PrintPreprocessedOutput.cpp revision 2a9be3e5b0c390f9189bb3dec2b2b6ba884f60cc 
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 <cctype>
30#include <cstdio>
31using namespace clang;
32
33/// PrintMacroDefinition - Print a macro definition in a form that will be
34/// properly accepted back as a definition.
35static 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  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
80namespace {
81class PrintPPOutputPPCallbacks : public PPCallbacks {
82  Preprocessor &PP;
83  SourceManager &SM;
84  TokenConcatenation ConcatInfo;
85public:
86  raw_ostream &OS;
87private:
88  unsigned CurLine;
89
90  bool EmittedTokensOnThisLine;
91  bool EmittedDirectiveOnThisLine;
92  SrcMgr::CharacteristicKind FileType;
93  SmallString<512> CurFilename;
94  bool Initialized;
95  bool DisableLineMarkers;
96  bool DumpDefines;
97  bool UseLineDirective;
98  bool IsFirstFileEntered;
99public:
100  PrintPPOutputPPCallbacks(Preprocessor &pp, raw_ostream &os,
101                           bool lineMarkers, bool defines)
102     : PP(pp), SM(PP.getSourceManager()),
103       ConcatInfo(PP), OS(os), DisableLineMarkers(lineMarkers),
104       DumpDefines(defines) {
105    CurLine = 0;
106    CurFilename += "<uninit>";
107    EmittedTokensOnThisLine = false;
108    EmittedDirectiveOnThisLine = false;
109    FileType = SrcMgr::C_User;
110    Initialized = false;
111    IsFirstFileEntered = false;
112
113    // If we're in microsoft mode, use normal #line instead of line markers.
114    UseLineDirective = PP.getLangOpts().MicrosoftExt;
115  }
116
117  void setEmittedTokensOnThisLine() { EmittedTokensOnThisLine = true; }
118  bool hasEmittedTokensOnThisLine() const { return EmittedTokensOnThisLine; }
119
120  void setEmittedDirectiveOnThisLine() { EmittedDirectiveOnThisLine = true; }
121  bool hasEmittedDirectiveOnThisLine() const {
122    return EmittedDirectiveOnThisLine;
123  }
124
125  bool startNewLineIfNeeded(bool ShouldUpdateCurrentLine = true);
126
127  virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
128                           SrcMgr::CharacteristicKind FileType,
129                           FileID PrevFID);
130  virtual void Ident(SourceLocation Loc, const std::string &str);
131  virtual void PragmaComment(SourceLocation Loc, const IdentifierInfo *Kind,
132                             const std::string &Str);
133  virtual void PragmaMessage(SourceLocation Loc, StringRef Str);
134  virtual void PragmaDiagnosticPush(SourceLocation Loc,
135                                    StringRef Namespace);
136  virtual void PragmaDiagnosticPop(SourceLocation Loc,
137                                   StringRef Namespace);
138  virtual void PragmaDiagnostic(SourceLocation Loc, StringRef Namespace,
139                                diag::Mapping Map, StringRef Str);
140
141  bool HandleFirstTokOnLine(Token &Tok);
142  bool MoveToLine(SourceLocation Loc) {
143    PresumedLoc PLoc = SM.getPresumedLoc(Loc);
144    if (PLoc.isInvalid())
145      return false;
146    return MoveToLine(PLoc.getLine());
147  }
148  bool MoveToLine(unsigned LineNo);
149
150  bool AvoidConcat(const Token &PrevPrevTok, const Token &PrevTok,
151                   const Token &Tok) {
152    return ConcatInfo.AvoidConcat(PrevPrevTok, PrevTok, Tok);
153  }
154  void WriteLineInfo(unsigned LineNo, const char *Extra=0, unsigned ExtraLen=0);
155  bool LineMarkersAreDisabled() const { return DisableLineMarkers; }
156  void HandleNewlinesInToken(const char *TokStr, unsigned Len);
157
158  /// MacroDefined - This hook is called whenever a macro definition is seen.
159  void MacroDefined(const Token &MacroNameTok, const MacroInfo *MI);
160
161  /// MacroUndefined - This hook is called whenever a macro #undef is seen.
162  void MacroUndefined(const Token &MacroNameTok, const MacroInfo *MI);
163};
164}  // end anonymous namespace
165
166void PrintPPOutputPPCallbacks::WriteLineInfo(unsigned LineNo,
167                                             const char *Extra,
168                                             unsigned ExtraLen) {
169  startNewLineIfNeeded(/*ShouldUpdateCurrentLine=*/false);
170
171  // Emit #line directives or GNU line markers depending on what mode we're in.
172  if (UseLineDirective) {
173    OS << "#line" << ' ' << LineNo << ' ' << '"';
174    OS.write(CurFilename.data(), CurFilename.size());
175    OS << '"';
176  } else {
177    OS << '#' << ' ' << LineNo << ' ' << '"';
178    OS.write(CurFilename.data(), CurFilename.size());
179    OS << '"';
180
181    if (ExtraLen)
182      OS.write(Extra, ExtraLen);
183
184    if (FileType == SrcMgr::C_System)
185      OS.write(" 3", 2);
186    else if (FileType == SrcMgr::C_ExternCSystem)
187      OS.write(" 3 4", 4);
188  }
189  OS << '\n';
190}
191
192/// MoveToLine - Move the output to the source line specified by the location
193/// object.  We can do this by emitting some number of \n's, or be emitting a
194/// #line directive.  This returns false if already at the specified line, true
195/// if some newlines were emitted.
196bool PrintPPOutputPPCallbacks::MoveToLine(unsigned LineNo) {
197  // If this line is "close enough" to the original line, just print newlines,
198  // otherwise print a #line directive.
199  if (LineNo-CurLine <= 8) {
200    if (LineNo-CurLine == 1)
201      OS << '\n';
202    else if (LineNo == CurLine)
203      return false;    // Spelling line moved, but expansion line didn't.
204    else {
205      const char *NewLines = "\n\n\n\n\n\n\n\n";
206      OS.write(NewLines, LineNo-CurLine);
207    }
208  } else if (!DisableLineMarkers) {
209    // Emit a #line or line marker.
210    WriteLineInfo(LineNo, 0, 0);
211  } else {
212    // Okay, we're in -P mode, which turns off line markers.  However, we still
213    // need to emit a newline between tokens on different lines.
214    startNewLineIfNeeded(/*ShouldUpdateCurrentLine=*/false);
215  }
216
217  CurLine = LineNo;
218  return true;
219}
220
221bool
222PrintPPOutputPPCallbacks::startNewLineIfNeeded(bool ShouldUpdateCurrentLine) {
223  if (EmittedTokensOnThisLine || EmittedDirectiveOnThisLine) {
224    OS << '\n';
225    EmittedTokensOnThisLine = false;
226    EmittedDirectiveOnThisLine = false;
227    if (ShouldUpdateCurrentLine)
228      ++CurLine;
229    return true;
230  }
231
232  return false;
233}
234
235/// FileChanged - Whenever the preprocessor enters or exits a #include file
236/// it invokes this handler.  Update our conception of the current source
237/// position.
238void PrintPPOutputPPCallbacks::FileChanged(SourceLocation Loc,
239                                           FileChangeReason Reason,
240                                       SrcMgr::CharacteristicKind NewFileType,
241                                       FileID PrevFID) {
242  // Unless we are exiting a #include, make sure to skip ahead to the line the
243  // #include directive was at.
244  SourceManager &SourceMgr = SM;
245
246  PresumedLoc UserLoc = SourceMgr.getPresumedLoc(Loc);
247  if (UserLoc.isInvalid())
248    return;
249
250  unsigned NewLine = UserLoc.getLine();
251
252  if (Reason == PPCallbacks::EnterFile) {
253    SourceLocation IncludeLoc = UserLoc.getIncludeLoc();
254    if (IncludeLoc.isValid())
255      MoveToLine(IncludeLoc);
256  } else if (Reason == PPCallbacks::SystemHeaderPragma) {
257    MoveToLine(NewLine);
258
259    // TODO GCC emits the # directive for this directive on the line AFTER the
260    // directive and emits a bunch of spaces that aren't needed.  Emulate this
261    // strange behavior.
262  }
263
264  CurLine = NewLine;
265
266  CurFilename.clear();
267  CurFilename += UserLoc.getFilename();
268  Lexer::Stringify(CurFilename);
269  FileType = NewFileType;
270
271  if (DisableLineMarkers) return;
272
273  if (!Initialized) {
274    WriteLineInfo(CurLine);
275    Initialized = true;
276  }
277
278  // Do not emit an enter marker for the main file (which we expect is the first
279  // entered file). This matches gcc, and improves compatibility with some tools
280  // which track the # line markers as a way to determine when the preprocessed
281  // output is in the context of the main file.
282  if (Reason == PPCallbacks::EnterFile && !IsFirstFileEntered) {
283    IsFirstFileEntered = true;
284    return;
285  }
286
287  switch (Reason) {
288  case PPCallbacks::EnterFile:
289    WriteLineInfo(CurLine, " 1", 2);
290    break;
291  case PPCallbacks::ExitFile:
292    WriteLineInfo(CurLine, " 2", 2);
293    break;
294  case PPCallbacks::SystemHeaderPragma:
295  case PPCallbacks::RenameFile:
296    WriteLineInfo(CurLine);
297    break;
298  }
299}
300
301/// Ident - Handle #ident directives when read by the preprocessor.
302///
303void PrintPPOutputPPCallbacks::Ident(SourceLocation Loc, const std::string &S) {
304  MoveToLine(Loc);
305
306  OS.write("#ident ", strlen("#ident "));
307  OS.write(&S[0], S.size());
308  EmittedTokensOnThisLine = true;
309}
310
311/// MacroDefined - This hook is called whenever a macro definition is seen.
312void PrintPPOutputPPCallbacks::MacroDefined(const Token &MacroNameTok,
313                                            const MacroInfo *MI) {
314  // Only print out macro definitions in -dD mode.
315  if (!DumpDefines ||
316      // Ignore __FILE__ etc.
317      MI->isBuiltinMacro()) return;
318
319  MoveToLine(MI->getDefinitionLoc());
320  PrintMacroDefinition(*MacroNameTok.getIdentifierInfo(), *MI, PP, OS);
321  setEmittedDirectiveOnThisLine();
322}
323
324void PrintPPOutputPPCallbacks::MacroUndefined(const Token &MacroNameTok,
325                                              const MacroInfo *MI) {
326  // Only print out macro definitions in -dD mode.
327  if (!DumpDefines) return;
328
329  MoveToLine(MacroNameTok.getLocation());
330  OS << "#undef " << MacroNameTok.getIdentifierInfo()->getName();
331  setEmittedDirectiveOnThisLine();
332}
333
334void PrintPPOutputPPCallbacks::PragmaComment(SourceLocation Loc,
335                                             const IdentifierInfo *Kind,
336                                             const std::string &Str) {
337  startNewLineIfNeeded();
338  MoveToLine(Loc);
339  OS << "#pragma comment(" << Kind->getName();
340
341  if (!Str.empty()) {
342    OS << ", \"";
343
344    for (unsigned i = 0, e = Str.size(); i != e; ++i) {
345      unsigned char Char = Str[i];
346      if (isprint(Char) && Char != '\\' && Char != '"')
347        OS << (char)Char;
348      else  // Output anything hard as an octal escape.
349        OS << '\\'
350           << (char)('0'+ ((Char >> 6) & 7))
351           << (char)('0'+ ((Char >> 3) & 7))
352           << (char)('0'+ ((Char >> 0) & 7));
353    }
354    OS << '"';
355  }
356
357  OS << ')';
358  setEmittedDirectiveOnThisLine();
359}
360
361void PrintPPOutputPPCallbacks::PragmaMessage(SourceLocation Loc,
362                                             StringRef Str) {
363  startNewLineIfNeeded();
364  MoveToLine(Loc);
365  OS << "#pragma message(";
366
367  OS << '"';
368
369  for (unsigned i = 0, e = Str.size(); i != e; ++i) {
370    unsigned char Char = Str[i];
371    if (isprint(Char) && Char != '\\' && Char != '"')
372      OS << (char)Char;
373    else  // Output anything hard as an octal escape.
374      OS << '\\'
375         << (char)('0'+ ((Char >> 6) & 7))
376         << (char)('0'+ ((Char >> 3) & 7))
377         << (char)('0'+ ((Char >> 0) & 7));
378  }
379  OS << '"';
380
381  OS << ')';
382  setEmittedDirectiveOnThisLine();
383}
384
385void PrintPPOutputPPCallbacks::
386PragmaDiagnosticPush(SourceLocation Loc, StringRef Namespace) {
387  startNewLineIfNeeded();
388  MoveToLine(Loc);
389  OS << "#pragma " << Namespace << " diagnostic push";
390  setEmittedDirectiveOnThisLine();
391}
392
393void PrintPPOutputPPCallbacks::
394PragmaDiagnosticPop(SourceLocation Loc, StringRef Namespace) {
395  startNewLineIfNeeded();
396  MoveToLine(Loc);
397  OS << "#pragma " << Namespace << " diagnostic pop";
398  setEmittedDirectiveOnThisLine();
399}
400
401void PrintPPOutputPPCallbacks::
402PragmaDiagnostic(SourceLocation Loc, StringRef Namespace,
403                 diag::Mapping Map, StringRef Str) {
404  startNewLineIfNeeded();
405  MoveToLine(Loc);
406  OS << "#pragma " << Namespace << " diagnostic ";
407  switch (Map) {
408  case diag::MAP_WARNING:
409    OS << "warning";
410    break;
411  case diag::MAP_ERROR:
412    OS << "error";
413    break;
414  case diag::MAP_IGNORE:
415    OS << "ignored";
416    break;
417  case diag::MAP_FATAL:
418    OS << "fatal";
419    break;
420  }
421  OS << " \"" << Str << '"';
422  setEmittedDirectiveOnThisLine();
423}
424
425/// HandleFirstTokOnLine - When emitting a preprocessed file in -E mode, this
426/// is called for the first token on each new line.  If this really is the start
427/// of a new logical line, handle it and return true, otherwise return false.
428/// This may not be the start of a logical line because the "start of line"
429/// marker is set for spelling lines, not expansion ones.
430bool PrintPPOutputPPCallbacks::HandleFirstTokOnLine(Token &Tok) {
431  // Figure out what line we went to and insert the appropriate number of
432  // newline characters.
433  if (!MoveToLine(Tok.getLocation()))
434    return false;
435
436  // Print out space characters so that the first token on a line is
437  // indented for easy reading.
438  unsigned ColNo = SM.getExpansionColumnNumber(Tok.getLocation());
439
440  // This hack prevents stuff like:
441  // #define HASH #
442  // HASH define foo bar
443  // From having the # character end up at column 1, which makes it so it
444  // is not handled as a #define next time through the preprocessor if in
445  // -fpreprocessed mode.
446  if (ColNo <= 1 && Tok.is(tok::hash))
447    OS << ' ';
448
449  // Otherwise, indent the appropriate number of spaces.
450  for (; ColNo > 1; --ColNo)
451    OS << ' ';
452
453  return true;
454}
455
456void PrintPPOutputPPCallbacks::HandleNewlinesInToken(const char *TokStr,
457                                                     unsigned Len) {
458  unsigned NumNewlines = 0;
459  for (; Len; --Len, ++TokStr) {
460    if (*TokStr != '\n' &&
461        *TokStr != '\r')
462      continue;
463
464    ++NumNewlines;
465
466    // If we have \n\r or \r\n, skip both and count as one line.
467    if (Len != 1 &&
468        (TokStr[1] == '\n' || TokStr[1] == '\r') &&
469        TokStr[0] != TokStr[1])
470      ++TokStr, --Len;
471  }
472
473  if (NumNewlines == 0) return;
474
475  CurLine += NumNewlines;
476}
477
478
479namespace {
480struct UnknownPragmaHandler : public PragmaHandler {
481  const char *Prefix;
482  PrintPPOutputPPCallbacks *Callbacks;
483
484  UnknownPragmaHandler(const char *prefix, PrintPPOutputPPCallbacks *callbacks)
485    : Prefix(prefix), Callbacks(callbacks) {}
486  virtual void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
487                            Token &PragmaTok) {
488    // Figure out what line we went to and insert the appropriate number of
489    // newline characters.
490    Callbacks->startNewLineIfNeeded();
491    Callbacks->MoveToLine(PragmaTok.getLocation());
492    Callbacks->OS.write(Prefix, strlen(Prefix));
493    // Read and print all of the pragma tokens.
494    while (PragmaTok.isNot(tok::eod)) {
495      if (PragmaTok.hasLeadingSpace())
496        Callbacks->OS << ' ';
497      std::string TokSpell = PP.getSpelling(PragmaTok);
498      Callbacks->OS.write(&TokSpell[0], TokSpell.size());
499      PP.LexUnexpandedToken(PragmaTok);
500    }
501    Callbacks->setEmittedDirectiveOnThisLine();
502  }
503};
504} // end anonymous namespace
505
506
507static void PrintPreprocessedTokens(Preprocessor &PP, Token &Tok,
508                                    PrintPPOutputPPCallbacks *Callbacks,
509                                    raw_ostream &OS) {
510  char Buffer[256];
511  Token PrevPrevTok, PrevTok;
512  PrevPrevTok.startToken();
513  PrevTok.startToken();
514  while (1) {
515    if (Callbacks->hasEmittedDirectiveOnThisLine()) {
516      Callbacks->startNewLineIfNeeded();
517      Callbacks->MoveToLine(Tok.getLocation());
518    }
519
520    // If this token is at the start of a line, emit newlines if needed.
521    if (Tok.isAtStartOfLine() && Callbacks->HandleFirstTokOnLine(Tok)) {
522      // done.
523    } else if (Tok.hasLeadingSpace() ||
524               // If we haven't emitted a token on this line yet, PrevTok isn't
525               // useful to look at and no concatenation could happen anyway.
526               (Callbacks->hasEmittedTokensOnThisLine() &&
527                // Don't print "-" next to "-", it would form "--".
528                Callbacks->AvoidConcat(PrevPrevTok, PrevTok, Tok))) {
529      OS << ' ';
530    }
531
532    if (IdentifierInfo *II = Tok.getIdentifierInfo()) {
533      OS << II->getName();
534    } else if (Tok.isLiteral() && !Tok.needsCleaning() &&
535               Tok.getLiteralData()) {
536      OS.write(Tok.getLiteralData(), Tok.getLength());
537    } else if (Tok.getLength() < 256) {
538      const char *TokPtr = Buffer;
539      unsigned Len = PP.getSpelling(Tok, TokPtr);
540      OS.write(TokPtr, Len);
541
542      // Tokens that can contain embedded newlines need to adjust our current
543      // line number.
544      if (Tok.getKind() == tok::comment)
545        Callbacks->HandleNewlinesInToken(TokPtr, Len);
546    } else {
547      std::string S = PP.getSpelling(Tok);
548      OS.write(&S[0], S.size());
549
550      // Tokens that can contain embedded newlines need to adjust our current
551      // line number.
552      if (Tok.getKind() == tok::comment)
553        Callbacks->HandleNewlinesInToken(&S[0], S.size());
554    }
555    Callbacks->setEmittedTokensOnThisLine();
556
557    if (Tok.is(tok::eof)) break;
558
559    PrevPrevTok = PrevTok;
560    PrevTok = Tok;
561    PP.Lex(Tok);
562  }
563}
564
565typedef std::pair<IdentifierInfo*, MacroInfo*> id_macro_pair;
566static int MacroIDCompare(const void* a, const void* b) {
567  const id_macro_pair *LHS = static_cast<const id_macro_pair*>(a);
568  const id_macro_pair *RHS = static_cast<const id_macro_pair*>(b);
569  return LHS->first->getName().compare(RHS->first->getName());
570}
571
572static void DoPrintMacros(Preprocessor &PP, raw_ostream *OS) {
573  // Ignore unknown pragmas.
574  PP.AddPragmaHandler(new EmptyPragmaHandler());
575
576  // -dM mode just scans and ignores all tokens in the files, then dumps out
577  // the macro table at the end.
578  PP.EnterMainSourceFile();
579
580  Token Tok;
581  do PP.Lex(Tok);
582  while (Tok.isNot(tok::eof));
583
584  SmallVector<id_macro_pair, 128> MacrosByID;
585  for (Preprocessor::macro_iterator I = PP.macro_begin(), E = PP.macro_end();
586       I != E; ++I) {
587    if (I->first->hasMacroDefinition())
588      MacrosByID.push_back(id_macro_pair(I->first, I->second));
589  }
590  llvm::array_pod_sort(MacrosByID.begin(), MacrosByID.end(), MacroIDCompare);
591
592  for (unsigned i = 0, e = MacrosByID.size(); i != e; ++i) {
593    MacroInfo &MI = *MacrosByID[i].second;
594    // Ignore computed macros like __LINE__ and friends.
595    if (MI.isBuiltinMacro()) continue;
596
597    PrintMacroDefinition(*MacrosByID[i].first, MI, PP, *OS);
598    *OS << '\n';
599  }
600}
601
602/// DoPrintPreprocessedInput - This implements -E mode.
603///
604void clang::DoPrintPreprocessedInput(Preprocessor &PP, raw_ostream *OS,
605                                     const PreprocessorOutputOptions &Opts) {
606  // Show macros with no output is handled specially.
607  if (!Opts.ShowCPP) {
608    assert(Opts.ShowMacros && "Not yet implemented!");
609    DoPrintMacros(PP, OS);
610    return;
611  }
612
613  // Inform the preprocessor whether we want it to retain comments or not, due
614  // to -C or -CC.
615  PP.SetCommentRetentionState(Opts.ShowComments, Opts.ShowMacroComments);
616
617  PrintPPOutputPPCallbacks *Callbacks =
618      new PrintPPOutputPPCallbacks(PP, *OS, !Opts.ShowLineMarkers,
619                                   Opts.ShowMacros);
620  PP.AddPragmaHandler(new UnknownPragmaHandler("#pragma", Callbacks));
621  PP.AddPragmaHandler("GCC", new UnknownPragmaHandler("#pragma GCC",Callbacks));
622  PP.AddPragmaHandler("clang",
623                      new UnknownPragmaHandler("#pragma clang", Callbacks));
624
625  PP.addPPCallbacks(Callbacks);
626
627  // After we have configured the preprocessor, enter the main file.
628  PP.EnterMainSourceFile();
629
630  // Consume all of the tokens that come from the predefines buffer.  Those
631  // should not be emitted into the output and are guaranteed to be at the
632  // start.
633  const SourceManager &SourceMgr = PP.getSourceManager();
634  Token Tok;
635  do {
636    PP.Lex(Tok);
637    if (Tok.is(tok::eof) || !Tok.getLocation().isFileID())
638      break;
639
640    PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
641    if (PLoc.isInvalid())
642      break;
643
644    if (strcmp(PLoc.getFilename(), "<built-in>"))
645      break;
646  } while (true);
647
648  // Read all the preprocessed tokens, printing them out to the stream.
649  PrintPreprocessedTokens(PP, Tok, Callbacks, *OS);
650  *OS << '\n';
651}
652