Fix import completion in LSP workspace (#69691)

* Fix import completion in LSP workspace

1. Provide unimported extension methods
2. Fully qualify unimported type in using statment

src/EditorFeatures/Core/IntelliSense/AsyncCompletion/CommitManager.cs

@@ -9,6 +9,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.Completion.Providers;
 using Microsoft.CodeAnalysis.Completion.Providers.Snippets;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
@@ -212,6 +213,10 @@ private AsyncCompletionData.CommitResult Commit(
                 if (roslynItem.Flags.IsCached())
                     roslynItem.Span = completionListSpan;
 
+                // Adding import is not allowed in debugger view
+                if (_textView is IDebuggerTextView)
+                    roslynItem = ImportCompletionItem.MarkItemToAlwaysFullyQualify(roslynItem);
+
                 change = completionService.GetChangeAsync(document, roslynItem, commitCharacter, cancellationToken).WaitAndGetResult(cancellationToken);
             }
             catch (OperationCanceledException e) when (e.CancellationToken != cancellationToken && FatalError.ReportAndCatch(e))

src/EditorFeatures/Core/IntelliSense/AsyncCompletion/CompletionSource.cs

@@ -392,7 +392,9 @@ public async Task<VSCompletionContext> GetExpandedCompletionContextAsync(
                 options = options with
                 {
                     FilterOutOfScopeLocals = false,
-                    ShowXmlDocCommentCompletion = false
+                    ShowXmlDocCommentCompletion = false,
+                    // Adding import is not allowed in debugger view
+                    CanAddImportStatement = false,
                 };
             }
 

src/Features/Core/Portable/Completion/CompletionOptions.cs

@@ -36,6 +36,12 @@ internal sealed record class CompletionOptions
         /// </summary>
         public bool UpdateImportCompletionCacheInBackground { get; init; } = false;
 
+        /// <summary>
+        /// Whether completion can add import statement as part of committed change.
+        /// For example, adding import is not allowed in debugger view.
+        /// </summary>
+        public bool CanAddImportStatement { get; init; } = true;
+
         public bool FilterOutOfScopeLocals { get; init; } = true;
         public bool ShowXmlDocCommentCompletion { get; init; } = true;
         public bool? ShowNewSnippetExperienceUserOption { get; init; } = null;

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/AbstractExtensionMethodImportCompletionProvider.cs

@@ -20,8 +20,10 @@ internal abstract class AbstractExtensionMethodImportCompletionProvider : Abstra
     {
         protected abstract string GenericSuffix { get; }
 
+        // Don't provide unimported extension methods if adding import is not supported,
+        // since we are current incapable of making a change using its fully qualify form.
         protected override bool ShouldProvideCompletion(CompletionContext completionContext, SyntaxContext syntaxContext)
-            => syntaxContext.IsRightOfNameSeparator && IsAddingImportsSupported(completionContext.Document);
+            => syntaxContext.IsRightOfNameSeparator && IsAddingImportsSupported(completionContext.Document, completionContext.CompletionOptions);
 
         protected override void LogCommit()
             => CompletionProvidersLogger.LogCommitOfExtensionMethodImportCompletionItem();

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/AbstractImportCompletionProvider.cs

@@ -202,10 +202,10 @@ public override async Task<CompletionChange> GetChangeAsync(
 
             async Task<bool> ShouldCompleteWithFullyQualifyTypeName()
             {
-                if (ImportCompletionItem.ShouldAlwaysAddMissingImport(completionItem))
-                    return false;
+                if (ImportCompletionItem.ShouldAlwaysFullyQualify(completionItem))
+                    return true;
 
-                if (!IsAddingImportsSupported(document))
+                if (!IsAddingImportsSupported(document, completionOptions: null))
                     return true;
 
                 // We might need to qualify unimported types to use them in an import directive, because they only affect members of the containing
@@ -242,24 +242,11 @@ private async Task<bool> IsInImportsDirectiveAsync(Document document, int positi
                 && !IsFinalSemicolonOfUsingOrExtern(node, leftToken);
         }
 
-        protected static bool IsAddingImportsSupported(Document document)
+        protected static bool IsAddingImportsSupported(Document document, CompletionOptions? completionOptions)
         {
-            var solution = document.Project.Solution;
-
-            // Certain types of workspace don't support document change, e.g. DebuggerIntelliSenseWorkspace
-            if (!solution.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return false;
-            }
-
             // Certain documents, e.g. Razor document, don't support adding imports
-            var documentSupportsFeatureService = solution.Services.GetRequiredService<IDocumentSupportsFeatureService>();
-            if (!documentSupportsFeatureService.SupportsRefactorings(document))
-            {
-                return false;
-            }
-
-            return true;
+            return completionOptions?.CanAddImportStatement != false &&
+                document.Project.Solution.Services.GetRequiredService<IDocumentSupportsFeatureService>().SupportsRefactorings(document);
         }
 
         private static SyntaxNode CreateImport(Document document, string namespaceName)

src/Features/Core/Portable/Completion/Providers/ImportCompletionProvider/ImportCompletionItem.cs

@@ -25,7 +25,7 @@ internal static class ImportCompletionItem
         private const string MethodKey = nameof(MethodKey);
         private const string ReceiverKey = nameof(ReceiverKey);
         private const string OverloadCountKey = nameof(OverloadCountKey);
-        private const string AlwaysAddMissingImportKey = nameof(AlwaysAddMissingImportKey);
+        private const string AlwaysFullyQualifyKey = nameof(AlwaysFullyQualifyKey);
 
         public static CompletionItem Create(
             string name,
@@ -211,8 +211,8 @@ private static (ISymbol? symbol, int overloadCount) GetSymbolAndOverloadCount(Co
             return (compilation.GetTypeByMetadataName(fullyQualifiedName), 0);
         }
 
-        public static CompletionItem MarkItemToAlwaysAddMissingImport(CompletionItem item) => item.WithProperties(item.Properties.Add(AlwaysAddMissingImportKey, AlwaysAddMissingImportKey));
+        public static CompletionItem MarkItemToAlwaysFullyQualify(CompletionItem item) => item.WithProperties(item.Properties.Add(AlwaysFullyQualifyKey, AlwaysFullyQualifyKey));
 
-        public static bool ShouldAlwaysAddMissingImport(CompletionItem item) => item.Properties.ContainsKey(AlwaysAddMissingImportKey);
+        public static bool ShouldAlwaysFullyQualify(CompletionItem item) => item.Properties.ContainsKey(AlwaysFullyQualifyKey);
     }
 }

src/Features/LanguageServer/Protocol/Handler/Completion/AbstractLspCompletionResultCreationService.cs

@@ -395,7 +395,6 @@ protected static async Task GetChangeAndPopulateSimpleTextEditAsync(
             CancellationToken cancellationToken)
         {
             Debug.Assert(selectedItem.Flags.IsExpanded());
-            selectedItem = ImportCompletionItem.MarkItemToAlwaysAddMissingImport(selectedItem);
             var completionChange = await completionService.GetChangeAsync(document, selectedItem, cancellationToken: cancellationToken).ConfigureAwait(false);
 
             var sourceText = await document.GetTextAsync(cancellationToken).ConfigureAwait(false);

src/Features/LanguageServer/ProtocolUnitTests/Completion/CompletionFeaturesTests.cs

@@ -95,10 +95,12 @@ public int M()
     }
 
     [Theory, CombinatorialData]
-    public async Task TestImportCompletion(bool mutatingLspWorkspace)
+    [WorkItem("https://github.com/dotnet/roslyn/issues/68791")]
+    public async Task TestImportCompletionForType(bool mutatingLspWorkspace, bool isInUsingStatement)
     {
-        var markup =
-@"
+        var markup = isInUsingStatement
+            ? @"global using static Task{|caret:|}"
+            : @"
 class A
 {
     void M()
@@ -146,7 +148,10 @@ void M()
         Assert.Equal("~Task  System.Threading.Tasks", resolvedItem.SortText);
         Assert.Equal(CompletionItemKind.Class, resolvedItem.Kind);
 
-        var expectedAdditionalEdit = new TextEdit() { NewText = "using System.Threading.Tasks;\r\n\r\n", Range = new() { Start = new(1, 0), End = new(1, 0) } };
+        TextEdit expectedAdditionalEdit = isInUsingStatement
+            ? new() { NewText = "System.Threading.Tasks.Task", Range = new() { Start = new(0, 20), End = new(0, 24) } }
+            : new() { NewText = "using System.Threading.Tasks;\r\n\r\n", Range = new() { Start = new(1, 0), End = new(1, 0) } };
+
         AssertJsonEquals(new[] { expectedAdditionalEdit }, resolvedItem.AdditionalTextEdits);
 
         Assert.Null(resolvedItem.LabelDetails.Detail);
@@ -164,6 +169,88 @@ void M()
         AssertJsonEquals(resolvedItem.Documentation, expectedDocumentation);
     }
 
+    [Theory, CombinatorialData]
+    [WorkItem("https://github.com/dotnet/roslyn/issues/69576")]
+    public async Task TestImportCompletionForExtensionMethod(bool mutatingLspWorkspace)
+    {
+        var markup =
+@"
+namespace NS2
+{
+    public static class ExtensionClass
+    {
+        public static bool ExtensionMethod(this object o) => true;
+    }
+}
+
+namespace NS1
+{
+    class Program
+    {
+        void M(object o)
+        {
+            o.{|caret:|}
+        }
+    }
+}";
+        await using var testLspServer = await CreateTestLspServerAsync(markup, mutatingLspWorkspace, DefaultClientCapabilities);
+        var completionParams = CreateCompletionParams(
+            testLspServer.GetLocations("caret").Single(),
+            invokeKind: LSP.VSInternalCompletionInvokeKind.Explicit,
+            triggerCharacter: "\0",
+            triggerKind: LSP.CompletionTriggerKind.Invoked);
+
+        // Make sure the import completion option is on.
+        testLspServer.TestWorkspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ShowItemsFromUnimportedNamespaces, LanguageNames.CSharp, true);
+        testLspServer.TestWorkspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ForceExpandedCompletionIndexCreation, true);
+
+        var document = testLspServer.GetCurrentSolution().Projects.First().Documents.First();
+
+        var completionResult = await testLspServer.ExecuteRequestAsync<LSP.CompletionParams, LSP.CompletionList>(LSP.Methods.TextDocumentCompletionName, completionParams, CancellationToken.None).ConfigureAwait(false);
+        Assert.NotNull(completionResult.ItemDefaults.EditRange);
+        Assert.NotNull(completionResult.ItemDefaults.Data);
+        Assert.NotNull(completionResult.ItemDefaults.CommitCharacters);
+
+        var actualItem = completionResult.Items.First(i => i.Label == "ExtensionMethod");
+        Assert.Equal("NS2", actualItem.LabelDetails.Description);
+        Assert.Equal("~ExtensionMethod NS2", actualItem.SortText);
+        Assert.Equal(CompletionItemKind.Method, actualItem.Kind);
+        Assert.Null(actualItem.LabelDetails.Detail);
+        Assert.Null(actualItem.FilterText);
+        Assert.Null(actualItem.TextEdit);
+        Assert.Null(actualItem.TextEditText);
+        Assert.Null(actualItem.AdditionalTextEdits);
+        Assert.Null(actualItem.Command);
+        Assert.Null(actualItem.CommitCharacters);
+        Assert.Null(actualItem.Data);
+        Assert.Null(actualItem.Detail);
+        Assert.Null(actualItem.Documentation);
+
+        actualItem.Data = completionResult.ItemDefaults.Data;
+
+        var resolvedItem = await testLspServer.ExecuteRequestAsync<LSP.CompletionItem, LSP.CompletionItem>(LSP.Methods.TextDocumentCompletionResolveName, actualItem, CancellationToken.None).ConfigureAwait(false);
+        Assert.Equal("NS2", resolvedItem.LabelDetails.Description);
+        Assert.Equal("~ExtensionMethod NS2", resolvedItem.SortText);
+        Assert.Equal(CompletionItemKind.Method, resolvedItem.Kind);
+
+        var expectedAdditionalEdit = new TextEdit() { NewText = "using NS2;\r\n\r\n", Range = new() { Start = new(1, 0), End = new(1, 0) } };
+        AssertJsonEquals(new[] { expectedAdditionalEdit }, resolvedItem.AdditionalTextEdits);
+
+        Assert.Null(resolvedItem.LabelDetails.Detail);
+        Assert.Null(resolvedItem.FilterText);
+        Assert.Null(resolvedItem.TextEdit);
+        Assert.Null(resolvedItem.TextEditText);
+        Assert.Null(resolvedItem.Command);
+        Assert.Null(resolvedItem.Detail);
+
+        var expectedDocumentation = new MarkupContent()
+        {
+            Kind = LSP.MarkupKind.PlainText,
+            Value = "(extension) bool object.ExtensionMethod()"
+        };
+        AssertJsonEquals(resolvedItem.Documentation, expectedDocumentation);
+    }
+
     [Theory, CombinatorialData]
     public async Task TestResolveComplexEdit(bool mutatingLspWorkspace)
     {

src/VisualStudio/Core/Test/DebuggerIntelliSense/CSharpDebuggerIntellisenseTests.vb

@@ -2,6 +2,8 @@
 ' The .NET Foundation licenses this file to you under the MIT license.
 ' See the LICENSE file in the project root for more information.
 
+Imports Microsoft.CodeAnalysis
+Imports Microsoft.CodeAnalysis.Completion
 Imports Microsoft.CodeAnalysis.Test.Utilities
 Imports Roslyn.Test.Utilities
 
@@ -758,5 +760,60 @@ $$</Document>
                 Assert.Contains("args", state.GetCurrentViewLineText())
             End Using
         End Function
+
+        <WpfTheory, CombinatorialData>
+        Public Async Function CommitUnimportedTypeShouldFullyQualify(isImmediateWindow As Boolean) As Task
+            Dim text = <Workspace>
+                           <Project Language="C#" CommonReferences="true">
+                               <Document>class Program
+{
+    static void Main(string[] args)
+    [|{|]
+    }
+}</Document>
+                           </Project>
+                       </Workspace>
+
+            Using state = TestState.CreateCSharpTestState(text, isImmediateWindow)
+
+                state.Workspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ForceExpandedCompletionIndexCreation, True)
+                state.Workspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ShowItemsFromUnimportedNamespaces, LanguageNames.CSharp, True)
+
+                state.SendTypeChars("Console")
+                Await state.WaitForAsynchronousOperationsAsync()
+                Await state.AssertCompletionSession()
+                Await state.AssertSelectedCompletionItem("Console", inlineDescription:="System")
+
+                state.SendTab()
+
+                Assert.Contains("System.Console", state.GetCurrentViewLineText())
+            End Using
+        End Function
+
+        <WpfTheory, CombinatorialData>
+        Public Async Function ShouldNotProvideUnimportedExtensionMethods(isImmediateWindow As Boolean) As Task
+            Dim text = <Workspace>
+                           <Project Language="C#" CommonReferences="true">
+                               <Document>class Program
+{
+    static void Main(string[] args)
+    [|{|]
+    }
+}</Document>
+                           </Project>
+                       </Workspace>
+
+            Using state = TestState.CreateCSharpTestState(text, isImmediateWindow)
+
+                state.Workspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ForceExpandedCompletionIndexCreation, True)
+                state.Workspace.GlobalOptions.SetGlobalOption(CompletionOptionsStorage.ShowItemsFromUnimportedNamespaces, LanguageNames.CSharp, True)
+
+                state.SendTypeChars("args.To")
+                Await state.WaitForAsynchronousOperationsAsync()
+                Await state.AssertCompletionSession()
+                Await state.AssertCompletionItemsContain("ToString", "")
+                Await state.AssertCompletionItemsDoNotContainAny("ToArray", "ToDictionary", "ToList")
+            End Using
+        End Function
     End Class
 End Namespace