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