Use Microsoft.IO over System.IO

When targeting .NET Framework, some commonly-used System.IO classes have
worse performance than in .NET. They are also not null-annotated, which
can allow bugs to slip through undetected.

This change uses a global alias across the solution so that Path and
Directory types come from the newer Microsoft.IO package/assembly. This
gives us a reduction in allocations, access to newer methods (like
Path.Join), and correct null annotations.

All other changes here are in response to the user of the newer package,
mostly around handling null values correctly.

Author: drewnoakes

Directory.Build.props

@@ -143,6 +143,10 @@
     <Using Include="Microsoft.VisualStudio.Composition.ImportCardinality" Alias="ImportCardinality" />
     <!-- Prevent accidental use of Microsoft.VisualStudio.Threading.IAsyncDisposable -->
     <Using Include="System.IAsyncDisposable" Alias="IAsyncDisposable" />
+    <!-- Enforce use of Microsoft.IO -->
+    <Using Include="Microsoft.IO.Path" Alias="Path" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
+    <Using Include="Microsoft.IO.Directory" Alias="Directory" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
+    <Using Include="Microsoft.IO.SearchOption" Alias="SearchOption" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
   </ItemGroup>
 
   <Import Project="eng\imports\LanguageSettings.props" />

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/IO/WindowsFileExplorer.cs

@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE.md file in the project root for more information.
 
 using System.Runtime.InteropServices;
-using Path = Microsoft.IO.Path;
 
 namespace Microsoft.VisualStudio.IO;
 

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/CreateFileFromTemplateService.cs

@@ -35,12 +35,20 @@ public async Task<bool> CreateFileAsync(string templateFile, string path)
         Requires.NotNull(templateFile);
         Requires.NotNullOrEmpty(path);
 
-        string directoryName = Path.GetDirectoryName(path);
         string fileName = Path.GetFileName(path);
+        string? directoryName = Path.GetDirectoryName(path);
+
+        if (directoryName is null)
+        {
+            return false;
+        }
 
         string? templateLanguage = await GetTemplateLanguageAsync();
+
         if (string.IsNullOrEmpty(templateLanguage))
+        {
             return false;
+        }
 
         await _projectVsServices.ThreadingService.SwitchToUIThread();
 

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/LanguageServices/Handlers/CompileItemHandler.cs

@@ -43,7 +43,7 @@ IEnumerable<string> GetFilePaths(BuildOptions options)
 
     protected override void AddToContext(IWorkspaceProjectContext context, string fullPath, IImmutableDictionary<string, string> metadata, bool isActiveContext, IManagedProjectDiagnosticOutputService logger)
     {
-        string[]? folderNames = FileItemServices.GetLogicalFolderNames(Path.GetDirectoryName(Project.FullPath), fullPath, metadata);
+        string[]? folderNames = FileItemServices.GetLogicalFolderNames(Path.GetDirectoryName(Project.FullPath)!, fullPath, metadata);
 
         logger.WriteLine("Adding source file '{0}'", fullPath);
         context.AddSourceFile(fullPath, isInCurrentContext: isActiveContext, folderNames: folderNames);

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Rename/FileMoveNotificationListener.cs

@@ -11,7 +11,6 @@
 using Microsoft.VisualStudio.Threading;
 // Debug collides with Microsoft.VisualStudio.ProjectSystem.VS.Debug
 using DiagDebug = System.Diagnostics.Debug;
-using Path = System.IO.Path;
 using static Microsoft.CodeAnalysis.Rename.Renamer;
 
 namespace Microsoft.VisualStudio.ProjectSystem.VS.Rename;
@@ -75,7 +74,13 @@ public async Task OnBeforeFilesMovedAsync(IReadOnlyCollection<IFileMoveItem> ite
             }
 
             // Get the relative folder path from the project to the destination.
-            string destinationFolderPath = Path.GetDirectoryName(_unconfiguredProject.MakeRelative(itemToMove.Destination));
+            string? destinationFolderPath = Path.GetDirectoryName(_unconfiguredProject.MakeRelative(itemToMove.Destination));
+
+            if ( (destinationFolderPath is null))
+            {
+                continue;
+            }
+
             string[] destinationFolders = destinationFolderPath.Split(Delimiter.Path, StringSplitOptions.RemoveEmptyEntries);
 
             // Since this rename only moves the location of the file to another directory, it will use the SyncNamespaceDocumentAction in Roslyn as the rename action within this set.

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Rename/RenamerProjectTreeActionHandler.cs

@@ -78,13 +78,14 @@ public override async Task RenameAsync(IProjectTreeActionHandlerContext context,
         Requires.NotNullOrEmpty(value);
 
         string? oldFilePath = node.FilePath;
-        string oldName = Path.GetFileNameWithoutExtension(oldFilePath);
+        string? oldName = Path.GetFileNameWithoutExtension(oldFilePath);
         string newFileWithExtension = value;
         CodeAnalysis.Project? project = GetCurrentProject();
 
         await CpsFileRenameAsync(context, node, value);
 
-        if (project is null ||
+        if (oldName is null ||
+            project is null ||
             await IsAutomationFunctionAsync() ||
             node.IsFolder ||
             _vsOnlineServices.ConnectedToVSOnline ||

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Retargeting/DotNetReleasesProvider.cs

@@ -4,7 +4,6 @@
 using Microsoft.VisualStudio.Linq;
 using Microsoft.VisualStudio.Shell.Interop;
 using Microsoft.VisualStudio.Threading;
-using Path = Microsoft.IO.Path;
 
 namespace Microsoft.VisualStudio.ProjectSystem.VS.Retargeting;
 

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Retargeting/ProjectRetargetHandler.cs

@@ -6,7 +6,6 @@
 using Microsoft.VisualStudio.Shell.Interop;
 using Microsoft.VisualStudio.Threading;
 using IFileSystem = Microsoft.VisualStudio.IO.IFileSystem;
-using Path = Microsoft.IO.Path;
 
 namespace Microsoft.VisualStudio.ProjectSystem.VS.Retargeting;
 

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Setup/DotNetEnvironment.cs

@@ -69,7 +69,7 @@ public bool IsSdkInstalled(string sdkVersion)
             registryKey,
             "InstallLocation");
 
-        if (!string.IsNullOrEmpty(installLocation))
+        if (!Strings.IsNullOrEmpty(installLocation))
         {
             string dotnetExePath = Path.Combine(installLocation, "dotnet.exe");
             if (_fileSystem.FileExists(dotnetExePath))

src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/TempPE/DesignTimeInputsChangeTracker.cs

@@ -196,6 +196,12 @@ internal void ProcessDataflowChanges(IProjectVersionedValue<ValueTuple<DesignTim
         // Make sure we have the up to date output path. If either of these don't exist, they will be null and we'll handle the ArgumentException below
         string? basePath = configChanges.After.Properties.GetValueOrDefault(ConfigurationGeneral.ProjectDirProperty);
         string? objPath = configChanges.After.Properties.GetValueOrDefault(ConfigurationGeneral.IntermediateOutputPathProperty);
+
+        if (basePath is null || objPath is null)
+        {
+            return null;
+        }
+
         try
         {
             tempPEOutputPath = Path.Combine(basePath, objPath, "TempPE");