Merge pull request #5626 from CyrusNajmabadi/workspaceOpenDocument

Provide a better exception message.  Fixes #4613

src/VisualStudio/Core/Def/Implementation/ProjectSystem/VisualStudioWorkspaceImpl.cs

@@ -8,6 +8,7 @@
 using EnvDTE;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Host.Mef;
 using Microsoft.CodeAnalysis.Notification;
@@ -47,6 +48,8 @@ internal abstract class VisualStudioWorkspaceImpl : VisualStudioWorkspace
         // document worker coordinator
         private ISolutionCrawlerRegistrationService _registrationService;
 
+        private readonly ForegroundThreadAffinitizedObject foregroundObject = new ForegroundThreadAffinitizedObject();
+
         public VisualStudioWorkspaceImpl(
             SVsServiceProvider serviceProvider,
             WorkspaceBackgroundWork backgroundWork)
@@ -672,6 +675,11 @@ public void OpenDocumentCore(DocumentId documentId, bool activate = true)
                 throw new ArgumentNullException(nameof(documentId));
             }
 
+            if (!foregroundObject.IsForeground())
+            {
+                throw new InvalidOperationException(ServicesVSResources.ThisWorkspaceOnlySupportsOpeningDocumentsOnTheUIThread);
+            }
+
             var document = this.GetHostDocument(documentId);
             if (document != null && document.Project != null)
             {

src/VisualStudio/Core/Def/ServicesVSResources.Designer.cs

@@ -1083,6 +1083,15 @@ internal class ServicesVSResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to This workspace only supports opening documents on the UI thread..
+        /// </summary>
+        internal static string ThisWorkspaceOnlySupportsOpeningDocumentsOnTheUIThread {
+            get {
+                return ResourceManager.GetString("ThisWorkspaceOnlySupportsOpeningDocumentsOnTheUIThread", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to C#/VB Todo List Table Data Source.
         /// </summary>

src/VisualStudio/Core/Def/ServicesVSResources.resx

@@ -501,8 +501,10 @@ Use the dropdown to view and switch to other projects this file may belong to.</
   <data name="ComputingRemoveSuppressionFix" xml:space="preserve">
     <value>Computing remove suppressions fix...</value>
   </data>
-<data name="ApplyingRemoveSuppressionFix" xml:space="preserve">
+  <data name="ApplyingRemoveSuppressionFix" xml:space="preserve">
     <value>Applying remove suppressions fix...</value>
   </data>
-  
+  <data name="ThisWorkspaceOnlySupportsOpeningDocumentsOnTheUIThread" xml:space="preserve">
+    <value>This workspace only supports opening documents on the UI thread.</value>
+  </data>
 </root>
\ No newline at end of file