C#: Rely on CLI to cleanup scratch dir

Author: hvitved

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/DependencyManager.cs

@@ -32,6 +32,7 @@ public sealed class DependencyManager : IDisposable
         private readonly FileContent fileContent;
         private readonly TemporaryDirectory packageDirectory;
         private readonly TemporaryDirectory tempWorkingDirectory;
+        private readonly bool cleanupTempWorkingDirectory;
 
         /// <summary>
         /// Performs C# dependency fetching.
@@ -59,7 +60,7 @@ public DependencyManager(string srcDir, IDependencyOptions options, ILogger logg
             this.progressMonitor.FindingFiles(srcDir);
 
             packageDirectory = new TemporaryDirectory(ComputeTempDirectory(sourceDir.FullName));
-            tempWorkingDirectory = new TemporaryDirectory(GetTemporaryWorkingDirectory());
+            tempWorkingDirectory = new TemporaryDirectory(GetTemporaryWorkingDirectory(out cleanupTempWorkingDirectory));
 
             var allFiles = GetAllFiles();
             var binaryFileExtensions = new HashSet<string>(new[] { ".dll", ".exe" }); // TODO: add more binary file extensions.
@@ -285,15 +286,17 @@ private static string ComputeTempDirectory(string srcDir)
             return Path.Combine(Path.GetTempPath(), "GitHub", "packages", sb.ToString());
         }
 
-        private static string GetTemporaryWorkingDirectory()
+        private static string GetTemporaryWorkingDirectory(out bool cleanupTempWorkingDirectory)
         {
+            cleanupTempWorkingDirectory = false;
             var tempFolder = EnvironmentVariables.GetScratchDirectory();
 
             if (string.IsNullOrEmpty(tempFolder))
             {
                 var tempPath = Path.GetTempPath();
                 var name = Guid.NewGuid().ToString("N").ToUpper();
                 tempFolder = Path.Combine(tempPath, "GitHub", name);
+                cleanupTempWorkingDirectory = true;
             }
 
             return tempFolder;
@@ -574,7 +577,8 @@ private void AnalyseSolutions(IEnumerable<string> solutions)
         public void Dispose()
         {
             packageDirectory?.Dispose();
-            tempWorkingDirectory?.Dispose();
+            if (cleanupTempWorkingDirectory)
+                tempWorkingDirectory?.Dispose();
         }
     }
 }