Use solution folder as starting search path for global.json (#9789)

* Use solution folder as starting search path for global.json

* remove unused UnconfiguredProject import

* remove unneeded comments

Author: phenning

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

@@ -13,28 +13,28 @@ namespace Microsoft.VisualStudio.ProjectSystem.VS.Retargeting;
 [Order(Order.Default)]
 internal sealed partial class ProjectRetargetHandler : IProjectRetargetHandler, IDisposable
 {
-    private readonly UnconfiguredProject _unconfiguredProject;
     private readonly Lazy<IDotNetReleasesProvider> _releasesProvider;
     private readonly IFileSystem _fileSystem;
     private readonly IProjectThreadingService _projectThreadingService;
     private readonly IVsService<SVsTrackProjectRetargeting, IVsTrackProjectRetargeting2> _projectRetargetingService;
+    private readonly IVsService<SVsSolution, IVsSolution> _solutionService;
 
     private Guid _currentSdkDescriptionId = Guid.Empty;
     private Guid _sdkRetargetId = Guid.Empty;
 
     [ImportingConstructor]
     public ProjectRetargetHandler(
-        UnconfiguredProject unconfiguredProject,
         Lazy<IDotNetReleasesProvider> releasesProvider,
         IFileSystem fileSystem,
         IProjectThreadingService projectThreadingService,
-        IVsService<SVsTrackProjectRetargeting, IVsTrackProjectRetargeting2> projectRetargetingService)
+        IVsService<SVsTrackProjectRetargeting, IVsTrackProjectRetargeting2> projectRetargetingService,
+        IVsService<SVsSolution, IVsSolution> solutionService)
     {
-        _unconfiguredProject = unconfiguredProject;
         _releasesProvider = releasesProvider;
         _fileSystem = fileSystem;
         _projectThreadingService = projectThreadingService;
         _projectRetargetingService = projectRetargetingService;
+        _solutionService = solutionService;
     }
 
     public Task<IProjectTargetChange?> CheckForRetargetAsync(RetargetCheckOptions options)
@@ -133,11 +133,11 @@ public Task RetargetAsync(TextWriter outputLogger, RetargetOptions options, IPro
 
     private async Task<string?> GetSdkVersionForProjectAsync()
     {
-        string projectDirectory = _unconfiguredProject.GetProjectDirectory();
+        string? solutionDirectory = await GetSolutionDirectoryAsync();
 
-        if (!string.IsNullOrEmpty(projectDirectory))
+        if (!string.IsNullOrEmpty(solutionDirectory))
         {
-            string? globalJsonPath = FindGlobalJsonPath(projectDirectory);
+            string? globalJsonPath = FindGlobalJsonPath(solutionDirectory!);
             if (globalJsonPath is not null)
             {
                 try
@@ -159,6 +159,22 @@ public Task RetargetAsync(TextWriter outputLogger, RetargetOptions options, IPro
         return null;
     }
 
+    private async Task<string?> GetSolutionDirectoryAsync()
+    {
+        IVsSolution? solution = await _solutionService.GetValueOrNullAsync();
+
+        if (solution is not null)
+        {
+            int hr = solution.GetSolutionInfo(out string solutionDirectory, out string _, out string _);
+            if (hr == HResult.OK && !string.IsNullOrEmpty(solutionDirectory))
+            {
+                return solutionDirectory;
+            }
+        }
+
+        return null;
+    }
+
     public void Dispose()
     {
         if (_currentSdkDescriptionId != Guid.Empty || _sdkRetargetId != Guid.Empty)