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/SemaInternal.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/CharUnits.h"
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/EvaluatedExprVisitor.h"
21#include "clang/AST/Expr.h"
22#include "clang/AST/ExprCXX.h"
23#include "clang/AST/ExprObjC.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/Analysis/Analyses/FormatString.h"
27#include "clang/Basic/CharInfo.h"
28#include "clang/Basic/TargetBuiltins.h"
29#include "clang/Basic/TargetInfo.h"
30#include "clang/Lex/Preprocessor.h"
31#include "clang/Sema/Initialization.h"
32#include "clang/Sema/Lookup.h"
33#include "clang/Sema/ScopeInfo.h"
34#include "clang/Sema/Sema.h"
35#include "llvm/ADT/BitVector.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/Support/ConvertUTF.h"
39#include "llvm/Support/raw_ostream.h"
40#include <limits>
41using namespace clang;
42using namespace sema;
43
44SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
45                                                    unsigned ByteNo) const {
46  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
47                               PP.getLangOpts(), PP.getTargetInfo());
48}
49
50/// Checks that a call expression's argument count is the desired number.
51/// This is useful when doing custom type-checking.  Returns true on error.
52static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
53  unsigned argCount = call->getNumArgs();
54  if (argCount == desiredArgCount) return false;
55
56  if (argCount < desiredArgCount)
57    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
58        << 0 /*function call*/ << desiredArgCount << argCount
59        << call->getSourceRange();
60
61  // Highlight all the excess arguments.
62  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
63                    call->getArg(argCount - 1)->getLocEnd());
64
65  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
66    << 0 /*function call*/ << desiredArgCount << argCount
67    << call->getArg(1)->getSourceRange();
68}
69
70/// Check that the first argument to __builtin_annotation is an integer
71/// and the second argument is a non-wide string literal.
72static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
73  if (checkArgCount(S, TheCall, 2))
74    return true;
75
76  // First argument should be an integer.
77  Expr *ValArg = TheCall->getArg(0);
78  QualType Ty = ValArg->getType();
79  if (!Ty->isIntegerType()) {
80    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
81      << ValArg->getSourceRange();
82    return true;
83  }
84
85  // Second argument should be a constant string.
86  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
87  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
88  if (!Literal || !Literal->isAscii()) {
89    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
90      << StrArg->getSourceRange();
91    return true;
92  }
93
94  TheCall->setType(Ty);
95  return false;
96}
97
98ExprResult
99Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
100  ExprResult TheCallResult(Owned(TheCall));
101
102  // Find out if any arguments are required to be integer constant expressions.
103  unsigned ICEArguments = 0;
104  ASTContext::GetBuiltinTypeError Error;
105  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
106  if (Error != ASTContext::GE_None)
107    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
108
109  // If any arguments are required to be ICE's, check and diagnose.
110  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
111    // Skip arguments not required to be ICE's.
112    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
113
114    llvm::APSInt Result;
115    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
116      return true;
117    ICEArguments &= ~(1 << ArgNo);
118  }
119
120  switch (BuiltinID) {
121  case Builtin::BI__builtin___CFStringMakeConstantString:
122    assert(TheCall->getNumArgs() == 1 &&
123           "Wrong # arguments to builtin CFStringMakeConstantString");
124    if (CheckObjCString(TheCall->getArg(0)))
125      return ExprError();
126    break;
127  case Builtin::BI__builtin_stdarg_start:
128  case Builtin::BI__builtin_va_start:
129    if (SemaBuiltinVAStart(TheCall))
130      return ExprError();
131    break;
132  case Builtin::BI__builtin_isgreater:
133  case Builtin::BI__builtin_isgreaterequal:
134  case Builtin::BI__builtin_isless:
135  case Builtin::BI__builtin_islessequal:
136  case Builtin::BI__builtin_islessgreater:
137  case Builtin::BI__builtin_isunordered:
138    if (SemaBuiltinUnorderedCompare(TheCall))
139      return ExprError();
140    break;
141  case Builtin::BI__builtin_fpclassify:
142    if (SemaBuiltinFPClassification(TheCall, 6))
143      return ExprError();
144    break;
145  case Builtin::BI__builtin_isfinite:
146  case Builtin::BI__builtin_isinf:
147  case Builtin::BI__builtin_isinf_sign:
148  case Builtin::BI__builtin_isnan:
149  case Builtin::BI__builtin_isnormal:
150    if (SemaBuiltinFPClassification(TheCall, 1))
151      return ExprError();
152    break;
153  case Builtin::BI__builtin_shufflevector:
154    return SemaBuiltinShuffleVector(TheCall);
155    // TheCall will be freed by the smart pointer here, but that's fine, since
156    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
157  case Builtin::BI__builtin_prefetch:
158    if (SemaBuiltinPrefetch(TheCall))
159      return ExprError();
160    break;
161  case Builtin::BI__builtin_object_size:
162    if (SemaBuiltinObjectSize(TheCall))
163      return ExprError();
164    break;
165  case Builtin::BI__builtin_longjmp:
166    if (SemaBuiltinLongjmp(TheCall))
167      return ExprError();
168    break;
169
170  case Builtin::BI__builtin_classify_type:
171    if (checkArgCount(*this, TheCall, 1)) return true;
172    TheCall->setType(Context.IntTy);
173    break;
174  case Builtin::BI__builtin_constant_p:
175    if (checkArgCount(*this, TheCall, 1)) return true;
176    TheCall->setType(Context.IntTy);
177    break;
178  case Builtin::BI__sync_fetch_and_add:
179  case Builtin::BI__sync_fetch_and_add_1:
180  case Builtin::BI__sync_fetch_and_add_2:
181  case Builtin::BI__sync_fetch_and_add_4:
182  case Builtin::BI__sync_fetch_and_add_8:
183  case Builtin::BI__sync_fetch_and_add_16:
184  case Builtin::BI__sync_fetch_and_sub:
185  case Builtin::BI__sync_fetch_and_sub_1:
186  case Builtin::BI__sync_fetch_and_sub_2:
187  case Builtin::BI__sync_fetch_and_sub_4:
188  case Builtin::BI__sync_fetch_and_sub_8:
189  case Builtin::BI__sync_fetch_and_sub_16:
190  case Builtin::BI__sync_fetch_and_or:
191  case Builtin::BI__sync_fetch_and_or_1:
192  case Builtin::BI__sync_fetch_and_or_2:
193  case Builtin::BI__sync_fetch_and_or_4:
194  case Builtin::BI__sync_fetch_and_or_8:
195  case Builtin::BI__sync_fetch_and_or_16:
196  case Builtin::BI__sync_fetch_and_and:
197  case Builtin::BI__sync_fetch_and_and_1:
198  case Builtin::BI__sync_fetch_and_and_2:
199  case Builtin::BI__sync_fetch_and_and_4:
200  case Builtin::BI__sync_fetch_and_and_8:
201  case Builtin::BI__sync_fetch_and_and_16:
202  case Builtin::BI__sync_fetch_and_xor:
203  case Builtin::BI__sync_fetch_and_xor_1:
204  case Builtin::BI__sync_fetch_and_xor_2:
205  case Builtin::BI__sync_fetch_and_xor_4:
206  case Builtin::BI__sync_fetch_and_xor_8:
207  case Builtin::BI__sync_fetch_and_xor_16:
208  case Builtin::BI__sync_add_and_fetch:
209  case Builtin::BI__sync_add_and_fetch_1:
210  case Builtin::BI__sync_add_and_fetch_2:
211  case Builtin::BI__sync_add_and_fetch_4:
212  case Builtin::BI__sync_add_and_fetch_8:
213  case Builtin::BI__sync_add_and_fetch_16:
214  case Builtin::BI__sync_sub_and_fetch:
215  case Builtin::BI__sync_sub_and_fetch_1:
216  case Builtin::BI__sync_sub_and_fetch_2:
217  case Builtin::BI__sync_sub_and_fetch_4:
218  case Builtin::BI__sync_sub_and_fetch_8:
219  case Builtin::BI__sync_sub_and_fetch_16:
220  case Builtin::BI__sync_and_and_fetch:
221  case Builtin::BI__sync_and_and_fetch_1:
222  case Builtin::BI__sync_and_and_fetch_2:
223  case Builtin::BI__sync_and_and_fetch_4:
224  case Builtin::BI__sync_and_and_fetch_8:
225  case Builtin::BI__sync_and_and_fetch_16:
226  case Builtin::BI__sync_or_and_fetch:
227  case Builtin::BI__sync_or_and_fetch_1:
228  case Builtin::BI__sync_or_and_fetch_2:
229  case Builtin::BI__sync_or_and_fetch_4:
230  case Builtin::BI__sync_or_and_fetch_8:
231  case Builtin::BI__sync_or_and_fetch_16:
232  case Builtin::BI__sync_xor_and_fetch:
233  case Builtin::BI__sync_xor_and_fetch_1:
234  case Builtin::BI__sync_xor_and_fetch_2:
235  case Builtin::BI__sync_xor_and_fetch_4:
236  case Builtin::BI__sync_xor_and_fetch_8:
237  case Builtin::BI__sync_xor_and_fetch_16:
238  case Builtin::BI__sync_val_compare_and_swap:
239  case Builtin::BI__sync_val_compare_and_swap_1:
240  case Builtin::BI__sync_val_compare_and_swap_2:
241  case Builtin::BI__sync_val_compare_and_swap_4:
242  case Builtin::BI__sync_val_compare_and_swap_8:
243  case Builtin::BI__sync_val_compare_and_swap_16:
244  case Builtin::BI__sync_bool_compare_and_swap:
245  case Builtin::BI__sync_bool_compare_and_swap_1:
246  case Builtin::BI__sync_bool_compare_and_swap_2:
247  case Builtin::BI__sync_bool_compare_and_swap_4:
248  case Builtin::BI__sync_bool_compare_and_swap_8:
249  case Builtin::BI__sync_bool_compare_and_swap_16:
250  case Builtin::BI__sync_lock_test_and_set:
251  case Builtin::BI__sync_lock_test_and_set_1:
252  case Builtin::BI__sync_lock_test_and_set_2:
253  case Builtin::BI__sync_lock_test_and_set_4:
254  case Builtin::BI__sync_lock_test_and_set_8:
255  case Builtin::BI__sync_lock_test_and_set_16:
256  case Builtin::BI__sync_lock_release:
257  case Builtin::BI__sync_lock_release_1:
258  case Builtin::BI__sync_lock_release_2:
259  case Builtin::BI__sync_lock_release_4:
260  case Builtin::BI__sync_lock_release_8:
261  case Builtin::BI__sync_lock_release_16:
262  case Builtin::BI__sync_swap:
263  case Builtin::BI__sync_swap_1:
264  case Builtin::BI__sync_swap_2:
265  case Builtin::BI__sync_swap_4:
266  case Builtin::BI__sync_swap_8:
267  case Builtin::BI__sync_swap_16:
268    return SemaBuiltinAtomicOverloaded(TheCallResult);
269#define BUILTIN(ID, TYPE, ATTRS)
270#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
271  case Builtin::BI##ID: \
272    return SemaAtomicOpsOverloaded(TheCallResult, AtomicExpr::AO##ID);
273#include "clang/Basic/Builtins.def"
274  case Builtin::BI__builtin_annotation:
275    if (SemaBuiltinAnnotation(*this, TheCall))
276      return ExprError();
277    break;
278  }
279
280  // Since the target specific builtins for each arch overlap, only check those
281  // of the arch we are compiling for.
282  if (BuiltinID >= Builtin::FirstTSBuiltin) {
283    switch (Context.getTargetInfo().getTriple().getArch()) {
284      case llvm::Triple::arm:
285      case llvm::Triple::thumb:
286        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
287          return ExprError();
288        break;
289      case llvm::Triple::mips:
290      case llvm::Triple::mipsel:
291      case llvm::Triple::mips64:
292      case llvm::Triple::mips64el:
293        if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
294          return ExprError();
295        break;
296      default:
297        break;
298    }
299  }
300
301  return TheCallResult;
302}
303
304// Get the valid immediate range for the specified NEON type code.
305static unsigned RFT(unsigned t, bool shift = false) {
306  NeonTypeFlags Type(t);
307  int IsQuad = Type.isQuad();
308  switch (Type.getEltType()) {
309  case NeonTypeFlags::Int8:
310  case NeonTypeFlags::Poly8:
311    return shift ? 7 : (8 << IsQuad) - 1;
312  case NeonTypeFlags::Int16:
313  case NeonTypeFlags::Poly16:
314    return shift ? 15 : (4 << IsQuad) - 1;
315  case NeonTypeFlags::Int32:
316    return shift ? 31 : (2 << IsQuad) - 1;
317  case NeonTypeFlags::Int64:
318    return shift ? 63 : (1 << IsQuad) - 1;
319  case NeonTypeFlags::Float16:
320    assert(!shift && "cannot shift float types!");
321    return (4 << IsQuad) - 1;
322  case NeonTypeFlags::Float32:
323    assert(!shift && "cannot shift float types!");
324    return (2 << IsQuad) - 1;
325  }
326  llvm_unreachable("Invalid NeonTypeFlag!");
327}
328
329/// getNeonEltType - Return the QualType corresponding to the elements of
330/// the vector type specified by the NeonTypeFlags.  This is used to check
331/// the pointer arguments for Neon load/store intrinsics.
332static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
333  switch (Flags.getEltType()) {
334  case NeonTypeFlags::Int8:
335    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
336  case NeonTypeFlags::Int16:
337    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
338  case NeonTypeFlags::Int32:
339    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
340  case NeonTypeFlags::Int64:
341    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
342  case NeonTypeFlags::Poly8:
343    return Context.SignedCharTy;
344  case NeonTypeFlags::Poly16:
345    return Context.ShortTy;
346  case NeonTypeFlags::Float16:
347    return Context.UnsignedShortTy;
348  case NeonTypeFlags::Float32:
349    return Context.FloatTy;
350  }
351  llvm_unreachable("Invalid NeonTypeFlag!");
352}
353
354bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
355  llvm::APSInt Result;
356
357  uint64_t mask = 0;
358  unsigned TV = 0;
359  int PtrArgNum = -1;
360  bool HasConstPtr = false;
361  switch (BuiltinID) {
362#define GET_NEON_OVERLOAD_CHECK
363#include "clang/Basic/arm_neon.inc"
364#undef GET_NEON_OVERLOAD_CHECK
365  }
366
367  // For NEON intrinsics which are overloaded on vector element type, validate
368  // the immediate which specifies which variant to emit.
369  unsigned ImmArg = TheCall->getNumArgs()-1;
370  if (mask) {
371    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
372      return true;
373
374    TV = Result.getLimitedValue(64);
375    if ((TV > 63) || (mask & (1ULL << TV)) == 0)
376      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
377        << TheCall->getArg(ImmArg)->getSourceRange();
378  }
379
380  if (PtrArgNum >= 0) {
381    // Check that pointer arguments have the specified type.
382    Expr *Arg = TheCall->getArg(PtrArgNum);
383    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
384      Arg = ICE->getSubExpr();
385    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
386    QualType RHSTy = RHS.get()->getType();
387    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
388    if (HasConstPtr)
389      EltTy = EltTy.withConst();
390    QualType LHSTy = Context.getPointerType(EltTy);
391    AssignConvertType ConvTy;
392    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
393    if (RHS.isInvalid())
394      return true;
395    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
396                                 RHS.get(), AA_Assigning))
397      return true;
398  }
399
400  // For NEON intrinsics which take an immediate value as part of the
401  // instruction, range check them here.
402  unsigned i = 0, l = 0, u = 0;
403  switch (BuiltinID) {
404  default: return false;
405  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
406  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
407  case ARM::BI__builtin_arm_vcvtr_f:
408  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
409#define GET_NEON_IMMEDIATE_CHECK
410#include "clang/Basic/arm_neon.inc"
411#undef GET_NEON_IMMEDIATE_CHECK
412  };
413
414  // We can't check the value of a dependent argument.
415  if (TheCall->getArg(i)->isTypeDependent() ||
416      TheCall->getArg(i)->isValueDependent())
417    return false;
418
419  // Check that the immediate argument is actually a constant.
420  if (SemaBuiltinConstantArg(TheCall, i, Result))
421    return true;
422
423  // Range check against the upper/lower values for this isntruction.
424  unsigned Val = Result.getZExtValue();
425  if (Val < l || Val > (u + l))
426    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
427      << l << u+l << TheCall->getArg(i)->getSourceRange();
428
429  // FIXME: VFP Intrinsics should error if VFP not present.
430  return false;
431}
432
433bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
434  unsigned i = 0, l = 0, u = 0;
435  switch (BuiltinID) {
436  default: return false;
437  case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
438  case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
439  case Mips::BI__builtin_mips_append: i = 2; l = 0; u = 31; break;
440  case Mips::BI__builtin_mips_balign: i = 2; l = 0; u = 3; break;
441  case Mips::BI__builtin_mips_precr_sra_ph_w: i = 2; l = 0; u = 31; break;
442  case Mips::BI__builtin_mips_precr_sra_r_ph_w: i = 2; l = 0; u = 31; break;
443  case Mips::BI__builtin_mips_prepend: i = 2; l = 0; u = 31; break;
444  };
445
446  // We can't check the value of a dependent argument.
447  if (TheCall->getArg(i)->isTypeDependent() ||
448      TheCall->getArg(i)->isValueDependent())
449    return false;
450
451  // Check that the immediate argument is actually a constant.
452  llvm::APSInt Result;
453  if (SemaBuiltinConstantArg(TheCall, i, Result))
454    return true;
455
456  // Range check against the upper/lower values for this instruction.
457  unsigned Val = Result.getZExtValue();
458  if (Val < l || Val > u)
459    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
460      << l << u << TheCall->getArg(i)->getSourceRange();
461
462  return false;
463}
464
465/// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
466/// parameter with the FormatAttr's correct format_idx and firstDataArg.
467/// Returns true when the format fits the function and the FormatStringInfo has
468/// been populated.
469bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
470                               FormatStringInfo *FSI) {
471  FSI->HasVAListArg = Format->getFirstArg() == 0;
472  FSI->FormatIdx = Format->getFormatIdx() - 1;
473  FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
474
475  // The way the format attribute works in GCC, the implicit this argument
476  // of member functions is counted. However, it doesn't appear in our own
477  // lists, so decrement format_idx in that case.
478  if (IsCXXMember) {
479    if(FSI->FormatIdx == 0)
480      return false;
481    --FSI->FormatIdx;
482    if (FSI->FirstDataArg != 0)
483      --FSI->FirstDataArg;
484  }
485  return true;
486}
487
488/// Handles the checks for format strings, non-POD arguments to vararg
489/// functions, and NULL arguments passed to non-NULL parameters.
490void Sema::checkCall(NamedDecl *FDecl,
491                     ArrayRef<const Expr *> Args,
492                     unsigned NumProtoArgs,
493                     bool IsMemberFunction,
494                     SourceLocation Loc,
495                     SourceRange Range,
496                     VariadicCallType CallType) {
497  if (CurContext->isDependentContext())
498    return;
499
500  // Printf and scanf checking.
501  bool HandledFormatString = false;
502  for (specific_attr_iterator<FormatAttr>
503         I = FDecl->specific_attr_begin<FormatAttr>(),
504         E = FDecl->specific_attr_end<FormatAttr>(); I != E ; ++I)
505    if (CheckFormatArguments(*I, Args, IsMemberFunction, CallType, Loc, Range))
506        HandledFormatString = true;
507
508  // Refuse POD arguments that weren't caught by the format string
509  // checks above.
510  if (!HandledFormatString && CallType != VariadicDoesNotApply)
511    for (unsigned ArgIdx = NumProtoArgs; ArgIdx < Args.size(); ++ArgIdx) {
512      // Args[ArgIdx] can be null in malformed code.
513      if (const Expr *Arg = Args[ArgIdx])
514        variadicArgumentPODCheck(Arg, CallType);
515    }
516
517  for (specific_attr_iterator<NonNullAttr>
518         I = FDecl->specific_attr_begin<NonNullAttr>(),
519         E = FDecl->specific_attr_end<NonNullAttr>(); I != E; ++I)
520    CheckNonNullArguments(*I, Args.data(), Loc);
521
522  // Type safety checking.
523  for (specific_attr_iterator<ArgumentWithTypeTagAttr>
524         i = FDecl->specific_attr_begin<ArgumentWithTypeTagAttr>(),
525         e = FDecl->specific_attr_end<ArgumentWithTypeTagAttr>(); i != e; ++i) {
526    CheckArgumentWithTypeTag(*i, Args.data());
527  }
528}
529
530/// CheckConstructorCall - Check a constructor call for correctness and safety
531/// properties not enforced by the C type system.
532void Sema::CheckConstructorCall(FunctionDecl *FDecl,
533                                ArrayRef<const Expr *> Args,
534                                const FunctionProtoType *Proto,
535                                SourceLocation Loc) {
536  VariadicCallType CallType =
537    Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
538  checkCall(FDecl, Args, Proto->getNumArgs(),
539            /*IsMemberFunction=*/true, Loc, SourceRange(), CallType);
540}
541
542/// CheckFunctionCall - Check a direct function call for various correctness
543/// and safety properties not strictly enforced by the C type system.
544bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
545                             const FunctionProtoType *Proto) {
546  bool IsMemberOperatorCall = isa<CXXOperatorCallExpr>(TheCall) &&
547                              isa<CXXMethodDecl>(FDecl);
548  bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall) ||
549                          IsMemberOperatorCall;
550  VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
551                                                  TheCall->getCallee());
552  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
553  Expr** Args = TheCall->getArgs();
554  unsigned NumArgs = TheCall->getNumArgs();
555  if (IsMemberOperatorCall) {
556    // If this is a call to a member operator, hide the first argument
557    // from checkCall.
558    // FIXME: Our choice of AST representation here is less than ideal.
559    ++Args;
560    --NumArgs;
561  }
562  checkCall(FDecl, llvm::makeArrayRef<const Expr *>(Args, NumArgs),
563            NumProtoArgs,
564            IsMemberFunction, TheCall->getRParenLoc(),
565            TheCall->getCallee()->getSourceRange(), CallType);
566
567  IdentifierInfo *FnInfo = FDecl->getIdentifier();
568  // None of the checks below are needed for functions that don't have
569  // simple names (e.g., C++ conversion functions).
570  if (!FnInfo)
571    return false;
572
573  unsigned CMId = FDecl->getMemoryFunctionKind();
574  if (CMId == 0)
575    return false;
576
577  // Handle memory setting and copying functions.
578  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
579    CheckStrlcpycatArguments(TheCall, FnInfo);
580  else if (CMId == Builtin::BIstrncat)
581    CheckStrncatArguments(TheCall, FnInfo);
582  else
583    CheckMemaccessArguments(TheCall, CMId, FnInfo);
584
585  return false;
586}
587
588bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
589                               ArrayRef<const Expr *> Args) {
590  VariadicCallType CallType =
591      Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
592
593  checkCall(Method, Args, Method->param_size(),
594            /*IsMemberFunction=*/false,
595            lbrac, Method->getSourceRange(), CallType);
596
597  return false;
598}
599
600bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall,
601                          const FunctionProtoType *Proto) {
602  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
603  if (!V)
604    return false;
605
606  QualType Ty = V->getType();
607  if (!Ty->isBlockPointerType())
608    return false;
609
610  VariadicCallType CallType =
611      Proto && Proto->isVariadic() ? VariadicBlock : VariadicDoesNotApply ;
612  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
613
614  checkCall(NDecl,
615            llvm::makeArrayRef<const Expr *>(TheCall->getArgs(),
616                                             TheCall->getNumArgs()),
617            NumProtoArgs, /*IsMemberFunction=*/false,
618            TheCall->getRParenLoc(),
619            TheCall->getCallee()->getSourceRange(), CallType);
620
621  return false;
622}
623
624ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
625                                         AtomicExpr::AtomicOp Op) {
626  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
627  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
628
629  // All these operations take one of the following forms:
630  enum {
631    // C    __c11_atomic_init(A *, C)
632    Init,
633    // C    __c11_atomic_load(A *, int)
634    Load,
635    // void __atomic_load(A *, CP, int)
636    Copy,
637    // C    __c11_atomic_add(A *, M, int)
638    Arithmetic,
639    // C    __atomic_exchange_n(A *, CP, int)
640    Xchg,
641    // void __atomic_exchange(A *, C *, CP, int)
642    GNUXchg,
643    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
644    C11CmpXchg,
645    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
646    GNUCmpXchg
647  } Form = Init;
648  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
649  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
650  // where:
651  //   C is an appropriate type,
652  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
653  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
654  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
655  //   the int parameters are for orderings.
656
657  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
658         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
659         && "need to update code for modified C11 atomics");
660  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
661               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
662  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
663             Op == AtomicExpr::AO__atomic_store_n ||
664             Op == AtomicExpr::AO__atomic_exchange_n ||
665             Op == AtomicExpr::AO__atomic_compare_exchange_n;
666  bool IsAddSub = false;
667
668  switch (Op) {
669  case AtomicExpr::AO__c11_atomic_init:
670    Form = Init;
671    break;
672
673  case AtomicExpr::AO__c11_atomic_load:
674  case AtomicExpr::AO__atomic_load_n:
675    Form = Load;
676    break;
677
678  case AtomicExpr::AO__c11_atomic_store:
679  case AtomicExpr::AO__atomic_load:
680  case AtomicExpr::AO__atomic_store:
681  case AtomicExpr::AO__atomic_store_n:
682    Form = Copy;
683    break;
684
685  case AtomicExpr::AO__c11_atomic_fetch_add:
686  case AtomicExpr::AO__c11_atomic_fetch_sub:
687  case AtomicExpr::AO__atomic_fetch_add:
688  case AtomicExpr::AO__atomic_fetch_sub:
689  case AtomicExpr::AO__atomic_add_fetch:
690  case AtomicExpr::AO__atomic_sub_fetch:
691    IsAddSub = true;
692    // Fall through.
693  case AtomicExpr::AO__c11_atomic_fetch_and:
694  case AtomicExpr::AO__c11_atomic_fetch_or:
695  case AtomicExpr::AO__c11_atomic_fetch_xor:
696  case AtomicExpr::AO__atomic_fetch_and:
697  case AtomicExpr::AO__atomic_fetch_or:
698  case AtomicExpr::AO__atomic_fetch_xor:
699  case AtomicExpr::AO__atomic_fetch_nand:
700  case AtomicExpr::AO__atomic_and_fetch:
701  case AtomicExpr::AO__atomic_or_fetch:
702  case AtomicExpr::AO__atomic_xor_fetch:
703  case AtomicExpr::AO__atomic_nand_fetch:
704    Form = Arithmetic;
705    break;
706
707  case AtomicExpr::AO__c11_atomic_exchange:
708  case AtomicExpr::AO__atomic_exchange_n:
709    Form = Xchg;
710    break;
711
712  case AtomicExpr::AO__atomic_exchange:
713    Form = GNUXchg;
714    break;
715
716  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
717  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
718    Form = C11CmpXchg;
719    break;
720
721  case AtomicExpr::AO__atomic_compare_exchange:
722  case AtomicExpr::AO__atomic_compare_exchange_n:
723    Form = GNUCmpXchg;
724    break;
725  }
726
727  // Check we have the right number of arguments.
728  if (TheCall->getNumArgs() < NumArgs[Form]) {
729    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
730      << 0 << NumArgs[Form] << TheCall->getNumArgs()
731      << TheCall->getCallee()->getSourceRange();
732    return ExprError();
733  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
734    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
735         diag::err_typecheck_call_too_many_args)
736      << 0 << NumArgs[Form] << TheCall->getNumArgs()
737      << TheCall->getCallee()->getSourceRange();
738    return ExprError();
739  }
740
741  // Inspect the first argument of the atomic operation.
742  Expr *Ptr = TheCall->getArg(0);
743  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
744  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
745  if (!pointerType) {
746    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
747      << Ptr->getType() << Ptr->getSourceRange();
748    return ExprError();
749  }
750
751  // For a __c11 builtin, this should be a pointer to an _Atomic type.
752  QualType AtomTy = pointerType->getPointeeType(); // 'A'
753  QualType ValType = AtomTy; // 'C'
754  if (IsC11) {
755    if (!AtomTy->isAtomicType()) {
756      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
757        << Ptr->getType() << Ptr->getSourceRange();
758      return ExprError();
759    }
760    if (AtomTy.isConstQualified()) {
761      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
762        << Ptr->getType() << Ptr->getSourceRange();
763      return ExprError();
764    }
765    ValType = AtomTy->getAs<AtomicType>()->getValueType();
766  }
767
768  // For an arithmetic operation, the implied arithmetic must be well-formed.
769  if (Form == Arithmetic) {
770    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
771    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
772      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
773        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
774      return ExprError();
775    }
776    if (!IsAddSub && !ValType->isIntegerType()) {
777      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
778        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
779      return ExprError();
780    }
781  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
782    // For __atomic_*_n operations, the value type must be a scalar integral or
783    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
784    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
785      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
786    return ExprError();
787  }
788
789  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
790    // For GNU atomics, require a trivially-copyable type. This is not part of
791    // the GNU atomics specification, but we enforce it for sanity.
792    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
793      << Ptr->getType() << Ptr->getSourceRange();
794    return ExprError();
795  }
796
797  // FIXME: For any builtin other than a load, the ValType must not be
798  // const-qualified.
799
800  switch (ValType.getObjCLifetime()) {
801  case Qualifiers::OCL_None:
802  case Qualifiers::OCL_ExplicitNone:
803    // okay
804    break;
805
806  case Qualifiers::OCL_Weak:
807  case Qualifiers::OCL_Strong:
808  case Qualifiers::OCL_Autoreleasing:
809    // FIXME: Can this happen? By this point, ValType should be known
810    // to be trivially copyable.
811    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
812      << ValType << Ptr->getSourceRange();
813    return ExprError();
814  }
815
816  QualType ResultType = ValType;
817  if (Form == Copy || Form == GNUXchg || Form == Init)
818    ResultType = Context.VoidTy;
819  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
820    ResultType = Context.BoolTy;
821
822  // The type of a parameter passed 'by value'. In the GNU atomics, such
823  // arguments are actually passed as pointers.
824  QualType ByValType = ValType; // 'CP'
825  if (!IsC11 && !IsN)
826    ByValType = Ptr->getType();
827
828  // The first argument --- the pointer --- has a fixed type; we
829  // deduce the types of the rest of the arguments accordingly.  Walk
830  // the remaining arguments, converting them to the deduced value type.
831  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
832    QualType Ty;
833    if (i < NumVals[Form] + 1) {
834      switch (i) {
835      case 1:
836        // The second argument is the non-atomic operand. For arithmetic, this
837        // is always passed by value, and for a compare_exchange it is always
838        // passed by address. For the rest, GNU uses by-address and C11 uses
839        // by-value.
840        assert(Form != Load);
841        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
842          Ty = ValType;
843        else if (Form == Copy || Form == Xchg)
844          Ty = ByValType;
845        else if (Form == Arithmetic)
846          Ty = Context.getPointerDiffType();
847        else
848          Ty = Context.getPointerType(ValType.getUnqualifiedType());
849        break;
850      case 2:
851        // The third argument to compare_exchange / GNU exchange is a
852        // (pointer to a) desired value.
853        Ty = ByValType;
854        break;
855      case 3:
856        // The fourth argument to GNU compare_exchange is a 'weak' flag.
857        Ty = Context.BoolTy;
858        break;
859      }
860    } else {
861      // The order(s) are always converted to int.
862      Ty = Context.IntTy;
863    }
864
865    InitializedEntity Entity =
866        InitializedEntity::InitializeParameter(Context, Ty, false);
867    ExprResult Arg = TheCall->getArg(i);
868    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
869    if (Arg.isInvalid())
870      return true;
871    TheCall->setArg(i, Arg.get());
872  }
873
874  // Permute the arguments into a 'consistent' order.
875  SmallVector<Expr*, 5> SubExprs;
876  SubExprs.push_back(Ptr);
877  switch (Form) {
878  case Init:
879    // Note, AtomicExpr::getVal1() has a special case for this atomic.
880    SubExprs.push_back(TheCall->getArg(1)); // Val1
881    break;
882  case Load:
883    SubExprs.push_back(TheCall->getArg(1)); // Order
884    break;
885  case Copy:
886  case Arithmetic:
887  case Xchg:
888    SubExprs.push_back(TheCall->getArg(2)); // Order
889    SubExprs.push_back(TheCall->getArg(1)); // Val1
890    break;
891  case GNUXchg:
892    // Note, AtomicExpr::getVal2() has a special case for this atomic.
893    SubExprs.push_back(TheCall->getArg(3)); // Order
894    SubExprs.push_back(TheCall->getArg(1)); // Val1
895    SubExprs.push_back(TheCall->getArg(2)); // Val2
896    break;
897  case C11CmpXchg:
898    SubExprs.push_back(TheCall->getArg(3)); // Order
899    SubExprs.push_back(TheCall->getArg(1)); // Val1
900    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
901    SubExprs.push_back(TheCall->getArg(2)); // Val2
902    break;
903  case GNUCmpXchg:
904    SubExprs.push_back(TheCall->getArg(4)); // Order
905    SubExprs.push_back(TheCall->getArg(1)); // Val1
906    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
907    SubExprs.push_back(TheCall->getArg(2)); // Val2
908    SubExprs.push_back(TheCall->getArg(3)); // Weak
909    break;
910  }
911
912  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
913                                        SubExprs, ResultType, Op,
914                                        TheCall->getRParenLoc()));
915}
916
917
918/// checkBuiltinArgument - Given a call to a builtin function, perform
919/// normal type-checking on the given argument, updating the call in
920/// place.  This is useful when a builtin function requires custom
921/// type-checking for some of its arguments but not necessarily all of
922/// them.
923///
924/// Returns true on error.
925static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
926  FunctionDecl *Fn = E->getDirectCallee();
927  assert(Fn && "builtin call without direct callee!");
928
929  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
930  InitializedEntity Entity =
931    InitializedEntity::InitializeParameter(S.Context, Param);
932
933  ExprResult Arg = E->getArg(0);
934  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
935  if (Arg.isInvalid())
936    return true;
937
938  E->setArg(ArgIndex, Arg.take());
939  return false;
940}
941
942/// SemaBuiltinAtomicOverloaded - We have a call to a function like
943/// __sync_fetch_and_add, which is an overloaded function based on the pointer
944/// type of its first argument.  The main ActOnCallExpr routines have already
945/// promoted the types of arguments because all of these calls are prototyped as
946/// void(...).
947///
948/// This function goes through and does final semantic checking for these
949/// builtins,
950ExprResult
951Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
952  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
953  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
954  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
955
956  // Ensure that we have at least one argument to do type inference from.
957  if (TheCall->getNumArgs() < 1) {
958    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
959      << 0 << 1 << TheCall->getNumArgs()
960      << TheCall->getCallee()->getSourceRange();
961    return ExprError();
962  }
963
964  // Inspect the first argument of the atomic builtin.  This should always be
965  // a pointer type, whose element is an integral scalar or pointer type.
966  // Because it is a pointer type, we don't have to worry about any implicit
967  // casts here.
968  // FIXME: We don't allow floating point scalars as input.
969  Expr *FirstArg = TheCall->getArg(0);
970  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
971  if (FirstArgResult.isInvalid())
972    return ExprError();
973  FirstArg = FirstArgResult.take();
974  TheCall->setArg(0, FirstArg);
975
976  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
977  if (!pointerType) {
978    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
979      << FirstArg->getType() << FirstArg->getSourceRange();
980    return ExprError();
981  }
982
983  QualType ValType = pointerType->getPointeeType();
984  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
985      !ValType->isBlockPointerType()) {
986    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
987      << FirstArg->getType() << FirstArg->getSourceRange();
988    return ExprError();
989  }
990
991  switch (ValType.getObjCLifetime()) {
992  case Qualifiers::OCL_None:
993  case Qualifiers::OCL_ExplicitNone:
994    // okay
995    break;
996
997  case Qualifiers::OCL_Weak:
998  case Qualifiers::OCL_Strong:
999  case Qualifiers::OCL_Autoreleasing:
1000    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1001      << ValType << FirstArg->getSourceRange();
1002    return ExprError();
1003  }
1004
1005  // Strip any qualifiers off ValType.
1006  ValType = ValType.getUnqualifiedType();
1007
1008  // The majority of builtins return a value, but a few have special return
1009  // types, so allow them to override appropriately below.
1010  QualType ResultType = ValType;
1011
1012  // We need to figure out which concrete builtin this maps onto.  For example,
1013  // __sync_fetch_and_add with a 2 byte object turns into
1014  // __sync_fetch_and_add_2.
1015#define BUILTIN_ROW(x) \
1016  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
1017    Builtin::BI##x##_8, Builtin::BI##x##_16 }
1018
1019  static const unsigned BuiltinIndices[][5] = {
1020    BUILTIN_ROW(__sync_fetch_and_add),
1021    BUILTIN_ROW(__sync_fetch_and_sub),
1022    BUILTIN_ROW(__sync_fetch_and_or),
1023    BUILTIN_ROW(__sync_fetch_and_and),
1024    BUILTIN_ROW(__sync_fetch_and_xor),
1025
1026    BUILTIN_ROW(__sync_add_and_fetch),
1027    BUILTIN_ROW(__sync_sub_and_fetch),
1028    BUILTIN_ROW(__sync_and_and_fetch),
1029    BUILTIN_ROW(__sync_or_and_fetch),
1030    BUILTIN_ROW(__sync_xor_and_fetch),
1031
1032    BUILTIN_ROW(__sync_val_compare_and_swap),
1033    BUILTIN_ROW(__sync_bool_compare_and_swap),
1034    BUILTIN_ROW(__sync_lock_test_and_set),
1035    BUILTIN_ROW(__sync_lock_release),
1036    BUILTIN_ROW(__sync_swap)
1037  };
1038#undef BUILTIN_ROW
1039
1040  // Determine the index of the size.
1041  unsigned SizeIndex;
1042  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1043  case 1: SizeIndex = 0; break;
1044  case 2: SizeIndex = 1; break;
1045  case 4: SizeIndex = 2; break;
1046  case 8: SizeIndex = 3; break;
1047  case 16: SizeIndex = 4; break;
1048  default:
1049    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1050      << FirstArg->getType() << FirstArg->getSourceRange();
1051    return ExprError();
1052  }
1053
1054  // Each of these builtins has one pointer argument, followed by some number of
1055  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1056  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1057  // as the number of fixed args.
1058  unsigned BuiltinID = FDecl->getBuiltinID();
1059  unsigned BuiltinIndex, NumFixed = 1;
1060  switch (BuiltinID) {
1061  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1062  case Builtin::BI__sync_fetch_and_add:
1063  case Builtin::BI__sync_fetch_and_add_1:
1064  case Builtin::BI__sync_fetch_and_add_2:
1065  case Builtin::BI__sync_fetch_and_add_4:
1066  case Builtin::BI__sync_fetch_and_add_8:
1067  case Builtin::BI__sync_fetch_and_add_16:
1068    BuiltinIndex = 0;
1069    break;
1070
1071  case Builtin::BI__sync_fetch_and_sub:
1072  case Builtin::BI__sync_fetch_and_sub_1:
1073  case Builtin::BI__sync_fetch_and_sub_2:
1074  case Builtin::BI__sync_fetch_and_sub_4:
1075  case Builtin::BI__sync_fetch_and_sub_8:
1076  case Builtin::BI__sync_fetch_and_sub_16:
1077    BuiltinIndex = 1;
1078    break;
1079
1080  case Builtin::BI__sync_fetch_and_or:
1081  case Builtin::BI__sync_fetch_and_or_1:
1082  case Builtin::BI__sync_fetch_and_or_2:
1083  case Builtin::BI__sync_fetch_and_or_4:
1084  case Builtin::BI__sync_fetch_and_or_8:
1085  case Builtin::BI__sync_fetch_and_or_16:
1086    BuiltinIndex = 2;
1087    break;
1088
1089  case Builtin::BI__sync_fetch_and_and:
1090  case Builtin::BI__sync_fetch_and_and_1:
1091  case Builtin::BI__sync_fetch_and_and_2:
1092  case Builtin::BI__sync_fetch_and_and_4:
1093  case Builtin::BI__sync_fetch_and_and_8:
1094  case Builtin::BI__sync_fetch_and_and_16:
1095    BuiltinIndex = 3;
1096    break;
1097
1098  case Builtin::BI__sync_fetch_and_xor:
1099  case Builtin::BI__sync_fetch_and_xor_1:
1100  case Builtin::BI__sync_fetch_and_xor_2:
1101  case Builtin::BI__sync_fetch_and_xor_4:
1102  case Builtin::BI__sync_fetch_and_xor_8:
1103  case Builtin::BI__sync_fetch_and_xor_16:
1104    BuiltinIndex = 4;
1105    break;
1106
1107  case Builtin::BI__sync_add_and_fetch:
1108  case Builtin::BI__sync_add_and_fetch_1:
1109  case Builtin::BI__sync_add_and_fetch_2:
1110  case Builtin::BI__sync_add_and_fetch_4:
1111  case Builtin::BI__sync_add_and_fetch_8:
1112  case Builtin::BI__sync_add_and_fetch_16:
1113    BuiltinIndex = 5;
1114    break;
1115
1116  case Builtin::BI__sync_sub_and_fetch:
1117  case Builtin::BI__sync_sub_and_fetch_1:
1118  case Builtin::BI__sync_sub_and_fetch_2:
1119  case Builtin::BI__sync_sub_and_fetch_4:
1120  case Builtin::BI__sync_sub_and_fetch_8:
1121  case Builtin::BI__sync_sub_and_fetch_16:
1122    BuiltinIndex = 6;
1123    break;
1124
1125  case Builtin::BI__sync_and_and_fetch:
1126  case Builtin::BI__sync_and_and_fetch_1:
1127  case Builtin::BI__sync_and_and_fetch_2:
1128  case Builtin::BI__sync_and_and_fetch_4:
1129  case Builtin::BI__sync_and_and_fetch_8:
1130  case Builtin::BI__sync_and_and_fetch_16:
1131    BuiltinIndex = 7;
1132    break;
1133
1134  case Builtin::BI__sync_or_and_fetch:
1135  case Builtin::BI__sync_or_and_fetch_1:
1136  case Builtin::BI__sync_or_and_fetch_2:
1137  case Builtin::BI__sync_or_and_fetch_4:
1138  case Builtin::BI__sync_or_and_fetch_8:
1139  case Builtin::BI__sync_or_and_fetch_16:
1140    BuiltinIndex = 8;
1141    break;
1142
1143  case Builtin::BI__sync_xor_and_fetch:
1144  case Builtin::BI__sync_xor_and_fetch_1:
1145  case Builtin::BI__sync_xor_and_fetch_2:
1146  case Builtin::BI__sync_xor_and_fetch_4:
1147  case Builtin::BI__sync_xor_and_fetch_8:
1148  case Builtin::BI__sync_xor_and_fetch_16:
1149    BuiltinIndex = 9;
1150    break;
1151
1152  case Builtin::BI__sync_val_compare_and_swap:
1153  case Builtin::BI__sync_val_compare_and_swap_1:
1154  case Builtin::BI__sync_val_compare_and_swap_2:
1155  case Builtin::BI__sync_val_compare_and_swap_4:
1156  case Builtin::BI__sync_val_compare_and_swap_8:
1157  case Builtin::BI__sync_val_compare_and_swap_16:
1158    BuiltinIndex = 10;
1159    NumFixed = 2;
1160    break;
1161
1162  case Builtin::BI__sync_bool_compare_and_swap:
1163  case Builtin::BI__sync_bool_compare_and_swap_1:
1164  case Builtin::BI__sync_bool_compare_and_swap_2:
1165  case Builtin::BI__sync_bool_compare_and_swap_4:
1166  case Builtin::BI__sync_bool_compare_and_swap_8:
1167  case Builtin::BI__sync_bool_compare_and_swap_16:
1168    BuiltinIndex = 11;
1169    NumFixed = 2;
1170    ResultType = Context.BoolTy;
1171    break;
1172
1173  case Builtin::BI__sync_lock_test_and_set:
1174  case Builtin::BI__sync_lock_test_and_set_1:
1175  case Builtin::BI__sync_lock_test_and_set_2:
1176  case Builtin::BI__sync_lock_test_and_set_4:
1177  case Builtin::BI__sync_lock_test_and_set_8:
1178  case Builtin::BI__sync_lock_test_and_set_16:
1179    BuiltinIndex = 12;
1180    break;
1181
1182  case Builtin::BI__sync_lock_release:
1183  case Builtin::BI__sync_lock_release_1:
1184  case Builtin::BI__sync_lock_release_2:
1185  case Builtin::BI__sync_lock_release_4:
1186  case Builtin::BI__sync_lock_release_8:
1187  case Builtin::BI__sync_lock_release_16:
1188    BuiltinIndex = 13;
1189    NumFixed = 0;
1190    ResultType = Context.VoidTy;
1191    break;
1192
1193  case Builtin::BI__sync_swap:
1194  case Builtin::BI__sync_swap_1:
1195  case Builtin::BI__sync_swap_2:
1196  case Builtin::BI__sync_swap_4:
1197  case Builtin::BI__sync_swap_8:
1198  case Builtin::BI__sync_swap_16:
1199    BuiltinIndex = 14;
1200    break;
1201  }
1202
1203  // Now that we know how many fixed arguments we expect, first check that we
1204  // have at least that many.
1205  if (TheCall->getNumArgs() < 1+NumFixed) {
1206    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1207      << 0 << 1+NumFixed << TheCall->getNumArgs()
1208      << TheCall->getCallee()->getSourceRange();
1209    return ExprError();
1210  }
1211
1212  // Get the decl for the concrete builtin from this, we can tell what the
1213  // concrete integer type we should convert to is.
1214  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1215  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1216  FunctionDecl *NewBuiltinDecl;
1217  if (NewBuiltinID == BuiltinID)
1218    NewBuiltinDecl = FDecl;
1219  else {
1220    // Perform builtin lookup to avoid redeclaring it.
1221    DeclarationName DN(&Context.Idents.get(NewBuiltinName));
1222    LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
1223    LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
1224    assert(Res.getFoundDecl());
1225    NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
1226    if (NewBuiltinDecl == 0)
1227      return ExprError();
1228  }
1229
1230  // The first argument --- the pointer --- has a fixed type; we
1231  // deduce the types of the rest of the arguments accordingly.  Walk
1232  // the remaining arguments, converting them to the deduced value type.
1233  for (unsigned i = 0; i != NumFixed; ++i) {
1234    ExprResult Arg = TheCall->getArg(i+1);
1235
1236    // GCC does an implicit conversion to the pointer or integer ValType.  This
1237    // can fail in some cases (1i -> int**), check for this error case now.
1238    // Initialize the argument.
1239    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1240                                                   ValType, /*consume*/ false);
1241    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1242    if (Arg.isInvalid())
1243      return ExprError();
1244
1245    // Okay, we have something that *can* be converted to the right type.  Check
1246    // to see if there is a potentially weird extension going on here.  This can
1247    // happen when you do an atomic operation on something like an char* and
1248    // pass in 42.  The 42 gets converted to char.  This is even more strange
1249    // for things like 45.123 -> char, etc.
1250    // FIXME: Do this check.
1251    TheCall->setArg(i+1, Arg.take());
1252  }
1253
1254  ASTContext& Context = this->getASTContext();
1255
1256  // Create a new DeclRefExpr to refer to the new decl.
1257  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1258      Context,
1259      DRE->getQualifierLoc(),
1260      SourceLocation(),
1261      NewBuiltinDecl,
1262      /*enclosing*/ false,
1263      DRE->getLocation(),
1264      Context.BuiltinFnTy,
1265      DRE->getValueKind());
1266
1267  // Set the callee in the CallExpr.
1268  // FIXME: This loses syntactic information.
1269  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
1270  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
1271                                              CK_BuiltinFnToFnPtr);
1272  TheCall->setCallee(PromotedCall.take());
1273
1274  // Change the result type of the call to match the original value type. This
1275  // is arbitrary, but the codegen for these builtins ins design to handle it
1276  // gracefully.
1277  TheCall->setType(ResultType);
1278
1279  return TheCallResult;
1280}
1281
1282/// CheckObjCString - Checks that the argument to the builtin
1283/// CFString constructor is correct
1284/// Note: It might also make sense to do the UTF-16 conversion here (would
1285/// simplify the backend).
1286bool Sema::CheckObjCString(Expr *Arg) {
1287  Arg = Arg->IgnoreParenCasts();
1288  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1289
1290  if (!Literal || !Literal->isAscii()) {
1291    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1292      << Arg->getSourceRange();
1293    return true;
1294  }
1295
1296  if (Literal->containsNonAsciiOrNull()) {
1297    StringRef String = Literal->getString();
1298    unsigned NumBytes = String.size();
1299    SmallVector<UTF16, 128> ToBuf(NumBytes);
1300    const UTF8 *FromPtr = (const UTF8 *)String.data();
1301    UTF16 *ToPtr = &ToBuf[0];
1302
1303    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1304                                                 &ToPtr, ToPtr + NumBytes,
1305                                                 strictConversion);
1306    // Check for conversion failure.
1307    if (Result != conversionOK)
1308      Diag(Arg->getLocStart(),
1309           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1310  }
1311  return false;
1312}
1313
1314/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1315/// Emit an error and return true on failure, return false on success.
1316bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1317  Expr *Fn = TheCall->getCallee();
1318  if (TheCall->getNumArgs() > 2) {
1319    Diag(TheCall->getArg(2)->getLocStart(),
1320         diag::err_typecheck_call_too_many_args)
1321      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1322      << Fn->getSourceRange()
1323      << SourceRange(TheCall->getArg(2)->getLocStart(),
1324                     (*(TheCall->arg_end()-1))->getLocEnd());
1325    return true;
1326  }
1327
1328  if (TheCall->getNumArgs() < 2) {
1329    return Diag(TheCall->getLocEnd(),
1330      diag::err_typecheck_call_too_few_args_at_least)
1331      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1332  }
1333
1334  // Type-check the first argument normally.
1335  if (checkBuiltinArgument(*this, TheCall, 0))
1336    return true;
1337
1338  // Determine whether the current function is variadic or not.
1339  BlockScopeInfo *CurBlock = getCurBlock();
1340  bool isVariadic;
1341  if (CurBlock)
1342    isVariadic = CurBlock->TheDecl->isVariadic();
1343  else if (FunctionDecl *FD = getCurFunctionDecl())
1344    isVariadic = FD->isVariadic();
1345  else
1346    isVariadic = getCurMethodDecl()->isVariadic();
1347
1348  if (!isVariadic) {
1349    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1350    return true;
1351  }
1352
1353  // Verify that the second argument to the builtin is the last argument of the
1354  // current function or method.
1355  bool SecondArgIsLastNamedArgument = false;
1356  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1357
1358  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1359    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1360      // FIXME: This isn't correct for methods (results in bogus warning).
1361      // Get the last formal in the current function.
1362      const ParmVarDecl *LastArg;
1363      if (CurBlock)
1364        LastArg = *(CurBlock->TheDecl->param_end()-1);
1365      else if (FunctionDecl *FD = getCurFunctionDecl())
1366        LastArg = *(FD->param_end()-1);
1367      else
1368        LastArg = *(getCurMethodDecl()->param_end()-1);
1369      SecondArgIsLastNamedArgument = PV == LastArg;
1370    }
1371  }
1372
1373  if (!SecondArgIsLastNamedArgument)
1374    Diag(TheCall->getArg(1)->getLocStart(),
1375         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1376  return false;
1377}
1378
1379/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1380/// friends.  This is declared to take (...), so we have to check everything.
1381bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1382  if (TheCall->getNumArgs() < 2)
1383    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1384      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1385  if (TheCall->getNumArgs() > 2)
1386    return Diag(TheCall->getArg(2)->getLocStart(),
1387                diag::err_typecheck_call_too_many_args)
1388      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1389      << SourceRange(TheCall->getArg(2)->getLocStart(),
1390                     (*(TheCall->arg_end()-1))->getLocEnd());
1391
1392  ExprResult OrigArg0 = TheCall->getArg(0);
1393  ExprResult OrigArg1 = TheCall->getArg(1);
1394
1395  // Do standard promotions between the two arguments, returning their common
1396  // type.
1397  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1398  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1399    return true;
1400
1401  // Make sure any conversions are pushed back into the call; this is
1402  // type safe since unordered compare builtins are declared as "_Bool
1403  // foo(...)".
1404  TheCall->setArg(0, OrigArg0.get());
1405  TheCall->setArg(1, OrigArg1.get());
1406
1407  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1408    return false;
1409
1410  // If the common type isn't a real floating type, then the arguments were
1411  // invalid for this operation.
1412  if (Res.isNull() || !Res->isRealFloatingType())
1413    return Diag(OrigArg0.get()->getLocStart(),
1414                diag::err_typecheck_call_invalid_ordered_compare)
1415      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1416      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1417
1418  return false;
1419}
1420
1421/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1422/// __builtin_isnan and friends.  This is declared to take (...), so we have
1423/// to check everything. We expect the last argument to be a floating point
1424/// value.
1425bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1426  if (TheCall->getNumArgs() < NumArgs)
1427    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1428      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1429  if (TheCall->getNumArgs() > NumArgs)
1430    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1431                diag::err_typecheck_call_too_many_args)
1432      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1433      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1434                     (*(TheCall->arg_end()-1))->getLocEnd());
1435
1436  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1437
1438  if (OrigArg->isTypeDependent())
1439    return false;
1440
1441  // This operation requires a non-_Complex floating-point number.
1442  if (!OrigArg->getType()->isRealFloatingType())
1443    return Diag(OrigArg->getLocStart(),
1444                diag::err_typecheck_call_invalid_unary_fp)
1445      << OrigArg->getType() << OrigArg->getSourceRange();
1446
1447  // If this is an implicit conversion from float -> double, remove it.
1448  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1449    Expr *CastArg = Cast->getSubExpr();
1450    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1451      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1452             "promotion from float to double is the only expected cast here");
1453      Cast->setSubExpr(0);
1454      TheCall->setArg(NumArgs-1, CastArg);
1455    }
1456  }
1457
1458  return false;
1459}
1460
1461/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1462// This is declared to take (...), so we have to check everything.
1463ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1464  if (TheCall->getNumArgs() < 2)
1465    return ExprError(Diag(TheCall->getLocEnd(),
1466                          diag::err_typecheck_call_too_few_args_at_least)
1467      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1468      << TheCall->getSourceRange());
1469
1470  // Determine which of the following types of shufflevector we're checking:
1471  // 1) unary, vector mask: (lhs, mask)
1472  // 2) binary, vector mask: (lhs, rhs, mask)
1473  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1474  QualType resType = TheCall->getArg(0)->getType();
1475  unsigned numElements = 0;
1476
1477  if (!TheCall->getArg(0)->isTypeDependent() &&
1478      !TheCall->getArg(1)->isTypeDependent()) {
1479    QualType LHSType = TheCall->getArg(0)->getType();
1480    QualType RHSType = TheCall->getArg(1)->getType();
1481
1482    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1483      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1484        << SourceRange(TheCall->getArg(0)->getLocStart(),
1485                       TheCall->getArg(1)->getLocEnd());
1486      return ExprError();
1487    }
1488
1489    numElements = LHSType->getAs<VectorType>()->getNumElements();
1490    unsigned numResElements = TheCall->getNumArgs() - 2;
1491
1492    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1493    // with mask.  If so, verify that RHS is an integer vector type with the
1494    // same number of elts as lhs.
1495    if (TheCall->getNumArgs() == 2) {
1496      if (!RHSType->hasIntegerRepresentation() ||
1497          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1498        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1499          << SourceRange(TheCall->getArg(1)->getLocStart(),
1500                         TheCall->getArg(1)->getLocEnd());
1501      numResElements = numElements;
1502    }
1503    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1504      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1505        << SourceRange(TheCall->getArg(0)->getLocStart(),
1506                       TheCall->getArg(1)->getLocEnd());
1507      return ExprError();
1508    } else if (numElements != numResElements) {
1509      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1510      resType = Context.getVectorType(eltType, numResElements,
1511                                      VectorType::GenericVector);
1512    }
1513  }
1514
1515  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1516    if (TheCall->getArg(i)->isTypeDependent() ||
1517        TheCall->getArg(i)->isValueDependent())
1518      continue;
1519
1520    llvm::APSInt Result(32);
1521    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1522      return ExprError(Diag(TheCall->getLocStart(),
1523                  diag::err_shufflevector_nonconstant_argument)
1524                << TheCall->getArg(i)->getSourceRange());
1525
1526    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1527      return ExprError(Diag(TheCall->getLocStart(),
1528                  diag::err_shufflevector_argument_too_large)
1529               << TheCall->getArg(i)->getSourceRange());
1530  }
1531
1532  SmallVector<Expr*, 32> exprs;
1533
1534  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1535    exprs.push_back(TheCall->getArg(i));
1536    TheCall->setArg(i, 0);
1537  }
1538
1539  return Owned(new (Context) ShuffleVectorExpr(Context, exprs, resType,
1540                                            TheCall->getCallee()->getLocStart(),
1541                                            TheCall->getRParenLoc()));
1542}
1543
1544/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1545// This is declared to take (const void*, ...) and can take two
1546// optional constant int args.
1547bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1548  unsigned NumArgs = TheCall->getNumArgs();
1549
1550  if (NumArgs > 3)
1551    return Diag(TheCall->getLocEnd(),
1552             diag::err_typecheck_call_too_many_args_at_most)
1553             << 0 /*function call*/ << 3 << NumArgs
1554             << TheCall->getSourceRange();
1555
1556  // Argument 0 is checked for us and the remaining arguments must be
1557  // constant integers.
1558  for (unsigned i = 1; i != NumArgs; ++i) {
1559    Expr *Arg = TheCall->getArg(i);
1560
1561    // We can't check the value of a dependent argument.
1562    if (Arg->isTypeDependent() || Arg->isValueDependent())
1563      continue;
1564
1565    llvm::APSInt Result;
1566    if (SemaBuiltinConstantArg(TheCall, i, Result))
1567      return true;
1568
1569    // FIXME: gcc issues a warning and rewrites these to 0. These
1570    // seems especially odd for the third argument since the default
1571    // is 3.
1572    if (i == 1) {
1573      if (Result.getLimitedValue() > 1)
1574        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1575             << "0" << "1" << Arg->getSourceRange();
1576    } else {
1577      if (Result.getLimitedValue() > 3)
1578        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1579            << "0" << "3" << Arg->getSourceRange();
1580    }
1581  }
1582
1583  return false;
1584}
1585
1586/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1587/// TheCall is a constant expression.
1588bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1589                                  llvm::APSInt &Result) {
1590  Expr *Arg = TheCall->getArg(ArgNum);
1591  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1592  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1593
1594  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1595
1596  if (!Arg->isIntegerConstantExpr(Result, Context))
1597    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1598                << FDecl->getDeclName() <<  Arg->getSourceRange();
1599
1600  return false;
1601}
1602
1603/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1604/// int type). This simply type checks that type is one of the defined
1605/// constants (0-3).
1606// For compatibility check 0-3, llvm only handles 0 and 2.
1607bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1608  llvm::APSInt Result;
1609
1610  // We can't check the value of a dependent argument.
1611  if (TheCall->getArg(1)->isTypeDependent() ||
1612      TheCall->getArg(1)->isValueDependent())
1613    return false;
1614
1615  // Check constant-ness first.
1616  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1617    return true;
1618
1619  Expr *Arg = TheCall->getArg(1);
1620  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1621    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1622             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1623  }
1624
1625  return false;
1626}
1627
1628/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1629/// This checks that val is a constant 1.
1630bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1631  Expr *Arg = TheCall->getArg(1);
1632  llvm::APSInt Result;
1633
1634  // TODO: This is less than ideal. Overload this to take a value.
1635  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1636    return true;
1637
1638  if (Result != 1)
1639    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1640             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1641
1642  return false;
1643}
1644
1645// Determine if an expression is a string literal or constant string.
1646// If this function returns false on the arguments to a function expecting a
1647// format string, we will usually need to emit a warning.
1648// True string literals are then checked by CheckFormatString.
1649Sema::StringLiteralCheckType
1650Sema::checkFormatStringExpr(const Expr *E, ArrayRef<const Expr *> Args,
1651                            bool HasVAListArg,
1652                            unsigned format_idx, unsigned firstDataArg,
1653                            FormatStringType Type, VariadicCallType CallType,
1654                            bool inFunctionCall) {
1655 tryAgain:
1656  if (E->isTypeDependent() || E->isValueDependent())
1657    return SLCT_NotALiteral;
1658
1659  E = E->IgnoreParenCasts();
1660
1661  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1662    // Technically -Wformat-nonliteral does not warn about this case.
1663    // The behavior of printf and friends in this case is implementation
1664    // dependent.  Ideally if the format string cannot be null then
1665    // it should have a 'nonnull' attribute in the function prototype.
1666    return SLCT_CheckedLiteral;
1667
1668  switch (E->getStmtClass()) {
1669  case Stmt::BinaryConditionalOperatorClass:
1670  case Stmt::ConditionalOperatorClass: {
1671    // The expression is a literal if both sub-expressions were, and it was
1672    // completely checked only if both sub-expressions were checked.
1673    const AbstractConditionalOperator *C =
1674        cast<AbstractConditionalOperator>(E);
1675    StringLiteralCheckType Left =
1676        checkFormatStringExpr(C->getTrueExpr(), Args,
1677                              HasVAListArg, format_idx, firstDataArg,
1678                              Type, CallType, inFunctionCall);
1679    if (Left == SLCT_NotALiteral)
1680      return SLCT_NotALiteral;
1681    StringLiteralCheckType Right =
1682        checkFormatStringExpr(C->getFalseExpr(), Args,
1683                              HasVAListArg, format_idx, firstDataArg,
1684                              Type, CallType, inFunctionCall);
1685    return Left < Right ? Left : Right;
1686  }
1687
1688  case Stmt::ImplicitCastExprClass: {
1689    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1690    goto tryAgain;
1691  }
1692
1693  case Stmt::OpaqueValueExprClass:
1694    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1695      E = src;
1696      goto tryAgain;
1697    }
1698    return SLCT_NotALiteral;
1699
1700  case Stmt::PredefinedExprClass:
1701    // While __func__, etc., are technically not string literals, they
1702    // cannot contain format specifiers and thus are not a security
1703    // liability.
1704    return SLCT_UncheckedLiteral;
1705
1706  case Stmt::DeclRefExprClass: {
1707    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1708
1709    // As an exception, do not flag errors for variables binding to
1710    // const string literals.
1711    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1712      bool isConstant = false;
1713      QualType T = DR->getType();
1714
1715      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1716        isConstant = AT->getElementType().isConstant(Context);
1717      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1718        isConstant = T.isConstant(Context) &&
1719                     PT->getPointeeType().isConstant(Context);
1720      } else if (T->isObjCObjectPointerType()) {
1721        // In ObjC, there is usually no "const ObjectPointer" type,
1722        // so don't check if the pointee type is constant.
1723        isConstant = T.isConstant(Context);
1724      }
1725
1726      if (isConstant) {
1727        if (const Expr *Init = VD->getAnyInitializer()) {
1728          // Look through initializers like const char c[] = { "foo" }
1729          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
1730            if (InitList->isStringLiteralInit())
1731              Init = InitList->getInit(0)->IgnoreParenImpCasts();
1732          }
1733          return checkFormatStringExpr(Init, Args,
1734                                       HasVAListArg, format_idx,
1735                                       firstDataArg, Type, CallType,
1736                                       /*inFunctionCall*/false);
1737        }
1738      }
1739
1740      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1741      // special check to see if the format string is a function parameter
1742      // of the function calling the printf function.  If the function
1743      // has an attribute indicating it is a printf-like function, then we
1744      // should suppress warnings concerning non-literals being used in a call
1745      // to a vprintf function.  For example:
1746      //
1747      // void
1748      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1749      //      va_list ap;
1750      //      va_start(ap, fmt);
1751      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1752      //      ...
1753      //
1754      if (HasVAListArg) {
1755        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1756          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1757            int PVIndex = PV->getFunctionScopeIndex() + 1;
1758            for (specific_attr_iterator<FormatAttr>
1759                 i = ND->specific_attr_begin<FormatAttr>(),
1760                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1761              FormatAttr *PVFormat = *i;
1762              // adjust for implicit parameter
1763              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1764                if (MD->isInstance())
1765                  ++PVIndex;
1766              // We also check if the formats are compatible.
1767              // We can't pass a 'scanf' string to a 'printf' function.
1768              if (PVIndex == PVFormat->getFormatIdx() &&
1769                  Type == GetFormatStringType(PVFormat))
1770                return SLCT_UncheckedLiteral;
1771            }
1772          }
1773        }
1774      }
1775    }
1776
1777    return SLCT_NotALiteral;
1778  }
1779
1780  case Stmt::CallExprClass:
1781  case Stmt::CXXMemberCallExprClass: {
1782    const CallExpr *CE = cast<CallExpr>(E);
1783    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1784      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1785        unsigned ArgIndex = FA->getFormatIdx();
1786        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1787          if (MD->isInstance())
1788            --ArgIndex;
1789        const Expr *Arg = CE->getArg(ArgIndex - 1);
1790
1791        return checkFormatStringExpr(Arg, Args,
1792                                     HasVAListArg, format_idx, firstDataArg,
1793                                     Type, CallType, inFunctionCall);
1794      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
1795        unsigned BuiltinID = FD->getBuiltinID();
1796        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
1797            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
1798          const Expr *Arg = CE->getArg(0);
1799          return checkFormatStringExpr(Arg, Args,
1800                                       HasVAListArg, format_idx,
1801                                       firstDataArg, Type, CallType,
1802                                       inFunctionCall);
1803        }
1804      }
1805    }
1806
1807    return SLCT_NotALiteral;
1808  }
1809  case Stmt::ObjCStringLiteralClass:
1810  case Stmt::StringLiteralClass: {
1811    const StringLiteral *StrE = NULL;
1812
1813    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1814      StrE = ObjCFExpr->getString();
1815    else
1816      StrE = cast<StringLiteral>(E);
1817
1818    if (StrE) {
1819      CheckFormatString(StrE, E, Args, HasVAListArg, format_idx,
1820                        firstDataArg, Type, inFunctionCall, CallType);
1821      return SLCT_CheckedLiteral;
1822    }
1823
1824    return SLCT_NotALiteral;
1825  }
1826
1827  default:
1828    return SLCT_NotALiteral;
1829  }
1830}
1831
1832void
1833Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1834                            const Expr * const *ExprArgs,
1835                            SourceLocation CallSiteLoc) {
1836  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1837                                  e = NonNull->args_end();
1838       i != e; ++i) {
1839    const Expr *ArgExpr = ExprArgs[*i];
1840
1841    // As a special case, transparent unions initialized with zero are
1842    // considered null for the purposes of the nonnull attribute.
1843    if (const RecordType *UT = ArgExpr->getType()->getAsUnionType()) {
1844      if (UT->getDecl()->hasAttr<TransparentUnionAttr>())
1845        if (const CompoundLiteralExpr *CLE =
1846            dyn_cast<CompoundLiteralExpr>(ArgExpr))
1847          if (const InitListExpr *ILE =
1848              dyn_cast<InitListExpr>(CLE->getInitializer()))
1849            ArgExpr = ILE->getInit(0);
1850    }
1851
1852    bool Result;
1853    if (ArgExpr->EvaluateAsBooleanCondition(Result, Context) && !Result)
1854      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1855  }
1856}
1857
1858Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1859  return llvm::StringSwitch<FormatStringType>(Format->getType())
1860  .Case("scanf", FST_Scanf)
1861  .Cases("printf", "printf0", FST_Printf)
1862  .Cases("NSString", "CFString", FST_NSString)
1863  .Case("strftime", FST_Strftime)
1864  .Case("strfmon", FST_Strfmon)
1865  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1866  .Default(FST_Unknown);
1867}
1868
1869/// CheckFormatArguments - Check calls to printf and scanf (and similar
1870/// functions) for correct use of format strings.
1871/// Returns true if a format string has been fully checked.
1872bool Sema::CheckFormatArguments(const FormatAttr *Format,
1873                                ArrayRef<const Expr *> Args,
1874                                bool IsCXXMember,
1875                                VariadicCallType CallType,
1876                                SourceLocation Loc, SourceRange Range) {
1877  FormatStringInfo FSI;
1878  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
1879    return CheckFormatArguments(Args, FSI.HasVAListArg, FSI.FormatIdx,
1880                                FSI.FirstDataArg, GetFormatStringType(Format),
1881                                CallType, Loc, Range);
1882  return false;
1883}
1884
1885bool Sema::CheckFormatArguments(ArrayRef<const Expr *> Args,
1886                                bool HasVAListArg, unsigned format_idx,
1887                                unsigned firstDataArg, FormatStringType Type,
1888                                VariadicCallType CallType,
1889                                SourceLocation Loc, SourceRange Range) {
1890  // CHECK: printf/scanf-like function is called with no format string.
1891  if (format_idx >= Args.size()) {
1892    Diag(Loc, diag::warn_missing_format_string) << Range;
1893    return false;
1894  }
1895
1896  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1897
1898  // CHECK: format string is not a string literal.
1899  //
1900  // Dynamically generated format strings are difficult to
1901  // automatically vet at compile time.  Requiring that format strings
1902  // are string literals: (1) permits the checking of format strings by
1903  // the compiler and thereby (2) can practically remove the source of
1904  // many format string exploits.
1905
1906  // Format string can be either ObjC string (e.g. @"%d") or
1907  // C string (e.g. "%d")
1908  // ObjC string uses the same format specifiers as C string, so we can use
1909  // the same format string checking logic for both ObjC and C strings.
1910  StringLiteralCheckType CT =
1911      checkFormatStringExpr(OrigFormatExpr, Args, HasVAListArg,
1912                            format_idx, firstDataArg, Type, CallType);
1913  if (CT != SLCT_NotALiteral)
1914    // Literal format string found, check done!
1915    return CT == SLCT_CheckedLiteral;
1916
1917  // Strftime is particular as it always uses a single 'time' argument,
1918  // so it is safe to pass a non-literal string.
1919  if (Type == FST_Strftime)
1920    return false;
1921
1922  // Do not emit diag when the string param is a macro expansion and the
1923  // format is either NSString or CFString. This is a hack to prevent
1924  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1925  // which are usually used in place of NS and CF string literals.
1926  if (Type == FST_NSString &&
1927      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
1928    return false;
1929
1930  // If there are no arguments specified, warn with -Wformat-security, otherwise
1931  // warn only with -Wformat-nonliteral.
1932  if (Args.size() == format_idx+1)
1933    Diag(Args[format_idx]->getLocStart(),
1934         diag::warn_format_nonliteral_noargs)
1935      << OrigFormatExpr->getSourceRange();
1936  else
1937    Diag(Args[format_idx]->getLocStart(),
1938         diag::warn_format_nonliteral)
1939           << OrigFormatExpr->getSourceRange();
1940  return false;
1941}
1942
1943namespace {
1944class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1945protected:
1946  Sema &S;
1947  const StringLiteral *FExpr;
1948  const Expr *OrigFormatExpr;
1949  const unsigned FirstDataArg;
1950  const unsigned NumDataArgs;
1951  const char *Beg; // Start of format string.
1952  const bool HasVAListArg;
1953  ArrayRef<const Expr *> Args;
1954  unsigned FormatIdx;
1955  llvm::BitVector CoveredArgs;
1956  bool usesPositionalArgs;
1957  bool atFirstArg;
1958  bool inFunctionCall;
1959  Sema::VariadicCallType CallType;
1960public:
1961  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1962                     const Expr *origFormatExpr, unsigned firstDataArg,
1963                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
1964                     ArrayRef<const Expr *> Args,
1965                     unsigned formatIdx, bool inFunctionCall,
1966                     Sema::VariadicCallType callType)
1967    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1968      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
1969      Beg(beg), HasVAListArg(hasVAListArg),
1970      Args(Args), FormatIdx(formatIdx),
1971      usesPositionalArgs(false), atFirstArg(true),
1972      inFunctionCall(inFunctionCall), CallType(callType) {
1973        CoveredArgs.resize(numDataArgs);
1974        CoveredArgs.reset();
1975      }
1976
1977  void DoneProcessing();
1978
1979  void HandleIncompleteSpecifier(const char *startSpecifier,
1980                                 unsigned specifierLen);
1981
1982  void HandleInvalidLengthModifier(
1983      const analyze_format_string::FormatSpecifier &FS,
1984      const analyze_format_string::ConversionSpecifier &CS,
1985      const char *startSpecifier, unsigned specifierLen, unsigned DiagID);
1986
1987  void HandleNonStandardLengthModifier(
1988      const analyze_format_string::FormatSpecifier &FS,
1989      const char *startSpecifier, unsigned specifierLen);
1990
1991  void HandleNonStandardConversionSpecifier(
1992      const analyze_format_string::ConversionSpecifier &CS,
1993      const char *startSpecifier, unsigned specifierLen);
1994
1995  virtual void HandlePosition(const char *startPos, unsigned posLen);
1996
1997  virtual void HandleInvalidPosition(const char *startSpecifier,
1998                                     unsigned specifierLen,
1999                                     analyze_format_string::PositionContext p);
2000
2001  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
2002
2003  void HandleNullChar(const char *nullCharacter);
2004
2005  template <typename Range>
2006  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
2007                                   const Expr *ArgumentExpr,
2008                                   PartialDiagnostic PDiag,
2009                                   SourceLocation StringLoc,
2010                                   bool IsStringLocation, Range StringRange,
2011                                   ArrayRef<FixItHint> Fixit = None);
2012
2013protected:
2014  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
2015                                        const char *startSpec,
2016                                        unsigned specifierLen,
2017                                        const char *csStart, unsigned csLen);
2018
2019  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
2020                                         const char *startSpec,
2021                                         unsigned specifierLen);
2022
2023  SourceRange getFormatStringRange();
2024  CharSourceRange getSpecifierRange(const char *startSpecifier,
2025                                    unsigned specifierLen);
2026  SourceLocation getLocationOfByte(const char *x);
2027
2028  const Expr *getDataArg(unsigned i) const;
2029
2030  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
2031                    const analyze_format_string::ConversionSpecifier &CS,
2032                    const char *startSpecifier, unsigned specifierLen,
2033                    unsigned argIndex);
2034
2035  template <typename Range>
2036  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
2037                            bool IsStringLocation, Range StringRange,
2038                            ArrayRef<FixItHint> Fixit = None);
2039
2040  void CheckPositionalAndNonpositionalArgs(
2041      const analyze_format_string::FormatSpecifier *FS);
2042};
2043}
2044
2045SourceRange CheckFormatHandler::getFormatStringRange() {
2046  return OrigFormatExpr->getSourceRange();
2047}
2048
2049CharSourceRange CheckFormatHandler::
2050getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2051  SourceLocation Start = getLocationOfByte(startSpecifier);
2052  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2053
2054  // Advance the end SourceLocation by one due to half-open ranges.
2055  End = End.getLocWithOffset(1);
2056
2057  return CharSourceRange::getCharRange(Start, End);
2058}
2059
2060SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2061  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2062}
2063
2064void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2065                                                   unsigned specifierLen){
2066  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2067                       getLocationOfByte(startSpecifier),
2068                       /*IsStringLocation*/true,
2069                       getSpecifierRange(startSpecifier, specifierLen));
2070}
2071
2072void CheckFormatHandler::HandleInvalidLengthModifier(
2073    const analyze_format_string::FormatSpecifier &FS,
2074    const analyze_format_string::ConversionSpecifier &CS,
2075    const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
2076  using namespace analyze_format_string;
2077
2078  const LengthModifier &LM = FS.getLengthModifier();
2079  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2080
2081  // See if we know how to fix this length modifier.
2082  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2083  if (FixedLM) {
2084    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2085                         getLocationOfByte(LM.getStart()),
2086                         /*IsStringLocation*/true,
2087                         getSpecifierRange(startSpecifier, specifierLen));
2088
2089    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2090      << FixedLM->toString()
2091      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2092
2093  } else {
2094    FixItHint Hint;
2095    if (DiagID == diag::warn_format_nonsensical_length)
2096      Hint = FixItHint::CreateRemoval(LMRange);
2097
2098    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2099                         getLocationOfByte(LM.getStart()),
2100                         /*IsStringLocation*/true,
2101                         getSpecifierRange(startSpecifier, specifierLen),
2102                         Hint);
2103  }
2104}
2105
2106void CheckFormatHandler::HandleNonStandardLengthModifier(
2107    const analyze_format_string::FormatSpecifier &FS,
2108    const char *startSpecifier, unsigned specifierLen) {
2109  using namespace analyze_format_string;
2110
2111  const LengthModifier &LM = FS.getLengthModifier();
2112  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2113
2114  // See if we know how to fix this length modifier.
2115  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2116  if (FixedLM) {
2117    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2118                           << LM.toString() << 0,
2119                         getLocationOfByte(LM.getStart()),
2120                         /*IsStringLocation*/true,
2121                         getSpecifierRange(startSpecifier, specifierLen));
2122
2123    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2124      << FixedLM->toString()
2125      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2126
2127  } else {
2128    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2129                           << LM.toString() << 0,
2130                         getLocationOfByte(LM.getStart()),
2131                         /*IsStringLocation*/true,
2132                         getSpecifierRange(startSpecifier, specifierLen));
2133  }
2134}
2135
2136void CheckFormatHandler::HandleNonStandardConversionSpecifier(
2137    const analyze_format_string::ConversionSpecifier &CS,
2138    const char *startSpecifier, unsigned specifierLen) {
2139  using namespace analyze_format_string;
2140
2141  // See if we know how to fix this conversion specifier.
2142  Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
2143  if (FixedCS) {
2144    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2145                          << CS.toString() << /*conversion specifier*/1,
2146                         getLocationOfByte(CS.getStart()),
2147                         /*IsStringLocation*/true,
2148                         getSpecifierRange(startSpecifier, specifierLen));
2149
2150    CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
2151    S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
2152      << FixedCS->toString()
2153      << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
2154  } else {
2155    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2156                          << CS.toString() << /*conversion specifier*/1,
2157                         getLocationOfByte(CS.getStart()),
2158                         /*IsStringLocation*/true,
2159                         getSpecifierRange(startSpecifier, specifierLen));
2160  }
2161}
2162
2163void CheckFormatHandler::HandlePosition(const char *startPos,
2164                                        unsigned posLen) {
2165  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
2166                               getLocationOfByte(startPos),
2167                               /*IsStringLocation*/true,
2168                               getSpecifierRange(startPos, posLen));
2169}
2170
2171void
2172CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
2173                                     analyze_format_string::PositionContext p) {
2174  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
2175                         << (unsigned) p,
2176                       getLocationOfByte(startPos), /*IsStringLocation*/true,
2177                       getSpecifierRange(startPos, posLen));
2178}
2179
2180void CheckFormatHandler::HandleZeroPosition(const char *startPos,
2181                                            unsigned posLen) {
2182  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
2183                               getLocationOfByte(startPos),
2184                               /*IsStringLocation*/true,
2185                               getSpecifierRange(startPos, posLen));
2186}
2187
2188void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
2189  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
2190    // The presence of a null character is likely an error.
2191    EmitFormatDiagnostic(
2192      S.PDiag(diag::warn_printf_format_string_contains_null_char),
2193      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
2194      getFormatStringRange());
2195  }
2196}
2197
2198// Note that this may return NULL if there was an error parsing or building
2199// one of the argument expressions.
2200const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
2201  return Args[FirstDataArg + i];
2202}
2203
2204void CheckFormatHandler::DoneProcessing() {
2205    // Does the number of data arguments exceed the number of
2206    // format conversions in the format string?
2207  if (!HasVAListArg) {
2208      // Find any arguments that weren't covered.
2209    CoveredArgs.flip();
2210    signed notCoveredArg = CoveredArgs.find_first();
2211    if (notCoveredArg >= 0) {
2212      assert((unsigned)notCoveredArg < NumDataArgs);
2213      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
2214        SourceLocation Loc = E->getLocStart();
2215        if (!S.getSourceManager().isInSystemMacro(Loc)) {
2216          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
2217                               Loc, /*IsStringLocation*/false,
2218                               getFormatStringRange());
2219        }
2220      }
2221    }
2222  }
2223}
2224
2225bool
2226CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
2227                                                     SourceLocation Loc,
2228                                                     const char *startSpec,
2229                                                     unsigned specifierLen,
2230                                                     const char *csStart,
2231                                                     unsigned csLen) {
2232
2233  bool keepGoing = true;
2234  if (argIndex < NumDataArgs) {
2235    // Consider the argument coverered, even though the specifier doesn't
2236    // make sense.
2237    CoveredArgs.set(argIndex);
2238  }
2239  else {
2240    // If argIndex exceeds the number of data arguments we
2241    // don't issue a warning because that is just a cascade of warnings (and
2242    // they may have intended '%%' anyway). We don't want to continue processing
2243    // the format string after this point, however, as we will like just get
2244    // gibberish when trying to match arguments.
2245    keepGoing = false;
2246  }
2247
2248  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2249                         << StringRef(csStart, csLen),
2250                       Loc, /*IsStringLocation*/true,
2251                       getSpecifierRange(startSpec, specifierLen));
2252
2253  return keepGoing;
2254}
2255
2256void
2257CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2258                                                      const char *startSpec,
2259                                                      unsigned specifierLen) {
2260  EmitFormatDiagnostic(
2261    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2262    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2263}
2264
2265bool
2266CheckFormatHandler::CheckNumArgs(
2267  const analyze_format_string::FormatSpecifier &FS,
2268  const analyze_format_string::ConversionSpecifier &CS,
2269  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2270
2271  if (argIndex >= NumDataArgs) {
2272    PartialDiagnostic PDiag = FS.usesPositionalArg()
2273      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2274           << (argIndex+1) << NumDataArgs)
2275      : S.PDiag(diag::warn_printf_insufficient_data_args);
2276    EmitFormatDiagnostic(
2277      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2278      getSpecifierRange(startSpecifier, specifierLen));
2279    return false;
2280  }
2281  return true;
2282}
2283
2284template<typename Range>
2285void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2286                                              SourceLocation Loc,
2287                                              bool IsStringLocation,
2288                                              Range StringRange,
2289                                              ArrayRef<FixItHint> FixIt) {
2290  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2291                       Loc, IsStringLocation, StringRange, FixIt);
2292}
2293
2294/// \brief If the format string is not within the funcion call, emit a note
2295/// so that the function call and string are in diagnostic messages.
2296///
2297/// \param InFunctionCall if true, the format string is within the function
2298/// call and only one diagnostic message will be produced.  Otherwise, an
2299/// extra note will be emitted pointing to location of the format string.
2300///
2301/// \param ArgumentExpr the expression that is passed as the format string
2302/// argument in the function call.  Used for getting locations when two
2303/// diagnostics are emitted.
2304///
2305/// \param PDiag the callee should already have provided any strings for the
2306/// diagnostic message.  This function only adds locations and fixits
2307/// to diagnostics.
2308///
2309/// \param Loc primary location for diagnostic.  If two diagnostics are
2310/// required, one will be at Loc and a new SourceLocation will be created for
2311/// the other one.
2312///
2313/// \param IsStringLocation if true, Loc points to the format string should be
2314/// used for the note.  Otherwise, Loc points to the argument list and will
2315/// be used with PDiag.
2316///
2317/// \param StringRange some or all of the string to highlight.  This is
2318/// templated so it can accept either a CharSourceRange or a SourceRange.
2319///
2320/// \param FixIt optional fix it hint for the format string.
2321template<typename Range>
2322void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2323                                              const Expr *ArgumentExpr,
2324                                              PartialDiagnostic PDiag,
2325                                              SourceLocation Loc,
2326                                              bool IsStringLocation,
2327                                              Range StringRange,
2328                                              ArrayRef<FixItHint> FixIt) {
2329  if (InFunctionCall) {
2330    const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
2331    D << StringRange;
2332    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2333         I != E; ++I) {
2334      D << *I;
2335    }
2336  } else {
2337    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2338      << ArgumentExpr->getSourceRange();
2339
2340    const Sema::SemaDiagnosticBuilder &Note =
2341      S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2342             diag::note_format_string_defined);
2343
2344    Note << StringRange;
2345    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2346         I != E; ++I) {
2347      Note << *I;
2348    }
2349  }
2350}
2351
2352//===--- CHECK: Printf format string checking ------------------------------===//
2353
2354namespace {
2355class CheckPrintfHandler : public CheckFormatHandler {
2356  bool ObjCContext;
2357public:
2358  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2359                     const Expr *origFormatExpr, unsigned firstDataArg,
2360                     unsigned numDataArgs, bool isObjC,
2361                     const char *beg, bool hasVAListArg,
2362                     ArrayRef<const Expr *> Args,
2363                     unsigned formatIdx, bool inFunctionCall,
2364                     Sema::VariadicCallType CallType)
2365  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2366                       numDataArgs, beg, hasVAListArg, Args,
2367                       formatIdx, inFunctionCall, CallType), ObjCContext(isObjC)
2368  {}
2369
2370
2371  bool HandleInvalidPrintfConversionSpecifier(
2372                                      const analyze_printf::PrintfSpecifier &FS,
2373                                      const char *startSpecifier,
2374                                      unsigned specifierLen);
2375
2376  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2377                             const char *startSpecifier,
2378                             unsigned specifierLen);
2379  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2380                       const char *StartSpecifier,
2381                       unsigned SpecifierLen,
2382                       const Expr *E);
2383
2384  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2385                    const char *startSpecifier, unsigned specifierLen);
2386  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2387                           const analyze_printf::OptionalAmount &Amt,
2388                           unsigned type,
2389                           const char *startSpecifier, unsigned specifierLen);
2390  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2391                  const analyze_printf::OptionalFlag &flag,
2392                  const char *startSpecifier, unsigned specifierLen);
2393  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2394                         const analyze_printf::OptionalFlag &ignoredFlag,
2395                         const analyze_printf::OptionalFlag &flag,
2396                         const char *startSpecifier, unsigned specifierLen);
2397  bool checkForCStrMembers(const analyze_printf::ArgType &AT,
2398                           const Expr *E, const CharSourceRange &CSR);
2399
2400};
2401}
2402
2403bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2404                                      const analyze_printf::PrintfSpecifier &FS,
2405                                      const char *startSpecifier,
2406                                      unsigned specifierLen) {
2407  const analyze_printf::PrintfConversionSpecifier &CS =
2408    FS.getConversionSpecifier();
2409
2410  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2411                                          getLocationOfByte(CS.getStart()),
2412                                          startSpecifier, specifierLen,
2413                                          CS.getStart(), CS.getLength());
2414}
2415
2416bool CheckPrintfHandler::HandleAmount(
2417                               const analyze_format_string::OptionalAmount &Amt,
2418                               unsigned k, const char *startSpecifier,
2419                               unsigned specifierLen) {
2420
2421  if (Amt.hasDataArgument()) {
2422    if (!HasVAListArg) {
2423      unsigned argIndex = Amt.getArgIndex();
2424      if (argIndex >= NumDataArgs) {
2425        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2426                               << k,
2427                             getLocationOfByte(Amt.getStart()),
2428                             /*IsStringLocation*/true,
2429                             getSpecifierRange(startSpecifier, specifierLen));
2430        // Don't do any more checking.  We will just emit
2431        // spurious errors.
2432        return false;
2433      }
2434
2435      // Type check the data argument.  It should be an 'int'.
2436      // Although not in conformance with C99, we also allow the argument to be
2437      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2438      // doesn't emit a warning for that case.
2439      CoveredArgs.set(argIndex);
2440      const Expr *Arg = getDataArg(argIndex);
2441      if (!Arg)
2442        return false;
2443
2444      QualType T = Arg->getType();
2445
2446      const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
2447      assert(AT.isValid());
2448
2449      if (!AT.matchesType(S.Context, T)) {
2450        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2451                               << k << AT.getRepresentativeTypeName(S.Context)
2452                               << T << Arg->getSourceRange(),
2453                             getLocationOfByte(Amt.getStart()),
2454                             /*IsStringLocation*/true,
2455                             getSpecifierRange(startSpecifier, specifierLen));
2456        // Don't do any more checking.  We will just emit
2457        // spurious errors.
2458        return false;
2459      }
2460    }
2461  }
2462  return true;
2463}
2464
2465void CheckPrintfHandler::HandleInvalidAmount(
2466                                      const analyze_printf::PrintfSpecifier &FS,
2467                                      const analyze_printf::OptionalAmount &Amt,
2468                                      unsigned type,
2469                                      const char *startSpecifier,
2470                                      unsigned specifierLen) {
2471  const analyze_printf::PrintfConversionSpecifier &CS =
2472    FS.getConversionSpecifier();
2473
2474  FixItHint fixit =
2475    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2476      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2477                                 Amt.getConstantLength()))
2478      : FixItHint();
2479
2480  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2481                         << type << CS.toString(),
2482                       getLocationOfByte(Amt.getStart()),
2483                       /*IsStringLocation*/true,
2484                       getSpecifierRange(startSpecifier, specifierLen),
2485                       fixit);
2486}
2487
2488void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2489                                    const analyze_printf::OptionalFlag &flag,
2490                                    const char *startSpecifier,
2491                                    unsigned specifierLen) {
2492  // Warn about pointless flag with a fixit removal.
2493  const analyze_printf::PrintfConversionSpecifier &CS =
2494    FS.getConversionSpecifier();
2495  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2496                         << flag.toString() << CS.toString(),
2497                       getLocationOfByte(flag.getPosition()),
2498                       /*IsStringLocation*/true,
2499                       getSpecifierRange(startSpecifier, specifierLen),
2500                       FixItHint::CreateRemoval(
2501                         getSpecifierRange(flag.getPosition(), 1)));
2502}
2503
2504void CheckPrintfHandler::HandleIgnoredFlag(
2505                                const analyze_printf::PrintfSpecifier &FS,
2506                                const analyze_printf::OptionalFlag &ignoredFlag,
2507                                const analyze_printf::OptionalFlag &flag,
2508                                const char *startSpecifier,
2509                                unsigned specifierLen) {
2510  // Warn about ignored flag with a fixit removal.
2511  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2512                         << ignoredFlag.toString() << flag.toString(),
2513                       getLocationOfByte(ignoredFlag.getPosition()),
2514                       /*IsStringLocation*/true,
2515                       getSpecifierRange(startSpecifier, specifierLen),
2516                       FixItHint::CreateRemoval(
2517                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2518}
2519
2520// Determines if the specified is a C++ class or struct containing
2521// a member with the specified name and kind (e.g. a CXXMethodDecl named
2522// "c_str()").
2523template<typename MemberKind>
2524static llvm::SmallPtrSet<MemberKind*, 1>
2525CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
2526  const RecordType *RT = Ty->getAs<RecordType>();
2527  llvm::SmallPtrSet<MemberKind*, 1> Results;
2528
2529  if (!RT)
2530    return Results;
2531  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
2532  if (!RD)
2533    return Results;
2534
2535  LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
2536                 Sema::LookupMemberName);
2537
2538  // We just need to include all members of the right kind turned up by the
2539  // filter, at this point.
2540  if (S.LookupQualifiedName(R, RT->getDecl()))
2541    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
2542      NamedDecl *decl = (*I)->getUnderlyingDecl();
2543      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
2544        Results.insert(FK);
2545    }
2546  return Results;
2547}
2548
2549// Check if a (w)string was passed when a (w)char* was needed, and offer a
2550// better diagnostic if so. AT is assumed to be valid.
2551// Returns true when a c_str() conversion method is found.
2552bool CheckPrintfHandler::checkForCStrMembers(
2553    const analyze_printf::ArgType &AT, const Expr *E,
2554    const CharSourceRange &CSR) {
2555  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
2556
2557  MethodSet Results =
2558      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
2559
2560  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
2561       MI != ME; ++MI) {
2562    const CXXMethodDecl *Method = *MI;
2563    if (Method->getNumParams() == 0 &&
2564          AT.matchesType(S.Context, Method->getResultType())) {
2565      // FIXME: Suggest parens if the expression needs them.
2566      SourceLocation EndLoc =
2567          S.getPreprocessor().getLocForEndOfToken(E->getLocEnd());
2568      S.Diag(E->getLocStart(), diag::note_printf_c_str)
2569          << "c_str()"
2570          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
2571      return true;
2572    }
2573  }
2574
2575  return false;
2576}
2577
2578bool
2579CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2580                                            &FS,
2581                                          const char *startSpecifier,
2582                                          unsigned specifierLen) {
2583
2584  using namespace analyze_format_string;
2585  using namespace analyze_printf;
2586  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2587
2588  if (FS.consumesDataArgument()) {
2589    if (atFirstArg) {
2590        atFirstArg = false;
2591        usesPositionalArgs = FS.usesPositionalArg();
2592    }
2593    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2594      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2595                                        startSpecifier, specifierLen);
2596      return false;
2597    }
2598  }
2599
2600  // First check if the field width, precision, and conversion specifier
2601  // have matching data arguments.
2602  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2603                    startSpecifier, specifierLen)) {
2604    return false;
2605  }
2606
2607  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2608                    startSpecifier, specifierLen)) {
2609    return false;
2610  }
2611
2612  if (!CS.consumesDataArgument()) {
2613    // FIXME: Technically specifying a precision or field width here
2614    // makes no sense.  Worth issuing a warning at some point.
2615    return true;
2616  }
2617
2618  // Consume the argument.
2619  unsigned argIndex = FS.getArgIndex();
2620  if (argIndex < NumDataArgs) {
2621    // The check to see if the argIndex is valid will come later.
2622    // We set the bit here because we may exit early from this
2623    // function if we encounter some other error.
2624    CoveredArgs.set(argIndex);
2625  }
2626
2627  // FreeBSD extensions
2628  if (CS.getKind() == ConversionSpecifier::FreeBSDbArg ||
2629      CS.getKind() == ConversionSpecifier::FreeBSDDArg) {
2630    // claim the second argument
2631    CoveredArgs.set(argIndex + 1);
2632
2633    // Now type check the data expression that matches the
2634    // format specifier.
2635    const Expr *Ex = getDataArg(argIndex);
2636    const analyze_printf::ArgType &AT =
2637      (CS.getKind() == ConversionSpecifier::FreeBSDbArg) ?
2638        ArgType(S.Context.IntTy) : ArgType::CStrTy;
2639    if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType()))
2640      S.Diag(getLocationOfByte(CS.getStart()),
2641             diag::warn_printf_conversion_argument_type_mismatch)
2642        << AT.getRepresentativeType(S.Context) << Ex->getType()
2643        << getSpecifierRange(startSpecifier, specifierLen)
2644        << Ex->getSourceRange();
2645
2646    // Now type check the data expression that matches the
2647    // format specifier.
2648    Ex = getDataArg(argIndex + 1);
2649    const analyze_printf::ArgType &AT2 = ArgType::CStrTy;
2650    if (AT2.isValid() && !AT2.matchesType(S.Context, Ex->getType()))
2651      S.Diag(getLocationOfByte(CS.getStart()),
2652             diag::warn_printf_conversion_argument_type_mismatch)
2653        << AT2.getRepresentativeType(S.Context) << Ex->getType()
2654        << getSpecifierRange(startSpecifier, specifierLen)
2655        << Ex->getSourceRange();
2656
2657     return true;
2658  }
2659  // END OF FREEBSD EXTENSIONS
2660
2661  // Check for using an Objective-C specific conversion specifier
2662  // in a non-ObjC literal.
2663  if (!ObjCContext && CS.isObjCArg()) {
2664    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2665                                                  specifierLen);
2666  }
2667
2668  // Check for invalid use of field width
2669  if (!FS.hasValidFieldWidth()) {
2670    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2671        startSpecifier, specifierLen);
2672  }
2673
2674  // Check for invalid use of precision
2675  if (!FS.hasValidPrecision()) {
2676    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2677        startSpecifier, specifierLen);
2678  }
2679
2680  // Check each flag does not conflict with any other component.
2681  if (!FS.hasValidThousandsGroupingPrefix())
2682    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2683  if (!FS.hasValidLeadingZeros())
2684    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2685  if (!FS.hasValidPlusPrefix())
2686    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2687  if (!FS.hasValidSpacePrefix())
2688    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2689  if (!FS.hasValidAlternativeForm())
2690    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2691  if (!FS.hasValidLeftJustified())
2692    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2693
2694  // Check that flags are not ignored by another flag
2695  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2696    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2697        startSpecifier, specifierLen);
2698  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2699    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2700            startSpecifier, specifierLen);
2701
2702  // Check the length modifier is valid with the given conversion specifier.
2703  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
2704    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2705                                diag::warn_format_nonsensical_length);
2706  else if (!FS.hasStandardLengthModifier())
2707    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
2708  else if (!FS.hasStandardLengthConversionCombination())
2709    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2710                                diag::warn_format_non_standard_conversion_spec);
2711
2712  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2713    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2714
2715  // The remaining checks depend on the data arguments.
2716  if (HasVAListArg)
2717    return true;
2718
2719  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2720    return false;
2721
2722  const Expr *Arg = getDataArg(argIndex);
2723  if (!Arg)
2724    return true;
2725
2726  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
2727}
2728
2729static bool requiresParensToAddCast(const Expr *E) {
2730  // FIXME: We should have a general way to reason about operator
2731  // precedence and whether parens are actually needed here.
2732  // Take care of a few common cases where they aren't.
2733  const Expr *Inside = E->IgnoreImpCasts();
2734  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
2735    Inside = POE->getSyntacticForm()->IgnoreImpCasts();
2736
2737  switch (Inside->getStmtClass()) {
2738  case Stmt::ArraySubscriptExprClass:
2739  case Stmt::CallExprClass:
2740  case Stmt::CharacterLiteralClass:
2741  case Stmt::CXXBoolLiteralExprClass:
2742  case Stmt::DeclRefExprClass:
2743  case Stmt::FloatingLiteralClass:
2744  case Stmt::IntegerLiteralClass:
2745  case Stmt::MemberExprClass:
2746  case Stmt::ObjCArrayLiteralClass:
2747  case Stmt::ObjCBoolLiteralExprClass:
2748  case Stmt::ObjCBoxedExprClass:
2749  case Stmt::ObjCDictionaryLiteralClass:
2750  case Stmt::ObjCEncodeExprClass:
2751  case Stmt::ObjCIvarRefExprClass:
2752  case Stmt::ObjCMessageExprClass:
2753  case Stmt::ObjCPropertyRefExprClass:
2754  case Stmt::ObjCStringLiteralClass:
2755  case Stmt::ObjCSubscriptRefExprClass:
2756  case Stmt::ParenExprClass:
2757  case Stmt::StringLiteralClass:
2758  case Stmt::UnaryOperatorClass:
2759    return false;
2760  default:
2761    return true;
2762  }
2763}
2764
2765bool
2766CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2767                                    const char *StartSpecifier,
2768                                    unsigned SpecifierLen,
2769                                    const Expr *E) {
2770  using namespace analyze_format_string;
2771  using namespace analyze_printf;
2772  // Now type check the data expression that matches the
2773  // format specifier.
2774  const analyze_printf::ArgType &AT = FS.getArgType(S.Context,
2775                                                    ObjCContext);
2776  if (!AT.isValid())
2777    return true;
2778
2779  QualType ExprTy = E->getType();
2780  while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
2781    ExprTy = TET->getUnderlyingExpr()->getType();
2782  }
2783
2784  if (AT.matchesType(S.Context, ExprTy))
2785    return true;
2786
2787  // Look through argument promotions for our error message's reported type.
2788  // This includes the integral and floating promotions, but excludes array
2789  // and function pointer decay; seeing that an argument intended to be a
2790  // string has type 'char [6]' is probably more confusing than 'char *'.
2791  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2792    if (ICE->getCastKind() == CK_IntegralCast ||
2793        ICE->getCastKind() == CK_FloatingCast) {
2794      E = ICE->getSubExpr();
2795      ExprTy = E->getType();
2796
2797      // Check if we didn't match because of an implicit cast from a 'char'
2798      // or 'short' to an 'int'.  This is done because printf is a varargs
2799      // function.
2800      if (ICE->getType() == S.Context.IntTy ||
2801          ICE->getType() == S.Context.UnsignedIntTy) {
2802        // All further checking is done on the subexpression.
2803        if (AT.matchesType(S.Context, ExprTy))
2804          return true;
2805      }
2806    }
2807  } else if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) {
2808    // Special case for 'a', which has type 'int' in C.
2809    // Note, however, that we do /not/ want to treat multibyte constants like
2810    // 'MooV' as characters! This form is deprecated but still exists.
2811    if (ExprTy == S.Context.IntTy)
2812      if (llvm::isUIntN(S.Context.getCharWidth(), CL->getValue()))
2813        ExprTy = S.Context.CharTy;
2814  }
2815
2816  // %C in an Objective-C context prints a unichar, not a wchar_t.
2817  // If the argument is an integer of some kind, believe the %C and suggest
2818  // a cast instead of changing the conversion specifier.
2819  QualType IntendedTy = ExprTy;
2820  if (ObjCContext &&
2821      FS.getConversionSpecifier().getKind() == ConversionSpecifier::CArg) {
2822    if (ExprTy->isIntegralOrUnscopedEnumerationType() &&
2823        !ExprTy->isCharType()) {
2824      // 'unichar' is defined as a typedef of unsigned short, but we should
2825      // prefer using the typedef if it is visible.
2826      IntendedTy = S.Context.UnsignedShortTy;
2827
2828      LookupResult Result(S, &S.Context.Idents.get("unichar"), E->getLocStart(),
2829                          Sema::LookupOrdinaryName);
2830      if (S.LookupName(Result, S.getCurScope())) {
2831        NamedDecl *ND = Result.getFoundDecl();
2832        if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(ND))
2833          if (TD->getUnderlyingType() == IntendedTy)
2834            IntendedTy = S.Context.getTypedefType(TD);
2835      }
2836    }
2837  }
2838
2839  // Special-case some of Darwin's platform-independence types by suggesting
2840  // casts to primitive types that are known to be large enough.
2841  bool ShouldNotPrintDirectly = false;
2842  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
2843    // Use a 'while' to peel off layers of typedefs.
2844    QualType TyTy = IntendedTy;
2845    while (const TypedefType *UserTy = TyTy->getAs<TypedefType>()) {
2846      StringRef Name = UserTy->getDecl()->getName();
2847      QualType CastTy = llvm::StringSwitch<QualType>(Name)
2848        .Case("NSInteger", S.Context.LongTy)
2849        .Case("NSUInteger", S.Context.UnsignedLongTy)
2850        .Case("SInt32", S.Context.IntTy)
2851        .Case("UInt32", S.Context.UnsignedIntTy)
2852        .Default(QualType());
2853
2854      if (!CastTy.isNull()) {
2855        ShouldNotPrintDirectly = true;
2856        IntendedTy = CastTy;
2857        break;
2858      }
2859      TyTy = UserTy->desugar();
2860    }
2861  }
2862
2863  // We may be able to offer a FixItHint if it is a supported type.
2864  PrintfSpecifier fixedFS = FS;
2865  bool success = fixedFS.fixType(IntendedTy, S.getLangOpts(),
2866                                 S.Context, ObjCContext);
2867
2868  if (success) {
2869    // Get the fix string from the fixed format specifier
2870    SmallString<16> buf;
2871    llvm::raw_svector_ostream os(buf);
2872    fixedFS.toString(os);
2873
2874    CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
2875
2876    if (IntendedTy == ExprTy) {
2877      // In this case, the specifier is wrong and should be changed to match
2878      // the argument.
2879      EmitFormatDiagnostic(
2880        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2881          << AT.getRepresentativeTypeName(S.Context) << IntendedTy
2882          << E->getSourceRange(),
2883        E->getLocStart(),
2884        /*IsStringLocation*/false,
2885        SpecRange,
2886        FixItHint::CreateReplacement(SpecRange, os.str()));
2887
2888    } else {
2889      // The canonical type for formatting this value is different from the
2890      // actual type of the expression. (This occurs, for example, with Darwin's
2891      // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
2892      // should be printed as 'long' for 64-bit compatibility.)
2893      // Rather than emitting a normal format/argument mismatch, we want to
2894      // add a cast to the recommended type (and correct the format string
2895      // if necessary).
2896      SmallString<16> CastBuf;
2897      llvm::raw_svector_ostream CastFix(CastBuf);
2898      CastFix << "(";
2899      IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
2900      CastFix << ")";
2901
2902      SmallVector<FixItHint,4> Hints;
2903      if (!AT.matchesType(S.Context, IntendedTy))
2904        Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
2905
2906      if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
2907        // If there's already a cast present, just replace it.
2908        SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
2909        Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
2910
2911      } else if (!requiresParensToAddCast(E)) {
2912        // If the expression has high enough precedence,
2913        // just write the C-style cast.
2914        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2915                                                   CastFix.str()));
2916      } else {
2917        // Otherwise, add parens around the expression as well as the cast.
2918        CastFix << "(";
2919        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2920                                                   CastFix.str()));
2921
2922        SourceLocation After = S.PP.getLocForEndOfToken(E->getLocEnd());
2923        Hints.push_back(FixItHint::CreateInsertion(After, ")"));
2924      }
2925
2926      if (ShouldNotPrintDirectly) {
2927        // The expression has a type that should not be printed directly.
2928        // We extract the name from the typedef because we don't want to show
2929        // the underlying type in the diagnostic.
2930        StringRef Name = cast<TypedefType>(ExprTy)->getDecl()->getName();
2931
2932        EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
2933                               << Name << IntendedTy
2934                               << E->getSourceRange(),
2935                             E->getLocStart(), /*IsStringLocation=*/false,
2936                             SpecRange, Hints);
2937      } else {
2938        // In this case, the expression could be printed using a different
2939        // specifier, but we've decided that the specifier is probably correct
2940        // and we should cast instead. Just use the normal warning message.
2941        EmitFormatDiagnostic(
2942          S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2943            << AT.getRepresentativeTypeName(S.Context) << ExprTy
2944            << E->getSourceRange(),
2945          E->getLocStart(), /*IsStringLocation*/false,
2946          SpecRange, Hints);
2947      }
2948    }
2949  } else {
2950    const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
2951                                                   SpecifierLen);
2952    // Since the warning for passing non-POD types to variadic functions
2953    // was deferred until now, we emit a warning for non-POD
2954    // arguments here.
2955    if (S.isValidVarArgType(ExprTy) == Sema::VAK_Invalid) {
2956      unsigned DiagKind;
2957      if (ExprTy->isObjCObjectType())
2958        DiagKind = diag::err_cannot_pass_objc_interface_to_vararg_format;
2959      else
2960        DiagKind = diag::warn_non_pod_vararg_with_format_string;
2961
2962      EmitFormatDiagnostic(
2963        S.PDiag(DiagKind)
2964          << S.getLangOpts().CPlusPlus11
2965          << ExprTy
2966          << CallType
2967          << AT.getRepresentativeTypeName(S.Context)
2968          << CSR
2969          << E->getSourceRange(),
2970        E->getLocStart(), /*IsStringLocation*/false, CSR);
2971
2972      checkForCStrMembers(AT, E, CSR);
2973    } else
2974      EmitFormatDiagnostic(
2975        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2976          << AT.getRepresentativeTypeName(S.Context) << ExprTy
2977          << CSR
2978          << E->getSourceRange(),
2979        E->getLocStart(), /*IsStringLocation*/false, CSR);
2980  }
2981
2982  return true;
2983}
2984
2985//===--- CHECK: Scanf format string checking ------------------------------===//
2986
2987namespace {
2988class CheckScanfHandler : public CheckFormatHandler {
2989public:
2990  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2991                    const Expr *origFormatExpr, unsigned firstDataArg,
2992                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
2993                    ArrayRef<const Expr *> Args,
2994                    unsigned formatIdx, bool inFunctionCall,
2995                    Sema::VariadicCallType CallType)
2996  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2997                       numDataArgs, beg, hasVAListArg,
2998                       Args, formatIdx, inFunctionCall, CallType)
2999  {}
3000
3001  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
3002                            const char *startSpecifier,
3003                            unsigned specifierLen);
3004
3005  bool HandleInvalidScanfConversionSpecifier(
3006          const analyze_scanf::ScanfSpecifier &FS,
3007          const char *startSpecifier,
3008          unsigned specifierLen);
3009
3010  void HandleIncompleteScanList(const char *start, const char *end);
3011};
3012}
3013
3014void CheckScanfHandler::HandleIncompleteScanList(const char *start,
3015                                                 const char *end) {
3016  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
3017                       getLocationOfByte(end), /*IsStringLocation*/true,
3018                       getSpecifierRange(start, end - start));
3019}
3020
3021bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
3022                                        const analyze_scanf::ScanfSpecifier &FS,
3023                                        const char *startSpecifier,
3024                                        unsigned specifierLen) {
3025
3026  const analyze_scanf::ScanfConversionSpecifier &CS =
3027    FS.getConversionSpecifier();
3028
3029  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
3030                                          getLocationOfByte(CS.getStart()),
3031                                          startSpecifier, specifierLen,
3032                                          CS.getStart(), CS.getLength());
3033}
3034
3035bool CheckScanfHandler::HandleScanfSpecifier(
3036                                       const analyze_scanf::ScanfSpecifier &FS,
3037                                       const char *startSpecifier,
3038                                       unsigned specifierLen) {
3039
3040  using namespace analyze_scanf;
3041  using namespace analyze_format_string;
3042
3043  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
3044
3045  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
3046  // be used to decide if we are using positional arguments consistently.
3047  if (FS.consumesDataArgument()) {
3048    if (atFirstArg) {
3049      atFirstArg = false;
3050      usesPositionalArgs = FS.usesPositionalArg();
3051    }
3052    else if (usesPositionalArgs != FS.usesPositionalArg()) {
3053      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
3054                                        startSpecifier, specifierLen);
3055      return false;
3056    }
3057  }
3058
3059  // Check if the field with is non-zero.
3060  const OptionalAmount &Amt = FS.getFieldWidth();
3061  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
3062    if (Amt.getConstantAmount() == 0) {
3063      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
3064                                                   Amt.getConstantLength());
3065      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
3066                           getLocationOfByte(Amt.getStart()),
3067                           /*IsStringLocation*/true, R,
3068                           FixItHint::CreateRemoval(R));
3069    }
3070  }
3071
3072  if (!FS.consumesDataArgument()) {
3073    // FIXME: Technically specifying a precision or field width here
3074    // makes no sense.  Worth issuing a warning at some point.
3075    return true;
3076  }
3077
3078  // Consume the argument.
3079  unsigned argIndex = FS.getArgIndex();
3080  if (argIndex < NumDataArgs) {
3081      // The check to see if the argIndex is valid will come later.
3082      // We set the bit here because we may exit early from this
3083      // function if we encounter some other error.
3084    CoveredArgs.set(argIndex);
3085  }
3086
3087  // Check the length modifier is valid with the given conversion specifier.
3088  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
3089    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3090                                diag::warn_format_nonsensical_length);
3091  else if (!FS.hasStandardLengthModifier())
3092    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
3093  else if (!FS.hasStandardLengthConversionCombination())
3094    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3095                                diag::warn_format_non_standard_conversion_spec);
3096
3097  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
3098    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
3099
3100  // The remaining checks depend on the data arguments.
3101  if (HasVAListArg)
3102    return true;
3103
3104  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
3105    return false;
3106
3107  // Check that the argument type matches the format specifier.
3108  const Expr *Ex = getDataArg(argIndex);
3109  if (!Ex)
3110    return true;
3111
3112  const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
3113  if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType())) {
3114    ScanfSpecifier fixedFS = FS;
3115    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
3116                                   S.Context);
3117
3118    if (success) {
3119      // Get the fix string from the fixed format specifier.
3120      SmallString<128> buf;
3121      llvm::raw_svector_ostream os(buf);
3122      fixedFS.toString(os);
3123
3124      EmitFormatDiagnostic(
3125        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3126          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3127          << Ex->getSourceRange(),
3128        Ex->getLocStart(),
3129        /*IsStringLocation*/false,
3130        getSpecifierRange(startSpecifier, specifierLen),
3131        FixItHint::CreateReplacement(
3132          getSpecifierRange(startSpecifier, specifierLen),
3133          os.str()));
3134    } else {
3135      EmitFormatDiagnostic(
3136        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3137          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3138          << Ex->getSourceRange(),
3139        Ex->getLocStart(),
3140        /*IsStringLocation*/false,
3141        getSpecifierRange(startSpecifier, specifierLen));
3142    }
3143  }
3144
3145  return true;
3146}
3147
3148void Sema::CheckFormatString(const StringLiteral *FExpr,
3149                             const Expr *OrigFormatExpr,
3150                             ArrayRef<const Expr *> Args,
3151                             bool HasVAListArg, unsigned format_idx,
3152                             unsigned firstDataArg, FormatStringType Type,
3153                             bool inFunctionCall, VariadicCallType CallType) {
3154
3155  // CHECK: is the format string a wide literal?
3156  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
3157    CheckFormatHandler::EmitFormatDiagnostic(
3158      *this, inFunctionCall, Args[format_idx],
3159      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
3160      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3161    return;
3162  }
3163
3164  // Str - The format string.  NOTE: this is NOT null-terminated!
3165  StringRef StrRef = FExpr->getString();
3166  const char *Str = StrRef.data();
3167  unsigned StrLen = StrRef.size();
3168  const unsigned numDataArgs = Args.size() - firstDataArg;
3169
3170  // CHECK: empty format string?
3171  if (StrLen == 0 && numDataArgs > 0) {
3172    CheckFormatHandler::EmitFormatDiagnostic(
3173      *this, inFunctionCall, Args[format_idx],
3174      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
3175      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3176    return;
3177  }
3178
3179  if (Type == FST_Printf || Type == FST_NSString) {
3180    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
3181                         numDataArgs, (Type == FST_NSString),
3182                         Str, HasVAListArg, Args, format_idx,
3183                         inFunctionCall, CallType);
3184
3185    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
3186                                                  getLangOpts(),
3187                                                  Context.getTargetInfo()))
3188      H.DoneProcessing();
3189  } else if (Type == FST_Scanf) {
3190    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
3191                        Str, HasVAListArg, Args, format_idx,
3192                        inFunctionCall, CallType);
3193
3194    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
3195                                                 getLangOpts(),
3196                                                 Context.getTargetInfo()))
3197      H.DoneProcessing();
3198  } // TODO: handle other formats
3199}
3200
3201//===--- CHECK: Standard memory functions ---------------------------------===//
3202
3203/// \brief Determine whether the given type is a dynamic class type (e.g.,
3204/// whether it has a vtable).
3205static bool isDynamicClassType(QualType T) {
3206  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
3207    if (CXXRecordDecl *Definition = Record->getDefinition())
3208      if (Definition->isDynamicClass())
3209        return true;
3210
3211  return false;
3212}
3213
3214/// \brief If E is a sizeof expression, returns its argument expression,
3215/// otherwise returns NULL.
3216static const Expr *getSizeOfExprArg(const Expr* E) {
3217  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3218      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3219    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
3220      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
3221
3222  return 0;
3223}
3224
3225/// \brief If E is a sizeof expression, returns its argument type.
3226static QualType getSizeOfArgType(const Expr* E) {
3227  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3228      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3229    if (SizeOf->getKind() == clang::UETT_SizeOf)
3230      return SizeOf->getTypeOfArgument();
3231
3232  return QualType();
3233}
3234
3235/// \brief Check for dangerous or invalid arguments to memset().
3236///
3237/// This issues warnings on known problematic, dangerous or unspecified
3238/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
3239/// function calls.
3240///
3241/// \param Call The call expression to diagnose.
3242void Sema::CheckMemaccessArguments(const CallExpr *Call,
3243                                   unsigned BId,
3244                                   IdentifierInfo *FnName) {
3245  assert(BId != 0);
3246
3247  // It is possible to have a non-standard definition of memset.  Validate
3248  // we have enough arguments, and if not, abort further checking.
3249  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
3250  if (Call->getNumArgs() < ExpectedNumArgs)
3251    return;
3252
3253  unsigned LastArg = (BId == Builtin::BImemset ||
3254                      BId == Builtin::BIstrndup ? 1 : 2);
3255  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
3256  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
3257
3258  // We have special checking when the length is a sizeof expression.
3259  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
3260  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
3261  llvm::FoldingSetNodeID SizeOfArgID;
3262
3263  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
3264    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
3265    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
3266
3267    QualType DestTy = Dest->getType();
3268    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
3269      QualType PointeeTy = DestPtrTy->getPointeeType();
3270
3271      // Never warn about void type pointers. This can be used to suppress
3272      // false positives.
3273      if (PointeeTy->isVoidType())
3274        continue;
3275
3276      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
3277      // actually comparing the expressions for equality. Because computing the
3278      // expression IDs can be expensive, we only do this if the diagnostic is
3279      // enabled.
3280      if (SizeOfArg &&
3281          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
3282                                   SizeOfArg->getExprLoc())) {
3283        // We only compute IDs for expressions if the warning is enabled, and
3284        // cache the sizeof arg's ID.
3285        if (SizeOfArgID == llvm::FoldingSetNodeID())
3286          SizeOfArg->Profile(SizeOfArgID, Context, true);
3287        llvm::FoldingSetNodeID DestID;
3288        Dest->Profile(DestID, Context, true);
3289        if (DestID == SizeOfArgID) {
3290          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
3291          //       over sizeof(src) as well.
3292          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
3293          StringRef ReadableName = FnName->getName();
3294
3295          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
3296            if (UnaryOp->getOpcode() == UO_AddrOf)
3297              ActionIdx = 1; // If its an address-of operator, just remove it.
3298          if (!PointeeTy->isIncompleteType() &&
3299              (Context.getTypeSize(PointeeTy) == Context.getCharWidth()))
3300            ActionIdx = 2; // If the pointee's size is sizeof(char),
3301                           // suggest an explicit length.
3302
3303          // If the function is defined as a builtin macro, do not show macro
3304          // expansion.
3305          SourceLocation SL = SizeOfArg->getExprLoc();
3306          SourceRange DSR = Dest->getSourceRange();
3307          SourceRange SSR = SizeOfArg->getSourceRange();
3308          SourceManager &SM  = PP.getSourceManager();
3309
3310          if (SM.isMacroArgExpansion(SL)) {
3311            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
3312            SL = SM.getSpellingLoc(SL);
3313            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
3314                             SM.getSpellingLoc(DSR.getEnd()));
3315            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
3316                             SM.getSpellingLoc(SSR.getEnd()));
3317          }
3318
3319          DiagRuntimeBehavior(SL, SizeOfArg,
3320                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
3321                                << ReadableName
3322                                << PointeeTy
3323                                << DestTy
3324                                << DSR
3325                                << SSR);
3326          DiagRuntimeBehavior(SL, SizeOfArg,
3327                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
3328                                << ActionIdx
3329                                << SSR);
3330
3331          break;
3332        }
3333      }
3334
3335      // Also check for cases where the sizeof argument is the exact same
3336      // type as the memory argument, and where it points to a user-defined
3337      // record type.
3338      if (SizeOfArgTy != QualType()) {
3339        if (PointeeTy->isRecordType() &&
3340            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
3341          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
3342                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
3343                                << FnName << SizeOfArgTy << ArgIdx
3344                                << PointeeTy << Dest->getSourceRange()
3345                                << LenExpr->getSourceRange());
3346          break;
3347        }
3348      }
3349
3350      // Always complain about dynamic classes.
3351      if (isDynamicClassType(PointeeTy)) {
3352
3353        unsigned OperationType = 0;
3354        // "overwritten" if we're warning about the destination for any call
3355        // but memcmp; otherwise a verb appropriate to the call.
3356        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
3357          if (BId == Builtin::BImemcpy)
3358            OperationType = 1;
3359          else if(BId == Builtin::BImemmove)
3360            OperationType = 2;
3361          else if (BId == Builtin::BImemcmp)
3362            OperationType = 3;
3363        }
3364
3365        DiagRuntimeBehavior(
3366          Dest->getExprLoc(), Dest,
3367          PDiag(diag::warn_dyn_class_memaccess)
3368            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
3369            << FnName << PointeeTy
3370            << OperationType
3371            << Call->getCallee()->getSourceRange());
3372      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
3373               BId != Builtin::BImemset)
3374        DiagRuntimeBehavior(
3375          Dest->getExprLoc(), Dest,
3376          PDiag(diag::warn_arc_object_memaccess)
3377            << ArgIdx << FnName << PointeeTy
3378            << Call->getCallee()->getSourceRange());
3379      else
3380        continue;
3381
3382      DiagRuntimeBehavior(
3383        Dest->getExprLoc(), Dest,
3384        PDiag(diag::note_bad_memaccess_silence)
3385          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
3386      break;
3387    }
3388  }
3389}
3390
3391// A little helper routine: ignore addition and subtraction of integer literals.
3392// This intentionally does not ignore all integer constant expressions because
3393// we don't want to remove sizeof().
3394static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
3395  Ex = Ex->IgnoreParenCasts();
3396
3397  for (;;) {
3398    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
3399    if (!BO || !BO->isAdditiveOp())
3400      break;
3401
3402    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
3403    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
3404
3405    if (isa<IntegerLiteral>(RHS))
3406      Ex = LHS;
3407    else if (isa<IntegerLiteral>(LHS))
3408      Ex = RHS;
3409    else
3410      break;
3411  }
3412
3413  return Ex;
3414}
3415
3416static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
3417                                                      ASTContext &Context) {
3418  // Only handle constant-sized or VLAs, but not flexible members.
3419  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
3420    // Only issue the FIXIT for arrays of size > 1.
3421    if (CAT->getSize().getSExtValue() <= 1)
3422      return false;
3423  } else if (!Ty->isVariableArrayType()) {
3424    return false;
3425  }
3426  return true;
3427}
3428
3429// Warn if the user has made the 'size' argument to strlcpy or strlcat
3430// be the size of the source, instead of the destination.
3431void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
3432                                    IdentifierInfo *FnName) {
3433
3434  // Don't crash if the user has the wrong number of arguments
3435  if (Call->getNumArgs() != 3)
3436    return;
3437
3438  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
3439  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
3440  const Expr *CompareWithSrc = NULL;
3441
3442  // Look for 'strlcpy(dst, x, sizeof(x))'
3443  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
3444    CompareWithSrc = Ex;
3445  else {
3446    // Look for 'strlcpy(dst, x, strlen(x))'
3447    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
3448      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
3449          && SizeCall->getNumArgs() == 1)
3450        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
3451    }
3452  }
3453
3454  if (!CompareWithSrc)
3455    return;
3456
3457  // Determine if the argument to sizeof/strlen is equal to the source
3458  // argument.  In principle there's all kinds of things you could do
3459  // here, for instance creating an == expression and evaluating it with
3460  // EvaluateAsBooleanCondition, but this uses a more direct technique:
3461  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
3462  if (!SrcArgDRE)
3463    return;
3464
3465  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
3466  if (!CompareWithSrcDRE ||
3467      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
3468    return;
3469
3470  const Expr *OriginalSizeArg = Call->getArg(2);
3471  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
3472    << OriginalSizeArg->getSourceRange() << FnName;
3473
3474  // Output a FIXIT hint if the destination is an array (rather than a
3475  // pointer to an array).  This could be enhanced to handle some
3476  // pointers if we know the actual size, like if DstArg is 'array+2'
3477  // we could say 'sizeof(array)-2'.
3478  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
3479  if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
3480    return;
3481
3482  SmallString<128> sizeString;
3483  llvm::raw_svector_ostream OS(sizeString);
3484  OS << "sizeof(";
3485  DstArg->printPretty(OS, 0, getPrintingPolicy());
3486  OS << ")";
3487
3488  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
3489    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
3490                                    OS.str());
3491}
3492
3493/// Check if two expressions refer to the same declaration.
3494static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
3495  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
3496    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
3497      return D1->getDecl() == D2->getDecl();
3498  return false;
3499}
3500
3501static const Expr *getStrlenExprArg(const Expr *E) {
3502  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
3503    const FunctionDecl *FD = CE->getDirectCallee();
3504    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
3505      return 0;
3506    return CE->getArg(0)->IgnoreParenCasts();
3507  }
3508  return 0;
3509}
3510
3511// Warn on anti-patterns as the 'size' argument to strncat.
3512// The correct size argument should look like following:
3513//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
3514void Sema::CheckStrncatArguments(const CallExpr *CE,
3515                                 IdentifierInfo *FnName) {
3516  // Don't crash if the user has the wrong number of arguments.
3517  if (CE->getNumArgs() < 3)
3518    return;
3519  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
3520  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
3521  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
3522
3523  // Identify common expressions, which are wrongly used as the size argument
3524  // to strncat and may lead to buffer overflows.
3525  unsigned PatternType = 0;
3526  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
3527    // - sizeof(dst)
3528    if (referToTheSameDecl(SizeOfArg, DstArg))
3529      PatternType = 1;
3530    // - sizeof(src)
3531    else if (referToTheSameDecl(SizeOfArg, SrcArg))
3532      PatternType = 2;
3533  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
3534    if (BE->getOpcode() == BO_Sub) {
3535      const Expr *L = BE->getLHS()->IgnoreParenCasts();
3536      const Expr *R = BE->getRHS()->IgnoreParenCasts();
3537      // - sizeof(dst) - strlen(dst)
3538      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
3539          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
3540        PatternType = 1;
3541      // - sizeof(src) - (anything)
3542      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
3543        PatternType = 2;
3544    }
3545  }
3546
3547  if (PatternType == 0)
3548    return;
3549
3550  // Generate the diagnostic.
3551  SourceLocation SL = LenArg->getLocStart();
3552  SourceRange SR = LenArg->getSourceRange();
3553  SourceManager &SM  = PP.getSourceManager();
3554
3555  // If the function is defined as a builtin macro, do not show macro expansion.
3556  if (SM.isMacroArgExpansion(SL)) {
3557    SL = SM.getSpellingLoc(SL);
3558    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
3559                     SM.getSpellingLoc(SR.getEnd()));
3560  }
3561
3562  // Check if the destination is an array (rather than a pointer to an array).
3563  QualType DstTy = DstArg->getType();
3564  bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
3565                                                                    Context);
3566  if (!isKnownSizeArray) {
3567    if (PatternType == 1)
3568      Diag(SL, diag::warn_strncat_wrong_size) << SR;
3569    else
3570      Diag(SL, diag::warn_strncat_src_size) << SR;
3571    return;
3572  }
3573
3574  if (PatternType == 1)
3575    Diag(SL, diag::warn_strncat_large_size) << SR;
3576  else
3577    Diag(SL, diag::warn_strncat_src_size) << SR;
3578
3579  SmallString<128> sizeString;
3580  llvm::raw_svector_ostream OS(sizeString);
3581  OS << "sizeof(";
3582  DstArg->printPretty(OS, 0, getPrintingPolicy());
3583  OS << ") - ";
3584  OS << "strlen(";
3585  DstArg->printPretty(OS, 0, getPrintingPolicy());
3586  OS << ") - 1";
3587
3588  Diag(SL, diag::note_strncat_wrong_size)
3589    << FixItHint::CreateReplacement(SR, OS.str());
3590}
3591
3592//===--- CHECK: Return Address of Stack Variable --------------------------===//
3593
3594static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3595                     Decl *ParentDecl);
3596static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3597                      Decl *ParentDecl);
3598
3599/// CheckReturnStackAddr - Check if a return statement returns the address
3600///   of a stack variable.
3601void
3602Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3603                           SourceLocation ReturnLoc) {
3604
3605  Expr *stackE = 0;
3606  SmallVector<DeclRefExpr *, 8> refVars;
3607
3608  // Perform checking for returned stack addresses, local blocks,
3609  // label addresses or references to temporaries.
3610  if (lhsType->isPointerType() ||
3611      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3612    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3613  } else if (lhsType->isReferenceType()) {
3614    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3615  }
3616
3617  if (stackE == 0)
3618    return; // Nothing suspicious was found.
3619
3620  SourceLocation diagLoc;
3621  SourceRange diagRange;
3622  if (refVars.empty()) {
3623    diagLoc = stackE->getLocStart();
3624    diagRange = stackE->getSourceRange();
3625  } else {
3626    // We followed through a reference variable. 'stackE' contains the
3627    // problematic expression but we will warn at the return statement pointing
3628    // at the reference variable. We will later display the "trail" of
3629    // reference variables using notes.
3630    diagLoc = refVars[0]->getLocStart();
3631    diagRange = refVars[0]->getSourceRange();
3632  }
3633
3634  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3635    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3636                                             : diag::warn_ret_stack_addr)
3637     << DR->getDecl()->getDeclName() << diagRange;
3638  } else if (isa<BlockExpr>(stackE)) { // local block.
3639    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3640  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3641    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3642  } else { // local temporary.
3643    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3644                                             : diag::warn_ret_local_temp_addr)
3645     << diagRange;
3646  }
3647
3648  // Display the "trail" of reference variables that we followed until we
3649  // found the problematic expression using notes.
3650  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3651    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3652    // If this var binds to another reference var, show the range of the next
3653    // var, otherwise the var binds to the problematic expression, in which case
3654    // show the range of the expression.
3655    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3656                                  : stackE->getSourceRange();
3657    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3658      << VD->getDeclName() << range;
3659  }
3660}
3661
3662/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3663///  check if the expression in a return statement evaluates to an address
3664///  to a location on the stack, a local block, an address of a label, or a
3665///  reference to local temporary. The recursion is used to traverse the
3666///  AST of the return expression, with recursion backtracking when we
3667///  encounter a subexpression that (1) clearly does not lead to one of the
3668///  above problematic expressions (2) is something we cannot determine leads to
3669///  a problematic expression based on such local checking.
3670///
3671///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3672///  the expression that they point to. Such variables are added to the
3673///  'refVars' vector so that we know what the reference variable "trail" was.
3674///
3675///  EvalAddr processes expressions that are pointers that are used as
3676///  references (and not L-values).  EvalVal handles all other values.
3677///  At the base case of the recursion is a check for the above problematic
3678///  expressions.
3679///
3680///  This implementation handles:
3681///
3682///   * pointer-to-pointer casts
3683///   * implicit conversions from array references to pointers
3684///   * taking the address of fields
3685///   * arbitrary interplay between "&" and "*" operators
3686///   * pointer arithmetic from an address of a stack variable
3687///   * taking the address of an array element where the array is on the stack
3688static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3689                      Decl *ParentDecl) {
3690  if (E->isTypeDependent())
3691      return NULL;
3692
3693  // We should only be called for evaluating pointer expressions.
3694  assert((E->getType()->isAnyPointerType() ||
3695          E->getType()->isBlockPointerType() ||
3696          E->getType()->isObjCQualifiedIdType()) &&
3697         "EvalAddr only works on pointers");
3698
3699  E = E->IgnoreParens();
3700
3701  // Our "symbolic interpreter" is just a dispatch off the currently
3702  // viewed AST node.  We then recursively traverse the AST by calling
3703  // EvalAddr and EvalVal appropriately.
3704  switch (E->getStmtClass()) {
3705  case Stmt::DeclRefExprClass: {
3706    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3707
3708    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3709      // If this is a reference variable, follow through to the expression that
3710      // it points to.
3711      if (V->hasLocalStorage() &&
3712          V->getType()->isReferenceType() && V->hasInit()) {
3713        // Add the reference variable to the "trail".
3714        refVars.push_back(DR);
3715        return EvalAddr(V->getInit(), refVars, ParentDecl);
3716      }
3717
3718    return NULL;
3719  }
3720
3721  case Stmt::UnaryOperatorClass: {
3722    // The only unary operator that make sense to handle here
3723    // is AddrOf.  All others don't make sense as pointers.
3724    UnaryOperator *U = cast<UnaryOperator>(E);
3725
3726    if (U->getOpcode() == UO_AddrOf)
3727      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3728    else
3729      return NULL;
3730  }
3731
3732  case Stmt::BinaryOperatorClass: {
3733    // Handle pointer arithmetic.  All other binary operators are not valid
3734    // in this context.
3735    BinaryOperator *B = cast<BinaryOperator>(E);
3736    BinaryOperatorKind op = B->getOpcode();
3737
3738    if (op != BO_Add && op != BO_Sub)
3739      return NULL;
3740
3741    Expr *Base = B->getLHS();
3742
3743    // Determine which argument is the real pointer base.  It could be
3744    // the RHS argument instead of the LHS.
3745    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3746
3747    assert (Base->getType()->isPointerType());
3748    return EvalAddr(Base, refVars, ParentDecl);
3749  }
3750
3751  // For conditional operators we need to see if either the LHS or RHS are
3752  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3753  case Stmt::ConditionalOperatorClass: {
3754    ConditionalOperator *C = cast<ConditionalOperator>(E);
3755
3756    // Handle the GNU extension for missing LHS.
3757    if (Expr *lhsExpr = C->getLHS()) {
3758    // In C++, we can have a throw-expression, which has 'void' type.
3759      if (!lhsExpr->getType()->isVoidType())
3760        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3761          return LHS;
3762    }
3763
3764    // In C++, we can have a throw-expression, which has 'void' type.
3765    if (C->getRHS()->getType()->isVoidType())
3766      return NULL;
3767
3768    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3769  }
3770
3771  case Stmt::BlockExprClass:
3772    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3773      return E; // local block.
3774    return NULL;
3775
3776  case Stmt::AddrLabelExprClass:
3777    return E; // address of label.
3778
3779  case Stmt::ExprWithCleanupsClass:
3780    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3781                    ParentDecl);
3782
3783  // For casts, we need to handle conversions from arrays to
3784  // pointer values, and pointer-to-pointer conversions.
3785  case Stmt::ImplicitCastExprClass:
3786  case Stmt::CStyleCastExprClass:
3787  case Stmt::CXXFunctionalCastExprClass:
3788  case Stmt::ObjCBridgedCastExprClass:
3789  case Stmt::CXXStaticCastExprClass:
3790  case Stmt::CXXDynamicCastExprClass:
3791  case Stmt::CXXConstCastExprClass:
3792  case Stmt::CXXReinterpretCastExprClass: {
3793    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3794    switch (cast<CastExpr>(E)->getCastKind()) {
3795    case CK_BitCast:
3796    case CK_LValueToRValue:
3797    case CK_NoOp:
3798    case CK_BaseToDerived:
3799    case CK_DerivedToBase:
3800    case CK_UncheckedDerivedToBase:
3801    case CK_Dynamic:
3802    case CK_CPointerToObjCPointerCast:
3803    case CK_BlockPointerToObjCPointerCast:
3804    case CK_AnyPointerToBlockPointerCast:
3805      return EvalAddr(SubExpr, refVars, ParentDecl);
3806
3807    case CK_ArrayToPointerDecay:
3808      return EvalVal(SubExpr, refVars, ParentDecl);
3809
3810    default:
3811      return 0;
3812    }
3813  }
3814
3815  case Stmt::MaterializeTemporaryExprClass:
3816    if (Expr *Result = EvalAddr(
3817                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3818                                refVars, ParentDecl))
3819      return Result;
3820
3821    return E;
3822
3823  // Everything else: we simply don't reason about them.
3824  default:
3825    return NULL;
3826  }
3827}
3828
3829
3830///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3831///   See the comments for EvalAddr for more details.
3832static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3833                     Decl *ParentDecl) {
3834do {
3835  // We should only be called for evaluating non-pointer expressions, or
3836  // expressions with a pointer type that are not used as references but instead
3837  // are l-values (e.g., DeclRefExpr with a pointer type).
3838
3839  // Our "symbolic interpreter" is just a dispatch off the currently
3840  // viewed AST node.  We then recursively traverse the AST by calling
3841  // EvalAddr and EvalVal appropriately.
3842
3843  E = E->IgnoreParens();
3844  switch (E->getStmtClass()) {
3845  case Stmt::ImplicitCastExprClass: {
3846    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3847    if (IE->getValueKind() == VK_LValue) {
3848      E = IE->getSubExpr();
3849      continue;
3850    }
3851    return NULL;
3852  }
3853
3854  case Stmt::ExprWithCleanupsClass:
3855    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3856
3857  case Stmt::DeclRefExprClass: {
3858    // When we hit a DeclRefExpr we are looking at code that refers to a
3859    // variable's name. If it's not a reference variable we check if it has
3860    // local storage within the function, and if so, return the expression.
3861    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3862
3863    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3864      // Check if it refers to itself, e.g. "int& i = i;".
3865      if (V == ParentDecl)
3866        return DR;
3867
3868      if (V->hasLocalStorage()) {
3869        if (!V->getType()->isReferenceType())
3870          return DR;
3871
3872        // Reference variable, follow through to the expression that
3873        // it points to.
3874        if (V->hasInit()) {
3875          // Add the reference variable to the "trail".
3876          refVars.push_back(DR);
3877          return EvalVal(V->getInit(), refVars, V);
3878        }
3879      }
3880    }
3881
3882    return NULL;
3883  }
3884
3885  case Stmt::UnaryOperatorClass: {
3886    // The only unary operator that make sense to handle here
3887    // is Deref.  All others don't resolve to a "name."  This includes
3888    // handling all sorts of rvalues passed to a unary operator.
3889    UnaryOperator *U = cast<UnaryOperator>(E);
3890
3891    if (U->getOpcode() == UO_Deref)
3892      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3893
3894    return NULL;
3895  }
3896
3897  case Stmt::ArraySubscriptExprClass: {
3898    // Array subscripts are potential references to data on the stack.  We
3899    // retrieve the DeclRefExpr* for the array variable if it indeed
3900    // has local storage.
3901    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3902  }
3903
3904  case Stmt::ConditionalOperatorClass: {
3905    // For conditional operators we need to see if either the LHS or RHS are
3906    // non-NULL Expr's.  If one is non-NULL, we return it.
3907    ConditionalOperator *C = cast<ConditionalOperator>(E);
3908
3909    // Handle the GNU extension for missing LHS.
3910    if (Expr *lhsExpr = C->getLHS())
3911      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3912        return LHS;
3913
3914    return EvalVal(C->getRHS(), refVars, ParentDecl);
3915  }
3916
3917  // Accesses to members are potential references to data on the stack.
3918  case Stmt::MemberExprClass: {
3919    MemberExpr *M = cast<MemberExpr>(E);
3920
3921    // Check for indirect access.  We only want direct field accesses.
3922    if (M->isArrow())
3923      return NULL;
3924
3925    // Check whether the member type is itself a reference, in which case
3926    // we're not going to refer to the member, but to what the member refers to.
3927    if (M->getMemberDecl()->getType()->isReferenceType())
3928      return NULL;
3929
3930    return EvalVal(M->getBase(), refVars, ParentDecl);
3931  }
3932
3933  case Stmt::MaterializeTemporaryExprClass:
3934    if (Expr *Result = EvalVal(
3935                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3936                               refVars, ParentDecl))
3937      return Result;
3938
3939    return E;
3940
3941  default:
3942    // Check that we don't return or take the address of a reference to a
3943    // temporary. This is only useful in C++.
3944    if (!E->isTypeDependent() && E->isRValue())
3945      return E;
3946
3947    // Everything else: we simply don't reason about them.
3948    return NULL;
3949  }
3950} while (true);
3951}
3952
3953//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3954
3955/// Check for comparisons of floating point operands using != and ==.
3956/// Issue a warning if these are no self-comparisons, as they are not likely
3957/// to do what the programmer intended.
3958void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3959  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3960  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3961
3962  // Special case: check for x == x (which is OK).
3963  // Do not emit warnings for such cases.
3964  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3965    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3966      if (DRL->getDecl() == DRR->getDecl())
3967        return;
3968
3969
3970  // Special case: check for comparisons against literals that can be exactly
3971  //  represented by APFloat.  In such cases, do not emit a warning.  This
3972  //  is a heuristic: often comparison against such literals are used to
3973  //  detect if a value in a variable has not changed.  This clearly can
3974  //  lead to false negatives.
3975  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3976    if (FLL->isExact())
3977      return;
3978  } else
3979    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
3980      if (FLR->isExact())
3981        return;
3982
3983  // Check for comparisons with builtin types.
3984  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3985    if (CL->isBuiltinCall())
3986      return;
3987
3988  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3989    if (CR->isBuiltinCall())
3990      return;
3991
3992  // Emit the diagnostic.
3993  Diag(Loc, diag::warn_floatingpoint_eq)
3994    << LHS->getSourceRange() << RHS->getSourceRange();
3995}
3996
3997//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3998//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3999
4000namespace {
4001
4002/// Structure recording the 'active' range of an integer-valued
4003/// expression.
4004struct IntRange {
4005  /// The number of bits active in the int.
4006  unsigned Width;
4007
4008  /// True if the int is known not to have negative values.
4009  bool NonNegative;
4010
4011  IntRange(unsigned Width, bool NonNegative)
4012    : Width(Width), NonNegative(NonNegative)
4013  {}
4014
4015  /// Returns the range of the bool type.
4016  static IntRange forBoolType() {
4017    return IntRange(1, true);
4018  }
4019
4020  /// Returns the range of an opaque value of the given integral type.
4021  static IntRange forValueOfType(ASTContext &C, QualType T) {
4022    return forValueOfCanonicalType(C,
4023                          T->getCanonicalTypeInternal().getTypePtr());
4024  }
4025
4026  /// Returns the range of an opaque value of a canonical integral type.
4027  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
4028    assert(T->isCanonicalUnqualified());
4029
4030    if (const VectorType *VT = dyn_cast<VectorType>(T))
4031      T = VT->getElementType().getTypePtr();
4032    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4033      T = CT->getElementType().getTypePtr();
4034
4035    // For enum types, use the known bit width of the enumerators.
4036    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
4037      EnumDecl *Enum = ET->getDecl();
4038      if (!Enum->isCompleteDefinition())
4039        return IntRange(C.getIntWidth(QualType(T, 0)), false);
4040
4041      unsigned NumPositive = Enum->getNumPositiveBits();
4042      unsigned NumNegative = Enum->getNumNegativeBits();
4043
4044      if (NumNegative == 0)
4045        return IntRange(NumPositive, true/*NonNegative*/);
4046      else
4047        return IntRange(std::max(NumPositive + 1, NumNegative),
4048                        false/*NonNegative*/);
4049    }
4050
4051    const BuiltinType *BT = cast<BuiltinType>(T);
4052    assert(BT->isInteger());
4053
4054    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4055  }
4056
4057  /// Returns the "target" range of a canonical integral type, i.e.
4058  /// the range of values expressible in the type.
4059  ///
4060  /// This matches forValueOfCanonicalType except that enums have the
4061  /// full range of their type, not the range of their enumerators.
4062  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
4063    assert(T->isCanonicalUnqualified());
4064
4065    if (const VectorType *VT = dyn_cast<VectorType>(T))
4066      T = VT->getElementType().getTypePtr();
4067    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4068      T = CT->getElementType().getTypePtr();
4069    if (const EnumType *ET = dyn_cast<EnumType>(T))
4070      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
4071
4072    const BuiltinType *BT = cast<BuiltinType>(T);
4073    assert(BT->isInteger());
4074
4075    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4076  }
4077
4078  /// Returns the supremum of two ranges: i.e. their conservative merge.
4079  static IntRange join(IntRange L, IntRange R) {
4080    return IntRange(std::max(L.Width, R.Width),
4081                    L.NonNegative && R.NonNegative);
4082  }
4083
4084  /// Returns the infinum of two ranges: i.e. their aggressive merge.
4085  static IntRange meet(IntRange L, IntRange R) {
4086    return IntRange(std::min(L.Width, R.Width),
4087                    L.NonNegative || R.NonNegative);
4088  }
4089};
4090
4091static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
4092                              unsigned MaxWidth) {
4093  if (value.isSigned() && value.isNegative())
4094    return IntRange(value.getMinSignedBits(), false);
4095
4096  if (value.getBitWidth() > MaxWidth)
4097    value = value.trunc(MaxWidth);
4098
4099  // isNonNegative() just checks the sign bit without considering
4100  // signedness.
4101  return IntRange(value.getActiveBits(), true);
4102}
4103
4104static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
4105                              unsigned MaxWidth) {
4106  if (result.isInt())
4107    return GetValueRange(C, result.getInt(), MaxWidth);
4108
4109  if (result.isVector()) {
4110    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
4111    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
4112      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
4113      R = IntRange::join(R, El);
4114    }
4115    return R;
4116  }
4117
4118  if (result.isComplexInt()) {
4119    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
4120    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
4121    return IntRange::join(R, I);
4122  }
4123
4124  // This can happen with lossless casts to intptr_t of "based" lvalues.
4125  // Assume it might use arbitrary bits.
4126  // FIXME: The only reason we need to pass the type in here is to get
4127  // the sign right on this one case.  It would be nice if APValue
4128  // preserved this.
4129  assert(result.isLValue() || result.isAddrLabelDiff());
4130  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
4131}
4132
4133/// Pseudo-evaluate the given integer expression, estimating the
4134/// range of values it might take.
4135///
4136/// \param MaxWidth - the width to which the value will be truncated
4137static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
4138  E = E->IgnoreParens();
4139
4140  // Try a full evaluation first.
4141  Expr::EvalResult result;
4142  if (E->EvaluateAsRValue(result, C))
4143    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
4144
4145  // I think we only want to look through implicit casts here; if the
4146  // user has an explicit widening cast, we should treat the value as
4147  // being of the new, wider type.
4148  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
4149    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
4150      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
4151
4152    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
4153
4154    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
4155
4156    // Assume that non-integer casts can span the full range of the type.
4157    if (!isIntegerCast)
4158      return OutputTypeRange;
4159
4160    IntRange SubRange
4161      = GetExprRange(C, CE->getSubExpr(),
4162                     std::min(MaxWidth, OutputTypeRange.Width));
4163
4164    // Bail out if the subexpr's range is as wide as the cast type.
4165    if (SubRange.Width >= OutputTypeRange.Width)
4166      return OutputTypeRange;
4167
4168    // Otherwise, we take the smaller width, and we're non-negative if
4169    // either the output type or the subexpr is.
4170    return IntRange(SubRange.Width,
4171                    SubRange.NonNegative || OutputTypeRange.NonNegative);
4172  }
4173
4174  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
4175    // If we can fold the condition, just take that operand.
4176    bool CondResult;
4177    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
4178      return GetExprRange(C, CondResult ? CO->getTrueExpr()
4179                                        : CO->getFalseExpr(),
4180                          MaxWidth);
4181
4182    // Otherwise, conservatively merge.
4183    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
4184    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
4185    return IntRange::join(L, R);
4186  }
4187
4188  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4189    switch (BO->getOpcode()) {
4190
4191    // Boolean-valued operations are single-bit and positive.
4192    case BO_LAnd:
4193    case BO_LOr:
4194    case BO_LT:
4195    case BO_GT:
4196    case BO_LE:
4197    case BO_GE:
4198    case BO_EQ:
4199    case BO_NE:
4200      return IntRange::forBoolType();
4201
4202    // The type of the assignments is the type of the LHS, so the RHS
4203    // is not necessarily the same type.
4204    case BO_MulAssign:
4205    case BO_DivAssign:
4206    case BO_RemAssign:
4207    case BO_AddAssign:
4208    case BO_SubAssign:
4209    case BO_XorAssign:
4210    case BO_OrAssign:
4211      // TODO: bitfields?
4212      return IntRange::forValueOfType(C, E->getType());
4213
4214    // Simple assignments just pass through the RHS, which will have
4215    // been coerced to the LHS type.
4216    case BO_Assign:
4217      // TODO: bitfields?
4218      return GetExprRange(C, BO->getRHS(), MaxWidth);
4219
4220    // Operations with opaque sources are black-listed.
4221    case BO_PtrMemD:
4222    case BO_PtrMemI:
4223      return IntRange::forValueOfType(C, E->getType());
4224
4225    // Bitwise-and uses the *infinum* of the two source ranges.
4226    case BO_And:
4227    case BO_AndAssign:
4228      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
4229                            GetExprRange(C, BO->getRHS(), MaxWidth));
4230
4231    // Left shift gets black-listed based on a judgement call.
4232    case BO_Shl:
4233      // ...except that we want to treat '1 << (blah)' as logically
4234      // positive.  It's an important idiom.
4235      if (IntegerLiteral *I
4236            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
4237        if (I->getValue() == 1) {
4238          IntRange R = IntRange::forValueOfType(C, E->getType());
4239          return IntRange(R.Width, /*NonNegative*/ true);
4240        }
4241      }
4242      // fallthrough
4243
4244    case BO_ShlAssign:
4245      return IntRange::forValueOfType(C, E->getType());
4246
4247    // Right shift by a constant can narrow its left argument.
4248    case BO_Shr:
4249    case BO_ShrAssign: {
4250      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4251
4252      // If the shift amount is a positive constant, drop the width by
4253      // that much.
4254      llvm::APSInt shift;
4255      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
4256          shift.isNonNegative()) {
4257        unsigned zext = shift.getZExtValue();
4258        if (zext >= L.Width)
4259          L.Width = (L.NonNegative ? 0 : 1);
4260        else
4261          L.Width -= zext;
4262      }
4263
4264      return L;
4265    }
4266
4267    // Comma acts as its right operand.
4268    case BO_Comma:
4269      return GetExprRange(C, BO->getRHS(), MaxWidth);
4270
4271    // Black-list pointer subtractions.
4272    case BO_Sub:
4273      if (BO->getLHS()->getType()->isPointerType())
4274        return IntRange::forValueOfType(C, E->getType());
4275      break;
4276
4277    // The width of a division result is mostly determined by the size
4278    // of the LHS.
4279    case BO_Div: {
4280      // Don't 'pre-truncate' the operands.
4281      unsigned opWidth = C.getIntWidth(E->getType());
4282      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4283
4284      // If the divisor is constant, use that.
4285      llvm::APSInt divisor;
4286      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
4287        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
4288        if (log2 >= L.Width)
4289          L.Width = (L.NonNegative ? 0 : 1);
4290        else
4291          L.Width = std::min(L.Width - log2, MaxWidth);
4292        return L;
4293      }
4294
4295      // Otherwise, just use the LHS's width.
4296      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4297      return IntRange(L.Width, L.NonNegative && R.NonNegative);
4298    }
4299
4300    // The result of a remainder can't be larger than the result of
4301    // either side.
4302    case BO_Rem: {
4303      // Don't 'pre-truncate' the operands.
4304      unsigned opWidth = C.getIntWidth(E->getType());
4305      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4306      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4307
4308      IntRange meet = IntRange::meet(L, R);
4309      meet.Width = std::min(meet.Width, MaxWidth);
4310      return meet;
4311    }
4312
4313    // The default behavior is okay for these.
4314    case BO_Mul:
4315    case BO_Add:
4316    case BO_Xor:
4317    case BO_Or:
4318      break;
4319    }
4320
4321    // The default case is to treat the operation as if it were closed
4322    // on the narrowest type that encompasses both operands.
4323    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4324    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
4325    return IntRange::join(L, R);
4326  }
4327
4328  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
4329    switch (UO->getOpcode()) {
4330    // Boolean-valued operations are white-listed.
4331    case UO_LNot:
4332      return IntRange::forBoolType();
4333
4334    // Operations with opaque sources are black-listed.
4335    case UO_Deref:
4336    case UO_AddrOf: // should be impossible
4337      return IntRange::forValueOfType(C, E->getType());
4338
4339    default:
4340      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
4341    }
4342  }
4343
4344  if (dyn_cast<OffsetOfExpr>(E)) {
4345    IntRange::forValueOfType(C, E->getType());
4346  }
4347
4348  if (FieldDecl *BitField = E->getSourceBitField())
4349    return IntRange(BitField->getBitWidthValue(C),
4350                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
4351
4352  return IntRange::forValueOfType(C, E->getType());
4353}
4354
4355static IntRange GetExprRange(ASTContext &C, Expr *E) {
4356  return GetExprRange(C, E, C.getIntWidth(E->getType()));
4357}
4358
4359/// Checks whether the given value, which currently has the given
4360/// source semantics, has the same value when coerced through the
4361/// target semantics.
4362static bool IsSameFloatAfterCast(const llvm::APFloat &value,
4363                                 const llvm::fltSemantics &Src,
4364                                 const llvm::fltSemantics &Tgt) {
4365  llvm::APFloat truncated = value;
4366
4367  bool ignored;
4368  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
4369  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
4370
4371  return truncated.bitwiseIsEqual(value);
4372}
4373
4374/// Checks whether the given value, which currently has the given
4375/// source semantics, has the same value when coerced through the
4376/// target semantics.
4377///
4378/// The value might be a vector of floats (or a complex number).
4379static bool IsSameFloatAfterCast(const APValue &value,
4380                                 const llvm::fltSemantics &Src,
4381                                 const llvm::fltSemantics &Tgt) {
4382  if (value.isFloat())
4383    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
4384
4385  if (value.isVector()) {
4386    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
4387      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
4388        return false;
4389    return true;
4390  }
4391
4392  assert(value.isComplexFloat());
4393  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
4394          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
4395}
4396
4397static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
4398
4399static bool IsZero(Sema &S, Expr *E) {
4400  // Suppress cases where we are comparing against an enum constant.
4401  if (const DeclRefExpr *DR =
4402      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
4403    if (isa<EnumConstantDecl>(DR->getDecl()))
4404      return false;
4405
4406  // Suppress cases where the '0' value is expanded from a macro.
4407  if (E->getLocStart().isMacroID())
4408    return false;
4409
4410  llvm::APSInt Value;
4411  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
4412}
4413
4414static bool HasEnumType(Expr *E) {
4415  // Strip off implicit integral promotions.
4416  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
4417    if (ICE->getCastKind() != CK_IntegralCast &&
4418        ICE->getCastKind() != CK_NoOp)
4419      break;
4420    E = ICE->getSubExpr();
4421  }
4422
4423  return E->getType()->isEnumeralType();
4424}
4425
4426static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
4427  BinaryOperatorKind op = E->getOpcode();
4428  if (E->isValueDependent())
4429    return;
4430
4431  if (op == BO_LT && IsZero(S, E->getRHS())) {
4432    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4433      << "< 0" << "false" << HasEnumType(E->getLHS())
4434      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4435  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
4436    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4437      << ">= 0" << "true" << HasEnumType(E->getLHS())
4438      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4439  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
4440    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4441      << "0 >" << "false" << HasEnumType(E->getRHS())
4442      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4443  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
4444    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4445      << "0 <=" << "true" << HasEnumType(E->getRHS())
4446      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4447  }
4448}
4449
4450static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
4451                                         Expr *Constant, Expr *Other,
4452                                         llvm::APSInt Value,
4453                                         bool RhsConstant) {
4454  // 0 values are handled later by CheckTrivialUnsignedComparison().
4455  if (Value == 0)
4456    return;
4457
4458  BinaryOperatorKind op = E->getOpcode();
4459  QualType OtherT = Other->getType();
4460  QualType ConstantT = Constant->getType();
4461  QualType CommonT = E->getLHS()->getType();
4462  if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
4463    return;
4464  assert((OtherT->isIntegerType() && ConstantT->isIntegerType())
4465         && "comparison with non-integer type");
4466
4467  bool ConstantSigned = ConstantT->isSignedIntegerType();
4468  bool CommonSigned = CommonT->isSignedIntegerType();
4469
4470  bool EqualityOnly = false;
4471
4472  // TODO: Investigate using GetExprRange() to get tighter bounds on
4473  // on the bit ranges.
4474  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
4475  unsigned OtherWidth = OtherRange.Width;
4476
4477  if (CommonSigned) {
4478    // The common type is signed, therefore no signed to unsigned conversion.
4479    if (!OtherRange.NonNegative) {
4480      // Check that the constant is representable in type OtherT.
4481      if (ConstantSigned) {
4482        if (OtherWidth >= Value.getMinSignedBits())
4483          return;
4484      } else { // !ConstantSigned
4485        if (OtherWidth >= Value.getActiveBits() + 1)
4486          return;
4487      }
4488    } else { // !OtherSigned
4489      // Check that the constant is representable in type OtherT.
4490      // Negative values are out of range.
4491      if (ConstantSigned) {
4492        if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
4493          return;
4494      } else { // !ConstantSigned
4495        if (OtherWidth >= Value.getActiveBits())
4496          return;
4497      }
4498    }
4499  } else {  // !CommonSigned
4500    if (OtherRange.NonNegative) {
4501      if (OtherWidth >= Value.getActiveBits())
4502        return;
4503    } else if (!OtherRange.NonNegative && !ConstantSigned) {
4504      // Check to see if the constant is representable in OtherT.
4505      if (OtherWidth > Value.getActiveBits())
4506        return;
4507      // Check to see if the constant is equivalent to a negative value
4508      // cast to CommonT.
4509      if (S.Context.getIntWidth(ConstantT) == S.Context.getIntWidth(CommonT) &&
4510          Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
4511        return;
4512      // The constant value rests between values that OtherT can represent after
4513      // conversion.  Relational comparison still works, but equality
4514      // comparisons will be tautological.
4515      EqualityOnly = true;
4516    } else { // OtherSigned && ConstantSigned
4517      assert(0 && "Two signed types converted to unsigned types.");
4518    }
4519  }
4520
4521  bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
4522
4523  bool IsTrue = true;
4524  if (op == BO_EQ || op == BO_NE) {
4525    IsTrue = op == BO_NE;
4526  } else if (EqualityOnly) {
4527    return;
4528  } else if (RhsConstant) {
4529    if (op == BO_GT || op == BO_GE)
4530      IsTrue = !PositiveConstant;
4531    else // op == BO_LT || op == BO_LE
4532      IsTrue = PositiveConstant;
4533  } else {
4534    if (op == BO_LT || op == BO_LE)
4535      IsTrue = !PositiveConstant;
4536    else // op == BO_GT || op == BO_GE
4537      IsTrue = PositiveConstant;
4538  }
4539
4540  // If this is a comparison to an enum constant, include that
4541  // constant in the diagnostic.
4542  const EnumConstantDecl *ED = 0;
4543  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
4544    ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
4545
4546  SmallString<64> PrettySourceValue;
4547  llvm::raw_svector_ostream OS(PrettySourceValue);
4548  if (ED)
4549    OS << '\'' << *ED << "' (" << Value << ")";
4550  else
4551    OS << Value;
4552
4553  S.Diag(E->getOperatorLoc(), diag::warn_out_of_range_compare)
4554      << OS.str() << OtherT << IsTrue
4555      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4556}
4557
4558/// Analyze the operands of the given comparison.  Implements the
4559/// fallback case from AnalyzeComparison.
4560static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
4561  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4562  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4563}
4564
4565/// \brief Implements -Wsign-compare.
4566///
4567/// \param E the binary operator to check for warnings
4568static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
4569  // The type the comparison is being performed in.
4570  QualType T = E->getLHS()->getType();
4571  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
4572         && "comparison with mismatched types");
4573  if (E->isValueDependent())
4574    return AnalyzeImpConvsInComparison(S, E);
4575
4576  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
4577  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
4578
4579  bool IsComparisonConstant = false;
4580
4581  // Check whether an integer constant comparison results in a value
4582  // of 'true' or 'false'.
4583  if (T->isIntegralType(S.Context)) {
4584    llvm::APSInt RHSValue;
4585    bool IsRHSIntegralLiteral =
4586      RHS->isIntegerConstantExpr(RHSValue, S.Context);
4587    llvm::APSInt LHSValue;
4588    bool IsLHSIntegralLiteral =
4589      LHS->isIntegerConstantExpr(LHSValue, S.Context);
4590    if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
4591        DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
4592    else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
4593      DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
4594    else
4595      IsComparisonConstant =
4596        (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
4597  } else if (!T->hasUnsignedIntegerRepresentation())
4598      IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
4599
4600  // We don't do anything special if this isn't an unsigned integral
4601  // comparison:  we're only interested in integral comparisons, and
4602  // signed comparisons only happen in cases we don't care to warn about.
4603  //
4604  // We also don't care about value-dependent expressions or expressions
4605  // whose result is a constant.
4606  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
4607    return AnalyzeImpConvsInComparison(S, E);
4608
4609  // Check to see if one of the (unmodified) operands is of different
4610  // signedness.
4611  Expr *signedOperand, *unsignedOperand;
4612  if (LHS->getType()->hasSignedIntegerRepresentation()) {
4613    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
4614           "unsigned comparison between two signed integer expressions?");
4615    signedOperand = LHS;
4616    unsignedOperand = RHS;
4617  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
4618    signedOperand = RHS;
4619    unsignedOperand = LHS;
4620  } else {
4621    CheckTrivialUnsignedComparison(S, E);
4622    return AnalyzeImpConvsInComparison(S, E);
4623  }
4624
4625  // Otherwise, calculate the effective range of the signed operand.
4626  IntRange signedRange = GetExprRange(S.Context, signedOperand);
4627
4628  // Go ahead and analyze implicit conversions in the operands.  Note
4629  // that we skip the implicit conversions on both sides.
4630  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
4631  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
4632
4633  // If the signed range is non-negative, -Wsign-compare won't fire,
4634  // but we should still check for comparisons which are always true
4635  // or false.
4636  if (signedRange.NonNegative)
4637    return CheckTrivialUnsignedComparison(S, E);
4638
4639  // For (in)equality comparisons, if the unsigned operand is a
4640  // constant which cannot collide with a overflowed signed operand,
4641  // then reinterpreting the signed operand as unsigned will not
4642  // change the result of the comparison.
4643  if (E->isEqualityOp()) {
4644    unsigned comparisonWidth = S.Context.getIntWidth(T);
4645    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
4646
4647    // We should never be unable to prove that the unsigned operand is
4648    // non-negative.
4649    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
4650
4651    if (unsignedRange.Width < comparisonWidth)
4652      return;
4653  }
4654
4655  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
4656    S.PDiag(diag::warn_mixed_sign_comparison)
4657      << LHS->getType() << RHS->getType()
4658      << LHS->getSourceRange() << RHS->getSourceRange());
4659}
4660
4661/// Analyzes an attempt to assign the given value to a bitfield.
4662///
4663/// Returns true if there was something fishy about the attempt.
4664static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
4665                                      SourceLocation InitLoc) {
4666  assert(Bitfield->isBitField());
4667  if (Bitfield->isInvalidDecl())
4668    return false;
4669
4670  // White-list bool bitfields.
4671  if (Bitfield->getType()->isBooleanType())
4672    return false;
4673
4674  // Ignore value- or type-dependent expressions.
4675  if (Bitfield->getBitWidth()->isValueDependent() ||
4676      Bitfield->getBitWidth()->isTypeDependent() ||
4677      Init->isValueDependent() ||
4678      Init->isTypeDependent())
4679    return false;
4680
4681  Expr *OriginalInit = Init->IgnoreParenImpCasts();
4682
4683  llvm::APSInt Value;
4684  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
4685    return false;
4686
4687  unsigned OriginalWidth = Value.getBitWidth();
4688  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
4689
4690  if (OriginalWidth <= FieldWidth)
4691    return false;
4692
4693  // Compute the value which the bitfield will contain.
4694  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
4695  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
4696
4697  // Check whether the stored value is equal to the original value.
4698  TruncatedValue = TruncatedValue.extend(OriginalWidth);
4699  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
4700    return false;
4701
4702  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4703  // therefore don't strictly fit into a signed bitfield of width 1.
4704  if (FieldWidth == 1 && Value == 1)
4705    return false;
4706
4707  std::string PrettyValue = Value.toString(10);
4708  std::string PrettyTrunc = TruncatedValue.toString(10);
4709
4710  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4711    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4712    << Init->getSourceRange();
4713
4714  return true;
4715}
4716
4717/// Analyze the given simple or compound assignment for warning-worthy
4718/// operations.
4719static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4720  // Just recurse on the LHS.
4721  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4722
4723  // We want to recurse on the RHS as normal unless we're assigning to
4724  // a bitfield.
4725  if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
4726    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4727                                  E->getOperatorLoc())) {
4728      // Recurse, ignoring any implicit conversions on the RHS.
4729      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4730                                        E->getOperatorLoc());
4731    }
4732  }
4733
4734  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4735}
4736
4737/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4738static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4739                            SourceLocation CContext, unsigned diag,
4740                            bool pruneControlFlow = false) {
4741  if (pruneControlFlow) {
4742    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4743                          S.PDiag(diag)
4744                            << SourceType << T << E->getSourceRange()
4745                            << SourceRange(CContext));
4746    return;
4747  }
4748  S.Diag(E->getExprLoc(), diag)
4749    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4750}
4751
4752/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4753static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4754                            SourceLocation CContext, unsigned diag,
4755                            bool pruneControlFlow = false) {
4756  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4757}
4758
4759/// Diagnose an implicit cast from a literal expression. Does not warn when the
4760/// cast wouldn't lose information.
4761void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4762                                    SourceLocation CContext) {
4763  // Try to convert the literal exactly to an integer. If we can, don't warn.
4764  bool isExact = false;
4765  const llvm::APFloat &Value = FL->getValue();
4766  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4767                            T->hasUnsignedIntegerRepresentation());
4768  if (Value.convertToInteger(IntegerValue,
4769                             llvm::APFloat::rmTowardZero, &isExact)
4770      == llvm::APFloat::opOK && isExact)
4771    return;
4772
4773  SmallString<16> PrettySourceValue;
4774  Value.toString(PrettySourceValue);
4775  SmallString<16> PrettyTargetValue;
4776  if (T->isSpecificBuiltinType(BuiltinType::Bool))
4777    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
4778  else
4779    IntegerValue.toString(PrettyTargetValue);
4780
4781  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4782    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
4783    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
4784}
4785
4786std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4787  if (!Range.Width) return "0";
4788
4789  llvm::APSInt ValueInRange = Value;
4790  ValueInRange.setIsSigned(!Range.NonNegative);
4791  ValueInRange = ValueInRange.trunc(Range.Width);
4792  return ValueInRange.toString(10);
4793}
4794
4795static bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
4796  if (!isa<ImplicitCastExpr>(Ex))
4797    return false;
4798
4799  Expr *InnerE = Ex->IgnoreParenImpCasts();
4800  const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
4801  const Type *Source =
4802    S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4803  if (Target->isDependentType())
4804    return false;
4805
4806  const BuiltinType *FloatCandidateBT =
4807    dyn_cast<BuiltinType>(ToBool ? Source : Target);
4808  const Type *BoolCandidateType = ToBool ? Target : Source;
4809
4810  return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
4811          FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
4812}
4813
4814void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
4815                                      SourceLocation CC) {
4816  unsigned NumArgs = TheCall->getNumArgs();
4817  for (unsigned i = 0; i < NumArgs; ++i) {
4818    Expr *CurrA = TheCall->getArg(i);
4819    if (!IsImplicitBoolFloatConversion(S, CurrA, true))
4820      continue;
4821
4822    bool IsSwapped = ((i > 0) &&
4823        IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
4824    IsSwapped |= ((i < (NumArgs - 1)) &&
4825        IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
4826    if (IsSwapped) {
4827      // Warn on this floating-point to bool conversion.
4828      DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
4829                      CurrA->getType(), CC,
4830                      diag::warn_impcast_floating_point_to_bool);
4831    }
4832  }
4833}
4834
4835void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4836                             SourceLocation CC, bool *ICContext = 0) {
4837  if (E->isTypeDependent() || E->isValueDependent()) return;
4838
4839  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4840  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4841  if (Source == Target) return;
4842  if (Target->isDependentType()) return;
4843
4844  // If the conversion context location is invalid don't complain. We also
4845  // don't want to emit a warning if the issue occurs from the expansion of
4846  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4847  // delay this check as long as possible. Once we detect we are in that
4848  // scenario, we just return.
4849  if (CC.isInvalid())
4850    return;
4851
4852  // Diagnose implicit casts to bool.
4853  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4854    if (isa<StringLiteral>(E))
4855      // Warn on string literal to bool.  Checks for string literals in logical
4856      // expressions, for instances, assert(0 && "error here"), is prevented
4857      // by a check in AnalyzeImplicitConversions().
4858      return DiagnoseImpCast(S, E, T, CC,
4859                             diag::warn_impcast_string_literal_to_bool);
4860    if (Source->isFunctionType()) {
4861      // Warn on function to bool. Checks free functions and static member
4862      // functions. Weakly imported functions are excluded from the check,
4863      // since it's common to test their value to check whether the linker
4864      // found a definition for them.
4865      ValueDecl *D = 0;
4866      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4867        D = R->getDecl();
4868      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4869        D = M->getMemberDecl();
4870      }
4871
4872      if (D && !D->isWeak()) {
4873        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4874          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4875            << F << E->getSourceRange() << SourceRange(CC);
4876          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4877            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4878          QualType ReturnType;
4879          UnresolvedSet<4> NonTemplateOverloads;
4880          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
4881          if (!ReturnType.isNull()
4882              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4883            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4884              << FixItHint::CreateInsertion(
4885                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4886          return;
4887        }
4888      }
4889    }
4890  }
4891
4892  // Strip vector types.
4893  if (isa<VectorType>(Source)) {
4894    if (!isa<VectorType>(Target)) {
4895      if (S.SourceMgr.isInSystemMacro(CC))
4896        return;
4897      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4898    }
4899
4900    // If the vector cast is cast between two vectors of the same size, it is
4901    // a bitcast, not a conversion.
4902    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4903      return;
4904
4905    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4906    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4907  }
4908
4909  // Strip complex types.
4910  if (isa<ComplexType>(Source)) {
4911    if (!isa<ComplexType>(Target)) {
4912      if (S.SourceMgr.isInSystemMacro(CC))
4913        return;
4914
4915      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4916    }
4917
4918    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4919    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4920  }
4921
4922  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4923  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4924
4925  // If the source is floating point...
4926  if (SourceBT && SourceBT->isFloatingPoint()) {
4927    // ...and the target is floating point...
4928    if (TargetBT && TargetBT->isFloatingPoint()) {
4929      // ...then warn if we're dropping FP rank.
4930
4931      // Builtin FP kinds are ordered by increasing FP rank.
4932      if (SourceBT->getKind() > TargetBT->getKind()) {
4933        // Don't warn about float constants that are precisely
4934        // representable in the target type.
4935        Expr::EvalResult result;
4936        if (E->EvaluateAsRValue(result, S.Context)) {
4937          // Value might be a float, a float vector, or a float complex.
4938          if (IsSameFloatAfterCast(result.Val,
4939                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4940                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4941            return;
4942        }
4943
4944        if (S.SourceMgr.isInSystemMacro(CC))
4945          return;
4946
4947        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4948      }
4949      return;
4950    }
4951
4952    // If the target is integral, always warn.
4953    if (TargetBT && TargetBT->isInteger()) {
4954      if (S.SourceMgr.isInSystemMacro(CC))
4955        return;
4956
4957      Expr *InnerE = E->IgnoreParenImpCasts();
4958      // We also want to warn on, e.g., "int i = -1.234"
4959      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4960        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4961          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4962
4963      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4964        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4965      } else {
4966        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4967      }
4968    }
4969
4970    // If the target is bool, warn if expr is a function or method call.
4971    if (Target->isSpecificBuiltinType(BuiltinType::Bool) &&
4972        isa<CallExpr>(E)) {
4973      // Check last argument of function call to see if it is an
4974      // implicit cast from a type matching the type the result
4975      // is being cast to.
4976      CallExpr *CEx = cast<CallExpr>(E);
4977      unsigned NumArgs = CEx->getNumArgs();
4978      if (NumArgs > 0) {
4979        Expr *LastA = CEx->getArg(NumArgs - 1);
4980        Expr *InnerE = LastA->IgnoreParenImpCasts();
4981        const Type *InnerType =
4982          S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4983        if (isa<ImplicitCastExpr>(LastA) && (InnerType == Target)) {
4984          // Warn on this floating-point to bool conversion
4985          DiagnoseImpCast(S, E, T, CC,
4986                          diag::warn_impcast_floating_point_to_bool);
4987        }
4988      }
4989    }
4990    return;
4991  }
4992
4993  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4994           == Expr::NPCK_GNUNull) && !Target->isAnyPointerType()
4995      && !Target->isBlockPointerType() && !Target->isMemberPointerType()
4996      && Target->isScalarType() && !Target->isNullPtrType()) {
4997    SourceLocation Loc = E->getSourceRange().getBegin();
4998    if (Loc.isMacroID())
4999      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
5000    if (!Loc.isMacroID() || CC.isMacroID())
5001      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
5002          << T << clang::SourceRange(CC)
5003          << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
5004  }
5005
5006  if (!Source->isIntegerType() || !Target->isIntegerType())
5007    return;
5008
5009  // TODO: remove this early return once the false positives for constant->bool
5010  // in templates, macros, etc, are reduced or removed.
5011  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
5012    return;
5013
5014  IntRange SourceRange = GetExprRange(S.Context, E);
5015  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
5016
5017  if (SourceRange.Width > TargetRange.Width) {
5018    // If the source is a constant, use a default-on diagnostic.
5019    // TODO: this should happen for bitfield stores, too.
5020    llvm::APSInt Value(32);
5021    if (E->isIntegerConstantExpr(Value, S.Context)) {
5022      if (S.SourceMgr.isInSystemMacro(CC))
5023        return;
5024
5025      std::string PrettySourceValue = Value.toString(10);
5026      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
5027
5028      S.DiagRuntimeBehavior(E->getExprLoc(), E,
5029        S.PDiag(diag::warn_impcast_integer_precision_constant)
5030            << PrettySourceValue << PrettyTargetValue
5031            << E->getType() << T << E->getSourceRange()
5032            << clang::SourceRange(CC));
5033      return;
5034    }
5035
5036    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
5037    if (S.SourceMgr.isInSystemMacro(CC))
5038      return;
5039
5040    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
5041      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
5042                             /* pruneControlFlow */ true);
5043    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
5044  }
5045
5046  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
5047      (!TargetRange.NonNegative && SourceRange.NonNegative &&
5048       SourceRange.Width == TargetRange.Width)) {
5049
5050    if (S.SourceMgr.isInSystemMacro(CC))
5051      return;
5052
5053    unsigned DiagID = diag::warn_impcast_integer_sign;
5054
5055    // Traditionally, gcc has warned about this under -Wsign-compare.
5056    // We also want to warn about it in -Wconversion.
5057    // So if -Wconversion is off, use a completely identical diagnostic
5058    // in the sign-compare group.
5059    // The conditional-checking code will
5060    if (ICContext) {
5061      DiagID = diag::warn_impcast_integer_sign_conditional;
5062      *ICContext = true;
5063    }
5064
5065    return DiagnoseImpCast(S, E, T, CC, DiagID);
5066  }
5067
5068  // Diagnose conversions between different enumeration types.
5069  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
5070  // type, to give us better diagnostics.
5071  QualType SourceType = E->getType();
5072  if (!S.getLangOpts().CPlusPlus) {
5073    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5074      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
5075        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
5076        SourceType = S.Context.getTypeDeclType(Enum);
5077        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
5078      }
5079  }
5080
5081  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
5082    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
5083      if (SourceEnum->getDecl()->hasNameForLinkage() &&
5084          TargetEnum->getDecl()->hasNameForLinkage() &&
5085          SourceEnum != TargetEnum) {
5086        if (S.SourceMgr.isInSystemMacro(CC))
5087          return;
5088
5089        return DiagnoseImpCast(S, E, SourceType, T, CC,
5090                               diag::warn_impcast_different_enum_types);
5091      }
5092
5093  return;
5094}
5095
5096void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5097                              SourceLocation CC, QualType T);
5098
5099void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
5100                             SourceLocation CC, bool &ICContext) {
5101  E = E->IgnoreParenImpCasts();
5102
5103  if (isa<ConditionalOperator>(E))
5104    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
5105
5106  AnalyzeImplicitConversions(S, E, CC);
5107  if (E->getType() != T)
5108    return CheckImplicitConversion(S, E, T, CC, &ICContext);
5109  return;
5110}
5111
5112void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5113                              SourceLocation CC, QualType T) {
5114  AnalyzeImplicitConversions(S, E->getCond(), CC);
5115
5116  bool Suspicious = false;
5117  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
5118  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
5119
5120  // If -Wconversion would have warned about either of the candidates
5121  // for a signedness conversion to the context type...
5122  if (!Suspicious) return;
5123
5124  // ...but it's currently ignored...
5125  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
5126                                 CC))
5127    return;
5128
5129  // ...then check whether it would have warned about either of the
5130  // candidates for a signedness conversion to the condition type.
5131  if (E->getType() == T) return;
5132
5133  Suspicious = false;
5134  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
5135                          E->getType(), CC, &Suspicious);
5136  if (!Suspicious)
5137    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
5138                            E->getType(), CC, &Suspicious);
5139}
5140
5141/// AnalyzeImplicitConversions - Find and report any interesting
5142/// implicit conversions in the given expression.  There are a couple
5143/// of competing diagnostics here, -Wconversion and -Wsign-compare.
5144void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
5145  QualType T = OrigE->getType();
5146  Expr *E = OrigE->IgnoreParenImpCasts();
5147
5148  if (E->isTypeDependent() || E->isValueDependent())
5149    return;
5150
5151  // For conditional operators, we analyze the arguments as if they
5152  // were being fed directly into the output.
5153  if (isa<ConditionalOperator>(E)) {
5154    ConditionalOperator *CO = cast<ConditionalOperator>(E);
5155    CheckConditionalOperator(S, CO, CC, T);
5156    return;
5157  }
5158
5159  // Check implicit argument conversions for function calls.
5160  if (CallExpr *Call = dyn_cast<CallExpr>(E))
5161    CheckImplicitArgumentConversions(S, Call, CC);
5162
5163  // Go ahead and check any implicit conversions we might have skipped.
5164  // The non-canonical typecheck is just an optimization;
5165  // CheckImplicitConversion will filter out dead implicit conversions.
5166  if (E->getType() != T)
5167    CheckImplicitConversion(S, E, T, CC);
5168
5169  // Now continue drilling into this expression.
5170
5171  // Skip past explicit casts.
5172  if (isa<ExplicitCastExpr>(E)) {
5173    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
5174    return AnalyzeImplicitConversions(S, E, CC);
5175  }
5176
5177  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5178    // Do a somewhat different check with comparison operators.
5179    if (BO->isComparisonOp())
5180      return AnalyzeComparison(S, BO);
5181
5182    // And with simple assignments.
5183    if (BO->getOpcode() == BO_Assign)
5184      return AnalyzeAssignment(S, BO);
5185  }
5186
5187  // These break the otherwise-useful invariant below.  Fortunately,
5188  // we don't really need to recurse into them, because any internal
5189  // expressions should have been analyzed already when they were
5190  // built into statements.
5191  if (isa<StmtExpr>(E)) return;
5192
5193  // Don't descend into unevaluated contexts.
5194  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
5195
5196  // Now just recurse over the expression's children.
5197  CC = E->getExprLoc();
5198  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
5199  bool IsLogicalOperator = BO && BO->isLogicalOp();
5200  for (Stmt::child_range I = E->children(); I; ++I) {
5201    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
5202    if (!ChildExpr)
5203      continue;
5204
5205    if (IsLogicalOperator &&
5206        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
5207      // Ignore checking string literals that are in logical operators.
5208      continue;
5209    AnalyzeImplicitConversions(S, ChildExpr, CC);
5210  }
5211}
5212
5213} // end anonymous namespace
5214
5215/// Diagnoses "dangerous" implicit conversions within the given
5216/// expression (which is a full expression).  Implements -Wconversion
5217/// and -Wsign-compare.
5218///
5219/// \param CC the "context" location of the implicit conversion, i.e.
5220///   the most location of the syntactic entity requiring the implicit
5221///   conversion
5222void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
5223  // Don't diagnose in unevaluated contexts.
5224  if (isUnevaluatedContext())
5225    return;
5226
5227  // Don't diagnose for value- or type-dependent expressions.
5228  if (E->isTypeDependent() || E->isValueDependent())
5229    return;
5230
5231  // Check for array bounds violations in cases where the check isn't triggered
5232  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
5233  // ArraySubscriptExpr is on the RHS of a variable initialization.
5234  CheckArrayAccess(E);
5235
5236  // This is not the right CC for (e.g.) a variable initialization.
5237  AnalyzeImplicitConversions(*this, E, CC);
5238}
5239
5240/// Diagnose when expression is an integer constant expression and its evaluation
5241/// results in integer overflow
5242void Sema::CheckForIntOverflow (Expr *E) {
5243  if (isa<BinaryOperator>(E->IgnoreParens())) {
5244    llvm::SmallVector<PartialDiagnosticAt, 4> Diags;
5245    E->EvaluateForOverflow(Context, &Diags);
5246  }
5247}
5248
5249namespace {
5250/// \brief Visitor for expressions which looks for unsequenced operations on the
5251/// same object.
5252class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
5253  /// \brief A tree of sequenced regions within an expression. Two regions are
5254  /// unsequenced if one is an ancestor or a descendent of the other. When we
5255  /// finish processing an expression with sequencing, such as a comma
5256  /// expression, we fold its tree nodes into its parent, since they are
5257  /// unsequenced with respect to nodes we will visit later.
5258  class SequenceTree {
5259    struct Value {
5260      explicit Value(unsigned Parent) : Parent(Parent), Merged(false) {}
5261      unsigned Parent : 31;
5262      bool Merged : 1;
5263    };
5264    llvm::SmallVector<Value, 8> Values;
5265
5266  public:
5267    /// \brief A region within an expression which may be sequenced with respect
5268    /// to some other region.
5269    class Seq {
5270      explicit Seq(unsigned N) : Index(N) {}
5271      unsigned Index;
5272      friend class SequenceTree;
5273    public:
5274      Seq() : Index(0) {}
5275    };
5276
5277    SequenceTree() { Values.push_back(Value(0)); }
5278    Seq root() const { return Seq(0); }
5279
5280    /// \brief Create a new sequence of operations, which is an unsequenced
5281    /// subset of \p Parent. This sequence of operations is sequenced with
5282    /// respect to other children of \p Parent.
5283    Seq allocate(Seq Parent) {
5284      Values.push_back(Value(Parent.Index));
5285      return Seq(Values.size() - 1);
5286    }
5287
5288    /// \brief Merge a sequence of operations into its parent.
5289    void merge(Seq S) {
5290      Values[S.Index].Merged = true;
5291    }
5292
5293    /// \brief Determine whether two operations are unsequenced. This operation
5294    /// is asymmetric: \p Cur should be the more recent sequence, and \p Old
5295    /// should have been merged into its parent as appropriate.
5296    bool isUnsequenced(Seq Cur, Seq Old) {
5297      unsigned C = representative(Cur.Index);
5298      unsigned Target = representative(Old.Index);
5299      while (C >= Target) {
5300        if (C == Target)
5301          return true;
5302        C = Values[C].Parent;
5303      }
5304      return false;
5305    }
5306
5307  private:
5308    /// \brief Pick a representative for a sequence.
5309    unsigned representative(unsigned K) {
5310      if (Values[K].Merged)
5311        // Perform path compression as we go.
5312        return Values[K].Parent = representative(Values[K].Parent);
5313      return K;
5314    }
5315  };
5316
5317  /// An object for which we can track unsequenced uses.
5318  typedef NamedDecl *Object;
5319
5320  /// Different flavors of object usage which we track. We only track the
5321  /// least-sequenced usage of each kind.
5322  enum UsageKind {
5323    /// A read of an object. Multiple unsequenced reads are OK.
5324    UK_Use,
5325    /// A modification of an object which is sequenced before the value
5326    /// computation of the expression, such as ++n.
5327    UK_ModAsValue,
5328    /// A modification of an object which is not sequenced before the value
5329    /// computation of the expression, such as n++.
5330    UK_ModAsSideEffect,
5331
5332    UK_Count = UK_ModAsSideEffect + 1
5333  };
5334
5335  struct Usage {
5336    Usage() : Use(0), Seq() {}
5337    Expr *Use;
5338    SequenceTree::Seq Seq;
5339  };
5340
5341  struct UsageInfo {
5342    UsageInfo() : Diagnosed(false) {}
5343    Usage Uses[UK_Count];
5344    /// Have we issued a diagnostic for this variable already?
5345    bool Diagnosed;
5346  };
5347  typedef llvm::SmallDenseMap<Object, UsageInfo, 16> UsageInfoMap;
5348
5349  Sema &SemaRef;
5350  /// Sequenced regions within the expression.
5351  SequenceTree Tree;
5352  /// Declaration modifications and references which we have seen.
5353  UsageInfoMap UsageMap;
5354  /// The region we are currently within.
5355  SequenceTree::Seq Region;
5356  /// Filled in with declarations which were modified as a side-effect
5357  /// (that is, post-increment operations).
5358  llvm::SmallVectorImpl<std::pair<Object, Usage> > *ModAsSideEffect;
5359  /// Expressions to check later. We defer checking these to reduce
5360  /// stack usage.
5361  llvm::SmallVectorImpl<Expr*> &WorkList;
5362
5363  /// RAII object wrapping the visitation of a sequenced subexpression of an
5364  /// expression. At the end of this process, the side-effects of the evaluation
5365  /// become sequenced with respect to the value computation of the result, so
5366  /// we downgrade any UK_ModAsSideEffect within the evaluation to
5367  /// UK_ModAsValue.
5368  struct SequencedSubexpression {
5369    SequencedSubexpression(SequenceChecker &Self)
5370      : Self(Self), OldModAsSideEffect(Self.ModAsSideEffect) {
5371      Self.ModAsSideEffect = &ModAsSideEffect;
5372    }
5373    ~SequencedSubexpression() {
5374      for (unsigned I = 0, E = ModAsSideEffect.size(); I != E; ++I) {
5375        UsageInfo &U = Self.UsageMap[ModAsSideEffect[I].first];
5376        U.Uses[UK_ModAsSideEffect] = ModAsSideEffect[I].second;
5377        Self.addUsage(U, ModAsSideEffect[I].first,
5378                      ModAsSideEffect[I].second.Use, UK_ModAsValue);
5379      }
5380      Self.ModAsSideEffect = OldModAsSideEffect;
5381    }
5382
5383    SequenceChecker &Self;
5384    llvm::SmallVector<std::pair<Object, Usage>, 4> ModAsSideEffect;
5385    llvm::SmallVectorImpl<std::pair<Object, Usage> > *OldModAsSideEffect;
5386  };
5387
5388  /// \brief Find the object which is produced by the specified expression,
5389  /// if any.
5390  Object getObject(Expr *E, bool Mod) const {
5391    E = E->IgnoreParenCasts();
5392    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
5393      if (Mod && (UO->getOpcode() == UO_PreInc || UO->getOpcode() == UO_PreDec))
5394        return getObject(UO->getSubExpr(), Mod);
5395    } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5396      if (BO->getOpcode() == BO_Comma)
5397        return getObject(BO->getRHS(), Mod);
5398      if (Mod && BO->isAssignmentOp())
5399        return getObject(BO->getLHS(), Mod);
5400    } else if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
5401      // FIXME: Check for more interesting cases, like "x.n = ++x.n".
5402      if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenCasts()))
5403        return ME->getMemberDecl();
5404    } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5405      // FIXME: If this is a reference, map through to its value.
5406      return DRE->getDecl();
5407    return 0;
5408  }
5409
5410  /// \brief Note that an object was modified or used by an expression.
5411  void addUsage(UsageInfo &UI, Object O, Expr *Ref, UsageKind UK) {
5412    Usage &U = UI.Uses[UK];
5413    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq)) {
5414      if (UK == UK_ModAsSideEffect && ModAsSideEffect)
5415        ModAsSideEffect->push_back(std::make_pair(O, U));
5416      U.Use = Ref;
5417      U.Seq = Region;
5418    }
5419  }
5420  /// \brief Check whether a modification or use conflicts with a prior usage.
5421  void checkUsage(Object O, UsageInfo &UI, Expr *Ref, UsageKind OtherKind,
5422                  bool IsModMod) {
5423    if (UI.Diagnosed)
5424      return;
5425
5426    const Usage &U = UI.Uses[OtherKind];
5427    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq))
5428      return;
5429
5430    Expr *Mod = U.Use;
5431    Expr *ModOrUse = Ref;
5432    if (OtherKind == UK_Use)
5433      std::swap(Mod, ModOrUse);
5434
5435    SemaRef.Diag(Mod->getExprLoc(),
5436                 IsModMod ? diag::warn_unsequenced_mod_mod
5437                          : diag::warn_unsequenced_mod_use)
5438      << O << SourceRange(ModOrUse->getExprLoc());
5439    UI.Diagnosed = true;
5440  }
5441
5442  void notePreUse(Object O, Expr *Use) {
5443    UsageInfo &U = UsageMap[O];
5444    // Uses conflict with other modifications.
5445    checkUsage(O, U, Use, UK_ModAsValue, false);
5446  }
5447  void notePostUse(Object O, Expr *Use) {
5448    UsageInfo &U = UsageMap[O];
5449    checkUsage(O, U, Use, UK_ModAsSideEffect, false);
5450    addUsage(U, O, Use, UK_Use);
5451  }
5452
5453  void notePreMod(Object O, Expr *Mod) {
5454    UsageInfo &U = UsageMap[O];
5455    // Modifications conflict with other modifications and with uses.
5456    checkUsage(O, U, Mod, UK_ModAsValue, true);
5457    checkUsage(O, U, Mod, UK_Use, false);
5458  }
5459  void notePostMod(Object O, Expr *Use, UsageKind UK) {
5460    UsageInfo &U = UsageMap[O];
5461    checkUsage(O, U, Use, UK_ModAsSideEffect, true);
5462    addUsage(U, O, Use, UK);
5463  }
5464
5465public:
5466  SequenceChecker(Sema &S, Expr *E,
5467                  llvm::SmallVectorImpl<Expr*> &WorkList)
5468    : EvaluatedExprVisitor<SequenceChecker>(S.Context), SemaRef(S),
5469      Region(Tree.root()), ModAsSideEffect(0), WorkList(WorkList) {
5470    Visit(E);
5471  }
5472
5473  void VisitStmt(Stmt *S) {
5474    // Skip all statements which aren't expressions for now.
5475  }
5476
5477  void VisitExpr(Expr *E) {
5478    // By default, just recurse to evaluated subexpressions.
5479    EvaluatedExprVisitor<SequenceChecker>::VisitStmt(E);
5480  }
5481
5482  void VisitCastExpr(CastExpr *E) {
5483    Object O = Object();
5484    if (E->getCastKind() == CK_LValueToRValue)
5485      O = getObject(E->getSubExpr(), false);
5486
5487    if (O)
5488      notePreUse(O, E);
5489    VisitExpr(E);
5490    if (O)
5491      notePostUse(O, E);
5492  }
5493
5494  void VisitBinComma(BinaryOperator *BO) {
5495    // C++11 [expr.comma]p1:
5496    //   Every value computation and side effect associated with the left
5497    //   expression is sequenced before every value computation and side
5498    //   effect associated with the right expression.
5499    SequenceTree::Seq LHS = Tree.allocate(Region);
5500    SequenceTree::Seq RHS = Tree.allocate(Region);
5501    SequenceTree::Seq OldRegion = Region;
5502
5503    {
5504      SequencedSubexpression SeqLHS(*this);
5505      Region = LHS;
5506      Visit(BO->getLHS());
5507    }
5508
5509    Region = RHS;
5510    Visit(BO->getRHS());
5511
5512    Region = OldRegion;
5513
5514    // Forget that LHS and RHS are sequenced. They are both unsequenced
5515    // with respect to other stuff.
5516    Tree.merge(LHS);
5517    Tree.merge(RHS);
5518  }
5519
5520  void VisitBinAssign(BinaryOperator *BO) {
5521    // The modification is sequenced after the value computation of the LHS
5522    // and RHS, so check it before inspecting the operands and update the
5523    // map afterwards.
5524    Object O = getObject(BO->getLHS(), true);
5525    if (!O)
5526      return VisitExpr(BO);
5527
5528    notePreMod(O, BO);
5529
5530    // C++11 [expr.ass]p7:
5531    //   E1 op= E2 is equivalent to E1 = E1 op E2, except that E1 is evaluated
5532    //   only once.
5533    //
5534    // Therefore, for a compound assignment operator, O is considered used
5535    // everywhere except within the evaluation of E1 itself.
5536    if (isa<CompoundAssignOperator>(BO))
5537      notePreUse(O, BO);
5538
5539    Visit(BO->getLHS());
5540
5541    if (isa<CompoundAssignOperator>(BO))
5542      notePostUse(O, BO);
5543
5544    Visit(BO->getRHS());
5545
5546    notePostMod(O, BO, UK_ModAsValue);
5547  }
5548  void VisitCompoundAssignOperator(CompoundAssignOperator *CAO) {
5549    VisitBinAssign(CAO);
5550  }
5551
5552  void VisitUnaryPreInc(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5553  void VisitUnaryPreDec(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5554  void VisitUnaryPreIncDec(UnaryOperator *UO) {
5555    Object O = getObject(UO->getSubExpr(), true);
5556    if (!O)
5557      return VisitExpr(UO);
5558
5559    notePreMod(O, UO);
5560    Visit(UO->getSubExpr());
5561    notePostMod(O, UO, UK_ModAsValue);
5562  }
5563
5564  void VisitUnaryPostInc(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5565  void VisitUnaryPostDec(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5566  void VisitUnaryPostIncDec(UnaryOperator *UO) {
5567    Object O = getObject(UO->getSubExpr(), true);
5568    if (!O)
5569      return VisitExpr(UO);
5570
5571    notePreMod(O, UO);
5572    Visit(UO->getSubExpr());
5573    notePostMod(O, UO, UK_ModAsSideEffect);
5574  }
5575
5576  /// Don't visit the RHS of '&&' or '||' if it might not be evaluated.
5577  void VisitBinLOr(BinaryOperator *BO) {
5578    // The side-effects of the LHS of an '&&' are sequenced before the
5579    // value computation of the RHS, and hence before the value computation
5580    // of the '&&' itself, unless the LHS evaluates to zero. We treat them
5581    // as if they were unconditionally sequenced.
5582    {
5583      SequencedSubexpression Sequenced(*this);
5584      Visit(BO->getLHS());
5585    }
5586
5587    bool Result;
5588    if (!BO->getLHS()->isValueDependent() &&
5589        BO->getLHS()->EvaluateAsBooleanCondition(Result, SemaRef.Context)) {
5590      if (!Result)
5591        Visit(BO->getRHS());
5592    } else {
5593      // Check for unsequenced operations in the RHS, treating it as an
5594      // entirely separate evaluation.
5595      //
5596      // FIXME: If there are operations in the RHS which are unsequenced
5597      // with respect to operations outside the RHS, and those operations
5598      // are unconditionally evaluated, diagnose them.
5599      WorkList.push_back(BO->getRHS());
5600    }
5601  }
5602  void VisitBinLAnd(BinaryOperator *BO) {
5603    {
5604      SequencedSubexpression Sequenced(*this);
5605      Visit(BO->getLHS());
5606    }
5607
5608    bool Result;
5609    if (!BO->getLHS()->isValueDependent() &&
5610        BO->getLHS()->EvaluateAsBooleanCondition(Result, SemaRef.Context)) {
5611      if (Result)
5612        Visit(BO->getRHS());
5613    } else {
5614      WorkList.push_back(BO->getRHS());
5615    }
5616  }
5617
5618  // Only visit the condition, unless we can be sure which subexpression will
5619  // be chosen.
5620  void VisitAbstractConditionalOperator(AbstractConditionalOperator *CO) {
5621    SequencedSubexpression Sequenced(*this);
5622    Visit(CO->getCond());
5623
5624    bool Result;
5625    if (!CO->getCond()->isValueDependent() &&
5626        CO->getCond()->EvaluateAsBooleanCondition(Result, SemaRef.Context))
5627      Visit(Result ? CO->getTrueExpr() : CO->getFalseExpr());
5628    else {
5629      WorkList.push_back(CO->getTrueExpr());
5630      WorkList.push_back(CO->getFalseExpr());
5631    }
5632  }
5633
5634  void VisitCXXConstructExpr(CXXConstructExpr *CCE) {
5635    if (!CCE->isListInitialization())
5636      return VisitExpr(CCE);
5637
5638    // In C++11, list initializations are sequenced.
5639    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5640    SequenceTree::Seq Parent = Region;
5641    for (CXXConstructExpr::arg_iterator I = CCE->arg_begin(),
5642                                        E = CCE->arg_end();
5643         I != E; ++I) {
5644      Region = Tree.allocate(Parent);
5645      Elts.push_back(Region);
5646      Visit(*I);
5647    }
5648
5649    // Forget that the initializers are sequenced.
5650    Region = Parent;
5651    for (unsigned I = 0; I < Elts.size(); ++I)
5652      Tree.merge(Elts[I]);
5653  }
5654
5655  void VisitInitListExpr(InitListExpr *ILE) {
5656    if (!SemaRef.getLangOpts().CPlusPlus11)
5657      return VisitExpr(ILE);
5658
5659    // In C++11, list initializations are sequenced.
5660    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5661    SequenceTree::Seq Parent = Region;
5662    for (unsigned I = 0; I < ILE->getNumInits(); ++I) {
5663      Expr *E = ILE->getInit(I);
5664      if (!E) continue;
5665      Region = Tree.allocate(Parent);
5666      Elts.push_back(Region);
5667      Visit(E);
5668    }
5669
5670    // Forget that the initializers are sequenced.
5671    Region = Parent;
5672    for (unsigned I = 0; I < Elts.size(); ++I)
5673      Tree.merge(Elts[I]);
5674  }
5675};
5676}
5677
5678void Sema::CheckUnsequencedOperations(Expr *E) {
5679  llvm::SmallVector<Expr*, 8> WorkList;
5680  WorkList.push_back(E);
5681  while (!WorkList.empty()) {
5682    Expr *Item = WorkList.back();
5683    WorkList.pop_back();
5684    SequenceChecker(*this, Item, WorkList);
5685  }
5686}
5687
5688void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
5689                              bool IsConstexpr) {
5690  CheckImplicitConversions(E, CheckLoc);
5691  CheckUnsequencedOperations(E);
5692  if (!IsConstexpr && !E->isValueDependent())
5693    CheckForIntOverflow(E);
5694}
5695
5696void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
5697                                       FieldDecl *BitField,
5698                                       Expr *Init) {
5699  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
5700}
5701
5702/// CheckParmsForFunctionDef - Check that the parameters of the given
5703/// function are appropriate for the definition of a function. This
5704/// takes care of any checks that cannot be performed on the
5705/// declaration itself, e.g., that the types of each of the function
5706/// parameters are complete.
5707bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
5708                                    bool CheckParameterNames) {
5709  bool HasInvalidParm = false;
5710  for (; P != PEnd; ++P) {
5711    ParmVarDecl *Param = *P;
5712
5713    // C99 6.7.5.3p4: the parameters in a parameter type list in a
5714    // function declarator that is part of a function definition of
5715    // that function shall not have incomplete type.
5716    //
5717    // This is also C++ [dcl.fct]p6.
5718    if (!Param->isInvalidDecl() &&
5719        RequireCompleteType(Param->getLocation(), Param->getType(),
5720                            diag::err_typecheck_decl_incomplete_type)) {
5721      Param->setInvalidDecl();
5722      HasInvalidParm = true;
5723    }
5724
5725    // C99 6.9.1p5: If the declarator includes a parameter type list, the
5726    // declaration of each parameter shall include an identifier.
5727    if (CheckParameterNames &&
5728        Param->getIdentifier() == 0 &&
5729        !Param->isImplicit() &&
5730        !getLangOpts().CPlusPlus)
5731      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
5732
5733    // C99 6.7.5.3p12:
5734    //   If the function declarator is not part of a definition of that
5735    //   function, parameters may have incomplete type and may use the [*]
5736    //   notation in their sequences of declarator specifiers to specify
5737    //   variable length array types.
5738    QualType PType = Param->getOriginalType();
5739    while (const ArrayType *AT = Context.getAsArrayType(PType)) {
5740      if (AT->getSizeModifier() == ArrayType::Star) {
5741        // FIXME: This diagnostic should point the '[*]' if source-location
5742        // information is added for it.
5743        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
5744        break;
5745      }
5746      PType= AT->getElementType();
5747    }
5748  }
5749
5750  return HasInvalidParm;
5751}
5752
5753/// CheckCastAlign - Implements -Wcast-align, which warns when a
5754/// pointer cast increases the alignment requirements.
5755void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
5756  // This is actually a lot of work to potentially be doing on every
5757  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
5758  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
5759                                          TRange.getBegin())
5760        == DiagnosticsEngine::Ignored)
5761    return;
5762
5763  // Ignore dependent types.
5764  if (T->isDependentType() || Op->getType()->isDependentType())
5765    return;
5766
5767  // Require that the destination be a pointer type.
5768  const PointerType *DestPtr = T->getAs<PointerType>();
5769  if (!DestPtr) return;
5770
5771  // If the destination has alignment 1, we're done.
5772  QualType DestPointee = DestPtr->getPointeeType();
5773  if (DestPointee->isIncompleteType()) return;
5774  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
5775  if (DestAlign.isOne()) return;
5776
5777  // Require that the source be a pointer type.
5778  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
5779  if (!SrcPtr) return;
5780  QualType SrcPointee = SrcPtr->getPointeeType();
5781
5782  // Whitelist casts from cv void*.  We already implicitly
5783  // whitelisted casts to cv void*, since they have alignment 1.
5784  // Also whitelist casts involving incomplete types, which implicitly
5785  // includes 'void'.
5786  if (SrcPointee->isIncompleteType()) return;
5787
5788  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
5789  if (SrcAlign >= DestAlign) return;
5790
5791  Diag(TRange.getBegin(), diag::warn_cast_align)
5792    << Op->getType() << T
5793    << static_cast<unsigned>(SrcAlign.getQuantity())
5794    << static_cast<unsigned>(DestAlign.getQuantity())
5795    << TRange << Op->getSourceRange();
5796}
5797
5798static const Type* getElementType(const Expr *BaseExpr) {
5799  const Type* EltType = BaseExpr->getType().getTypePtr();
5800  if (EltType->isAnyPointerType())
5801    return EltType->getPointeeType().getTypePtr();
5802  else if (EltType->isArrayType())
5803    return EltType->getBaseElementTypeUnsafe();
5804  return EltType;
5805}
5806
5807/// \brief Check whether this array fits the idiom of a size-one tail padded
5808/// array member of a struct.
5809///
5810/// We avoid emitting out-of-bounds access warnings for such arrays as they are
5811/// commonly used to emulate flexible arrays in C89 code.
5812static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
5813                                    const NamedDecl *ND) {
5814  if (Size != 1 || !ND) return false;
5815
5816  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
5817  if (!FD) return false;
5818
5819  // Don't consider sizes resulting from macro expansions or template argument
5820  // substitution to form C89 tail-padded arrays.
5821
5822  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
5823  while (TInfo) {
5824    TypeLoc TL = TInfo->getTypeLoc();
5825    // Look through typedefs.
5826    if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
5827      const TypedefNameDecl *TDL = TTL.getTypedefNameDecl();
5828      TInfo = TDL->getTypeSourceInfo();
5829      continue;
5830    }
5831    if (ConstantArrayTypeLoc CTL = TL.getAs<ConstantArrayTypeLoc>()) {
5832      const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
5833      if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
5834        return false;
5835    }
5836    break;
5837  }
5838
5839  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
5840  if (!RD) return false;
5841  if (RD->isUnion()) return false;
5842  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
5843    if (!CRD->isStandardLayout()) return false;
5844  }
5845
5846  // See if this is the last field decl in the record.
5847  const Decl *D = FD;
5848  while ((D = D->getNextDeclInContext()))
5849    if (isa<FieldDecl>(D))
5850      return false;
5851  return true;
5852}
5853
5854void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
5855                            const ArraySubscriptExpr *ASE,
5856                            bool AllowOnePastEnd, bool IndexNegated) {
5857  IndexExpr = IndexExpr->IgnoreParenImpCasts();
5858  if (IndexExpr->isValueDependent())
5859    return;
5860
5861  const Type *EffectiveType = getElementType(BaseExpr);
5862  BaseExpr = BaseExpr->IgnoreParenCasts();
5863  const ConstantArrayType *ArrayTy =
5864    Context.getAsConstantArrayType(BaseExpr->getType());
5865  if (!ArrayTy)
5866    return;
5867
5868  llvm::APSInt index;
5869  if (!IndexExpr->EvaluateAsInt(index, Context))
5870    return;
5871  if (IndexNegated)
5872    index = -index;
5873
5874  const NamedDecl *ND = NULL;
5875  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5876    ND = dyn_cast<NamedDecl>(DRE->getDecl());
5877  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5878    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5879
5880  if (index.isUnsigned() || !index.isNegative()) {
5881    llvm::APInt size = ArrayTy->getSize();
5882    if (!size.isStrictlyPositive())
5883      return;
5884
5885    const Type* BaseType = getElementType(BaseExpr);
5886    if (BaseType != EffectiveType) {
5887      // Make sure we're comparing apples to apples when comparing index to size
5888      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
5889      uint64_t array_typesize = Context.getTypeSize(BaseType);
5890      // Handle ptrarith_typesize being zero, such as when casting to void*
5891      if (!ptrarith_typesize) ptrarith_typesize = 1;
5892      if (ptrarith_typesize != array_typesize) {
5893        // There's a cast to a different size type involved
5894        uint64_t ratio = array_typesize / ptrarith_typesize;
5895        // TODO: Be smarter about handling cases where array_typesize is not a
5896        // multiple of ptrarith_typesize
5897        if (ptrarith_typesize * ratio == array_typesize)
5898          size *= llvm::APInt(size.getBitWidth(), ratio);
5899      }
5900    }
5901
5902    if (size.getBitWidth() > index.getBitWidth())
5903      index = index.zext(size.getBitWidth());
5904    else if (size.getBitWidth() < index.getBitWidth())
5905      size = size.zext(index.getBitWidth());
5906
5907    // For array subscripting the index must be less than size, but for pointer
5908    // arithmetic also allow the index (offset) to be equal to size since
5909    // computing the next address after the end of the array is legal and
5910    // commonly done e.g. in C++ iterators and range-based for loops.
5911    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
5912      return;
5913
5914    // Also don't warn for arrays of size 1 which are members of some
5915    // structure. These are often used to approximate flexible arrays in C89
5916    // code.
5917    if (IsTailPaddedMemberArray(*this, size, ND))
5918      return;
5919
5920    // Suppress the warning if the subscript expression (as identified by the
5921    // ']' location) and the index expression are both from macro expansions
5922    // within a system header.
5923    if (ASE) {
5924      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
5925          ASE->getRBracketLoc());
5926      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
5927        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
5928            IndexExpr->getLocStart());
5929        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
5930          return;
5931      }
5932    }
5933
5934    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
5935    if (ASE)
5936      DiagID = diag::warn_array_index_exceeds_bounds;
5937
5938    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5939                        PDiag(DiagID) << index.toString(10, true)
5940                          << size.toString(10, true)
5941                          << (unsigned)size.getLimitedValue(~0U)
5942                          << IndexExpr->getSourceRange());
5943  } else {
5944    unsigned DiagID = diag::warn_array_index_precedes_bounds;
5945    if (!ASE) {
5946      DiagID = diag::warn_ptr_arith_precedes_bounds;
5947      if (index.isNegative()) index = -index;
5948    }
5949
5950    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5951                        PDiag(DiagID) << index.toString(10, true)
5952                          << IndexExpr->getSourceRange());
5953  }
5954
5955  if (!ND) {
5956    // Try harder to find a NamedDecl to point at in the note.
5957    while (const ArraySubscriptExpr *ASE =
5958           dyn_cast<ArraySubscriptExpr>(BaseExpr))
5959      BaseExpr = ASE->getBase()->IgnoreParenCasts();
5960    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5961      ND = dyn_cast<NamedDecl>(DRE->getDecl());
5962    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5963      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5964  }
5965
5966  if (ND)
5967    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
5968                        PDiag(diag::note_array_index_out_of_bounds)
5969                          << ND->getDeclName());
5970}
5971
5972void Sema::CheckArrayAccess(const Expr *expr) {
5973  int AllowOnePastEnd = 0;
5974  while (expr) {
5975    expr = expr->IgnoreParenImpCasts();
5976    switch (expr->getStmtClass()) {
5977      case Stmt::ArraySubscriptExprClass: {
5978        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
5979        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
5980                         AllowOnePastEnd > 0);
5981        return;
5982      }
5983      case Stmt::UnaryOperatorClass: {
5984        // Only unwrap the * and & unary operators
5985        const UnaryOperator *UO = cast<UnaryOperator>(expr);
5986        expr = UO->getSubExpr();
5987        switch (UO->getOpcode()) {
5988          case UO_AddrOf:
5989            AllowOnePastEnd++;
5990            break;
5991          case UO_Deref:
5992            AllowOnePastEnd--;
5993            break;
5994          default:
5995            return;
5996        }
5997        break;
5998      }
5999      case Stmt::ConditionalOperatorClass: {
6000        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
6001        if (const Expr *lhs = cond->getLHS())
6002          CheckArrayAccess(lhs);
6003        if (const Expr *rhs = cond->getRHS())
6004          CheckArrayAccess(rhs);
6005        return;
6006      }
6007      default:
6008        return;
6009    }
6010  }
6011}
6012
6013//===--- CHECK: Objective-C retain cycles ----------------------------------//
6014
6015namespace {
6016  struct RetainCycleOwner {
6017    RetainCycleOwner() : Variable(0), Indirect(false) {}
6018    VarDecl *Variable;
6019    SourceRange Range;
6020    SourceLocation Loc;
6021    bool Indirect;
6022
6023    void setLocsFrom(Expr *e) {
6024      Loc = e->getExprLoc();
6025      Range = e->getSourceRange();
6026    }
6027  };
6028}
6029
6030/// Consider whether capturing the given variable can possibly lead to
6031/// a retain cycle.
6032static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
6033  // In ARC, it's captured strongly iff the variable has __strong
6034  // lifetime.  In MRR, it's captured strongly if the variable is
6035  // __block and has an appropriate type.
6036  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6037    return false;
6038
6039  owner.Variable = var;
6040  if (ref)
6041    owner.setLocsFrom(ref);
6042  return true;
6043}
6044
6045static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
6046  while (true) {
6047    e = e->IgnoreParens();
6048    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
6049      switch (cast->getCastKind()) {
6050      case CK_BitCast:
6051      case CK_LValueBitCast:
6052      case CK_LValueToRValue:
6053      case CK_ARCReclaimReturnedObject:
6054        e = cast->getSubExpr();
6055        continue;
6056
6057      default:
6058        return false;
6059      }
6060    }
6061
6062    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
6063      ObjCIvarDecl *ivar = ref->getDecl();
6064      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6065        return false;
6066
6067      // Try to find a retain cycle in the base.
6068      if (!findRetainCycleOwner(S, ref->getBase(), owner))
6069        return false;
6070
6071      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
6072      owner.Indirect = true;
6073      return true;
6074    }
6075
6076    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
6077      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
6078      if (!var) return false;
6079      return considerVariable(var, ref, owner);
6080    }
6081
6082    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
6083      if (member->isArrow()) return false;
6084
6085      // Don't count this as an indirect ownership.
6086      e = member->getBase();
6087      continue;
6088    }
6089
6090    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
6091      // Only pay attention to pseudo-objects on property references.
6092      ObjCPropertyRefExpr *pre
6093        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
6094                                              ->IgnoreParens());
6095      if (!pre) return false;
6096      if (pre->isImplicitProperty()) return false;
6097      ObjCPropertyDecl *property = pre->getExplicitProperty();
6098      if (!property->isRetaining() &&
6099          !(property->getPropertyIvarDecl() &&
6100            property->getPropertyIvarDecl()->getType()
6101              .getObjCLifetime() == Qualifiers::OCL_Strong))
6102          return false;
6103
6104      owner.Indirect = true;
6105      if (pre->isSuperReceiver()) {
6106        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
6107        if (!owner.Variable)
6108          return false;
6109        owner.Loc = pre->getLocation();
6110        owner.Range = pre->getSourceRange();
6111        return true;
6112      }
6113      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
6114                              ->getSourceExpr());
6115      continue;
6116    }
6117
6118    // Array ivars?
6119
6120    return false;
6121  }
6122}
6123
6124namespace {
6125  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
6126    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
6127      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
6128        Variable(variable), Capturer(0) {}
6129
6130    VarDecl *Variable;
6131    Expr *Capturer;
6132
6133    void VisitDeclRefExpr(DeclRefExpr *ref) {
6134      if (ref->getDecl() == Variable && !Capturer)
6135        Capturer = ref;
6136    }
6137
6138    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
6139      if (Capturer) return;
6140      Visit(ref->getBase());
6141      if (Capturer && ref->isFreeIvar())
6142        Capturer = ref;
6143    }
6144
6145    void VisitBlockExpr(BlockExpr *block) {
6146      // Look inside nested blocks
6147      if (block->getBlockDecl()->capturesVariable(Variable))
6148        Visit(block->getBlockDecl()->getBody());
6149    }
6150
6151    void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
6152      if (Capturer) return;
6153      if (OVE->getSourceExpr())
6154        Visit(OVE->getSourceExpr());
6155    }
6156  };
6157}
6158
6159/// Check whether the given argument is a block which captures a
6160/// variable.
6161static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
6162  assert(owner.Variable && owner.Loc.isValid());
6163
6164  e = e->IgnoreParenCasts();
6165
6166  // Look through [^{...} copy] and Block_copy(^{...}).
6167  if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
6168    Selector Cmd = ME->getSelector();
6169    if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
6170      e = ME->getInstanceReceiver();
6171      if (!e)
6172        return 0;
6173      e = e->IgnoreParenCasts();
6174    }
6175  } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
6176    if (CE->getNumArgs() == 1) {
6177      FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
6178      if (Fn) {
6179        const IdentifierInfo *FnI = Fn->getIdentifier();
6180        if (FnI && FnI->isStr("_Block_copy")) {
6181          e = CE->getArg(0)->IgnoreParenCasts();
6182        }
6183      }
6184    }
6185  }
6186
6187  BlockExpr *block = dyn_cast<BlockExpr>(e);
6188  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
6189    return 0;
6190
6191  FindCaptureVisitor visitor(S.Context, owner.Variable);
6192  visitor.Visit(block->getBlockDecl()->getBody());
6193  return visitor.Capturer;
6194}
6195
6196static void diagnoseRetainCycle(Sema &S, Expr *capturer,
6197                                RetainCycleOwner &owner) {
6198  assert(capturer);
6199  assert(owner.Variable && owner.Loc.isValid());
6200
6201  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
6202    << owner.Variable << capturer->getSourceRange();
6203  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
6204    << owner.Indirect << owner.Range;
6205}
6206
6207/// Check for a keyword selector that starts with the word 'add' or
6208/// 'set'.
6209static bool isSetterLikeSelector(Selector sel) {
6210  if (sel.isUnarySelector()) return false;
6211
6212  StringRef str = sel.getNameForSlot(0);
6213  while (!str.empty() && str.front() == '_') str = str.substr(1);
6214  if (str.startswith("set"))
6215    str = str.substr(3);
6216  else if (str.startswith("add")) {
6217    // Specially whitelist 'addOperationWithBlock:'.
6218    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
6219      return false;
6220    str = str.substr(3);
6221  }
6222  else
6223    return false;
6224
6225  if (str.empty()) return true;
6226  return !isLowercase(str.front());
6227}
6228
6229/// Check a message send to see if it's likely to cause a retain cycle.
6230void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
6231  // Only check instance methods whose selector looks like a setter.
6232  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
6233    return;
6234
6235  // Try to find a variable that the receiver is strongly owned by.
6236  RetainCycleOwner owner;
6237  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
6238    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
6239      return;
6240  } else {
6241    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
6242    owner.Variable = getCurMethodDecl()->getSelfDecl();
6243    owner.Loc = msg->getSuperLoc();
6244    owner.Range = msg->getSuperLoc();
6245  }
6246
6247  // Check whether the receiver is captured by any of the arguments.
6248  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
6249    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
6250      return diagnoseRetainCycle(*this, capturer, owner);
6251}
6252
6253/// Check a property assign to see if it's likely to cause a retain cycle.
6254void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
6255  RetainCycleOwner owner;
6256  if (!findRetainCycleOwner(*this, receiver, owner))
6257    return;
6258
6259  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
6260    diagnoseRetainCycle(*this, capturer, owner);
6261}
6262
6263void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
6264  RetainCycleOwner Owner;
6265  if (!considerVariable(Var, /*DeclRefExpr=*/0, Owner))
6266    return;
6267
6268  // Because we don't have an expression for the variable, we have to set the
6269  // location explicitly here.
6270  Owner.Loc = Var->getLocation();
6271  Owner.Range = Var->getSourceRange();
6272
6273  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
6274    diagnoseRetainCycle(*this, Capturer, Owner);
6275}
6276
6277static bool checkUnsafeAssignLiteral(Sema &S, SourceLocation Loc,
6278                                     Expr *RHS, bool isProperty) {
6279  // Check if RHS is an Objective-C object literal, which also can get
6280  // immediately zapped in a weak reference.  Note that we explicitly
6281  // allow ObjCStringLiterals, since those are designed to never really die.
6282  RHS = RHS->IgnoreParenImpCasts();
6283
6284  // This enum needs to match with the 'select' in
6285  // warn_objc_arc_literal_assign (off-by-1).
6286  Sema::ObjCLiteralKind Kind = S.CheckLiteralKind(RHS);
6287  if (Kind == Sema::LK_String || Kind == Sema::LK_None)
6288    return false;
6289
6290  S.Diag(Loc, diag::warn_arc_literal_assign)
6291    << (unsigned) Kind
6292    << (isProperty ? 0 : 1)
6293    << RHS->getSourceRange();
6294
6295  return true;
6296}
6297
6298static bool checkUnsafeAssignObject(Sema &S, SourceLocation Loc,
6299                                    Qualifiers::ObjCLifetime LT,
6300                                    Expr *RHS, bool isProperty) {
6301  // Strip off any implicit cast added to get to the one ARC-specific.
6302  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6303    if (cast->getCastKind() == CK_ARCConsumeObject) {
6304      S.Diag(Loc, diag::warn_arc_retained_assign)
6305        << (LT == Qualifiers::OCL_ExplicitNone)
6306        << (isProperty ? 0 : 1)
6307        << RHS->getSourceRange();
6308      return true;
6309    }
6310    RHS = cast->getSubExpr();
6311  }
6312
6313  if (LT == Qualifiers::OCL_Weak &&
6314      checkUnsafeAssignLiteral(S, Loc, RHS, isProperty))
6315    return true;
6316
6317  return false;
6318}
6319
6320bool Sema::checkUnsafeAssigns(SourceLocation Loc,
6321                              QualType LHS, Expr *RHS) {
6322  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
6323
6324  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
6325    return false;
6326
6327  if (checkUnsafeAssignObject(*this, Loc, LT, RHS, false))
6328    return true;
6329
6330  return false;
6331}
6332
6333void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
6334                              Expr *LHS, Expr *RHS) {
6335  QualType LHSType;
6336  // PropertyRef on LHS type need be directly obtained from
6337  // its declaration as it has a PsuedoType.
6338  ObjCPropertyRefExpr *PRE
6339    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
6340  if (PRE && !PRE->isImplicitProperty()) {
6341    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6342    if (PD)
6343      LHSType = PD->getType();
6344  }
6345
6346  if (LHSType.isNull())
6347    LHSType = LHS->getType();
6348
6349  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
6350
6351  if (LT == Qualifiers::OCL_Weak) {
6352    DiagnosticsEngine::Level Level =
6353      Diags.getDiagnosticLevel(diag::warn_arc_repeated_use_of_weak, Loc);
6354    if (Level != DiagnosticsEngine::Ignored)
6355      getCurFunction()->markSafeWeakUse(LHS);
6356  }
6357
6358  if (checkUnsafeAssigns(Loc, LHSType, RHS))
6359    return;
6360
6361  // FIXME. Check for other life times.
6362  if (LT != Qualifiers::OCL_None)
6363    return;
6364
6365  if (PRE) {
6366    if (PRE->isImplicitProperty())
6367      return;
6368    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6369    if (!PD)
6370      return;
6371
6372    unsigned Attributes = PD->getPropertyAttributes();
6373    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
6374      // when 'assign' attribute was not explicitly specified
6375      // by user, ignore it and rely on property type itself
6376      // for lifetime info.
6377      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
6378      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
6379          LHSType->isObjCRetainableType())
6380        return;
6381
6382      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6383        if (cast->getCastKind() == CK_ARCConsumeObject) {
6384          Diag(Loc, diag::warn_arc_retained_property_assign)
6385          << RHS->getSourceRange();
6386          return;
6387        }
6388        RHS = cast->getSubExpr();
6389      }
6390    }
6391    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
6392      if (checkUnsafeAssignObject(*this, Loc, Qualifiers::OCL_Weak, RHS, true))
6393        return;
6394    }
6395  }
6396}
6397
6398//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
6399
6400namespace {
6401bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
6402                                 SourceLocation StmtLoc,
6403                                 const NullStmt *Body) {
6404  // Do not warn if the body is a macro that expands to nothing, e.g:
6405  //
6406  // #define CALL(x)
6407  // if (condition)
6408  //   CALL(0);
6409  //
6410  if (Body->hasLeadingEmptyMacro())
6411    return false;
6412
6413  // Get line numbers of statement and body.
6414  bool StmtLineInvalid;
6415  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
6416                                                      &StmtLineInvalid);
6417  if (StmtLineInvalid)
6418    return false;
6419
6420  bool BodyLineInvalid;
6421  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
6422                                                      &BodyLineInvalid);
6423  if (BodyLineInvalid)
6424    return false;
6425
6426  // Warn if null statement and body are on the same line.
6427  if (StmtLine != BodyLine)
6428    return false;
6429
6430  return true;
6431}
6432} // Unnamed namespace
6433
6434void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
6435                                 const Stmt *Body,
6436                                 unsigned DiagID) {
6437  // Since this is a syntactic check, don't emit diagnostic for template
6438  // instantiations, this just adds noise.
6439  if (CurrentInstantiationScope)
6440    return;
6441
6442  // The body should be a null statement.
6443  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6444  if (!NBody)
6445    return;
6446
6447  // Do the usual checks.
6448  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6449    return;
6450
6451  Diag(NBody->getSemiLoc(), DiagID);
6452  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6453}
6454
6455void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
6456                                 const Stmt *PossibleBody) {
6457  assert(!CurrentInstantiationScope); // Ensured by caller
6458
6459  SourceLocation StmtLoc;
6460  const Stmt *Body;
6461  unsigned DiagID;
6462  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
6463    StmtLoc = FS->getRParenLoc();
6464    Body = FS->getBody();
6465    DiagID = diag::warn_empty_for_body;
6466  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
6467    StmtLoc = WS->getCond()->getSourceRange().getEnd();
6468    Body = WS->getBody();
6469    DiagID = diag::warn_empty_while_body;
6470  } else
6471    return; // Neither `for' nor `while'.
6472
6473  // The body should be a null statement.
6474  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6475  if (!NBody)
6476    return;
6477
6478  // Skip expensive checks if diagnostic is disabled.
6479  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
6480          DiagnosticsEngine::Ignored)
6481    return;
6482
6483  // Do the usual checks.
6484  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6485    return;
6486
6487  // `for(...);' and `while(...);' are popular idioms, so in order to keep
6488  // noise level low, emit diagnostics only if for/while is followed by a
6489  // CompoundStmt, e.g.:
6490  //    for (int i = 0; i < n; i++);
6491  //    {
6492  //      a(i);
6493  //    }
6494  // or if for/while is followed by a statement with more indentation
6495  // than for/while itself:
6496  //    for (int i = 0; i < n; i++);
6497  //      a(i);
6498  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
6499  if (!ProbableTypo) {
6500    bool BodyColInvalid;
6501    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
6502                             PossibleBody->getLocStart(),
6503                             &BodyColInvalid);
6504    if (BodyColInvalid)
6505      return;
6506
6507    bool StmtColInvalid;
6508    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
6509                             S->getLocStart(),
6510                             &StmtColInvalid);
6511    if (StmtColInvalid)
6512      return;
6513
6514    if (BodyCol > StmtCol)
6515      ProbableTypo = true;
6516  }
6517
6518  if (ProbableTypo) {
6519    Diag(NBody->getSemiLoc(), DiagID);
6520    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6521  }
6522}
6523
6524//===--- Layout compatibility ----------------------------------------------//
6525
6526namespace {
6527
6528bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
6529
6530/// \brief Check if two enumeration types are layout-compatible.
6531bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
6532  // C++11 [dcl.enum] p8:
6533  // Two enumeration types are layout-compatible if they have the same
6534  // underlying type.
6535  return ED1->isComplete() && ED2->isComplete() &&
6536         C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
6537}
6538
6539/// \brief Check if two fields are layout-compatible.
6540bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
6541  if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
6542    return false;
6543
6544  if (Field1->isBitField() != Field2->isBitField())
6545    return false;
6546
6547  if (Field1->isBitField()) {
6548    // Make sure that the bit-fields are the same length.
6549    unsigned Bits1 = Field1->getBitWidthValue(C);
6550    unsigned Bits2 = Field2->getBitWidthValue(C);
6551
6552    if (Bits1 != Bits2)
6553      return false;
6554  }
6555
6556  return true;
6557}
6558
6559/// \brief Check if two standard-layout structs are layout-compatible.
6560/// (C++11 [class.mem] p17)
6561bool isLayoutCompatibleStruct(ASTContext &C,
6562                              RecordDecl *RD1,
6563                              RecordDecl *RD2) {
6564  // If both records are C++ classes, check that base classes match.
6565  if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
6566    // If one of records is a CXXRecordDecl we are in C++ mode,
6567    // thus the other one is a CXXRecordDecl, too.
6568    const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
6569    // Check number of base classes.
6570    if (D1CXX->getNumBases() != D2CXX->getNumBases())
6571      return false;
6572
6573    // Check the base classes.
6574    for (CXXRecordDecl::base_class_const_iterator
6575               Base1 = D1CXX->bases_begin(),
6576           BaseEnd1 = D1CXX->bases_end(),
6577              Base2 = D2CXX->bases_begin();
6578         Base1 != BaseEnd1;
6579         ++Base1, ++Base2) {
6580      if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
6581        return false;
6582    }
6583  } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
6584    // If only RD2 is a C++ class, it should have zero base classes.
6585    if (D2CXX->getNumBases() > 0)
6586      return false;
6587  }
6588
6589  // Check the fields.
6590  RecordDecl::field_iterator Field2 = RD2->field_begin(),
6591                             Field2End = RD2->field_end(),
6592                             Field1 = RD1->field_begin(),
6593                             Field1End = RD1->field_end();
6594  for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
6595    if (!isLayoutCompatible(C, *Field1, *Field2))
6596      return false;
6597  }
6598  if (Field1 != Field1End || Field2 != Field2End)
6599    return false;
6600
6601  return true;
6602}
6603
6604/// \brief Check if two standard-layout unions are layout-compatible.
6605/// (C++11 [class.mem] p18)
6606bool isLayoutCompatibleUnion(ASTContext &C,
6607                             RecordDecl *RD1,
6608                             RecordDecl *RD2) {
6609  llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
6610  for (RecordDecl::field_iterator Field2 = RD2->field_begin(),
6611                                  Field2End = RD2->field_end();
6612       Field2 != Field2End; ++Field2) {
6613    UnmatchedFields.insert(*Field2);
6614  }
6615
6616  for (RecordDecl::field_iterator Field1 = RD1->field_begin(),
6617                                  Field1End = RD1->field_end();
6618       Field1 != Field1End; ++Field1) {
6619    llvm::SmallPtrSet<FieldDecl *, 8>::iterator
6620        I = UnmatchedFields.begin(),
6621        E = UnmatchedFields.end();
6622
6623    for ( ; I != E; ++I) {
6624      if (isLayoutCompatible(C, *Field1, *I)) {
6625        bool Result = UnmatchedFields.erase(*I);
6626        (void) Result;
6627        assert(Result);
6628        break;
6629      }
6630    }
6631    if (I == E)
6632      return false;
6633  }
6634
6635  return UnmatchedFields.empty();
6636}
6637
6638bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
6639  if (RD1->isUnion() != RD2->isUnion())
6640    return false;
6641
6642  if (RD1->isUnion())
6643    return isLayoutCompatibleUnion(C, RD1, RD2);
6644  else
6645    return isLayoutCompatibleStruct(C, RD1, RD2);
6646}
6647
6648/// \brief Check if two types are layout-compatible in C++11 sense.
6649bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
6650  if (T1.isNull() || T2.isNull())
6651    return false;
6652
6653  // C++11 [basic.types] p11:
6654  // If two types T1 and T2 are the same type, then T1 and T2 are
6655  // layout-compatible types.
6656  if (C.hasSameType(T1, T2))
6657    return true;
6658
6659  T1 = T1.getCanonicalType().getUnqualifiedType();
6660  T2 = T2.getCanonicalType().getUnqualifiedType();
6661
6662  const Type::TypeClass TC1 = T1->getTypeClass();
6663  const Type::TypeClass TC2 = T2->getTypeClass();
6664
6665  if (TC1 != TC2)
6666    return false;
6667
6668  if (TC1 == Type::Enum) {
6669    return isLayoutCompatible(C,
6670                              cast<EnumType>(T1)->getDecl(),
6671                              cast<EnumType>(T2)->getDecl());
6672  } else if (TC1 == Type::Record) {
6673    if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
6674      return false;
6675
6676    return isLayoutCompatible(C,
6677                              cast<RecordType>(T1)->getDecl(),
6678                              cast<RecordType>(T2)->getDecl());
6679  }
6680
6681  return false;
6682}
6683}
6684
6685//===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
6686
6687namespace {
6688/// \brief Given a type tag expression find the type tag itself.
6689///
6690/// \param TypeExpr Type tag expression, as it appears in user's code.
6691///
6692/// \param VD Declaration of an identifier that appears in a type tag.
6693///
6694/// \param MagicValue Type tag magic value.
6695bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
6696                     const ValueDecl **VD, uint64_t *MagicValue) {
6697  while(true) {
6698    if (!TypeExpr)
6699      return false;
6700
6701    TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
6702
6703    switch (TypeExpr->getStmtClass()) {
6704    case Stmt::UnaryOperatorClass: {
6705      const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
6706      if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
6707        TypeExpr = UO->getSubExpr();
6708        continue;
6709      }
6710      return false;
6711    }
6712
6713    case Stmt::DeclRefExprClass: {
6714      const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
6715      *VD = DRE->getDecl();
6716      return true;
6717    }
6718
6719    case Stmt::IntegerLiteralClass: {
6720      const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
6721      llvm::APInt MagicValueAPInt = IL->getValue();
6722      if (MagicValueAPInt.getActiveBits() <= 64) {
6723        *MagicValue = MagicValueAPInt.getZExtValue();
6724        return true;
6725      } else
6726        return false;
6727    }
6728
6729    case Stmt::BinaryConditionalOperatorClass:
6730    case Stmt::ConditionalOperatorClass: {
6731      const AbstractConditionalOperator *ACO =
6732          cast<AbstractConditionalOperator>(TypeExpr);
6733      bool Result;
6734      if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
6735        if (Result)
6736          TypeExpr = ACO->getTrueExpr();
6737        else
6738          TypeExpr = ACO->getFalseExpr();
6739        continue;
6740      }
6741      return false;
6742    }
6743
6744    case Stmt::BinaryOperatorClass: {
6745      const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
6746      if (BO->getOpcode() == BO_Comma) {
6747        TypeExpr = BO->getRHS();
6748        continue;
6749      }
6750      return false;
6751    }
6752
6753    default:
6754      return false;
6755    }
6756  }
6757}
6758
6759/// \brief Retrieve the C type corresponding to type tag TypeExpr.
6760///
6761/// \param TypeExpr Expression that specifies a type tag.
6762///
6763/// \param MagicValues Registered magic values.
6764///
6765/// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
6766///        kind.
6767///
6768/// \param TypeInfo Information about the corresponding C type.
6769///
6770/// \returns true if the corresponding C type was found.
6771bool GetMatchingCType(
6772        const IdentifierInfo *ArgumentKind,
6773        const Expr *TypeExpr, const ASTContext &Ctx,
6774        const llvm::DenseMap<Sema::TypeTagMagicValue,
6775                             Sema::TypeTagData> *MagicValues,
6776        bool &FoundWrongKind,
6777        Sema::TypeTagData &TypeInfo) {
6778  FoundWrongKind = false;
6779
6780  // Variable declaration that has type_tag_for_datatype attribute.
6781  const ValueDecl *VD = NULL;
6782
6783  uint64_t MagicValue;
6784
6785  if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
6786    return false;
6787
6788  if (VD) {
6789    for (specific_attr_iterator<TypeTagForDatatypeAttr>
6790             I = VD->specific_attr_begin<TypeTagForDatatypeAttr>(),
6791             E = VD->specific_attr_end<TypeTagForDatatypeAttr>();
6792         I != E; ++I) {
6793      if (I->getArgumentKind() != ArgumentKind) {
6794        FoundWrongKind = true;
6795        return false;
6796      }
6797      TypeInfo.Type = I->getMatchingCType();
6798      TypeInfo.LayoutCompatible = I->getLayoutCompatible();
6799      TypeInfo.MustBeNull = I->getMustBeNull();
6800      return true;
6801    }
6802    return false;
6803  }
6804
6805  if (!MagicValues)
6806    return false;
6807
6808  llvm::DenseMap<Sema::TypeTagMagicValue,
6809                 Sema::TypeTagData>::const_iterator I =
6810      MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
6811  if (I == MagicValues->end())
6812    return false;
6813
6814  TypeInfo = I->second;
6815  return true;
6816}
6817} // unnamed namespace
6818
6819void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
6820                                      uint64_t MagicValue, QualType Type,
6821                                      bool LayoutCompatible,
6822                                      bool MustBeNull) {
6823  if (!TypeTagForDatatypeMagicValues)
6824    TypeTagForDatatypeMagicValues.reset(
6825        new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
6826
6827  TypeTagMagicValue Magic(ArgumentKind, MagicValue);
6828  (*TypeTagForDatatypeMagicValues)[Magic] =
6829      TypeTagData(Type, LayoutCompatible, MustBeNull);
6830}
6831
6832namespace {
6833bool IsSameCharType(QualType T1, QualType T2) {
6834  const BuiltinType *BT1 = T1->getAs<BuiltinType>();
6835  if (!BT1)
6836    return false;
6837
6838  const BuiltinType *BT2 = T2->getAs<BuiltinType>();
6839  if (!BT2)
6840    return false;
6841
6842  BuiltinType::Kind T1Kind = BT1->getKind();
6843  BuiltinType::Kind T2Kind = BT2->getKind();
6844
6845  return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
6846         (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
6847         (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
6848         (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
6849}
6850} // unnamed namespace
6851
6852void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
6853                                    const Expr * const *ExprArgs) {
6854  const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
6855  bool IsPointerAttr = Attr->getIsPointer();
6856
6857  const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
6858  bool FoundWrongKind;
6859  TypeTagData TypeInfo;
6860  if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
6861                        TypeTagForDatatypeMagicValues.get(),
6862                        FoundWrongKind, TypeInfo)) {
6863    if (FoundWrongKind)
6864      Diag(TypeTagExpr->getExprLoc(),
6865           diag::warn_type_tag_for_datatype_wrong_kind)
6866        << TypeTagExpr->getSourceRange();
6867    return;
6868  }
6869
6870  const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
6871  if (IsPointerAttr) {
6872    // Skip implicit cast of pointer to `void *' (as a function argument).
6873    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
6874      if (ICE->getType()->isVoidPointerType() &&
6875          ICE->getCastKind() == CK_BitCast)
6876        ArgumentExpr = ICE->getSubExpr();
6877  }
6878  QualType ArgumentType = ArgumentExpr->getType();
6879
6880  // Passing a `void*' pointer shouldn't trigger a warning.
6881  if (IsPointerAttr && ArgumentType->isVoidPointerType())
6882    return;
6883
6884  if (TypeInfo.MustBeNull) {
6885    // Type tag with matching void type requires a null pointer.
6886    if (!ArgumentExpr->isNullPointerConstant(Context,
6887                                             Expr::NPC_ValueDependentIsNotNull)) {
6888      Diag(ArgumentExpr->getExprLoc(),
6889           diag::warn_type_safety_null_pointer_required)
6890          << ArgumentKind->getName()
6891          << ArgumentExpr->getSourceRange()
6892          << TypeTagExpr->getSourceRange();
6893    }
6894    return;
6895  }
6896
6897  QualType RequiredType = TypeInfo.Type;
6898  if (IsPointerAttr)
6899    RequiredType = Context.getPointerType(RequiredType);
6900
6901  bool mismatch = false;
6902  if (!TypeInfo.LayoutCompatible) {
6903    mismatch = !Context.hasSameType(ArgumentType, RequiredType);
6904
6905    // C++11 [basic.fundamental] p1:
6906    // Plain char, signed char, and unsigned char are three distinct types.
6907    //
6908    // But we treat plain `char' as equivalent to `signed char' or `unsigned
6909    // char' depending on the current char signedness mode.
6910    if (mismatch)
6911      if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
6912                                           RequiredType->getPointeeType())) ||
6913          (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
6914        mismatch = false;
6915  } else
6916    if (IsPointerAttr)
6917      mismatch = !isLayoutCompatible(Context,
6918                                     ArgumentType->getPointeeType(),
6919                                     RequiredType->getPointeeType());
6920    else
6921      mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
6922
6923  if (mismatch)
6924    Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
6925        << ArgumentType << ArgumentKind->getName()
6926        << TypeInfo.LayoutCompatible << RequiredType
6927        << ArgumentExpr->getSourceRange()
6928        << TypeTagExpr->getSourceRange();
6929}
6930