C#: Address review comments

Author: hvitved

csharp/extractor/Semmle.Extraction.CIL.Driver/ExtractorOptions.cs

@@ -176,8 +176,7 @@ internal class ExtractorOptions : CommonOptions
 
         public ExtractorOptions(string[] args)
         {
-            PDB = true;
-            this.ParseArguments(args);
+            this.ParseArguments(args.Append("--pdb").ToArray());
 
             AddFrameworkDirectories(false);
 

csharp/extractor/Semmle.Extraction/Extractor/StandaloneExtractor.cs

@@ -4,8 +4,7 @@ namespace Semmle.Extraction
 {
     public class StandaloneExtractor : Extractor
     {
-        private readonly ExtractorMode mode;
-        public override ExtractorMode Mode => mode;
+        public override ExtractorMode Mode { get; }
 
         /// <summary>
         /// Creates a new extractor instance for one compilation unit.
@@ -14,9 +13,11 @@ public class StandaloneExtractor : Extractor
         /// <param name="pathTransformer">The object used for path transformations.</param>
         public StandaloneExtractor(ILogger logger, PathTransformer pathTransformer, CommonOptions options) : base(logger, pathTransformer)
         {
-            mode = ExtractorMode.Standalone;
+            Mode = ExtractorMode.Standalone;
             if (options.QlTest)
-                mode |= ExtractorMode.QlTest;
+            {
+                Mode |= ExtractorMode.QlTest;
+            }
         }
     }
 }

csharp/extractor/Semmle.Extraction/Extractor/TracingExtractor.cs

@@ -4,8 +4,7 @@ namespace Semmle.Extraction
 {
     public class TracingExtractor : Extractor
     {
-        private readonly ExtractorMode mode;
-        public override ExtractorMode Mode => mode;
+        public override ExtractorMode Mode { get; }
         public string OutputPath { get; }
 
         /// <summary>
@@ -17,9 +16,11 @@ public class TracingExtractor : Extractor
         public TracingExtractor(string outputPath, ILogger logger, PathTransformer pathTransformer, CommonOptions options) : base(logger, pathTransformer)
         {
             OutputPath = outputPath;
-            mode = ExtractorMode.None;
+            Mode = ExtractorMode.None;
             if (options.QlTest)
-                mode |= ExtractorMode.QlTest;
+            {
+                Mode |= ExtractorMode.QlTest;
+            }
         }
     }
 }

csharp/extractor/Semmle.Extraction/Options.cs

@@ -37,7 +37,7 @@ public abstract class CommonOptions : ICommandLineOptions
         /// <summary>
         /// Whether to extract PDB information.
         /// </summary>
-        public bool PDB { get; set; } = false;
+        public bool PDB { get; private set; } = false;
 
         /// <summary>
         /// Whether "fast extraction mode" has been enabled.