Added shims for completion and sig help. Also added tests.

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("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests", "src\Tools\ExternalAccess\FSharpTest\Microsoft.CodeAnalysis.ExternalAccess.FSharp.UnitTests.csproj", "{BFFB5CAE-33B5-447E-9218-BDEBFDA96CB5}"
+EndProject
 Global
 	GlobalSection(SharedMSBuildProjectFiles) = preSolution
 		src\Compilers\VisualBasic\BasicAnalyzerDriver\BasicAnalyzerDriver.projitems*{2523d0e6-df32-4a3e-8ae0-a19bffae2ef6}*SharedItemsImports = 4
@@ -1069,6 +1071,10 @@ 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
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1258,6 +1264,7 @@ 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}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {604E6B91-7BC0-4126-AE07-D4D2FEFC3D29}

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

@@ -55,6 +55,7 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.EditorFeatures.Wpf" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.ServiceHub" />
     <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

@@ -53,7 +53,6 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.ServiceHub" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Editor.UI.Wpf" WorkItem="https://github.com/dotnet/roslyn/issues/35091" />
     <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.
@@ -84,6 +83,7 @@
     <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="RoslynETAHost" WorkItem="https://github.com/dotnet/roslyn/issues/35072" />

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

@@ -37,6 +37,7 @@
     <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" />

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

@@ -77,6 +77,7 @@
     <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" />

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

@@ -65,6 +65,7 @@
     <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/FSharpInternalCommonCompletionProvider.cs

@@ -0,0 +1,36 @@
+// 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.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.ExternalAccess.FSharp.Completion;
+using Microsoft.CodeAnalysis.Options;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Internal.Completion
+{
+    internal sealed class FSharpInternalCommonCompletionProvider : CommonCompletionProvider
+    {
+        private readonly IFSharpCommonCompletionProvider _provider;
+
+        public FSharpInternalCommonCompletionProvider(IFSharpCommonCompletionProvider provider)
+        {
+            _provider = provider;
+        }
+
+        public override Task ProvideCompletionsAsync(CompletionContext context)
+        {
+            return _provider.ProvideCompletionsAsync(context);
+        }
+
+        protected override Task<TextChange?> GetTextChangeAsync(CompletionItem selectedItem, char? ch, CancellationToken cancellationToken)
+        {
+            return _provider.GetTextChangeAsync(base.GetTextChangeAsync, selectedItem, ch, cancellationToken);
+        }
+
+        internal override bool IsInsertionTrigger(SourceText text, int insertedCharacterPosition, OptionSet options)
+        {
+            return _provider.IsInsertionTrigger(text, insertedCharacterPosition, options);
+        }
+    }
+}

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/Editor/FSharpContentTypeNames.cs

@@ -6,5 +6,6 @@ internal static class FSharpContentTypeNames
     {
         public const string RoslynContentType = Microsoft.CodeAnalysis.Editor.ContentTypeNames.RoslynContentType;
         public const string FSharpContentType = "F#";
+        public const string FSharpSignatureHelpContentType = "F# Signature Help";
     }
 }