FormatString.cpp revision 47ad6ce1afad6b70927347dfa15e0f1dc76bf5bb 
1// FormatString.cpp - Common stuff for handling printf/scanf formats -*- C++ -*-
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// Shared details for processing format strings of printf and scanf
11// (and friends).
12//
13//===----------------------------------------------------------------------===//
14
15#include "FormatStringParsing.h"
16#include "clang/Basic/LangOptions.h"
17#include "clang/Basic/TargetInfo.h"
18
19using clang::analyze_format_string::ArgType;
20using clang::analyze_format_string::FormatStringHandler;
21using clang::analyze_format_string::FormatSpecifier;
22using clang::analyze_format_string::LengthModifier;
23using clang::analyze_format_string::OptionalAmount;
24using clang::analyze_format_string::PositionContext;
25using clang::analyze_format_string::ConversionSpecifier;
26using namespace clang;
27
28// Key function to FormatStringHandler.
29FormatStringHandler::~FormatStringHandler() {}
30
31//===----------------------------------------------------------------------===//
32// Functions for parsing format strings components in both printf and
33// scanf format strings.
34//===----------------------------------------------------------------------===//
35
36OptionalAmount
37clang::analyze_format_string::ParseAmount(const char *&Beg, const char *E) {
38  const char *I = Beg;
39  UpdateOnReturn <const char*> UpdateBeg(Beg, I);
40
41  unsigned accumulator = 0;
42  bool hasDigits = false;
43
44  for ( ; I != E; ++I) {
45    char c = *I;
46    if (c >= '0' && c <= '9') {
47      hasDigits = true;
48      accumulator = (accumulator * 10) + (c - '0');
49      continue;
50    }
51
52    if (hasDigits)
53      return OptionalAmount(OptionalAmount::Constant, accumulator, Beg, I - Beg,
54          false);
55
56    break;
57  }
58
59  return OptionalAmount();
60}
61
62OptionalAmount
63clang::analyze_format_string::ParseNonPositionAmount(const char *&Beg,
64                                                     const char *E,
65                                                     unsigned &argIndex) {
66  if (*Beg == '*') {
67    ++Beg;
68    return OptionalAmount(OptionalAmount::Arg, argIndex++, Beg, 0, false);
69  }
70
71  return ParseAmount(Beg, E);
72}
73
74OptionalAmount
75clang::analyze_format_string::ParsePositionAmount(FormatStringHandler &H,
76                                                  const char *Start,
77                                                  const char *&Beg,
78                                                  const char *E,
79                                                  PositionContext p) {
80  if (*Beg == '*') {
81    const char *I = Beg + 1;
82    const OptionalAmount &Amt = ParseAmount(I, E);
83
84    if (Amt.getHowSpecified() == OptionalAmount::NotSpecified) {
85      H.HandleInvalidPosition(Beg, I - Beg, p);
86      return OptionalAmount(false);
87    }
88
89    if (I == E) {
90      // No more characters left?
91      H.HandleIncompleteSpecifier(Start, E - Start);
92      return OptionalAmount(false);
93    }
94
95    assert(Amt.getHowSpecified() == OptionalAmount::Constant);
96
97    if (*I == '$') {
98      // Handle positional arguments
99
100      // Special case: '*0$', since this is an easy mistake.
101      if (Amt.getConstantAmount() == 0) {
102        H.HandleZeroPosition(Beg, I - Beg + 1);
103        return OptionalAmount(false);
104      }
105
106      const char *Tmp = Beg;
107      Beg = ++I;
108
109      return OptionalAmount(OptionalAmount::Arg, Amt.getConstantAmount() - 1,
110                            Tmp, 0, true);
111    }
112
113    H.HandleInvalidPosition(Beg, I - Beg, p);
114    return OptionalAmount(false);
115  }
116
117  return ParseAmount(Beg, E);
118}
119
120
121bool
122clang::analyze_format_string::ParseFieldWidth(FormatStringHandler &H,
123                                              FormatSpecifier &CS,
124                                              const char *Start,
125                                              const char *&Beg, const char *E,
126                                              unsigned *argIndex) {
127  // FIXME: Support negative field widths.
128  if (argIndex) {
129    CS.setFieldWidth(ParseNonPositionAmount(Beg, E, *argIndex));
130  }
131  else {
132    const OptionalAmount Amt =
133      ParsePositionAmount(H, Start, Beg, E,
134                          analyze_format_string::FieldWidthPos);
135
136    if (Amt.isInvalid())
137      return true;
138    CS.setFieldWidth(Amt);
139  }
140  return false;
141}
142
143bool
144clang::analyze_format_string::ParseArgPosition(FormatStringHandler &H,
145                                               FormatSpecifier &FS,
146                                               const char *Start,
147                                               const char *&Beg,
148                                               const char *E) {
149  const char *I = Beg;
150
151  const OptionalAmount &Amt = ParseAmount(I, E);
152
153  if (I == E) {
154    // No more characters left?
155    H.HandleIncompleteSpecifier(Start, E - Start);
156    return true;
157  }
158
159  if (Amt.getHowSpecified() == OptionalAmount::Constant && *(I++) == '$') {
160    // Warn that positional arguments are non-standard.
161    H.HandlePosition(Start, I - Start);
162
163    // Special case: '%0$', since this is an easy mistake.
164    if (Amt.getConstantAmount() == 0) {
165      H.HandleZeroPosition(Start, I - Start);
166      return true;
167    }
168
169    FS.setArgIndex(Amt.getConstantAmount() - 1);
170    FS.setUsesPositionalArg();
171    // Update the caller's pointer if we decided to consume
172    // these characters.
173    Beg = I;
174    return false;
175  }
176
177  return false;
178}
179
180bool
181clang::analyze_format_string::ParseLengthModifier(FormatSpecifier &FS,
182                                                  const char *&I,
183                                                  const char *E,
184                                                  const LangOptions &LO,
185                                                  bool IsScanf) {
186  LengthModifier::Kind lmKind = LengthModifier::None;
187  const char *lmPosition = I;
188  switch (*I) {
189    default:
190      return false;
191    case 'h':
192      ++I;
193      lmKind = (I != E && *I == 'h') ? (++I, LengthModifier::AsChar)
194                                     : LengthModifier::AsShort;
195      break;
196    case 'l':
197      ++I;
198      lmKind = (I != E && *I == 'l') ? (++I, LengthModifier::AsLongLong)
199                                     : LengthModifier::AsLong;
200      break;
201    case 'j': lmKind = LengthModifier::AsIntMax;     ++I; break;
202    case 'z': lmKind = LengthModifier::AsSizeT;      ++I; break;
203    case 't': lmKind = LengthModifier::AsPtrDiff;    ++I; break;
204    case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break;
205    case 'q': lmKind = LengthModifier::AsQuad;       ++I; break;
206    case 'a':
207      if (IsScanf && !LO.C99 && !LO.CPlusPlus11) {
208        // For scanf in C90, look at the next character to see if this should
209        // be parsed as the GNU extension 'a' length modifier. If not, this
210        // will be parsed as a conversion specifier.
211        ++I;
212        if (I != E && (*I == 's' || *I == 'S' || *I == '[')) {
213          lmKind = LengthModifier::AsAllocate;
214          break;
215        }
216        --I;
217      }
218      return false;
219    case 'm':
220      if (IsScanf) {
221        lmKind = LengthModifier::AsMAllocate;
222        ++I;
223        break;
224      }
225      return false;
226    // printf: AsInt64, AsInt32, AsInt3264
227    // scanf:  AsInt64
228    case 'I':
229      if (I + 1 != E && I + 2 != E) {
230        if (I[1] == '6' && I[2] == '4') {
231          I += 3;
232          lmKind = LengthModifier::AsInt64;
233          break;
234        }
235        if (IsScanf)
236          return false;
237
238        if (I[1] == '3' && I[2] == '2') {
239          I += 3;
240          lmKind = LengthModifier::AsInt32;
241          break;
242        }
243      }
244      ++I;
245      lmKind = LengthModifier::AsInt3264;
246      break;
247  }
248  LengthModifier lm(lmPosition, lmKind);
249  FS.setLengthModifier(lm);
250  return true;
251}
252
253//===----------------------------------------------------------------------===//
254// Methods on ArgType.
255//===----------------------------------------------------------------------===//
256
257bool ArgType::matchesType(ASTContext &C, QualType argTy) const {
258  if (Ptr) {
259    // It has to be a pointer.
260    const PointerType *PT = argTy->getAs<PointerType>();
261    if (!PT)
262      return false;
263
264    // We cannot write through a const qualified pointer.
265    if (PT->getPointeeType().isConstQualified())
266      return false;
267
268    argTy = PT->getPointeeType();
269  }
270
271  switch (K) {
272    case InvalidTy:
273      llvm_unreachable("ArgType must be valid");
274
275    case UnknownTy:
276      return true;
277
278    case AnyCharTy: {
279      if (const EnumType *ETy = argTy->getAs<EnumType>())
280        argTy = ETy->getDecl()->getIntegerType();
281
282      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
283        switch (BT->getKind()) {
284          default:
285            break;
286          case BuiltinType::Char_S:
287          case BuiltinType::SChar:
288          case BuiltinType::UChar:
289          case BuiltinType::Char_U:
290            return true;
291        }
292      return false;
293    }
294
295    case SpecificTy: {
296      if (const EnumType *ETy = argTy->getAs<EnumType>())
297        argTy = ETy->getDecl()->getIntegerType();
298      argTy = C.getCanonicalType(argTy).getUnqualifiedType();
299
300      if (T == argTy)
301        return true;
302      // Check for "compatible types".
303      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
304        switch (BT->getKind()) {
305          default:
306            break;
307          case BuiltinType::Char_S:
308          case BuiltinType::SChar:
309          case BuiltinType::Char_U:
310          case BuiltinType::UChar:
311            return T == C.UnsignedCharTy || T == C.SignedCharTy;
312          case BuiltinType::Short:
313            return T == C.UnsignedShortTy;
314          case BuiltinType::UShort:
315            return T == C.ShortTy;
316          case BuiltinType::Int:
317            return T == C.UnsignedIntTy;
318          case BuiltinType::UInt:
319            return T == C.IntTy;
320          case BuiltinType::Long:
321            return T == C.UnsignedLongTy;
322          case BuiltinType::ULong:
323            return T == C.LongTy;
324          case BuiltinType::LongLong:
325            return T == C.UnsignedLongLongTy;
326          case BuiltinType::ULongLong:
327            return T == C.LongLongTy;
328        }
329      return false;
330    }
331
332    case CStrTy: {
333      const PointerType *PT = argTy->getAs<PointerType>();
334      if (!PT)
335        return false;
336      QualType pointeeTy = PT->getPointeeType();
337      if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
338        switch (BT->getKind()) {
339          case BuiltinType::Void:
340          case BuiltinType::Char_U:
341          case BuiltinType::UChar:
342          case BuiltinType::Char_S:
343          case BuiltinType::SChar:
344            return true;
345          default:
346            break;
347        }
348
349      return false;
350    }
351
352    case WCStrTy: {
353      const PointerType *PT = argTy->getAs<PointerType>();
354      if (!PT)
355        return false;
356      QualType pointeeTy =
357        C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType();
358      return pointeeTy == C.getWideCharType();
359    }
360
361    case WIntTy: {
362
363      QualType PromoArg =
364        argTy->isPromotableIntegerType()
365          ? C.getPromotedIntegerType(argTy) : argTy;
366
367      QualType WInt = C.getCanonicalType(C.getWIntType()).getUnqualifiedType();
368      PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
369
370      // If the promoted argument is the corresponding signed type of the
371      // wint_t type, then it should match.
372      if (PromoArg->hasSignedIntegerRepresentation() &&
373          C.getCorrespondingUnsignedType(PromoArg) == WInt)
374        return true;
375
376      return WInt == PromoArg;
377    }
378
379    case CPointerTy:
380      return argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
381             argTy->isBlockPointerType() || argTy->isNullPtrType();
382
383    case ObjCPointerTy: {
384      if (argTy->getAs<ObjCObjectPointerType>() ||
385          argTy->getAs<BlockPointerType>())
386        return true;
387
388      // Handle implicit toll-free bridging.
389      if (const PointerType *PT = argTy->getAs<PointerType>()) {
390        // Things such as CFTypeRef are really just opaque pointers
391        // to C structs representing CF types that can often be bridged
392        // to Objective-C objects.  Since the compiler doesn't know which
393        // structs can be toll-free bridged, we just accept them all.
394        QualType pointee = PT->getPointeeType();
395        if (pointee->getAsStructureType() || pointee->isVoidType())
396          return true;
397      }
398      return false;
399    }
400  }
401
402  llvm_unreachable("Invalid ArgType Kind!");
403}
404
405QualType ArgType::getRepresentativeType(ASTContext &C) const {
406  QualType Res;
407  switch (K) {
408    case InvalidTy:
409      llvm_unreachable("No representative type for Invalid ArgType");
410    case UnknownTy:
411      llvm_unreachable("No representative type for Unknown ArgType");
412    case AnyCharTy:
413      Res = C.CharTy;
414      break;
415    case SpecificTy:
416      Res = T;
417      break;
418    case CStrTy:
419      Res = C.getPointerType(C.CharTy);
420      break;
421    case WCStrTy:
422      Res = C.getPointerType(C.getWideCharType());
423      break;
424    case ObjCPointerTy:
425      Res = C.ObjCBuiltinIdTy;
426      break;
427    case CPointerTy:
428      Res = C.VoidPtrTy;
429      break;
430    case WIntTy: {
431      Res = C.getWIntType();
432      break;
433    }
434  }
435
436  if (Ptr)
437    Res = C.getPointerType(Res);
438  return Res;
439}
440
441std::string ArgType::getRepresentativeTypeName(ASTContext &C) const {
442  std::string S = getRepresentativeType(C).getAsString();
443
444  std::string Alias;
445  if (Name) {
446    // Use a specific name for this type, e.g. "size_t".
447    Alias = Name;
448    if (Ptr) {
449      // If ArgType is actually a pointer to T, append an asterisk.
450      Alias += (Alias[Alias.size()-1] == '*') ? "*" : " *";
451    }
452    // If Alias is the same as the underlying type, e.g. wchar_t, then drop it.
453    if (S == Alias)
454      Alias.clear();
455  }
456
457  if (!Alias.empty())
458    return std::string("'") + Alias + "' (aka '" + S + "')";
459  return std::string("'") + S + "'";
460}
461
462
463//===----------------------------------------------------------------------===//
464// Methods on OptionalAmount.
465//===----------------------------------------------------------------------===//
466
467ArgType
468analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const {
469  return Ctx.IntTy;
470}
471
472//===----------------------------------------------------------------------===//
473// Methods on LengthModifier.
474//===----------------------------------------------------------------------===//
475
476const char *
477analyze_format_string::LengthModifier::toString() const {
478  switch (kind) {
479  case AsChar:
480    return "hh";
481  case AsShort:
482    return "h";
483  case AsLong: // or AsWideChar
484    return "l";
485  case AsLongLong:
486    return "ll";
487  case AsQuad:
488    return "q";
489  case AsIntMax:
490    return "j";
491  case AsSizeT:
492    return "z";
493  case AsPtrDiff:
494    return "t";
495  case AsInt32:
496    return "I32";
497  case AsInt3264:
498    return "I";
499  case AsInt64:
500    return "I64";
501  case AsLongDouble:
502    return "L";
503  case AsAllocate:
504    return "a";
505  case AsMAllocate:
506    return "m";
507  case None:
508    return "";
509  }
510  return NULL;
511}
512
513//===----------------------------------------------------------------------===//
514// Methods on ConversionSpecifier.
515//===----------------------------------------------------------------------===//
516
517const char *ConversionSpecifier::toString() const {
518  switch (kind) {
519  case dArg: return "d";
520  case DArg: return "D";
521  case iArg: return "i";
522  case oArg: return "o";
523  case OArg: return "O";
524  case uArg: return "u";
525  case UArg: return "U";
526  case xArg: return "x";
527  case XArg: return "X";
528  case fArg: return "f";
529  case FArg: return "F";
530  case eArg: return "e";
531  case EArg: return "E";
532  case gArg: return "g";
533  case GArg: return "G";
534  case aArg: return "a";
535  case AArg: return "A";
536  case cArg: return "c";
537  case sArg: return "s";
538  case pArg: return "p";
539  case nArg: return "n";
540  case PercentArg:  return "%";
541  case ScanListArg: return "[";
542  case InvalidSpecifier: return NULL;
543
544  // POSIX unicode extensions.
545  case CArg: return "C";
546  case SArg: return "S";
547
548  // Objective-C specific specifiers.
549  case ObjCObjArg: return "@";
550
551  // GlibC specific specifiers.
552  case PrintErrno: return "m";
553  }
554  return NULL;
555}
556
557Optional<ConversionSpecifier>
558ConversionSpecifier::getStandardSpecifier() const {
559  ConversionSpecifier::Kind NewKind;
560
561  switch (getKind()) {
562  default:
563    return None;
564  case DArg:
565    NewKind = dArg;
566    break;
567  case UArg:
568    NewKind = uArg;
569    break;
570  case OArg:
571    NewKind = oArg;
572    break;
573  }
574
575  ConversionSpecifier FixedCS(*this);
576  FixedCS.setKind(NewKind);
577  return FixedCS;
578}
579
580//===----------------------------------------------------------------------===//
581// Methods on OptionalAmount.
582//===----------------------------------------------------------------------===//
583
584void OptionalAmount::toString(raw_ostream &os) const {
585  switch (hs) {
586  case Invalid:
587  case NotSpecified:
588    return;
589  case Arg:
590    if (UsesDotPrefix)
591        os << ".";
592    if (usesPositionalArg())
593      os << "*" << getPositionalArgIndex() << "$";
594    else
595      os << "*";
596    break;
597  case Constant:
598    if (UsesDotPrefix)
599        os << ".";
600    os << amt;
601    break;
602  }
603}
604
605bool FormatSpecifier::hasValidLengthModifier(const TargetInfo &Target) const {
606  switch (LM.getKind()) {
607    case LengthModifier::None:
608      return true;
609
610    // Handle most integer flags
611    case LengthModifier::AsChar:
612    case LengthModifier::AsShort:
613    case LengthModifier::AsLongLong:
614    case LengthModifier::AsQuad:
615    case LengthModifier::AsIntMax:
616    case LengthModifier::AsSizeT:
617    case LengthModifier::AsPtrDiff:
618      switch (CS.getKind()) {
619        case ConversionSpecifier::dArg:
620        case ConversionSpecifier::DArg:
621        case ConversionSpecifier::iArg:
622        case ConversionSpecifier::oArg:
623        case ConversionSpecifier::OArg:
624        case ConversionSpecifier::uArg:
625        case ConversionSpecifier::UArg:
626        case ConversionSpecifier::xArg:
627        case ConversionSpecifier::XArg:
628        case ConversionSpecifier::nArg:
629          return true;
630        default:
631          return false;
632      }
633
634    // Handle 'l' flag
635    case LengthModifier::AsLong:
636      switch (CS.getKind()) {
637        case ConversionSpecifier::dArg:
638        case ConversionSpecifier::DArg:
639        case ConversionSpecifier::iArg:
640        case ConversionSpecifier::oArg:
641        case ConversionSpecifier::OArg:
642        case ConversionSpecifier::uArg:
643        case ConversionSpecifier::UArg:
644        case ConversionSpecifier::xArg:
645        case ConversionSpecifier::XArg:
646        case ConversionSpecifier::aArg:
647        case ConversionSpecifier::AArg:
648        case ConversionSpecifier::fArg:
649        case ConversionSpecifier::FArg:
650        case ConversionSpecifier::eArg:
651        case ConversionSpecifier::EArg:
652        case ConversionSpecifier::gArg:
653        case ConversionSpecifier::GArg:
654        case ConversionSpecifier::nArg:
655        case ConversionSpecifier::cArg:
656        case ConversionSpecifier::sArg:
657        case ConversionSpecifier::ScanListArg:
658          return true;
659        default:
660          return false;
661      }
662
663    case LengthModifier::AsLongDouble:
664      switch (CS.getKind()) {
665        case ConversionSpecifier::aArg:
666        case ConversionSpecifier::AArg:
667        case ConversionSpecifier::fArg:
668        case ConversionSpecifier::FArg:
669        case ConversionSpecifier::eArg:
670        case ConversionSpecifier::EArg:
671        case ConversionSpecifier::gArg:
672        case ConversionSpecifier::GArg:
673          return true;
674        // GNU libc extension.
675        case ConversionSpecifier::dArg:
676        case ConversionSpecifier::iArg:
677        case ConversionSpecifier::oArg:
678        case ConversionSpecifier::uArg:
679        case ConversionSpecifier::xArg:
680        case ConversionSpecifier::XArg:
681          return !Target.getTriple().isOSDarwin() &&
682                 !Target.getTriple().isOSWindows();
683        default:
684          return false;
685      }
686
687    case LengthModifier::AsAllocate:
688      switch (CS.getKind()) {
689        case ConversionSpecifier::sArg:
690        case ConversionSpecifier::SArg:
691        case ConversionSpecifier::ScanListArg:
692          return true;
693        default:
694          return false;
695      }
696
697    case LengthModifier::AsMAllocate:
698      switch (CS.getKind()) {
699        case ConversionSpecifier::cArg:
700        case ConversionSpecifier::CArg:
701        case ConversionSpecifier::sArg:
702        case ConversionSpecifier::SArg:
703        case ConversionSpecifier::ScanListArg:
704          return true;
705        default:
706          return false;
707      }
708    case LengthModifier::AsInt32:
709    case LengthModifier::AsInt3264:
710    case LengthModifier::AsInt64:
711      switch (CS.getKind()) {
712        case ConversionSpecifier::dArg:
713        case ConversionSpecifier::iArg:
714        case ConversionSpecifier::oArg:
715        case ConversionSpecifier::uArg:
716        case ConversionSpecifier::xArg:
717        case ConversionSpecifier::XArg:
718          return Target.getTriple().isOSMSVCRT();
719        default:
720          return false;
721      }
722  }
723  llvm_unreachable("Invalid LengthModifier Kind!");
724}
725
726bool FormatSpecifier::hasStandardLengthModifier() const {
727  switch (LM.getKind()) {
728    case LengthModifier::None:
729    case LengthModifier::AsChar:
730    case LengthModifier::AsShort:
731    case LengthModifier::AsLong:
732    case LengthModifier::AsLongLong:
733    case LengthModifier::AsIntMax:
734    case LengthModifier::AsSizeT:
735    case LengthModifier::AsPtrDiff:
736    case LengthModifier::AsLongDouble:
737      return true;
738    case LengthModifier::AsAllocate:
739    case LengthModifier::AsMAllocate:
740    case LengthModifier::AsQuad:
741    case LengthModifier::AsInt32:
742    case LengthModifier::AsInt3264:
743    case LengthModifier::AsInt64:
744      return false;
745  }
746  llvm_unreachable("Invalid LengthModifier Kind!");
747}
748
749bool FormatSpecifier::hasStandardConversionSpecifier(const LangOptions &LangOpt) const {
750  switch (CS.getKind()) {
751    case ConversionSpecifier::cArg:
752    case ConversionSpecifier::dArg:
753    case ConversionSpecifier::iArg:
754    case ConversionSpecifier::oArg:
755    case ConversionSpecifier::uArg:
756    case ConversionSpecifier::xArg:
757    case ConversionSpecifier::XArg:
758    case ConversionSpecifier::fArg:
759    case ConversionSpecifier::FArg:
760    case ConversionSpecifier::eArg:
761    case ConversionSpecifier::EArg:
762    case ConversionSpecifier::gArg:
763    case ConversionSpecifier::GArg:
764    case ConversionSpecifier::aArg:
765    case ConversionSpecifier::AArg:
766    case ConversionSpecifier::sArg:
767    case ConversionSpecifier::pArg:
768    case ConversionSpecifier::nArg:
769    case ConversionSpecifier::ObjCObjArg:
770    case ConversionSpecifier::ScanListArg:
771    case ConversionSpecifier::PercentArg:
772      return true;
773    case ConversionSpecifier::CArg:
774    case ConversionSpecifier::SArg:
775      return LangOpt.ObjC1 || LangOpt.ObjC2;
776    case ConversionSpecifier::InvalidSpecifier:
777    case ConversionSpecifier::PrintErrno:
778    case ConversionSpecifier::DArg:
779    case ConversionSpecifier::OArg:
780    case ConversionSpecifier::UArg:
781      return false;
782  }
783  llvm_unreachable("Invalid ConversionSpecifier Kind!");
784}
785
786bool FormatSpecifier::hasStandardLengthConversionCombination() const {
787  if (LM.getKind() == LengthModifier::AsLongDouble) {
788    switch(CS.getKind()) {
789        case ConversionSpecifier::dArg:
790        case ConversionSpecifier::iArg:
791        case ConversionSpecifier::oArg:
792        case ConversionSpecifier::uArg:
793        case ConversionSpecifier::xArg:
794        case ConversionSpecifier::XArg:
795          return false;
796        default:
797          return true;
798    }
799  }
800  return true;
801}
802
803Optional<LengthModifier> FormatSpecifier::getCorrectedLengthModifier() const {
804  if (CS.isAnyIntArg() || CS.getKind() == ConversionSpecifier::nArg) {
805    if (LM.getKind() == LengthModifier::AsLongDouble ||
806        LM.getKind() == LengthModifier::AsQuad) {
807      LengthModifier FixedLM(LM);
808      FixedLM.setKind(LengthModifier::AsLongLong);
809      return FixedLM;
810    }
811  }
812
813  return None;
814}
815
816bool FormatSpecifier::namedTypeToLengthModifier(QualType QT,
817                                                LengthModifier &LM) {
818  assert(isa<TypedefType>(QT) && "Expected a TypedefType");
819  const TypedefNameDecl *Typedef = cast<TypedefType>(QT)->getDecl();
820
821  for (;;) {
822    const IdentifierInfo *Identifier = Typedef->getIdentifier();
823    if (Identifier->getName() == "size_t") {
824      LM.setKind(LengthModifier::AsSizeT);
825      return true;
826    } else if (Identifier->getName() == "ssize_t") {
827      // Not C99, but common in Unix.
828      LM.setKind(LengthModifier::AsSizeT);
829      return true;
830    } else if (Identifier->getName() == "intmax_t") {
831      LM.setKind(LengthModifier::AsIntMax);
832      return true;
833    } else if (Identifier->getName() == "uintmax_t") {
834      LM.setKind(LengthModifier::AsIntMax);
835      return true;
836    } else if (Identifier->getName() == "ptrdiff_t") {
837      LM.setKind(LengthModifier::AsPtrDiff);
838      return true;
839    }
840
841    QualType T = Typedef->getUnderlyingType();
842    if (!isa<TypedefType>(T))
843      break;
844
845    Typedef = cast<TypedefType>(T)->getDecl();
846  }
847  return false;
848}
849