Remove sync over async blocking in workspace (#76491)

Author: CyrusNajmabadi

src/EditorFeatures/VisualBasic/EndConstructGeneration/EndConstructCommandHandler.vb

@@ -142,7 +142,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.EndConstructGeneration
 
             Dim options = buffer.GetCodeCleanupOptions(_editorOptionsService, document.Project.GetFallbackAnalyzerOptions(), document.Project.Services, explicitFormat:=False, allowImportsInHiddenRegions:=document.AllowImportsInHiddenRegions())
             Dim cleanDocument = CodeCleaner.CleanupAsync(document, GetSpanToCleanup(statement), Options, codeCleanups, cancellationToken:=cancellationToken).WaitAndGetResult(cancellationToken)
-            Dim changes = cleanDocument.GetTextChangesAsync(document, cancellationToken).WaitAndGetResult(cancellationToken)
+            Dim changes = cleanDocument.GetTextChangesSynchronously(document, cancellationToken)
 
             Using transaction = New CaretPreservingEditTransaction(VBEditorResources.End_Construct, view, _undoHistoryRegistry, _editorOperationsFactoryService)
                 transaction.MergePolicy = AutomaticCodeChangeMergePolicy.Instance

src/EditorFeatures/VisualBasic/LineCommit/CommitFormatter.vb

@@ -121,7 +121,7 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.LineCommit
                     End If
                 End If
 
-                Dim changes = finalDocument.GetTextChangesAsync(document, cancellationToken).WaitAndGetResult(cancellationToken)
+                Dim changes = finalDocument.GetTextChangesSynchronously(document, cancellationToken)
                 buffer.ApplyChanges(changes)
             End Using
         End Sub

src/Workspaces/Core/Portable/Workspace/Solution/Document.cs

@@ -419,7 +419,13 @@ public Document WithFilePath(string? filePath)
     /// Get the text changes between this document and a prior version of the same document.
     /// The changes, when applied to the text of the old document, will produce the text of the current document.
     /// </summary>
-    public async Task<IEnumerable<TextChange>> GetTextChangesAsync(Document oldDocument, CancellationToken cancellationToken = default)
+    public Task<IEnumerable<TextChange>> GetTextChangesAsync(Document oldDocument, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult<IEnumerable<TextChange>>(GetTextChangesSynchronously(oldDocument, cancellationToken));
+    }
+
+    internal ImmutableArray<TextChange> GetTextChangesSynchronously(
+        Document oldDocument, CancellationToken cancellationToken)
     {
         try
         {
@@ -443,10 +449,10 @@ public async Task<IEnumerable<TextChange>> GetTextChangesAsync(Document oldDocum
                     var container = text.Container;
                     if (container != null)
                     {
-                        var textChanges = text.GetTextChanges(oldText).ToList();
+                        var textChanges = text.GetTextChanges(oldText).ToImmutableArray();
 
                         // if changes are significant (not the whole document being replaced) then use these changes
-                        if (textChanges.Count > 1 || (textChanges.Count == 1 && textChanges[0].Span != new TextSpan(0, oldText.Length)))
+                        if (textChanges.Length > 1 || (textChanges.Length == 1 && textChanges[0].Span != new TextSpan(0, oldText.Length)))
                         {
                             return textChanges;
                         }
@@ -456,17 +462,18 @@ public async Task<IEnumerable<TextChange>> GetTextChangesAsync(Document oldDocum
                 // get changes by diffing the trees
                 if (this.SupportsSyntaxTree)
                 {
-                    var tree = (await this.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false))!;
-                    var oldTree = await oldDocument.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);
+                    var tree = this.GetSyntaxTreeSynchronously(cancellationToken);
+                    var oldTree = oldDocument.GetSyntaxTreeSynchronously(cancellationToken);
 
+                    RoslynDebug.Assert(tree is object);
                     RoslynDebug.Assert(oldTree is object);
-                    return tree.GetChanges(oldTree);
+                    return tree.GetChanges(oldTree).ToImmutableArray();
                 }
 
-                text = await this.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
-                oldText = await oldDocument.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
+                text = this.GetTextSynchronously(cancellationToken);
+                oldText = oldDocument.GetTextSynchronously(cancellationToken);
 
-                return text.GetTextChanges(oldText).ToList();
+                return text.GetTextChanges(oldText).ToImmutableArray();
             }
         }
         catch (Exception e) when (FatalError.ReportAndPropagateUnlessCanceled(e, cancellationToken))

src/Workspaces/Core/Portable/Workspace/Workspace.cs

@@ -2013,7 +2013,7 @@ private void ApplyChangedDocument(
             {
                 // We have the old text, but no new text is easily available. This typically happens when the content is modified via changes to the syntax tree.
                 // Ask document to compute equivalent text changes by comparing the syntax trees, and use them to
-                var textChanges = newDoc.GetTextChangesAsync(oldDoc, CancellationToken.None).WaitAndGetResult_CanCallOnBackground(CancellationToken.None); // needs wait
+                var textChanges = newDoc.GetTextChangesSynchronously(oldDoc, CancellationToken.None);
                 this.ApplyDocumentTextChanged(documentId, oldText.WithChanges(textChanges));
             }
             else
@@ -2025,15 +2025,6 @@ private void ApplyChangedDocument(
         }
     }
 
-    [Conditional("DEBUG")]
-    private static void CheckNoChanges(Solution oldSolution, Solution newSolution)
-    {
-        var changes = newSolution.GetChanges(oldSolution);
-        Contract.ThrowIfTrue(changes.GetAddedProjects().Any());
-        Contract.ThrowIfTrue(changes.GetRemovedProjects().Any());
-        Contract.ThrowIfTrue(changes.GetProjectChanges().Any());
-    }
-
     private static ProjectInfo CreateProjectInfo(Project project)
     {
         return ProjectInfo.Create(