Clean up FieldDeclarationIntermediateNode

- Enable nullability
- Add constructor
- Remove unnecessary argument null check
- Change `Modifiers` property to return an `ImmutableArray<string>` rather than an `IList<string>` (backed by a `List<string>`).
- Change `SupressWarnings` property to return an `ImmutableArray<string>` rather than an `IList<string>` (backed by a `List<string>`).
- Make `FieldName`, `FieldType`, and `IsTagHelperField` properties read-only.

Author: DustinCampbell

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/CSharpCodeWriterTest.cs

@@ -303,7 +303,11 @@ public void WriteField_WritesFieldDeclaration()
         using var writer = new CodeWriter();
 
         // Act
-        writer.WriteField(Array.Empty<string>(), new[] { "private" }, "global::System.String", "_myString");
+        writer.WriteField(
+            suppressWarnings: [],
+            modifiers: ["private"],
+            typeName: "global::System.String",
+            fieldName: "_myString");
 
         // Assert
         var output = writer.GetText().ToString();
@@ -320,7 +324,11 @@ public void WriteField_WithModifiers_WritesFieldDeclaration()
         using var writer = new CodeWriter();
 
         // Act
-        writer.WriteField(Array.Empty<string>(), new[] { "private", "readonly", "static" }, "global::System.String", "_myString");
+        writer.WriteField(
+            suppressWarnings: [],
+            modifiers: ["private", "readonly", "static"],
+            typeName: "global::System.String",
+            fieldName: "_myString");
 
         // Assert
         var output = writer.GetText().ToString();
@@ -338,10 +346,10 @@ public void WriteField_WithModifiersAndSupressions_WritesFieldDeclaration()
 
         // Act
         writer.WriteField(
-            new[] { "0001", "0002", },
-            new[] { "private", "readonly", "static" },
-            "global::System.String",
-            "_myString");
+            suppressWarnings: ["0001", "0002"],
+            modifiers: ["private", "readonly", "static"],
+            typeName: "global::System.String",
+            fieldName: "_myString");
 
         // Assert
         var output = writer.GetText().ToString();
@@ -403,7 +411,7 @@ public void CSharpCodeWriter_RespectTabSetting()
 
         // Act
         context.BuildClassDeclaration(modifiers: [], "C", null, interfaces: [], typeParameters: []);
-        writer.WriteField(Array.Empty<string>(), Array.Empty<string>(), "int", "f");
+        writer.WriteField(suppressWarnings: [], modifiers: [], typeName: "int", fieldName: "f");
 
         // Assert
         var output = writer.GetText().ToString();
@@ -428,7 +436,7 @@ public void CSharpCodeWriter_RespectSpaceSetting()
 
         // Act
         context.BuildClassDeclaration(modifiers: [], "C", null, interfaces: [], typeParameters: []);
-        writer.WriteField(Array.Empty<string>(), Array.Empty<string>(), "int", "f");
+        writer.WriteField(suppressWarnings: [], modifiers: [], typeName: "int", fieldName: "f");
 
         // Assert
         var output = writer.GetText().ToString();

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/CodeGeneration/DefaultDocumentWriterTest.cs

@@ -367,16 +367,10 @@ public void WriteDocument_WritesField()
         // Arrange
         var document = new DocumentIntermediateNode();
         var builder = IntermediateNodeBuilder.Create(document);
-        builder.Add(new FieldDeclarationIntermediateNode()
-        {
-            Modifiers =
-                {
-                    "internal",
-                    "readonly",
-                },
-            FieldName = "_foo",
-            FieldType = "string",
-        });
+        builder.Add(new FieldDeclarationIntermediateNode(
+            fieldName: "_foo",
+            fieldType: "string",
+            modifiers: ["internal", "readonly"]));
 
         var codeDocument = TestRazorCodeDocument.CreateEmpty();
         var options = RazorCodeGenerationOptions.Default;

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/CodeGeneration/CodeWriterExtensions.cs

@@ -304,35 +304,20 @@ public static CodeWriter WriteStartInstanceMethodInvocation(this CodeWriter writ
             string.Format(CultureInfo.InvariantCulture, InstanceMethodFormat, instanceName, methodName));
     }
 
-    public static CodeWriter WriteField(this CodeWriter writer, IList<string> suppressWarnings, IList<string> modifiers, string typeName, string fieldName)
+    public static CodeWriter WriteField(
+        this CodeWriter writer,
+        ImmutableArray<string> suppressWarnings,
+        ImmutableArray<string> modifiers,
+        string typeName,
+        string fieldName)
     {
-        if (suppressWarnings == null)
-        {
-            throw new ArgumentNullException(nameof(suppressWarnings));
-        }
-
-        if (modifiers == null)
-        {
-            throw new ArgumentNullException(nameof(modifiers));
-        }
-
-        if (typeName == null)
-        {
-            throw new ArgumentNullException(nameof(typeName));
-        }
-
-        if (fieldName == null)
-        {
-            throw new ArgumentNullException(nameof(fieldName));
-        }
-
-        for (var i = 0; i < suppressWarnings.Count; i++)
+        for (var i = 0; i < suppressWarnings.Length; i++)
         {
             writer.Write("#pragma warning disable ");
             writer.WriteLine(suppressWarnings[i]);
         }
 
-        for (var i = 0; i < modifiers.Count; i++)
+        for (var i = 0; i < modifiers.Length; i++)
         {
             writer.Write(modifiers[i]);
             writer.Write(" ");
@@ -344,7 +329,7 @@ public static CodeWriter WriteField(this CodeWriter writer, IList<string> suppre
         writer.Write(";");
         writer.WriteLine();
 
-        for (var i = suppressWarnings.Count - 1; i >= 0; i--)
+        for (var i = suppressWarnings.Length - 1; i >= 0; i--)
         {
             writer.Write("#pragma warning restore ");
             writer.WriteLine(suppressWarnings[i]);

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/DefaultTagHelperOptimizationPass.cs

@@ -191,16 +191,13 @@ private void AddField(Context context, TagHelperDescriptor tagHelper)
             i++;
         }
 
-        context.Class.Children.Insert(i, new FieldDeclarationIntermediateNode()
-        {
-            IsTagHelperField = true,
-            Modifiers =
-                {
-                    "private",
-                },
-            FieldName = context.GetFieldName(tagHelper),
-            FieldType = "global::" + tagHelper.GetTypeName(),
-        });
+        var fieldNode = new FieldDeclarationIntermediateNode(
+            fieldName: context.GetFieldName(tagHelper),
+            fieldType: "global::" + tagHelper.GetTypeName(),
+            modifiers: ["private"],
+            isTagHelperField: true);
+
+        context.Class.Children.Insert(i, fieldNode);
     }
 
     private bool IsTagHelperRuntimeNode(TagHelperIntermediateNode node)

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/DefaultTagHelperTargetExtension.cs

@@ -4,6 +4,7 @@
 #nullable disable
 
 using System;
+using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Globalization;
 using System.Linq;
@@ -15,11 +16,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions;
 
 internal sealed class DefaultTagHelperTargetExtension : IDefaultTagHelperTargetExtension
 {
-    private static readonly string[] FieldUnintializedModifiers = { "0649", };
+    private static readonly ImmutableArray<string> s_fieldUninitializedWarnings = ["0649"];
 
-    private static readonly string[] FieldUnusedModifiers = { "0169", };
+    private static readonly ImmutableArray<string> s_fieldUnusedWarnings = ["0169"];
 
-    private static readonly string[] PrivateModifiers = new string[] { "private" };
+    private static readonly ImmutableArray<string> s_privateModifiers = ["private"];
 
     public string RunnerVariableName { get; set; } = "__tagHelperRunner";
 
@@ -102,7 +103,7 @@ public void WriteTagHelperBody(CodeRenderingContext context, DefaultTagHelperBod
             // 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 = GetDeterministicId(context);
-            
+
             context.CodeWriter.WriteStringLiteral(node.TagName)
                 .WriteParameterSeparator()
                 .Write(TagModeTypeName)
@@ -474,7 +475,7 @@ public void WriteTagHelperProperty(CodeRenderingContext context, DefaultTagHelpe
     public void WriteTagHelperRuntime(CodeRenderingContext context, DefaultTagHelperRuntimeIntermediateNode node)
     {
         context.CodeWriter.WriteLine("#line hidden");
-        context.CodeWriter.WriteField(FieldUnintializedModifiers, PrivateModifiers, ExecutionContextTypeName, ExecutionContextVariableName);
+        context.CodeWriter.WriteField(s_fieldUninitializedWarnings, s_privateModifiers, ExecutionContextTypeName, ExecutionContextVariableName);
 
         context.CodeWriter
             .Write("private ")
@@ -487,7 +488,7 @@ public void WriteTagHelperRuntime(CodeRenderingContext context, DefaultTagHelper
 
         if (!context.Options.DesignTime)
         {
-            context.CodeWriter.WriteField(FieldUnusedModifiers, PrivateModifiers, "string", StringValueBufferVariableName);
+            context.CodeWriter.WriteField(s_fieldUnusedWarnings, s_privateModifiers, "string", StringValueBufferVariableName);
 
             var backedScopeManageVariableName = "__backed" + ScopeManagerVariableName;
             context.CodeWriter

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Intermediate/FieldDeclarationIntermediateNode.cs

@@ -1,37 +1,39 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
-using System;
-using System.Collections.Generic;
+using System.Collections.Immutable;
 
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate;
 
-public sealed class FieldDeclarationIntermediateNode : MemberDeclarationIntermediateNode
+public sealed class FieldDeclarationIntermediateNode(
+    string fieldName,
+    string fieldType,
+    ImmutableArray<string> modifiers,
+    ImmutableArray<string> suppressWarnings,
+    bool isTagHelperField = false) : MemberDeclarationIntermediateNode
 {
-    public override IntermediateNodeCollection Children => IntermediateNodeCollection.ReadOnly;
-
-    public IList<string> Modifiers { get; } = new List<string>();
+    public string FieldName { get; } = fieldName;
+    public string FieldType { get; } = fieldType;
 
-    public IList<string> SuppressWarnings { get; } = new List<string>();
+    public bool IsTagHelperField { get; } = isTagHelperField;
 
-    public string FieldName { get; set; }
+    public ImmutableArray<string> Modifiers { get; } = modifiers.NullToEmpty();
+    public ImmutableArray<string> SuppressWarnings { get; } = suppressWarnings.NullToEmpty();
 
-    public string FieldType { get; set; }
-
-    public bool IsTagHelperField { get; set; }
+    public override IntermediateNodeCollection Children => IntermediateNodeCollection.ReadOnly;
 
-    public override void Accept(IntermediateNodeVisitor visitor)
+    public FieldDeclarationIntermediateNode(
+        string fieldName,
+        string fieldType,
+        ImmutableArray<string> modifiers,
+        bool isTagHelperField = false)
+        : this(fieldName, fieldType, modifiers, suppressWarnings: [], isTagHelperField)
     {
-        if (visitor == null)
-        {
-            throw new ArgumentNullException(nameof(visitor));
-        }
-
-        visitor.VisitFieldDeclaration(this);
     }
 
+    public override void Accept(IntermediateNodeVisitor visitor)
+        => visitor.VisitFieldDeclaration(this);
+
     public override void FormatNode(IntermediateNodeFormatter formatter)
     {
         formatter.WriteContent(FieldName);

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Intermediate/MemberDeclarationIntermediateNode.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#nullable disable
-
 namespace Microsoft.AspNetCore.Razor.Language.Intermediate;
 
 public abstract class MemberDeclarationIntermediateNode : IntermediateNode

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Mvc/ViewComponentTagHelperPass.cs

@@ -123,16 +123,13 @@ private void AddField(Context context, TagHelperDescriptor tagHelper)
             i++;
         }
 
-        context.Class.Children.Insert(i, new FieldDeclarationIntermediateNode()
-        {
-            IsTagHelperField = true,
-            Modifiers =
-                {
-                    "private",
-                },
-            FieldName = context.GetFieldName(tagHelper),
-            FieldType = "global::" + context.GetFullyQualifiedName(tagHelper),
-        });
+        var fieldNode = new FieldDeclarationIntermediateNode(
+            fieldName: context.GetFieldName(tagHelper),
+            fieldType: "global::" + context.GetFullyQualifiedName(tagHelper),
+            modifiers: ["private"],
+            isTagHelperField: true);
+
+        context.Class.Children.Insert(i, fieldNode);
     }
 
     private void AddTagHelperClass(Context context, TagHelperDescriptor tagHelper)