Merge pull request #38107 from sharwell/show-code

Show code instead of designer if the designer is not installed

src/VisualStudio/Core/Def/Implementation/AbstractEditorFactory.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.IO;
 using System.Runtime.InteropServices;
@@ -25,10 +27,10 @@ namespace Microsoft.VisualStudio.LanguageServices.Implementation
     /// <summary>
     /// The base class of both the Roslyn editor factories.
     /// </summary>
-    internal abstract partial class AbstractEditorFactory : IVsEditorFactory, IVsEditorFactoryNotify
+    internal abstract class AbstractEditorFactory : IVsEditorFactory, IVsEditorFactoryNotify
     {
         private readonly IComponentModel _componentModel;
-        private Microsoft.VisualStudio.OLE.Interop.IServiceProvider _oleServiceProvider;
+        private Microsoft.VisualStudio.OLE.Interop.IServiceProvider? _oleServiceProvider;
         private bool _encoding;
 
         protected AbstractEditorFactory(IComponentModel componentModel)
@@ -52,7 +54,7 @@ int IVsEditorFactory.Close()
         public int CreateEditorInstance(
             uint grfCreateDoc,
             string pszMkDocument,
-            string pszPhysicalView,
+            string? pszPhysicalView,
             IVsHierarchy vsHierarchy,
             uint itemid,
             IntPtr punkDocDataExisting,
@@ -72,7 +74,7 @@ int IVsEditorFactory.Close()
                 ? "Code"
                 : pszPhysicalView;
 
-            IVsTextBuffer textBuffer = null;
+            IVsTextBuffer? textBuffer = null;
 
             // Is this document already open? If so, let's see if it's a IVsTextBuffer we should re-use. This allows us
             // to properly handle multiple windows open for the same document.
@@ -130,6 +132,10 @@ int IVsEditorFactory.Close()
 
                     // We must create the WinForms designer here
                     var loaderName = GetWinFormsLoaderName(vsHierarchy);
+                    if (loaderName is null)
+                    {
+                        goto case "Code";
+                    }
 
                     var designerService = (IVSMDDesignerService)_oleServiceProvider.QueryService<SVSMDDesignerService>();
                     var designerLoader = (IVSMDDesignerLoader)designerService.CreateDesignerLoader(loaderName);
@@ -173,7 +179,7 @@ int IVsEditorFactory.Close()
             return VSConstants.S_OK;
         }
 
-        private static string GetWinFormsLoaderName(IVsHierarchy vsHierarchy)
+        private string? GetWinFormsLoaderName(IVsHierarchy vsHierarchy)
         {
             const string LoaderName = "Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader";
             const string NewLoaderName = "Microsoft.VisualStudio.Design.Core.Serialization.CodeDom.VSCodeDomDesignerLoader";
@@ -193,6 +199,18 @@ private static string GetWinFormsLoaderName(IVsHierarchy vsHierarchy)
                 if (frameworkName.Identifier == ".NETCoreApp" &&
                     frameworkName.Version?.Major >= 3)
                 {
+                    if (!(_oleServiceProvider.QueryService<SVsShell>() is IVsShell shell))
+                    {
+                        return null;
+                    }
+
+                    var newWinFormsDesignerPackage = new Guid("c78ca057-cc29-421f-ad6d-3b0943debdfc");
+                    if (!ErrorHandler.Succeeded(shell.IsPackageInstalled(newWinFormsDesignerPackage, out var installed))
+                        || installed == 0)
+                    {
+                        return null;
+                    }
+
                     return NewLoaderName;
                 }
             }
@@ -205,7 +223,7 @@ private static string GetWinFormsLoaderName(IVsHierarchy vsHierarchy)
             return LoaderName;
         }
 
-        public int MapLogicalView(ref Guid rguidLogicalView, out string pbstrPhysicalView)
+        public int MapLogicalView(ref Guid rguidLogicalView, out string? pbstrPhysicalView)
         {
             pbstrPhysicalView = null;
 
@@ -267,7 +285,7 @@ private void FormatDocumentCreatedFromTemplate(IVsHierarchy hierarchy, uint item
             var workspace = _componentModel.GetService<VisualStudioWorkspace>();
             var solution = workspace.CurrentSolution;
 
-            ProjectId projectIdToAddTo = null;
+            ProjectId? projectIdToAddTo = null;
 
             foreach (var projectId in solution.ProjectIds)
             {
@@ -292,7 +310,7 @@ private void FormatDocumentCreatedFromTemplate(IVsHierarchy hierarchy, uint item
 
             var documentId = DocumentId.CreateNewId(projectIdToAddTo);
             var forkedSolution = solution.AddDocument(DocumentInfo.Create(documentId, filePath, loader: new FileTextLoader(filePath, defaultEncoding: null), filePath: filePath));
-            var addedDocument = forkedSolution.GetDocument(documentId);
+            var addedDocument = forkedSolution.GetDocument(documentId)!;
 
             var rootToFormat = addedDocument.GetSyntaxRootSynchronously(cancellationToken);
             var documentOptions = ThreadHelper.JoinableTaskFactory.Run(() => addedDocument.GetOptionsAsync(cancellationToken));