagHelper));
+            }
+
+            return string.Equals(tagHelper.Kind, TagHelperConventions.DefaultKind, StringComparison.Ordinal);
+        }
+
+        public static bool KindUsesDefaultTagHelperRuntime(this TagHelperDescriptor tagHelper)
+        {
+            if (tagHelper == null)
+            {
+                throw new ArgumentNullException(nameof(tagHelper));
+            }
+
+            tagHelper.Metadata.TryGetValue(TagHelperMetadata.Runtime.Name, out var value);
+            return string.Equals(TagHelperConventions.DefaultKind, value, StringComparison.Ordinal);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/TagHelperMetadata.cs

@@ -3,13 +3,18 @@
 
 namespace Microsoft.AspNetCore.Razor.Language
 {
-    internal static class TagHelperMetadata
+    public static class TagHelperMetadata
     {
         public static class Common
         {
-            internal const string PropertyName = "Common.PropertyName";
+            public static readonly string PropertyName = "Common.PropertyName";
 
-            internal const string TypeName = "Common.TypeName";
+            public static readonly string TypeName = "Common.TypeName";
+        }
+
+        public static class Runtime
+        {
+            public static readonly string Name = "Runtime.Name";
         }
     }
 }

src/Microsoft.CodeAnalysis.Razor/DefaultTagHelperDescriptorFactory.cs

@@ -57,6 +57,7 @@ namespace Microsoft.CodeAnalysis.Razor
 
             var typeName = GetFullName(type);
             var assemblyName = type.ContainingAssembly.Identity.Name;
+
             var descriptorBuilder = TagHelperDescriptorBuilder.Create(typeName, assemblyName);
             descriptorBuilder.SetTypeName(typeName);
 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/InstrumentationPassTest.cs

@@ -140,7 +140,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             var builder = IntermediateNodeBuilder.Create(document);
             builder.Push(new TagHelperIntermediateNode());
 
-            builder.Push(new AddTagHelperHtmlAttributeIntermediateNode());
+            builder.Push(new TagHelperHtmlAttributeIntermediateNode());
 
             builder.Push(new CSharpExpressionIntermediateNode()
             {
@@ -171,7 +171,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                         n,
                         c =>
                         {
-                            Assert.IsType<AddTagHelperHtmlAttributeIntermediateNode>(c);
+                            Assert.IsType<TagHelperHtmlAttributeIntermediateNode>(c);
                             Children(
                                 c,
                                 s => CSharpExpression("Hi", s));
@@ -187,7 +187,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             var builder = IntermediateNodeBuilder.Create(document);
             builder.Push(new TagHelperIntermediateNode());
 
-            builder.Push(new SetTagHelperPropertyIntermediateNode());
+            builder.Push(new TagHelperPropertyIntermediateNode());
 
             builder.Push(new CSharpExpressionIntermediateNode()
             {
@@ -218,7 +218,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
                         n,
                         c =>
                         {
-                            Assert.IsType<SetTagHelperPropertyIntermediateNode>(c);
+                            Assert.IsType<TagHelperPropertyIntermediateNode>(c);
                             Children(
                                 c,
                                 s => CSharpExpression("Hi", s));

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/IntegrationTests/CodeGenerationIntegrationTest.cs

@@ -547,9 +547,10 @@ public class AllTagHelper : {typeof(TagHelper).FullName}
             IEnumerable<MetadataReference> compilationReferences,
             IEnumerable<string> expectedErrors = null)
         {
-            var syntaxTree = CSharpSyntaxTree.ParseText(document.GetCSharpDocument().GeneratedCode);
-            var options = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
+            var cSharp = document.GetCSharpDocument().GeneratedCode;
 
+            var syntaxTree = CSharpSyntaxTree.ParseText(cSharp);
+            var options = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
             var compilation = CSharpCompilation.Create("CodeGenerationTestAssembly", new[] { syntaxTree }, compilationReferences, options);
 
             var diagnostics = compilation.GetDiagnostics();

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/ModelExpressionPassTest.cs

@@ -46,7 +46,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
             // Assert
             var tagHelper = FindTagHelperNode(irDocument);
-            var setProperty = tagHelper.Children.OfType<SetTagHelperPropertyIntermediateNode>().Single();
+            var setProperty = tagHelper.Children.OfType<TagHelperPropertyIntermediateNode>().Single();
 
             var token = Assert.IsType<IntermediateToken>(Assert.Single(setProperty.Children));
             Assert.True(token.IsCSharp);
@@ -87,7 +87,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
             // Assert
             var tagHelper = FindTagHelperNode(irDocument);
-            var setProperty = tagHelper.Children.OfType<SetTagHelperPropertyIntermediateNode>().Single();
+            var setProperty = tagHelper.Children.OfType<TagHelperPropertyIntermediateNode>().Single();
 
             var expression = Assert.IsType<CSharpExpressionIntermediateNode>(Assert.Single(setProperty.Children));
             Assert.Equal("ModelExpressionProvider.CreateModelExpression(ViewData, __model => __model.Bar)", GetCSharpContent(expression));
@@ -132,7 +132,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
             // Assert
             var tagHelper = FindTagHelperNode(irDocument);
-            var setProperty = tagHelper.Children.OfType<SetTagHelperPropertyIntermediateNode>().Single();
+            var setProperty = tagHelper.Children.OfType<TagHelperPropertyIntermediateNode>().Single();
 
             var expression = Assert.IsType<CSharpExpressionIntermediateNode>(Assert.Single(setProperty.Children));
             Assert.Equal("ModelExpressionProvider.CreateModelExpression(ViewData, __model => Bar)", GetCSharpContent(expression));

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TagHelperDescriptorExtensionsTest.cs

@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
         [Fact]
         public void IsViewComponentKind_ReturnsFalse_ForNonVCTHDescriptor()
         {
-            //Arrange
+            // Arrange
             var tagHelper = CreateTagHelperDescriptor();
 
             // Act
@@ -62,21 +62,21 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
         private static TagHelperDescriptor CreateTagHelperDescriptor()
         {
-            var descriptor = TagHelperDescriptorBuilder.Create("TypeName", "AssemblyName")
+            var tagHelper = TagHelperDescriptorBuilder.Create("TypeName", "AssemblyName")
                 .TagMatchingRuleDescriptor(rule => rule.RequireTagName("tag-name"))
                 .Build();
 
-            return descriptor;
+            return tagHelper;
         }
 
         private static TagHelperDescriptor CreateViewComponentTagHelperDescriptor(string name = "ViewComponentName")
         {
-            var descriptor = TagHelperDescriptorBuilder.Create(ViewComponentTagHelperConventions.Kind, "TypeName", "AssemblyName")
+            var tagHelper = TagHelperDescriptorBuilder.Create(ViewComponentTagHelperConventions.Kind, "TypeName", "AssemblyName")
                 .TagMatchingRuleDescriptor(rule => rule.RequireTagName("tag-name"))
                 .AddMetadata(ViewComponentTagHelperMetadata.Name, name)
                 .Build();
 
-            return descriptor;
+            return tagHelper;
         }
     }
 }

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper_DesignTime.codegen.cs

@@ -14,6 +14,7 @@ namespace AspNetCore
     using Microsoft.AspNetCore.Mvc.ViewFeatures;
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ModelExpressionTagHelper_cshtml : global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<DateTime>
     {
+        private global::InputTestTagHelper __InputTestTagHelper;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -27,7 +28,6 @@ global::System.Object __typeHelper = "InputTestTagHelper, AppCode";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::InputTestTagHelper __InputTestTagHelper = null;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper_DesignTime.ir.txt

@@ -11,6 +11,8 @@ Document -
         UsingDirective - (135:5,1 [40] ) - Microsoft.AspNetCore.Mvc.Rendering
         UsingDirective - (178:6,1 [43] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ModelExpressionTagHelper_cshtml - global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<DateTime> - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::InputTestTagHelper - __InputTestTagHelper
             DesignTimeDirective - 
                 DirectiveToken - (231:7,8 [62] ) - global::Microsoft.AspNetCore.Mvc.Rendering.IHtmlHelper<TModel>
                 DirectiveToken - (294:7,71 [4] ) - Html
@@ -29,31 +31,32 @@ Document -
                 DirectiveToken - (33:2,14 [29] ModelExpressionTagHelper.cshtml) - "InputTestTagHelper, AppCode"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - InputTestTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (17:1,0 [2] ModelExpressionTagHelper.cshtml)
                     IntermediateToken - (17:1,0 [2] ModelExpressionTagHelper.cshtml) - Html - \n
                 HtmlContent - (62:2,43 [4] ModelExpressionTagHelper.cshtml)
                     IntermediateToken - (62:2,43 [4] ModelExpressionTagHelper.cshtml) - Html - \n\n
                 TagHelper - (66:4,0 [25] ModelExpressionTagHelper.cshtml) - input-test - TagMode.SelfClosing
-                    TagHelperBody - 
-                    CreateTagHelper -  - InputTestTagHelper
-                    SetTagHelperProperty - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - for - For - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - InputTestTagHelper
+                    DefaultTagHelperProperty - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - for - Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression InputTestTagHelper.For - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - ModelExpressionProvider.CreateModelExpression(ViewData, __model => 
                             IntermediateToken -  - CSharp - __model.
                             IntermediateToken - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - CSharp - Date
                             IntermediateToken -  - CSharp - )
+                    DefaultTagHelperExecute - 
                 HtmlContent - (91:4,25 [2] ModelExpressionTagHelper.cshtml)
                     IntermediateToken - (91:4,25 [2] ModelExpressionTagHelper.cshtml) - Html - \n
                 TagHelper - (93:5,0 [27] ModelExpressionTagHelper.cshtml) - input-test - TagMode.SelfClosing
-                    TagHelperBody - 
-                    CreateTagHelper -  - InputTestTagHelper
-                    SetTagHelperProperty - (110:5,17 [6] ModelExpressionTagHelper.cshtml) - for - For - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - InputTestTagHelper
+                    DefaultTagHelperProperty - (110:5,17 [6] ModelExpressionTagHelper.cshtml) - for - Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression InputTestTagHelper.For - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - ModelExpressionProvider.CreateModelExpression(ViewData, __model => 
                             IntermediateToken - (111:5,18 [5] ModelExpressionTagHelper.cshtml) - CSharp - Model
                             IntermediateToken -  - CSharp - )
+                    DefaultTagHelperExecute - 
                 HtmlContent - (120:5,27 [2] ModelExpressionTagHelper.cshtml)
                     IntermediateToken - (120:5,27 [2] ModelExpressionTagHelper.cshtml) - Html - \n
             Inject - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper_DesignTime.mappings.txt

@@ -1,20 +1,20 @@
 Source Location: (7:0,7 [8] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper.cshtml)
 |DateTime|
-Generated Location: (889:19,0 [8] )
+Generated Location: (955:20,0 [8] )
 |DateTime|
 
 Source Location: (33:2,14 [29] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper.cshtml)
 |"InputTestTagHelper, AppCode"|
-Generated Location: (1030:23,37 [29] )
+Generated Location: (1096:24,37 [29] )
 |"InputTestTagHelper, AppCode"|
 
 Source Location: (83:4,17 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper.cshtml)
 |Date|
-Generated Location: (1675:35,102 [4] )
+Generated Location: (1668:35,102 [4] )
 |Date|
 
 Source Location: (111:5,18 [5] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper.cshtml)
 |Model|
-Generated Location: (1991:41,94 [5] )
+Generated Location: (1984:41,94 [5] )
 |Model|
 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper_Runtime.codegen.cs

@@ -16,9 +16,9 @@ namespace AspNetCore
     {
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -32,7 +32,7 @@ namespace AspNetCore
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::InputTestTagHelper __InputTestTagHelper = null;
+        private global::InputTestTagHelper __InputTestTagHelper;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ModelExpressionTagHelper_Runtime.ir.txt

@@ -10,7 +10,8 @@ Document -
         UsingDirective - (135:5,1 [42] ) - Microsoft.AspNetCore.Mvc.Rendering
         UsingDirective - (178:6,1 [45] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ModelExpressionTagHelper_cshtml - global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<DateTime> - 
-            DeclareTagHelperFields -  - InputTestTagHelper
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::InputTestTagHelper - __InputTestTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(17, 2, true);
@@ -27,14 +28,15 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(66, 25, false);
                 TagHelper - (66:4,0 [25] ModelExpressionTagHelper.cshtml) - input-test - TagMode.SelfClosing
-                    TagHelperBody - 
-                    CreateTagHelper -  - InputTestTagHelper
-                    SetTagHelperProperty - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - for - For - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - InputTestTagHelper
+                    DefaultTagHelperProperty - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - for - Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression InputTestTagHelper.For - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - ModelExpressionProvider.CreateModelExpression(ViewData, __model => 
                             IntermediateToken -  - CSharp - __model.
                             IntermediateToken - (83:4,17 [4] ModelExpressionTagHelper.cshtml) - CSharp - Date
                             IntermediateToken -  - CSharp - )
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 
@@ -46,13 +48,14 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(93, 27, false);
                 TagHelper - (93:5,0 [27] ModelExpressionTagHelper.cshtml) - input-test - TagMode.SelfClosing
-                    TagHelperBody - 
-                    CreateTagHelper -  - InputTestTagHelper
-                    SetTagHelperProperty - (110:5,17 [6] ModelExpressionTagHelper.cshtml) - for - For - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - InputTestTagHelper
+                    DefaultTagHelperProperty - (110:5,17 [6] ModelExpressionTagHelper.cshtml) - for - Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression InputTestTagHelper.For - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - ModelExpressionProvider.CreateModelExpression(ViewData, __model => 
                             IntermediateToken - (111:5,18 [5] ModelExpressionTagHelper.cshtml) - CSharp - Model
                             IntermediateToken -  - CSharp - )
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel_DesignTime.codegen.cs

@@ -19,6 +19,7 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
 #line hidden
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPagesWithoutModel_cshtml : global::Microsoft.AspNetCore.Mvc.RazorPages.Page
     {
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -28,7 +29,6 @@ global::System.Object __typeHelper = "*, AppCode";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::DivTagHelper __DivTagHelper = null;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel_DesignTime.ir.txt

@@ -12,6 +12,8 @@ Document -
         UsingDirective - (178:6,1 [43] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         UsingDirective - (38:3,1 [41] RazorPagesWithoutModel.cshtml) - Microsoft.AspNetCore.Mvc.RazorPages
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPagesWithoutModel_cshtml - global::Microsoft.AspNetCore.Mvc.RazorPages.Page - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             DesignTimeDirective - 
                 DirectiveToken - (231:7,8 [62] ) - global::Microsoft.AspNetCore.Mvc.Rendering.IHtmlHelper<TModel>
                 DirectiveToken - (294:7,71 [4] ) - Html
@@ -29,7 +31,6 @@ Document -
                 DirectiveToken - (23:2,14 [12] RazorPagesWithoutModel.cshtml) - "*, AppCode"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - DivTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (7:1,0 [2] RazorPagesWithoutModel.cshtml)
                     IntermediateToken - (7:1,0 [2] RazorPagesWithoutModel.cshtml) - Html - \n
@@ -49,15 +50,16 @@ Document -
                     IntermediateToken - (449:21,43 [1] RazorPagesWithoutModel.cshtml) - Html - >
                     IntermediateToken - (450:21,44 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
                 TagHelper - (456:22,4 [31] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (468:22,16 [11] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (468:22,16 [11] RazorPagesWithoutModel.cshtml) - Html - text-danger
+                    DefaultTagHelperExecute - 
                 HtmlContent - (487:22,35 [6] RazorPagesWithoutModel.cshtml)
                     IntermediateToken - (487:22,35 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
                 TagHelper - (493:23,4 [237] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (517:23,28 [48] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (517:23,28 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
                             IntermediateToken - (527:24,8 [6] RazorPagesWithoutModel.cshtml) - Html - <label
@@ -69,7 +71,7 @@ Document -
                             IntermediateToken - (570:24,51 [8] RazorPagesWithoutModel.cshtml) - Html - </label>
                             IntermediateToken - (578:24,59 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
                         TagHelper - (588:25,8 [130] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (611:25,31 [101] RazorPagesWithoutModel.cshtml)
                                     IntermediateToken - (611:25,31 [14] RazorPagesWithoutModel.cshtml) - Html - \n            
                                     IntermediateToken - (625:26,12 [6] RazorPagesWithoutModel.cshtml) - Html - <input
@@ -81,24 +83,26 @@ Document -
                                     IntermediateToken - (694:27,37 [1] RazorPagesWithoutModel.cshtml) - Html - >
                                     IntermediateToken - (695:27,38 [7] RazorPagesWithoutModel.cshtml) - Html - </span>
                                     IntermediateToken - (702:27,45 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
-                            CreateTagHelper -  - DivTagHelper
-                            AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (600:25,20 [9] RazorPagesWithoutModel.cshtml)
                                     IntermediateToken - (600:25,20 [9] RazorPagesWithoutModel.cshtml) - Html - col-md-10
+                            DefaultTagHelperExecute - 
                         HtmlContent - (718:28,14 [6] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (718:28,14 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (505:23,16 [10] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (505:23,16 [10] RazorPagesWithoutModel.cshtml) - Html - form-group
+                    DefaultTagHelperExecute - 
                 HtmlContent - (730:29,10 [6] RazorPagesWithoutModel.cshtml)
                     IntermediateToken - (730:29,10 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
                 TagHelper - (736:30,4 [174] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (760:30,28 [10] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (760:30,28 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
                         TagHelper - (770:31,8 [128] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (809:31,47 [83] RazorPagesWithoutModel.cshtml)
                                     IntermediateToken - (809:31,47 [14] RazorPagesWithoutModel.cshtml) - Html - \n            
                                     IntermediateToken - (823:32,12 [7] RazorPagesWithoutModel.cshtml) - Html - <button
@@ -108,16 +112,18 @@ Document -
                                     IntermediateToken - (869:32,58 [4] RazorPagesWithoutModel.cshtml) - Html - Save
                                     IntermediateToken - (873:32,62 [9] RazorPagesWithoutModel.cshtml) - Html - </button>
                                     IntermediateToken - (882:32,71 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
-                            CreateTagHelper -  - DivTagHelper
-                            AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (782:31,20 [25] RazorPagesWithoutModel.cshtml)
                                     IntermediateToken - (782:31,20 [25] RazorPagesWithoutModel.cshtml) - Html - col-md-offset-2 col-md-10
+                            DefaultTagHelperExecute - 
                         HtmlContent - (898:33,14 [6] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (898:33,14 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (748:30,16 [10] RazorPagesWithoutModel.cshtml)
                             IntermediateToken - (748:30,16 [10] RazorPagesWithoutModel.cshtml) - Html - form-group
+                    DefaultTagHelperExecute - 
                 HtmlContent - (910:34,10 [11] RazorPagesWithoutModel.cshtml)
                     IntermediateToken - (910:34,10 [2] RazorPagesWithoutModel.cshtml) - Html - \n
                     IntermediateToken - (912:35,0 [7] RazorPagesWithoutModel.cshtml) - Html - </form>

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel_DesignTime.mappings.txt

@@ -5,12 +5,12 @@ Generated Location: (696:15,0 [41] )
 
 Source Location: (23:2,14 [12] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel.cshtml)
 |"*, AppCode"|
-Generated Location: (1099:24,37 [12] )
+Generated Location: (1153:25,37 [12] )
 |"*, AppCode"|
 
 Source Location: (566:24,47 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel.cshtml)
 |Name|
-Generated Location: (1647:36,47 [4] )
+Generated Location: (1640:36,47 [4] )
 |Name|
 
 Source Location: (95:5,12 [283] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel.cshtml)
@@ -28,7 +28,7 @@ Source Location: (95:5,12 [283] TestFiles/IntegrationTests/CodeGenerationIntegra
         public string Name { get; set; }
     }
 |
-Generated Location: (2128:47,12 [283] )
+Generated Location: (2121:47,12 [283] )
 |
     public IActionResult OnPost(Customer customer)
     {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel_Runtime.codegen.cs

@@ -25,9 +25,9 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_3 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("class", new global::Microsoft.AspNetCore.Html.HtmlString("col-md-offset-2 col-md-10"), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -41,7 +41,7 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::DivTagHelper __DivTagHelper = null;
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPagesWithoutModel_Runtime.ir.txt

@@ -11,11 +11,12 @@ Document -
         UsingDirective - (178:6,1 [45] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         UsingDirective - (38:3,1 [43] RazorPagesWithoutModel.cshtml) - Microsoft.AspNetCore.Mvc.RazorPages
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPagesWithoutModel_cshtml - global::Microsoft.AspNetCore.Mvc.RazorPages.Page - 
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0 - class - text-danger - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1 - class - col-md-10 - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2 - class - form-group - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3 - class - col-md-offset-2 col-md-10 - AttributeStructure.DoubleQuotes
-            DeclareTagHelperFields -  - DivTagHelper
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_0 - class - text-danger - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_1 - class - col-md-10 - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_2 - class - form-group - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_3 - class - col-md-offset-2 col-md-10 - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(7, 2, true);
@@ -47,9 +48,10 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(456, 31, false);
                 TagHelper - (456:22,4 [31] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 
@@ -61,7 +63,7 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(493, 237, false);
                 TagHelper - (493:23,4 [237] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(517, 48, true);
                         HtmlContent - (517:23,28 [48] RazorPagesWithoutModel.cshtml)
@@ -87,7 +89,7 @@ Document -
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(588, 130, false);
                         TagHelper - (588:25,8 [130] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - BeginContext(611, 101, true);
                                 HtmlContent - (611:25,31 [101] RazorPagesWithoutModel.cshtml)
@@ -103,8 +105,9 @@ Document -
                                     IntermediateToken - (702:27,45 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - EndContext();
-                            CreateTagHelper -  - DivTagHelper
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            DefaultTagHelperExecute - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
                         CSharpCode - 
@@ -113,8 +116,9 @@ Document -
                             IntermediateToken - (718:28,14 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 
@@ -126,7 +130,7 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(736, 174, false);
                 TagHelper - (736:30,4 [174] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(760, 10, true);
                         HtmlContent - (760:30,28 [10] RazorPagesWithoutModel.cshtml)
@@ -136,7 +140,7 @@ Document -
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(770, 128, false);
                         TagHelper - (770:31,8 [128] RazorPagesWithoutModel.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - BeginContext(809, 83, true);
                                 HtmlContent - (809:31,47 [83] RazorPagesWithoutModel.cshtml)
@@ -150,8 +154,9 @@ Document -
                                     IntermediateToken - (882:32,71 [10] RazorPagesWithoutModel.cshtml) - Html - \n        
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - EndContext();
-                            CreateTagHelper -  - DivTagHelper
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3
+                            DefaultTagHelperExecute - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
                         CSharpCode - 
@@ -160,8 +165,9 @@ Document -
                             IntermediateToken - (898:33,14 [6] RazorPagesWithoutModel.cshtml) - Html - \n    
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages_DesignTime.codegen.cs

@@ -19,6 +19,7 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
 #line hidden
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPages_cshtml : global::Microsoft.AspNetCore.Mvc.RazorPages.Page
     {
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -32,7 +33,6 @@ global::System.Object __typeHelper = "*, AppCode";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::DivTagHelper __DivTagHelper = null;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages_DesignTime.ir.txt

@@ -12,6 +12,8 @@ Document -
         UsingDirective - (178:6,1 [43] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         UsingDirective - (55:4,1 [41] RazorPages.cshtml) - Microsoft.AspNetCore.Mvc.RazorPages
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPages_cshtml - global::Microsoft.AspNetCore.Mvc.RazorPages.Page - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             DesignTimeDirective - 
                 DirectiveToken - (231:7,8 [62] ) - global::Microsoft.AspNetCore.Mvc.Rendering.IHtmlHelper<TModel>
                 DirectiveToken - (294:7,71 [4] ) - Html
@@ -30,7 +32,6 @@ Document -
                 DirectiveToken - (40:3,14 [12] RazorPages.cshtml) - "*, AppCode"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - DivTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (7:1,0 [2] RazorPages.cshtml)
                     IntermediateToken - (7:1,0 [2] RazorPages.cshtml) - Html - \n
@@ -50,15 +51,16 @@ Document -
                     IntermediateToken - (543:25,43 [2] RazorPages.cshtml) - Html -  >
                     IntermediateToken - (545:25,45 [6] RazorPages.cshtml) - Html - \n    
                 TagHelper - (551:26,4 [31] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (563:26,16 [11] RazorPages.cshtml)
                             IntermediateToken - (563:26,16 [11] RazorPages.cshtml) - Html - text-danger
+                    DefaultTagHelperExecute - 
                 HtmlContent - (582:26,35 [6] RazorPages.cshtml)
                     IntermediateToken - (582:26,35 [6] RazorPages.cshtml) - Html - \n    
                 TagHelper - (588:27,4 [243] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (612:27,28 [48] RazorPages.cshtml)
                             IntermediateToken - (612:27,28 [10] RazorPages.cshtml) - Html - \n        
                             IntermediateToken - (622:28,8 [6] RazorPages.cshtml) - Html - <label
@@ -70,7 +72,7 @@ Document -
                             IntermediateToken - (671:28,57 [8] RazorPages.cshtml) - Html - </label>
                             IntermediateToken - (679:28,65 [10] RazorPages.cshtml) - Html - \n        
                         TagHelper - (689:29,8 [130] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (712:29,31 [101] RazorPages.cshtml)
                                     IntermediateToken - (712:29,31 [14] RazorPages.cshtml) - Html - \n            
                                     IntermediateToken - (726:30,12 [6] RazorPages.cshtml) - Html - <input
@@ -82,24 +84,26 @@ Document -
                                     IntermediateToken - (795:31,37 [1] RazorPages.cshtml) - Html - >
                                     IntermediateToken - (796:31,38 [7] RazorPages.cshtml) - Html - </span>
                                     IntermediateToken - (803:31,45 [10] RazorPages.cshtml) - Html - \n        
-                            CreateTagHelper -  - DivTagHelper
-                            AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (701:29,20 [9] RazorPages.cshtml)
                                     IntermediateToken - (701:29,20 [9] RazorPages.cshtml) - Html - col-md-10
+                            DefaultTagHelperExecute - 
                         HtmlContent - (819:32,14 [6] RazorPages.cshtml)
                             IntermediateToken - (819:32,14 [6] RazorPages.cshtml) - Html - \n    
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (600:27,16 [10] RazorPages.cshtml)
                             IntermediateToken - (600:27,16 [10] RazorPages.cshtml) - Html - form-group
+                    DefaultTagHelperExecute - 
                 HtmlContent - (831:33,10 [6] RazorPages.cshtml)
                     IntermediateToken - (831:33,10 [6] RazorPages.cshtml) - Html - \n    
                 TagHelper - (837:34,4 [174] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (861:34,28 [10] RazorPages.cshtml)
                             IntermediateToken - (861:34,28 [10] RazorPages.cshtml) - Html - \n        
                         TagHelper - (871:35,8 [128] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (910:35,47 [83] RazorPages.cshtml)
                                     IntermediateToken - (910:35,47 [14] RazorPages.cshtml) - Html - \n            
                                     IntermediateToken - (924:36,12 [7] RazorPages.cshtml) - Html - <button
@@ -109,16 +113,18 @@ Document -
                                     IntermediateToken - (970:36,58 [4] RazorPages.cshtml) - Html - Save
                                     IntermediateToken - (974:36,62 [9] RazorPages.cshtml) - Html - </button>
                                     IntermediateToken - (983:36,71 [10] RazorPages.cshtml) - Html - \n        
-                            CreateTagHelper -  - DivTagHelper
-                            AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (883:35,20 [25] RazorPages.cshtml)
                                     IntermediateToken - (883:35,20 [25] RazorPages.cshtml) - Html - col-md-offset-2 col-md-10
+                            DefaultTagHelperExecute - 
                         HtmlContent - (999:37,14 [6] RazorPages.cshtml)
                             IntermediateToken - (999:37,14 [6] RazorPages.cshtml) - Html - \n    
-                    CreateTagHelper -  - DivTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (849:34,16 [10] RazorPages.cshtml)
                             IntermediateToken - (849:34,16 [10] RazorPages.cshtml) - Html - form-group
+                    DefaultTagHelperExecute - 
                 HtmlContent - (1011:38,10 [11] RazorPages.cshtml)
                     IntermediateToken - (1011:38,10 [2] RazorPages.cshtml) - Html - \n
                     IntermediateToken - (1013:39,0 [7] RazorPages.cshtml) - Html - </form>

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages_DesignTime.mappings.txt

@@ -5,17 +5,17 @@ Generated Location: (672:15,0 [41] )
 
 Source Location: (16:2,7 [8] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages.cshtml)
 |NewModel|
-Generated Location: (1026:24,0 [8] )
+Generated Location: (1080:25,0 [8] )
 |NewModel|
 
 Source Location: (40:3,14 [12] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages.cshtml)
 |"*, AppCode"|
-Generated Location: (1167:28,37 [12] )
+Generated Location: (1221:29,37 [12] )
 |"*, AppCode"|
 
 Source Location: (661:28,47 [10] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages.cshtml)
 |Model.Name|
-Generated Location: (1703:40,47 [10] )
+Generated Location: (1696:40,47 [10] )
 |Model.Name|
 
 Source Location: (112:6,12 [360] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages.cshtml)
@@ -36,7 +36,7 @@ Source Location: (112:6,12 [360] TestFiles/IntegrationTests/CodeGenerationIntegr
         public string Name { get; set; }
     }
 |
-Generated Location: (2178:51,12 [360] )
+Generated Location: (2171:51,12 [360] )
 |
     public class NewModel : PageModel
     {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages_Runtime.codegen.cs

@@ -25,9 +25,9 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_3 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("class", new global::Microsoft.AspNetCore.Html.HtmlString("col-md-offset-2 col-md-10"), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -41,7 +41,7 @@ using Microsoft.AspNetCore.Mvc.RazorPages;
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::DivTagHelper __DivTagHelper = null;
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorPages_Runtime.ir.txt

@@ -11,11 +11,12 @@ Document -
         UsingDirective - (178:6,1 [45] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         UsingDirective - (55:4,1 [43] RazorPages.cshtml) - Microsoft.AspNetCore.Mvc.RazorPages
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_RazorPages_cshtml - global::Microsoft.AspNetCore.Mvc.RazorPages.Page - 
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0 - class - text-danger - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1 - class - col-md-10 - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2 - class - form-group - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3 - class - col-md-offset-2 col-md-10 - AttributeStructure.DoubleQuotes
-            DeclareTagHelperFields -  - DivTagHelper
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_0 - class - text-danger - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_1 - class - col-md-10 - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_2 - class - form-group - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_3 - class - col-md-offset-2 col-md-10 - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(7, 2, true);
@@ -47,9 +48,10 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(551, 31, false);
                 TagHelper - (551:26,4 [31] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 
@@ -61,7 +63,7 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(588, 243, false);
                 TagHelper - (588:27,4 [243] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(612, 48, true);
                         HtmlContent - (612:27,28 [48] RazorPages.cshtml)
@@ -87,7 +89,7 @@ Document -
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(689, 130, false);
                         TagHelper - (689:29,8 [130] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - BeginContext(712, 101, true);
                                 HtmlContent - (712:29,31 [101] RazorPages.cshtml)
@@ -103,8 +105,9 @@ Document -
                                     IntermediateToken - (803:31,45 [10] RazorPages.cshtml) - Html - \n        
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - EndContext();
-                            CreateTagHelper -  - DivTagHelper
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            DefaultTagHelperExecute - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
                         CSharpCode - 
@@ -113,8 +116,9 @@ Document -
                             IntermediateToken - (819:32,14 [6] RazorPages.cshtml) - Html - \n    
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 
@@ -126,7 +130,7 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(837, 174, false);
                 TagHelper - (837:34,4 [174] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(861, 10, true);
                         HtmlContent - (861:34,28 [10] RazorPages.cshtml)
@@ -136,7 +140,7 @@ Document -
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(871, 128, false);
                         TagHelper - (871:35,8 [128] RazorPages.cshtml) - div - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - BeginContext(910, 83, true);
                                 HtmlContent - (910:35,47 [83] RazorPages.cshtml)
@@ -150,8 +154,9 @@ Document -
                                     IntermediateToken - (983:36,71 [10] RazorPages.cshtml) - Html - \n        
                                 CSharpCode - 
                                     IntermediateToken -  - CSharp - EndContext();
-                            CreateTagHelper -  - DivTagHelper
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_3
+                            DefaultTagHelperExecute - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
                         CSharpCode - 
@@ -160,8 +165,9 @@ Document -
                             IntermediateToken - (999:37,14 [6] RazorPages.cshtml) - Html - \n    
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
-                    CreateTagHelper -  - DivTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - DivTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper_DesignTime.codegen.cs

@@ -14,6 +14,8 @@ namespace AspNetCore
     using Microsoft.AspNetCore.Mvc.ViewFeatures;
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml : global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<dynamic>
     {
+        private global::AllTagHelper __AllTagHelper;
+        private global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper __TestViewComponentTagHelper;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -23,8 +25,6 @@ global::System.Object __typeHelper = "*, AppCode";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper = null;
-        private global::AllTagHelper __AllTagHelper = null;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {
@@ -34,14 +34,14 @@ global::System.Object __typeHelper = "*, AppCode";
 
 #line default
 #line hidden
-            __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper = CreateTagHelper<global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper>();
             __AllTagHelper = CreateTagHelper<global::AllTagHelper>();
+            __TestViewComponentTagHelper = CreateTagHelper<global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper>();
 #line 6 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper.cshtml"
                 __o = foo;
 
 #line default
 #line hidden
-            __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper.firstName = string.Empty;
+            __TestViewComponentTagHelper.firstName = string.Empty;
             __AllTagHelper.Bar = " World";
         }
         #pragma warning restore 1998

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper_DesignTime.ir.txt

@@ -11,6 +11,9 @@ Document -
         UsingDirective - (135:5,1 [40] ) - Microsoft.AspNetCore.Mvc.Rendering
         UsingDirective - (178:6,1 [43] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml - global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<dynamic> - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::AllTagHelper - __AllTagHelper
+            FieldDeclaration -  - private - global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper - __TestViewComponentTagHelper
             DesignTimeDirective - 
                 DirectiveToken - (231:7,8 [62] ) - global::Microsoft.AspNetCore.Mvc.Rendering.IHtmlHelper<TModel>
                 DirectiveToken - (294:7,71 [4] ) - Html
@@ -28,7 +31,6 @@ Document -
                 DirectiveToken - (14:0,14 [12] ViewComponentTagHelper.cshtml) - "*, AppCode"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper - AllTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (26:0,26 [2] ViewComponentTagHelper.cshtml)
                     IntermediateToken - (26:0,26 [2] ViewComponentTagHelper.cshtml) - Html - \n
@@ -37,15 +39,16 @@ Document -
                 HtmlContent - (59:4,0 [2] ViewComponentTagHelper.cshtml)
                     IntermediateToken - (59:4,0 [2] ViewComponentTagHelper.cshtml) - Html - \n
                 TagHelper - (61:5,0 [50] ViewComponentTagHelper.cshtml) - vc:test - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper
-                    CreateTagHelper -  - AllTagHelper
-                    SetTagHelperProperty - (82:5,21 [4] ViewComponentTagHelper.cshtml) - first-name - firstName - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - AllTagHelper
+                    DefaultTagHelperCreate -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper
+                    DefaultTagHelperProperty - (82:5,21 [4] ViewComponentTagHelper.cshtml) - first-name - string TestViewComponentTagHelper.firstName - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - (83:5,22 [3] ViewComponentTagHelper.cshtml)
                             IntermediateToken - (83:5,22 [3] ViewComponentTagHelper.cshtml) - CSharp - foo
-                    SetTagHelperProperty - (93:5,32 [6] ViewComponentTagHelper.cshtml) - bar - Bar - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperProperty - (93:5,32 [6] ViewComponentTagHelper.cshtml) - bar - string AllTagHelper.Bar - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (93:5,32 [6] ViewComponentTagHelper.cshtml)
                             IntermediateToken - (93:5,32 [6] ViewComponentTagHelper.cshtml) - Html -  World
+                    DefaultTagHelperExecute - 
             Inject - 
             Inject - 
             Inject - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper_DesignTime.mappings.txt

@@ -1,19 +1,19 @@
 Source Location: (14:0,14 [12] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper.cshtml)
 |"*, AppCode"|
-Generated Location: (921:19,37 [12] )
+Generated Location: (1168:21,37 [12] )
 |"*, AppCode"|
 
 Source Location: (30:1,2 [26] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper.cshtml)
 |
     var foo = "Hello";
 |
-Generated Location: (1663:31,2 [26] )
+Generated Location: (1538:31,2 [26] )
 |
     var foo = "Hello";
 |
 
 Source Location: (83:5,22 [3] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper.cshtml)
 |foo|
-Generated Location: (2232:39,22 [3] )
+Generated Location: (1996:39,22 [3] )
 |foo|
 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper_Runtime.codegen.cs

@@ -14,12 +14,13 @@ namespace AspNetCore
     using Microsoft.AspNetCore.Mvc.ViewFeatures;
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml : global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<dynamic>
     {
+        private global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper __TestViewComponentTagHelper;
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_0 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("bar", " World", global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -33,8 +34,7 @@ namespace AspNetCore
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper = null;
-        private global::AllTagHelper __AllTagHelper = null;
+        private global::AllTagHelper __AllTagHelper;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {
@@ -51,10 +51,10 @@ namespace AspNetCore
             __tagHelperExecutionContext = __tagHelperScopeManager.Begin("vc:test", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagAndEndTag, "test", async() => {
             }
             );
-            __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper = CreateTagHelper<global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper>();
-            __tagHelperExecutionContext.Add(__AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper);
             __AllTagHelper = CreateTagHelper<global::AllTagHelper>();
             __tagHelperExecutionContext.Add(__AllTagHelper);
+            __TestViewComponentTagHelper = CreateTagHelper<global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper>();
+            __tagHelperExecutionContext.Add(__TestViewComponentTagHelper);
             BeginWriteTagHelperAttribute();
 #line 6 "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper.cshtml"
          WriteLiteral(foo);
@@ -62,8 +62,8 @@ namespace AspNetCore
 #line default
 #line hidden
             __tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
-            __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper.firstName = __tagHelperStringValueBuffer;
-            __tagHelperExecutionContext.AddTagHelperAttribute("first-name", __AspNetCore_TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml___Generated__TestViewComponentTagHelper.firstName, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+            __TestViewComponentTagHelper.firstName = __tagHelperStringValueBuffer;
+            __tagHelperExecutionContext.AddTagHelperAttribute("first-name", __TestViewComponentTagHelper.firstName, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
             __AllTagHelper.Bar = (string)__tagHelperAttribute_0.Value;
             __tagHelperExecutionContext.AddTagHelperAttribute(__tagHelperAttribute_0);
             await __tagHelperRunner.RunAsync(__tagHelperExecutionContext);

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/ViewComponentTagHelper_Runtime.ir.txt

@@ -10,8 +10,10 @@ Document -
         UsingDirective - (135:5,1 [42] ) - Microsoft.AspNetCore.Mvc.Rendering
         UsingDirective - (178:6,1 [45] ) - Microsoft.AspNetCore.Mvc.ViewFeatures
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml - global::Microsoft.AspNetCore.Mvc.Razor.RazorPage<dynamic> - 
-            DeclarePreallocatedTagHelperAttribute -  - __tagHelperAttribute_0 - bar -  World - HtmlAttributeValueStyle.DoubleQuotes
-            DeclareTagHelperFields -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper - AllTagHelper
+            FieldDeclaration -  - private - global::AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper - __TestViewComponentTagHelper
+            PreallocatedTagHelperPropertyValue -  - __tagHelperAttribute_0 - bar -  World - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::AllTagHelper - __AllTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 CSharpCode - (30:1,2 [26] ViewComponentTagHelper.cshtml)
                     IntermediateToken - (30:1,2 [26] ViewComponentTagHelper.cshtml) - CSharp - \n    var foo = "Hello";\n
@@ -24,13 +26,14 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(61, 50, false);
                 TagHelper - (61:5,0 [50] ViewComponentTagHelper.cshtml) - vc:test - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
-                    CreateTagHelper -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper
-                    CreateTagHelper -  - AllTagHelper
-                    SetTagHelperProperty - (82:5,21 [4] ViewComponentTagHelper.cshtml) - first-name - firstName - HtmlAttributeValueStyle.DoubleQuotes
+                    DefaultTagHelperBody - 
+                    DefaultTagHelperCreate -  - AllTagHelper
+                    DefaultTagHelperCreate -  - AspNetCore.TestFiles_IntegrationTests_CodeGenerationIntegrationTest_ViewComponentTagHelper_cshtml.__Generated__TestViewComponentTagHelper
+                    DefaultTagHelperProperty - (82:5,21 [4] ViewComponentTagHelper.cshtml) - first-name - string TestViewComponentTagHelper.firstName - HtmlAttributeValueStyle.DoubleQuotes
                         CSharpExpression - (83:5,22 [3] ViewComponentTagHelper.cshtml)
                             IntermediateToken - (83:5,22 [3] ViewComponentTagHelper.cshtml) - CSharp - foo
-                    SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_0 - bar - Bar
+                    PreallocatedTagHelperProperty - (93:5,32 [6] ViewComponentTagHelper.cshtml) - __tagHelperAttribute_0 - bar - Bar
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
             Inject - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/InstrumentationPassIntegrationTest/BasicTest.codegen.cs

@@ -11,9 +11,9 @@ namespace Razor
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_2 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("unbound", new global::Microsoft.AspNetCore.Html.HtmlString("foo"), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -27,8 +27,8 @@ namespace Razor
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::FormTagHelper __FormTagHelper = null;
-        private global::InputTagHelper __InputTagHelper = null;
+        private global::FormTagHelper __FormTagHelper;
+        private global::InputTagHelper __InputTagHelper;
         #pragma warning disable 1998
         public async override global::System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/TestFiles/IntegrationTests/InstrumentationPassIntegrationTest/BasicTest.ir.txt

@@ -1,10 +1,12 @@
 Document - 
     NamespaceDeclaration -  - Razor
         ClassDeclaration -  - public - Template -  - 
-            DeclarePreallocatedTagHelperAttribute -  - __tagHelperAttribute_0 - value - Hello - HtmlAttributeValueStyle.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1 - type - text - AttributeStructure.SingleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2 - unbound - foo - AttributeStructure.DoubleQuotes
-            DeclareTagHelperFields -  - FormTagHelper - InputTagHelper
+            PreallocatedTagHelperPropertyValue -  - __tagHelperAttribute_0 - value - Hello - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_1 - type - text - HtmlAttributeValueStyle.SingleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_2 - unbound - foo - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::FormTagHelper - __FormTagHelper
+            FieldDeclaration -  - private - global::InputTagHelper - __InputTagHelper
             MethodDeclaration -  - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(31, 28, true);
@@ -32,7 +34,7 @@ Document -
                 CSharpCode - 
                     IntermediateToken -  - CSharp - BeginContext(71, 87, false);
                 TagHelper - (71:3,0 [87] BasicTest.cshtml) - form - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(91, 6, true);
                         HtmlContent - (91:3,20 [6] BasicTest.cshtml)
@@ -42,13 +44,14 @@ Document -
                         CSharpCode - 
                             IntermediateToken -  - CSharp - BeginContext(97, 52, false);
                         TagHelper - (97:4,4 [52] BasicTest.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - InputTagHelper
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_0 - value - FooProp
-                            SetTagHelperProperty - (121:4,28 [13] BasicTest.cshtml) - date - BarProp - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - InputTagHelper
+                            PreallocatedTagHelperProperty - (110:4,17 [5] BasicTest.cshtml) - __tagHelperAttribute_0 - value - FooProp
+                            DefaultTagHelperProperty - (121:4,28 [13] BasicTest.cshtml) - date - System.DateTime InputTagHelper.BarProp - HtmlAttributeValueStyle.DoubleQuotes
                                 CSharpExpression - (122:4,29 [12] BasicTest.cshtml)
                                     IntermediateToken - (122:4,29 [12] BasicTest.cshtml) - CSharp - DateTime.Now
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                            DefaultTagHelperExecute - 
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
                         CSharpCode - 
@@ -57,8 +60,9 @@ Document -
                             IntermediateToken - (149:4,56 [2] BasicTest.cshtml) - Html - \n
                         CSharpCode - 
                             IntermediateToken -  - CSharp - EndContext();
-                    CreateTagHelper -  - FormTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - FormTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 
                 CSharpCode - 
                     IntermediateToken -  - CSharp - EndContext();
                 CSharpCode - 

test/Microsoft.AspNetCore.Mvc.Razor.Extensions.Test/ViewComponentTagHelperPassTest.cs

@@ -1,10 +1,11 @@
 // 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.Linq;
 using System.Text;
 using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
-using Microsoft.CodeAnalysis.Razor;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
@@ -22,6 +23,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             var tagHelpers = new[]
             {
                 TagHelperDescriptorBuilder.Create("TestTagHelper", "TestAssembly")
+                    .TypeName("TestTagHelper")
                     .BoundAttributeDescriptor(attribute => attribute
                         .Name("Foo")
                         .TypeName("System.Int32"))
@@ -42,7 +44,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
             // Assert
             var @class = FindClassNode(irDocument);
-            Assert.Equal(2, @class.Children.Count); // No class node created for a VCTH
+            Assert.Equal(3, @class.Children.Count); // No class node created for a VCTH
             for (var i = 0; i < @class.Children.Count; i++)
             {
                 Assert.IsNotType<CSharpCodeIntermediateNode>(@class.Children[i]);
@@ -60,6 +62,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
             var tagHelpers = new[]
             {
                 TagHelperDescriptorBuilder.Create(ViewComponentTagHelperConventions.Kind, "TestTagHelper", "TestAssembly")
+                    .TypeName("__Generated__TagCloudViewComponentTagHelper")
                     .BoundAttributeDescriptor(attribute => attribute
                         .Name("Foo")
                         .TypeName("System.Int32")
@@ -77,21 +80,21 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Extensions
 
             var irDocument = CreateIRDocument(engine, codeDocument);
 
-            var expectedVCTHName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
+            var vcthFullName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
 
             // Act
             pass.Execute(codeDocument, irDocument);
 
             // Assert
             var tagHelper = FindTagHelperNode(irDocument);
-            Assert.Equal(expectedVCTHName, Assert.IsType<CreateTagHelperIntermediateNode>(tagHelper.Children[1]).TagHelperTypeName);
-            Assert.Equal(expectedVCTHName, Assert.IsType<SetTagHelperPropertyIntermediateNode>(tagHelper.Children[2]).TagHelperTypeName);
+            Assert.Equal(vcthFullName, Assert.IsType<DefaultTagHelperCreateIntermediateNode>(tagHelper.Children[1]).Type);
+            Assert.Equal("Foo", Assert.IsType<DefaultTagHelperPropertyIntermediateNode>(tagHelper.Children[2]).Property);
 
 
             var @class = FindClassNode(irDocument);
-            Assert.Equal(3, @class.Children.Count);
+            Assert.Equal(4, @class.Children.Count);
 
-            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children[2]);
+            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children.Last());
             var tokenNode = vcthClass.Children[0] as IntermediateToken;
             Assert.Equal(
                 @"[Microsoft.AspNetCore.Razor.TagHelpers.HtmlTargetElementAttribute(""tagcloud"")]
@@ -130,6 +133,7 @@ public class __Generated__TagCloudViewComponentTagHelper : Microsoft.AspNetCore.
             var tagHelpers = new[]
             {
                 TagHelperDescriptorBuilder.Create(ViewComponentTagHelperConventions.Kind, "TestTagHelper", "TestAssembly")
+                    .TypeName("__Generated__TagCloudViewComponentTagHelper")
                     .BoundAttributeDescriptor(attribute => attribute
                         .Name("Foo")
                         .TypeName("System.Collections.Generic.Dictionary<System.String, System.Int32>")
@@ -148,20 +152,20 @@ public class __Generated__TagCloudViewComponentTagHelper : Microsoft.AspNetCore.
 
             var irDocument = CreateIRDocument(engine, codeDocument);
 
-            var expectedVCTHName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
+            var vcthFullName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
 
             // Act
             pass.Execute(codeDocument, irDocument);
 
             // Assert
             var tagHelper = FindTagHelperNode(irDocument);
-            Assert.Equal(expectedVCTHName, Assert.IsType<CreateTagHelperIntermediateNode>(tagHelper.Children[1]).TagHelperTypeName);
-            Assert.IsType<AddTagHelperHtmlAttributeIntermediateNode>(tagHelper.Children[2]);
+            Assert.Equal(vcthFullName, Assert.IsType<DefaultTagHelperCreateIntermediateNode>(tagHelper.Children[1]).Type);
+            Assert.IsType<DefaultTagHelperHtmlAttributeIntermediateNode>(tagHelper.Children[2]);
 
             var @class = FindClassNode(irDocument);
-            Assert.Equal(3, @class.Children.Count);
+            Assert.Equal(4, @class.Children.Count);
 
-            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children[2]);
+            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children[3]);
             var tokenNode = vcthClass.Children[0] as IntermediateToken;
             Assert.Equal(
                 @"[Microsoft.AspNetCore.Razor.TagHelpers.HtmlTargetElementAttribute(""tagcloud"")]
@@ -202,18 +206,18 @@ public class __Generated__TagCloudViewComponentTagHelper : Microsoft.AspNetCore.
             {
                 TagHelperDescriptorBuilder.Create("PTestTagHelper", "TestAssembly")
                     .TypeName("PTestTagHelper")
-                    .BoundAttributeDescriptor(attribute =>
-                        attribute
-                            .Name("Foo")
-                            .TypeName("System.Int32"))
-                    .TagMatchingRuleDescriptor(rule =>
-                        rule.RequireTagName("p"))
+                    .BoundAttributeDescriptor(attribute => attribute
+                        .PropertyName("Foo")
+                        .Name("Foo")
+                        .TypeName("System.Int32"))
+                    .TagMatchingRuleDescriptor(rule => rule.RequireTagName("p"))
                     .Build(),
                 TagHelperDescriptorBuilder.Create(ViewComponentTagHelperConventions.Kind, "TestTagHelper", "TestAssembly")
+                    .TypeName("__Generated__TagCloudViewComponentTagHelper")
                     .BoundAttributeDescriptor(attribute => attribute
+                        .PropertyName("Foo")
                         .Name("Foo")
-                        .TypeName("System.Int32")
-                        .PropertyName("Foo"))
+                        .TypeName("System.Int32"))
                     .TagMatchingRuleDescriptor(rule => rule.RequireTagName("tagcloud"))
                     .AddMetadata(ViewComponentTagHelperMetadata.Name, "TagCloud")
                     .Build()
@@ -226,27 +230,26 @@ public class __Generated__TagCloudViewComponentTagHelper : Microsoft.AspNetCore.
             };
 
             var irDocument = CreateIRDocument(engine, codeDocument);
-
-            var expectedTagHelperName = "PTestTagHelper";
-            var expectedVCTHName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
+            
+            var vcthFullName = "AspNetCore.test_cshtml.__Generated__TagCloudViewComponentTagHelper";
 
             // Act
             pass.Execute(codeDocument, irDocument);
 
             // Assert
             var outerTagHelper = FindTagHelperNode(irDocument);
-            Assert.Equal(expectedTagHelperName, Assert.IsType<CreateTagHelperIntermediateNode>(outerTagHelper.Children[1]).TagHelperTypeName);
-            Assert.Equal(expectedTagHelperName, Assert.IsType<SetTagHelperPropertyIntermediateNode>(outerTagHelper.Children[2]).TagHelperTypeName);
+            Assert.Equal("PTestTagHelper", Assert.IsType<DefaultTagHelperCreateIntermediateNode>(outerTagHelper.Children[1]).Type);
+            Assert.Equal("Foo", Assert.IsType<DefaultTagHelperPropertyIntermediateNode>(outerTagHelper.Children[2]).Property);
 
             var vcth = FindTagHelperNode(outerTagHelper.Children[0]);
-            Assert.Equal(expectedVCTHName, Assert.IsType<CreateTagHelperIntermediateNode>(vcth.Children[1]).TagHelperTypeName);
-            Assert.Equal(expectedVCTHName, Assert.IsType<SetTagHelperPropertyIntermediateNode>(vcth.Children[2]).TagHelperTypeName);
+            Assert.Equal(vcthFullName, Assert.IsType<DefaultTagHelperCreateIntermediateNode>(vcth.Children[1]).Type);
+            Assert.Equal("Foo", Assert.IsType<DefaultTagHelperPropertyIntermediateNode>(vcth.Children[2]).Property);
 
 
             var @class = FindClassNode(irDocument);
-            Assert.Equal(3, @class.Children.Count);
+            Assert.Equal(5, @class.Children.Count);
 
-            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children[2]);
+            var vcthClass = Assert.IsType<CSharpCodeIntermediateNode>(@class.Children.Last());
             var tokenNode = vcthClass.Children[0] as IntermediateToken;
             Assert.Equal(
                 @"[Microsoft.AspNetCore.Razor.TagHelpers.HtmlTargetElementAttribute(""tagcloud"")]
@@ -303,6 +306,12 @@ public class __Generated__TagCloudViewComponentTagHelper : Microsoft.AspNetCore.
                 }
             }
 
+            // We also expect the default tag helper pass to run first.
+            var documentNode = codeDocument.GetDocumentIntermediateNode();
+
+            var defaultTagHelperPass = engine.Features.OfType<DefaultTagHelperOptimizationPass>().Single();
+            defaultTagHelperPass.Execute(codeDocument, documentNode);
+
             return codeDocument.GetDocumentIntermediateNode();
         }
 

test/Microsoft.AspNetCore.Razor.Language.Test/CodeGeneration/DesignTimeTagHelperWriterTest.cs

@@ -1,264 +0,0 @@
-// 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;
-using System.Collections.Generic;
-using System.Linq;
-using Microsoft.AspNetCore.Razor.Language.Intermediate;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
-{
-    public class DesignTimeTagHelperWriterTest
-    {
-        [Fact]
-        public void WriteDeclareTagHelperFields_DeclaresUsedTagHelperTypes()
-        {
-            // Arrange
-            var writer = new DesignTimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-            var node = new DeclareTagHelperFieldsIntermediateNode();
-            node.UsedTagHelperTypeNames.Add("PTagHelper");
-            node.UsedTagHelperTypeNames.Add("MyTagHelper");
-
-            // Act
-            writer.WriteDeclareTagHelperFields(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"private global::PTagHelper __PTagHelper = null;
-private global::MyTagHelper __MyTagHelper = null;
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteCreateTagHelper_RendersCorrectly_UsesSpecifiedTagHelperType()
-        {
-            // Arrange
-            var writer = new DesignTimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-            var node = new CreateTagHelperIntermediateNode()
-            {
-                TagHelperTypeName = "TestNamespace.MyTagHelper"
-            };
-
-            // Act
-            writer.WriteCreateTagHelper(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"__TestNamespace_MyTagHelper = CreateTagHelper<global::TestNamespace.MyTagHelper>();
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.String"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input bound=""value"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new DesignTimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"Render Children
-__InputTagHelper.FooProp = ""value"";
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_NonStringAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.Int32"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input bound=""42"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new DesignTimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"#line 3 ""test.cshtml""
-__InputTagHelper.FooProp = 42;
-
-#line default
-#line hidden
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_IndexerAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.Collections.Generic.Dictionary<System.String, System.Int32>")
-                            .AsDictionaryAttribute("foo-", "System.Int32"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input foo-bound=""42"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new DesignTimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"#line 3 ""test.cshtml""
-__InputTagHelper.FooProp[""bound""] = 42;
-
-#line default
-#line hidden
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        private static CodeRenderingContext GetCodeRenderingContext(TagHelperWriter writer, RazorCodeDocument codeDocument = null)
-        {
-            var options = RazorCodeGenerationOptions.CreateDefault();
-            var codeWriter = new CodeWriter();
-            var nodeWriter = new DesignTimeNodeWriter();
-            var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, codeDocument?.Source,  options)
-            {
-                TagHelperWriter = writer,
-                TagHelperRenderingContext = new TagHelperRenderingContext()
-            };
-            context.SetRenderChildren(n =>
-            {
-                codeWriter.WriteLine("Render Children");
-            });
-
-            return context;
-        }
-
-        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument)
-        {
-            var engine = RazorEngine.Create();
-
-            return Lower(codeDocument, engine);
-        }
-
-        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument, RazorEngine engine)
-        {
-            for (var i = 0; i < engine.Phases.Count; i++)
-            {
-                var phase = engine.Phases[i];
-                phase.Execute(codeDocument);
-
-                if (phase is IRazorIntermediateNodeLoweringPhase)
-                {
-                    break;
-                }
-            }
-
-            var irDocument = codeDocument.GetDocumentIntermediateNode();
-            Assert.NotNull(irDocument);
-
-            return irDocument;
-        }
-
-        private static TagHelperDescriptor CreateTagHelperDescriptor(
-            string tagName,
-            string typeName,
-            string assemblyName,
-            IEnumerable<Action<BoundAttributeDescriptorBuilder>> attributes = null)
-        {
-            var builder = TagHelperDescriptorBuilder.Create(typeName, assemblyName);
-            builder.TypeName(typeName);
-
-            if (attributes != null)
-            {
-                foreach (var attributeBuilder in attributes)
-                {
-                    builder.BoundAttributeDescriptor(attributeBuilder);
-                }
-            }
-
-            builder.TagMatchingRuleDescriptor(ruleBuilder => ruleBuilder.RequireTagName(tagName));
-
-            var descriptor = builder.Build();
-
-            return descriptor;
-        }
-    }
-}

test/Microsoft.AspNetCore.Razor.Language.Test/CodeGeneration/RuntimeTagHelperWriterTest.cs

@@ -1,501 +0,0 @@
-// 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;
-using System.Collections.Generic;
-using System.Linq;
-using Microsoft.AspNetCore.Razor.Language.Intermediate;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
-{
-    public class RuntimeTagHelperWriterTest
-    {
-        [Fact]
-        public void WriteDeclareTagHelperFields_DeclaresRequiredFields()
-        {
-            // Arrange
-            var node = new DeclareTagHelperFieldsIntermediateNode();
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-
-            // Act
-            writer.WriteDeclareTagHelperFields(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"#line hidden
-#pragma warning disable 0414
-private string __tagHelperStringValueBuffer = null;
-#pragma warning restore 0414
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
-{
-    get
-    {
-        if (__backed__tagHelperScopeManager == null)
-        {
-            __backed__tagHelperScopeManager = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager(StartTagHelperWritingScope, EndTagHelperWritingScope);
-        }
-        return __backed__tagHelperScopeManager;
-    }
-}
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteDeclareTagHelperFields_DeclaresUsedTagHelperTypes()
-        {
-            // Arrange
-            var node = new DeclareTagHelperFieldsIntermediateNode();
-            node.UsedTagHelperTypeNames.Add("PTagHelper");
-            node.UsedTagHelperTypeNames.Add("MyTagHelper");
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-
-            // Act
-            writer.WriteDeclareTagHelperFields(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"#line hidden
-#pragma warning disable 0414
-private string __tagHelperStringValueBuffer = null;
-#pragma warning restore 0414
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
-private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
-{
-    get
-    {
-        if (__backed__tagHelperScopeManager == null)
-        {
-            __backed__tagHelperScopeManager = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager(StartTagHelperWritingScope, EndTagHelperWritingScope);
-        }
-        return __backed__tagHelperScopeManager;
-    }
-}
-private global::PTagHelper __PTagHelper = null;
-private global::MyTagHelper __MyTagHelper = null;
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteTagHelperBody_RendersCorrectly_UsesTagNameAndModeFromContext()
-        {
-            // Arrange
-            var node = new TagHelperBodyIntermediateNode();
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-            context.Items[CodeRenderingContext.SuppressUniqueIds] = "test";
-            context.TagHelperRenderingContext = new TagHelperRenderingContext()
-            {
-                TagName = "p",
-                TagMode = TagMode.SelfClosing
-            };
-
-            // Act
-            writer.WriteTagHelperBody(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"__tagHelperExecutionContext = __tagHelperScopeManager.Begin(""p"", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.SelfClosing, ""test"", async() => {
-    Render Children
-}
-);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteCreateTagHelper_RendersCorrectly_UsesSpecifiedTagHelperType()
-        {
-            // Arrange
-            var node = new CreateTagHelperIntermediateNode()
-            {
-                TagHelperTypeName = "TestNamespace.MyTagHelper"
-            };
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-
-            // Act
-            writer.WriteCreateTagHelper(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"__TestNamespace_MyTagHelper = CreateTagHelper<global::TestNamespace.MyTagHelper>();
-__tagHelperExecutionContext.Add(__TestNamespace_MyTagHelper);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteTagHelper_RendersCorrectly_SetsTagNameAndModeInContext()
-        {
-            // Arrange
-            var node = new TagHelperIntermediateNode();
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer);
-
-            // Act
-            writer.WriteTagHelper(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"Render Children
-await __tagHelperRunner.RunAsync(__tagHelperExecutionContext);
-if (!__tagHelperExecutionContext.Output.IsContentModified)
-{
-    await __tagHelperExecutionContext.SetOutputContentAsync();
-}
-Write(__tagHelperExecutionContext.Output);
-__tagHelperExecutionContext = __tagHelperScopeManager.End();
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteAddTagHelperHtmlAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly")
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input name=""value"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as AddTagHelperHtmlAttributeIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteAddTagHelperHtmlAttribute(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"BeginWriteTagHelperAttribute();
-Render Children
-__tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
-__tagHelperExecutionContext.AddHtmlAttribute(""name"", Html.Raw(__tagHelperStringValueBuffer), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteAddTagHelperHtmlAttribute_DataAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly")
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input data-test=""Blah-@Foo"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as AddTagHelperHtmlAttributeIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteAddTagHelperHtmlAttribute(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"BeginWriteTagHelperAttribute();
-Render Children
-__tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
-__tagHelperExecutionContext.AddHtmlAttribute(""data-test"", Html.Raw(__tagHelperStringValueBuffer), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteAddTagHelperHtmlAttribute_DynamicAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly")
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input test=""Blah-@Foo"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as AddTagHelperHtmlAttributeIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteAddTagHelperHtmlAttribute(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"BeginAddHtmlAttributeValues(__tagHelperExecutionContext, ""test"", 2, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-Render Children
-EndAddHtmlAttributeValues(__tagHelperExecutionContext);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.String"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input bound=""value"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-
-            // The attribute value is not rendered inline because we are not using the preallocated writer.
-            Assert.Equal(
-@"BeginWriteTagHelperAttribute();
-Render Children
-__tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
-__InputTagHelper.FooProp = __tagHelperStringValueBuffer;
-__tagHelperExecutionContext.AddTagHelperAttribute(""bound"", __InputTagHelper.FooProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_NonStringAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.Int32"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input bound=""42"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"#line 3 ""test.cshtml""
-__InputTagHelper.FooProp = 42;
-
-#line default
-#line hidden
-__tagHelperExecutionContext.AddTagHelperAttribute(""bound"", __InputTagHelper.FooProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        [Fact]
-        public void WriteSetTagHelperProperty_IndexerAttribute_RendersCorrectly()
-        {
-            // Arrange
-            var descriptors = new[]
-            {
-                CreateTagHelperDescriptor(
-                    tagName: "input",
-                    typeName: "InputTagHelper",
-                    assemblyName: "TestAssembly",
-                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                    {
-                        builder => builder
-                            .Name("bound")
-                            .PropertyName("FooProp")
-                            .TypeName("System.Collections.Generic.Dictionary<System.String, System.Int32>")
-                            .AsDictionaryAttribute("foo-", "System.Int32"),
-                    })
-            };
-            var engine = RazorEngine.Create(builder => builder.AddTagHelpers(descriptors));
-            var content = @"
-@addTagHelper *, TestAssembly
-<input foo-bound=""42"" />";
-            var sourceDocument = TestRazorSourceDocument.Create(content);
-            var codeDocument = RazorCodeDocument.Create(sourceDocument);
-            var irDocument = Lower(codeDocument, engine);
-            var node = irDocument.Children.Last().Children[2] as SetTagHelperPropertyIntermediateNode;
-
-            var writer = new RuntimeTagHelperWriter();
-            var context = GetCodeRenderingContext(writer, codeDocument);
-
-            // Act
-            writer.WriteSetTagHelperProperty(context, node);
-
-            // Assert
-            var csharp = context.CodeWriter.Builder.ToString();
-            Assert.Equal(
-@"if (__InputTagHelper.FooProp == null)
-{
-    throw new InvalidOperationException(InvalidTagHelperIndexerAssignment(""foo-bound"", ""InputTagHelper"", ""FooProp""));
-}
-#line 3 ""test.cshtml""
-__InputTagHelper.FooProp[""bound""] = 42;
-
-#line default
-#line hidden
-__tagHelperExecutionContext.AddTagHelperAttribute(""foo-bound"", __InputTagHelper.FooProp[""bound""], global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
-",
-                csharp,
-                ignoreLineEndingDifferences: true);
-        }
-
-        private static CodeRenderingContext GetCodeRenderingContext(TagHelperWriter writer, RazorCodeDocument codeDocument = null)
-        {
-            var codeWriter = new CodeWriter();
-            var nodeWriter = new RuntimeNodeWriter();
-            var options = RazorCodeGenerationOptions.CreateDefault();
-            var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, codeDocument?.Source, options)
-            {
-                TagHelperWriter = writer,
-                TagHelperRenderingContext = new TagHelperRenderingContext()
-            };
-            context.SetRenderChildren(n =>
-            {
-                codeWriter.WriteLine("Render Children");
-            });
-
-            return context;
-        }
-
-        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument)
-        {
-            var engine = RazorEngine.Create();
-
-            return Lower(codeDocument, engine);
-        }
-
-        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument, RazorEngine engine)
-        {
-            for (var i = 0; i < engine.Phases.Count; i++)
-            {
-                var phase = engine.Phases[i];
-                phase.Execute(codeDocument);
-
-                if (phase is IRazorIntermediateNodeLoweringPhase)
-                {
-                    break;
-                }
-            }
-
-            var irDocument = codeDocument.GetDocumentIntermediateNode();
-            Assert.NotNull(irDocument);
-
-            return irDocument;
-        }
-
-        private static TagHelperDescriptor CreateTagHelperDescriptor(
-            string tagName,
-            string typeName,
-            string assemblyName,
-            IEnumerable<Action<BoundAttributeDescriptorBuilder>> attributes = null)
-        {
-            var builder = TagHelperDescriptorBuilder.Create(typeName, assemblyName);
-            builder.TypeName(typeName);
-
-            if (attributes != null)
-            {
-                foreach (var attributeBuilder in attributes)
-                {
-                    builder.BoundAttributeDescriptor(attributeBuilder);
-                }
-            }
-
-            builder.TagMatchingRuleDescriptor(ruleBuilder => ruleBuilder.RequireTagName(tagName));
-
-            var descriptor = builder.Build();
-
-            return descriptor;
-        }
-    }
-}

test/Microsoft.AspNetCore.Razor.Language.Test/DefaultRazorIntermediateNodeLoweringPhaseIntegrationTest.cs

@@ -198,14 +198,12 @@ namespace Microsoft.AspNetCore.Razor.Language
                     SyntaxConstants.CSharp.AddTagHelperKeyword,
                     n,
                     v => DirectiveToken(DirectiveTokenKind.String, "*, TestAssembly", v)),
-                n => TagHelperFieldDeclaration(n, "SpanTagHelper"),
                 n => TagHelper(
                     "span",
                     TagMode.StartTagAndEndTag,
                     tagHelpers,
                     n,
                     c => Assert.IsType<TagHelperBodyIntermediateNode>(c),
-                    c => Assert.IsType<CreateTagHelperIntermediateNode>(c),
                     c => TagHelperHtmlAttribute(
                         "val",
                         AttributeStructure.DoubleQuotes,
@@ -242,14 +240,12 @@ namespace Microsoft.AspNetCore.Razor.Language
                     SyntaxConstants.CSharp.TagHelperPrefixKeyword,
                     n,
                     v => DirectiveToken(DirectiveTokenKind.String, "cool:", v)),
-                n => TagHelperFieldDeclaration(n, "SpanTagHelper"),
                 n => TagHelper(
                     "span",  // Note: this is span not cool:span
                     TagMode.StartTagAndEndTag,
                     tagHelpers,
                     n,
                     c => Assert.IsType<TagHelperBodyIntermediateNode>(c),
-                    c => Assert.IsType<CreateTagHelperIntermediateNode>(c),
                     c => TagHelperHtmlAttribute(
                         "val",
                         AttributeStructure.DoubleQuotes,
@@ -272,7 +268,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                             tagName: "span",
                             typeName: "SpanTagHelper",
                             assemblyName: "TestAssembly")
-                    };
+            };
 
             // Act
             var documentNode = Lower(codeDocument, tagHelpers: tagHelpers);
@@ -295,15 +291,13 @@ namespace Microsoft.AspNetCore.Razor.Language
                         tagHelpers,
                         c1,
                         c2 => Assert.IsType<TagHelperBodyIntermediateNode>(c2),
-                        c2 => Assert.IsType<CreateTagHelperIntermediateNode>(c2),
                         c2 => TagHelperHtmlAttribute(
                             "val",
                             AttributeStructure.DoubleQuotes,
                             c2,
                             v => CSharpExpressionAttributeValue(string.Empty, "Hello", v),
                             v => LiteralAttributeValue(" ", "World", v))),
-                    c1 => Html(Environment.NewLine, c1)),
-                n => TagHelperFieldDeclaration(n, "SpanTagHelper"));
+                    c1 => Html(Environment.NewLine, c1)));
         }
 
         [Fact]
@@ -314,18 +308,18 @@ namespace Microsoft.AspNetCore.Razor.Language
 <input bound='foo' />");
             var tagHelpers = new[]
             {
-                        CreateTagHelperDescriptor(
-                            tagName: "input",
-                            typeName: "InputTagHelper",
-                            assemblyName: "TestAssembly",
-                            attributes: new Action<BoundAttributeDescriptorBuilder>[]
-                            {
-                                builder => builder
-                                    .Name("bound")
-                                    .PropertyName("FooProp")
-                                    .TypeName("System.String"),
+                CreateTagHelperDescriptor(
+                    tagName: "input",
+                    typeName: "InputTagHelper",
+                    assemblyName: "TestAssembly",
+                    attributes: new Action<BoundAttributeDescriptorBuilder>[]
+                    {
+                        builder => builder
+                            .Name("bound")
+                            .PropertyName("FooProp")
+                            .TypeName("System.String"),
                             })
-                    };
+            };
 
             // Act
             var documentNode = Lower(codeDocument, tagHelpers: tagHelpers);
@@ -337,14 +331,12 @@ namespace Microsoft.AspNetCore.Razor.Language
                     SyntaxConstants.CSharp.AddTagHelperKeyword,
                     n,
                     v => DirectiveToken(DirectiveTokenKind.String, "*, TestAssembly", v)),
-                n => TagHelperFieldDeclaration(n, "InputTagHelper"),
                 n => TagHelper(
                     "input",
                     TagMode.SelfClosing,
                     tagHelpers,
                     n,
                     c => Assert.IsType<TagHelperBodyIntermediateNode>(c),
-                    c => Assert.IsType<CreateTagHelperIntermediateNode>(c),
                     c => SetTagHelperProperty(
                         "bound",
                         "FooProp",

test/Microsoft.AspNetCore.Razor.Language.Test/DocumentClassifierPassBaseTest.cs

@@ -143,33 +143,6 @@ namespace Microsoft.AspNetCore.Razor.Language
                 n => Assert.IsType<ClassDeclarationIntermediateNode>(n));
         }
 
-        [Fact]
-        public void Execute_AddsTagHelperFieldsToClass()
-        {
-            // Arrange
-            var documentNode = new DocumentIntermediateNode()
-            {
-                Options = RazorCodeGenerationOptions.CreateDefault(),
-            };
-
-            var builder = IntermediateNodeBuilder.Create(documentNode);
-            builder.Add(new DeclareTagHelperFieldsIntermediateNode());
-
-            var pass = new TestDocumentClassifierPass();
-            pass.Engine = RazorEngine.CreateEmpty(b => { });
-
-            // Act
-            pass.Execute(TestRazorCodeDocument.CreateEmpty(), documentNode);
-
-            // Assert
-            var @namespace = SingleChild<NamespaceDeclarationIntermediateNode>(documentNode);
-            var @class = SingleChild<ClassDeclarationIntermediateNode>(@namespace);
-            Children(
-                @class,
-                n => Assert.IsType<DeclareTagHelperFieldsIntermediateNode>(n),
-                n => Assert.IsType<MethodDeclarationIntermediateNode>(n));
-        }
-
         [Fact]
         public void Execute_AddsTheRestToMethod()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/Extensions/DefaultTagHelperTargetExtensionTest.cs

@@ -0,0 +1,926 @@
+// 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;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
+using Microsoft.AspNetCore.Razor.Language.Intermediate;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Razor.Language.Extensions
+{
+    public class DefaultTagHelperTargetExtensionTest
+    {
+        private static readonly TagHelperDescriptor StringPropertyTagHelper = CreateTagHelperDescriptor(
+            tagName: "input",
+            typeName: "InputTagHelper",
+            assemblyName: "TestAssembly",
+            attributes: new Action<BoundAttributeDescriptorBuilder>[]
+            {
+                builder => builder
+                    .Name("bound")
+                    .PropertyName("StringProp")
+                    .TypeName("System.String"),
+            });
+
+        private static readonly TagHelperDescriptor IntPropertyTagHelper = CreateTagHelperDescriptor(
+            tagName: "input",
+            typeName: "InputTagHelper",
+            assemblyName: "TestAssembly",
+            attributes: new Action<BoundAttributeDescriptorBuilder>[]
+            {
+                builder => builder
+                    .Name("bound")
+                    .PropertyName("IntProp")
+                    .TypeName("System.Int32"),
+            });
+
+        private static readonly TagHelperDescriptor StringIndexerTagHelper = CreateTagHelperDescriptor(
+            tagName: "input",
+            typeName: "InputTagHelper",
+            assemblyName: "TestAssembly",
+            attributes: new Action<BoundAttributeDescriptorBuilder>[]
+            {
+                builder => builder
+                    .Name("bound")
+                    .PropertyName("StringIndexer")
+                    .TypeName("System.Collections.Generic.Dictionary<System.String, System.String>")
+                    .AsDictionary("foo-", "System.String"),
+            });
+
+        private static readonly TagHelperDescriptor IntIndexerTagHelper = CreateTagHelperDescriptor(
+            tagName: "input",
+            typeName: "InputTagHelper",
+            assemblyName: "TestAssembly",
+            attributes: new Action<BoundAttributeDescriptorBuilder>[]
+            {
+                builder => builder
+                    .Name("bound")
+                    .PropertyName("IntIndexer")
+                    .TypeName("System.Collections.Generic.Dictionary<System.String, System.Int32>")
+                    .AsDictionary("foo-", "System.Int32"),
+            });
+
+        private static readonly SourceSpan Span = new SourceSpan("test.cshtml", 15, 2, 5, 2);
+
+        [Fact]
+        public void WriteTagHelperBody_DesignTime_WritesChildren()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperBodyIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperBody(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"Render Children
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperBody_Runtime_RendersCorrectly_UsesTagNameAndModeFromContext()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            context.TagHelperRenderingContext.TagMode = TagMode.SelfClosing;
+            context.TagHelperRenderingContext.TagName = "p";
+
+            var node = new DefaultTagHelperBodyIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperBody(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__tagHelperExecutionContext = __tagHelperScopeManager.Begin(""p"", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.SelfClosing, ""test"", async() => {
+    Render Children
+}
+);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperCreate_DesignTime_RendersCorrectly_UsesSpecifiedTagHelperType()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperCreateIntermediateNode()
+            {
+                Field = "__TestNamespace_MyTagHelper",
+                Type = "TestNamespace.MyTagHelper",
+            };
+
+            // Act
+            extension.WriteTagHelperCreate(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__TestNamespace_MyTagHelper = CreateTagHelper<global::TestNamespace.MyTagHelper>();
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperCreate_Runtime_RendersCorrectly_UsesSpecifiedTagHelperType()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperCreateIntermediateNode()
+            {
+                Field = "__TestNamespace_MyTagHelper",
+                Type = "TestNamespace.MyTagHelper",
+            };
+
+            // Act
+            extension.WriteTagHelperCreate(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__TestNamespace_MyTagHelper = CreateTagHelper<global::TestNamespace.MyTagHelper>();
+__tagHelperExecutionContext.Add(__TestNamespace_MyTagHelper);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperExecute_DesignTime_WritesNothing()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperExecuteIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperExecute(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+                @"",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperExecute_Runtime_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperExecuteIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperExecute(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"await __tagHelperRunner.RunAsync(__tagHelperExecutionContext);
+if (!__tagHelperExecutionContext.Output.IsContentModified)
+{
+    await __tagHelperExecutionContext.SetOutputContentAsync();
+}
+Write(__tagHelperExecutionContext.Output);
+__tagHelperExecutionContext = __tagHelperScopeManager.End();
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperHtmlAttribute_DesignTime_WritesNothing()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperHtmlAttributeIntermediateNode()
+            {
+                AttributeName = "name",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                Children =
+                {
+                    new HtmlAttributeValueIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.Html, Content = "Blah-" } }
+                    },
+                    new CSharpCodeAttributeValueIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "\"Foo\"", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperHtmlAttribute(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"Render Children
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperHtmlAttribute_Runtime_SimpleAttribute_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperHtmlAttributeIntermediateNode()
+            {
+                AttributeName = "name",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                Children =
+                {
+                    new HtmlAttributeIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.Html, Content = "\"value\"", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperHtmlAttribute(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"BeginWriteTagHelperAttribute();
+Render Children
+__tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
+__tagHelperExecutionContext.AddHtmlAttribute(""name"", Html.Raw(__tagHelperStringValueBuffer), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperHtmlAttribute_Runtime_DynamicAttribute_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperHtmlAttributeIntermediateNode()
+            {
+                AttributeName = "name",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                Children =
+                {
+                    new HtmlAttributeValueIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.Html, Content = "Blah-" } }
+                    },
+                    new CSharpCodeAttributeValueIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "\"Foo\"", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperHtmlAttribute(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"BeginAddHtmlAttributeValues(__tagHelperExecutionContext, ""name"", 2, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+Render Children
+EndAddHtmlAttributeValues(__tagHelperExecutionContext);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_DesignTime_StringProperty_HtmlContent_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = StringPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "StringProp",
+                TagHelper = StringPropertyTagHelper,
+                Children =
+                {
+                    new HtmlContentIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.Html, Content = "value", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"Render Children
+__InputTagHelper.StringProp = ""value"";
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact] // We don't actually assign the expression result at design time, we just use string.Empty as a placeholder.
+        public void WriteTagHelperProperty_DesignTime_StringProperty_NonHtmlContent_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = StringPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "StringProp",
+                TagHelper = StringPropertyTagHelper,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "\"3+5\"", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"Render Children
+__InputTagHelper.StringProp = string.Empty;
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_DesignTime_NonStringProperty_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "IntProp",
+                TagHelper = IntPropertyTagHelper,
+                Source = Span,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"#line 3 ""test.cshtml""
+__InputTagHelper.IntProp = 32;
+
+#line default
+#line hidden
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_DesignTime_NonStringProperty_RendersCorrectly_WithoutLocation()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "IntProp",
+                TagHelper = IntPropertyTagHelper,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__InputTagHelper.IntProp = 32;
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_DesignTime_NonStringIndexer_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "foo-bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntIndexerTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = true,
+                Property = "IntIndexer",
+                TagHelper = IntIndexerTagHelper,
+                Source = Span,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"#line 3 ""test.cshtml""
+__InputTagHelper.IntIndexer[""bound""] = 32;
+
+#line default
+#line hidden
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_DesignTime_NonStringIndexer_RendersCorrectly_WithoutLocation()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "foo-bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntIndexerTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = true,
+                Property = "IntIndexer",
+                TagHelper = IntIndexerTagHelper,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__InputTagHelper.IntIndexer[""bound""] = 32;
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_Runtime_StringProperty_HtmlContent_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = StringPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "StringProp",
+                TagHelper = StringPropertyTagHelper,
+                Children =
+                {
+                    new HtmlContentIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.Html, Content = "\"value\"", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+
+            // The attribute value is not rendered inline because we are not using the preallocated writer.
+            Assert.Equal(
+@"BeginWriteTagHelperAttribute();
+Render Children
+__tagHelperStringValueBuffer = EndWriteTagHelperAttribute();
+__InputTagHelper.StringProp = __tagHelperStringValueBuffer;
+__tagHelperExecutionContext.AddTagHelperAttribute(""bound"", __InputTagHelper.StringProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_Runtime_NonStringProperty_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "IntProp",
+                TagHelper = IntPropertyTagHelper,
+                Source = Span,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                },
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"#line 3 ""test.cshtml""
+__InputTagHelper.IntProp = 32;
+
+#line default
+#line hidden
+__tagHelperExecutionContext.AddTagHelperAttribute(""bound"", __InputTagHelper.IntProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_Runtime_NonStringProperty_RendersCorrectly_WithoutLocation()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntPropertyTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = false,
+                Property = "IntProp",
+                TagHelper = IntPropertyTagHelper,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"__InputTagHelper.IntProp = 32;
+__tagHelperExecutionContext.AddTagHelperAttribute(""bound"", __InputTagHelper.IntProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_Runtime_NonStringIndexer_RendersCorrectly()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "foo-bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntIndexerTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = true,
+                Property = "IntIndexer",
+                TagHelper = IntIndexerTagHelper,
+                Source = Span,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"if (__InputTagHelper.IntIndexer == null)
+{
+    throw new InvalidOperationException(InvalidTagHelperIndexerAssignment(""foo-bound"", ""InputTagHelper"", ""IntIndexer""));
+}
+#line 3 ""test.cshtml""
+__InputTagHelper.IntIndexer[""bound""] = 32;
+
+#line default
+#line hidden
+__tagHelperExecutionContext.AddTagHelperAttribute(""foo-bound"", __InputTagHelper.IntIndexer[""bound""], global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperProperty_Runtime_NonStringIndexer_RendersCorrectly_WithoutLocation()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperPropertyIntermediateNode()
+            {
+                AttributeName = "foo-bound",
+                AttributeStructure = AttributeStructure.DoubleQuotes,
+                BoundAttribute = IntIndexerTagHelper.BoundAttributes.Single(),
+                Field = "__InputTagHelper",
+                IsIndexerNameMatch = true,
+                Property = "IntIndexer",
+                TagHelper = IntIndexerTagHelper,
+                Children =
+                {
+                    new CSharpExpressionIntermediateNode()
+                    {
+                        Children = { new IntermediateToken { Kind = IntermediateToken.TokenKind.CSharp, Content = "32", } },
+                    }
+                }
+            };
+
+            // Act
+            extension.WriteTagHelperProperty(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"if (__InputTagHelper.IntIndexer == null)
+{
+    throw new InvalidOperationException(InvalidTagHelperIndexerAssignment(""foo-bound"", ""InputTagHelper"", ""IntIndexer""));
+}
+__InputTagHelper.IntIndexer[""bound""] = 32;
+__tagHelperExecutionContext.AddTagHelperAttribute(""foo-bound"", __InputTagHelper.IntIndexer[""bound""], global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperRuntime_DesignTime_WritesNothing()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension() { DesignTime = true };
+            var context = GetDesignTimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperRuntimeIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperRuntime(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+                @"",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        [Fact]
+        public void WriteTagHelperRuntime_Runtime_DeclaresRequiredFields()
+        {
+            // Arrange
+            var extension = new DefaultTagHelperTargetExtension();
+            var context = GetRuntimeCodeRenderingContext();
+
+            var node = new DefaultTagHelperRuntimeIntermediateNode();
+
+            // Act
+            extension.WriteTagHelperRuntime(context, node);
+
+            // Assert
+            var csharp = context.CodeWriter.Builder.ToString();
+            Assert.Equal(
+@"#line hidden
+#pragma warning disable 0414
+private string __tagHelperStringValueBuffer;
+#pragma warning restore 0414
+private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
+private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
+private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
+private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
+{
+    get
+    {
+        if (__backed__tagHelperScopeManager == null)
+        {
+            __backed__tagHelperScopeManager = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager(StartTagHelperWritingScope, EndTagHelperWritingScope);
+        }
+        return __backed__tagHelperScopeManager;
+    }
+}
+",
+                csharp,
+                ignoreLineEndingDifferences: true);
+        }
+
+        private static CodeRenderingContext GetRuntimeCodeRenderingContext()
+        {
+            var codeWriter = new CodeWriter();
+            var nodeWriter = new RuntimeNodeWriter();
+            var options = RazorCodeGenerationOptions.CreateDefault();
+            var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, null, options)
+            {
+                Items =
+                {
+                    { CodeRenderingContext.SuppressUniqueIds, "test" },
+                },
+                TagHelperWriter = new RuntimeTagHelperWriter(),
+                TagHelperRenderingContext = new TagHelperRenderingContext()
+            };
+            context.SetRenderChildren(n =>
+            {
+                codeWriter.WriteLine("Render Children");
+            });
+
+            return context;
+        }
+
+        private static CodeRenderingContext GetDesignTimeCodeRenderingContext()
+        {
+            var codeWriter = new CodeWriter();
+            var nodeWriter = new RuntimeNodeWriter();
+            var options = RazorCodeGenerationOptions.CreateDesignTimeDefault();
+            var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, null, options)
+            {
+                Items =
+                {
+                    { CodeRenderingContext.SuppressUniqueIds, "test" },
+                },
+                TagHelperWriter = new DesignTimeTagHelperWriter(),
+                TagHelperRenderingContext = new TagHelperRenderingContext()
+            };
+            context.SetRenderChildren(n =>
+            {
+                codeWriter.WriteLine("Render Children");
+            });
+
+            return context;
+        }
+
+        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument)
+        {
+            var engine = RazorEngine.Create();
+            return Lower(codeDocument, engine);
+        }
+
+        private static DocumentIntermediateNode LowerDesignTime(RazorCodeDocument codeDocument)
+        {
+            var engine = RazorEngine.CreateDesignTime();
+            return Lower(codeDocument, engine);
+        }
+
+        private static DocumentIntermediateNode Lower(RazorCodeDocument codeDocument, RazorEngine engine)
+        {
+            for (var i = 0; i < engine.Phases.Count; i++)
+            {
+                var phase = engine.Phases[i];
+                phase.Execute(codeDocument);
+
+                if (phase is IRazorIntermediateNodeLoweringPhase)
+                {
+                    break;
+                }
+            }
+
+            var irDocument = codeDocument.GetDocumentIntermediateNode();
+            Assert.NotNull(irDocument);
+
+            return irDocument;
+        }
+
+        private static TagHelperDescriptor CreateTagHelperDescriptor(
+            string tagName,
+            string typeName,
+            string assemblyName,
+            IEnumerable<Action<BoundAttributeDescriptorBuilder>> attributes = null)
+        {
+            var builder = TagHelperDescriptorBuilder.Create(typeName, assemblyName);
+            builder.TypeName(typeName);
+
+            if (attributes != null)
+            {
+                foreach (var attributeBuilder in attributes)
+                {
+                    builder.BindAttribute(attributeBuilder);
+                }
+            }
+
+            builder.TagMatchingRule(ruleBuilder => ruleBuilder.RequireTagName(tagName));
+
+            var descriptor = builder.Build();
+
+            return descriptor;
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Language.Test/Extensions/PreallocatedAttributeTargetExtensionTest.cs

@@ -18,16 +18,16 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             var options = RazorCodeGenerationOptions.CreateDefault();
             var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, sourceDocument: null, options: options);
 
-            var node = new DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode()
+            var node = new PreallocatedTagHelperHtmlAttributeValueIntermediateNode()
             {
-                Name = "Foo",
+                AttributeName = "Foo",
                 Value = "Bar",
                 AttributeStructure = AttributeStructure.DoubleQuotes,
                 VariableName = "MyProp"
             };
 
             // Act
-            extension.WriteDeclarePreallocatedTagHelperHtmlAttribute(context, node);
+            extension.WriteTagHelperHtmlAttributeValue(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();
@@ -48,16 +48,16 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             var options = RazorCodeGenerationOptions.CreateDefault();
             var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, sourceDocument: null, options: options);
 
-            var node = new DeclarePreallocatedTagHelperHtmlAttributeIntermediateNode()
+            var node = new PreallocatedTagHelperHtmlAttributeValueIntermediateNode()
             {
-                Name = "Foo",
+                AttributeName = "Foo",
                 Value = "Bar",
                 AttributeStructure = AttributeStructure.Minimized,
                 VariableName = "_tagHelper1"
             };
 
             // Act
-            extension.WriteDeclarePreallocatedTagHelperHtmlAttribute(context, node);
+            extension.WriteTagHelperHtmlAttributeValue(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();
@@ -78,13 +78,13 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             var options = RazorCodeGenerationOptions.CreateDefault();
             var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, sourceDocument: null, options: options);
 
-            var node = new AddPreallocatedTagHelperHtmlAttributeIntermediateNode()
+            var node = new PreallocatedTagHelperHtmlAttributeIntermediateNode()
             {
                 VariableName = "_tagHelper1"
             };
 
             // Act
-            extension.WriteAddPreallocatedTagHelperHtmlAttribute(context, node);
+            extension.WriteTagHelperHtmlAttribute(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();
@@ -105,16 +105,16 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             var options = RazorCodeGenerationOptions.CreateDefault();
             var context = new DefaultCodeRenderingContext(codeWriter, nodeWriter, sourceDocument: null, options: options);
 
-            var node = new DeclarePreallocatedTagHelperAttributeIntermediateNode()
+            var node = new PreallocatedTagHelperPropertyValueIntermediateNode()
             {
-                Name = "Foo",
+                AttributeName = "Foo",
                 Value = "Bar",
                 AttributeStructure = AttributeStructure.DoubleQuotes,
                 VariableName = "_tagHelper1",
             };
 
             // Act
-            extension.WriteDeclarePreallocatedTagHelperAttribute(context, node);
+            extension.WriteTagHelperPropertyValue(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();
@@ -147,16 +147,16 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
 
             var descriptor = builder.Build();
 
-            var node = new SetPreallocatedTagHelperPropertyIntermediateNode()
+            var node = new PreallocatedTagHelperPropertyIntermediateNode()
             {
                 AttributeName = descriptor.Name,
-                TagHelperTypeName = "FooTagHelper",
+                Field = "__FooTagHelper",
                 VariableName = "_tagHelper1",
-                Descriptor = descriptor,
+                BoundAttribute = descriptor,
             };
 
             // Act
-            extension.WriteSetPreallocatedTagHelperProperty(context, node);
+            extension.WriteTagHelperProperty(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();
@@ -194,17 +194,18 @@ __tagHelperExecutionContext.AddTagHelperAttribute(_tagHelper1);
 
             var descriptor = builder.Build();
 
-            var node = new SetPreallocatedTagHelperPropertyIntermediateNode()
+            var node = new PreallocatedTagHelperPropertyIntermediateNode()
             {
                 AttributeName = "pre-Foo",
-                TagHelperTypeName = "FooTagHelper",
+                Field = "__FooTagHelper",
                 VariableName = "_tagHelper1",
-                Descriptor = descriptor,
-                IsIndexerNameMatch = true
+                BoundAttribute = descriptor,
+                IsIndexerNameMatch = true,
+                TagHelper = tagHelperBuilder.Build(),
             };
 
             // Act
-            extension.WriteSetPreallocatedTagHelperProperty(context, node);
+            extension.WriteTagHelperProperty(context, node);
 
             // Assert
             var csharp = context.CodeWriter.Builder.ToString();

test/Microsoft.AspNetCore.Razor.Language.Test/IntegrationTests/TestTagHelperDescriptors.cs

@@ -406,7 +406,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                             builder => builder
                                 .Name("int-dictionary")
                                 .PropertyName("IntDictionaryProperty")
-                                .TypeName(typeof(IDictionary<string, int>).FullName)
+                                .TypeName("System.Collections.Generic.IDictionary<string, int>")
                                 .AsDictionaryAttribute("int-prefix-", typeof(int).FullName),
                             builder => builder
                                 .Name("string-prefix-grabber")

test/Microsoft.AspNetCore.Razor.Language.Test/Intermediate/ExtensionIntermediateNodeTest.cs

@@ -87,6 +87,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
             {
                 WasSpecificMethodCalled = true;
             }
-        }       
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Language.Test/RazorEngineTest.cs

@@ -22,6 +22,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             Assert.IsType<DefaultRazorEngine>(engine);
             AssertDefaultRuntimeFeatures(engine.Features);
             AssertDefaultRuntimePhases(engine.Phases);
+            AssertDefaultRuntimeTargetExtensions(engine);
         }
 
         [Fact]
@@ -35,6 +36,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             Assert.IsType<DefaultRazorEngine>(engine);
             AssertDefaultDesignTimeFeatures(engine.Features);
             AssertDefaultDesignTimePhases(engine.Phases);
+            AssertDefaultDesignTimeTargetExtensions(engine);
         }
 
         [Fact]
@@ -48,6 +50,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             Assert.IsType<DefaultRazorEngine>(engine);
             AssertDefaultRuntimeFeatures(engine.Features);
             AssertDefaultRuntimePhases(engine.Phases);
+            AssertDefaultRuntimeTargetExtensions(engine);
         }
 
         [Fact]
@@ -61,6 +64,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             Assert.IsType<DefaultRazorEngine>(engine);
             AssertDefaultDesignTimeFeatures(engine.Features);
             AssertDefaultDesignTimePhases(engine.Phases);
+            AssertDefaultDesignTimeTargetExtensions(engine);
         }
 
         [Fact]
@@ -133,12 +137,15 @@ namespace Microsoft.AspNetCore.Razor.Language
                 p => Assert.Same(phases[1], p));
         }
 
-        private static void AssertDefaultTargetExtensions(RazorEngine engine)
+        private static void AssertDefaultRuntimeTargetExtensions(RazorEngine engine)
         {
             var feature = engine.Features.OfType<IRazorTargetExtensionFeature>().FirstOrDefault();
             Assert.NotNull(feature);
 
-            Assert.Empty(feature.TargetExtensions);
+            Assert.Collection(
+                feature.TargetExtensions,
+                extension => Assert.False(Assert.IsType<DefaultTagHelperTargetExtension>(extension).DesignTime),
+                extension => Assert.IsType<PreallocatedAttributeTargetExtension>(extension));
         }
 
         private static void AssertDefaultRuntimeFeatures(IEnumerable<IRazorEngineFeature> features)
@@ -151,6 +158,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 feature => Assert.IsType<HtmlNodeOptimizationPass>(feature),
                 feature => Assert.IsType<DefaultDocumentClassifierPass>(feature),
                 feature => Assert.IsType<DirectiveRemovalOptimizationPass>(feature),
+                feature => Assert.IsType<DefaultTagHelperOptimizationPass>(feature),
                 feature => Assert.IsType<DefaultDocumentClassifierPassFeature>(feature),
                 feature => Assert.IsType<PreallocatedTagHelperAttributeOptimizationPass>(feature));
         }
@@ -169,6 +177,17 @@ namespace Microsoft.AspNetCore.Razor.Language
                 phase => Assert.IsType<DefaultRazorCSharpLoweringPhase>(phase));
         }
 
+        private static void AssertDefaultDesignTimeTargetExtensions(RazorEngine engine)
+        {
+            var feature = engine.Features.OfType<IRazorTargetExtensionFeature>().FirstOrDefault();
+            Assert.NotNull(feature);
+
+            Assert.Collection(
+                feature.TargetExtensions,
+                extension => Assert.True(Assert.IsType<DefaultTagHelperTargetExtension>(extension).DesignTime),
+                extension => Assert.IsType<DesignTimeDirectiveTargetExtension>(extension));
+        }
+
         private static void AssertDefaultDesignTimeFeatures(IEnumerable<IRazorEngineFeature> features)
         {
             Assert.Collection(
@@ -179,6 +198,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 feature => Assert.IsType<HtmlNodeOptimizationPass>(feature),
                 feature => Assert.IsType<DefaultDocumentClassifierPass>(feature),
                 feature => Assert.IsType<DirectiveRemovalOptimizationPass>(feature),
+                feature => Assert.IsType<DefaultTagHelperOptimizationPass>(feature),
                 feature => Assert.IsType<DefaultDocumentClassifierPassFeature>(feature),
                 feature => Assert.IsType<DesignTimeOptionsFeature>(feature),
                 feature => Assert.IsType<DesignTimeDirectivePass>(feature));

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers_DesignTime.codegen.cs

@@ -5,6 +5,10 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
     #line hidden
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_AttributeTargetingTagHelpers_DesignTime
     {
+        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper;
+        private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper;
+        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -14,10 +18,6 @@ global::System.Object __typeHelper = "*, TestAssembly";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper = null;
-        private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper = null;
-        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper = null;
-        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2 = null;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers_DesignTime.ir.txt

@@ -1,27 +1,32 @@
 Document - 
     NamespaceDeclaration -  - Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_AttributeTargetingTagHelpers_DesignTime -  - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::TestNamespace.PTagHelper - __TestNamespace_PTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.CatchAllTagHelper - __TestNamespace_CatchAllTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper2 - __TestNamespace_InputTagHelper2
             DesignTimeDirective - 
                 DirectiveToken - (14:0,14 [15] AttributeTargetingTagHelpers.cshtml) - *, TestAssembly
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - TestNamespace.PTagHelper - TestNamespace.CatchAllTagHelper - TestNamespace.InputTagHelper - TestNamespace.InputTagHelper2
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (29:0,29 [4] AttributeTargetingTagHelpers.cshtml)
                     IntermediateToken - (29:0,29 [4] AttributeTargetingTagHelpers.cshtml) - Html - \n\n
                 TagHelper - (33:2,0 [228] AttributeTargetingTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (48:2,15 [9] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (48:2,15 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                             IntermediateToken - (54:3,4 [3] AttributeTargetingTagHelpers.cshtml) - Html - <p>
                         TagHelper - (57:3,7 [36] AttributeTargetingTagHelpers.cshtml) - strong - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (79:3,29 [5] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (79:3,29 [5] AttributeTargetingTagHelpers.cshtml) - Html - Hello
-                            CreateTagHelper -  - TestNamespace.CatchAllTagHelper
-                            AddTagHelperHtmlAttribute -  - catchAll - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
+                            DefaultTagHelperHtmlAttribute -  - catchAll - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (75:3,25 [2] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (75:3,25 [2] AttributeTargetingTagHelpers.cshtml) - Html - hi
+                            DefaultTagHelperExecute - 
                         HtmlContent - (93:3,43 [62] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (93:3,43 [8] AttributeTargetingTagHelpers.cshtml) - Html - <strong>
                             IntermediateToken - (101:3,51 [5] AttributeTargetingTagHelpers.cshtml) - Html - World
@@ -33,38 +38,41 @@ Document -
                             IntermediateToken - (146:4,25 [3] AttributeTargetingTagHelpers.cshtml) - Html -  />
                             IntermediateToken - (149:4,28 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                         TagHelper - (155:5,4 [40] AttributeTargetingTagHelpers.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            SetTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper2.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - CSharp - true
+                            DefaultTagHelperExecute - 
                         HtmlContent - (195:5,44 [6] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (195:5,44 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                         TagHelper - (201:6,4 [54] AttributeTargetingTagHelpers.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            CreateTagHelper -  - TestNamespace.CatchAllTagHelper
-                            SetTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
+                            DefaultTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper2.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - CSharp - true
-                            AddTagHelperHtmlAttribute -  - catchAll - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperHtmlAttribute -  - catchAll - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (249:6,52 [2] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (249:6,52 [2] AttributeTargetingTagHelpers.cshtml) - Html - hi
+                            DefaultTagHelperExecute - 
                         HtmlContent - (255:6,58 [2] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (255:6,58 [2] AttributeTargetingTagHelpers.cshtml) - Html - \n
-                    CreateTagHelper -  - TestNamespace.PTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (43:2,10 [3] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (43:2,10 [3] AttributeTargetingTagHelpers.cshtml) - Html - btn
+                    DefaultTagHelperExecute - 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers_DesignTime.mappings.txt

@@ -1,15 +1,15 @@
 Source Location: (14:0,14 [15] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers.cshtml)
 |*, TestAssembly|
-Generated Location: (435:10,38 [15] )
+Generated Location: (779:14,38 [15] )
 |*, TestAssembly|
 
 Source Location: (187:5,36 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers.cshtml)
 |true|
-Generated Location: (1679:29,42 [4] )
+Generated Location: (1651:29,42 [4] )
 |true|
 
 Source Location: (233:6,36 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers.cshtml)
 |true|
-Generated Location: (2332:39,42 [4] )
+Generated Location: (2304:39,42 [4] )
 |true|
 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers_Runtime.codegen.cs

@@ -11,9 +11,9 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_2 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("class", new global::Microsoft.AspNetCore.Html.HtmlString("btn"), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -27,10 +27,10 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper = null;
-        private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper = null;
-        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper = null;
-        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2 = null;
+        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper;
+        private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper;
+        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/AttributeTargetingTagHelpers_Runtime.ir.txt

@@ -1,24 +1,29 @@
 Document - 
     NamespaceDeclaration -  - Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_AttributeTargetingTagHelpers_Runtime -  - 
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0 - catchAll - hi - AttributeStructure.DoubleQuotes
-            DeclarePreallocatedTagHelperAttribute -  - __tagHelperAttribute_1 - type - checkbox - HtmlAttributeValueStyle.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2 - class - btn - AttributeStructure.DoubleQuotes
-            DeclareTagHelperFields -  - TestNamespace.PTagHelper - TestNamespace.CatchAllTagHelper - TestNamespace.InputTagHelper - TestNamespace.InputTagHelper2
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_0 - catchAll - hi - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperPropertyValue -  - __tagHelperAttribute_1 - type - checkbox - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_2 - class - btn - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::TestNamespace.PTagHelper - __TestNamespace_PTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.CatchAllTagHelper - __TestNamespace_CatchAllTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper2 - __TestNamespace_InputTagHelper2
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (31:1,0 [2] AttributeTargetingTagHelpers.cshtml)
                     IntermediateToken - (31:1,0 [2] AttributeTargetingTagHelpers.cshtml) - Html - \n
                 TagHelper - (33:2,0 [228] AttributeTargetingTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (48:2,15 [9] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (48:2,15 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                             IntermediateToken - (54:3,4 [3] AttributeTargetingTagHelpers.cshtml) - Html - <p>
                         TagHelper - (57:3,7 [36] AttributeTargetingTagHelpers.cshtml) - strong - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
+                            DefaultTagHelperBody - 
                                 HtmlContent - (79:3,29 [5] AttributeTargetingTagHelpers.cshtml)
                                     IntermediateToken - (79:3,29 [5] AttributeTargetingTagHelpers.cshtml) - Html - Hello
-                            CreateTagHelper -  - TestNamespace.CatchAllTagHelper
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                            DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                            DefaultTagHelperExecute - 
                         HtmlContent - (93:3,43 [62] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (93:3,43 [8] AttributeTargetingTagHelpers.cshtml) - Html - <strong>
                             IntermediateToken - (101:3,51 [5] AttributeTargetingTagHelpers.cshtml) - Html - World
@@ -30,26 +35,29 @@ Document -
                             IntermediateToken - (146:4,25 [3] AttributeTargetingTagHelpers.cshtml) - Html -  />
                             IntermediateToken - (149:4,28 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                         TagHelper - (155:5,4 [40] AttributeTargetingTagHelpers.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_1 - type - Type
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_1 - type - Type
-                            SetTagHelperProperty - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            PreallocatedTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - __tagHelperAttribute_1 - type - Type
+                            PreallocatedTagHelperProperty - (168:5,17 [8] AttributeTargetingTagHelpers.cshtml) - __tagHelperAttribute_1 - type - Type
+                            DefaultTagHelperProperty - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (187:5,36 [4] AttributeTargetingTagHelpers.cshtml) - CSharp - true
+                            DefaultTagHelperExecute - 
                         HtmlContent - (195:5,44 [6] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (195:5,44 [6] AttributeTargetingTagHelpers.cshtml) - Html - \n    
                         TagHelper - (201:6,4 [54] AttributeTargetingTagHelpers.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            CreateTagHelper -  - TestNamespace.CatchAllTagHelper
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_1 - type - Type
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_1 - type - Type
-                            SetTagHelperProperty - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
+                            PreallocatedTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - __tagHelperAttribute_1 - type - Type
+                            PreallocatedTagHelperProperty - (214:6,17 [8] AttributeTargetingTagHelpers.cshtml) - __tagHelperAttribute_1 - type - Type
+                            DefaultTagHelperProperty - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (233:6,36 [4] AttributeTargetingTagHelpers.cshtml) - CSharp - true
-                            AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                            PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_0
+                            DefaultTagHelperExecute - 
                         HtmlContent - (255:6,58 [2] AttributeTargetingTagHelpers.cshtml)
                             IntermediateToken - (255:6,58 [2] AttributeTargetingTagHelpers.cshtml) - Html - \n
-                    CreateTagHelper -  - TestNamespace.PTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_2
+                    DefaultTagHelperExecute - 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_DesignTime.codegen.cs

@@ -5,6 +5,9 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
     #line hidden
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_BasicTagHelpers_DesignTime
     {
+        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper;
+        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -14,9 +17,6 @@ global::System.Object __typeHelper = "*, TestAssembly";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper = null;
-        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper = null;
-        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2 = null;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_DesignTime.ir.txt

@@ -1,11 +1,14 @@
 Document - 
     NamespaceDeclaration -  - Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_BasicTagHelpers_DesignTime -  - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::TestNamespace.PTagHelper - __TestNamespace_PTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper2 - __TestNamespace_InputTagHelper2
             DesignTimeDirective - 
                 DirectiveToken - (14:0,14 [17] BasicTagHelpers.cshtml) - "*, TestAssembly"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - TestNamespace.PTagHelper - TestNamespace.InputTagHelper - TestNamespace.InputTagHelper2
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (31:0,31 [73] BasicTagHelpers.cshtml)
                     IntermediateToken - (31:0,31 [4] BasicTagHelpers.cshtml) - Html - \n\n
@@ -17,57 +20,61 @@ Document -
                     IntermediateToken - (97:2,62 [1] BasicTagHelpers.cshtml) - Html - >
                     IntermediateToken - (98:2,63 [6] BasicTagHelpers.cshtml) - Html - \n    
                 TagHelper - (104:3,4 [216] BasicTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (145:3,45 [10] BasicTagHelpers.cshtml)
                             IntermediateToken - (145:3,45 [10] BasicTagHelpers.cshtml) - Html - \n        
                         TagHelper - (155:4,8 [25] BasicTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.PTagHelper
-                            AddTagHelperHtmlAttribute -  - data - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                            DefaultTagHelperHtmlAttribute -  - data - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (164:4,17 [10] BasicTagHelpers.cshtml)
                                     IntermediateToken - (164:4,17 [10] BasicTagHelpers.cshtml) - Html - -delay1000
+                            DefaultTagHelperExecute - 
                         HtmlContent - (180:4,33 [10] BasicTagHelpers.cshtml)
                             IntermediateToken - (180:4,33 [10] BasicTagHelpers.cshtml) - Html - \n        
                         TagHelper - (190:5,8 [71] BasicTagHelpers.cshtml) - input - TagMode.StartTagOnly
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            AddTagHelperHtmlAttribute -  - data-interval - AttributeStructure.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperHtmlAttribute -  - data-interval - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (212:5,30 [7] BasicTagHelpers.cshtml)
                                     IntermediateToken - (212:5,30 [7] BasicTagHelpers.cshtml) - Html - 2000 + 
                                 CSharpExpression - (220:5,38 [23] BasicTagHelpers.cshtml)
                                     IntermediateToken - (220:5,38 [23] BasicTagHelpers.cshtml) - CSharp - ViewBag.DefaultInterval
                                 HtmlContent - (243:5,61 [4] BasicTagHelpers.cshtml)
                                     IntermediateToken - (243:5,61 [4] BasicTagHelpers.cshtml) - Html -  + 1
-                            SetTagHelperProperty - (255:5,73 [4] BasicTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (255:5,73 [4] BasicTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (255:5,73 [4] BasicTagHelpers.cshtml)
                                     IntermediateToken - (255:5,73 [4] BasicTagHelpers.cshtml) - Html - text
-                            SetTagHelperProperty - (255:5,73 [4] BasicTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (255:5,73 [4] BasicTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper2.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (255:5,73 [4] BasicTagHelpers.cshtml)
                                     IntermediateToken - (255:5,73 [4] BasicTagHelpers.cshtml) - Html - text
+                            DefaultTagHelperExecute - 
                         HtmlContent - (261:5,79 [10] BasicTagHelpers.cshtml)
                             IntermediateToken - (261:5,79 [10] BasicTagHelpers.cshtml) - Html - \n        
                         TagHelper - (271:6,8 [39] BasicTagHelpers.cshtml) - input - TagMode.SelfClosing
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            SetTagHelperProperty - (284:6,21 [8] BasicTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperProperty - (284:6,21 [8] BasicTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (284:6,21 [8] BasicTagHelpers.cshtml)
                                     IntermediateToken - (284:6,21 [8] BasicTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (284:6,21 [8] BasicTagHelpers.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (284:6,21 [8] BasicTagHelpers.cshtml) - type - string TestNamespace.InputTagHelper2.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (284:6,21 [8] BasicTagHelpers.cshtml)
                                     IntermediateToken - (284:6,21 [8] BasicTagHelpers.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (303:6,40 [4] BasicTagHelpers.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (303:6,40 [4] BasicTagHelpers.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (303:6,40 [4] BasicTagHelpers.cshtml) - CSharp - true
+                            DefaultTagHelperExecute - 
                         HtmlContent - (310:6,47 [6] BasicTagHelpers.cshtml)
                             IntermediateToken - (310:6,47 [6] BasicTagHelpers.cshtml) - Html - \n    
-                    CreateTagHelper -  - TestNamespace.PTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (114:3,14 [11] BasicTagHelpers.cshtml)
                             IntermediateToken - (114:3,14 [11] BasicTagHelpers.cshtml) - Html - Hello World
-                    AddTagHelperHtmlAttribute -  - data-delay - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperHtmlAttribute -  - data-delay - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (139:3,39 [4] BasicTagHelpers.cshtml)
                             IntermediateToken - (139:3,39 [4] BasicTagHelpers.cshtml) - Html - 1000
+                    DefaultTagHelperExecute - 
                 HtmlContent - (320:7,8 [8] BasicTagHelpers.cshtml)
                     IntermediateToken - (320:7,8 [2] BasicTagHelpers.cshtml) - Html - \n
                     IntermediateToken - (322:8,0 [6] BasicTagHelpers.cshtml) - Html - </div>

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_DesignTime.mappings.txt

@@ -1,15 +1,15 @@
 Source Location: (14:0,14 [17] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers.cshtml)
 |"*, TestAssembly"|
-Generated Location: (421:10,37 [17] )
+Generated Location: (673:13,37 [17] )
 |"*, TestAssembly"|
 
 Source Location: (220:5,38 [23] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers.cshtml)
 |ViewBag.DefaultInterval|
-Generated Location: (1384:26,38 [23] )
+Generated Location: (1363:26,38 [23] )
 |ViewBag.DefaultInterval|
 
 Source Location: (303:6,40 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers.cshtml)
 |true|
-Generated Location: (2082:37,42 [4] )
+Generated Location: (2061:37,42 [4] )
 |true|
 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_DesignTime.codegen.cs

@@ -5,6 +5,9 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
     #line hidden
     public class TestFiles_IntegrationTests_CodeGenerationIntegrationTest_BasicTagHelpers_Prefixed_DesignTime
     {
+        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper;
+        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -18,9 +21,6 @@ global::System.Object __typeHelper = "*, TestAssembly";
         }
         #pragma warning restore 219
         private static System.Object __o = null;
-        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper = null;
-        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper = null;
-        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2 = null;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_DesignTime.ir.txt

@@ -1,12 +1,15 @@
 Document - 
     NamespaceDeclaration -  - Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_BasicTagHelpers_Prefixed_DesignTime -  - 
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::TestNamespace.PTagHelper - __TestNamespace_PTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper2 - __TestNamespace_InputTagHelper2
             DesignTimeDirective - 
                 DirectiveToken - (17:0,17 [5] BasicTagHelpers_Prefixed.cshtml) - "THS"
                 DirectiveToken - (38:1,14 [17] BasicTagHelpers_Prefixed.cshtml) - "*, TestAssembly"
             CSharpCode - 
                 IntermediateToken -  - CSharp - private static System.Object __o = null;
-            DeclareTagHelperFields -  - TestNamespace.PTagHelper - TestNamespace.InputTagHelper - TestNamespace.InputTagHelper2
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (22:0,22 [2] BasicTagHelpers_Prefixed.cshtml)
                     IntermediateToken - (22:0,22 [2] BasicTagHelpers_Prefixed.cshtml) - Html - \n
@@ -17,7 +20,7 @@ Document -
                     IntermediateToken - (102:3,43 [1] BasicTagHelpers_Prefixed.cshtml) - Html - >
                     IntermediateToken - (103:3,44 [6] BasicTagHelpers_Prefixed.cshtml) - Html - \n    
                 TagHelper - (109:4,4 [136] BasicTagHelpers_Prefixed.cshtml) - p - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (135:4,30 [56] BasicTagHelpers_Prefixed.cshtml)
                             IntermediateToken - (135:4,30 [10] BasicTagHelpers_Prefixed.cshtml) - Html - \n        
                             IntermediateToken - (145:5,8 [3] BasicTagHelpers_Prefixed.cshtml) - Html - <p>
@@ -28,23 +31,25 @@ Document -
                             IntermediateToken - (180:6,26 [1] BasicTagHelpers_Prefixed.cshtml) - Html - >
                             IntermediateToken - (181:6,27 [10] BasicTagHelpers_Prefixed.cshtml) - Html - \n        
                         TagHelper - (191:7,8 [41] BasicTagHelpers_Prefixed.cshtml) - input - TagMode.StartTagOnly
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            SetTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            DefaultTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - type - string TestNamespace.InputTagHelper.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml)
                                     IntermediateToken - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - type - Type - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - type - string TestNamespace.InputTagHelper2.Type - HtmlAttributeValueStyle.DoubleQuotes
                                 HtmlContent - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml)
                                     IntermediateToken - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - Html - checkbox
-                            SetTagHelperProperty - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperProperty - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - CSharp - true
+                            DefaultTagHelperExecute - 
                         HtmlContent - (232:7,49 [6] BasicTagHelpers_Prefixed.cshtml)
                             IntermediateToken - (232:7,49 [6] BasicTagHelpers_Prefixed.cshtml) - Html - \n    
-                    CreateTagHelper -  - TestNamespace.PTagHelper
-                    AddTagHelperHtmlAttribute -  - class - AttributeStructure.DoubleQuotes
+                    DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                    DefaultTagHelperHtmlAttribute -  - class - HtmlAttributeValueStyle.DoubleQuotes
                         HtmlContent - (122:4,17 [11] BasicTagHelpers_Prefixed.cshtml)
                             IntermediateToken - (122:4,17 [11] BasicTagHelpers_Prefixed.cshtml) - Html - Hello World
+                    DefaultTagHelperExecute - 
                 HtmlContent - (245:8,11 [11] BasicTagHelpers_Prefixed.cshtml)
                     IntermediateToken - (245:8,11 [2] BasicTagHelpers_Prefixed.cshtml) - Html - \n
                     IntermediateToken - (247:9,0 [9] BasicTagHelpers_Prefixed.cshtml) - Html - </THSdiv>

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_DesignTime.mappings.txt

@@ -1,15 +1,15 @@
 Source Location: (17:0,17 [5] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed.cshtml)
 |"THS"|
-Generated Location: (430:10,37 [5] )
+Generated Location: (682:13,37 [5] )
 |"THS"|
 
 Source Location: (38:1,14 [17] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed.cshtml)
 |"*, TestAssembly"|
-Generated Location: (535:14,37 [17] )
+Generated Location: (787:17,37 [17] )
 |"*, TestAssembly"|
 
 Source Location: (226:7,43 [4] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed.cshtml)
 |true|
-Generated Location: (1569:31,43 [4] )
+Generated Location: (1548:31,43 [4] )
 |true|
 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.codegen.cs

@@ -10,9 +10,9 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         private static readonly global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute __tagHelperAttribute_1 = new global::Microsoft.AspNetCore.Razor.TagHelpers.TagHelperAttribute("class", new global::Microsoft.AspNetCore.Html.HtmlString("Hello World"), global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.DoubleQuotes);
         #line hidden
         #pragma warning disable 0414
-        private string __tagHelperStringValueBuffer = null;
+        private string __tagHelperStringValueBuffer;
         #pragma warning restore 0414
-        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext = null;
+        private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext __tagHelperExecutionContext;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner __tagHelperRunner = new global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner();
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __backed__tagHelperScopeManager = null;
         private global::Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperScopeManager __tagHelperScopeManager
@@ -26,9 +26,9 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
                 return __backed__tagHelperScopeManager;
             }
         }
-        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper = null;
-        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper = null;
-        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2 = null;
+        private global::TestNamespace.PTagHelper __TestNamespace_PTagHelper;
+        private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::TestNamespace.InputTagHelper2 __TestNamespace_InputTagHelper2;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.ir.txt

@@ -1,9 +1,12 @@
 Document - 
     NamespaceDeclaration -  - Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         ClassDeclaration -  - public - TestFiles_IntegrationTests_CodeGenerationIntegrationTest_BasicTagHelpers_Prefixed_Runtime -  - 
-            DeclarePreallocatedTagHelperAttribute -  - __tagHelperAttribute_0 - type - checkbox - HtmlAttributeValueStyle.DoubleQuotes
-            DeclarePreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1 - class - Hello World - AttributeStructure.DoubleQuotes
-            DeclareTagHelperFields -  - TestNamespace.PTagHelper - TestNamespace.InputTagHelper - TestNamespace.InputTagHelper2
+            PreallocatedTagHelperPropertyValue -  - __tagHelperAttribute_0 - type - checkbox - HtmlAttributeValueStyle.DoubleQuotes
+            PreallocatedTagHelperHtmlAttributeValue -  - __tagHelperAttribute_1 - class - Hello World - HtmlAttributeValueStyle.DoubleQuotes
+            DefaultTagHelperRuntime - 
+            FieldDeclaration -  - private - global::TestNamespace.PTagHelper - __TestNamespace_PTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::TestNamespace.InputTagHelper2 - __TestNamespace_InputTagHelper2
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (57:2,0 [52] BasicTagHelpers_Prefixed.cshtml)
                     IntermediateToken - (57:2,0 [2] BasicTagHelpers_Prefixed.cshtml) - Html - \n
@@ -12,7 +15,7 @@ Document -
                     IntermediateToken - (102:3,43 [1] BasicTagHelpers_Prefixed.cshtml) - Html - >
                     IntermediateToken - (103:3,44 [6] BasicTagHelpers_Prefixed.cshtml) - Html - \n    
                 TagHelper - (109:4,4 [136] BasicTagHelpers_Prefixed.cshtml) - p - TagMode.StartTagAndEndTag
-                    TagHelperBody - 
+                    DefaultTagHelperBody - 
                         HtmlContent - (135:4,30 [56] BasicTagHelpers_Prefixed.cshtml)
                             IntermediateToken - (135:4,30 [10] BasicTagHelpers_Prefixed.cshtml) - Html - \n        
                             IntermediateToken - (145:5,8 [3] BasicTagHelpers_Prefixed.cshtml) - Html - <p>
@@ -23,17 +26,19 @@ Document -
                             IntermediateToken - (180:6,26 [1] BasicTagHelpers_Prefixed.cshtml) - Html - >
                             IntermediateToken - (181:6,27 [10] BasicTagHelpers_Prefixed.cshtml) - Html - \n        
                         TagHelper - (191:7,8 [41] BasicTagHelpers_Prefixed.cshtml) - input - TagMode.StartTagOnly
-                            TagHelperBody - 
-                            CreateTagHelper -  - TestNamespace.InputTagHelper
-                            CreateTagHelper -  - TestNamespace.InputTagHelper2
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_0 - type - Type
-                            SetPreallocatedTagHelperProperty -  - __tagHelperAttribute_0 - type - Type
-                            SetTagHelperProperty - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - checked - Checked - HtmlAttributeValueStyle.DoubleQuotes
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper
+                            DefaultTagHelperCreate -  - TestNamespace.InputTagHelper2
+                            PreallocatedTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - __tagHelperAttribute_0 - type - Type
+                            PreallocatedTagHelperProperty - (207:7,24 [8] BasicTagHelpers_Prefixed.cshtml) - __tagHelperAttribute_0 - type - Type
+                            DefaultTagHelperProperty - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - checked - bool TestNamespace.InputTagHelper2.Checked - HtmlAttributeValueStyle.DoubleQuotes
                                 IntermediateToken - (226:7,43 [4] BasicTagHelpers_Prefixed.cshtml) - CSharp - true
+                            DefaultTagHelperExecute - 
                         HtmlContent - (232:7,49 [6] BasicTagHelpers_Prefixed.cshtml)
                             IntermediateToken - (232:7,49 [6] BasicTagHelpers_Prefixed.cshtml) - Html - \n    
-                    CreateTagHelper -  - TestNamespace.PTagHelper
-                    AddPreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                    DefaultTagHelperCreate -  - TestNamespace.PTagHelper
+                    PreallocatedTagHelperHtmlAttribute -  - __tagHelperAttribute_1
+                    DefaultTagHelperExecute - 
                 HtmlContent - (245:8,11 [11] BasicTagHelpers_Prefixed.cshtml)
                     IntermediateToken - (245:8,11 [2] BasicTagHelpers_Prefixed.cshtml) - Html - \n
                     IntermediateToken - (247:9,0 [9] BasicTagHelpers_Prefixed.cshtml) - Html - </THSdiv>