[Vsintegration] Fix deadlock when a solution is opened during VS 2026…

src/VisualStudio/LanguageService/XSharpLanguagePackage.cs

@@ -236,7 +236,7 @@ public void GetIntellisenseSettings(bool load)
         protected override async System.Threading.Tasks.Task InitializeAsync(CancellationToken cancellationToken, IProgress<ServiceProgressData> progress)
         {
             instance = this;
-            Logger.Initialize();
+            await Logger.InitializeAsync();
             await base.InitializeAsync(cancellationToken, progress);
             _txtManager = await GetServiceAsync(typeof(SVsTextManager)) as IVsTextManager4;
             Assumes.Present(_txtManager);

src/VisualStudio/ProjectPackage/XSharpProjectPackage.cs

@@ -174,9 +174,14 @@ public XSharpProjectPackage() : base()
         /// </summary>
         protected override async Task InitializeAsync(CancellationToken cancellationToken, IProgress<ServiceProgressData> progress)
         {
-            // Give the codemodel a way to talk to the VS Shell
+            // Give the codemodel a way to talk to the VS Shell.
+            // Everything on this path is awaited and must stay that way: when a solution is opened
+            // while VS is starting, the shell loads this package synchronously from
+            // Solution.OpenAsync() -> CanOpenProject() and waits for it on the UI thread. Blocking
+            // here while waiting for that same UI thread deadlocks the IDE.
             _shellEvents = new XSharpShellEvents();
-            XSharp.Support.Logger.Initialize();
+            await _shellEvents.InitializeAsync();
+            await XSharp.Support.Logger.InitializeAsync();
             this.RegisterToolWindows();
 
             await base.InitializeAsync(cancellationToken, progress);

src/VisualStudio/ProjectPackage/XSharpShellEvents.cs

@@ -28,34 +28,22 @@ internal class XSharpShellEvents
         bool isInitialized = false;
         static XSharpShellEvents()
         {
+            // Only read the environment here. Showing the warning is UI work and would block while
+            // waiting for the UI thread, which deadlocks when we are constructed during a package
+            // load that the shell is waiting for. It is reported from InitializeAsync() instead.
             hasEnvironmentvariable = !string.IsNullOrEmpty(System.Environment.GetEnvironmentVariable("XSharpMsBuildDir"));
-            if (!hasEnvironmentvariable)
-            {
-                VS.MessageBox.ShowWarning("The environment variable 'XSharpMsBuildDir' is missing. \rSome projects may have problems loading. \rPlease run the XSharp setup program again.");
-            }
         }
 
-        internal XSharpShellEvents()
-        {
-            if (ThreadHelper.CheckAccess())
-            {
-                // Already on UI thread
-                Initialize();
-            }
-            else
-            {
-                ThreadHelper.JoinableTaskFactory.Run(async delegate
-                {
-                    await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
-                    Initialize();
-                });
-            }
-        }
-        internal void Initialize()
+        /// <summary>
+        /// Subscribe to the shell events. Must be awaited and never waited on: we are called from
+        /// XSharpProjectPackage.InitializeAsync(), where blocking while waiting for the UI thread
+        /// deadlocks the IDE. See the remarks on Logger.InitializeAsync().
+        /// </summary>
+        internal async Task InitializeAsync()
         {
             if (isInitialized)
                 return;
-            ThreadHelper.ThrowIfNotOnUIThread();
+            await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
 #if DEV17
             VS.Events.SolutionEvents.OnAfterOpenSolution += SolutionEvents_OnAfterOpenSolution;
 #endif
@@ -65,20 +53,22 @@ internal void Initialize()
             VS.Events.SolutionEvents.OnBeforeOpenProject += SolutionEvents_OnBeforeOpenProject;
 
             VS.Events.DocumentEvents.Closed += DocumentEvents_Closed;
-            ThreadHelper.JoinableTaskFactory.Run(async delegate
-            {
 
-                _ = await VS.Commands.InterceptAsync(KnownCommands.File_CloseSolution, CloseDesignerWindows);
-                _ = await VS.Commands.InterceptAsync(KnownCommands.File_Exit, CloseDesignerWindows);
-                var sol = await VS.Solutions.GetCurrentSolutionAsync();
+            _ = await VS.Commands.InterceptAsync(KnownCommands.File_CloseSolution, CloseDesignerWindows);
+            _ = await VS.Commands.InterceptAsync(KnownCommands.File_Exit, CloseDesignerWindows);
+            var sol = await VS.Solutions.GetCurrentSolutionAsync();
 #if DEV17
-                if (sol is Solution)
-                {
-                    SolutionEvents_OnAfterOpenSolution(sol);
-                }
+            if (sol is Solution)
+            {
+                await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
+                SolutionEvents_OnAfterOpenSolution(sol);
+            }
 #endif
-            });
             isInitialized = true;
+            if (!hasEnvironmentvariable)
+            {
+                VS.MessageBox.ShowWarningAsync("The environment variable 'XSharpMsBuildDir' is missing. \rSome projects may have problems loading. \rPlease run the XSharp setup program again.").FireAndForget();
+            }
         }