Allow expressions with @bind:event

Fixes aspnet/AspNetCoredotnet/aspnetcore-tooling#13181

The big change here is that we have to allow an HtmlAttributeIRNode to have
a dynamically computed attribute name. This isn't something that exists
anywhere else in the system.
\n\nCommit migrated from 559f0f5e52

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentBindLoweringPass.cs

@@ -275,6 +275,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 out var valueAttributeName,
                 out var changeAttributeName,
                 out var expressionAttributeName,
+                out var changeAttributeNode,
                 out var valueAttribute,
                 out var changeAttribute,
                 out var expressionAttribute))
@@ -393,12 +394,13 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                         [ComponentMetadata.Common.OriginalAttributeName] = node.OriginalAttributeName,
                     },
                     AttributeName = changeAttributeName,
+                    AttributeNameExpression = changeAttributeNode,
                     Source = node.Source,
 
                     Prefix = changeAttributeName + "=\"",
                     Suffix = "\"",
 
-                    EventUpdatesAttributeName = valueNode.AttributeName,
+                    EventUpdatesAttributeName = valueAttributeName,
                 };
 
                 changeNode.Children.Add(new CSharpExpressionAttributeValueIntermediateNode());
@@ -510,6 +512,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             out string valueAttributeName,
             out string changeAttributeName,
             out string expressionAttributeName,
+            out CSharpExpressionIntermediateNode changeAttributeNode,
             out BoundAttributeDescriptor valueAttribute,
             out BoundAttributeDescriptor changeAttribute,
             out BoundAttributeDescriptor expressionAttribute)
@@ -517,10 +520,20 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             valueAttributeName = null;
             changeAttributeName = null;
             expressionAttributeName = null;
+            changeAttributeNode = null;
             valueAttribute = null;
             changeAttribute = null;
             expressionAttribute = null;
 
+            // The tag helper specifies attribute names, they should win.
+            //
+            // This handles cases like <input type="text" bind="@Foo" /> where the tag helper is
+            // generated to match a specific tag and has metadata that identify the attributes.
+            //
+            // We expect 1 bind tag helper per-node.
+            var node = bindEntry.BindNode;
+            var attributeName = node.AttributeName;
+
             // Even though some of our 'bind' tag helpers specify the attribute names, they
             // should still satisfy one of the valid syntaxes.
             if (!TryParseBindAttribute(bindEntry, out valueAttributeName))
@@ -528,24 +541,25 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 return false;
             }
 
-            if (bindEntry.BindEventNode != null)
-            {
-                changeAttributeName = GetAttributeContent(bindEntry.BindEventNode)?.Content?.Trim('"');
-            }
-
-            // The tag helper specifies attribute names, they should win.
-            //
-            // This handles cases like <input type="text" bind="@Foo" /> where the tag helper is 
-            // generated to match a specific tag and has metadata that identify the attributes.
-            //
-            // We expect 1 bind tag helper per-node.
-            var node = bindEntry.BindNode;
-            var attributeName = node.AttributeName;
             valueAttributeName = node.TagHelper.GetValueAttributeName() ?? valueAttributeName;
 
             // If there an attribute that specifies the event like @bind:event="oninput",
             // that should be preferred. Otherwise, use the one from the tag helper.
-            changeAttributeName ??= node.TagHelper.GetChangeAttributeName();
+            if (bindEntry.BindEventNode == null)
+            {
+                // @bind:event not specified
+                changeAttributeName ??= node.TagHelper.GetChangeAttributeName();
+            }
+            else if (TryExtractEventNodeStaticText(bindEntry.BindEventNode, out var text))
+            {
+                // @bind:event="oninput" - change attribute is static
+                changeAttributeName = text;
+            }
+            else
+            {
+                // @bind:event="@someExpr" - we can't know the name of the change attribute, it's dynamic
+                changeAttributeNode = ExtractEventNodeExpression(bindEntry.BindEventNode);
+            }
 
             expressionAttributeName = node.TagHelper.GetExpressionAttributeName();
 
@@ -554,7 +568,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             if (componentTagHelper == null)
             {
                 // If it's not a component node then there isn't too much else to figure out.
-                return attributeName != null && changeAttributeName != null;
+                return attributeName != null && (changeAttributeName != null || changeAttributeNode != null);
             }
 
             // If this is a component, we need an attribute name for the value.
@@ -597,6 +611,28 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             }
 
             return true;
+
+            static bool TryExtractEventNodeStaticText(TagHelperDirectiveAttributeParameterIntermediateNode node, out string text)
+            {
+                if (node.Children[0] is HtmlContentIntermediateNode html)
+                {
+                    text = GetAttributeContent(html).Content;
+                    return true;
+                }
+
+                text = null;
+                return false;
+            }
+
+            static CSharpExpressionIntermediateNode ExtractEventNodeExpression(TagHelperDirectiveAttributeParameterIntermediateNode node)
+            {
+                if (node.Children[0] is CSharpExpressionIntermediateNode expression)
+                {
+                    return expression;
+                }
+
+                return null;
+            }
         }
 
         private void RewriteNodesForComponentDelegateBind(

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDesignTimeNodeWriter.cs

@@ -85,6 +85,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 throw new ArgumentNullException(nameof(node));
             }
 
+            WriteCSharpExpressionInnards(context, node);
+        }
+
+        private void WriteCSharpExpressionInnards(CodeRenderingContext context, CSharpExpressionIntermediateNode node, string type = null)
+        {
             if (node.Children.Count == 0)
             {
                 return;
@@ -95,9 +100,22 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 using (context.CodeWriter.BuildLinePragma(node.Source.Value, context))
                 {
                     var offset = DesignTimeVariable.Length + " = ".Length;
+
+                    if (type != null)
+                    {
+                        offset += type.Length + 2; // two parenthesis
+                    }
+
                     context.CodeWriter.WritePadding(offset, node.Source, context);
                     context.CodeWriter.WriteStartAssignment(DesignTimeVariable);
 
+                    if (type != null)
+                    {
+                        context.CodeWriter.Write("(");
+                        context.CodeWriter.Write(type);
+                        context.CodeWriter.Write(")");
+                    }
+
                     for (var i = 0; i < node.Children.Count; i++)
                     {
                         if (node.Children[i] is IntermediateToken token && token.IsCSharp)
@@ -209,6 +227,13 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 throw new ArgumentNullException(nameof(node));
             }
 
+            // This expression may contain code so we have to render it or else the design-time
+            // exprience is broken.
+            if (node.AttributeNameExpression is CSharpExpressionIntermediateNode expression)
+            {
+                WriteCSharpExpressionInnards(context, expression, "string");
+            }
+
             context.RenderChildren(node);
         }
 
@@ -275,11 +300,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             // Do nothing
         }
 
-        protected override void BeginWriteAttribute(CodeWriter codeWriter, string key)
+        protected override void BeginWriteAttribute(CodeRenderingContext context, string key)
         {
-            if (codeWriter == null)
+            if (context == null)
             {
-                throw new ArgumentNullException(nameof(codeWriter));
+                throw new ArgumentNullException(nameof(context));
             }
 
             if (key == null)
@@ -287,7 +312,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 throw new ArgumentNullException(nameof(key));
             }
 
-            codeWriter
+            context.CodeWriter
                 .WriteStartMethodInvocation($"{_scopeStack.BuilderVarName}.{nameof(ComponentsApi.RenderTreeBuilder.AddAttribute)}")
                 .Write("-1")
                 .WriteParameterSeparator()
@@ -295,6 +320,31 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 .WriteParameterSeparator();
         }
 
+        protected override void BeginWriteAttribute(CodeRenderingContext context, IntermediateNode expression)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            if (expression == null)
+            {
+                throw new ArgumentNullException(nameof(expression));
+            }
+
+            context.CodeWriter.WriteStartMethodInvocation($"{_scopeStack.BuilderVarName}.{ComponentsApi.RenderTreeBuilder.AddAttribute}");
+            context.CodeWriter.Write("-1");
+            context.CodeWriter.WriteParameterSeparator();
+
+            var tokens = GetCSharpTokens(expression);
+            for (var i = 0; i < tokens.Count; i++)
+            {
+                context.CodeWriter.Write(tokens[i].Content);
+            }
+
+            context.CodeWriter.WriteParameterSeparator();
+        }
+
         public override void WriteComponent(CodeRenderingContext context, ComponentIntermediateNode node)
         {
             if (context == null)
@@ -679,7 +729,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             // __builder.AddAttribute(1, "ChildContent", (RenderFragment)((__builder73) => { ... }));
             // OR
             // __builder.AddAttribute(1, "ChildContent", (RenderFragment<Person>)((person) => (__builder73) => { ... }));
-            BeginWriteAttribute(context.CodeWriter, node.AttributeName);
+            BeginWriteAttribute(context, node.AttributeName);
             context.CodeWriter.Write($"({node.TypeName})(");
 
             WriteComponentChildContentInnards(context, node);

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentNodeWriter.cs

@@ -12,7 +12,9 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
 {
     internal abstract class ComponentNodeWriter : IntermediateNodeWriter, ITemplateTargetExtension
     {
-        protected abstract void BeginWriteAttribute(CodeWriter codeWriter, string key);
+        protected abstract void BeginWriteAttribute(CodeRenderingContext context, string key);
+
+        protected abstract void BeginWriteAttribute(CodeRenderingContext context, IntermediateNode expression);
 
         protected abstract void WriteReferenceCaptureInnards(CodeRenderingContext context, ReferenceCaptureIntermediateNode node, bool shouldTypeCheck);
 

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentRuntimeNodeWriter.cs

@@ -233,7 +233,14 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             Debug.Assert(_currentAttributeValues.Count == 0);
             context.RenderChildren(node);
 
-            WriteAttribute(context, node.AttributeName, _currentAttributeValues);
+            if (node.AttributeNameExpression == null)
+            {
+                WriteAttribute(context, node.AttributeName, _currentAttributeValues);
+            }
+            else
+            {
+                WriteAttribute(context, node.AttributeNameExpression, _currentAttributeValues);
+            }
             _currentAttributeValues.Clear();
 
             if (!string.IsNullOrEmpty(node.EventUpdatesAttributeName))
@@ -659,7 +666,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
             // _builder.AddAttribute(1, "ChildContent", (RenderFragment)((__builder73) => { ... }));
             // OR
             // _builder.AddAttribute(1, "ChildContent", (RenderFragment<Person>)((person) => (__builder73) => { ... }));
-            BeginWriteAttribute(context.CodeWriter, node.AttributeName);
+            BeginWriteAttribute(context, node.AttributeName);
             context.CodeWriter.Write($"({node.TypeName})(");
 
             WriteComponentChildContentInnards(context, node);
@@ -837,14 +844,21 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
 
         private void WriteAttribute(CodeRenderingContext context, string key, IList<IntermediateToken> value)
         {
-            BeginWriteAttribute(context.CodeWriter, key);
+            BeginWriteAttribute(context, key);
             WriteAttributeValue(context, value);
             context.CodeWriter.WriteEndMethodInvocation();
         }
 
-        protected override void BeginWriteAttribute(CodeWriter codeWriter, string key)
+        private void WriteAttribute(CodeRenderingContext context, IntermediateNode nameExpression, IList<IntermediateToken> value)
         {
-            codeWriter
+            BeginWriteAttribute(context, nameExpression);
+            WriteAttributeValue(context, value);
+            context.CodeWriter.WriteEndMethodInvocation();
+        }
+
+        protected override void BeginWriteAttribute(CodeRenderingContext context, string key)
+        {
+            context.CodeWriter
                 .WriteStartMethodInvocation($"{_scopeStack.BuilderVarName}.{ComponentsApi.RenderTreeBuilder.AddAttribute}")
                 .Write((_sourceSequence++).ToString())
                 .WriteParameterSeparator()
@@ -852,6 +866,21 @@ namespace Microsoft.AspNetCore.Razor.Language.Components
                 .WriteParameterSeparator();
         }
 
+        protected override void BeginWriteAttribute(CodeRenderingContext context, IntermediateNode nameExpression)
+        {
+            context.CodeWriter.WriteStartMethodInvocation($"{_scopeStack.BuilderVarName}.{ComponentsApi.RenderTreeBuilder.AddAttribute}");
+            context.CodeWriter.Write((_sourceSequence++).ToString());
+            context.CodeWriter.WriteParameterSeparator();
+
+            var tokens = GetCSharpTokens(nameExpression);
+            for (var i = 0; i < tokens.Count; i++)
+            {
+                WriteCSharpToken(context, tokens[i]);
+            }
+
+            context.CodeWriter.WriteParameterSeparator();
+        }
+
         private static string GetHtmlContent(HtmlContentIntermediateNode node)
         {
             var builder = new StringBuilder();

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

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Linq;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate
 {
@@ -9,6 +10,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
     {
         public override IntermediateNodeCollection Children { get; } = new IntermediateNodeCollection();
 
+        public CSharpExpressionIntermediateNode AttributeNameExpression { get; set; }
+
         public string AttributeName { get; set; }
 
         public string Prefix { get; set; }
@@ -32,6 +35,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Intermediate
             formatter.WriteContent(AttributeName);
 
             formatter.WriteProperty(nameof(AttributeName), AttributeName);
+            formatter.WriteProperty(nameof(AttributeNameExpression), string.Join(string.Empty, AttributeNameExpression?.FindDescendantNodes<IntermediateToken>().Select(n => n.Content) ?? Array.Empty<string>()));
             formatter.WriteProperty(nameof(Prefix), Prefix);
             formatter.WriteProperty(nameof(Suffix), Suffix);
             formatter.WriteProperty(nameof(EventUpdatesAttributeName), EventUpdatesAttributeName);

src/Razor/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs

@@ -1011,6 +1011,64 @@ namespace Test
             CompileToAssembly(generated);
         }
 
+        [Fact]
+        public void BindToElement_WithEventAsExpression()
+        {
+            // Arrange
+            AdditionalSyntaxTrees.Add(Parse(@"
+using System;
+using Microsoft.AspNetCore.Components;
+
+namespace Test
+{
+    [BindElement(""div"", ""value"", ""myvalue"", ""myevent"")]
+    public static class BindAttributes
+    {
+    }
+}"));
+            // Act
+            var generated = CompileToCSharp(@"
+@{ var x = ""anotherevent""; }
+<div @bind-value=""@ParentValue"" @bind-value:event=""@x"" />
+@code {
+    public string ParentValue { get; set; } = ""hi"";
+}");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
+        [Fact]
+        public void BindToElement_WithEventAsExplicitExpression()
+        {
+            // Arrange
+            AdditionalSyntaxTrees.Add(Parse(@"
+using System;
+using Microsoft.AspNetCore.Components;
+
+namespace Test
+{
+    [BindElement(""div"", ""value"", ""myvalue"", ""myevent"")]
+    public static class BindAttributes
+    {
+    }
+}"));
+            // Act
+            var generated = CompileToCSharp(@"
+@{ var x = ""anotherevent""; }
+<div @bind-value=""@ParentValue"" @bind-value:event=""@(x.ToString())"" />
+@code {
+    public string ParentValue { get; set; } = ""hi"";
+}");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
         [Fact]
         public void BuiltIn_BindToInputWithoutType_WritesAttributes()
         {

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.codegen.cs

@@ -0,0 +1,59 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 219
+        private void __RazorDirectiveTokenHelpers__() {
+        }
+        #pragma warning restore 219
+        #pragma warning disable 0414
+        private static System.Object __o = null;
+        #pragma warning restore 0414
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+   var x = "anotherevent"; 
+
+#line default
+#line hidden
+#nullable disable
+            __o = Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                   ParentValue
+
+#line default
+#line hidden
+#nullable disable
+            );
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                       __o = (string)x.ToString();
+
+#line default
+#line hidden
+#nullable disable
+            __o = Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, ParentValue);
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    public string ParentValue { get; set; } = "hi";
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.ir.txt

@@ -0,0 +1,33 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [12] ) - System
+        UsingDirective - (18:2,1 [32] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [17] ) - System.Linq
+        UsingDirective - (73:4,1 [28] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [37] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase - 
+            DesignTimeDirective - 
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning disable 0414
+            CSharpCode - 
+                IntermediateToken -  - CSharp - private static System.Object __o = null;
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning restore 0414
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var x = "anotherevent"; 
+                MarkupElement - (30:1,0 [70] x:\dir\subdir\Test\TestComponent.cshtml) - div
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - myvalue=" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+                            IntermediateToken - (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - =" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, 
+                            IntermediateToken -  - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                HtmlContent - (100:1,70 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (100:1,70 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+            CSharpCode - (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+                IntermediateToken - (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    public string ParentValue { get; set; } = "hi";\n

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.mappings.txt

@@ -0,0 +1,24 @@
+Source Location: (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+| var x = "anotherevent"; |
+Generated Location: (854:24,2 [25] )
+| var x = "anotherevent"; |
+
+Source Location: (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml)
+|ParentValue|
+Generated Location: (1098:32,19 [11] )
+|ParentValue|
+
+Source Location: (83:1,53 [12] x:\dir\subdir\Test\TestComponent.cshtml)
+|x.ToString()|
+Generated Location: (1300:40,53 [12] )
+|x.ToString()|
+
+Source Location: (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    public string ParentValue { get; set; } = "hi";
+|
+Generated Location: (1631:50,7 [55] )
+|
+    public string ParentValue { get; set; } = "hi";
+|
+

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.codegen.cs

@@ -0,0 +1,59 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 219
+        private void __RazorDirectiveTokenHelpers__() {
+        }
+        #pragma warning restore 219
+        #pragma warning disable 0414
+        private static System.Object __o = null;
+        #pragma warning restore 0414
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+   var x = "anotherevent"; 
+
+#line default
+#line hidden
+#nullable disable
+            __o = Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                   ParentValue
+
+#line default
+#line hidden
+#nullable disable
+            );
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                      __o = (string)x;
+
+#line default
+#line hidden
+#nullable disable
+            __o = Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, ParentValue);
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    public string ParentValue { get; set; } = "hi";
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.ir.txt

@@ -0,0 +1,33 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [12] ) - System
+        UsingDirective - (18:2,1 [32] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [17] ) - System.Linq
+        UsingDirective - (73:4,1 [28] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [37] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase - 
+            DesignTimeDirective - 
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning disable 0414
+            CSharpCode - 
+                IntermediateToken -  - CSharp - private static System.Object __o = null;
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning restore 0414
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var x = "anotherevent"; 
+                MarkupElement - (30:1,0 [57] x:\dir\subdir\Test\TestComponent.cshtml) - div
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - myvalue=" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+                            IntermediateToken - (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - =" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, 
+                            IntermediateToken -  - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                HtmlContent - (87:1,57 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (87:1,57 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
+            CSharpCode - (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+                IntermediateToken - (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    public string ParentValue { get; set; } = "hi";\n

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.mappings.txt

@@ -0,0 +1,24 @@
+Source Location: (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+| var x = "anotherevent"; |
+Generated Location: (854:24,2 [25] )
+| var x = "anotherevent"; |
+
+Source Location: (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml)
+|ParentValue|
+Generated Location: (1098:32,19 [11] )
+|ParentValue|
+
+Source Location: (82:1,52 [1] x:\dir\subdir\Test\TestComponent.cshtml)
+|x|
+Generated Location: (1299:40,52 [1] )
+|x|
+
+Source Location: (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    public string ParentValue { get; set; } = "hi";
+|
+Generated Location: (1619:50,7 [55] )
+|
+    public string ParentValue { get; set; } = "hi";
+|
+

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.codegen.cs

@@ -0,0 +1,56 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+   var x = "anotherevent"; 
+
+#line default
+#line hidden
+#nullable disable
+            __builder.OpenElement(0, "div");
+            __builder.AddAttribute(1, "myvalue", Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                   ParentValue
+
+#line default
+#line hidden
+#nullable disable
+            ));
+            __builder.AddAttribute(2, 
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                                     x.ToString()
+
+#line default
+#line hidden
+#nullable disable
+            , Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, ParentValue));
+            __builder.SetUpdatesAttributeName("myvalue");
+            __builder.CloseElement();
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    public string ParentValue { get; set; } = "hi";
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.ir.txt

@@ -0,0 +1,24 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [14] ) - System
+        UsingDirective - (18:2,1 [34] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [19] ) - System.Linq
+        UsingDirective - (73:4,1 [30] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [39] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase - 
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var x = "anotherevent"; 
+                MarkupElement - (30:1,0 [70] x:\dir\subdir\Test\TestComponent.cshtml) - div
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - myvalue=" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+                            IntermediateToken - (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - =" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, 
+                            IntermediateToken -  - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+            CSharpCode - (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+                IntermediateToken - (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    public string ParentValue { get; set; } = "hi";\n

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExplicitExpression/TestComponent.mappings.txt

@@ -0,0 +1,14 @@
+Source Location: (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+| var x = "anotherevent"; |
+Generated Location: (586:17,2 [25] )
+| var x = "anotherevent"; |
+
+Source Location: (109:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    public string ParentValue { get; set; } = "hi";
+|
+Generated Location: (1575:47,7 [55] )
+|
+    public string ParentValue { get; set; } = "hi";
+|
+

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.codegen.cs

@@ -0,0 +1,56 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+   var x = "anotherevent"; 
+
+#line default
+#line hidden
+#nullable disable
+            __builder.OpenElement(0, "div");
+            __builder.AddAttribute(1, "myvalue", Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                   ParentValue
+
+#line default
+#line hidden
+#nullable disable
+            ));
+            __builder.AddAttribute(2, 
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                                    x
+
+#line default
+#line hidden
+#nullable disable
+            , Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, ParentValue));
+            __builder.SetUpdatesAttributeName("myvalue");
+            __builder.CloseElement();
+        }
+        #pragma warning restore 1998
+#nullable restore
+#line 3 "x:\dir\subdir\Test\TestComponent.cshtml"
+       
+    public string ParentValue { get; set; } = "hi";
+
+#line default
+#line hidden
+#nullable disable
+    }
+}
+#pragma warning restore 1591

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.ir.txt

@@ -0,0 +1,24 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [14] ) - System
+        UsingDirective - (18:2,1 [34] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [19] ) - System.Linq
+        UsingDirective - (73:4,1 [30] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [39] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - Microsoft.AspNetCore.Components.ComponentBase - 
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+                    IntermediateToken - (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var x = "anotherevent"; 
+                MarkupElement - (30:1,0 [57] x:\dir\subdir\Test\TestComponent.cshtml) - div
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - myvalue=" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.BindConverter.FormatValue(
+                            IntermediateToken - (49:1,19 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+                    HtmlAttribute - (48:1,18 [12] x:\dir\subdir\Test\TestComponent.cshtml) - =" - "
+                        CSharpExpressionAttributeValue -  - 
+                            IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.EventCallback.Factory.CreateBinder(this, __value => ParentValue = __value, 
+                            IntermediateToken -  - CSharp - ParentValue
+                            IntermediateToken -  - CSharp - )
+            CSharpCode - (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+                IntermediateToken - (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - \n    public string ParentValue { get; set; } = "hi";\n

src/Razor/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/BindToElement_WithEventAsExpression/TestComponent.mappings.txt

@@ -0,0 +1,14 @@
+Source Location: (2:0,2 [25] x:\dir\subdir\Test\TestComponent.cshtml)
+| var x = "anotherevent"; |
+Generated Location: (586:17,2 [25] )
+| var x = "anotherevent"; |
+
+Source Location: (96:2,7 [55] x:\dir\subdir\Test\TestComponent.cshtml)
+|
+    public string ParentValue { get; set; } = "hi";
+|
+Generated Location: (1563:47,7 [55] )
+|
+    public string ParentValue { get; set; } = "hi";
+|
+