SemaChecking.cpp revision 0234bfa2b03470b8ce379a7485e60ffa35c1d550 
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
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 file implements extra semantic analysis beyond what is enforced
11//  by the C type system.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/Initialization.h"
16#include "clang/Sema/Sema.h"
17#include "clang/Sema/SemaInternal.h"
18#include "clang/Sema/Initialization.h"
19#include "clang/Sema/Lookup.h"
20#include "clang/Sema/ScopeInfo.h"
21#include "clang/Analysis/Analyses/FormatString.h"
22#include "clang/AST/ASTContext.h"
23#include "clang/AST/CharUnits.h"
24#include "clang/AST/DeclCXX.h"
25#include "clang/AST/DeclObjC.h"
26#include "clang/AST/Expr.h"
27#include "clang/AST/ExprCXX.h"
28#include "clang/AST/ExprObjC.h"
29#include "clang/AST/EvaluatedExprVisitor.h"
30#include "clang/AST/DeclObjC.h"
31#include "clang/AST/StmtCXX.h"
32#include "clang/AST/StmtObjC.h"
33#include "clang/Lex/Preprocessor.h"
34#include "llvm/ADT/BitVector.h"
35#include "llvm/ADT/SmallString.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/Support/raw_ostream.h"
38#include "clang/Basic/TargetBuiltins.h"
39#include "clang/Basic/TargetInfo.h"
40#include "clang/Basic/ConvertUTF.h"
41#include <limits>
42using namespace clang;
43using namespace sema;
44
45SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
46                                                    unsigned ByteNo) const {
47  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
48                               PP.getLangOpts(), PP.getTargetInfo());
49}
50
51/// Checks that a call expression's argument count is the desired number.
52/// This is useful when doing custom type-checking.  Returns true on error.
53static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
54  unsigned argCount = call->getNumArgs();
55  if (argCount == desiredArgCount) return false;
56
57  if (argCount < desiredArgCount)
58    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
59        << 0 /*function call*/ << desiredArgCount << argCount
60        << call->getSourceRange();
61
62  // Highlight all the excess arguments.
63  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
64                    call->getArg(argCount - 1)->getLocEnd());
65
66  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
67    << 0 /*function call*/ << desiredArgCount << argCount
68    << call->getArg(1)->getSourceRange();
69}
70
71/// Check that the first argument to __builtin_annotation is an integer
72/// and the second argument is a non-wide string literal.
73static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
74  if (checkArgCount(S, TheCall, 2))
75    return true;
76
77  // First argument should be an integer.
78  Expr *ValArg = TheCall->getArg(0);
79  QualType Ty = ValArg->getType();
80  if (!Ty->isIntegerType()) {
81    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
82      << ValArg->getSourceRange();
83    return true;
84  }
85
86  // Second argument should be a constant string.
87  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
88  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
89  if (!Literal || !Literal->isAscii()) {
90    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
91      << StrArg->getSourceRange();
92    return true;
93  }
94
95  TheCall->setType(Ty);
96  return false;
97}
98
99ExprResult
100Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
101  ExprResult TheCallResult(Owned(TheCall));
102
103  // Find out if any arguments are required to be integer constant expressions.
104  unsigned ICEArguments = 0;
105  ASTContext::GetBuiltinTypeError Error;
106  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
107  if (Error != ASTContext::GE_None)
108    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
109
110  // If any arguments are required to be ICE's, check and diagnose.
111  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
112    // Skip arguments not required to be ICE's.
113    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
114
115    llvm::APSInt Result;
116    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
117      return true;
118    ICEArguments &= ~(1 << ArgNo);
119  }
120
121  switch (BuiltinID) {
122  case Builtin::BI__builtin___CFStringMakeConstantString:
123    assert(TheCall->getNumArgs() == 1 &&
124           "Wrong # arguments to builtin CFStringMakeConstantString");
125    if (CheckObjCString(TheCall->getArg(0)))
126      return ExprError();
127    break;
128  case Builtin::BI__builtin_stdarg_start:
129  case Builtin::BI__builtin_va_start:
130    if (SemaBuiltinVAStart(TheCall))
131      return ExprError();
132    break;
133  case Builtin::BI__builtin_isgreater:
134  case Builtin::BI__builtin_isgreaterequal:
135  case Builtin::BI__builtin_isless:
136  case Builtin::BI__builtin_islessequal:
137  case Builtin::BI__builtin_islessgreater:
138  case Builtin::BI__builtin_isunordered:
139    if (SemaBuiltinUnorderedCompare(TheCall))
140      return ExprError();
141    break;
142  case Builtin::BI__builtin_fpclassify:
143    if (SemaBuiltinFPClassification(TheCall, 6))
144      return ExprError();
145    break;
146  case Builtin::BI__builtin_isfinite:
147  case Builtin::BI__builtin_isinf:
148  case Builtin::BI__builtin_isinf_sign:
149  case Builtin::BI__builtin_isnan:
150  case Builtin::BI__builtin_isnormal:
151    if (SemaBuiltinFPClassification(TheCall, 1))
152      return ExprError();
153    break;
154  case Builtin::BI__builtin_shufflevector:
155    return SemaBuiltinShuffleVector(TheCall);
156    // TheCall will be freed by the smart pointer here, but that's fine, since
157    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
158  case Builtin::BI__builtin_prefetch:
159    if (SemaBuiltinPrefetch(TheCall))
160      return ExprError();
161    break;
162  case Builtin::BI__builtin_object_size:
163    if (SemaBuiltinObjectSize(TheCall))
164      return ExprError();
165    break;
166  case Builtin::BI__builtin_longjmp:
167    if (SemaBuiltinLongjmp(TheCall))
168      return ExprError();
169    break;
170
171  case Builtin::BI__builtin_classify_type:
172    if (checkArgCount(*this, TheCall, 1)) return true;
173    TheCall->setType(Context.IntTy);
174    break;
175  case Builtin::BI__builtin_constant_p:
176    if (checkArgCount(*this, TheCall, 1)) return true;
177    TheCall->setType(Context.IntTy);
178    break;
179  case Builtin::BI__sync_fetch_and_add:
180  case Builtin::BI__sync_fetch_and_add_1:
181  case Builtin::BI__sync_fetch_and_add_2:
182  case Builtin::BI__sync_fetch_and_add_4:
183  case Builtin::BI__sync_fetch_and_add_8:
184  case Builtin::BI__sync_fetch_and_add_16:
185  case Builtin::BI__sync_fetch_and_sub:
186  case Builtin::BI__sync_fetch_and_sub_1:
187  case Builtin::BI__sync_fetch_and_sub_2:
188  case Builtin::BI__sync_fetch_and_sub_4:
189  case Builtin::BI__sync_fetch_and_sub_8:
190  case Builtin::BI__sync_fetch_and_sub_16:
191  case Builtin::BI__sync_fetch_and_or:
192  case Builtin::BI__sync_fetch_and_or_1:
193  case Builtin::BI__sync_fetch_and_or_2:
194  case Builtin::BI__sync_fetch_and_or_4:
195  case Builtin::BI__sync_fetch_and_or_8:
196  case Builtin::BI__sync_fetch_and_or_16:
197  case Builtin::BI__sync_fetch_and_and:
198  case Builtin::BI__sync_fetch_and_and_1:
199  case Builtin::BI__sync_fetch_and_and_2:
200  case Builtin::BI__sync_fetch_and_and_4:
201  case Builtin::BI__sync_fetch_and_and_8:
202  case Builtin::BI__sync_fetch_and_and_16:
203  case Builtin::BI__sync_fetch_and_xor:
204  case Builtin::BI__sync_fetch_and_xor_1:
205  case Builtin::BI__sync_fetch_and_xor_2:
206  case Builtin::BI__sync_fetch_and_xor_4:
207  case Builtin::BI__sync_fetch_and_xor_8:
208  case Builtin::BI__sync_fetch_and_xor_16:
209  case Builtin::BI__sync_add_and_fetch:
210  case Builtin::BI__sync_add_and_fetch_1:
211  case Builtin::BI__sync_add_and_fetch_2:
212  case Builtin::BI__sync_add_and_fetch_4:
213  case Builtin::BI__sync_add_and_fetch_8:
214  case Builtin::BI__sync_add_and_fetch_16:
215  case Builtin::BI__sync_sub_and_fetch:
216  case Builtin::BI__sync_sub_and_fetch_1:
217  case Builtin::BI__sync_sub_and_fetch_2:
218  case Builtin::BI__sync_sub_and_fetch_4:
219  case Builtin::BI__sync_sub_and_fetch_8:
220  case Builtin::BI__sync_sub_and_fetch_16:
221  case Builtin::BI__sync_and_and_fetch:
222  case Builtin::BI__sync_and_and_fetch_1:
223  case Builtin::BI__sync_and_and_fetch_2:
224  case Builtin::BI__sync_and_and_fetch_4:
225  case Builtin::BI__sync_and_and_fetch_8:
226  case Builtin::BI__sync_and_and_fetch_16:
227  case Builtin::BI__sync_or_and_fetch:
228  case Builtin::BI__sync_or_and_fetch_1:
229  case Builtin::BI__sync_or_and_fetch_2:
230  case Builtin::BI__sync_or_and_fetch_4:
231  case Builtin::BI__sync_or_and_fetch_8:
232  case Builtin::BI__sync_or_and_fetch_16:
233  case Builtin::BI__sync_xor_and_fetch:
234  case Builtin::BI__sync_xor_and_fetch_1:
235  case Builtin::BI__sync_xor_and_fetch_2:
236  case Builtin::BI__sync_xor_and_fetch_4:
237  case Builtin::BI__sync_xor_and_fetch_8:
238  case Builtin::BI__sync_xor_and_fetch_16:
239  case Builtin::BI__sync_val_compare_and_swap:
240  case Builtin::BI__sync_val_compare_and_swap_1:
241  case Builtin::BI__sync_val_compare_and_swap_2:
242  case Builtin::BI__sync_val_compare_and_swap_4:
243  case Builtin::BI__sync_val_compare_and_swap_8:
244  case Builtin::BI__sync_val_compare_and_swap_16:
245  case Builtin::BI__sync_bool_compare_and_swap:
246  case Builtin::BI__sync_bool_compare_and_swap_1:
247  case Builtin::BI__sync_bool_compare_and_swap_2:
248  case Builtin::BI__sync_bool_compare_and_swap_4:
249  case Builtin::BI__sync_bool_compare_and_swap_8:
250  case Builtin::BI__sync_bool_compare_and_swap_16:
251  case Builtin::BI__sync_lock_test_and_set:
252  case Builtin::BI__sync_lock_test_and_set_1:
253  case Builtin::BI__sync_lock_test_and_set_2:
254  case Builtin::BI__sync_lock_test_and_set_4:
255  case Builtin::BI__sync_lock_test_and_set_8:
256  case Builtin::BI__sync_lock_test_and_set_16:
257  case Builtin::BI__sync_lock_release:
258  case Builtin::BI__sync_lock_release_1:
259  case Builtin::BI__sync_lock_release_2:
260  case Builtin::BI__sync_lock_release_4:
261  case Builtin::BI__sync_lock_release_8:
262  case Builtin::BI__sync_lock_release_16:
263  case Builtin::BI__sync_swap:
264  case Builtin::BI__sync_swap_1:
265  case Builtin::BI__sync_swap_2:
266  case Builtin::BI__sync_swap_4:
267  case Builtin::BI__sync_swap_8:
268  case Builtin::BI__sync_swap_16:
269    return SemaBuiltinAtomicOverloaded(TheCallResult);
270#define BUILTIN(ID, TYPE, ATTRS)
271#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
272  case Builtin::BI##ID: \
273    return SemaAtomicOpsOverloaded(TheCallResult, AtomicExpr::AO##ID);
274#include "clang/Basic/Builtins.def"
275  case Builtin::BI__builtin_annotation:
276    if (SemaBuiltinAnnotation(*this, TheCall))
277      return ExprError();
278    break;
279  }
280
281  // Since the target specific builtins for each arch overlap, only check those
282  // of the arch we are compiling for.
283  if (BuiltinID >= Builtin::FirstTSBuiltin) {
284    switch (Context.getTargetInfo().getTriple().getArch()) {
285      case llvm::Triple::arm:
286      case llvm::Triple::thumb:
287        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
288          return ExprError();
289        break;
290      case llvm::Triple::mips:
291      case llvm::Triple::mipsel:
292      case llvm::Triple::mips64:
293      case llvm::Triple::mips64el:
294        if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
295          return ExprError();
296        break;
297      default:
298        break;
299    }
300  }
301
302  return TheCallResult;
303}
304
305// Get the valid immediate range for the specified NEON type code.
306static unsigned RFT(unsigned t, bool shift = false) {
307  NeonTypeFlags Type(t);
308  int IsQuad = Type.isQuad();
309  switch (Type.getEltType()) {
310  case NeonTypeFlags::Int8:
311  case NeonTypeFlags::Poly8:
312    return shift ? 7 : (8 << IsQuad) - 1;
313  case NeonTypeFlags::Int16:
314  case NeonTypeFlags::Poly16:
315    return shift ? 15 : (4 << IsQuad) - 1;
316  case NeonTypeFlags::Int32:
317    return shift ? 31 : (2 << IsQuad) - 1;
318  case NeonTypeFlags::Int64:
319    return shift ? 63 : (1 << IsQuad) - 1;
320  case NeonTypeFlags::Float16:
321    assert(!shift && "cannot shift float types!");
322    return (4 << IsQuad) - 1;
323  case NeonTypeFlags::Float32:
324    assert(!shift && "cannot shift float types!");
325    return (2 << IsQuad) - 1;
326  }
327  llvm_unreachable("Invalid NeonTypeFlag!");
328}
329
330/// getNeonEltType - Return the QualType corresponding to the elements of
331/// the vector type specified by the NeonTypeFlags.  This is used to check
332/// the pointer arguments for Neon load/store intrinsics.
333static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
334  switch (Flags.getEltType()) {
335  case NeonTypeFlags::Int8:
336    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
337  case NeonTypeFlags::Int16:
338    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
339  case NeonTypeFlags::Int32:
340    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
341  case NeonTypeFlags::Int64:
342    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
343  case NeonTypeFlags::Poly8:
344    return Context.SignedCharTy;
345  case NeonTypeFlags::Poly16:
346    return Context.ShortTy;
347  case NeonTypeFlags::Float16:
348    return Context.UnsignedShortTy;
349  case NeonTypeFlags::Float32:
350    return Context.FloatTy;
351  }
352  llvm_unreachable("Invalid NeonTypeFlag!");
353}
354
355bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
356  llvm::APSInt Result;
357
358  uint64_t mask = 0;
359  unsigned TV = 0;
360  int PtrArgNum = -1;
361  bool HasConstPtr = false;
362  switch (BuiltinID) {
363#define GET_NEON_OVERLOAD_CHECK
364#include "clang/Basic/arm_neon.inc"
365#undef GET_NEON_OVERLOAD_CHECK
366  }
367
368  // For NEON intrinsics which are overloaded on vector element type, validate
369  // the immediate which specifies which variant to emit.
370  unsigned ImmArg = TheCall->getNumArgs()-1;
371  if (mask) {
372    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
373      return true;
374
375    TV = Result.getLimitedValue(64);
376    if ((TV > 63) || (mask & (1ULL << TV)) == 0)
377      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
378        << TheCall->getArg(ImmArg)->getSourceRange();
379  }
380
381  if (PtrArgNum >= 0) {
382    // Check that pointer arguments have the specified type.
383    Expr *Arg = TheCall->getArg(PtrArgNum);
384    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
385      Arg = ICE->getSubExpr();
386    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
387    QualType RHSTy = RHS.get()->getType();
388    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
389    if (HasConstPtr)
390      EltTy = EltTy.withConst();
391    QualType LHSTy = Context.getPointerType(EltTy);
392    AssignConvertType ConvTy;
393    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
394    if (RHS.isInvalid())
395      return true;
396    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
397                                 RHS.get(), AA_Assigning))
398      return true;
399  }
400
401  // For NEON intrinsics which take an immediate value as part of the
402  // instruction, range check them here.
403  unsigned i = 0, l = 0, u = 0;
404  switch (BuiltinID) {
405  default: return false;
406  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
407  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
408  case ARM::BI__builtin_arm_vcvtr_f:
409  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
410#define GET_NEON_IMMEDIATE_CHECK
411#include "clang/Basic/arm_neon.inc"
412#undef GET_NEON_IMMEDIATE_CHECK
413  };
414
415  // We can't check the value of a dependent argument.
416  if (TheCall->getArg(i)->isTypeDependent() ||
417      TheCall->getArg(i)->isValueDependent())
418    return false;
419
420  // Check that the immediate argument is actually a constant.
421  if (SemaBuiltinConstantArg(TheCall, i, Result))
422    return true;
423
424  // Range check against the upper/lower values for this isntruction.
425  unsigned Val = Result.getZExtValue();
426  if (Val < l || Val > (u + l))
427    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
428      << l << u+l << TheCall->getArg(i)->getSourceRange();
429
430  // FIXME: VFP Intrinsics should error if VFP not present.
431  return false;
432}
433
434bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
435  unsigned i = 0, l = 0, u = 0;
436  switch (BuiltinID) {
437  default: return false;
438  case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
439  case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
440  case Mips::BI__builtin_mips_append: i = 2; l = 0; u = 31; break;
441  case Mips::BI__builtin_mips_balign: i = 2; l = 0; u = 3; break;
442  case Mips::BI__builtin_mips_precr_sra_ph_w: i = 2; l = 0; u = 31; break;
443  case Mips::BI__builtin_mips_precr_sra_r_ph_w: i = 2; l = 0; u = 31; break;
444  case Mips::BI__builtin_mips_prepend: i = 2; l = 0; u = 31; break;
445  };
446
447  // We can't check the value of a dependent argument.
448  if (TheCall->getArg(i)->isTypeDependent() ||
449      TheCall->getArg(i)->isValueDependent())
450    return false;
451
452  // Check that the immediate argument is actually a constant.
453  llvm::APSInt Result;
454  if (SemaBuiltinConstantArg(TheCall, i, Result))
455    return true;
456
457  // Range check against the upper/lower values for this instruction.
458  unsigned Val = Result.getZExtValue();
459  if (Val < l || Val > u)
460    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
461      << l << u << TheCall->getArg(i)->getSourceRange();
462
463  return false;
464}
465
466/// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
467/// parameter with the FormatAttr's correct format_idx and firstDataArg.
468/// Returns true when the format fits the function and the FormatStringInfo has
469/// been populated.
470bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
471                               FormatStringInfo *FSI) {
472  FSI->HasVAListArg = Format->getFirstArg() == 0;
473  FSI->FormatIdx = Format->getFormatIdx() - 1;
474  FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
475
476  // The way the format attribute works in GCC, the implicit this argument
477  // of member functions is counted. However, it doesn't appear in our own
478  // lists, so decrement format_idx in that case.
479  if (IsCXXMember) {
480    if(FSI->FormatIdx == 0)
481      return false;
482    --FSI->FormatIdx;
483    if (FSI->FirstDataArg != 0)
484      --FSI->FirstDataArg;
485  }
486  return true;
487}
488
489/// Handles the checks for format strings, non-POD arguments to vararg
490/// functions, and NULL arguments passed to non-NULL parameters.
491void Sema::checkCall(NamedDecl *FDecl, Expr **Args,
492                     unsigned NumArgs,
493                     unsigned NumProtoArgs,
494                     bool IsMemberFunction,
495                     SourceLocation Loc,
496                     SourceRange Range,
497                     VariadicCallType CallType) {
498  if (CurContext->isDependentContext())
499    return;
500
501  // Printf and scanf checking.
502  bool HandledFormatString = false;
503  for (specific_attr_iterator<FormatAttr>
504         I = FDecl->specific_attr_begin<FormatAttr>(),
505         E = FDecl->specific_attr_end<FormatAttr>(); I != E ; ++I)
506    if (CheckFormatArguments(*I, Args, NumArgs, IsMemberFunction, CallType,
507                             Loc, Range))
508        HandledFormatString = true;
509
510  // Refuse POD arguments that weren't caught by the format string
511  // checks above.
512  if (!HandledFormatString && CallType != VariadicDoesNotApply)
513    for (unsigned ArgIdx = NumProtoArgs; ArgIdx < NumArgs; ++ArgIdx) {
514      // Args[ArgIdx] can be null in malformed code.
515      if (Expr *Arg = Args[ArgIdx])
516        variadicArgumentPODCheck(Arg, CallType);
517    }
518
519  for (specific_attr_iterator<NonNullAttr>
520         I = FDecl->specific_attr_begin<NonNullAttr>(),
521         E = FDecl->specific_attr_end<NonNullAttr>(); I != E; ++I)
522    CheckNonNullArguments(*I, Args, Loc);
523
524  // Type safety checking.
525  for (specific_attr_iterator<ArgumentWithTypeTagAttr>
526         i = FDecl->specific_attr_begin<ArgumentWithTypeTagAttr>(),
527         e = FDecl->specific_attr_end<ArgumentWithTypeTagAttr>(); i != e; ++i) {
528    CheckArgumentWithTypeTag(*i, Args);
529  }
530}
531
532/// CheckConstructorCall - Check a constructor call for correctness and safety
533/// properties not enforced by the C type system.
534void Sema::CheckConstructorCall(FunctionDecl *FDecl, Expr **Args,
535                                unsigned NumArgs,
536                                const FunctionProtoType *Proto,
537                                SourceLocation Loc) {
538  VariadicCallType CallType =
539    Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
540  checkCall(FDecl, Args, NumArgs, Proto->getNumArgs(),
541            /*IsMemberFunction=*/true, Loc, SourceRange(), CallType);
542}
543
544/// CheckFunctionCall - Check a direct function call for various correctness
545/// and safety properties not strictly enforced by the C type system.
546bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
547                             const FunctionProtoType *Proto) {
548  bool IsMemberOperatorCall = isa<CXXOperatorCallExpr>(TheCall) &&
549                              isa<CXXMethodDecl>(FDecl);
550  bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall) ||
551                          IsMemberOperatorCall;
552  VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
553                                                  TheCall->getCallee());
554  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
555  Expr** Args = TheCall->getArgs();
556  unsigned NumArgs = TheCall->getNumArgs();
557  if (IsMemberOperatorCall) {
558    // If this is a call to a member operator, hide the first argument
559    // from checkCall.
560    // FIXME: Our choice of AST representation here is less than ideal.
561    ++Args;
562    --NumArgs;
563  }
564  checkCall(FDecl, Args, NumArgs, NumProtoArgs,
565            IsMemberFunction, TheCall->getRParenLoc(),
566            TheCall->getCallee()->getSourceRange(), CallType);
567
568  IdentifierInfo *FnInfo = FDecl->getIdentifier();
569  // None of the checks below are needed for functions that don't have
570  // simple names (e.g., C++ conversion functions).
571  if (!FnInfo)
572    return false;
573
574  unsigned CMId = FDecl->getMemoryFunctionKind();
575  if (CMId == 0)
576    return false;
577
578  // Handle memory setting and copying functions.
579  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
580    CheckStrlcpycatArguments(TheCall, FnInfo);
581  else if (CMId == Builtin::BIstrncat)
582    CheckStrncatArguments(TheCall, FnInfo);
583  else
584    CheckMemaccessArguments(TheCall, CMId, FnInfo);
585
586  return false;
587}
588
589bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
590                               Expr **Args, unsigned NumArgs) {
591  VariadicCallType CallType =
592      Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
593
594  checkCall(Method, Args, NumArgs, Method->param_size(),
595            /*IsMemberFunction=*/false,
596            lbrac, Method->getSourceRange(), CallType);
597
598  return false;
599}
600
601bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall,
602                          const FunctionProtoType *Proto) {
603  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
604  if (!V)
605    return false;
606
607  QualType Ty = V->getType();
608  if (!Ty->isBlockPointerType())
609    return false;
610
611  VariadicCallType CallType =
612      Proto && Proto->isVariadic() ? VariadicBlock : VariadicDoesNotApply ;
613  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
614
615  checkCall(NDecl, TheCall->getArgs(), TheCall->getNumArgs(),
616            NumProtoArgs, /*IsMemberFunction=*/false,
617            TheCall->getRParenLoc(),
618            TheCall->getCallee()->getSourceRange(), CallType);
619
620  return false;
621}
622
623ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
624                                         AtomicExpr::AtomicOp Op) {
625  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
626  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
627
628  // All these operations take one of the following forms:
629  enum {
630    // C    __c11_atomic_init(A *, C)
631    Init,
632    // C    __c11_atomic_load(A *, int)
633    Load,
634    // void __atomic_load(A *, CP, int)
635    Copy,
636    // C    __c11_atomic_add(A *, M, int)
637    Arithmetic,
638    // C    __atomic_exchange_n(A *, CP, int)
639    Xchg,
640    // void __atomic_exchange(A *, C *, CP, int)
641    GNUXchg,
642    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
643    C11CmpXchg,
644    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
645    GNUCmpXchg
646  } Form = Init;
647  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
648  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
649  // where:
650  //   C is an appropriate type,
651  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
652  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
653  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
654  //   the int parameters are for orderings.
655
656  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
657         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
658         && "need to update code for modified C11 atomics");
659  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
660               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
661  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
662             Op == AtomicExpr::AO__atomic_store_n ||
663             Op == AtomicExpr::AO__atomic_exchange_n ||
664             Op == AtomicExpr::AO__atomic_compare_exchange_n;
665  bool IsAddSub = false;
666
667  switch (Op) {
668  case AtomicExpr::AO__c11_atomic_init:
669    Form = Init;
670    break;
671
672  case AtomicExpr::AO__c11_atomic_load:
673  case AtomicExpr::AO__atomic_load_n:
674    Form = Load;
675    break;
676
677  case AtomicExpr::AO__c11_atomic_store:
678  case AtomicExpr::AO__atomic_load:
679  case AtomicExpr::AO__atomic_store:
680  case AtomicExpr::AO__atomic_store_n:
681    Form = Copy;
682    break;
683
684  case AtomicExpr::AO__c11_atomic_fetch_add:
685  case AtomicExpr::AO__c11_atomic_fetch_sub:
686  case AtomicExpr::AO__atomic_fetch_add:
687  case AtomicExpr::AO__atomic_fetch_sub:
688  case AtomicExpr::AO__atomic_add_fetch:
689  case AtomicExpr::AO__atomic_sub_fetch:
690    IsAddSub = true;
691    // Fall through.
692  case AtomicExpr::AO__c11_atomic_fetch_and:
693  case AtomicExpr::AO__c11_atomic_fetch_or:
694  case AtomicExpr::AO__c11_atomic_fetch_xor:
695  case AtomicExpr::AO__atomic_fetch_and:
696  case AtomicExpr::AO__atomic_fetch_or:
697  case AtomicExpr::AO__atomic_fetch_xor:
698  case AtomicExpr::AO__atomic_fetch_nand:
699  case AtomicExpr::AO__atomic_and_fetch:
700  case AtomicExpr::AO__atomic_or_fetch:
701  case AtomicExpr::AO__atomic_xor_fetch:
702  case AtomicExpr::AO__atomic_nand_fetch:
703    Form = Arithmetic;
704    break;
705
706  case AtomicExpr::AO__c11_atomic_exchange:
707  case AtomicExpr::AO__atomic_exchange_n:
708    Form = Xchg;
709    break;
710
711  case AtomicExpr::AO__atomic_exchange:
712    Form = GNUXchg;
713    break;
714
715  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
716  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
717    Form = C11CmpXchg;
718    break;
719
720  case AtomicExpr::AO__atomic_compare_exchange:
721  case AtomicExpr::AO__atomic_compare_exchange_n:
722    Form = GNUCmpXchg;
723    break;
724  }
725
726  // Check we have the right number of arguments.
727  if (TheCall->getNumArgs() < NumArgs[Form]) {
728    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
729      << 0 << NumArgs[Form] << TheCall->getNumArgs()
730      << TheCall->getCallee()->getSourceRange();
731    return ExprError();
732  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
733    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
734         diag::err_typecheck_call_too_many_args)
735      << 0 << NumArgs[Form] << TheCall->getNumArgs()
736      << TheCall->getCallee()->getSourceRange();
737    return ExprError();
738  }
739
740  // Inspect the first argument of the atomic operation.
741  Expr *Ptr = TheCall->getArg(0);
742  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
743  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
744  if (!pointerType) {
745    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
746      << Ptr->getType() << Ptr->getSourceRange();
747    return ExprError();
748  }
749
750  // For a __c11 builtin, this should be a pointer to an _Atomic type.
751  QualType AtomTy = pointerType->getPointeeType(); // 'A'
752  QualType ValType = AtomTy; // 'C'
753  if (IsC11) {
754    if (!AtomTy->isAtomicType()) {
755      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
756        << Ptr->getType() << Ptr->getSourceRange();
757      return ExprError();
758    }
759    if (AtomTy.isConstQualified()) {
760      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
761        << Ptr->getType() << Ptr->getSourceRange();
762      return ExprError();
763    }
764    ValType = AtomTy->getAs<AtomicType>()->getValueType();
765  }
766
767  // For an arithmetic operation, the implied arithmetic must be well-formed.
768  if (Form == Arithmetic) {
769    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
770    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
771      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
772        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
773      return ExprError();
774    }
775    if (!IsAddSub && !ValType->isIntegerType()) {
776      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
777        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
778      return ExprError();
779    }
780  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
781    // For __atomic_*_n operations, the value type must be a scalar integral or
782    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
783    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
784      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
785    return ExprError();
786  }
787
788  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
789    // For GNU atomics, require a trivially-copyable type. This is not part of
790    // the GNU atomics specification, but we enforce it for sanity.
791    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
792      << Ptr->getType() << Ptr->getSourceRange();
793    return ExprError();
794  }
795
796  // FIXME: For any builtin other than a load, the ValType must not be
797  // const-qualified.
798
799  switch (ValType.getObjCLifetime()) {
800  case Qualifiers::OCL_None:
801  case Qualifiers::OCL_ExplicitNone:
802    // okay
803    break;
804
805  case Qualifiers::OCL_Weak:
806  case Qualifiers::OCL_Strong:
807  case Qualifiers::OCL_Autoreleasing:
808    // FIXME: Can this happen? By this point, ValType should be known
809    // to be trivially copyable.
810    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
811      << ValType << Ptr->getSourceRange();
812    return ExprError();
813  }
814
815  QualType ResultType = ValType;
816  if (Form == Copy || Form == GNUXchg || Form == Init)
817    ResultType = Context.VoidTy;
818  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
819    ResultType = Context.BoolTy;
820
821  // The type of a parameter passed 'by value'. In the GNU atomics, such
822  // arguments are actually passed as pointers.
823  QualType ByValType = ValType; // 'CP'
824  if (!IsC11 && !IsN)
825    ByValType = Ptr->getType();
826
827  // The first argument --- the pointer --- has a fixed type; we
828  // deduce the types of the rest of the arguments accordingly.  Walk
829  // the remaining arguments, converting them to the deduced value type.
830  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
831    QualType Ty;
832    if (i < NumVals[Form] + 1) {
833      switch (i) {
834      case 1:
835        // The second argument is the non-atomic operand. For arithmetic, this
836        // is always passed by value, and for a compare_exchange it is always
837        // passed by address. For the rest, GNU uses by-address and C11 uses
838        // by-value.
839        assert(Form != Load);
840        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
841          Ty = ValType;
842        else if (Form == Copy || Form == Xchg)
843          Ty = ByValType;
844        else if (Form == Arithmetic)
845          Ty = Context.getPointerDiffType();
846        else
847          Ty = Context.getPointerType(ValType.getUnqualifiedType());
848        break;
849      case 2:
850        // The third argument to compare_exchange / GNU exchange is a
851        // (pointer to a) desired value.
852        Ty = ByValType;
853        break;
854      case 3:
855        // The fourth argument to GNU compare_exchange is a 'weak' flag.
856        Ty = Context.BoolTy;
857        break;
858      }
859    } else {
860      // The order(s) are always converted to int.
861      Ty = Context.IntTy;
862    }
863
864    InitializedEntity Entity =
865        InitializedEntity::InitializeParameter(Context, Ty, false);
866    ExprResult Arg = TheCall->getArg(i);
867    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
868    if (Arg.isInvalid())
869      return true;
870    TheCall->setArg(i, Arg.get());
871  }
872
873  // Permute the arguments into a 'consistent' order.
874  SmallVector<Expr*, 5> SubExprs;
875  SubExprs.push_back(Ptr);
876  switch (Form) {
877  case Init:
878    // Note, AtomicExpr::getVal1() has a special case for this atomic.
879    SubExprs.push_back(TheCall->getArg(1)); // Val1
880    break;
881  case Load:
882    SubExprs.push_back(TheCall->getArg(1)); // Order
883    break;
884  case Copy:
885  case Arithmetic:
886  case Xchg:
887    SubExprs.push_back(TheCall->getArg(2)); // Order
888    SubExprs.push_back(TheCall->getArg(1)); // Val1
889    break;
890  case GNUXchg:
891    // Note, AtomicExpr::getVal2() has a special case for this atomic.
892    SubExprs.push_back(TheCall->getArg(3)); // Order
893    SubExprs.push_back(TheCall->getArg(1)); // Val1
894    SubExprs.push_back(TheCall->getArg(2)); // Val2
895    break;
896  case C11CmpXchg:
897    SubExprs.push_back(TheCall->getArg(3)); // Order
898    SubExprs.push_back(TheCall->getArg(1)); // Val1
899    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
900    SubExprs.push_back(TheCall->getArg(2)); // Val2
901    break;
902  case GNUCmpXchg:
903    SubExprs.push_back(TheCall->getArg(4)); // Order
904    SubExprs.push_back(TheCall->getArg(1)); // Val1
905    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
906    SubExprs.push_back(TheCall->getArg(2)); // Val2
907    SubExprs.push_back(TheCall->getArg(3)); // Weak
908    break;
909  }
910
911  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
912                                        SubExprs, ResultType, Op,
913                                        TheCall->getRParenLoc()));
914}
915
916
917/// checkBuiltinArgument - Given a call to a builtin function, perform
918/// normal type-checking on the given argument, updating the call in
919/// place.  This is useful when a builtin function requires custom
920/// type-checking for some of its arguments but not necessarily all of
921/// them.
922///
923/// Returns true on error.
924static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
925  FunctionDecl *Fn = E->getDirectCallee();
926  assert(Fn && "builtin call without direct callee!");
927
928  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
929  InitializedEntity Entity =
930    InitializedEntity::InitializeParameter(S.Context, Param);
931
932  ExprResult Arg = E->getArg(0);
933  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
934  if (Arg.isInvalid())
935    return true;
936
937  E->setArg(ArgIndex, Arg.take());
938  return false;
939}
940
941/// SemaBuiltinAtomicOverloaded - We have a call to a function like
942/// __sync_fetch_and_add, which is an overloaded function based on the pointer
943/// type of its first argument.  The main ActOnCallExpr routines have already
944/// promoted the types of arguments because all of these calls are prototyped as
945/// void(...).
946///
947/// This function goes through and does final semantic checking for these
948/// builtins,
949ExprResult
950Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
951  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
952  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
953  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
954
955  // Ensure that we have at least one argument to do type inference from.
956  if (TheCall->getNumArgs() < 1) {
957    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
958      << 0 << 1 << TheCall->getNumArgs()
959      << TheCall->getCallee()->getSourceRange();
960    return ExprError();
961  }
962
963  // Inspect the first argument of the atomic builtin.  This should always be
964  // a pointer type, whose element is an integral scalar or pointer type.
965  // Because it is a pointer type, we don't have to worry about any implicit
966  // casts here.
967  // FIXME: We don't allow floating point scalars as input.
968  Expr *FirstArg = TheCall->getArg(0);
969  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
970  if (FirstArgResult.isInvalid())
971    return ExprError();
972  FirstArg = FirstArgResult.take();
973  TheCall->setArg(0, FirstArg);
974
975  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
976  if (!pointerType) {
977    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
978      << FirstArg->getType() << FirstArg->getSourceRange();
979    return ExprError();
980  }
981
982  QualType ValType = pointerType->getPointeeType();
983  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
984      !ValType->isBlockPointerType()) {
985    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
986      << FirstArg->getType() << FirstArg->getSourceRange();
987    return ExprError();
988  }
989
990  switch (ValType.getObjCLifetime()) {
991  case Qualifiers::OCL_None:
992  case Qualifiers::OCL_ExplicitNone:
993    // okay
994    break;
995
996  case Qualifiers::OCL_Weak:
997  case Qualifiers::OCL_Strong:
998  case Qualifiers::OCL_Autoreleasing:
999    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1000      << ValType << FirstArg->getSourceRange();
1001    return ExprError();
1002  }
1003
1004  // Strip any qualifiers off ValType.
1005  ValType = ValType.getUnqualifiedType();
1006
1007  // The majority of builtins return a value, but a few have special return
1008  // types, so allow them to override appropriately below.
1009  QualType ResultType = ValType;
1010
1011  // We need to figure out which concrete builtin this maps onto.  For example,
1012  // __sync_fetch_and_add with a 2 byte object turns into
1013  // __sync_fetch_and_add_2.
1014#define BUILTIN_ROW(x) \
1015  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
1016    Builtin::BI##x##_8, Builtin::BI##x##_16 }
1017
1018  static const unsigned BuiltinIndices[][5] = {
1019    BUILTIN_ROW(__sync_fetch_and_add),
1020    BUILTIN_ROW(__sync_fetch_and_sub),
1021    BUILTIN_ROW(__sync_fetch_and_or),
1022    BUILTIN_ROW(__sync_fetch_and_and),
1023    BUILTIN_ROW(__sync_fetch_and_xor),
1024
1025    BUILTIN_ROW(__sync_add_and_fetch),
1026    BUILTIN_ROW(__sync_sub_and_fetch),
1027    BUILTIN_ROW(__sync_and_and_fetch),
1028    BUILTIN_ROW(__sync_or_and_fetch),
1029    BUILTIN_ROW(__sync_xor_and_fetch),
1030
1031    BUILTIN_ROW(__sync_val_compare_and_swap),
1032    BUILTIN_ROW(__sync_bool_compare_and_swap),
1033    BUILTIN_ROW(__sync_lock_test_and_set),
1034    BUILTIN_ROW(__sync_lock_release),
1035    BUILTIN_ROW(__sync_swap)
1036  };
1037#undef BUILTIN_ROW
1038
1039  // Determine the index of the size.
1040  unsigned SizeIndex;
1041  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1042  case 1: SizeIndex = 0; break;
1043  case 2: SizeIndex = 1; break;
1044  case 4: SizeIndex = 2; break;
1045  case 8: SizeIndex = 3; break;
1046  case 16: SizeIndex = 4; break;
1047  default:
1048    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1049      << FirstArg->getType() << FirstArg->getSourceRange();
1050    return ExprError();
1051  }
1052
1053  // Each of these builtins has one pointer argument, followed by some number of
1054  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1055  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1056  // as the number of fixed args.
1057  unsigned BuiltinID = FDecl->getBuiltinID();
1058  unsigned BuiltinIndex, NumFixed = 1;
1059  switch (BuiltinID) {
1060  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1061  case Builtin::BI__sync_fetch_and_add:
1062  case Builtin::BI__sync_fetch_and_add_1:
1063  case Builtin::BI__sync_fetch_and_add_2:
1064  case Builtin::BI__sync_fetch_and_add_4:
1065  case Builtin::BI__sync_fetch_and_add_8:
1066  case Builtin::BI__sync_fetch_and_add_16:
1067    BuiltinIndex = 0;
1068    break;
1069
1070  case Builtin::BI__sync_fetch_and_sub:
1071  case Builtin::BI__sync_fetch_and_sub_1:
1072  case Builtin::BI__sync_fetch_and_sub_2:
1073  case Builtin::BI__sync_fetch_and_sub_4:
1074  case Builtin::BI__sync_fetch_and_sub_8:
1075  case Builtin::BI__sync_fetch_and_sub_16:
1076    BuiltinIndex = 1;
1077    break;
1078
1079  case Builtin::BI__sync_fetch_and_or:
1080  case Builtin::BI__sync_fetch_and_or_1:
1081  case Builtin::BI__sync_fetch_and_or_2:
1082  case Builtin::BI__sync_fetch_and_or_4:
1083  case Builtin::BI__sync_fetch_and_or_8:
1084  case Builtin::BI__sync_fetch_and_or_16:
1085    BuiltinIndex = 2;
1086    break;
1087
1088  case Builtin::BI__sync_fetch_and_and:
1089  case Builtin::BI__sync_fetch_and_and_1:
1090  case Builtin::BI__sync_fetch_and_and_2:
1091  case Builtin::BI__sync_fetch_and_and_4:
1092  case Builtin::BI__sync_fetch_and_and_8:
1093  case Builtin::BI__sync_fetch_and_and_16:
1094    BuiltinIndex = 3;
1095    break;
1096
1097  case Builtin::BI__sync_fetch_and_xor:
1098  case Builtin::BI__sync_fetch_and_xor_1:
1099  case Builtin::BI__sync_fetch_and_xor_2:
1100  case Builtin::BI__sync_fetch_and_xor_4:
1101  case Builtin::BI__sync_fetch_and_xor_8:
1102  case Builtin::BI__sync_fetch_and_xor_16:
1103    BuiltinIndex = 4;
1104    break;
1105
1106  case Builtin::BI__sync_add_and_fetch:
1107  case Builtin::BI__sync_add_and_fetch_1:
1108  case Builtin::BI__sync_add_and_fetch_2:
1109  case Builtin::BI__sync_add_and_fetch_4:
1110  case Builtin::BI__sync_add_and_fetch_8:
1111  case Builtin::BI__sync_add_and_fetch_16:
1112    BuiltinIndex = 5;
1113    break;
1114
1115  case Builtin::BI__sync_sub_and_fetch:
1116  case Builtin::BI__sync_sub_and_fetch_1:
1117  case Builtin::BI__sync_sub_and_fetch_2:
1118  case Builtin::BI__sync_sub_and_fetch_4:
1119  case Builtin::BI__sync_sub_and_fetch_8:
1120  case Builtin::BI__sync_sub_and_fetch_16:
1121    BuiltinIndex = 6;
1122    break;
1123
1124  case Builtin::BI__sync_and_and_fetch:
1125  case Builtin::BI__sync_and_and_fetch_1:
1126  case Builtin::BI__sync_and_and_fetch_2:
1127  case Builtin::BI__sync_and_and_fetch_4:
1128  case Builtin::BI__sync_and_and_fetch_8:
1129  case Builtin::BI__sync_and_and_fetch_16:
1130    BuiltinIndex = 7;
1131    break;
1132
1133  case Builtin::BI__sync_or_and_fetch:
1134  case Builtin::BI__sync_or_and_fetch_1:
1135  case Builtin::BI__sync_or_and_fetch_2:
1136  case Builtin::BI__sync_or_and_fetch_4:
1137  case Builtin::BI__sync_or_and_fetch_8:
1138  case Builtin::BI__sync_or_and_fetch_16:
1139    BuiltinIndex = 8;
1140    break;
1141
1142  case Builtin::BI__sync_xor_and_fetch:
1143  case Builtin::BI__sync_xor_and_fetch_1:
1144  case Builtin::BI__sync_xor_and_fetch_2:
1145  case Builtin::BI__sync_xor_and_fetch_4:
1146  case Builtin::BI__sync_xor_and_fetch_8:
1147  case Builtin::BI__sync_xor_and_fetch_16:
1148    BuiltinIndex = 9;
1149    break;
1150
1151  case Builtin::BI__sync_val_compare_and_swap:
1152  case Builtin::BI__sync_val_compare_and_swap_1:
1153  case Builtin::BI__sync_val_compare_and_swap_2:
1154  case Builtin::BI__sync_val_compare_and_swap_4:
1155  case Builtin::BI__sync_val_compare_and_swap_8:
1156  case Builtin::BI__sync_val_compare_and_swap_16:
1157    BuiltinIndex = 10;
1158    NumFixed = 2;
1159    break;
1160
1161  case Builtin::BI__sync_bool_compare_and_swap:
1162  case Builtin::BI__sync_bool_compare_and_swap_1:
1163  case Builtin::BI__sync_bool_compare_and_swap_2:
1164  case Builtin::BI__sync_bool_compare_and_swap_4:
1165  case Builtin::BI__sync_bool_compare_and_swap_8:
1166  case Builtin::BI__sync_bool_compare_and_swap_16:
1167    BuiltinIndex = 11;
1168    NumFixed = 2;
1169    ResultType = Context.BoolTy;
1170    break;
1171
1172  case Builtin::BI__sync_lock_test_and_set:
1173  case Builtin::BI__sync_lock_test_and_set_1:
1174  case Builtin::BI__sync_lock_test_and_set_2:
1175  case Builtin::BI__sync_lock_test_and_set_4:
1176  case Builtin::BI__sync_lock_test_and_set_8:
1177  case Builtin::BI__sync_lock_test_and_set_16:
1178    BuiltinIndex = 12;
1179    break;
1180
1181  case Builtin::BI__sync_lock_release:
1182  case Builtin::BI__sync_lock_release_1:
1183  case Builtin::BI__sync_lock_release_2:
1184  case Builtin::BI__sync_lock_release_4:
1185  case Builtin::BI__sync_lock_release_8:
1186  case Builtin::BI__sync_lock_release_16:
1187    BuiltinIndex = 13;
1188    NumFixed = 0;
1189    ResultType = Context.VoidTy;
1190    break;
1191
1192  case Builtin::BI__sync_swap:
1193  case Builtin::BI__sync_swap_1:
1194  case Builtin::BI__sync_swap_2:
1195  case Builtin::BI__sync_swap_4:
1196  case Builtin::BI__sync_swap_8:
1197  case Builtin::BI__sync_swap_16:
1198    BuiltinIndex = 14;
1199    break;
1200  }
1201
1202  // Now that we know how many fixed arguments we expect, first check that we
1203  // have at least that many.
1204  if (TheCall->getNumArgs() < 1+NumFixed) {
1205    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1206      << 0 << 1+NumFixed << TheCall->getNumArgs()
1207      << TheCall->getCallee()->getSourceRange();
1208    return ExprError();
1209  }
1210
1211  // Get the decl for the concrete builtin from this, we can tell what the
1212  // concrete integer type we should convert to is.
1213  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1214  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1215  FunctionDecl *NewBuiltinDecl;
1216  if (NewBuiltinID == BuiltinID)
1217    NewBuiltinDecl = FDecl;
1218  else {
1219    // Perform builtin lookup to avoid redeclaring it.
1220    DeclarationName DN(&Context.Idents.get(NewBuiltinName));
1221    LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
1222    LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
1223    assert(Res.getFoundDecl());
1224    NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
1225    if (NewBuiltinDecl == 0)
1226      return ExprError();
1227  }
1228
1229  // The first argument --- the pointer --- has a fixed type; we
1230  // deduce the types of the rest of the arguments accordingly.  Walk
1231  // the remaining arguments, converting them to the deduced value type.
1232  for (unsigned i = 0; i != NumFixed; ++i) {
1233    ExprResult Arg = TheCall->getArg(i+1);
1234
1235    // GCC does an implicit conversion to the pointer or integer ValType.  This
1236    // can fail in some cases (1i -> int**), check for this error case now.
1237    // Initialize the argument.
1238    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1239                                                   ValType, /*consume*/ false);
1240    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1241    if (Arg.isInvalid())
1242      return ExprError();
1243
1244    // Okay, we have something that *can* be converted to the right type.  Check
1245    // to see if there is a potentially weird extension going on here.  This can
1246    // happen when you do an atomic operation on something like an char* and
1247    // pass in 42.  The 42 gets converted to char.  This is even more strange
1248    // for things like 45.123 -> char, etc.
1249    // FIXME: Do this check.
1250    TheCall->setArg(i+1, Arg.take());
1251  }
1252
1253  ASTContext& Context = this->getASTContext();
1254
1255  // Create a new DeclRefExpr to refer to the new decl.
1256  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1257      Context,
1258      DRE->getQualifierLoc(),
1259      SourceLocation(),
1260      NewBuiltinDecl,
1261      /*enclosing*/ false,
1262      DRE->getLocation(),
1263      Context.BuiltinFnTy,
1264      DRE->getValueKind());
1265
1266  // Set the callee in the CallExpr.
1267  // FIXME: This loses syntactic information.
1268  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
1269  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
1270                                              CK_BuiltinFnToFnPtr);
1271  TheCall->setCallee(PromotedCall.take());
1272
1273  // Change the result type of the call to match the original value type. This
1274  // is arbitrary, but the codegen for these builtins ins design to handle it
1275  // gracefully.
1276  TheCall->setType(ResultType);
1277
1278  return TheCallResult;
1279}
1280
1281/// CheckObjCString - Checks that the argument to the builtin
1282/// CFString constructor is correct
1283/// Note: It might also make sense to do the UTF-16 conversion here (would
1284/// simplify the backend).
1285bool Sema::CheckObjCString(Expr *Arg) {
1286  Arg = Arg->IgnoreParenCasts();
1287  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1288
1289  if (!Literal || !Literal->isAscii()) {
1290    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1291      << Arg->getSourceRange();
1292    return true;
1293  }
1294
1295  if (Literal->containsNonAsciiOrNull()) {
1296    StringRef String = Literal->getString();
1297    unsigned NumBytes = String.size();
1298    SmallVector<UTF16, 128> ToBuf(NumBytes);
1299    const UTF8 *FromPtr = (const UTF8 *)String.data();
1300    UTF16 *ToPtr = &ToBuf[0];
1301
1302    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1303                                                 &ToPtr, ToPtr + NumBytes,
1304                                                 strictConversion);
1305    // Check for conversion failure.
1306    if (Result != conversionOK)
1307      Diag(Arg->getLocStart(),
1308           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1309  }
1310  return false;
1311}
1312
1313/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1314/// Emit an error and return true on failure, return false on success.
1315bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1316  Expr *Fn = TheCall->getCallee();
1317  if (TheCall->getNumArgs() > 2) {
1318    Diag(TheCall->getArg(2)->getLocStart(),
1319         diag::err_typecheck_call_too_many_args)
1320      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1321      << Fn->getSourceRange()
1322      << SourceRange(TheCall->getArg(2)->getLocStart(),
1323                     (*(TheCall->arg_end()-1))->getLocEnd());
1324    return true;
1325  }
1326
1327  if (TheCall->getNumArgs() < 2) {
1328    return Diag(TheCall->getLocEnd(),
1329      diag::err_typecheck_call_too_few_args_at_least)
1330      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1331  }
1332
1333  // Type-check the first argument normally.
1334  if (checkBuiltinArgument(*this, TheCall, 0))
1335    return true;
1336
1337  // Determine whether the current function is variadic or not.
1338  BlockScopeInfo *CurBlock = getCurBlock();
1339  bool isVariadic;
1340  if (CurBlock)
1341    isVariadic = CurBlock->TheDecl->isVariadic();
1342  else if (FunctionDecl *FD = getCurFunctionDecl())
1343    isVariadic = FD->isVariadic();
1344  else
1345    isVariadic = getCurMethodDecl()->isVariadic();
1346
1347  if (!isVariadic) {
1348    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1349    return true;
1350  }
1351
1352  // Verify that the second argument to the builtin is the last argument of the
1353  // current function or method.
1354  bool SecondArgIsLastNamedArgument = false;
1355  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1356
1357  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1358    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1359      // FIXME: This isn't correct for methods (results in bogus warning).
1360      // Get the last formal in the current function.
1361      const ParmVarDecl *LastArg;
1362      if (CurBlock)
1363        LastArg = *(CurBlock->TheDecl->param_end()-1);
1364      else if (FunctionDecl *FD = getCurFunctionDecl())
1365        LastArg = *(FD->param_end()-1);
1366      else
1367        LastArg = *(getCurMethodDecl()->param_end()-1);
1368      SecondArgIsLastNamedArgument = PV == LastArg;
1369    }
1370  }
1371
1372  if (!SecondArgIsLastNamedArgument)
1373    Diag(TheCall->getArg(1)->getLocStart(),
1374         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1375  return false;
1376}
1377
1378/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1379/// friends.  This is declared to take (...), so we have to check everything.
1380bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1381  if (TheCall->getNumArgs() < 2)
1382    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1383      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1384  if (TheCall->getNumArgs() > 2)
1385    return Diag(TheCall->getArg(2)->getLocStart(),
1386                diag::err_typecheck_call_too_many_args)
1387      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1388      << SourceRange(TheCall->getArg(2)->getLocStart(),
1389                     (*(TheCall->arg_end()-1))->getLocEnd());
1390
1391  ExprResult OrigArg0 = TheCall->getArg(0);
1392  ExprResult OrigArg1 = TheCall->getArg(1);
1393
1394  // Do standard promotions between the two arguments, returning their common
1395  // type.
1396  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1397  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1398    return true;
1399
1400  // Make sure any conversions are pushed back into the call; this is
1401  // type safe since unordered compare builtins are declared as "_Bool
1402  // foo(...)".
1403  TheCall->setArg(0, OrigArg0.get());
1404  TheCall->setArg(1, OrigArg1.get());
1405
1406  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1407    return false;
1408
1409  // If the common type isn't a real floating type, then the arguments were
1410  // invalid for this operation.
1411  if (Res.isNull() || !Res->isRealFloatingType())
1412    return Diag(OrigArg0.get()->getLocStart(),
1413                diag::err_typecheck_call_invalid_ordered_compare)
1414      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1415      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1416
1417  return false;
1418}
1419
1420/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1421/// __builtin_isnan and friends.  This is declared to take (...), so we have
1422/// to check everything. We expect the last argument to be a floating point
1423/// value.
1424bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1425  if (TheCall->getNumArgs() < NumArgs)
1426    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1427      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1428  if (TheCall->getNumArgs() > NumArgs)
1429    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1430                diag::err_typecheck_call_too_many_args)
1431      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1432      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1433                     (*(TheCall->arg_end()-1))->getLocEnd());
1434
1435  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1436
1437  if (OrigArg->isTypeDependent())
1438    return false;
1439
1440  // This operation requires a non-_Complex floating-point number.
1441  if (!OrigArg->getType()->isRealFloatingType())
1442    return Diag(OrigArg->getLocStart(),
1443                diag::err_typecheck_call_invalid_unary_fp)
1444      << OrigArg->getType() << OrigArg->getSourceRange();
1445
1446  // If this is an implicit conversion from float -> double, remove it.
1447  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1448    Expr *CastArg = Cast->getSubExpr();
1449    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1450      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1451             "promotion from float to double is the only expected cast here");
1452      Cast->setSubExpr(0);
1453      TheCall->setArg(NumArgs-1, CastArg);
1454    }
1455  }
1456
1457  return false;
1458}
1459
1460/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1461// This is declared to take (...), so we have to check everything.
1462ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1463  if (TheCall->getNumArgs() < 2)
1464    return ExprError(Diag(TheCall->getLocEnd(),
1465                          diag::err_typecheck_call_too_few_args_at_least)
1466      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1467      << TheCall->getSourceRange());
1468
1469  // Determine which of the following types of shufflevector we're checking:
1470  // 1) unary, vector mask: (lhs, mask)
1471  // 2) binary, vector mask: (lhs, rhs, mask)
1472  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1473  QualType resType = TheCall->getArg(0)->getType();
1474  unsigned numElements = 0;
1475
1476  if (!TheCall->getArg(0)->isTypeDependent() &&
1477      !TheCall->getArg(1)->isTypeDependent()) {
1478    QualType LHSType = TheCall->getArg(0)->getType();
1479    QualType RHSType = TheCall->getArg(1)->getType();
1480
1481    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1482      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1483        << SourceRange(TheCall->getArg(0)->getLocStart(),
1484                       TheCall->getArg(1)->getLocEnd());
1485      return ExprError();
1486    }
1487
1488    numElements = LHSType->getAs<VectorType>()->getNumElements();
1489    unsigned numResElements = TheCall->getNumArgs() - 2;
1490
1491    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1492    // with mask.  If so, verify that RHS is an integer vector type with the
1493    // same number of elts as lhs.
1494    if (TheCall->getNumArgs() == 2) {
1495      if (!RHSType->hasIntegerRepresentation() ||
1496          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1497        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1498          << SourceRange(TheCall->getArg(1)->getLocStart(),
1499                         TheCall->getArg(1)->getLocEnd());
1500      numResElements = numElements;
1501    }
1502    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1503      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1504        << SourceRange(TheCall->getArg(0)->getLocStart(),
1505                       TheCall->getArg(1)->getLocEnd());
1506      return ExprError();
1507    } else if (numElements != numResElements) {
1508      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1509      resType = Context.getVectorType(eltType, numResElements,
1510                                      VectorType::GenericVector);
1511    }
1512  }
1513
1514  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1515    if (TheCall->getArg(i)->isTypeDependent() ||
1516        TheCall->getArg(i)->isValueDependent())
1517      continue;
1518
1519    llvm::APSInt Result(32);
1520    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1521      return ExprError(Diag(TheCall->getLocStart(),
1522                  diag::err_shufflevector_nonconstant_argument)
1523                << TheCall->getArg(i)->getSourceRange());
1524
1525    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1526      return ExprError(Diag(TheCall->getLocStart(),
1527                  diag::err_shufflevector_argument_too_large)
1528               << TheCall->getArg(i)->getSourceRange());
1529  }
1530
1531  SmallVector<Expr*, 32> exprs;
1532
1533  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1534    exprs.push_back(TheCall->getArg(i));
1535    TheCall->setArg(i, 0);
1536  }
1537
1538  return Owned(new (Context) ShuffleVectorExpr(Context, exprs, resType,
1539                                            TheCall->getCallee()->getLocStart(),
1540                                            TheCall->getRParenLoc()));
1541}
1542
1543/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1544// This is declared to take (const void*, ...) and can take two
1545// optional constant int args.
1546bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1547  unsigned NumArgs = TheCall->getNumArgs();
1548
1549  if (NumArgs > 3)
1550    return Diag(TheCall->getLocEnd(),
1551             diag::err_typecheck_call_too_many_args_at_most)
1552             << 0 /*function call*/ << 3 << NumArgs
1553             << TheCall->getSourceRange();
1554
1555  // Argument 0 is checked for us and the remaining arguments must be
1556  // constant integers.
1557  for (unsigned i = 1; i != NumArgs; ++i) {
1558    Expr *Arg = TheCall->getArg(i);
1559
1560    // We can't check the value of a dependent argument.
1561    if (Arg->isTypeDependent() || Arg->isValueDependent())
1562      continue;
1563
1564    llvm::APSInt Result;
1565    if (SemaBuiltinConstantArg(TheCall, i, Result))
1566      return true;
1567
1568    // FIXME: gcc issues a warning and rewrites these to 0. These
1569    // seems especially odd for the third argument since the default
1570    // is 3.
1571    if (i == 1) {
1572      if (Result.getLimitedValue() > 1)
1573        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1574             << "0" << "1" << Arg->getSourceRange();
1575    } else {
1576      if (Result.getLimitedValue() > 3)
1577        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1578            << "0" << "3" << Arg->getSourceRange();
1579    }
1580  }
1581
1582  return false;
1583}
1584
1585/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1586/// TheCall is a constant expression.
1587bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1588                                  llvm::APSInt &Result) {
1589  Expr *Arg = TheCall->getArg(ArgNum);
1590  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1591  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1592
1593  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1594
1595  if (!Arg->isIntegerConstantExpr(Result, Context))
1596    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1597                << FDecl->getDeclName() <<  Arg->getSourceRange();
1598
1599  return false;
1600}
1601
1602/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1603/// int type). This simply type checks that type is one of the defined
1604/// constants (0-3).
1605// For compatibility check 0-3, llvm only handles 0 and 2.
1606bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1607  llvm::APSInt Result;
1608
1609  // We can't check the value of a dependent argument.
1610  if (TheCall->getArg(1)->isTypeDependent() ||
1611      TheCall->getArg(1)->isValueDependent())
1612    return false;
1613
1614  // Check constant-ness first.
1615  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1616    return true;
1617
1618  Expr *Arg = TheCall->getArg(1);
1619  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1620    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1621             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1622  }
1623
1624  return false;
1625}
1626
1627/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1628/// This checks that val is a constant 1.
1629bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1630  Expr *Arg = TheCall->getArg(1);
1631  llvm::APSInt Result;
1632
1633  // TODO: This is less than ideal. Overload this to take a value.
1634  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1635    return true;
1636
1637  if (Result != 1)
1638    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1639             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1640
1641  return false;
1642}
1643
1644// Determine if an expression is a string literal or constant string.
1645// If this function returns false on the arguments to a function expecting a
1646// format string, we will usually need to emit a warning.
1647// True string literals are then checked by CheckFormatString.
1648Sema::StringLiteralCheckType
1649Sema::checkFormatStringExpr(const Expr *E, Expr **Args,
1650                            unsigned NumArgs, bool HasVAListArg,
1651                            unsigned format_idx, unsigned firstDataArg,
1652                            FormatStringType Type, VariadicCallType CallType,
1653                            bool inFunctionCall) {
1654 tryAgain:
1655  if (E->isTypeDependent() || E->isValueDependent())
1656    return SLCT_NotALiteral;
1657
1658  E = E->IgnoreParenCasts();
1659
1660  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1661    // Technically -Wformat-nonliteral does not warn about this case.
1662    // The behavior of printf and friends in this case is implementation
1663    // dependent.  Ideally if the format string cannot be null then
1664    // it should have a 'nonnull' attribute in the function prototype.
1665    return SLCT_CheckedLiteral;
1666
1667  switch (E->getStmtClass()) {
1668  case Stmt::BinaryConditionalOperatorClass:
1669  case Stmt::ConditionalOperatorClass: {
1670    // The expression is a literal if both sub-expressions were, and it was
1671    // completely checked only if both sub-expressions were checked.
1672    const AbstractConditionalOperator *C =
1673        cast<AbstractConditionalOperator>(E);
1674    StringLiteralCheckType Left =
1675        checkFormatStringExpr(C->getTrueExpr(), Args, NumArgs,
1676                              HasVAListArg, format_idx, firstDataArg,
1677                              Type, CallType, inFunctionCall);
1678    if (Left == SLCT_NotALiteral)
1679      return SLCT_NotALiteral;
1680    StringLiteralCheckType Right =
1681        checkFormatStringExpr(C->getFalseExpr(), Args, NumArgs,
1682                              HasVAListArg, format_idx, firstDataArg,
1683                              Type, CallType, inFunctionCall);
1684    return Left < Right ? Left : Right;
1685  }
1686
1687  case Stmt::ImplicitCastExprClass: {
1688    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1689    goto tryAgain;
1690  }
1691
1692  case Stmt::OpaqueValueExprClass:
1693    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1694      E = src;
1695      goto tryAgain;
1696    }
1697    return SLCT_NotALiteral;
1698
1699  case Stmt::PredefinedExprClass:
1700    // While __func__, etc., are technically not string literals, they
1701    // cannot contain format specifiers and thus are not a security
1702    // liability.
1703    return SLCT_UncheckedLiteral;
1704
1705  case Stmt::DeclRefExprClass: {
1706    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1707
1708    // As an exception, do not flag errors for variables binding to
1709    // const string literals.
1710    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1711      bool isConstant = false;
1712      QualType T = DR->getType();
1713
1714      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1715        isConstant = AT->getElementType().isConstant(Context);
1716      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1717        isConstant = T.isConstant(Context) &&
1718                     PT->getPointeeType().isConstant(Context);
1719      } else if (T->isObjCObjectPointerType()) {
1720        // In ObjC, there is usually no "const ObjectPointer" type,
1721        // so don't check if the pointee type is constant.
1722        isConstant = T.isConstant(Context);
1723      }
1724
1725      if (isConstant) {
1726        if (const Expr *Init = VD->getAnyInitializer()) {
1727          // Look through initializers like const char c[] = { "foo" }
1728          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
1729            if (InitList->isStringLiteralInit())
1730              Init = InitList->getInit(0)->IgnoreParenImpCasts();
1731          }
1732          return checkFormatStringExpr(Init, Args, NumArgs,
1733                                       HasVAListArg, format_idx,
1734                                       firstDataArg, Type, CallType,
1735                                       /*inFunctionCall*/false);
1736        }
1737      }
1738
1739      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1740      // special check to see if the format string is a function parameter
1741      // of the function calling the printf function.  If the function
1742      // has an attribute indicating it is a printf-like function, then we
1743      // should suppress warnings concerning non-literals being used in a call
1744      // to a vprintf function.  For example:
1745      //
1746      // void
1747      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1748      //      va_list ap;
1749      //      va_start(ap, fmt);
1750      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1751      //      ...
1752      //
1753      if (HasVAListArg) {
1754        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1755          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1756            int PVIndex = PV->getFunctionScopeIndex() + 1;
1757            for (specific_attr_iterator<FormatAttr>
1758                 i = ND->specific_attr_begin<FormatAttr>(),
1759                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1760              FormatAttr *PVFormat = *i;
1761              // adjust for implicit parameter
1762              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1763                if (MD->isInstance())
1764                  ++PVIndex;
1765              // We also check if the formats are compatible.
1766              // We can't pass a 'scanf' string to a 'printf' function.
1767              if (PVIndex == PVFormat->getFormatIdx() &&
1768                  Type == GetFormatStringType(PVFormat))
1769                return SLCT_UncheckedLiteral;
1770            }
1771          }
1772        }
1773      }
1774    }
1775
1776    return SLCT_NotALiteral;
1777  }
1778
1779  case Stmt::CallExprClass:
1780  case Stmt::CXXMemberCallExprClass: {
1781    const CallExpr *CE = cast<CallExpr>(E);
1782    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1783      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1784        unsigned ArgIndex = FA->getFormatIdx();
1785        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1786          if (MD->isInstance())
1787            --ArgIndex;
1788        const Expr *Arg = CE->getArg(ArgIndex - 1);
1789
1790        return checkFormatStringExpr(Arg, Args, NumArgs,
1791                                     HasVAListArg, format_idx, firstDataArg,
1792                                     Type, CallType, inFunctionCall);
1793      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
1794        unsigned BuiltinID = FD->getBuiltinID();
1795        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
1796            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
1797          const Expr *Arg = CE->getArg(0);
1798          return checkFormatStringExpr(Arg, Args, NumArgs,
1799                                       HasVAListArg, format_idx,
1800                                       firstDataArg, Type, CallType,
1801                                       inFunctionCall);
1802        }
1803      }
1804    }
1805
1806    return SLCT_NotALiteral;
1807  }
1808  case Stmt::ObjCStringLiteralClass:
1809  case Stmt::StringLiteralClass: {
1810    const StringLiteral *StrE = NULL;
1811
1812    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1813      StrE = ObjCFExpr->getString();
1814    else
1815      StrE = cast<StringLiteral>(E);
1816
1817    if (StrE) {
1818      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
1819                        firstDataArg, Type, inFunctionCall, CallType);
1820      return SLCT_CheckedLiteral;
1821    }
1822
1823    return SLCT_NotALiteral;
1824  }
1825
1826  default:
1827    return SLCT_NotALiteral;
1828  }
1829}
1830
1831void
1832Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1833                            const Expr * const *ExprArgs,
1834                            SourceLocation CallSiteLoc) {
1835  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1836                                  e = NonNull->args_end();
1837       i != e; ++i) {
1838    const Expr *ArgExpr = ExprArgs[*i];
1839    if (ArgExpr->isNullPointerConstant(Context,
1840                                       Expr::NPC_ValueDependentIsNotNull))
1841      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1842  }
1843}
1844
1845Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1846  return llvm::StringSwitch<FormatStringType>(Format->getType())
1847  .Case("scanf", FST_Scanf)
1848  .Cases("printf", "printf0", FST_Printf)
1849  .Cases("NSString", "CFString", FST_NSString)
1850  .Case("strftime", FST_Strftime)
1851  .Case("strfmon", FST_Strfmon)
1852  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1853  .Default(FST_Unknown);
1854}
1855
1856/// CheckFormatArguments - Check calls to printf and scanf (and similar
1857/// functions) for correct use of format strings.
1858/// Returns true if a format string has been fully checked.
1859bool Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
1860                                unsigned NumArgs, bool IsCXXMember,
1861                                VariadicCallType CallType,
1862                                SourceLocation Loc, SourceRange Range) {
1863  FormatStringInfo FSI;
1864  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
1865    return CheckFormatArguments(Args, NumArgs, FSI.HasVAListArg, FSI.FormatIdx,
1866                                FSI.FirstDataArg, GetFormatStringType(Format),
1867                                CallType, Loc, Range);
1868  return false;
1869}
1870
1871bool Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
1872                                bool HasVAListArg, unsigned format_idx,
1873                                unsigned firstDataArg, FormatStringType Type,
1874                                VariadicCallType CallType,
1875                                SourceLocation Loc, SourceRange Range) {
1876  // CHECK: printf/scanf-like function is called with no format string.
1877  if (format_idx >= NumArgs) {
1878    Diag(Loc, diag::warn_missing_format_string) << Range;
1879    return false;
1880  }
1881
1882  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1883
1884  // CHECK: format string is not a string literal.
1885  //
1886  // Dynamically generated format strings are difficult to
1887  // automatically vet at compile time.  Requiring that format strings
1888  // are string literals: (1) permits the checking of format strings by
1889  // the compiler and thereby (2) can practically remove the source of
1890  // many format string exploits.
1891
1892  // Format string can be either ObjC string (e.g. @"%d") or
1893  // C string (e.g. "%d")
1894  // ObjC string uses the same format specifiers as C string, so we can use
1895  // the same format string checking logic for both ObjC and C strings.
1896  StringLiteralCheckType CT =
1897      checkFormatStringExpr(OrigFormatExpr, Args, NumArgs, HasVAListArg,
1898                            format_idx, firstDataArg, Type, CallType);
1899  if (CT != SLCT_NotALiteral)
1900    // Literal format string found, check done!
1901    return CT == SLCT_CheckedLiteral;
1902
1903  // Strftime is particular as it always uses a single 'time' argument,
1904  // so it is safe to pass a non-literal string.
1905  if (Type == FST_Strftime)
1906    return false;
1907
1908  // Do not emit diag when the string param is a macro expansion and the
1909  // format is either NSString or CFString. This is a hack to prevent
1910  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1911  // which are usually used in place of NS and CF string literals.
1912  if (Type == FST_NSString &&
1913      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
1914    return false;
1915
1916  // If there are no arguments specified, warn with -Wformat-security, otherwise
1917  // warn only with -Wformat-nonliteral.
1918  if (NumArgs == format_idx+1)
1919    Diag(Args[format_idx]->getLocStart(),
1920         diag::warn_format_nonliteral_noargs)
1921      << OrigFormatExpr->getSourceRange();
1922  else
1923    Diag(Args[format_idx]->getLocStart(),
1924         diag::warn_format_nonliteral)
1925           << OrigFormatExpr->getSourceRange();
1926  return false;
1927}
1928
1929namespace {
1930class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1931protected:
1932  Sema &S;
1933  const StringLiteral *FExpr;
1934  const Expr *OrigFormatExpr;
1935  const unsigned FirstDataArg;
1936  const unsigned NumDataArgs;
1937  const char *Beg; // Start of format string.
1938  const bool HasVAListArg;
1939  const Expr * const *Args;
1940  const unsigned NumArgs;
1941  unsigned FormatIdx;
1942  llvm::BitVector CoveredArgs;
1943  bool usesPositionalArgs;
1944  bool atFirstArg;
1945  bool inFunctionCall;
1946  Sema::VariadicCallType CallType;
1947public:
1948  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1949                     const Expr *origFormatExpr, unsigned firstDataArg,
1950                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
1951                     Expr **args, unsigned numArgs,
1952                     unsigned formatIdx, bool inFunctionCall,
1953                     Sema::VariadicCallType callType)
1954    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1955      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
1956      Beg(beg), HasVAListArg(hasVAListArg),
1957      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
1958      usesPositionalArgs(false), atFirstArg(true),
1959      inFunctionCall(inFunctionCall), CallType(callType) {
1960        CoveredArgs.resize(numDataArgs);
1961        CoveredArgs.reset();
1962      }
1963
1964  void DoneProcessing();
1965
1966  void HandleIncompleteSpecifier(const char *startSpecifier,
1967                                 unsigned specifierLen);
1968
1969  void HandleInvalidLengthModifier(
1970      const analyze_format_string::FormatSpecifier &FS,
1971      const analyze_format_string::ConversionSpecifier &CS,
1972      const char *startSpecifier, unsigned specifierLen, unsigned DiagID);
1973
1974  void HandleNonStandardLengthModifier(
1975      const analyze_format_string::FormatSpecifier &FS,
1976      const char *startSpecifier, unsigned specifierLen);
1977
1978  void HandleNonStandardConversionSpecifier(
1979      const analyze_format_string::ConversionSpecifier &CS,
1980      const char *startSpecifier, unsigned specifierLen);
1981
1982  virtual void HandlePosition(const char *startPos, unsigned posLen);
1983
1984  virtual void HandleInvalidPosition(const char *startSpecifier,
1985                                     unsigned specifierLen,
1986                                     analyze_format_string::PositionContext p);
1987
1988  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1989
1990  void HandleNullChar(const char *nullCharacter);
1991
1992  template <typename Range>
1993  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1994                                   const Expr *ArgumentExpr,
1995                                   PartialDiagnostic PDiag,
1996                                   SourceLocation StringLoc,
1997                                   bool IsStringLocation, Range StringRange,
1998                            ArrayRef<FixItHint> Fixit = ArrayRef<FixItHint>());
1999
2000protected:
2001  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
2002                                        const char *startSpec,
2003                                        unsigned specifierLen,
2004                                        const char *csStart, unsigned csLen);
2005
2006  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
2007                                         const char *startSpec,
2008                                         unsigned specifierLen);
2009
2010  SourceRange getFormatStringRange();
2011  CharSourceRange getSpecifierRange(const char *startSpecifier,
2012                                    unsigned specifierLen);
2013  SourceLocation getLocationOfByte(const char *x);
2014
2015  const Expr *getDataArg(unsigned i) const;
2016
2017  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
2018                    const analyze_format_string::ConversionSpecifier &CS,
2019                    const char *startSpecifier, unsigned specifierLen,
2020                    unsigned argIndex);
2021
2022  template <typename Range>
2023  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
2024                            bool IsStringLocation, Range StringRange,
2025                            ArrayRef<FixItHint> Fixit = ArrayRef<FixItHint>());
2026
2027  void CheckPositionalAndNonpositionalArgs(
2028      const analyze_format_string::FormatSpecifier *FS);
2029};
2030}
2031
2032SourceRange CheckFormatHandler::getFormatStringRange() {
2033  return OrigFormatExpr->getSourceRange();
2034}
2035
2036CharSourceRange CheckFormatHandler::
2037getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2038  SourceLocation Start = getLocationOfByte(startSpecifier);
2039  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2040
2041  // Advance the end SourceLocation by one due to half-open ranges.
2042  End = End.getLocWithOffset(1);
2043
2044  return CharSourceRange::getCharRange(Start, End);
2045}
2046
2047SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2048  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2049}
2050
2051void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2052                                                   unsigned specifierLen){
2053  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2054                       getLocationOfByte(startSpecifier),
2055                       /*IsStringLocation*/true,
2056                       getSpecifierRange(startSpecifier, specifierLen));
2057}
2058
2059void CheckFormatHandler::HandleInvalidLengthModifier(
2060    const analyze_format_string::FormatSpecifier &FS,
2061    const analyze_format_string::ConversionSpecifier &CS,
2062    const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
2063  using namespace analyze_format_string;
2064
2065  const LengthModifier &LM = FS.getLengthModifier();
2066  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2067
2068  // See if we know how to fix this length modifier.
2069  llvm::Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2070  if (FixedLM) {
2071    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2072                         getLocationOfByte(LM.getStart()),
2073                         /*IsStringLocation*/true,
2074                         getSpecifierRange(startSpecifier, specifierLen));
2075
2076    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2077      << FixedLM->toString()
2078      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2079
2080  } else {
2081    FixItHint Hint;
2082    if (DiagID == diag::warn_format_nonsensical_length)
2083      Hint = FixItHint::CreateRemoval(LMRange);
2084
2085    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2086                         getLocationOfByte(LM.getStart()),
2087                         /*IsStringLocation*/true,
2088                         getSpecifierRange(startSpecifier, specifierLen),
2089                         Hint);
2090  }
2091}
2092
2093void CheckFormatHandler::HandleNonStandardLengthModifier(
2094    const analyze_format_string::FormatSpecifier &FS,
2095    const char *startSpecifier, unsigned specifierLen) {
2096  using namespace analyze_format_string;
2097
2098  const LengthModifier &LM = FS.getLengthModifier();
2099  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2100
2101  // See if we know how to fix this length modifier.
2102  llvm::Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2103  if (FixedLM) {
2104    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2105                           << LM.toString() << 0,
2106                         getLocationOfByte(LM.getStart()),
2107                         /*IsStringLocation*/true,
2108                         getSpecifierRange(startSpecifier, specifierLen));
2109
2110    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2111      << FixedLM->toString()
2112      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2113
2114  } else {
2115    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2116                           << LM.toString() << 0,
2117                         getLocationOfByte(LM.getStart()),
2118                         /*IsStringLocation*/true,
2119                         getSpecifierRange(startSpecifier, specifierLen));
2120  }
2121}
2122
2123void CheckFormatHandler::HandleNonStandardConversionSpecifier(
2124    const analyze_format_string::ConversionSpecifier &CS,
2125    const char *startSpecifier, unsigned specifierLen) {
2126  using namespace analyze_format_string;
2127
2128  // See if we know how to fix this conversion specifier.
2129  llvm::Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
2130  if (FixedCS) {
2131    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2132                          << CS.toString() << /*conversion specifier*/1,
2133                         getLocationOfByte(CS.getStart()),
2134                         /*IsStringLocation*/true,
2135                         getSpecifierRange(startSpecifier, specifierLen));
2136
2137    CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
2138    S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
2139      << FixedCS->toString()
2140      << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
2141  } else {
2142    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2143                          << CS.toString() << /*conversion specifier*/1,
2144                         getLocationOfByte(CS.getStart()),
2145                         /*IsStringLocation*/true,
2146                         getSpecifierRange(startSpecifier, specifierLen));
2147  }
2148}
2149
2150void CheckFormatHandler::HandlePosition(const char *startPos,
2151                                        unsigned posLen) {
2152  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
2153                               getLocationOfByte(startPos),
2154                               /*IsStringLocation*/true,
2155                               getSpecifierRange(startPos, posLen));
2156}
2157
2158void
2159CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
2160                                     analyze_format_string::PositionContext p) {
2161  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
2162                         << (unsigned) p,
2163                       getLocationOfByte(startPos), /*IsStringLocation*/true,
2164                       getSpecifierRange(startPos, posLen));
2165}
2166
2167void CheckFormatHandler::HandleZeroPosition(const char *startPos,
2168                                            unsigned posLen) {
2169  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
2170                               getLocationOfByte(startPos),
2171                               /*IsStringLocation*/true,
2172                               getSpecifierRange(startPos, posLen));
2173}
2174
2175void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
2176  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
2177    // The presence of a null character is likely an error.
2178    EmitFormatDiagnostic(
2179      S.PDiag(diag::warn_printf_format_string_contains_null_char),
2180      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
2181      getFormatStringRange());
2182  }
2183}
2184
2185// Note that this may return NULL if there was an error parsing or building
2186// one of the argument expressions.
2187const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
2188  return Args[FirstDataArg + i];
2189}
2190
2191void CheckFormatHandler::DoneProcessing() {
2192    // Does the number of data arguments exceed the number of
2193    // format conversions in the format string?
2194  if (!HasVAListArg) {
2195      // Find any arguments that weren't covered.
2196    CoveredArgs.flip();
2197    signed notCoveredArg = CoveredArgs.find_first();
2198    if (notCoveredArg >= 0) {
2199      assert((unsigned)notCoveredArg < NumDataArgs);
2200      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
2201        SourceLocation Loc = E->getLocStart();
2202        if (!S.getSourceManager().isInSystemMacro(Loc)) {
2203          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
2204                               Loc, /*IsStringLocation*/false,
2205                               getFormatStringRange());
2206        }
2207      }
2208    }
2209  }
2210}
2211
2212bool
2213CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
2214                                                     SourceLocation Loc,
2215                                                     const char *startSpec,
2216                                                     unsigned specifierLen,
2217                                                     const char *csStart,
2218                                                     unsigned csLen) {
2219
2220  bool keepGoing = true;
2221  if (argIndex < NumDataArgs) {
2222    // Consider the argument coverered, even though the specifier doesn't
2223    // make sense.
2224    CoveredArgs.set(argIndex);
2225  }
2226  else {
2227    // If argIndex exceeds the number of data arguments we
2228    // don't issue a warning because that is just a cascade of warnings (and
2229    // they may have intended '%%' anyway). We don't want to continue processing
2230    // the format string after this point, however, as we will like just get
2231    // gibberish when trying to match arguments.
2232    keepGoing = false;
2233  }
2234
2235  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2236                         << StringRef(csStart, csLen),
2237                       Loc, /*IsStringLocation*/true,
2238                       getSpecifierRange(startSpec, specifierLen));
2239
2240  return keepGoing;
2241}
2242
2243void
2244CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2245                                                      const char *startSpec,
2246                                                      unsigned specifierLen) {
2247  EmitFormatDiagnostic(
2248    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2249    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2250}
2251
2252bool
2253CheckFormatHandler::CheckNumArgs(
2254  const analyze_format_string::FormatSpecifier &FS,
2255  const analyze_format_string::ConversionSpecifier &CS,
2256  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2257
2258  if (argIndex >= NumDataArgs) {
2259    PartialDiagnostic PDiag = FS.usesPositionalArg()
2260      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2261           << (argIndex+1) << NumDataArgs)
2262      : S.PDiag(diag::warn_printf_insufficient_data_args);
2263    EmitFormatDiagnostic(
2264      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2265      getSpecifierRange(startSpecifier, specifierLen));
2266    return false;
2267  }
2268  return true;
2269}
2270
2271template<typename Range>
2272void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2273                                              SourceLocation Loc,
2274                                              bool IsStringLocation,
2275                                              Range StringRange,
2276                                              ArrayRef<FixItHint> FixIt) {
2277  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2278                       Loc, IsStringLocation, StringRange, FixIt);
2279}
2280
2281/// \brief If the format string is not within the funcion call, emit a note
2282/// so that the function call and string are in diagnostic messages.
2283///
2284/// \param InFunctionCall if true, the format string is within the function
2285/// call and only one diagnostic message will be produced.  Otherwise, an
2286/// extra note will be emitted pointing to location of the format string.
2287///
2288/// \param ArgumentExpr the expression that is passed as the format string
2289/// argument in the function call.  Used for getting locations when two
2290/// diagnostics are emitted.
2291///
2292/// \param PDiag the callee should already have provided any strings for the
2293/// diagnostic message.  This function only adds locations and fixits
2294/// to diagnostics.
2295///
2296/// \param Loc primary location for diagnostic.  If two diagnostics are
2297/// required, one will be at Loc and a new SourceLocation will be created for
2298/// the other one.
2299///
2300/// \param IsStringLocation if true, Loc points to the format string should be
2301/// used for the note.  Otherwise, Loc points to the argument list and will
2302/// be used with PDiag.
2303///
2304/// \param StringRange some or all of the string to highlight.  This is
2305/// templated so it can accept either a CharSourceRange or a SourceRange.
2306///
2307/// \param FixIt optional fix it hint for the format string.
2308template<typename Range>
2309void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2310                                              const Expr *ArgumentExpr,
2311                                              PartialDiagnostic PDiag,
2312                                              SourceLocation Loc,
2313                                              bool IsStringLocation,
2314                                              Range StringRange,
2315                                              ArrayRef<FixItHint> FixIt) {
2316  if (InFunctionCall) {
2317    const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
2318    D << StringRange;
2319    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2320         I != E; ++I) {
2321      D << *I;
2322    }
2323  } else {
2324    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2325      << ArgumentExpr->getSourceRange();
2326
2327    const Sema::SemaDiagnosticBuilder &Note =
2328      S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2329             diag::note_format_string_defined);
2330
2331    Note << StringRange;
2332    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2333         I != E; ++I) {
2334      Note << *I;
2335    }
2336  }
2337}
2338
2339//===--- CHECK: Printf format string checking ------------------------------===//
2340
2341namespace {
2342class CheckPrintfHandler : public CheckFormatHandler {
2343  bool ObjCContext;
2344public:
2345  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2346                     const Expr *origFormatExpr, unsigned firstDataArg,
2347                     unsigned numDataArgs, bool isObjC,
2348                     const char *beg, bool hasVAListArg,
2349                     Expr **Args, unsigned NumArgs,
2350                     unsigned formatIdx, bool inFunctionCall,
2351                     Sema::VariadicCallType CallType)
2352  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2353                       numDataArgs, beg, hasVAListArg, Args, NumArgs,
2354                       formatIdx, inFunctionCall, CallType), ObjCContext(isObjC)
2355  {}
2356
2357
2358  bool HandleInvalidPrintfConversionSpecifier(
2359                                      const analyze_printf::PrintfSpecifier &FS,
2360                                      const char *startSpecifier,
2361                                      unsigned specifierLen);
2362
2363  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2364                             const char *startSpecifier,
2365                             unsigned specifierLen);
2366  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2367                       const char *StartSpecifier,
2368                       unsigned SpecifierLen,
2369                       const Expr *E);
2370
2371  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2372                    const char *startSpecifier, unsigned specifierLen);
2373  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2374                           const analyze_printf::OptionalAmount &Amt,
2375                           unsigned type,
2376                           const char *startSpecifier, unsigned specifierLen);
2377  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2378                  const analyze_printf::OptionalFlag &flag,
2379                  const char *startSpecifier, unsigned specifierLen);
2380  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2381                         const analyze_printf::OptionalFlag &ignoredFlag,
2382                         const analyze_printf::OptionalFlag &flag,
2383                         const char *startSpecifier, unsigned specifierLen);
2384  bool checkForCStrMembers(const analyze_printf::ArgType &AT,
2385                           const Expr *E, const CharSourceRange &CSR);
2386
2387};
2388}
2389
2390bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2391                                      const analyze_printf::PrintfSpecifier &FS,
2392                                      const char *startSpecifier,
2393                                      unsigned specifierLen) {
2394  const analyze_printf::PrintfConversionSpecifier &CS =
2395    FS.getConversionSpecifier();
2396
2397  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2398                                          getLocationOfByte(CS.getStart()),
2399                                          startSpecifier, specifierLen,
2400                                          CS.getStart(), CS.getLength());
2401}
2402
2403bool CheckPrintfHandler::HandleAmount(
2404                               const analyze_format_string::OptionalAmount &Amt,
2405                               unsigned k, const char *startSpecifier,
2406                               unsigned specifierLen) {
2407
2408  if (Amt.hasDataArgument()) {
2409    if (!HasVAListArg) {
2410      unsigned argIndex = Amt.getArgIndex();
2411      if (argIndex >= NumDataArgs) {
2412        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2413                               << k,
2414                             getLocationOfByte(Amt.getStart()),
2415                             /*IsStringLocation*/true,
2416                             getSpecifierRange(startSpecifier, specifierLen));
2417        // Don't do any more checking.  We will just emit
2418        // spurious errors.
2419        return false;
2420      }
2421
2422      // Type check the data argument.  It should be an 'int'.
2423      // Although not in conformance with C99, we also allow the argument to be
2424      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2425      // doesn't emit a warning for that case.
2426      CoveredArgs.set(argIndex);
2427      const Expr *Arg = getDataArg(argIndex);
2428      if (!Arg)
2429        return false;
2430
2431      QualType T = Arg->getType();
2432
2433      const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
2434      assert(AT.isValid());
2435
2436      if (!AT.matchesType(S.Context, T)) {
2437        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2438                               << k << AT.getRepresentativeTypeName(S.Context)
2439                               << T << Arg->getSourceRange(),
2440                             getLocationOfByte(Amt.getStart()),
2441                             /*IsStringLocation*/true,
2442                             getSpecifierRange(startSpecifier, specifierLen));
2443        // Don't do any more checking.  We will just emit
2444        // spurious errors.
2445        return false;
2446      }
2447    }
2448  }
2449  return true;
2450}
2451
2452void CheckPrintfHandler::HandleInvalidAmount(
2453                                      const analyze_printf::PrintfSpecifier &FS,
2454                                      const analyze_printf::OptionalAmount &Amt,
2455                                      unsigned type,
2456                                      const char *startSpecifier,
2457                                      unsigned specifierLen) {
2458  const analyze_printf::PrintfConversionSpecifier &CS =
2459    FS.getConversionSpecifier();
2460
2461  FixItHint fixit =
2462    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2463      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2464                                 Amt.getConstantLength()))
2465      : FixItHint();
2466
2467  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2468                         << type << CS.toString(),
2469                       getLocationOfByte(Amt.getStart()),
2470                       /*IsStringLocation*/true,
2471                       getSpecifierRange(startSpecifier, specifierLen),
2472                       fixit);
2473}
2474
2475void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2476                                    const analyze_printf::OptionalFlag &flag,
2477                                    const char *startSpecifier,
2478                                    unsigned specifierLen) {
2479  // Warn about pointless flag with a fixit removal.
2480  const analyze_printf::PrintfConversionSpecifier &CS =
2481    FS.getConversionSpecifier();
2482  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2483                         << flag.toString() << CS.toString(),
2484                       getLocationOfByte(flag.getPosition()),
2485                       /*IsStringLocation*/true,
2486                       getSpecifierRange(startSpecifier, specifierLen),
2487                       FixItHint::CreateRemoval(
2488                         getSpecifierRange(flag.getPosition(), 1)));
2489}
2490
2491void CheckPrintfHandler::HandleIgnoredFlag(
2492                                const analyze_printf::PrintfSpecifier &FS,
2493                                const analyze_printf::OptionalFlag &ignoredFlag,
2494                                const analyze_printf::OptionalFlag &flag,
2495                                const char *startSpecifier,
2496                                unsigned specifierLen) {
2497  // Warn about ignored flag with a fixit removal.
2498  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2499                         << ignoredFlag.toString() << flag.toString(),
2500                       getLocationOfByte(ignoredFlag.getPosition()),
2501                       /*IsStringLocation*/true,
2502                       getSpecifierRange(startSpecifier, specifierLen),
2503                       FixItHint::CreateRemoval(
2504                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2505}
2506
2507// Determines if the specified is a C++ class or struct containing
2508// a member with the specified name and kind (e.g. a CXXMethodDecl named
2509// "c_str()").
2510template<typename MemberKind>
2511static llvm::SmallPtrSet<MemberKind*, 1>
2512CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
2513  const RecordType *RT = Ty->getAs<RecordType>();
2514  llvm::SmallPtrSet<MemberKind*, 1> Results;
2515
2516  if (!RT)
2517    return Results;
2518  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
2519  if (!RD)
2520    return Results;
2521
2522  LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
2523                 Sema::LookupMemberName);
2524
2525  // We just need to include all members of the right kind turned up by the
2526  // filter, at this point.
2527  if (S.LookupQualifiedName(R, RT->getDecl()))
2528    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
2529      NamedDecl *decl = (*I)->getUnderlyingDecl();
2530      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
2531        Results.insert(FK);
2532    }
2533  return Results;
2534}
2535
2536// Check if a (w)string was passed when a (w)char* was needed, and offer a
2537// better diagnostic if so. AT is assumed to be valid.
2538// Returns true when a c_str() conversion method is found.
2539bool CheckPrintfHandler::checkForCStrMembers(
2540    const analyze_printf::ArgType &AT, const Expr *E,
2541    const CharSourceRange &CSR) {
2542  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
2543
2544  MethodSet Results =
2545      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
2546
2547  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
2548       MI != ME; ++MI) {
2549    const CXXMethodDecl *Method = *MI;
2550    if (Method->getNumParams() == 0 &&
2551          AT.matchesType(S.Context, Method->getResultType())) {
2552      // FIXME: Suggest parens if the expression needs them.
2553      SourceLocation EndLoc =
2554          S.getPreprocessor().getLocForEndOfToken(E->getLocEnd());
2555      S.Diag(E->getLocStart(), diag::note_printf_c_str)
2556          << "c_str()"
2557          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
2558      return true;
2559    }
2560  }
2561
2562  return false;
2563}
2564
2565bool
2566CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2567                                            &FS,
2568                                          const char *startSpecifier,
2569                                          unsigned specifierLen) {
2570
2571  using namespace analyze_format_string;
2572  using namespace analyze_printf;
2573  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2574
2575  if (FS.consumesDataArgument()) {
2576    if (atFirstArg) {
2577        atFirstArg = false;
2578        usesPositionalArgs = FS.usesPositionalArg();
2579    }
2580    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2581      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2582                                        startSpecifier, specifierLen);
2583      return false;
2584    }
2585  }
2586
2587  // First check if the field width, precision, and conversion specifier
2588  // have matching data arguments.
2589  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2590                    startSpecifier, specifierLen)) {
2591    return false;
2592  }
2593
2594  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2595                    startSpecifier, specifierLen)) {
2596    return false;
2597  }
2598
2599  if (!CS.consumesDataArgument()) {
2600    // FIXME: Technically specifying a precision or field width here
2601    // makes no sense.  Worth issuing a warning at some point.
2602    return true;
2603  }
2604
2605  // Consume the argument.
2606  unsigned argIndex = FS.getArgIndex();
2607  if (argIndex < NumDataArgs) {
2608    // The check to see if the argIndex is valid will come later.
2609    // We set the bit here because we may exit early from this
2610    // function if we encounter some other error.
2611    CoveredArgs.set(argIndex);
2612  }
2613
2614  // Check for using an Objective-C specific conversion specifier
2615  // in a non-ObjC literal.
2616  if (!ObjCContext && CS.isObjCArg()) {
2617    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2618                                                  specifierLen);
2619  }
2620
2621  // Check for invalid use of field width
2622  if (!FS.hasValidFieldWidth()) {
2623    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2624        startSpecifier, specifierLen);
2625  }
2626
2627  // Check for invalid use of precision
2628  if (!FS.hasValidPrecision()) {
2629    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2630        startSpecifier, specifierLen);
2631  }
2632
2633  // Check each flag does not conflict with any other component.
2634  if (!FS.hasValidThousandsGroupingPrefix())
2635    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2636  if (!FS.hasValidLeadingZeros())
2637    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2638  if (!FS.hasValidPlusPrefix())
2639    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2640  if (!FS.hasValidSpacePrefix())
2641    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2642  if (!FS.hasValidAlternativeForm())
2643    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2644  if (!FS.hasValidLeftJustified())
2645    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2646
2647  // Check that flags are not ignored by another flag
2648  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2649    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2650        startSpecifier, specifierLen);
2651  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2652    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2653            startSpecifier, specifierLen);
2654
2655  // Check the length modifier is valid with the given conversion specifier.
2656  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
2657    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2658                                diag::warn_format_nonsensical_length);
2659  else if (!FS.hasStandardLengthModifier())
2660    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
2661  else if (!FS.hasStandardLengthConversionCombination())
2662    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2663                                diag::warn_format_non_standard_conversion_spec);
2664
2665  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2666    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2667
2668  // The remaining checks depend on the data arguments.
2669  if (HasVAListArg)
2670    return true;
2671
2672  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2673    return false;
2674
2675  const Expr *Arg = getDataArg(argIndex);
2676  if (!Arg)
2677    return true;
2678
2679  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
2680}
2681
2682static bool requiresParensToAddCast(const Expr *E) {
2683  // FIXME: We should have a general way to reason about operator
2684  // precedence and whether parens are actually needed here.
2685  // Take care of a few common cases where they aren't.
2686  const Expr *Inside = E->IgnoreImpCasts();
2687  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
2688    Inside = POE->getSyntacticForm()->IgnoreImpCasts();
2689
2690  switch (Inside->getStmtClass()) {
2691  case Stmt::ArraySubscriptExprClass:
2692  case Stmt::CallExprClass:
2693  case Stmt::DeclRefExprClass:
2694  case Stmt::MemberExprClass:
2695  case Stmt::ObjCIvarRefExprClass:
2696  case Stmt::ObjCMessageExprClass:
2697  case Stmt::ObjCPropertyRefExprClass:
2698  case Stmt::ParenExprClass:
2699  case Stmt::UnaryOperatorClass:
2700    return false;
2701  default:
2702    return true;
2703  }
2704}
2705
2706bool
2707CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2708                                    const char *StartSpecifier,
2709                                    unsigned SpecifierLen,
2710                                    const Expr *E) {
2711  using namespace analyze_format_string;
2712  using namespace analyze_printf;
2713  // Now type check the data expression that matches the
2714  // format specifier.
2715  const analyze_printf::ArgType &AT = FS.getArgType(S.Context,
2716                                                    ObjCContext);
2717  if (!AT.isValid())
2718    return true;
2719
2720  QualType IntendedTy = E->getType();
2721  if (AT.matchesType(S.Context, IntendedTy))
2722    return true;
2723
2724  // Look through argument promotions for our error message's reported type.
2725  // This includes the integral and floating promotions, but excludes array
2726  // and function pointer decay; seeing that an argument intended to be a
2727  // string has type 'char [6]' is probably more confusing than 'char *'.
2728  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2729    if (ICE->getCastKind() == CK_IntegralCast ||
2730        ICE->getCastKind() == CK_FloatingCast) {
2731      E = ICE->getSubExpr();
2732      IntendedTy = E->getType();
2733
2734      // Check if we didn't match because of an implicit cast from a 'char'
2735      // or 'short' to an 'int'.  This is done because printf is a varargs
2736      // function.
2737      if (ICE->getType() == S.Context.IntTy ||
2738          ICE->getType() == S.Context.UnsignedIntTy) {
2739        // All further checking is done on the subexpression.
2740        if (AT.matchesType(S.Context, IntendedTy))
2741          return true;
2742      }
2743    }
2744  }
2745
2746  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
2747    // Special-case some of Darwin's platform-independence types.
2748    if (const TypedefType *UserTy = IntendedTy->getAs<TypedefType>()) {
2749      StringRef Name = UserTy->getDecl()->getName();
2750      IntendedTy = llvm::StringSwitch<QualType>(Name)
2751        .Case("NSInteger", S.Context.LongTy)
2752        .Case("NSUInteger", S.Context.UnsignedLongTy)
2753        .Case("SInt32", S.Context.IntTy)
2754        .Case("UInt32", S.Context.UnsignedIntTy)
2755        .Default(IntendedTy);
2756    }
2757  }
2758
2759  // We may be able to offer a FixItHint if it is a supported type.
2760  PrintfSpecifier fixedFS = FS;
2761  bool success = fixedFS.fixType(IntendedTy, S.getLangOpts(),
2762                                 S.Context, ObjCContext);
2763
2764  if (success) {
2765    // Get the fix string from the fixed format specifier
2766    SmallString<16> buf;
2767    llvm::raw_svector_ostream os(buf);
2768    fixedFS.toString(os);
2769
2770    CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
2771
2772    if (IntendedTy != E->getType()) {
2773      // The canonical type for formatting this value is different from the
2774      // actual type of the expression. (This occurs, for example, with Darwin's
2775      // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
2776      // should be printed as 'long' for 64-bit compatibility.)
2777      // Rather than emitting a normal format/argument mismatch, we want to
2778      // add a cast to the recommended type (and correct the format string
2779      // if necessary).
2780      SmallString<16> CastBuf;
2781      llvm::raw_svector_ostream CastFix(CastBuf);
2782      CastFix << "(";
2783      IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
2784      CastFix << ")";
2785
2786      SmallVector<FixItHint,4> Hints;
2787      if (!AT.matchesType(S.Context, IntendedTy))
2788        Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
2789
2790      if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
2791        // If there's already a cast present, just replace it.
2792        SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
2793        Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
2794
2795      } else if (!requiresParensToAddCast(E)) {
2796        // If the expression has high enough precedence,
2797        // just write the C-style cast.
2798        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2799                                                   CastFix.str()));
2800      } else {
2801        // Otherwise, add parens around the expression as well as the cast.
2802        CastFix << "(";
2803        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2804                                                   CastFix.str()));
2805
2806        SourceLocation After = S.PP.getLocForEndOfToken(E->getLocEnd());
2807        Hints.push_back(FixItHint::CreateInsertion(After, ")"));
2808      }
2809
2810      // We extract the name from the typedef because we don't want to show
2811      // the underlying type in the diagnostic.
2812      const TypedefType *UserTy = cast<TypedefType>(E->getType());
2813      StringRef Name = UserTy->getDecl()->getName();
2814
2815      // Finally, emit the diagnostic.
2816      EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
2817                             << Name << IntendedTy
2818                             << E->getSourceRange(),
2819                           E->getLocStart(), /*IsStringLocation=*/false,
2820                           SpecRange, Hints);
2821    } else {
2822      EmitFormatDiagnostic(
2823        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2824          << AT.getRepresentativeTypeName(S.Context) << IntendedTy
2825          << E->getSourceRange(),
2826        E->getLocStart(),
2827        /*IsStringLocation*/false,
2828        SpecRange,
2829        FixItHint::CreateReplacement(SpecRange, os.str()));
2830    }
2831  } else {
2832    const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
2833                                                   SpecifierLen);
2834    // Since the warning for passing non-POD types to variadic functions
2835    // was deferred until now, we emit a warning for non-POD
2836    // arguments here.
2837    if (S.isValidVarArgType(E->getType()) == Sema::VAK_Invalid) {
2838      unsigned DiagKind;
2839      if (E->getType()->isObjCObjectType())
2840        DiagKind = diag::err_cannot_pass_objc_interface_to_vararg_format;
2841      else
2842        DiagKind = diag::warn_non_pod_vararg_with_format_string;
2843
2844      EmitFormatDiagnostic(
2845        S.PDiag(DiagKind)
2846          << S.getLangOpts().CPlusPlus0x
2847          << E->getType()
2848          << CallType
2849          << AT.getRepresentativeTypeName(S.Context)
2850          << CSR
2851          << E->getSourceRange(),
2852        E->getLocStart(), /*IsStringLocation*/false, CSR);
2853
2854      checkForCStrMembers(AT, E, CSR);
2855    } else
2856      EmitFormatDiagnostic(
2857        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2858          << AT.getRepresentativeTypeName(S.Context) << E->getType()
2859          << CSR
2860          << E->getSourceRange(),
2861        E->getLocStart(), /*IsStringLocation*/false, CSR);
2862  }
2863
2864  return true;
2865}
2866
2867//===--- CHECK: Scanf format string checking ------------------------------===//
2868
2869namespace {
2870class CheckScanfHandler : public CheckFormatHandler {
2871public:
2872  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2873                    const Expr *origFormatExpr, unsigned firstDataArg,
2874                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
2875                    Expr **Args, unsigned NumArgs,
2876                    unsigned formatIdx, bool inFunctionCall,
2877                    Sema::VariadicCallType CallType)
2878  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2879                       numDataArgs, beg, hasVAListArg,
2880                       Args, NumArgs, formatIdx, inFunctionCall, CallType)
2881  {}
2882
2883  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2884                            const char *startSpecifier,
2885                            unsigned specifierLen);
2886
2887  bool HandleInvalidScanfConversionSpecifier(
2888          const analyze_scanf::ScanfSpecifier &FS,
2889          const char *startSpecifier,
2890          unsigned specifierLen);
2891
2892  void HandleIncompleteScanList(const char *start, const char *end);
2893};
2894}
2895
2896void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2897                                                 const char *end) {
2898  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2899                       getLocationOfByte(end), /*IsStringLocation*/true,
2900                       getSpecifierRange(start, end - start));
2901}
2902
2903bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2904                                        const analyze_scanf::ScanfSpecifier &FS,
2905                                        const char *startSpecifier,
2906                                        unsigned specifierLen) {
2907
2908  const analyze_scanf::ScanfConversionSpecifier &CS =
2909    FS.getConversionSpecifier();
2910
2911  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2912                                          getLocationOfByte(CS.getStart()),
2913                                          startSpecifier, specifierLen,
2914                                          CS.getStart(), CS.getLength());
2915}
2916
2917bool CheckScanfHandler::HandleScanfSpecifier(
2918                                       const analyze_scanf::ScanfSpecifier &FS,
2919                                       const char *startSpecifier,
2920                                       unsigned specifierLen) {
2921
2922  using namespace analyze_scanf;
2923  using namespace analyze_format_string;
2924
2925  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2926
2927  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2928  // be used to decide if we are using positional arguments consistently.
2929  if (FS.consumesDataArgument()) {
2930    if (atFirstArg) {
2931      atFirstArg = false;
2932      usesPositionalArgs = FS.usesPositionalArg();
2933    }
2934    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2935      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2936                                        startSpecifier, specifierLen);
2937      return false;
2938    }
2939  }
2940
2941  // Check if the field with is non-zero.
2942  const OptionalAmount &Amt = FS.getFieldWidth();
2943  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2944    if (Amt.getConstantAmount() == 0) {
2945      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2946                                                   Amt.getConstantLength());
2947      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2948                           getLocationOfByte(Amt.getStart()),
2949                           /*IsStringLocation*/true, R,
2950                           FixItHint::CreateRemoval(R));
2951    }
2952  }
2953
2954  if (!FS.consumesDataArgument()) {
2955    // FIXME: Technically specifying a precision or field width here
2956    // makes no sense.  Worth issuing a warning at some point.
2957    return true;
2958  }
2959
2960  // Consume the argument.
2961  unsigned argIndex = FS.getArgIndex();
2962  if (argIndex < NumDataArgs) {
2963      // The check to see if the argIndex is valid will come later.
2964      // We set the bit here because we may exit early from this
2965      // function if we encounter some other error.
2966    CoveredArgs.set(argIndex);
2967  }
2968
2969  // Check the length modifier is valid with the given conversion specifier.
2970  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
2971    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2972                                diag::warn_format_nonsensical_length);
2973  else if (!FS.hasStandardLengthModifier())
2974    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
2975  else if (!FS.hasStandardLengthConversionCombination())
2976    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2977                                diag::warn_format_non_standard_conversion_spec);
2978
2979  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2980    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2981
2982  // The remaining checks depend on the data arguments.
2983  if (HasVAListArg)
2984    return true;
2985
2986  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2987    return false;
2988
2989  // Check that the argument type matches the format specifier.
2990  const Expr *Ex = getDataArg(argIndex);
2991  if (!Ex)
2992    return true;
2993
2994  const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
2995  if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType())) {
2996    ScanfSpecifier fixedFS = FS;
2997    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2998                                   S.Context);
2999
3000    if (success) {
3001      // Get the fix string from the fixed format specifier.
3002      SmallString<128> buf;
3003      llvm::raw_svector_ostream os(buf);
3004      fixedFS.toString(os);
3005
3006      EmitFormatDiagnostic(
3007        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3008          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3009          << Ex->getSourceRange(),
3010        Ex->getLocStart(),
3011        /*IsStringLocation*/false,
3012        getSpecifierRange(startSpecifier, specifierLen),
3013        FixItHint::CreateReplacement(
3014          getSpecifierRange(startSpecifier, specifierLen),
3015          os.str()));
3016    } else {
3017      EmitFormatDiagnostic(
3018        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3019          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3020          << Ex->getSourceRange(),
3021        Ex->getLocStart(),
3022        /*IsStringLocation*/false,
3023        getSpecifierRange(startSpecifier, specifierLen));
3024    }
3025  }
3026
3027  return true;
3028}
3029
3030void Sema::CheckFormatString(const StringLiteral *FExpr,
3031                             const Expr *OrigFormatExpr,
3032                             Expr **Args, unsigned NumArgs,
3033                             bool HasVAListArg, unsigned format_idx,
3034                             unsigned firstDataArg, FormatStringType Type,
3035                             bool inFunctionCall, VariadicCallType CallType) {
3036
3037  // CHECK: is the format string a wide literal?
3038  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
3039    CheckFormatHandler::EmitFormatDiagnostic(
3040      *this, inFunctionCall, Args[format_idx],
3041      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
3042      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3043    return;
3044  }
3045
3046  // Str - The format string.  NOTE: this is NOT null-terminated!
3047  StringRef StrRef = FExpr->getString();
3048  const char *Str = StrRef.data();
3049  unsigned StrLen = StrRef.size();
3050  const unsigned numDataArgs = NumArgs - firstDataArg;
3051
3052  // CHECK: empty format string?
3053  if (StrLen == 0 && numDataArgs > 0) {
3054    CheckFormatHandler::EmitFormatDiagnostic(
3055      *this, inFunctionCall, Args[format_idx],
3056      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
3057      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3058    return;
3059  }
3060
3061  if (Type == FST_Printf || Type == FST_NSString) {
3062    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
3063                         numDataArgs, (Type == FST_NSString),
3064                         Str, HasVAListArg, Args, NumArgs, format_idx,
3065                         inFunctionCall, CallType);
3066
3067    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
3068                                                  getLangOpts(),
3069                                                  Context.getTargetInfo()))
3070      H.DoneProcessing();
3071  } else if (Type == FST_Scanf) {
3072    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
3073                        Str, HasVAListArg, Args, NumArgs, format_idx,
3074                        inFunctionCall, CallType);
3075
3076    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
3077                                                 getLangOpts(),
3078                                                 Context.getTargetInfo()))
3079      H.DoneProcessing();
3080  } // TODO: handle other formats
3081}
3082
3083//===--- CHECK: Standard memory functions ---------------------------------===//
3084
3085/// \brief Determine whether the given type is a dynamic class type (e.g.,
3086/// whether it has a vtable).
3087static bool isDynamicClassType(QualType T) {
3088  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
3089    if (CXXRecordDecl *Definition = Record->getDefinition())
3090      if (Definition->isDynamicClass())
3091        return true;
3092
3093  return false;
3094}
3095
3096/// \brief If E is a sizeof expression, returns its argument expression,
3097/// otherwise returns NULL.
3098static const Expr *getSizeOfExprArg(const Expr* E) {
3099  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3100      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3101    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
3102      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
3103
3104  return 0;
3105}
3106
3107/// \brief If E is a sizeof expression, returns its argument type.
3108static QualType getSizeOfArgType(const Expr* E) {
3109  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3110      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3111    if (SizeOf->getKind() == clang::UETT_SizeOf)
3112      return SizeOf->getTypeOfArgument();
3113
3114  return QualType();
3115}
3116
3117/// \brief Check for dangerous or invalid arguments to memset().
3118///
3119/// This issues warnings on known problematic, dangerous or unspecified
3120/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
3121/// function calls.
3122///
3123/// \param Call The call expression to diagnose.
3124void Sema::CheckMemaccessArguments(const CallExpr *Call,
3125                                   unsigned BId,
3126                                   IdentifierInfo *FnName) {
3127  assert(BId != 0);
3128
3129  // It is possible to have a non-standard definition of memset.  Validate
3130  // we have enough arguments, and if not, abort further checking.
3131  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
3132  if (Call->getNumArgs() < ExpectedNumArgs)
3133    return;
3134
3135  unsigned LastArg = (BId == Builtin::BImemset ||
3136                      BId == Builtin::BIstrndup ? 1 : 2);
3137  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
3138  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
3139
3140  // We have special checking when the length is a sizeof expression.
3141  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
3142  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
3143  llvm::FoldingSetNodeID SizeOfArgID;
3144
3145  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
3146    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
3147    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
3148
3149    QualType DestTy = Dest->getType();
3150    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
3151      QualType PointeeTy = DestPtrTy->getPointeeType();
3152
3153      // Never warn about void type pointers. This can be used to suppress
3154      // false positives.
3155      if (PointeeTy->isVoidType())
3156        continue;
3157
3158      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
3159      // actually comparing the expressions for equality. Because computing the
3160      // expression IDs can be expensive, we only do this if the diagnostic is
3161      // enabled.
3162      if (SizeOfArg &&
3163          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
3164                                   SizeOfArg->getExprLoc())) {
3165        // We only compute IDs for expressions if the warning is enabled, and
3166        // cache the sizeof arg's ID.
3167        if (SizeOfArgID == llvm::FoldingSetNodeID())
3168          SizeOfArg->Profile(SizeOfArgID, Context, true);
3169        llvm::FoldingSetNodeID DestID;
3170        Dest->Profile(DestID, Context, true);
3171        if (DestID == SizeOfArgID) {
3172          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
3173          //       over sizeof(src) as well.
3174          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
3175          StringRef ReadableName = FnName->getName();
3176
3177          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
3178            if (UnaryOp->getOpcode() == UO_AddrOf)
3179              ActionIdx = 1; // If its an address-of operator, just remove it.
3180          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
3181            ActionIdx = 2; // If the pointee's size is sizeof(char),
3182                           // suggest an explicit length.
3183
3184          // If the function is defined as a builtin macro, do not show macro
3185          // expansion.
3186          SourceLocation SL = SizeOfArg->getExprLoc();
3187          SourceRange DSR = Dest->getSourceRange();
3188          SourceRange SSR = SizeOfArg->getSourceRange();
3189          SourceManager &SM  = PP.getSourceManager();
3190
3191          if (SM.isMacroArgExpansion(SL)) {
3192            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
3193            SL = SM.getSpellingLoc(SL);
3194            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
3195                             SM.getSpellingLoc(DSR.getEnd()));
3196            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
3197                             SM.getSpellingLoc(SSR.getEnd()));
3198          }
3199
3200          DiagRuntimeBehavior(SL, SizeOfArg,
3201                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
3202                                << ReadableName
3203                                << PointeeTy
3204                                << DestTy
3205                                << DSR
3206                                << SSR);
3207          DiagRuntimeBehavior(SL, SizeOfArg,
3208                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
3209                                << ActionIdx
3210                                << SSR);
3211
3212          break;
3213        }
3214      }
3215
3216      // Also check for cases where the sizeof argument is the exact same
3217      // type as the memory argument, and where it points to a user-defined
3218      // record type.
3219      if (SizeOfArgTy != QualType()) {
3220        if (PointeeTy->isRecordType() &&
3221            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
3222          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
3223                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
3224                                << FnName << SizeOfArgTy << ArgIdx
3225                                << PointeeTy << Dest->getSourceRange()
3226                                << LenExpr->getSourceRange());
3227          break;
3228        }
3229      }
3230
3231      // Always complain about dynamic classes.
3232      if (isDynamicClassType(PointeeTy)) {
3233
3234        unsigned OperationType = 0;
3235        // "overwritten" if we're warning about the destination for any call
3236        // but memcmp; otherwise a verb appropriate to the call.
3237        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
3238          if (BId == Builtin::BImemcpy)
3239            OperationType = 1;
3240          else if(BId == Builtin::BImemmove)
3241            OperationType = 2;
3242          else if (BId == Builtin::BImemcmp)
3243            OperationType = 3;
3244        }
3245
3246        DiagRuntimeBehavior(
3247          Dest->getExprLoc(), Dest,
3248          PDiag(diag::warn_dyn_class_memaccess)
3249            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
3250            << FnName << PointeeTy
3251            << OperationType
3252            << Call->getCallee()->getSourceRange());
3253      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
3254               BId != Builtin::BImemset)
3255        DiagRuntimeBehavior(
3256          Dest->getExprLoc(), Dest,
3257          PDiag(diag::warn_arc_object_memaccess)
3258            << ArgIdx << FnName << PointeeTy
3259            << Call->getCallee()->getSourceRange());
3260      else
3261        continue;
3262
3263      DiagRuntimeBehavior(
3264        Dest->getExprLoc(), Dest,
3265        PDiag(diag::note_bad_memaccess_silence)
3266          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
3267      break;
3268    }
3269  }
3270}
3271
3272// A little helper routine: ignore addition and subtraction of integer literals.
3273// This intentionally does not ignore all integer constant expressions because
3274// we don't want to remove sizeof().
3275static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
3276  Ex = Ex->IgnoreParenCasts();
3277
3278  for (;;) {
3279    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
3280    if (!BO || !BO->isAdditiveOp())
3281      break;
3282
3283    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
3284    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
3285
3286    if (isa<IntegerLiteral>(RHS))
3287      Ex = LHS;
3288    else if (isa<IntegerLiteral>(LHS))
3289      Ex = RHS;
3290    else
3291      break;
3292  }
3293
3294  return Ex;
3295}
3296
3297static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
3298                                                      ASTContext &Context) {
3299  // Only handle constant-sized or VLAs, but not flexible members.
3300  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
3301    // Only issue the FIXIT for arrays of size > 1.
3302    if (CAT->getSize().getSExtValue() <= 1)
3303      return false;
3304  } else if (!Ty->isVariableArrayType()) {
3305    return false;
3306  }
3307  return true;
3308}
3309
3310// Warn if the user has made the 'size' argument to strlcpy or strlcat
3311// be the size of the source, instead of the destination.
3312void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
3313                                    IdentifierInfo *FnName) {
3314
3315  // Don't crash if the user has the wrong number of arguments
3316  if (Call->getNumArgs() != 3)
3317    return;
3318
3319  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
3320  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
3321  const Expr *CompareWithSrc = NULL;
3322
3323  // Look for 'strlcpy(dst, x, sizeof(x))'
3324  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
3325    CompareWithSrc = Ex;
3326  else {
3327    // Look for 'strlcpy(dst, x, strlen(x))'
3328    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
3329      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
3330          && SizeCall->getNumArgs() == 1)
3331        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
3332    }
3333  }
3334
3335  if (!CompareWithSrc)
3336    return;
3337
3338  // Determine if the argument to sizeof/strlen is equal to the source
3339  // argument.  In principle there's all kinds of things you could do
3340  // here, for instance creating an == expression and evaluating it with
3341  // EvaluateAsBooleanCondition, but this uses a more direct technique:
3342  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
3343  if (!SrcArgDRE)
3344    return;
3345
3346  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
3347  if (!CompareWithSrcDRE ||
3348      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
3349    return;
3350
3351  const Expr *OriginalSizeArg = Call->getArg(2);
3352  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
3353    << OriginalSizeArg->getSourceRange() << FnName;
3354
3355  // Output a FIXIT hint if the destination is an array (rather than a
3356  // pointer to an array).  This could be enhanced to handle some
3357  // pointers if we know the actual size, like if DstArg is 'array+2'
3358  // we could say 'sizeof(array)-2'.
3359  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
3360  if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
3361    return;
3362
3363  SmallString<128> sizeString;
3364  llvm::raw_svector_ostream OS(sizeString);
3365  OS << "sizeof(";
3366  DstArg->printPretty(OS, 0, getPrintingPolicy());
3367  OS << ")";
3368
3369  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
3370    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
3371                                    OS.str());
3372}
3373
3374/// Check if two expressions refer to the same declaration.
3375static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
3376  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
3377    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
3378      return D1->getDecl() == D2->getDecl();
3379  return false;
3380}
3381
3382static const Expr *getStrlenExprArg(const Expr *E) {
3383  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
3384    const FunctionDecl *FD = CE->getDirectCallee();
3385    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
3386      return 0;
3387    return CE->getArg(0)->IgnoreParenCasts();
3388  }
3389  return 0;
3390}
3391
3392// Warn on anti-patterns as the 'size' argument to strncat.
3393// The correct size argument should look like following:
3394//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
3395void Sema::CheckStrncatArguments(const CallExpr *CE,
3396                                 IdentifierInfo *FnName) {
3397  // Don't crash if the user has the wrong number of arguments.
3398  if (CE->getNumArgs() < 3)
3399    return;
3400  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
3401  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
3402  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
3403
3404  // Identify common expressions, which are wrongly used as the size argument
3405  // to strncat and may lead to buffer overflows.
3406  unsigned PatternType = 0;
3407  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
3408    // - sizeof(dst)
3409    if (referToTheSameDecl(SizeOfArg, DstArg))
3410      PatternType = 1;
3411    // - sizeof(src)
3412    else if (referToTheSameDecl(SizeOfArg, SrcArg))
3413      PatternType = 2;
3414  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
3415    if (BE->getOpcode() == BO_Sub) {
3416      const Expr *L = BE->getLHS()->IgnoreParenCasts();
3417      const Expr *R = BE->getRHS()->IgnoreParenCasts();
3418      // - sizeof(dst) - strlen(dst)
3419      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
3420          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
3421        PatternType = 1;
3422      // - sizeof(src) - (anything)
3423      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
3424        PatternType = 2;
3425    }
3426  }
3427
3428  if (PatternType == 0)
3429    return;
3430
3431  // Generate the diagnostic.
3432  SourceLocation SL = LenArg->getLocStart();
3433  SourceRange SR = LenArg->getSourceRange();
3434  SourceManager &SM  = PP.getSourceManager();
3435
3436  // If the function is defined as a builtin macro, do not show macro expansion.
3437  if (SM.isMacroArgExpansion(SL)) {
3438    SL = SM.getSpellingLoc(SL);
3439    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
3440                     SM.getSpellingLoc(SR.getEnd()));
3441  }
3442
3443  // Check if the destination is an array (rather than a pointer to an array).
3444  QualType DstTy = DstArg->getType();
3445  bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
3446                                                                    Context);
3447  if (!isKnownSizeArray) {
3448    if (PatternType == 1)
3449      Diag(SL, diag::warn_strncat_wrong_size) << SR;
3450    else
3451      Diag(SL, diag::warn_strncat_src_size) << SR;
3452    return;
3453  }
3454
3455  if (PatternType == 1)
3456    Diag(SL, diag::warn_strncat_large_size) << SR;
3457  else
3458    Diag(SL, diag::warn_strncat_src_size) << SR;
3459
3460  SmallString<128> sizeString;
3461  llvm::raw_svector_ostream OS(sizeString);
3462  OS << "sizeof(";
3463  DstArg->printPretty(OS, 0, getPrintingPolicy());
3464  OS << ") - ";
3465  OS << "strlen(";
3466  DstArg->printPretty(OS, 0, getPrintingPolicy());
3467  OS << ") - 1";
3468
3469  Diag(SL, diag::note_strncat_wrong_size)
3470    << FixItHint::CreateReplacement(SR, OS.str());
3471}
3472
3473//===--- CHECK: Return Address of Stack Variable --------------------------===//
3474
3475static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3476                     Decl *ParentDecl);
3477static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3478                      Decl *ParentDecl);
3479
3480/// CheckReturnStackAddr - Check if a return statement returns the address
3481///   of a stack variable.
3482void
3483Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3484                           SourceLocation ReturnLoc) {
3485
3486  Expr *stackE = 0;
3487  SmallVector<DeclRefExpr *, 8> refVars;
3488
3489  // Perform checking for returned stack addresses, local blocks,
3490  // label addresses or references to temporaries.
3491  if (lhsType->isPointerType() ||
3492      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3493    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3494  } else if (lhsType->isReferenceType()) {
3495    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3496  }
3497
3498  if (stackE == 0)
3499    return; // Nothing suspicious was found.
3500
3501  SourceLocation diagLoc;
3502  SourceRange diagRange;
3503  if (refVars.empty()) {
3504    diagLoc = stackE->getLocStart();
3505    diagRange = stackE->getSourceRange();
3506  } else {
3507    // We followed through a reference variable. 'stackE' contains the
3508    // problematic expression but we will warn at the return statement pointing
3509    // at the reference variable. We will later display the "trail" of
3510    // reference variables using notes.
3511    diagLoc = refVars[0]->getLocStart();
3512    diagRange = refVars[0]->getSourceRange();
3513  }
3514
3515  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3516    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3517                                             : diag::warn_ret_stack_addr)
3518     << DR->getDecl()->getDeclName() << diagRange;
3519  } else if (isa<BlockExpr>(stackE)) { // local block.
3520    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3521  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3522    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3523  } else { // local temporary.
3524    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3525                                             : diag::warn_ret_local_temp_addr)
3526     << diagRange;
3527  }
3528
3529  // Display the "trail" of reference variables that we followed until we
3530  // found the problematic expression using notes.
3531  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3532    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3533    // If this var binds to another reference var, show the range of the next
3534    // var, otherwise the var binds to the problematic expression, in which case
3535    // show the range of the expression.
3536    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3537                                  : stackE->getSourceRange();
3538    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3539      << VD->getDeclName() << range;
3540  }
3541}
3542
3543/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3544///  check if the expression in a return statement evaluates to an address
3545///  to a location on the stack, a local block, an address of a label, or a
3546///  reference to local temporary. The recursion is used to traverse the
3547///  AST of the return expression, with recursion backtracking when we
3548///  encounter a subexpression that (1) clearly does not lead to one of the
3549///  above problematic expressions (2) is something we cannot determine leads to
3550///  a problematic expression based on such local checking.
3551///
3552///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3553///  the expression that they point to. Such variables are added to the
3554///  'refVars' vector so that we know what the reference variable "trail" was.
3555///
3556///  EvalAddr processes expressions that are pointers that are used as
3557///  references (and not L-values).  EvalVal handles all other values.
3558///  At the base case of the recursion is a check for the above problematic
3559///  expressions.
3560///
3561///  This implementation handles:
3562///
3563///   * pointer-to-pointer casts
3564///   * implicit conversions from array references to pointers
3565///   * taking the address of fields
3566///   * arbitrary interplay between "&" and "*" operators
3567///   * pointer arithmetic from an address of a stack variable
3568///   * taking the address of an array element where the array is on the stack
3569static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3570                      Decl *ParentDecl) {
3571  if (E->isTypeDependent())
3572      return NULL;
3573
3574  // We should only be called for evaluating pointer expressions.
3575  assert((E->getType()->isAnyPointerType() ||
3576          E->getType()->isBlockPointerType() ||
3577          E->getType()->isObjCQualifiedIdType()) &&
3578         "EvalAddr only works on pointers");
3579
3580  E = E->IgnoreParens();
3581
3582  // Our "symbolic interpreter" is just a dispatch off the currently
3583  // viewed AST node.  We then recursively traverse the AST by calling
3584  // EvalAddr and EvalVal appropriately.
3585  switch (E->getStmtClass()) {
3586  case Stmt::DeclRefExprClass: {
3587    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3588
3589    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3590      // If this is a reference variable, follow through to the expression that
3591      // it points to.
3592      if (V->hasLocalStorage() &&
3593          V->getType()->isReferenceType() && V->hasInit()) {
3594        // Add the reference variable to the "trail".
3595        refVars.push_back(DR);
3596        return EvalAddr(V->getInit(), refVars, ParentDecl);
3597      }
3598
3599    return NULL;
3600  }
3601
3602  case Stmt::UnaryOperatorClass: {
3603    // The only unary operator that make sense to handle here
3604    // is AddrOf.  All others don't make sense as pointers.
3605    UnaryOperator *U = cast<UnaryOperator>(E);
3606
3607    if (U->getOpcode() == UO_AddrOf)
3608      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3609    else
3610      return NULL;
3611  }
3612
3613  case Stmt::BinaryOperatorClass: {
3614    // Handle pointer arithmetic.  All other binary operators are not valid
3615    // in this context.
3616    BinaryOperator *B = cast<BinaryOperator>(E);
3617    BinaryOperatorKind op = B->getOpcode();
3618
3619    if (op != BO_Add && op != BO_Sub)
3620      return NULL;
3621
3622    Expr *Base = B->getLHS();
3623
3624    // Determine which argument is the real pointer base.  It could be
3625    // the RHS argument instead of the LHS.
3626    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3627
3628    assert (Base->getType()->isPointerType());
3629    return EvalAddr(Base, refVars, ParentDecl);
3630  }
3631
3632  // For conditional operators we need to see if either the LHS or RHS are
3633  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3634  case Stmt::ConditionalOperatorClass: {
3635    ConditionalOperator *C = cast<ConditionalOperator>(E);
3636
3637    // Handle the GNU extension for missing LHS.
3638    if (Expr *lhsExpr = C->getLHS()) {
3639    // In C++, we can have a throw-expression, which has 'void' type.
3640      if (!lhsExpr->getType()->isVoidType())
3641        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3642          return LHS;
3643    }
3644
3645    // In C++, we can have a throw-expression, which has 'void' type.
3646    if (C->getRHS()->getType()->isVoidType())
3647      return NULL;
3648
3649    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3650  }
3651
3652  case Stmt::BlockExprClass:
3653    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3654      return E; // local block.
3655    return NULL;
3656
3657  case Stmt::AddrLabelExprClass:
3658    return E; // address of label.
3659
3660  case Stmt::ExprWithCleanupsClass:
3661    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3662                    ParentDecl);
3663
3664  // For casts, we need to handle conversions from arrays to
3665  // pointer values, and pointer-to-pointer conversions.
3666  case Stmt::ImplicitCastExprClass:
3667  case Stmt::CStyleCastExprClass:
3668  case Stmt::CXXFunctionalCastExprClass:
3669  case Stmt::ObjCBridgedCastExprClass:
3670  case Stmt::CXXStaticCastExprClass:
3671  case Stmt::CXXDynamicCastExprClass:
3672  case Stmt::CXXConstCastExprClass:
3673  case Stmt::CXXReinterpretCastExprClass: {
3674    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3675    switch (cast<CastExpr>(E)->getCastKind()) {
3676    case CK_BitCast:
3677    case CK_LValueToRValue:
3678    case CK_NoOp:
3679    case CK_BaseToDerived:
3680    case CK_DerivedToBase:
3681    case CK_UncheckedDerivedToBase:
3682    case CK_Dynamic:
3683    case CK_CPointerToObjCPointerCast:
3684    case CK_BlockPointerToObjCPointerCast:
3685    case CK_AnyPointerToBlockPointerCast:
3686      return EvalAddr(SubExpr, refVars, ParentDecl);
3687
3688    case CK_ArrayToPointerDecay:
3689      return EvalVal(SubExpr, refVars, ParentDecl);
3690
3691    default:
3692      return 0;
3693    }
3694  }
3695
3696  case Stmt::MaterializeTemporaryExprClass:
3697    if (Expr *Result = EvalAddr(
3698                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3699                                refVars, ParentDecl))
3700      return Result;
3701
3702    return E;
3703
3704  // Everything else: we simply don't reason about them.
3705  default:
3706    return NULL;
3707  }
3708}
3709
3710
3711///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3712///   See the comments for EvalAddr for more details.
3713static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3714                     Decl *ParentDecl) {
3715do {
3716  // We should only be called for evaluating non-pointer expressions, or
3717  // expressions with a pointer type that are not used as references but instead
3718  // are l-values (e.g., DeclRefExpr with a pointer type).
3719
3720  // Our "symbolic interpreter" is just a dispatch off the currently
3721  // viewed AST node.  We then recursively traverse the AST by calling
3722  // EvalAddr and EvalVal appropriately.
3723
3724  E = E->IgnoreParens();
3725  switch (E->getStmtClass()) {
3726  case Stmt::ImplicitCastExprClass: {
3727    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3728    if (IE->getValueKind() == VK_LValue) {
3729      E = IE->getSubExpr();
3730      continue;
3731    }
3732    return NULL;
3733  }
3734
3735  case Stmt::ExprWithCleanupsClass:
3736    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3737
3738  case Stmt::DeclRefExprClass: {
3739    // When we hit a DeclRefExpr we are looking at code that refers to a
3740    // variable's name. If it's not a reference variable we check if it has
3741    // local storage within the function, and if so, return the expression.
3742    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3743
3744    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3745      // Check if it refers to itself, e.g. "int& i = i;".
3746      if (V == ParentDecl)
3747        return DR;
3748
3749      if (V->hasLocalStorage()) {
3750        if (!V->getType()->isReferenceType())
3751          return DR;
3752
3753        // Reference variable, follow through to the expression that
3754        // it points to.
3755        if (V->hasInit()) {
3756          // Add the reference variable to the "trail".
3757          refVars.push_back(DR);
3758          return EvalVal(V->getInit(), refVars, V);
3759        }
3760      }
3761    }
3762
3763    return NULL;
3764  }
3765
3766  case Stmt::UnaryOperatorClass: {
3767    // The only unary operator that make sense to handle here
3768    // is Deref.  All others don't resolve to a "name."  This includes
3769    // handling all sorts of rvalues passed to a unary operator.
3770    UnaryOperator *U = cast<UnaryOperator>(E);
3771
3772    if (U->getOpcode() == UO_Deref)
3773      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3774
3775    return NULL;
3776  }
3777
3778  case Stmt::ArraySubscriptExprClass: {
3779    // Array subscripts are potential references to data on the stack.  We
3780    // retrieve the DeclRefExpr* for the array variable if it indeed
3781    // has local storage.
3782    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3783  }
3784
3785  case Stmt::ConditionalOperatorClass: {
3786    // For conditional operators we need to see if either the LHS or RHS are
3787    // non-NULL Expr's.  If one is non-NULL, we return it.
3788    ConditionalOperator *C = cast<ConditionalOperator>(E);
3789
3790    // Handle the GNU extension for missing LHS.
3791    if (Expr *lhsExpr = C->getLHS())
3792      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3793        return LHS;
3794
3795    return EvalVal(C->getRHS(), refVars, ParentDecl);
3796  }
3797
3798  // Accesses to members are potential references to data on the stack.
3799  case Stmt::MemberExprClass: {
3800    MemberExpr *M = cast<MemberExpr>(E);
3801
3802    // Check for indirect access.  We only want direct field accesses.
3803    if (M->isArrow())
3804      return NULL;
3805
3806    // Check whether the member type is itself a reference, in which case
3807    // we're not going to refer to the member, but to what the member refers to.
3808    if (M->getMemberDecl()->getType()->isReferenceType())
3809      return NULL;
3810
3811    return EvalVal(M->getBase(), refVars, ParentDecl);
3812  }
3813
3814  case Stmt::MaterializeTemporaryExprClass:
3815    if (Expr *Result = EvalVal(
3816                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3817                               refVars, ParentDecl))
3818      return Result;
3819
3820    return E;
3821
3822  default:
3823    // Check that we don't return or take the address of a reference to a
3824    // temporary. This is only useful in C++.
3825    if (!E->isTypeDependent() && E->isRValue())
3826      return E;
3827
3828    // Everything else: we simply don't reason about them.
3829    return NULL;
3830  }
3831} while (true);
3832}
3833
3834//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3835
3836/// Check for comparisons of floating point operands using != and ==.
3837/// Issue a warning if these are no self-comparisons, as they are not likely
3838/// to do what the programmer intended.
3839void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3840  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3841  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3842
3843  // Special case: check for x == x (which is OK).
3844  // Do not emit warnings for such cases.
3845  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3846    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3847      if (DRL->getDecl() == DRR->getDecl())
3848        return;
3849
3850
3851  // Special case: check for comparisons against literals that can be exactly
3852  //  represented by APFloat.  In such cases, do not emit a warning.  This
3853  //  is a heuristic: often comparison against such literals are used to
3854  //  detect if a value in a variable has not changed.  This clearly can
3855  //  lead to false negatives.
3856  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3857    if (FLL->isExact())
3858      return;
3859  } else
3860    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
3861      if (FLR->isExact())
3862        return;
3863
3864  // Check for comparisons with builtin types.
3865  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3866    if (CL->isBuiltinCall())
3867      return;
3868
3869  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3870    if (CR->isBuiltinCall())
3871      return;
3872
3873  // Emit the diagnostic.
3874  Diag(Loc, diag::warn_floatingpoint_eq)
3875    << LHS->getSourceRange() << RHS->getSourceRange();
3876}
3877
3878//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3879//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3880
3881namespace {
3882
3883/// Structure recording the 'active' range of an integer-valued
3884/// expression.
3885struct IntRange {
3886  /// The number of bits active in the int.
3887  unsigned Width;
3888
3889  /// True if the int is known not to have negative values.
3890  bool NonNegative;
3891
3892  IntRange(unsigned Width, bool NonNegative)
3893    : Width(Width), NonNegative(NonNegative)
3894  {}
3895
3896  /// Returns the range of the bool type.
3897  static IntRange forBoolType() {
3898    return IntRange(1, true);
3899  }
3900
3901  /// Returns the range of an opaque value of the given integral type.
3902  static IntRange forValueOfType(ASTContext &C, QualType T) {
3903    return forValueOfCanonicalType(C,
3904                          T->getCanonicalTypeInternal().getTypePtr());
3905  }
3906
3907  /// Returns the range of an opaque value of a canonical integral type.
3908  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3909    assert(T->isCanonicalUnqualified());
3910
3911    if (const VectorType *VT = dyn_cast<VectorType>(T))
3912      T = VT->getElementType().getTypePtr();
3913    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3914      T = CT->getElementType().getTypePtr();
3915
3916    // For enum types, use the known bit width of the enumerators.
3917    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3918      EnumDecl *Enum = ET->getDecl();
3919      if (!Enum->isCompleteDefinition())
3920        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3921
3922      unsigned NumPositive = Enum->getNumPositiveBits();
3923      unsigned NumNegative = Enum->getNumNegativeBits();
3924
3925      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3926    }
3927
3928    const BuiltinType *BT = cast<BuiltinType>(T);
3929    assert(BT->isInteger());
3930
3931    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3932  }
3933
3934  /// Returns the "target" range of a canonical integral type, i.e.
3935  /// the range of values expressible in the type.
3936  ///
3937  /// This matches forValueOfCanonicalType except that enums have the
3938  /// full range of their type, not the range of their enumerators.
3939  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3940    assert(T->isCanonicalUnqualified());
3941
3942    if (const VectorType *VT = dyn_cast<VectorType>(T))
3943      T = VT->getElementType().getTypePtr();
3944    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3945      T = CT->getElementType().getTypePtr();
3946    if (const EnumType *ET = dyn_cast<EnumType>(T))
3947      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3948
3949    const BuiltinType *BT = cast<BuiltinType>(T);
3950    assert(BT->isInteger());
3951
3952    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3953  }
3954
3955  /// Returns the supremum of two ranges: i.e. their conservative merge.
3956  static IntRange join(IntRange L, IntRange R) {
3957    return IntRange(std::max(L.Width, R.Width),
3958                    L.NonNegative && R.NonNegative);
3959  }
3960
3961  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3962  static IntRange meet(IntRange L, IntRange R) {
3963    return IntRange(std::min(L.Width, R.Width),
3964                    L.NonNegative || R.NonNegative);
3965  }
3966};
3967
3968static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
3969                              unsigned MaxWidth) {
3970  if (value.isSigned() && value.isNegative())
3971    return IntRange(value.getMinSignedBits(), false);
3972
3973  if (value.getBitWidth() > MaxWidth)
3974    value = value.trunc(MaxWidth);
3975
3976  // isNonNegative() just checks the sign bit without considering
3977  // signedness.
3978  return IntRange(value.getActiveBits(), true);
3979}
3980
3981static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3982                              unsigned MaxWidth) {
3983  if (result.isInt())
3984    return GetValueRange(C, result.getInt(), MaxWidth);
3985
3986  if (result.isVector()) {
3987    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3988    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3989      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3990      R = IntRange::join(R, El);
3991    }
3992    return R;
3993  }
3994
3995  if (result.isComplexInt()) {
3996    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3997    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3998    return IntRange::join(R, I);
3999  }
4000
4001  // This can happen with lossless casts to intptr_t of "based" lvalues.
4002  // Assume it might use arbitrary bits.
4003  // FIXME: The only reason we need to pass the type in here is to get
4004  // the sign right on this one case.  It would be nice if APValue
4005  // preserved this.
4006  assert(result.isLValue() || result.isAddrLabelDiff());
4007  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
4008}
4009
4010/// Pseudo-evaluate the given integer expression, estimating the
4011/// range of values it might take.
4012///
4013/// \param MaxWidth - the width to which the value will be truncated
4014static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
4015  E = E->IgnoreParens();
4016
4017  // Try a full evaluation first.
4018  Expr::EvalResult result;
4019  if (E->EvaluateAsRValue(result, C))
4020    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
4021
4022  // I think we only want to look through implicit casts here; if the
4023  // user has an explicit widening cast, we should treat the value as
4024  // being of the new, wider type.
4025  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
4026    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
4027      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
4028
4029    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
4030
4031    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
4032
4033    // Assume that non-integer casts can span the full range of the type.
4034    if (!isIntegerCast)
4035      return OutputTypeRange;
4036
4037    IntRange SubRange
4038      = GetExprRange(C, CE->getSubExpr(),
4039                     std::min(MaxWidth, OutputTypeRange.Width));
4040
4041    // Bail out if the subexpr's range is as wide as the cast type.
4042    if (SubRange.Width >= OutputTypeRange.Width)
4043      return OutputTypeRange;
4044
4045    // Otherwise, we take the smaller width, and we're non-negative if
4046    // either the output type or the subexpr is.
4047    return IntRange(SubRange.Width,
4048                    SubRange.NonNegative || OutputTypeRange.NonNegative);
4049  }
4050
4051  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
4052    // If we can fold the condition, just take that operand.
4053    bool CondResult;
4054    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
4055      return GetExprRange(C, CondResult ? CO->getTrueExpr()
4056                                        : CO->getFalseExpr(),
4057                          MaxWidth);
4058
4059    // Otherwise, conservatively merge.
4060    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
4061    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
4062    return IntRange::join(L, R);
4063  }
4064
4065  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4066    switch (BO->getOpcode()) {
4067
4068    // Boolean-valued operations are single-bit and positive.
4069    case BO_LAnd:
4070    case BO_LOr:
4071    case BO_LT:
4072    case BO_GT:
4073    case BO_LE:
4074    case BO_GE:
4075    case BO_EQ:
4076    case BO_NE:
4077      return IntRange::forBoolType();
4078
4079    // The type of the assignments is the type of the LHS, so the RHS
4080    // is not necessarily the same type.
4081    case BO_MulAssign:
4082    case BO_DivAssign:
4083    case BO_RemAssign:
4084    case BO_AddAssign:
4085    case BO_SubAssign:
4086    case BO_XorAssign:
4087    case BO_OrAssign:
4088      // TODO: bitfields?
4089      return IntRange::forValueOfType(C, E->getType());
4090
4091    // Simple assignments just pass through the RHS, which will have
4092    // been coerced to the LHS type.
4093    case BO_Assign:
4094      // TODO: bitfields?
4095      return GetExprRange(C, BO->getRHS(), MaxWidth);
4096
4097    // Operations with opaque sources are black-listed.
4098    case BO_PtrMemD:
4099    case BO_PtrMemI:
4100      return IntRange::forValueOfType(C, E->getType());
4101
4102    // Bitwise-and uses the *infinum* of the two source ranges.
4103    case BO_And:
4104    case BO_AndAssign:
4105      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
4106                            GetExprRange(C, BO->getRHS(), MaxWidth));
4107
4108    // Left shift gets black-listed based on a judgement call.
4109    case BO_Shl:
4110      // ...except that we want to treat '1 << (blah)' as logically
4111      // positive.  It's an important idiom.
4112      if (IntegerLiteral *I
4113            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
4114        if (I->getValue() == 1) {
4115          IntRange R = IntRange::forValueOfType(C, E->getType());
4116          return IntRange(R.Width, /*NonNegative*/ true);
4117        }
4118      }
4119      // fallthrough
4120
4121    case BO_ShlAssign:
4122      return IntRange::forValueOfType(C, E->getType());
4123
4124    // Right shift by a constant can narrow its left argument.
4125    case BO_Shr:
4126    case BO_ShrAssign: {
4127      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4128
4129      // If the shift amount is a positive constant, drop the width by
4130      // that much.
4131      llvm::APSInt shift;
4132      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
4133          shift.isNonNegative()) {
4134        unsigned zext = shift.getZExtValue();
4135        if (zext >= L.Width)
4136          L.Width = (L.NonNegative ? 0 : 1);
4137        else
4138          L.Width -= zext;
4139      }
4140
4141      return L;
4142    }
4143
4144    // Comma acts as its right operand.
4145    case BO_Comma:
4146      return GetExprRange(C, BO->getRHS(), MaxWidth);
4147
4148    // Black-list pointer subtractions.
4149    case BO_Sub:
4150      if (BO->getLHS()->getType()->isPointerType())
4151        return IntRange::forValueOfType(C, E->getType());
4152      break;
4153
4154    // The width of a division result is mostly determined by the size
4155    // of the LHS.
4156    case BO_Div: {
4157      // Don't 'pre-truncate' the operands.
4158      unsigned opWidth = C.getIntWidth(E->getType());
4159      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4160
4161      // If the divisor is constant, use that.
4162      llvm::APSInt divisor;
4163      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
4164        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
4165        if (log2 >= L.Width)
4166          L.Width = (L.NonNegative ? 0 : 1);
4167        else
4168          L.Width = std::min(L.Width - log2, MaxWidth);
4169        return L;
4170      }
4171
4172      // Otherwise, just use the LHS's width.
4173      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4174      return IntRange(L.Width, L.NonNegative && R.NonNegative);
4175    }
4176
4177    // The result of a remainder can't be larger than the result of
4178    // either side.
4179    case BO_Rem: {
4180      // Don't 'pre-truncate' the operands.
4181      unsigned opWidth = C.getIntWidth(E->getType());
4182      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4183      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4184
4185      IntRange meet = IntRange::meet(L, R);
4186      meet.Width = std::min(meet.Width, MaxWidth);
4187      return meet;
4188    }
4189
4190    // The default behavior is okay for these.
4191    case BO_Mul:
4192    case BO_Add:
4193    case BO_Xor:
4194    case BO_Or:
4195      break;
4196    }
4197
4198    // The default case is to treat the operation as if it were closed
4199    // on the narrowest type that encompasses both operands.
4200    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4201    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
4202    return IntRange::join(L, R);
4203  }
4204
4205  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
4206    switch (UO->getOpcode()) {
4207    // Boolean-valued operations are white-listed.
4208    case UO_LNot:
4209      return IntRange::forBoolType();
4210
4211    // Operations with opaque sources are black-listed.
4212    case UO_Deref:
4213    case UO_AddrOf: // should be impossible
4214      return IntRange::forValueOfType(C, E->getType());
4215
4216    default:
4217      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
4218    }
4219  }
4220
4221  if (dyn_cast<OffsetOfExpr>(E)) {
4222    IntRange::forValueOfType(C, E->getType());
4223  }
4224
4225  if (FieldDecl *BitField = E->getBitField())
4226    return IntRange(BitField->getBitWidthValue(C),
4227                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
4228
4229  return IntRange::forValueOfType(C, E->getType());
4230}
4231
4232static IntRange GetExprRange(ASTContext &C, Expr *E) {
4233  return GetExprRange(C, E, C.getIntWidth(E->getType()));
4234}
4235
4236/// Checks whether the given value, which currently has the given
4237/// source semantics, has the same value when coerced through the
4238/// target semantics.
4239static bool IsSameFloatAfterCast(const llvm::APFloat &value,
4240                                 const llvm::fltSemantics &Src,
4241                                 const llvm::fltSemantics &Tgt) {
4242  llvm::APFloat truncated = value;
4243
4244  bool ignored;
4245  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
4246  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
4247
4248  return truncated.bitwiseIsEqual(value);
4249}
4250
4251/// Checks whether the given value, which currently has the given
4252/// source semantics, has the same value when coerced through the
4253/// target semantics.
4254///
4255/// The value might be a vector of floats (or a complex number).
4256static bool IsSameFloatAfterCast(const APValue &value,
4257                                 const llvm::fltSemantics &Src,
4258                                 const llvm::fltSemantics &Tgt) {
4259  if (value.isFloat())
4260    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
4261
4262  if (value.isVector()) {
4263    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
4264      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
4265        return false;
4266    return true;
4267  }
4268
4269  assert(value.isComplexFloat());
4270  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
4271          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
4272}
4273
4274static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
4275
4276static bool IsZero(Sema &S, Expr *E) {
4277  // Suppress cases where we are comparing against an enum constant.
4278  if (const DeclRefExpr *DR =
4279      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
4280    if (isa<EnumConstantDecl>(DR->getDecl()))
4281      return false;
4282
4283  // Suppress cases where the '0' value is expanded from a macro.
4284  if (E->getLocStart().isMacroID())
4285    return false;
4286
4287  llvm::APSInt Value;
4288  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
4289}
4290
4291static bool HasEnumType(Expr *E) {
4292  // Strip off implicit integral promotions.
4293  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
4294    if (ICE->getCastKind() != CK_IntegralCast &&
4295        ICE->getCastKind() != CK_NoOp)
4296      break;
4297    E = ICE->getSubExpr();
4298  }
4299
4300  return E->getType()->isEnumeralType();
4301}
4302
4303static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
4304  BinaryOperatorKind op = E->getOpcode();
4305  if (E->isValueDependent())
4306    return;
4307
4308  if (op == BO_LT && IsZero(S, E->getRHS())) {
4309    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4310      << "< 0" << "false" << HasEnumType(E->getLHS())
4311      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4312  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
4313    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4314      << ">= 0" << "true" << HasEnumType(E->getLHS())
4315      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4316  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
4317    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4318      << "0 >" << "false" << HasEnumType(E->getRHS())
4319      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4320  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
4321    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4322      << "0 <=" << "true" << HasEnumType(E->getRHS())
4323      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4324  }
4325}
4326
4327static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
4328                                         Expr *Constant, Expr *Other,
4329                                         llvm::APSInt Value,
4330                                         bool RhsConstant) {
4331  BinaryOperatorKind op = E->getOpcode();
4332  QualType OtherT = Other->getType();
4333  QualType ConstantT = Constant->getType();
4334  if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
4335    return;
4336  assert((OtherT->isIntegerType() && ConstantT->isIntegerType())
4337         && "comparison with non-integer type");
4338  // FIXME. handle cases for signedness to catch (signed char)N == 200
4339  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
4340  IntRange LitRange = GetValueRange(S.Context, Value, Value.getBitWidth());
4341  if (OtherRange.Width >= LitRange.Width)
4342    return;
4343  bool IsTrue = true;
4344  if (op == BO_EQ)
4345    IsTrue = false;
4346  else if (op == BO_NE)
4347    IsTrue = true;
4348  else if (RhsConstant) {
4349    if (op == BO_GT || op == BO_GE)
4350      IsTrue = !LitRange.NonNegative;
4351    else // op == BO_LT || op == BO_LE
4352      IsTrue = LitRange.NonNegative;
4353  } else {
4354    if (op == BO_LT || op == BO_LE)
4355      IsTrue = !LitRange.NonNegative;
4356    else // op == BO_GT || op == BO_GE
4357      IsTrue = LitRange.NonNegative;
4358  }
4359  SmallString<16> PrettySourceValue(Value.toString(10));
4360  S.Diag(E->getOperatorLoc(), diag::warn_out_of_range_compare)
4361  << PrettySourceValue << OtherT << IsTrue
4362  << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4363}
4364
4365/// Analyze the operands of the given comparison.  Implements the
4366/// fallback case from AnalyzeComparison.
4367static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
4368  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4369  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4370}
4371
4372/// \brief Implements -Wsign-compare.
4373///
4374/// \param E the binary operator to check for warnings
4375static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
4376  // The type the comparison is being performed in.
4377  QualType T = E->getLHS()->getType();
4378  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
4379         && "comparison with mismatched types");
4380  if (E->isValueDependent())
4381    return AnalyzeImpConvsInComparison(S, E);
4382
4383  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
4384  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
4385
4386  bool IsComparisonConstant = false;
4387
4388  // Check whether an integer constant comparison results in a value
4389  // of 'true' or 'false'.
4390  if (T->isIntegralType(S.Context)) {
4391    llvm::APSInt RHSValue;
4392    bool IsRHSIntegralLiteral =
4393      RHS->isIntegerConstantExpr(RHSValue, S.Context);
4394    llvm::APSInt LHSValue;
4395    bool IsLHSIntegralLiteral =
4396      LHS->isIntegerConstantExpr(LHSValue, S.Context);
4397    if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
4398        DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
4399    else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
4400      DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
4401    else
4402      IsComparisonConstant =
4403        (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
4404  } else if (!T->hasUnsignedIntegerRepresentation())
4405      IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
4406
4407  // We don't do anything special if this isn't an unsigned integral
4408  // comparison:  we're only interested in integral comparisons, and
4409  // signed comparisons only happen in cases we don't care to warn about.
4410  //
4411  // We also don't care about value-dependent expressions or expressions
4412  // whose result is a constant.
4413  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
4414    return AnalyzeImpConvsInComparison(S, E);
4415
4416  // Check to see if one of the (unmodified) operands is of different
4417  // signedness.
4418  Expr *signedOperand, *unsignedOperand;
4419  if (LHS->getType()->hasSignedIntegerRepresentation()) {
4420    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
4421           "unsigned comparison between two signed integer expressions?");
4422    signedOperand = LHS;
4423    unsignedOperand = RHS;
4424  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
4425    signedOperand = RHS;
4426    unsignedOperand = LHS;
4427  } else {
4428    CheckTrivialUnsignedComparison(S, E);
4429    return AnalyzeImpConvsInComparison(S, E);
4430  }
4431
4432  // Otherwise, calculate the effective range of the signed operand.
4433  IntRange signedRange = GetExprRange(S.Context, signedOperand);
4434
4435  // Go ahead and analyze implicit conversions in the operands.  Note
4436  // that we skip the implicit conversions on both sides.
4437  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
4438  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
4439
4440  // If the signed range is non-negative, -Wsign-compare won't fire,
4441  // but we should still check for comparisons which are always true
4442  // or false.
4443  if (signedRange.NonNegative)
4444    return CheckTrivialUnsignedComparison(S, E);
4445
4446  // For (in)equality comparisons, if the unsigned operand is a
4447  // constant which cannot collide with a overflowed signed operand,
4448  // then reinterpreting the signed operand as unsigned will not
4449  // change the result of the comparison.
4450  if (E->isEqualityOp()) {
4451    unsigned comparisonWidth = S.Context.getIntWidth(T);
4452    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
4453
4454    // We should never be unable to prove that the unsigned operand is
4455    // non-negative.
4456    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
4457
4458    if (unsignedRange.Width < comparisonWidth)
4459      return;
4460  }
4461
4462  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
4463    S.PDiag(diag::warn_mixed_sign_comparison)
4464      << LHS->getType() << RHS->getType()
4465      << LHS->getSourceRange() << RHS->getSourceRange());
4466}
4467
4468/// Analyzes an attempt to assign the given value to a bitfield.
4469///
4470/// Returns true if there was something fishy about the attempt.
4471static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
4472                                      SourceLocation InitLoc) {
4473  assert(Bitfield->isBitField());
4474  if (Bitfield->isInvalidDecl())
4475    return false;
4476
4477  // White-list bool bitfields.
4478  if (Bitfield->getType()->isBooleanType())
4479    return false;
4480
4481  // Ignore value- or type-dependent expressions.
4482  if (Bitfield->getBitWidth()->isValueDependent() ||
4483      Bitfield->getBitWidth()->isTypeDependent() ||
4484      Init->isValueDependent() ||
4485      Init->isTypeDependent())
4486    return false;
4487
4488  Expr *OriginalInit = Init->IgnoreParenImpCasts();
4489
4490  llvm::APSInt Value;
4491  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
4492    return false;
4493
4494  unsigned OriginalWidth = Value.getBitWidth();
4495  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
4496
4497  if (OriginalWidth <= FieldWidth)
4498    return false;
4499
4500  // Compute the value which the bitfield will contain.
4501  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
4502  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
4503
4504  // Check whether the stored value is equal to the original value.
4505  TruncatedValue = TruncatedValue.extend(OriginalWidth);
4506  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
4507    return false;
4508
4509  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4510  // therefore don't strictly fit into a signed bitfield of width 1.
4511  if (FieldWidth == 1 && Value == 1)
4512    return false;
4513
4514  std::string PrettyValue = Value.toString(10);
4515  std::string PrettyTrunc = TruncatedValue.toString(10);
4516
4517  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4518    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4519    << Init->getSourceRange();
4520
4521  return true;
4522}
4523
4524/// Analyze the given simple or compound assignment for warning-worthy
4525/// operations.
4526static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4527  // Just recurse on the LHS.
4528  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4529
4530  // We want to recurse on the RHS as normal unless we're assigning to
4531  // a bitfield.
4532  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
4533    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4534                                  E->getOperatorLoc())) {
4535      // Recurse, ignoring any implicit conversions on the RHS.
4536      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4537                                        E->getOperatorLoc());
4538    }
4539  }
4540
4541  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4542}
4543
4544/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4545static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4546                            SourceLocation CContext, unsigned diag,
4547                            bool pruneControlFlow = false) {
4548  if (pruneControlFlow) {
4549    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4550                          S.PDiag(diag)
4551                            << SourceType << T << E->getSourceRange()
4552                            << SourceRange(CContext));
4553    return;
4554  }
4555  S.Diag(E->getExprLoc(), diag)
4556    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4557}
4558
4559/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4560static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4561                            SourceLocation CContext, unsigned diag,
4562                            bool pruneControlFlow = false) {
4563  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4564}
4565
4566/// Diagnose an implicit cast from a literal expression. Does not warn when the
4567/// cast wouldn't lose information.
4568void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4569                                    SourceLocation CContext) {
4570  // Try to convert the literal exactly to an integer. If we can, don't warn.
4571  bool isExact = false;
4572  const llvm::APFloat &Value = FL->getValue();
4573  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4574                            T->hasUnsignedIntegerRepresentation());
4575  if (Value.convertToInteger(IntegerValue,
4576                             llvm::APFloat::rmTowardZero, &isExact)
4577      == llvm::APFloat::opOK && isExact)
4578    return;
4579
4580  SmallString<16> PrettySourceValue;
4581  Value.toString(PrettySourceValue);
4582  SmallString<16> PrettyTargetValue;
4583  if (T->isSpecificBuiltinType(BuiltinType::Bool))
4584    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
4585  else
4586    IntegerValue.toString(PrettyTargetValue);
4587
4588  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4589    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
4590    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
4591}
4592
4593std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4594  if (!Range.Width) return "0";
4595
4596  llvm::APSInt ValueInRange = Value;
4597  ValueInRange.setIsSigned(!Range.NonNegative);
4598  ValueInRange = ValueInRange.trunc(Range.Width);
4599  return ValueInRange.toString(10);
4600}
4601
4602static bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
4603  if (!isa<ImplicitCastExpr>(Ex))
4604    return false;
4605
4606  Expr *InnerE = Ex->IgnoreParenImpCasts();
4607  const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
4608  const Type *Source =
4609    S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4610  if (Target->isDependentType())
4611    return false;
4612
4613  const BuiltinType *FloatCandidateBT =
4614    dyn_cast<BuiltinType>(ToBool ? Source : Target);
4615  const Type *BoolCandidateType = ToBool ? Target : Source;
4616
4617  return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
4618          FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
4619}
4620
4621void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
4622                                      SourceLocation CC) {
4623  unsigned NumArgs = TheCall->getNumArgs();
4624  for (unsigned i = 0; i < NumArgs; ++i) {
4625    Expr *CurrA = TheCall->getArg(i);
4626    if (!IsImplicitBoolFloatConversion(S, CurrA, true))
4627      continue;
4628
4629    bool IsSwapped = ((i > 0) &&
4630        IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
4631    IsSwapped |= ((i < (NumArgs - 1)) &&
4632        IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
4633    if (IsSwapped) {
4634      // Warn on this floating-point to bool conversion.
4635      DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
4636                      CurrA->getType(), CC,
4637                      diag::warn_impcast_floating_point_to_bool);
4638    }
4639  }
4640}
4641
4642void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4643                             SourceLocation CC, bool *ICContext = 0) {
4644  if (E->isTypeDependent() || E->isValueDependent()) return;
4645
4646  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4647  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4648  if (Source == Target) return;
4649  if (Target->isDependentType()) return;
4650
4651  // If the conversion context location is invalid don't complain. We also
4652  // don't want to emit a warning if the issue occurs from the expansion of
4653  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4654  // delay this check as long as possible. Once we detect we are in that
4655  // scenario, we just return.
4656  if (CC.isInvalid())
4657    return;
4658
4659  // Diagnose implicit casts to bool.
4660  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4661    if (isa<StringLiteral>(E))
4662      // Warn on string literal to bool.  Checks for string literals in logical
4663      // expressions, for instances, assert(0 && "error here"), is prevented
4664      // by a check in AnalyzeImplicitConversions().
4665      return DiagnoseImpCast(S, E, T, CC,
4666                             diag::warn_impcast_string_literal_to_bool);
4667    if (Source->isFunctionType()) {
4668      // Warn on function to bool. Checks free functions and static member
4669      // functions. Weakly imported functions are excluded from the check,
4670      // since it's common to test their value to check whether the linker
4671      // found a definition for them.
4672      ValueDecl *D = 0;
4673      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4674        D = R->getDecl();
4675      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4676        D = M->getMemberDecl();
4677      }
4678
4679      if (D && !D->isWeak()) {
4680        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4681          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4682            << F << E->getSourceRange() << SourceRange(CC);
4683          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4684            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4685          QualType ReturnType;
4686          UnresolvedSet<4> NonTemplateOverloads;
4687          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
4688          if (!ReturnType.isNull()
4689              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4690            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4691              << FixItHint::CreateInsertion(
4692                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4693          return;
4694        }
4695      }
4696    }
4697  }
4698
4699  // Strip vector types.
4700  if (isa<VectorType>(Source)) {
4701    if (!isa<VectorType>(Target)) {
4702      if (S.SourceMgr.isInSystemMacro(CC))
4703        return;
4704      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4705    }
4706
4707    // If the vector cast is cast between two vectors of the same size, it is
4708    // a bitcast, not a conversion.
4709    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4710      return;
4711
4712    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4713    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4714  }
4715
4716  // Strip complex types.
4717  if (isa<ComplexType>(Source)) {
4718    if (!isa<ComplexType>(Target)) {
4719      if (S.SourceMgr.isInSystemMacro(CC))
4720        return;
4721
4722      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4723    }
4724
4725    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4726    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4727  }
4728
4729  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4730  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4731
4732  // If the source is floating point...
4733  if (SourceBT && SourceBT->isFloatingPoint()) {
4734    // ...and the target is floating point...
4735    if (TargetBT && TargetBT->isFloatingPoint()) {
4736      // ...then warn if we're dropping FP rank.
4737
4738      // Builtin FP kinds are ordered by increasing FP rank.
4739      if (SourceBT->getKind() > TargetBT->getKind()) {
4740        // Don't warn about float constants that are precisely
4741        // representable in the target type.
4742        Expr::EvalResult result;
4743        if (E->EvaluateAsRValue(result, S.Context)) {
4744          // Value might be a float, a float vector, or a float complex.
4745          if (IsSameFloatAfterCast(result.Val,
4746                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4747                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4748            return;
4749        }
4750
4751        if (S.SourceMgr.isInSystemMacro(CC))
4752          return;
4753
4754        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4755      }
4756      return;
4757    }
4758
4759    // If the target is integral, always warn.
4760    if (TargetBT && TargetBT->isInteger()) {
4761      if (S.SourceMgr.isInSystemMacro(CC))
4762        return;
4763
4764      Expr *InnerE = E->IgnoreParenImpCasts();
4765      // We also want to warn on, e.g., "int i = -1.234"
4766      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4767        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4768          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4769
4770      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4771        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4772      } else {
4773        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4774      }
4775    }
4776
4777    // If the target is bool, warn if expr is a function or method call.
4778    if (Target->isSpecificBuiltinType(BuiltinType::Bool) &&
4779        isa<CallExpr>(E)) {
4780      // Check last argument of function call to see if it is an
4781      // implicit cast from a type matching the type the result
4782      // is being cast to.
4783      CallExpr *CEx = cast<CallExpr>(E);
4784      unsigned NumArgs = CEx->getNumArgs();
4785      if (NumArgs > 0) {
4786        Expr *LastA = CEx->getArg(NumArgs - 1);
4787        Expr *InnerE = LastA->IgnoreParenImpCasts();
4788        const Type *InnerType =
4789          S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4790        if (isa<ImplicitCastExpr>(LastA) && (InnerType == Target)) {
4791          // Warn on this floating-point to bool conversion
4792          DiagnoseImpCast(S, E, T, CC,
4793                          diag::warn_impcast_floating_point_to_bool);
4794        }
4795      }
4796    }
4797    return;
4798  }
4799
4800  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4801           == Expr::NPCK_GNUNull) && !Target->isAnyPointerType()
4802      && !Target->isBlockPointerType() && !Target->isMemberPointerType()) {
4803    SourceLocation Loc = E->getSourceRange().getBegin();
4804    if (Loc.isMacroID())
4805      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4806    if (!Loc.isMacroID() || CC.isMacroID())
4807      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4808          << T << clang::SourceRange(CC)
4809          << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
4810  }
4811
4812  if (!Source->isIntegerType() || !Target->isIntegerType())
4813    return;
4814
4815  // TODO: remove this early return once the false positives for constant->bool
4816  // in templates, macros, etc, are reduced or removed.
4817  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
4818    return;
4819
4820  IntRange SourceRange = GetExprRange(S.Context, E);
4821  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
4822
4823  if (SourceRange.Width > TargetRange.Width) {
4824    // If the source is a constant, use a default-on diagnostic.
4825    // TODO: this should happen for bitfield stores, too.
4826    llvm::APSInt Value(32);
4827    if (E->isIntegerConstantExpr(Value, S.Context)) {
4828      if (S.SourceMgr.isInSystemMacro(CC))
4829        return;
4830
4831      std::string PrettySourceValue = Value.toString(10);
4832      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
4833
4834      S.DiagRuntimeBehavior(E->getExprLoc(), E,
4835        S.PDiag(diag::warn_impcast_integer_precision_constant)
4836            << PrettySourceValue << PrettyTargetValue
4837            << E->getType() << T << E->getSourceRange()
4838            << clang::SourceRange(CC));
4839      return;
4840    }
4841
4842    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
4843    if (S.SourceMgr.isInSystemMacro(CC))
4844      return;
4845
4846    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
4847      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
4848                             /* pruneControlFlow */ true);
4849    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
4850  }
4851
4852  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
4853      (!TargetRange.NonNegative && SourceRange.NonNegative &&
4854       SourceRange.Width == TargetRange.Width)) {
4855
4856    if (S.SourceMgr.isInSystemMacro(CC))
4857      return;
4858
4859    unsigned DiagID = diag::warn_impcast_integer_sign;
4860
4861    // Traditionally, gcc has warned about this under -Wsign-compare.
4862    // We also want to warn about it in -Wconversion.
4863    // So if -Wconversion is off, use a completely identical diagnostic
4864    // in the sign-compare group.
4865    // The conditional-checking code will
4866    if (ICContext) {
4867      DiagID = diag::warn_impcast_integer_sign_conditional;
4868      *ICContext = true;
4869    }
4870
4871    return DiagnoseImpCast(S, E, T, CC, DiagID);
4872  }
4873
4874  // Diagnose conversions between different enumeration types.
4875  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
4876  // type, to give us better diagnostics.
4877  QualType SourceType = E->getType();
4878  if (!S.getLangOpts().CPlusPlus) {
4879    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
4880      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
4881        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
4882        SourceType = S.Context.getTypeDeclType(Enum);
4883        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
4884      }
4885  }
4886
4887  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
4888    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
4889      if ((SourceEnum->getDecl()->getIdentifier() ||
4890           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4891          (TargetEnum->getDecl()->getIdentifier() ||
4892           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4893          SourceEnum != TargetEnum) {
4894        if (S.SourceMgr.isInSystemMacro(CC))
4895          return;
4896
4897        return DiagnoseImpCast(S, E, SourceType, T, CC,
4898                               diag::warn_impcast_different_enum_types);
4899      }
4900
4901  return;
4902}
4903
4904void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
4905                              SourceLocation CC, QualType T);
4906
4907void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
4908                             SourceLocation CC, bool &ICContext) {
4909  E = E->IgnoreParenImpCasts();
4910
4911  if (isa<ConditionalOperator>(E))
4912    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
4913
4914  AnalyzeImplicitConversions(S, E, CC);
4915  if (E->getType() != T)
4916    return CheckImplicitConversion(S, E, T, CC, &ICContext);
4917  return;
4918}
4919
4920void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
4921                              SourceLocation CC, QualType T) {
4922  AnalyzeImplicitConversions(S, E->getCond(), CC);
4923
4924  bool Suspicious = false;
4925  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
4926  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
4927
4928  // If -Wconversion would have warned about either of the candidates
4929  // for a signedness conversion to the context type...
4930  if (!Suspicious) return;
4931
4932  // ...but it's currently ignored...
4933  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
4934                                 CC))
4935    return;
4936
4937  // ...then check whether it would have warned about either of the
4938  // candidates for a signedness conversion to the condition type.
4939  if (E->getType() == T) return;
4940
4941  Suspicious = false;
4942  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
4943                          E->getType(), CC, &Suspicious);
4944  if (!Suspicious)
4945    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
4946                            E->getType(), CC, &Suspicious);
4947}
4948
4949/// AnalyzeImplicitConversions - Find and report any interesting
4950/// implicit conversions in the given expression.  There are a couple
4951/// of competing diagnostics here, -Wconversion and -Wsign-compare.
4952void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
4953  QualType T = OrigE->getType();
4954  Expr *E = OrigE->IgnoreParenImpCasts();
4955
4956  if (E->isTypeDependent() || E->isValueDependent())
4957    return;
4958
4959  // For conditional operators, we analyze the arguments as if they
4960  // were being fed directly into the output.
4961  if (isa<ConditionalOperator>(E)) {
4962    ConditionalOperator *CO = cast<ConditionalOperator>(E);
4963    CheckConditionalOperator(S, CO, CC, T);
4964    return;
4965  }
4966
4967  // Check implicit argument conversions for function calls.
4968  if (CallExpr *Call = dyn_cast<CallExpr>(E))
4969    CheckImplicitArgumentConversions(S, Call, CC);
4970
4971  // Go ahead and check any implicit conversions we might have skipped.
4972  // The non-canonical typecheck is just an optimization;
4973  // CheckImplicitConversion will filter out dead implicit conversions.
4974  if (E->getType() != T)
4975    CheckImplicitConversion(S, E, T, CC);
4976
4977  // Now continue drilling into this expression.
4978
4979  // Skip past explicit casts.
4980  if (isa<ExplicitCastExpr>(E)) {
4981    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4982    return AnalyzeImplicitConversions(S, E, CC);
4983  }
4984
4985  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4986    // Do a somewhat different check with comparison operators.
4987    if (BO->isComparisonOp())
4988      return AnalyzeComparison(S, BO);
4989
4990    // And with simple assignments.
4991    if (BO->getOpcode() == BO_Assign)
4992      return AnalyzeAssignment(S, BO);
4993  }
4994
4995  // These break the otherwise-useful invariant below.  Fortunately,
4996  // we don't really need to recurse into them, because any internal
4997  // expressions should have been analyzed already when they were
4998  // built into statements.
4999  if (isa<StmtExpr>(E)) return;
5000
5001  // Don't descend into unevaluated contexts.
5002  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
5003
5004  // Now just recurse over the expression's children.
5005  CC = E->getExprLoc();
5006  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
5007  bool IsLogicalOperator = BO && BO->isLogicalOp();
5008  for (Stmt::child_range I = E->children(); I; ++I) {
5009    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
5010    if (!ChildExpr)
5011      continue;
5012
5013    if (IsLogicalOperator &&
5014        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
5015      // Ignore checking string literals that are in logical operators.
5016      continue;
5017    AnalyzeImplicitConversions(S, ChildExpr, CC);
5018  }
5019}
5020
5021} // end anonymous namespace
5022
5023/// Diagnoses "dangerous" implicit conversions within the given
5024/// expression (which is a full expression).  Implements -Wconversion
5025/// and -Wsign-compare.
5026///
5027/// \param CC the "context" location of the implicit conversion, i.e.
5028///   the most location of the syntactic entity requiring the implicit
5029///   conversion
5030void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
5031  // Don't diagnose in unevaluated contexts.
5032  if (isUnevaluatedContext())
5033    return;
5034
5035  // Don't diagnose for value- or type-dependent expressions.
5036  if (E->isTypeDependent() || E->isValueDependent())
5037    return;
5038
5039  // Check for array bounds violations in cases where the check isn't triggered
5040  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
5041  // ArraySubscriptExpr is on the RHS of a variable initialization.
5042  CheckArrayAccess(E);
5043
5044  // This is not the right CC for (e.g.) a variable initialization.
5045  AnalyzeImplicitConversions(*this, E, CC);
5046}
5047
5048void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
5049                                       FieldDecl *BitField,
5050                                       Expr *Init) {
5051  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
5052}
5053
5054/// CheckParmsForFunctionDef - Check that the parameters of the given
5055/// function are appropriate for the definition of a function. This
5056/// takes care of any checks that cannot be performed on the
5057/// declaration itself, e.g., that the types of each of the function
5058/// parameters are complete.
5059bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
5060                                    bool CheckParameterNames) {
5061  bool HasInvalidParm = false;
5062  for (; P != PEnd; ++P) {
5063    ParmVarDecl *Param = *P;
5064
5065    // C99 6.7.5.3p4: the parameters in a parameter type list in a
5066    // function declarator that is part of a function definition of
5067    // that function shall not have incomplete type.
5068    //
5069    // This is also C++ [dcl.fct]p6.
5070    if (!Param->isInvalidDecl() &&
5071        RequireCompleteType(Param->getLocation(), Param->getType(),
5072                            diag::err_typecheck_decl_incomplete_type)) {
5073      Param->setInvalidDecl();
5074      HasInvalidParm = true;
5075    }
5076
5077    // C99 6.9.1p5: If the declarator includes a parameter type list, the
5078    // declaration of each parameter shall include an identifier.
5079    if (CheckParameterNames &&
5080        Param->getIdentifier() == 0 &&
5081        !Param->isImplicit() &&
5082        !getLangOpts().CPlusPlus)
5083      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
5084
5085    // C99 6.7.5.3p12:
5086    //   If the function declarator is not part of a definition of that
5087    //   function, parameters may have incomplete type and may use the [*]
5088    //   notation in their sequences of declarator specifiers to specify
5089    //   variable length array types.
5090    QualType PType = Param->getOriginalType();
5091    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
5092      if (AT->getSizeModifier() == ArrayType::Star) {
5093        // FIXME: This diagnosic should point the '[*]' if source-location
5094        // information is added for it.
5095        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
5096      }
5097    }
5098  }
5099
5100  return HasInvalidParm;
5101}
5102
5103/// CheckCastAlign - Implements -Wcast-align, which warns when a
5104/// pointer cast increases the alignment requirements.
5105void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
5106  // This is actually a lot of work to potentially be doing on every
5107  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
5108  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
5109                                          TRange.getBegin())
5110        == DiagnosticsEngine::Ignored)
5111    return;
5112
5113  // Ignore dependent types.
5114  if (T->isDependentType() || Op->getType()->isDependentType())
5115    return;
5116
5117  // Require that the destination be a pointer type.
5118  const PointerType *DestPtr = T->getAs<PointerType>();
5119  if (!DestPtr) return;
5120
5121  // If the destination has alignment 1, we're done.
5122  QualType DestPointee = DestPtr->getPointeeType();
5123  if (DestPointee->isIncompleteType()) return;
5124  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
5125  if (DestAlign.isOne()) return;
5126
5127  // Require that the source be a pointer type.
5128  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
5129  if (!SrcPtr) return;
5130  QualType SrcPointee = SrcPtr->getPointeeType();
5131
5132  // Whitelist casts from cv void*.  We already implicitly
5133  // whitelisted casts to cv void*, since they have alignment 1.
5134  // Also whitelist casts involving incomplete types, which implicitly
5135  // includes 'void'.
5136  if (SrcPointee->isIncompleteType()) return;
5137
5138  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
5139  if (SrcAlign >= DestAlign) return;
5140
5141  Diag(TRange.getBegin(), diag::warn_cast_align)
5142    << Op->getType() << T
5143    << static_cast<unsigned>(SrcAlign.getQuantity())
5144    << static_cast<unsigned>(DestAlign.getQuantity())
5145    << TRange << Op->getSourceRange();
5146}
5147
5148static const Type* getElementType(const Expr *BaseExpr) {
5149  const Type* EltType = BaseExpr->getType().getTypePtr();
5150  if (EltType->isAnyPointerType())
5151    return EltType->getPointeeType().getTypePtr();
5152  else if (EltType->isArrayType())
5153    return EltType->getBaseElementTypeUnsafe();
5154  return EltType;
5155}
5156
5157/// \brief Check whether this array fits the idiom of a size-one tail padded
5158/// array member of a struct.
5159///
5160/// We avoid emitting out-of-bounds access warnings for such arrays as they are
5161/// commonly used to emulate flexible arrays in C89 code.
5162static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
5163                                    const NamedDecl *ND) {
5164  if (Size != 1 || !ND) return false;
5165
5166  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
5167  if (!FD) return false;
5168
5169  // Don't consider sizes resulting from macro expansions or template argument
5170  // substitution to form C89 tail-padded arrays.
5171
5172  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
5173  while (TInfo) {
5174    TypeLoc TL = TInfo->getTypeLoc();
5175    // Look through typedefs.
5176    const TypedefTypeLoc *TTL = dyn_cast<TypedefTypeLoc>(&TL);
5177    if (TTL) {
5178      const TypedefNameDecl *TDL = TTL->getTypedefNameDecl();
5179      TInfo = TDL->getTypeSourceInfo();
5180      continue;
5181    }
5182    ConstantArrayTypeLoc CTL = cast<ConstantArrayTypeLoc>(TL);
5183    const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
5184    if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
5185      return false;
5186    break;
5187  }
5188
5189  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
5190  if (!RD) return false;
5191  if (RD->isUnion()) return false;
5192  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
5193    if (!CRD->isStandardLayout()) return false;
5194  }
5195
5196  // See if this is the last field decl in the record.
5197  const Decl *D = FD;
5198  while ((D = D->getNextDeclInContext()))
5199    if (isa<FieldDecl>(D))
5200      return false;
5201  return true;
5202}
5203
5204void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
5205                            const ArraySubscriptExpr *ASE,
5206                            bool AllowOnePastEnd, bool IndexNegated) {
5207  IndexExpr = IndexExpr->IgnoreParenImpCasts();
5208  if (IndexExpr->isValueDependent())
5209    return;
5210
5211  const Type *EffectiveType = getElementType(BaseExpr);
5212  BaseExpr = BaseExpr->IgnoreParenCasts();
5213  const ConstantArrayType *ArrayTy =
5214    Context.getAsConstantArrayType(BaseExpr->getType());
5215  if (!ArrayTy)
5216    return;
5217
5218  llvm::APSInt index;
5219  if (!IndexExpr->EvaluateAsInt(index, Context))
5220    return;
5221  if (IndexNegated)
5222    index = -index;
5223
5224  const NamedDecl *ND = NULL;
5225  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5226    ND = dyn_cast<NamedDecl>(DRE->getDecl());
5227  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5228    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5229
5230  if (index.isUnsigned() || !index.isNegative()) {
5231    llvm::APInt size = ArrayTy->getSize();
5232    if (!size.isStrictlyPositive())
5233      return;
5234
5235    const Type* BaseType = getElementType(BaseExpr);
5236    if (BaseType != EffectiveType) {
5237      // Make sure we're comparing apples to apples when comparing index to size
5238      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
5239      uint64_t array_typesize = Context.getTypeSize(BaseType);
5240      // Handle ptrarith_typesize being zero, such as when casting to void*
5241      if (!ptrarith_typesize) ptrarith_typesize = 1;
5242      if (ptrarith_typesize != array_typesize) {
5243        // There's a cast to a different size type involved
5244        uint64_t ratio = array_typesize / ptrarith_typesize;
5245        // TODO: Be smarter about handling cases where array_typesize is not a
5246        // multiple of ptrarith_typesize
5247        if (ptrarith_typesize * ratio == array_typesize)
5248          size *= llvm::APInt(size.getBitWidth(), ratio);
5249      }
5250    }
5251
5252    if (size.getBitWidth() > index.getBitWidth())
5253      index = index.zext(size.getBitWidth());
5254    else if (size.getBitWidth() < index.getBitWidth())
5255      size = size.zext(index.getBitWidth());
5256
5257    // For array subscripting the index must be less than size, but for pointer
5258    // arithmetic also allow the index (offset) to be equal to size since
5259    // computing the next address after the end of the array is legal and
5260    // commonly done e.g. in C++ iterators and range-based for loops.
5261    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
5262      return;
5263
5264    // Also don't warn for arrays of size 1 which are members of some
5265    // structure. These are often used to approximate flexible arrays in C89
5266    // code.
5267    if (IsTailPaddedMemberArray(*this, size, ND))
5268      return;
5269
5270    // Suppress the warning if the subscript expression (as identified by the
5271    // ']' location) and the index expression are both from macro expansions
5272    // within a system header.
5273    if (ASE) {
5274      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
5275          ASE->getRBracketLoc());
5276      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
5277        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
5278            IndexExpr->getLocStart());
5279        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
5280          return;
5281      }
5282    }
5283
5284    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
5285    if (ASE)
5286      DiagID = diag::warn_array_index_exceeds_bounds;
5287
5288    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5289                        PDiag(DiagID) << index.toString(10, true)
5290                          << size.toString(10, true)
5291                          << (unsigned)size.getLimitedValue(~0U)
5292                          << IndexExpr->getSourceRange());
5293  } else {
5294    unsigned DiagID = diag::warn_array_index_precedes_bounds;
5295    if (!ASE) {
5296      DiagID = diag::warn_ptr_arith_precedes_bounds;
5297      if (index.isNegative()) index = -index;
5298    }
5299
5300    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5301                        PDiag(DiagID) << index.toString(10, true)
5302                          << IndexExpr->getSourceRange());
5303  }
5304
5305  if (!ND) {
5306    // Try harder to find a NamedDecl to point at in the note.
5307    while (const ArraySubscriptExpr *ASE =
5308           dyn_cast<ArraySubscriptExpr>(BaseExpr))
5309      BaseExpr = ASE->getBase()->IgnoreParenCasts();
5310    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5311      ND = dyn_cast<NamedDecl>(DRE->getDecl());
5312    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5313      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5314  }
5315
5316  if (ND)
5317    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
5318                        PDiag(diag::note_array_index_out_of_bounds)
5319                          << ND->getDeclName());
5320}
5321
5322void Sema::CheckArrayAccess(const Expr *expr) {
5323  int AllowOnePastEnd = 0;
5324  while (expr) {
5325    expr = expr->IgnoreParenImpCasts();
5326    switch (expr->getStmtClass()) {
5327      case Stmt::ArraySubscriptExprClass: {
5328        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
5329        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
5330                         AllowOnePastEnd > 0);
5331        return;
5332      }
5333      case Stmt::UnaryOperatorClass: {
5334        // Only unwrap the * and & unary operators
5335        const UnaryOperator *UO = cast<UnaryOperator>(expr);
5336        expr = UO->getSubExpr();
5337        switch (UO->getOpcode()) {
5338          case UO_AddrOf:
5339            AllowOnePastEnd++;
5340            break;
5341          case UO_Deref:
5342            AllowOnePastEnd--;
5343            break;
5344          default:
5345            return;
5346        }
5347        break;
5348      }
5349      case Stmt::ConditionalOperatorClass: {
5350        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
5351        if (const Expr *lhs = cond->getLHS())
5352          CheckArrayAccess(lhs);
5353        if (const Expr *rhs = cond->getRHS())
5354          CheckArrayAccess(rhs);
5355        return;
5356      }
5357      default:
5358        return;
5359    }
5360  }
5361}
5362
5363//===--- CHECK: Objective-C retain cycles ----------------------------------//
5364
5365namespace {
5366  struct RetainCycleOwner {
5367    RetainCycleOwner() : Variable(0), Indirect(false) {}
5368    VarDecl *Variable;
5369    SourceRange Range;
5370    SourceLocation Loc;
5371    bool Indirect;
5372
5373    void setLocsFrom(Expr *e) {
5374      Loc = e->getExprLoc();
5375      Range = e->getSourceRange();
5376    }
5377  };
5378}
5379
5380/// Consider whether capturing the given variable can possibly lead to
5381/// a retain cycle.
5382static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
5383  // In ARC, it's captured strongly iff the variable has __strong
5384  // lifetime.  In MRR, it's captured strongly if the variable is
5385  // __block and has an appropriate type.
5386  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
5387    return false;
5388
5389  owner.Variable = var;
5390  if (ref)
5391    owner.setLocsFrom(ref);
5392  return true;
5393}
5394
5395static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
5396  while (true) {
5397    e = e->IgnoreParens();
5398    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
5399      switch (cast->getCastKind()) {
5400      case CK_BitCast:
5401      case CK_LValueBitCast:
5402      case CK_LValueToRValue:
5403      case CK_ARCReclaimReturnedObject:
5404        e = cast->getSubExpr();
5405        continue;
5406
5407      default:
5408        return false;
5409      }
5410    }
5411
5412    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
5413      ObjCIvarDecl *ivar = ref->getDecl();
5414      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
5415        return false;
5416
5417      // Try to find a retain cycle in the base.
5418      if (!findRetainCycleOwner(S, ref->getBase(), owner))
5419        return false;
5420
5421      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
5422      owner.Indirect = true;
5423      return true;
5424    }
5425
5426    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
5427      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
5428      if (!var) return false;
5429      return considerVariable(var, ref, owner);
5430    }
5431
5432    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
5433      if (member->isArrow()) return false;
5434
5435      // Don't count this as an indirect ownership.
5436      e = member->getBase();
5437      continue;
5438    }
5439
5440    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
5441      // Only pay attention to pseudo-objects on property references.
5442      ObjCPropertyRefExpr *pre
5443        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
5444                                              ->IgnoreParens());
5445      if (!pre) return false;
5446      if (pre->isImplicitProperty()) return false;
5447      ObjCPropertyDecl *property = pre->getExplicitProperty();
5448      if (!property->isRetaining() &&
5449          !(property->getPropertyIvarDecl() &&
5450            property->getPropertyIvarDecl()->getType()
5451              .getObjCLifetime() == Qualifiers::OCL_Strong))
5452          return false;
5453
5454      owner.Indirect = true;
5455      if (pre->isSuperReceiver()) {
5456        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
5457        if (!owner.Variable)
5458          return false;
5459        owner.Loc = pre->getLocation();
5460        owner.Range = pre->getSourceRange();
5461        return true;
5462      }
5463      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
5464                              ->getSourceExpr());
5465      continue;
5466    }
5467
5468    // Array ivars?
5469
5470    return false;
5471  }
5472}
5473
5474namespace {
5475  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
5476    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
5477      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
5478        Variable(variable), Capturer(0) {}
5479
5480    VarDecl *Variable;
5481    Expr *Capturer;
5482
5483    void VisitDeclRefExpr(DeclRefExpr *ref) {
5484      if (ref->getDecl() == Variable && !Capturer)
5485        Capturer = ref;
5486    }
5487
5488    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
5489      if (Capturer) return;
5490      Visit(ref->getBase());
5491      if (Capturer && ref->isFreeIvar())
5492        Capturer = ref;
5493    }
5494
5495    void VisitBlockExpr(BlockExpr *block) {
5496      // Look inside nested blocks
5497      if (block->getBlockDecl()->capturesVariable(Variable))
5498        Visit(block->getBlockDecl()->getBody());
5499    }
5500
5501    void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
5502      if (Capturer) return;
5503      if (OVE->getSourceExpr())
5504        Visit(OVE->getSourceExpr());
5505    }
5506  };
5507}
5508
5509/// Check whether the given argument is a block which captures a
5510/// variable.
5511static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
5512  assert(owner.Variable && owner.Loc.isValid());
5513
5514  e = e->IgnoreParenCasts();
5515
5516  // Look through [^{...} copy] and Block_copy(^{...}).
5517  if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
5518    Selector Cmd = ME->getSelector();
5519    if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
5520      e = ME->getInstanceReceiver();
5521      if (!e)
5522        return 0;
5523      e = e->IgnoreParenCasts();
5524    }
5525  } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
5526    if (CE->getNumArgs() == 1) {
5527      FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
5528      if (Fn) {
5529        const IdentifierInfo *FnI = Fn->getIdentifier();
5530        if (FnI && FnI->isStr("_Block_copy")) {
5531          e = CE->getArg(0)->IgnoreParenCasts();
5532        }
5533      }
5534    }
5535  }
5536
5537  BlockExpr *block = dyn_cast<BlockExpr>(e);
5538  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
5539    return 0;
5540
5541  FindCaptureVisitor visitor(S.Context, owner.Variable);
5542  visitor.Visit(block->getBlockDecl()->getBody());
5543  return visitor.Capturer;
5544}
5545
5546static void diagnoseRetainCycle(Sema &S, Expr *capturer,
5547                                RetainCycleOwner &owner) {
5548  assert(capturer);
5549  assert(owner.Variable && owner.Loc.isValid());
5550
5551  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
5552    << owner.Variable << capturer->getSourceRange();
5553  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
5554    << owner.Indirect << owner.Range;
5555}
5556
5557/// Check for a keyword selector that starts with the word 'add' or
5558/// 'set'.
5559static bool isSetterLikeSelector(Selector sel) {
5560  if (sel.isUnarySelector()) return false;
5561
5562  StringRef str = sel.getNameForSlot(0);
5563  while (!str.empty() && str.front() == '_') str = str.substr(1);
5564  if (str.startswith("set"))
5565    str = str.substr(3);
5566  else if (str.startswith("add")) {
5567    // Specially whitelist 'addOperationWithBlock:'.
5568    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
5569      return false;
5570    str = str.substr(3);
5571  }
5572  else
5573    return false;
5574
5575  if (str.empty()) return true;
5576  return !islower(str.front());
5577}
5578
5579/// Check a message send to see if it's likely to cause a retain cycle.
5580void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
5581  // Only check instance methods whose selector looks like a setter.
5582  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
5583    return;
5584
5585  // Try to find a variable that the receiver is strongly owned by.
5586  RetainCycleOwner owner;
5587  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
5588    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
5589      return;
5590  } else {
5591    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
5592    owner.Variable = getCurMethodDecl()->getSelfDecl();
5593    owner.Loc = msg->getSuperLoc();
5594    owner.Range = msg->getSuperLoc();
5595  }
5596
5597  // Check whether the receiver is captured by any of the arguments.
5598  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
5599    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
5600      return diagnoseRetainCycle(*this, capturer, owner);
5601}
5602
5603/// Check a property assign to see if it's likely to cause a retain cycle.
5604void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
5605  RetainCycleOwner owner;
5606  if (!findRetainCycleOwner(*this, receiver, owner))
5607    return;
5608
5609  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
5610    diagnoseRetainCycle(*this, capturer, owner);
5611}
5612
5613void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
5614  RetainCycleOwner Owner;
5615  if (!considerVariable(Var, /*DeclRefExpr=*/0, Owner))
5616    return;
5617
5618  // Because we don't have an expression for the variable, we have to set the
5619  // location explicitly here.
5620  Owner.Loc = Var->getLocation();
5621  Owner.Range = Var->getSourceRange();
5622
5623  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
5624    diagnoseRetainCycle(*this, Capturer, Owner);
5625}
5626
5627bool Sema::checkUnsafeAssigns(SourceLocation Loc,
5628                              QualType LHS, Expr *RHS) {
5629  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
5630  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
5631    return false;
5632  // strip off any implicit cast added to get to the one arc-specific
5633  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5634    if (cast->getCastKind() == CK_ARCConsumeObject) {
5635      Diag(Loc, diag::warn_arc_retained_assign)
5636        << (LT == Qualifiers::OCL_ExplicitNone) << 1
5637        << RHS->getSourceRange();
5638      return true;
5639    }
5640    RHS = cast->getSubExpr();
5641  }
5642  return false;
5643}
5644
5645void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
5646                              Expr *LHS, Expr *RHS) {
5647  QualType LHSType;
5648  // PropertyRef on LHS type need be directly obtained from
5649  // its declaration as it has a PsuedoType.
5650  ObjCPropertyRefExpr *PRE
5651    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
5652  if (PRE && !PRE->isImplicitProperty()) {
5653    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5654    if (PD)
5655      LHSType = PD->getType();
5656  }
5657
5658  if (LHSType.isNull())
5659    LHSType = LHS->getType();
5660
5661  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
5662
5663  if (LT == Qualifiers::OCL_Weak) {
5664    DiagnosticsEngine::Level Level =
5665      Diags.getDiagnosticLevel(diag::warn_arc_repeated_use_of_weak, Loc);
5666    if (Level != DiagnosticsEngine::Ignored)
5667      getCurFunction()->markSafeWeakUse(LHS);
5668  }
5669
5670  if (checkUnsafeAssigns(Loc, LHSType, RHS))
5671    return;
5672
5673  // FIXME. Check for other life times.
5674  if (LT != Qualifiers::OCL_None)
5675    return;
5676
5677  if (PRE) {
5678    if (PRE->isImplicitProperty())
5679      return;
5680    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5681    if (!PD)
5682      return;
5683
5684    unsigned Attributes = PD->getPropertyAttributes();
5685    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
5686      // when 'assign' attribute was not explicitly specified
5687      // by user, ignore it and rely on property type itself
5688      // for lifetime info.
5689      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
5690      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
5691          LHSType->isObjCRetainableType())
5692        return;
5693
5694      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5695        if (cast->getCastKind() == CK_ARCConsumeObject) {
5696          Diag(Loc, diag::warn_arc_retained_property_assign)
5697          << RHS->getSourceRange();
5698          return;
5699        }
5700        RHS = cast->getSubExpr();
5701      }
5702    }
5703    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
5704      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5705        if (cast->getCastKind() == CK_ARCConsumeObject) {
5706          Diag(Loc, diag::warn_arc_retained_assign)
5707          << 0 << 0<< RHS->getSourceRange();
5708          return;
5709        }
5710        RHS = cast->getSubExpr();
5711      }
5712    }
5713  }
5714}
5715
5716//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
5717
5718namespace {
5719bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
5720                                 SourceLocation StmtLoc,
5721                                 const NullStmt *Body) {
5722  // Do not warn if the body is a macro that expands to nothing, e.g:
5723  //
5724  // #define CALL(x)
5725  // if (condition)
5726  //   CALL(0);
5727  //
5728  if (Body->hasLeadingEmptyMacro())
5729    return false;
5730
5731  // Get line numbers of statement and body.
5732  bool StmtLineInvalid;
5733  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
5734                                                      &StmtLineInvalid);
5735  if (StmtLineInvalid)
5736    return false;
5737
5738  bool BodyLineInvalid;
5739  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
5740                                                      &BodyLineInvalid);
5741  if (BodyLineInvalid)
5742    return false;
5743
5744  // Warn if null statement and body are on the same line.
5745  if (StmtLine != BodyLine)
5746    return false;
5747
5748  return true;
5749}
5750} // Unnamed namespace
5751
5752void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
5753                                 const Stmt *Body,
5754                                 unsigned DiagID) {
5755  // Since this is a syntactic check, don't emit diagnostic for template
5756  // instantiations, this just adds noise.
5757  if (CurrentInstantiationScope)
5758    return;
5759
5760  // The body should be a null statement.
5761  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5762  if (!NBody)
5763    return;
5764
5765  // Do the usual checks.
5766  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5767    return;
5768
5769  Diag(NBody->getSemiLoc(), DiagID);
5770  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5771}
5772
5773void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
5774                                 const Stmt *PossibleBody) {
5775  assert(!CurrentInstantiationScope); // Ensured by caller
5776
5777  SourceLocation StmtLoc;
5778  const Stmt *Body;
5779  unsigned DiagID;
5780  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
5781    StmtLoc = FS->getRParenLoc();
5782    Body = FS->getBody();
5783    DiagID = diag::warn_empty_for_body;
5784  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
5785    StmtLoc = WS->getCond()->getSourceRange().getEnd();
5786    Body = WS->getBody();
5787    DiagID = diag::warn_empty_while_body;
5788  } else
5789    return; // Neither `for' nor `while'.
5790
5791  // The body should be a null statement.
5792  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5793  if (!NBody)
5794    return;
5795
5796  // Skip expensive checks if diagnostic is disabled.
5797  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
5798          DiagnosticsEngine::Ignored)
5799    return;
5800
5801  // Do the usual checks.
5802  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5803    return;
5804
5805  // `for(...);' and `while(...);' are popular idioms, so in order to keep
5806  // noise level low, emit diagnostics only if for/while is followed by a
5807  // CompoundStmt, e.g.:
5808  //    for (int i = 0; i < n; i++);
5809  //    {
5810  //      a(i);
5811  //    }
5812  // or if for/while is followed by a statement with more indentation
5813  // than for/while itself:
5814  //    for (int i = 0; i < n; i++);
5815  //      a(i);
5816  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
5817  if (!ProbableTypo) {
5818    bool BodyColInvalid;
5819    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
5820                             PossibleBody->getLocStart(),
5821                             &BodyColInvalid);
5822    if (BodyColInvalid)
5823      return;
5824
5825    bool StmtColInvalid;
5826    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
5827                             S->getLocStart(),
5828                             &StmtColInvalid);
5829    if (StmtColInvalid)
5830      return;
5831
5832    if (BodyCol > StmtCol)
5833      ProbableTypo = true;
5834  }
5835
5836  if (ProbableTypo) {
5837    Diag(NBody->getSemiLoc(), DiagID);
5838    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5839  }
5840}
5841
5842//===--- Layout compatibility ----------------------------------------------//
5843
5844namespace {
5845
5846bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
5847
5848/// \brief Check if two enumeration types are layout-compatible.
5849bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
5850  // C++11 [dcl.enum] p8:
5851  // Two enumeration types are layout-compatible if they have the same
5852  // underlying type.
5853  return ED1->isComplete() && ED2->isComplete() &&
5854         C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
5855}
5856
5857/// \brief Check if two fields are layout-compatible.
5858bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
5859  if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
5860    return false;
5861
5862  if (Field1->isBitField() != Field2->isBitField())
5863    return false;
5864
5865  if (Field1->isBitField()) {
5866    // Make sure that the bit-fields are the same length.
5867    unsigned Bits1 = Field1->getBitWidthValue(C);
5868    unsigned Bits2 = Field2->getBitWidthValue(C);
5869
5870    if (Bits1 != Bits2)
5871      return false;
5872  }
5873
5874  return true;
5875}
5876
5877/// \brief Check if two standard-layout structs are layout-compatible.
5878/// (C++11 [class.mem] p17)
5879bool isLayoutCompatibleStruct(ASTContext &C,
5880                              RecordDecl *RD1,
5881                              RecordDecl *RD2) {
5882  // If both records are C++ classes, check that base classes match.
5883  if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
5884    // If one of records is a CXXRecordDecl we are in C++ mode,
5885    // thus the other one is a CXXRecordDecl, too.
5886    const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
5887    // Check number of base classes.
5888    if (D1CXX->getNumBases() != D2CXX->getNumBases())
5889      return false;
5890
5891    // Check the base classes.
5892    for (CXXRecordDecl::base_class_const_iterator
5893               Base1 = D1CXX->bases_begin(),
5894           BaseEnd1 = D1CXX->bases_end(),
5895              Base2 = D2CXX->bases_begin();
5896         Base1 != BaseEnd1;
5897         ++Base1, ++Base2) {
5898      if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
5899        return false;
5900    }
5901  } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
5902    // If only RD2 is a C++ class, it should have zero base classes.
5903    if (D2CXX->getNumBases() > 0)
5904      return false;
5905  }
5906
5907  // Check the fields.
5908  RecordDecl::field_iterator Field2 = RD2->field_begin(),
5909                             Field2End = RD2->field_end(),
5910                             Field1 = RD1->field_begin(),
5911                             Field1End = RD1->field_end();
5912  for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
5913    if (!isLayoutCompatible(C, *Field1, *Field2))
5914      return false;
5915  }
5916  if (Field1 != Field1End || Field2 != Field2End)
5917    return false;
5918
5919  return true;
5920}
5921
5922/// \brief Check if two standard-layout unions are layout-compatible.
5923/// (C++11 [class.mem] p18)
5924bool isLayoutCompatibleUnion(ASTContext &C,
5925                             RecordDecl *RD1,
5926                             RecordDecl *RD2) {
5927  llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
5928  for (RecordDecl::field_iterator Field2 = RD2->field_begin(),
5929                                  Field2End = RD2->field_end();
5930       Field2 != Field2End; ++Field2) {
5931    UnmatchedFields.insert(*Field2);
5932  }
5933
5934  for (RecordDecl::field_iterator Field1 = RD1->field_begin(),
5935                                  Field1End = RD1->field_end();
5936       Field1 != Field1End; ++Field1) {
5937    llvm::SmallPtrSet<FieldDecl *, 8>::iterator
5938        I = UnmatchedFields.begin(),
5939        E = UnmatchedFields.end();
5940
5941    for ( ; I != E; ++I) {
5942      if (isLayoutCompatible(C, *Field1, *I)) {
5943        bool Result = UnmatchedFields.erase(*I);
5944        (void) Result;
5945        assert(Result);
5946        break;
5947      }
5948    }
5949    if (I == E)
5950      return false;
5951  }
5952
5953  return UnmatchedFields.empty();
5954}
5955
5956bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
5957  if (RD1->isUnion() != RD2->isUnion())
5958    return false;
5959
5960  if (RD1->isUnion())
5961    return isLayoutCompatibleUnion(C, RD1, RD2);
5962  else
5963    return isLayoutCompatibleStruct(C, RD1, RD2);
5964}
5965
5966/// \brief Check if two types are layout-compatible in C++11 sense.
5967bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
5968  if (T1.isNull() || T2.isNull())
5969    return false;
5970
5971  // C++11 [basic.types] p11:
5972  // If two types T1 and T2 are the same type, then T1 and T2 are
5973  // layout-compatible types.
5974  if (C.hasSameType(T1, T2))
5975    return true;
5976
5977  T1 = T1.getCanonicalType().getUnqualifiedType();
5978  T2 = T2.getCanonicalType().getUnqualifiedType();
5979
5980  const Type::TypeClass TC1 = T1->getTypeClass();
5981  const Type::TypeClass TC2 = T2->getTypeClass();
5982
5983  if (TC1 != TC2)
5984    return false;
5985
5986  if (TC1 == Type::Enum) {
5987    return isLayoutCompatible(C,
5988                              cast<EnumType>(T1)->getDecl(),
5989                              cast<EnumType>(T2)->getDecl());
5990  } else if (TC1 == Type::Record) {
5991    if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
5992      return false;
5993
5994    return isLayoutCompatible(C,
5995                              cast<RecordType>(T1)->getDecl(),
5996                              cast<RecordType>(T2)->getDecl());
5997  }
5998
5999  return false;
6000}
6001}
6002
6003//===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
6004
6005namespace {
6006/// \brief Given a type tag expression find the type tag itself.
6007///
6008/// \param TypeExpr Type tag expression, as it appears in user's code.
6009///
6010/// \param VD Declaration of an identifier that appears in a type tag.
6011///
6012/// \param MagicValue Type tag magic value.
6013bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
6014                     const ValueDecl **VD, uint64_t *MagicValue) {
6015  while(true) {
6016    if (!TypeExpr)
6017      return false;
6018
6019    TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
6020
6021    switch (TypeExpr->getStmtClass()) {
6022    case Stmt::UnaryOperatorClass: {
6023      const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
6024      if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
6025        TypeExpr = UO->getSubExpr();
6026        continue;
6027      }
6028      return false;
6029    }
6030
6031    case Stmt::DeclRefExprClass: {
6032      const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
6033      *VD = DRE->getDecl();
6034      return true;
6035    }
6036
6037    case Stmt::IntegerLiteralClass: {
6038      const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
6039      llvm::APInt MagicValueAPInt = IL->getValue();
6040      if (MagicValueAPInt.getActiveBits() <= 64) {
6041        *MagicValue = MagicValueAPInt.getZExtValue();
6042        return true;
6043      } else
6044        return false;
6045    }
6046
6047    case Stmt::BinaryConditionalOperatorClass:
6048    case Stmt::ConditionalOperatorClass: {
6049      const AbstractConditionalOperator *ACO =
6050          cast<AbstractConditionalOperator>(TypeExpr);
6051      bool Result;
6052      if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
6053        if (Result)
6054          TypeExpr = ACO->getTrueExpr();
6055        else
6056          TypeExpr = ACO->getFalseExpr();
6057        continue;
6058      }
6059      return false;
6060    }
6061
6062    case Stmt::BinaryOperatorClass: {
6063      const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
6064      if (BO->getOpcode() == BO_Comma) {
6065        TypeExpr = BO->getRHS();
6066        continue;
6067      }
6068      return false;
6069    }
6070
6071    default:
6072      return false;
6073    }
6074  }
6075}
6076
6077/// \brief Retrieve the C type corresponding to type tag TypeExpr.
6078///
6079/// \param TypeExpr Expression that specifies a type tag.
6080///
6081/// \param MagicValues Registered magic values.
6082///
6083/// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
6084///        kind.
6085///
6086/// \param TypeInfo Information about the corresponding C type.
6087///
6088/// \returns true if the corresponding C type was found.
6089bool GetMatchingCType(
6090        const IdentifierInfo *ArgumentKind,
6091        const Expr *TypeExpr, const ASTContext &Ctx,
6092        const llvm::DenseMap<Sema::TypeTagMagicValue,
6093                             Sema::TypeTagData> *MagicValues,
6094        bool &FoundWrongKind,
6095        Sema::TypeTagData &TypeInfo) {
6096  FoundWrongKind = false;
6097
6098  // Variable declaration that has type_tag_for_datatype attribute.
6099  const ValueDecl *VD = NULL;
6100
6101  uint64_t MagicValue;
6102
6103  if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
6104    return false;
6105
6106  if (VD) {
6107    for (specific_attr_iterator<TypeTagForDatatypeAttr>
6108             I = VD->specific_attr_begin<TypeTagForDatatypeAttr>(),
6109             E = VD->specific_attr_end<TypeTagForDatatypeAttr>();
6110         I != E; ++I) {
6111      if (I->getArgumentKind() != ArgumentKind) {
6112        FoundWrongKind = true;
6113        return false;
6114      }
6115      TypeInfo.Type = I->getMatchingCType();
6116      TypeInfo.LayoutCompatible = I->getLayoutCompatible();
6117      TypeInfo.MustBeNull = I->getMustBeNull();
6118      return true;
6119    }
6120    return false;
6121  }
6122
6123  if (!MagicValues)
6124    return false;
6125
6126  llvm::DenseMap<Sema::TypeTagMagicValue,
6127                 Sema::TypeTagData>::const_iterator I =
6128      MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
6129  if (I == MagicValues->end())
6130    return false;
6131
6132  TypeInfo = I->second;
6133  return true;
6134}
6135} // unnamed namespace
6136
6137void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
6138                                      uint64_t MagicValue, QualType Type,
6139                                      bool LayoutCompatible,
6140                                      bool MustBeNull) {
6141  if (!TypeTagForDatatypeMagicValues)
6142    TypeTagForDatatypeMagicValues.reset(
6143        new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
6144
6145  TypeTagMagicValue Magic(ArgumentKind, MagicValue);
6146  (*TypeTagForDatatypeMagicValues)[Magic] =
6147      TypeTagData(Type, LayoutCompatible, MustBeNull);
6148}
6149
6150namespace {
6151bool IsSameCharType(QualType T1, QualType T2) {
6152  const BuiltinType *BT1 = T1->getAs<BuiltinType>();
6153  if (!BT1)
6154    return false;
6155
6156  const BuiltinType *BT2 = T2->getAs<BuiltinType>();
6157  if (!BT2)
6158    return false;
6159
6160  BuiltinType::Kind T1Kind = BT1->getKind();
6161  BuiltinType::Kind T2Kind = BT2->getKind();
6162
6163  return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
6164         (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
6165         (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
6166         (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
6167}
6168} // unnamed namespace
6169
6170void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
6171                                    const Expr * const *ExprArgs) {
6172  const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
6173  bool IsPointerAttr = Attr->getIsPointer();
6174
6175  const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
6176  bool FoundWrongKind;
6177  TypeTagData TypeInfo;
6178  if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
6179                        TypeTagForDatatypeMagicValues.get(),
6180                        FoundWrongKind, TypeInfo)) {
6181    if (FoundWrongKind)
6182      Diag(TypeTagExpr->getExprLoc(),
6183           diag::warn_type_tag_for_datatype_wrong_kind)
6184        << TypeTagExpr->getSourceRange();
6185    return;
6186  }
6187
6188  const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
6189  if (IsPointerAttr) {
6190    // Skip implicit cast of pointer to `void *' (as a function argument).
6191    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
6192      if (ICE->getType()->isVoidPointerType())
6193        ArgumentExpr = ICE->getSubExpr();
6194  }
6195  QualType ArgumentType = ArgumentExpr->getType();
6196
6197  // Passing a `void*' pointer shouldn't trigger a warning.
6198  if (IsPointerAttr && ArgumentType->isVoidPointerType())
6199    return;
6200
6201  if (TypeInfo.MustBeNull) {
6202    // Type tag with matching void type requires a null pointer.
6203    if (!ArgumentExpr->isNullPointerConstant(Context,
6204                                             Expr::NPC_ValueDependentIsNotNull)) {
6205      Diag(ArgumentExpr->getExprLoc(),
6206           diag::warn_type_safety_null_pointer_required)
6207          << ArgumentKind->getName()
6208          << ArgumentExpr->getSourceRange()
6209          << TypeTagExpr->getSourceRange();
6210    }
6211    return;
6212  }
6213
6214  QualType RequiredType = TypeInfo.Type;
6215  if (IsPointerAttr)
6216    RequiredType = Context.getPointerType(RequiredType);
6217
6218  bool mismatch = false;
6219  if (!TypeInfo.LayoutCompatible) {
6220    mismatch = !Context.hasSameType(ArgumentType, RequiredType);
6221
6222    // C++11 [basic.fundamental] p1:
6223    // Plain char, signed char, and unsigned char are three distinct types.
6224    //
6225    // But we treat plain `char' as equivalent to `signed char' or `unsigned
6226    // char' depending on the current char signedness mode.
6227    if (mismatch)
6228      if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
6229                                           RequiredType->getPointeeType())) ||
6230          (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
6231        mismatch = false;
6232  } else
6233    if (IsPointerAttr)
6234      mismatch = !isLayoutCompatible(Context,
6235                                     ArgumentType->getPointeeType(),
6236                                     RequiredType->getPointeeType());
6237    else
6238      mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
6239
6240  if (mismatch)
6241    Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
6242        << ArgumentType << ArgumentKind->getName()
6243        << TypeInfo.LayoutCompatible << RequiredType
6244        << ArgumentExpr->getSourceRange()
6245        << TypeTagExpr->getSourceRange();
6246}
6247