path: root/Source/DafnyDriver/DafnyDriver.ssc

//-----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation.  All Rights Reserved.
//
//-----------------------------------------------------------------------------
//---------------------------------------------------------------------------------------------
// OnlyDafny OnlyDafny.ssc
//       - main program for taking a Dafny program and verifying it
//---------------------------------------------------------------------------------------------

namespace Microsoft.Boogie 
{
  using System;
  using System.IO;
  using System.Collections;
  using System.Collections.Generic;
  using PureCollections;
  using Microsoft.Boogie;
  using Microsoft.Boogie.AbstractInterpretation;
  using System.Diagnostics;
  using VC;
  using Cci = System.Compiler;
  using AI = Microsoft.AbstractInterpretationFramework;

/* 
  The following assemblies are referenced because they are needed at runtime, not at compile time:
    BaseTypes
    Provers.Z3
    System.Compiler.Framework
*/

  public class OnlyDafny
  {
    // ------------------------------------------------------------------------
    // Main
    
    public static void Main (string[]! args) 
    {
      assert forall{int i in (0:args.Length); args[i] != null};
      CommandLineOptions.Clo.RunningBoogieFromCommandLine = true;
      if (CommandLineOptions.Clo.Parse(args) != 1)
      {
        goto END;
      }
      if (CommandLineOptions.Clo.Files.Count == 0)
      {
        ErrorWriteLine("*** Error: No input files were specified.");
        goto END;
      }
      if (CommandLineOptions.Clo.XmlSink != null) {
        string errMsg = CommandLineOptions.Clo.XmlSink.Open();
        if (errMsg != null) {
          ErrorWriteLine("*** Error: " + errMsg);
          goto END;
        }
      }
      if (!CommandLineOptions.Clo.DontShowLogo)
      {
        Console.WriteLine(CommandLineOptions.Clo.Version);
      }
      if (CommandLineOptions.Clo.ShowEnv == CommandLineOptions.ShowEnvironment.Always) 
      {
        Console.WriteLine("---Command arguments");
        foreach (string! arg in args) 
        {
          Console.WriteLine(arg);
        }
        Console.WriteLine("--------------------");
      }

      SelectPlatform(CommandLineOptions.Clo);

      // Make sure the Spec# runtime is initialized.
      // This happens when the static constructor for the Runtime type is executed.
      // Otherwise, if a reference happens to get chased to it, it is loaded twice
      // and then the types in it do not get unique representations.
      if (System.Type.GetType("Mono.Runtime") == null) {  // MONO
        Cci.AssemblyNode a = Microsoft.SpecSharp.Runtime.RuntimeAssembly;
        assert a != null;
      }

      foreach (string! file in CommandLineOptions.Clo.Files) 
      {
        string extension = Path.GetExtension(file);
        if (extension != null) { extension = extension.ToLower(); }
        if (extension != ".dfy")
        {
            ErrorWriteLine("*** Error: '{0}': Filename extension '{1}' is not supported. Input files must be Dafny programs (.dfy).", file,
                extension == null ? "" : extension);
            goto END;
        }
      }
      CommandLineOptions.Clo.RunningBoogieOnSsc = false;
      ProcessFiles(CommandLineOptions.Clo.Files);

      END:
        if (CommandLineOptions.Clo.XmlSink != null) {
          CommandLineOptions.Clo.XmlSink.Close();
        }
        if (CommandLineOptions.Clo.Wait) 
        {
          Console.WriteLine("Press Enter to exit.");
          Console.ReadLine();
        }
    }

    public static void ErrorWriteLine(string! s) {
      if (!s.Contains("Error: ") && !s.Contains("Error BP")) {
        Console.WriteLine(s);
        return;
      }
      
      // split the string up into its first line and the remaining lines
      string remaining = null;
      int i = s.IndexOf('\r');
      if (0 <= i) {
        remaining = s.Substring(i+1);
        if (remaining.StartsWith("\n")) {
          remaining = remaining.Substring(1);
        }
        s = s.Substring(0, i);
      }
      
      ConsoleColor col = Console.ForegroundColor;
      Console.ForegroundColor = ConsoleColor.Red;
      Console.WriteLine(s);
      Console.ForegroundColor = col;
      
      if (remaining != null) {
        Console.WriteLine(remaining);
      }
    }

    public static void ErrorWriteLine(string! format, params object[] args) {
      string s = string.Format(format, args);
      ErrorWriteLine(s);
    }

    public static void AdvisoryWriteLine(string! format, params object[] args) {
      ConsoleColor col = Console.ForegroundColor;
      Console.ForegroundColor = ConsoleColor.Yellow;
      Console.WriteLine(format, args);
      Console.ForegroundColor = col;
    }

    public static void SelectPlatform(CommandLineOptions! options)
    {
      if (options.TargetPlatformLocation != null) {
        // Make sure static constructor runs before we start setting locations, etc.
        System.Compiler.SystemTypes.Clear();

        switch (options.TargetPlatform){
        case CommandLineOptions.PlatformType.v1: Microsoft.SpecSharp.TargetPlatform.SetToV1(options.TargetPlatformLocation); break;
        case CommandLineOptions.PlatformType.v11: Microsoft.SpecSharp.TargetPlatform.SetToV1_1(options.TargetPlatformLocation); break;
        case CommandLineOptions.PlatformType.v2: Microsoft.SpecSharp.TargetPlatform.SetToV2(options.TargetPlatformLocation); break;
        case CommandLineOptions.PlatformType.cli1: Microsoft.SpecSharp.TargetPlatform.SetToPostV1_1(options.TargetPlatformLocation); break;
        }
        
        if (options.StandardLibraryLocation != null && options.StandardLibraryLocation.Length > 0){
          System.Compiler.SystemAssemblyLocation.Location = options.StandardLibraryLocation;
        }
        System.Compiler.SystemCompilerRuntimeAssemblyLocation.Location = options.TargetPlatformLocation + @"\System.Compiler.Runtime.dll";
                
        System.Compiler.SystemTypes.Initialize(true, true);
      }
    }
  
    static string! GetErrorLine(Cci.ErrorNode! node)
        requires node.SourceContext.Document != null ==> node.SourceContext.Document.Name != null;
    {
      string message = node.GetMessage(System.Threading.Thread.CurrentThread.CurrentUICulture);
      string kind;
      if (message.Contains("(trace position)")) {
        kind = "Related information";
      } else {
        kind = "Error";
      }
      if (node.SourceContext.Document != null) {
        return string.Format("{0}({1},{2}): {3}: {4}", Path.GetFileName((!)node.SourceContext.Document.Name), node.SourceContext.StartLine, node.SourceContext.StartColumn, kind, message);
      } else {
        return string.Format("{0}: {1}", kind, message);
      }
    }

    enum FileType { Unknown, Cil, Bpl, Dafny };

    class ErrorReporter
    {
        public Cci.ErrorNodeList! errors = new Cci.ErrorNodeList();
        public int errorsReported;
        
        public void ReportErrors()
        {
            //sort the portion of the array that will be reported to make output more deterministic
            errors.Sort(errorsReported,errors.Count-errorsReported);
            for(;errorsReported < errors.Count; errorsReported++) {
                Cci.ErrorNode error = errors[errorsReported];
                if (error != null)
                    ErrorWriteLine(GetErrorLine(error));
            } 
        }
    }

    static void ProcessFiles (List<string!>! fileNames)
    {
      using (XmlFileScope xf = new XmlFileScope(CommandLineOptions.Clo.XmlSink, fileNames[fileNames.Count-1])) {
        Dafny.Program dafnyProgram;
        string programName = fileNames.Count == 1 ? fileNames[0] : "the program";
        string err = Dafny.Main.ParseCheck(fileNames, programName, out dafnyProgram);
        if (err != null) {
          ErrorWriteLine(err);
        } else if (dafnyProgram != null && !CommandLineOptions.Clo.NoResolve && !CommandLineOptions.Clo.NoTypecheck) {
          Dafny.Translator translator = new Dafny.Translator();
          Program boogieProgram = translator.Translate(dafnyProgram);
          if (CommandLineOptions.Clo.PrintFile != null) 
          {
            PrintBplFile(CommandLineOptions.Clo.PrintFile, boogieProgram, false);
          }

          string! bplFilename;
          if (CommandLineOptions.Clo.PrintFile != null) {
            bplFilename = CommandLineOptions.Clo.PrintFile;
          } else {
            string baseName = (!)Path.GetFileName(fileNames[fileNames.Count-1]);
            baseName = (!)Path.ChangeExtension(baseName, "bpl");
            bplFilename = Path.Combine(Path.GetTempPath(), baseName);
          }

          int errorCount, verified, inconclusives, timeOuts, outOfMemories;
          PipelineOutcome oc = BoogiePipelineWithRerun(boogieProgram, bplFilename, null/*new ErrorReporter()*/, out errorCount, out verified, out inconclusives, out timeOuts, out outOfMemories);
          switch (oc) {
            case PipelineOutcome.VerificationCompleted:
              if (CommandLineOptions.Clo.Compile) {
                string targetFilename = "out.cs";
                using (TextWriter target = new StreamWriter(new FileStream(targetFilename, System.IO.FileMode.Create))) {
                  Dafny.Compiler compiler = new Dafny.Compiler(target);
                  compiler.Compile(dafnyProgram);
                  WriteTrailer(verified, errorCount, inconclusives, timeOuts, outOfMemories);
                  if (compiler.ErrorCount == 0) {
                    Console.WriteLine("Compiled program written to {0}", targetFilename);
                  } else {
                    Console.WriteLine("File {0} contains the partially compiled program", targetFilename);
                  }
                }
              } else {
                WriteTrailer(verified, errorCount, inconclusives, timeOuts, outOfMemories);
              }
              break;
            case PipelineOutcome.Done:
              WriteTrailer(verified, errorCount, inconclusives, timeOuts, outOfMemories);
              break;
            default:
              // error has already been reported to user
              break;
          }
        }
      }
    }
    
    
    static void PrintBplFile (string! filename, Program! program, bool allowPrintDesugaring)
    {
        bool oldPrintDesugaring = CommandLineOptions.Clo.PrintDesugarings;
        if (!allowPrintDesugaring) {
          CommandLineOptions.Clo.PrintDesugarings = false;
        }
        using (TokenTextWriter writer = filename == "-" ?
                                        new TokenTextWriter("<console>", Console.Out) :
                                        new TokenTextWriter(filename))
        {
            writer.WriteLine("// " + CommandLineOptions.Clo.Version);
            writer.WriteLine("// " + CommandLineOptions.Clo.Environment);
            writer.WriteLine();
            program.Emit(writer);
        }
        CommandLineOptions.Clo.PrintDesugarings = oldPrintDesugaring;
    }
    
    
    static bool ProgramHasDebugInfo (Program! program)
    {
        // We inspect the last declaration because the first comes from the prelude and therefore always has source context.
        return program.TopLevelDeclarations.Count > 0 && 
            ((!)program.TopLevelDeclarations[program.TopLevelDeclarations.Count - 1]).tok.IsValid;
    }
    
    
    /// <summary>
    /// Inform the user about something and proceed with translation normally.
    /// Print newline after the message.
    /// </summary>
    public static void Inform(string s) {
      if ( ! CommandLineOptions.Clo.Trace) { return; }
      Console.WriteLine(s);
    }

    static void WriteTrailer(int verified, int errors, int inconclusives, int timeOuts, int outOfMemories)
      requires 0 <= errors && 0 <= inconclusives && 0 <= timeOuts && 0 <= outOfMemories;
    {
      Console.WriteLine();
      Console.Write("{0} finished with {1} verified, {2} error{3}", CommandLineOptions.Clo.ToolName, verified, errors, errors == 1 ? "" : "s");
      if (inconclusives != 0) {
        Console.Write(", {0} inconclusive{1}", inconclusives, inconclusives == 1 ? "" : "s");
      }
      if (timeOuts != 0) {
        Console.Write(", {0} time out{1}", timeOuts, timeOuts == 1 ? "" : "s");
      }
      if (outOfMemories != 0) {
        Console.Write(", {0} out of memory", outOfMemories);
      }
      Console.WriteLine();
      Console.Out.Flush();
    }

    

    static void ReportBplError(Absy! node, string! message, bool error)
    {
      IToken tok = node.tok;
      string s;
      if (tok == null) {
        s = message;
      } else {
        s = string.Format("{0}({1},{2}): {3}", tok.filename, tok.line, tok.col, message);
      }
      if (error) {
        ErrorWriteLine(s);
        if (CommandLineOptions.Clo.CEVPrint) {
          TextWriter mw = VC.VCGen.ErrorReporter.ModelWriter;
          mw.WriteLine("BEGINNING_OF_ERROR");
          mw.WriteLine(s);
          mw.WriteLine("END_OF_ERROR");
          mw.Flush();
        }
      } else {
        Console.WriteLine(s);
        if (CommandLineOptions.Clo.CEVPrint) {
          TextWriter mw = VC.VCGen.ErrorReporter.ModelWriter;
          mw.WriteLine("BEGINNING_OF_RELATED_INFO");
          mw.WriteLine(s);
          mw.WriteLine("END_OF_RELATED_INFO");
          mw.Flush();
        }
      }
    }

    /// <summary>
    /// Parse the given files into one Boogie program.  If an I/O or parse error occurs, an error will be printed
    /// and null will be returned.  On success, a non-null program is returned.
    /// </summary>
    static Program ParseBoogieProgram(List<string!>! fileNames, bool suppressTraceOutput)
    {
      BoogiePL.Errors.count = 0;
      Program program = null;
      bool okay = true;
      foreach (string bplFileName in fileNames) {
        if (!suppressTraceOutput) {
          if (CommandLineOptions.Clo.XmlSink != null) {
            CommandLineOptions.Clo.XmlSink.WriteFileFragment(bplFileName);
          }
          if (CommandLineOptions.Clo.Trace) {
            Console.WriteLine("Parsing " + bplFileName);
          }
        }

        Program programSnippet;
        int errorCount;
        try {
          errorCount = BoogiePL.Parser.Parse(bplFileName, out programSnippet);
          if (programSnippet == null || errorCount != 0) {
            Console.WriteLine("{0} parse errors detected in {1}", BoogiePL.Errors.count, bplFileName);
            okay = false;
            continue;
          }
        } catch (IOException e) {
          ErrorWriteLine("Error opening file \"{0}\": {1}", bplFileName, e.Message);
          okay = false;
          continue;
        }
        if (program == null) {
          program = programSnippet;
        } else if (programSnippet != null) {
          program.TopLevelDeclarations.AddRange(programSnippet.TopLevelDeclarations);
        }
      }
      if (!okay) {
        return null;
      } else if (program == null) {
        return new Program();
      } else {
        return program;
      }
    }
    
        /// <summary>
    /// Resolve, type check, infer invariants for, and verify the given Boogie program.
    /// The intention is that this Boogie program has been produced by translation from something
    /// else.  Hence, any resolution errors and type checking errors are due to errors in
    /// the translation.
    /// The method prints errors for resolution and type checking errors, but still returns
    /// their error code.
    /// </summary>
    static PipelineOutcome BoogiePipelineWithRerun (Program! program, string! bplFileName,
        ErrorReporter errorReporter,
        out int errorCount, out int verified, out int inconclusives, out int timeOuts, out int outOfMemories)
      ensures 0 <= inconclusives && 0 <= timeOuts;
    {
      errorCount = verified = inconclusives = timeOuts = outOfMemories = 0;
      PipelineOutcome oc = ResolveAndTypecheck(program, bplFileName);
      switch (oc) {
        case PipelineOutcome.Done:
          return oc;
          
        case PipelineOutcome.ResolutionError:
        case PipelineOutcome.TypeCheckingError:
          {
            PrintBplFile(bplFileName, program, false);
            Console.WriteLine();
            Console.WriteLine("*** Encountered internal translation error - re-running Boogie to get better debug information");
            Console.WriteLine();
            
            List<string!>! fileNames = new List<string!> ();
            fileNames.Add(bplFileName);
            Program reparsedProgram = ParseBoogieProgram(fileNames, true);
            if (reparsedProgram != null) {
              ResolveAndTypecheck(reparsedProgram, bplFileName);
            }
          }
          return oc;

        case PipelineOutcome.ResolvedAndTypeChecked:
          return InferAndVerify(program, errorReporter, out errorCount, out verified, out inconclusives, out timeOuts, out outOfMemories);
          
        default:
          assert false;  // unexpected outcome
      }
    }


    enum PipelineOutcome { Done, ResolutionError, TypeCheckingError, ResolvedAndTypeChecked, FatalError, VerificationCompleted }
    
    /// <summary>
    /// Resolves and type checks the given Boogie program.  Any errors are reported to the
    /// console.  Returns:
    ///  - Done if no errors occurred, and command line specified no resolution or no type checking.
    ///  - ResolutionError if a resolution error occurred
    ///  - TypeCheckingError if a type checking error occurred
    ///  - ResolvedAndTypeChecked if both resolution and type checking succeeded
    /// </summary>
    static PipelineOutcome ResolveAndTypecheck (Program! program, string! bplFileName)
    {
      // ---------- Resolve ------------------------------------------------------------

      if (CommandLineOptions.Clo.NoResolve) { return PipelineOutcome.Done; }

      int errorCount = program.Resolve();
      if (errorCount != 0) {
        Console.WriteLine("{0} name resolution errors detected in {1}", errorCount, bplFileName);
        return PipelineOutcome.ResolutionError;
      }

      // ---------- Type check ------------------------------------------------------------
      
      if (CommandLineOptions.Clo.NoTypecheck) { return PipelineOutcome.Done; }
      
      errorCount = program.Typecheck();
      if (errorCount != 0) {
        Console.WriteLine("{0} type checking errors detected in {1}", errorCount, bplFileName);
        return PipelineOutcome.TypeCheckingError;
      }
    
      if (CommandLineOptions.Clo.PrintFile != null && CommandLineOptions.Clo.PrintDesugarings) 
      {
        // if PrintDesugaring option is engaged, print the file here, after resolution and type checking
        PrintBplFile(CommandLineOptions.Clo.PrintFile, program, true);
      }

      return PipelineOutcome.ResolvedAndTypeChecked;
    }
    
    /// <summary>
    /// Given a resolved and type checked Boogie program, infers invariants for the program
    /// and then attempts to verify it.  Returns:
    ///  - Done if command line specified no verification
    ///  - FatalError if a fatal error occurred, in which case an error has been printed to console
    ///  - VerificationCompleted if inference and verification completed, in which the out
    ///    parameters contain meaningful values
    /// </summary>
    static PipelineOutcome InferAndVerify (Program! program,
                                           ErrorReporter errorReporter,
                                           out int errorCount, out int verified, out int inconclusives, out int timeOuts, out int outOfMemories)
      ensures 0 <= inconclusives && 0 <= timeOuts;
    {
      errorCount = verified = inconclusives = timeOuts = outOfMemories = 0;
  
      // ---------- Infer invariants --------------------------------------------------------
      
      // Abstract interpretation -> Always use (at least) intervals, if not specified otherwise (e.g. with the "/noinfer" switch)
      Microsoft.Boogie.AbstractInterpretation.AbstractInterpretation.RunAbstractInterpretation(program);
       
      if (CommandLineOptions.Clo.LoopUnrollCount != -1) {
        program.UnrollLoops(CommandLineOptions.Clo.LoopUnrollCount);
      }

      if (CommandLineOptions.Clo.PrintInstrumented) {
        program.Emit(new TokenTextWriter(Console.Out));
      }

      if (CommandLineOptions.Clo.ExpandLambdas) {
        LambdaHelper.ExpandLambdas(program);
        //PrintBplFile ("-", program, true);
      }

      // ---------- Verify ------------------------------------------------------------

      if (!CommandLineOptions.Clo.Verify) { return PipelineOutcome.Done; }
            
      #region Verify each implementation
      
#if ROB_DEBUG
      string now = DateTime.Now.ToString().Replace(' ','-').Replace('/','-').Replace(':','-');
      System.IO.StreamWriter w = new System.IO.StreamWriter(@"\temp\batch_"+now+".bpl");
      program.Emit(new TokenTextWriter(w));
      w.Close();
#endif

      ConditionGeneration vcgen = null;
      try
      {
        if (CommandLineOptions.Clo.vcVariety == CommandLineOptions.VCVariety.Doomed)
        {
          vcgen = new DCGen(program, CommandLineOptions.Clo.SimplifyLogFilePath, CommandLineOptions.Clo.SimplifyLogFileAppend);
        } else
        {
          vcgen = new VCGen(program, CommandLineOptions.Clo.SimplifyLogFilePath, CommandLineOptions.Clo.SimplifyLogFileAppend);
        }         
      }
      catch (ProverException e)
      {
        ErrorWriteLine("Fatal Error: ProverException: {0}", e);
        return PipelineOutcome.FatalError;
      }
      
      foreach ( Declaration! decl in program.TopLevelDeclarations )
      {
        Implementation impl = decl as Implementation;
        if (impl != null && CommandLineOptions.Clo.UserWantsToCheckRoutine((!)impl.Name) && !impl.SkipVerification) {
          List<Counterexample!>? errors;

          DateTime start = new DateTime();  // to please compiler's definite assignment rules
          if (CommandLineOptions.Clo.Trace || CommandLineOptions.Clo.XmlSink != null) {
            start = DateTime.Now;
            if (CommandLineOptions.Clo.Trace) {
              Console.WriteLine();
              Console.WriteLine("Verifying {0} ...", impl.Name);
            }
            if (CommandLineOptions.Clo.XmlSink != null) {
              CommandLineOptions.Clo.XmlSink.WriteStartMethod(impl.Name, start);
            }
          }

          ConditionGeneration.Outcome outcome;
          try
          {
            outcome = vcgen.VerifyImplementation(impl, program, out errors);
          }
          catch (VCGenException e)
          {
            ReportBplError(impl, String.Format("Error BP5010: {0}  Encountered in implementation {1}.", e.Message, impl.Name), true);
            errors = null;
            outcome = VCGen.Outcome.Inconclusive;
          }
          catch (UnexpectedProverOutputException upo)
          {
            AdvisoryWriteLine("Advisory: {0} SKIPPED because of internal error: unexpected prover output: {1}", impl.Name, upo.Message);
            errors = null;
            outcome = VCGen.Outcome.Inconclusive;
          }

          string! timeIndication = "";
          DateTime end = DateTime.Now;
          TimeSpan elapsed = end - start;
          if (CommandLineOptions.Clo.Trace || CommandLineOptions.Clo.XmlSink != null) {
            if (CommandLineOptions.Clo.Trace) {
              timeIndication = string.Format("  [{0} s]  ", elapsed.TotalSeconds);
            }
          }
          

          switch (outcome) {
            default:
              assert false;  // unexpected outcome
            case VCGen.Outcome.Correct:
              Inform(String.Format("{0}verified", timeIndication));
              verified++;
              break;
            case VCGen.Outcome.TimedOut:
              timeOuts++;
              Inform(String.Format("{0}timed out", timeIndication));
              break;
            case VCGen.Outcome.OutOfMemory:
              outOfMemories++;
              Inform(String.Format("{0}out of memory", timeIndication));
              break;
            case VCGen.Outcome.Inconclusive:
              inconclusives++;
              Inform(String.Format("{0}inconclusive", timeIndication));
              break;
            case VCGen.Outcome.Errors:
              assert errors != null;  // guaranteed by postcondition of VerifyImplementation
              if (errorReporter != null)
              {
//                assert translatedProgram != null;
//                ErrorReporting h = new ErrorReporting();
//                h.errorReportingWithTrace(translatedProgram, errors, impl);
                
                errorReporter.ReportErrors();
              }
              else
              {
                // BP1xxx: Parsing errors
                // BP2xxx: Name resolution errors
                // BP3xxx: Typechecking errors
                // BP4xxx: Abstract interpretation errors (Is there such a thing?)
                // BP5xxx: Verification errors
                
                errors.Sort(new CounterexampleComparer());
                foreach (Counterexample error in errors)
                {
                  if (error is CallCounterexample)
                  {
                    CallCounterexample! err = (CallCounterexample) error;
                    ReportBplError(err.FailingCall, "Error BP5002: A precondition for this call might not hold.", true);
                    ReportBplError(err.FailingRequires, "Related location: This is the precondition that might not hold.", false);
                    if (CommandLineOptions.Clo.XmlSink != null) {
                      CommandLineOptions.Clo.XmlSink.WriteError("precondition violation", err.FailingCall.tok, err.FailingRequires.tok, error.Trace);
                    }
                  }
                  else if (error is ReturnCounterexample)
                  {
                    ReturnCounterexample! err = (ReturnCounterexample) error;
                    ReportBplError(err.FailingReturn, "Error BP5003: A postcondition might not hold at this return statement.", true);
                    ReportBplError(err.FailingEnsures, "Related location: This is the postcondition that might not hold.", false);
                    if (CommandLineOptions.Clo.XmlSink != null) {
                      CommandLineOptions.Clo.XmlSink.WriteError("postcondition violation", err.FailingReturn.tok, err.FailingEnsures.tok, error.Trace);
                    }
                  }
                  else // error is AssertCounterexample
                  {
                    AssertCounterexample! err = (AssertCounterexample) error;
                    if (err.FailingAssert is LoopInitAssertCmd) {
                      ReportBplError(err.FailingAssert, "Error BP5004: This loop invariant might not hold on entry.", true);
                      if (CommandLineOptions.Clo.XmlSink != null) {
                        CommandLineOptions.Clo.XmlSink.WriteError("loop invariant entry violation", err.FailingAssert.tok, null, error.Trace);
                      }
                    }
                    else if (err.FailingAssert is LoopInvMaintainedAssertCmd) {
                      // this assertion is a loop invariant which is not maintained
                      ReportBplError(err.FailingAssert, "Error BP5005: This loop invariant might not be maintained by the loop.", true);
                      if (CommandLineOptions.Clo.XmlSink != null) {
                        CommandLineOptions.Clo.XmlSink.WriteError("loop invariant maintenance violation", err.FailingAssert.tok, null, error.Trace);
                      }
                    } else {
                      string msg = err.FailingAssert.ErrorData as string;
                      if (msg == null) {
                        msg = "Error BP5001: This assertion might not hold.";
                      }
                      ReportBplError(err.FailingAssert, msg, true);
                      if (CommandLineOptions.Clo.XmlSink != null) {
                        CommandLineOptions.Clo.XmlSink.WriteError("assertion violation", err.FailingAssert.tok, null, error.Trace);
                      }
                    }
                  }
                  if (CommandLineOptions.Clo.EnhancedErrorMessages == 1) { 
                    foreach (string! info in error.relatedInformation) {
                      Console.WriteLine("       " + info);
                    } 
                  }
                  if (CommandLineOptions.Clo.ErrorTrace > 0) {
                    Console.WriteLine("Execution trace:");
                    foreach (Block! b in error.Trace) {
                      if (b.tok == null) {
                        Console.WriteLine("    <intermediate block>");
                      } else {
                        // for ErrorTrace == 1 restrict the output; 
                        // do not print tokens with -17:-4 as their location because they have been 
                        // introduced in the translation and do not give any useful feedback to the user
                        if (!(CommandLineOptions.Clo.ErrorTrace == 1 && b.tok.line == -17 && b.tok.col == -4)) {
                          Console.WriteLine("    {0}({1},{2}): {3}", b.tok.filename, b.tok.line, b.tok.col, b.Label);
                        }
                      }
                    }
                  }
                  errorCount++;
                  }
              }
              Inform(String.Format("{0}error{1}", timeIndication, errors.Count == 1 ? "" : "s"));
              break;
          }
          if (CommandLineOptions.Clo.XmlSink != null) {
            CommandLineOptions.Clo.XmlSink.WriteEndMethod(outcome.ToString().ToLowerInvariant(), end, elapsed);
          }
          if (outcome == VCGen.Outcome.Errors || CommandLineOptions.Clo.Trace) {
            Console.Out.Flush();
          }
        }
      }
      vcgen.Close();
      ((!)CommandLineOptions.Clo.TheProverFactory).Close();

      #endregion
      
      return PipelineOutcome.VerificationCompleted;
    }
   
  }
}