SemaChecking.cpp revision c8fa525b5b81eeb7a62294dd3218ca2a6ccf0a6a 
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::CheckPointerCall(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() && !Ty->isFunctionPointerType())
608    return false;
609
610  VariadicCallType CallType;
611  if (!Proto || !Proto->isVariadic()) {
612    CallType = VariadicDoesNotApply;
613  } else if (Ty->isBlockPointerType()) {
614    CallType = VariadicBlock;
615  } else { // Ty->isFunctionPointerType()
616    CallType = VariadicFunction;
617  }
618  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
619
620  checkCall(NDecl,
621            llvm::makeArrayRef<const Expr *>(TheCall->getArgs(),
622                                             TheCall->getNumArgs()),
623            NumProtoArgs, /*IsMemberFunction=*/false,
624            TheCall->getRParenLoc(),
625            TheCall->getCallee()->getSourceRange(), CallType);
626
627  return false;
628}
629
630ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
631                                         AtomicExpr::AtomicOp Op) {
632  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
633  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
634
635  // All these operations take one of the following forms:
636  enum {
637    // C    __c11_atomic_init(A *, C)
638    Init,
639    // C    __c11_atomic_load(A *, int)
640    Load,
641    // void __atomic_load(A *, CP, int)
642    Copy,
643    // C    __c11_atomic_add(A *, M, int)
644    Arithmetic,
645    // C    __atomic_exchange_n(A *, CP, int)
646    Xchg,
647    // void __atomic_exchange(A *, C *, CP, int)
648    GNUXchg,
649    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
650    C11CmpXchg,
651    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
652    GNUCmpXchg
653  } Form = Init;
654  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
655  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
656  // where:
657  //   C is an appropriate type,
658  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
659  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
660  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
661  //   the int parameters are for orderings.
662
663  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
664         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
665         && "need to update code for modified C11 atomics");
666  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
667               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
668  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
669             Op == AtomicExpr::AO__atomic_store_n ||
670             Op == AtomicExpr::AO__atomic_exchange_n ||
671             Op == AtomicExpr::AO__atomic_compare_exchange_n;
672  bool IsAddSub = false;
673
674  switch (Op) {
675  case AtomicExpr::AO__c11_atomic_init:
676    Form = Init;
677    break;
678
679  case AtomicExpr::AO__c11_atomic_load:
680  case AtomicExpr::AO__atomic_load_n:
681    Form = Load;
682    break;
683
684  case AtomicExpr::AO__c11_atomic_store:
685  case AtomicExpr::AO__atomic_load:
686  case AtomicExpr::AO__atomic_store:
687  case AtomicExpr::AO__atomic_store_n:
688    Form = Copy;
689    break;
690
691  case AtomicExpr::AO__c11_atomic_fetch_add:
692  case AtomicExpr::AO__c11_atomic_fetch_sub:
693  case AtomicExpr::AO__atomic_fetch_add:
694  case AtomicExpr::AO__atomic_fetch_sub:
695  case AtomicExpr::AO__atomic_add_fetch:
696  case AtomicExpr::AO__atomic_sub_fetch:
697    IsAddSub = true;
698    // Fall through.
699  case AtomicExpr::AO__c11_atomic_fetch_and:
700  case AtomicExpr::AO__c11_atomic_fetch_or:
701  case AtomicExpr::AO__c11_atomic_fetch_xor:
702  case AtomicExpr::AO__atomic_fetch_and:
703  case AtomicExpr::AO__atomic_fetch_or:
704  case AtomicExpr::AO__atomic_fetch_xor:
705  case AtomicExpr::AO__atomic_fetch_nand:
706  case AtomicExpr::AO__atomic_and_fetch:
707  case AtomicExpr::AO__atomic_or_fetch:
708  case AtomicExpr::AO__atomic_xor_fetch:
709  case AtomicExpr::AO__atomic_nand_fetch:
710    Form = Arithmetic;
711    break;
712
713  case AtomicExpr::AO__c11_atomic_exchange:
714  case AtomicExpr::AO__atomic_exchange_n:
715    Form = Xchg;
716    break;
717
718  case AtomicExpr::AO__atomic_exchange:
719    Form = GNUXchg;
720    break;
721
722  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
723  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
724    Form = C11CmpXchg;
725    break;
726
727  case AtomicExpr::AO__atomic_compare_exchange:
728  case AtomicExpr::AO__atomic_compare_exchange_n:
729    Form = GNUCmpXchg;
730    break;
731  }
732
733  // Check we have the right number of arguments.
734  if (TheCall->getNumArgs() < NumArgs[Form]) {
735    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
736      << 0 << NumArgs[Form] << TheCall->getNumArgs()
737      << TheCall->getCallee()->getSourceRange();
738    return ExprError();
739  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
740    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
741         diag::err_typecheck_call_too_many_args)
742      << 0 << NumArgs[Form] << TheCall->getNumArgs()
743      << TheCall->getCallee()->getSourceRange();
744    return ExprError();
745  }
746
747  // Inspect the first argument of the atomic operation.
748  Expr *Ptr = TheCall->getArg(0);
749  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
750  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
751  if (!pointerType) {
752    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
753      << Ptr->getType() << Ptr->getSourceRange();
754    return ExprError();
755  }
756
757  // For a __c11 builtin, this should be a pointer to an _Atomic type.
758  QualType AtomTy = pointerType->getPointeeType(); // 'A'
759  QualType ValType = AtomTy; // 'C'
760  if (IsC11) {
761    if (!AtomTy->isAtomicType()) {
762      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
763        << Ptr->getType() << Ptr->getSourceRange();
764      return ExprError();
765    }
766    if (AtomTy.isConstQualified()) {
767      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
768        << Ptr->getType() << Ptr->getSourceRange();
769      return ExprError();
770    }
771    ValType = AtomTy->getAs<AtomicType>()->getValueType();
772  }
773
774  // For an arithmetic operation, the implied arithmetic must be well-formed.
775  if (Form == Arithmetic) {
776    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
777    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
778      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
779        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
780      return ExprError();
781    }
782    if (!IsAddSub && !ValType->isIntegerType()) {
783      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
784        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
785      return ExprError();
786    }
787  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
788    // For __atomic_*_n operations, the value type must be a scalar integral or
789    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
790    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
791      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
792    return ExprError();
793  }
794
795  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
796    // For GNU atomics, require a trivially-copyable type. This is not part of
797    // the GNU atomics specification, but we enforce it for sanity.
798    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
799      << Ptr->getType() << Ptr->getSourceRange();
800    return ExprError();
801  }
802
803  // FIXME: For any builtin other than a load, the ValType must not be
804  // const-qualified.
805
806  switch (ValType.getObjCLifetime()) {
807  case Qualifiers::OCL_None:
808  case Qualifiers::OCL_ExplicitNone:
809    // okay
810    break;
811
812  case Qualifiers::OCL_Weak:
813  case Qualifiers::OCL_Strong:
814  case Qualifiers::OCL_Autoreleasing:
815    // FIXME: Can this happen? By this point, ValType should be known
816    // to be trivially copyable.
817    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
818      << ValType << Ptr->getSourceRange();
819    return ExprError();
820  }
821
822  QualType ResultType = ValType;
823  if (Form == Copy || Form == GNUXchg || Form == Init)
824    ResultType = Context.VoidTy;
825  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
826    ResultType = Context.BoolTy;
827
828  // The type of a parameter passed 'by value'. In the GNU atomics, such
829  // arguments are actually passed as pointers.
830  QualType ByValType = ValType; // 'CP'
831  if (!IsC11 && !IsN)
832    ByValType = Ptr->getType();
833
834  // The first argument --- the pointer --- has a fixed type; we
835  // deduce the types of the rest of the arguments accordingly.  Walk
836  // the remaining arguments, converting them to the deduced value type.
837  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
838    QualType Ty;
839    if (i < NumVals[Form] + 1) {
840      switch (i) {
841      case 1:
842        // The second argument is the non-atomic operand. For arithmetic, this
843        // is always passed by value, and for a compare_exchange it is always
844        // passed by address. For the rest, GNU uses by-address and C11 uses
845        // by-value.
846        assert(Form != Load);
847        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
848          Ty = ValType;
849        else if (Form == Copy || Form == Xchg)
850          Ty = ByValType;
851        else if (Form == Arithmetic)
852          Ty = Context.getPointerDiffType();
853        else
854          Ty = Context.getPointerType(ValType.getUnqualifiedType());
855        break;
856      case 2:
857        // The third argument to compare_exchange / GNU exchange is a
858        // (pointer to a) desired value.
859        Ty = ByValType;
860        break;
861      case 3:
862        // The fourth argument to GNU compare_exchange is a 'weak' flag.
863        Ty = Context.BoolTy;
864        break;
865      }
866    } else {
867      // The order(s) are always converted to int.
868      Ty = Context.IntTy;
869    }
870
871    InitializedEntity Entity =
872        InitializedEntity::InitializeParameter(Context, Ty, false);
873    ExprResult Arg = TheCall->getArg(i);
874    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
875    if (Arg.isInvalid())
876      return true;
877    TheCall->setArg(i, Arg.get());
878  }
879
880  // Permute the arguments into a 'consistent' order.
881  SmallVector<Expr*, 5> SubExprs;
882  SubExprs.push_back(Ptr);
883  switch (Form) {
884  case Init:
885    // Note, AtomicExpr::getVal1() has a special case for this atomic.
886    SubExprs.push_back(TheCall->getArg(1)); // Val1
887    break;
888  case Load:
889    SubExprs.push_back(TheCall->getArg(1)); // Order
890    break;
891  case Copy:
892  case Arithmetic:
893  case Xchg:
894    SubExprs.push_back(TheCall->getArg(2)); // Order
895    SubExprs.push_back(TheCall->getArg(1)); // Val1
896    break;
897  case GNUXchg:
898    // Note, AtomicExpr::getVal2() has a special case for this atomic.
899    SubExprs.push_back(TheCall->getArg(3)); // Order
900    SubExprs.push_back(TheCall->getArg(1)); // Val1
901    SubExprs.push_back(TheCall->getArg(2)); // Val2
902    break;
903  case C11CmpXchg:
904    SubExprs.push_back(TheCall->getArg(3)); // Order
905    SubExprs.push_back(TheCall->getArg(1)); // Val1
906    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
907    SubExprs.push_back(TheCall->getArg(2)); // Val2
908    break;
909  case GNUCmpXchg:
910    SubExprs.push_back(TheCall->getArg(4)); // Order
911    SubExprs.push_back(TheCall->getArg(1)); // Val1
912    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
913    SubExprs.push_back(TheCall->getArg(2)); // Val2
914    SubExprs.push_back(TheCall->getArg(3)); // Weak
915    break;
916  }
917
918  AtomicExpr *AE = new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
919                                            SubExprs, ResultType, Op,
920                                            TheCall->getRParenLoc());
921
922  if ((Op == AtomicExpr::AO__c11_atomic_load ||
923       (Op == AtomicExpr::AO__c11_atomic_store)) &&
924      Context.AtomicUsesUnsupportedLibcall(AE))
925    Diag(AE->getLocStart(), diag::err_atomic_load_store_uses_lib) <<
926    ((Op == AtomicExpr::AO__c11_atomic_load) ? 0 : 1);
927
928  return Owned(AE);
929}
930
931
932/// checkBuiltinArgument - Given a call to a builtin function, perform
933/// normal type-checking on the given argument, updating the call in
934/// place.  This is useful when a builtin function requires custom
935/// type-checking for some of its arguments but not necessarily all of
936/// them.
937///
938/// Returns true on error.
939static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
940  FunctionDecl *Fn = E->getDirectCallee();
941  assert(Fn && "builtin call without direct callee!");
942
943  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
944  InitializedEntity Entity =
945    InitializedEntity::InitializeParameter(S.Context, Param);
946
947  ExprResult Arg = E->getArg(0);
948  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
949  if (Arg.isInvalid())
950    return true;
951
952  E->setArg(ArgIndex, Arg.take());
953  return false;
954}
955
956/// SemaBuiltinAtomicOverloaded - We have a call to a function like
957/// __sync_fetch_and_add, which is an overloaded function based on the pointer
958/// type of its first argument.  The main ActOnCallExpr routines have already
959/// promoted the types of arguments because all of these calls are prototyped as
960/// void(...).
961///
962/// This function goes through and does final semantic checking for these
963/// builtins,
964ExprResult
965Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
966  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
967  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
968  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
969
970  // Ensure that we have at least one argument to do type inference from.
971  if (TheCall->getNumArgs() < 1) {
972    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
973      << 0 << 1 << TheCall->getNumArgs()
974      << TheCall->getCallee()->getSourceRange();
975    return ExprError();
976  }
977
978  // Inspect the first argument of the atomic builtin.  This should always be
979  // a pointer type, whose element is an integral scalar or pointer type.
980  // Because it is a pointer type, we don't have to worry about any implicit
981  // casts here.
982  // FIXME: We don't allow floating point scalars as input.
983  Expr *FirstArg = TheCall->getArg(0);
984  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
985  if (FirstArgResult.isInvalid())
986    return ExprError();
987  FirstArg = FirstArgResult.take();
988  TheCall->setArg(0, FirstArg);
989
990  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
991  if (!pointerType) {
992    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
993      << FirstArg->getType() << FirstArg->getSourceRange();
994    return ExprError();
995  }
996
997  QualType ValType = pointerType->getPointeeType();
998  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
999      !ValType->isBlockPointerType()) {
1000    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
1001      << FirstArg->getType() << FirstArg->getSourceRange();
1002    return ExprError();
1003  }
1004
1005  switch (ValType.getObjCLifetime()) {
1006  case Qualifiers::OCL_None:
1007  case Qualifiers::OCL_ExplicitNone:
1008    // okay
1009    break;
1010
1011  case Qualifiers::OCL_Weak:
1012  case Qualifiers::OCL_Strong:
1013  case Qualifiers::OCL_Autoreleasing:
1014    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1015      << ValType << FirstArg->getSourceRange();
1016    return ExprError();
1017  }
1018
1019  // Strip any qualifiers off ValType.
1020  ValType = ValType.getUnqualifiedType();
1021
1022  // The majority of builtins return a value, but a few have special return
1023  // types, so allow them to override appropriately below.
1024  QualType ResultType = ValType;
1025
1026  // We need to figure out which concrete builtin this maps onto.  For example,
1027  // __sync_fetch_and_add with a 2 byte object turns into
1028  // __sync_fetch_and_add_2.
1029#define BUILTIN_ROW(x) \
1030  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
1031    Builtin::BI##x##_8, Builtin::BI##x##_16 }
1032
1033  static const unsigned BuiltinIndices[][5] = {
1034    BUILTIN_ROW(__sync_fetch_and_add),
1035    BUILTIN_ROW(__sync_fetch_and_sub),
1036    BUILTIN_ROW(__sync_fetch_and_or),
1037    BUILTIN_ROW(__sync_fetch_and_and),
1038    BUILTIN_ROW(__sync_fetch_and_xor),
1039
1040    BUILTIN_ROW(__sync_add_and_fetch),
1041    BUILTIN_ROW(__sync_sub_and_fetch),
1042    BUILTIN_ROW(__sync_and_and_fetch),
1043    BUILTIN_ROW(__sync_or_and_fetch),
1044    BUILTIN_ROW(__sync_xor_and_fetch),
1045
1046    BUILTIN_ROW(__sync_val_compare_and_swap),
1047    BUILTIN_ROW(__sync_bool_compare_and_swap),
1048    BUILTIN_ROW(__sync_lock_test_and_set),
1049    BUILTIN_ROW(__sync_lock_release),
1050    BUILTIN_ROW(__sync_swap)
1051  };
1052#undef BUILTIN_ROW
1053
1054  // Determine the index of the size.
1055  unsigned SizeIndex;
1056  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1057  case 1: SizeIndex = 0; break;
1058  case 2: SizeIndex = 1; break;
1059  case 4: SizeIndex = 2; break;
1060  case 8: SizeIndex = 3; break;
1061  case 16: SizeIndex = 4; break;
1062  default:
1063    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1064      << FirstArg->getType() << FirstArg->getSourceRange();
1065    return ExprError();
1066  }
1067
1068  // Each of these builtins has one pointer argument, followed by some number of
1069  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1070  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1071  // as the number of fixed args.
1072  unsigned BuiltinID = FDecl->getBuiltinID();
1073  unsigned BuiltinIndex, NumFixed = 1;
1074  switch (BuiltinID) {
1075  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1076  case Builtin::BI__sync_fetch_and_add:
1077  case Builtin::BI__sync_fetch_and_add_1:
1078  case Builtin::BI__sync_fetch_and_add_2:
1079  case Builtin::BI__sync_fetch_and_add_4:
1080  case Builtin::BI__sync_fetch_and_add_8:
1081  case Builtin::BI__sync_fetch_and_add_16:
1082    BuiltinIndex = 0;
1083    break;
1084
1085  case Builtin::BI__sync_fetch_and_sub:
1086  case Builtin::BI__sync_fetch_and_sub_1:
1087  case Builtin::BI__sync_fetch_and_sub_2:
1088  case Builtin::BI__sync_fetch_and_sub_4:
1089  case Builtin::BI__sync_fetch_and_sub_8:
1090  case Builtin::BI__sync_fetch_and_sub_16:
1091    BuiltinIndex = 1;
1092    break;
1093
1094  case Builtin::BI__sync_fetch_and_or:
1095  case Builtin::BI__sync_fetch_and_or_1:
1096  case Builtin::BI__sync_fetch_and_or_2:
1097  case Builtin::BI__sync_fetch_and_or_4:
1098  case Builtin::BI__sync_fetch_and_or_8:
1099  case Builtin::BI__sync_fetch_and_or_16:
1100    BuiltinIndex = 2;
1101    break;
1102
1103  case Builtin::BI__sync_fetch_and_and:
1104  case Builtin::BI__sync_fetch_and_and_1:
1105  case Builtin::BI__sync_fetch_and_and_2:
1106  case Builtin::BI__sync_fetch_and_and_4:
1107  case Builtin::BI__sync_fetch_and_and_8:
1108  case Builtin::BI__sync_fetch_and_and_16:
1109    BuiltinIndex = 3;
1110    break;
1111
1112  case Builtin::BI__sync_fetch_and_xor:
1113  case Builtin::BI__sync_fetch_and_xor_1:
1114  case Builtin::BI__sync_fetch_and_xor_2:
1115  case Builtin::BI__sync_fetch_and_xor_4:
1116  case Builtin::BI__sync_fetch_and_xor_8:
1117  case Builtin::BI__sync_fetch_and_xor_16:
1118    BuiltinIndex = 4;
1119    break;
1120
1121  case Builtin::BI__sync_add_and_fetch:
1122  case Builtin::BI__sync_add_and_fetch_1:
1123  case Builtin::BI__sync_add_and_fetch_2:
1124  case Builtin::BI__sync_add_and_fetch_4:
1125  case Builtin::BI__sync_add_and_fetch_8:
1126  case Builtin::BI__sync_add_and_fetch_16:
1127    BuiltinIndex = 5;
1128    break;
1129
1130  case Builtin::BI__sync_sub_and_fetch:
1131  case Builtin::BI__sync_sub_and_fetch_1:
1132  case Builtin::BI__sync_sub_and_fetch_2:
1133  case Builtin::BI__sync_sub_and_fetch_4:
1134  case Builtin::BI__sync_sub_and_fetch_8:
1135  case Builtin::BI__sync_sub_and_fetch_16:
1136    BuiltinIndex = 6;
1137    break;
1138
1139  case Builtin::BI__sync_and_and_fetch:
1140  case Builtin::BI__sync_and_and_fetch_1:
1141  case Builtin::BI__sync_and_and_fetch_2:
1142  case Builtin::BI__sync_and_and_fetch_4:
1143  case Builtin::BI__sync_and_and_fetch_8:
1144  case Builtin::BI__sync_and_and_fetch_16:
1145    BuiltinIndex = 7;
1146    break;
1147
1148  case Builtin::BI__sync_or_and_fetch:
1149  case Builtin::BI__sync_or_and_fetch_1:
1150  case Builtin::BI__sync_or_and_fetch_2:
1151  case Builtin::BI__sync_or_and_fetch_4:
1152  case Builtin::BI__sync_or_and_fetch_8:
1153  case Builtin::BI__sync_or_and_fetch_16:
1154    BuiltinIndex = 8;
1155    break;
1156
1157  case Builtin::BI__sync_xor_and_fetch:
1158  case Builtin::BI__sync_xor_and_fetch_1:
1159  case Builtin::BI__sync_xor_and_fetch_2:
1160  case Builtin::BI__sync_xor_and_fetch_4:
1161  case Builtin::BI__sync_xor_and_fetch_8:
1162  case Builtin::BI__sync_xor_and_fetch_16:
1163    BuiltinIndex = 9;
1164    break;
1165
1166  case Builtin::BI__sync_val_compare_and_swap:
1167  case Builtin::BI__sync_val_compare_and_swap_1:
1168  case Builtin::BI__sync_val_compare_and_swap_2:
1169  case Builtin::BI__sync_val_compare_and_swap_4:
1170  case Builtin::BI__sync_val_compare_and_swap_8:
1171  case Builtin::BI__sync_val_compare_and_swap_16:
1172    BuiltinIndex = 10;
1173    NumFixed = 2;
1174    break;
1175
1176  case Builtin::BI__sync_bool_compare_and_swap:
1177  case Builtin::BI__sync_bool_compare_and_swap_1:
1178  case Builtin::BI__sync_bool_compare_and_swap_2:
1179  case Builtin::BI__sync_bool_compare_and_swap_4:
1180  case Builtin::BI__sync_bool_compare_and_swap_8:
1181  case Builtin::BI__sync_bool_compare_and_swap_16:
1182    BuiltinIndex = 11;
1183    NumFixed = 2;
1184    ResultType = Context.BoolTy;
1185    break;
1186
1187  case Builtin::BI__sync_lock_test_and_set:
1188  case Builtin::BI__sync_lock_test_and_set_1:
1189  case Builtin::BI__sync_lock_test_and_set_2:
1190  case Builtin::BI__sync_lock_test_and_set_4:
1191  case Builtin::BI__sync_lock_test_and_set_8:
1192  case Builtin::BI__sync_lock_test_and_set_16:
1193    BuiltinIndex = 12;
1194    break;
1195
1196  case Builtin::BI__sync_lock_release:
1197  case Builtin::BI__sync_lock_release_1:
1198  case Builtin::BI__sync_lock_release_2:
1199  case Builtin::BI__sync_lock_release_4:
1200  case Builtin::BI__sync_lock_release_8:
1201  case Builtin::BI__sync_lock_release_16:
1202    BuiltinIndex = 13;
1203    NumFixed = 0;
1204    ResultType = Context.VoidTy;
1205    break;
1206
1207  case Builtin::BI__sync_swap:
1208  case Builtin::BI__sync_swap_1:
1209  case Builtin::BI__sync_swap_2:
1210  case Builtin::BI__sync_swap_4:
1211  case Builtin::BI__sync_swap_8:
1212  case Builtin::BI__sync_swap_16:
1213    BuiltinIndex = 14;
1214    break;
1215  }
1216
1217  // Now that we know how many fixed arguments we expect, first check that we
1218  // have at least that many.
1219  if (TheCall->getNumArgs() < 1+NumFixed) {
1220    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1221      << 0 << 1+NumFixed << TheCall->getNumArgs()
1222      << TheCall->getCallee()->getSourceRange();
1223    return ExprError();
1224  }
1225
1226  // Get the decl for the concrete builtin from this, we can tell what the
1227  // concrete integer type we should convert to is.
1228  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1229  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1230  FunctionDecl *NewBuiltinDecl;
1231  if (NewBuiltinID == BuiltinID)
1232    NewBuiltinDecl = FDecl;
1233  else {
1234    // Perform builtin lookup to avoid redeclaring it.
1235    DeclarationName DN(&Context.Idents.get(NewBuiltinName));
1236    LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
1237    LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
1238    assert(Res.getFoundDecl());
1239    NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
1240    if (NewBuiltinDecl == 0)
1241      return ExprError();
1242  }
1243
1244  // The first argument --- the pointer --- has a fixed type; we
1245  // deduce the types of the rest of the arguments accordingly.  Walk
1246  // the remaining arguments, converting them to the deduced value type.
1247  for (unsigned i = 0; i != NumFixed; ++i) {
1248    ExprResult Arg = TheCall->getArg(i+1);
1249
1250    // GCC does an implicit conversion to the pointer or integer ValType.  This
1251    // can fail in some cases (1i -> int**), check for this error case now.
1252    // Initialize the argument.
1253    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1254                                                   ValType, /*consume*/ false);
1255    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1256    if (Arg.isInvalid())
1257      return ExprError();
1258
1259    // Okay, we have something that *can* be converted to the right type.  Check
1260    // to see if there is a potentially weird extension going on here.  This can
1261    // happen when you do an atomic operation on something like an char* and
1262    // pass in 42.  The 42 gets converted to char.  This is even more strange
1263    // for things like 45.123 -> char, etc.
1264    // FIXME: Do this check.
1265    TheCall->setArg(i+1, Arg.take());
1266  }
1267
1268  ASTContext& Context = this->getASTContext();
1269
1270  // Create a new DeclRefExpr to refer to the new decl.
1271  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1272      Context,
1273      DRE->getQualifierLoc(),
1274      SourceLocation(),
1275      NewBuiltinDecl,
1276      /*enclosing*/ false,
1277      DRE->getLocation(),
1278      Context.BuiltinFnTy,
1279      DRE->getValueKind());
1280
1281  // Set the callee in the CallExpr.
1282  // FIXME: This loses syntactic information.
1283  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
1284  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
1285                                              CK_BuiltinFnToFnPtr);
1286  TheCall->setCallee(PromotedCall.take());
1287
1288  // Change the result type of the call to match the original value type. This
1289  // is arbitrary, but the codegen for these builtins ins design to handle it
1290  // gracefully.
1291  TheCall->setType(ResultType);
1292
1293  return TheCallResult;
1294}
1295
1296/// CheckObjCString - Checks that the argument to the builtin
1297/// CFString constructor is correct
1298/// Note: It might also make sense to do the UTF-16 conversion here (would
1299/// simplify the backend).
1300bool Sema::CheckObjCString(Expr *Arg) {
1301  Arg = Arg->IgnoreParenCasts();
1302  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1303
1304  if (!Literal || !Literal->isAscii()) {
1305    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1306      << Arg->getSourceRange();
1307    return true;
1308  }
1309
1310  if (Literal->containsNonAsciiOrNull()) {
1311    StringRef String = Literal->getString();
1312    unsigned NumBytes = String.size();
1313    SmallVector<UTF16, 128> ToBuf(NumBytes);
1314    const UTF8 *FromPtr = (const UTF8 *)String.data();
1315    UTF16 *ToPtr = &ToBuf[0];
1316
1317    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1318                                                 &ToPtr, ToPtr + NumBytes,
1319                                                 strictConversion);
1320    // Check for conversion failure.
1321    if (Result != conversionOK)
1322      Diag(Arg->getLocStart(),
1323           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1324  }
1325  return false;
1326}
1327
1328/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1329/// Emit an error and return true on failure, return false on success.
1330bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1331  Expr *Fn = TheCall->getCallee();
1332  if (TheCall->getNumArgs() > 2) {
1333    Diag(TheCall->getArg(2)->getLocStart(),
1334         diag::err_typecheck_call_too_many_args)
1335      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1336      << Fn->getSourceRange()
1337      << SourceRange(TheCall->getArg(2)->getLocStart(),
1338                     (*(TheCall->arg_end()-1))->getLocEnd());
1339    return true;
1340  }
1341
1342  if (TheCall->getNumArgs() < 2) {
1343    return Diag(TheCall->getLocEnd(),
1344      diag::err_typecheck_call_too_few_args_at_least)
1345      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1346  }
1347
1348  // Type-check the first argument normally.
1349  if (checkBuiltinArgument(*this, TheCall, 0))
1350    return true;
1351
1352  // Determine whether the current function is variadic or not.
1353  BlockScopeInfo *CurBlock = getCurBlock();
1354  bool isVariadic;
1355  if (CurBlock)
1356    isVariadic = CurBlock->TheDecl->isVariadic();
1357  else if (FunctionDecl *FD = getCurFunctionDecl())
1358    isVariadic = FD->isVariadic();
1359  else
1360    isVariadic = getCurMethodDecl()->isVariadic();
1361
1362  if (!isVariadic) {
1363    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1364    return true;
1365  }
1366
1367  // Verify that the second argument to the builtin is the last argument of the
1368  // current function or method.
1369  bool SecondArgIsLastNamedArgument = false;
1370  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1371
1372  // These are valid if SecondArgIsLastNamedArgument is false after the next
1373  // block.
1374  QualType Type;
1375  SourceLocation ParamLoc;
1376
1377  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1378    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1379      // FIXME: This isn't correct for methods (results in bogus warning).
1380      // Get the last formal in the current function.
1381      const ParmVarDecl *LastArg;
1382      if (CurBlock)
1383        LastArg = *(CurBlock->TheDecl->param_end()-1);
1384      else if (FunctionDecl *FD = getCurFunctionDecl())
1385        LastArg = *(FD->param_end()-1);
1386      else
1387        LastArg = *(getCurMethodDecl()->param_end()-1);
1388      SecondArgIsLastNamedArgument = PV == LastArg;
1389
1390      Type = PV->getType();
1391      ParamLoc = PV->getLocation();
1392    }
1393  }
1394
1395  if (!SecondArgIsLastNamedArgument)
1396    Diag(TheCall->getArg(1)->getLocStart(),
1397         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1398  else if (Type->isReferenceType()) {
1399    Diag(Arg->getLocStart(),
1400         diag::warn_va_start_of_reference_type_is_undefined);
1401    Diag(ParamLoc, diag::note_parameter_type) << Type;
1402  }
1403
1404  return false;
1405}
1406
1407/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1408/// friends.  This is declared to take (...), so we have to check everything.
1409bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1410  if (TheCall->getNumArgs() < 2)
1411    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1412      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1413  if (TheCall->getNumArgs() > 2)
1414    return Diag(TheCall->getArg(2)->getLocStart(),
1415                diag::err_typecheck_call_too_many_args)
1416      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1417      << SourceRange(TheCall->getArg(2)->getLocStart(),
1418                     (*(TheCall->arg_end()-1))->getLocEnd());
1419
1420  ExprResult OrigArg0 = TheCall->getArg(0);
1421  ExprResult OrigArg1 = TheCall->getArg(1);
1422
1423  // Do standard promotions between the two arguments, returning their common
1424  // type.
1425  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1426  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1427    return true;
1428
1429  // Make sure any conversions are pushed back into the call; this is
1430  // type safe since unordered compare builtins are declared as "_Bool
1431  // foo(...)".
1432  TheCall->setArg(0, OrigArg0.get());
1433  TheCall->setArg(1, OrigArg1.get());
1434
1435  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1436    return false;
1437
1438  // If the common type isn't a real floating type, then the arguments were
1439  // invalid for this operation.
1440  if (Res.isNull() || !Res->isRealFloatingType())
1441    return Diag(OrigArg0.get()->getLocStart(),
1442                diag::err_typecheck_call_invalid_ordered_compare)
1443      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1444      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1445
1446  return false;
1447}
1448
1449/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1450/// __builtin_isnan and friends.  This is declared to take (...), so we have
1451/// to check everything. We expect the last argument to be a floating point
1452/// value.
1453bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1454  if (TheCall->getNumArgs() < NumArgs)
1455    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1456      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1457  if (TheCall->getNumArgs() > NumArgs)
1458    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1459                diag::err_typecheck_call_too_many_args)
1460      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1461      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1462                     (*(TheCall->arg_end()-1))->getLocEnd());
1463
1464  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1465
1466  if (OrigArg->isTypeDependent())
1467    return false;
1468
1469  // This operation requires a non-_Complex floating-point number.
1470  if (!OrigArg->getType()->isRealFloatingType())
1471    return Diag(OrigArg->getLocStart(),
1472                diag::err_typecheck_call_invalid_unary_fp)
1473      << OrigArg->getType() << OrigArg->getSourceRange();
1474
1475  // If this is an implicit conversion from float -> double, remove it.
1476  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1477    Expr *CastArg = Cast->getSubExpr();
1478    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1479      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1480             "promotion from float to double is the only expected cast here");
1481      Cast->setSubExpr(0);
1482      TheCall->setArg(NumArgs-1, CastArg);
1483    }
1484  }
1485
1486  return false;
1487}
1488
1489/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1490// This is declared to take (...), so we have to check everything.
1491ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1492  if (TheCall->getNumArgs() < 2)
1493    return ExprError(Diag(TheCall->getLocEnd(),
1494                          diag::err_typecheck_call_too_few_args_at_least)
1495      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1496      << TheCall->getSourceRange());
1497
1498  // Determine which of the following types of shufflevector we're checking:
1499  // 1) unary, vector mask: (lhs, mask)
1500  // 2) binary, vector mask: (lhs, rhs, mask)
1501  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1502  QualType resType = TheCall->getArg(0)->getType();
1503  unsigned numElements = 0;
1504
1505  if (!TheCall->getArg(0)->isTypeDependent() &&
1506      !TheCall->getArg(1)->isTypeDependent()) {
1507    QualType LHSType = TheCall->getArg(0)->getType();
1508    QualType RHSType = TheCall->getArg(1)->getType();
1509
1510    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1511      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1512        << SourceRange(TheCall->getArg(0)->getLocStart(),
1513                       TheCall->getArg(1)->getLocEnd());
1514      return ExprError();
1515    }
1516
1517    numElements = LHSType->getAs<VectorType>()->getNumElements();
1518    unsigned numResElements = TheCall->getNumArgs() - 2;
1519
1520    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1521    // with mask.  If so, verify that RHS is an integer vector type with the
1522    // same number of elts as lhs.
1523    if (TheCall->getNumArgs() == 2) {
1524      if (!RHSType->hasIntegerRepresentation() ||
1525          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1526        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1527          << SourceRange(TheCall->getArg(1)->getLocStart(),
1528                         TheCall->getArg(1)->getLocEnd());
1529      numResElements = numElements;
1530    }
1531    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1532      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1533        << SourceRange(TheCall->getArg(0)->getLocStart(),
1534                       TheCall->getArg(1)->getLocEnd());
1535      return ExprError();
1536    } else if (numElements != numResElements) {
1537      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1538      resType = Context.getVectorType(eltType, numResElements,
1539                                      VectorType::GenericVector);
1540    }
1541  }
1542
1543  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1544    if (TheCall->getArg(i)->isTypeDependent() ||
1545        TheCall->getArg(i)->isValueDependent())
1546      continue;
1547
1548    llvm::APSInt Result(32);
1549    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1550      return ExprError(Diag(TheCall->getLocStart(),
1551                  diag::err_shufflevector_nonconstant_argument)
1552                << TheCall->getArg(i)->getSourceRange());
1553
1554    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1555      return ExprError(Diag(TheCall->getLocStart(),
1556                  diag::err_shufflevector_argument_too_large)
1557               << TheCall->getArg(i)->getSourceRange());
1558  }
1559
1560  SmallVector<Expr*, 32> exprs;
1561
1562  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1563    exprs.push_back(TheCall->getArg(i));
1564    TheCall->setArg(i, 0);
1565  }
1566
1567  return Owned(new (Context) ShuffleVectorExpr(Context, exprs, resType,
1568                                            TheCall->getCallee()->getLocStart(),
1569                                            TheCall->getRParenLoc()));
1570}
1571
1572/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1573// This is declared to take (const void*, ...) and can take two
1574// optional constant int args.
1575bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1576  unsigned NumArgs = TheCall->getNumArgs();
1577
1578  if (NumArgs > 3)
1579    return Diag(TheCall->getLocEnd(),
1580             diag::err_typecheck_call_too_many_args_at_most)
1581             << 0 /*function call*/ << 3 << NumArgs
1582             << TheCall->getSourceRange();
1583
1584  // Argument 0 is checked for us and the remaining arguments must be
1585  // constant integers.
1586  for (unsigned i = 1; i != NumArgs; ++i) {
1587    Expr *Arg = TheCall->getArg(i);
1588
1589    // We can't check the value of a dependent argument.
1590    if (Arg->isTypeDependent() || Arg->isValueDependent())
1591      continue;
1592
1593    llvm::APSInt Result;
1594    if (SemaBuiltinConstantArg(TheCall, i, Result))
1595      return true;
1596
1597    // FIXME: gcc issues a warning and rewrites these to 0. These
1598    // seems especially odd for the third argument since the default
1599    // is 3.
1600    if (i == 1) {
1601      if (Result.getLimitedValue() > 1)
1602        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1603             << "0" << "1" << Arg->getSourceRange();
1604    } else {
1605      if (Result.getLimitedValue() > 3)
1606        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1607            << "0" << "3" << Arg->getSourceRange();
1608    }
1609  }
1610
1611  return false;
1612}
1613
1614/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1615/// TheCall is a constant expression.
1616bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1617                                  llvm::APSInt &Result) {
1618  Expr *Arg = TheCall->getArg(ArgNum);
1619  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1620  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1621
1622  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1623
1624  if (!Arg->isIntegerConstantExpr(Result, Context))
1625    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1626                << FDecl->getDeclName() <<  Arg->getSourceRange();
1627
1628  return false;
1629}
1630
1631/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1632/// int type). This simply type checks that type is one of the defined
1633/// constants (0-3).
1634// For compatibility check 0-3, llvm only handles 0 and 2.
1635bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1636  llvm::APSInt Result;
1637
1638  // We can't check the value of a dependent argument.
1639  if (TheCall->getArg(1)->isTypeDependent() ||
1640      TheCall->getArg(1)->isValueDependent())
1641    return false;
1642
1643  // Check constant-ness first.
1644  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1645    return true;
1646
1647  Expr *Arg = TheCall->getArg(1);
1648  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1649    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1650             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1651  }
1652
1653  return false;
1654}
1655
1656/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1657/// This checks that val is a constant 1.
1658bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1659  Expr *Arg = TheCall->getArg(1);
1660  llvm::APSInt Result;
1661
1662  // TODO: This is less than ideal. Overload this to take a value.
1663  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1664    return true;
1665
1666  if (Result != 1)
1667    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1668             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1669
1670  return false;
1671}
1672
1673// Determine if an expression is a string literal or constant string.
1674// If this function returns false on the arguments to a function expecting a
1675// format string, we will usually need to emit a warning.
1676// True string literals are then checked by CheckFormatString.
1677Sema::StringLiteralCheckType
1678Sema::checkFormatStringExpr(const Expr *E, ArrayRef<const Expr *> Args,
1679                            bool HasVAListArg,
1680                            unsigned format_idx, unsigned firstDataArg,
1681                            FormatStringType Type, VariadicCallType CallType,
1682                            bool inFunctionCall) {
1683 tryAgain:
1684  if (E->isTypeDependent() || E->isValueDependent())
1685    return SLCT_NotALiteral;
1686
1687  E = E->IgnoreParenCasts();
1688
1689  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1690    // Technically -Wformat-nonliteral does not warn about this case.
1691    // The behavior of printf and friends in this case is implementation
1692    // dependent.  Ideally if the format string cannot be null then
1693    // it should have a 'nonnull' attribute in the function prototype.
1694    return SLCT_CheckedLiteral;
1695
1696  switch (E->getStmtClass()) {
1697  case Stmt::BinaryConditionalOperatorClass:
1698  case Stmt::ConditionalOperatorClass: {
1699    // The expression is a literal if both sub-expressions were, and it was
1700    // completely checked only if both sub-expressions were checked.
1701    const AbstractConditionalOperator *C =
1702        cast<AbstractConditionalOperator>(E);
1703    StringLiteralCheckType Left =
1704        checkFormatStringExpr(C->getTrueExpr(), Args,
1705                              HasVAListArg, format_idx, firstDataArg,
1706                              Type, CallType, inFunctionCall);
1707    if (Left == SLCT_NotALiteral)
1708      return SLCT_NotALiteral;
1709    StringLiteralCheckType Right =
1710        checkFormatStringExpr(C->getFalseExpr(), Args,
1711                              HasVAListArg, format_idx, firstDataArg,
1712                              Type, CallType, inFunctionCall);
1713    return Left < Right ? Left : Right;
1714  }
1715
1716  case Stmt::ImplicitCastExprClass: {
1717    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1718    goto tryAgain;
1719  }
1720
1721  case Stmt::OpaqueValueExprClass:
1722    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1723      E = src;
1724      goto tryAgain;
1725    }
1726    return SLCT_NotALiteral;
1727
1728  case Stmt::PredefinedExprClass:
1729    // While __func__, etc., are technically not string literals, they
1730    // cannot contain format specifiers and thus are not a security
1731    // liability.
1732    return SLCT_UncheckedLiteral;
1733
1734  case Stmt::DeclRefExprClass: {
1735    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1736
1737    // As an exception, do not flag errors for variables binding to
1738    // const string literals.
1739    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1740      bool isConstant = false;
1741      QualType T = DR->getType();
1742
1743      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1744        isConstant = AT->getElementType().isConstant(Context);
1745      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1746        isConstant = T.isConstant(Context) &&
1747                     PT->getPointeeType().isConstant(Context);
1748      } else if (T->isObjCObjectPointerType()) {
1749        // In ObjC, there is usually no "const ObjectPointer" type,
1750        // so don't check if the pointee type is constant.
1751        isConstant = T.isConstant(Context);
1752      }
1753
1754      if (isConstant) {
1755        if (const Expr *Init = VD->getAnyInitializer()) {
1756          // Look through initializers like const char c[] = { "foo" }
1757          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
1758            if (InitList->isStringLiteralInit())
1759              Init = InitList->getInit(0)->IgnoreParenImpCasts();
1760          }
1761          return checkFormatStringExpr(Init, Args,
1762                                       HasVAListArg, format_idx,
1763                                       firstDataArg, Type, CallType,
1764                                       /*inFunctionCall*/false);
1765        }
1766      }
1767
1768      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1769      // special check to see if the format string is a function parameter
1770      // of the function calling the printf function.  If the function
1771      // has an attribute indicating it is a printf-like function, then we
1772      // should suppress warnings concerning non-literals being used in a call
1773      // to a vprintf function.  For example:
1774      //
1775      // void
1776      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1777      //      va_list ap;
1778      //      va_start(ap, fmt);
1779      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1780      //      ...
1781      //
1782      if (HasVAListArg) {
1783        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1784          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1785            int PVIndex = PV->getFunctionScopeIndex() + 1;
1786            for (specific_attr_iterator<FormatAttr>
1787                 i = ND->specific_attr_begin<FormatAttr>(),
1788                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1789              FormatAttr *PVFormat = *i;
1790              // adjust for implicit parameter
1791              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1792                if (MD->isInstance())
1793                  ++PVIndex;
1794              // We also check if the formats are compatible.
1795              // We can't pass a 'scanf' string to a 'printf' function.
1796              if (PVIndex == PVFormat->getFormatIdx() &&
1797                  Type == GetFormatStringType(PVFormat))
1798                return SLCT_UncheckedLiteral;
1799            }
1800          }
1801        }
1802      }
1803    }
1804
1805    return SLCT_NotALiteral;
1806  }
1807
1808  case Stmt::CallExprClass:
1809  case Stmt::CXXMemberCallExprClass: {
1810    const CallExpr *CE = cast<CallExpr>(E);
1811    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1812      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1813        unsigned ArgIndex = FA->getFormatIdx();
1814        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1815          if (MD->isInstance())
1816            --ArgIndex;
1817        const Expr *Arg = CE->getArg(ArgIndex - 1);
1818
1819        return checkFormatStringExpr(Arg, Args,
1820                                     HasVAListArg, format_idx, firstDataArg,
1821                                     Type, CallType, inFunctionCall);
1822      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
1823        unsigned BuiltinID = FD->getBuiltinID();
1824        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
1825            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
1826          const Expr *Arg = CE->getArg(0);
1827          return checkFormatStringExpr(Arg, Args,
1828                                       HasVAListArg, format_idx,
1829                                       firstDataArg, Type, CallType,
1830                                       inFunctionCall);
1831        }
1832      }
1833    }
1834
1835    return SLCT_NotALiteral;
1836  }
1837  case Stmt::ObjCStringLiteralClass:
1838  case Stmt::StringLiteralClass: {
1839    const StringLiteral *StrE = NULL;
1840
1841    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1842      StrE = ObjCFExpr->getString();
1843    else
1844      StrE = cast<StringLiteral>(E);
1845
1846    if (StrE) {
1847      CheckFormatString(StrE, E, Args, HasVAListArg, format_idx,
1848                        firstDataArg, Type, inFunctionCall, CallType);
1849      return SLCT_CheckedLiteral;
1850    }
1851
1852    return SLCT_NotALiteral;
1853  }
1854
1855  default:
1856    return SLCT_NotALiteral;
1857  }
1858}
1859
1860void
1861Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1862                            const Expr * const *ExprArgs,
1863                            SourceLocation CallSiteLoc) {
1864  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1865                                  e = NonNull->args_end();
1866       i != e; ++i) {
1867    const Expr *ArgExpr = ExprArgs[*i];
1868
1869    // As a special case, transparent unions initialized with zero are
1870    // considered null for the purposes of the nonnull attribute.
1871    if (const RecordType *UT = ArgExpr->getType()->getAsUnionType()) {
1872      if (UT->getDecl()->hasAttr<TransparentUnionAttr>())
1873        if (const CompoundLiteralExpr *CLE =
1874            dyn_cast<CompoundLiteralExpr>(ArgExpr))
1875          if (const InitListExpr *ILE =
1876              dyn_cast<InitListExpr>(CLE->getInitializer()))
1877            ArgExpr = ILE->getInit(0);
1878    }
1879
1880    bool Result;
1881    if (ArgExpr->EvaluateAsBooleanCondition(Result, Context) && !Result)
1882      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1883  }
1884}
1885
1886Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1887  return llvm::StringSwitch<FormatStringType>(Format->getType())
1888  .Case("scanf", FST_Scanf)
1889  .Cases("printf", "printf0", FST_Printf)
1890  .Cases("NSString", "CFString", FST_NSString)
1891  .Case("strftime", FST_Strftime)
1892  .Case("strfmon", FST_Strfmon)
1893  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1894  .Default(FST_Unknown);
1895}
1896
1897/// CheckFormatArguments - Check calls to printf and scanf (and similar
1898/// functions) for correct use of format strings.
1899/// Returns true if a format string has been fully checked.
1900bool Sema::CheckFormatArguments(const FormatAttr *Format,
1901                                ArrayRef<const Expr *> Args,
1902                                bool IsCXXMember,
1903                                VariadicCallType CallType,
1904                                SourceLocation Loc, SourceRange Range) {
1905  FormatStringInfo FSI;
1906  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
1907    return CheckFormatArguments(Args, FSI.HasVAListArg, FSI.FormatIdx,
1908                                FSI.FirstDataArg, GetFormatStringType(Format),
1909                                CallType, Loc, Range);
1910  return false;
1911}
1912
1913bool Sema::CheckFormatArguments(ArrayRef<const Expr *> Args,
1914                                bool HasVAListArg, unsigned format_idx,
1915                                unsigned firstDataArg, FormatStringType Type,
1916                                VariadicCallType CallType,
1917                                SourceLocation Loc, SourceRange Range) {
1918  // CHECK: printf/scanf-like function is called with no format string.
1919  if (format_idx >= Args.size()) {
1920    Diag(Loc, diag::warn_missing_format_string) << Range;
1921    return false;
1922  }
1923
1924  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1925
1926  // CHECK: format string is not a string literal.
1927  //
1928  // Dynamically generated format strings are difficult to
1929  // automatically vet at compile time.  Requiring that format strings
1930  // are string literals: (1) permits the checking of format strings by
1931  // the compiler and thereby (2) can practically remove the source of
1932  // many format string exploits.
1933
1934  // Format string can be either ObjC string (e.g. @"%d") or
1935  // C string (e.g. "%d")
1936  // ObjC string uses the same format specifiers as C string, so we can use
1937  // the same format string checking logic for both ObjC and C strings.
1938  StringLiteralCheckType CT =
1939      checkFormatStringExpr(OrigFormatExpr, Args, HasVAListArg,
1940                            format_idx, firstDataArg, Type, CallType);
1941  if (CT != SLCT_NotALiteral)
1942    // Literal format string found, check done!
1943    return CT == SLCT_CheckedLiteral;
1944
1945  // Strftime is particular as it always uses a single 'time' argument,
1946  // so it is safe to pass a non-literal string.
1947  if (Type == FST_Strftime)
1948    return false;
1949
1950  // Do not emit diag when the string param is a macro expansion and the
1951  // format is either NSString or CFString. This is a hack to prevent
1952  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1953  // which are usually used in place of NS and CF string literals.
1954  if (Type == FST_NSString &&
1955      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
1956    return false;
1957
1958  // If there are no arguments specified, warn with -Wformat-security, otherwise
1959  // warn only with -Wformat-nonliteral.
1960  if (Args.size() == firstDataArg)
1961    Diag(Args[format_idx]->getLocStart(),
1962         diag::warn_format_nonliteral_noargs)
1963      << OrigFormatExpr->getSourceRange();
1964  else
1965    Diag(Args[format_idx]->getLocStart(),
1966         diag::warn_format_nonliteral)
1967           << OrigFormatExpr->getSourceRange();
1968  return false;
1969}
1970
1971namespace {
1972class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1973protected:
1974  Sema &S;
1975  const StringLiteral *FExpr;
1976  const Expr *OrigFormatExpr;
1977  const unsigned FirstDataArg;
1978  const unsigned NumDataArgs;
1979  const char *Beg; // Start of format string.
1980  const bool HasVAListArg;
1981  ArrayRef<const Expr *> Args;
1982  unsigned FormatIdx;
1983  llvm::BitVector CoveredArgs;
1984  bool usesPositionalArgs;
1985  bool atFirstArg;
1986  bool inFunctionCall;
1987  Sema::VariadicCallType CallType;
1988public:
1989  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1990                     const Expr *origFormatExpr, unsigned firstDataArg,
1991                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
1992                     ArrayRef<const Expr *> Args,
1993                     unsigned formatIdx, bool inFunctionCall,
1994                     Sema::VariadicCallType callType)
1995    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1996      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
1997      Beg(beg), HasVAListArg(hasVAListArg),
1998      Args(Args), FormatIdx(formatIdx),
1999      usesPositionalArgs(false), atFirstArg(true),
2000      inFunctionCall(inFunctionCall), CallType(callType) {
2001        CoveredArgs.resize(numDataArgs);
2002        CoveredArgs.reset();
2003      }
2004
2005  void DoneProcessing();
2006
2007  void HandleIncompleteSpecifier(const char *startSpecifier,
2008                                 unsigned specifierLen);
2009
2010  void HandleInvalidLengthModifier(
2011      const analyze_format_string::FormatSpecifier &FS,
2012      const analyze_format_string::ConversionSpecifier &CS,
2013      const char *startSpecifier, unsigned specifierLen, unsigned DiagID);
2014
2015  void HandleNonStandardLengthModifier(
2016      const analyze_format_string::FormatSpecifier &FS,
2017      const char *startSpecifier, unsigned specifierLen);
2018
2019  void HandleNonStandardConversionSpecifier(
2020      const analyze_format_string::ConversionSpecifier &CS,
2021      const char *startSpecifier, unsigned specifierLen);
2022
2023  virtual void HandlePosition(const char *startPos, unsigned posLen);
2024
2025  virtual void HandleInvalidPosition(const char *startSpecifier,
2026                                     unsigned specifierLen,
2027                                     analyze_format_string::PositionContext p);
2028
2029  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
2030
2031  void HandleNullChar(const char *nullCharacter);
2032
2033  template <typename Range>
2034  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
2035                                   const Expr *ArgumentExpr,
2036                                   PartialDiagnostic PDiag,
2037                                   SourceLocation StringLoc,
2038                                   bool IsStringLocation, Range StringRange,
2039                                   ArrayRef<FixItHint> Fixit = None);
2040
2041protected:
2042  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
2043                                        const char *startSpec,
2044                                        unsigned specifierLen,
2045                                        const char *csStart, unsigned csLen);
2046
2047  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
2048                                         const char *startSpec,
2049                                         unsigned specifierLen);
2050
2051  SourceRange getFormatStringRange();
2052  CharSourceRange getSpecifierRange(const char *startSpecifier,
2053                                    unsigned specifierLen);
2054  SourceLocation getLocationOfByte(const char *x);
2055
2056  const Expr *getDataArg(unsigned i) const;
2057
2058  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
2059                    const analyze_format_string::ConversionSpecifier &CS,
2060                    const char *startSpecifier, unsigned specifierLen,
2061                    unsigned argIndex);
2062
2063  template <typename Range>
2064  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
2065                            bool IsStringLocation, Range StringRange,
2066                            ArrayRef<FixItHint> Fixit = None);
2067
2068  void CheckPositionalAndNonpositionalArgs(
2069      const analyze_format_string::FormatSpecifier *FS);
2070};
2071}
2072
2073SourceRange CheckFormatHandler::getFormatStringRange() {
2074  return OrigFormatExpr->getSourceRange();
2075}
2076
2077CharSourceRange CheckFormatHandler::
2078getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2079  SourceLocation Start = getLocationOfByte(startSpecifier);
2080  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2081
2082  // Advance the end SourceLocation by one due to half-open ranges.
2083  End = End.getLocWithOffset(1);
2084
2085  return CharSourceRange::getCharRange(Start, End);
2086}
2087
2088SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2089  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2090}
2091
2092void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2093                                                   unsigned specifierLen){
2094  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2095                       getLocationOfByte(startSpecifier),
2096                       /*IsStringLocation*/true,
2097                       getSpecifierRange(startSpecifier, specifierLen));
2098}
2099
2100void CheckFormatHandler::HandleInvalidLengthModifier(
2101    const analyze_format_string::FormatSpecifier &FS,
2102    const analyze_format_string::ConversionSpecifier &CS,
2103    const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
2104  using namespace analyze_format_string;
2105
2106  const LengthModifier &LM = FS.getLengthModifier();
2107  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2108
2109  // See if we know how to fix this length modifier.
2110  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2111  if (FixedLM) {
2112    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2113                         getLocationOfByte(LM.getStart()),
2114                         /*IsStringLocation*/true,
2115                         getSpecifierRange(startSpecifier, specifierLen));
2116
2117    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2118      << FixedLM->toString()
2119      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2120
2121  } else {
2122    FixItHint Hint;
2123    if (DiagID == diag::warn_format_nonsensical_length)
2124      Hint = FixItHint::CreateRemoval(LMRange);
2125
2126    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2127                         getLocationOfByte(LM.getStart()),
2128                         /*IsStringLocation*/true,
2129                         getSpecifierRange(startSpecifier, specifierLen),
2130                         Hint);
2131  }
2132}
2133
2134void CheckFormatHandler::HandleNonStandardLengthModifier(
2135    const analyze_format_string::FormatSpecifier &FS,
2136    const char *startSpecifier, unsigned specifierLen) {
2137  using namespace analyze_format_string;
2138
2139  const LengthModifier &LM = FS.getLengthModifier();
2140  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2141
2142  // See if we know how to fix this length modifier.
2143  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2144  if (FixedLM) {
2145    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2146                           << LM.toString() << 0,
2147                         getLocationOfByte(LM.getStart()),
2148                         /*IsStringLocation*/true,
2149                         getSpecifierRange(startSpecifier, specifierLen));
2150
2151    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2152      << FixedLM->toString()
2153      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2154
2155  } else {
2156    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2157                           << LM.toString() << 0,
2158                         getLocationOfByte(LM.getStart()),
2159                         /*IsStringLocation*/true,
2160                         getSpecifierRange(startSpecifier, specifierLen));
2161  }
2162}
2163
2164void CheckFormatHandler::HandleNonStandardConversionSpecifier(
2165    const analyze_format_string::ConversionSpecifier &CS,
2166    const char *startSpecifier, unsigned specifierLen) {
2167  using namespace analyze_format_string;
2168
2169  // See if we know how to fix this conversion specifier.
2170  Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
2171  if (FixedCS) {
2172    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2173                          << CS.toString() << /*conversion specifier*/1,
2174                         getLocationOfByte(CS.getStart()),
2175                         /*IsStringLocation*/true,
2176                         getSpecifierRange(startSpecifier, specifierLen));
2177
2178    CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
2179    S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
2180      << FixedCS->toString()
2181      << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
2182  } else {
2183    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2184                          << CS.toString() << /*conversion specifier*/1,
2185                         getLocationOfByte(CS.getStart()),
2186                         /*IsStringLocation*/true,
2187                         getSpecifierRange(startSpecifier, specifierLen));
2188  }
2189}
2190
2191void CheckFormatHandler::HandlePosition(const char *startPos,
2192                                        unsigned posLen) {
2193  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
2194                               getLocationOfByte(startPos),
2195                               /*IsStringLocation*/true,
2196                               getSpecifierRange(startPos, posLen));
2197}
2198
2199void
2200CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
2201                                     analyze_format_string::PositionContext p) {
2202  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
2203                         << (unsigned) p,
2204                       getLocationOfByte(startPos), /*IsStringLocation*/true,
2205                       getSpecifierRange(startPos, posLen));
2206}
2207
2208void CheckFormatHandler::HandleZeroPosition(const char *startPos,
2209                                            unsigned posLen) {
2210  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
2211                               getLocationOfByte(startPos),
2212                               /*IsStringLocation*/true,
2213                               getSpecifierRange(startPos, posLen));
2214}
2215
2216void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
2217  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
2218    // The presence of a null character is likely an error.
2219    EmitFormatDiagnostic(
2220      S.PDiag(diag::warn_printf_format_string_contains_null_char),
2221      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
2222      getFormatStringRange());
2223  }
2224}
2225
2226// Note that this may return NULL if there was an error parsing or building
2227// one of the argument expressions.
2228const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
2229  return Args[FirstDataArg + i];
2230}
2231
2232void CheckFormatHandler::DoneProcessing() {
2233    // Does the number of data arguments exceed the number of
2234    // format conversions in the format string?
2235  if (!HasVAListArg) {
2236      // Find any arguments that weren't covered.
2237    CoveredArgs.flip();
2238    signed notCoveredArg = CoveredArgs.find_first();
2239    if (notCoveredArg >= 0) {
2240      assert((unsigned)notCoveredArg < NumDataArgs);
2241      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
2242        SourceLocation Loc = E->getLocStart();
2243        if (!S.getSourceManager().isInSystemMacro(Loc)) {
2244          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
2245                               Loc, /*IsStringLocation*/false,
2246                               getFormatStringRange());
2247        }
2248      }
2249    }
2250  }
2251}
2252
2253bool
2254CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
2255                                                     SourceLocation Loc,
2256                                                     const char *startSpec,
2257                                                     unsigned specifierLen,
2258                                                     const char *csStart,
2259                                                     unsigned csLen) {
2260
2261  bool keepGoing = true;
2262  if (argIndex < NumDataArgs) {
2263    // Consider the argument coverered, even though the specifier doesn't
2264    // make sense.
2265    CoveredArgs.set(argIndex);
2266  }
2267  else {
2268    // If argIndex exceeds the number of data arguments we
2269    // don't issue a warning because that is just a cascade of warnings (and
2270    // they may have intended '%%' anyway). We don't want to continue processing
2271    // the format string after this point, however, as we will like just get
2272    // gibberish when trying to match arguments.
2273    keepGoing = false;
2274  }
2275
2276  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2277                         << StringRef(csStart, csLen),
2278                       Loc, /*IsStringLocation*/true,
2279                       getSpecifierRange(startSpec, specifierLen));
2280
2281  return keepGoing;
2282}
2283
2284void
2285CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2286                                                      const char *startSpec,
2287                                                      unsigned specifierLen) {
2288  EmitFormatDiagnostic(
2289    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2290    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2291}
2292
2293bool
2294CheckFormatHandler::CheckNumArgs(
2295  const analyze_format_string::FormatSpecifier &FS,
2296  const analyze_format_string::ConversionSpecifier &CS,
2297  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2298
2299  if (argIndex >= NumDataArgs) {
2300    PartialDiagnostic PDiag = FS.usesPositionalArg()
2301      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2302           << (argIndex+1) << NumDataArgs)
2303      : S.PDiag(diag::warn_printf_insufficient_data_args);
2304    EmitFormatDiagnostic(
2305      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2306      getSpecifierRange(startSpecifier, specifierLen));
2307    return false;
2308  }
2309  return true;
2310}
2311
2312template<typename Range>
2313void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2314                                              SourceLocation Loc,
2315                                              bool IsStringLocation,
2316                                              Range StringRange,
2317                                              ArrayRef<FixItHint> FixIt) {
2318  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2319                       Loc, IsStringLocation, StringRange, FixIt);
2320}
2321
2322/// \brief If the format string is not within the funcion call, emit a note
2323/// so that the function call and string are in diagnostic messages.
2324///
2325/// \param InFunctionCall if true, the format string is within the function
2326/// call and only one diagnostic message will be produced.  Otherwise, an
2327/// extra note will be emitted pointing to location of the format string.
2328///
2329/// \param ArgumentExpr the expression that is passed as the format string
2330/// argument in the function call.  Used for getting locations when two
2331/// diagnostics are emitted.
2332///
2333/// \param PDiag the callee should already have provided any strings for the
2334/// diagnostic message.  This function only adds locations and fixits
2335/// to diagnostics.
2336///
2337/// \param Loc primary location for diagnostic.  If two diagnostics are
2338/// required, one will be at Loc and a new SourceLocation will be created for
2339/// the other one.
2340///
2341/// \param IsStringLocation if true, Loc points to the format string should be
2342/// used for the note.  Otherwise, Loc points to the argument list and will
2343/// be used with PDiag.
2344///
2345/// \param StringRange some or all of the string to highlight.  This is
2346/// templated so it can accept either a CharSourceRange or a SourceRange.
2347///
2348/// \param FixIt optional fix it hint for the format string.
2349template<typename Range>
2350void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2351                                              const Expr *ArgumentExpr,
2352                                              PartialDiagnostic PDiag,
2353                                              SourceLocation Loc,
2354                                              bool IsStringLocation,
2355                                              Range StringRange,
2356                                              ArrayRef<FixItHint> FixIt) {
2357  if (InFunctionCall) {
2358    const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
2359    D << StringRange;
2360    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2361         I != E; ++I) {
2362      D << *I;
2363    }
2364  } else {
2365    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2366      << ArgumentExpr->getSourceRange();
2367
2368    const Sema::SemaDiagnosticBuilder &Note =
2369      S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2370             diag::note_format_string_defined);
2371
2372    Note << StringRange;
2373    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2374         I != E; ++I) {
2375      Note << *I;
2376    }
2377  }
2378}
2379
2380//===--- CHECK: Printf format string checking ------------------------------===//
2381
2382namespace {
2383class CheckPrintfHandler : public CheckFormatHandler {
2384  bool ObjCContext;
2385public:
2386  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2387                     const Expr *origFormatExpr, unsigned firstDataArg,
2388                     unsigned numDataArgs, bool isObjC,
2389                     const char *beg, bool hasVAListArg,
2390                     ArrayRef<const Expr *> Args,
2391                     unsigned formatIdx, bool inFunctionCall,
2392                     Sema::VariadicCallType CallType)
2393  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2394                       numDataArgs, beg, hasVAListArg, Args,
2395                       formatIdx, inFunctionCall, CallType), ObjCContext(isObjC)
2396  {}
2397
2398
2399  bool HandleInvalidPrintfConversionSpecifier(
2400                                      const analyze_printf::PrintfSpecifier &FS,
2401                                      const char *startSpecifier,
2402                                      unsigned specifierLen);
2403
2404  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2405                             const char *startSpecifier,
2406                             unsigned specifierLen);
2407  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2408                       const char *StartSpecifier,
2409                       unsigned SpecifierLen,
2410                       const Expr *E);
2411
2412  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2413                    const char *startSpecifier, unsigned specifierLen);
2414  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2415                           const analyze_printf::OptionalAmount &Amt,
2416                           unsigned type,
2417                           const char *startSpecifier, unsigned specifierLen);
2418  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2419                  const analyze_printf::OptionalFlag &flag,
2420                  const char *startSpecifier, unsigned specifierLen);
2421  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2422                         const analyze_printf::OptionalFlag &ignoredFlag,
2423                         const analyze_printf::OptionalFlag &flag,
2424                         const char *startSpecifier, unsigned specifierLen);
2425  bool checkForCStrMembers(const analyze_printf::ArgType &AT,
2426                           const Expr *E, const CharSourceRange &CSR);
2427
2428};
2429}
2430
2431bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2432                                      const analyze_printf::PrintfSpecifier &FS,
2433                                      const char *startSpecifier,
2434                                      unsigned specifierLen) {
2435  const analyze_printf::PrintfConversionSpecifier &CS =
2436    FS.getConversionSpecifier();
2437
2438  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2439                                          getLocationOfByte(CS.getStart()),
2440                                          startSpecifier, specifierLen,
2441                                          CS.getStart(), CS.getLength());
2442}
2443
2444bool CheckPrintfHandler::HandleAmount(
2445                               const analyze_format_string::OptionalAmount &Amt,
2446                               unsigned k, const char *startSpecifier,
2447                               unsigned specifierLen) {
2448
2449  if (Amt.hasDataArgument()) {
2450    if (!HasVAListArg) {
2451      unsigned argIndex = Amt.getArgIndex();
2452      if (argIndex >= NumDataArgs) {
2453        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2454                               << k,
2455                             getLocationOfByte(Amt.getStart()),
2456                             /*IsStringLocation*/true,
2457                             getSpecifierRange(startSpecifier, specifierLen));
2458        // Don't do any more checking.  We will just emit
2459        // spurious errors.
2460        return false;
2461      }
2462
2463      // Type check the data argument.  It should be an 'int'.
2464      // Although not in conformance with C99, we also allow the argument to be
2465      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2466      // doesn't emit a warning for that case.
2467      CoveredArgs.set(argIndex);
2468      const Expr *Arg = getDataArg(argIndex);
2469      if (!Arg)
2470        return false;
2471
2472      QualType T = Arg->getType();
2473
2474      const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
2475      assert(AT.isValid());
2476
2477      if (!AT.matchesType(S.Context, T)) {
2478        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2479                               << k << AT.getRepresentativeTypeName(S.Context)
2480                               << T << Arg->getSourceRange(),
2481                             getLocationOfByte(Amt.getStart()),
2482                             /*IsStringLocation*/true,
2483                             getSpecifierRange(startSpecifier, specifierLen));
2484        // Don't do any more checking.  We will just emit
2485        // spurious errors.
2486        return false;
2487      }
2488    }
2489  }
2490  return true;
2491}
2492
2493void CheckPrintfHandler::HandleInvalidAmount(
2494                                      const analyze_printf::PrintfSpecifier &FS,
2495                                      const analyze_printf::OptionalAmount &Amt,
2496                                      unsigned type,
2497                                      const char *startSpecifier,
2498                                      unsigned specifierLen) {
2499  const analyze_printf::PrintfConversionSpecifier &CS =
2500    FS.getConversionSpecifier();
2501
2502  FixItHint fixit =
2503    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2504      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2505                                 Amt.getConstantLength()))
2506      : FixItHint();
2507
2508  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2509                         << type << CS.toString(),
2510                       getLocationOfByte(Amt.getStart()),
2511                       /*IsStringLocation*/true,
2512                       getSpecifierRange(startSpecifier, specifierLen),
2513                       fixit);
2514}
2515
2516void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2517                                    const analyze_printf::OptionalFlag &flag,
2518                                    const char *startSpecifier,
2519                                    unsigned specifierLen) {
2520  // Warn about pointless flag with a fixit removal.
2521  const analyze_printf::PrintfConversionSpecifier &CS =
2522    FS.getConversionSpecifier();
2523  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2524                         << flag.toString() << CS.toString(),
2525                       getLocationOfByte(flag.getPosition()),
2526                       /*IsStringLocation*/true,
2527                       getSpecifierRange(startSpecifier, specifierLen),
2528                       FixItHint::CreateRemoval(
2529                         getSpecifierRange(flag.getPosition(), 1)));
2530}
2531
2532void CheckPrintfHandler::HandleIgnoredFlag(
2533                                const analyze_printf::PrintfSpecifier &FS,
2534                                const analyze_printf::OptionalFlag &ignoredFlag,
2535                                const analyze_printf::OptionalFlag &flag,
2536                                const char *startSpecifier,
2537                                unsigned specifierLen) {
2538  // Warn about ignored flag with a fixit removal.
2539  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2540                         << ignoredFlag.toString() << flag.toString(),
2541                       getLocationOfByte(ignoredFlag.getPosition()),
2542                       /*IsStringLocation*/true,
2543                       getSpecifierRange(startSpecifier, specifierLen),
2544                       FixItHint::CreateRemoval(
2545                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2546}
2547
2548// Determines if the specified is a C++ class or struct containing
2549// a member with the specified name and kind (e.g. a CXXMethodDecl named
2550// "c_str()").
2551template<typename MemberKind>
2552static llvm::SmallPtrSet<MemberKind*, 1>
2553CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
2554  const RecordType *RT = Ty->getAs<RecordType>();
2555  llvm::SmallPtrSet<MemberKind*, 1> Results;
2556
2557  if (!RT)
2558    return Results;
2559  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
2560  if (!RD)
2561    return Results;
2562
2563  LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
2564                 Sema::LookupMemberName);
2565
2566  // We just need to include all members of the right kind turned up by the
2567  // filter, at this point.
2568  if (S.LookupQualifiedName(R, RT->getDecl()))
2569    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
2570      NamedDecl *decl = (*I)->getUnderlyingDecl();
2571      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
2572        Results.insert(FK);
2573    }
2574  return Results;
2575}
2576
2577// Check if a (w)string was passed when a (w)char* was needed, and offer a
2578// better diagnostic if so. AT is assumed to be valid.
2579// Returns true when a c_str() conversion method is found.
2580bool CheckPrintfHandler::checkForCStrMembers(
2581    const analyze_printf::ArgType &AT, const Expr *E,
2582    const CharSourceRange &CSR) {
2583  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
2584
2585  MethodSet Results =
2586      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
2587
2588  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
2589       MI != ME; ++MI) {
2590    const CXXMethodDecl *Method = *MI;
2591    if (Method->getNumParams() == 0 &&
2592          AT.matchesType(S.Context, Method->getResultType())) {
2593      // FIXME: Suggest parens if the expression needs them.
2594      SourceLocation EndLoc =
2595          S.getPreprocessor().getLocForEndOfToken(E->getLocEnd());
2596      S.Diag(E->getLocStart(), diag::note_printf_c_str)
2597          << "c_str()"
2598          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
2599      return true;
2600    }
2601  }
2602
2603  return false;
2604}
2605
2606bool
2607CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2608                                            &FS,
2609                                          const char *startSpecifier,
2610                                          unsigned specifierLen) {
2611
2612  using namespace analyze_format_string;
2613  using namespace analyze_printf;
2614  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2615
2616  if (FS.consumesDataArgument()) {
2617    if (atFirstArg) {
2618        atFirstArg = false;
2619        usesPositionalArgs = FS.usesPositionalArg();
2620    }
2621    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2622      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2623                                        startSpecifier, specifierLen);
2624      return false;
2625    }
2626  }
2627
2628  // First check if the field width, precision, and conversion specifier
2629  // have matching data arguments.
2630  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2631                    startSpecifier, specifierLen)) {
2632    return false;
2633  }
2634
2635  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2636                    startSpecifier, specifierLen)) {
2637    return false;
2638  }
2639
2640  if (!CS.consumesDataArgument()) {
2641    // FIXME: Technically specifying a precision or field width here
2642    // makes no sense.  Worth issuing a warning at some point.
2643    return true;
2644  }
2645
2646  // Consume the argument.
2647  unsigned argIndex = FS.getArgIndex();
2648  if (argIndex < NumDataArgs) {
2649    // The check to see if the argIndex is valid will come later.
2650    // We set the bit here because we may exit early from this
2651    // function if we encounter some other error.
2652    CoveredArgs.set(argIndex);
2653  }
2654
2655  // Check for using an Objective-C specific conversion specifier
2656  // in a non-ObjC literal.
2657  if (!ObjCContext && CS.isObjCArg()) {
2658    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2659                                                  specifierLen);
2660  }
2661
2662  // Check for invalid use of field width
2663  if (!FS.hasValidFieldWidth()) {
2664    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2665        startSpecifier, specifierLen);
2666  }
2667
2668  // Check for invalid use of precision
2669  if (!FS.hasValidPrecision()) {
2670    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2671        startSpecifier, specifierLen);
2672  }
2673
2674  // Check each flag does not conflict with any other component.
2675  if (!FS.hasValidThousandsGroupingPrefix())
2676    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2677  if (!FS.hasValidLeadingZeros())
2678    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2679  if (!FS.hasValidPlusPrefix())
2680    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2681  if (!FS.hasValidSpacePrefix())
2682    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2683  if (!FS.hasValidAlternativeForm())
2684    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2685  if (!FS.hasValidLeftJustified())
2686    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2687
2688  // Check that flags are not ignored by another flag
2689  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2690    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2691        startSpecifier, specifierLen);
2692  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2693    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2694            startSpecifier, specifierLen);
2695
2696  // Check the length modifier is valid with the given conversion specifier.
2697  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
2698    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2699                                diag::warn_format_nonsensical_length);
2700  else if (!FS.hasStandardLengthModifier())
2701    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
2702  else if (!FS.hasStandardLengthConversionCombination())
2703    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2704                                diag::warn_format_non_standard_conversion_spec);
2705
2706  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2707    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2708
2709  // The remaining checks depend on the data arguments.
2710  if (HasVAListArg)
2711    return true;
2712
2713  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2714    return false;
2715
2716  const Expr *Arg = getDataArg(argIndex);
2717  if (!Arg)
2718    return true;
2719
2720  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
2721}
2722
2723static bool requiresParensToAddCast(const Expr *E) {
2724  // FIXME: We should have a general way to reason about operator
2725  // precedence and whether parens are actually needed here.
2726  // Take care of a few common cases where they aren't.
2727  const Expr *Inside = E->IgnoreImpCasts();
2728  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
2729    Inside = POE->getSyntacticForm()->IgnoreImpCasts();
2730
2731  switch (Inside->getStmtClass()) {
2732  case Stmt::ArraySubscriptExprClass:
2733  case Stmt::CallExprClass:
2734  case Stmt::CharacterLiteralClass:
2735  case Stmt::CXXBoolLiteralExprClass:
2736  case Stmt::DeclRefExprClass:
2737  case Stmt::FloatingLiteralClass:
2738  case Stmt::IntegerLiteralClass:
2739  case Stmt::MemberExprClass:
2740  case Stmt::ObjCArrayLiteralClass:
2741  case Stmt::ObjCBoolLiteralExprClass:
2742  case Stmt::ObjCBoxedExprClass:
2743  case Stmt::ObjCDictionaryLiteralClass:
2744  case Stmt::ObjCEncodeExprClass:
2745  case Stmt::ObjCIvarRefExprClass:
2746  case Stmt::ObjCMessageExprClass:
2747  case Stmt::ObjCPropertyRefExprClass:
2748  case Stmt::ObjCStringLiteralClass:
2749  case Stmt::ObjCSubscriptRefExprClass:
2750  case Stmt::ParenExprClass:
2751  case Stmt::StringLiteralClass:
2752  case Stmt::UnaryOperatorClass:
2753    return false;
2754  default:
2755    return true;
2756  }
2757}
2758
2759bool
2760CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2761                                    const char *StartSpecifier,
2762                                    unsigned SpecifierLen,
2763                                    const Expr *E) {
2764  using namespace analyze_format_string;
2765  using namespace analyze_printf;
2766  // Now type check the data expression that matches the
2767  // format specifier.
2768  const analyze_printf::ArgType &AT = FS.getArgType(S.Context,
2769                                                    ObjCContext);
2770  if (!AT.isValid())
2771    return true;
2772
2773  QualType ExprTy = E->getType();
2774  while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
2775    ExprTy = TET->getUnderlyingExpr()->getType();
2776  }
2777
2778  if (AT.matchesType(S.Context, ExprTy))
2779    return true;
2780
2781  // Look through argument promotions for our error message's reported type.
2782  // This includes the integral and floating promotions, but excludes array
2783  // and function pointer decay; seeing that an argument intended to be a
2784  // string has type 'char [6]' is probably more confusing than 'char *'.
2785  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2786    if (ICE->getCastKind() == CK_IntegralCast ||
2787        ICE->getCastKind() == CK_FloatingCast) {
2788      E = ICE->getSubExpr();
2789      ExprTy = E->getType();
2790
2791      // Check if we didn't match because of an implicit cast from a 'char'
2792      // or 'short' to an 'int'.  This is done because printf is a varargs
2793      // function.
2794      if (ICE->getType() == S.Context.IntTy ||
2795          ICE->getType() == S.Context.UnsignedIntTy) {
2796        // All further checking is done on the subexpression.
2797        if (AT.matchesType(S.Context, ExprTy))
2798          return true;
2799      }
2800    }
2801  } else if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) {
2802    // Special case for 'a', which has type 'int' in C.
2803    // Note, however, that we do /not/ want to treat multibyte constants like
2804    // 'MooV' as characters! This form is deprecated but still exists.
2805    if (ExprTy == S.Context.IntTy)
2806      if (llvm::isUIntN(S.Context.getCharWidth(), CL->getValue()))
2807        ExprTy = S.Context.CharTy;
2808  }
2809
2810  // %C in an Objective-C context prints a unichar, not a wchar_t.
2811  // If the argument is an integer of some kind, believe the %C and suggest
2812  // a cast instead of changing the conversion specifier.
2813  QualType IntendedTy = ExprTy;
2814  if (ObjCContext &&
2815      FS.getConversionSpecifier().getKind() == ConversionSpecifier::CArg) {
2816    if (ExprTy->isIntegralOrUnscopedEnumerationType() &&
2817        !ExprTy->isCharType()) {
2818      // 'unichar' is defined as a typedef of unsigned short, but we should
2819      // prefer using the typedef if it is visible.
2820      IntendedTy = S.Context.UnsignedShortTy;
2821
2822      LookupResult Result(S, &S.Context.Idents.get("unichar"), E->getLocStart(),
2823                          Sema::LookupOrdinaryName);
2824      if (S.LookupName(Result, S.getCurScope())) {
2825        NamedDecl *ND = Result.getFoundDecl();
2826        if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(ND))
2827          if (TD->getUnderlyingType() == IntendedTy)
2828            IntendedTy = S.Context.getTypedefType(TD);
2829      }
2830    }
2831  }
2832
2833  // Special-case some of Darwin's platform-independence types by suggesting
2834  // casts to primitive types that are known to be large enough.
2835  bool ShouldNotPrintDirectly = false;
2836  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
2837    // Use a 'while' to peel off layers of typedefs.
2838    QualType TyTy = IntendedTy;
2839    while (const TypedefType *UserTy = TyTy->getAs<TypedefType>()) {
2840      StringRef Name = UserTy->getDecl()->getName();
2841      QualType CastTy = llvm::StringSwitch<QualType>(Name)
2842        .Case("NSInteger", S.Context.LongTy)
2843        .Case("NSUInteger", S.Context.UnsignedLongTy)
2844        .Case("SInt32", S.Context.IntTy)
2845        .Case("UInt32", S.Context.UnsignedIntTy)
2846        .Default(QualType());
2847
2848      if (!CastTy.isNull()) {
2849        ShouldNotPrintDirectly = true;
2850        IntendedTy = CastTy;
2851        break;
2852      }
2853      TyTy = UserTy->desugar();
2854    }
2855  }
2856
2857  // We may be able to offer a FixItHint if it is a supported type.
2858  PrintfSpecifier fixedFS = FS;
2859  bool success = fixedFS.fixType(IntendedTy, S.getLangOpts(),
2860                                 S.Context, ObjCContext);
2861
2862  if (success) {
2863    // Get the fix string from the fixed format specifier
2864    SmallString<16> buf;
2865    llvm::raw_svector_ostream os(buf);
2866    fixedFS.toString(os);
2867
2868    CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
2869
2870    if (IntendedTy == ExprTy) {
2871      // In this case, the specifier is wrong and should be changed to match
2872      // the argument.
2873      EmitFormatDiagnostic(
2874        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2875          << AT.getRepresentativeTypeName(S.Context) << IntendedTy
2876          << E->getSourceRange(),
2877        E->getLocStart(),
2878        /*IsStringLocation*/false,
2879        SpecRange,
2880        FixItHint::CreateReplacement(SpecRange, os.str()));
2881
2882    } else {
2883      // The canonical type for formatting this value is different from the
2884      // actual type of the expression. (This occurs, for example, with Darwin's
2885      // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
2886      // should be printed as 'long' for 64-bit compatibility.)
2887      // Rather than emitting a normal format/argument mismatch, we want to
2888      // add a cast to the recommended type (and correct the format string
2889      // if necessary).
2890      SmallString<16> CastBuf;
2891      llvm::raw_svector_ostream CastFix(CastBuf);
2892      CastFix << "(";
2893      IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
2894      CastFix << ")";
2895
2896      SmallVector<FixItHint,4> Hints;
2897      if (!AT.matchesType(S.Context, IntendedTy))
2898        Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
2899
2900      if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
2901        // If there's already a cast present, just replace it.
2902        SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
2903        Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
2904
2905      } else if (!requiresParensToAddCast(E)) {
2906        // If the expression has high enough precedence,
2907        // just write the C-style cast.
2908        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2909                                                   CastFix.str()));
2910      } else {
2911        // Otherwise, add parens around the expression as well as the cast.
2912        CastFix << "(";
2913        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2914                                                   CastFix.str()));
2915
2916        SourceLocation After = S.PP.getLocForEndOfToken(E->getLocEnd());
2917        Hints.push_back(FixItHint::CreateInsertion(After, ")"));
2918      }
2919
2920      if (ShouldNotPrintDirectly) {
2921        // The expression has a type that should not be printed directly.
2922        // We extract the name from the typedef because we don't want to show
2923        // the underlying type in the diagnostic.
2924        StringRef Name = cast<TypedefType>(ExprTy)->getDecl()->getName();
2925
2926        EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
2927                               << Name << IntendedTy
2928                               << E->getSourceRange(),
2929                             E->getLocStart(), /*IsStringLocation=*/false,
2930                             SpecRange, Hints);
2931      } else {
2932        // In this case, the expression could be printed using a different
2933        // specifier, but we've decided that the specifier is probably correct
2934        // and we should cast instead. Just use the normal warning message.
2935        EmitFormatDiagnostic(
2936          S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2937            << AT.getRepresentativeTypeName(S.Context) << ExprTy
2938            << E->getSourceRange(),
2939          E->getLocStart(), /*IsStringLocation*/false,
2940          SpecRange, Hints);
2941      }
2942    }
2943  } else {
2944    const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
2945                                                   SpecifierLen);
2946    // Since the warning for passing non-POD types to variadic functions
2947    // was deferred until now, we emit a warning for non-POD
2948    // arguments here.
2949    if (S.isValidVarArgType(ExprTy) == Sema::VAK_Invalid) {
2950      unsigned DiagKind;
2951      if (ExprTy->isObjCObjectType())
2952        DiagKind = diag::err_cannot_pass_objc_interface_to_vararg_format;
2953      else
2954        DiagKind = diag::warn_non_pod_vararg_with_format_string;
2955
2956      EmitFormatDiagnostic(
2957        S.PDiag(DiagKind)
2958          << S.getLangOpts().CPlusPlus11
2959          << ExprTy
2960          << CallType
2961          << AT.getRepresentativeTypeName(S.Context)
2962          << CSR
2963          << E->getSourceRange(),
2964        E->getLocStart(), /*IsStringLocation*/false, CSR);
2965
2966      checkForCStrMembers(AT, E, CSR);
2967    } else
2968      EmitFormatDiagnostic(
2969        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2970          << AT.getRepresentativeTypeName(S.Context) << ExprTy
2971          << CSR
2972          << E->getSourceRange(),
2973        E->getLocStart(), /*IsStringLocation*/false, CSR);
2974  }
2975
2976  return true;
2977}
2978
2979//===--- CHECK: Scanf format string checking ------------------------------===//
2980
2981namespace {
2982class CheckScanfHandler : public CheckFormatHandler {
2983public:
2984  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2985                    const Expr *origFormatExpr, unsigned firstDataArg,
2986                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
2987                    ArrayRef<const Expr *> Args,
2988                    unsigned formatIdx, bool inFunctionCall,
2989                    Sema::VariadicCallType CallType)
2990  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2991                       numDataArgs, beg, hasVAListArg,
2992                       Args, formatIdx, inFunctionCall, CallType)
2993  {}
2994
2995  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2996                            const char *startSpecifier,
2997                            unsigned specifierLen);
2998
2999  bool HandleInvalidScanfConversionSpecifier(
3000          const analyze_scanf::ScanfSpecifier &FS,
3001          const char *startSpecifier,
3002          unsigned specifierLen);
3003
3004  void HandleIncompleteScanList(const char *start, const char *end);
3005};
3006}
3007
3008void CheckScanfHandler::HandleIncompleteScanList(const char *start,
3009                                                 const char *end) {
3010  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
3011                       getLocationOfByte(end), /*IsStringLocation*/true,
3012                       getSpecifierRange(start, end - start));
3013}
3014
3015bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
3016                                        const analyze_scanf::ScanfSpecifier &FS,
3017                                        const char *startSpecifier,
3018                                        unsigned specifierLen) {
3019
3020  const analyze_scanf::ScanfConversionSpecifier &CS =
3021    FS.getConversionSpecifier();
3022
3023  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
3024                                          getLocationOfByte(CS.getStart()),
3025                                          startSpecifier, specifierLen,
3026                                          CS.getStart(), CS.getLength());
3027}
3028
3029bool CheckScanfHandler::HandleScanfSpecifier(
3030                                       const analyze_scanf::ScanfSpecifier &FS,
3031                                       const char *startSpecifier,
3032                                       unsigned specifierLen) {
3033
3034  using namespace analyze_scanf;
3035  using namespace analyze_format_string;
3036
3037  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
3038
3039  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
3040  // be used to decide if we are using positional arguments consistently.
3041  if (FS.consumesDataArgument()) {
3042    if (atFirstArg) {
3043      atFirstArg = false;
3044      usesPositionalArgs = FS.usesPositionalArg();
3045    }
3046    else if (usesPositionalArgs != FS.usesPositionalArg()) {
3047      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
3048                                        startSpecifier, specifierLen);
3049      return false;
3050    }
3051  }
3052
3053  // Check if the field with is non-zero.
3054  const OptionalAmount &Amt = FS.getFieldWidth();
3055  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
3056    if (Amt.getConstantAmount() == 0) {
3057      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
3058                                                   Amt.getConstantLength());
3059      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
3060                           getLocationOfByte(Amt.getStart()),
3061                           /*IsStringLocation*/true, R,
3062                           FixItHint::CreateRemoval(R));
3063    }
3064  }
3065
3066  if (!FS.consumesDataArgument()) {
3067    // FIXME: Technically specifying a precision or field width here
3068    // makes no sense.  Worth issuing a warning at some point.
3069    return true;
3070  }
3071
3072  // Consume the argument.
3073  unsigned argIndex = FS.getArgIndex();
3074  if (argIndex < NumDataArgs) {
3075      // The check to see if the argIndex is valid will come later.
3076      // We set the bit here because we may exit early from this
3077      // function if we encounter some other error.
3078    CoveredArgs.set(argIndex);
3079  }
3080
3081  // Check the length modifier is valid with the given conversion specifier.
3082  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
3083    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3084                                diag::warn_format_nonsensical_length);
3085  else if (!FS.hasStandardLengthModifier())
3086    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
3087  else if (!FS.hasStandardLengthConversionCombination())
3088    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3089                                diag::warn_format_non_standard_conversion_spec);
3090
3091  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
3092    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
3093
3094  // The remaining checks depend on the data arguments.
3095  if (HasVAListArg)
3096    return true;
3097
3098  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
3099    return false;
3100
3101  // Check that the argument type matches the format specifier.
3102  const Expr *Ex = getDataArg(argIndex);
3103  if (!Ex)
3104    return true;
3105
3106  const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
3107  if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType())) {
3108    ScanfSpecifier fixedFS = FS;
3109    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
3110                                   S.Context);
3111
3112    if (success) {
3113      // Get the fix string from the fixed format specifier.
3114      SmallString<128> buf;
3115      llvm::raw_svector_ostream os(buf);
3116      fixedFS.toString(os);
3117
3118      EmitFormatDiagnostic(
3119        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3120          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3121          << Ex->getSourceRange(),
3122        Ex->getLocStart(),
3123        /*IsStringLocation*/false,
3124        getSpecifierRange(startSpecifier, specifierLen),
3125        FixItHint::CreateReplacement(
3126          getSpecifierRange(startSpecifier, specifierLen),
3127          os.str()));
3128    } else {
3129      EmitFormatDiagnostic(
3130        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3131          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3132          << Ex->getSourceRange(),
3133        Ex->getLocStart(),
3134        /*IsStringLocation*/false,
3135        getSpecifierRange(startSpecifier, specifierLen));
3136    }
3137  }
3138
3139  return true;
3140}
3141
3142void Sema::CheckFormatString(const StringLiteral *FExpr,
3143                             const Expr *OrigFormatExpr,
3144                             ArrayRef<const Expr *> Args,
3145                             bool HasVAListArg, unsigned format_idx,
3146                             unsigned firstDataArg, FormatStringType Type,
3147                             bool inFunctionCall, VariadicCallType CallType) {
3148
3149  // CHECK: is the format string a wide literal?
3150  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
3151    CheckFormatHandler::EmitFormatDiagnostic(
3152      *this, inFunctionCall, Args[format_idx],
3153      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
3154      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3155    return;
3156  }
3157
3158  // Str - The format string.  NOTE: this is NOT null-terminated!
3159  StringRef StrRef = FExpr->getString();
3160  const char *Str = StrRef.data();
3161  unsigned StrLen = StrRef.size();
3162  const unsigned numDataArgs = Args.size() - firstDataArg;
3163
3164  // CHECK: empty format string?
3165  if (StrLen == 0 && numDataArgs > 0) {
3166    CheckFormatHandler::EmitFormatDiagnostic(
3167      *this, inFunctionCall, Args[format_idx],
3168      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
3169      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3170    return;
3171  }
3172
3173  if (Type == FST_Printf || Type == FST_NSString) {
3174    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
3175                         numDataArgs, (Type == FST_NSString),
3176                         Str, HasVAListArg, Args, format_idx,
3177                         inFunctionCall, CallType);
3178
3179    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
3180                                                  getLangOpts(),
3181                                                  Context.getTargetInfo()))
3182      H.DoneProcessing();
3183  } else if (Type == FST_Scanf) {
3184    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
3185                        Str, HasVAListArg, Args, format_idx,
3186                        inFunctionCall, CallType);
3187
3188    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
3189                                                 getLangOpts(),
3190                                                 Context.getTargetInfo()))
3191      H.DoneProcessing();
3192  } // TODO: handle other formats
3193}
3194
3195//===--- CHECK: Standard memory functions ---------------------------------===//
3196
3197/// \brief Determine whether the given type is a dynamic class type (e.g.,
3198/// whether it has a vtable).
3199static bool isDynamicClassType(QualType T) {
3200  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
3201    if (CXXRecordDecl *Definition = Record->getDefinition())
3202      if (Definition->isDynamicClass())
3203        return true;
3204
3205  return false;
3206}
3207
3208/// \brief If E is a sizeof expression, returns its argument expression,
3209/// otherwise returns NULL.
3210static const Expr *getSizeOfExprArg(const Expr* E) {
3211  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3212      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3213    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
3214      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
3215
3216  return 0;
3217}
3218
3219/// \brief If E is a sizeof expression, returns its argument type.
3220static QualType getSizeOfArgType(const Expr* E) {
3221  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3222      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3223    if (SizeOf->getKind() == clang::UETT_SizeOf)
3224      return SizeOf->getTypeOfArgument();
3225
3226  return QualType();
3227}
3228
3229/// \brief Check for dangerous or invalid arguments to memset().
3230///
3231/// This issues warnings on known problematic, dangerous or unspecified
3232/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
3233/// function calls.
3234///
3235/// \param Call The call expression to diagnose.
3236void Sema::CheckMemaccessArguments(const CallExpr *Call,
3237                                   unsigned BId,
3238                                   IdentifierInfo *FnName) {
3239  assert(BId != 0);
3240
3241  // It is possible to have a non-standard definition of memset.  Validate
3242  // we have enough arguments, and if not, abort further checking.
3243  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
3244  if (Call->getNumArgs() < ExpectedNumArgs)
3245    return;
3246
3247  unsigned LastArg = (BId == Builtin::BImemset ||
3248                      BId == Builtin::BIstrndup ? 1 : 2);
3249  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
3250  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
3251
3252  // We have special checking when the length is a sizeof expression.
3253  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
3254  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
3255  llvm::FoldingSetNodeID SizeOfArgID;
3256
3257  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
3258    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
3259    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
3260
3261    QualType DestTy = Dest->getType();
3262    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
3263      QualType PointeeTy = DestPtrTy->getPointeeType();
3264
3265      // Never warn about void type pointers. This can be used to suppress
3266      // false positives.
3267      if (PointeeTy->isVoidType())
3268        continue;
3269
3270      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
3271      // actually comparing the expressions for equality. Because computing the
3272      // expression IDs can be expensive, we only do this if the diagnostic is
3273      // enabled.
3274      if (SizeOfArg &&
3275          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
3276                                   SizeOfArg->getExprLoc())) {
3277        // We only compute IDs for expressions if the warning is enabled, and
3278        // cache the sizeof arg's ID.
3279        if (SizeOfArgID == llvm::FoldingSetNodeID())
3280          SizeOfArg->Profile(SizeOfArgID, Context, true);
3281        llvm::FoldingSetNodeID DestID;
3282        Dest->Profile(DestID, Context, true);
3283        if (DestID == SizeOfArgID) {
3284          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
3285          //       over sizeof(src) as well.
3286          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
3287          StringRef ReadableName = FnName->getName();
3288
3289          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
3290            if (UnaryOp->getOpcode() == UO_AddrOf)
3291              ActionIdx = 1; // If its an address-of operator, just remove it.
3292          if (!PointeeTy->isIncompleteType() &&
3293              (Context.getTypeSize(PointeeTy) == Context.getCharWidth()))
3294            ActionIdx = 2; // If the pointee's size is sizeof(char),
3295                           // suggest an explicit length.
3296
3297          // If the function is defined as a builtin macro, do not show macro
3298          // expansion.
3299          SourceLocation SL = SizeOfArg->getExprLoc();
3300          SourceRange DSR = Dest->getSourceRange();
3301          SourceRange SSR = SizeOfArg->getSourceRange();
3302          SourceManager &SM  = PP.getSourceManager();
3303
3304          if (SM.isMacroArgExpansion(SL)) {
3305            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
3306            SL = SM.getSpellingLoc(SL);
3307            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
3308                             SM.getSpellingLoc(DSR.getEnd()));
3309            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
3310                             SM.getSpellingLoc(SSR.getEnd()));
3311          }
3312
3313          DiagRuntimeBehavior(SL, SizeOfArg,
3314                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
3315                                << ReadableName
3316                                << PointeeTy
3317                                << DestTy
3318                                << DSR
3319                                << SSR);
3320          DiagRuntimeBehavior(SL, SizeOfArg,
3321                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
3322                                << ActionIdx
3323                                << SSR);
3324
3325          break;
3326        }
3327      }
3328
3329      // Also check for cases where the sizeof argument is the exact same
3330      // type as the memory argument, and where it points to a user-defined
3331      // record type.
3332      if (SizeOfArgTy != QualType()) {
3333        if (PointeeTy->isRecordType() &&
3334            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
3335          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
3336                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
3337                                << FnName << SizeOfArgTy << ArgIdx
3338                                << PointeeTy << Dest->getSourceRange()
3339                                << LenExpr->getSourceRange());
3340          break;
3341        }
3342      }
3343
3344      // Always complain about dynamic classes.
3345      if (isDynamicClassType(PointeeTy)) {
3346
3347        unsigned OperationType = 0;
3348        // "overwritten" if we're warning about the destination for any call
3349        // but memcmp; otherwise a verb appropriate to the call.
3350        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
3351          if (BId == Builtin::BImemcpy)
3352            OperationType = 1;
3353          else if(BId == Builtin::BImemmove)
3354            OperationType = 2;
3355          else if (BId == Builtin::BImemcmp)
3356            OperationType = 3;
3357        }
3358
3359        DiagRuntimeBehavior(
3360          Dest->getExprLoc(), Dest,
3361          PDiag(diag::warn_dyn_class_memaccess)
3362            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
3363            << FnName << PointeeTy
3364            << OperationType
3365            << Call->getCallee()->getSourceRange());
3366      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
3367               BId != Builtin::BImemset)
3368        DiagRuntimeBehavior(
3369          Dest->getExprLoc(), Dest,
3370          PDiag(diag::warn_arc_object_memaccess)
3371            << ArgIdx << FnName << PointeeTy
3372            << Call->getCallee()->getSourceRange());
3373      else
3374        continue;
3375
3376      DiagRuntimeBehavior(
3377        Dest->getExprLoc(), Dest,
3378        PDiag(diag::note_bad_memaccess_silence)
3379          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
3380      break;
3381    }
3382  }
3383}
3384
3385// A little helper routine: ignore addition and subtraction of integer literals.
3386// This intentionally does not ignore all integer constant expressions because
3387// we don't want to remove sizeof().
3388static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
3389  Ex = Ex->IgnoreParenCasts();
3390
3391  for (;;) {
3392    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
3393    if (!BO || !BO->isAdditiveOp())
3394      break;
3395
3396    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
3397    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
3398
3399    if (isa<IntegerLiteral>(RHS))
3400      Ex = LHS;
3401    else if (isa<IntegerLiteral>(LHS))
3402      Ex = RHS;
3403    else
3404      break;
3405  }
3406
3407  return Ex;
3408}
3409
3410static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
3411                                                      ASTContext &Context) {
3412  // Only handle constant-sized or VLAs, but not flexible members.
3413  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
3414    // Only issue the FIXIT for arrays of size > 1.
3415    if (CAT->getSize().getSExtValue() <= 1)
3416      return false;
3417  } else if (!Ty->isVariableArrayType()) {
3418    return false;
3419  }
3420  return true;
3421}
3422
3423// Warn if the user has made the 'size' argument to strlcpy or strlcat
3424// be the size of the source, instead of the destination.
3425void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
3426                                    IdentifierInfo *FnName) {
3427
3428  // Don't crash if the user has the wrong number of arguments
3429  if (Call->getNumArgs() != 3)
3430    return;
3431
3432  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
3433  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
3434  const Expr *CompareWithSrc = NULL;
3435
3436  // Look for 'strlcpy(dst, x, sizeof(x))'
3437  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
3438    CompareWithSrc = Ex;
3439  else {
3440    // Look for 'strlcpy(dst, x, strlen(x))'
3441    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
3442      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
3443          && SizeCall->getNumArgs() == 1)
3444        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
3445    }
3446  }
3447
3448  if (!CompareWithSrc)
3449    return;
3450
3451  // Determine if the argument to sizeof/strlen is equal to the source
3452  // argument.  In principle there's all kinds of things you could do
3453  // here, for instance creating an == expression and evaluating it with
3454  // EvaluateAsBooleanCondition, but this uses a more direct technique:
3455  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
3456  if (!SrcArgDRE)
3457    return;
3458
3459  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
3460  if (!CompareWithSrcDRE ||
3461      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
3462    return;
3463
3464  const Expr *OriginalSizeArg = Call->getArg(2);
3465  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
3466    << OriginalSizeArg->getSourceRange() << FnName;
3467
3468  // Output a FIXIT hint if the destination is an array (rather than a
3469  // pointer to an array).  This could be enhanced to handle some
3470  // pointers if we know the actual size, like if DstArg is 'array+2'
3471  // we could say 'sizeof(array)-2'.
3472  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
3473  if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
3474    return;
3475
3476  SmallString<128> sizeString;
3477  llvm::raw_svector_ostream OS(sizeString);
3478  OS << "sizeof(";
3479  DstArg->printPretty(OS, 0, getPrintingPolicy());
3480  OS << ")";
3481
3482  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
3483    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
3484                                    OS.str());
3485}
3486
3487/// Check if two expressions refer to the same declaration.
3488static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
3489  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
3490    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
3491      return D1->getDecl() == D2->getDecl();
3492  return false;
3493}
3494
3495static const Expr *getStrlenExprArg(const Expr *E) {
3496  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
3497    const FunctionDecl *FD = CE->getDirectCallee();
3498    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
3499      return 0;
3500    return CE->getArg(0)->IgnoreParenCasts();
3501  }
3502  return 0;
3503}
3504
3505// Warn on anti-patterns as the 'size' argument to strncat.
3506// The correct size argument should look like following:
3507//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
3508void Sema::CheckStrncatArguments(const CallExpr *CE,
3509                                 IdentifierInfo *FnName) {
3510  // Don't crash if the user has the wrong number of arguments.
3511  if (CE->getNumArgs() < 3)
3512    return;
3513  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
3514  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
3515  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
3516
3517  // Identify common expressions, which are wrongly used as the size argument
3518  // to strncat and may lead to buffer overflows.
3519  unsigned PatternType = 0;
3520  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
3521    // - sizeof(dst)
3522    if (referToTheSameDecl(SizeOfArg, DstArg))
3523      PatternType = 1;
3524    // - sizeof(src)
3525    else if (referToTheSameDecl(SizeOfArg, SrcArg))
3526      PatternType = 2;
3527  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
3528    if (BE->getOpcode() == BO_Sub) {
3529      const Expr *L = BE->getLHS()->IgnoreParenCasts();
3530      const Expr *R = BE->getRHS()->IgnoreParenCasts();
3531      // - sizeof(dst) - strlen(dst)
3532      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
3533          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
3534        PatternType = 1;
3535      // - sizeof(src) - (anything)
3536      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
3537        PatternType = 2;
3538    }
3539  }
3540
3541  if (PatternType == 0)
3542    return;
3543
3544  // Generate the diagnostic.
3545  SourceLocation SL = LenArg->getLocStart();
3546  SourceRange SR = LenArg->getSourceRange();
3547  SourceManager &SM  = PP.getSourceManager();
3548
3549  // If the function is defined as a builtin macro, do not show macro expansion.
3550  if (SM.isMacroArgExpansion(SL)) {
3551    SL = SM.getSpellingLoc(SL);
3552    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
3553                     SM.getSpellingLoc(SR.getEnd()));
3554  }
3555
3556  // Check if the destination is an array (rather than a pointer to an array).
3557  QualType DstTy = DstArg->getType();
3558  bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
3559                                                                    Context);
3560  if (!isKnownSizeArray) {
3561    if (PatternType == 1)
3562      Diag(SL, diag::warn_strncat_wrong_size) << SR;
3563    else
3564      Diag(SL, diag::warn_strncat_src_size) << SR;
3565    return;
3566  }
3567
3568  if (PatternType == 1)
3569    Diag(SL, diag::warn_strncat_large_size) << SR;
3570  else
3571    Diag(SL, diag::warn_strncat_src_size) << SR;
3572
3573  SmallString<128> sizeString;
3574  llvm::raw_svector_ostream OS(sizeString);
3575  OS << "sizeof(";
3576  DstArg->printPretty(OS, 0, getPrintingPolicy());
3577  OS << ") - ";
3578  OS << "strlen(";
3579  DstArg->printPretty(OS, 0, getPrintingPolicy());
3580  OS << ") - 1";
3581
3582  Diag(SL, diag::note_strncat_wrong_size)
3583    << FixItHint::CreateReplacement(SR, OS.str());
3584}
3585
3586//===--- CHECK: Return Address of Stack Variable --------------------------===//
3587
3588static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3589                     Decl *ParentDecl);
3590static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3591                      Decl *ParentDecl);
3592
3593/// CheckReturnStackAddr - Check if a return statement returns the address
3594///   of a stack variable.
3595void
3596Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3597                           SourceLocation ReturnLoc) {
3598
3599  Expr *stackE = 0;
3600  SmallVector<DeclRefExpr *, 8> refVars;
3601
3602  // Perform checking for returned stack addresses, local blocks,
3603  // label addresses or references to temporaries.
3604  if (lhsType->isPointerType() ||
3605      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3606    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3607  } else if (lhsType->isReferenceType()) {
3608    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3609  }
3610
3611  if (stackE == 0)
3612    return; // Nothing suspicious was found.
3613
3614  SourceLocation diagLoc;
3615  SourceRange diagRange;
3616  if (refVars.empty()) {
3617    diagLoc = stackE->getLocStart();
3618    diagRange = stackE->getSourceRange();
3619  } else {
3620    // We followed through a reference variable. 'stackE' contains the
3621    // problematic expression but we will warn at the return statement pointing
3622    // at the reference variable. We will later display the "trail" of
3623    // reference variables using notes.
3624    diagLoc = refVars[0]->getLocStart();
3625    diagRange = refVars[0]->getSourceRange();
3626  }
3627
3628  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3629    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3630                                             : diag::warn_ret_stack_addr)
3631     << DR->getDecl()->getDeclName() << diagRange;
3632  } else if (isa<BlockExpr>(stackE)) { // local block.
3633    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3634  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3635    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3636  } else { // local temporary.
3637    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3638                                             : diag::warn_ret_local_temp_addr)
3639     << diagRange;
3640  }
3641
3642  // Display the "trail" of reference variables that we followed until we
3643  // found the problematic expression using notes.
3644  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3645    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3646    // If this var binds to another reference var, show the range of the next
3647    // var, otherwise the var binds to the problematic expression, in which case
3648    // show the range of the expression.
3649    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3650                                  : stackE->getSourceRange();
3651    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3652      << VD->getDeclName() << range;
3653  }
3654}
3655
3656/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3657///  check if the expression in a return statement evaluates to an address
3658///  to a location on the stack, a local block, an address of a label, or a
3659///  reference to local temporary. The recursion is used to traverse the
3660///  AST of the return expression, with recursion backtracking when we
3661///  encounter a subexpression that (1) clearly does not lead to one of the
3662///  above problematic expressions (2) is something we cannot determine leads to
3663///  a problematic expression based on such local checking.
3664///
3665///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3666///  the expression that they point to. Such variables are added to the
3667///  'refVars' vector so that we know what the reference variable "trail" was.
3668///
3669///  EvalAddr processes expressions that are pointers that are used as
3670///  references (and not L-values).  EvalVal handles all other values.
3671///  At the base case of the recursion is a check for the above problematic
3672///  expressions.
3673///
3674///  This implementation handles:
3675///
3676///   * pointer-to-pointer casts
3677///   * implicit conversions from array references to pointers
3678///   * taking the address of fields
3679///   * arbitrary interplay between "&" and "*" operators
3680///   * pointer arithmetic from an address of a stack variable
3681///   * taking the address of an array element where the array is on the stack
3682static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3683                      Decl *ParentDecl) {
3684  if (E->isTypeDependent())
3685      return NULL;
3686
3687  // We should only be called for evaluating pointer expressions.
3688  assert((E->getType()->isAnyPointerType() ||
3689          E->getType()->isBlockPointerType() ||
3690          E->getType()->isObjCQualifiedIdType()) &&
3691         "EvalAddr only works on pointers");
3692
3693  E = E->IgnoreParens();
3694
3695  // Our "symbolic interpreter" is just a dispatch off the currently
3696  // viewed AST node.  We then recursively traverse the AST by calling
3697  // EvalAddr and EvalVal appropriately.
3698  switch (E->getStmtClass()) {
3699  case Stmt::DeclRefExprClass: {
3700    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3701
3702    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3703      // If this is a reference variable, follow through to the expression that
3704      // it points to.
3705      if (V->hasLocalStorage() &&
3706          V->getType()->isReferenceType() && V->hasInit()) {
3707        // Add the reference variable to the "trail".
3708        refVars.push_back(DR);
3709        return EvalAddr(V->getInit(), refVars, ParentDecl);
3710      }
3711
3712    return NULL;
3713  }
3714
3715  case Stmt::UnaryOperatorClass: {
3716    // The only unary operator that make sense to handle here
3717    // is AddrOf.  All others don't make sense as pointers.
3718    UnaryOperator *U = cast<UnaryOperator>(E);
3719
3720    if (U->getOpcode() == UO_AddrOf)
3721      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3722    else
3723      return NULL;
3724  }
3725
3726  case Stmt::BinaryOperatorClass: {
3727    // Handle pointer arithmetic.  All other binary operators are not valid
3728    // in this context.
3729    BinaryOperator *B = cast<BinaryOperator>(E);
3730    BinaryOperatorKind op = B->getOpcode();
3731
3732    if (op != BO_Add && op != BO_Sub)
3733      return NULL;
3734
3735    Expr *Base = B->getLHS();
3736
3737    // Determine which argument is the real pointer base.  It could be
3738    // the RHS argument instead of the LHS.
3739    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3740
3741    assert (Base->getType()->isPointerType());
3742    return EvalAddr(Base, refVars, ParentDecl);
3743  }
3744
3745  // For conditional operators we need to see if either the LHS or RHS are
3746  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3747  case Stmt::ConditionalOperatorClass: {
3748    ConditionalOperator *C = cast<ConditionalOperator>(E);
3749
3750    // Handle the GNU extension for missing LHS.
3751    if (Expr *lhsExpr = C->getLHS()) {
3752    // In C++, we can have a throw-expression, which has 'void' type.
3753      if (!lhsExpr->getType()->isVoidType())
3754        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3755          return LHS;
3756    }
3757
3758    // In C++, we can have a throw-expression, which has 'void' type.
3759    if (C->getRHS()->getType()->isVoidType())
3760      return NULL;
3761
3762    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3763  }
3764
3765  case Stmt::BlockExprClass:
3766    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3767      return E; // local block.
3768    return NULL;
3769
3770  case Stmt::AddrLabelExprClass:
3771    return E; // address of label.
3772
3773  case Stmt::ExprWithCleanupsClass:
3774    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3775                    ParentDecl);
3776
3777  // For casts, we need to handle conversions from arrays to
3778  // pointer values, and pointer-to-pointer conversions.
3779  case Stmt::ImplicitCastExprClass:
3780  case Stmt::CStyleCastExprClass:
3781  case Stmt::CXXFunctionalCastExprClass:
3782  case Stmt::ObjCBridgedCastExprClass:
3783  case Stmt::CXXStaticCastExprClass:
3784  case Stmt::CXXDynamicCastExprClass:
3785  case Stmt::CXXConstCastExprClass:
3786  case Stmt::CXXReinterpretCastExprClass: {
3787    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3788    switch (cast<CastExpr>(E)->getCastKind()) {
3789    case CK_BitCast:
3790    case CK_LValueToRValue:
3791    case CK_NoOp:
3792    case CK_BaseToDerived:
3793    case CK_DerivedToBase:
3794    case CK_UncheckedDerivedToBase:
3795    case CK_Dynamic:
3796    case CK_CPointerToObjCPointerCast:
3797    case CK_BlockPointerToObjCPointerCast:
3798    case CK_AnyPointerToBlockPointerCast:
3799      return EvalAddr(SubExpr, refVars, ParentDecl);
3800
3801    case CK_ArrayToPointerDecay:
3802      return EvalVal(SubExpr, refVars, ParentDecl);
3803
3804    default:
3805      return 0;
3806    }
3807  }
3808
3809  case Stmt::MaterializeTemporaryExprClass:
3810    if (Expr *Result = EvalAddr(
3811                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3812                                refVars, ParentDecl))
3813      return Result;
3814
3815    return E;
3816
3817  // Everything else: we simply don't reason about them.
3818  default:
3819    return NULL;
3820  }
3821}
3822
3823
3824///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3825///   See the comments for EvalAddr for more details.
3826static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3827                     Decl *ParentDecl) {
3828do {
3829  // We should only be called for evaluating non-pointer expressions, or
3830  // expressions with a pointer type that are not used as references but instead
3831  // are l-values (e.g., DeclRefExpr with a pointer type).
3832
3833  // Our "symbolic interpreter" is just a dispatch off the currently
3834  // viewed AST node.  We then recursively traverse the AST by calling
3835  // EvalAddr and EvalVal appropriately.
3836
3837  E = E->IgnoreParens();
3838  switch (E->getStmtClass()) {
3839  case Stmt::ImplicitCastExprClass: {
3840    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3841    if (IE->getValueKind() == VK_LValue) {
3842      E = IE->getSubExpr();
3843      continue;
3844    }
3845    return NULL;
3846  }
3847
3848  case Stmt::ExprWithCleanupsClass:
3849    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3850
3851  case Stmt::DeclRefExprClass: {
3852    // When we hit a DeclRefExpr we are looking at code that refers to a
3853    // variable's name. If it's not a reference variable we check if it has
3854    // local storage within the function, and if so, return the expression.
3855    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3856
3857    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3858      // Check if it refers to itself, e.g. "int& i = i;".
3859      if (V == ParentDecl)
3860        return DR;
3861
3862      if (V->hasLocalStorage()) {
3863        if (!V->getType()->isReferenceType())
3864          return DR;
3865
3866        // Reference variable, follow through to the expression that
3867        // it points to.
3868        if (V->hasInit()) {
3869          // Add the reference variable to the "trail".
3870          refVars.push_back(DR);
3871          return EvalVal(V->getInit(), refVars, V);
3872        }
3873      }
3874    }
3875
3876    return NULL;
3877  }
3878
3879  case Stmt::UnaryOperatorClass: {
3880    // The only unary operator that make sense to handle here
3881    // is Deref.  All others don't resolve to a "name."  This includes
3882    // handling all sorts of rvalues passed to a unary operator.
3883    UnaryOperator *U = cast<UnaryOperator>(E);
3884
3885    if (U->getOpcode() == UO_Deref)
3886      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3887
3888    return NULL;
3889  }
3890
3891  case Stmt::ArraySubscriptExprClass: {
3892    // Array subscripts are potential references to data on the stack.  We
3893    // retrieve the DeclRefExpr* for the array variable if it indeed
3894    // has local storage.
3895    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3896  }
3897
3898  case Stmt::ConditionalOperatorClass: {
3899    // For conditional operators we need to see if either the LHS or RHS are
3900    // non-NULL Expr's.  If one is non-NULL, we return it.
3901    ConditionalOperator *C = cast<ConditionalOperator>(E);
3902
3903    // Handle the GNU extension for missing LHS.
3904    if (Expr *lhsExpr = C->getLHS())
3905      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3906        return LHS;
3907
3908    return EvalVal(C->getRHS(), refVars, ParentDecl);
3909  }
3910
3911  // Accesses to members are potential references to data on the stack.
3912  case Stmt::MemberExprClass: {
3913    MemberExpr *M = cast<MemberExpr>(E);
3914
3915    // Check for indirect access.  We only want direct field accesses.
3916    if (M->isArrow())
3917      return NULL;
3918
3919    // Check whether the member type is itself a reference, in which case
3920    // we're not going to refer to the member, but to what the member refers to.
3921    if (M->getMemberDecl()->getType()->isReferenceType())
3922      return NULL;
3923
3924    return EvalVal(M->getBase(), refVars, ParentDecl);
3925  }
3926
3927  case Stmt::MaterializeTemporaryExprClass:
3928    if (Expr *Result = EvalVal(
3929                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3930                               refVars, ParentDecl))
3931      return Result;
3932
3933    return E;
3934
3935  default:
3936    // Check that we don't return or take the address of a reference to a
3937    // temporary. This is only useful in C++.
3938    if (!E->isTypeDependent() && E->isRValue())
3939      return E;
3940
3941    // Everything else: we simply don't reason about them.
3942    return NULL;
3943  }
3944} while (true);
3945}
3946
3947//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3948
3949/// Check for comparisons of floating point operands using != and ==.
3950/// Issue a warning if these are no self-comparisons, as they are not likely
3951/// to do what the programmer intended.
3952void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3953  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3954  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3955
3956  // Special case: check for x == x (which is OK).
3957  // Do not emit warnings for such cases.
3958  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3959    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3960      if (DRL->getDecl() == DRR->getDecl())
3961        return;
3962
3963
3964  // Special case: check for comparisons against literals that can be exactly
3965  //  represented by APFloat.  In such cases, do not emit a warning.  This
3966  //  is a heuristic: often comparison against such literals are used to
3967  //  detect if a value in a variable has not changed.  This clearly can
3968  //  lead to false negatives.
3969  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3970    if (FLL->isExact())
3971      return;
3972  } else
3973    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
3974      if (FLR->isExact())
3975        return;
3976
3977  // Check for comparisons with builtin types.
3978  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3979    if (CL->isBuiltinCall())
3980      return;
3981
3982  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3983    if (CR->isBuiltinCall())
3984      return;
3985
3986  // Emit the diagnostic.
3987  Diag(Loc, diag::warn_floatingpoint_eq)
3988    << LHS->getSourceRange() << RHS->getSourceRange();
3989}
3990
3991//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3992//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3993
3994namespace {
3995
3996/// Structure recording the 'active' range of an integer-valued
3997/// expression.
3998struct IntRange {
3999  /// The number of bits active in the int.
4000  unsigned Width;
4001
4002  /// True if the int is known not to have negative values.
4003  bool NonNegative;
4004
4005  IntRange(unsigned Width, bool NonNegative)
4006    : Width(Width), NonNegative(NonNegative)
4007  {}
4008
4009  /// Returns the range of the bool type.
4010  static IntRange forBoolType() {
4011    return IntRange(1, true);
4012  }
4013
4014  /// Returns the range of an opaque value of the given integral type.
4015  static IntRange forValueOfType(ASTContext &C, QualType T) {
4016    return forValueOfCanonicalType(C,
4017                          T->getCanonicalTypeInternal().getTypePtr());
4018  }
4019
4020  /// Returns the range of an opaque value of a canonical integral type.
4021  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
4022    assert(T->isCanonicalUnqualified());
4023
4024    if (const VectorType *VT = dyn_cast<VectorType>(T))
4025      T = VT->getElementType().getTypePtr();
4026    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4027      T = CT->getElementType().getTypePtr();
4028
4029    // For enum types, use the known bit width of the enumerators.
4030    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
4031      EnumDecl *Enum = ET->getDecl();
4032      if (!Enum->isCompleteDefinition())
4033        return IntRange(C.getIntWidth(QualType(T, 0)), false);
4034
4035      unsigned NumPositive = Enum->getNumPositiveBits();
4036      unsigned NumNegative = Enum->getNumNegativeBits();
4037
4038      if (NumNegative == 0)
4039        return IntRange(NumPositive, true/*NonNegative*/);
4040      else
4041        return IntRange(std::max(NumPositive + 1, NumNegative),
4042                        false/*NonNegative*/);
4043    }
4044
4045    const BuiltinType *BT = cast<BuiltinType>(T);
4046    assert(BT->isInteger());
4047
4048    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4049  }
4050
4051  /// Returns the "target" range of a canonical integral type, i.e.
4052  /// the range of values expressible in the type.
4053  ///
4054  /// This matches forValueOfCanonicalType except that enums have the
4055  /// full range of their type, not the range of their enumerators.
4056  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
4057    assert(T->isCanonicalUnqualified());
4058
4059    if (const VectorType *VT = dyn_cast<VectorType>(T))
4060      T = VT->getElementType().getTypePtr();
4061    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4062      T = CT->getElementType().getTypePtr();
4063    if (const EnumType *ET = dyn_cast<EnumType>(T))
4064      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
4065
4066    const BuiltinType *BT = cast<BuiltinType>(T);
4067    assert(BT->isInteger());
4068
4069    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4070  }
4071
4072  /// Returns the supremum of two ranges: i.e. their conservative merge.
4073  static IntRange join(IntRange L, IntRange R) {
4074    return IntRange(std::max(L.Width, R.Width),
4075                    L.NonNegative && R.NonNegative);
4076  }
4077
4078  /// Returns the infinum of two ranges: i.e. their aggressive merge.
4079  static IntRange meet(IntRange L, IntRange R) {
4080    return IntRange(std::min(L.Width, R.Width),
4081                    L.NonNegative || R.NonNegative);
4082  }
4083};
4084
4085static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
4086                              unsigned MaxWidth) {
4087  if (value.isSigned() && value.isNegative())
4088    return IntRange(value.getMinSignedBits(), false);
4089
4090  if (value.getBitWidth() > MaxWidth)
4091    value = value.trunc(MaxWidth);
4092
4093  // isNonNegative() just checks the sign bit without considering
4094  // signedness.
4095  return IntRange(value.getActiveBits(), true);
4096}
4097
4098static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
4099                              unsigned MaxWidth) {
4100  if (result.isInt())
4101    return GetValueRange(C, result.getInt(), MaxWidth);
4102
4103  if (result.isVector()) {
4104    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
4105    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
4106      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
4107      R = IntRange::join(R, El);
4108    }
4109    return R;
4110  }
4111
4112  if (result.isComplexInt()) {
4113    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
4114    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
4115    return IntRange::join(R, I);
4116  }
4117
4118  // This can happen with lossless casts to intptr_t of "based" lvalues.
4119  // Assume it might use arbitrary bits.
4120  // FIXME: The only reason we need to pass the type in here is to get
4121  // the sign right on this one case.  It would be nice if APValue
4122  // preserved this.
4123  assert(result.isLValue() || result.isAddrLabelDiff());
4124  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
4125}
4126
4127/// Pseudo-evaluate the given integer expression, estimating the
4128/// range of values it might take.
4129///
4130/// \param MaxWidth - the width to which the value will be truncated
4131static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
4132  E = E->IgnoreParens();
4133
4134  // Try a full evaluation first.
4135  Expr::EvalResult result;
4136  if (E->EvaluateAsRValue(result, C))
4137    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
4138
4139  // I think we only want to look through implicit casts here; if the
4140  // user has an explicit widening cast, we should treat the value as
4141  // being of the new, wider type.
4142  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
4143    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
4144      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
4145
4146    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
4147
4148    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
4149
4150    // Assume that non-integer casts can span the full range of the type.
4151    if (!isIntegerCast)
4152      return OutputTypeRange;
4153
4154    IntRange SubRange
4155      = GetExprRange(C, CE->getSubExpr(),
4156                     std::min(MaxWidth, OutputTypeRange.Width));
4157
4158    // Bail out if the subexpr's range is as wide as the cast type.
4159    if (SubRange.Width >= OutputTypeRange.Width)
4160      return OutputTypeRange;
4161
4162    // Otherwise, we take the smaller width, and we're non-negative if
4163    // either the output type or the subexpr is.
4164    return IntRange(SubRange.Width,
4165                    SubRange.NonNegative || OutputTypeRange.NonNegative);
4166  }
4167
4168  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
4169    // If we can fold the condition, just take that operand.
4170    bool CondResult;
4171    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
4172      return GetExprRange(C, CondResult ? CO->getTrueExpr()
4173                                        : CO->getFalseExpr(),
4174                          MaxWidth);
4175
4176    // Otherwise, conservatively merge.
4177    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
4178    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
4179    return IntRange::join(L, R);
4180  }
4181
4182  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4183    switch (BO->getOpcode()) {
4184
4185    // Boolean-valued operations are single-bit and positive.
4186    case BO_LAnd:
4187    case BO_LOr:
4188    case BO_LT:
4189    case BO_GT:
4190    case BO_LE:
4191    case BO_GE:
4192    case BO_EQ:
4193    case BO_NE:
4194      return IntRange::forBoolType();
4195
4196    // The type of the assignments is the type of the LHS, so the RHS
4197    // is not necessarily the same type.
4198    case BO_MulAssign:
4199    case BO_DivAssign:
4200    case BO_RemAssign:
4201    case BO_AddAssign:
4202    case BO_SubAssign:
4203    case BO_XorAssign:
4204    case BO_OrAssign:
4205      // TODO: bitfields?
4206      return IntRange::forValueOfType(C, E->getType());
4207
4208    // Simple assignments just pass through the RHS, which will have
4209    // been coerced to the LHS type.
4210    case BO_Assign:
4211      // TODO: bitfields?
4212      return GetExprRange(C, BO->getRHS(), MaxWidth);
4213
4214    // Operations with opaque sources are black-listed.
4215    case BO_PtrMemD:
4216    case BO_PtrMemI:
4217      return IntRange::forValueOfType(C, E->getType());
4218
4219    // Bitwise-and uses the *infinum* of the two source ranges.
4220    case BO_And:
4221    case BO_AndAssign:
4222      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
4223                            GetExprRange(C, BO->getRHS(), MaxWidth));
4224
4225    // Left shift gets black-listed based on a judgement call.
4226    case BO_Shl:
4227      // ...except that we want to treat '1 << (blah)' as logically
4228      // positive.  It's an important idiom.
4229      if (IntegerLiteral *I
4230            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
4231        if (I->getValue() == 1) {
4232          IntRange R = IntRange::forValueOfType(C, E->getType());
4233          return IntRange(R.Width, /*NonNegative*/ true);
4234        }
4235      }
4236      // fallthrough
4237
4238    case BO_ShlAssign:
4239      return IntRange::forValueOfType(C, E->getType());
4240
4241    // Right shift by a constant can narrow its left argument.
4242    case BO_Shr:
4243    case BO_ShrAssign: {
4244      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4245
4246      // If the shift amount is a positive constant, drop the width by
4247      // that much.
4248      llvm::APSInt shift;
4249      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
4250          shift.isNonNegative()) {
4251        unsigned zext = shift.getZExtValue();
4252        if (zext >= L.Width)
4253          L.Width = (L.NonNegative ? 0 : 1);
4254        else
4255          L.Width -= zext;
4256      }
4257
4258      return L;
4259    }
4260
4261    // Comma acts as its right operand.
4262    case BO_Comma:
4263      return GetExprRange(C, BO->getRHS(), MaxWidth);
4264
4265    // Black-list pointer subtractions.
4266    case BO_Sub:
4267      if (BO->getLHS()->getType()->isPointerType())
4268        return IntRange::forValueOfType(C, E->getType());
4269      break;
4270
4271    // The width of a division result is mostly determined by the size
4272    // of the LHS.
4273    case BO_Div: {
4274      // Don't 'pre-truncate' the operands.
4275      unsigned opWidth = C.getIntWidth(E->getType());
4276      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4277
4278      // If the divisor is constant, use that.
4279      llvm::APSInt divisor;
4280      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
4281        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
4282        if (log2 >= L.Width)
4283          L.Width = (L.NonNegative ? 0 : 1);
4284        else
4285          L.Width = std::min(L.Width - log2, MaxWidth);
4286        return L;
4287      }
4288
4289      // Otherwise, just use the LHS's width.
4290      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4291      return IntRange(L.Width, L.NonNegative && R.NonNegative);
4292    }
4293
4294    // The result of a remainder can't be larger than the result of
4295    // either side.
4296    case BO_Rem: {
4297      // Don't 'pre-truncate' the operands.
4298      unsigned opWidth = C.getIntWidth(E->getType());
4299      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4300      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4301
4302      IntRange meet = IntRange::meet(L, R);
4303      meet.Width = std::min(meet.Width, MaxWidth);
4304      return meet;
4305    }
4306
4307    // The default behavior is okay for these.
4308    case BO_Mul:
4309    case BO_Add:
4310    case BO_Xor:
4311    case BO_Or:
4312      break;
4313    }
4314
4315    // The default case is to treat the operation as if it were closed
4316    // on the narrowest type that encompasses both operands.
4317    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4318    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
4319    return IntRange::join(L, R);
4320  }
4321
4322  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
4323    switch (UO->getOpcode()) {
4324    // Boolean-valued operations are white-listed.
4325    case UO_LNot:
4326      return IntRange::forBoolType();
4327
4328    // Operations with opaque sources are black-listed.
4329    case UO_Deref:
4330    case UO_AddrOf: // should be impossible
4331      return IntRange::forValueOfType(C, E->getType());
4332
4333    default:
4334      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
4335    }
4336  }
4337
4338  if (dyn_cast<OffsetOfExpr>(E)) {
4339    IntRange::forValueOfType(C, E->getType());
4340  }
4341
4342  if (FieldDecl *BitField = E->getSourceBitField())
4343    return IntRange(BitField->getBitWidthValue(C),
4344                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
4345
4346  return IntRange::forValueOfType(C, E->getType());
4347}
4348
4349static IntRange GetExprRange(ASTContext &C, Expr *E) {
4350  return GetExprRange(C, E, C.getIntWidth(E->getType()));
4351}
4352
4353/// Checks whether the given value, which currently has the given
4354/// source semantics, has the same value when coerced through the
4355/// target semantics.
4356static bool IsSameFloatAfterCast(const llvm::APFloat &value,
4357                                 const llvm::fltSemantics &Src,
4358                                 const llvm::fltSemantics &Tgt) {
4359  llvm::APFloat truncated = value;
4360
4361  bool ignored;
4362  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
4363  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
4364
4365  return truncated.bitwiseIsEqual(value);
4366}
4367
4368/// Checks whether the given value, which currently has the given
4369/// source semantics, has the same value when coerced through the
4370/// target semantics.
4371///
4372/// The value might be a vector of floats (or a complex number).
4373static bool IsSameFloatAfterCast(const APValue &value,
4374                                 const llvm::fltSemantics &Src,
4375                                 const llvm::fltSemantics &Tgt) {
4376  if (value.isFloat())
4377    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
4378
4379  if (value.isVector()) {
4380    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
4381      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
4382        return false;
4383    return true;
4384  }
4385
4386  assert(value.isComplexFloat());
4387  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
4388          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
4389}
4390
4391static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
4392
4393static bool IsZero(Sema &S, Expr *E) {
4394  // Suppress cases where we are comparing against an enum constant.
4395  if (const DeclRefExpr *DR =
4396      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
4397    if (isa<EnumConstantDecl>(DR->getDecl()))
4398      return false;
4399
4400  // Suppress cases where the '0' value is expanded from a macro.
4401  if (E->getLocStart().isMacroID())
4402    return false;
4403
4404  llvm::APSInt Value;
4405  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
4406}
4407
4408static bool HasEnumType(Expr *E) {
4409  // Strip off implicit integral promotions.
4410  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
4411    if (ICE->getCastKind() != CK_IntegralCast &&
4412        ICE->getCastKind() != CK_NoOp)
4413      break;
4414    E = ICE->getSubExpr();
4415  }
4416
4417  return E->getType()->isEnumeralType();
4418}
4419
4420static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
4421  BinaryOperatorKind op = E->getOpcode();
4422  if (E->isValueDependent())
4423    return;
4424
4425  if (op == BO_LT && IsZero(S, E->getRHS())) {
4426    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4427      << "< 0" << "false" << HasEnumType(E->getLHS())
4428      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4429  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
4430    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4431      << ">= 0" << "true" << HasEnumType(E->getLHS())
4432      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4433  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
4434    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4435      << "0 >" << "false" << HasEnumType(E->getRHS())
4436      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4437  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
4438    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4439      << "0 <=" << "true" << HasEnumType(E->getRHS())
4440      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4441  }
4442}
4443
4444static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
4445                                         Expr *Constant, Expr *Other,
4446                                         llvm::APSInt Value,
4447                                         bool RhsConstant) {
4448  // 0 values are handled later by CheckTrivialUnsignedComparison().
4449  if (Value == 0)
4450    return;
4451
4452  BinaryOperatorKind op = E->getOpcode();
4453  QualType OtherT = Other->getType();
4454  QualType ConstantT = Constant->getType();
4455  QualType CommonT = E->getLHS()->getType();
4456  if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
4457    return;
4458  assert((OtherT->isIntegerType() && ConstantT->isIntegerType())
4459         && "comparison with non-integer type");
4460
4461  bool ConstantSigned = ConstantT->isSignedIntegerType();
4462  bool CommonSigned = CommonT->isSignedIntegerType();
4463
4464  bool EqualityOnly = false;
4465
4466  // TODO: Investigate using GetExprRange() to get tighter bounds on
4467  // on the bit ranges.
4468  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
4469  unsigned OtherWidth = OtherRange.Width;
4470
4471  if (CommonSigned) {
4472    // The common type is signed, therefore no signed to unsigned conversion.
4473    if (!OtherRange.NonNegative) {
4474      // Check that the constant is representable in type OtherT.
4475      if (ConstantSigned) {
4476        if (OtherWidth >= Value.getMinSignedBits())
4477          return;
4478      } else { // !ConstantSigned
4479        if (OtherWidth >= Value.getActiveBits() + 1)
4480          return;
4481      }
4482    } else { // !OtherSigned
4483      // Check that the constant is representable in type OtherT.
4484      // Negative values are out of range.
4485      if (ConstantSigned) {
4486        if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
4487          return;
4488      } else { // !ConstantSigned
4489        if (OtherWidth >= Value.getActiveBits())
4490          return;
4491      }
4492    }
4493  } else {  // !CommonSigned
4494    if (OtherRange.NonNegative) {
4495      if (OtherWidth >= Value.getActiveBits())
4496        return;
4497    } else if (!OtherRange.NonNegative && !ConstantSigned) {
4498      // Check to see if the constant is representable in OtherT.
4499      if (OtherWidth > Value.getActiveBits())
4500        return;
4501      // Check to see if the constant is equivalent to a negative value
4502      // cast to CommonT.
4503      if (S.Context.getIntWidth(ConstantT) == S.Context.getIntWidth(CommonT) &&
4504          Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
4505        return;
4506      // The constant value rests between values that OtherT can represent after
4507      // conversion.  Relational comparison still works, but equality
4508      // comparisons will be tautological.
4509      EqualityOnly = true;
4510    } else { // OtherSigned && ConstantSigned
4511      assert(0 && "Two signed types converted to unsigned types.");
4512    }
4513  }
4514
4515  bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
4516
4517  bool IsTrue = true;
4518  if (op == BO_EQ || op == BO_NE) {
4519    IsTrue = op == BO_NE;
4520  } else if (EqualityOnly) {
4521    return;
4522  } else if (RhsConstant) {
4523    if (op == BO_GT || op == BO_GE)
4524      IsTrue = !PositiveConstant;
4525    else // op == BO_LT || op == BO_LE
4526      IsTrue = PositiveConstant;
4527  } else {
4528    if (op == BO_LT || op == BO_LE)
4529      IsTrue = !PositiveConstant;
4530    else // op == BO_GT || op == BO_GE
4531      IsTrue = PositiveConstant;
4532  }
4533
4534  // If this is a comparison to an enum constant, include that
4535  // constant in the diagnostic.
4536  const EnumConstantDecl *ED = 0;
4537  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
4538    ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
4539
4540  SmallString<64> PrettySourceValue;
4541  llvm::raw_svector_ostream OS(PrettySourceValue);
4542  if (ED)
4543    OS << '\'' << *ED << "' (" << Value << ")";
4544  else
4545    OS << Value;
4546
4547  S.Diag(E->getOperatorLoc(), diag::warn_out_of_range_compare)
4548      << OS.str() << OtherT << IsTrue
4549      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4550}
4551
4552/// Analyze the operands of the given comparison.  Implements the
4553/// fallback case from AnalyzeComparison.
4554static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
4555  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4556  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4557}
4558
4559/// \brief Implements -Wsign-compare.
4560///
4561/// \param E the binary operator to check for warnings
4562static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
4563  // The type the comparison is being performed in.
4564  QualType T = E->getLHS()->getType();
4565  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
4566         && "comparison with mismatched types");
4567  if (E->isValueDependent())
4568    return AnalyzeImpConvsInComparison(S, E);
4569
4570  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
4571  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
4572
4573  bool IsComparisonConstant = false;
4574
4575  // Check whether an integer constant comparison results in a value
4576  // of 'true' or 'false'.
4577  if (T->isIntegralType(S.Context)) {
4578    llvm::APSInt RHSValue;
4579    bool IsRHSIntegralLiteral =
4580      RHS->isIntegerConstantExpr(RHSValue, S.Context);
4581    llvm::APSInt LHSValue;
4582    bool IsLHSIntegralLiteral =
4583      LHS->isIntegerConstantExpr(LHSValue, S.Context);
4584    if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
4585        DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
4586    else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
4587      DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
4588    else
4589      IsComparisonConstant =
4590        (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
4591  } else if (!T->hasUnsignedIntegerRepresentation())
4592      IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
4593
4594  // We don't do anything special if this isn't an unsigned integral
4595  // comparison:  we're only interested in integral comparisons, and
4596  // signed comparisons only happen in cases we don't care to warn about.
4597  //
4598  // We also don't care about value-dependent expressions or expressions
4599  // whose result is a constant.
4600  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
4601    return AnalyzeImpConvsInComparison(S, E);
4602
4603  // Check to see if one of the (unmodified) operands is of different
4604  // signedness.
4605  Expr *signedOperand, *unsignedOperand;
4606  if (LHS->getType()->hasSignedIntegerRepresentation()) {
4607    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
4608           "unsigned comparison between two signed integer expressions?");
4609    signedOperand = LHS;
4610    unsignedOperand = RHS;
4611  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
4612    signedOperand = RHS;
4613    unsignedOperand = LHS;
4614  } else {
4615    CheckTrivialUnsignedComparison(S, E);
4616    return AnalyzeImpConvsInComparison(S, E);
4617  }
4618
4619  // Otherwise, calculate the effective range of the signed operand.
4620  IntRange signedRange = GetExprRange(S.Context, signedOperand);
4621
4622  // Go ahead and analyze implicit conversions in the operands.  Note
4623  // that we skip the implicit conversions on both sides.
4624  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
4625  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
4626
4627  // If the signed range is non-negative, -Wsign-compare won't fire,
4628  // but we should still check for comparisons which are always true
4629  // or false.
4630  if (signedRange.NonNegative)
4631    return CheckTrivialUnsignedComparison(S, E);
4632
4633  // For (in)equality comparisons, if the unsigned operand is a
4634  // constant which cannot collide with a overflowed signed operand,
4635  // then reinterpreting the signed operand as unsigned will not
4636  // change the result of the comparison.
4637  if (E->isEqualityOp()) {
4638    unsigned comparisonWidth = S.Context.getIntWidth(T);
4639    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
4640
4641    // We should never be unable to prove that the unsigned operand is
4642    // non-negative.
4643    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
4644
4645    if (unsignedRange.Width < comparisonWidth)
4646      return;
4647  }
4648
4649  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
4650    S.PDiag(diag::warn_mixed_sign_comparison)
4651      << LHS->getType() << RHS->getType()
4652      << LHS->getSourceRange() << RHS->getSourceRange());
4653}
4654
4655/// Analyzes an attempt to assign the given value to a bitfield.
4656///
4657/// Returns true if there was something fishy about the attempt.
4658static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
4659                                      SourceLocation InitLoc) {
4660  assert(Bitfield->isBitField());
4661  if (Bitfield->isInvalidDecl())
4662    return false;
4663
4664  // White-list bool bitfields.
4665  if (Bitfield->getType()->isBooleanType())
4666    return false;
4667
4668  // Ignore value- or type-dependent expressions.
4669  if (Bitfield->getBitWidth()->isValueDependent() ||
4670      Bitfield->getBitWidth()->isTypeDependent() ||
4671      Init->isValueDependent() ||
4672      Init->isTypeDependent())
4673    return false;
4674
4675  Expr *OriginalInit = Init->IgnoreParenImpCasts();
4676
4677  llvm::APSInt Value;
4678  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
4679    return false;
4680
4681  unsigned OriginalWidth = Value.getBitWidth();
4682  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
4683
4684  if (OriginalWidth <= FieldWidth)
4685    return false;
4686
4687  // Compute the value which the bitfield will contain.
4688  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
4689  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
4690
4691  // Check whether the stored value is equal to the original value.
4692  TruncatedValue = TruncatedValue.extend(OriginalWidth);
4693  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
4694    return false;
4695
4696  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4697  // therefore don't strictly fit into a signed bitfield of width 1.
4698  if (FieldWidth == 1 && Value == 1)
4699    return false;
4700
4701  std::string PrettyValue = Value.toString(10);
4702  std::string PrettyTrunc = TruncatedValue.toString(10);
4703
4704  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4705    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4706    << Init->getSourceRange();
4707
4708  return true;
4709}
4710
4711/// Analyze the given simple or compound assignment for warning-worthy
4712/// operations.
4713static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4714  // Just recurse on the LHS.
4715  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4716
4717  // We want to recurse on the RHS as normal unless we're assigning to
4718  // a bitfield.
4719  if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
4720    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4721                                  E->getOperatorLoc())) {
4722      // Recurse, ignoring any implicit conversions on the RHS.
4723      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4724                                        E->getOperatorLoc());
4725    }
4726  }
4727
4728  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4729}
4730
4731/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4732static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4733                            SourceLocation CContext, unsigned diag,
4734                            bool pruneControlFlow = false) {
4735  if (pruneControlFlow) {
4736    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4737                          S.PDiag(diag)
4738                            << SourceType << T << E->getSourceRange()
4739                            << SourceRange(CContext));
4740    return;
4741  }
4742  S.Diag(E->getExprLoc(), diag)
4743    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4744}
4745
4746/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4747static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4748                            SourceLocation CContext, unsigned diag,
4749                            bool pruneControlFlow = false) {
4750  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4751}
4752
4753/// Diagnose an implicit cast from a literal expression. Does not warn when the
4754/// cast wouldn't lose information.
4755void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4756                                    SourceLocation CContext) {
4757  // Try to convert the literal exactly to an integer. If we can, don't warn.
4758  bool isExact = false;
4759  const llvm::APFloat &Value = FL->getValue();
4760  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4761                            T->hasUnsignedIntegerRepresentation());
4762  if (Value.convertToInteger(IntegerValue,
4763                             llvm::APFloat::rmTowardZero, &isExact)
4764      == llvm::APFloat::opOK && isExact)
4765    return;
4766
4767  SmallString<16> PrettySourceValue;
4768  Value.toString(PrettySourceValue);
4769  SmallString<16> PrettyTargetValue;
4770  if (T->isSpecificBuiltinType(BuiltinType::Bool))
4771    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
4772  else
4773    IntegerValue.toString(PrettyTargetValue);
4774
4775  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4776    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
4777    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
4778}
4779
4780std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4781  if (!Range.Width) return "0";
4782
4783  llvm::APSInt ValueInRange = Value;
4784  ValueInRange.setIsSigned(!Range.NonNegative);
4785  ValueInRange = ValueInRange.trunc(Range.Width);
4786  return ValueInRange.toString(10);
4787}
4788
4789static bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
4790  if (!isa<ImplicitCastExpr>(Ex))
4791    return false;
4792
4793  Expr *InnerE = Ex->IgnoreParenImpCasts();
4794  const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
4795  const Type *Source =
4796    S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4797  if (Target->isDependentType())
4798    return false;
4799
4800  const BuiltinType *FloatCandidateBT =
4801    dyn_cast<BuiltinType>(ToBool ? Source : Target);
4802  const Type *BoolCandidateType = ToBool ? Target : Source;
4803
4804  return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
4805          FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
4806}
4807
4808void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
4809                                      SourceLocation CC) {
4810  unsigned NumArgs = TheCall->getNumArgs();
4811  for (unsigned i = 0; i < NumArgs; ++i) {
4812    Expr *CurrA = TheCall->getArg(i);
4813    if (!IsImplicitBoolFloatConversion(S, CurrA, true))
4814      continue;
4815
4816    bool IsSwapped = ((i > 0) &&
4817        IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
4818    IsSwapped |= ((i < (NumArgs - 1)) &&
4819        IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
4820    if (IsSwapped) {
4821      // Warn on this floating-point to bool conversion.
4822      DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
4823                      CurrA->getType(), CC,
4824                      diag::warn_impcast_floating_point_to_bool);
4825    }
4826  }
4827}
4828
4829void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4830                             SourceLocation CC, bool *ICContext = 0) {
4831  if (E->isTypeDependent() || E->isValueDependent()) return;
4832
4833  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4834  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4835  if (Source == Target) return;
4836  if (Target->isDependentType()) return;
4837
4838  // If the conversion context location is invalid don't complain. We also
4839  // don't want to emit a warning if the issue occurs from the expansion of
4840  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4841  // delay this check as long as possible. Once we detect we are in that
4842  // scenario, we just return.
4843  if (CC.isInvalid())
4844    return;
4845
4846  // Diagnose implicit casts to bool.
4847  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4848    if (isa<StringLiteral>(E))
4849      // Warn on string literal to bool.  Checks for string literals in logical
4850      // expressions, for instances, assert(0 && "error here"), is prevented
4851      // by a check in AnalyzeImplicitConversions().
4852      return DiagnoseImpCast(S, E, T, CC,
4853                             diag::warn_impcast_string_literal_to_bool);
4854    if (Source->isFunctionType()) {
4855      // Warn on function to bool. Checks free functions and static member
4856      // functions. Weakly imported functions are excluded from the check,
4857      // since it's common to test their value to check whether the linker
4858      // found a definition for them.
4859      ValueDecl *D = 0;
4860      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4861        D = R->getDecl();
4862      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4863        D = M->getMemberDecl();
4864      }
4865
4866      if (D && !D->isWeak()) {
4867        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4868          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4869            << F << E->getSourceRange() << SourceRange(CC);
4870          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4871            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4872          QualType ReturnType;
4873          UnresolvedSet<4> NonTemplateOverloads;
4874          S.tryExprAsCall(*E, ReturnType, NonTemplateOverloads);
4875          if (!ReturnType.isNull()
4876              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4877            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4878              << FixItHint::CreateInsertion(
4879                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4880          return;
4881        }
4882      }
4883    }
4884  }
4885
4886  // Strip vector types.
4887  if (isa<VectorType>(Source)) {
4888    if (!isa<VectorType>(Target)) {
4889      if (S.SourceMgr.isInSystemMacro(CC))
4890        return;
4891      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4892    }
4893
4894    // If the vector cast is cast between two vectors of the same size, it is
4895    // a bitcast, not a conversion.
4896    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4897      return;
4898
4899    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4900    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4901  }
4902
4903  // Strip complex types.
4904  if (isa<ComplexType>(Source)) {
4905    if (!isa<ComplexType>(Target)) {
4906      if (S.SourceMgr.isInSystemMacro(CC))
4907        return;
4908
4909      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4910    }
4911
4912    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4913    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4914  }
4915
4916  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4917  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4918
4919  // If the source is floating point...
4920  if (SourceBT && SourceBT->isFloatingPoint()) {
4921    // ...and the target is floating point...
4922    if (TargetBT && TargetBT->isFloatingPoint()) {
4923      // ...then warn if we're dropping FP rank.
4924
4925      // Builtin FP kinds are ordered by increasing FP rank.
4926      if (SourceBT->getKind() > TargetBT->getKind()) {
4927        // Don't warn about float constants that are precisely
4928        // representable in the target type.
4929        Expr::EvalResult result;
4930        if (E->EvaluateAsRValue(result, S.Context)) {
4931          // Value might be a float, a float vector, or a float complex.
4932          if (IsSameFloatAfterCast(result.Val,
4933                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4934                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4935            return;
4936        }
4937
4938        if (S.SourceMgr.isInSystemMacro(CC))
4939          return;
4940
4941        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4942      }
4943      return;
4944    }
4945
4946    // If the target is integral, always warn.
4947    if (TargetBT && TargetBT->isInteger()) {
4948      if (S.SourceMgr.isInSystemMacro(CC))
4949        return;
4950
4951      Expr *InnerE = E->IgnoreParenImpCasts();
4952      // We also want to warn on, e.g., "int i = -1.234"
4953      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4954        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4955          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4956
4957      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4958        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4959      } else {
4960        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4961      }
4962    }
4963
4964    // If the target is bool, warn if expr is a function or method call.
4965    if (Target->isSpecificBuiltinType(BuiltinType::Bool) &&
4966        isa<CallExpr>(E)) {
4967      // Check last argument of function call to see if it is an
4968      // implicit cast from a type matching the type the result
4969      // is being cast to.
4970      CallExpr *CEx = cast<CallExpr>(E);
4971      unsigned NumArgs = CEx->getNumArgs();
4972      if (NumArgs > 0) {
4973        Expr *LastA = CEx->getArg(NumArgs - 1);
4974        Expr *InnerE = LastA->IgnoreParenImpCasts();
4975        const Type *InnerType =
4976          S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4977        if (isa<ImplicitCastExpr>(LastA) && (InnerType == Target)) {
4978          // Warn on this floating-point to bool conversion
4979          DiagnoseImpCast(S, E, T, CC,
4980                          diag::warn_impcast_floating_point_to_bool);
4981        }
4982      }
4983    }
4984    return;
4985  }
4986
4987  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4988           == Expr::NPCK_GNUNull) && !Target->isAnyPointerType()
4989      && !Target->isBlockPointerType() && !Target->isMemberPointerType()
4990      && Target->isScalarType() && !Target->isNullPtrType()) {
4991    SourceLocation Loc = E->getSourceRange().getBegin();
4992    if (Loc.isMacroID())
4993      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4994    if (!Loc.isMacroID() || CC.isMacroID())
4995      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4996          << T << clang::SourceRange(CC)
4997          << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
4998  }
4999
5000  if (!Source->isIntegerType() || !Target->isIntegerType())
5001    return;
5002
5003  // TODO: remove this early return once the false positives for constant->bool
5004  // in templates, macros, etc, are reduced or removed.
5005  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
5006    return;
5007
5008  IntRange SourceRange = GetExprRange(S.Context, E);
5009  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
5010
5011  if (SourceRange.Width > TargetRange.Width) {
5012    // If the source is a constant, use a default-on diagnostic.
5013    // TODO: this should happen for bitfield stores, too.
5014    llvm::APSInt Value(32);
5015    if (E->isIntegerConstantExpr(Value, S.Context)) {
5016      if (S.SourceMgr.isInSystemMacro(CC))
5017        return;
5018
5019      std::string PrettySourceValue = Value.toString(10);
5020      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
5021
5022      S.DiagRuntimeBehavior(E->getExprLoc(), E,
5023        S.PDiag(diag::warn_impcast_integer_precision_constant)
5024            << PrettySourceValue << PrettyTargetValue
5025            << E->getType() << T << E->getSourceRange()
5026            << clang::SourceRange(CC));
5027      return;
5028    }
5029
5030    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
5031    if (S.SourceMgr.isInSystemMacro(CC))
5032      return;
5033
5034    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
5035      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
5036                             /* pruneControlFlow */ true);
5037    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
5038  }
5039
5040  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
5041      (!TargetRange.NonNegative && SourceRange.NonNegative &&
5042       SourceRange.Width == TargetRange.Width)) {
5043
5044    if (S.SourceMgr.isInSystemMacro(CC))
5045      return;
5046
5047    unsigned DiagID = diag::warn_impcast_integer_sign;
5048
5049    // Traditionally, gcc has warned about this under -Wsign-compare.
5050    // We also want to warn about it in -Wconversion.
5051    // So if -Wconversion is off, use a completely identical diagnostic
5052    // in the sign-compare group.
5053    // The conditional-checking code will
5054    if (ICContext) {
5055      DiagID = diag::warn_impcast_integer_sign_conditional;
5056      *ICContext = true;
5057    }
5058
5059    return DiagnoseImpCast(S, E, T, CC, DiagID);
5060  }
5061
5062  // Diagnose conversions between different enumeration types.
5063  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
5064  // type, to give us better diagnostics.
5065  QualType SourceType = E->getType();
5066  if (!S.getLangOpts().CPlusPlus) {
5067    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5068      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
5069        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
5070        SourceType = S.Context.getTypeDeclType(Enum);
5071        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
5072      }
5073  }
5074
5075  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
5076    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
5077      if (SourceEnum->getDecl()->hasNameForLinkage() &&
5078          TargetEnum->getDecl()->hasNameForLinkage() &&
5079          SourceEnum != TargetEnum) {
5080        if (S.SourceMgr.isInSystemMacro(CC))
5081          return;
5082
5083        return DiagnoseImpCast(S, E, SourceType, T, CC,
5084                               diag::warn_impcast_different_enum_types);
5085      }
5086
5087  return;
5088}
5089
5090void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5091                              SourceLocation CC, QualType T);
5092
5093void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
5094                             SourceLocation CC, bool &ICContext) {
5095  E = E->IgnoreParenImpCasts();
5096
5097  if (isa<ConditionalOperator>(E))
5098    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
5099
5100  AnalyzeImplicitConversions(S, E, CC);
5101  if (E->getType() != T)
5102    return CheckImplicitConversion(S, E, T, CC, &ICContext);
5103  return;
5104}
5105
5106void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5107                              SourceLocation CC, QualType T) {
5108  AnalyzeImplicitConversions(S, E->getCond(), CC);
5109
5110  bool Suspicious = false;
5111  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
5112  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
5113
5114  // If -Wconversion would have warned about either of the candidates
5115  // for a signedness conversion to the context type...
5116  if (!Suspicious) return;
5117
5118  // ...but it's currently ignored...
5119  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
5120                                 CC))
5121    return;
5122
5123  // ...then check whether it would have warned about either of the
5124  // candidates for a signedness conversion to the condition type.
5125  if (E->getType() == T) return;
5126
5127  Suspicious = false;
5128  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
5129                          E->getType(), CC, &Suspicious);
5130  if (!Suspicious)
5131    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
5132                            E->getType(), CC, &Suspicious);
5133}
5134
5135/// AnalyzeImplicitConversions - Find and report any interesting
5136/// implicit conversions in the given expression.  There are a couple
5137/// of competing diagnostics here, -Wconversion and -Wsign-compare.
5138void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
5139  QualType T = OrigE->getType();
5140  Expr *E = OrigE->IgnoreParenImpCasts();
5141
5142  if (E->isTypeDependent() || E->isValueDependent())
5143    return;
5144
5145  // For conditional operators, we analyze the arguments as if they
5146  // were being fed directly into the output.
5147  if (isa<ConditionalOperator>(E)) {
5148    ConditionalOperator *CO = cast<ConditionalOperator>(E);
5149    CheckConditionalOperator(S, CO, CC, T);
5150    return;
5151  }
5152
5153  // Check implicit argument conversions for function calls.
5154  if (CallExpr *Call = dyn_cast<CallExpr>(E))
5155    CheckImplicitArgumentConversions(S, Call, CC);
5156
5157  // Go ahead and check any implicit conversions we might have skipped.
5158  // The non-canonical typecheck is just an optimization;
5159  // CheckImplicitConversion will filter out dead implicit conversions.
5160  if (E->getType() != T)
5161    CheckImplicitConversion(S, E, T, CC);
5162
5163  // Now continue drilling into this expression.
5164
5165  if (PseudoObjectExpr * POE = dyn_cast<PseudoObjectExpr>(E)) {
5166    if (POE->getResultExpr())
5167      E = POE->getResultExpr();
5168  }
5169
5170  if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E))
5171    return AnalyzeImplicitConversions(S, OVE->getSourceExpr(), CC);
5172
5173  // Skip past explicit casts.
5174  if (isa<ExplicitCastExpr>(E)) {
5175    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
5176    return AnalyzeImplicitConversions(S, E, CC);
5177  }
5178
5179  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5180    // Do a somewhat different check with comparison operators.
5181    if (BO->isComparisonOp())
5182      return AnalyzeComparison(S, BO);
5183
5184    // And with simple assignments.
5185    if (BO->getOpcode() == BO_Assign)
5186      return AnalyzeAssignment(S, BO);
5187  }
5188
5189  // These break the otherwise-useful invariant below.  Fortunately,
5190  // we don't really need to recurse into them, because any internal
5191  // expressions should have been analyzed already when they were
5192  // built into statements.
5193  if (isa<StmtExpr>(E)) return;
5194
5195  // Don't descend into unevaluated contexts.
5196  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
5197
5198  // Now just recurse over the expression's children.
5199  CC = E->getExprLoc();
5200  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
5201  bool IsLogicalOperator = BO && BO->isLogicalOp();
5202  for (Stmt::child_range I = E->children(); I; ++I) {
5203    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
5204    if (!ChildExpr)
5205      continue;
5206
5207    if (IsLogicalOperator &&
5208        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
5209      // Ignore checking string literals that are in logical operators.
5210      continue;
5211    AnalyzeImplicitConversions(S, ChildExpr, CC);
5212  }
5213}
5214
5215} // end anonymous namespace
5216
5217/// Diagnoses "dangerous" implicit conversions within the given
5218/// expression (which is a full expression).  Implements -Wconversion
5219/// and -Wsign-compare.
5220///
5221/// \param CC the "context" location of the implicit conversion, i.e.
5222///   the most location of the syntactic entity requiring the implicit
5223///   conversion
5224void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
5225  // Don't diagnose in unevaluated contexts.
5226  if (isUnevaluatedContext())
5227    return;
5228
5229  // Don't diagnose for value- or type-dependent expressions.
5230  if (E->isTypeDependent() || E->isValueDependent())
5231    return;
5232
5233  // Check for array bounds violations in cases where the check isn't triggered
5234  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
5235  // ArraySubscriptExpr is on the RHS of a variable initialization.
5236  CheckArrayAccess(E);
5237
5238  // This is not the right CC for (e.g.) a variable initialization.
5239  AnalyzeImplicitConversions(*this, E, CC);
5240}
5241
5242/// Diagnose when expression is an integer constant expression and its evaluation
5243/// results in integer overflow
5244void Sema::CheckForIntOverflow (Expr *E) {
5245  if (isa<BinaryOperator>(E->IgnoreParens())) {
5246    llvm::SmallVector<PartialDiagnosticAt, 4> Diags;
5247    E->EvaluateForOverflow(Context, &Diags);
5248  }
5249}
5250
5251namespace {
5252/// \brief Visitor for expressions which looks for unsequenced operations on the
5253/// same object.
5254class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
5255  /// \brief A tree of sequenced regions within an expression. Two regions are
5256  /// unsequenced if one is an ancestor or a descendent of the other. When we
5257  /// finish processing an expression with sequencing, such as a comma
5258  /// expression, we fold its tree nodes into its parent, since they are
5259  /// unsequenced with respect to nodes we will visit later.
5260  class SequenceTree {
5261    struct Value {
5262      explicit Value(unsigned Parent) : Parent(Parent), Merged(false) {}
5263      unsigned Parent : 31;
5264      bool Merged : 1;
5265    };
5266    llvm::SmallVector<Value, 8> Values;
5267
5268  public:
5269    /// \brief A region within an expression which may be sequenced with respect
5270    /// to some other region.
5271    class Seq {
5272      explicit Seq(unsigned N) : Index(N) {}
5273      unsigned Index;
5274      friend class SequenceTree;
5275    public:
5276      Seq() : Index(0) {}
5277    };
5278
5279    SequenceTree() { Values.push_back(Value(0)); }
5280    Seq root() const { return Seq(0); }
5281
5282    /// \brief Create a new sequence of operations, which is an unsequenced
5283    /// subset of \p Parent. This sequence of operations is sequenced with
5284    /// respect to other children of \p Parent.
5285    Seq allocate(Seq Parent) {
5286      Values.push_back(Value(Parent.Index));
5287      return Seq(Values.size() - 1);
5288    }
5289
5290    /// \brief Merge a sequence of operations into its parent.
5291    void merge(Seq S) {
5292      Values[S.Index].Merged = true;
5293    }
5294
5295    /// \brief Determine whether two operations are unsequenced. This operation
5296    /// is asymmetric: \p Cur should be the more recent sequence, and \p Old
5297    /// should have been merged into its parent as appropriate.
5298    bool isUnsequenced(Seq Cur, Seq Old) {
5299      unsigned C = representative(Cur.Index);
5300      unsigned Target = representative(Old.Index);
5301      while (C >= Target) {
5302        if (C == Target)
5303          return true;
5304        C = Values[C].Parent;
5305      }
5306      return false;
5307    }
5308
5309  private:
5310    /// \brief Pick a representative for a sequence.
5311    unsigned representative(unsigned K) {
5312      if (Values[K].Merged)
5313        // Perform path compression as we go.
5314        return Values[K].Parent = representative(Values[K].Parent);
5315      return K;
5316    }
5317  };
5318
5319  /// An object for which we can track unsequenced uses.
5320  typedef NamedDecl *Object;
5321
5322  /// Different flavors of object usage which we track. We only track the
5323  /// least-sequenced usage of each kind.
5324  enum UsageKind {
5325    /// A read of an object. Multiple unsequenced reads are OK.
5326    UK_Use,
5327    /// A modification of an object which is sequenced before the value
5328    /// computation of the expression, such as ++n.
5329    UK_ModAsValue,
5330    /// A modification of an object which is not sequenced before the value
5331    /// computation of the expression, such as n++.
5332    UK_ModAsSideEffect,
5333
5334    UK_Count = UK_ModAsSideEffect + 1
5335  };
5336
5337  struct Usage {
5338    Usage() : Use(0), Seq() {}
5339    Expr *Use;
5340    SequenceTree::Seq Seq;
5341  };
5342
5343  struct UsageInfo {
5344    UsageInfo() : Diagnosed(false) {}
5345    Usage Uses[UK_Count];
5346    /// Have we issued a diagnostic for this variable already?
5347    bool Diagnosed;
5348  };
5349  typedef llvm::SmallDenseMap<Object, UsageInfo, 16> UsageInfoMap;
5350
5351  Sema &SemaRef;
5352  /// Sequenced regions within the expression.
5353  SequenceTree Tree;
5354  /// Declaration modifications and references which we have seen.
5355  UsageInfoMap UsageMap;
5356  /// The region we are currently within.
5357  SequenceTree::Seq Region;
5358  /// Filled in with declarations which were modified as a side-effect
5359  /// (that is, post-increment operations).
5360  llvm::SmallVectorImpl<std::pair<Object, Usage> > *ModAsSideEffect;
5361  /// Expressions to check later. We defer checking these to reduce
5362  /// stack usage.
5363  llvm::SmallVectorImpl<Expr*> &WorkList;
5364
5365  /// RAII object wrapping the visitation of a sequenced subexpression of an
5366  /// expression. At the end of this process, the side-effects of the evaluation
5367  /// become sequenced with respect to the value computation of the result, so
5368  /// we downgrade any UK_ModAsSideEffect within the evaluation to
5369  /// UK_ModAsValue.
5370  struct SequencedSubexpression {
5371    SequencedSubexpression(SequenceChecker &Self)
5372      : Self(Self), OldModAsSideEffect(Self.ModAsSideEffect) {
5373      Self.ModAsSideEffect = &ModAsSideEffect;
5374    }
5375    ~SequencedSubexpression() {
5376      for (unsigned I = 0, E = ModAsSideEffect.size(); I != E; ++I) {
5377        UsageInfo &U = Self.UsageMap[ModAsSideEffect[I].first];
5378        U.Uses[UK_ModAsSideEffect] = ModAsSideEffect[I].second;
5379        Self.addUsage(U, ModAsSideEffect[I].first,
5380                      ModAsSideEffect[I].second.Use, UK_ModAsValue);
5381      }
5382      Self.ModAsSideEffect = OldModAsSideEffect;
5383    }
5384
5385    SequenceChecker &Self;
5386    llvm::SmallVector<std::pair<Object, Usage>, 4> ModAsSideEffect;
5387    llvm::SmallVectorImpl<std::pair<Object, Usage> > *OldModAsSideEffect;
5388  };
5389
5390  /// RAII object wrapping the visitation of a subexpression which we might
5391  /// choose to evaluate as a constant. If any subexpression is evaluated and
5392  /// found to be non-constant, this allows us to suppress the evaluation of
5393  /// the outer expression.
5394  class EvaluationTracker {
5395  public:
5396    EvaluationTracker(SequenceChecker &Self)
5397        : Self(Self), Prev(Self.EvalTracker), EvalOK(true) {
5398      Self.EvalTracker = this;
5399    }
5400    ~EvaluationTracker() {
5401      Self.EvalTracker = Prev;
5402      if (Prev)
5403        Prev->EvalOK &= EvalOK;
5404    }
5405
5406    bool evaluate(const Expr *E, bool &Result) {
5407      if (!EvalOK || E->isValueDependent())
5408        return false;
5409      EvalOK = E->EvaluateAsBooleanCondition(Result, Self.SemaRef.Context);
5410      return EvalOK;
5411    }
5412
5413  private:
5414    SequenceChecker &Self;
5415    EvaluationTracker *Prev;
5416    bool EvalOK;
5417  } *EvalTracker;
5418
5419  /// \brief Find the object which is produced by the specified expression,
5420  /// if any.
5421  Object getObject(Expr *E, bool Mod) const {
5422    E = E->IgnoreParenCasts();
5423    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
5424      if (Mod && (UO->getOpcode() == UO_PreInc || UO->getOpcode() == UO_PreDec))
5425        return getObject(UO->getSubExpr(), Mod);
5426    } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5427      if (BO->getOpcode() == BO_Comma)
5428        return getObject(BO->getRHS(), Mod);
5429      if (Mod && BO->isAssignmentOp())
5430        return getObject(BO->getLHS(), Mod);
5431    } else if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
5432      // FIXME: Check for more interesting cases, like "x.n = ++x.n".
5433      if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenCasts()))
5434        return ME->getMemberDecl();
5435    } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5436      // FIXME: If this is a reference, map through to its value.
5437      return DRE->getDecl();
5438    return 0;
5439  }
5440
5441  /// \brief Note that an object was modified or used by an expression.
5442  void addUsage(UsageInfo &UI, Object O, Expr *Ref, UsageKind UK) {
5443    Usage &U = UI.Uses[UK];
5444    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq)) {
5445      if (UK == UK_ModAsSideEffect && ModAsSideEffect)
5446        ModAsSideEffect->push_back(std::make_pair(O, U));
5447      U.Use = Ref;
5448      U.Seq = Region;
5449    }
5450  }
5451  /// \brief Check whether a modification or use conflicts with a prior usage.
5452  void checkUsage(Object O, UsageInfo &UI, Expr *Ref, UsageKind OtherKind,
5453                  bool IsModMod) {
5454    if (UI.Diagnosed)
5455      return;
5456
5457    const Usage &U = UI.Uses[OtherKind];
5458    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq))
5459      return;
5460
5461    Expr *Mod = U.Use;
5462    Expr *ModOrUse = Ref;
5463    if (OtherKind == UK_Use)
5464      std::swap(Mod, ModOrUse);
5465
5466    SemaRef.Diag(Mod->getExprLoc(),
5467                 IsModMod ? diag::warn_unsequenced_mod_mod
5468                          : diag::warn_unsequenced_mod_use)
5469      << O << SourceRange(ModOrUse->getExprLoc());
5470    UI.Diagnosed = true;
5471  }
5472
5473  void notePreUse(Object O, Expr *Use) {
5474    UsageInfo &U = UsageMap[O];
5475    // Uses conflict with other modifications.
5476    checkUsage(O, U, Use, UK_ModAsValue, false);
5477  }
5478  void notePostUse(Object O, Expr *Use) {
5479    UsageInfo &U = UsageMap[O];
5480    checkUsage(O, U, Use, UK_ModAsSideEffect, false);
5481    addUsage(U, O, Use, UK_Use);
5482  }
5483
5484  void notePreMod(Object O, Expr *Mod) {
5485    UsageInfo &U = UsageMap[O];
5486    // Modifications conflict with other modifications and with uses.
5487    checkUsage(O, U, Mod, UK_ModAsValue, true);
5488    checkUsage(O, U, Mod, UK_Use, false);
5489  }
5490  void notePostMod(Object O, Expr *Use, UsageKind UK) {
5491    UsageInfo &U = UsageMap[O];
5492    checkUsage(O, U, Use, UK_ModAsSideEffect, true);
5493    addUsage(U, O, Use, UK);
5494  }
5495
5496public:
5497  SequenceChecker(Sema &S, Expr *E,
5498                  llvm::SmallVectorImpl<Expr*> &WorkList)
5499    : EvaluatedExprVisitor<SequenceChecker>(S.Context), SemaRef(S),
5500      Region(Tree.root()), ModAsSideEffect(0), WorkList(WorkList),
5501      EvalTracker(0) {
5502    Visit(E);
5503  }
5504
5505  void VisitStmt(Stmt *S) {
5506    // Skip all statements which aren't expressions for now.
5507  }
5508
5509  void VisitExpr(Expr *E) {
5510    // By default, just recurse to evaluated subexpressions.
5511    EvaluatedExprVisitor<SequenceChecker>::VisitStmt(E);
5512  }
5513
5514  void VisitCastExpr(CastExpr *E) {
5515    Object O = Object();
5516    if (E->getCastKind() == CK_LValueToRValue)
5517      O = getObject(E->getSubExpr(), false);
5518
5519    if (O)
5520      notePreUse(O, E);
5521    VisitExpr(E);
5522    if (O)
5523      notePostUse(O, E);
5524  }
5525
5526  void VisitBinComma(BinaryOperator *BO) {
5527    // C++11 [expr.comma]p1:
5528    //   Every value computation and side effect associated with the left
5529    //   expression is sequenced before every value computation and side
5530    //   effect associated with the right expression.
5531    SequenceTree::Seq LHS = Tree.allocate(Region);
5532    SequenceTree::Seq RHS = Tree.allocate(Region);
5533    SequenceTree::Seq OldRegion = Region;
5534
5535    {
5536      SequencedSubexpression SeqLHS(*this);
5537      Region = LHS;
5538      Visit(BO->getLHS());
5539    }
5540
5541    Region = RHS;
5542    Visit(BO->getRHS());
5543
5544    Region = OldRegion;
5545
5546    // Forget that LHS and RHS are sequenced. They are both unsequenced
5547    // with respect to other stuff.
5548    Tree.merge(LHS);
5549    Tree.merge(RHS);
5550  }
5551
5552  void VisitBinAssign(BinaryOperator *BO) {
5553    // The modification is sequenced after the value computation of the LHS
5554    // and RHS, so check it before inspecting the operands and update the
5555    // map afterwards.
5556    Object O = getObject(BO->getLHS(), true);
5557    if (!O)
5558      return VisitExpr(BO);
5559
5560    notePreMod(O, BO);
5561
5562    // C++11 [expr.ass]p7:
5563    //   E1 op= E2 is equivalent to E1 = E1 op E2, except that E1 is evaluated
5564    //   only once.
5565    //
5566    // Therefore, for a compound assignment operator, O is considered used
5567    // everywhere except within the evaluation of E1 itself.
5568    if (isa<CompoundAssignOperator>(BO))
5569      notePreUse(O, BO);
5570
5571    Visit(BO->getLHS());
5572
5573    if (isa<CompoundAssignOperator>(BO))
5574      notePostUse(O, BO);
5575
5576    Visit(BO->getRHS());
5577
5578    notePostMod(O, BO, UK_ModAsValue);
5579  }
5580  void VisitCompoundAssignOperator(CompoundAssignOperator *CAO) {
5581    VisitBinAssign(CAO);
5582  }
5583
5584  void VisitUnaryPreInc(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5585  void VisitUnaryPreDec(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5586  void VisitUnaryPreIncDec(UnaryOperator *UO) {
5587    Object O = getObject(UO->getSubExpr(), true);
5588    if (!O)
5589      return VisitExpr(UO);
5590
5591    notePreMod(O, UO);
5592    Visit(UO->getSubExpr());
5593    notePostMod(O, UO, UK_ModAsValue);
5594  }
5595
5596  void VisitUnaryPostInc(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5597  void VisitUnaryPostDec(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5598  void VisitUnaryPostIncDec(UnaryOperator *UO) {
5599    Object O = getObject(UO->getSubExpr(), true);
5600    if (!O)
5601      return VisitExpr(UO);
5602
5603    notePreMod(O, UO);
5604    Visit(UO->getSubExpr());
5605    notePostMod(O, UO, UK_ModAsSideEffect);
5606  }
5607
5608  /// Don't visit the RHS of '&&' or '||' if it might not be evaluated.
5609  void VisitBinLOr(BinaryOperator *BO) {
5610    // The side-effects of the LHS of an '&&' are sequenced before the
5611    // value computation of the RHS, and hence before the value computation
5612    // of the '&&' itself, unless the LHS evaluates to zero. We treat them
5613    // as if they were unconditionally sequenced.
5614    EvaluationTracker Eval(*this);
5615    {
5616      SequencedSubexpression Sequenced(*this);
5617      Visit(BO->getLHS());
5618    }
5619
5620    bool Result;
5621    if (Eval.evaluate(BO->getLHS(), Result)) {
5622      if (!Result)
5623        Visit(BO->getRHS());
5624    } else {
5625      // Check for unsequenced operations in the RHS, treating it as an
5626      // entirely separate evaluation.
5627      //
5628      // FIXME: If there are operations in the RHS which are unsequenced
5629      // with respect to operations outside the RHS, and those operations
5630      // are unconditionally evaluated, diagnose them.
5631      WorkList.push_back(BO->getRHS());
5632    }
5633  }
5634  void VisitBinLAnd(BinaryOperator *BO) {
5635    EvaluationTracker Eval(*this);
5636    {
5637      SequencedSubexpression Sequenced(*this);
5638      Visit(BO->getLHS());
5639    }
5640
5641    bool Result;
5642    if (Eval.evaluate(BO->getLHS(), Result)) {
5643      if (Result)
5644        Visit(BO->getRHS());
5645    } else {
5646      WorkList.push_back(BO->getRHS());
5647    }
5648  }
5649
5650  // Only visit the condition, unless we can be sure which subexpression will
5651  // be chosen.
5652  void VisitAbstractConditionalOperator(AbstractConditionalOperator *CO) {
5653    EvaluationTracker Eval(*this);
5654    SequencedSubexpression Sequenced(*this);
5655    Visit(CO->getCond());
5656
5657    bool Result;
5658    if (Eval.evaluate(CO->getCond(), Result))
5659      Visit(Result ? CO->getTrueExpr() : CO->getFalseExpr());
5660    else {
5661      WorkList.push_back(CO->getTrueExpr());
5662      WorkList.push_back(CO->getFalseExpr());
5663    }
5664  }
5665
5666  void VisitCXXConstructExpr(CXXConstructExpr *CCE) {
5667    if (!CCE->isListInitialization())
5668      return VisitExpr(CCE);
5669
5670    // In C++11, list initializations are sequenced.
5671    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5672    SequenceTree::Seq Parent = Region;
5673    for (CXXConstructExpr::arg_iterator I = CCE->arg_begin(),
5674                                        E = CCE->arg_end();
5675         I != E; ++I) {
5676      Region = Tree.allocate(Parent);
5677      Elts.push_back(Region);
5678      Visit(*I);
5679    }
5680
5681    // Forget that the initializers are sequenced.
5682    Region = Parent;
5683    for (unsigned I = 0; I < Elts.size(); ++I)
5684      Tree.merge(Elts[I]);
5685  }
5686
5687  void VisitInitListExpr(InitListExpr *ILE) {
5688    if (!SemaRef.getLangOpts().CPlusPlus11)
5689      return VisitExpr(ILE);
5690
5691    // In C++11, list initializations are sequenced.
5692    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5693    SequenceTree::Seq Parent = Region;
5694    for (unsigned I = 0; I < ILE->getNumInits(); ++I) {
5695      Expr *E = ILE->getInit(I);
5696      if (!E) continue;
5697      Region = Tree.allocate(Parent);
5698      Elts.push_back(Region);
5699      Visit(E);
5700    }
5701
5702    // Forget that the initializers are sequenced.
5703    Region = Parent;
5704    for (unsigned I = 0; I < Elts.size(); ++I)
5705      Tree.merge(Elts[I]);
5706  }
5707};
5708}
5709
5710void Sema::CheckUnsequencedOperations(Expr *E) {
5711  llvm::SmallVector<Expr*, 8> WorkList;
5712  WorkList.push_back(E);
5713  while (!WorkList.empty()) {
5714    Expr *Item = WorkList.back();
5715    WorkList.pop_back();
5716    SequenceChecker(*this, Item, WorkList);
5717  }
5718}
5719
5720void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
5721                              bool IsConstexpr) {
5722  CheckImplicitConversions(E, CheckLoc);
5723  CheckUnsequencedOperations(E);
5724  if (!IsConstexpr && !E->isValueDependent())
5725    CheckForIntOverflow(E);
5726}
5727
5728void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
5729                                       FieldDecl *BitField,
5730                                       Expr *Init) {
5731  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
5732}
5733
5734/// CheckParmsForFunctionDef - Check that the parameters of the given
5735/// function are appropriate for the definition of a function. This
5736/// takes care of any checks that cannot be performed on the
5737/// declaration itself, e.g., that the types of each of the function
5738/// parameters are complete.
5739bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
5740                                    bool CheckParameterNames) {
5741  bool HasInvalidParm = false;
5742  for (; P != PEnd; ++P) {
5743    ParmVarDecl *Param = *P;
5744
5745    // C99 6.7.5.3p4: the parameters in a parameter type list in a
5746    // function declarator that is part of a function definition of
5747    // that function shall not have incomplete type.
5748    //
5749    // This is also C++ [dcl.fct]p6.
5750    if (!Param->isInvalidDecl() &&
5751        RequireCompleteType(Param->getLocation(), Param->getType(),
5752                            diag::err_typecheck_decl_incomplete_type)) {
5753      Param->setInvalidDecl();
5754      HasInvalidParm = true;
5755    }
5756
5757    // C99 6.9.1p5: If the declarator includes a parameter type list, the
5758    // declaration of each parameter shall include an identifier.
5759    if (CheckParameterNames &&
5760        Param->getIdentifier() == 0 &&
5761        !Param->isImplicit() &&
5762        !getLangOpts().CPlusPlus)
5763      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
5764
5765    // C99 6.7.5.3p12:
5766    //   If the function declarator is not part of a definition of that
5767    //   function, parameters may have incomplete type and may use the [*]
5768    //   notation in their sequences of declarator specifiers to specify
5769    //   variable length array types.
5770    QualType PType = Param->getOriginalType();
5771    while (const ArrayType *AT = Context.getAsArrayType(PType)) {
5772      if (AT->getSizeModifier() == ArrayType::Star) {
5773        // FIXME: This diagnostic should point the '[*]' if source-location
5774        // information is added for it.
5775        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
5776        break;
5777      }
5778      PType= AT->getElementType();
5779    }
5780
5781    // MSVC destroys objects passed by value in the callee.  Therefore a
5782    // function definition which takes such a parameter must be able to call the
5783    // object's destructor.
5784    if (getLangOpts().CPlusPlus &&
5785        Context.getTargetInfo().getCXXABI().isArgumentDestroyedByCallee()) {
5786      if (const RecordType *RT = Param->getType()->getAs<RecordType>())
5787        FinalizeVarWithDestructor(Param, RT);
5788    }
5789  }
5790
5791  return HasInvalidParm;
5792}
5793
5794/// CheckCastAlign - Implements -Wcast-align, which warns when a
5795/// pointer cast increases the alignment requirements.
5796void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
5797  // This is actually a lot of work to potentially be doing on every
5798  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
5799  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
5800                                          TRange.getBegin())
5801        == DiagnosticsEngine::Ignored)
5802    return;
5803
5804  // Ignore dependent types.
5805  if (T->isDependentType() || Op->getType()->isDependentType())
5806    return;
5807
5808  // Require that the destination be a pointer type.
5809  const PointerType *DestPtr = T->getAs<PointerType>();
5810  if (!DestPtr) return;
5811
5812  // If the destination has alignment 1, we're done.
5813  QualType DestPointee = DestPtr->getPointeeType();
5814  if (DestPointee->isIncompleteType()) return;
5815  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
5816  if (DestAlign.isOne()) return;
5817
5818  // Require that the source be a pointer type.
5819  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
5820  if (!SrcPtr) return;
5821  QualType SrcPointee = SrcPtr->getPointeeType();
5822
5823  // Whitelist casts from cv void*.  We already implicitly
5824  // whitelisted casts to cv void*, since they have alignment 1.
5825  // Also whitelist casts involving incomplete types, which implicitly
5826  // includes 'void'.
5827  if (SrcPointee->isIncompleteType()) return;
5828
5829  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
5830  if (SrcAlign >= DestAlign) return;
5831
5832  Diag(TRange.getBegin(), diag::warn_cast_align)
5833    << Op->getType() << T
5834    << static_cast<unsigned>(SrcAlign.getQuantity())
5835    << static_cast<unsigned>(DestAlign.getQuantity())
5836    << TRange << Op->getSourceRange();
5837}
5838
5839static const Type* getElementType(const Expr *BaseExpr) {
5840  const Type* EltType = BaseExpr->getType().getTypePtr();
5841  if (EltType->isAnyPointerType())
5842    return EltType->getPointeeType().getTypePtr();
5843  else if (EltType->isArrayType())
5844    return EltType->getBaseElementTypeUnsafe();
5845  return EltType;
5846}
5847
5848/// \brief Check whether this array fits the idiom of a size-one tail padded
5849/// array member of a struct.
5850///
5851/// We avoid emitting out-of-bounds access warnings for such arrays as they are
5852/// commonly used to emulate flexible arrays in C89 code.
5853static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
5854                                    const NamedDecl *ND) {
5855  if (Size != 1 || !ND) return false;
5856
5857  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
5858  if (!FD) return false;
5859
5860  // Don't consider sizes resulting from macro expansions or template argument
5861  // substitution to form C89 tail-padded arrays.
5862
5863  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
5864  while (TInfo) {
5865    TypeLoc TL = TInfo->getTypeLoc();
5866    // Look through typedefs.
5867    if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
5868      const TypedefNameDecl *TDL = TTL.getTypedefNameDecl();
5869      TInfo = TDL->getTypeSourceInfo();
5870      continue;
5871    }
5872    if (ConstantArrayTypeLoc CTL = TL.getAs<ConstantArrayTypeLoc>()) {
5873      const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
5874      if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
5875        return false;
5876    }
5877    break;
5878  }
5879
5880  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
5881  if (!RD) return false;
5882  if (RD->isUnion()) return false;
5883  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
5884    if (!CRD->isStandardLayout()) return false;
5885  }
5886
5887  // See if this is the last field decl in the record.
5888  const Decl *D = FD;
5889  while ((D = D->getNextDeclInContext()))
5890    if (isa<FieldDecl>(D))
5891      return false;
5892  return true;
5893}
5894
5895void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
5896                            const ArraySubscriptExpr *ASE,
5897                            bool AllowOnePastEnd, bool IndexNegated) {
5898  IndexExpr = IndexExpr->IgnoreParenImpCasts();
5899  if (IndexExpr->isValueDependent())
5900    return;
5901
5902  const Type *EffectiveType = getElementType(BaseExpr);
5903  BaseExpr = BaseExpr->IgnoreParenCasts();
5904  const ConstantArrayType *ArrayTy =
5905    Context.getAsConstantArrayType(BaseExpr->getType());
5906  if (!ArrayTy)
5907    return;
5908
5909  llvm::APSInt index;
5910  if (!IndexExpr->EvaluateAsInt(index, Context))
5911    return;
5912  if (IndexNegated)
5913    index = -index;
5914
5915  const NamedDecl *ND = NULL;
5916  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5917    ND = dyn_cast<NamedDecl>(DRE->getDecl());
5918  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5919    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5920
5921  if (index.isUnsigned() || !index.isNegative()) {
5922    llvm::APInt size = ArrayTy->getSize();
5923    if (!size.isStrictlyPositive())
5924      return;
5925
5926    const Type* BaseType = getElementType(BaseExpr);
5927    if (BaseType != EffectiveType) {
5928      // Make sure we're comparing apples to apples when comparing index to size
5929      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
5930      uint64_t array_typesize = Context.getTypeSize(BaseType);
5931      // Handle ptrarith_typesize being zero, such as when casting to void*
5932      if (!ptrarith_typesize) ptrarith_typesize = 1;
5933      if (ptrarith_typesize != array_typesize) {
5934        // There's a cast to a different size type involved
5935        uint64_t ratio = array_typesize / ptrarith_typesize;
5936        // TODO: Be smarter about handling cases where array_typesize is not a
5937        // multiple of ptrarith_typesize
5938        if (ptrarith_typesize * ratio == array_typesize)
5939          size *= llvm::APInt(size.getBitWidth(), ratio);
5940      }
5941    }
5942
5943    if (size.getBitWidth() > index.getBitWidth())
5944      index = index.zext(size.getBitWidth());
5945    else if (size.getBitWidth() < index.getBitWidth())
5946      size = size.zext(index.getBitWidth());
5947
5948    // For array subscripting the index must be less than size, but for pointer
5949    // arithmetic also allow the index (offset) to be equal to size since
5950    // computing the next address after the end of the array is legal and
5951    // commonly done e.g. in C++ iterators and range-based for loops.
5952    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
5953      return;
5954
5955    // Also don't warn for arrays of size 1 which are members of some
5956    // structure. These are often used to approximate flexible arrays in C89
5957    // code.
5958    if (IsTailPaddedMemberArray(*this, size, ND))
5959      return;
5960
5961    // Suppress the warning if the subscript expression (as identified by the
5962    // ']' location) and the index expression are both from macro expansions
5963    // within a system header.
5964    if (ASE) {
5965      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
5966          ASE->getRBracketLoc());
5967      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
5968        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
5969            IndexExpr->getLocStart());
5970        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
5971          return;
5972      }
5973    }
5974
5975    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
5976    if (ASE)
5977      DiagID = diag::warn_array_index_exceeds_bounds;
5978
5979    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5980                        PDiag(DiagID) << index.toString(10, true)
5981                          << size.toString(10, true)
5982                          << (unsigned)size.getLimitedValue(~0U)
5983                          << IndexExpr->getSourceRange());
5984  } else {
5985    unsigned DiagID = diag::warn_array_index_precedes_bounds;
5986    if (!ASE) {
5987      DiagID = diag::warn_ptr_arith_precedes_bounds;
5988      if (index.isNegative()) index = -index;
5989    }
5990
5991    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5992                        PDiag(DiagID) << index.toString(10, true)
5993                          << IndexExpr->getSourceRange());
5994  }
5995
5996  if (!ND) {
5997    // Try harder to find a NamedDecl to point at in the note.
5998    while (const ArraySubscriptExpr *ASE =
5999           dyn_cast<ArraySubscriptExpr>(BaseExpr))
6000      BaseExpr = ASE->getBase()->IgnoreParenCasts();
6001    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
6002      ND = dyn_cast<NamedDecl>(DRE->getDecl());
6003    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
6004      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
6005  }
6006
6007  if (ND)
6008    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
6009                        PDiag(diag::note_array_index_out_of_bounds)
6010                          << ND->getDeclName());
6011}
6012
6013void Sema::CheckArrayAccess(const Expr *expr) {
6014  int AllowOnePastEnd = 0;
6015  while (expr) {
6016    expr = expr->IgnoreParenImpCasts();
6017    switch (expr->getStmtClass()) {
6018      case Stmt::ArraySubscriptExprClass: {
6019        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
6020        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
6021                         AllowOnePastEnd > 0);
6022        return;
6023      }
6024      case Stmt::UnaryOperatorClass: {
6025        // Only unwrap the * and & unary operators
6026        const UnaryOperator *UO = cast<UnaryOperator>(expr);
6027        expr = UO->getSubExpr();
6028        switch (UO->getOpcode()) {
6029          case UO_AddrOf:
6030            AllowOnePastEnd++;
6031            break;
6032          case UO_Deref:
6033            AllowOnePastEnd--;
6034            break;
6035          default:
6036            return;
6037        }
6038        break;
6039      }
6040      case Stmt::ConditionalOperatorClass: {
6041        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
6042        if (const Expr *lhs = cond->getLHS())
6043          CheckArrayAccess(lhs);
6044        if (const Expr *rhs = cond->getRHS())
6045          CheckArrayAccess(rhs);
6046        return;
6047      }
6048      default:
6049        return;
6050    }
6051  }
6052}
6053
6054//===--- CHECK: Objective-C retain cycles ----------------------------------//
6055
6056namespace {
6057  struct RetainCycleOwner {
6058    RetainCycleOwner() : Variable(0), Indirect(false) {}
6059    VarDecl *Variable;
6060    SourceRange Range;
6061    SourceLocation Loc;
6062    bool Indirect;
6063
6064    void setLocsFrom(Expr *e) {
6065      Loc = e->getExprLoc();
6066      Range = e->getSourceRange();
6067    }
6068  };
6069}
6070
6071/// Consider whether capturing the given variable can possibly lead to
6072/// a retain cycle.
6073static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
6074  // In ARC, it's captured strongly iff the variable has __strong
6075  // lifetime.  In MRR, it's captured strongly if the variable is
6076  // __block and has an appropriate type.
6077  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6078    return false;
6079
6080  owner.Variable = var;
6081  if (ref)
6082    owner.setLocsFrom(ref);
6083  return true;
6084}
6085
6086static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
6087  while (true) {
6088    e = e->IgnoreParens();
6089    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
6090      switch (cast->getCastKind()) {
6091      case CK_BitCast:
6092      case CK_LValueBitCast:
6093      case CK_LValueToRValue:
6094      case CK_ARCReclaimReturnedObject:
6095        e = cast->getSubExpr();
6096        continue;
6097
6098      default:
6099        return false;
6100      }
6101    }
6102
6103    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
6104      ObjCIvarDecl *ivar = ref->getDecl();
6105      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6106        return false;
6107
6108      // Try to find a retain cycle in the base.
6109      if (!findRetainCycleOwner(S, ref->getBase(), owner))
6110        return false;
6111
6112      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
6113      owner.Indirect = true;
6114      return true;
6115    }
6116
6117    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
6118      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
6119      if (!var) return false;
6120      return considerVariable(var, ref, owner);
6121    }
6122
6123    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
6124      if (member->isArrow()) return false;
6125
6126      // Don't count this as an indirect ownership.
6127      e = member->getBase();
6128      continue;
6129    }
6130
6131    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
6132      // Only pay attention to pseudo-objects on property references.
6133      ObjCPropertyRefExpr *pre
6134        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
6135                                              ->IgnoreParens());
6136      if (!pre) return false;
6137      if (pre->isImplicitProperty()) return false;
6138      ObjCPropertyDecl *property = pre->getExplicitProperty();
6139      if (!property->isRetaining() &&
6140          !(property->getPropertyIvarDecl() &&
6141            property->getPropertyIvarDecl()->getType()
6142              .getObjCLifetime() == Qualifiers::OCL_Strong))
6143          return false;
6144
6145      owner.Indirect = true;
6146      if (pre->isSuperReceiver()) {
6147        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
6148        if (!owner.Variable)
6149          return false;
6150        owner.Loc = pre->getLocation();
6151        owner.Range = pre->getSourceRange();
6152        return true;
6153      }
6154      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
6155                              ->getSourceExpr());
6156      continue;
6157    }
6158
6159    // Array ivars?
6160
6161    return false;
6162  }
6163}
6164
6165namespace {
6166  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
6167    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
6168      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
6169        Variable(variable), Capturer(0) {}
6170
6171    VarDecl *Variable;
6172    Expr *Capturer;
6173
6174    void VisitDeclRefExpr(DeclRefExpr *ref) {
6175      if (ref->getDecl() == Variable && !Capturer)
6176        Capturer = ref;
6177    }
6178
6179    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
6180      if (Capturer) return;
6181      Visit(ref->getBase());
6182      if (Capturer && ref->isFreeIvar())
6183        Capturer = ref;
6184    }
6185
6186    void VisitBlockExpr(BlockExpr *block) {
6187      // Look inside nested blocks
6188      if (block->getBlockDecl()->capturesVariable(Variable))
6189        Visit(block->getBlockDecl()->getBody());
6190    }
6191
6192    void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
6193      if (Capturer) return;
6194      if (OVE->getSourceExpr())
6195        Visit(OVE->getSourceExpr());
6196    }
6197  };
6198}
6199
6200/// Check whether the given argument is a block which captures a
6201/// variable.
6202static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
6203  assert(owner.Variable && owner.Loc.isValid());
6204
6205  e = e->IgnoreParenCasts();
6206
6207  // Look through [^{...} copy] and Block_copy(^{...}).
6208  if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
6209    Selector Cmd = ME->getSelector();
6210    if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
6211      e = ME->getInstanceReceiver();
6212      if (!e)
6213        return 0;
6214      e = e->IgnoreParenCasts();
6215    }
6216  } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
6217    if (CE->getNumArgs() == 1) {
6218      FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
6219      if (Fn) {
6220        const IdentifierInfo *FnI = Fn->getIdentifier();
6221        if (FnI && FnI->isStr("_Block_copy")) {
6222          e = CE->getArg(0)->IgnoreParenCasts();
6223        }
6224      }
6225    }
6226  }
6227
6228  BlockExpr *block = dyn_cast<BlockExpr>(e);
6229  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
6230    return 0;
6231
6232  FindCaptureVisitor visitor(S.Context, owner.Variable);
6233  visitor.Visit(block->getBlockDecl()->getBody());
6234  return visitor.Capturer;
6235}
6236
6237static void diagnoseRetainCycle(Sema &S, Expr *capturer,
6238                                RetainCycleOwner &owner) {
6239  assert(capturer);
6240  assert(owner.Variable && owner.Loc.isValid());
6241
6242  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
6243    << owner.Variable << capturer->getSourceRange();
6244  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
6245    << owner.Indirect << owner.Range;
6246}
6247
6248/// Check for a keyword selector that starts with the word 'add' or
6249/// 'set'.
6250static bool isSetterLikeSelector(Selector sel) {
6251  if (sel.isUnarySelector()) return false;
6252
6253  StringRef str = sel.getNameForSlot(0);
6254  while (!str.empty() && str.front() == '_') str = str.substr(1);
6255  if (str.startswith("set"))
6256    str = str.substr(3);
6257  else if (str.startswith("add")) {
6258    // Specially whitelist 'addOperationWithBlock:'.
6259    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
6260      return false;
6261    str = str.substr(3);
6262  }
6263  else
6264    return false;
6265
6266  if (str.empty()) return true;
6267  return !isLowercase(str.front());
6268}
6269
6270/// Check a message send to see if it's likely to cause a retain cycle.
6271void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
6272  // Only check instance methods whose selector looks like a setter.
6273  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
6274    return;
6275
6276  // Try to find a variable that the receiver is strongly owned by.
6277  RetainCycleOwner owner;
6278  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
6279    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
6280      return;
6281  } else {
6282    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
6283    owner.Variable = getCurMethodDecl()->getSelfDecl();
6284    owner.Loc = msg->getSuperLoc();
6285    owner.Range = msg->getSuperLoc();
6286  }
6287
6288  // Check whether the receiver is captured by any of the arguments.
6289  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
6290    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
6291      return diagnoseRetainCycle(*this, capturer, owner);
6292}
6293
6294/// Check a property assign to see if it's likely to cause a retain cycle.
6295void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
6296  RetainCycleOwner owner;
6297  if (!findRetainCycleOwner(*this, receiver, owner))
6298    return;
6299
6300  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
6301    diagnoseRetainCycle(*this, capturer, owner);
6302}
6303
6304void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
6305  RetainCycleOwner Owner;
6306  if (!considerVariable(Var, /*DeclRefExpr=*/0, Owner))
6307    return;
6308
6309  // Because we don't have an expression for the variable, we have to set the
6310  // location explicitly here.
6311  Owner.Loc = Var->getLocation();
6312  Owner.Range = Var->getSourceRange();
6313
6314  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
6315    diagnoseRetainCycle(*this, Capturer, Owner);
6316}
6317
6318static bool checkUnsafeAssignLiteral(Sema &S, SourceLocation Loc,
6319                                     Expr *RHS, bool isProperty) {
6320  // Check if RHS is an Objective-C object literal, which also can get
6321  // immediately zapped in a weak reference.  Note that we explicitly
6322  // allow ObjCStringLiterals, since those are designed to never really die.
6323  RHS = RHS->IgnoreParenImpCasts();
6324
6325  // This enum needs to match with the 'select' in
6326  // warn_objc_arc_literal_assign (off-by-1).
6327  Sema::ObjCLiteralKind Kind = S.CheckLiteralKind(RHS);
6328  if (Kind == Sema::LK_String || Kind == Sema::LK_None)
6329    return false;
6330
6331  S.Diag(Loc, diag::warn_arc_literal_assign)
6332    << (unsigned) Kind
6333    << (isProperty ? 0 : 1)
6334    << RHS->getSourceRange();
6335
6336  return true;
6337}
6338
6339static bool checkUnsafeAssignObject(Sema &S, SourceLocation Loc,
6340                                    Qualifiers::ObjCLifetime LT,
6341                                    Expr *RHS, bool isProperty) {
6342  // Strip off any implicit cast added to get to the one ARC-specific.
6343  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6344    if (cast->getCastKind() == CK_ARCConsumeObject) {
6345      S.Diag(Loc, diag::warn_arc_retained_assign)
6346        << (LT == Qualifiers::OCL_ExplicitNone)
6347        << (isProperty ? 0 : 1)
6348        << RHS->getSourceRange();
6349      return true;
6350    }
6351    RHS = cast->getSubExpr();
6352  }
6353
6354  if (LT == Qualifiers::OCL_Weak &&
6355      checkUnsafeAssignLiteral(S, Loc, RHS, isProperty))
6356    return true;
6357
6358  return false;
6359}
6360
6361bool Sema::checkUnsafeAssigns(SourceLocation Loc,
6362                              QualType LHS, Expr *RHS) {
6363  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
6364
6365  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
6366    return false;
6367
6368  if (checkUnsafeAssignObject(*this, Loc, LT, RHS, false))
6369    return true;
6370
6371  return false;
6372}
6373
6374void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
6375                              Expr *LHS, Expr *RHS) {
6376  QualType LHSType;
6377  // PropertyRef on LHS type need be directly obtained from
6378  // its declaration as it has a PsuedoType.
6379  ObjCPropertyRefExpr *PRE
6380    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
6381  if (PRE && !PRE->isImplicitProperty()) {
6382    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6383    if (PD)
6384      LHSType = PD->getType();
6385  }
6386
6387  if (LHSType.isNull())
6388    LHSType = LHS->getType();
6389
6390  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
6391
6392  if (LT == Qualifiers::OCL_Weak) {
6393    DiagnosticsEngine::Level Level =
6394      Diags.getDiagnosticLevel(diag::warn_arc_repeated_use_of_weak, Loc);
6395    if (Level != DiagnosticsEngine::Ignored)
6396      getCurFunction()->markSafeWeakUse(LHS);
6397  }
6398
6399  if (checkUnsafeAssigns(Loc, LHSType, RHS))
6400    return;
6401
6402  // FIXME. Check for other life times.
6403  if (LT != Qualifiers::OCL_None)
6404    return;
6405
6406  if (PRE) {
6407    if (PRE->isImplicitProperty())
6408      return;
6409    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6410    if (!PD)
6411      return;
6412
6413    unsigned Attributes = PD->getPropertyAttributes();
6414    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
6415      // when 'assign' attribute was not explicitly specified
6416      // by user, ignore it and rely on property type itself
6417      // for lifetime info.
6418      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
6419      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
6420          LHSType->isObjCRetainableType())
6421        return;
6422
6423      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6424        if (cast->getCastKind() == CK_ARCConsumeObject) {
6425          Diag(Loc, diag::warn_arc_retained_property_assign)
6426          << RHS->getSourceRange();
6427          return;
6428        }
6429        RHS = cast->getSubExpr();
6430      }
6431    }
6432    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
6433      if (checkUnsafeAssignObject(*this, Loc, Qualifiers::OCL_Weak, RHS, true))
6434        return;
6435    }
6436  }
6437}
6438
6439//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
6440
6441namespace {
6442bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
6443                                 SourceLocation StmtLoc,
6444                                 const NullStmt *Body) {
6445  // Do not warn if the body is a macro that expands to nothing, e.g:
6446  //
6447  // #define CALL(x)
6448  // if (condition)
6449  //   CALL(0);
6450  //
6451  if (Body->hasLeadingEmptyMacro())
6452    return false;
6453
6454  // Get line numbers of statement and body.
6455  bool StmtLineInvalid;
6456  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
6457                                                      &StmtLineInvalid);
6458  if (StmtLineInvalid)
6459    return false;
6460
6461  bool BodyLineInvalid;
6462  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
6463                                                      &BodyLineInvalid);
6464  if (BodyLineInvalid)
6465    return false;
6466
6467  // Warn if null statement and body are on the same line.
6468  if (StmtLine != BodyLine)
6469    return false;
6470
6471  return true;
6472}
6473} // Unnamed namespace
6474
6475void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
6476                                 const Stmt *Body,
6477                                 unsigned DiagID) {
6478  // Since this is a syntactic check, don't emit diagnostic for template
6479  // instantiations, this just adds noise.
6480  if (CurrentInstantiationScope)
6481    return;
6482
6483  // The body should be a null statement.
6484  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6485  if (!NBody)
6486    return;
6487
6488  // Do the usual checks.
6489  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6490    return;
6491
6492  Diag(NBody->getSemiLoc(), DiagID);
6493  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6494}
6495
6496void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
6497                                 const Stmt *PossibleBody) {
6498  assert(!CurrentInstantiationScope); // Ensured by caller
6499
6500  SourceLocation StmtLoc;
6501  const Stmt *Body;
6502  unsigned DiagID;
6503  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
6504    StmtLoc = FS->getRParenLoc();
6505    Body = FS->getBody();
6506    DiagID = diag::warn_empty_for_body;
6507  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
6508    StmtLoc = WS->getCond()->getSourceRange().getEnd();
6509    Body = WS->getBody();
6510    DiagID = diag::warn_empty_while_body;
6511  } else
6512    return; // Neither `for' nor `while'.
6513
6514  // The body should be a null statement.
6515  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6516  if (!NBody)
6517    return;
6518
6519  // Skip expensive checks if diagnostic is disabled.
6520  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
6521          DiagnosticsEngine::Ignored)
6522    return;
6523
6524  // Do the usual checks.
6525  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6526    return;
6527
6528  // `for(...);' and `while(...);' are popular idioms, so in order to keep
6529  // noise level low, emit diagnostics only if for/while is followed by a
6530  // CompoundStmt, e.g.:
6531  //    for (int i = 0; i < n; i++);
6532  //    {
6533  //      a(i);
6534  //    }
6535  // or if for/while is followed by a statement with more indentation
6536  // than for/while itself:
6537  //    for (int i = 0; i < n; i++);
6538  //      a(i);
6539  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
6540  if (!ProbableTypo) {
6541    bool BodyColInvalid;
6542    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
6543                             PossibleBody->getLocStart(),
6544                             &BodyColInvalid);
6545    if (BodyColInvalid)
6546      return;
6547
6548    bool StmtColInvalid;
6549    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
6550                             S->getLocStart(),
6551                             &StmtColInvalid);
6552    if (StmtColInvalid)
6553      return;
6554
6555    if (BodyCol > StmtCol)
6556      ProbableTypo = true;
6557  }
6558
6559  if (ProbableTypo) {
6560    Diag(NBody->getSemiLoc(), DiagID);
6561    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6562  }
6563}
6564
6565//===--- Layout compatibility ----------------------------------------------//
6566
6567namespace {
6568
6569bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
6570
6571/// \brief Check if two enumeration types are layout-compatible.
6572bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
6573  // C++11 [dcl.enum] p8:
6574  // Two enumeration types are layout-compatible if they have the same
6575  // underlying type.
6576  return ED1->isComplete() && ED2->isComplete() &&
6577         C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
6578}
6579
6580/// \brief Check if two fields are layout-compatible.
6581bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
6582  if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
6583    return false;
6584
6585  if (Field1->isBitField() != Field2->isBitField())
6586    return false;
6587
6588  if (Field1->isBitField()) {
6589    // Make sure that the bit-fields are the same length.
6590    unsigned Bits1 = Field1->getBitWidthValue(C);
6591    unsigned Bits2 = Field2->getBitWidthValue(C);
6592
6593    if (Bits1 != Bits2)
6594      return false;
6595  }
6596
6597  return true;
6598}
6599
6600/// \brief Check if two standard-layout structs are layout-compatible.
6601/// (C++11 [class.mem] p17)
6602bool isLayoutCompatibleStruct(ASTContext &C,
6603                              RecordDecl *RD1,
6604                              RecordDecl *RD2) {
6605  // If both records are C++ classes, check that base classes match.
6606  if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
6607    // If one of records is a CXXRecordDecl we are in C++ mode,
6608    // thus the other one is a CXXRecordDecl, too.
6609    const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
6610    // Check number of base classes.
6611    if (D1CXX->getNumBases() != D2CXX->getNumBases())
6612      return false;
6613
6614    // Check the base classes.
6615    for (CXXRecordDecl::base_class_const_iterator
6616               Base1 = D1CXX->bases_begin(),
6617           BaseEnd1 = D1CXX->bases_end(),
6618              Base2 = D2CXX->bases_begin();
6619         Base1 != BaseEnd1;
6620         ++Base1, ++Base2) {
6621      if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
6622        return false;
6623    }
6624  } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
6625    // If only RD2 is a C++ class, it should have zero base classes.
6626    if (D2CXX->getNumBases() > 0)
6627      return false;
6628  }
6629
6630  // Check the fields.
6631  RecordDecl::field_iterator Field2 = RD2->field_begin(),
6632                             Field2End = RD2->field_end(),
6633                             Field1 = RD1->field_begin(),
6634                             Field1End = RD1->field_end();
6635  for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
6636    if (!isLayoutCompatible(C, *Field1, *Field2))
6637      return false;
6638  }
6639  if (Field1 != Field1End || Field2 != Field2End)
6640    return false;
6641
6642  return true;
6643}
6644
6645/// \brief Check if two standard-layout unions are layout-compatible.
6646/// (C++11 [class.mem] p18)
6647bool isLayoutCompatibleUnion(ASTContext &C,
6648                             RecordDecl *RD1,
6649                             RecordDecl *RD2) {
6650  llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
6651  for (RecordDecl::field_iterator Field2 = RD2->field_begin(),
6652                                  Field2End = RD2->field_end();
6653       Field2 != Field2End; ++Field2) {
6654    UnmatchedFields.insert(*Field2);
6655  }
6656
6657  for (RecordDecl::field_iterator Field1 = RD1->field_begin(),
6658                                  Field1End = RD1->field_end();
6659       Field1 != Field1End; ++Field1) {
6660    llvm::SmallPtrSet<FieldDecl *, 8>::iterator
6661        I = UnmatchedFields.begin(),
6662        E = UnmatchedFields.end();
6663
6664    for ( ; I != E; ++I) {
6665      if (isLayoutCompatible(C, *Field1, *I)) {
6666        bool Result = UnmatchedFields.erase(*I);
6667        (void) Result;
6668        assert(Result);
6669        break;
6670      }
6671    }
6672    if (I == E)
6673      return false;
6674  }
6675
6676  return UnmatchedFields.empty();
6677}
6678
6679bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
6680  if (RD1->isUnion() != RD2->isUnion())
6681    return false;
6682
6683  if (RD1->isUnion())
6684    return isLayoutCompatibleUnion(C, RD1, RD2);
6685  else
6686    return isLayoutCompatibleStruct(C, RD1, RD2);
6687}
6688
6689/// \brief Check if two types are layout-compatible in C++11 sense.
6690bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
6691  if (T1.isNull() || T2.isNull())
6692    return false;
6693
6694  // C++11 [basic.types] p11:
6695  // If two types T1 and T2 are the same type, then T1 and T2 are
6696  // layout-compatible types.
6697  if (C.hasSameType(T1, T2))
6698    return true;
6699
6700  T1 = T1.getCanonicalType().getUnqualifiedType();
6701  T2 = T2.getCanonicalType().getUnqualifiedType();
6702
6703  const Type::TypeClass TC1 = T1->getTypeClass();
6704  const Type::TypeClass TC2 = T2->getTypeClass();
6705
6706  if (TC1 != TC2)
6707    return false;
6708
6709  if (TC1 == Type::Enum) {
6710    return isLayoutCompatible(C,
6711                              cast<EnumType>(T1)->getDecl(),
6712                              cast<EnumType>(T2)->getDecl());
6713  } else if (TC1 == Type::Record) {
6714    if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
6715      return false;
6716
6717    return isLayoutCompatible(C,
6718                              cast<RecordType>(T1)->getDecl(),
6719                              cast<RecordType>(T2)->getDecl());
6720  }
6721
6722  return false;
6723}
6724}
6725
6726//===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
6727
6728namespace {
6729/// \brief Given a type tag expression find the type tag itself.
6730///
6731/// \param TypeExpr Type tag expression, as it appears in user's code.
6732///
6733/// \param VD Declaration of an identifier that appears in a type tag.
6734///
6735/// \param MagicValue Type tag magic value.
6736bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
6737                     const ValueDecl **VD, uint64_t *MagicValue) {
6738  while(true) {
6739    if (!TypeExpr)
6740      return false;
6741
6742    TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
6743
6744    switch (TypeExpr->getStmtClass()) {
6745    case Stmt::UnaryOperatorClass: {
6746      const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
6747      if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
6748        TypeExpr = UO->getSubExpr();
6749        continue;
6750      }
6751      return false;
6752    }
6753
6754    case Stmt::DeclRefExprClass: {
6755      const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
6756      *VD = DRE->getDecl();
6757      return true;
6758    }
6759
6760    case Stmt::IntegerLiteralClass: {
6761      const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
6762      llvm::APInt MagicValueAPInt = IL->getValue();
6763      if (MagicValueAPInt.getActiveBits() <= 64) {
6764        *MagicValue = MagicValueAPInt.getZExtValue();
6765        return true;
6766      } else
6767        return false;
6768    }
6769
6770    case Stmt::BinaryConditionalOperatorClass:
6771    case Stmt::ConditionalOperatorClass: {
6772      const AbstractConditionalOperator *ACO =
6773          cast<AbstractConditionalOperator>(TypeExpr);
6774      bool Result;
6775      if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
6776        if (Result)
6777          TypeExpr = ACO->getTrueExpr();
6778        else
6779          TypeExpr = ACO->getFalseExpr();
6780        continue;
6781      }
6782      return false;
6783    }
6784
6785    case Stmt::BinaryOperatorClass: {
6786      const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
6787      if (BO->getOpcode() == BO_Comma) {
6788        TypeExpr = BO->getRHS();
6789        continue;
6790      }
6791      return false;
6792    }
6793
6794    default:
6795      return false;
6796    }
6797  }
6798}
6799
6800/// \brief Retrieve the C type corresponding to type tag TypeExpr.
6801///
6802/// \param TypeExpr Expression that specifies a type tag.
6803///
6804/// \param MagicValues Registered magic values.
6805///
6806/// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
6807///        kind.
6808///
6809/// \param TypeInfo Information about the corresponding C type.
6810///
6811/// \returns true if the corresponding C type was found.
6812bool GetMatchingCType(
6813        const IdentifierInfo *ArgumentKind,
6814        const Expr *TypeExpr, const ASTContext &Ctx,
6815        const llvm::DenseMap<Sema::TypeTagMagicValue,
6816                             Sema::TypeTagData> *MagicValues,
6817        bool &FoundWrongKind,
6818        Sema::TypeTagData &TypeInfo) {
6819  FoundWrongKind = false;
6820
6821  // Variable declaration that has type_tag_for_datatype attribute.
6822  const ValueDecl *VD = NULL;
6823
6824  uint64_t MagicValue;
6825
6826  if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
6827    return false;
6828
6829  if (VD) {
6830    for (specific_attr_iterator<TypeTagForDatatypeAttr>
6831             I = VD->specific_attr_begin<TypeTagForDatatypeAttr>(),
6832             E = VD->specific_attr_end<TypeTagForDatatypeAttr>();
6833         I != E; ++I) {
6834      if (I->getArgumentKind() != ArgumentKind) {
6835        FoundWrongKind = true;
6836        return false;
6837      }
6838      TypeInfo.Type = I->getMatchingCType();
6839      TypeInfo.LayoutCompatible = I->getLayoutCompatible();
6840      TypeInfo.MustBeNull = I->getMustBeNull();
6841      return true;
6842    }
6843    return false;
6844  }
6845
6846  if (!MagicValues)
6847    return false;
6848
6849  llvm::DenseMap<Sema::TypeTagMagicValue,
6850                 Sema::TypeTagData>::const_iterator I =
6851      MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
6852  if (I == MagicValues->end())
6853    return false;
6854
6855  TypeInfo = I->second;
6856  return true;
6857}
6858} // unnamed namespace
6859
6860void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
6861                                      uint64_t MagicValue, QualType Type,
6862                                      bool LayoutCompatible,
6863                                      bool MustBeNull) {
6864  if (!TypeTagForDatatypeMagicValues)
6865    TypeTagForDatatypeMagicValues.reset(
6866        new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
6867
6868  TypeTagMagicValue Magic(ArgumentKind, MagicValue);
6869  (*TypeTagForDatatypeMagicValues)[Magic] =
6870      TypeTagData(Type, LayoutCompatible, MustBeNull);
6871}
6872
6873namespace {
6874bool IsSameCharType(QualType T1, QualType T2) {
6875  const BuiltinType *BT1 = T1->getAs<BuiltinType>();
6876  if (!BT1)
6877    return false;
6878
6879  const BuiltinType *BT2 = T2->getAs<BuiltinType>();
6880  if (!BT2)
6881    return false;
6882
6883  BuiltinType::Kind T1Kind = BT1->getKind();
6884  BuiltinType::Kind T2Kind = BT2->getKind();
6885
6886  return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
6887         (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
6888         (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
6889         (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
6890}
6891} // unnamed namespace
6892
6893void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
6894                                    const Expr * const *ExprArgs) {
6895  const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
6896  bool IsPointerAttr = Attr->getIsPointer();
6897
6898  const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
6899  bool FoundWrongKind;
6900  TypeTagData TypeInfo;
6901  if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
6902                        TypeTagForDatatypeMagicValues.get(),
6903                        FoundWrongKind, TypeInfo)) {
6904    if (FoundWrongKind)
6905      Diag(TypeTagExpr->getExprLoc(),
6906           diag::warn_type_tag_for_datatype_wrong_kind)
6907        << TypeTagExpr->getSourceRange();
6908    return;
6909  }
6910
6911  const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
6912  if (IsPointerAttr) {
6913    // Skip implicit cast of pointer to `void *' (as a function argument).
6914    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
6915      if (ICE->getType()->isVoidPointerType() &&
6916          ICE->getCastKind() == CK_BitCast)
6917        ArgumentExpr = ICE->getSubExpr();
6918  }
6919  QualType ArgumentType = ArgumentExpr->getType();
6920
6921  // Passing a `void*' pointer shouldn't trigger a warning.
6922  if (IsPointerAttr && ArgumentType->isVoidPointerType())
6923    return;
6924
6925  if (TypeInfo.MustBeNull) {
6926    // Type tag with matching void type requires a null pointer.
6927    if (!ArgumentExpr->isNullPointerConstant(Context,
6928                                             Expr::NPC_ValueDependentIsNotNull)) {
6929      Diag(ArgumentExpr->getExprLoc(),
6930           diag::warn_type_safety_null_pointer_required)
6931          << ArgumentKind->getName()
6932          << ArgumentExpr->getSourceRange()
6933          << TypeTagExpr->getSourceRange();
6934    }
6935    return;
6936  }
6937
6938  QualType RequiredType = TypeInfo.Type;
6939  if (IsPointerAttr)
6940    RequiredType = Context.getPointerType(RequiredType);
6941
6942  bool mismatch = false;
6943  if (!TypeInfo.LayoutCompatible) {
6944    mismatch = !Context.hasSameType(ArgumentType, RequiredType);
6945
6946    // C++11 [basic.fundamental] p1:
6947    // Plain char, signed char, and unsigned char are three distinct types.
6948    //
6949    // But we treat plain `char' as equivalent to `signed char' or `unsigned
6950    // char' depending on the current char signedness mode.
6951    if (mismatch)
6952      if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
6953                                           RequiredType->getPointeeType())) ||
6954          (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
6955        mismatch = false;
6956  } else
6957    if (IsPointerAttr)
6958      mismatch = !isLayoutCompatible(Context,
6959                                     ArgumentType->getPointeeType(),
6960                                     RequiredType->getPointeeType());
6961    else
6962      mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
6963
6964  if (mismatch)
6965    Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
6966        << ArgumentType << ArgumentKind->getName()
6967        << TypeInfo.LayoutCompatible << RequiredType
6968        << ArgumentExpr->getSourceRange()
6969        << TypeTagExpr->getSourceRange();
6970}
6971