Add property access codegen for component attributes that otherwise don't need codegen

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

@@ -5,10 +5,12 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Globalization;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
+using Microsoft.AspNetCore.Razor.PooledObjects;
 
 namespace Microsoft.AspNetCore.Razor.Language.Components;
 
@@ -529,11 +531,15 @@ private IntermediateNode[] RewriteUsage(IntermediateNode parent, BindEntry bindE
         }
         else
         {
+            using var _ = ArrayBuilderPool<IntermediateNode>.GetPooledObject(out var builder);
+
+            var valuePropertyName = valueAttribute?.GetPropertyName();
+
             ComponentAttributeIntermediateNode valueNode = node != null ? new ComponentAttributeIntermediateNode(node) : new ComponentAttributeIntermediateNode(getNode);
             valueNode.Annotations[ComponentMetadata.Common.OriginalAttributeName] = bindEntry.GetOriginalAttributeName();
             valueNode.AttributeName = valueAttributeName;
             valueNode.BoundAttribute = valueAttribute; // Might be null if it doesn't match a component attribute
-            valueNode.PropertyName = valueAttribute?.GetPropertyName();
+            valueNode.PropertyName = valuePropertyName;
             valueNode.TagHelper = valueAttribute == null ? null : bindEntry.GetEffectiveNodeTagHelperDescriptor();
             valueNode.TypeName = valueAttribute?.IsWeaklyTyped() == false ? valueAttribute.TypeName : null;
 
@@ -544,6 +550,8 @@ private IntermediateNode[] RewriteUsage(IntermediateNode parent, BindEntry bindE
                 valueNode.Children[0].Children.Add(valueExpressionTokens[i]);
             }
 
+            builder.Add(valueNode);
+
             var changeNode = node != null ? new ComponentAttributeIntermediateNode(node) : new ComponentAttributeIntermediateNode(getNode);
             changeNode.Annotations[ComponentMetadata.Common.OriginalAttributeName] = bindEntry.GetOriginalAttributeName();
             changeNode.AttributeName = changeAttributeName;
@@ -559,12 +567,13 @@ private IntermediateNode[] RewriteUsage(IntermediateNode parent, BindEntry bindE
                 changeNode.Children[0].Children.Add(changeExpressionTokens[i]);
             }
 
+            builder.Add(changeNode);
+
             // Finally, also emit a node for the "Expression" attribute, but only if the target
             // component is defined to accept one
-            ComponentAttributeIntermediateNode expressionNode = null;
             if (expressionAttribute != null)
             {
-                expressionNode = node != null ? new ComponentAttributeIntermediateNode(node) : new ComponentAttributeIntermediateNode(getNode);
+                var expressionNode = node != null ? new ComponentAttributeIntermediateNode(node) : new ComponentAttributeIntermediateNode(getNode);
                 expressionNode.Annotations[ComponentMetadata.Common.OriginalAttributeName] = bindEntry.GetOriginalAttributeName();
                 expressionNode.AttributeName = expressionAttributeName;
                 expressionNode.BoundAttribute = expressionAttribute;
@@ -579,12 +588,34 @@ private IntermediateNode[] RewriteUsage(IntermediateNode parent, BindEntry bindE
                     Content = $"() => {original.Content}",
                     Kind = TokenKind.CSharp
                 });
+
+                builder.Add(expressionNode);
             }
 
-            return expressionNode == null
-                ? new[] { valueNode, changeNode }
-                : new[] { valueNode, changeNode, expressionNode };
+            // We don't need to generate any runtime code for these attributes normally, as they're handled by the above nodes,
+            // but in order for IDE scenarios around component attributes to work we need to generate a little bit of design
+            // time code, so we create design time specific nodes with minimal information in order to do so.
+            TryAddDesignTimePropertyAccessHelperNode(builder, bindEntry.BindSetNode, valuePropertyName);
+            TryAddDesignTimePropertyAccessHelperNode(builder, bindEntry.BindEventNode, valuePropertyName);
+            TryAddDesignTimePropertyAccessHelperNode(builder, bindEntry.BindAfterNode, valuePropertyName);
+
+            return builder.ToArray();
+        }
+    }
+
+    private static void TryAddDesignTimePropertyAccessHelperNode(ImmutableArray<IntermediateNode>.Builder builder, TagHelperDirectiveAttributeParameterIntermediateNode intermediateNode, string propertyName)
+    {
+        if (intermediateNode is null || propertyName is null)
+        {
+            return;
         }
+
+        var helperNode = new ComponentAttributeIntermediateNode(intermediateNode);
+        helperNode.Annotations[ComponentMetadata.Common.OriginalAttributeName] = intermediateNode.OriginalAttributeName;
+        helperNode.Annotations[ComponentMetadata.Common.IsDesignTimePropertyAccessHelper] = bool.TrueString;
+        helperNode.PropertyName = propertyName;
+
+        builder.Add(helperNode);
     }
 
     private bool TryParseBindAttribute(BindEntry bindEntry, out string valueAttributeName)

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

@@ -362,7 +362,7 @@ public override void WriteComponent(CodeRenderingContext context, ComponentInter
             throw new ArgumentNullException(nameof(node));
         }
 
-        // We might need a scope for inferring types, 
+        // We might need a scope for inferring types,
         CodeWriterExtensions.CSharpCodeWritingScope? typeInferenceCaptureScope = null;
         string typeInferenceLocalName = null;
 
@@ -632,6 +632,12 @@ public override void WriteComponentAttribute(CodeRenderingContext context, Compo
             throw new ArgumentNullException(nameof(node));
         }
 
+        // This attribute might only be here in order to allow us to generate code in WritePropertyAccess
+        if (node.IsDesignTimePropertyAccessHelper())
+        {
+            return;
+        }
+
         // Looks like:
         // __o = 17;
         context.CodeWriter.Write(DesignTimeVariable);
@@ -647,7 +653,7 @@ public override void WriteComponentAttribute(CodeRenderingContext context, Compo
     private void WritePropertyAccess(CodeRenderingContext context, ComponentAttributeIntermediateNode node, ComponentIntermediateNode componentNode, string typeInferenceLocalName, bool shouldWriteBL0005Disable, out bool wrotePropertyAccess)
     {
         wrotePropertyAccess = false;
-        if (node?.TagHelper?.Name is null || node.Annotations["OriginalAttributeSpan"] is null)
+        if (node?.TagHelper?.Name is null || node.Annotations[ComponentMetadata.Common.OriginalAttributeSpan] is null)
         {
             return;
         }
@@ -683,7 +689,7 @@ private void WritePropertyAccess(CodeRenderingContext context, ComponentAttribut
             context.CodeWriter.WriteLine("#pragma warning disable BL0005");
         }
 
-        var attributeSourceSpan = (SourceSpan)node.Annotations["OriginalAttributeSpan"];
+        var attributeSourceSpan = (SourceSpan)node.Annotations[ComponentMetadata.Common.OriginalAttributeSpan];
         attributeSourceSpan = new SourceSpan(attributeSourceSpan.FilePath, attributeSourceSpan.AbsoluteIndex + offset, attributeSourceSpan.LineIndex, attributeSourceSpan.CharacterIndex + offset, node.PropertyName.Length, attributeSourceSpan.LineCount, attributeSourceSpan.CharacterIndex + offset + node.PropertyName.Length);
 
         if (componentNode.TypeInferenceNode == null)

src/Compiler/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentMetadata.cs

@@ -41,6 +41,10 @@ public static class Common
         public const string DirectiveAttribute = "Common.DirectiveAttribute";
 
         public const string AddAttributeMethodName = "Common.AddAttributeMethodName";
+
+        public const string OriginalAttributeSpan = "Common.OriginalAttributeSpan";
+
+        public const string IsDesignTimePropertyAccessHelper = "Common.IsDesignTimePropertyAccessHelper";
     }
 
     public static class Bind

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

@@ -326,6 +326,12 @@ protected List<TypeInferenceMethodParameter> GetTypeInferenceMethodParameters(Co
         {
             if (child is ComponentAttributeIntermediateNode attribute)
             {
+                // Some nodes just exist to help with property access at design time, and don't need anything else written
+                if (child.IsDesignTimePropertyAccessHelper())
+                {
+                    continue;
+                }
+
                 string typeName;
                 if (attribute.GloballyQualifiedTypeName != null)
                 {

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

@@ -547,6 +547,11 @@ public override void WriteComponentAttribute(CodeRenderingContext context, Compo
             throw new ArgumentNullException(nameof(node));
         }
 
+        if (node.IsDesignTimePropertyAccessHelper())
+        {
+            return;
+        }
+
         var addAttributeMethod = node.Annotations[ComponentMetadata.Common.AddAttributeMethodName] as string ?? AddComponentParameterMethodName;
 
         // _builder.AddComponentParameter(1, "Foo", 42);

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

@@ -1768,7 +1768,7 @@ public override void VisitMarkupMinimizedTagHelperAttribute(MarkupMinimizedTagHe
                             IsIndexerNameMatch = indexerMatch,
                         };
 
-                        setTagHelperProperty.Annotations.Add("OriginalAttributeSpan", BuildSourceSpanFromNode(node.Name));
+                        setTagHelperProperty.Annotations.Add(ComponentMetadata.Common.OriginalAttributeSpan, BuildSourceSpanFromNode(node.Name));
 
                         _builder.Add(setTagHelperProperty);
                     }
@@ -1909,7 +1909,7 @@ public override void VisitMarkupTagHelperAttribute(MarkupTagHelperAttributeSynta
                             IsIndexerNameMatch = indexerMatch,
                         };
 
-                        setTagHelperProperty.Annotations.Add("OriginalAttributeSpan", BuildSourceSpanFromNode(node.Name));
+                        setTagHelperProperty.Annotations.Add(ComponentMetadata.Common.OriginalAttributeSpan, BuildSourceSpanFromNode(node.Name));
 
                         _builder.Push(setTagHelperProperty);
                         VisitAttributeValue(attributeValueNode);
@@ -1988,7 +1988,7 @@ public override void VisitMarkupTagHelperDirectiveAttribute(MarkupTagHelperDirec
                             };
                         }
 
-                        attributeNode.Annotations.Add("OriginalAttributeSpan", BuildSourceSpanFromNode(node.Name));
+                        attributeNode.Annotations.Add(ComponentMetadata.Common.OriginalAttributeSpan, BuildSourceSpanFromNode(node.Name));
 
                         _builder.Push(attributeNode);
                         VisitAttributeValue(attributeValueNode);

src/Compiler/Microsoft.AspNetCore.Razor.Language/src/Intermediate/ComponentAttributeIntermediateNode.cs

@@ -25,6 +25,11 @@ public ComponentAttributeIntermediateNode(TagHelperHtmlAttributeIntermediateNode
         AttributeStructure = attributeNode.AttributeStructure;
         Source = attributeNode.Source;
 
+        foreach (var annotation in attributeNode.Annotations)
+        {
+            Annotations[annotation.Key] = annotation.Value;
+        }
+
         for (var i = 0; i < attributeNode.Children.Count; i++)
         {
             Children.Add(attributeNode.Children[i]);
@@ -115,6 +120,11 @@ public ComponentAttributeIntermediateNode(TagHelperDirectiveAttributeParameterIn
         TagHelper = directiveAttributeParameterNode.TagHelper;
         TypeName = directiveAttributeParameterNode.BoundAttributeParameter.TypeName;
 
+        foreach (var annotation in directiveAttributeParameterNode.Annotations)
+        {
+            Annotations[annotation.Key] = annotation.Value;
+        }
+
         for (var i = 0; i < directiveAttributeParameterNode.Children.Count; i++)
         {
             Children.Add(directiveAttributeParameterNode.Children[i]);

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

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Microsoft.AspNetCore.Razor.Language.Components;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate;
 
@@ -18,6 +19,13 @@ public static bool IsImported(this IntermediateNode node)
         return ReferenceEquals(node.Annotations[CommonAnnotations.Imported], CommonAnnotations.Imported);
     }
 
+    public static bool IsDesignTimePropertyAccessHelper(this IntermediateNode tagHelper)
+    {
+        return tagHelper.Annotations[ComponentMetadata.Common.IsDesignTimePropertyAccessHelper] is string text &&
+            bool.TryParse(text, out var result) &&
+            result;
+    }
+
     public static IReadOnlyList<RazorDiagnostic> GetAllDiagnostics(this IntermediateNode node)
     {
         if (node == null)

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

@@ -354,71 +354,6 @@ public class MyComponent : ComponentBase
         CompileToAssembly(generated);
     }
 
-    [Fact]
-    public void Component_WithWriteOnlyParameter()
-    {
-        // Arrange
-        AdditionalSyntaxTrees.Add(Parse("""
-            using Microsoft.AspNetCore.Components;
-
-            namespace Test
-            {
-                public class MyComponent : ComponentBase
-                {
-                    [Parameter]
-                    public int Prop { set { _ = value; } }
-                }
-            }
-            """));
-
-        // Act
-        var generated = CompileToCSharp("""
-            <MyComponent Prop="1">
-            </MyComponent>
-            """);
-
-        // Assert
-        AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
-        AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
-        CompileToAssembly(generated);
-    }
-
-    [Fact]
-    public void Component_WithInitOnlyParameter()
-    {
-        // Arrange
-        AdditionalSyntaxTrees.Add(Parse("""
-            namespace System.Runtime.CompilerServices;
-
-            internal static class IsExternalInit
-            {
-            }
-            """));
-        AdditionalSyntaxTrees.Add(Parse("""
-            using Microsoft.AspNetCore.Components;
-
-            namespace Test
-            {
-                public class MyComponent : ComponentBase
-                {
-                    [Parameter]
-                    public int Prop { get; init; }
-                }
-            }
-            """));
-
-        // Act
-        var generated = CompileToCSharp("""
-            <MyComponent Prop="1">
-            </MyComponent>
-            """);
-
-        // Assert
-        AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
-        AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
-        CompileToAssembly(generated);
-    }
-
     [Fact]
     public void ComponentWithTypeParameters_WithSemicolon()
     {

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

@@ -40,6 +40,15 @@ protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.
 #line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
                    Value
 
+#line default
+#line hidden
+#nullable disable
+             = default;
+            ((global::Test.MyComponent)default).
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                             Value
+
 #line default
 #line hidden
 #nullable disable

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

@@ -21,6 +21,9 @@
                     ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - OnChanged - OnChanged - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - __value => ParentValue = __value
+                    ComponentAttribute - (58:0,58 [9] x:\dir\subdir\Test\TestComponent.cshtml) - bind-Value - Value - AttributeStructure.DoubleQuotes
+                        HtmlContent - (58:0,58 [9] x:\dir\subdir\Test\TestComponent.cshtml)
+                            LazyIntermediateToken - (58:0,58 [9] x:\dir\subdir\Test\TestComponent.cshtml) - Html - OnChanged
                 HtmlContent - (71:0,71 [2] x:\dir\subdir\Test\TestComponent.cshtml)
                     LazyIntermediateToken - (71:0,71 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
             CSharpCode - (80:1,7 [50] x:\dir\subdir\Test\TestComponent.cshtml)

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

@@ -8,11 +8,16 @@ Source Location: (19:0,19 [5] x:\dir\subdir\Test\TestComponent.cshtml)
 Generated Location: (1544:40,19 [5] )
 |Value|
 
+Source Location: (45:0,45 [5] x:\dir\subdir\Test\TestComponent.cshtml)
+|Value|
+Generated Location: (1791:49,45 [5] )
+|Value|
+
 Source Location: (80:1,7 [50] x:\dir\subdir\Test\TestComponent.cshtml)
 |
     public int ParentValue { get; set; } = 42;
 |
-Generated Location: (1957:58,7 [50] )
+Generated Location: (2204:67,7 [50] )
 |
     public int ParentValue { get; set; } = 42;
 |

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

@@ -34,6 +34,26 @@ protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.
             __builder.AddAttribute(-1, "ChildContent", (global::Microsoft.AspNetCore.Components.RenderFragment)((__builder2) => {
             }
             ));
+            #pragma warning disable BL0005
+            ((global::Test.MyComponent)default).
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                   Value
+
+#line default
+#line hidden
+#nullable disable
+             = default;
+            ((global::Test.MyComponent)default).
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                                 Value
+
+#line default
+#line hidden
+#nullable disable
+             = default;
+            #pragma warning restore BL0005
 #nullable restore
 #line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
 __o = typeof(global::Test.MyComponent);

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

@@ -21,6 +21,8 @@
                     ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueChanged - ValueChanged - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - __value => { ParentValue = __value; global::Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.InvokeSynchronousDelegate(Update); }
+                    ComponentAttribute - (62:0,62 [6] x:\dir\subdir\Test\TestComponent.cshtml) - bind-Value - Value - AttributeStructure.DoubleQuotes
+                        LazyIntermediateToken - (62:0,62 [6] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - Update
                 HtmlContent - (72:0,72 [2] x:\dir\subdir\Test\TestComponent.cshtml)
                     LazyIntermediateToken - (72:0,72 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html - \n
             CSharpCode - (81:1,7 [82] x:\dir\subdir\Test\TestComponent.cshtml)