SemaChecking.cpp revision f9eaf98bf524f7e2dcb9875a9f4afd9e25fc615d 
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements extra semantic analysis beyond what is enforced
11//  by the C type system.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/SemaInternal.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/CharUnits.h"
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/EvaluatedExprVisitor.h"
21#include "clang/AST/Expr.h"
22#include "clang/AST/ExprCXX.h"
23#include "clang/AST/ExprObjC.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/Analysis/Analyses/FormatString.h"
27#include "clang/Basic/CharInfo.h"
28#include "clang/Basic/TargetBuiltins.h"
29#include "clang/Basic/TargetInfo.h"
30#include "clang/Lex/Preprocessor.h"
31#include "clang/Sema/Initialization.h"
32#include "clang/Sema/Lookup.h"
33#include "clang/Sema/ScopeInfo.h"
34#include "clang/Sema/Sema.h"
35#include "llvm/ADT/BitVector.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/Support/ConvertUTF.h"
39#include "llvm/Support/raw_ostream.h"
40#include <limits>
41using namespace clang;
42using namespace sema;
43
44SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
45                                                    unsigned ByteNo) const {
46  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
47                               PP.getLangOpts(), PP.getTargetInfo());
48}
49
50/// Checks that a call expression's argument count is the desired number.
51/// This is useful when doing custom type-checking.  Returns true on error.
52static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
53  unsigned argCount = call->getNumArgs();
54  if (argCount == desiredArgCount) return false;
55
56  if (argCount < desiredArgCount)
57    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
58        << 0 /*function call*/ << desiredArgCount << argCount
59        << call->getSourceRange();
60
61  // Highlight all the excess arguments.
62  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
63                    call->getArg(argCount - 1)->getLocEnd());
64
65  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
66    << 0 /*function call*/ << desiredArgCount << argCount
67    << call->getArg(1)->getSourceRange();
68}
69
70/// Check that the first argument to __builtin_annotation is an integer
71/// and the second argument is a non-wide string literal.
72static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
73  if (checkArgCount(S, TheCall, 2))
74    return true;
75
76  // First argument should be an integer.
77  Expr *ValArg = TheCall->getArg(0);
78  QualType Ty = ValArg->getType();
79  if (!Ty->isIntegerType()) {
80    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
81      << ValArg->getSourceRange();
82    return true;
83  }
84
85  // Second argument should be a constant string.
86  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
87  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
88  if (!Literal || !Literal->isAscii()) {
89    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
90      << StrArg->getSourceRange();
91    return true;
92  }
93
94  TheCall->setType(Ty);
95  return false;
96}
97
98ExprResult
99Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
100  ExprResult TheCallResult(Owned(TheCall));
101
102  // Find out if any arguments are required to be integer constant expressions.
103  unsigned ICEArguments = 0;
104  ASTContext::GetBuiltinTypeError Error;
105  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
106  if (Error != ASTContext::GE_None)
107    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
108
109  // If any arguments are required to be ICE's, check and diagnose.
110  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
111    // Skip arguments not required to be ICE's.
112    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
113
114    llvm::APSInt Result;
115    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
116      return true;
117    ICEArguments &= ~(1 << ArgNo);
118  }
119
120  switch (BuiltinID) {
121  case Builtin::BI__builtin___CFStringMakeConstantString:
122    assert(TheCall->getNumArgs() == 1 &&
123           "Wrong # arguments to builtin CFStringMakeConstantString");
124    if (CheckObjCString(TheCall->getArg(0)))
125      return ExprError();
126    break;
127  case Builtin::BI__builtin_stdarg_start:
128  case Builtin::BI__builtin_va_start:
129    if (SemaBuiltinVAStart(TheCall))
130      return ExprError();
131    break;
132  case Builtin::BI__builtin_isgreater:
133  case Builtin::BI__builtin_isgreaterequal:
134  case Builtin::BI__builtin_isless:
135  case Builtin::BI__builtin_islessequal:
136  case Builtin::BI__builtin_islessgreater:
137  case Builtin::BI__builtin_isunordered:
138    if (SemaBuiltinUnorderedCompare(TheCall))
139      return ExprError();
140    break;
141  case Builtin::BI__builtin_fpclassify:
142    if (SemaBuiltinFPClassification(TheCall, 6))
143      return ExprError();
144    break;
145  case Builtin::BI__builtin_isfinite:
146  case Builtin::BI__builtin_isinf:
147  case Builtin::BI__builtin_isinf_sign:
148  case Builtin::BI__builtin_isnan:
149  case Builtin::BI__builtin_isnormal:
150    if (SemaBuiltinFPClassification(TheCall, 1))
151      return ExprError();
152    break;
153  case Builtin::BI__builtin_shufflevector:
154    return SemaBuiltinShuffleVector(TheCall);
155    // TheCall will be freed by the smart pointer here, but that's fine, since
156    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
157  case Builtin::BI__builtin_prefetch:
158    if (SemaBuiltinPrefetch(TheCall))
159      return ExprError();
160    break;
161  case Builtin::BI__builtin_object_size:
162    if (SemaBuiltinObjectSize(TheCall))
163      return ExprError();
164    break;
165  case Builtin::BI__builtin_longjmp:
166    if (SemaBuiltinLongjmp(TheCall))
167      return ExprError();
168    break;
169
170  case Builtin::BI__builtin_classify_type:
171    if (checkArgCount(*this, TheCall, 1)) return true;
172    TheCall->setType(Context.IntTy);
173    break;
174  case Builtin::BI__builtin_constant_p:
175    if (checkArgCount(*this, TheCall, 1)) return true;
176    TheCall->setType(Context.IntTy);
177    break;
178  case Builtin::BI__sync_fetch_and_add:
179  case Builtin::BI__sync_fetch_and_add_1:
180  case Builtin::BI__sync_fetch_and_add_2:
181  case Builtin::BI__sync_fetch_and_add_4:
182  case Builtin::BI__sync_fetch_and_add_8:
183  case Builtin::BI__sync_fetch_and_add_16:
184  case Builtin::BI__sync_fetch_and_sub:
185  case Builtin::BI__sync_fetch_and_sub_1:
186  case Builtin::BI__sync_fetch_and_sub_2:
187  case Builtin::BI__sync_fetch_and_sub_4:
188  case Builtin::BI__sync_fetch_and_sub_8:
189  case Builtin::BI__sync_fetch_and_sub_16:
190  case Builtin::BI__sync_fetch_and_or:
191  case Builtin::BI__sync_fetch_and_or_1:
192  case Builtin::BI__sync_fetch_and_or_2:
193  case Builtin::BI__sync_fetch_and_or_4:
194  case Builtin::BI__sync_fetch_and_or_8:
195  case Builtin::BI__sync_fetch_and_or_16:
196  case Builtin::BI__sync_fetch_and_and:
197  case Builtin::BI__sync_fetch_and_and_1:
198  case Builtin::BI__sync_fetch_and_and_2:
199  case Builtin::BI__sync_fetch_and_and_4:
200  case Builtin::BI__sync_fetch_and_and_8:
201  case Builtin::BI__sync_fetch_and_and_16:
202  case Builtin::BI__sync_fetch_and_xor:
203  case Builtin::BI__sync_fetch_and_xor_1:
204  case Builtin::BI__sync_fetch_and_xor_2:
205  case Builtin::BI__sync_fetch_and_xor_4:
206  case Builtin::BI__sync_fetch_and_xor_8:
207  case Builtin::BI__sync_fetch_and_xor_16:
208  case Builtin::BI__sync_add_and_fetch:
209  case Builtin::BI__sync_add_and_fetch_1:
210  case Builtin::BI__sync_add_and_fetch_2:
211  case Builtin::BI__sync_add_and_fetch_4:
212  case Builtin::BI__sync_add_and_fetch_8:
213  case Builtin::BI__sync_add_and_fetch_16:
214  case Builtin::BI__sync_sub_and_fetch:
215  case Builtin::BI__sync_sub_and_fetch_1:
216  case Builtin::BI__sync_sub_and_fetch_2:
217  case Builtin::BI__sync_sub_and_fetch_4:
218  case Builtin::BI__sync_sub_and_fetch_8:
219  case Builtin::BI__sync_sub_and_fetch_16:
220  case Builtin::BI__sync_and_and_fetch:
221  case Builtin::BI__sync_and_and_fetch_1:
222  case Builtin::BI__sync_and_and_fetch_2:
223  case Builtin::BI__sync_and_and_fetch_4:
224  case Builtin::BI__sync_and_and_fetch_8:
225  case Builtin::BI__sync_and_and_fetch_16:
226  case Builtin::BI__sync_or_and_fetch:
227  case Builtin::BI__sync_or_and_fetch_1:
228  case Builtin::BI__sync_or_and_fetch_2:
229  case Builtin::BI__sync_or_and_fetch_4:
230  case Builtin::BI__sync_or_and_fetch_8:
231  case Builtin::BI__sync_or_and_fetch_16:
232  case Builtin::BI__sync_xor_and_fetch:
233  case Builtin::BI__sync_xor_and_fetch_1:
234  case Builtin::BI__sync_xor_and_fetch_2:
235  case Builtin::BI__sync_xor_and_fetch_4:
236  case Builtin::BI__sync_xor_and_fetch_8:
237  case Builtin::BI__sync_xor_and_fetch_16:
238  case Builtin::BI__sync_val_compare_and_swap:
239  case Builtin::BI__sync_val_compare_and_swap_1:
240  case Builtin::BI__sync_val_compare_and_swap_2:
241  case Builtin::BI__sync_val_compare_and_swap_4:
242  case Builtin::BI__sync_val_compare_and_swap_8:
243  case Builtin::BI__sync_val_compare_and_swap_16:
244  case Builtin::BI__sync_bool_compare_and_swap:
245  case Builtin::BI__sync_bool_compare_and_swap_1:
246  case Builtin::BI__sync_bool_compare_and_swap_2:
247  case Builtin::BI__sync_bool_compare_and_swap_4:
248  case Builtin::BI__sync_bool_compare_and_swap_8:
249  case Builtin::BI__sync_bool_compare_and_swap_16:
250  case Builtin::BI__sync_lock_test_and_set:
251  case Builtin::BI__sync_lock_test_and_set_1:
252  case Builtin::BI__sync_lock_test_and_set_2:
253  case Builtin::BI__sync_lock_test_and_set_4:
254  case Builtin::BI__sync_lock_test_and_set_8:
255  case Builtin::BI__sync_lock_test_and_set_16:
256  case Builtin::BI__sync_lock_release:
257  case Builtin::BI__sync_lock_release_1:
258  case Builtin::BI__sync_lock_release_2:
259  case Builtin::BI__sync_lock_release_4:
260  case Builtin::BI__sync_lock_release_8:
261  case Builtin::BI__sync_lock_release_16:
262  case Builtin::BI__sync_swap:
263  case Builtin::BI__sync_swap_1:
264  case Builtin::BI__sync_swap_2:
265  case Builtin::BI__sync_swap_4:
266  case Builtin::BI__sync_swap_8:
267  case Builtin::BI__sync_swap_16:
268    return SemaBuiltinAtomicOverloaded(TheCallResult);
269#define BUILTIN(ID, TYPE, ATTRS)
270#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
271  case Builtin::BI##ID: \
272    return SemaAtomicOpsOverloaded(TheCallResult, AtomicExpr::AO##ID);
273#include "clang/Basic/Builtins.def"
274  case Builtin::BI__builtin_annotation:
275    if (SemaBuiltinAnnotation(*this, TheCall))
276      return ExprError();
277    break;
278  }
279
280  // Since the target specific builtins for each arch overlap, only check those
281  // of the arch we are compiling for.
282  if (BuiltinID >= Builtin::FirstTSBuiltin) {
283    switch (Context.getTargetInfo().getTriple().getArch()) {
284      case llvm::Triple::arm:
285      case llvm::Triple::thumb:
286        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
287          return ExprError();
288        break;
289      case llvm::Triple::mips:
290      case llvm::Triple::mipsel:
291      case llvm::Triple::mips64:
292      case llvm::Triple::mips64el:
293        if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
294          return ExprError();
295        break;
296      default:
297        break;
298    }
299  }
300
301  return TheCallResult;
302}
303
304// Get the valid immediate range for the specified NEON type code.
305static unsigned RFT(unsigned t, bool shift = false) {
306  NeonTypeFlags Type(t);
307  int IsQuad = Type.isQuad();
308  switch (Type.getEltType()) {
309  case NeonTypeFlags::Int8:
310  case NeonTypeFlags::Poly8:
311    return shift ? 7 : (8 << IsQuad) - 1;
312  case NeonTypeFlags::Int16:
313  case NeonTypeFlags::Poly16:
314    return shift ? 15 : (4 << IsQuad) - 1;
315  case NeonTypeFlags::Int32:
316    return shift ? 31 : (2 << IsQuad) - 1;
317  case NeonTypeFlags::Int64:
318    return shift ? 63 : (1 << IsQuad) - 1;
319  case NeonTypeFlags::Float16:
320    assert(!shift && "cannot shift float types!");
321    return (4 << IsQuad) - 1;
322  case NeonTypeFlags::Float32:
323    assert(!shift && "cannot shift float types!");
324    return (2 << IsQuad) - 1;
325  }
326  llvm_unreachable("Invalid NeonTypeFlag!");
327}
328
329/// getNeonEltType - Return the QualType corresponding to the elements of
330/// the vector type specified by the NeonTypeFlags.  This is used to check
331/// the pointer arguments for Neon load/store intrinsics.
332static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
333  switch (Flags.getEltType()) {
334  case NeonTypeFlags::Int8:
335    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
336  case NeonTypeFlags::Int16:
337    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
338  case NeonTypeFlags::Int32:
339    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
340  case NeonTypeFlags::Int64:
341    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
342  case NeonTypeFlags::Poly8:
343    return Context.SignedCharTy;
344  case NeonTypeFlags::Poly16:
345    return Context.ShortTy;
346  case NeonTypeFlags::Float16:
347    return Context.UnsignedShortTy;
348  case NeonTypeFlags::Float32:
349    return Context.FloatTy;
350  }
351  llvm_unreachable("Invalid NeonTypeFlag!");
352}
353
354bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
355  llvm::APSInt Result;
356
357  uint64_t mask = 0;
358  unsigned TV = 0;
359  int PtrArgNum = -1;
360  bool HasConstPtr = false;
361  switch (BuiltinID) {
362#define GET_NEON_OVERLOAD_CHECK
363#include "clang/Basic/arm_neon.inc"
364#undef GET_NEON_OVERLOAD_CHECK
365  }
366
367  // For NEON intrinsics which are overloaded on vector element type, validate
368  // the immediate which specifies which variant to emit.
369  unsigned ImmArg = TheCall->getNumArgs()-1;
370  if (mask) {
371    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
372      return true;
373
374    TV = Result.getLimitedValue(64);
375    if ((TV > 63) || (mask & (1ULL << TV)) == 0)
376      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
377        << TheCall->getArg(ImmArg)->getSourceRange();
378  }
379
380  if (PtrArgNum >= 0) {
381    // Check that pointer arguments have the specified type.
382    Expr *Arg = TheCall->getArg(PtrArgNum);
383    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
384      Arg = ICE->getSubExpr();
385    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
386    QualType RHSTy = RHS.get()->getType();
387    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
388    if (HasConstPtr)
389      EltTy = EltTy.withConst();
390    QualType LHSTy = Context.getPointerType(EltTy);
391    AssignConvertType ConvTy;
392    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
393    if (RHS.isInvalid())
394      return true;
395    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
396                                 RHS.get(), AA_Assigning))
397      return true;
398  }
399
400  // For NEON intrinsics which take an immediate value as part of the
401  // instruction, range check them here.
402  unsigned i = 0, l = 0, u = 0;
403  switch (BuiltinID) {
404  default: return false;
405  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
406  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
407  case ARM::BI__builtin_arm_vcvtr_f:
408  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
409#define GET_NEON_IMMEDIATE_CHECK
410#include "clang/Basic/arm_neon.inc"
411#undef GET_NEON_IMMEDIATE_CHECK
412  };
413
414  // We can't check the value of a dependent argument.
415  if (TheCall->getArg(i)->isTypeDependent() ||
416      TheCall->getArg(i)->isValueDependent())
417    return false;
418
419  // Check that the immediate argument is actually a constant.
420  if (SemaBuiltinConstantArg(TheCall, i, Result))
421    return true;
422
423  // Range check against the upper/lower values for this isntruction.
424  unsigned Val = Result.getZExtValue();
425  if (Val < l || Val > (u + l))
426    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
427      << l << u+l << TheCall->getArg(i)->getSourceRange();
428
429  // FIXME: VFP Intrinsics should error if VFP not present.
430  return false;
431}
432
433bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
434  unsigned i = 0, l = 0, u = 0;
435  switch (BuiltinID) {
436  default: return false;
437  case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
438  case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
439  case Mips::BI__builtin_mips_append: i = 2; l = 0; u = 31; break;
440  case Mips::BI__builtin_mips_balign: i = 2; l = 0; u = 3; break;
441  case Mips::BI__builtin_mips_precr_sra_ph_w: i = 2; l = 0; u = 31; break;
442  case Mips::BI__builtin_mips_precr_sra_r_ph_w: i = 2; l = 0; u = 31; break;
443  case Mips::BI__builtin_mips_prepend: i = 2; l = 0; u = 31; break;
444  };
445
446  // We can't check the value of a dependent argument.
447  if (TheCall->getArg(i)->isTypeDependent() ||
448      TheCall->getArg(i)->isValueDependent())
449    return false;
450
451  // Check that the immediate argument is actually a constant.
452  llvm::APSInt Result;
453  if (SemaBuiltinConstantArg(TheCall, i, Result))
454    return true;
455
456  // Range check against the upper/lower values for this instruction.
457  unsigned Val = Result.getZExtValue();
458  if (Val < l || Val > u)
459    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
460      << l << u << TheCall->getArg(i)->getSourceRange();
461
462  return false;
463}
464
465/// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
466/// parameter with the FormatAttr's correct format_idx and firstDataArg.
467/// Returns true when the format fits the function and the FormatStringInfo has
468/// been populated.
469bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
470                               FormatStringInfo *FSI) {
471  FSI->HasVAListArg = Format->getFirstArg() == 0;
472  FSI->FormatIdx = Format->getFormatIdx() - 1;
473  FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
474
475  // The way the format attribute works in GCC, the implicit this argument
476  // of member functions is counted. However, it doesn't appear in our own
477  // lists, so decrement format_idx in that case.
478  if (IsCXXMember) {
479    if(FSI->FormatIdx == 0)
480      return false;
481    --FSI->FormatIdx;
482    if (FSI->FirstDataArg != 0)
483      --FSI->FirstDataArg;
484  }
485  return true;
486}
487
488/// Handles the checks for format strings, non-POD arguments to vararg
489/// functions, and NULL arguments passed to non-NULL parameters.
490void Sema::checkCall(NamedDecl *FDecl,
491                     ArrayRef<const Expr *> Args,
492                     unsigned NumProtoArgs,
493                     bool IsMemberFunction,
494                     SourceLocation Loc,
495                     SourceRange Range,
496                     VariadicCallType CallType) {
497  if (CurContext->isDependentContext())
498    return;
499
500  // Printf and scanf checking.
501  bool HandledFormatString = false;
502  for (specific_attr_iterator<FormatAttr>
503         I = FDecl->specific_attr_begin<FormatAttr>(),
504         E = FDecl->specific_attr_end<FormatAttr>(); I != E ; ++I)
505    if (CheckFormatArguments(*I, Args, IsMemberFunction, CallType, Loc, Range))
506        HandledFormatString = true;
507
508  // Refuse POD arguments that weren't caught by the format string
509  // checks above.
510  if (!HandledFormatString && CallType != VariadicDoesNotApply)
511    for (unsigned ArgIdx = NumProtoArgs; ArgIdx < Args.size(); ++ArgIdx) {
512      // Args[ArgIdx] can be null in malformed code.
513      if (const Expr *Arg = Args[ArgIdx])
514        variadicArgumentPODCheck(Arg, CallType);
515    }
516
517  for (specific_attr_iterator<NonNullAttr>
518         I = FDecl->specific_attr_begin<NonNullAttr>(),
519         E = FDecl->specific_attr_end<NonNullAttr>(); I != E; ++I)
520    CheckNonNullArguments(*I, Args.data(), Loc);
521
522  // Type safety checking.
523  for (specific_attr_iterator<ArgumentWithTypeTagAttr>
524         i = FDecl->specific_attr_begin<ArgumentWithTypeTagAttr>(),
525         e = FDecl->specific_attr_end<ArgumentWithTypeTagAttr>(); i != e; ++i) {
526    CheckArgumentWithTypeTag(*i, Args.data());
527  }
528}
529
530/// CheckConstructorCall - Check a constructor call for correctness and safety
531/// properties not enforced by the C type system.
532void Sema::CheckConstructorCall(FunctionDecl *FDecl,
533                                ArrayRef<const Expr *> Args,
534                                const FunctionProtoType *Proto,
535                                SourceLocation Loc) {
536  VariadicCallType CallType =
537    Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
538  checkCall(FDecl, Args, Proto->getNumArgs(),
539            /*IsMemberFunction=*/true, Loc, SourceRange(), CallType);
540}
541
542/// CheckFunctionCall - Check a direct function call for various correctness
543/// and safety properties not strictly enforced by the C type system.
544bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
545                             const FunctionProtoType *Proto) {
546  bool IsMemberOperatorCall = isa<CXXOperatorCallExpr>(TheCall) &&
547                              isa<CXXMethodDecl>(FDecl);
548  bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall) ||
549                          IsMemberOperatorCall;
550  VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
551                                                  TheCall->getCallee());
552  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
553  Expr** Args = TheCall->getArgs();
554  unsigned NumArgs = TheCall->getNumArgs();
555  if (IsMemberOperatorCall) {
556    // If this is a call to a member operator, hide the first argument
557    // from checkCall.
558    // FIXME: Our choice of AST representation here is less than ideal.
559    ++Args;
560    --NumArgs;
561  }
562  checkCall(FDecl, llvm::makeArrayRef<const Expr *>(Args, NumArgs),
563            NumProtoArgs,
564            IsMemberFunction, TheCall->getRParenLoc(),
565            TheCall->getCallee()->getSourceRange(), CallType);
566
567  IdentifierInfo *FnInfo = FDecl->getIdentifier();
568  // None of the checks below are needed for functions that don't have
569  // simple names (e.g., C++ conversion functions).
570  if (!FnInfo)
571    return false;
572
573  unsigned CMId = FDecl->getMemoryFunctionKind();
574  if (CMId == 0)
575    return false;
576
577  // Handle memory setting and copying functions.
578  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
579    CheckStrlcpycatArguments(TheCall, FnInfo);
580  else if (CMId == Builtin::BIstrncat)
581    CheckStrncatArguments(TheCall, FnInfo);
582  else
583    CheckMemaccessArguments(TheCall, CMId, FnInfo);
584
585  return false;
586}
587
588bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
589                               ArrayRef<const Expr *> Args) {
590  VariadicCallType CallType =
591      Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
592
593  checkCall(Method, Args, Method->param_size(),
594            /*IsMemberFunction=*/false,
595            lbrac, Method->getSourceRange(), CallType);
596
597  return false;
598}
599
600bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall,
601                          const FunctionProtoType *Proto) {
602  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
603  if (!V)
604    return false;
605
606  QualType Ty = V->getType();
607  if (!Ty->isBlockPointerType())
608    return false;
609
610  VariadicCallType CallType =
611      Proto && Proto->isVariadic() ? VariadicBlock : VariadicDoesNotApply ;
612  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
613
614  checkCall(NDecl,
615            llvm::makeArrayRef<const Expr *>(TheCall->getArgs(),
616                                             TheCall->getNumArgs()),
617            NumProtoArgs, /*IsMemberFunction=*/false,
618            TheCall->getRParenLoc(),
619            TheCall->getCallee()->getSourceRange(), CallType);
620
621  return false;
622}
623
624ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
625                                         AtomicExpr::AtomicOp Op) {
626  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
627  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
628
629  // All these operations take one of the following forms:
630  enum {
631    // C    __c11_atomic_init(A *, C)
632    Init,
633    // C    __c11_atomic_load(A *, int)
634    Load,
635    // void __atomic_load(A *, CP, int)
636    Copy,
637    // C    __c11_atomic_add(A *, M, int)
638    Arithmetic,
639    // C    __atomic_exchange_n(A *, CP, int)
640    Xchg,
641    // void __atomic_exchange(A *, C *, CP, int)
642    GNUXchg,
643    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
644    C11CmpXchg,
645    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
646    GNUCmpXchg
647  } Form = Init;
648  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
649  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
650  // where:
651  //   C is an appropriate type,
652  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
653  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
654  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
655  //   the int parameters are for orderings.
656
657  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
658         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
659         && "need to update code for modified C11 atomics");
660  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
661               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
662  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
663             Op == AtomicExpr::AO__atomic_store_n ||
664             Op == AtomicExpr::AO__atomic_exchange_n ||
665             Op == AtomicExpr::AO__atomic_compare_exchange_n;
666  bool IsAddSub = false;
667
668  switch (Op) {
669  case AtomicExpr::AO__c11_atomic_init:
670    Form = Init;
671    break;
672
673  case AtomicExpr::AO__c11_atomic_load:
674  case AtomicExpr::AO__atomic_load_n:
675    Form = Load;
676    break;
677
678  case AtomicExpr::AO__c11_atomic_store:
679  case AtomicExpr::AO__atomic_load:
680  case AtomicExpr::AO__atomic_store:
681  case AtomicExpr::AO__atomic_store_n:
682    Form = Copy;
683    break;
684
685  case AtomicExpr::AO__c11_atomic_fetch_add:
686  case AtomicExpr::AO__c11_atomic_fetch_sub:
687  case AtomicExpr::AO__atomic_fetch_add:
688  case AtomicExpr::AO__atomic_fetch_sub:
689  case AtomicExpr::AO__atomic_add_fetch:
690  case AtomicExpr::AO__atomic_sub_fetch:
691    IsAddSub = true;
692    // Fall through.
693  case AtomicExpr::AO__c11_atomic_fetch_and:
694  case AtomicExpr::AO__c11_atomic_fetch_or:
695  case AtomicExpr::AO__c11_atomic_fetch_xor:
696  case AtomicExpr::AO__atomic_fetch_and:
697  case AtomicExpr::AO__atomic_fetch_or:
698  case AtomicExpr::AO__atomic_fetch_xor:
699  case AtomicExpr::AO__atomic_fetch_nand:
700  case AtomicExpr::AO__atomic_and_fetch:
701  case AtomicExpr::AO__atomic_or_fetch:
702  case AtomicExpr::AO__atomic_xor_fetch:
703  case AtomicExpr::AO__atomic_nand_fetch:
704    Form = Arithmetic;
705    break;
706
707  case AtomicExpr::AO__c11_atomic_exchange:
708  case AtomicExpr::AO__atomic_exchange_n:
709    Form = Xchg;
710    break;
711
712  case AtomicExpr::AO__atomic_exchange:
713    Form = GNUXchg;
714    break;
715
716  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
717  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
718    Form = C11CmpXchg;
719    break;
720
721  case AtomicExpr::AO__atomic_compare_exchange:
722  case AtomicExpr::AO__atomic_compare_exchange_n:
723    Form = GNUCmpXchg;
724    break;
725  }
726
727  // Check we have the right number of arguments.
728  if (TheCall->getNumArgs() < NumArgs[Form]) {
729    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
730      << 0 << NumArgs[Form] << TheCall->getNumArgs()
731      << TheCall->getCallee()->getSourceRange();
732    return ExprError();
733  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
734    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
735         diag::err_typecheck_call_too_many_args)
736      << 0 << NumArgs[Form] << TheCall->getNumArgs()
737      << TheCall->getCallee()->getSourceRange();
738    return ExprError();
739  }
740
741  // Inspect the first argument of the atomic operation.
742  Expr *Ptr = TheCall->getArg(0);
743  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
744  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
745  if (!pointerType) {
746    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
747      << Ptr->getType() << Ptr->getSourceRange();
748    return ExprError();
749  }
750
751  // For a __c11 builtin, this should be a pointer to an _Atomic type.
752  QualType AtomTy = pointerType->getPointeeType(); // 'A'
753  QualType ValType = AtomTy; // 'C'
754  if (IsC11) {
755    if (!AtomTy->isAtomicType()) {
756      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
757        << Ptr->getType() << Ptr->getSourceRange();
758      return ExprError();
759    }
760    if (AtomTy.isConstQualified()) {
761      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
762        << Ptr->getType() << Ptr->getSourceRange();
763      return ExprError();
764    }
765    ValType = AtomTy->getAs<AtomicType>()->getValueType();
766  }
767
768  // For an arithmetic operation, the implied arithmetic must be well-formed.
769  if (Form == Arithmetic) {
770    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
771    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
772      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
773        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
774      return ExprError();
775    }
776    if (!IsAddSub && !ValType->isIntegerType()) {
777      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
778        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
779      return ExprError();
780    }
781  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
782    // For __atomic_*_n operations, the value type must be a scalar integral or
783    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
784    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
785      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
786    return ExprError();
787  }
788
789  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
790    // For GNU atomics, require a trivially-copyable type. This is not part of
791    // the GNU atomics specification, but we enforce it for sanity.
792    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
793      << Ptr->getType() << Ptr->getSourceRange();
794    return ExprError();
795  }
796
797  // FIXME: For any builtin other than a load, the ValType must not be
798  // const-qualified.
799
800  switch (ValType.getObjCLifetime()) {
801  case Qualifiers::OCL_None:
802  case Qualifiers::OCL_ExplicitNone:
803    // okay
804    break;
805
806  case Qualifiers::OCL_Weak:
807  case Qualifiers::OCL_Strong:
808  case Qualifiers::OCL_Autoreleasing:
809    // FIXME: Can this happen? By this point, ValType should be known
810    // to be trivially copyable.
811    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
812      << ValType << Ptr->getSourceRange();
813    return ExprError();
814  }
815
816  QualType ResultType = ValType;
817  if (Form == Copy || Form == GNUXchg || Form == Init)
818    ResultType = Context.VoidTy;
819  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
820    ResultType = Context.BoolTy;
821
822  // The type of a parameter passed 'by value'. In the GNU atomics, such
823  // arguments are actually passed as pointers.
824  QualType ByValType = ValType; // 'CP'
825  if (!IsC11 && !IsN)
826    ByValType = Ptr->getType();
827
828  // The first argument --- the pointer --- has a fixed type; we
829  // deduce the types of the rest of the arguments accordingly.  Walk
830  // the remaining arguments, converting them to the deduced value type.
831  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
832    QualType Ty;
833    if (i < NumVals[Form] + 1) {
834      switch (i) {
835      case 1:
836        // The second argument is the non-atomic operand. For arithmetic, this
837        // is always passed by value, and for a compare_exchange it is always
838        // passed by address. For the rest, GNU uses by-address and C11 uses
839        // by-value.
840        assert(Form != Load);
841        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
842          Ty = ValType;
843        else if (Form == Copy || Form == Xchg)
844          Ty = ByValType;
845        else if (Form == Arithmetic)
846          Ty = Context.getPointerDiffType();
847        else
848          Ty = Context.getPointerType(ValType.getUnqualifiedType());
849        break;
850      case 2:
851        // The third argument to compare_exchange / GNU exchange is a
852        // (pointer to a) desired value.
853        Ty = ByValType;
854        break;
855      case 3:
856        // The fourth argument to GNU compare_exchange is a 'weak' flag.
857        Ty = Context.BoolTy;
858        break;
859      }
860    } else {
861      // The order(s) are always converted to int.
862      Ty = Context.IntTy;
863    }
864
865    InitializedEntity Entity =
866        InitializedEntity::InitializeParameter(Context, Ty, false);
867    ExprResult Arg = TheCall->getArg(i);
868    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
869    if (Arg.isInvalid())
870      return true;
871    TheCall->setArg(i, Arg.get());
872  }
873
874  // Permute the arguments into a 'consistent' order.
875  SmallVector<Expr*, 5> SubExprs;
876  SubExprs.push_back(Ptr);
877  switch (Form) {
878  case Init:
879    // Note, AtomicExpr::getVal1() has a special case for this atomic.
880    SubExprs.push_back(TheCall->getArg(1)); // Val1
881    break;
882  case Load:
883    SubExprs.push_back(TheCall->getArg(1)); // Order
884    break;
885  case Copy:
886  case Arithmetic:
887  case Xchg:
888    SubExprs.push_back(TheCall->getArg(2)); // Order
889    SubExprs.push_back(TheCall->getArg(1)); // Val1
890    break;
891  case GNUXchg:
892    // Note, AtomicExpr::getVal2() has a special case for this atomic.
893    SubExprs.push_back(TheCall->getArg(3)); // Order
894    SubExprs.push_back(TheCall->getArg(1)); // Val1
895    SubExprs.push_back(TheCall->getArg(2)); // Val2
896    break;
897  case C11CmpXchg:
898    SubExprs.push_back(TheCall->getArg(3)); // Order
899    SubExprs.push_back(TheCall->getArg(1)); // Val1
900    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
901    SubExprs.push_back(TheCall->getArg(2)); // Val2
902    break;
903  case GNUCmpXchg:
904    SubExprs.push_back(TheCall->getArg(4)); // Order
905    SubExprs.push_back(TheCall->getArg(1)); // Val1
906    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
907    SubExprs.push_back(TheCall->getArg(2)); // Val2
908    SubExprs.push_back(TheCall->getArg(3)); // Weak
909    break;
910  }
911
912  AtomicExpr *AE = new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
913                                            SubExprs, ResultType, Op,
914                                            TheCall->getRParenLoc());
915
916  if ((Op == AtomicExpr::AO__c11_atomic_load ||
917       (Op == AtomicExpr::AO__c11_atomic_store)) &&
918      Context.AtomicUsesUnsupportedLibcall(AE))
919    Diag(AE->getLocStart(), diag::err_atomic_load_store_uses_lib) <<
920    ((Op == AtomicExpr::AO__c11_atomic_load) ? 0 : 1);
921
922  return Owned(AE);
923}
924
925
926/// checkBuiltinArgument - Given a call to a builtin function, perform
927/// normal type-checking on the given argument, updating the call in
928/// place.  This is useful when a builtin function requires custom
929/// type-checking for some of its arguments but not necessarily all of
930/// them.
931///
932/// Returns true on error.
933static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
934  FunctionDecl *Fn = E->getDirectCallee();
935  assert(Fn && "builtin call without direct callee!");
936
937  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
938  InitializedEntity Entity =
939    InitializedEntity::InitializeParameter(S.Context, Param);
940
941  ExprResult Arg = E->getArg(0);
942  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
943  if (Arg.isInvalid())
944    return true;
945
946  E->setArg(ArgIndex, Arg.take());
947  return false;
948}
949
950/// SemaBuiltinAtomicOverloaded - We have a call to a function like
951/// __sync_fetch_and_add, which is an overloaded function based on the pointer
952/// type of its first argument.  The main ActOnCallExpr routines have already
953/// promoted the types of arguments because all of these calls are prototyped as
954/// void(...).
955///
956/// This function goes through and does final semantic checking for these
957/// builtins,
958ExprResult
959Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
960  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
961  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
962  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
963
964  // Ensure that we have at least one argument to do type inference from.
965  if (TheCall->getNumArgs() < 1) {
966    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
967      << 0 << 1 << TheCall->getNumArgs()
968      << TheCall->getCallee()->getSourceRange();
969    return ExprError();
970  }
971
972  // Inspect the first argument of the atomic builtin.  This should always be
973  // a pointer type, whose element is an integral scalar or pointer type.
974  // Because it is a pointer type, we don't have to worry about any implicit
975  // casts here.
976  // FIXME: We don't allow floating point scalars as input.
977  Expr *FirstArg = TheCall->getArg(0);
978  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
979  if (FirstArgResult.isInvalid())
980    return ExprError();
981  FirstArg = FirstArgResult.take();
982  TheCall->setArg(0, FirstArg);
983
984  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
985  if (!pointerType) {
986    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
987      << FirstArg->getType() << FirstArg->getSourceRange();
988    return ExprError();
989  }
990
991  QualType ValType = pointerType->getPointeeType();
992  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
993      !ValType->isBlockPointerType()) {
994    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
995      << FirstArg->getType() << FirstArg->getSourceRange();
996    return ExprError();
997  }
998
999  switch (ValType.getObjCLifetime()) {
1000  case Qualifiers::OCL_None:
1001  case Qualifiers::OCL_ExplicitNone:
1002    // okay
1003    break;
1004
1005  case Qualifiers::OCL_Weak:
1006  case Qualifiers::OCL_Strong:
1007  case Qualifiers::OCL_Autoreleasing:
1008    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1009      << ValType << FirstArg->getSourceRange();
1010    return ExprError();
1011  }
1012
1013  // Strip any qualifiers off ValType.
1014  ValType = ValType.getUnqualifiedType();
1015
1016  // The majority of builtins return a value, but a few have special return
1017  // types, so allow them to override appropriately below.
1018  QualType ResultType = ValType;
1019
1020  // We need to figure out which concrete builtin this maps onto.  For example,
1021  // __sync_fetch_and_add with a 2 byte object turns into
1022  // __sync_fetch_and_add_2.
1023#define BUILTIN_ROW(x) \
1024  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
1025    Builtin::BI##x##_8, Builtin::BI##x##_16 }
1026
1027  static const unsigned BuiltinIndices[][5] = {
1028    BUILTIN_ROW(__sync_fetch_and_add),
1029    BUILTIN_ROW(__sync_fetch_and_sub),
1030    BUILTIN_ROW(__sync_fetch_and_or),
1031    BUILTIN_ROW(__sync_fetch_and_and),
1032    BUILTIN_ROW(__sync_fetch_and_xor),
1033
1034    BUILTIN_ROW(__sync_add_and_fetch),
1035    BUILTIN_ROW(__sync_sub_and_fetch),
1036    BUILTIN_ROW(__sync_and_and_fetch),
1037    BUILTIN_ROW(__sync_or_and_fetch),
1038    BUILTIN_ROW(__sync_xor_and_fetch),
1039
1040    BUILTIN_ROW(__sync_val_compare_and_swap),
1041    BUILTIN_ROW(__sync_bool_compare_and_swap),
1042    BUILTIN_ROW(__sync_lock_test_and_set),
1043    BUILTIN_ROW(__sync_lock_release),
1044    BUILTIN_ROW(__sync_swap)
1045  };
1046#undef BUILTIN_ROW
1047
1048  // Determine the index of the size.
1049  unsigned SizeIndex;
1050  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1051  case 1: SizeIndex = 0; break;
1052  case 2: SizeIndex = 1; break;
1053  case 4: SizeIndex = 2; break;
1054  case 8: SizeIndex = 3; break;
1055  case 16: SizeIndex = 4; break;
1056  default:
1057    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1058      << FirstArg->getType() << FirstArg->getSourceRange();
1059    return ExprError();
1060  }
1061
1062  // Each of these builtins has one pointer argument, followed by some number of
1063  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1064  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1065  // as the number of fixed args.
1066  unsigned BuiltinID = FDecl->getBuiltinID();
1067  unsigned BuiltinIndex, NumFixed = 1;
1068  switch (BuiltinID) {
1069  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1070  case Builtin::BI__sync_fetch_and_add:
1071  case Builtin::BI__sync_fetch_and_add_1:
1072  case Builtin::BI__sync_fetch_and_add_2:
1073  case Builtin::BI__sync_fetch_and_add_4:
1074  case Builtin::BI__sync_fetch_and_add_8:
1075  case Builtin::BI__sync_fetch_and_add_16:
1076    BuiltinIndex = 0;
1077    break;
1078
1079  case Builtin::BI__sync_fetch_and_sub:
1080  case Builtin::BI__sync_fetch_and_sub_1:
1081  case Builtin::BI__sync_fetch_and_sub_2:
1082  case Builtin::BI__sync_fetch_and_sub_4:
1083  case Builtin::BI__sync_fetch_and_sub_8:
1084  case Builtin::BI__sync_fetch_and_sub_16:
1085    BuiltinIndex = 1;
1086    break;
1087
1088  case Builtin::BI__sync_fetch_and_or:
1089  case Builtin::BI__sync_fetch_and_or_1:
1090  case Builtin::BI__sync_fetch_and_or_2:
1091  case Builtin::BI__sync_fetch_and_or_4:
1092  case Builtin::BI__sync_fetch_and_or_8:
1093  case Builtin::BI__sync_fetch_and_or_16:
1094    BuiltinIndex = 2;
1095    break;
1096
1097  case Builtin::BI__sync_fetch_and_and:
1098  case Builtin::BI__sync_fetch_and_and_1:
1099  case Builtin::BI__sync_fetch_and_and_2:
1100  case Builtin::BI__sync_fetch_and_and_4:
1101  case Builtin::BI__sync_fetch_and_and_8:
1102  case Builtin::BI__sync_fetch_and_and_16:
1103    BuiltinIndex = 3;
1104    break;
1105
1106  case Builtin::BI__sync_fetch_and_xor:
1107  case Builtin::BI__sync_fetch_and_xor_1:
1108  case Builtin::BI__sync_fetch_and_xor_2:
1109  case Builtin::BI__sync_fetch_and_xor_4:
1110  case Builtin::BI__sync_fetch_and_xor_8:
1111  case Builtin::BI__sync_fetch_and_xor_16:
1112    BuiltinIndex = 4;
1113    break;
1114
1115  case Builtin::BI__sync_add_and_fetch:
1116  case Builtin::BI__sync_add_and_fetch_1:
1117  case Builtin::BI__sync_add_and_fetch_2:
1118  case Builtin::BI__sync_add_and_fetch_4:
1119  case Builtin::BI__sync_add_and_fetch_8:
1120  case Builtin::BI__sync_add_and_fetch_16:
1121    BuiltinIndex = 5;
1122    break;
1123
1124  case Builtin::BI__sync_sub_and_fetch:
1125  case Builtin::BI__sync_sub_and_fetch_1:
1126  case Builtin::BI__sync_sub_and_fetch_2:
1127  case Builtin::BI__sync_sub_and_fetch_4:
1128  case Builtin::BI__sync_sub_and_fetch_8:
1129  case Builtin::BI__sync_sub_and_fetch_16:
1130    BuiltinIndex = 6;
1131    break;
1132
1133  case Builtin::BI__sync_and_and_fetch:
1134  case Builtin::BI__sync_and_and_fetch_1:
1135  case Builtin::BI__sync_and_and_fetch_2:
1136  case Builtin::BI__sync_and_and_fetch_4:
1137  case Builtin::BI__sync_and_and_fetch_8:
1138  case Builtin::BI__sync_and_and_fetch_16:
1139    BuiltinIndex = 7;
1140    break;
1141
1142  case Builtin::BI__sync_or_and_fetch:
1143  case Builtin::BI__sync_or_and_fetch_1:
1144  case Builtin::BI__sync_or_and_fetch_2:
1145  case Builtin::BI__sync_or_and_fetch_4:
1146  case Builtin::BI__sync_or_and_fetch_8:
1147  case Builtin::BI__sync_or_and_fetch_16:
1148    BuiltinIndex = 8;
1149    break;
1150
1151  case Builtin::BI__sync_xor_and_fetch:
1152  case Builtin::BI__sync_xor_and_fetch_1:
1153  case Builtin::BI__sync_xor_and_fetch_2:
1154  case Builtin::BI__sync_xor_and_fetch_4:
1155  case Builtin::BI__sync_xor_and_fetch_8:
1156  case Builtin::BI__sync_xor_and_fetch_16:
1157    BuiltinIndex = 9;
1158    break;
1159
1160  case Builtin::BI__sync_val_compare_and_swap:
1161  case Builtin::BI__sync_val_compare_and_swap_1:
1162  case Builtin::BI__sync_val_compare_and_swap_2:
1163  case Builtin::BI__sync_val_compare_and_swap_4:
1164  case Builtin::BI__sync_val_compare_and_swap_8:
1165  case Builtin::BI__sync_val_compare_and_swap_16:
1166    BuiltinIndex = 10;
1167    NumFixed = 2;
1168    break;
1169
1170  case Builtin::BI__sync_bool_compare_and_swap:
1171  case Builtin::BI__sync_bool_compare_and_swap_1:
1172  case Builtin::BI__sync_bool_compare_and_swap_2:
1173  case Builtin::BI__sync_bool_compare_and_swap_4:
1174  case Builtin::BI__sync_bool_compare_and_swap_8:
1175  case Builtin::BI__sync_bool_compare_and_swap_16:
1176    BuiltinIndex = 11;
1177    NumFixed = 2;
1178    ResultType = Context.BoolTy;
1179    break;
1180
1181  case Builtin::BI__sync_lock_test_and_set:
1182  case Builtin::BI__sync_lock_test_and_set_1:
1183  case Builtin::BI__sync_lock_test_and_set_2:
1184  case Builtin::BI__sync_lock_test_and_set_4:
1185  case Builtin::BI__sync_lock_test_and_set_8:
1186  case Builtin::BI__sync_lock_test_and_set_16:
1187    BuiltinIndex = 12;
1188    break;
1189
1190  case Builtin::BI__sync_lock_release:
1191  case Builtin::BI__sync_lock_release_1:
1192  case Builtin::BI__sync_lock_release_2:
1193  case Builtin::BI__sync_lock_release_4:
1194  case Builtin::BI__sync_lock_release_8:
1195  case Builtin::BI__sync_lock_release_16:
1196    BuiltinIndex = 13;
1197    NumFixed = 0;
1198    ResultType = Context.VoidTy;
1199    break;
1200
1201  case Builtin::BI__sync_swap:
1202  case Builtin::BI__sync_swap_1:
1203  case Builtin::BI__sync_swap_2:
1204  case Builtin::BI__sync_swap_4:
1205  case Builtin::BI__sync_swap_8:
1206  case Builtin::BI__sync_swap_16:
1207    BuiltinIndex = 14;
1208    break;
1209  }
1210
1211  // Now that we know how many fixed arguments we expect, first check that we
1212  // have at least that many.
1213  if (TheCall->getNumArgs() < 1+NumFixed) {
1214    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1215      << 0 << 1+NumFixed << TheCall->getNumArgs()
1216      << TheCall->getCallee()->getSourceRange();
1217    return ExprError();
1218  }
1219
1220  // Get the decl for the concrete builtin from this, we can tell what the
1221  // concrete integer type we should convert to is.
1222  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1223  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1224  FunctionDecl *NewBuiltinDecl;
1225  if (NewBuiltinID == BuiltinID)
1226    NewBuiltinDecl = FDecl;
1227  else {
1228    // Perform builtin lookup to avoid redeclaring it.
1229    DeclarationName DN(&Context.Idents.get(NewBuiltinName));
1230    LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
1231    LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
1232    assert(Res.getFoundDecl());
1233    NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
1234    if (NewBuiltinDecl == 0)
1235      return ExprError();
1236  }
1237
1238  // The first argument --- the pointer --- has a fixed type; we
1239  // deduce the types of the rest of the arguments accordingly.  Walk
1240  // the remaining arguments, converting them to the deduced value type.
1241  for (unsigned i = 0; i != NumFixed; ++i) {
1242    ExprResult Arg = TheCall->getArg(i+1);
1243
1244    // GCC does an implicit conversion to the pointer or integer ValType.  This
1245    // can fail in some cases (1i -> int**), check for this error case now.
1246    // Initialize the argument.
1247    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1248                                                   ValType, /*consume*/ false);
1249    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1250    if (Arg.isInvalid())
1251      return ExprError();
1252
1253    // Okay, we have something that *can* be converted to the right type.  Check
1254    // to see if there is a potentially weird extension going on here.  This can
1255    // happen when you do an atomic operation on something like an char* and
1256    // pass in 42.  The 42 gets converted to char.  This is even more strange
1257    // for things like 45.123 -> char, etc.
1258    // FIXME: Do this check.
1259    TheCall->setArg(i+1, Arg.take());
1260  }
1261
1262  ASTContext& Context = this->getASTContext();
1263
1264  // Create a new DeclRefExpr to refer to the new decl.
1265  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1266      Context,
1267      DRE->getQualifierLoc(),
1268      SourceLocation(),
1269      NewBuiltinDecl,
1270      /*enclosing*/ false,
1271      DRE->getLocation(),
1272      Context.BuiltinFnTy,
1273      DRE->getValueKind());
1274
1275  // Set the callee in the CallExpr.
1276  // FIXME: This loses syntactic information.
1277  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
1278  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
1279                                              CK_BuiltinFnToFnPtr);
1280  TheCall->setCallee(PromotedCall.take());
1281
1282  // Change the result type of the call to match the original value type. This
1283  // is arbitrary, but the codegen for these builtins ins design to handle it
1284  // gracefully.
1285  TheCall->setType(ResultType);
1286
1287  return TheCallResult;
1288}
1289
1290/// CheckObjCString - Checks that the argument to the builtin
1291/// CFString constructor is correct
1292/// Note: It might also make sense to do the UTF-16 conversion here (would
1293/// simplify the backend).
1294bool Sema::CheckObjCString(Expr *Arg) {
1295  Arg = Arg->IgnoreParenCasts();
1296  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1297
1298  if (!Literal || !Literal->isAscii()) {
1299    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1300      << Arg->getSourceRange();
1301    return true;
1302  }
1303
1304  if (Literal->containsNonAsciiOrNull()) {
1305    StringRef String = Literal->getString();
1306    unsigned NumBytes = String.size();
1307    SmallVector<UTF16, 128> ToBuf(NumBytes);
1308    const UTF8 *FromPtr = (const UTF8 *)String.data();
1309    UTF16 *ToPtr = &ToBuf[0];
1310
1311    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1312                                                 &ToPtr, ToPtr + NumBytes,
1313                                                 strictConversion);
1314    // Check for conversion failure.
1315    if (Result != conversionOK)
1316      Diag(Arg->getLocStart(),
1317           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1318  }
1319  return false;
1320}
1321
1322/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1323/// Emit an error and return true on failure, return false on success.
1324bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1325  Expr *Fn = TheCall->getCallee();
1326  if (TheCall->getNumArgs() > 2) {
1327    Diag(TheCall->getArg(2)->getLocStart(),
1328         diag::err_typecheck_call_too_many_args)
1329      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1330      << Fn->getSourceRange()
1331      << SourceRange(TheCall->getArg(2)->getLocStart(),
1332                     (*(TheCall->arg_end()-1))->getLocEnd());
1333    return true;
1334  }
1335
1336  if (TheCall->getNumArgs() < 2) {
1337    return Diag(TheCall->getLocEnd(),
1338      diag::err_typecheck_call_too_few_args_at_least)
1339      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1340  }
1341
1342  // Type-check the first argument normally.
1343  if (checkBuiltinArgument(*this, TheCall, 0))
1344    return true;
1345
1346  // Determine whether the current function is variadic or not.
1347  BlockScopeInfo *CurBlock = getCurBlock();
1348  bool isVariadic;
1349  if (CurBlock)
1350    isVariadic = CurBlock->TheDecl->isVariadic();
1351  else if (FunctionDecl *FD = getCurFunctionDecl())
1352    isVariadic = FD->isVariadic();
1353  else
1354    isVariadic = getCurMethodDecl()->isVariadic();
1355
1356  if (!isVariadic) {
1357    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1358    return true;
1359  }
1360
1361  // Verify that the second argument to the builtin is the last argument of the
1362  // current function or method.
1363  bool SecondArgIsLastNamedArgument = false;
1364  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1365
1366  // These are valid if SecondArgIsLastNamedArgument is false after the next
1367  // block.
1368  QualType Type;
1369  SourceLocation ParamLoc;
1370
1371  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1372    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1373      // FIXME: This isn't correct for methods (results in bogus warning).
1374      // Get the last formal in the current function.
1375      const ParmVarDecl *LastArg;
1376      if (CurBlock)
1377        LastArg = *(CurBlock->TheDecl->param_end()-1);
1378      else if (FunctionDecl *FD = getCurFunctionDecl())
1379        LastArg = *(FD->param_end()-1);
1380      else
1381        LastArg = *(getCurMethodDecl()->param_end()-1);
1382      SecondArgIsLastNamedArgument = PV == LastArg;
1383
1384      Type = PV->getType();
1385      ParamLoc = PV->getLocation();
1386    }
1387  }
1388
1389  if (!SecondArgIsLastNamedArgument)
1390    Diag(TheCall->getArg(1)->getLocStart(),
1391         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1392  else if (Type->isReferenceType()) {
1393    Diag(Arg->getLocStart(),
1394         diag::warn_va_start_of_reference_type_is_undefined);
1395    Diag(ParamLoc, diag::note_parameter_type) << Type;
1396  }
1397
1398  return false;
1399}
1400
1401/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1402/// friends.  This is declared to take (...), so we have to check everything.
1403bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1404  if (TheCall->getNumArgs() < 2)
1405    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1406      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1407  if (TheCall->getNumArgs() > 2)
1408    return Diag(TheCall->getArg(2)->getLocStart(),
1409                diag::err_typecheck_call_too_many_args)
1410      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1411      << SourceRange(TheCall->getArg(2)->getLocStart(),
1412                     (*(TheCall->arg_end()-1))->getLocEnd());
1413
1414  ExprResult OrigArg0 = TheCall->getArg(0);
1415  ExprResult OrigArg1 = TheCall->getArg(1);
1416
1417  // Do standard promotions between the two arguments, returning their common
1418  // type.
1419  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1420  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1421    return true;
1422
1423  // Make sure any conversions are pushed back into the call; this is
1424  // type safe since unordered compare builtins are declared as "_Bool
1425  // foo(...)".
1426  TheCall->setArg(0, OrigArg0.get());
1427  TheCall->setArg(1, OrigArg1.get());
1428
1429  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1430    return false;
1431
1432  // If the common type isn't a real floating type, then the arguments were
1433  // invalid for this operation.
1434  if (Res.isNull() || !Res->isRealFloatingType())
1435    return Diag(OrigArg0.get()->getLocStart(),
1436                diag::err_typecheck_call_invalid_ordered_compare)
1437      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1438      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1439
1440  return false;
1441}
1442
1443/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1444/// __builtin_isnan and friends.  This is declared to take (...), so we have
1445/// to check everything. We expect the last argument to be a floating point
1446/// value.
1447bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1448  if (TheCall->getNumArgs() < NumArgs)
1449    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1450      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1451  if (TheCall->getNumArgs() > NumArgs)
1452    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1453                diag::err_typecheck_call_too_many_args)
1454      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1455      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1456                     (*(TheCall->arg_end()-1))->getLocEnd());
1457
1458  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1459
1460  if (OrigArg->isTypeDependent())
1461    return false;
1462
1463  // This operation requires a non-_Complex floating-point number.
1464  if (!OrigArg->getType()->isRealFloatingType())
1465    return Diag(OrigArg->getLocStart(),
1466                diag::err_typecheck_call_invalid_unary_fp)
1467      << OrigArg->getType() << OrigArg->getSourceRange();
1468
1469  // If this is an implicit conversion from float -> double, remove it.
1470  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1471    Expr *CastArg = Cast->getSubExpr();
1472    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1473      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1474             "promotion from float to double is the only expected cast here");
1475      Cast->setSubExpr(0);
1476      TheCall->setArg(NumArgs-1, CastArg);
1477    }
1478  }
1479
1480  return false;
1481}
1482
1483/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1484// This is declared to take (...), so we have to check everything.
1485ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1486  if (TheCall->getNumArgs() < 2)
1487    return ExprError(Diag(TheCall->getLocEnd(),
1488                          diag::err_typecheck_call_too_few_args_at_least)
1489      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1490      << TheCall->getSourceRange());
1491
1492  // Determine which of the following types of shufflevector we're checking:
1493  // 1) unary, vector mask: (lhs, mask)
1494  // 2) binary, vector mask: (lhs, rhs, mask)
1495  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1496  QualType resType = TheCall->getArg(0)->getType();
1497  unsigned numElements = 0;
1498
1499  if (!TheCall->getArg(0)->isTypeDependent() &&
1500      !TheCall->getArg(1)->isTypeDependent()) {
1501    QualType LHSType = TheCall->getArg(0)->getType();
1502    QualType RHSType = TheCall->getArg(1)->getType();
1503
1504    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1505      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1506        << SourceRange(TheCall->getArg(0)->getLocStart(),
1507                       TheCall->getArg(1)->getLocEnd());
1508      return ExprError();
1509    }
1510
1511    numElements = LHSType->getAs<VectorType>()->getNumElements();
1512    unsigned numResElements = TheCall->getNumArgs() - 2;
1513
1514    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1515    // with mask.  If so, verify that RHS is an integer vector type with the
1516    // same number of elts as lhs.
1517    if (TheCall->getNumArgs() == 2) {
1518      if (!RHSType->hasIntegerRepresentation() ||
1519          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1520        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1521          << SourceRange(TheCall->getArg(1)->getLocStart(),
1522                         TheCall->getArg(1)->getLocEnd());
1523      numResElements = numElements;
1524    }
1525    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1526      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1527        << SourceRange(TheCall->getArg(0)->getLocStart(),
1528                       TheCall->getArg(1)->getLocEnd());
1529      return ExprError();
1530    } else if (numElements != numResElements) {
1531      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1532      resType = Context.getVectorType(eltType, numResElements,
1533                                      VectorType::GenericVector);
1534    }
1535  }
1536
1537  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1538    if (TheCall->getArg(i)->isTypeDependent() ||
1539        TheCall->getArg(i)->isValueDependent())
1540      continue;
1541
1542    llvm::APSInt Result(32);
1543    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1544      return ExprError(Diag(TheCall->getLocStart(),
1545                  diag::err_shufflevector_nonconstant_argument)
1546                << TheCall->getArg(i)->getSourceRange());
1547
1548    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1549      return ExprError(Diag(TheCall->getLocStart(),
1550                  diag::err_shufflevector_argument_too_large)
1551               << TheCall->getArg(i)->getSourceRange());
1552  }
1553
1554  SmallVector<Expr*, 32> exprs;
1555
1556  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1557    exprs.push_back(TheCall->getArg(i));
1558    TheCall->setArg(i, 0);
1559  }
1560
1561  return Owned(new (Context) ShuffleVectorExpr(Context, exprs, resType,
1562                                            TheCall->getCallee()->getLocStart(),
1563                                            TheCall->getRParenLoc()));
1564}
1565
1566/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1567// This is declared to take (const void*, ...) and can take two
1568// optional constant int args.
1569bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1570  unsigned NumArgs = TheCall->getNumArgs();
1571
1572  if (NumArgs > 3)
1573    return Diag(TheCall->getLocEnd(),
1574             diag::err_typecheck_call_too_many_args_at_most)
1575             << 0 /*function call*/ << 3 << NumArgs
1576             << TheCall->getSourceRange();
1577
1578  // Argument 0 is checked for us and the remaining arguments must be
1579  // constant integers.
1580  for (unsigned i = 1; i != NumArgs; ++i) {
1581    Expr *Arg = TheCall->getArg(i);
1582
1583    // We can't check the value of a dependent argument.
1584    if (Arg->isTypeDependent() || Arg->isValueDependent())
1585      continue;
1586
1587    llvm::APSInt Result;
1588    if (SemaBuiltinConstantArg(TheCall, i, Result))
1589      return true;
1590
1591    // FIXME: gcc issues a warning and rewrites these to 0. These
1592    // seems especially odd for the third argument since the default
1593    // is 3.
1594    if (i == 1) {
1595      if (Result.getLimitedValue() > 1)
1596        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1597             << "0" << "1" << Arg->getSourceRange();
1598    } else {
1599      if (Result.getLimitedValue() > 3)
1600        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1601            << "0" << "3" << Arg->getSourceRange();
1602    }
1603  }
1604
1605  return false;
1606}
1607
1608/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1609/// TheCall is a constant expression.
1610bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1611                                  llvm::APSInt &Result) {
1612  Expr *Arg = TheCall->getArg(ArgNum);
1613  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1614  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1615
1616  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1617
1618  if (!Arg->isIntegerConstantExpr(Result, Context))
1619    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1620                << FDecl->getDeclName() <<  Arg->getSourceRange();
1621
1622  return false;
1623}
1624
1625/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1626/// int type). This simply type checks that type is one of the defined
1627/// constants (0-3).
1628// For compatibility check 0-3, llvm only handles 0 and 2.
1629bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1630  llvm::APSInt Result;
1631
1632  // We can't check the value of a dependent argument.
1633  if (TheCall->getArg(1)->isTypeDependent() ||
1634      TheCall->getArg(1)->isValueDependent())
1635    return false;
1636
1637  // Check constant-ness first.
1638  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1639    return true;
1640
1641  Expr *Arg = TheCall->getArg(1);
1642  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1643    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1644             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1645  }
1646
1647  return false;
1648}
1649
1650/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1651/// This checks that val is a constant 1.
1652bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1653  Expr *Arg = TheCall->getArg(1);
1654  llvm::APSInt Result;
1655
1656  // TODO: This is less than ideal. Overload this to take a value.
1657  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1658    return true;
1659
1660  if (Result != 1)
1661    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1662             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1663
1664  return false;
1665}
1666
1667// Determine if an expression is a string literal or constant string.
1668// If this function returns false on the arguments to a function expecting a
1669// format string, we will usually need to emit a warning.
1670// True string literals are then checked by CheckFormatString.
1671Sema::StringLiteralCheckType
1672Sema::checkFormatStringExpr(const Expr *E, ArrayRef<const Expr *> Args,
1673                            bool HasVAListArg,
1674                            unsigned format_idx, unsigned firstDataArg,
1675                            FormatStringType Type, VariadicCallType CallType,
1676                            bool inFunctionCall) {
1677 tryAgain:
1678  if (E->isTypeDependent() || E->isValueDependent())
1679    return SLCT_NotALiteral;
1680
1681  E = E->IgnoreParenCasts();
1682
1683  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1684    // Technically -Wformat-nonliteral does not warn about this case.
1685    // The behavior of printf and friends in this case is implementation
1686    // dependent.  Ideally if the format string cannot be null then
1687    // it should have a 'nonnull' attribute in the function prototype.
1688    return SLCT_CheckedLiteral;
1689
1690  switch (E->getStmtClass()) {
1691  case Stmt::BinaryConditionalOperatorClass:
1692  case Stmt::ConditionalOperatorClass: {
1693    // The expression is a literal if both sub-expressions were, and it was
1694    // completely checked only if both sub-expressions were checked.
1695    const AbstractConditionalOperator *C =
1696        cast<AbstractConditionalOperator>(E);
1697    StringLiteralCheckType Left =
1698        checkFormatStringExpr(C->getTrueExpr(), Args,
1699                              HasVAListArg, format_idx, firstDataArg,
1700                              Type, CallType, inFunctionCall);
1701    if (Left == SLCT_NotALiteral)
1702      return SLCT_NotALiteral;
1703    StringLiteralCheckType Right =
1704        checkFormatStringExpr(C->getFalseExpr(), Args,
1705                              HasVAListArg, format_idx, firstDataArg,
1706                              Type, CallType, inFunctionCall);
1707    return Left < Right ? Left : Right;
1708  }
1709
1710  case Stmt::ImplicitCastExprClass: {
1711    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1712    goto tryAgain;
1713  }
1714
1715  case Stmt::OpaqueValueExprClass:
1716    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1717      E = src;
1718      goto tryAgain;
1719    }
1720    return SLCT_NotALiteral;
1721
1722  case Stmt::PredefinedExprClass:
1723    // While __func__, etc., are technically not string literals, they
1724    // cannot contain format specifiers and thus are not a security
1725    // liability.
1726    return SLCT_UncheckedLiteral;
1727
1728  case Stmt::DeclRefExprClass: {
1729    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1730
1731    // As an exception, do not flag errors for variables binding to
1732    // const string literals.
1733    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1734      bool isConstant = false;
1735      QualType T = DR->getType();
1736
1737      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1738        isConstant = AT->getElementType().isConstant(Context);
1739      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1740        isConstant = T.isConstant(Context) &&
1741                     PT->getPointeeType().isConstant(Context);
1742      } else if (T->isObjCObjectPointerType()) {
1743        // In ObjC, there is usually no "const ObjectPointer" type,
1744        // so don't check if the pointee type is constant.
1745        isConstant = T.isConstant(Context);
1746      }
1747
1748      if (isConstant) {
1749        if (const Expr *Init = VD->getAnyInitializer()) {
1750          // Look through initializers like const char c[] = { "foo" }
1751          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
1752            if (InitList->isStringLiteralInit())
1753              Init = InitList->getInit(0)->IgnoreParenImpCasts();
1754          }
1755          return checkFormatStringExpr(Init, Args,
1756                                       HasVAListArg, format_idx,
1757                                       firstDataArg, Type, CallType,
1758                                       /*inFunctionCall*/false);
1759        }
1760      }
1761
1762      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1763      // special check to see if the format string is a function parameter
1764      // of the function calling the printf function.  If the function
1765      // has an attribute indicating it is a printf-like function, then we
1766      // should suppress warnings concerning non-literals being used in a call
1767      // to a vprintf function.  For example:
1768      //
1769      // void
1770      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1771      //      va_list ap;
1772      //      va_start(ap, fmt);
1773      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1774      //      ...
1775      //
1776      if (HasVAListArg) {
1777        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1778          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1779            int PVIndex = PV->getFunctionScopeIndex() + 1;
1780            for (specific_attr_iterator<FormatAttr>
1781                 i = ND->specific_attr_begin<FormatAttr>(),
1782                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1783              FormatAttr *PVFormat = *i;
1784              // adjust for implicit parameter
1785              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1786                if (MD->isInstance())
1787                  ++PVIndex;
1788              // We also check if the formats are compatible.
1789              // We can't pass a 'scanf' string to a 'printf' function.
1790              if (PVIndex == PVFormat->getFormatIdx() &&
1791                  Type == GetFormatStringType(PVFormat))
1792                return SLCT_UncheckedLiteral;
1793            }
1794          }
1795        }
1796      }
1797    }
1798
1799    return SLCT_NotALiteral;
1800  }
1801
1802  case Stmt::CallExprClass:
1803  case Stmt::CXXMemberCallExprClass: {
1804    const CallExpr *CE = cast<CallExpr>(E);
1805    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1806      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1807        unsigned ArgIndex = FA->getFormatIdx();
1808        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1809          if (MD->isInstance())
1810            --ArgIndex;
1811        const Expr *Arg = CE->getArg(ArgIndex - 1);
1812
1813        return checkFormatStringExpr(Arg, Args,
1814                                     HasVAListArg, format_idx, firstDataArg,
1815                                     Type, CallType, inFunctionCall);
1816      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
1817        unsigned BuiltinID = FD->getBuiltinID();
1818        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
1819            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
1820          const Expr *Arg = CE->getArg(0);
1821          return checkFormatStringExpr(Arg, Args,
1822                                       HasVAListArg, format_idx,
1823                                       firstDataArg, Type, CallType,
1824                                       inFunctionCall);
1825        }
1826      }
1827    }
1828
1829    return SLCT_NotALiteral;
1830  }
1831  case Stmt::ObjCStringLiteralClass:
1832  case Stmt::StringLiteralClass: {
1833    const StringLiteral *StrE = NULL;
1834
1835    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1836      StrE = ObjCFExpr->getString();
1837    else
1838      StrE = cast<StringLiteral>(E);
1839
1840    if (StrE) {
1841      CheckFormatString(StrE, E, Args, HasVAListArg, format_idx,
1842                        firstDataArg, Type, inFunctionCall, CallType);
1843      return SLCT_CheckedLiteral;
1844    }
1845
1846    return SLCT_NotALiteral;
1847  }
1848
1849  default:
1850    return SLCT_NotALiteral;
1851  }
1852}
1853
1854void
1855Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1856                            const Expr * const *ExprArgs,
1857                            SourceLocation CallSiteLoc) {
1858  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1859                                  e = NonNull->args_end();
1860       i != e; ++i) {
1861    const Expr *ArgExpr = ExprArgs[*i];
1862
1863    // As a special case, transparent unions initialized with zero are
1864    // considered null for the purposes of the nonnull attribute.
1865    if (const RecordType *UT = ArgExpr->getType()->getAsUnionType()) {
1866      if (UT->getDecl()->hasAttr<TransparentUnionAttr>())
1867        if (const CompoundLiteralExpr *CLE =
1868            dyn_cast<CompoundLiteralExpr>(ArgExpr))
1869          if (const InitListExpr *ILE =
1870              dyn_cast<InitListExpr>(CLE->getInitializer()))
1871            ArgExpr = ILE->getInit(0);
1872    }
1873
1874    bool Result;
1875    if (ArgExpr->EvaluateAsBooleanCondition(Result, Context) && !Result)
1876      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1877  }
1878}
1879
1880Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1881  return llvm::StringSwitch<FormatStringType>(Format->getType())
1882  .Case("scanf", FST_Scanf)
1883  .Cases("printf", "printf0", FST_Printf)
1884  .Cases("NSString", "CFString", FST_NSString)
1885  .Case("strftime", FST_Strftime)
1886  .Case("strfmon", FST_Strfmon)
1887  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1888  .Default(FST_Unknown);
1889}
1890
1891/// CheckFormatArguments - Check calls to printf and scanf (and similar
1892/// functions) for correct use of format strings.
1893/// Returns true if a format string has been fully checked.
1894bool Sema::CheckFormatArguments(const FormatAttr *Format,
1895                                ArrayRef<const Expr *> Args,
1896                                bool IsCXXMember,
1897                                VariadicCallType CallType,
1898                                SourceLocation Loc, SourceRange Range) {
1899  FormatStringInfo FSI;
1900  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
1901    return CheckFormatArguments(Args, FSI.HasVAListArg, FSI.FormatIdx,
1902                                FSI.FirstDataArg, GetFormatStringType(Format),
1903                                CallType, Loc, Range);
1904  return false;
1905}
1906
1907bool Sema::CheckFormatArguments(ArrayRef<const Expr *> Args,
1908                                bool HasVAListArg, unsigned format_idx,
1909                                unsigned firstDataArg, FormatStringType Type,
1910                                VariadicCallType CallType,
1911                                SourceLocation Loc, SourceRange Range) {
1912  // CHECK: printf/scanf-like function is called with no format string.
1913  if (format_idx >= Args.size()) {
1914    Diag(Loc, diag::warn_missing_format_string) << Range;
1915    return false;
1916  }
1917
1918  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1919
1920  // CHECK: format string is not a string literal.
1921  //
1922  // Dynamically generated format strings are difficult to
1923  // automatically vet at compile time.  Requiring that format strings
1924  // are string literals: (1) permits the checking of format strings by
1925  // the compiler and thereby (2) can practically remove the source of
1926  // many format string exploits.
1927
1928  // Format string can be either ObjC string (e.g. @"%d") or
1929  // C string (e.g. "%d")
1930  // ObjC string uses the same format specifiers as C string, so we can use
1931  // the same format string checking logic for both ObjC and C strings.
1932  StringLiteralCheckType CT =
1933      checkFormatStringExpr(OrigFormatExpr, Args, HasVAListArg,
1934                            format_idx, firstDataArg, Type, CallType);
1935  if (CT != SLCT_NotALiteral)
1936    // Literal format string found, check done!
1937    return CT == SLCT_CheckedLiteral;
1938
1939  // Strftime is particular as it always uses a single 'time' argument,
1940  // so it is safe to pass a non-literal string.
1941  if (Type == FST_Strftime)
1942    return false;
1943
1944  // Do not emit diag when the string param is a macro expansion and the
1945  // format is either NSString or CFString. This is a hack to prevent
1946  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1947  // which are usually used in place of NS and CF string literals.
1948  if (Type == FST_NSString &&
1949      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
1950    return false;
1951
1952  // If there are no arguments specified, warn with -Wformat-security, otherwise
1953  // warn only with -Wformat-nonliteral.
1954  if (Args.size() == format_idx+1)
1955    Diag(Args[format_idx]->getLocStart(),
1956         diag::warn_format_nonliteral_noargs)
1957      << OrigFormatExpr->getSourceRange();
1958  else
1959    Diag(Args[format_idx]->getLocStart(),
1960         diag::warn_format_nonliteral)
1961           << OrigFormatExpr->getSourceRange();
1962  return false;
1963}
1964
1965namespace {
1966class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1967protected:
1968  Sema &S;
1969  const StringLiteral *FExpr;
1970  const Expr *OrigFormatExpr;
1971  const unsigned FirstDataArg;
1972  const unsigned NumDataArgs;
1973  const char *Beg; // Start of format string.
1974  const bool HasVAListArg;
1975  ArrayRef<const Expr *> Args;
1976  unsigned FormatIdx;
1977  llvm::BitVector CoveredArgs;
1978  bool usesPositionalArgs;
1979  bool atFirstArg;
1980  bool inFunctionCall;
1981  Sema::VariadicCallType CallType;
1982public:
1983  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1984                     const Expr *origFormatExpr, unsigned firstDataArg,
1985                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
1986                     ArrayRef<const Expr *> Args,
1987                     unsigned formatIdx, bool inFunctionCall,
1988                     Sema::VariadicCallType callType)
1989    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1990      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
1991      Beg(beg), HasVAListArg(hasVAListArg),
1992      Args(Args), FormatIdx(formatIdx),
1993      usesPositionalArgs(false), atFirstArg(true),
1994      inFunctionCall(inFunctionCall), CallType(callType) {
1995        CoveredArgs.resize(numDataArgs);
1996        CoveredArgs.reset();
1997      }
1998
1999  void DoneProcessing();
2000
2001  void HandleIncompleteSpecifier(const char *startSpecifier,
2002                                 unsigned specifierLen);
2003
2004  void HandleInvalidLengthModifier(
2005      const analyze_format_string::FormatSpecifier &FS,
2006      const analyze_format_string::ConversionSpecifier &CS,
2007      const char *startSpecifier, unsigned specifierLen, unsigned DiagID);
2008
2009  void HandleNonStandardLengthModifier(
2010      const analyze_format_string::FormatSpecifier &FS,
2011      const char *startSpecifier, unsigned specifierLen);
2012
2013  void HandleNonStandardConversionSpecifier(
2014      const analyze_format_string::ConversionSpecifier &CS,
2015      const char *startSpecifier, unsigned specifierLen);
2016
2017  virtual void HandlePosition(const char *startPos, unsigned posLen);
2018
2019  virtual void HandleInvalidPosition(const char *startSpecifier,
2020                                     unsigned specifierLen,
2021                                     analyze_format_string::PositionContext p);
2022
2023  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
2024
2025  void HandleNullChar(const char *nullCharacter);
2026
2027  template <typename Range>
2028  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
2029                                   const Expr *ArgumentExpr,
2030                                   PartialDiagnostic PDiag,
2031                                   SourceLocation StringLoc,
2032                                   bool IsStringLocation, Range StringRange,
2033                                   ArrayRef<FixItHint> Fixit = None);
2034
2035protected:
2036  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
2037                                        const char *startSpec,
2038                                        unsigned specifierLen,
2039                                        const char *csStart, unsigned csLen);
2040
2041  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
2042                                         const char *startSpec,
2043                                         unsigned specifierLen);
2044
2045  SourceRange getFormatStringRange();
2046  CharSourceRange getSpecifierRange(const char *startSpecifier,
2047                                    unsigned specifierLen);
2048  SourceLocation getLocationOfByte(const char *x);
2049
2050  const Expr *getDataArg(unsigned i) const;
2051
2052  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
2053                    const analyze_format_string::ConversionSpecifier &CS,
2054                    const char *startSpecifier, unsigned specifierLen,
2055                    unsigned argIndex);
2056
2057  template <typename Range>
2058  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
2059                            bool IsStringLocation, Range StringRange,
2060                            ArrayRef<FixItHint> Fixit = None);
2061
2062  void CheckPositionalAndNonpositionalArgs(
2063      const analyze_format_string::FormatSpecifier *FS);
2064};
2065}
2066
2067SourceRange CheckFormatHandler::getFormatStringRange() {
2068  return OrigFormatExpr->getSourceRange();
2069}
2070
2071CharSourceRange CheckFormatHandler::
2072getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2073  SourceLocation Start = getLocationOfByte(startSpecifier);
2074  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2075
2076  // Advance the end SourceLocation by one due to half-open ranges.
2077  End = End.getLocWithOffset(1);
2078
2079  return CharSourceRange::getCharRange(Start, End);
2080}
2081
2082SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2083  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2084}
2085
2086void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2087                                                   unsigned specifierLen){
2088  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2089                       getLocationOfByte(startSpecifier),
2090                       /*IsStringLocation*/true,
2091                       getSpecifierRange(startSpecifier, specifierLen));
2092}
2093
2094void CheckFormatHandler::HandleInvalidLengthModifier(
2095    const analyze_format_string::FormatSpecifier &FS,
2096    const analyze_format_string::ConversionSpecifier &CS,
2097    const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
2098  using namespace analyze_format_string;
2099
2100  const LengthModifier &LM = FS.getLengthModifier();
2101  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2102
2103  // See if we know how to fix this length modifier.
2104  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2105  if (FixedLM) {
2106    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2107                         getLocationOfByte(LM.getStart()),
2108                         /*IsStringLocation*/true,
2109                         getSpecifierRange(startSpecifier, specifierLen));
2110
2111    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2112      << FixedLM->toString()
2113      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2114
2115  } else {
2116    FixItHint Hint;
2117    if (DiagID == diag::warn_format_nonsensical_length)
2118      Hint = FixItHint::CreateRemoval(LMRange);
2119
2120    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
2121                         getLocationOfByte(LM.getStart()),
2122                         /*IsStringLocation*/true,
2123                         getSpecifierRange(startSpecifier, specifierLen),
2124                         Hint);
2125  }
2126}
2127
2128void CheckFormatHandler::HandleNonStandardLengthModifier(
2129    const analyze_format_string::FormatSpecifier &FS,
2130    const char *startSpecifier, unsigned specifierLen) {
2131  using namespace analyze_format_string;
2132
2133  const LengthModifier &LM = FS.getLengthModifier();
2134  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2135
2136  // See if we know how to fix this length modifier.
2137  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
2138  if (FixedLM) {
2139    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2140                           << LM.toString() << 0,
2141                         getLocationOfByte(LM.getStart()),
2142                         /*IsStringLocation*/true,
2143                         getSpecifierRange(startSpecifier, specifierLen));
2144
2145    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
2146      << FixedLM->toString()
2147      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
2148
2149  } else {
2150    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2151                           << LM.toString() << 0,
2152                         getLocationOfByte(LM.getStart()),
2153                         /*IsStringLocation*/true,
2154                         getSpecifierRange(startSpecifier, specifierLen));
2155  }
2156}
2157
2158void CheckFormatHandler::HandleNonStandardConversionSpecifier(
2159    const analyze_format_string::ConversionSpecifier &CS,
2160    const char *startSpecifier, unsigned specifierLen) {
2161  using namespace analyze_format_string;
2162
2163  // See if we know how to fix this conversion specifier.
2164  Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
2165  if (FixedCS) {
2166    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2167                          << CS.toString() << /*conversion specifier*/1,
2168                         getLocationOfByte(CS.getStart()),
2169                         /*IsStringLocation*/true,
2170                         getSpecifierRange(startSpecifier, specifierLen));
2171
2172    CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
2173    S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
2174      << FixedCS->toString()
2175      << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
2176  } else {
2177    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
2178                          << CS.toString() << /*conversion specifier*/1,
2179                         getLocationOfByte(CS.getStart()),
2180                         /*IsStringLocation*/true,
2181                         getSpecifierRange(startSpecifier, specifierLen));
2182  }
2183}
2184
2185void CheckFormatHandler::HandlePosition(const char *startPos,
2186                                        unsigned posLen) {
2187  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
2188                               getLocationOfByte(startPos),
2189                               /*IsStringLocation*/true,
2190                               getSpecifierRange(startPos, posLen));
2191}
2192
2193void
2194CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
2195                                     analyze_format_string::PositionContext p) {
2196  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
2197                         << (unsigned) p,
2198                       getLocationOfByte(startPos), /*IsStringLocation*/true,
2199                       getSpecifierRange(startPos, posLen));
2200}
2201
2202void CheckFormatHandler::HandleZeroPosition(const char *startPos,
2203                                            unsigned posLen) {
2204  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
2205                               getLocationOfByte(startPos),
2206                               /*IsStringLocation*/true,
2207                               getSpecifierRange(startPos, posLen));
2208}
2209
2210void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
2211  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
2212    // The presence of a null character is likely an error.
2213    EmitFormatDiagnostic(
2214      S.PDiag(diag::warn_printf_format_string_contains_null_char),
2215      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
2216      getFormatStringRange());
2217  }
2218}
2219
2220// Note that this may return NULL if there was an error parsing or building
2221// one of the argument expressions.
2222const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
2223  return Args[FirstDataArg + i];
2224}
2225
2226void CheckFormatHandler::DoneProcessing() {
2227    // Does the number of data arguments exceed the number of
2228    // format conversions in the format string?
2229  if (!HasVAListArg) {
2230      // Find any arguments that weren't covered.
2231    CoveredArgs.flip();
2232    signed notCoveredArg = CoveredArgs.find_first();
2233    if (notCoveredArg >= 0) {
2234      assert((unsigned)notCoveredArg < NumDataArgs);
2235      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
2236        SourceLocation Loc = E->getLocStart();
2237        if (!S.getSourceManager().isInSystemMacro(Loc)) {
2238          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
2239                               Loc, /*IsStringLocation*/false,
2240                               getFormatStringRange());
2241        }
2242      }
2243    }
2244  }
2245}
2246
2247bool
2248CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
2249                                                     SourceLocation Loc,
2250                                                     const char *startSpec,
2251                                                     unsigned specifierLen,
2252                                                     const char *csStart,
2253                                                     unsigned csLen) {
2254
2255  bool keepGoing = true;
2256  if (argIndex < NumDataArgs) {
2257    // Consider the argument coverered, even though the specifier doesn't
2258    // make sense.
2259    CoveredArgs.set(argIndex);
2260  }
2261  else {
2262    // If argIndex exceeds the number of data arguments we
2263    // don't issue a warning because that is just a cascade of warnings (and
2264    // they may have intended '%%' anyway). We don't want to continue processing
2265    // the format string after this point, however, as we will like just get
2266    // gibberish when trying to match arguments.
2267    keepGoing = false;
2268  }
2269
2270  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2271                         << StringRef(csStart, csLen),
2272                       Loc, /*IsStringLocation*/true,
2273                       getSpecifierRange(startSpec, specifierLen));
2274
2275  return keepGoing;
2276}
2277
2278void
2279CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2280                                                      const char *startSpec,
2281                                                      unsigned specifierLen) {
2282  EmitFormatDiagnostic(
2283    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2284    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2285}
2286
2287bool
2288CheckFormatHandler::CheckNumArgs(
2289  const analyze_format_string::FormatSpecifier &FS,
2290  const analyze_format_string::ConversionSpecifier &CS,
2291  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2292
2293  if (argIndex >= NumDataArgs) {
2294    PartialDiagnostic PDiag = FS.usesPositionalArg()
2295      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2296           << (argIndex+1) << NumDataArgs)
2297      : S.PDiag(diag::warn_printf_insufficient_data_args);
2298    EmitFormatDiagnostic(
2299      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2300      getSpecifierRange(startSpecifier, specifierLen));
2301    return false;
2302  }
2303  return true;
2304}
2305
2306template<typename Range>
2307void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2308                                              SourceLocation Loc,
2309                                              bool IsStringLocation,
2310                                              Range StringRange,
2311                                              ArrayRef<FixItHint> FixIt) {
2312  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2313                       Loc, IsStringLocation, StringRange, FixIt);
2314}
2315
2316/// \brief If the format string is not within the funcion call, emit a note
2317/// so that the function call and string are in diagnostic messages.
2318///
2319/// \param InFunctionCall if true, the format string is within the function
2320/// call and only one diagnostic message will be produced.  Otherwise, an
2321/// extra note will be emitted pointing to location of the format string.
2322///
2323/// \param ArgumentExpr the expression that is passed as the format string
2324/// argument in the function call.  Used for getting locations when two
2325/// diagnostics are emitted.
2326///
2327/// \param PDiag the callee should already have provided any strings for the
2328/// diagnostic message.  This function only adds locations and fixits
2329/// to diagnostics.
2330///
2331/// \param Loc primary location for diagnostic.  If two diagnostics are
2332/// required, one will be at Loc and a new SourceLocation will be created for
2333/// the other one.
2334///
2335/// \param IsStringLocation if true, Loc points to the format string should be
2336/// used for the note.  Otherwise, Loc points to the argument list and will
2337/// be used with PDiag.
2338///
2339/// \param StringRange some or all of the string to highlight.  This is
2340/// templated so it can accept either a CharSourceRange or a SourceRange.
2341///
2342/// \param FixIt optional fix it hint for the format string.
2343template<typename Range>
2344void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2345                                              const Expr *ArgumentExpr,
2346                                              PartialDiagnostic PDiag,
2347                                              SourceLocation Loc,
2348                                              bool IsStringLocation,
2349                                              Range StringRange,
2350                                              ArrayRef<FixItHint> FixIt) {
2351  if (InFunctionCall) {
2352    const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
2353    D << StringRange;
2354    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2355         I != E; ++I) {
2356      D << *I;
2357    }
2358  } else {
2359    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2360      << ArgumentExpr->getSourceRange();
2361
2362    const Sema::SemaDiagnosticBuilder &Note =
2363      S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2364             diag::note_format_string_defined);
2365
2366    Note << StringRange;
2367    for (ArrayRef<FixItHint>::iterator I = FixIt.begin(), E = FixIt.end();
2368         I != E; ++I) {
2369      Note << *I;
2370    }
2371  }
2372}
2373
2374//===--- CHECK: Printf format string checking ------------------------------===//
2375
2376namespace {
2377class CheckPrintfHandler : public CheckFormatHandler {
2378  bool ObjCContext;
2379public:
2380  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2381                     const Expr *origFormatExpr, unsigned firstDataArg,
2382                     unsigned numDataArgs, bool isObjC,
2383                     const char *beg, bool hasVAListArg,
2384                     ArrayRef<const Expr *> Args,
2385                     unsigned formatIdx, bool inFunctionCall,
2386                     Sema::VariadicCallType CallType)
2387  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2388                       numDataArgs, beg, hasVAListArg, Args,
2389                       formatIdx, inFunctionCall, CallType), ObjCContext(isObjC)
2390  {}
2391
2392
2393  bool HandleInvalidPrintfConversionSpecifier(
2394                                      const analyze_printf::PrintfSpecifier &FS,
2395                                      const char *startSpecifier,
2396                                      unsigned specifierLen);
2397
2398  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2399                             const char *startSpecifier,
2400                             unsigned specifierLen);
2401  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2402                       const char *StartSpecifier,
2403                       unsigned SpecifierLen,
2404                       const Expr *E);
2405
2406  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2407                    const char *startSpecifier, unsigned specifierLen);
2408  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2409                           const analyze_printf::OptionalAmount &Amt,
2410                           unsigned type,
2411                           const char *startSpecifier, unsigned specifierLen);
2412  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2413                  const analyze_printf::OptionalFlag &flag,
2414                  const char *startSpecifier, unsigned specifierLen);
2415  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2416                         const analyze_printf::OptionalFlag &ignoredFlag,
2417                         const analyze_printf::OptionalFlag &flag,
2418                         const char *startSpecifier, unsigned specifierLen);
2419  bool checkForCStrMembers(const analyze_printf::ArgType &AT,
2420                           const Expr *E, const CharSourceRange &CSR);
2421
2422};
2423}
2424
2425bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2426                                      const analyze_printf::PrintfSpecifier &FS,
2427                                      const char *startSpecifier,
2428                                      unsigned specifierLen) {
2429  const analyze_printf::PrintfConversionSpecifier &CS =
2430    FS.getConversionSpecifier();
2431
2432  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2433                                          getLocationOfByte(CS.getStart()),
2434                                          startSpecifier, specifierLen,
2435                                          CS.getStart(), CS.getLength());
2436}
2437
2438bool CheckPrintfHandler::HandleAmount(
2439                               const analyze_format_string::OptionalAmount &Amt,
2440                               unsigned k, const char *startSpecifier,
2441                               unsigned specifierLen) {
2442
2443  if (Amt.hasDataArgument()) {
2444    if (!HasVAListArg) {
2445      unsigned argIndex = Amt.getArgIndex();
2446      if (argIndex >= NumDataArgs) {
2447        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2448                               << k,
2449                             getLocationOfByte(Amt.getStart()),
2450                             /*IsStringLocation*/true,
2451                             getSpecifierRange(startSpecifier, specifierLen));
2452        // Don't do any more checking.  We will just emit
2453        // spurious errors.
2454        return false;
2455      }
2456
2457      // Type check the data argument.  It should be an 'int'.
2458      // Although not in conformance with C99, we also allow the argument to be
2459      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2460      // doesn't emit a warning for that case.
2461      CoveredArgs.set(argIndex);
2462      const Expr *Arg = getDataArg(argIndex);
2463      if (!Arg)
2464        return false;
2465
2466      QualType T = Arg->getType();
2467
2468      const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
2469      assert(AT.isValid());
2470
2471      if (!AT.matchesType(S.Context, T)) {
2472        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2473                               << k << AT.getRepresentativeTypeName(S.Context)
2474                               << T << Arg->getSourceRange(),
2475                             getLocationOfByte(Amt.getStart()),
2476                             /*IsStringLocation*/true,
2477                             getSpecifierRange(startSpecifier, specifierLen));
2478        // Don't do any more checking.  We will just emit
2479        // spurious errors.
2480        return false;
2481      }
2482    }
2483  }
2484  return true;
2485}
2486
2487void CheckPrintfHandler::HandleInvalidAmount(
2488                                      const analyze_printf::PrintfSpecifier &FS,
2489                                      const analyze_printf::OptionalAmount &Amt,
2490                                      unsigned type,
2491                                      const char *startSpecifier,
2492                                      unsigned specifierLen) {
2493  const analyze_printf::PrintfConversionSpecifier &CS =
2494    FS.getConversionSpecifier();
2495
2496  FixItHint fixit =
2497    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2498      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2499                                 Amt.getConstantLength()))
2500      : FixItHint();
2501
2502  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2503                         << type << CS.toString(),
2504                       getLocationOfByte(Amt.getStart()),
2505                       /*IsStringLocation*/true,
2506                       getSpecifierRange(startSpecifier, specifierLen),
2507                       fixit);
2508}
2509
2510void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2511                                    const analyze_printf::OptionalFlag &flag,
2512                                    const char *startSpecifier,
2513                                    unsigned specifierLen) {
2514  // Warn about pointless flag with a fixit removal.
2515  const analyze_printf::PrintfConversionSpecifier &CS =
2516    FS.getConversionSpecifier();
2517  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2518                         << flag.toString() << CS.toString(),
2519                       getLocationOfByte(flag.getPosition()),
2520                       /*IsStringLocation*/true,
2521                       getSpecifierRange(startSpecifier, specifierLen),
2522                       FixItHint::CreateRemoval(
2523                         getSpecifierRange(flag.getPosition(), 1)));
2524}
2525
2526void CheckPrintfHandler::HandleIgnoredFlag(
2527                                const analyze_printf::PrintfSpecifier &FS,
2528                                const analyze_printf::OptionalFlag &ignoredFlag,
2529                                const analyze_printf::OptionalFlag &flag,
2530                                const char *startSpecifier,
2531                                unsigned specifierLen) {
2532  // Warn about ignored flag with a fixit removal.
2533  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2534                         << ignoredFlag.toString() << flag.toString(),
2535                       getLocationOfByte(ignoredFlag.getPosition()),
2536                       /*IsStringLocation*/true,
2537                       getSpecifierRange(startSpecifier, specifierLen),
2538                       FixItHint::CreateRemoval(
2539                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2540}
2541
2542// Determines if the specified is a C++ class or struct containing
2543// a member with the specified name and kind (e.g. a CXXMethodDecl named
2544// "c_str()").
2545template<typename MemberKind>
2546static llvm::SmallPtrSet<MemberKind*, 1>
2547CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
2548  const RecordType *RT = Ty->getAs<RecordType>();
2549  llvm::SmallPtrSet<MemberKind*, 1> Results;
2550
2551  if (!RT)
2552    return Results;
2553  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
2554  if (!RD)
2555    return Results;
2556
2557  LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
2558                 Sema::LookupMemberName);
2559
2560  // We just need to include all members of the right kind turned up by the
2561  // filter, at this point.
2562  if (S.LookupQualifiedName(R, RT->getDecl()))
2563    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
2564      NamedDecl *decl = (*I)->getUnderlyingDecl();
2565      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
2566        Results.insert(FK);
2567    }
2568  return Results;
2569}
2570
2571// Check if a (w)string was passed when a (w)char* was needed, and offer a
2572// better diagnostic if so. AT is assumed to be valid.
2573// Returns true when a c_str() conversion method is found.
2574bool CheckPrintfHandler::checkForCStrMembers(
2575    const analyze_printf::ArgType &AT, const Expr *E,
2576    const CharSourceRange &CSR) {
2577  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
2578
2579  MethodSet Results =
2580      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
2581
2582  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
2583       MI != ME; ++MI) {
2584    const CXXMethodDecl *Method = *MI;
2585    if (Method->getNumParams() == 0 &&
2586          AT.matchesType(S.Context, Method->getResultType())) {
2587      // FIXME: Suggest parens if the expression needs them.
2588      SourceLocation EndLoc =
2589          S.getPreprocessor().getLocForEndOfToken(E->getLocEnd());
2590      S.Diag(E->getLocStart(), diag::note_printf_c_str)
2591          << "c_str()"
2592          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
2593      return true;
2594    }
2595  }
2596
2597  return false;
2598}
2599
2600bool
2601CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2602                                            &FS,
2603                                          const char *startSpecifier,
2604                                          unsigned specifierLen) {
2605
2606  using namespace analyze_format_string;
2607  using namespace analyze_printf;
2608  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2609
2610  if (FS.consumesDataArgument()) {
2611    if (atFirstArg) {
2612        atFirstArg = false;
2613        usesPositionalArgs = FS.usesPositionalArg();
2614    }
2615    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2616      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2617                                        startSpecifier, specifierLen);
2618      return false;
2619    }
2620  }
2621
2622  // First check if the field width, precision, and conversion specifier
2623  // have matching data arguments.
2624  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2625                    startSpecifier, specifierLen)) {
2626    return false;
2627  }
2628
2629  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2630                    startSpecifier, specifierLen)) {
2631    return false;
2632  }
2633
2634  if (!CS.consumesDataArgument()) {
2635    // FIXME: Technically specifying a precision or field width here
2636    // makes no sense.  Worth issuing a warning at some point.
2637    return true;
2638  }
2639
2640  // Consume the argument.
2641  unsigned argIndex = FS.getArgIndex();
2642  if (argIndex < NumDataArgs) {
2643    // The check to see if the argIndex is valid will come later.
2644    // We set the bit here because we may exit early from this
2645    // function if we encounter some other error.
2646    CoveredArgs.set(argIndex);
2647  }
2648
2649  // Check for using an Objective-C specific conversion specifier
2650  // in a non-ObjC literal.
2651  if (!ObjCContext && CS.isObjCArg()) {
2652    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2653                                                  specifierLen);
2654  }
2655
2656  // Check for invalid use of field width
2657  if (!FS.hasValidFieldWidth()) {
2658    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2659        startSpecifier, specifierLen);
2660  }
2661
2662  // Check for invalid use of precision
2663  if (!FS.hasValidPrecision()) {
2664    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2665        startSpecifier, specifierLen);
2666  }
2667
2668  // Check each flag does not conflict with any other component.
2669  if (!FS.hasValidThousandsGroupingPrefix())
2670    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2671  if (!FS.hasValidLeadingZeros())
2672    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2673  if (!FS.hasValidPlusPrefix())
2674    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2675  if (!FS.hasValidSpacePrefix())
2676    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2677  if (!FS.hasValidAlternativeForm())
2678    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2679  if (!FS.hasValidLeftJustified())
2680    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2681
2682  // Check that flags are not ignored by another flag
2683  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2684    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2685        startSpecifier, specifierLen);
2686  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2687    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2688            startSpecifier, specifierLen);
2689
2690  // Check the length modifier is valid with the given conversion specifier.
2691  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
2692    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2693                                diag::warn_format_nonsensical_length);
2694  else if (!FS.hasStandardLengthModifier())
2695    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
2696  else if (!FS.hasStandardLengthConversionCombination())
2697    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
2698                                diag::warn_format_non_standard_conversion_spec);
2699
2700  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2701    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2702
2703  // The remaining checks depend on the data arguments.
2704  if (HasVAListArg)
2705    return true;
2706
2707  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2708    return false;
2709
2710  const Expr *Arg = getDataArg(argIndex);
2711  if (!Arg)
2712    return true;
2713
2714  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
2715}
2716
2717static bool requiresParensToAddCast(const Expr *E) {
2718  // FIXME: We should have a general way to reason about operator
2719  // precedence and whether parens are actually needed here.
2720  // Take care of a few common cases where they aren't.
2721  const Expr *Inside = E->IgnoreImpCasts();
2722  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
2723    Inside = POE->getSyntacticForm()->IgnoreImpCasts();
2724
2725  switch (Inside->getStmtClass()) {
2726  case Stmt::ArraySubscriptExprClass:
2727  case Stmt::CallExprClass:
2728  case Stmt::CharacterLiteralClass:
2729  case Stmt::CXXBoolLiteralExprClass:
2730  case Stmt::DeclRefExprClass:
2731  case Stmt::FloatingLiteralClass:
2732  case Stmt::IntegerLiteralClass:
2733  case Stmt::MemberExprClass:
2734  case Stmt::ObjCArrayLiteralClass:
2735  case Stmt::ObjCBoolLiteralExprClass:
2736  case Stmt::ObjCBoxedExprClass:
2737  case Stmt::ObjCDictionaryLiteralClass:
2738  case Stmt::ObjCEncodeExprClass:
2739  case Stmt::ObjCIvarRefExprClass:
2740  case Stmt::ObjCMessageExprClass:
2741  case Stmt::ObjCPropertyRefExprClass:
2742  case Stmt::ObjCStringLiteralClass:
2743  case Stmt::ObjCSubscriptRefExprClass:
2744  case Stmt::ParenExprClass:
2745  case Stmt::StringLiteralClass:
2746  case Stmt::UnaryOperatorClass:
2747    return false;
2748  default:
2749    return true;
2750  }
2751}
2752
2753bool
2754CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2755                                    const char *StartSpecifier,
2756                                    unsigned SpecifierLen,
2757                                    const Expr *E) {
2758  using namespace analyze_format_string;
2759  using namespace analyze_printf;
2760  // Now type check the data expression that matches the
2761  // format specifier.
2762  const analyze_printf::ArgType &AT = FS.getArgType(S.Context,
2763                                                    ObjCContext);
2764  if (!AT.isValid())
2765    return true;
2766
2767  QualType ExprTy = E->getType();
2768  while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
2769    ExprTy = TET->getUnderlyingExpr()->getType();
2770  }
2771
2772  if (AT.matchesType(S.Context, ExprTy))
2773    return true;
2774
2775  // Look through argument promotions for our error message's reported type.
2776  // This includes the integral and floating promotions, but excludes array
2777  // and function pointer decay; seeing that an argument intended to be a
2778  // string has type 'char [6]' is probably more confusing than 'char *'.
2779  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2780    if (ICE->getCastKind() == CK_IntegralCast ||
2781        ICE->getCastKind() == CK_FloatingCast) {
2782      E = ICE->getSubExpr();
2783      ExprTy = E->getType();
2784
2785      // Check if we didn't match because of an implicit cast from a 'char'
2786      // or 'short' to an 'int'.  This is done because printf is a varargs
2787      // function.
2788      if (ICE->getType() == S.Context.IntTy ||
2789          ICE->getType() == S.Context.UnsignedIntTy) {
2790        // All further checking is done on the subexpression.
2791        if (AT.matchesType(S.Context, ExprTy))
2792          return true;
2793      }
2794    }
2795  } else if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) {
2796    // Special case for 'a', which has type 'int' in C.
2797    // Note, however, that we do /not/ want to treat multibyte constants like
2798    // 'MooV' as characters! This form is deprecated but still exists.
2799    if (ExprTy == S.Context.IntTy)
2800      if (llvm::isUIntN(S.Context.getCharWidth(), CL->getValue()))
2801        ExprTy = S.Context.CharTy;
2802  }
2803
2804  // %C in an Objective-C context prints a unichar, not a wchar_t.
2805  // If the argument is an integer of some kind, believe the %C and suggest
2806  // a cast instead of changing the conversion specifier.
2807  QualType IntendedTy = ExprTy;
2808  if (ObjCContext &&
2809      FS.getConversionSpecifier().getKind() == ConversionSpecifier::CArg) {
2810    if (ExprTy->isIntegralOrUnscopedEnumerationType() &&
2811        !ExprTy->isCharType()) {
2812      // 'unichar' is defined as a typedef of unsigned short, but we should
2813      // prefer using the typedef if it is visible.
2814      IntendedTy = S.Context.UnsignedShortTy;
2815
2816      LookupResult Result(S, &S.Context.Idents.get("unichar"), E->getLocStart(),
2817                          Sema::LookupOrdinaryName);
2818      if (S.LookupName(Result, S.getCurScope())) {
2819        NamedDecl *ND = Result.getFoundDecl();
2820        if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(ND))
2821          if (TD->getUnderlyingType() == IntendedTy)
2822            IntendedTy = S.Context.getTypedefType(TD);
2823      }
2824    }
2825  }
2826
2827  // Special-case some of Darwin's platform-independence types by suggesting
2828  // casts to primitive types that are known to be large enough.
2829  bool ShouldNotPrintDirectly = false;
2830  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
2831    // Use a 'while' to peel off layers of typedefs.
2832    QualType TyTy = IntendedTy;
2833    while (const TypedefType *UserTy = TyTy->getAs<TypedefType>()) {
2834      StringRef Name = UserTy->getDecl()->getName();
2835      QualType CastTy = llvm::StringSwitch<QualType>(Name)
2836        .Case("NSInteger", S.Context.LongTy)
2837        .Case("NSUInteger", S.Context.UnsignedLongTy)
2838        .Case("SInt32", S.Context.IntTy)
2839        .Case("UInt32", S.Context.UnsignedIntTy)
2840        .Default(QualType());
2841
2842      if (!CastTy.isNull()) {
2843        ShouldNotPrintDirectly = true;
2844        IntendedTy = CastTy;
2845        break;
2846      }
2847      TyTy = UserTy->desugar();
2848    }
2849  }
2850
2851  // We may be able to offer a FixItHint if it is a supported type.
2852  PrintfSpecifier fixedFS = FS;
2853  bool success = fixedFS.fixType(IntendedTy, S.getLangOpts(),
2854                                 S.Context, ObjCContext);
2855
2856  if (success) {
2857    // Get the fix string from the fixed format specifier
2858    SmallString<16> buf;
2859    llvm::raw_svector_ostream os(buf);
2860    fixedFS.toString(os);
2861
2862    CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
2863
2864    if (IntendedTy == ExprTy) {
2865      // In this case, the specifier is wrong and should be changed to match
2866      // the argument.
2867      EmitFormatDiagnostic(
2868        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2869          << AT.getRepresentativeTypeName(S.Context) << IntendedTy
2870          << E->getSourceRange(),
2871        E->getLocStart(),
2872        /*IsStringLocation*/false,
2873        SpecRange,
2874        FixItHint::CreateReplacement(SpecRange, os.str()));
2875
2876    } else {
2877      // The canonical type for formatting this value is different from the
2878      // actual type of the expression. (This occurs, for example, with Darwin's
2879      // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
2880      // should be printed as 'long' for 64-bit compatibility.)
2881      // Rather than emitting a normal format/argument mismatch, we want to
2882      // add a cast to the recommended type (and correct the format string
2883      // if necessary).
2884      SmallString<16> CastBuf;
2885      llvm::raw_svector_ostream CastFix(CastBuf);
2886      CastFix << "(";
2887      IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
2888      CastFix << ")";
2889
2890      SmallVector<FixItHint,4> Hints;
2891      if (!AT.matchesType(S.Context, IntendedTy))
2892        Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
2893
2894      if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
2895        // If there's already a cast present, just replace it.
2896        SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
2897        Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
2898
2899      } else if (!requiresParensToAddCast(E)) {
2900        // If the expression has high enough precedence,
2901        // just write the C-style cast.
2902        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2903                                                   CastFix.str()));
2904      } else {
2905        // Otherwise, add parens around the expression as well as the cast.
2906        CastFix << "(";
2907        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
2908                                                   CastFix.str()));
2909
2910        SourceLocation After = S.PP.getLocForEndOfToken(E->getLocEnd());
2911        Hints.push_back(FixItHint::CreateInsertion(After, ")"));
2912      }
2913
2914      if (ShouldNotPrintDirectly) {
2915        // The expression has a type that should not be printed directly.
2916        // We extract the name from the typedef because we don't want to show
2917        // the underlying type in the diagnostic.
2918        StringRef Name = cast<TypedefType>(ExprTy)->getDecl()->getName();
2919
2920        EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
2921                               << Name << IntendedTy
2922                               << E->getSourceRange(),
2923                             E->getLocStart(), /*IsStringLocation=*/false,
2924                             SpecRange, Hints);
2925      } else {
2926        // In this case, the expression could be printed using a different
2927        // specifier, but we've decided that the specifier is probably correct
2928        // and we should cast instead. Just use the normal warning message.
2929        EmitFormatDiagnostic(
2930          S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2931            << AT.getRepresentativeTypeName(S.Context) << ExprTy
2932            << E->getSourceRange(),
2933          E->getLocStart(), /*IsStringLocation*/false,
2934          SpecRange, Hints);
2935      }
2936    }
2937  } else {
2938    const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
2939                                                   SpecifierLen);
2940    // Since the warning for passing non-POD types to variadic functions
2941    // was deferred until now, we emit a warning for non-POD
2942    // arguments here.
2943    if (S.isValidVarArgType(ExprTy) == Sema::VAK_Invalid) {
2944      unsigned DiagKind;
2945      if (ExprTy->isObjCObjectType())
2946        DiagKind = diag::err_cannot_pass_objc_interface_to_vararg_format;
2947      else
2948        DiagKind = diag::warn_non_pod_vararg_with_format_string;
2949
2950      EmitFormatDiagnostic(
2951        S.PDiag(DiagKind)
2952          << S.getLangOpts().CPlusPlus11
2953          << ExprTy
2954          << CallType
2955          << AT.getRepresentativeTypeName(S.Context)
2956          << CSR
2957          << E->getSourceRange(),
2958        E->getLocStart(), /*IsStringLocation*/false, CSR);
2959
2960      checkForCStrMembers(AT, E, CSR);
2961    } else
2962      EmitFormatDiagnostic(
2963        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2964          << AT.getRepresentativeTypeName(S.Context) << ExprTy
2965          << CSR
2966          << E->getSourceRange(),
2967        E->getLocStart(), /*IsStringLocation*/false, CSR);
2968  }
2969
2970  return true;
2971}
2972
2973//===--- CHECK: Scanf format string checking ------------------------------===//
2974
2975namespace {
2976class CheckScanfHandler : public CheckFormatHandler {
2977public:
2978  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2979                    const Expr *origFormatExpr, unsigned firstDataArg,
2980                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
2981                    ArrayRef<const Expr *> Args,
2982                    unsigned formatIdx, bool inFunctionCall,
2983                    Sema::VariadicCallType CallType)
2984  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2985                       numDataArgs, beg, hasVAListArg,
2986                       Args, formatIdx, inFunctionCall, CallType)
2987  {}
2988
2989  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2990                            const char *startSpecifier,
2991                            unsigned specifierLen);
2992
2993  bool HandleInvalidScanfConversionSpecifier(
2994          const analyze_scanf::ScanfSpecifier &FS,
2995          const char *startSpecifier,
2996          unsigned specifierLen);
2997
2998  void HandleIncompleteScanList(const char *start, const char *end);
2999};
3000}
3001
3002void CheckScanfHandler::HandleIncompleteScanList(const char *start,
3003                                                 const char *end) {
3004  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
3005                       getLocationOfByte(end), /*IsStringLocation*/true,
3006                       getSpecifierRange(start, end - start));
3007}
3008
3009bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
3010                                        const analyze_scanf::ScanfSpecifier &FS,
3011                                        const char *startSpecifier,
3012                                        unsigned specifierLen) {
3013
3014  const analyze_scanf::ScanfConversionSpecifier &CS =
3015    FS.getConversionSpecifier();
3016
3017  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
3018                                          getLocationOfByte(CS.getStart()),
3019                                          startSpecifier, specifierLen,
3020                                          CS.getStart(), CS.getLength());
3021}
3022
3023bool CheckScanfHandler::HandleScanfSpecifier(
3024                                       const analyze_scanf::ScanfSpecifier &FS,
3025                                       const char *startSpecifier,
3026                                       unsigned specifierLen) {
3027
3028  using namespace analyze_scanf;
3029  using namespace analyze_format_string;
3030
3031  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
3032
3033  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
3034  // be used to decide if we are using positional arguments consistently.
3035  if (FS.consumesDataArgument()) {
3036    if (atFirstArg) {
3037      atFirstArg = false;
3038      usesPositionalArgs = FS.usesPositionalArg();
3039    }
3040    else if (usesPositionalArgs != FS.usesPositionalArg()) {
3041      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
3042                                        startSpecifier, specifierLen);
3043      return false;
3044    }
3045  }
3046
3047  // Check if the field with is non-zero.
3048  const OptionalAmount &Amt = FS.getFieldWidth();
3049  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
3050    if (Amt.getConstantAmount() == 0) {
3051      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
3052                                                   Amt.getConstantLength());
3053      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
3054                           getLocationOfByte(Amt.getStart()),
3055                           /*IsStringLocation*/true, R,
3056                           FixItHint::CreateRemoval(R));
3057    }
3058  }
3059
3060  if (!FS.consumesDataArgument()) {
3061    // FIXME: Technically specifying a precision or field width here
3062    // makes no sense.  Worth issuing a warning at some point.
3063    return true;
3064  }
3065
3066  // Consume the argument.
3067  unsigned argIndex = FS.getArgIndex();
3068  if (argIndex < NumDataArgs) {
3069      // The check to see if the argIndex is valid will come later.
3070      // We set the bit here because we may exit early from this
3071      // function if we encounter some other error.
3072    CoveredArgs.set(argIndex);
3073  }
3074
3075  // Check the length modifier is valid with the given conversion specifier.
3076  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
3077    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3078                                diag::warn_format_nonsensical_length);
3079  else if (!FS.hasStandardLengthModifier())
3080    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
3081  else if (!FS.hasStandardLengthConversionCombination())
3082    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3083                                diag::warn_format_non_standard_conversion_spec);
3084
3085  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
3086    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
3087
3088  // The remaining checks depend on the data arguments.
3089  if (HasVAListArg)
3090    return true;
3091
3092  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
3093    return false;
3094
3095  // Check that the argument type matches the format specifier.
3096  const Expr *Ex = getDataArg(argIndex);
3097  if (!Ex)
3098    return true;
3099
3100  const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
3101  if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType())) {
3102    ScanfSpecifier fixedFS = FS;
3103    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
3104                                   S.Context);
3105
3106    if (success) {
3107      // Get the fix string from the fixed format specifier.
3108      SmallString<128> buf;
3109      llvm::raw_svector_ostream os(buf);
3110      fixedFS.toString(os);
3111
3112      EmitFormatDiagnostic(
3113        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3114          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3115          << Ex->getSourceRange(),
3116        Ex->getLocStart(),
3117        /*IsStringLocation*/false,
3118        getSpecifierRange(startSpecifier, specifierLen),
3119        FixItHint::CreateReplacement(
3120          getSpecifierRange(startSpecifier, specifierLen),
3121          os.str()));
3122    } else {
3123      EmitFormatDiagnostic(
3124        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
3125          << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3126          << Ex->getSourceRange(),
3127        Ex->getLocStart(),
3128        /*IsStringLocation*/false,
3129        getSpecifierRange(startSpecifier, specifierLen));
3130    }
3131  }
3132
3133  return true;
3134}
3135
3136void Sema::CheckFormatString(const StringLiteral *FExpr,
3137                             const Expr *OrigFormatExpr,
3138                             ArrayRef<const Expr *> Args,
3139                             bool HasVAListArg, unsigned format_idx,
3140                             unsigned firstDataArg, FormatStringType Type,
3141                             bool inFunctionCall, VariadicCallType CallType) {
3142
3143  // CHECK: is the format string a wide literal?
3144  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
3145    CheckFormatHandler::EmitFormatDiagnostic(
3146      *this, inFunctionCall, Args[format_idx],
3147      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
3148      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3149    return;
3150  }
3151
3152  // Str - The format string.  NOTE: this is NOT null-terminated!
3153  StringRef StrRef = FExpr->getString();
3154  const char *Str = StrRef.data();
3155  unsigned StrLen = StrRef.size();
3156  const unsigned numDataArgs = Args.size() - firstDataArg;
3157
3158  // CHECK: empty format string?
3159  if (StrLen == 0 && numDataArgs > 0) {
3160    CheckFormatHandler::EmitFormatDiagnostic(
3161      *this, inFunctionCall, Args[format_idx],
3162      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
3163      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
3164    return;
3165  }
3166
3167  if (Type == FST_Printf || Type == FST_NSString) {
3168    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
3169                         numDataArgs, (Type == FST_NSString),
3170                         Str, HasVAListArg, Args, format_idx,
3171                         inFunctionCall, CallType);
3172
3173    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
3174                                                  getLangOpts(),
3175                                                  Context.getTargetInfo()))
3176      H.DoneProcessing();
3177  } else if (Type == FST_Scanf) {
3178    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
3179                        Str, HasVAListArg, Args, format_idx,
3180                        inFunctionCall, CallType);
3181
3182    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
3183                                                 getLangOpts(),
3184                                                 Context.getTargetInfo()))
3185      H.DoneProcessing();
3186  } // TODO: handle other formats
3187}
3188
3189//===--- CHECK: Standard memory functions ---------------------------------===//
3190
3191/// \brief Determine whether the given type is a dynamic class type (e.g.,
3192/// whether it has a vtable).
3193static bool isDynamicClassType(QualType T) {
3194  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
3195    if (CXXRecordDecl *Definition = Record->getDefinition())
3196      if (Definition->isDynamicClass())
3197        return true;
3198
3199  return false;
3200}
3201
3202/// \brief If E is a sizeof expression, returns its argument expression,
3203/// otherwise returns NULL.
3204static const Expr *getSizeOfExprArg(const Expr* E) {
3205  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3206      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3207    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
3208      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
3209
3210  return 0;
3211}
3212
3213/// \brief If E is a sizeof expression, returns its argument type.
3214static QualType getSizeOfArgType(const Expr* E) {
3215  if (const UnaryExprOrTypeTraitExpr *SizeOf =
3216      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
3217    if (SizeOf->getKind() == clang::UETT_SizeOf)
3218      return SizeOf->getTypeOfArgument();
3219
3220  return QualType();
3221}
3222
3223/// \brief Check for dangerous or invalid arguments to memset().
3224///
3225/// This issues warnings on known problematic, dangerous or unspecified
3226/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
3227/// function calls.
3228///
3229/// \param Call The call expression to diagnose.
3230void Sema::CheckMemaccessArguments(const CallExpr *Call,
3231                                   unsigned BId,
3232                                   IdentifierInfo *FnName) {
3233  assert(BId != 0);
3234
3235  // It is possible to have a non-standard definition of memset.  Validate
3236  // we have enough arguments, and if not, abort further checking.
3237  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
3238  if (Call->getNumArgs() < ExpectedNumArgs)
3239    return;
3240
3241  unsigned LastArg = (BId == Builtin::BImemset ||
3242                      BId == Builtin::BIstrndup ? 1 : 2);
3243  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
3244  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
3245
3246  // We have special checking when the length is a sizeof expression.
3247  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
3248  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
3249  llvm::FoldingSetNodeID SizeOfArgID;
3250
3251  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
3252    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
3253    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
3254
3255    QualType DestTy = Dest->getType();
3256    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
3257      QualType PointeeTy = DestPtrTy->getPointeeType();
3258
3259      // Never warn about void type pointers. This can be used to suppress
3260      // false positives.
3261      if (PointeeTy->isVoidType())
3262        continue;
3263
3264      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
3265      // actually comparing the expressions for equality. Because computing the
3266      // expression IDs can be expensive, we only do this if the diagnostic is
3267      // enabled.
3268      if (SizeOfArg &&
3269          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
3270                                   SizeOfArg->getExprLoc())) {
3271        // We only compute IDs for expressions if the warning is enabled, and
3272        // cache the sizeof arg's ID.
3273        if (SizeOfArgID == llvm::FoldingSetNodeID())
3274          SizeOfArg->Profile(SizeOfArgID, Context, true);
3275        llvm::FoldingSetNodeID DestID;
3276        Dest->Profile(DestID, Context, true);
3277        if (DestID == SizeOfArgID) {
3278          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
3279          //       over sizeof(src) as well.
3280          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
3281          StringRef ReadableName = FnName->getName();
3282
3283          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
3284            if (UnaryOp->getOpcode() == UO_AddrOf)
3285              ActionIdx = 1; // If its an address-of operator, just remove it.
3286          if (!PointeeTy->isIncompleteType() &&
3287              (Context.getTypeSize(PointeeTy) == Context.getCharWidth()))
3288            ActionIdx = 2; // If the pointee's size is sizeof(char),
3289                           // suggest an explicit length.
3290
3291          // If the function is defined as a builtin macro, do not show macro
3292          // expansion.
3293          SourceLocation SL = SizeOfArg->getExprLoc();
3294          SourceRange DSR = Dest->getSourceRange();
3295          SourceRange SSR = SizeOfArg->getSourceRange();
3296          SourceManager &SM  = PP.getSourceManager();
3297
3298          if (SM.isMacroArgExpansion(SL)) {
3299            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
3300            SL = SM.getSpellingLoc(SL);
3301            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
3302                             SM.getSpellingLoc(DSR.getEnd()));
3303            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
3304                             SM.getSpellingLoc(SSR.getEnd()));
3305          }
3306
3307          DiagRuntimeBehavior(SL, SizeOfArg,
3308                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
3309                                << ReadableName
3310                                << PointeeTy
3311                                << DestTy
3312                                << DSR
3313                                << SSR);
3314          DiagRuntimeBehavior(SL, SizeOfArg,
3315                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
3316                                << ActionIdx
3317                                << SSR);
3318
3319          break;
3320        }
3321      }
3322
3323      // Also check for cases where the sizeof argument is the exact same
3324      // type as the memory argument, and where it points to a user-defined
3325      // record type.
3326      if (SizeOfArgTy != QualType()) {
3327        if (PointeeTy->isRecordType() &&
3328            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
3329          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
3330                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
3331                                << FnName << SizeOfArgTy << ArgIdx
3332                                << PointeeTy << Dest->getSourceRange()
3333                                << LenExpr->getSourceRange());
3334          break;
3335        }
3336      }
3337
3338      // Always complain about dynamic classes.
3339      if (isDynamicClassType(PointeeTy)) {
3340
3341        unsigned OperationType = 0;
3342        // "overwritten" if we're warning about the destination for any call
3343        // but memcmp; otherwise a verb appropriate to the call.
3344        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
3345          if (BId == Builtin::BImemcpy)
3346            OperationType = 1;
3347          else if(BId == Builtin::BImemmove)
3348            OperationType = 2;
3349          else if (BId == Builtin::BImemcmp)
3350            OperationType = 3;
3351        }
3352
3353        DiagRuntimeBehavior(
3354          Dest->getExprLoc(), Dest,
3355          PDiag(diag::warn_dyn_class_memaccess)
3356            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
3357            << FnName << PointeeTy
3358            << OperationType
3359            << Call->getCallee()->getSourceRange());
3360      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
3361               BId != Builtin::BImemset)
3362        DiagRuntimeBehavior(
3363          Dest->getExprLoc(), Dest,
3364          PDiag(diag::warn_arc_object_memaccess)
3365            << ArgIdx << FnName << PointeeTy
3366            << Call->getCallee()->getSourceRange());
3367      else
3368        continue;
3369
3370      DiagRuntimeBehavior(
3371        Dest->getExprLoc(), Dest,
3372        PDiag(diag::note_bad_memaccess_silence)
3373          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
3374      break;
3375    }
3376  }
3377}
3378
3379// A little helper routine: ignore addition and subtraction of integer literals.
3380// This intentionally does not ignore all integer constant expressions because
3381// we don't want to remove sizeof().
3382static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
3383  Ex = Ex->IgnoreParenCasts();
3384
3385  for (;;) {
3386    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
3387    if (!BO || !BO->isAdditiveOp())
3388      break;
3389
3390    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
3391    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
3392
3393    if (isa<IntegerLiteral>(RHS))
3394      Ex = LHS;
3395    else if (isa<IntegerLiteral>(LHS))
3396      Ex = RHS;
3397    else
3398      break;
3399  }
3400
3401  return Ex;
3402}
3403
3404static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
3405                                                      ASTContext &Context) {
3406  // Only handle constant-sized or VLAs, but not flexible members.
3407  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
3408    // Only issue the FIXIT for arrays of size > 1.
3409    if (CAT->getSize().getSExtValue() <= 1)
3410      return false;
3411  } else if (!Ty->isVariableArrayType()) {
3412    return false;
3413  }
3414  return true;
3415}
3416
3417// Warn if the user has made the 'size' argument to strlcpy or strlcat
3418// be the size of the source, instead of the destination.
3419void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
3420                                    IdentifierInfo *FnName) {
3421
3422  // Don't crash if the user has the wrong number of arguments
3423  if (Call->getNumArgs() != 3)
3424    return;
3425
3426  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
3427  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
3428  const Expr *CompareWithSrc = NULL;
3429
3430  // Look for 'strlcpy(dst, x, sizeof(x))'
3431  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
3432    CompareWithSrc = Ex;
3433  else {
3434    // Look for 'strlcpy(dst, x, strlen(x))'
3435    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
3436      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
3437          && SizeCall->getNumArgs() == 1)
3438        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
3439    }
3440  }
3441
3442  if (!CompareWithSrc)
3443    return;
3444
3445  // Determine if the argument to sizeof/strlen is equal to the source
3446  // argument.  In principle there's all kinds of things you could do
3447  // here, for instance creating an == expression and evaluating it with
3448  // EvaluateAsBooleanCondition, but this uses a more direct technique:
3449  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
3450  if (!SrcArgDRE)
3451    return;
3452
3453  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
3454  if (!CompareWithSrcDRE ||
3455      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
3456    return;
3457
3458  const Expr *OriginalSizeArg = Call->getArg(2);
3459  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
3460    << OriginalSizeArg->getSourceRange() << FnName;
3461
3462  // Output a FIXIT hint if the destination is an array (rather than a
3463  // pointer to an array).  This could be enhanced to handle some
3464  // pointers if we know the actual size, like if DstArg is 'array+2'
3465  // we could say 'sizeof(array)-2'.
3466  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
3467  if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
3468    return;
3469
3470  SmallString<128> sizeString;
3471  llvm::raw_svector_ostream OS(sizeString);
3472  OS << "sizeof(";
3473  DstArg->printPretty(OS, 0, getPrintingPolicy());
3474  OS << ")";
3475
3476  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
3477    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
3478                                    OS.str());
3479}
3480
3481/// Check if two expressions refer to the same declaration.
3482static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
3483  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
3484    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
3485      return D1->getDecl() == D2->getDecl();
3486  return false;
3487}
3488
3489static const Expr *getStrlenExprArg(const Expr *E) {
3490  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
3491    const FunctionDecl *FD = CE->getDirectCallee();
3492    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
3493      return 0;
3494    return CE->getArg(0)->IgnoreParenCasts();
3495  }
3496  return 0;
3497}
3498
3499// Warn on anti-patterns as the 'size' argument to strncat.
3500// The correct size argument should look like following:
3501//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
3502void Sema::CheckStrncatArguments(const CallExpr *CE,
3503                                 IdentifierInfo *FnName) {
3504  // Don't crash if the user has the wrong number of arguments.
3505  if (CE->getNumArgs() < 3)
3506    return;
3507  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
3508  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
3509  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
3510
3511  // Identify common expressions, which are wrongly used as the size argument
3512  // to strncat and may lead to buffer overflows.
3513  unsigned PatternType = 0;
3514  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
3515    // - sizeof(dst)
3516    if (referToTheSameDecl(SizeOfArg, DstArg))
3517      PatternType = 1;
3518    // - sizeof(src)
3519    else if (referToTheSameDecl(SizeOfArg, SrcArg))
3520      PatternType = 2;
3521  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
3522    if (BE->getOpcode() == BO_Sub) {
3523      const Expr *L = BE->getLHS()->IgnoreParenCasts();
3524      const Expr *R = BE->getRHS()->IgnoreParenCasts();
3525      // - sizeof(dst) - strlen(dst)
3526      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
3527          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
3528        PatternType = 1;
3529      // - sizeof(src) - (anything)
3530      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
3531        PatternType = 2;
3532    }
3533  }
3534
3535  if (PatternType == 0)
3536    return;
3537
3538  // Generate the diagnostic.
3539  SourceLocation SL = LenArg->getLocStart();
3540  SourceRange SR = LenArg->getSourceRange();
3541  SourceManager &SM  = PP.getSourceManager();
3542
3543  // If the function is defined as a builtin macro, do not show macro expansion.
3544  if (SM.isMacroArgExpansion(SL)) {
3545    SL = SM.getSpellingLoc(SL);
3546    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
3547                     SM.getSpellingLoc(SR.getEnd()));
3548  }
3549
3550  // Check if the destination is an array (rather than a pointer to an array).
3551  QualType DstTy = DstArg->getType();
3552  bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
3553                                                                    Context);
3554  if (!isKnownSizeArray) {
3555    if (PatternType == 1)
3556      Diag(SL, diag::warn_strncat_wrong_size) << SR;
3557    else
3558      Diag(SL, diag::warn_strncat_src_size) << SR;
3559    return;
3560  }
3561
3562  if (PatternType == 1)
3563    Diag(SL, diag::warn_strncat_large_size) << SR;
3564  else
3565    Diag(SL, diag::warn_strncat_src_size) << SR;
3566
3567  SmallString<128> sizeString;
3568  llvm::raw_svector_ostream OS(sizeString);
3569  OS << "sizeof(";
3570  DstArg->printPretty(OS, 0, getPrintingPolicy());
3571  OS << ") - ";
3572  OS << "strlen(";
3573  DstArg->printPretty(OS, 0, getPrintingPolicy());
3574  OS << ") - 1";
3575
3576  Diag(SL, diag::note_strncat_wrong_size)
3577    << FixItHint::CreateReplacement(SR, OS.str());
3578}
3579
3580//===--- CHECK: Return Address of Stack Variable --------------------------===//
3581
3582static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3583                     Decl *ParentDecl);
3584static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3585                      Decl *ParentDecl);
3586
3587/// CheckReturnStackAddr - Check if a return statement returns the address
3588///   of a stack variable.
3589void
3590Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3591                           SourceLocation ReturnLoc) {
3592
3593  Expr *stackE = 0;
3594  SmallVector<DeclRefExpr *, 8> refVars;
3595
3596  // Perform checking for returned stack addresses, local blocks,
3597  // label addresses or references to temporaries.
3598  if (lhsType->isPointerType() ||
3599      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3600    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3601  } else if (lhsType->isReferenceType()) {
3602    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3603  }
3604
3605  if (stackE == 0)
3606    return; // Nothing suspicious was found.
3607
3608  SourceLocation diagLoc;
3609  SourceRange diagRange;
3610  if (refVars.empty()) {
3611    diagLoc = stackE->getLocStart();
3612    diagRange = stackE->getSourceRange();
3613  } else {
3614    // We followed through a reference variable. 'stackE' contains the
3615    // problematic expression but we will warn at the return statement pointing
3616    // at the reference variable. We will later display the "trail" of
3617    // reference variables using notes.
3618    diagLoc = refVars[0]->getLocStart();
3619    diagRange = refVars[0]->getSourceRange();
3620  }
3621
3622  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3623    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3624                                             : diag::warn_ret_stack_addr)
3625     << DR->getDecl()->getDeclName() << diagRange;
3626  } else if (isa<BlockExpr>(stackE)) { // local block.
3627    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3628  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3629    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3630  } else { // local temporary.
3631    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3632                                             : diag::warn_ret_local_temp_addr)
3633     << diagRange;
3634  }
3635
3636  // Display the "trail" of reference variables that we followed until we
3637  // found the problematic expression using notes.
3638  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3639    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3640    // If this var binds to another reference var, show the range of the next
3641    // var, otherwise the var binds to the problematic expression, in which case
3642    // show the range of the expression.
3643    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3644                                  : stackE->getSourceRange();
3645    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3646      << VD->getDeclName() << range;
3647  }
3648}
3649
3650/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3651///  check if the expression in a return statement evaluates to an address
3652///  to a location on the stack, a local block, an address of a label, or a
3653///  reference to local temporary. The recursion is used to traverse the
3654///  AST of the return expression, with recursion backtracking when we
3655///  encounter a subexpression that (1) clearly does not lead to one of the
3656///  above problematic expressions (2) is something we cannot determine leads to
3657///  a problematic expression based on such local checking.
3658///
3659///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3660///  the expression that they point to. Such variables are added to the
3661///  'refVars' vector so that we know what the reference variable "trail" was.
3662///
3663///  EvalAddr processes expressions that are pointers that are used as
3664///  references (and not L-values).  EvalVal handles all other values.
3665///  At the base case of the recursion is a check for the above problematic
3666///  expressions.
3667///
3668///  This implementation handles:
3669///
3670///   * pointer-to-pointer casts
3671///   * implicit conversions from array references to pointers
3672///   * taking the address of fields
3673///   * arbitrary interplay between "&" and "*" operators
3674///   * pointer arithmetic from an address of a stack variable
3675///   * taking the address of an array element where the array is on the stack
3676static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3677                      Decl *ParentDecl) {
3678  if (E->isTypeDependent())
3679      return NULL;
3680
3681  // We should only be called for evaluating pointer expressions.
3682  assert((E->getType()->isAnyPointerType() ||
3683          E->getType()->isBlockPointerType() ||
3684          E->getType()->isObjCQualifiedIdType()) &&
3685         "EvalAddr only works on pointers");
3686
3687  E = E->IgnoreParens();
3688
3689  // Our "symbolic interpreter" is just a dispatch off the currently
3690  // viewed AST node.  We then recursively traverse the AST by calling
3691  // EvalAddr and EvalVal appropriately.
3692  switch (E->getStmtClass()) {
3693  case Stmt::DeclRefExprClass: {
3694    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3695
3696    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3697      // If this is a reference variable, follow through to the expression that
3698      // it points to.
3699      if (V->hasLocalStorage() &&
3700          V->getType()->isReferenceType() && V->hasInit()) {
3701        // Add the reference variable to the "trail".
3702        refVars.push_back(DR);
3703        return EvalAddr(V->getInit(), refVars, ParentDecl);
3704      }
3705
3706    return NULL;
3707  }
3708
3709  case Stmt::UnaryOperatorClass: {
3710    // The only unary operator that make sense to handle here
3711    // is AddrOf.  All others don't make sense as pointers.
3712    UnaryOperator *U = cast<UnaryOperator>(E);
3713
3714    if (U->getOpcode() == UO_AddrOf)
3715      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3716    else
3717      return NULL;
3718  }
3719
3720  case Stmt::BinaryOperatorClass: {
3721    // Handle pointer arithmetic.  All other binary operators are not valid
3722    // in this context.
3723    BinaryOperator *B = cast<BinaryOperator>(E);
3724    BinaryOperatorKind op = B->getOpcode();
3725
3726    if (op != BO_Add && op != BO_Sub)
3727      return NULL;
3728
3729    Expr *Base = B->getLHS();
3730
3731    // Determine which argument is the real pointer base.  It could be
3732    // the RHS argument instead of the LHS.
3733    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3734
3735    assert (Base->getType()->isPointerType());
3736    return EvalAddr(Base, refVars, ParentDecl);
3737  }
3738
3739  // For conditional operators we need to see if either the LHS or RHS are
3740  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3741  case Stmt::ConditionalOperatorClass: {
3742    ConditionalOperator *C = cast<ConditionalOperator>(E);
3743
3744    // Handle the GNU extension for missing LHS.
3745    if (Expr *lhsExpr = C->getLHS()) {
3746    // In C++, we can have a throw-expression, which has 'void' type.
3747      if (!lhsExpr->getType()->isVoidType())
3748        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3749          return LHS;
3750    }
3751
3752    // In C++, we can have a throw-expression, which has 'void' type.
3753    if (C->getRHS()->getType()->isVoidType())
3754      return NULL;
3755
3756    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3757  }
3758
3759  case Stmt::BlockExprClass:
3760    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3761      return E; // local block.
3762    return NULL;
3763
3764  case Stmt::AddrLabelExprClass:
3765    return E; // address of label.
3766
3767  case Stmt::ExprWithCleanupsClass:
3768    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3769                    ParentDecl);
3770
3771  // For casts, we need to handle conversions from arrays to
3772  // pointer values, and pointer-to-pointer conversions.
3773  case Stmt::ImplicitCastExprClass:
3774  case Stmt::CStyleCastExprClass:
3775  case Stmt::CXXFunctionalCastExprClass:
3776  case Stmt::ObjCBridgedCastExprClass:
3777  case Stmt::CXXStaticCastExprClass:
3778  case Stmt::CXXDynamicCastExprClass:
3779  case Stmt::CXXConstCastExprClass:
3780  case Stmt::CXXReinterpretCastExprClass: {
3781    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3782    switch (cast<CastExpr>(E)->getCastKind()) {
3783    case CK_BitCast:
3784    case CK_LValueToRValue:
3785    case CK_NoOp:
3786    case CK_BaseToDerived:
3787    case CK_DerivedToBase:
3788    case CK_UncheckedDerivedToBase:
3789    case CK_Dynamic:
3790    case CK_CPointerToObjCPointerCast:
3791    case CK_BlockPointerToObjCPointerCast:
3792    case CK_AnyPointerToBlockPointerCast:
3793      return EvalAddr(SubExpr, refVars, ParentDecl);
3794
3795    case CK_ArrayToPointerDecay:
3796      return EvalVal(SubExpr, refVars, ParentDecl);
3797
3798    default:
3799      return 0;
3800    }
3801  }
3802
3803  case Stmt::MaterializeTemporaryExprClass:
3804    if (Expr *Result = EvalAddr(
3805                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3806                                refVars, ParentDecl))
3807      return Result;
3808
3809    return E;
3810
3811  // Everything else: we simply don't reason about them.
3812  default:
3813    return NULL;
3814  }
3815}
3816
3817
3818///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3819///   See the comments for EvalAddr for more details.
3820static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3821                     Decl *ParentDecl) {
3822do {
3823  // We should only be called for evaluating non-pointer expressions, or
3824  // expressions with a pointer type that are not used as references but instead
3825  // are l-values (e.g., DeclRefExpr with a pointer type).
3826
3827  // Our "symbolic interpreter" is just a dispatch off the currently
3828  // viewed AST node.  We then recursively traverse the AST by calling
3829  // EvalAddr and EvalVal appropriately.
3830
3831  E = E->IgnoreParens();
3832  switch (E->getStmtClass()) {
3833  case Stmt::ImplicitCastExprClass: {
3834    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3835    if (IE->getValueKind() == VK_LValue) {
3836      E = IE->getSubExpr();
3837      continue;
3838    }
3839    return NULL;
3840  }
3841
3842  case Stmt::ExprWithCleanupsClass:
3843    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3844
3845  case Stmt::DeclRefExprClass: {
3846    // When we hit a DeclRefExpr we are looking at code that refers to a
3847    // variable's name. If it's not a reference variable we check if it has
3848    // local storage within the function, and if so, return the expression.
3849    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3850
3851    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3852      // Check if it refers to itself, e.g. "int& i = i;".
3853      if (V == ParentDecl)
3854        return DR;
3855
3856      if (V->hasLocalStorage()) {
3857        if (!V->getType()->isReferenceType())
3858          return DR;
3859
3860        // Reference variable, follow through to the expression that
3861        // it points to.
3862        if (V->hasInit()) {
3863          // Add the reference variable to the "trail".
3864          refVars.push_back(DR);
3865          return EvalVal(V->getInit(), refVars, V);
3866        }
3867      }
3868    }
3869
3870    return NULL;
3871  }
3872
3873  case Stmt::UnaryOperatorClass: {
3874    // The only unary operator that make sense to handle here
3875    // is Deref.  All others don't resolve to a "name."  This includes
3876    // handling all sorts of rvalues passed to a unary operator.
3877    UnaryOperator *U = cast<UnaryOperator>(E);
3878
3879    if (U->getOpcode() == UO_Deref)
3880      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3881
3882    return NULL;
3883  }
3884
3885  case Stmt::ArraySubscriptExprClass: {
3886    // Array subscripts are potential references to data on the stack.  We
3887    // retrieve the DeclRefExpr* for the array variable if it indeed
3888    // has local storage.
3889    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3890  }
3891
3892  case Stmt::ConditionalOperatorClass: {
3893    // For conditional operators we need to see if either the LHS or RHS are
3894    // non-NULL Expr's.  If one is non-NULL, we return it.
3895    ConditionalOperator *C = cast<ConditionalOperator>(E);
3896
3897    // Handle the GNU extension for missing LHS.
3898    if (Expr *lhsExpr = C->getLHS())
3899      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3900        return LHS;
3901
3902    return EvalVal(C->getRHS(), refVars, ParentDecl);
3903  }
3904
3905  // Accesses to members are potential references to data on the stack.
3906  case Stmt::MemberExprClass: {
3907    MemberExpr *M = cast<MemberExpr>(E);
3908
3909    // Check for indirect access.  We only want direct field accesses.
3910    if (M->isArrow())
3911      return NULL;
3912
3913    // Check whether the member type is itself a reference, in which case
3914    // we're not going to refer to the member, but to what the member refers to.
3915    if (M->getMemberDecl()->getType()->isReferenceType())
3916      return NULL;
3917
3918    return EvalVal(M->getBase(), refVars, ParentDecl);
3919  }
3920
3921  case Stmt::MaterializeTemporaryExprClass:
3922    if (Expr *Result = EvalVal(
3923                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3924                               refVars, ParentDecl))
3925      return Result;
3926
3927    return E;
3928
3929  default:
3930    // Check that we don't return or take the address of a reference to a
3931    // temporary. This is only useful in C++.
3932    if (!E->isTypeDependent() && E->isRValue())
3933      return E;
3934
3935    // Everything else: we simply don't reason about them.
3936    return NULL;
3937  }
3938} while (true);
3939}
3940
3941//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3942
3943/// Check for comparisons of floating point operands using != and ==.
3944/// Issue a warning if these are no self-comparisons, as they are not likely
3945/// to do what the programmer intended.
3946void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3947  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3948  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3949
3950  // Special case: check for x == x (which is OK).
3951  // Do not emit warnings for such cases.
3952  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3953    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3954      if (DRL->getDecl() == DRR->getDecl())
3955        return;
3956
3957
3958  // Special case: check for comparisons against literals that can be exactly
3959  //  represented by APFloat.  In such cases, do not emit a warning.  This
3960  //  is a heuristic: often comparison against such literals are used to
3961  //  detect if a value in a variable has not changed.  This clearly can
3962  //  lead to false negatives.
3963  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3964    if (FLL->isExact())
3965      return;
3966  } else
3967    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
3968      if (FLR->isExact())
3969        return;
3970
3971  // Check for comparisons with builtin types.
3972  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3973    if (CL->isBuiltinCall())
3974      return;
3975
3976  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3977    if (CR->isBuiltinCall())
3978      return;
3979
3980  // Emit the diagnostic.
3981  Diag(Loc, diag::warn_floatingpoint_eq)
3982    << LHS->getSourceRange() << RHS->getSourceRange();
3983}
3984
3985//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3986//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3987
3988namespace {
3989
3990/// Structure recording the 'active' range of an integer-valued
3991/// expression.
3992struct IntRange {
3993  /// The number of bits active in the int.
3994  unsigned Width;
3995
3996  /// True if the int is known not to have negative values.
3997  bool NonNegative;
3998
3999  IntRange(unsigned Width, bool NonNegative)
4000    : Width(Width), NonNegative(NonNegative)
4001  {}
4002
4003  /// Returns the range of the bool type.
4004  static IntRange forBoolType() {
4005    return IntRange(1, true);
4006  }
4007
4008  /// Returns the range of an opaque value of the given integral type.
4009  static IntRange forValueOfType(ASTContext &C, QualType T) {
4010    return forValueOfCanonicalType(C,
4011                          T->getCanonicalTypeInternal().getTypePtr());
4012  }
4013
4014  /// Returns the range of an opaque value of a canonical integral type.
4015  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
4016    assert(T->isCanonicalUnqualified());
4017
4018    if (const VectorType *VT = dyn_cast<VectorType>(T))
4019      T = VT->getElementType().getTypePtr();
4020    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4021      T = CT->getElementType().getTypePtr();
4022
4023    // For enum types, use the known bit width of the enumerators.
4024    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
4025      EnumDecl *Enum = ET->getDecl();
4026      if (!Enum->isCompleteDefinition())
4027        return IntRange(C.getIntWidth(QualType(T, 0)), false);
4028
4029      unsigned NumPositive = Enum->getNumPositiveBits();
4030      unsigned NumNegative = Enum->getNumNegativeBits();
4031
4032      if (NumNegative == 0)
4033        return IntRange(NumPositive, true/*NonNegative*/);
4034      else
4035        return IntRange(std::max(NumPositive + 1, NumNegative),
4036                        false/*NonNegative*/);
4037    }
4038
4039    const BuiltinType *BT = cast<BuiltinType>(T);
4040    assert(BT->isInteger());
4041
4042    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4043  }
4044
4045  /// Returns the "target" range of a canonical integral type, i.e.
4046  /// the range of values expressible in the type.
4047  ///
4048  /// This matches forValueOfCanonicalType except that enums have the
4049  /// full range of their type, not the range of their enumerators.
4050  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
4051    assert(T->isCanonicalUnqualified());
4052
4053    if (const VectorType *VT = dyn_cast<VectorType>(T))
4054      T = VT->getElementType().getTypePtr();
4055    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
4056      T = CT->getElementType().getTypePtr();
4057    if (const EnumType *ET = dyn_cast<EnumType>(T))
4058      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
4059
4060    const BuiltinType *BT = cast<BuiltinType>(T);
4061    assert(BT->isInteger());
4062
4063    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
4064  }
4065
4066  /// Returns the supremum of two ranges: i.e. their conservative merge.
4067  static IntRange join(IntRange L, IntRange R) {
4068    return IntRange(std::max(L.Width, R.Width),
4069                    L.NonNegative && R.NonNegative);
4070  }
4071
4072  /// Returns the infinum of two ranges: i.e. their aggressive merge.
4073  static IntRange meet(IntRange L, IntRange R) {
4074    return IntRange(std::min(L.Width, R.Width),
4075                    L.NonNegative || R.NonNegative);
4076  }
4077};
4078
4079static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
4080                              unsigned MaxWidth) {
4081  if (value.isSigned() && value.isNegative())
4082    return IntRange(value.getMinSignedBits(), false);
4083
4084  if (value.getBitWidth() > MaxWidth)
4085    value = value.trunc(MaxWidth);
4086
4087  // isNonNegative() just checks the sign bit without considering
4088  // signedness.
4089  return IntRange(value.getActiveBits(), true);
4090}
4091
4092static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
4093                              unsigned MaxWidth) {
4094  if (result.isInt())
4095    return GetValueRange(C, result.getInt(), MaxWidth);
4096
4097  if (result.isVector()) {
4098    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
4099    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
4100      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
4101      R = IntRange::join(R, El);
4102    }
4103    return R;
4104  }
4105
4106  if (result.isComplexInt()) {
4107    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
4108    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
4109    return IntRange::join(R, I);
4110  }
4111
4112  // This can happen with lossless casts to intptr_t of "based" lvalues.
4113  // Assume it might use arbitrary bits.
4114  // FIXME: The only reason we need to pass the type in here is to get
4115  // the sign right on this one case.  It would be nice if APValue
4116  // preserved this.
4117  assert(result.isLValue() || result.isAddrLabelDiff());
4118  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
4119}
4120
4121/// Pseudo-evaluate the given integer expression, estimating the
4122/// range of values it might take.
4123///
4124/// \param MaxWidth - the width to which the value will be truncated
4125static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
4126  E = E->IgnoreParens();
4127
4128  // Try a full evaluation first.
4129  Expr::EvalResult result;
4130  if (E->EvaluateAsRValue(result, C))
4131    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
4132
4133  // I think we only want to look through implicit casts here; if the
4134  // user has an explicit widening cast, we should treat the value as
4135  // being of the new, wider type.
4136  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
4137    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
4138      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
4139
4140    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
4141
4142    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
4143
4144    // Assume that non-integer casts can span the full range of the type.
4145    if (!isIntegerCast)
4146      return OutputTypeRange;
4147
4148    IntRange SubRange
4149      = GetExprRange(C, CE->getSubExpr(),
4150                     std::min(MaxWidth, OutputTypeRange.Width));
4151
4152    // Bail out if the subexpr's range is as wide as the cast type.
4153    if (SubRange.Width >= OutputTypeRange.Width)
4154      return OutputTypeRange;
4155
4156    // Otherwise, we take the smaller width, and we're non-negative if
4157    // either the output type or the subexpr is.
4158    return IntRange(SubRange.Width,
4159                    SubRange.NonNegative || OutputTypeRange.NonNegative);
4160  }
4161
4162  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
4163    // If we can fold the condition, just take that operand.
4164    bool CondResult;
4165    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
4166      return GetExprRange(C, CondResult ? CO->getTrueExpr()
4167                                        : CO->getFalseExpr(),
4168                          MaxWidth);
4169
4170    // Otherwise, conservatively merge.
4171    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
4172    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
4173    return IntRange::join(L, R);
4174  }
4175
4176  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4177    switch (BO->getOpcode()) {
4178
4179    // Boolean-valued operations are single-bit and positive.
4180    case BO_LAnd:
4181    case BO_LOr:
4182    case BO_LT:
4183    case BO_GT:
4184    case BO_LE:
4185    case BO_GE:
4186    case BO_EQ:
4187    case BO_NE:
4188      return IntRange::forBoolType();
4189
4190    // The type of the assignments is the type of the LHS, so the RHS
4191    // is not necessarily the same type.
4192    case BO_MulAssign:
4193    case BO_DivAssign:
4194    case BO_RemAssign:
4195    case BO_AddAssign:
4196    case BO_SubAssign:
4197    case BO_XorAssign:
4198    case BO_OrAssign:
4199      // TODO: bitfields?
4200      return IntRange::forValueOfType(C, E->getType());
4201
4202    // Simple assignments just pass through the RHS, which will have
4203    // been coerced to the LHS type.
4204    case BO_Assign:
4205      // TODO: bitfields?
4206      return GetExprRange(C, BO->getRHS(), MaxWidth);
4207
4208    // Operations with opaque sources are black-listed.
4209    case BO_PtrMemD:
4210    case BO_PtrMemI:
4211      return IntRange::forValueOfType(C, E->getType());
4212
4213    // Bitwise-and uses the *infinum* of the two source ranges.
4214    case BO_And:
4215    case BO_AndAssign:
4216      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
4217                            GetExprRange(C, BO->getRHS(), MaxWidth));
4218
4219    // Left shift gets black-listed based on a judgement call.
4220    case BO_Shl:
4221      // ...except that we want to treat '1 << (blah)' as logically
4222      // positive.  It's an important idiom.
4223      if (IntegerLiteral *I
4224            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
4225        if (I->getValue() == 1) {
4226          IntRange R = IntRange::forValueOfType(C, E->getType());
4227          return IntRange(R.Width, /*NonNegative*/ true);
4228        }
4229      }
4230      // fallthrough
4231
4232    case BO_ShlAssign:
4233      return IntRange::forValueOfType(C, E->getType());
4234
4235    // Right shift by a constant can narrow its left argument.
4236    case BO_Shr:
4237    case BO_ShrAssign: {
4238      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4239
4240      // If the shift amount is a positive constant, drop the width by
4241      // that much.
4242      llvm::APSInt shift;
4243      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
4244          shift.isNonNegative()) {
4245        unsigned zext = shift.getZExtValue();
4246        if (zext >= L.Width)
4247          L.Width = (L.NonNegative ? 0 : 1);
4248        else
4249          L.Width -= zext;
4250      }
4251
4252      return L;
4253    }
4254
4255    // Comma acts as its right operand.
4256    case BO_Comma:
4257      return GetExprRange(C, BO->getRHS(), MaxWidth);
4258
4259    // Black-list pointer subtractions.
4260    case BO_Sub:
4261      if (BO->getLHS()->getType()->isPointerType())
4262        return IntRange::forValueOfType(C, E->getType());
4263      break;
4264
4265    // The width of a division result is mostly determined by the size
4266    // of the LHS.
4267    case BO_Div: {
4268      // Don't 'pre-truncate' the operands.
4269      unsigned opWidth = C.getIntWidth(E->getType());
4270      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4271
4272      // If the divisor is constant, use that.
4273      llvm::APSInt divisor;
4274      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
4275        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
4276        if (log2 >= L.Width)
4277          L.Width = (L.NonNegative ? 0 : 1);
4278        else
4279          L.Width = std::min(L.Width - log2, MaxWidth);
4280        return L;
4281      }
4282
4283      // Otherwise, just use the LHS's width.
4284      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4285      return IntRange(L.Width, L.NonNegative && R.NonNegative);
4286    }
4287
4288    // The result of a remainder can't be larger than the result of
4289    // either side.
4290    case BO_Rem: {
4291      // Don't 'pre-truncate' the operands.
4292      unsigned opWidth = C.getIntWidth(E->getType());
4293      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
4294      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
4295
4296      IntRange meet = IntRange::meet(L, R);
4297      meet.Width = std::min(meet.Width, MaxWidth);
4298      return meet;
4299    }
4300
4301    // The default behavior is okay for these.
4302    case BO_Mul:
4303    case BO_Add:
4304    case BO_Xor:
4305    case BO_Or:
4306      break;
4307    }
4308
4309    // The default case is to treat the operation as if it were closed
4310    // on the narrowest type that encompasses both operands.
4311    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4312    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
4313    return IntRange::join(L, R);
4314  }
4315
4316  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
4317    switch (UO->getOpcode()) {
4318    // Boolean-valued operations are white-listed.
4319    case UO_LNot:
4320      return IntRange::forBoolType();
4321
4322    // Operations with opaque sources are black-listed.
4323    case UO_Deref:
4324    case UO_AddrOf: // should be impossible
4325      return IntRange::forValueOfType(C, E->getType());
4326
4327    default:
4328      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
4329    }
4330  }
4331
4332  if (dyn_cast<OffsetOfExpr>(E)) {
4333    IntRange::forValueOfType(C, E->getType());
4334  }
4335
4336  if (FieldDecl *BitField = E->getSourceBitField())
4337    return IntRange(BitField->getBitWidthValue(C),
4338                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
4339
4340  return IntRange::forValueOfType(C, E->getType());
4341}
4342
4343static IntRange GetExprRange(ASTContext &C, Expr *E) {
4344  return GetExprRange(C, E, C.getIntWidth(E->getType()));
4345}
4346
4347/// Checks whether the given value, which currently has the given
4348/// source semantics, has the same value when coerced through the
4349/// target semantics.
4350static bool IsSameFloatAfterCast(const llvm::APFloat &value,
4351                                 const llvm::fltSemantics &Src,
4352                                 const llvm::fltSemantics &Tgt) {
4353  llvm::APFloat truncated = value;
4354
4355  bool ignored;
4356  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
4357  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
4358
4359  return truncated.bitwiseIsEqual(value);
4360}
4361
4362/// Checks whether the given value, which currently has the given
4363/// source semantics, has the same value when coerced through the
4364/// target semantics.
4365///
4366/// The value might be a vector of floats (or a complex number).
4367static bool IsSameFloatAfterCast(const APValue &value,
4368                                 const llvm::fltSemantics &Src,
4369                                 const llvm::fltSemantics &Tgt) {
4370  if (value.isFloat())
4371    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
4372
4373  if (value.isVector()) {
4374    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
4375      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
4376        return false;
4377    return true;
4378  }
4379
4380  assert(value.isComplexFloat());
4381  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
4382          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
4383}
4384
4385static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
4386
4387static bool IsZero(Sema &S, Expr *E) {
4388  // Suppress cases where we are comparing against an enum constant.
4389  if (const DeclRefExpr *DR =
4390      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
4391    if (isa<EnumConstantDecl>(DR->getDecl()))
4392      return false;
4393
4394  // Suppress cases where the '0' value is expanded from a macro.
4395  if (E->getLocStart().isMacroID())
4396    return false;
4397
4398  llvm::APSInt Value;
4399  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
4400}
4401
4402static bool HasEnumType(Expr *E) {
4403  // Strip off implicit integral promotions.
4404  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
4405    if (ICE->getCastKind() != CK_IntegralCast &&
4406        ICE->getCastKind() != CK_NoOp)
4407      break;
4408    E = ICE->getSubExpr();
4409  }
4410
4411  return E->getType()->isEnumeralType();
4412}
4413
4414static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
4415  BinaryOperatorKind op = E->getOpcode();
4416  if (E->isValueDependent())
4417    return;
4418
4419  if (op == BO_LT && IsZero(S, E->getRHS())) {
4420    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4421      << "< 0" << "false" << HasEnumType(E->getLHS())
4422      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4423  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
4424    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4425      << ">= 0" << "true" << HasEnumType(E->getLHS())
4426      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4427  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
4428    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4429      << "0 >" << "false" << HasEnumType(E->getRHS())
4430      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4431  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
4432    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4433      << "0 <=" << "true" << HasEnumType(E->getRHS())
4434      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4435  }
4436}
4437
4438static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
4439                                         Expr *Constant, Expr *Other,
4440                                         llvm::APSInt Value,
4441                                         bool RhsConstant) {
4442  // 0 values are handled later by CheckTrivialUnsignedComparison().
4443  if (Value == 0)
4444    return;
4445
4446  BinaryOperatorKind op = E->getOpcode();
4447  QualType OtherT = Other->getType();
4448  QualType ConstantT = Constant->getType();
4449  QualType CommonT = E->getLHS()->getType();
4450  if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
4451    return;
4452  assert((OtherT->isIntegerType() && ConstantT->isIntegerType())
4453         && "comparison with non-integer type");
4454
4455  bool ConstantSigned = ConstantT->isSignedIntegerType();
4456  bool CommonSigned = CommonT->isSignedIntegerType();
4457
4458  bool EqualityOnly = false;
4459
4460  // TODO: Investigate using GetExprRange() to get tighter bounds on
4461  // on the bit ranges.
4462  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
4463  unsigned OtherWidth = OtherRange.Width;
4464
4465  if (CommonSigned) {
4466    // The common type is signed, therefore no signed to unsigned conversion.
4467    if (!OtherRange.NonNegative) {
4468      // Check that the constant is representable in type OtherT.
4469      if (ConstantSigned) {
4470        if (OtherWidth >= Value.getMinSignedBits())
4471          return;
4472      } else { // !ConstantSigned
4473        if (OtherWidth >= Value.getActiveBits() + 1)
4474          return;
4475      }
4476    } else { // !OtherSigned
4477      // Check that the constant is representable in type OtherT.
4478      // Negative values are out of range.
4479      if (ConstantSigned) {
4480        if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
4481          return;
4482      } else { // !ConstantSigned
4483        if (OtherWidth >= Value.getActiveBits())
4484          return;
4485      }
4486    }
4487  } else {  // !CommonSigned
4488    if (OtherRange.NonNegative) {
4489      if (OtherWidth >= Value.getActiveBits())
4490        return;
4491    } else if (!OtherRange.NonNegative && !ConstantSigned) {
4492      // Check to see if the constant is representable in OtherT.
4493      if (OtherWidth > Value.getActiveBits())
4494        return;
4495      // Check to see if the constant is equivalent to a negative value
4496      // cast to CommonT.
4497      if (S.Context.getIntWidth(ConstantT) == S.Context.getIntWidth(CommonT) &&
4498          Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
4499        return;
4500      // The constant value rests between values that OtherT can represent after
4501      // conversion.  Relational comparison still works, but equality
4502      // comparisons will be tautological.
4503      EqualityOnly = true;
4504    } else { // OtherSigned && ConstantSigned
4505      assert(0 && "Two signed types converted to unsigned types.");
4506    }
4507  }
4508
4509  bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
4510
4511  bool IsTrue = true;
4512  if (op == BO_EQ || op == BO_NE) {
4513    IsTrue = op == BO_NE;
4514  } else if (EqualityOnly) {
4515    return;
4516  } else if (RhsConstant) {
4517    if (op == BO_GT || op == BO_GE)
4518      IsTrue = !PositiveConstant;
4519    else // op == BO_LT || op == BO_LE
4520      IsTrue = PositiveConstant;
4521  } else {
4522    if (op == BO_LT || op == BO_LE)
4523      IsTrue = !PositiveConstant;
4524    else // op == BO_GT || op == BO_GE
4525      IsTrue = PositiveConstant;
4526  }
4527
4528  // If this is a comparison to an enum constant, include that
4529  // constant in the diagnostic.
4530  const EnumConstantDecl *ED = 0;
4531  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
4532    ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
4533
4534  SmallString<64> PrettySourceValue;
4535  llvm::raw_svector_ostream OS(PrettySourceValue);
4536  if (ED)
4537    OS << '\'' << *ED << "' (" << Value << ")";
4538  else
4539    OS << Value;
4540
4541  S.Diag(E->getOperatorLoc(), diag::warn_out_of_range_compare)
4542      << OS.str() << OtherT << IsTrue
4543      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4544}
4545
4546/// Analyze the operands of the given comparison.  Implements the
4547/// fallback case from AnalyzeComparison.
4548static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
4549  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4550  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4551}
4552
4553/// \brief Implements -Wsign-compare.
4554///
4555/// \param E the binary operator to check for warnings
4556static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
4557  // The type the comparison is being performed in.
4558  QualType T = E->getLHS()->getType();
4559  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
4560         && "comparison with mismatched types");
4561  if (E->isValueDependent())
4562    return AnalyzeImpConvsInComparison(S, E);
4563
4564  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
4565  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
4566
4567  bool IsComparisonConstant = false;
4568
4569  // Check whether an integer constant comparison results in a value
4570  // of 'true' or 'false'.
4571  if (T->isIntegralType(S.Context)) {
4572    llvm::APSInt RHSValue;
4573    bool IsRHSIntegralLiteral =
4574      RHS->isIntegerConstantExpr(RHSValue, S.Context);
4575    llvm::APSInt LHSValue;
4576    bool IsLHSIntegralLiteral =
4577      LHS->isIntegerConstantExpr(LHSValue, S.Context);
4578    if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
4579        DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
4580    else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
4581      DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
4582    else
4583      IsComparisonConstant =
4584        (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
4585  } else if (!T->hasUnsignedIntegerRepresentation())
4586      IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
4587
4588  // We don't do anything special if this isn't an unsigned integral
4589  // comparison:  we're only interested in integral comparisons, and
4590  // signed comparisons only happen in cases we don't care to warn about.
4591  //
4592  // We also don't care about value-dependent expressions or expressions
4593  // whose result is a constant.
4594  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
4595    return AnalyzeImpConvsInComparison(S, E);
4596
4597  // Check to see if one of the (unmodified) operands is of different
4598  // signedness.
4599  Expr *signedOperand, *unsignedOperand;
4600  if (LHS->getType()->hasSignedIntegerRepresentation()) {
4601    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
4602           "unsigned comparison between two signed integer expressions?");
4603    signedOperand = LHS;
4604    unsignedOperand = RHS;
4605  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
4606    signedOperand = RHS;
4607    unsignedOperand = LHS;
4608  } else {
4609    CheckTrivialUnsignedComparison(S, E);
4610    return AnalyzeImpConvsInComparison(S, E);
4611  }
4612
4613  // Otherwise, calculate the effective range of the signed operand.
4614  IntRange signedRange = GetExprRange(S.Context, signedOperand);
4615
4616  // Go ahead and analyze implicit conversions in the operands.  Note
4617  // that we skip the implicit conversions on both sides.
4618  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
4619  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
4620
4621  // If the signed range is non-negative, -Wsign-compare won't fire,
4622  // but we should still check for comparisons which are always true
4623  // or false.
4624  if (signedRange.NonNegative)
4625    return CheckTrivialUnsignedComparison(S, E);
4626
4627  // For (in)equality comparisons, if the unsigned operand is a
4628  // constant which cannot collide with a overflowed signed operand,
4629  // then reinterpreting the signed operand as unsigned will not
4630  // change the result of the comparison.
4631  if (E->isEqualityOp()) {
4632    unsigned comparisonWidth = S.Context.getIntWidth(T);
4633    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
4634
4635    // We should never be unable to prove that the unsigned operand is
4636    // non-negative.
4637    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
4638
4639    if (unsignedRange.Width < comparisonWidth)
4640      return;
4641  }
4642
4643  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
4644    S.PDiag(diag::warn_mixed_sign_comparison)
4645      << LHS->getType() << RHS->getType()
4646      << LHS->getSourceRange() << RHS->getSourceRange());
4647}
4648
4649/// Analyzes an attempt to assign the given value to a bitfield.
4650///
4651/// Returns true if there was something fishy about the attempt.
4652static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
4653                                      SourceLocation InitLoc) {
4654  assert(Bitfield->isBitField());
4655  if (Bitfield->isInvalidDecl())
4656    return false;
4657
4658  // White-list bool bitfields.
4659  if (Bitfield->getType()->isBooleanType())
4660    return false;
4661
4662  // Ignore value- or type-dependent expressions.
4663  if (Bitfield->getBitWidth()->isValueDependent() ||
4664      Bitfield->getBitWidth()->isTypeDependent() ||
4665      Init->isValueDependent() ||
4666      Init->isTypeDependent())
4667    return false;
4668
4669  Expr *OriginalInit = Init->IgnoreParenImpCasts();
4670
4671  llvm::APSInt Value;
4672  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
4673    return false;
4674
4675  unsigned OriginalWidth = Value.getBitWidth();
4676  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
4677
4678  if (OriginalWidth <= FieldWidth)
4679    return false;
4680
4681  // Compute the value which the bitfield will contain.
4682  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
4683  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
4684
4685  // Check whether the stored value is equal to the original value.
4686  TruncatedValue = TruncatedValue.extend(OriginalWidth);
4687  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
4688    return false;
4689
4690  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4691  // therefore don't strictly fit into a signed bitfield of width 1.
4692  if (FieldWidth == 1 && Value == 1)
4693    return false;
4694
4695  std::string PrettyValue = Value.toString(10);
4696  std::string PrettyTrunc = TruncatedValue.toString(10);
4697
4698  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4699    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4700    << Init->getSourceRange();
4701
4702  return true;
4703}
4704
4705/// Analyze the given simple or compound assignment for warning-worthy
4706/// operations.
4707static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4708  // Just recurse on the LHS.
4709  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4710
4711  // We want to recurse on the RHS as normal unless we're assigning to
4712  // a bitfield.
4713  if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
4714    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4715                                  E->getOperatorLoc())) {
4716      // Recurse, ignoring any implicit conversions on the RHS.
4717      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4718                                        E->getOperatorLoc());
4719    }
4720  }
4721
4722  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4723}
4724
4725/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4726static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4727                            SourceLocation CContext, unsigned diag,
4728                            bool pruneControlFlow = false) {
4729  if (pruneControlFlow) {
4730    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4731                          S.PDiag(diag)
4732                            << SourceType << T << E->getSourceRange()
4733                            << SourceRange(CContext));
4734    return;
4735  }
4736  S.Diag(E->getExprLoc(), diag)
4737    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4738}
4739
4740/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4741static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4742                            SourceLocation CContext, unsigned diag,
4743                            bool pruneControlFlow = false) {
4744  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4745}
4746
4747/// Diagnose an implicit cast from a literal expression. Does not warn when the
4748/// cast wouldn't lose information.
4749void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4750                                    SourceLocation CContext) {
4751  // Try to convert the literal exactly to an integer. If we can, don't warn.
4752  bool isExact = false;
4753  const llvm::APFloat &Value = FL->getValue();
4754  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4755                            T->hasUnsignedIntegerRepresentation());
4756  if (Value.convertToInteger(IntegerValue,
4757                             llvm::APFloat::rmTowardZero, &isExact)
4758      == llvm::APFloat::opOK && isExact)
4759    return;
4760
4761  SmallString<16> PrettySourceValue;
4762  Value.toString(PrettySourceValue);
4763  SmallString<16> PrettyTargetValue;
4764  if (T->isSpecificBuiltinType(BuiltinType::Bool))
4765    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
4766  else
4767    IntegerValue.toString(PrettyTargetValue);
4768
4769  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4770    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
4771    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
4772}
4773
4774std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4775  if (!Range.Width) return "0";
4776
4777  llvm::APSInt ValueInRange = Value;
4778  ValueInRange.setIsSigned(!Range.NonNegative);
4779  ValueInRange = ValueInRange.trunc(Range.Width);
4780  return ValueInRange.toString(10);
4781}
4782
4783static bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
4784  if (!isa<ImplicitCastExpr>(Ex))
4785    return false;
4786
4787  Expr *InnerE = Ex->IgnoreParenImpCasts();
4788  const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
4789  const Type *Source =
4790    S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4791  if (Target->isDependentType())
4792    return false;
4793
4794  const BuiltinType *FloatCandidateBT =
4795    dyn_cast<BuiltinType>(ToBool ? Source : Target);
4796  const Type *BoolCandidateType = ToBool ? Target : Source;
4797
4798  return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
4799          FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
4800}
4801
4802void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
4803                                      SourceLocation CC) {
4804  unsigned NumArgs = TheCall->getNumArgs();
4805  for (unsigned i = 0; i < NumArgs; ++i) {
4806    Expr *CurrA = TheCall->getArg(i);
4807    if (!IsImplicitBoolFloatConversion(S, CurrA, true))
4808      continue;
4809
4810    bool IsSwapped = ((i > 0) &&
4811        IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
4812    IsSwapped |= ((i < (NumArgs - 1)) &&
4813        IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
4814    if (IsSwapped) {
4815      // Warn on this floating-point to bool conversion.
4816      DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
4817                      CurrA->getType(), CC,
4818                      diag::warn_impcast_floating_point_to_bool);
4819    }
4820  }
4821}
4822
4823void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4824                             SourceLocation CC, bool *ICContext = 0) {
4825  if (E->isTypeDependent() || E->isValueDependent()) return;
4826
4827  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4828  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4829  if (Source == Target) return;
4830  if (Target->isDependentType()) return;
4831
4832  // If the conversion context location is invalid don't complain. We also
4833  // don't want to emit a warning if the issue occurs from the expansion of
4834  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4835  // delay this check as long as possible. Once we detect we are in that
4836  // scenario, we just return.
4837  if (CC.isInvalid())
4838    return;
4839
4840  // Diagnose implicit casts to bool.
4841  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4842    if (isa<StringLiteral>(E))
4843      // Warn on string literal to bool.  Checks for string literals in logical
4844      // expressions, for instances, assert(0 && "error here"), is prevented
4845      // by a check in AnalyzeImplicitConversions().
4846      return DiagnoseImpCast(S, E, T, CC,
4847                             diag::warn_impcast_string_literal_to_bool);
4848    if (Source->isFunctionType()) {
4849      // Warn on function to bool. Checks free functions and static member
4850      // functions. Weakly imported functions are excluded from the check,
4851      // since it's common to test their value to check whether the linker
4852      // found a definition for them.
4853      ValueDecl *D = 0;
4854      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4855        D = R->getDecl();
4856      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4857        D = M->getMemberDecl();
4858      }
4859
4860      if (D && !D->isWeak()) {
4861        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4862          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4863            << F << E->getSourceRange() << SourceRange(CC);
4864          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4865            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4866          QualType ReturnType;
4867          UnresolvedSet<4> NonTemplateOverloads;
4868          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
4869          if (!ReturnType.isNull()
4870              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4871            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4872              << FixItHint::CreateInsertion(
4873                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4874          return;
4875        }
4876      }
4877    }
4878  }
4879
4880  // Strip vector types.
4881  if (isa<VectorType>(Source)) {
4882    if (!isa<VectorType>(Target)) {
4883      if (S.SourceMgr.isInSystemMacro(CC))
4884        return;
4885      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4886    }
4887
4888    // If the vector cast is cast between two vectors of the same size, it is
4889    // a bitcast, not a conversion.
4890    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4891      return;
4892
4893    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4894    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4895  }
4896
4897  // Strip complex types.
4898  if (isa<ComplexType>(Source)) {
4899    if (!isa<ComplexType>(Target)) {
4900      if (S.SourceMgr.isInSystemMacro(CC))
4901        return;
4902
4903      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4904    }
4905
4906    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4907    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4908  }
4909
4910  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4911  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4912
4913  // If the source is floating point...
4914  if (SourceBT && SourceBT->isFloatingPoint()) {
4915    // ...and the target is floating point...
4916    if (TargetBT && TargetBT->isFloatingPoint()) {
4917      // ...then warn if we're dropping FP rank.
4918
4919      // Builtin FP kinds are ordered by increasing FP rank.
4920      if (SourceBT->getKind() > TargetBT->getKind()) {
4921        // Don't warn about float constants that are precisely
4922        // representable in the target type.
4923        Expr::EvalResult result;
4924        if (E->EvaluateAsRValue(result, S.Context)) {
4925          // Value might be a float, a float vector, or a float complex.
4926          if (IsSameFloatAfterCast(result.Val,
4927                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4928                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4929            return;
4930        }
4931
4932        if (S.SourceMgr.isInSystemMacro(CC))
4933          return;
4934
4935        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4936      }
4937      return;
4938    }
4939
4940    // If the target is integral, always warn.
4941    if (TargetBT && TargetBT->isInteger()) {
4942      if (S.SourceMgr.isInSystemMacro(CC))
4943        return;
4944
4945      Expr *InnerE = E->IgnoreParenImpCasts();
4946      // We also want to warn on, e.g., "int i = -1.234"
4947      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4948        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4949          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4950
4951      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4952        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4953      } else {
4954        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4955      }
4956    }
4957
4958    // If the target is bool, warn if expr is a function or method call.
4959    if (Target->isSpecificBuiltinType(BuiltinType::Bool) &&
4960        isa<CallExpr>(E)) {
4961      // Check last argument of function call to see if it is an
4962      // implicit cast from a type matching the type the result
4963      // is being cast to.
4964      CallExpr *CEx = cast<CallExpr>(E);
4965      unsigned NumArgs = CEx->getNumArgs();
4966      if (NumArgs > 0) {
4967        Expr *LastA = CEx->getArg(NumArgs - 1);
4968        Expr *InnerE = LastA->IgnoreParenImpCasts();
4969        const Type *InnerType =
4970          S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
4971        if (isa<ImplicitCastExpr>(LastA) && (InnerType == Target)) {
4972          // Warn on this floating-point to bool conversion
4973          DiagnoseImpCast(S, E, T, CC,
4974                          diag::warn_impcast_floating_point_to_bool);
4975        }
4976      }
4977    }
4978    return;
4979  }
4980
4981  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4982           == Expr::NPCK_GNUNull) && !Target->isAnyPointerType()
4983      && !Target->isBlockPointerType() && !Target->isMemberPointerType()
4984      && Target->isScalarType() && !Target->isNullPtrType()) {
4985    SourceLocation Loc = E->getSourceRange().getBegin();
4986    if (Loc.isMacroID())
4987      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4988    if (!Loc.isMacroID() || CC.isMacroID())
4989      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4990          << T << clang::SourceRange(CC)
4991          << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
4992  }
4993
4994  if (!Source->isIntegerType() || !Target->isIntegerType())
4995    return;
4996
4997  // TODO: remove this early return once the false positives for constant->bool
4998  // in templates, macros, etc, are reduced or removed.
4999  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
5000    return;
5001
5002  IntRange SourceRange = GetExprRange(S.Context, E);
5003  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
5004
5005  if (SourceRange.Width > TargetRange.Width) {
5006    // If the source is a constant, use a default-on diagnostic.
5007    // TODO: this should happen for bitfield stores, too.
5008    llvm::APSInt Value(32);
5009    if (E->isIntegerConstantExpr(Value, S.Context)) {
5010      if (S.SourceMgr.isInSystemMacro(CC))
5011        return;
5012
5013      std::string PrettySourceValue = Value.toString(10);
5014      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
5015
5016      S.DiagRuntimeBehavior(E->getExprLoc(), E,
5017        S.PDiag(diag::warn_impcast_integer_precision_constant)
5018            << PrettySourceValue << PrettyTargetValue
5019            << E->getType() << T << E->getSourceRange()
5020            << clang::SourceRange(CC));
5021      return;
5022    }
5023
5024    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
5025    if (S.SourceMgr.isInSystemMacro(CC))
5026      return;
5027
5028    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
5029      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
5030                             /* pruneControlFlow */ true);
5031    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
5032  }
5033
5034  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
5035      (!TargetRange.NonNegative && SourceRange.NonNegative &&
5036       SourceRange.Width == TargetRange.Width)) {
5037
5038    if (S.SourceMgr.isInSystemMacro(CC))
5039      return;
5040
5041    unsigned DiagID = diag::warn_impcast_integer_sign;
5042
5043    // Traditionally, gcc has warned about this under -Wsign-compare.
5044    // We also want to warn about it in -Wconversion.
5045    // So if -Wconversion is off, use a completely identical diagnostic
5046    // in the sign-compare group.
5047    // The conditional-checking code will
5048    if (ICContext) {
5049      DiagID = diag::warn_impcast_integer_sign_conditional;
5050      *ICContext = true;
5051    }
5052
5053    return DiagnoseImpCast(S, E, T, CC, DiagID);
5054  }
5055
5056  // Diagnose conversions between different enumeration types.
5057  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
5058  // type, to give us better diagnostics.
5059  QualType SourceType = E->getType();
5060  if (!S.getLangOpts().CPlusPlus) {
5061    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5062      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
5063        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
5064        SourceType = S.Context.getTypeDeclType(Enum);
5065        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
5066      }
5067  }
5068
5069  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
5070    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
5071      if (SourceEnum->getDecl()->hasNameForLinkage() &&
5072          TargetEnum->getDecl()->hasNameForLinkage() &&
5073          SourceEnum != TargetEnum) {
5074        if (S.SourceMgr.isInSystemMacro(CC))
5075          return;
5076
5077        return DiagnoseImpCast(S, E, SourceType, T, CC,
5078                               diag::warn_impcast_different_enum_types);
5079      }
5080
5081  return;
5082}
5083
5084void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5085                              SourceLocation CC, QualType T);
5086
5087void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
5088                             SourceLocation CC, bool &ICContext) {
5089  E = E->IgnoreParenImpCasts();
5090
5091  if (isa<ConditionalOperator>(E))
5092    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
5093
5094  AnalyzeImplicitConversions(S, E, CC);
5095  if (E->getType() != T)
5096    return CheckImplicitConversion(S, E, T, CC, &ICContext);
5097  return;
5098}
5099
5100void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
5101                              SourceLocation CC, QualType T) {
5102  AnalyzeImplicitConversions(S, E->getCond(), CC);
5103
5104  bool Suspicious = false;
5105  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
5106  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
5107
5108  // If -Wconversion would have warned about either of the candidates
5109  // for a signedness conversion to the context type...
5110  if (!Suspicious) return;
5111
5112  // ...but it's currently ignored...
5113  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
5114                                 CC))
5115    return;
5116
5117  // ...then check whether it would have warned about either of the
5118  // candidates for a signedness conversion to the condition type.
5119  if (E->getType() == T) return;
5120
5121  Suspicious = false;
5122  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
5123                          E->getType(), CC, &Suspicious);
5124  if (!Suspicious)
5125    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
5126                            E->getType(), CC, &Suspicious);
5127}
5128
5129/// AnalyzeImplicitConversions - Find and report any interesting
5130/// implicit conversions in the given expression.  There are a couple
5131/// of competing diagnostics here, -Wconversion and -Wsign-compare.
5132void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
5133  QualType T = OrigE->getType();
5134  Expr *E = OrigE->IgnoreParenImpCasts();
5135
5136  if (E->isTypeDependent() || E->isValueDependent())
5137    return;
5138
5139  // For conditional operators, we analyze the arguments as if they
5140  // were being fed directly into the output.
5141  if (isa<ConditionalOperator>(E)) {
5142    ConditionalOperator *CO = cast<ConditionalOperator>(E);
5143    CheckConditionalOperator(S, CO, CC, T);
5144    return;
5145  }
5146
5147  // Check implicit argument conversions for function calls.
5148  if (CallExpr *Call = dyn_cast<CallExpr>(E))
5149    CheckImplicitArgumentConversions(S, Call, CC);
5150
5151  // Go ahead and check any implicit conversions we might have skipped.
5152  // The non-canonical typecheck is just an optimization;
5153  // CheckImplicitConversion will filter out dead implicit conversions.
5154  if (E->getType() != T)
5155    CheckImplicitConversion(S, E, T, CC);
5156
5157  // Now continue drilling into this expression.
5158
5159  if (PseudoObjectExpr * POE = dyn_cast<PseudoObjectExpr>(E)) {
5160    if (POE->getResultExpr())
5161      E = POE->getResultExpr();
5162  }
5163
5164  if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E))
5165    return AnalyzeImplicitConversions(S, OVE->getSourceExpr(), CC);
5166
5167  // Skip past explicit casts.
5168  if (isa<ExplicitCastExpr>(E)) {
5169    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
5170    return AnalyzeImplicitConversions(S, E, CC);
5171  }
5172
5173  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5174    // Do a somewhat different check with comparison operators.
5175    if (BO->isComparisonOp())
5176      return AnalyzeComparison(S, BO);
5177
5178    // And with simple assignments.
5179    if (BO->getOpcode() == BO_Assign)
5180      return AnalyzeAssignment(S, BO);
5181  }
5182
5183  // These break the otherwise-useful invariant below.  Fortunately,
5184  // we don't really need to recurse into them, because any internal
5185  // expressions should have been analyzed already when they were
5186  // built into statements.
5187  if (isa<StmtExpr>(E)) return;
5188
5189  // Don't descend into unevaluated contexts.
5190  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
5191
5192  // Now just recurse over the expression's children.
5193  CC = E->getExprLoc();
5194  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
5195  bool IsLogicalOperator = BO && BO->isLogicalOp();
5196  for (Stmt::child_range I = E->children(); I; ++I) {
5197    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
5198    if (!ChildExpr)
5199      continue;
5200
5201    if (IsLogicalOperator &&
5202        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
5203      // Ignore checking string literals that are in logical operators.
5204      continue;
5205    AnalyzeImplicitConversions(S, ChildExpr, CC);
5206  }
5207}
5208
5209} // end anonymous namespace
5210
5211/// Diagnoses "dangerous" implicit conversions within the given
5212/// expression (which is a full expression).  Implements -Wconversion
5213/// and -Wsign-compare.
5214///
5215/// \param CC the "context" location of the implicit conversion, i.e.
5216///   the most location of the syntactic entity requiring the implicit
5217///   conversion
5218void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
5219  // Don't diagnose in unevaluated contexts.
5220  if (isUnevaluatedContext())
5221    return;
5222
5223  // Don't diagnose for value- or type-dependent expressions.
5224  if (E->isTypeDependent() || E->isValueDependent())
5225    return;
5226
5227  // Check for array bounds violations in cases where the check isn't triggered
5228  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
5229  // ArraySubscriptExpr is on the RHS of a variable initialization.
5230  CheckArrayAccess(E);
5231
5232  // This is not the right CC for (e.g.) a variable initialization.
5233  AnalyzeImplicitConversions(*this, E, CC);
5234}
5235
5236/// Diagnose when expression is an integer constant expression and its evaluation
5237/// results in integer overflow
5238void Sema::CheckForIntOverflow (Expr *E) {
5239  if (isa<BinaryOperator>(E->IgnoreParens())) {
5240    llvm::SmallVector<PartialDiagnosticAt, 4> Diags;
5241    E->EvaluateForOverflow(Context, &Diags);
5242  }
5243}
5244
5245namespace {
5246/// \brief Visitor for expressions which looks for unsequenced operations on the
5247/// same object.
5248class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
5249  /// \brief A tree of sequenced regions within an expression. Two regions are
5250  /// unsequenced if one is an ancestor or a descendent of the other. When we
5251  /// finish processing an expression with sequencing, such as a comma
5252  /// expression, we fold its tree nodes into its parent, since they are
5253  /// unsequenced with respect to nodes we will visit later.
5254  class SequenceTree {
5255    struct Value {
5256      explicit Value(unsigned Parent) : Parent(Parent), Merged(false) {}
5257      unsigned Parent : 31;
5258      bool Merged : 1;
5259    };
5260    llvm::SmallVector<Value, 8> Values;
5261
5262  public:
5263    /// \brief A region within an expression which may be sequenced with respect
5264    /// to some other region.
5265    class Seq {
5266      explicit Seq(unsigned N) : Index(N) {}
5267      unsigned Index;
5268      friend class SequenceTree;
5269    public:
5270      Seq() : Index(0) {}
5271    };
5272
5273    SequenceTree() { Values.push_back(Value(0)); }
5274    Seq root() const { return Seq(0); }
5275
5276    /// \brief Create a new sequence of operations, which is an unsequenced
5277    /// subset of \p Parent. This sequence of operations is sequenced with
5278    /// respect to other children of \p Parent.
5279    Seq allocate(Seq Parent) {
5280      Values.push_back(Value(Parent.Index));
5281      return Seq(Values.size() - 1);
5282    }
5283
5284    /// \brief Merge a sequence of operations into its parent.
5285    void merge(Seq S) {
5286      Values[S.Index].Merged = true;
5287    }
5288
5289    /// \brief Determine whether two operations are unsequenced. This operation
5290    /// is asymmetric: \p Cur should be the more recent sequence, and \p Old
5291    /// should have been merged into its parent as appropriate.
5292    bool isUnsequenced(Seq Cur, Seq Old) {
5293      unsigned C = representative(Cur.Index);
5294      unsigned Target = representative(Old.Index);
5295      while (C >= Target) {
5296        if (C == Target)
5297          return true;
5298        C = Values[C].Parent;
5299      }
5300      return false;
5301    }
5302
5303  private:
5304    /// \brief Pick a representative for a sequence.
5305    unsigned representative(unsigned K) {
5306      if (Values[K].Merged)
5307        // Perform path compression as we go.
5308        return Values[K].Parent = representative(Values[K].Parent);
5309      return K;
5310    }
5311  };
5312
5313  /// An object for which we can track unsequenced uses.
5314  typedef NamedDecl *Object;
5315
5316  /// Different flavors of object usage which we track. We only track the
5317  /// least-sequenced usage of each kind.
5318  enum UsageKind {
5319    /// A read of an object. Multiple unsequenced reads are OK.
5320    UK_Use,
5321    /// A modification of an object which is sequenced before the value
5322    /// computation of the expression, such as ++n.
5323    UK_ModAsValue,
5324    /// A modification of an object which is not sequenced before the value
5325    /// computation of the expression, such as n++.
5326    UK_ModAsSideEffect,
5327
5328    UK_Count = UK_ModAsSideEffect + 1
5329  };
5330
5331  struct Usage {
5332    Usage() : Use(0), Seq() {}
5333    Expr *Use;
5334    SequenceTree::Seq Seq;
5335  };
5336
5337  struct UsageInfo {
5338    UsageInfo() : Diagnosed(false) {}
5339    Usage Uses[UK_Count];
5340    /// Have we issued a diagnostic for this variable already?
5341    bool Diagnosed;
5342  };
5343  typedef llvm::SmallDenseMap<Object, UsageInfo, 16> UsageInfoMap;
5344
5345  Sema &SemaRef;
5346  /// Sequenced regions within the expression.
5347  SequenceTree Tree;
5348  /// Declaration modifications and references which we have seen.
5349  UsageInfoMap UsageMap;
5350  /// The region we are currently within.
5351  SequenceTree::Seq Region;
5352  /// Filled in with declarations which were modified as a side-effect
5353  /// (that is, post-increment operations).
5354  llvm::SmallVectorImpl<std::pair<Object, Usage> > *ModAsSideEffect;
5355  /// Expressions to check later. We defer checking these to reduce
5356  /// stack usage.
5357  llvm::SmallVectorImpl<Expr*> &WorkList;
5358
5359  /// RAII object wrapping the visitation of a sequenced subexpression of an
5360  /// expression. At the end of this process, the side-effects of the evaluation
5361  /// become sequenced with respect to the value computation of the result, so
5362  /// we downgrade any UK_ModAsSideEffect within the evaluation to
5363  /// UK_ModAsValue.
5364  struct SequencedSubexpression {
5365    SequencedSubexpression(SequenceChecker &Self)
5366      : Self(Self), OldModAsSideEffect(Self.ModAsSideEffect) {
5367      Self.ModAsSideEffect = &ModAsSideEffect;
5368    }
5369    ~SequencedSubexpression() {
5370      for (unsigned I = 0, E = ModAsSideEffect.size(); I != E; ++I) {
5371        UsageInfo &U = Self.UsageMap[ModAsSideEffect[I].first];
5372        U.Uses[UK_ModAsSideEffect] = ModAsSideEffect[I].second;
5373        Self.addUsage(U, ModAsSideEffect[I].first,
5374                      ModAsSideEffect[I].second.Use, UK_ModAsValue);
5375      }
5376      Self.ModAsSideEffect = OldModAsSideEffect;
5377    }
5378
5379    SequenceChecker &Self;
5380    llvm::SmallVector<std::pair<Object, Usage>, 4> ModAsSideEffect;
5381    llvm::SmallVectorImpl<std::pair<Object, Usage> > *OldModAsSideEffect;
5382  };
5383
5384  /// \brief Find the object which is produced by the specified expression,
5385  /// if any.
5386  Object getObject(Expr *E, bool Mod) const {
5387    E = E->IgnoreParenCasts();
5388    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
5389      if (Mod && (UO->getOpcode() == UO_PreInc || UO->getOpcode() == UO_PreDec))
5390        return getObject(UO->getSubExpr(), Mod);
5391    } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5392      if (BO->getOpcode() == BO_Comma)
5393        return getObject(BO->getRHS(), Mod);
5394      if (Mod && BO->isAssignmentOp())
5395        return getObject(BO->getLHS(), Mod);
5396    } else if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
5397      // FIXME: Check for more interesting cases, like "x.n = ++x.n".
5398      if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenCasts()))
5399        return ME->getMemberDecl();
5400    } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
5401      // FIXME: If this is a reference, map through to its value.
5402      return DRE->getDecl();
5403    return 0;
5404  }
5405
5406  /// \brief Note that an object was modified or used by an expression.
5407  void addUsage(UsageInfo &UI, Object O, Expr *Ref, UsageKind UK) {
5408    Usage &U = UI.Uses[UK];
5409    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq)) {
5410      if (UK == UK_ModAsSideEffect && ModAsSideEffect)
5411        ModAsSideEffect->push_back(std::make_pair(O, U));
5412      U.Use = Ref;
5413      U.Seq = Region;
5414    }
5415  }
5416  /// \brief Check whether a modification or use conflicts with a prior usage.
5417  void checkUsage(Object O, UsageInfo &UI, Expr *Ref, UsageKind OtherKind,
5418                  bool IsModMod) {
5419    if (UI.Diagnosed)
5420      return;
5421
5422    const Usage &U = UI.Uses[OtherKind];
5423    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq))
5424      return;
5425
5426    Expr *Mod = U.Use;
5427    Expr *ModOrUse = Ref;
5428    if (OtherKind == UK_Use)
5429      std::swap(Mod, ModOrUse);
5430
5431    SemaRef.Diag(Mod->getExprLoc(),
5432                 IsModMod ? diag::warn_unsequenced_mod_mod
5433                          : diag::warn_unsequenced_mod_use)
5434      << O << SourceRange(ModOrUse->getExprLoc());
5435    UI.Diagnosed = true;
5436  }
5437
5438  void notePreUse(Object O, Expr *Use) {
5439    UsageInfo &U = UsageMap[O];
5440    // Uses conflict with other modifications.
5441    checkUsage(O, U, Use, UK_ModAsValue, false);
5442  }
5443  void notePostUse(Object O, Expr *Use) {
5444    UsageInfo &U = UsageMap[O];
5445    checkUsage(O, U, Use, UK_ModAsSideEffect, false);
5446    addUsage(U, O, Use, UK_Use);
5447  }
5448
5449  void notePreMod(Object O, Expr *Mod) {
5450    UsageInfo &U = UsageMap[O];
5451    // Modifications conflict with other modifications and with uses.
5452    checkUsage(O, U, Mod, UK_ModAsValue, true);
5453    checkUsage(O, U, Mod, UK_Use, false);
5454  }
5455  void notePostMod(Object O, Expr *Use, UsageKind UK) {
5456    UsageInfo &U = UsageMap[O];
5457    checkUsage(O, U, Use, UK_ModAsSideEffect, true);
5458    addUsage(U, O, Use, UK);
5459  }
5460
5461public:
5462  SequenceChecker(Sema &S, Expr *E,
5463                  llvm::SmallVectorImpl<Expr*> &WorkList)
5464    : EvaluatedExprVisitor<SequenceChecker>(S.Context), SemaRef(S),
5465      Region(Tree.root()), ModAsSideEffect(0), WorkList(WorkList) {
5466    Visit(E);
5467  }
5468
5469  void VisitStmt(Stmt *S) {
5470    // Skip all statements which aren't expressions for now.
5471  }
5472
5473  void VisitExpr(Expr *E) {
5474    // By default, just recurse to evaluated subexpressions.
5475    EvaluatedExprVisitor<SequenceChecker>::VisitStmt(E);
5476  }
5477
5478  void VisitCastExpr(CastExpr *E) {
5479    Object O = Object();
5480    if (E->getCastKind() == CK_LValueToRValue)
5481      O = getObject(E->getSubExpr(), false);
5482
5483    if (O)
5484      notePreUse(O, E);
5485    VisitExpr(E);
5486    if (O)
5487      notePostUse(O, E);
5488  }
5489
5490  void VisitBinComma(BinaryOperator *BO) {
5491    // C++11 [expr.comma]p1:
5492    //   Every value computation and side effect associated with the left
5493    //   expression is sequenced before every value computation and side
5494    //   effect associated with the right expression.
5495    SequenceTree::Seq LHS = Tree.allocate(Region);
5496    SequenceTree::Seq RHS = Tree.allocate(Region);
5497    SequenceTree::Seq OldRegion = Region;
5498
5499    {
5500      SequencedSubexpression SeqLHS(*this);
5501      Region = LHS;
5502      Visit(BO->getLHS());
5503    }
5504
5505    Region = RHS;
5506    Visit(BO->getRHS());
5507
5508    Region = OldRegion;
5509
5510    // Forget that LHS and RHS are sequenced. They are both unsequenced
5511    // with respect to other stuff.
5512    Tree.merge(LHS);
5513    Tree.merge(RHS);
5514  }
5515
5516  void VisitBinAssign(BinaryOperator *BO) {
5517    // The modification is sequenced after the value computation of the LHS
5518    // and RHS, so check it before inspecting the operands and update the
5519    // map afterwards.
5520    Object O = getObject(BO->getLHS(), true);
5521    if (!O)
5522      return VisitExpr(BO);
5523
5524    notePreMod(O, BO);
5525
5526    // C++11 [expr.ass]p7:
5527    //   E1 op= E2 is equivalent to E1 = E1 op E2, except that E1 is evaluated
5528    //   only once.
5529    //
5530    // Therefore, for a compound assignment operator, O is considered used
5531    // everywhere except within the evaluation of E1 itself.
5532    if (isa<CompoundAssignOperator>(BO))
5533      notePreUse(O, BO);
5534
5535    Visit(BO->getLHS());
5536
5537    if (isa<CompoundAssignOperator>(BO))
5538      notePostUse(O, BO);
5539
5540    Visit(BO->getRHS());
5541
5542    notePostMod(O, BO, UK_ModAsValue);
5543  }
5544  void VisitCompoundAssignOperator(CompoundAssignOperator *CAO) {
5545    VisitBinAssign(CAO);
5546  }
5547
5548  void VisitUnaryPreInc(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5549  void VisitUnaryPreDec(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
5550  void VisitUnaryPreIncDec(UnaryOperator *UO) {
5551    Object O = getObject(UO->getSubExpr(), true);
5552    if (!O)
5553      return VisitExpr(UO);
5554
5555    notePreMod(O, UO);
5556    Visit(UO->getSubExpr());
5557    notePostMod(O, UO, UK_ModAsValue);
5558  }
5559
5560  void VisitUnaryPostInc(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5561  void VisitUnaryPostDec(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
5562  void VisitUnaryPostIncDec(UnaryOperator *UO) {
5563    Object O = getObject(UO->getSubExpr(), true);
5564    if (!O)
5565      return VisitExpr(UO);
5566
5567    notePreMod(O, UO);
5568    Visit(UO->getSubExpr());
5569    notePostMod(O, UO, UK_ModAsSideEffect);
5570  }
5571
5572  /// Don't visit the RHS of '&&' or '||' if it might not be evaluated.
5573  void VisitBinLOr(BinaryOperator *BO) {
5574    // The side-effects of the LHS of an '&&' are sequenced before the
5575    // value computation of the RHS, and hence before the value computation
5576    // of the '&&' itself, unless the LHS evaluates to zero. We treat them
5577    // as if they were unconditionally sequenced.
5578    {
5579      SequencedSubexpression Sequenced(*this);
5580      Visit(BO->getLHS());
5581    }
5582
5583    bool Result;
5584    if (!BO->getLHS()->isValueDependent() &&
5585        BO->getLHS()->EvaluateAsBooleanCondition(Result, SemaRef.Context)) {
5586      if (!Result)
5587        Visit(BO->getRHS());
5588    } else {
5589      // Check for unsequenced operations in the RHS, treating it as an
5590      // entirely separate evaluation.
5591      //
5592      // FIXME: If there are operations in the RHS which are unsequenced
5593      // with respect to operations outside the RHS, and those operations
5594      // are unconditionally evaluated, diagnose them.
5595      WorkList.push_back(BO->getRHS());
5596    }
5597  }
5598  void VisitBinLAnd(BinaryOperator *BO) {
5599    {
5600      SequencedSubexpression Sequenced(*this);
5601      Visit(BO->getLHS());
5602    }
5603
5604    bool Result;
5605    if (!BO->getLHS()->isValueDependent() &&
5606        BO->getLHS()->EvaluateAsBooleanCondition(Result, SemaRef.Context)) {
5607      if (Result)
5608        Visit(BO->getRHS());
5609    } else {
5610      WorkList.push_back(BO->getRHS());
5611    }
5612  }
5613
5614  // Only visit the condition, unless we can be sure which subexpression will
5615  // be chosen.
5616  void VisitAbstractConditionalOperator(AbstractConditionalOperator *CO) {
5617    SequencedSubexpression Sequenced(*this);
5618    Visit(CO->getCond());
5619
5620    bool Result;
5621    if (!CO->getCond()->isValueDependent() &&
5622        CO->getCond()->EvaluateAsBooleanCondition(Result, SemaRef.Context))
5623      Visit(Result ? CO->getTrueExpr() : CO->getFalseExpr());
5624    else {
5625      WorkList.push_back(CO->getTrueExpr());
5626      WorkList.push_back(CO->getFalseExpr());
5627    }
5628  }
5629
5630  void VisitCXXConstructExpr(CXXConstructExpr *CCE) {
5631    if (!CCE->isListInitialization())
5632      return VisitExpr(CCE);
5633
5634    // In C++11, list initializations are sequenced.
5635    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5636    SequenceTree::Seq Parent = Region;
5637    for (CXXConstructExpr::arg_iterator I = CCE->arg_begin(),
5638                                        E = CCE->arg_end();
5639         I != E; ++I) {
5640      Region = Tree.allocate(Parent);
5641      Elts.push_back(Region);
5642      Visit(*I);
5643    }
5644
5645    // Forget that the initializers are sequenced.
5646    Region = Parent;
5647    for (unsigned I = 0; I < Elts.size(); ++I)
5648      Tree.merge(Elts[I]);
5649  }
5650
5651  void VisitInitListExpr(InitListExpr *ILE) {
5652    if (!SemaRef.getLangOpts().CPlusPlus11)
5653      return VisitExpr(ILE);
5654
5655    // In C++11, list initializations are sequenced.
5656    llvm::SmallVector<SequenceTree::Seq, 32> Elts;
5657    SequenceTree::Seq Parent = Region;
5658    for (unsigned I = 0; I < ILE->getNumInits(); ++I) {
5659      Expr *E = ILE->getInit(I);
5660      if (!E) continue;
5661      Region = Tree.allocate(Parent);
5662      Elts.push_back(Region);
5663      Visit(E);
5664    }
5665
5666    // Forget that the initializers are sequenced.
5667    Region = Parent;
5668    for (unsigned I = 0; I < Elts.size(); ++I)
5669      Tree.merge(Elts[I]);
5670  }
5671};
5672}
5673
5674void Sema::CheckUnsequencedOperations(Expr *E) {
5675  llvm::SmallVector<Expr*, 8> WorkList;
5676  WorkList.push_back(E);
5677  while (!WorkList.empty()) {
5678    Expr *Item = WorkList.back();
5679    WorkList.pop_back();
5680    SequenceChecker(*this, Item, WorkList);
5681  }
5682}
5683
5684void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
5685                              bool IsConstexpr) {
5686  CheckImplicitConversions(E, CheckLoc);
5687  CheckUnsequencedOperations(E);
5688  if (!IsConstexpr && !E->isValueDependent())
5689    CheckForIntOverflow(E);
5690}
5691
5692void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
5693                                       FieldDecl *BitField,
5694                                       Expr *Init) {
5695  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
5696}
5697
5698/// CheckParmsForFunctionDef - Check that the parameters of the given
5699/// function are appropriate for the definition of a function. This
5700/// takes care of any checks that cannot be performed on the
5701/// declaration itself, e.g., that the types of each of the function
5702/// parameters are complete.
5703bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
5704                                    bool CheckParameterNames) {
5705  bool HasInvalidParm = false;
5706  for (; P != PEnd; ++P) {
5707    ParmVarDecl *Param = *P;
5708
5709    // C99 6.7.5.3p4: the parameters in a parameter type list in a
5710    // function declarator that is part of a function definition of
5711    // that function shall not have incomplete type.
5712    //
5713    // This is also C++ [dcl.fct]p6.
5714    if (!Param->isInvalidDecl() &&
5715        RequireCompleteType(Param->getLocation(), Param->getType(),
5716                            diag::err_typecheck_decl_incomplete_type)) {
5717      Param->setInvalidDecl();
5718      HasInvalidParm = true;
5719    }
5720
5721    // C99 6.9.1p5: If the declarator includes a parameter type list, the
5722    // declaration of each parameter shall include an identifier.
5723    if (CheckParameterNames &&
5724        Param->getIdentifier() == 0 &&
5725        !Param->isImplicit() &&
5726        !getLangOpts().CPlusPlus)
5727      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
5728
5729    // C99 6.7.5.3p12:
5730    //   If the function declarator is not part of a definition of that
5731    //   function, parameters may have incomplete type and may use the [*]
5732    //   notation in their sequences of declarator specifiers to specify
5733    //   variable length array types.
5734    QualType PType = Param->getOriginalType();
5735    while (const ArrayType *AT = Context.getAsArrayType(PType)) {
5736      if (AT->getSizeModifier() == ArrayType::Star) {
5737        // FIXME: This diagnostic should point the '[*]' if source-location
5738        // information is added for it.
5739        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
5740        break;
5741      }
5742      PType= AT->getElementType();
5743    }
5744  }
5745
5746  return HasInvalidParm;
5747}
5748
5749/// CheckCastAlign - Implements -Wcast-align, which warns when a
5750/// pointer cast increases the alignment requirements.
5751void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
5752  // This is actually a lot of work to potentially be doing on every
5753  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
5754  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
5755                                          TRange.getBegin())
5756        == DiagnosticsEngine::Ignored)
5757    return;
5758
5759  // Ignore dependent types.
5760  if (T->isDependentType() || Op->getType()->isDependentType())
5761    return;
5762
5763  // Require that the destination be a pointer type.
5764  const PointerType *DestPtr = T->getAs<PointerType>();
5765  if (!DestPtr) return;
5766
5767  // If the destination has alignment 1, we're done.
5768  QualType DestPointee = DestPtr->getPointeeType();
5769  if (DestPointee->isIncompleteType()) return;
5770  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
5771  if (DestAlign.isOne()) return;
5772
5773  // Require that the source be a pointer type.
5774  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
5775  if (!SrcPtr) return;
5776  QualType SrcPointee = SrcPtr->getPointeeType();
5777
5778  // Whitelist casts from cv void*.  We already implicitly
5779  // whitelisted casts to cv void*, since they have alignment 1.
5780  // Also whitelist casts involving incomplete types, which implicitly
5781  // includes 'void'.
5782  if (SrcPointee->isIncompleteType()) return;
5783
5784  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
5785  if (SrcAlign >= DestAlign) return;
5786
5787  Diag(TRange.getBegin(), diag::warn_cast_align)
5788    << Op->getType() << T
5789    << static_cast<unsigned>(SrcAlign.getQuantity())
5790    << static_cast<unsigned>(DestAlign.getQuantity())
5791    << TRange << Op->getSourceRange();
5792}
5793
5794static const Type* getElementType(const Expr *BaseExpr) {
5795  const Type* EltType = BaseExpr->getType().getTypePtr();
5796  if (EltType->isAnyPointerType())
5797    return EltType->getPointeeType().getTypePtr();
5798  else if (EltType->isArrayType())
5799    return EltType->getBaseElementTypeUnsafe();
5800  return EltType;
5801}
5802
5803/// \brief Check whether this array fits the idiom of a size-one tail padded
5804/// array member of a struct.
5805///
5806/// We avoid emitting out-of-bounds access warnings for such arrays as they are
5807/// commonly used to emulate flexible arrays in C89 code.
5808static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
5809                                    const NamedDecl *ND) {
5810  if (Size != 1 || !ND) return false;
5811
5812  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
5813  if (!FD) return false;
5814
5815  // Don't consider sizes resulting from macro expansions or template argument
5816  // substitution to form C89 tail-padded arrays.
5817
5818  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
5819  while (TInfo) {
5820    TypeLoc TL = TInfo->getTypeLoc();
5821    // Look through typedefs.
5822    if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
5823      const TypedefNameDecl *TDL = TTL.getTypedefNameDecl();
5824      TInfo = TDL->getTypeSourceInfo();
5825      continue;
5826    }
5827    if (ConstantArrayTypeLoc CTL = TL.getAs<ConstantArrayTypeLoc>()) {
5828      const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
5829      if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
5830        return false;
5831    }
5832    break;
5833  }
5834
5835  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
5836  if (!RD) return false;
5837  if (RD->isUnion()) return false;
5838  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
5839    if (!CRD->isStandardLayout()) return false;
5840  }
5841
5842  // See if this is the last field decl in the record.
5843  const Decl *D = FD;
5844  while ((D = D->getNextDeclInContext()))
5845    if (isa<FieldDecl>(D))
5846      return false;
5847  return true;
5848}
5849
5850void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
5851                            const ArraySubscriptExpr *ASE,
5852                            bool AllowOnePastEnd, bool IndexNegated) {
5853  IndexExpr = IndexExpr->IgnoreParenImpCasts();
5854  if (IndexExpr->isValueDependent())
5855    return;
5856
5857  const Type *EffectiveType = getElementType(BaseExpr);
5858  BaseExpr = BaseExpr->IgnoreParenCasts();
5859  const ConstantArrayType *ArrayTy =
5860    Context.getAsConstantArrayType(BaseExpr->getType());
5861  if (!ArrayTy)
5862    return;
5863
5864  llvm::APSInt index;
5865  if (!IndexExpr->EvaluateAsInt(index, Context))
5866    return;
5867  if (IndexNegated)
5868    index = -index;
5869
5870  const NamedDecl *ND = NULL;
5871  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5872    ND = dyn_cast<NamedDecl>(DRE->getDecl());
5873  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5874    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5875
5876  if (index.isUnsigned() || !index.isNegative()) {
5877    llvm::APInt size = ArrayTy->getSize();
5878    if (!size.isStrictlyPositive())
5879      return;
5880
5881    const Type* BaseType = getElementType(BaseExpr);
5882    if (BaseType != EffectiveType) {
5883      // Make sure we're comparing apples to apples when comparing index to size
5884      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
5885      uint64_t array_typesize = Context.getTypeSize(BaseType);
5886      // Handle ptrarith_typesize being zero, such as when casting to void*
5887      if (!ptrarith_typesize) ptrarith_typesize = 1;
5888      if (ptrarith_typesize != array_typesize) {
5889        // There's a cast to a different size type involved
5890        uint64_t ratio = array_typesize / ptrarith_typesize;
5891        // TODO: Be smarter about handling cases where array_typesize is not a
5892        // multiple of ptrarith_typesize
5893        if (ptrarith_typesize * ratio == array_typesize)
5894          size *= llvm::APInt(size.getBitWidth(), ratio);
5895      }
5896    }
5897
5898    if (size.getBitWidth() > index.getBitWidth())
5899      index = index.zext(size.getBitWidth());
5900    else if (size.getBitWidth() < index.getBitWidth())
5901      size = size.zext(index.getBitWidth());
5902
5903    // For array subscripting the index must be less than size, but for pointer
5904    // arithmetic also allow the index (offset) to be equal to size since
5905    // computing the next address after the end of the array is legal and
5906    // commonly done e.g. in C++ iterators and range-based for loops.
5907    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
5908      return;
5909
5910    // Also don't warn for arrays of size 1 which are members of some
5911    // structure. These are often used to approximate flexible arrays in C89
5912    // code.
5913    if (IsTailPaddedMemberArray(*this, size, ND))
5914      return;
5915
5916    // Suppress the warning if the subscript expression (as identified by the
5917    // ']' location) and the index expression are both from macro expansions
5918    // within a system header.
5919    if (ASE) {
5920      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
5921          ASE->getRBracketLoc());
5922      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
5923        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
5924            IndexExpr->getLocStart());
5925        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
5926          return;
5927      }
5928    }
5929
5930    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
5931    if (ASE)
5932      DiagID = diag::warn_array_index_exceeds_bounds;
5933
5934    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5935                        PDiag(DiagID) << index.toString(10, true)
5936                          << size.toString(10, true)
5937                          << (unsigned)size.getLimitedValue(~0U)
5938                          << IndexExpr->getSourceRange());
5939  } else {
5940    unsigned DiagID = diag::warn_array_index_precedes_bounds;
5941    if (!ASE) {
5942      DiagID = diag::warn_ptr_arith_precedes_bounds;
5943      if (index.isNegative()) index = -index;
5944    }
5945
5946    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
5947                        PDiag(DiagID) << index.toString(10, true)
5948                          << IndexExpr->getSourceRange());
5949  }
5950
5951  if (!ND) {
5952    // Try harder to find a NamedDecl to point at in the note.
5953    while (const ArraySubscriptExpr *ASE =
5954           dyn_cast<ArraySubscriptExpr>(BaseExpr))
5955      BaseExpr = ASE->getBase()->IgnoreParenCasts();
5956    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5957      ND = dyn_cast<NamedDecl>(DRE->getDecl());
5958    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5959      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5960  }
5961
5962  if (ND)
5963    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
5964                        PDiag(diag::note_array_index_out_of_bounds)
5965                          << ND->getDeclName());
5966}
5967
5968void Sema::CheckArrayAccess(const Expr *expr) {
5969  int AllowOnePastEnd = 0;
5970  while (expr) {
5971    expr = expr->IgnoreParenImpCasts();
5972    switch (expr->getStmtClass()) {
5973      case Stmt::ArraySubscriptExprClass: {
5974        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
5975        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
5976                         AllowOnePastEnd > 0);
5977        return;
5978      }
5979      case Stmt::UnaryOperatorClass: {
5980        // Only unwrap the * and & unary operators
5981        const UnaryOperator *UO = cast<UnaryOperator>(expr);
5982        expr = UO->getSubExpr();
5983        switch (UO->getOpcode()) {
5984          case UO_AddrOf:
5985            AllowOnePastEnd++;
5986            break;
5987          case UO_Deref:
5988            AllowOnePastEnd--;
5989            break;
5990          default:
5991            return;
5992        }
5993        break;
5994      }
5995      case Stmt::ConditionalOperatorClass: {
5996        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
5997        if (const Expr *lhs = cond->getLHS())
5998          CheckArrayAccess(lhs);
5999        if (const Expr *rhs = cond->getRHS())
6000          CheckArrayAccess(rhs);
6001        return;
6002      }
6003      default:
6004        return;
6005    }
6006  }
6007}
6008
6009//===--- CHECK: Objective-C retain cycles ----------------------------------//
6010
6011namespace {
6012  struct RetainCycleOwner {
6013    RetainCycleOwner() : Variable(0), Indirect(false) {}
6014    VarDecl *Variable;
6015    SourceRange Range;
6016    SourceLocation Loc;
6017    bool Indirect;
6018
6019    void setLocsFrom(Expr *e) {
6020      Loc = e->getExprLoc();
6021      Range = e->getSourceRange();
6022    }
6023  };
6024}
6025
6026/// Consider whether capturing the given variable can possibly lead to
6027/// a retain cycle.
6028static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
6029  // In ARC, it's captured strongly iff the variable has __strong
6030  // lifetime.  In MRR, it's captured strongly if the variable is
6031  // __block and has an appropriate type.
6032  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6033    return false;
6034
6035  owner.Variable = var;
6036  if (ref)
6037    owner.setLocsFrom(ref);
6038  return true;
6039}
6040
6041static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
6042  while (true) {
6043    e = e->IgnoreParens();
6044    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
6045      switch (cast->getCastKind()) {
6046      case CK_BitCast:
6047      case CK_LValueBitCast:
6048      case CK_LValueToRValue:
6049      case CK_ARCReclaimReturnedObject:
6050        e = cast->getSubExpr();
6051        continue;
6052
6053      default:
6054        return false;
6055      }
6056    }
6057
6058    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
6059      ObjCIvarDecl *ivar = ref->getDecl();
6060      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
6061        return false;
6062
6063      // Try to find a retain cycle in the base.
6064      if (!findRetainCycleOwner(S, ref->getBase(), owner))
6065        return false;
6066
6067      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
6068      owner.Indirect = true;
6069      return true;
6070    }
6071
6072    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
6073      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
6074      if (!var) return false;
6075      return considerVariable(var, ref, owner);
6076    }
6077
6078    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
6079      if (member->isArrow()) return false;
6080
6081      // Don't count this as an indirect ownership.
6082      e = member->getBase();
6083      continue;
6084    }
6085
6086    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
6087      // Only pay attention to pseudo-objects on property references.
6088      ObjCPropertyRefExpr *pre
6089        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
6090                                              ->IgnoreParens());
6091      if (!pre) return false;
6092      if (pre->isImplicitProperty()) return false;
6093      ObjCPropertyDecl *property = pre->getExplicitProperty();
6094      if (!property->isRetaining() &&
6095          !(property->getPropertyIvarDecl() &&
6096            property->getPropertyIvarDecl()->getType()
6097              .getObjCLifetime() == Qualifiers::OCL_Strong))
6098          return false;
6099
6100      owner.Indirect = true;
6101      if (pre->isSuperReceiver()) {
6102        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
6103        if (!owner.Variable)
6104          return false;
6105        owner.Loc = pre->getLocation();
6106        owner.Range = pre->getSourceRange();
6107        return true;
6108      }
6109      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
6110                              ->getSourceExpr());
6111      continue;
6112    }
6113
6114    // Array ivars?
6115
6116    return false;
6117  }
6118}
6119
6120namespace {
6121  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
6122    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
6123      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
6124        Variable(variable), Capturer(0) {}
6125
6126    VarDecl *Variable;
6127    Expr *Capturer;
6128
6129    void VisitDeclRefExpr(DeclRefExpr *ref) {
6130      if (ref->getDecl() == Variable && !Capturer)
6131        Capturer = ref;
6132    }
6133
6134    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
6135      if (Capturer) return;
6136      Visit(ref->getBase());
6137      if (Capturer && ref->isFreeIvar())
6138        Capturer = ref;
6139    }
6140
6141    void VisitBlockExpr(BlockExpr *block) {
6142      // Look inside nested blocks
6143      if (block->getBlockDecl()->capturesVariable(Variable))
6144        Visit(block->getBlockDecl()->getBody());
6145    }
6146
6147    void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
6148      if (Capturer) return;
6149      if (OVE->getSourceExpr())
6150        Visit(OVE->getSourceExpr());
6151    }
6152  };
6153}
6154
6155/// Check whether the given argument is a block which captures a
6156/// variable.
6157static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
6158  assert(owner.Variable && owner.Loc.isValid());
6159
6160  e = e->IgnoreParenCasts();
6161
6162  // Look through [^{...} copy] and Block_copy(^{...}).
6163  if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
6164    Selector Cmd = ME->getSelector();
6165    if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
6166      e = ME->getInstanceReceiver();
6167      if (!e)
6168        return 0;
6169      e = e->IgnoreParenCasts();
6170    }
6171  } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
6172    if (CE->getNumArgs() == 1) {
6173      FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
6174      if (Fn) {
6175        const IdentifierInfo *FnI = Fn->getIdentifier();
6176        if (FnI && FnI->isStr("_Block_copy")) {
6177          e = CE->getArg(0)->IgnoreParenCasts();
6178        }
6179      }
6180    }
6181  }
6182
6183  BlockExpr *block = dyn_cast<BlockExpr>(e);
6184  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
6185    return 0;
6186
6187  FindCaptureVisitor visitor(S.Context, owner.Variable);
6188  visitor.Visit(block->getBlockDecl()->getBody());
6189  return visitor.Capturer;
6190}
6191
6192static void diagnoseRetainCycle(Sema &S, Expr *capturer,
6193                                RetainCycleOwner &owner) {
6194  assert(capturer);
6195  assert(owner.Variable && owner.Loc.isValid());
6196
6197  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
6198    << owner.Variable << capturer->getSourceRange();
6199  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
6200    << owner.Indirect << owner.Range;
6201}
6202
6203/// Check for a keyword selector that starts with the word 'add' or
6204/// 'set'.
6205static bool isSetterLikeSelector(Selector sel) {
6206  if (sel.isUnarySelector()) return false;
6207
6208  StringRef str = sel.getNameForSlot(0);
6209  while (!str.empty() && str.front() == '_') str = str.substr(1);
6210  if (str.startswith("set"))
6211    str = str.substr(3);
6212  else if (str.startswith("add")) {
6213    // Specially whitelist 'addOperationWithBlock:'.
6214    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
6215      return false;
6216    str = str.substr(3);
6217  }
6218  else
6219    return false;
6220
6221  if (str.empty()) return true;
6222  return !isLowercase(str.front());
6223}
6224
6225/// Check a message send to see if it's likely to cause a retain cycle.
6226void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
6227  // Only check instance methods whose selector looks like a setter.
6228  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
6229    return;
6230
6231  // Try to find a variable that the receiver is strongly owned by.
6232  RetainCycleOwner owner;
6233  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
6234    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
6235      return;
6236  } else {
6237    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
6238    owner.Variable = getCurMethodDecl()->getSelfDecl();
6239    owner.Loc = msg->getSuperLoc();
6240    owner.Range = msg->getSuperLoc();
6241  }
6242
6243  // Check whether the receiver is captured by any of the arguments.
6244  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
6245    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
6246      return diagnoseRetainCycle(*this, capturer, owner);
6247}
6248
6249/// Check a property assign to see if it's likely to cause a retain cycle.
6250void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
6251  RetainCycleOwner owner;
6252  if (!findRetainCycleOwner(*this, receiver, owner))
6253    return;
6254
6255  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
6256    diagnoseRetainCycle(*this, capturer, owner);
6257}
6258
6259void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
6260  RetainCycleOwner Owner;
6261  if (!considerVariable(Var, /*DeclRefExpr=*/0, Owner))
6262    return;
6263
6264  // Because we don't have an expression for the variable, we have to set the
6265  // location explicitly here.
6266  Owner.Loc = Var->getLocation();
6267  Owner.Range = Var->getSourceRange();
6268
6269  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
6270    diagnoseRetainCycle(*this, Capturer, Owner);
6271}
6272
6273static bool checkUnsafeAssignLiteral(Sema &S, SourceLocation Loc,
6274                                     Expr *RHS, bool isProperty) {
6275  // Check if RHS is an Objective-C object literal, which also can get
6276  // immediately zapped in a weak reference.  Note that we explicitly
6277  // allow ObjCStringLiterals, since those are designed to never really die.
6278  RHS = RHS->IgnoreParenImpCasts();
6279
6280  // This enum needs to match with the 'select' in
6281  // warn_objc_arc_literal_assign (off-by-1).
6282  Sema::ObjCLiteralKind Kind = S.CheckLiteralKind(RHS);
6283  if (Kind == Sema::LK_String || Kind == Sema::LK_None)
6284    return false;
6285
6286  S.Diag(Loc, diag::warn_arc_literal_assign)
6287    << (unsigned) Kind
6288    << (isProperty ? 0 : 1)
6289    << RHS->getSourceRange();
6290
6291  return true;
6292}
6293
6294static bool checkUnsafeAssignObject(Sema &S, SourceLocation Loc,
6295                                    Qualifiers::ObjCLifetime LT,
6296                                    Expr *RHS, bool isProperty) {
6297  // Strip off any implicit cast added to get to the one ARC-specific.
6298  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6299    if (cast->getCastKind() == CK_ARCConsumeObject) {
6300      S.Diag(Loc, diag::warn_arc_retained_assign)
6301        << (LT == Qualifiers::OCL_ExplicitNone)
6302        << (isProperty ? 0 : 1)
6303        << RHS->getSourceRange();
6304      return true;
6305    }
6306    RHS = cast->getSubExpr();
6307  }
6308
6309  if (LT == Qualifiers::OCL_Weak &&
6310      checkUnsafeAssignLiteral(S, Loc, RHS, isProperty))
6311    return true;
6312
6313  return false;
6314}
6315
6316bool Sema::checkUnsafeAssigns(SourceLocation Loc,
6317                              QualType LHS, Expr *RHS) {
6318  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
6319
6320  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
6321    return false;
6322
6323  if (checkUnsafeAssignObject(*this, Loc, LT, RHS, false))
6324    return true;
6325
6326  return false;
6327}
6328
6329void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
6330                              Expr *LHS, Expr *RHS) {
6331  QualType LHSType;
6332  // PropertyRef on LHS type need be directly obtained from
6333  // its declaration as it has a PsuedoType.
6334  ObjCPropertyRefExpr *PRE
6335    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
6336  if (PRE && !PRE->isImplicitProperty()) {
6337    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6338    if (PD)
6339      LHSType = PD->getType();
6340  }
6341
6342  if (LHSType.isNull())
6343    LHSType = LHS->getType();
6344
6345  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
6346
6347  if (LT == Qualifiers::OCL_Weak) {
6348    DiagnosticsEngine::Level Level =
6349      Diags.getDiagnosticLevel(diag::warn_arc_repeated_use_of_weak, Loc);
6350    if (Level != DiagnosticsEngine::Ignored)
6351      getCurFunction()->markSafeWeakUse(LHS);
6352  }
6353
6354  if (checkUnsafeAssigns(Loc, LHSType, RHS))
6355    return;
6356
6357  // FIXME. Check for other life times.
6358  if (LT != Qualifiers::OCL_None)
6359    return;
6360
6361  if (PRE) {
6362    if (PRE->isImplicitProperty())
6363      return;
6364    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
6365    if (!PD)
6366      return;
6367
6368    unsigned Attributes = PD->getPropertyAttributes();
6369    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
6370      // when 'assign' attribute was not explicitly specified
6371      // by user, ignore it and rely on property type itself
6372      // for lifetime info.
6373      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
6374      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
6375          LHSType->isObjCRetainableType())
6376        return;
6377
6378      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
6379        if (cast->getCastKind() == CK_ARCConsumeObject) {
6380          Diag(Loc, diag::warn_arc_retained_property_assign)
6381          << RHS->getSourceRange();
6382          return;
6383        }
6384        RHS = cast->getSubExpr();
6385      }
6386    }
6387    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
6388      if (checkUnsafeAssignObject(*this, Loc, Qualifiers::OCL_Weak, RHS, true))
6389        return;
6390    }
6391  }
6392}
6393
6394//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
6395
6396namespace {
6397bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
6398                                 SourceLocation StmtLoc,
6399                                 const NullStmt *Body) {
6400  // Do not warn if the body is a macro that expands to nothing, e.g:
6401  //
6402  // #define CALL(x)
6403  // if (condition)
6404  //   CALL(0);
6405  //
6406  if (Body->hasLeadingEmptyMacro())
6407    return false;
6408
6409  // Get line numbers of statement and body.
6410  bool StmtLineInvalid;
6411  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
6412                                                      &StmtLineInvalid);
6413  if (StmtLineInvalid)
6414    return false;
6415
6416  bool BodyLineInvalid;
6417  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
6418                                                      &BodyLineInvalid);
6419  if (BodyLineInvalid)
6420    return false;
6421
6422  // Warn if null statement and body are on the same line.
6423  if (StmtLine != BodyLine)
6424    return false;
6425
6426  return true;
6427}
6428} // Unnamed namespace
6429
6430void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
6431                                 const Stmt *Body,
6432                                 unsigned DiagID) {
6433  // Since this is a syntactic check, don't emit diagnostic for template
6434  // instantiations, this just adds noise.
6435  if (CurrentInstantiationScope)
6436    return;
6437
6438  // The body should be a null statement.
6439  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6440  if (!NBody)
6441    return;
6442
6443  // Do the usual checks.
6444  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6445    return;
6446
6447  Diag(NBody->getSemiLoc(), DiagID);
6448  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6449}
6450
6451void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
6452                                 const Stmt *PossibleBody) {
6453  assert(!CurrentInstantiationScope); // Ensured by caller
6454
6455  SourceLocation StmtLoc;
6456  const Stmt *Body;
6457  unsigned DiagID;
6458  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
6459    StmtLoc = FS->getRParenLoc();
6460    Body = FS->getBody();
6461    DiagID = diag::warn_empty_for_body;
6462  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
6463    StmtLoc = WS->getCond()->getSourceRange().getEnd();
6464    Body = WS->getBody();
6465    DiagID = diag::warn_empty_while_body;
6466  } else
6467    return; // Neither `for' nor `while'.
6468
6469  // The body should be a null statement.
6470  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
6471  if (!NBody)
6472    return;
6473
6474  // Skip expensive checks if diagnostic is disabled.
6475  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
6476          DiagnosticsEngine::Ignored)
6477    return;
6478
6479  // Do the usual checks.
6480  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
6481    return;
6482
6483  // `for(...);' and `while(...);' are popular idioms, so in order to keep
6484  // noise level low, emit diagnostics only if for/while is followed by a
6485  // CompoundStmt, e.g.:
6486  //    for (int i = 0; i < n; i++);
6487  //    {
6488  //      a(i);
6489  //    }
6490  // or if for/while is followed by a statement with more indentation
6491  // than for/while itself:
6492  //    for (int i = 0; i < n; i++);
6493  //      a(i);
6494  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
6495  if (!ProbableTypo) {
6496    bool BodyColInvalid;
6497    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
6498                             PossibleBody->getLocStart(),
6499                             &BodyColInvalid);
6500    if (BodyColInvalid)
6501      return;
6502
6503    bool StmtColInvalid;
6504    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
6505                             S->getLocStart(),
6506                             &StmtColInvalid);
6507    if (StmtColInvalid)
6508      return;
6509
6510    if (BodyCol > StmtCol)
6511      ProbableTypo = true;
6512  }
6513
6514  if (ProbableTypo) {
6515    Diag(NBody->getSemiLoc(), DiagID);
6516    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
6517  }
6518}
6519
6520//===--- Layout compatibility ----------------------------------------------//
6521
6522namespace {
6523
6524bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
6525
6526/// \brief Check if two enumeration types are layout-compatible.
6527bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
6528  // C++11 [dcl.enum] p8:
6529  // Two enumeration types are layout-compatible if they have the same
6530  // underlying type.
6531  return ED1->isComplete() && ED2->isComplete() &&
6532         C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
6533}
6534
6535/// \brief Check if two fields are layout-compatible.
6536bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
6537  if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
6538    return false;
6539
6540  if (Field1->isBitField() != Field2->isBitField())
6541    return false;
6542
6543  if (Field1->isBitField()) {
6544    // Make sure that the bit-fields are the same length.
6545    unsigned Bits1 = Field1->getBitWidthValue(C);
6546    unsigned Bits2 = Field2->getBitWidthValue(C);
6547
6548    if (Bits1 != Bits2)
6549      return false;
6550  }
6551
6552  return true;
6553}
6554
6555/// \brief Check if two standard-layout structs are layout-compatible.
6556/// (C++11 [class.mem] p17)
6557bool isLayoutCompatibleStruct(ASTContext &C,
6558                              RecordDecl *RD1,
6559                              RecordDecl *RD2) {
6560  // If both records are C++ classes, check that base classes match.
6561  if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
6562    // If one of records is a CXXRecordDecl we are in C++ mode,
6563    // thus the other one is a CXXRecordDecl, too.
6564    const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
6565    // Check number of base classes.
6566    if (D1CXX->getNumBases() != D2CXX->getNumBases())
6567      return false;
6568
6569    // Check the base classes.
6570    for (CXXRecordDecl::base_class_const_iterator
6571               Base1 = D1CXX->bases_begin(),
6572           BaseEnd1 = D1CXX->bases_end(),
6573              Base2 = D2CXX->bases_begin();
6574         Base1 != BaseEnd1;
6575         ++Base1, ++Base2) {
6576      if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
6577        return false;
6578    }
6579  } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
6580    // If only RD2 is a C++ class, it should have zero base classes.
6581    if (D2CXX->getNumBases() > 0)
6582      return false;
6583  }
6584
6585  // Check the fields.
6586  RecordDecl::field_iterator Field2 = RD2->field_begin(),
6587                             Field2End = RD2->field_end(),
6588                             Field1 = RD1->field_begin(),
6589                             Field1End = RD1->field_end();
6590  for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
6591    if (!isLayoutCompatible(C, *Field1, *Field2))
6592      return false;
6593  }
6594  if (Field1 != Field1End || Field2 != Field2End)
6595    return false;
6596
6597  return true;
6598}
6599
6600/// \brief Check if two standard-layout unions are layout-compatible.
6601/// (C++11 [class.mem] p18)
6602bool isLayoutCompatibleUnion(ASTContext &C,
6603                             RecordDecl *RD1,
6604                             RecordDecl *RD2) {
6605  llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
6606  for (RecordDecl::field_iterator Field2 = RD2->field_begin(),
6607                                  Field2End = RD2->field_end();
6608       Field2 != Field2End; ++Field2) {
6609    UnmatchedFields.insert(*Field2);
6610  }
6611
6612  for (RecordDecl::field_iterator Field1 = RD1->field_begin(),
6613                                  Field1End = RD1->field_end();
6614       Field1 != Field1End; ++Field1) {
6615    llvm::SmallPtrSet<FieldDecl *, 8>::iterator
6616        I = UnmatchedFields.begin(),
6617        E = UnmatchedFields.end();
6618
6619    for ( ; I != E; ++I) {
6620      if (isLayoutCompatible(C, *Field1, *I)) {
6621        bool Result = UnmatchedFields.erase(*I);
6622        (void) Result;
6623        assert(Result);
6624        break;
6625      }
6626    }
6627    if (I == E)
6628      return false;
6629  }
6630
6631  return UnmatchedFields.empty();
6632}
6633
6634bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
6635  if (RD1->isUnion() != RD2->isUnion())
6636    return false;
6637
6638  if (RD1->isUnion())
6639    return isLayoutCompatibleUnion(C, RD1, RD2);
6640  else
6641    return isLayoutCompatibleStruct(C, RD1, RD2);
6642}
6643
6644/// \brief Check if two types are layout-compatible in C++11 sense.
6645bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
6646  if (T1.isNull() || T2.isNull())
6647    return false;
6648
6649  // C++11 [basic.types] p11:
6650  // If two types T1 and T2 are the same type, then T1 and T2 are
6651  // layout-compatible types.
6652  if (C.hasSameType(T1, T2))
6653    return true;
6654
6655  T1 = T1.getCanonicalType().getUnqualifiedType();
6656  T2 = T2.getCanonicalType().getUnqualifiedType();
6657
6658  const Type::TypeClass TC1 = T1->getTypeClass();
6659  const Type::TypeClass TC2 = T2->getTypeClass();
6660
6661  if (TC1 != TC2)
6662    return false;
6663
6664  if (TC1 == Type::Enum) {
6665    return isLayoutCompatible(C,
6666                              cast<EnumType>(T1)->getDecl(),
6667                              cast<EnumType>(T2)->getDecl());
6668  } else if (TC1 == Type::Record) {
6669    if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
6670      return false;
6671
6672    return isLayoutCompatible(C,
6673                              cast<RecordType>(T1)->getDecl(),
6674                              cast<RecordType>(T2)->getDecl());
6675  }
6676
6677  return false;
6678}
6679}
6680
6681//===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
6682
6683namespace {
6684/// \brief Given a type tag expression find the type tag itself.
6685///
6686/// \param TypeExpr Type tag expression, as it appears in user's code.
6687///
6688/// \param VD Declaration of an identifier that appears in a type tag.
6689///
6690/// \param MagicValue Type tag magic value.
6691bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
6692                     const ValueDecl **VD, uint64_t *MagicValue) {
6693  while(true) {
6694    if (!TypeExpr)
6695      return false;
6696
6697    TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
6698
6699    switch (TypeExpr->getStmtClass()) {
6700    case Stmt::UnaryOperatorClass: {
6701      const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
6702      if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
6703        TypeExpr = UO->getSubExpr();
6704        continue;
6705      }
6706      return false;
6707    }
6708
6709    case Stmt::DeclRefExprClass: {
6710      const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
6711      *VD = DRE->getDecl();
6712      return true;
6713    }
6714
6715    case Stmt::IntegerLiteralClass: {
6716      const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
6717      llvm::APInt MagicValueAPInt = IL->getValue();
6718      if (MagicValueAPInt.getActiveBits() <= 64) {
6719        *MagicValue = MagicValueAPInt.getZExtValue();
6720        return true;
6721      } else
6722        return false;
6723    }
6724
6725    case Stmt::BinaryConditionalOperatorClass:
6726    case Stmt::ConditionalOperatorClass: {
6727      const AbstractConditionalOperator *ACO =
6728          cast<AbstractConditionalOperator>(TypeExpr);
6729      bool Result;
6730      if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
6731        if (Result)
6732          TypeExpr = ACO->getTrueExpr();
6733        else
6734          TypeExpr = ACO->getFalseExpr();
6735        continue;
6736      }
6737      return false;
6738    }
6739
6740    case Stmt::BinaryOperatorClass: {
6741      const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
6742      if (BO->getOpcode() == BO_Comma) {
6743        TypeExpr = BO->getRHS();
6744        continue;
6745      }
6746      return false;
6747    }
6748
6749    default:
6750      return false;
6751    }
6752  }
6753}
6754
6755/// \brief Retrieve the C type corresponding to type tag TypeExpr.
6756///
6757/// \param TypeExpr Expression that specifies a type tag.
6758///
6759/// \param MagicValues Registered magic values.
6760///
6761/// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
6762///        kind.
6763///
6764/// \param TypeInfo Information about the corresponding C type.
6765///
6766/// \returns true if the corresponding C type was found.
6767bool GetMatchingCType(
6768        const IdentifierInfo *ArgumentKind,
6769        const Expr *TypeExpr, const ASTContext &Ctx,
6770        const llvm::DenseMap<Sema::TypeTagMagicValue,
6771                             Sema::TypeTagData> *MagicValues,
6772        bool &FoundWrongKind,
6773        Sema::TypeTagData &TypeInfo) {
6774  FoundWrongKind = false;
6775
6776  // Variable declaration that has type_tag_for_datatype attribute.
6777  const ValueDecl *VD = NULL;
6778
6779  uint64_t MagicValue;
6780
6781  if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
6782    return false;
6783
6784  if (VD) {
6785    for (specific_attr_iterator<TypeTagForDatatypeAttr>
6786             I = VD->specific_attr_begin<TypeTagForDatatypeAttr>(),
6787             E = VD->specific_attr_end<TypeTagForDatatypeAttr>();
6788         I != E; ++I) {
6789      if (I->getArgumentKind() != ArgumentKind) {
6790        FoundWrongKind = true;
6791        return false;
6792      }
6793      TypeInfo.Type = I->getMatchingCType();
6794      TypeInfo.LayoutCompatible = I->getLayoutCompatible();
6795      TypeInfo.MustBeNull = I->getMustBeNull();
6796      return true;
6797    }
6798    return false;
6799  }
6800
6801  if (!MagicValues)
6802    return false;
6803
6804  llvm::DenseMap<Sema::TypeTagMagicValue,
6805                 Sema::TypeTagData>::const_iterator I =
6806      MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
6807  if (I == MagicValues->end())
6808    return false;
6809
6810  TypeInfo = I->second;
6811  return true;
6812}
6813} // unnamed namespace
6814
6815void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
6816                                      uint64_t MagicValue, QualType Type,
6817                                      bool LayoutCompatible,
6818                                      bool MustBeNull) {
6819  if (!TypeTagForDatatypeMagicValues)
6820    TypeTagForDatatypeMagicValues.reset(
6821        new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
6822
6823  TypeTagMagicValue Magic(ArgumentKind, MagicValue);
6824  (*TypeTagForDatatypeMagicValues)[Magic] =
6825      TypeTagData(Type, LayoutCompatible, MustBeNull);
6826}
6827
6828namespace {
6829bool IsSameCharType(QualType T1, QualType T2) {
6830  const BuiltinType *BT1 = T1->getAs<BuiltinType>();
6831  if (!BT1)
6832    return false;
6833
6834  const BuiltinType *BT2 = T2->getAs<BuiltinType>();
6835  if (!BT2)
6836    return false;
6837
6838  BuiltinType::Kind T1Kind = BT1->getKind();
6839  BuiltinType::Kind T2Kind = BT2->getKind();
6840
6841  return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
6842         (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
6843         (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
6844         (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
6845}
6846} // unnamed namespace
6847
6848void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
6849                                    const Expr * const *ExprArgs) {
6850  const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
6851  bool IsPointerAttr = Attr->getIsPointer();
6852
6853  const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
6854  bool FoundWrongKind;
6855  TypeTagData TypeInfo;
6856  if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
6857                        TypeTagForDatatypeMagicValues.get(),
6858                        FoundWrongKind, TypeInfo)) {
6859    if (FoundWrongKind)
6860      Diag(TypeTagExpr->getExprLoc(),
6861           diag::warn_type_tag_for_datatype_wrong_kind)
6862        << TypeTagExpr->getSourceRange();
6863    return;
6864  }
6865
6866  const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
6867  if (IsPointerAttr) {
6868    // Skip implicit cast of pointer to `void *' (as a function argument).
6869    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
6870      if (ICE->getType()->isVoidPointerType() &&
6871          ICE->getCastKind() == CK_BitCast)
6872        ArgumentExpr = ICE->getSubExpr();
6873  }
6874  QualType ArgumentType = ArgumentExpr->getType();
6875
6876  // Passing a `void*' pointer shouldn't trigger a warning.
6877  if (IsPointerAttr && ArgumentType->isVoidPointerType())
6878    return;
6879
6880  if (TypeInfo.MustBeNull) {
6881    // Type tag with matching void type requires a null pointer.
6882    if (!ArgumentExpr->isNullPointerConstant(Context,
6883                                             Expr::NPC_ValueDependentIsNotNull)) {
6884      Diag(ArgumentExpr->getExprLoc(),
6885           diag::warn_type_safety_null_pointer_required)
6886          << ArgumentKind->getName()
6887          << ArgumentExpr->getSourceRange()
6888          << TypeTagExpr->getSourceRange();
6889    }
6890    return;
6891  }
6892
6893  QualType RequiredType = TypeInfo.Type;
6894  if (IsPointerAttr)
6895    RequiredType = Context.getPointerType(RequiredType);
6896
6897  bool mismatch = false;
6898  if (!TypeInfo.LayoutCompatible) {
6899    mismatch = !Context.hasSameType(ArgumentType, RequiredType);
6900
6901    // C++11 [basic.fundamental] p1:
6902    // Plain char, signed char, and unsigned char are three distinct types.
6903    //
6904    // But we treat plain `char' as equivalent to `signed char' or `unsigned
6905    // char' depending on the current char signedness mode.
6906    if (mismatch)
6907      if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
6908                                           RequiredType->getPointeeType())) ||
6909          (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
6910        mismatch = false;
6911  } else
6912    if (IsPointerAttr)
6913      mismatch = !isLayoutCompatible(Context,
6914                                     ArgumentType->getPointeeType(),
6915                                     RequiredType->getPointeeType());
6916    else
6917      mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
6918
6919  if (mismatch)
6920    Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
6921        << ArgumentType << ArgumentKind->getName()
6922        << TypeInfo.LayoutCompatible << RequiredType
6923        << ArgumentExpr->getSourceRange()
6924        << TypeTagExpr->getSourceRange();
6925}
6926