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      1 //===--- PrintPreprocessedOutput.cpp - Implement the -E mode --------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This code simply runs the preprocessor on the input file and prints out the
     11 // result.  This is the traditional behavior of the -E option.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Frontend/Utils.h"
     16 #include "clang/Basic/Diagnostic.h"
     17 #include "clang/Basic/SourceManager.h"
     18 #include "clang/Frontend/PreprocessorOutputOptions.h"
     19 #include "clang/Lex/MacroInfo.h"
     20 #include "clang/Lex/PPCallbacks.h"
     21 #include "clang/Lex/Pragma.h"
     22 #include "clang/Lex/Preprocessor.h"
     23 #include "clang/Lex/TokenConcatenation.h"
     24 #include "llvm/ADT/SmallString.h"
     25 #include "llvm/ADT/STLExtras.h"
     26 #include "llvm/ADT/StringRef.h"
     27 #include "llvm/Config/config.h"
     28 #include "llvm/Support/raw_ostream.h"
     29 #include "llvm/Support/ErrorHandling.h"
     30 #include <cstdio>
     31 using namespace clang;
     32 
     33 /// PrintMacroDefinition - Print a macro definition in a form that will be
     34 /// properly accepted back as a definition.
     35 static void PrintMacroDefinition(const IdentifierInfo &II, const MacroInfo &MI,
     36                                  Preprocessor &PP, raw_ostream &OS) {
     37   OS << "#define " << II.getName();
     38 
     39   if (MI.isFunctionLike()) {
     40     OS << '(';
     41     if (!MI.arg_empty()) {
     42       MacroInfo::arg_iterator AI = MI.arg_begin(), E = MI.arg_end();
     43       for (; AI+1 != E; ++AI) {
     44         OS << (*AI)->getName();
     45         OS << ',';
     46       }
     47 
     48       // Last argument.
     49       if ((*AI)->getName() == "__VA_ARGS__")
     50         OS << "...";
     51       else
     52         OS << (*AI)->getName();
     53     }
     54 
     55     if (MI.isGNUVarargs())
     56       OS << "...";  // #define foo(x...)
     57 
     58     OS << ')';
     59   }
     60 
     61   // GCC always emits a space, even if the macro body is empty.  However, do not
     62   // want to emit two spaces if the first token has a leading space.
     63   if (MI.tokens_empty() || !MI.tokens_begin()->hasLeadingSpace())
     64     OS << ' ';
     65 
     66   llvm::SmallString<128> SpellingBuffer;
     67   for (MacroInfo::tokens_iterator I = MI.tokens_begin(), E = MI.tokens_end();
     68        I != E; ++I) {
     69     if (I->hasLeadingSpace())
     70       OS << ' ';
     71 
     72     OS << PP.getSpelling(*I, SpellingBuffer);
     73   }
     74 }
     75 
     76 //===----------------------------------------------------------------------===//
     77 // Preprocessed token printer
     78 //===----------------------------------------------------------------------===//
     79 
     80 namespace {
     81 class PrintPPOutputPPCallbacks : public PPCallbacks {
     82   Preprocessor &PP;
     83   SourceManager &SM;
     84   TokenConcatenation ConcatInfo;
     85 public:
     86   raw_ostream &OS;
     87 private:
     88   unsigned CurLine;
     89 
     90   bool EmittedTokensOnThisLine;
     91   bool EmittedMacroOnThisLine;
     92   SrcMgr::CharacteristicKind FileType;
     93   llvm::SmallString<512> CurFilename;
     94   bool Initialized;
     95   bool DisableLineMarkers;
     96   bool DumpDefines;
     97   bool UseLineDirective;
     98 public:
     99   PrintPPOutputPPCallbacks(Preprocessor &pp, raw_ostream &os,
    100                            bool lineMarkers, bool defines)
    101      : PP(pp), SM(PP.getSourceManager()),
    102        ConcatInfo(PP), OS(os), DisableLineMarkers(lineMarkers),
    103        DumpDefines(defines) {
    104     CurLine = 0;
    105     CurFilename += "<uninit>";
    106     EmittedTokensOnThisLine = false;
    107     EmittedMacroOnThisLine = false;
    108     FileType = SrcMgr::C_User;
    109     Initialized = false;
    110 
    111     // If we're in microsoft mode, use normal #line instead of line markers.
    112     UseLineDirective = PP.getLangOptions().MicrosoftExt;
    113   }
    114 
    115   void SetEmittedTokensOnThisLine() { EmittedTokensOnThisLine = true; }
    116   bool hasEmittedTokensOnThisLine() const { return EmittedTokensOnThisLine; }
    117 
    118   bool StartNewLineIfNeeded();
    119 
    120   virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
    121                            SrcMgr::CharacteristicKind FileType,
    122                            FileID PrevFID);
    123   virtual void Ident(SourceLocation Loc, const std::string &str);
    124   virtual void PragmaComment(SourceLocation Loc, const IdentifierInfo *Kind,
    125                              const std::string &Str);
    126   virtual void PragmaMessage(SourceLocation Loc, StringRef Str);
    127   virtual void PragmaDiagnosticPush(SourceLocation Loc,
    128                                     StringRef Namespace);
    129   virtual void PragmaDiagnosticPop(SourceLocation Loc,
    130                                    StringRef Namespace);
    131   virtual void PragmaDiagnostic(SourceLocation Loc, StringRef Namespace,
    132                                 diag::Mapping Map, StringRef Str);
    133 
    134   bool HandleFirstTokOnLine(Token &Tok);
    135   bool MoveToLine(SourceLocation Loc) {
    136     PresumedLoc PLoc = SM.getPresumedLoc(Loc);
    137     if (PLoc.isInvalid())
    138       return false;
    139     return MoveToLine(PLoc.getLine());
    140   }
    141   bool MoveToLine(unsigned LineNo);
    142 
    143   bool AvoidConcat(const Token &PrevPrevTok, const Token &PrevTok,
    144                    const Token &Tok) {
    145     return ConcatInfo.AvoidConcat(PrevPrevTok, PrevTok, Tok);
    146   }
    147   void WriteLineInfo(unsigned LineNo, const char *Extra=0, unsigned ExtraLen=0);
    148   bool LineMarkersAreDisabled() const { return DisableLineMarkers; }
    149   void HandleNewlinesInToken(const char *TokStr, unsigned Len);
    150 
    151   /// MacroDefined - This hook is called whenever a macro definition is seen.
    152   void MacroDefined(const Token &MacroNameTok, const MacroInfo *MI);
    153 
    154   /// MacroUndefined - This hook is called whenever a macro #undef is seen.
    155   void MacroUndefined(const Token &MacroNameTok, const MacroInfo *MI);
    156 };
    157 }  // end anonymous namespace
    158 
    159 void PrintPPOutputPPCallbacks::WriteLineInfo(unsigned LineNo,
    160                                              const char *Extra,
    161                                              unsigned ExtraLen) {
    162   if (EmittedTokensOnThisLine || EmittedMacroOnThisLine) {
    163     OS << '\n';
    164     EmittedTokensOnThisLine = false;
    165     EmittedMacroOnThisLine = false;
    166   }
    167 
    168   // Emit #line directives or GNU line markers depending on what mode we're in.
    169   if (UseLineDirective) {
    170     OS << "#line" << ' ' << LineNo << ' ' << '"';
    171     OS.write(CurFilename.data(), CurFilename.size());
    172     OS << '"';
    173   } else {
    174     OS << '#' << ' ' << LineNo << ' ' << '"';
    175     OS.write(CurFilename.data(), CurFilename.size());
    176     OS << '"';
    177 
    178     if (ExtraLen)
    179       OS.write(Extra, ExtraLen);
    180 
    181     if (FileType == SrcMgr::C_System)
    182       OS.write(" 3", 2);
    183     else if (FileType == SrcMgr::C_ExternCSystem)
    184       OS.write(" 3 4", 4);
    185   }
    186   OS << '\n';
    187 }
    188 
    189 /// MoveToLine - Move the output to the source line specified by the location
    190 /// object.  We can do this by emitting some number of \n's, or be emitting a
    191 /// #line directive.  This returns false if already at the specified line, true
    192 /// if some newlines were emitted.
    193 bool PrintPPOutputPPCallbacks::MoveToLine(unsigned LineNo) {
    194   // If this line is "close enough" to the original line, just print newlines,
    195   // otherwise print a #line directive.
    196   if (LineNo-CurLine <= 8) {
    197     if (LineNo-CurLine == 1)
    198       OS << '\n';
    199     else if (LineNo == CurLine)
    200       return false;    // Spelling line moved, but expansion line didn't.
    201     else {
    202       const char *NewLines = "\n\n\n\n\n\n\n\n";
    203       OS.write(NewLines, LineNo-CurLine);
    204     }
    205   } else if (!DisableLineMarkers) {
    206     // Emit a #line or line marker.
    207     WriteLineInfo(LineNo, 0, 0);
    208   } else {
    209     // Okay, we're in -P mode, which turns off line markers.  However, we still
    210     // need to emit a newline between tokens on different lines.
    211     if (EmittedTokensOnThisLine || EmittedMacroOnThisLine) {
    212       OS << '\n';
    213       EmittedTokensOnThisLine = false;
    214       EmittedMacroOnThisLine = false;
    215     }
    216   }
    217 
    218   CurLine = LineNo;
    219   return true;
    220 }
    221 
    222 bool PrintPPOutputPPCallbacks::StartNewLineIfNeeded() {
    223   if (EmittedTokensOnThisLine || EmittedMacroOnThisLine) {
    224     OS << '\n';
    225     EmittedTokensOnThisLine = false;
    226     EmittedMacroOnThisLine = false;
    227     ++CurLine;
    228     return true;
    229   }
    230 
    231   return false;
    232 }
    233 
    234 /// FileChanged - Whenever the preprocessor enters or exits a #include file
    235 /// it invokes this handler.  Update our conception of the current source
    236 /// position.
    237 void PrintPPOutputPPCallbacks::FileChanged(SourceLocation Loc,
    238                                            FileChangeReason Reason,
    239                                        SrcMgr::CharacteristicKind NewFileType,
    240                                        FileID PrevFID) {
    241   // Unless we are exiting a #include, make sure to skip ahead to the line the
    242   // #include directive was at.
    243   SourceManager &SourceMgr = SM;
    244 
    245   PresumedLoc UserLoc = SourceMgr.getPresumedLoc(Loc);
    246   if (UserLoc.isInvalid())
    247     return;
    248 
    249   unsigned NewLine = UserLoc.getLine();
    250 
    251   if (Reason == PPCallbacks::EnterFile) {
    252     SourceLocation IncludeLoc = UserLoc.getIncludeLoc();
    253     if (IncludeLoc.isValid())
    254       MoveToLine(IncludeLoc);
    255   } else if (Reason == PPCallbacks::SystemHeaderPragma) {
    256     MoveToLine(NewLine);
    257 
    258     // TODO GCC emits the # directive for this directive on the line AFTER the
    259     // directive and emits a bunch of spaces that aren't needed.  Emulate this
    260     // strange behavior.
    261   }
    262 
    263   CurLine = NewLine;
    264 
    265   CurFilename.clear();
    266   CurFilename += UserLoc.getFilename();
    267   Lexer::Stringify(CurFilename);
    268   FileType = NewFileType;
    269 
    270   if (DisableLineMarkers) return;
    271 
    272   if (!Initialized) {
    273     WriteLineInfo(CurLine);
    274     Initialized = true;
    275   }
    276 
    277   switch (Reason) {
    278   case PPCallbacks::EnterFile:
    279     WriteLineInfo(CurLine, " 1", 2);
    280     break;
    281   case PPCallbacks::ExitFile:
    282     WriteLineInfo(CurLine, " 2", 2);
    283     break;
    284   case PPCallbacks::SystemHeaderPragma:
    285   case PPCallbacks::RenameFile:
    286     WriteLineInfo(CurLine);
    287     break;
    288   }
    289 }
    290 
    291 /// Ident - Handle #ident directives when read by the preprocessor.
    292 ///
    293 void PrintPPOutputPPCallbacks::Ident(SourceLocation Loc, const std::string &S) {
    294   MoveToLine(Loc);
    295 
    296   OS.write("#ident ", strlen("#ident "));
    297   OS.write(&S[0], S.size());
    298   EmittedTokensOnThisLine = true;
    299 }
    300 
    301 /// MacroDefined - This hook is called whenever a macro definition is seen.
    302 void PrintPPOutputPPCallbacks::MacroDefined(const Token &MacroNameTok,
    303                                             const MacroInfo *MI) {
    304   // Only print out macro definitions in -dD mode.
    305   if (!DumpDefines ||
    306       // Ignore __FILE__ etc.
    307       MI->isBuiltinMacro()) return;
    308 
    309   MoveToLine(MI->getDefinitionLoc());
    310   PrintMacroDefinition(*MacroNameTok.getIdentifierInfo(), *MI, PP, OS);
    311   EmittedMacroOnThisLine = true;
    312 }
    313 
    314 void PrintPPOutputPPCallbacks::MacroUndefined(const Token &MacroNameTok,
    315                                               const MacroInfo *MI) {
    316   // Only print out macro definitions in -dD mode.
    317   if (!DumpDefines) return;
    318 
    319   MoveToLine(MacroNameTok.getLocation());
    320   OS << "#undef " << MacroNameTok.getIdentifierInfo()->getName();
    321   EmittedMacroOnThisLine = true;
    322 }
    323 
    324 void PrintPPOutputPPCallbacks::PragmaComment(SourceLocation Loc,
    325                                              const IdentifierInfo *Kind,
    326                                              const std::string &Str) {
    327   MoveToLine(Loc);
    328   OS << "#pragma comment(" << Kind->getName();
    329 
    330   if (!Str.empty()) {
    331     OS << ", \"";
    332 
    333     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
    334       unsigned char Char = Str[i];
    335       if (isprint(Char) && Char != '\\' && Char != '"')
    336         OS << (char)Char;
    337       else  // Output anything hard as an octal escape.
    338         OS << '\\'
    339            << (char)('0'+ ((Char >> 6) & 7))
    340            << (char)('0'+ ((Char >> 3) & 7))
    341            << (char)('0'+ ((Char >> 0) & 7));
    342     }
    343     OS << '"';
    344   }
    345 
    346   OS << ')';
    347   EmittedTokensOnThisLine = true;
    348 }
    349 
    350 void PrintPPOutputPPCallbacks::PragmaMessage(SourceLocation Loc,
    351                                              StringRef Str) {
    352   MoveToLine(Loc);
    353   OS << "#pragma message(";
    354 
    355   OS << '"';
    356 
    357   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
    358     unsigned char Char = Str[i];
    359     if (isprint(Char) && Char != '\\' && Char != '"')
    360       OS << (char)Char;
    361     else  // Output anything hard as an octal escape.
    362       OS << '\\'
    363          << (char)('0'+ ((Char >> 6) & 7))
    364          << (char)('0'+ ((Char >> 3) & 7))
    365          << (char)('0'+ ((Char >> 0) & 7));
    366   }
    367   OS << '"';
    368 
    369   OS << ')';
    370   EmittedTokensOnThisLine = true;
    371 }
    372 
    373 void PrintPPOutputPPCallbacks::
    374 PragmaDiagnosticPush(SourceLocation Loc, StringRef Namespace) {
    375   MoveToLine(Loc);
    376   OS << "#pragma " << Namespace << " diagnostic push";
    377   EmittedTokensOnThisLine = true;
    378 }
    379 
    380 void PrintPPOutputPPCallbacks::
    381 PragmaDiagnosticPop(SourceLocation Loc, StringRef Namespace) {
    382   MoveToLine(Loc);
    383   OS << "#pragma " << Namespace << " diagnostic pop";
    384   EmittedTokensOnThisLine = true;
    385 }
    386 
    387 void PrintPPOutputPPCallbacks::
    388 PragmaDiagnostic(SourceLocation Loc, StringRef Namespace,
    389                  diag::Mapping Map, StringRef Str) {
    390   MoveToLine(Loc);
    391   OS << "#pragma " << Namespace << " diagnostic ";
    392   switch (Map) {
    393   default: llvm_unreachable("unexpected diagnostic kind");
    394   case diag::MAP_WARNING:
    395     OS << "warning";
    396     break;
    397   case diag::MAP_ERROR:
    398     OS << "error";
    399     break;
    400   case diag::MAP_IGNORE:
    401     OS << "ignored";
    402     break;
    403   case diag::MAP_FATAL:
    404     OS << "fatal";
    405     break;
    406   }
    407   OS << " \"" << Str << '"';
    408   EmittedTokensOnThisLine = true;
    409 }
    410 
    411 /// HandleFirstTokOnLine - When emitting a preprocessed file in -E mode, this
    412 /// is called for the first token on each new line.  If this really is the start
    413 /// of a new logical line, handle it and return true, otherwise return false.
    414 /// This may not be the start of a logical line because the "start of line"
    415 /// marker is set for spelling lines, not expansion ones.
    416 bool PrintPPOutputPPCallbacks::HandleFirstTokOnLine(Token &Tok) {
    417   // Figure out what line we went to and insert the appropriate number of
    418   // newline characters.
    419   if (!MoveToLine(Tok.getLocation()))
    420     return false;
    421 
    422   // Print out space characters so that the first token on a line is
    423   // indented for easy reading.
    424   unsigned ColNo = SM.getExpansionColumnNumber(Tok.getLocation());
    425 
    426   // This hack prevents stuff like:
    427   // #define HASH #
    428   // HASH define foo bar
    429   // From having the # character end up at column 1, which makes it so it
    430   // is not handled as a #define next time through the preprocessor if in
    431   // -fpreprocessed mode.
    432   if (ColNo <= 1 && Tok.is(tok::hash))
    433     OS << ' ';
    434 
    435   // Otherwise, indent the appropriate number of spaces.
    436   for (; ColNo > 1; --ColNo)
    437     OS << ' ';
    438 
    439   return true;
    440 }
    441 
    442 void PrintPPOutputPPCallbacks::HandleNewlinesInToken(const char *TokStr,
    443                                                      unsigned Len) {
    444   unsigned NumNewlines = 0;
    445   for (; Len; --Len, ++TokStr) {
    446     if (*TokStr != '\n' &&
    447         *TokStr != '\r')
    448       continue;
    449 
    450     ++NumNewlines;
    451 
    452     // If we have \n\r or \r\n, skip both and count as one line.
    453     if (Len != 1 &&
    454         (TokStr[1] == '\n' || TokStr[1] == '\r') &&
    455         TokStr[0] != TokStr[1])
    456       ++TokStr, --Len;
    457   }
    458 
    459   if (NumNewlines == 0) return;
    460 
    461   CurLine += NumNewlines;
    462 }
    463 
    464 
    465 namespace {
    466 struct UnknownPragmaHandler : public PragmaHandler {
    467   const char *Prefix;
    468   PrintPPOutputPPCallbacks *Callbacks;
    469 
    470   UnknownPragmaHandler(const char *prefix, PrintPPOutputPPCallbacks *callbacks)
    471     : Prefix(prefix), Callbacks(callbacks) {}
    472   virtual void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
    473                             Token &PragmaTok) {
    474     // Figure out what line we went to and insert the appropriate number of
    475     // newline characters.
    476     Callbacks->StartNewLineIfNeeded();
    477     Callbacks->MoveToLine(PragmaTok.getLocation());
    478     Callbacks->OS.write(Prefix, strlen(Prefix));
    479     Callbacks->SetEmittedTokensOnThisLine();
    480     // Read and print all of the pragma tokens.
    481     while (PragmaTok.isNot(tok::eod)) {
    482       if (PragmaTok.hasLeadingSpace())
    483         Callbacks->OS << ' ';
    484       std::string TokSpell = PP.getSpelling(PragmaTok);
    485       Callbacks->OS.write(&TokSpell[0], TokSpell.size());
    486       PP.LexUnexpandedToken(PragmaTok);
    487     }
    488     Callbacks->StartNewLineIfNeeded();
    489   }
    490 };
    491 } // end anonymous namespace
    492 
    493 
    494 static void PrintPreprocessedTokens(Preprocessor &PP, Token &Tok,
    495                                     PrintPPOutputPPCallbacks *Callbacks,
    496                                     raw_ostream &OS) {
    497   char Buffer[256];
    498   Token PrevPrevTok, PrevTok;
    499   PrevPrevTok.startToken();
    500   PrevTok.startToken();
    501   while (1) {
    502 
    503     // If this token is at the start of a line, emit newlines if needed.
    504     if (Tok.isAtStartOfLine() && Callbacks->HandleFirstTokOnLine(Tok)) {
    505       // done.
    506     } else if (Tok.hasLeadingSpace() ||
    507                // If we haven't emitted a token on this line yet, PrevTok isn't
    508                // useful to look at and no concatenation could happen anyway.
    509                (Callbacks->hasEmittedTokensOnThisLine() &&
    510                 // Don't print "-" next to "-", it would form "--".
    511                 Callbacks->AvoidConcat(PrevPrevTok, PrevTok, Tok))) {
    512       OS << ' ';
    513     }
    514 
    515     if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
    516       OS << II->getName();
    517     } else if (Tok.isLiteral() && !Tok.needsCleaning() &&
    518                Tok.getLiteralData()) {
    519       OS.write(Tok.getLiteralData(), Tok.getLength());
    520     } else if (Tok.getLength() < 256) {
    521       const char *TokPtr = Buffer;
    522       unsigned Len = PP.getSpelling(Tok, TokPtr);
    523       OS.write(TokPtr, Len);
    524 
    525       // Tokens that can contain embedded newlines need to adjust our current
    526       // line number.
    527       if (Tok.getKind() == tok::comment)
    528         Callbacks->HandleNewlinesInToken(TokPtr, Len);
    529     } else {
    530       std::string S = PP.getSpelling(Tok);
    531       OS.write(&S[0], S.size());
    532 
    533       // Tokens that can contain embedded newlines need to adjust our current
    534       // line number.
    535       if (Tok.getKind() == tok::comment)
    536         Callbacks->HandleNewlinesInToken(&S[0], S.size());
    537     }
    538     Callbacks->SetEmittedTokensOnThisLine();
    539 
    540     if (Tok.is(tok::eof)) break;
    541 
    542     PrevPrevTok = PrevTok;
    543     PrevTok = Tok;
    544     PP.Lex(Tok);
    545   }
    546 }
    547 
    548 typedef std::pair<IdentifierInfo*, MacroInfo*> id_macro_pair;
    549 static int MacroIDCompare(const void* a, const void* b) {
    550   const id_macro_pair *LHS = static_cast<const id_macro_pair*>(a);
    551   const id_macro_pair *RHS = static_cast<const id_macro_pair*>(b);
    552   return LHS->first->getName().compare(RHS->first->getName());
    553 }
    554 
    555 static void DoPrintMacros(Preprocessor &PP, raw_ostream *OS) {
    556   // Ignore unknown pragmas.
    557   PP.AddPragmaHandler(new EmptyPragmaHandler());
    558 
    559   // -dM mode just scans and ignores all tokens in the files, then dumps out
    560   // the macro table at the end.
    561   PP.EnterMainSourceFile();
    562 
    563   Token Tok;
    564   do PP.Lex(Tok);
    565   while (Tok.isNot(tok::eof));
    566 
    567   SmallVector<id_macro_pair, 128>
    568     MacrosByID(PP.macro_begin(), PP.macro_end());
    569   llvm::array_pod_sort(MacrosByID.begin(), MacrosByID.end(), MacroIDCompare);
    570 
    571   for (unsigned i = 0, e = MacrosByID.size(); i != e; ++i) {
    572     MacroInfo &MI = *MacrosByID[i].second;
    573     // Ignore computed macros like __LINE__ and friends.
    574     if (MI.isBuiltinMacro()) continue;
    575 
    576     PrintMacroDefinition(*MacrosByID[i].first, MI, PP, *OS);
    577     *OS << '\n';
    578   }
    579 }
    580 
    581 /// DoPrintPreprocessedInput - This implements -E mode.
    582 ///
    583 void clang::DoPrintPreprocessedInput(Preprocessor &PP, raw_ostream *OS,
    584                                      const PreprocessorOutputOptions &Opts) {
    585   // Show macros with no output is handled specially.
    586   if (!Opts.ShowCPP) {
    587     assert(Opts.ShowMacros && "Not yet implemented!");
    588     DoPrintMacros(PP, OS);
    589     return;
    590   }
    591 
    592   // Inform the preprocessor whether we want it to retain comments or not, due
    593   // to -C or -CC.
    594   PP.SetCommentRetentionState(Opts.ShowComments, Opts.ShowMacroComments);
    595 
    596   PrintPPOutputPPCallbacks *Callbacks =
    597       new PrintPPOutputPPCallbacks(PP, *OS, !Opts.ShowLineMarkers,
    598                                    Opts.ShowMacros);
    599   PP.AddPragmaHandler(new UnknownPragmaHandler("#pragma", Callbacks));
    600   PP.AddPragmaHandler("GCC", new UnknownPragmaHandler("#pragma GCC",Callbacks));
    601   PP.AddPragmaHandler("clang",
    602                       new UnknownPragmaHandler("#pragma clang", Callbacks));
    603 
    604   PP.addPPCallbacks(Callbacks);
    605 
    606   // After we have configured the preprocessor, enter the main file.
    607   PP.EnterMainSourceFile();
    608 
    609   // Consume all of the tokens that come from the predefines buffer.  Those
    610   // should not be emitted into the output and are guaranteed to be at the
    611   // start.
    612   const SourceManager &SourceMgr = PP.getSourceManager();
    613   Token Tok;
    614   do {
    615     PP.Lex(Tok);
    616     if (Tok.is(tok::eof) || !Tok.getLocation().isFileID())
    617       break;
    618 
    619     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
    620     if (PLoc.isInvalid())
    621       break;
    622 
    623     if (strcmp(PLoc.getFilename(), "<built-in>"))
    624       break;
    625   } while (true);
    626 
    627   // Read all the preprocessed tokens, printing them out to the stream.
    628   PrintPreprocessedTokens(PP, Tok, Callbacks, *OS);
    629   *OS << '\n';
    630 }
    631