Fix document diagnostics document open check

src/LanguageServer/Protocol/Handler/Diagnostics/AbstractDocumentPullDiagnosticHandler.cs

@@ -34,16 +34,16 @@ protected override ValueTask<ImmutableArray<IDiagnosticSource>> GetOrderedDiagno
         //
         // Only consider open documents here (and only closed ones in the WorkspacePullDiagnosticHandler).  Each
         // handler treats those as separate worlds that they are responsible for.
-        var textDocument = context.TextDocument;
-        if (textDocument is null)
+        var identifier = GetTextDocumentIdentifier(diagnosticsParams);
+        if (identifier is null || context.Document is null)
         {
             context.TraceDebug("Ignoring diagnostics request because no text document was provided");
             return new([]);
         }
 
-        if (!context.IsTracking(textDocument.GetURI()))
+        if (!context.IsTracking(identifier.DocumentUri))
         {
-            context.TraceWarning($"Ignoring diagnostics request for untracked document: {textDocument.GetURI()}");
+            context.TraceWarning($"Ignoring diagnostics request for untracked document: {identifier.DocumentUri}");
             return new([]);
         }
 

src/LanguageServer/Protocol/Handler/Diagnostics/DiagnosticSourceProviders/DocumentSyntaxAndSemanticDiagnosticSourceProvider.cs

@@ -24,12 +24,7 @@ internal abstract class AbstractDocumentSyntaxAndSemanticDiagnosticSourceProvide
 
     public ValueTask<ImmutableArray<IDiagnosticSource>> CreateDiagnosticSourcesAsync(RequestContext context, CancellationToken cancellationToken)
     {
-        if (context.GetTrackedDocument<TextDocument>() is { } document)
-        {
-            return new([new DocumentDiagnosticSource(kind, document)]);
-        }
-
-        return new([]);
+        return new([new DocumentDiagnosticSource(kind, context.GetRequiredDocument())]);
     }
 
     [Export(typeof(IDiagnosticSourceProvider)), Shared]

src/LanguageServer/Protocol/Handler/Diagnostics/Public/PublicDocumentNonLocalDiagnosticSourceProvider.cs

@@ -31,11 +31,10 @@ internal sealed class PublicDocumentNonLocalDiagnosticSourceProvider(
     public ValueTask<ImmutableArray<IDiagnosticSource>> CreateDiagnosticSourcesAsync(RequestContext context, CancellationToken cancellationToken)
     {
         // Non-local document diagnostics are reported only when full solution analysis is enabled for analyzer execution.
-        if (context.GetTrackedDocument<TextDocument>() is { } textDocument &&
-            globalOptions.GetBackgroundAnalysisScope(textDocument.Project.Language) == BackgroundAnalysisScope.FullSolution)
+        if (globalOptions.GetBackgroundAnalysisScope(context.GetRequiredDocument().Project.Language) == BackgroundAnalysisScope.FullSolution)
         {
             // NOTE: Compiler does not report any non-local diagnostics, so we bail out for compiler analyzer.
-            return new([new NonLocalDocumentDiagnosticSource(textDocument, a => !a.IsCompilerAnalyzer())]);
+            return new([new NonLocalDocumentDiagnosticSource(context.GetRequiredDocument(), a => !a.IsCompilerAnalyzer())]);
         }
 
         return new([]);

src/LanguageServer/Protocol/Handler/EditAndContinue/DocumentEditAndContinueDiagnosticSourceProvider.cs

@@ -25,11 +25,6 @@ internal sealed class DocumentEditAndContinueDiagnosticSourceProvider() : IDiagn
 
     public ValueTask<ImmutableArray<IDiagnosticSource>> CreateDiagnosticSourcesAsync(RequestContext context, CancellationToken cancellationToken)
     {
-        if (context.GetTrackedDocument<Document>() is { } document)
-        {
-            return new([EditAndContinueDiagnosticSource.CreateOpenDocumentSource(document)]);
-        }
-
-        return new([]);
+        return new([EditAndContinueDiagnosticSource.CreateOpenDocumentSource(context.GetRequiredDocument())]);
     }
 }

src/LanguageServer/Protocol/Handler/RequestContext.cs

@@ -320,29 +320,6 @@ public SourceText GetTrackedDocumentSourceText(DocumentUri documentUri)
         return _trackedDocuments[documentUri].Text;
     }
 
-    public TDocument? GetTrackedDocument<TDocument>() where TDocument : TextDocument
-    {
-        // Note: context.Document may be null in the case where the client is asking about a document that we have
-        // since removed from the workspace.  In this case, we don't really have anything to process.
-        // GetPreviousResults will be used to properly realize this and notify the client that the doc is gone.
-        //
-        // Only consider open documents here (and only closed ones in the WorkspacePullDiagnosticHandler).  Each
-        // handler treats those as separate worlds that they are responsible for.
-        if (TextDocument is not TDocument document)
-        {
-            TraceDebug($"Ignoring diagnostics request because no {typeof(TDocument).Name} was provided");
-            return null;
-        }
-
-        if (!IsTracking(document.GetURI()))
-        {
-            TraceDebug($"Ignoring diagnostics request for untracked document: {document.GetURI()}");
-            return null;
-        }
-
-        return document;
-    }
-
     /// <summary>
     /// Allows a mutating request to close a document and stop it being tracked.
     /// Mutating requests are serialized by the execution queue in order to prevent concurrent access.

src/LanguageServer/Protocol/Handler/Tasks/DocumentTaskDiagnosticSourceProvider.cs

@@ -25,12 +25,7 @@ internal sealed class DocumentTaskDiagnosticSourceProvider([Import] IGlobalOptio
 
     public ValueTask<ImmutableArray<IDiagnosticSource>> CreateDiagnosticSourcesAsync(RequestContext context, CancellationToken cancellationToken)
     {
-        if (context.GetTrackedDocument<Document>() is { } document)
-        {
-            return new([new TaskListDiagnosticSource(document, globalOptions)]);
-        }
-
-        return new([]);
+        return new([new TaskListDiagnosticSource(context.GetRequiredDocument(), globalOptions)]);
     }
 }
 

src/LanguageServer/ProtocolUnitTests/Diagnostics/PullDiagnosticTests.cs

@@ -935,6 +935,37 @@ class A
         Assert.Equal(LSP.DiagnosticSeverity.Information, results.Single().Diagnostics!.Single().Severity);
     }
 
+    [ConditionalTheory(typeof(UnixLikeOnly)), CombinatorialData]
+    public async Task TestDocumentDiagnosticsWhenClientRequestsWithDifferentCasing(bool useVSDiagnostics, bool mutatingLspWorkspace)
+    {
+        var markup = @"class A {";
+
+        var workspaceXml =
+            $"""
+            <Workspace>
+                <Project Language="C#" CommonReferences="true" AssemblyName="CSProj1">
+                    <Document FilePath="/Users/ConsoleApp1/Class1.cs">{markup}</Document>
+                </Project>
+            </Workspace>
+            """;
+
+        await using var testLspServer = await CreateTestWorkspaceFromXmlAsync(workspaceXml, mutatingLspWorkspace, BackgroundAnalysisScope.OpenFiles, useVSDiagnostics);
+
+        var document = testLspServer.GetCurrentSolution().Projects.Single().Documents.Single();
+
+        var loweredUri = ProtocolConversions.CreateAbsoluteDocumentUri(document.FilePath!.ToLowerInvariant());
+        await testLspServer.OpenDocumentAsync(loweredUri);
+
+        var results = await RunGetDocumentPullDiagnosticsAsync(
+            testLspServer, loweredUri, useVSDiagnostics);
+
+        // When looking up the document based on a URI, the workspace ignores casing differences and can open the document with different casing.
+        // When diagnostics checks if the document is open, it should also be able to tell that the document is open, even though the URI casing is different from the file path.
+
+        Assert.Equal("CS1513", results.Single().Diagnostics!.Single().Code);
+        Assert.NotNull(results.Single().Diagnostics!.Single().CodeDescription!.Href.ParsedUri);
+    }
+
     #endregion
 
     #region Workspace Diagnostics