C#: Fix quality issues

csharp/extractor/Semmle.Extraction/Context.cs

@@ -37,7 +37,7 @@ namespace Semmle.Extraction
         // A recursion guard against writing to the trap file whilst writing an id to the trap file.
         private bool writingLabel = false;
 
-        private readonly Queue<IEntity> labelQueue = new();
+        private readonly Queue<IEntity> labelQueue = [];
 
         protected void DefineLabel(IEntity entity)
         {

csharp/extractor/Semmle.Extraction/EscapingTextWriter.cs

@@ -56,7 +56,7 @@ namespace Semmle.Extraction
                 default:
                     wrapped.Write(c);
                     break;
-            };
+            }
         }
 
         public void WriteSubId(IEntity entity)

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

@@ -65,7 +65,7 @@ namespace Semmle.Extraction
 
         // Roslyn framework has no apparent mechanism to associate assemblies with their files.
         // So this lookup table needs to be populated.
-        private readonly Dictionary<string, string> referenceFilenames = new Dictionary<string, string>();
+        private readonly Dictionary<string, string> referenceFilenames = [];
 
         public void SetAssemblyFile(string assembly, string file)
         {

csharp/extractor/Semmle.Extraction/Id.cs

@@ -125,7 +125,7 @@ namespace Semmle.Extraction
             if (!Valid)
                 throw new InvalidOperationException("Attempt to use an invalid label");
 
-            return "#" + Value;
+            return $"#{Value}";
         }
 
         public static bool operator ==(Label l1, Label l2) => l1.Value == l2.Value;

csharp/extractor/Semmle.Extraction/PathTransformer.cs

@@ -92,7 +92,7 @@ namespace Semmle.Extraction
                 {
                     var ret = value;
                     if (ret.Length >= 2 && ret[1] == ':' && Char.IsLower(ret[0]))
-                        ret = Char.ToUpper(ret[0]) + "_" + ret.Substring(2);
+                        ret = $"{char.ToUpper(ret[0])}_{ret[2..]}";
                     return ret.Replace('\\', '/').Replace(":", "_");
                 }
             }

csharp/extractor/Semmle.Extraction/TrapWriter.cs

@@ -48,7 +48,7 @@ namespace Semmle.Extraction
 
             writerLazy = new Lazy<StreamWriter>(() =>
             {
-                var tempPath = trap ?? FileUtils.GetTemporaryWorkingDirectory(out var _);
+                var tempPath = trap ?? FileUtils.GetTemporaryWorkingDirectory(out _);
 
                 do
                 {
@@ -139,7 +139,7 @@ namespace Semmle.Extraction
                 // - the same file was compiled multiple times, or
                 // - the file doesn't exist (due to wrong #line directive or because it's an in-memory source generated AST).
                 // In any case, this is not a fatal error.
-                logger.LogWarning("Problem archiving " + dest + ": " + ex);
+                logger.LogWarning($"Problem archiving {dest}: {ex}");
             }
         }