Fix up compiler passes using FindDescendantNodes

Now that `FindDirectiveReferences` returns an `ImmutableArray`, several compiler passes need to be adjusted.

- Use `Length` rather than `Count`.
- Prefer foreach statements now that we're not contending with an `IReadOnlyList`.
- Enable nullability where it was trivial.

Author: DustinCampbell

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

@@ -1097,12 +1097,12 @@ private void RewriteNodesForElementEventCallbackBind(
     private static IntermediateToken GetAttributeContent(IntermediateNode node)
     {
         var nodes = node.FindDescendantNodes<TemplateIntermediateNode>();
-        var template = nodes.Count > 0 ? nodes[0] : default;
+        var template = nodes.Length > 0 ? nodes[0] : default;
         if (template != null)
         {
             // See comments in TemplateDiagnosticPass
             node.AddDiagnostic(ComponentDiagnosticFactory.Create_TemplateInvalidLocation(template.Source));
-            return new IntermediateToken() { Kind = TokenKind.CSharp, Content = string.Empty, };
+            return new IntermediateToken() { Kind = TokenKind.CSharp, Content = string.Empty };
         }
 
         if (node.Children[0] is HtmlContentIntermediateNode htmlContentNode)

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentComplexAttributeContentPass.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
-
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
@@ -25,10 +23,9 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
             return;
         }
 
-        var nodes = documentNode.FindDescendantNodes<TagHelperIntermediateNode>();
-        for (var i = 0; i < nodes.Count; i++)
+        foreach (var node in documentNode.FindDescendantNodes<TagHelperIntermediateNode>())
         {
-            ProcessAttributes(nodes[i]);
+            ProcessAttributes(node);
         }
     }
 

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentCssScopePass.cs

@@ -24,21 +24,15 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
             return;
         }
 
-        var nodes = documentNode.FindDescendantNodes<MarkupElementIntermediateNode>();
-        for (var i = 0; i < nodes.Count; i++)
+        foreach (var node in documentNode.FindDescendantNodes<MarkupElementIntermediateNode>())
         {
-            ProcessElement(nodes[i], cssScope);
+            // Add a minimized attribute whose name is simply the CSS scope
+            node.Children.Add(new HtmlAttributeIntermediateNode
+            {
+                AttributeName = cssScope,
+                Prefix = cssScope,
+                Suffix = string.Empty,
+            });
         }
     }
-
-    private void ProcessElement(MarkupElementIntermediateNode node, string cssScope)
-    {
-        // Add a minimized attribute whose name is simply the CSS scope
-        node.Children.Add(new HtmlAttributeIntermediateNode
-        {
-            AttributeName = cssScope,
-            Prefix = cssScope,
-            Suffix = string.Empty,
-        });
-    }
 }

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentDesignTimeNodeWriter.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
-
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -104,7 +102,7 @@ public override void WriteCSharpExpression(CodeRenderingContext context, CSharpE
         WriteCSharpExpressionInnards(context, node);
     }
 
-    private void WriteCSharpExpressionInnards(CodeRenderingContext context, CSharpExpressionIntermediateNode node, string type = null)
+    private void WriteCSharpExpressionInnards(CodeRenderingContext context, CSharpExpressionIntermediateNode node, string? type = null)
     {
         if (node.Children.Count == 0)
         {
@@ -191,7 +189,7 @@ public override void WriteCSharpCode(CodeRenderingContext context, CSharpCodeInt
             }
         }
 
-        IDisposable linePragmaScope = null;
+        IDisposable? linePragmaScope = null;
         if (node.Source != null)
         {
             if (!isWhitespaceStatement)
@@ -372,7 +370,7 @@ public override void WriteComponent(CodeRenderingContext context, ComponentInter
 
         // We might need a scope for inferring types,
         CodeWriterExtensions.CSharpCodeWritingScope? typeInferenceCaptureScope = null;
-        string typeInferenceLocalName = null;
+        string? typeInferenceLocalName = null;
 
         var suppressTypeInference = ShouldSuppressTypeInferenceCall(node);
         if (suppressTypeInference)
@@ -563,7 +561,7 @@ public override void WriteComponent(CodeRenderingContext context, ComponentInter
         // the "usings directive is unnecessary" message.
         // Looks like:
         // __o = typeof(SomeNamespace.SomeComponent);
-        using (context.CodeWriter.BuildLinePragma(node.Source.Value, context))
+        using (context.CodeWriter.BuildLinePragma(node.Source.AssumeNotNull(), context))
         {
             context.CodeWriter.Write(DesignTimeVariable);
             context.CodeWriter.Write(" = ");
@@ -677,7 +675,7 @@ public override void WriteComponentAttribute(CodeRenderingContext context, Compo
         context.CodeWriter.WriteLine();
     }
 
-    private void WritePropertyAccess(CodeRenderingContext context, ComponentAttributeIntermediateNode node, ComponentIntermediateNode componentNode, string typeInferenceLocalName, bool shouldWriteBL0005Disable, out bool wrotePropertyAccess)
+    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.OriginalAttributeSpan is null)

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentEventHandlerLoweringPass.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
@@ -156,7 +157,7 @@ private static void ProcessDuplicates(IntermediateNode parent)
     private static IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperDirectiveAttributeIntermediateNode node)
     {
         var original = GetAttributeContent(node);
-        if (original.Count == 0)
+        if (original.Length == 0)
         {
             // This can happen in error cases, the parser will already have flagged this
             // as an error, so ignore it.
@@ -171,8 +172,8 @@ private static IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperD
         // correct context for intellisense when typing in the attribute.
         var eventArgsType = node.TagHelper.GetEventArgsType();
 
-        using var _ = ListPool<IntermediateToken>.GetPooledObject(out var tokens);
-        tokens.SetCapacityIfLarger(original.Count + 2);
+        using var tokens = new PooledArrayBuilder<IntermediateToken>(original.Length + 2);
+        tokens.SetCapacityIfLarger(original.Length + 2);
 
         tokens.Add(
             new IntermediateToken()
@@ -181,10 +182,7 @@ private static IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperD
                 Kind = TokenKind.CSharp
             });
 
-        for (var i = 0; i < original.Count; i++)
-        {
-            tokens.Add(original[i]);
-        }
+        tokens.AddRange(original);
 
         tokens.Add(
             new IntermediateToken()
@@ -240,15 +238,15 @@ private static IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperD
         }
     }
 
-    private static IReadOnlyList<IntermediateToken> GetAttributeContent(IntermediateNode node)
+    private static ImmutableArray<IntermediateToken> GetAttributeContent(IntermediateNode node)
     {
         var nodes = node.FindDescendantNodes<TemplateIntermediateNode>();
-        var template = nodes.Count > 0 ? nodes[0] : default;
+        var template = nodes.Length > 0 ? nodes[0] : null;
         if (template != null)
         {
             // See comments in TemplateDiagnosticPass
             node.AddDiagnostic(ComponentDiagnosticFactory.Create_TemplateInvalidLocation(template.Source));
-            return new[] { new IntermediateToken() { Kind = TokenKind.CSharp, Content = string.Empty, }, };
+            return [new IntermediateToken() { Kind = TokenKind.CSharp, Content = string.Empty }];
         }
 
         if (node.Children.Count == 1 && node.Children[0] is HtmlContentIntermediateNode htmlContentNode)
@@ -258,12 +256,10 @@ private static IReadOnlyList<IntermediateToken> GetAttributeContent(Intermediate
             var tokens = htmlContentNode.FindDescendantNodes<IntermediateToken>();
 
             var content = "\"" + string.Join(string.Empty, tokens.Select(t => t.Content.Replace("\"", "\\\""))) + "\"";
-            return new[] { new IntermediateToken() { Content = content, Kind = TokenKind.CSharp, } };
-        }
-        else
-        {
-            return node.FindDescendantNodes<IntermediateToken>();
+            return [new IntermediateToken() { Content = content, Kind = TokenKind.CSharp }];
         }
+
+        return node.FindDescendantNodes<IntermediateToken>();
     }
 
     private static IntermediateNode RewriteParameterUsage(TagHelperDirectiveAttributeParameterIntermediateNode node)

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentRuntimeNodeWriter.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
-
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Components/ComponentSplatLoweringPass.cs

@@ -18,9 +18,7 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
             return;
         }
 
-        var references = documentNode.FindDescendantReferences<TagHelperDirectiveAttributeIntermediateNode>();
-
-        foreach (var reference in references)
+        foreach (var reference in documentNode.FindDescendantReferences<TagHelperDirectiveAttributeIntermediateNode>())
         {
             var node = (TagHelperDirectiveAttributeIntermediateNode)reference.Node;
             if (node.TagHelper.IsSplatTagHelper())

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/DefaultTagHelperOptimizationPass.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
-
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/ViewCssScopePass.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
-
 using System;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 
@@ -28,23 +26,22 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
         }
 
         var scopeWithSeparator = " " + cssScope;
-        var nodes = documentNode.FindDescendantNodes<HtmlContentIntermediateNode>();
-        IntermediateToken previousTokenOpt = null;
-        foreach (var node in nodes)
+        IntermediateToken? previousToken = null;
+        foreach (var node in documentNode.FindDescendantNodes<HtmlContentIntermediateNode>())
         {
-            ProcessElement(node, scopeWithSeparator, ref previousTokenOpt);
+            ProcessElement(node, scopeWithSeparator, ref previousToken);
         }
     }
 
-    private void ProcessElement(HtmlContentIntermediateNode node, string cssScope, ref IntermediateToken previousTokenOpt)
+    private void ProcessElement(HtmlContentIntermediateNode node, string cssScope, ref IntermediateToken? previousToken)
     {
         // Add a minimized attribute whose name is simply the CSS scope
         for (var i = 0; i < node.Children.Count; i++)
         {
             var child = node.Children[i];
             if (child is IntermediateToken token && token.IsHtml)
             {
-                if (IsValidElement(token, previousTokenOpt))
+                if (IsValidElement(token, previousToken))
                 {
                     node.Children.Insert(i + 1, new IntermediateToken()
                     {
@@ -55,16 +52,16 @@ private void ProcessElement(HtmlContentIntermediateNode node, string cssScope, r
                     i++;
                 }
 
-                previousTokenOpt = token;
+                previousToken = token;
             }
         }
 
-        static bool IsValidElement(IntermediateToken token, IntermediateToken previousTokenOpt)
+        static bool IsValidElement(IntermediateToken token, IntermediateToken? previousToken)
         {
             var content = token.Content.AsSpan();
 
             // `<!tag` is lowered into separate nodes `<` and `tag`, we process the latter.
-            if (previousTokenOpt?.Content == "<" && content is [not '<', ..])
+            if (previousToken?.Content == "<" && content is [not '<', ..])
             {
                 // There is no leading `<` to trim.
             }

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Mvc/ViewComponentTagHelperPass.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
-
 using System.Collections.Generic;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
@@ -36,10 +34,8 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
 
         // 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++)
+        foreach (var node in documentNode.FindDescendantNodes<TagHelperIntermediateNode>())
         {
-            var node = nodes[i];
             foreach (var tagHelper in node.TagHelpers)
             {
                 RewriteUsage(context, node, tagHelper);