Ensure new files are formatted based on the right language version

Author: davidwengier

src/VisualStudio/CSharp/Impl/LanguageService/CSharpEditorFactory.cs

@@ -5,11 +5,13 @@
 #nullable disable
 
 using System;
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.CodeGeneration;
 using Microsoft.CodeAnalysis.CSharp.FileHeaders;
 using Microsoft.CodeAnalysis.CSharp.MisplacedUsingDirectives;
@@ -18,6 +20,8 @@
 using Microsoft.CodeAnalysis.FileHeaders;
 using Microsoft.VisualStudio.ComponentModelHost;
 using Microsoft.VisualStudio.LanguageServices.Implementation;
+using Microsoft.VisualStudio.LanguageServices.Utilities;
+using Microsoft.VisualStudio.Shell.Interop;
 
 namespace Microsoft.VisualStudio.LanguageServices.CSharp.LanguageService
 {
@@ -32,5 +36,22 @@ public CSharpEditorFactory(IComponentModel componentModel)
 
         protected override string ContentTypeName => ContentTypeNames.CSharpContentType;
         protected override string LanguageName => LanguageNames.CSharp;
+
+        protected override Solution GetSolutionWithCorrectParseOptionsForProject(ProjectId projectId, IVsHierarchy hierarchy, Solution solution)
+        {
+            var project = solution.GetProject(projectId);
+
+            Debug.Assert(project is not null);
+
+            if (project.ParseOptions is CSharpParseOptions parseOptions &&
+                hierarchy is IVsBuildPropertyStorage propertyStorage &&
+                ErrorHandler.Succeeded(propertyStorage.GetPropertyValue("LangVersion", null, (uint)_PersistStorageType.PST_PROJECT_FILE, out var langVersionString)) &&
+                LanguageVersionFacts.TryParse(langVersionString, out var langVersion))
+            {
+                return solution.WithProjectParseOptions(projectId, parseOptions.WithLanguageVersion(langVersion));
+            }
+
+            return solution;
+        }
     }
 }

src/VisualStudio/Core/Def/Implementation/AbstractEditorFactory.cs

@@ -46,6 +46,8 @@ protected AbstractEditorFactory(IComponentModel componentModel)
         protected abstract string ContentTypeName { get; }
         protected abstract string LanguageName { get; }
 
+        protected abstract Solution GetSolutionWithCorrectParseOptionsForProject(ProjectId projectId, IVsHierarchy hierarchy, Solution solution);
+
         public void SetEncoding(bool value)
             => _encoding = value;
 
@@ -325,6 +327,12 @@ private async Task FormatDocumentCreatedFromTemplateAsync(IVsHierarchy hierarchy
                 projectIdToAddTo = temporaryProject.Id;
             }
 
+            // We need to ensure that decisions made during new document formatting are based on the right language
+            // version from the project system, but the NotifyItemAdded event happens before a design time build,
+            // and someimes before we have even been told about the projects existence, so we have to ask the hierarchy
+            // for the language version to use.
+            solution = GetSolutionWithCorrectParseOptionsForProject(projectIdToAddTo, hierarchy, solution);
+
             var documentId = DocumentId.CreateNewId(projectIdToAddTo);
             var forkedSolution = solution.AddDocument(DocumentInfo.Create(documentId, filePath, loader: new FileTextLoader(filePath, defaultEncoding: null), filePath: filePath));
             var addedDocument = forkedSolution.GetDocument(documentId)!;

src/VisualStudio/VisualBasic/Impl/LanguageService/VisualBasicEditorFactory.vb

@@ -7,10 +7,12 @@ Imports Microsoft.CodeAnalysis
 Imports Microsoft.CodeAnalysis.Editing
 Imports Microsoft.CodeAnalysis.Editor
 Imports Microsoft.CodeAnalysis.FileHeaders
+Imports Microsoft.CodeAnalysis.VisualBasic
 Imports Microsoft.CodeAnalysis.VisualBasic.CodeGeneration
 Imports Microsoft.CodeAnalysis.VisualBasic.FileHeaders
 Imports Microsoft.VisualStudio.ComponentModelHost
 Imports Microsoft.VisualStudio.LanguageServices.Implementation
+Imports Microsoft.VisualStudio.Shell.Interop
 
 Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic
     <Guid(Guids.VisualBasicEditorFactoryIdString)>
@@ -24,5 +26,33 @@ Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic
         Protected Overrides ReadOnly Property ContentTypeName As String = ContentTypeNames.VisualBasicContentType
 
         Protected Overrides ReadOnly Property LanguageName As String = LanguageNames.VisualBasic
+
+        Protected Overrides Function GetSolutionWithCorrectParseOptionsForProject(projectId As ProjectId, hierarchy As IVsHierarchy, solution As Solution) As Solution
+            Dim project = solution.GetProject(projectId)
+
+            Debug.Assert(project IsNot Nothing)
+
+            Dim parseOptions = TryCast(project.ParseOptions, VisualBasicParseOptions)
+            If parseOptions Is Nothing Then
+                Return solution
+            End If
+
+            Dim propertyStorage = TryCast(hierarchy, IVsBuildPropertyStorage)
+            If propertyStorage Is Nothing Then
+                Return solution
+            End If
+
+            Dim langVersionString = ""
+            If ErrorHandler.Failed(propertyStorage.GetPropertyValue("LangVersion", Nothing, CUInt(_PersistStorageType.PST_PROJECT_FILE), langVersionString)) Then
+                Return solution
+            End If
+
+            Dim langVersion = LanguageVersion.Default
+            If TryParse(langVersionString, langVersion) Then
+                Return solution.WithProjectParseOptions(projectId, parseOptions.WithLanguageVersion(langVersion))
+            End If
+
+            Return solution
+        End Function
     End Class
 End Namespace