Fix merge conflicts

eng/config/PublishData.json

@@ -38,4 +38,4 @@
       "insertionTitlePrefix": "[17.7P1]"
     }
   }
-}
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServer.ContainedLanguage/DefaultLSPDocumentSynchronizer.cs

@@ -100,6 +100,30 @@ internal class DefaultLSPDocumentSynchronizer : LSPDocumentSynchronizer
         return new SynchronizedResult<TVirtualDocumentSnapshot>(onSynchronizedResult, virtualDocumentSnapshot);
     }
 
+    internal SynchronizedResult<TVirtualDocumentSnapshot>? TryReturnPossiblyFutureSnapshot<TVirtualDocumentSnapshot>(
+        int requiredHostDocumentVersion,
+        Uri hostDocumentUri) where TVirtualDocumentSnapshot : VirtualDocumentSnapshot
+    {
+        lock (_documentContextLock)
+        {
+            var preSyncedSnapshot = GetVirtualDocumentSnapshot<TVirtualDocumentSnapshot>(hostDocumentUri);
+            var virtualDocumentUri = preSyncedSnapshot.Uri;
+            if (!_virtualDocumentContexts.TryGetValue(virtualDocumentUri, out var documentContext))
+            {
+                // Document was deleted/removed in mid-synchronization
+                return new SynchronizedResult<TVirtualDocumentSnapshot>(false, preSyncedSnapshot);
+            }
+
+            if (requiredHostDocumentVersion <= documentContext.SeenHostDocumentVersion)
+            {
+                // Already synchronized
+                return new SynchronizedResult<TVirtualDocumentSnapshot>(true, preSyncedSnapshot);
+            }
+        }
+
+        return null;
+    }
+
     [Obsolete]
     public override Task<bool> TrySynchronizeVirtualDocumentAsync(int requiredHostDocumentVersion, VirtualDocumentSnapshot virtualDocument, CancellationToken cancellationToken)
         => TrySynchronizeVirtualDocumentAsync(requiredHostDocumentVersion, virtualDocument, rejectOnNewerParallelRequest: true, cancellationToken);

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/DefaultRazorLanguageServerCustomMessageTarget.cs

@@ -1012,10 +1012,27 @@ internal class DefaultRazorLanguageServerCustomMessageTarget : RazorLanguageServ
         }
         else if (request.OriginatingKind == RazorLanguageKind.CSharp)
         {
-            (synchronized, virtualDocumentSnapshot) = await _documentSynchronizer.TrySynchronizeVirtualDocumentAsync<CSharpVirtualDocumentSnapshot>(
-                request.HostDocument.Version,
-                request.HostDocument.Uri,
-                cancellationToken);
+            // TODO this is a partial workaround to fix prefix completion by avoiding sync (which times out during resolve endpoint) if we are currently at a higher version value
+            // this does not fix postfix completion and should be superceded by eventual synchronization fix
+
+            var futureDataSyncResult =
+                (_documentSynchronizer as DefaultLSPDocumentSynchronizer)?.TryReturnPossiblyFutureSnapshot<CSharpVirtualDocumentSnapshot>(
+                    request.HostDocument.Version,
+                    request.HostDocument.Uri);
+            if (futureDataSyncResult?.Synchronized == true)
+            {
+                (synchronized, virtualDocumentSnapshot) = futureDataSyncResult;
+            }
+            else
+            {
+                (synchronized, virtualDocumentSnapshot) = await _documentSynchronizer
+                        .TrySynchronizeVirtualDocumentAsync<CSharpVirtualDocumentSnapshot>(
+                            request.HostDocument.Version,
+                            request.HostDocument.Uri,
+                            rejectOnNewerParallelRequest: true,
+                            cancellationToken);
+            }
+
             languageServerName = RazorLSPConstants.RazorCSharpLanguageServerName;
         }
         else