C#: Fix some LGTM alerts on the extractor

csharp/autobuilder/Semmle.Autobuild/Project.cs

@@ -39,7 +39,7 @@ public Project(Autobuilder builder, string path) : base(builder, path)
             {
                 projFile = builder.Actions.LoadXml(FullPath);
             }
-            catch (Exception e) when (e is XmlException || e is FileNotFoundException)
+            catch (Exception ex) when (ex is XmlException || ex is FileNotFoundException)
             {
                 builder.Log(Severity.Info, $"Unable to read project file {path}.");
                 return;

csharp/autobuilder/Semmle.Autobuild/Solution.cs

@@ -63,7 +63,7 @@ public Solution(Autobuilder builder, string path, bool allowProject) : base(buil
             {
                 solution = SolutionFile.Parse(FullPath);
             }
-            catch (Exception e) when (e is InvalidProjectFileException || e is FileNotFoundException)
+            catch (Exception ex) when (ex is InvalidProjectFileException || ex is FileNotFoundException)
             {
                 // We allow specifying projects as solutions in lgtm.yml, so model
                 // that scenario as a solution with just that one project

csharp/extractor/Semmle.Extraction.CIL/Entities/Assembly.cs

@@ -143,7 +143,7 @@ public static void ExtractCIL(Layout layout, string assemblyPath, ILogger logger
                     }
                 }
             }
-            catch (Exception ex)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
                 logger.Log(Severity.Error, string.Format("Exception extracting {0}: {1}", assemblyPath, ex));
             }

csharp/extractor/Semmle.Extraction.CIL/Entities/Method.cs

@@ -402,6 +402,9 @@ public MemberReferenceMethod(GenericContext gc, MemberReferenceHandle handle) :
 
             declType = parentMethod == null ? parent as Type : parentMethod.DeclaringType;
 
+            if (declType is null)
+                throw new InternalError("Parent context of method is not a type");
+
             ShortId = MakeMethodId(declType, nameLabel);
 
             var typeSourceDeclaration = declType.SourceDeclaration;

csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs

@@ -1121,7 +1121,7 @@ class GenericMethodParameter : ITypeSignature
             static readonly Id excl = Id.Create("M!");
             public Id MakeId(GenericContext outerGc)
             {
-                if (innerGc != outerGc && innerGc is Method method)
+                if (!ReferenceEquals(innerGc, outerGc) && innerGc is Method method)
                     return open + method.Label.Value + close + excl + index;
                 return excl + index;
             }

csharp/extractor/Semmle.Extraction.CSharp.Standalone/BuildAnalysis.cs

@@ -283,7 +283,7 @@ void AnalyseProjectFiles(FileInfo[] projectFiles)
                     }
                     ++succeededProjects;
                 }
-                catch (Exception ex)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
                     ++failedProjects;
                     progressMonitor.FailedProjectFile(proj.FullName, ex.Message);

csharp/extractor/Semmle.Extraction.CSharp.Standalone/NugetPackages.cs

@@ -183,10 +183,10 @@ void RestoreNugetPackage(string package, IProgressMonitor pm)
                     }
                 }
             }
-            catch (Exception e)
-                when (e is System.ComponentModel.Win32Exception || e is FileNotFoundException)
+            catch (Exception ex)
+                when (ex is System.ComponentModel.Win32Exception || ex is FileNotFoundException)
             {
-                pm.FailedNugetCommand(pi.FileName, pi.Arguments, e.Message);
+                pm.FailedNugetCommand(pi.FileName, pi.Arguments, ex.Message);
             }
         }
 

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

@@ -97,7 +97,7 @@ void SetReferencePaths()
                         extractor.SetAssemblyFile(assemblyIdentity, refPath);
                     }
                 }
-                catch (Exception ex)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
                     extractor.Message(new Message
                     {
@@ -272,7 +272,7 @@ void DoAnalyseAssembly(PortableExecutableReference r)
                     ReportProgress(assemblyPath, trapWriter.TrapFile, stopwatch.Elapsed, skipExtraction ? AnalysisAction.UpToDate : AnalysisAction.Extracted);
                 }
             }
-            catch (Exception ex)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
                 Logger.Log(Severity.Error, "  Unhandled exception analyzing {0}: {1}", r.FilePath, ex);
             }
@@ -354,7 +354,7 @@ void DoExtractTree(SyntaxTree tree)
 
                 ReportProgress(sourcePath, trapPath, stopwatch.Elapsed, excluded ? AnalysisAction.Excluded : upToDate ? AnalysisAction.UpToDate : AnalysisAction.Extracted);
             }
-            catch (Exception ex)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
                 extractor.Message(new Message { exception = ex, message = string.Format("Unhandled exception processing {0}: {1}", tree.FilePath, ex), severity = Severity.Error });
             }

csharp/extractor/Semmle.Extraction.CSharp/Entities/Modifier.cs

@@ -134,6 +134,9 @@ public static void ExtractModifiers(Context cx, IEntity key, ISymbol symbol)
             if (symbol.Kind == SymbolKind.NamedType)
             {
                 INamedTypeSymbol nt = symbol as INamedTypeSymbol;
+                if (nt is null)
+                    throw new InternalError(symbol, "Symbol kind is inconsistent with its type");
+
                 if (nt.TypeKind == TypeKind.Struct)
                 {
                     // Sadly, these properties are internal so cannot be accessed directly.

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Checked.cs

@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp.Syntax;  // lgtm[cs/similar-file]
 using Semmle.Extraction.Kinds;
 
 namespace Semmle.Extraction.CSharp.Entities.Statements

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Return.cs

@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp.Syntax;  // lgtm[cs/similar-file]
 using Semmle.Extraction.Kinds;
 
 namespace Semmle.Extraction.CSharp.Entities.Statements

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Throw.cs

@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp.Syntax;  // lgtm[cs/similar-file]
 using Semmle.Extraction.Kinds;
 
 namespace Semmle.Extraction.CSharp.Entities.Statements

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Unchecked.cs

@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp.Syntax;  // lgtm[cs/similar-file]
 using Semmle.Extraction.Kinds;
 
 namespace Semmle.Extraction.CSharp.Entities.Statements

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

@@ -165,9 +165,9 @@ public static ExitCode Run(string[] args)
 
                     return analyser.TotalErrors == 0 ? ExitCode.Ok : ExitCode.Errors;
                 }
-                catch (Exception e)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
-                    logger.Log(Severity.Error, "  Unhandled exception: {0}", e);
+                    logger.Log(Severity.Error, "  Unhandled exception: {0}", ex);
                     return ExitCode.Errors;
                 }
             }
@@ -354,9 +354,9 @@ public static void ExtractStandalone(
 
                     pm.MissingSummary(analyser.MissingTypes.Count(), analyser.MissingNamespaces.Count());
                 }
-                catch (Exception e)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
-                    analyser.Logger.Log(Severity.Error, "  Unhandled exception: {0}", e);
+                    analyser.Logger.Log(Severity.Error, "  Unhandled exception: {0}", ex);
                 }
             }
         }

csharp/extractor/Semmle.Extraction.CSharp/Kinds/StmtKind.cs

@@ -1,4 +1,4 @@
-namespace Semmle.Extraction.Kinds
+namespace Semmle.Extraction.Kinds  // lgtm[cs/similar-file]
 {
     /// <summary>
     /// This enum has been auto-generated from the C# DB scheme - do not edit.

csharp/extractor/Semmle.Extraction.CSharp/Kinds/TypeKind.cs

@@ -1,4 +1,4 @@
-namespace Semmle.Extraction.Kinds
+namespace Semmle.Extraction.Kinds  // lgtm[cs/similar-file]
 {
     /// <summary>
     /// This enum has been auto-generated from the C# DB scheme - do not edit.

csharp/extractor/Semmle.Extraction.CSharp/Populators/Ast.cs

@@ -54,9 +54,9 @@ public static void Extract(this Context cx, CSharpSyntaxNode node, IExpressionPa
                 {
                     node.Accept(new Ast(cx, parent, child));
                 }
-                catch (System.Exception e)
+                catch (System.Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
-                    cx.ModelError(node, "Exception processing syntax node of type {0}: {1}", node.Kind(), e);
+                    cx.ModelError(node, "Exception processing syntax node of type {0}: {1}", node.Kind(), ex);
                 }
             }
         }

csharp/extractor/Semmle.Extraction.CSharp/Populators/Symbols.cs

@@ -55,9 +55,9 @@ public static IEntity CreateEntity(this Context cx, ISymbol symbol)
                 {
                     return symbol.Accept(new Symbols(cx));
                 }
-                catch (Exception e)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
-                    cx.ModelError(symbol, "Exception processing symbol '{2}' of type '{0}': {1}", symbol.Kind, e, symbol);
+                    cx.ModelError(symbol, "Exception processing symbol '{2}' of type '{0}': {1}", symbol.Kind, ex, symbol);
                     return null;
                 }
             }

csharp/extractor/Semmle.Extraction/Context.cs

@@ -93,7 +93,7 @@ private void CheckEntityHasUniqueLabel(IId id, ICachedEntity entity)
         {
             if (idLabelCache.TryGetValue(id, out var originalEntity))
             {
-                Extractor.Message(new Message { message = "Label collision for " + id.ToString(), severity = Severity.Warning });
+                Extractor.Message(new Message { message = "Label collision for " + id, severity = Severity.Warning });
             }
             else
             {
@@ -216,13 +216,13 @@ public void PopulateAll()
                 {
                     populateQueue.Dequeue()();
                 }
-                catch (InternalError e)
+                catch (InternalError ex)
                 {
-                    Extractor.Message(e.ExtractionMessage);
+                    Extractor.Message(ex.ExtractionMessage);
                 }
-                catch (Exception e)
+                catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
                 {
-                    Extractor.Message(new Message { severity = Severity.Error, exception = e, message = "Uncaught exception" });
+                    Extractor.Message(new Message { severity = Severity.Error, exception = ex, message = "Uncaught exception" });
                 }
             }
         }
@@ -504,7 +504,7 @@ static public void Try(this Context context, SyntaxNode node, ISymbol symbol, Ac
             {
                 a();
             }
-            catch (Exception ex)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
                 var internalError = ex as InternalError;
                 var message = internalError != null

csharp/extractor/Semmle.Extraction/Symbol.cs

@@ -57,7 +57,7 @@ protected void WithDuplicationGuard(System.Action a, IEntity location)
         public override bool Equals(object obj)
         {
             var other = obj as CachedEntity<Initializer>;
-            return obj != null && obj.GetType() == GetType() && Equals(other.symbol, symbol);
+            return other?.GetType() == GetType() && Equals(other.symbol, symbol);
         }
 
         public abstract TrapStackBehaviour TrapStackBehaviour { get; }

csharp/extractor/Semmle.Extraction/TrapWriter.cs

@@ -190,7 +190,7 @@ public void Dispose()
                     FileUtils.TryDelete(tmpFile);
                 }
             }
-            catch (Exception ex)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
                 Logger.Log(Severity.Error, "Failed to move the trap file from {0} to {1} because {2}", tmpFile, TrapFile, ex);
             }

csharp/extractor/Semmle.Util/CanonicalPathCache.cs

@@ -70,7 +70,7 @@ class GetFinalPathNameByHandleStrategy : PathStrategy
         /// <returns>The canonical path.</returns>
         public override string GetCanonicalPath(string path, IPathCache cache)
         {
-            using (var hFile = Win32.CreateFile(
+            using (var hFile = Win32.CreateFile(  // lgtm[cs/call-to-unmanaged-code]
                 path,
                 0,
                 Win32.FILE_SHARE_READ | Win32.FILE_SHARE_WRITE,
@@ -88,13 +88,13 @@ public override string GetCanonicalPath(string path, IPathCache cache)
                 else
                 {
                     StringBuilder outPath = new StringBuilder(Win32.MAX_PATH);
-                    int length = Win32.GetFinalPathNameByHandle(hFile, outPath, outPath.Capacity, 0);
+                    int length = Win32.GetFinalPathNameByHandle(hFile, outPath, outPath.Capacity, 0);  // lgtm[cs/call-to-unmanaged-code]
                     if (length >= outPath.Capacity)
                     {
                         // Path length exceeded MAX_PATH.
                         // Possible if target has a long path.
                         outPath = new StringBuilder(length + 1);
-                        length = Win32.GetFinalPathNameByHandle(hFile, outPath, outPath.Capacity, 0);
+                        length = Win32.GetFinalPathNameByHandle(hFile, outPath, outPath.Capacity, 0);  // lgtm[cs/call-to-unmanaged-code]
                     }
 
                     const int PREAMBLE = 4; // outPath always starts \\?\

csharp/extractor/Semmle.Util/Logger.cs

@@ -74,9 +74,9 @@ public FileLogger(Verbosity verbosity, string outputFile)
                     FileShare.ReadWrite, 8192));
                 writer.AutoFlush = true;
             }
-            catch (Exception e)
+            catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {
-                Console.Error.WriteLine("SEMMLE: Couldn't initialise C# extractor output: " + e.Message + "\n" + e.StackTrace);
+                Console.Error.WriteLine("SEMMLE: Couldn't initialise C# extractor output: " + ex.Message + "\n" + ex.StackTrace);
                 Console.Error.Flush();
                 throw;
             }

csharp/extractor/Semmle.Util/Win32.cs

@@ -11,14 +11,14 @@ namespace Semmle.Util
     public class Win32
     {
         [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
-        public static extern int GetFinalPathNameByHandle(
+        public static extern int GetFinalPathNameByHandle(  // lgtm[cs/unmanaged-code]
             SafeHandle handle,
             [In, Out] StringBuilder path,
             int bufLen,
             int flags);
 
         [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
-        public static extern SafeFileHandle CreateFile(
+        public static extern SafeFileHandle CreateFile(  // lgtm[cs/unmanaged-code]
             string filename,
             uint desiredAccess,
             uint shareMode,