diff --git a/build/Targets/GenerateInternalsVisibleTo.targets b/build/Targets/GenerateInternalsVisibleTo.targets
index d970105b002c27de243526a9af0c82743428260a..ac9eadbde56826dad875afce181e7280791664f5 100644
--- a/build/Targets/GenerateInternalsVisibleTo.targets
+++ b/build/Targets/GenerateInternalsVisibleTo.targets
@@ -17,6 +17,9 @@
     <InternalsVisibleToTypeScript>
       <Visible>false</Visible>
     </InternalsVisibleToTypeScript>
+    <InternalsVisibleToFSharp>
+      <Visible>false</Visible>
+    </InternalsVisibleToFSharp>
     <InternalsVisibleToMoq>
       <Visible>false</Visible>
     </InternalsVisibleToMoq>
@@ -33,7 +36,7 @@
           Inputs="$(MSBuildThisFileFullPath);$(MSBuildProjectFile)"
           Outputs="$(GeneratedInternalsVisibleToFile)"
           DependsOnTargets="PrepareForBuild"
-          Condition="'@(InternalsVisibleTo)' != '' OR '@(InternalsVisibleToTest)' != '' OR '@(InternalsVisibleToTypeScript)' != '' OR '@(InternalsVisibleToMoq)' != ''">
+          Condition="'@(InternalsVisibleTo)' != '' OR '@(InternalsVisibleToTest)' != '' OR '@(InternalsVisibleToTypeScript)' != '' OR '@(InternalsVisibleToFSharp)' != '' OR '@(InternalsVisibleToMoq)' != ''">
 
     <!--
          This is a slightly evil trick. What we have is a group of InternalsVisibleTo items which
@@ -66,6 +69,11 @@
                 Condition="'@(InternalsVisibleToTypeScript)' != ''">
       <Output TaskParameter="Include" ItemName="InternalsVisibleToAttribute" />
     </CreateItem>
+    <CreateItem Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute"
+                AdditionalMetadata="_Parameter1=%(InternalsVisibleToFSharp.Identity), PublicKey=002400000480000094000000060200000024000052534131000400000100010007D1FA57C4AED9F0A32E84AA0FAEFD0DE9E8FD6AEC8F87FB03766C834C99921EB23BE79AD9D5DCC1DD9AD236132102900B723CF980957FC4E177108FC607774F29E8320E92EA05ECE4E821C0A5EFE8F1645C4C0C93C1AB99285D622CAA652C1DFAD63D745D6F2DE5F17E5EAF0FC4963D261C8A12436518206DC093344D5AD293" 
+                Condition="'@(InternalsVisibleToFSharp)' != ''">
+      <Output TaskParameter="Include" ItemName="InternalsVisibleToAttribute" />
+    </CreateItem>
     <CreateItem Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute"
                 AdditionalMetadata="_Parameter1=%(InternalsVisibleToMoq.Identity), PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7"
                 Condition="'@(InternalsVisibleToMoq)' != ''">
diff --git a/src/EditorFeatures/Core/EditorFeatures.csproj b/src/EditorFeatures/Core/EditorFeatures.csproj
index eea48f8267545287bd7333ba76d5540d6e76ff9e..dcb9a28f5748c33fa582f6a16d30867224933c49 100644
--- a/src/EditorFeatures/Core/EditorFeatures.csproj
+++ b/src/EditorFeatures/Core/EditorFeatures.csproj
@@ -134,6 +134,7 @@
     <InternalsVisibleToTypeScript Include="Microsoft.VisualStudio.LanguageServices.TypeScript" />
     <InternalsVisibleToTypeScript Include="Microsoft.Test.Apex.VisualStudio" />
     <InternalsVisibleToTypeScript Include="Roslyn.Services.Editor.TypeScript.UnitTests" />
+    <InternalsVisibleToFSharp Include="FSharp.Editor" />
     <InternalsVisibleToMoq Include="DynamicProxyGenAssembly2" />
   </ItemGroup>
   <ItemGroup>
diff --git a/src/EditorFeatures/Core/Implementation/Classification/SyntacticClassificationTaggerProvider.cs b/src/EditorFeatures/Core/Implementation/Classification/SyntacticClassificationTaggerProvider.cs
index ca401dbb21dcbdf2195f628de325ac90e6a4b3b8..f211e67a129f39e9c30c3497695ff6cc2d99876b 100644
--- a/src/EditorFeatures/Core/Implementation/Classification/SyntacticClassificationTaggerProvider.cs
+++ b/src/EditorFeatures/Core/Implementation/Classification/SyntacticClassificationTaggerProvider.cs
@@ -16,8 +16,7 @@
 namespace Microsoft.CodeAnalysis.Editor.Implementation.Classification
 {
     [Export(typeof(ITaggerProvider))]
-    [ContentType(ContentTypeNames.CSharpContentType)]
-    [ContentType(ContentTypeNames.VisualBasicContentType)]
+    [ContentType(ContentTypeNames.RoslynContentType)]
     [TextViewRole(PredefinedTextViewRoles.Document)]
     [TagType(typeof(IClassificationTag))]
     internal partial class SyntacticClassificationTaggerProvider : ITaggerProvider
diff --git a/src/EditorFeatures/Text/TextEditorFeatures.csproj b/src/EditorFeatures/Text/TextEditorFeatures.csproj
index b982cc65055863e720313f126fc220bdce21f88a..8effdeaf0f1adf90d121caaeeb08107ace7e93cf 100644
--- a/src/EditorFeatures/Text/TextEditorFeatures.csproj
+++ b/src/EditorFeatures/Text/TextEditorFeatures.csproj
@@ -51,6 +51,8 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.VisualBasic.InteractiveEditorFeatures" />
     <InternalsVisibleToTypeScript Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" />
     <InternalsVisibleToTypeScript Include="Microsoft.VisualStudio.LanguageServices.TypeScript" />
+    <InternalsVisibleToFSharp Include="FSharp.Editor" />
+    <InternalsVisibleToFSharp Include="FSharp.LanguageService" />
     <!-- The rest are for test purposes only. -->
     <InternalsVisibleToTest Include="Roslyn.Services.Editor.CSharp.UnitTests" />
     <InternalsVisibleToTest Include="Roslyn.Services.Editor.UnitTests" />
diff --git a/src/Features/Core/Portable/Features.csproj b/src/Features/Core/Portable/Features.csproj
index 536986379ecf78d8b14ab13f4e8e1d5baad1a988..869d289c099adcc85fbf462f687d88a58ddf3ae4 100644
--- a/src/Features/Core/Portable/Features.csproj
+++ b/src/Features/Core/Portable/Features.csproj
@@ -69,6 +69,7 @@
     <InternalsVisibleToTypeScript Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" />
     <InternalsVisibleToTypeScript Include="Microsoft.VisualStudio.LanguageServices.TypeScript" />
     <InternalsVisibleToTypeScript Include="Roslyn.Services.Editor.TypeScript.UnitTests" />
+    <InternalsVisibleToFSharp Include="FSharp.Editor" />
     <InternalsVisibleToMoq Include="DynamicProxyGenAssembly2" />
   </ItemGroup>
   <ItemGroup>
diff --git a/src/VisualStudio/Core/Def/Implementation/ProjectSystem/AbstractProject.cs b/src/VisualStudio/Core/Def/Implementation/ProjectSystem/AbstractProject.cs
index 1d2321b801435f513996b450cf8b6d3580447bad..a66ddddc61c1e77a2302f6de7b7d3220364736c1 100644
--- a/src/VisualStudio/Core/Def/Implementation/ProjectSystem/AbstractProject.cs
+++ b/src/VisualStudio/Core/Def/Implementation/ProjectSystem/AbstractProject.cs
@@ -352,6 +352,11 @@ public ImmutableArray<ProjectReference> GetCurrentProjectReferences()
         {
             return ImmutableArray.CreateRange(_projectReferences);
         }
+        
+        public ImmutableArray<VisualStudioMetadataReference> GetCurrentMetadataReferences()
+        {
+            return ImmutableArray.CreateRange(_metadataReferences);
+        }
 
         public IVisualStudioHostDocument GetDocumentOrAdditionalDocument(DocumentId id)
         {
diff --git a/src/VisualStudio/Core/Def/ServicesVisualStudio.csproj b/src/VisualStudio/Core/Def/ServicesVisualStudio.csproj
index 0a3377985bdeb0b4d7a7e2a590ad5beacfe75f1d..4541d33a8b83736c256a30c9010e6c152c56fca4 100644
--- a/src/VisualStudio/Core/Def/ServicesVisualStudio.csproj
+++ b/src/VisualStudio/Core/Def/ServicesVisualStudio.csproj
@@ -234,6 +234,8 @@
     <InternalsVisibleToTypeScript Include="ManagedSourceCodeAnalysis" />
     <InternalsVisibleToTypeScript Include="CodeAnalysis" />
     <InternalsVisibleToTypeScript Include="StanCore" />
+    <InternalsVisibleToFSharp Include="FSharp.Editor" />
+    <InternalsVisibleToFSharp Include="FSharp.LanguageService" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="envdte, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
diff --git a/src/VisualStudio/Core/Impl/ServicesVisualStudioImpl.csproj b/src/VisualStudio/Core/Impl/ServicesVisualStudioImpl.csproj
index 6ac92377072c315753e7efadca7ea7037c192aec..5bfce057fcc3c70817e8a71cb024e6ec0614be8d 100644
--- a/src/VisualStudio/Core/Impl/ServicesVisualStudioImpl.csproj
+++ b/src/VisualStudio/Core/Impl/ServicesVisualStudioImpl.csproj
@@ -67,6 +67,8 @@
     <InternalsVisibleToTest Include="Roslyn.VisualStudio.Services.UnitTests" />
     <InternalsVisibleToTypeScript Include="Microsoft.VisualStudio.LanguageServices.TypeScript" />
     <InternalsVisibleToTypeScript Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" />
+    <InternalsVisibleToFSharp Include="FSharp.Editor" />    
+    <InternalsVisibleToFSharp Include="FSharp.LanguageService" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="envdte, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
diff --git a/src/Workspaces/Core/Portable/Diagnostics/Extensions.cs b/src/Workspaces/Core/Portable/Diagnostics/Extensions.cs
index 8b1ee538265ae70bcabb00eb14490710351d1919..70dee2bb2aab61e6782ef501d4bcc8193c48e99a 100644
--- a/src/Workspaces/Core/Portable/Diagnostics/Extensions.cs
+++ b/src/Workspaces/Core/Portable/Diagnostics/Extensions.cs
@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Globalization;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeFixes;
@@ -57,6 +58,15 @@ public static DiagnosticData ToDiagnosticData(this Diagnostic diagnostic, Projec
                 return DiagnosticData.Create(project.GetDocument(diagnostic.Location.SourceTree), diagnostic);
             }
 
+            if (diagnostic.Location.Kind == LocationKind.ExternalFile)
+            {
+                var document = project.Documents.FirstOrDefault(d => d.FilePath == diagnostic.Location.GetLineSpan().Path);
+                if (document != null)
+                {
+                    return DiagnosticData.Create(document, diagnostic);
+                }
+            }
+
             return DiagnosticData.Create(project, diagnostic);
         }