Merge pull request #15952 from tamasvajk/buildless/impr1

C#: Add logging for source file parsing

Author: tamasvajk

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

@@ -284,9 +284,14 @@ public static IEnumerable<Action> ReadSyntaxTrees(IEnumerable<string> sources, A
                 try
                 {
                     using var file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
-                    var st = CSharpSyntaxTree.ParseText(SourceText.From(file, encoding), parseOptions, path);
+                    analyser.Logger.Log(Severity.Trace, $"Parsing source file: '{path}'");
+                    var tree = CSharpSyntaxTree.ParseText(SourceText.From(file, encoding), parseOptions, path);
+                    analyser.Logger.Log(Severity.Trace, $"Source file parsed: '{path}'");
+
                     lock (ret)
-                        ret.Add(st);
+                    {
+                        ret.Add(tree);
+                    }
                 }
                 catch (IOException ex)
                 {