Clean up RewrittenSyntaxTree naming and null handling in DefaultTagHelperResolutionPhase

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/DefaultRazorTagHelperBinderPhaseTest.cs

@@ -489,7 +489,7 @@ public void Execute_CombinesErrorsOnRewritingErrors()
         codeDocument = projectEngine.ExecutePhase<DefaultRazorTagHelperRewritePhase>(codeDocument);
 
         // Assert
-        var outputTree = codeDocument.GetSyntaxTree();
+        var outputTree = codeDocument.GetTagHelperRewrittenSyntaxTree();
         Assert.Empty(originalTree.Diagnostics);
         Assert.NotSame(erroredOriginalTree, outputTree);
         Assert.Equal<RazorDiagnostic>([initialError, expectedRewritingError], outputTree.Diagnostics);

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

@@ -36,7 +36,9 @@ internal class DefaultRazorIntermediateNodeLoweringPhase : RazorEnginePhaseBase,
 {
     protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument, CancellationToken cancellationToken)
     {
-        var syntaxTree = codeDocument.GetPreTagHelperSyntaxTree() ?? codeDocument.GetSyntaxTree();
+        // The canonical syntax tree is established by DefaultRazorTagHelperContextDiscoveryPhase,
+        // which always runs before this phase in the pipeline.
+        var syntaxTree = codeDocument.GetSyntaxTree();
         ThrowForMissingDocumentDependency(syntaxTree);
 
         var documentNode = new DocumentIntermediateNode();

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultRazorTagHelperContextDiscoveryPhase.cs

@@ -18,7 +18,8 @@ internal sealed partial class DefaultRazorTagHelperContextDiscoveryPhase : Razor
 {
     protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument, CancellationToken cancellationToken)
     {
-        var syntaxTree = codeDocument.GetPreTagHelperSyntaxTree() ?? codeDocument.GetSyntaxTree();
+        // The canonical syntax tree is established by DefaultRazorParsingPhase (which runs before this phase).
+        var syntaxTree = codeDocument.GetSyntaxTree();
         ThrowForMissingDocumentDependency(syntaxTree);
 
         if (!codeDocument.TryGetTagHelpers(out var tagHelpers))
@@ -56,7 +57,6 @@ protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument,
         var context = TagHelperDocumentContext.GetOrCreate(tagHelperPrefix, visitor.GetResults());
         return codeDocument
             .WithTagHelperContext(context)
-            .WithPreTagHelperSyntaxTree(syntaxTree)
             .WithDirectiveTagHelperContributions(directiveContributions);
     }
 

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultRazorTagHelperRewritePhase.cs

@@ -10,21 +10,28 @@ internal sealed class DefaultRazorTagHelperRewritePhase : RazorEnginePhaseBase
 {
     protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument, CancellationToken cancellationToken)
     {
-        if (!codeDocument.TryGetPreTagHelperSyntaxTree(out var syntaxTree) ||
-            !codeDocument.TryGetTagHelperContext(out var context) ||
-            context.TagHelpers is [])
+        if (!codeDocument.TryGetSyntaxTree(out var syntaxTree))
         {
-            // No descriptors, so no need to see if any are used. Without setting this though,
-            // we trigger an Assert in the ProcessRemaining method in the source generator.
             return codeDocument.WithReferencedTagHelpers([]);
         }
 
+        if (!codeDocument.TryGetTagHelperContext(out var context) ||
+            context.TagHelpers is [])
+        {
+            // No tag helpers to rewrite. The rewritten tree is the same as the canonical tree.
+            // Tooling in the workspaces layer always expects GetRequiredTagHelperRewrittenSyntaxTree()
+            // to return a non-null value after the full pipeline has run.
+            return codeDocument
+                .WithReferencedTagHelpers([])
+                .WithTagHelperRewrittenSyntaxTree(syntaxTree);
+        }
+
         var binder = context.GetBinder();
         using var usedHelpers = new TagHelperCollection.Builder();
         var rewrittenSyntaxTree = TagHelperParseTreeRewriter.Rewrite(syntaxTree, binder, usedHelpers, cancellationToken);
 
         return codeDocument
             .WithReferencedTagHelpers(usedHelpers.ToCollection())
-            .WithSyntaxTree(rewrittenSyntaxTree);
+            .WithTagHelperRewrittenSyntaxTree(rewrittenSyntaxTree);
     }
 }

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultTagHelperResolutionPhase.cs

@@ -40,14 +40,17 @@ protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument,
         }
 
         var tagHelperContext = codeDocument.GetTagHelperContext();
-        var syntaxTree = codeDocument.GetPreTagHelperSyntaxTree() ?? codeDocument.GetSyntaxTree();
-        var parserOptions = syntaxTree?.Options;
+
+        // This phase works with IR nodes only -- no syntax tree access needed.
+        // RazorCodeDocument.ParserOptions is a non-nullable property initialized by Create(),
+        // so it is always available here.
+        var parserOptions = codeDocument.ParserOptions;
 
         // Choose resolver based on file kind and language version. Component features
         // (MarkupElementIntermediateNode, RZ10012 diagnostics) require Version_3_0+ because
         // the ComponentDocumentClassifierPass is only registered at that version.
         _resolver = (codeDocument.FileKind.IsComponent() || codeDocument.FileKind.IsComponentImport())
-            && parserOptions?.LanguageVersion >= RazorLanguageVersion.Version_3_0
+            && parserOptions.LanguageVersion >= RazorLanguageVersion.Version_3_0
             ? new ComponentTagHelperResolver()
             : new LegacyTagHelperResolver();
 
@@ -65,7 +68,7 @@ protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument,
 
         using var usedHelpers = new TagHelperCollection.Builder();
         var sourceDocument = codeDocument.Source;
-        var context = new ResolutionContext(sourceDocument, parserOptions, documentNode);
+        var context = new ResolutionContext(sourceDocument, documentNode);
         ResolveElements(documentNode, binder, prefix, usedHelpers, in context);
 
         // Add tag helper descriptor validation diagnostics (e.g. RZ3003).
@@ -90,13 +93,11 @@ protected override RazorCodeDocument ExecuteCore(RazorCodeDocument codeDocument,
     private readonly struct ResolutionContext
     {
         public readonly RazorSourceDocument SourceDocument;
-        public readonly RazorParserOptions ParserOptions;
         public readonly DocumentIntermediateNode DocumentNode;
 
-        public ResolutionContext(RazorSourceDocument sourceDocument, RazorParserOptions parserOptions, DocumentIntermediateNode documentNode)
+        public ResolutionContext(RazorSourceDocument sourceDocument, DocumentIntermediateNode documentNode)
         {
             SourceDocument = sourceDocument;
-            ParserOptions = parserOptions;
             DocumentNode = documentNode;
         }
     }

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/RazorCodeDocument.cs

@@ -23,8 +23,14 @@ public sealed partial class RazorCodeDocument
 
     private readonly TagHelperCollection? _tagHelpers;
     private readonly TagHelperCollection? _referencedTagHelpers;
-    private readonly RazorSyntaxTree? _preTagHelperSyntaxTree;
+    // The canonical syntax tree produced by parsing and syntax-tree passes, before tag helper rewriting.
+    // Established by DefaultRazorTagHelperContextDiscoveryPhase (which reads it from _tagHelperRewrittenSyntaxTree
+    // on the first run). Once set, this field is stable throughout the rest of the pipeline.
     private readonly RazorSyntaxTree? _syntaxTree;
+    // The working syntax tree: initially set by DefaultRazorParsingPhase (same value as _syntaxTree),
+    // updated by DefaultRazorSyntaxTreePhase, and finally replaced with the tag-helper-rewritten tree
+    // by DefaultRazorTagHelperRewritePhase.
+    private readonly RazorSyntaxTree? _tagHelperRewrittenSyntaxTree;
     private readonly ImmutableArray<RazorSyntaxTree> _importSyntaxTrees;
     private readonly TagHelperDocumentContext? _tagHelperContext;
     private readonly DocumentIntermediateNode? _documentNode;
@@ -38,8 +44,8 @@ private RazorCodeDocument(
         RazorCodeGenerationOptions codeGenerationOptions,
         TagHelperCollection? tagHelpers,
         TagHelperCollection? referencedTagHelpers,
-        RazorSyntaxTree? preTagHelperSyntaxTree,
         RazorSyntaxTree? syntaxTree,
+        RazorSyntaxTree? tagHelperRewrittenSyntaxTree,
         ImmutableArray<RazorSyntaxTree> importSyntaxTrees,
         TagHelperDocumentContext? tagHelperContext,
         DocumentIntermediateNode? documentNode,
@@ -54,8 +60,8 @@ private RazorCodeDocument(
 
         _tagHelpers = tagHelpers;
         _referencedTagHelpers = referencedTagHelpers;
-        _preTagHelperSyntaxTree = preTagHelperSyntaxTree;
         _syntaxTree = syntaxTree;
+        _tagHelperRewrittenSyntaxTree = tagHelperRewrittenSyntaxTree;
         _importSyntaxTrees = importSyntaxTrees;
         _tagHelperContext = tagHelperContext;
         _documentNode = documentNode;
@@ -84,8 +90,8 @@ public static RazorCodeDocument Create(
             codeGenerationOptions ?? RazorCodeGenerationOptions.Default,
             tagHelpers: null,
             referencedTagHelpers: null,
-            preTagHelperSyntaxTree: null,
             syntaxTree: null,
+            tagHelperRewrittenSyntaxTree: null,
             importSyntaxTrees: default,
             tagHelperContext: null,
             documentNode: null,
@@ -111,7 +117,7 @@ internal RazorCodeDocument WithTagHelpers(TagHelperCollection? value)
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, value, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, value, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
     internal bool TryGetReferencedTagHelpers([NotNullWhen(true)] out TagHelperCollection? result)
@@ -132,50 +138,51 @@ internal RazorCodeDocument WithReferencedTagHelpers(TagHelperCollection value)
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, value, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, value, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
-    internal bool TryGetPreTagHelperSyntaxTree([NotNullWhen(true)] out RazorSyntaxTree? result)
+    internal bool TryGetSyntaxTree([NotNullWhen(true)] out RazorSyntaxTree? result)
     {
-        result = _preTagHelperSyntaxTree;
+        result = _syntaxTree;
         return result is not null;
     }
 
-    internal RazorSyntaxTree? GetPreTagHelperSyntaxTree()
-        => _preTagHelperSyntaxTree;
+    internal RazorSyntaxTree? GetSyntaxTree()
+        => _syntaxTree;
 
-    internal RazorSyntaxTree GetRequiredPreTagHelperSyntaxTree()
-        => _preTagHelperSyntaxTree.AssumeNotNull();
+    internal RazorSyntaxTree GetRequiredSyntaxTree()
+        => _syntaxTree.AssumeNotNull();
 
-    internal RazorCodeDocument WithPreTagHelperSyntaxTree(RazorSyntaxTree? value)
+    internal RazorCodeDocument WithSyntaxTree(RazorSyntaxTree value)
     {
-        if (ReferenceEquals(value, _preTagHelperSyntaxTree))
+        Debug.Assert(value is not null);
+        if (ReferenceEquals(value, _syntaxTree))
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, value, _syntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, value, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
-    internal bool TryGetSyntaxTree([NotNullWhen(true)] out RazorSyntaxTree? result)
+    internal bool TryGetTagHelperRewrittenSyntaxTree([NotNullWhen(true)] out RazorSyntaxTree? result)
     {
-        result = _syntaxTree;
+        result = _tagHelperRewrittenSyntaxTree;
         return result is not null;
     }
 
-    internal RazorSyntaxTree? GetSyntaxTree()
-        => _syntaxTree;
+    internal RazorSyntaxTree? GetTagHelperRewrittenSyntaxTree()
+        => _tagHelperRewrittenSyntaxTree;
 
-    internal RazorSyntaxTree GetRequiredSyntaxTree()
-        => _syntaxTree.AssumeNotNull();
+    internal RazorSyntaxTree GetRequiredTagHelperRewrittenSyntaxTree()
+        => _tagHelperRewrittenSyntaxTree.AssumeNotNull();
 
-    internal RazorCodeDocument WithSyntaxTree(RazorSyntaxTree value)
+    internal RazorCodeDocument WithTagHelperRewrittenSyntaxTree(RazorSyntaxTree value)
     {
         Debug.Assert(value is not null);
-        if (ReferenceEquals(value, _syntaxTree))
+        if (ReferenceEquals(value, _tagHelperRewrittenSyntaxTree))
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, value, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, value, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
     internal bool TryGetImportSyntaxTrees(out ImmutableArray<RazorSyntaxTree> result)
@@ -202,7 +209,7 @@ internal RazorCodeDocument WithImportSyntaxTrees(ImmutableArray<RazorSyntaxTree>
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, value, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, value, _tagHelperContext, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
     internal bool TryGetTagHelperContext([NotNullWhen(true)] out TagHelperDocumentContext? result)
@@ -225,7 +232,7 @@ internal RazorCodeDocument WithTagHelperContext(TagHelperDocumentContext value)
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, value, _documentNode, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, value, _documentNode, _csharpDocument, _directiveTagHelperContributions);
     }
 
     internal bool TryGetDocumentNode([NotNullWhen(true)] out DocumentIntermediateNode? result)
@@ -247,7 +254,7 @@ internal RazorCodeDocument WithDocumentNode(DocumentIntermediateNode value)
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, _tagHelperContext, value, _csharpDocument, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, value, _csharpDocument, _directiveTagHelperContributions);
     }
 
     internal bool TryGetCSharpDocument([NotNullWhen(true)] out RazorCSharpDocument? result)
@@ -269,7 +276,7 @@ internal RazorCodeDocument WithCSharpDocument(RazorCSharpDocument value)
         {
             return this;
         }
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, value, _directiveTagHelperContributions);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, value, _directiveTagHelperContributions);
     }
 
     internal ImmutableArray<DirectiveTagHelperContribution> GetDirectiveTagHelperContributions()
@@ -282,7 +289,7 @@ internal RazorCodeDocument WithDirectiveTagHelperContributions(ImmutableArray<Di
             return this;
         }
 
-        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _preTagHelperSyntaxTree, _syntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, value);
+        return new RazorCodeDocument(Source, Imports, ParserOptions, CodeGenerationOptions, _tagHelpers, _referencedTagHelpers, _syntaxTree, _tagHelperRewrittenSyntaxTree, _importSyntaxTrees, _tagHelperContext, _documentNode, _csharpDocument, value);
     }
 
     // In general documents will have a relative path (relative to the project root).

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/RazorHtmlWriter.cs

@@ -44,7 +44,7 @@ public static RazorHtmlDocument GetHtmlDocument(RazorCodeDocument codeDocument)
         using var codeWriter = new CodeWriter(options);
 
         var htmlWriter = new RazorHtmlWriter(source, codeWriter);
-        var syntaxTree = codeDocument.GetRequiredSyntaxTree();
+        var syntaxTree = codeDocument.GetRequiredTagHelperRewrittenSyntaxTree();
 
         htmlWriter.Visit(syntaxTree);
 

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/SourceGenerators/SourceGeneratorProjectEngine.cs

@@ -58,8 +58,8 @@ public SourceGeneratorRazorCodeDocument ProcessInitialParse(RazorProjectItem pro
 
         codeDocument = ExecutePhases(Phases[.._discoveryPhaseIndex], codeDocument, cancellationToken);
 
-        // record the syntax tree, before the tag helper re-writing occurs
-        codeDocument = codeDocument.WithPreTagHelperSyntaxTree(codeDocument.GetSyntaxTree());
+        // By this point, DefaultRazorParsingPhase has set the canonical syntax tree (_syntaxTree)
+        // so that discovery and subsequent phases can read it via GetSyntaxTree().
         return new SourceGeneratorRazorCodeDocument(codeDocument);
     }
 
@@ -69,7 +69,7 @@ public SourceGeneratorRazorCodeDocument ProcessTagHelpers(
         bool checkForIdempotency, 
         CancellationToken cancellationToken)
     {
-        Debug.Assert(sgDocument.CodeDocument.GetPreTagHelperSyntaxTree() is not null);
+        Debug.Assert(sgDocument.CodeDocument.GetSyntaxTree() is not null);
 
         int startIndex = _discoveryPhaseIndex;
         var codeDocument = sgDocument.CodeDocument;

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/ExtractToComponentCodeActionProvider.cs

@@ -39,7 +39,7 @@ public Task<ImmutableArray<RazorVSInternalCodeAction>> ProvideAsync(RazorCodeAct
             return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
         }
 
-        if (!context.CodeDocument.TryGetSyntaxTree(out var syntaxTree))
+        if (!context.CodeDocument.TryGetTagHelperRewrittenSyntaxTree(out var syntaxTree))
         {
             return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
         }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/ExtractToComponentCodeActionResolver.cs

@@ -57,7 +57,7 @@ internal class ExtractToComponentCodeActionResolver(
             builder.AppendLine();
         }
 
-        var syntaxTree = componentDocument.GetRequiredSyntaxTree();
+        var syntaxTree = componentDocument.GetRequiredTagHelperRewrittenSyntaxTree();
 
         // Right now this includes all the usings in the original document.
         // https://github.com/dotnet/razor/issues/11025 tracks reducing to only the required set.