Make cross language project references work when references are built

Author: Kevin Ransom

vsintegration/src/FSharp.Editor/LanguageService/LanguageService.fs

@@ -35,7 +35,7 @@ open Microsoft.VisualStudio.Shell
 open Microsoft.VisualStudio.Shell.Interop
 open Microsoft.VisualStudio.ComponentModelHost
 
-// Exposes FSharpChecker as MEF export
+/// Exposes FSharpChecker as MEF export
 [<Export(typeof<FSharpCheckerProvider>); Composition.Shared>]
 type internal FSharpCheckerProvider 
     [<ImportingConstructor>]
@@ -82,10 +82,10 @@ type internal FSharpCheckerProvider
 
 
 /// Exposes FCS FSharpProjectOptions information management as MEF component.
-//
-// This service allows analyzers to get an appropriate FSharpProjectOptions value for a project or single file.
-// It also allows a 'cheaper' route to get the project options relevant to parsing (e.g. the #define values).
-// The main entrypoints are TryGetOptionsForDocumentOrProject and TryGetOptionsForEditingDocumentOrProject.
+///
+/// This service allows analyzers to get an appropriate FSharpProjectOptions value for a project or single file.
+/// It also allows a 'cheaper' route to get the project options relevant to parsing (e.g. the #define values).
+/// The main entrypoints are TryGetOptionsForDocumentOrProject and TryGetOptionsForEditingDocumentOrProject.
 [<Export(typeof<FSharpProjectOptionsManager>); Composition.Shared>]
 type internal FSharpProjectOptionsManager
     [<ImportingConstructor>]

vsintegration/src/FSharp.LanguageService/FSharp.LanguageService.fsproj

@@ -67,6 +67,7 @@
       <GeneratedModuleName>Microsoft.VisualStudio.FSharp.LanguageService.Strings</GeneratedModuleName>
     </EmbeddedResource>
     <Compile Include="AssemblyInfo.fs" />
+    <Compile Include="LanguageServiceConstants.fs" />
     <Compile Include="Error.fs" />
     <Compile Include="Vs.fs" />
     <Compile Include="Colorize.fs" />

vsintegration/src/FSharp.LanguageService/LanguageServiceConstants.fs

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Microsoft.VisualStudio.FSharp.LanguageService
+
+[<RequireQualifiedAccess>]
+module internal LanguageServiceConstants =
+    
+    /// "F#"
+    [<Literal>]
+    let FSharpLanguageName = "F#"

vsintegration/src/FSharp.LanguageService/ProjectSitesAndFiles.fs

@@ -34,23 +34,20 @@ module internal rec Microsoft.VisualStudio.FSharp.LanguageService.SiteProvider
 
 open System
 open System.Collections.Concurrent
-open System.ComponentModel.Composition
-open System.IO
 open System.Diagnostics
-open Microsoft.VisualStudio
-open Microsoft.VisualStudio.TextManager.Interop
-open Microsoft.VisualStudio.Shell.Interop
-open Microsoft.FSharp.Compiler.SourceCodeServices
+open System.IO
 
 open Microsoft.CodeAnalysis
-open Microsoft.VisualStudio.LanguageServices
+open Microsoft.FSharp.Compiler.SourceCodeServices
+
+open Microsoft.VisualStudio
+open Microsoft.VisualStudio.FSharp.LanguageService
 open Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem
 open Microsoft.VisualStudio.LanguageServices.Implementation.TaskList
-open VSLangProj
-open System.ComponentModel.Composition.Primitives
-open Microsoft.VisualStudio.Shell
-open System.Collections.Immutable
+open Microsoft.VisualStudio.Shell.Interop
+open Microsoft.VisualStudio.TextManager.Interop
 
+open VSLangProj
 
 /// An additional interface that an IProjectSite object can implement to indicate it has an FSharpProjectOptions 
 /// already available, so we don't have to recreate it
@@ -274,7 +271,7 @@ type internal ProjectSitesAndFiles() =
                         if not (isNull project) then
                             for reference in project.ProjectReferences do
                                 let project = workspace.CurrentSolution.GetProject(reference.ProjectId)
-                                if not (isNull project) then
+                                if not (isNull project) && project.Language = LanguageServiceConstants.FSharpLanguageName then
                                     let siteProvider = provideProjectSiteProvider (workspace, project, serviceProvider, projectOptionsTable)
                                     let referenceProject = workspace.ProjectTracker.GetProject(reference.ProjectId)
                                     let outputPath = referenceProject.BinOutputPath