F# Shim - Round 2

Roslyn.sln

@@ -404,6 +404,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.CodeAnalysis.Exte
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Roslyn.VisualStudio.Setup.ServiceHub", "src\Setup\DevDivVsix\ServiceHubConfig\Roslyn.VisualStudio.Setup.ServiceHub.csproj", "{3D33BBFD-EC63-4E8C-A714-0A48A3809A87}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests", "src\Tools\ExternalAccess\FSharpTest\Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests.csproj", "{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.CodeAnalysis.ExternalAccess.Apex", "src\Tools\ExternalAccess\Apex\Microsoft.CodeAnalysis.ExternalAccess.Apex.csproj", "{FC32EF16-31B1-47B3-B625-A80933CB3F29}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.CodeAnalysis.ExternalAccess.CodeLens", "src\Tools\ExternalAccess\CodeLens\Microsoft.CodeAnalysis.ExternalAccess.CodeLens.csproj", "{D5B1328C-A9EF-4E55-93D7-B8455855709A}"
@@ -1081,6 +1083,10 @@ Global
 		{3D33BBFD-EC63-4E8C-A714-0A48A3809A87}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{3D33BBFD-EC63-4E8C-A714-0A48A3809A87}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{3D33BBFD-EC63-4E8C-A714-0A48A3809A87}.Release|Any CPU.Build.0 = Release|Any CPU
+		{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}.Release|Any CPU.Build.0 = Release|Any CPU
 		{FC32EF16-31B1-47B3-B625-A80933CB3F29}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{FC32EF16-31B1-47B3-B625-A80933CB3F29}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{FC32EF16-31B1-47B3-B625-A80933CB3F29}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -1294,6 +1300,7 @@ Global
 		{FA51A3CB-5174-4D99-B76E-DC31C5361DF3} = {8977A560-45C2-4EC2-A849-97335B382C74}
 		{DE53934B-7FC1-48A0-85AB-C519FBBD02CF} = {8977A560-45C2-4EC2-A849-97335B382C74}
 		{3D33BBFD-EC63-4E8C-A714-0A48A3809A87} = {BE25E872-1667-4649-9D19-96B83E75A44E}
+		{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5} = {8977A560-45C2-4EC2-A849-97335B382C74}
 		{FC32EF16-31B1-47B3-B625-A80933CB3F29} = {8977A560-45C2-4EC2-A849-97335B382C74}
 		{D5B1328C-A9EF-4E55-93D7-B8455855709A} = {8977A560-45C2-4EC2-A849-97335B382C74}
 		{BDB3414C-35F8-4E2D-8603-DE9CF259540F} = {8977A560-45C2-4EC2-A849-97335B382C74}

src/EditorFeatures/Core.Wpf/Microsoft.CodeAnalysis.EditorFeatures.Wpf.csproj

@@ -54,8 +54,8 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.VisualBasic" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.EditorFeatures.Wpf" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.ServiceHub" />
-    <InternalsVisibleTo Include="FSharp.Editor" Key="$(FSharpKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35076" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.IntegrationTest.Utilities" />
     <InternalsVisibleTo Include="Roslyn.Services.Test.Utilities" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.EditorFeatures.UnitTests" />

src/EditorFeatures/Core/Microsoft.CodeAnalysis.EditorFeatures.csproj

@@ -52,7 +52,6 @@
     <InternalsVisibleTo Include="Roslyn.VisualStudio.DiagnosticsWindow" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.ServiceHub" />
     <InternalsVisibleTo Include="Roslyn.Hosting.Diagnostics" />
-    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
     <!-- BEGIN MONODEVELOP
     These MonoDevelop dependencies don't ship with Visual Studio, so can't break our
     binary insertions and are exempted from the ExternalAccess adapter assembly policies.
@@ -83,6 +82,7 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.IntegrationTests" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Test.Utilities2" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests" />
     <!-- Eventually a bunch of these unit tests should move into Roslyn.Services.Implementation.UnitTests
          and this should be removed. -->
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
@@ -99,7 +99,6 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.15.8" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.0" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.1" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
-    <InternalsVisibleTo Include="FSharp.Editor" Key="$(FSharpKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35076" />
     <InternalsVisibleTo Include="DynamicProxyGenAssembly2" Key="$(MoqPublicKey)" LoadsWithinVisualStudio="false" />
   </ItemGroup>
   <ItemGroup>

src/EditorFeatures/Text/Microsoft.CodeAnalysis.EditorFeatures.Text.csproj

@@ -36,6 +36,7 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.ExternalDependencyServices" WorkItem="https://github.com/dotnet/roslyn/issues/35085" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.EditorFeatures.Wpf" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Implementation" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.TypeScript" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
@@ -50,8 +51,6 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.0" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.1" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Xaml" />
-    <InternalsVisibleTo Include="FSharp.Editor" Key="$(FSharpKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35076" />
-    <InternalsVisibleTo Include="FSharp.LanguageService" Key="$(FSharpKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35076" />
     <!-- BEGIN MONODEVELOP
     These MonoDevelop dependencies don't ship with Visual Studio, so can't break our
     binary insertions and are exempted from the ExternalAccess adapter assembly policies.

src/Features/Core/Portable/Microsoft.CodeAnalysis.Features.csproj

@@ -75,6 +75,7 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.CSharp.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Test.Utilities2" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.TypeScript.EditorFeatures" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.TypeScript" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
     <InternalsVisibleTo Include="Roslyn.Services.Editor.TypeScript.UnitTests" Key="$(TypeScriptKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35077" />
@@ -88,7 +89,6 @@
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.15.8" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.0" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.Remote.CSharp.16.1" Key="$(RemoteLanguageServiceKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35074" />
-    <InternalsVisibleTo Include="FSharp.Editor" Key="$(FSharpKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35076" />
     <InternalsVisibleTo Include="DynamicProxyGenAssembly2" Key="$(MoqPublicKey)" LoadsWithinVisualStudio="false" />
     <InternalsVisibleTo Include="Microsoft.Test.Apex.VisualStudio" Key="$(VisualStudioKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35081" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.Alm.Shared.CodeAnalysisClient" Key="$(VisualStudioKey)" WorkItem="https://github.com/dotnet/roslyn/issues/35086" />

src/Test/Utilities/Portable/Roslyn.Test.Utilities.csproj

@@ -64,6 +64,7 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.EditorFeatures.Test.Utilities" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Workspaces.UnitTests" />
     <InternalsVisibleTo Include="Microsoft.VisualStudio.LanguageServices.CSharp.UnitTests" />
+    <InternalsVisibleTo Include="Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\..\..\Compilers\Shared\CoreClrAnalyzerAssemblyLoader.cs" />

src/Tools/ExternalAccess/FSharp/Completion/FSharpCommonCompletionItem.cs

@@ -0,0 +1,29 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.ExternalAccess.FSharp.Internal;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion
+{
+    internal static class FSharpCommonCompletionItem
+    {
+        public static CompletionItem Create(
+            string displayText,
+            string displayTextSuffix,
+            CompletionItemRules rules,
+            FSharpGlyph? glyph = null,
+            ImmutableArray<SymbolDisplayPart> description = default,
+            string sortText = null,
+            string filterText = null,
+            bool showsWarningIcon = false,
+            ImmutableDictionary<string, string> properties = null,
+            ImmutableArray<string> tags = default,
+            string inlineDescription = null)
+        {
+            var roslynGlyph = glyph.HasValue ? FSharpGlyphHelpers.ConvertTo(glyph.Value) : (Glyph?)null;
+            return CommonCompletionItem.Create(
+                displayText, displayTextSuffix, rules, roslynGlyph, description, sortText, filterText, showsWarningIcon, properties, tags, inlineDescription);
+        }
+    }
+}

src/Tools/ExternalAccess/FSharp/Completion/FSharpCommonCompletionProvider.cs

@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.ExternalAccess.FSharp.Internal.Completion;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion
+{
+    internal static class FSharpCommonCompletionProvider
+    {
+        public static CompletionProvider Create(IFSharpCommonCompletionProvider fsharpCommonCompletionProvider)
+        {
+            return new FSharpInternalCommonCompletionProvider(fsharpCommonCompletionProvider);
+        }
+    }
+}

src/Tools/ExternalAccess/FSharp/Completion/FSharpCommonCompletionUtilities.cs

@@ -0,0 +1,16 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion
+{
+    internal static class FSharpCommonCompletionUtilities
+    {
+        public static bool IsStartingNewWord(SourceText text, int characterPosition, Func<char, bool> isWordStartCharacter, Func<char, bool> isWordCharacter)
+        {
+            return CommonCompletionUtilities.IsStartingNewWord(text, characterPosition, isWordStartCharacter, isWordCharacter);
+        }
+    }
+}

src/Tools/ExternalAccess/FSharp/Completion/FSharpFileSystemCompletionHelper.cs

@@ -0,0 +1,38 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.ExternalAccess.FSharp.Internal;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion
+{
+    internal class FSharpFileSystemCompletionHelper
+    {
+        private readonly FileSystemCompletionHelper _fileSystemCompletionHelper;
+
+        public FSharpFileSystemCompletionHelper(
+            FSharpGlyph folderGlyph,
+            FSharpGlyph fileGlyph,
+            ImmutableArray<string> searchPaths,
+            string baseDirectoryOpt,
+            ImmutableArray<string> allowableExtensions,
+            CompletionItemRules itemRules)
+        {
+            _fileSystemCompletionHelper =
+                new FileSystemCompletionHelper(
+                    FSharpGlyphHelpers.ConvertTo(folderGlyph),
+                    FSharpGlyphHelpers.ConvertTo(fileGlyph),
+                    searchPaths,
+                    baseDirectoryOpt,
+                    allowableExtensions,
+                    itemRules);
+        }
+
+        public Task<ImmutableArray<CompletionItem>> GetItemsAsync(string directoryPath, CancellationToken cancellationToken)
+        {
+            return _fileSystemCompletionHelper.GetItemsAsync(directoryPath, cancellationToken);
+        }
+    }
+}

src/Tools/ExternalAccess/FSharp/Completion/IFSharpCommonCompletionProvider.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.Options;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion
+{
+    internal interface IFSharpCommonCompletionProvider
+    {
+        Task ProvideCompletionsAsync(CompletionContext context);
+
+        bool IsInsertionTrigger(SourceText text, int insertedCharacterPosition, OptionSet options);
+
+        Task<TextChange?> GetTextChangeAsync(
+            Func<CompletionItem, char?, CancellationToken, Task<TextChange?>> baseGetTextChangeAsync,
+            CompletionItem selectedItem,
+            char? ch,
+            CancellationToken cancellationToken);
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/FSharpDiagnosticCustomTags.cs

@@ -1,7 +1,5 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-using Microsoft;
-
 namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
 {
     internal static class FSharpDiagnosticCustomTags

src/Tools/ExternalAccess/FSharp/Diagnostics/FSharpIDEDiagnosticIds.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal static class FSharpIDEDiagnosticIds
+    {
+        public static string SimplifyNamesDiagnosticId => IDEDiagnosticIds.SimplifyNamesDiagnosticId;
+        public static string RemoveUnnecessaryImportsDiagnosticId => IDEDiagnosticIds.RemoveUnnecessaryImportsDiagnosticId;
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/IFSharpDocumentDiagnosticAnalyzer.cs

@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal interface IFSharpDocumentDiagnosticAnalyzer
+    {
+        Task<ImmutableArray<Diagnostic>> AnalyzeSemanticsAsync(Document document, CancellationToken cancellationToken);
+
+        Task<ImmutableArray<Diagnostic>> AnalyzeSyntaxAsync(Document document, CancellationToken cancellationToken);
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/IFSharpProjectDiagnosticAnalyzer.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal interface IFSharpProjectDiagnosticAnalyzer
+    {
+        Task<ImmutableArray<Diagnostic>> AnalyzeProjectAsync(Project project, CancellationToken cancellationToken);
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/IFSharpSimplifyNameDiagnosticAnalyzer.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal interface IFSharpSimplifyNameDiagnosticAnalyzer
+    {
+        Task<ImmutableArray<Diagnostic>> AnalyzeSemanticsAsync(DiagnosticDescriptor descriptor, Document document, CancellationToken cancellationToken);
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/IFSharpUnusedDeclarationsDiagnosticAnalyzer.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal interface IFSharpUnusedDeclarationsDiagnosticAnalyzer
+    {
+        Task<ImmutableArray<Diagnostic>> AnalyzeSemanticsAsync(DiagnosticDescriptor descriptor, Document document, CancellationToken cancellationToken);
+    }
+}

src/Tools/ExternalAccess/FSharp/Diagnostics/IFSharpUnusedOpensDiagnosticAnalyzer.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Diagnostics
+{
+    internal interface IFSharpUnusedOpensDiagnosticAnalyzer
+    {
+        Task<ImmutableArray<Diagnostic>> AnalyzeSemanticsAsync(DiagnosticDescriptor descriptor, Document document, CancellationToken cancellationToken);
+    }
+}