text: //===--- Preprocess.cpp - C Language Family Preprocessor Implementation ---===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file implements the Preprocessor interface.
  //
  //===----------------------------------------------------------------------===//
  //
  // Options to support:
  //   -H       - Print the name of each header file used.
  //   -d[DNI] - Dump various things.
  //   -fworking-directory - #line's with preprocessor's working dir.
  //   -fpreprocessed
  //   -dependency-file,-M,-MM,-MF,-MG,-MP,-MT,-MQ,-MD,-MMD
  //   -W*
  //   -w
  //
  // Messages to emit:
  //   "Multiple include guards may be useful for:\n"
  //
  //===----------------------------------------------------------------------===//
  
  #include "clang/Lex/Preprocessor.h"
  #include "clang/Basic/FileManager.h"
  #include "clang/Basic/FileSystemStatCache.h"
  #include "clang/Basic/SourceManager.h"
  #include "clang/Basic/TargetInfo.h"
  #include "clang/Lex/CodeCompletionHandler.h"
  #include "clang/Lex/ExternalPreprocessorSource.h"
  #include "clang/Lex/HeaderSearch.h"
  #include "clang/Lex/LexDiagnostic.h"
  #include "clang/Lex/LiteralSupport.h"
  #include "clang/Lex/MacroArgs.h"
  #include "clang/Lex/MacroInfo.h"
  #include "clang/Lex/ModuleLoader.h"
  #include "clang/Lex/Pragma.h"
  #include "clang/Lex/PreprocessingRecord.h"
  #include "clang/Lex/PreprocessorOptions.h"
  #include "clang/Lex/ScratchBuffer.h"
  #include "llvm/ADT/APFloat.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/Support/Capacity.h"
  #include "llvm/Support/ConvertUTF.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/raw_ostream.h"
  using namespace clang;
  
  //===----------------------------------------------------------------------===//
  ExternalPreprocessorSource::~ExternalPreprocessorSource() { }
  
  Preprocessor::Preprocessor(IntrusiveRefCntPtr<PreprocessorOptions> PPOpts,
                             DiagnosticsEngine &diags, LangOptions &opts,
                             SourceManager &SM, HeaderSearch &Headers,
                             ModuleLoader &TheModuleLoader,
                             IdentifierInfoLookup *IILookup, bool OwnsHeaders,
                             TranslationUnitKind TUKind)
      : PPOpts(PPOpts), Diags(&diags), LangOpts(opts), Target(nullptr),
        AuxTarget(nullptr), FileMgr(Headers.getFileMgr()), SourceMgr(SM),
        ScratchBuf(new ScratchBuffer(SourceMgr)), HeaderInfo(Headers),
        TheModuleLoader(TheModuleLoader), ExternalSource(nullptr),
        Identifiers(opts, IILookup),
        PragmaHandlers(new PragmaNamespace(StringRef())),
        IncrementalProcessing(false), TUKind(TUKind), CodeComplete(nullptr),
        CodeCompletionFile(nullptr), CodeCompletionOffset(0),
        LastTokenWasAt(false), ModuleImportExpectsIdentifier(false),
        CodeCompletionReached(0), MainFileDir(nullptr),
        SkipMainFilePreamble(0, true), CurPPLexer(nullptr), CurDirLookup(nullptr),
        CurLexerKind(CLK_Lexer), CurSubmodule(nullptr), Callbacks(nullptr),
        CurSubmoduleState(&NullSubmoduleState), MacroArgCache(nullptr),
        Record(nullptr), MIChainHead(nullptr), DeserialMIChainHead(nullptr) {
    OwnsHeaderSearch = OwnsHeaders;
    
    CounterValue = 0; // __COUNTER__ starts at 0.
    
    // Clear stats.
    NumDirectives = NumDefined = NumUndefined = NumPragma = 0;
    NumIf = NumElse = NumEndif = 0;
    NumEnteredSourceFiles = 0;
    NumMacroExpanded = NumFnMacroExpanded = NumBuiltinMacroExpanded = 0;
    NumFastMacroExpanded = NumTokenPaste = NumFastTokenPaste = 0;
    MaxIncludeStackDepth = 0;
    NumSkipped = 0;
    
    // Default to discarding comments.
    KeepComments = false;
    KeepMacroComments = false;
    SuppressIncludeNotFoundError = false;
    
    // Macro expansion is enabled.
    DisableMacroExpansion = false;
    MacroExpansionInDirectivesOverride = false;
    InMacroArgs = false;
    InMacroArgPreExpansion = false;
    NumCachedTokenLexers = 0;
    PragmasEnabled = true;
    ParsingIfOrElifDirective = false;
    PreprocessedOutput = false;
  
    CachedLexPos = 0;
  
    // We haven't read anything from the external source.
    ReadMacrosFromExternalSource = false;
    
    // "Poison" __VA_ARGS__, which can only appear in the expansion of a macro.
    // This gets unpoisoned where it is allowed.
    (Ident__VA_ARGS__ = getIdentifierInfo("__VA_ARGS__"))->setIsPoisoned();
    SetPoisonReason(Ident__VA_ARGS__,diag::ext_pp_bad_vaargs_use);
    
    // Initialize the pragma handlers.
    RegisterBuiltinPragmas();
    
    // Initialize builtin macros like __LINE__ and friends.
    RegisterBuiltinMacros();
    
    if(LangOpts.Borland) {
      Ident__exception_info        = getIdentifierInfo("_exception_info");
      Ident___exception_info       = getIdentifierInfo("__exception_info");
      Ident_GetExceptionInfo       = getIdentifierInfo("GetExceptionInformation");
      Ident__exception_code        = getIdentifierInfo("_exception_code");
      Ident___exception_code       = getIdentifierInfo("__exception_code");
      Ident_GetExceptionCode       = getIdentifierInfo("GetExceptionCode");
      Ident__abnormal_termination  = getIdentifierInfo("_abnormal_termination");
      Ident___abnormal_termination = getIdentifierInfo("__abnormal_termination");
      Ident_AbnormalTermination    = getIdentifierInfo("AbnormalTermination");
    } else {
      Ident__exception_info = Ident__exception_code = nullptr;
      Ident__abnormal_termination = Ident___exception_info = nullptr;
      Ident___exception_code = Ident___abnormal_termination = nullptr;
      Ident_GetExceptionInfo = Ident_GetExceptionCode = nullptr;
      Ident_AbnormalTermination = nullptr;
    }
  }
  
  Preprocessor::~Preprocessor() {
    assert(BacktrackPositions.empty() && "EnableBacktrack/Backtrack imbalance!");
  
    IncludeMacroStack.clear();
  
    // Destroy any macro definitions.
    while (MacroInfoChain *I = MIChainHead) {
      MIChainHead = I->Next;
      I->~MacroInfoChain();
    }
  
    // Free any cached macro expanders.
    // This populates MacroArgCache, so all TokenLexers need to be destroyed
    // before the code below that frees up the MacroArgCache list.
    std::fill(TokenLexerCache, TokenLexerCache + NumCachedTokenLexers, nullptr);
    CurTokenLexer.reset();
  
    while (DeserializedMacroInfoChain *I = DeserialMIChainHead) {
      DeserialMIChainHead = I->Next;
      I->~DeserializedMacroInfoChain();
    }
  
    // Free any cached MacroArgs.
    for (MacroArgs *ArgList = MacroArgCache; ArgList;)
      ArgList = ArgList->deallocate();
  
    // Delete the header search info, if we own it.
    if (OwnsHeaderSearch)
      delete &HeaderInfo;
  }
  
  void Preprocessor::Initialize(const TargetInfo &Target,
                                const TargetInfo *AuxTarget) {
    assert((!this->Target || this->Target == &Target) &&
           "Invalid override of target information");
    this->Target = &Target;
  
    assert((!this->AuxTarget || this->AuxTarget == AuxTarget) &&
           "Invalid override of aux target information.");
    this->AuxTarget = AuxTarget;
  
    // Initialize information about built-ins.
    BuiltinInfo.InitializeTarget(Target, AuxTarget);
    HeaderInfo.setTarget(Target);
  }
  
  void Preprocessor::InitializeForModelFile() {
    NumEnteredSourceFiles = 0;
  
    // Reset pragmas
    PragmaHandlersBackup = std::move(PragmaHandlers);
    PragmaHandlers = llvm::make_unique<PragmaNamespace>(StringRef());
    RegisterBuiltinPragmas();
  
    // Reset PredefinesFileID
    PredefinesFileID = FileID();
  }
  
  void Preprocessor::FinalizeForModelFile() {
    NumEnteredSourceFiles = 1;
  
    PragmaHandlers = std::move(PragmaHandlersBackup);
  }
  
  void Preprocessor::setPTHManager(PTHManager* pm) {
    PTH.reset(pm);
    FileMgr.addStatCache(PTH->createStatCache());
  }
  
  void Preprocessor::DumpToken(const Token &Tok, bool DumpFlags) const {
    llvm::errs() << tok::getTokenName(Tok.getKind()) << " '"
                 << getSpelling(Tok) << "'";
  
    if (!DumpFlags) return;
  
    llvm::errs() << "\t";
    if (Tok.isAtStartOfLine())
      llvm::errs() << " [StartOfLine]";
    if (Tok.hasLeadingSpace())
      llvm::errs() << " [LeadingSpace]";
    if (Tok.isExpandDisabled())
      llvm::errs() << " [ExpandDisabled]";
    if (Tok.needsCleaning()) {
      const char *Start = SourceMgr.getCharacterData(Tok.getLocation());
      llvm::errs() << " [UnClean='" << StringRef(Start, Tok.getLength())
                   << "']";
    }
  
    llvm::errs() << "\tLoc=<";
    DumpLocation(Tok.getLocation());
    llvm::errs() << ">";
  }
  
  void Preprocessor::DumpLocation(SourceLocation Loc) const {
    Loc.dump(SourceMgr);
  }
  
  void Preprocessor::DumpMacro(const MacroInfo &MI) const {
    llvm::errs() << "MACRO: ";
    for (unsigned i = 0, e = MI.getNumTokens(); i != e; ++i) {
      DumpToken(MI.getReplacementToken(i));
      llvm::errs() << "  ";
    }
    llvm::errs() << "\n";
  }
  
  void Preprocessor::PrintStats() {
    llvm::errs() << "\n*** Preprocessor Stats:\n";
    llvm::errs() << NumDirectives << " directives found:\n";
    llvm::errs() << "  " << NumDefined << " #define.\n";
    llvm::errs() << "  " << NumUndefined << " #undef.\n";
    llvm::errs() << "  #include/#include_next/#import:\n";
    llvm::errs() << "    " << NumEnteredSourceFiles << " source files entered.\n";
    llvm::errs() << "    " << MaxIncludeStackDepth << " max include stack depth\n";
    llvm::errs() << "  " << NumIf << " #if/#ifndef/#ifdef.\n";
    llvm::errs() << "  " << NumElse << " #else/#elif.\n";
    llvm::errs() << "  " << NumEndif << " #endif.\n";
    llvm::errs() << "  " << NumPragma << " #pragma.\n";
    llvm::errs() << NumSkipped << " #if/#ifndef#ifdef regions skipped\n";
  
    llvm::errs() << NumMacroExpanded << "/" << NumFnMacroExpanded << "/"
               << NumBuiltinMacroExpanded << " obj/fn/builtin macros expanded, "
               << NumFastMacroExpanded << " on the fast path.\n";
    llvm::errs() << (NumFastTokenPaste+NumTokenPaste)
               << " token paste (##) operations performed, "
               << NumFastTokenPaste << " on the fast path.\n";
  
    llvm::errs() << "\nPreprocessor Memory: " << getTotalMemory() << "B total";
  
    llvm::errs() << "\n  BumpPtr: " << BP.getTotalMemory();
    llvm::errs() << "\n  Macro Expanded Tokens: "
                 << llvm::capacity_in_bytes(MacroExpandedTokens);
    llvm::errs() << "\n  Predefines Buffer: " << Predefines.capacity();
    // FIXME: List information for all submodules.
    llvm::errs() << "\n  Macros: "
                 << llvm::capacity_in_bytes(CurSubmoduleState->Macros);
    llvm::errs() << "\n  #pragma push_macro Info: "
                 << llvm::capacity_in_bytes(PragmaPushMacroInfo);
    llvm::errs() << "\n  Poison Reasons: "
                 << llvm::capacity_in_bytes(PoisonReasons);
    llvm::errs() << "\n  Comment Handlers: "
                 << llvm::capacity_in_bytes(CommentHandlers) << "\n";
  }
  
  Preprocessor::macro_iterator
  Preprocessor::macro_begin(bool IncludeExternalMacros) const {
    if (IncludeExternalMacros && ExternalSource &&
        !ReadMacrosFromExternalSource) {
      ReadMacrosFromExternalSource = true;
      ExternalSource->ReadDefinedMacros();
    }
  
    // Make sure we cover all macros in visible modules.
    for (const ModuleMacro &Macro : ModuleMacros)
      CurSubmoduleState->Macros.insert(std::make_pair(Macro.II, MacroState()));
  
    return CurSubmoduleState->Macros.begin();
  }
  
  size_t Preprocessor::getTotalMemory() const {
    return BP.getTotalMemory()
      + llvm::capacity_in_bytes(MacroExpandedTokens)
      + Predefines.capacity() /* Predefines buffer. */
      // FIXME: Include sizes from all submodules, and include MacroInfo sizes,
      // and ModuleMacros.
      + llvm::capacity_in_bytes(CurSubmoduleState->Macros)
      + llvm::capacity_in_bytes(PragmaPushMacroInfo)
      + llvm::capacity_in_bytes(PoisonReasons)
      + llvm::capacity_in_bytes(CommentHandlers);
  }
  
  Preprocessor::macro_iterator
  Preprocessor::macro_end(bool IncludeExternalMacros) const {
    if (IncludeExternalMacros && ExternalSource &&
        !ReadMacrosFromExternalSource) {
      ReadMacrosFromExternalSource = true;
      ExternalSource->ReadDefinedMacros();
    }
  
    return CurSubmoduleState->Macros.end();
  }
  
  /// \brief Compares macro tokens with a specified token value sequence.
  static bool MacroDefinitionEquals(const MacroInfo *MI,
                                    ArrayRef<TokenValue> Tokens) {
    return Tokens.size() == MI->getNumTokens() &&
        std::equal(Tokens.begin(), Tokens.end(), MI->tokens_begin());
  }
  
  StringRef Preprocessor::getLastMacroWithSpelling(
                                      SourceLocation Loc,
                                      ArrayRef<TokenValue> Tokens) const {
    SourceLocation BestLocation;
    StringRef BestSpelling;
    for (Preprocessor::macro_iterator I = macro_begin(), E = macro_end();
         I != E; ++I) {
      const MacroDirective::DefInfo
        Def = I->second.findDirectiveAtLoc(Loc, SourceMgr);
      if (!Def || !Def.getMacroInfo())
        continue;
      if (!Def.getMacroInfo()->isObjectLike())
        continue;
      if (!MacroDefinitionEquals(Def.getMacroInfo(), Tokens))
        continue;
      SourceLocation Location = Def.getLocation();
      // Choose the macro defined latest.
      if (BestLocation.isInvalid() ||
          (Location.isValid() &&
           SourceMgr.isBeforeInTranslationUnit(BestLocation, Location))) {
        BestLocation = Location;
        BestSpelling = I->first->getName();
      }
    }
    return BestSpelling;
  }
  
  void Preprocessor::recomputeCurLexerKind() {
    if (CurLexer)
      CurLexerKind = CLK_Lexer;
    else if (CurPTHLexer)
      CurLexerKind = CLK_PTHLexer;
    else if (CurTokenLexer)
      CurLexerKind = CLK_TokenLexer;
    else 
      CurLexerKind = CLK_CachingLexer;
  }
  
  bool Preprocessor::SetCodeCompletionPoint(const FileEntry *File,
                                            unsigned CompleteLine,
                                            unsigned CompleteColumn) {
    assert(File);
    assert(CompleteLine && CompleteColumn && "Starts from 1:1");
    assert(!CodeCompletionFile && "Already set");
  
    using llvm::MemoryBuffer;
  
    // Load the actual file's contents.
    bool Invalid = false;
    const MemoryBuffer *Buffer = SourceMgr.getMemoryBufferForFile(File, &Invalid);
    if (Invalid)
      return true;
  
    // Find the byte position of the truncation point.
    const char *Position = Buffer->getBufferStart();
    for (unsigned Line = 1; Line < CompleteLine; ++Line) {
      for (; *Position; ++Position) {
        if (*Position != '\r' && *Position != '\n')
          continue;
  
        // Eat \r\n or \n\r as a single line.
        if ((Position[1] == '\r' || Position[1] == '\n') &&
            Position[0] != Position[1])
          ++Position;
        ++Position;
        break;
      }
    }
  
    Position += CompleteColumn - 1;
  
    // If pointing inside the preamble, adjust the position at the beginning of
    // the file after the preamble.
    if (SkipMainFilePreamble.first &&
        SourceMgr.getFileEntryForID(SourceMgr.getMainFileID()) == File) {
      if (Position - Buffer->getBufferStart() < SkipMainFilePreamble.first)
        Position = Buffer->getBufferStart() + SkipMainFilePreamble.first;
    }
  
    if (Position > Buffer->getBufferEnd())
      Position = Buffer->getBufferEnd();
  
    CodeCompletionFile = File;
    CodeCompletionOffset = Position - Buffer->getBufferStart();
  
    std::unique_ptr<MemoryBuffer> NewBuffer =
        MemoryBuffer::getNewUninitMemBuffer(Buffer->getBufferSize() + 1,
                                            Buffer->getBufferIdentifier());
    char *NewBuf = const_cast<char*>(NewBuffer->getBufferStart());
    char *NewPos = std::copy(Buffer->getBufferStart(), Position, NewBuf);
    *NewPos = '\0';
    std::copy(Position, Buffer->getBufferEnd(), NewPos+1);
    SourceMgr.overrideFileContents(File, std::move(NewBuffer));
  
    return false;
  }
  
  void Preprocessor::CodeCompleteNaturalLanguage() {
    if (CodeComplete)
      CodeComplete->CodeCompleteNaturalLanguage();
    setCodeCompletionReached();
  }
  
  /// getSpelling - This method is used to get the spelling of a token into a
  /// SmallVector. Note that the returned StringRef may not point to the
  /// supplied buffer if a copy can be avoided.
  StringRef Preprocessor::getSpelling(const Token &Tok,
                                            SmallVectorImpl<char> &Buffer,
                                            bool *Invalid) const {
    // NOTE: this has to be checked *before* testing for an IdentifierInfo.
    if (Tok.isNot(tok::raw_identifier) && !Tok.hasUCN()) {
      // Try the fast path.
      if (const IdentifierInfo *II = Tok.getIdentifierInfo())
        return II->getName();
    }
  
    // Resize the buffer if we need to copy into it.
    if (Tok.needsCleaning())
      Buffer.resize(Tok.getLength());
  
    const char *Ptr = Buffer.data();
    unsigned Len = getSpelling(Tok, Ptr, Invalid);
    return StringRef(Ptr, Len);
  }
  
  /// CreateString - Plop the specified string into a scratch buffer and return a
  /// location for it.  If specified, the source location provides a source
  /// location for the token.
  void Preprocessor::CreateString(StringRef Str, Token &Tok,
                                  SourceLocation ExpansionLocStart,
                                  SourceLocation ExpansionLocEnd) {
    Tok.setLength(Str.size());
  
    const char *DestPtr;
    SourceLocation Loc = ScratchBuf->getToken(Str.data(), Str.size(), DestPtr);
  
    if (ExpansionLocStart.isValid())
      Loc = SourceMgr.createExpansionLoc(Loc, ExpansionLocStart,
                                         ExpansionLocEnd, Str.size());
    Tok.setLocation(Loc);
  
    // If this is a raw identifier or a literal token, set the pointer data.
    if (Tok.is(tok::raw_identifier))
      Tok.setRawIdentifierData(DestPtr);
    else if (Tok.isLiteral())
      Tok.setLiteralData(DestPtr);
  }
  
  Module *Preprocessor::getCurrentModule() {
    if (getLangOpts().CurrentModule.empty())
      return nullptr;
  
    return getHeaderSearchInfo().lookupModule(getLangOpts().CurrentModule);
  }
  
  //===----------------------------------------------------------------------===//
  // Preprocessor Initialization Methods
  //===----------------------------------------------------------------------===//
  
  
  /// EnterMainSourceFile - Enter the specified FileID as the main source file,
  /// which implicitly adds the builtin defines etc.
  void Preprocessor::EnterMainSourceFile() {
    // We do not allow the preprocessor to reenter the main file.  Doing so will
    // cause FileID's to accumulate information from both runs (e.g. #line
    // information) and predefined macros aren't guaranteed to be set properly.
    assert(NumEnteredSourceFiles == 0 && "Cannot reenter the main file!");
    FileID MainFileID = SourceMgr.getMainFileID();
  
    // If MainFileID is loaded it means we loaded an AST file, no need to enter
    // a main file.
    if (!SourceMgr.isLoadedFileID(MainFileID)) {
      // Enter the main file source buffer.
      EnterSourceFile(MainFileID, nullptr, SourceLocation());
  
      // If we've been asked to skip bytes in the main file (e.g., as part of a
      // precompiled preamble), do so now.
      if (SkipMainFilePreamble.first > 0)
        CurLexer->SkipBytes(SkipMainFilePreamble.first, 
                            SkipMainFilePreamble.second);
      
      // Tell the header info that the main file was entered.  If the file is later
      // #imported, it won't be re-entered.
      if (const FileEntry *FE = SourceMgr.getFileEntryForID(MainFileID))
        HeaderInfo.IncrementIncludeCount(FE);
    }
  
    // Preprocess Predefines to populate the initial preprocessor state.
    std::unique_ptr<llvm::MemoryBuffer> SB =
      llvm::MemoryBuffer::getMemBufferCopy(Predefines, "<built-in>");
    assert(SB && "Cannot create predefined source buffer");
    FileID FID = SourceMgr.createFileID(std::move(SB));
    assert(!FID.isInvalid() && "Could not create FileID for predefines?");
    setPredefinesFileID(FID);
  
    // Start parsing the predefines.
    EnterSourceFile(FID, nullptr, SourceLocation());
  }
  
  void Preprocessor::EndSourceFile() {
    // Notify the client that we reached the end of the source file.
    if (Callbacks)
      Callbacks->EndOfMainFile();
  }
  
  //===----------------------------------------------------------------------===//
  // Lexer Event Handling.
  //===----------------------------------------------------------------------===//
  
  /// LookUpIdentifierInfo - Given a tok::raw_identifier token, look up the
  /// identifier information for the token and install it into the token,
  /// updating the token kind accordingly.
  IdentifierInfo *Preprocessor::LookUpIdentifierInfo(Token &Identifier) const {
    assert(!Identifier.getRawIdentifier().empty() && "No raw identifier data!");
  
    // Look up this token, see if it is a macro, or if it is a language keyword.
    IdentifierInfo *II;
    if (!Identifier.needsCleaning() && !Identifier.hasUCN()) {
      // No cleaning needed, just use the characters from the lexed buffer.
      II = getIdentifierInfo(Identifier.getRawIdentifier());
    } else {
      // Cleaning needed, alloca a buffer, clean into it, then use the buffer.
      SmallString<64> IdentifierBuffer;
      StringRef CleanedStr = getSpelling(Identifier, IdentifierBuffer);
  
      if (Identifier.hasUCN()) {
        SmallString<64> UCNIdentifierBuffer;
        expandUCNs(UCNIdentifierBuffer, CleanedStr);
        II = getIdentifierInfo(UCNIdentifierBuffer);
      } else {
        II = getIdentifierInfo(CleanedStr);
      }
    }
  
    // Update the token info (identifier info and appropriate token kind).
    Identifier.setIdentifierInfo(II);
    Identifier.setKind(II->getTokenID());
  
    return II;
  }
  
  void Preprocessor::SetPoisonReason(IdentifierInfo *II, unsigned DiagID) {
    PoisonReasons[II] = DiagID;
  }
  
  void Preprocessor::PoisonSEHIdentifiers(bool Poison) {
    assert(Ident__exception_code && Ident__exception_info);
    assert(Ident___exception_code && Ident___exception_info);
    Ident__exception_code->setIsPoisoned(Poison);
    Ident___exception_code->setIsPoisoned(Poison);
    Ident_GetExceptionCode->setIsPoisoned(Poison);
    Ident__exception_info->setIsPoisoned(Poison);
    Ident___exception_info->setIsPoisoned(Poison);
    Ident_GetExceptionInfo->setIsPoisoned(Poison);
    Ident__abnormal_termination->setIsPoisoned(Poison);
    Ident___abnormal_termination->setIsPoisoned(Poison);
    Ident_AbnormalTermination->setIsPoisoned(Poison);
  }
  
  void Preprocessor::HandlePoisonedIdentifier(Token & Identifier) {
    assert(Identifier.getIdentifierInfo() &&
           "Can't handle identifiers without identifier info!");
    llvm::DenseMap<IdentifierInfo*,unsigned>::const_iterator it =
      PoisonReasons.find(Identifier.getIdentifierInfo());
    if(it == PoisonReasons.end())
      Diag(Identifier, diag::err_pp_used_poisoned_id);
    else
      Diag(Identifier,it->second) << Identifier.getIdentifierInfo();
  }
  
  /// \brief Returns a diagnostic message kind for reporting a future keyword as
  /// appropriate for the identifier and specified language.
  static diag::kind getFutureCompatDiagKind(const IdentifierInfo &II,
                                            const LangOptions &LangOpts) {
    assert(II.isFutureCompatKeyword() && "diagnostic should not be needed");
  
    if (LangOpts.CPlusPlus)
      return llvm::StringSwitch<diag::kind>(II.getName())
  #define CXX11_KEYWORD(NAME, FLAGS)                                             \
          .Case(#NAME, diag::warn_cxx11_keyword)
  #include "clang/Basic/TokenKinds.def"
          ;
  
    llvm_unreachable(
        "Keyword not known to come from a newer Standard or proposed Standard");
  }
  
  /// HandleIdentifier - This callback is invoked when the lexer reads an
  /// identifier.  This callback looks up the identifier in the map and/or
  /// potentially macro expands it or turns it into a named token (like 'for').
  ///
  /// Note that callers of this method are guarded by checking the
  /// IdentifierInfo's 'isHandleIdentifierCase' bit.  If this method changes, the
  /// IdentifierInfo methods that compute these properties will need to change to
  /// match.
  bool Preprocessor::HandleIdentifier(Token &Identifier) {
    assert(Identifier.getIdentifierInfo() &&
           "Can't handle identifiers without identifier info!");
  
    IdentifierInfo &II = *Identifier.getIdentifierInfo();
  
    // If the information about this identifier is out of date, update it from
    // the external source.
    // We have to treat __VA_ARGS__ in a special way, since it gets
    // serialized with isPoisoned = true, but our preprocessor may have
    // unpoisoned it if we're defining a C99 macro.
    if (II.isOutOfDate()) {
      bool CurrentIsPoisoned = false;
      if (&II == Ident__VA_ARGS__)
        CurrentIsPoisoned = Ident__VA_ARGS__->isPoisoned();
  
      ExternalSource->updateOutOfDateIdentifier(II);
      Identifier.setKind(II.getTokenID());
  
      if (&II == Ident__VA_ARGS__)
        II.setIsPoisoned(CurrentIsPoisoned);
    }
    
    // If this identifier was poisoned, and if it was not produced from a macro
    // expansion, emit an error.
    if (II.isPoisoned() && CurPPLexer) {
      HandlePoisonedIdentifier(Identifier);
    }
  
    // If this is a macro to be expanded, do it.
    if (MacroDefinition MD = getMacroDefinition(&II)) {
      auto *MI = MD.getMacroInfo();
      assert(MI && "macro definition with no macro info?");
      if (!DisableMacroExpansion) {
        if (!Identifier.isExpandDisabled() && MI->isEnabled()) {
          // C99 6.10.3p10: If the preprocessing token immediately after the
          // macro name isn't a '(', this macro should not be expanded.
          if (!MI->isFunctionLike() || isNextPPTokenLParen())
            return HandleMacroExpandedIdentifier(Identifier, MD);
        } else {
          // C99 6.10.3.4p2 says that a disabled macro may never again be
          // expanded, even if it's in a context where it could be expanded in the
          // future.
          Identifier.setFlag(Token::DisableExpand);
          if (MI->isObjectLike() || isNextPPTokenLParen())
            Diag(Identifier, diag::pp_disabled_macro_expansion);
        }
      }
    }
  
    // If this identifier is a keyword in a newer Standard or proposed Standard,
    // produce a warning. Don't warn if we're not considering macro expansion,
    // since this identifier might be the name of a macro.
    // FIXME: This warning is disabled in cases where it shouldn't be, like
    //   "#define constexpr constexpr", "int constexpr;"
    if (II.isFutureCompatKeyword() && !DisableMacroExpansion) {
      Diag(Identifier, getFutureCompatDiagKind(II, getLangOpts()))
          << II.getName();
      // Don't diagnose this keyword again in this translation unit.
      II.setIsFutureCompatKeyword(false);
    }
  
    // C++ 2.11p2: If this is an alternative representation of a C++ operator,
    // then we act as if it is the actual operator and not the textual
    // representation of it.
    if (II.isCPlusPlusOperatorKeyword())
      Identifier.setIdentifierInfo(nullptr);
  
    // If this is an extension token, diagnose its use.
    // We avoid diagnosing tokens that originate from macro definitions.
    // FIXME: This warning is disabled in cases where it shouldn't be,
    // like "#define TY typeof", "TY(1) x".
    if (II.isExtensionToken() && !DisableMacroExpansion)
      Diag(Identifier, diag::ext_token_used);
    
    // If this is the 'import' contextual keyword following an '@', note
    // that the next token indicates a module name.
    //
    // Note that we do not treat 'import' as a contextual
    // keyword when we're in a caching lexer, because caching lexers only get
    // used in contexts where import declarations are disallowed.
    if (LastTokenWasAt && II.isModulesImport() && !InMacroArgs && 
        !DisableMacroExpansion &&
        (getLangOpts().Modules || getLangOpts().DebuggerSupport) && 
        CurLexerKind != CLK_CachingLexer) {
      ModuleImportLoc = Identifier.getLocation();
      ModuleImportPath.clear();
      ModuleImportExpectsIdentifier = true;
      CurLexerKind = CLK_LexAfterModuleImport;
    }
    return true;
  }
  
  void Preprocessor::Lex(Token &Result) {
    // We loop here until a lex function retuns a token; this avoids recursion.
    bool ReturnedToken;
    do {
      switch (CurLexerKind) {
      case CLK_Lexer:
        ReturnedToken = CurLexer->Lex(Result);
        break;
      case CLK_PTHLexer:
        ReturnedToken = CurPTHLexer->Lex(Result);
        break;
      case CLK_TokenLexer:
        ReturnedToken = CurTokenLexer->Lex(Result);
        break;
      case CLK_CachingLexer:
        CachingLex(Result);
        ReturnedToken = true;
        break;
      case CLK_LexAfterModuleImport:
        LexAfterModuleImport(Result);
        ReturnedToken = true;
        break;
      }
    } while (!ReturnedToken);
  
    LastTokenWasAt = Result.is(tok::at);
  }
  
  
  /// \brief Lex a token following the 'import' contextual keyword.
  ///
  void Preprocessor::LexAfterModuleImport(Token &Result) {
    // Figure out what kind of lexer we actually have.
    recomputeCurLexerKind();
    
    // Lex the next token.
    Lex(Result);
  
    // The token sequence 
    //
    //   import identifier (. identifier)*
    //
    // indicates a module import directive. We already saw the 'import' 
    // contextual keyword, so now we're looking for the identifiers.
    if (ModuleImportExpectsIdentifier && Result.getKind() == tok::identifier) {
      // We expected to see an identifier here, and we did; continue handling
      // identifiers.
      ModuleImportPath.push_back(std::make_pair(Result.getIdentifierInfo(),
                                                Result.getLocation()));
      ModuleImportExpectsIdentifier = false;
      CurLexerKind = CLK_LexAfterModuleImport;
      return;
    }
    
    // If we're expecting a '.' or a ';', and we got a '.', then wait until we
    // see the next identifier.
    if (!ModuleImportExpectsIdentifier && Result.getKind() == tok::period) {
      ModuleImportExpectsIdentifier = true;
      CurLexerKind = CLK_LexAfterModuleImport;
      return;
    }
  
    // If we have a non-empty module path, load the named module.
    if (!ModuleImportPath.empty()) {
      Module *Imported = nullptr;
      if (getLangOpts().Modules) {
        Imported = TheModuleLoader.loadModule(ModuleImportLoc,
                                              ModuleImportPath,
                                              Module::Hidden,
                                              /*IsIncludeDirective=*/false);
        if (Imported)
          makeModuleVisible(Imported, ModuleImportLoc);
      }
      if (Callbacks && (getLangOpts().Modules || getLangOpts().DebuggerSupport))
        Callbacks->moduleImport(ModuleImportLoc, ModuleImportPath, Imported);
    }
  }
  
  void Preprocessor::makeModuleVisible(Module *M, SourceLocation Loc) {
    CurSubmoduleState->VisibleModules.setVisible(
        M, Loc, [](Module *) {},
        [&](ArrayRef<Module *> Path, Module *Conflict, StringRef Message) {
          // FIXME: Include the path in the diagnostic.
          // FIXME: Include the import location for the conflicting module.
          Diag(ModuleImportLoc, diag::warn_module_conflict)
              << Path[0]->getFullModuleName()
              << Conflict->getFullModuleName()
              << Message;
        });
  
    // Add this module to the imports list of the currently-built submodule.
    if (!BuildingSubmoduleStack.empty() && M != BuildingSubmoduleStack.back().M)
      BuildingSubmoduleStack.back().M->Imports.insert(M);
  }
  
  bool Preprocessor::FinishLexStringLiteral(Token &Result, std::string &String,
                                            const char *DiagnosticTag,
                                            bool AllowMacroExpansion) {
    // We need at least one string literal.
    if (Result.isNot(tok::string_literal)) {
      Diag(Result, diag::err_expected_string_literal)
        << /*Source='in...'*/0 << DiagnosticTag;
      return false;
    }
  
    // Lex string literal tokens, optionally with macro expansion.
    SmallVector<Token, 4> StrToks;
    do {
      StrToks.push_back(Result);
  
      if (Result.hasUDSuffix())
        Diag(Result, diag::err_invalid_string_udl);
  
      if (AllowMacroExpansion)
        Lex(Result);
      else
        LexUnexpandedToken(Result);
    } while (Result.is(tok::string_literal));
  
    // Concatenate and parse the strings.
    StringLiteralParser Literal(StrToks, *this);
    assert(Literal.isAscii() && "Didn't allow wide strings in");
  
    if (Literal.hadError)
      return false;
  
    if (Literal.Pascal) {
      Diag(StrToks[0].getLocation(), diag::err_expected_string_literal)
        << /*Source='in...'*/0 << DiagnosticTag;
      return false;
    }
  
    String = Literal.GetString();
    return true;
  }
  
  bool Preprocessor::parseSimpleIntegerLiteral(Token &Tok, uint64_t &Value) {
    assert(Tok.is(tok::numeric_constant));
    SmallString<8> IntegerBuffer;
    bool NumberInvalid = false;
    StringRef Spelling = getSpelling(Tok, IntegerBuffer, &NumberInvalid);
    if (NumberInvalid)
      return false;
    NumericLiteralParser Literal(Spelling, Tok.getLocation(), *this);
    if (Literal.hadError || !Literal.isIntegerLiteral() || Literal.hasUDSuffix())
      return false;
    llvm::APInt APVal(64, 0);
    if (Literal.GetIntegerValue(APVal))
      return false;
    Lex(Tok);
    Value = APVal.getLimitedValue();
    return true;
  }
  
  void Preprocessor::addCommentHandler(CommentHandler *Handler) {
    assert(Handler && "NULL comment handler");
    assert(std::find(CommentHandlers.begin(), CommentHandlers.end(), Handler) ==
           CommentHandlers.end() && "Comment handler already registered");
    CommentHandlers.push_back(Handler);
  }
  
  void Preprocessor::removeCommentHandler(CommentHandler *Handler) {
    std::vector<CommentHandler *>::iterator Pos
    = std::find(CommentHandlers.begin(), CommentHandlers.end(), Handler);
    assert(Pos != CommentHandlers.end() && "Comment handler not registered");
    CommentHandlers.erase(Pos);
  }
  
  bool Preprocessor::HandleComment(Token &result, SourceRange Comment) {
    bool AnyPendingTokens = false;
    for (std::vector<CommentHandler *>::iterator H = CommentHandlers.begin(),
         HEnd = CommentHandlers.end();
         H != HEnd; ++H) {
      if ((*H)->HandleComment(*this, Comment))
        AnyPendingTokens = true;
    }
    if (!AnyPendingTokens || getCommentRetentionState())
      return false;
    Lex(result);
    return true;
  }
  
  ModuleLoader::~ModuleLoader() { }
  
  CommentHandler::~CommentHandler() { }
  
  CodeCompletionHandler::~CodeCompletionHandler() { }
  
  void Preprocessor::createPreprocessingRecord() {
    if (Record)
      return;
    
    Record = new PreprocessingRecord(getSourceManager());
    addPPCallbacks(std::unique_ptr<PPCallbacks>(Record));
  }
  