SemaChecking.cpp revision 2ebb98a78471f2039af4321bae657e7daacc2a62 
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements extra semantic analysis beyond what is enforced
11//  by the C type system.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/Initialization.h"
16#include "clang/Sema/Sema.h"
17#include "clang/Sema/SemaInternal.h"
18#include "clang/Sema/Initialization.h"
19#include "clang/Sema/ScopeInfo.h"
20#include "clang/Analysis/Analyses/FormatString.h"
21#include "clang/AST/ASTContext.h"
22#include "clang/AST/CharUnits.h"
23#include "clang/AST/DeclCXX.h"
24#include "clang/AST/DeclObjC.h"
25#include "clang/AST/ExprCXX.h"
26#include "clang/AST/ExprObjC.h"
27#include "clang/AST/EvaluatedExprVisitor.h"
28#include "clang/AST/DeclObjC.h"
29#include "clang/AST/StmtCXX.h"
30#include "clang/AST/StmtObjC.h"
31#include "clang/Lex/Preprocessor.h"
32#include "llvm/ADT/BitVector.h"
33#include "llvm/ADT/SmallString.h"
34#include "llvm/ADT/STLExtras.h"
35#include "llvm/Support/raw_ostream.h"
36#include "clang/Basic/TargetBuiltins.h"
37#include "clang/Basic/TargetInfo.h"
38#include "clang/Basic/ConvertUTF.h"
39#include <limits>
40using namespace clang;
41using namespace sema;
42
43SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
44                                                    unsigned ByteNo) const {
45  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
46                               PP.getLangOpts(), PP.getTargetInfo());
47}
48
49/// Checks that a call expression's argument count is the desired number.
50/// This is useful when doing custom type-checking.  Returns true on error.
51static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
52  unsigned argCount = call->getNumArgs();
53  if (argCount == desiredArgCount) return false;
54
55  if (argCount < desiredArgCount)
56    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
57        << 0 /*function call*/ << desiredArgCount << argCount
58        << call->getSourceRange();
59
60  // Highlight all the excess arguments.
61  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
62                    call->getArg(argCount - 1)->getLocEnd());
63
64  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
65    << 0 /*function call*/ << desiredArgCount << argCount
66    << call->getArg(1)->getSourceRange();
67}
68
69/// CheckBuiltinAnnotationString - Checks that string argument to the builtin
70/// annotation is a non wide string literal.
71static bool CheckBuiltinAnnotationString(Sema &S, Expr *Arg) {
72  Arg = Arg->IgnoreParenCasts();
73  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
74  if (!Literal || !Literal->isAscii()) {
75    S.Diag(Arg->getLocStart(), diag::err_builtin_annotation_not_string_constant)
76      << Arg->getSourceRange();
77    return true;
78  }
79  return false;
80}
81
82ExprResult
83Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
84  ExprResult TheCallResult(Owned(TheCall));
85
86  // Find out if any arguments are required to be integer constant expressions.
87  unsigned ICEArguments = 0;
88  ASTContext::GetBuiltinTypeError Error;
89  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
90  if (Error != ASTContext::GE_None)
91    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
92
93  // If any arguments are required to be ICE's, check and diagnose.
94  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
95    // Skip arguments not required to be ICE's.
96    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
97
98    llvm::APSInt Result;
99    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
100      return true;
101    ICEArguments &= ~(1 << ArgNo);
102  }
103
104  switch (BuiltinID) {
105  case Builtin::BI__builtin___CFStringMakeConstantString:
106    assert(TheCall->getNumArgs() == 1 &&
107           "Wrong # arguments to builtin CFStringMakeConstantString");
108    if (CheckObjCString(TheCall->getArg(0)))
109      return ExprError();
110    break;
111  case Builtin::BI__builtin_stdarg_start:
112  case Builtin::BI__builtin_va_start:
113    if (SemaBuiltinVAStart(TheCall))
114      return ExprError();
115    break;
116  case Builtin::BI__builtin_isgreater:
117  case Builtin::BI__builtin_isgreaterequal:
118  case Builtin::BI__builtin_isless:
119  case Builtin::BI__builtin_islessequal:
120  case Builtin::BI__builtin_islessgreater:
121  case Builtin::BI__builtin_isunordered:
122    if (SemaBuiltinUnorderedCompare(TheCall))
123      return ExprError();
124    break;
125  case Builtin::BI__builtin_fpclassify:
126    if (SemaBuiltinFPClassification(TheCall, 6))
127      return ExprError();
128    break;
129  case Builtin::BI__builtin_isfinite:
130  case Builtin::BI__builtin_isinf:
131  case Builtin::BI__builtin_isinf_sign:
132  case Builtin::BI__builtin_isnan:
133  case Builtin::BI__builtin_isnormal:
134    if (SemaBuiltinFPClassification(TheCall, 1))
135      return ExprError();
136    break;
137  case Builtin::BI__builtin_shufflevector:
138    return SemaBuiltinShuffleVector(TheCall);
139    // TheCall will be freed by the smart pointer here, but that's fine, since
140    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
141  case Builtin::BI__builtin_prefetch:
142    if (SemaBuiltinPrefetch(TheCall))
143      return ExprError();
144    break;
145  case Builtin::BI__builtin_object_size:
146    if (SemaBuiltinObjectSize(TheCall))
147      return ExprError();
148    break;
149  case Builtin::BI__builtin_longjmp:
150    if (SemaBuiltinLongjmp(TheCall))
151      return ExprError();
152    break;
153
154  case Builtin::BI__builtin_classify_type:
155    if (checkArgCount(*this, TheCall, 1)) return true;
156    TheCall->setType(Context.IntTy);
157    break;
158  case Builtin::BI__builtin_constant_p:
159    if (checkArgCount(*this, TheCall, 1)) return true;
160    TheCall->setType(Context.IntTy);
161    break;
162  case Builtin::BI__sync_fetch_and_add:
163  case Builtin::BI__sync_fetch_and_add_1:
164  case Builtin::BI__sync_fetch_and_add_2:
165  case Builtin::BI__sync_fetch_and_add_4:
166  case Builtin::BI__sync_fetch_and_add_8:
167  case Builtin::BI__sync_fetch_and_add_16:
168  case Builtin::BI__sync_fetch_and_sub:
169  case Builtin::BI__sync_fetch_and_sub_1:
170  case Builtin::BI__sync_fetch_and_sub_2:
171  case Builtin::BI__sync_fetch_and_sub_4:
172  case Builtin::BI__sync_fetch_and_sub_8:
173  case Builtin::BI__sync_fetch_and_sub_16:
174  case Builtin::BI__sync_fetch_and_or:
175  case Builtin::BI__sync_fetch_and_or_1:
176  case Builtin::BI__sync_fetch_and_or_2:
177  case Builtin::BI__sync_fetch_and_or_4:
178  case Builtin::BI__sync_fetch_and_or_8:
179  case Builtin::BI__sync_fetch_and_or_16:
180  case Builtin::BI__sync_fetch_and_and:
181  case Builtin::BI__sync_fetch_and_and_1:
182  case Builtin::BI__sync_fetch_and_and_2:
183  case Builtin::BI__sync_fetch_and_and_4:
184  case Builtin::BI__sync_fetch_and_and_8:
185  case Builtin::BI__sync_fetch_and_and_16:
186  case Builtin::BI__sync_fetch_and_xor:
187  case Builtin::BI__sync_fetch_and_xor_1:
188  case Builtin::BI__sync_fetch_and_xor_2:
189  case Builtin::BI__sync_fetch_and_xor_4:
190  case Builtin::BI__sync_fetch_and_xor_8:
191  case Builtin::BI__sync_fetch_and_xor_16:
192  case Builtin::BI__sync_add_and_fetch:
193  case Builtin::BI__sync_add_and_fetch_1:
194  case Builtin::BI__sync_add_and_fetch_2:
195  case Builtin::BI__sync_add_and_fetch_4:
196  case Builtin::BI__sync_add_and_fetch_8:
197  case Builtin::BI__sync_add_and_fetch_16:
198  case Builtin::BI__sync_sub_and_fetch:
199  case Builtin::BI__sync_sub_and_fetch_1:
200  case Builtin::BI__sync_sub_and_fetch_2:
201  case Builtin::BI__sync_sub_and_fetch_4:
202  case Builtin::BI__sync_sub_and_fetch_8:
203  case Builtin::BI__sync_sub_and_fetch_16:
204  case Builtin::BI__sync_and_and_fetch:
205  case Builtin::BI__sync_and_and_fetch_1:
206  case Builtin::BI__sync_and_and_fetch_2:
207  case Builtin::BI__sync_and_and_fetch_4:
208  case Builtin::BI__sync_and_and_fetch_8:
209  case Builtin::BI__sync_and_and_fetch_16:
210  case Builtin::BI__sync_or_and_fetch:
211  case Builtin::BI__sync_or_and_fetch_1:
212  case Builtin::BI__sync_or_and_fetch_2:
213  case Builtin::BI__sync_or_and_fetch_4:
214  case Builtin::BI__sync_or_and_fetch_8:
215  case Builtin::BI__sync_or_and_fetch_16:
216  case Builtin::BI__sync_xor_and_fetch:
217  case Builtin::BI__sync_xor_and_fetch_1:
218  case Builtin::BI__sync_xor_and_fetch_2:
219  case Builtin::BI__sync_xor_and_fetch_4:
220  case Builtin::BI__sync_xor_and_fetch_8:
221  case Builtin::BI__sync_xor_and_fetch_16:
222  case Builtin::BI__sync_val_compare_and_swap:
223  case Builtin::BI__sync_val_compare_and_swap_1:
224  case Builtin::BI__sync_val_compare_and_swap_2:
225  case Builtin::BI__sync_val_compare_and_swap_4:
226  case Builtin::BI__sync_val_compare_and_swap_8:
227  case Builtin::BI__sync_val_compare_and_swap_16:
228  case Builtin::BI__sync_bool_compare_and_swap:
229  case Builtin::BI__sync_bool_compare_and_swap_1:
230  case Builtin::BI__sync_bool_compare_and_swap_2:
231  case Builtin::BI__sync_bool_compare_and_swap_4:
232  case Builtin::BI__sync_bool_compare_and_swap_8:
233  case Builtin::BI__sync_bool_compare_and_swap_16:
234  case Builtin::BI__sync_lock_test_and_set:
235  case Builtin::BI__sync_lock_test_and_set_1:
236  case Builtin::BI__sync_lock_test_and_set_2:
237  case Builtin::BI__sync_lock_test_and_set_4:
238  case Builtin::BI__sync_lock_test_and_set_8:
239  case Builtin::BI__sync_lock_test_and_set_16:
240  case Builtin::BI__sync_lock_release:
241  case Builtin::BI__sync_lock_release_1:
242  case Builtin::BI__sync_lock_release_2:
243  case Builtin::BI__sync_lock_release_4:
244  case Builtin::BI__sync_lock_release_8:
245  case Builtin::BI__sync_lock_release_16:
246  case Builtin::BI__sync_swap:
247  case Builtin::BI__sync_swap_1:
248  case Builtin::BI__sync_swap_2:
249  case Builtin::BI__sync_swap_4:
250  case Builtin::BI__sync_swap_8:
251  case Builtin::BI__sync_swap_16:
252    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
253  case Builtin::BI__atomic_load:
254    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Load);
255  case Builtin::BI__atomic_store:
256    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Store);
257  case Builtin::BI__atomic_init:
258    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Init);
259  case Builtin::BI__atomic_exchange:
260    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xchg);
261  case Builtin::BI__atomic_compare_exchange_strong:
262    return SemaAtomicOpsOverloaded(move(TheCallResult),
263                                   AtomicExpr::CmpXchgStrong);
264  case Builtin::BI__atomic_compare_exchange_weak:
265    return SemaAtomicOpsOverloaded(move(TheCallResult),
266                                   AtomicExpr::CmpXchgWeak);
267  case Builtin::BI__atomic_fetch_add:
268    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Add);
269  case Builtin::BI__atomic_fetch_sub:
270    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Sub);
271  case Builtin::BI__atomic_fetch_and:
272    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::And);
273  case Builtin::BI__atomic_fetch_or:
274    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Or);
275  case Builtin::BI__atomic_fetch_xor:
276    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xor);
277  case Builtin::BI__builtin_annotation:
278    if (CheckBuiltinAnnotationString(*this, TheCall->getArg(1)))
279      return ExprError();
280    break;
281  }
282
283  // Since the target specific builtins for each arch overlap, only check those
284  // of the arch we are compiling for.
285  if (BuiltinID >= Builtin::FirstTSBuiltin) {
286    switch (Context.getTargetInfo().getTriple().getArch()) {
287      case llvm::Triple::arm:
288      case llvm::Triple::thumb:
289        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
290          return ExprError();
291        break;
292      default:
293        break;
294    }
295  }
296
297  return move(TheCallResult);
298}
299
300// Get the valid immediate range for the specified NEON type code.
301static unsigned RFT(unsigned t, bool shift = false) {
302  NeonTypeFlags Type(t);
303  int IsQuad = Type.isQuad();
304  switch (Type.getEltType()) {
305  case NeonTypeFlags::Int8:
306  case NeonTypeFlags::Poly8:
307    return shift ? 7 : (8 << IsQuad) - 1;
308  case NeonTypeFlags::Int16:
309  case NeonTypeFlags::Poly16:
310    return shift ? 15 : (4 << IsQuad) - 1;
311  case NeonTypeFlags::Int32:
312    return shift ? 31 : (2 << IsQuad) - 1;
313  case NeonTypeFlags::Int64:
314    return shift ? 63 : (1 << IsQuad) - 1;
315  case NeonTypeFlags::Float16:
316    assert(!shift && "cannot shift float types!");
317    return (4 << IsQuad) - 1;
318  case NeonTypeFlags::Float32:
319    assert(!shift && "cannot shift float types!");
320    return (2 << IsQuad) - 1;
321  }
322  llvm_unreachable("Invalid NeonTypeFlag!");
323}
324
325/// getNeonEltType - Return the QualType corresponding to the elements of
326/// the vector type specified by the NeonTypeFlags.  This is used to check
327/// the pointer arguments for Neon load/store intrinsics.
328static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
329  switch (Flags.getEltType()) {
330  case NeonTypeFlags::Int8:
331    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
332  case NeonTypeFlags::Int16:
333    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
334  case NeonTypeFlags::Int32:
335    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
336  case NeonTypeFlags::Int64:
337    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
338  case NeonTypeFlags::Poly8:
339    return Context.SignedCharTy;
340  case NeonTypeFlags::Poly16:
341    return Context.ShortTy;
342  case NeonTypeFlags::Float16:
343    return Context.UnsignedShortTy;
344  case NeonTypeFlags::Float32:
345    return Context.FloatTy;
346  }
347  llvm_unreachable("Invalid NeonTypeFlag!");
348}
349
350bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
351  llvm::APSInt Result;
352
353  unsigned mask = 0;
354  unsigned TV = 0;
355  int PtrArgNum = -1;
356  bool HasConstPtr = false;
357  switch (BuiltinID) {
358#define GET_NEON_OVERLOAD_CHECK
359#include "clang/Basic/arm_neon.inc"
360#undef GET_NEON_OVERLOAD_CHECK
361  }
362
363  // For NEON intrinsics which are overloaded on vector element type, validate
364  // the immediate which specifies which variant to emit.
365  unsigned ImmArg = TheCall->getNumArgs()-1;
366  if (mask) {
367    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
368      return true;
369
370    TV = Result.getLimitedValue(64);
371    if ((TV > 63) || (mask & (1 << TV)) == 0)
372      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
373        << TheCall->getArg(ImmArg)->getSourceRange();
374  }
375
376  if (PtrArgNum >= 0) {
377    // Check that pointer arguments have the specified type.
378    Expr *Arg = TheCall->getArg(PtrArgNum);
379    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
380      Arg = ICE->getSubExpr();
381    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
382    QualType RHSTy = RHS.get()->getType();
383    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
384    if (HasConstPtr)
385      EltTy = EltTy.withConst();
386    QualType LHSTy = Context.getPointerType(EltTy);
387    AssignConvertType ConvTy;
388    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
389    if (RHS.isInvalid())
390      return true;
391    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
392                                 RHS.get(), AA_Assigning))
393      return true;
394  }
395
396  // For NEON intrinsics which take an immediate value as part of the
397  // instruction, range check them here.
398  unsigned i = 0, l = 0, u = 0;
399  switch (BuiltinID) {
400  default: return false;
401  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
402  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
403  case ARM::BI__builtin_arm_vcvtr_f:
404  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
405#define GET_NEON_IMMEDIATE_CHECK
406#include "clang/Basic/arm_neon.inc"
407#undef GET_NEON_IMMEDIATE_CHECK
408  };
409
410  // Check that the immediate argument is actually a constant.
411  if (SemaBuiltinConstantArg(TheCall, i, Result))
412    return true;
413
414  // Range check against the upper/lower values for this isntruction.
415  unsigned Val = Result.getZExtValue();
416  if (Val < l || Val > (u + l))
417    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
418      << l << u+l << TheCall->getArg(i)->getSourceRange();
419
420  // FIXME: VFP Intrinsics should error if VFP not present.
421  return false;
422}
423
424/// CheckFunctionCall - Check a direct function call for various correctness
425/// and safety properties not strictly enforced by the C type system.
426bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
427  // Get the IdentifierInfo* for the called function.
428  IdentifierInfo *FnInfo = FDecl->getIdentifier();
429
430  // None of the checks below are needed for functions that don't have
431  // simple names (e.g., C++ conversion functions).
432  if (!FnInfo)
433    return false;
434
435  // FIXME: This mechanism should be abstracted to be less fragile and
436  // more efficient. For example, just map function ids to custom
437  // handlers.
438
439  // Printf and scanf checking.
440  for (specific_attr_iterator<FormatAttr>
441         i = FDecl->specific_attr_begin<FormatAttr>(),
442         e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
443    CheckFormatArguments(*i, TheCall);
444  }
445
446  for (specific_attr_iterator<NonNullAttr>
447         i = FDecl->specific_attr_begin<NonNullAttr>(),
448         e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) {
449    CheckNonNullArguments(*i, TheCall->getArgs(),
450                          TheCall->getCallee()->getLocStart());
451  }
452
453  unsigned CMId = FDecl->getMemoryFunctionKind();
454  if (CMId == 0)
455    return false;
456
457  // Handle memory setting and copying functions.
458  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
459    CheckStrlcpycatArguments(TheCall, FnInfo);
460  else if (CMId == Builtin::BIstrncat)
461    CheckStrncatArguments(TheCall, FnInfo);
462  else
463    CheckMemaccessArguments(TheCall, CMId, FnInfo);
464
465  return false;
466}
467
468bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
469                               Expr **Args, unsigned NumArgs) {
470  for (specific_attr_iterator<FormatAttr>
471       i = Method->specific_attr_begin<FormatAttr>(),
472       e = Method->specific_attr_end<FormatAttr>(); i != e ; ++i) {
473
474    CheckFormatArguments(*i, Args, NumArgs, false, lbrac,
475                         Method->getSourceRange());
476  }
477
478  // diagnose nonnull arguments.
479  for (specific_attr_iterator<NonNullAttr>
480       i = Method->specific_attr_begin<NonNullAttr>(),
481       e = Method->specific_attr_end<NonNullAttr>(); i != e; ++i) {
482    CheckNonNullArguments(*i, Args, lbrac);
483  }
484
485  return false;
486}
487
488bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
489  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
490  if (!V)
491    return false;
492
493  QualType Ty = V->getType();
494  if (!Ty->isBlockPointerType())
495    return false;
496
497  // format string checking.
498  for (specific_attr_iterator<FormatAttr>
499       i = NDecl->specific_attr_begin<FormatAttr>(),
500       e = NDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
501    CheckFormatArguments(*i, TheCall);
502  }
503
504  return false;
505}
506
507ExprResult
508Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, AtomicExpr::AtomicOp Op) {
509  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
510  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
511
512  // All these operations take one of the following four forms:
513  // T   __atomic_load(_Atomic(T)*, int)                              (loads)
514  // T*  __atomic_add(_Atomic(T*)*, ptrdiff_t, int)         (pointer add/sub)
515  // int __atomic_compare_exchange_strong(_Atomic(T)*, T*, T, int, int)
516  //                                                                (cmpxchg)
517  // T   __atomic_exchange(_Atomic(T)*, T, int)             (everything else)
518  // where T is an appropriate type, and the int paremeterss are for orderings.
519  unsigned NumVals = 1;
520  unsigned NumOrders = 1;
521  if (Op == AtomicExpr::Load) {
522    NumVals = 0;
523  } else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong) {
524    NumVals = 2;
525    NumOrders = 2;
526  }
527  if (Op == AtomicExpr::Init)
528    NumOrders = 0;
529
530  if (TheCall->getNumArgs() < NumVals+NumOrders+1) {
531    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
532      << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs()
533      << TheCall->getCallee()->getSourceRange();
534    return ExprError();
535  } else if (TheCall->getNumArgs() > NumVals+NumOrders+1) {
536    Diag(TheCall->getArg(NumVals+NumOrders+1)->getLocStart(),
537         diag::err_typecheck_call_too_many_args)
538      << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs()
539      << TheCall->getCallee()->getSourceRange();
540    return ExprError();
541  }
542
543  // Inspect the first argument of the atomic operation.  This should always be
544  // a pointer to an _Atomic type.
545  Expr *Ptr = TheCall->getArg(0);
546  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
547  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
548  if (!pointerType) {
549    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
550      << Ptr->getType() << Ptr->getSourceRange();
551    return ExprError();
552  }
553
554  QualType AtomTy = pointerType->getPointeeType();
555  if (!AtomTy->isAtomicType()) {
556    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
557      << Ptr->getType() << Ptr->getSourceRange();
558    return ExprError();
559  }
560  QualType ValType = AtomTy->getAs<AtomicType>()->getValueType();
561
562  if ((Op == AtomicExpr::Add || Op == AtomicExpr::Sub) &&
563      !ValType->isIntegerType() && !ValType->isPointerType()) {
564    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
565      << Ptr->getType() << Ptr->getSourceRange();
566    return ExprError();
567  }
568
569  if (!ValType->isIntegerType() &&
570      (Op == AtomicExpr::And || Op == AtomicExpr::Or || Op == AtomicExpr::Xor)){
571    Diag(DRE->getLocStart(), diag::err_atomic_op_logical_needs_atomic_int)
572      << Ptr->getType() << Ptr->getSourceRange();
573    return ExprError();
574  }
575
576  switch (ValType.getObjCLifetime()) {
577  case Qualifiers::OCL_None:
578  case Qualifiers::OCL_ExplicitNone:
579    // okay
580    break;
581
582  case Qualifiers::OCL_Weak:
583  case Qualifiers::OCL_Strong:
584  case Qualifiers::OCL_Autoreleasing:
585    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
586      << ValType << Ptr->getSourceRange();
587    return ExprError();
588  }
589
590  QualType ResultType = ValType;
591  if (Op == AtomicExpr::Store || Op == AtomicExpr::Init)
592    ResultType = Context.VoidTy;
593  else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong)
594    ResultType = Context.BoolTy;
595
596  // The first argument --- the pointer --- has a fixed type; we
597  // deduce the types of the rest of the arguments accordingly.  Walk
598  // the remaining arguments, converting them to the deduced value type.
599  for (unsigned i = 1; i != NumVals+NumOrders+1; ++i) {
600    ExprResult Arg = TheCall->getArg(i);
601    QualType Ty;
602    if (i < NumVals+1) {
603      // The second argument to a cmpxchg is a pointer to the data which will
604      // be exchanged. The second argument to a pointer add/subtract is the
605      // amount to add/subtract, which must be a ptrdiff_t.  The third
606      // argument to a cmpxchg and the second argument in all other cases
607      // is the type of the value.
608      if (i == 1 && (Op == AtomicExpr::CmpXchgWeak ||
609                     Op == AtomicExpr::CmpXchgStrong))
610         Ty = Context.getPointerType(ValType.getUnqualifiedType());
611      else if (!ValType->isIntegerType() &&
612               (Op == AtomicExpr::Add || Op == AtomicExpr::Sub))
613        Ty = Context.getPointerDiffType();
614      else
615        Ty = ValType;
616    } else {
617      // The order(s) are always converted to int.
618      Ty = Context.IntTy;
619    }
620    InitializedEntity Entity =
621        InitializedEntity::InitializeParameter(Context, Ty, false);
622    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
623    if (Arg.isInvalid())
624      return true;
625    TheCall->setArg(i, Arg.get());
626  }
627
628  SmallVector<Expr*, 5> SubExprs;
629  SubExprs.push_back(Ptr);
630  if (Op == AtomicExpr::Load) {
631    SubExprs.push_back(TheCall->getArg(1)); // Order
632  } else if (Op == AtomicExpr::Init) {
633    SubExprs.push_back(TheCall->getArg(1)); // Val1
634  } else if (Op != AtomicExpr::CmpXchgWeak && Op != AtomicExpr::CmpXchgStrong) {
635    SubExprs.push_back(TheCall->getArg(2)); // Order
636    SubExprs.push_back(TheCall->getArg(1)); // Val1
637  } else {
638    SubExprs.push_back(TheCall->getArg(3)); // Order
639    SubExprs.push_back(TheCall->getArg(1)); // Val1
640    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
641    SubExprs.push_back(TheCall->getArg(2)); // Val2
642  }
643
644  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
645                                        SubExprs.data(), SubExprs.size(),
646                                        ResultType, Op,
647                                        TheCall->getRParenLoc()));
648}
649
650
651/// checkBuiltinArgument - Given a call to a builtin function, perform
652/// normal type-checking on the given argument, updating the call in
653/// place.  This is useful when a builtin function requires custom
654/// type-checking for some of its arguments but not necessarily all of
655/// them.
656///
657/// Returns true on error.
658static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
659  FunctionDecl *Fn = E->getDirectCallee();
660  assert(Fn && "builtin call without direct callee!");
661
662  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
663  InitializedEntity Entity =
664    InitializedEntity::InitializeParameter(S.Context, Param);
665
666  ExprResult Arg = E->getArg(0);
667  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
668  if (Arg.isInvalid())
669    return true;
670
671  E->setArg(ArgIndex, Arg.take());
672  return false;
673}
674
675/// SemaBuiltinAtomicOverloaded - We have a call to a function like
676/// __sync_fetch_and_add, which is an overloaded function based on the pointer
677/// type of its first argument.  The main ActOnCallExpr routines have already
678/// promoted the types of arguments because all of these calls are prototyped as
679/// void(...).
680///
681/// This function goes through and does final semantic checking for these
682/// builtins,
683ExprResult
684Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
685  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
686  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
687  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
688
689  // Ensure that we have at least one argument to do type inference from.
690  if (TheCall->getNumArgs() < 1) {
691    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
692      << 0 << 1 << TheCall->getNumArgs()
693      << TheCall->getCallee()->getSourceRange();
694    return ExprError();
695  }
696
697  // Inspect the first argument of the atomic builtin.  This should always be
698  // a pointer type, whose element is an integral scalar or pointer type.
699  // Because it is a pointer type, we don't have to worry about any implicit
700  // casts here.
701  // FIXME: We don't allow floating point scalars as input.
702  Expr *FirstArg = TheCall->getArg(0);
703  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
704  if (FirstArgResult.isInvalid())
705    return ExprError();
706  FirstArg = FirstArgResult.take();
707  TheCall->setArg(0, FirstArg);
708
709  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
710  if (!pointerType) {
711    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
712      << FirstArg->getType() << FirstArg->getSourceRange();
713    return ExprError();
714  }
715
716  QualType ValType = pointerType->getPointeeType();
717  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
718      !ValType->isBlockPointerType()) {
719    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
720      << FirstArg->getType() << FirstArg->getSourceRange();
721    return ExprError();
722  }
723
724  switch (ValType.getObjCLifetime()) {
725  case Qualifiers::OCL_None:
726  case Qualifiers::OCL_ExplicitNone:
727    // okay
728    break;
729
730  case Qualifiers::OCL_Weak:
731  case Qualifiers::OCL_Strong:
732  case Qualifiers::OCL_Autoreleasing:
733    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
734      << ValType << FirstArg->getSourceRange();
735    return ExprError();
736  }
737
738  // Strip any qualifiers off ValType.
739  ValType = ValType.getUnqualifiedType();
740
741  // The majority of builtins return a value, but a few have special return
742  // types, so allow them to override appropriately below.
743  QualType ResultType = ValType;
744
745  // We need to figure out which concrete builtin this maps onto.  For example,
746  // __sync_fetch_and_add with a 2 byte object turns into
747  // __sync_fetch_and_add_2.
748#define BUILTIN_ROW(x) \
749  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
750    Builtin::BI##x##_8, Builtin::BI##x##_16 }
751
752  static const unsigned BuiltinIndices[][5] = {
753    BUILTIN_ROW(__sync_fetch_and_add),
754    BUILTIN_ROW(__sync_fetch_and_sub),
755    BUILTIN_ROW(__sync_fetch_and_or),
756    BUILTIN_ROW(__sync_fetch_and_and),
757    BUILTIN_ROW(__sync_fetch_and_xor),
758
759    BUILTIN_ROW(__sync_add_and_fetch),
760    BUILTIN_ROW(__sync_sub_and_fetch),
761    BUILTIN_ROW(__sync_and_and_fetch),
762    BUILTIN_ROW(__sync_or_and_fetch),
763    BUILTIN_ROW(__sync_xor_and_fetch),
764
765    BUILTIN_ROW(__sync_val_compare_and_swap),
766    BUILTIN_ROW(__sync_bool_compare_and_swap),
767    BUILTIN_ROW(__sync_lock_test_and_set),
768    BUILTIN_ROW(__sync_lock_release),
769    BUILTIN_ROW(__sync_swap)
770  };
771#undef BUILTIN_ROW
772
773  // Determine the index of the size.
774  unsigned SizeIndex;
775  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
776  case 1: SizeIndex = 0; break;
777  case 2: SizeIndex = 1; break;
778  case 4: SizeIndex = 2; break;
779  case 8: SizeIndex = 3; break;
780  case 16: SizeIndex = 4; break;
781  default:
782    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
783      << FirstArg->getType() << FirstArg->getSourceRange();
784    return ExprError();
785  }
786
787  // Each of these builtins has one pointer argument, followed by some number of
788  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
789  // that we ignore.  Find out which row of BuiltinIndices to read from as well
790  // as the number of fixed args.
791  unsigned BuiltinID = FDecl->getBuiltinID();
792  unsigned BuiltinIndex, NumFixed = 1;
793  switch (BuiltinID) {
794  default: llvm_unreachable("Unknown overloaded atomic builtin!");
795  case Builtin::BI__sync_fetch_and_add:
796  case Builtin::BI__sync_fetch_and_add_1:
797  case Builtin::BI__sync_fetch_and_add_2:
798  case Builtin::BI__sync_fetch_and_add_4:
799  case Builtin::BI__sync_fetch_and_add_8:
800  case Builtin::BI__sync_fetch_and_add_16:
801    BuiltinIndex = 0;
802    break;
803
804  case Builtin::BI__sync_fetch_and_sub:
805  case Builtin::BI__sync_fetch_and_sub_1:
806  case Builtin::BI__sync_fetch_and_sub_2:
807  case Builtin::BI__sync_fetch_and_sub_4:
808  case Builtin::BI__sync_fetch_and_sub_8:
809  case Builtin::BI__sync_fetch_and_sub_16:
810    BuiltinIndex = 1;
811    break;
812
813  case Builtin::BI__sync_fetch_and_or:
814  case Builtin::BI__sync_fetch_and_or_1:
815  case Builtin::BI__sync_fetch_and_or_2:
816  case Builtin::BI__sync_fetch_and_or_4:
817  case Builtin::BI__sync_fetch_and_or_8:
818  case Builtin::BI__sync_fetch_and_or_16:
819    BuiltinIndex = 2;
820    break;
821
822  case Builtin::BI__sync_fetch_and_and:
823  case Builtin::BI__sync_fetch_and_and_1:
824  case Builtin::BI__sync_fetch_and_and_2:
825  case Builtin::BI__sync_fetch_and_and_4:
826  case Builtin::BI__sync_fetch_and_and_8:
827  case Builtin::BI__sync_fetch_and_and_16:
828    BuiltinIndex = 3;
829    break;
830
831  case Builtin::BI__sync_fetch_and_xor:
832  case Builtin::BI__sync_fetch_and_xor_1:
833  case Builtin::BI__sync_fetch_and_xor_2:
834  case Builtin::BI__sync_fetch_and_xor_4:
835  case Builtin::BI__sync_fetch_and_xor_8:
836  case Builtin::BI__sync_fetch_and_xor_16:
837    BuiltinIndex = 4;
838    break;
839
840  case Builtin::BI__sync_add_and_fetch:
841  case Builtin::BI__sync_add_and_fetch_1:
842  case Builtin::BI__sync_add_and_fetch_2:
843  case Builtin::BI__sync_add_and_fetch_4:
844  case Builtin::BI__sync_add_and_fetch_8:
845  case Builtin::BI__sync_add_and_fetch_16:
846    BuiltinIndex = 5;
847    break;
848
849  case Builtin::BI__sync_sub_and_fetch:
850  case Builtin::BI__sync_sub_and_fetch_1:
851  case Builtin::BI__sync_sub_and_fetch_2:
852  case Builtin::BI__sync_sub_and_fetch_4:
853  case Builtin::BI__sync_sub_and_fetch_8:
854  case Builtin::BI__sync_sub_and_fetch_16:
855    BuiltinIndex = 6;
856    break;
857
858  case Builtin::BI__sync_and_and_fetch:
859  case Builtin::BI__sync_and_and_fetch_1:
860  case Builtin::BI__sync_and_and_fetch_2:
861  case Builtin::BI__sync_and_and_fetch_4:
862  case Builtin::BI__sync_and_and_fetch_8:
863  case Builtin::BI__sync_and_and_fetch_16:
864    BuiltinIndex = 7;
865    break;
866
867  case Builtin::BI__sync_or_and_fetch:
868  case Builtin::BI__sync_or_and_fetch_1:
869  case Builtin::BI__sync_or_and_fetch_2:
870  case Builtin::BI__sync_or_and_fetch_4:
871  case Builtin::BI__sync_or_and_fetch_8:
872  case Builtin::BI__sync_or_and_fetch_16:
873    BuiltinIndex = 8;
874    break;
875
876  case Builtin::BI__sync_xor_and_fetch:
877  case Builtin::BI__sync_xor_and_fetch_1:
878  case Builtin::BI__sync_xor_and_fetch_2:
879  case Builtin::BI__sync_xor_and_fetch_4:
880  case Builtin::BI__sync_xor_and_fetch_8:
881  case Builtin::BI__sync_xor_and_fetch_16:
882    BuiltinIndex = 9;
883    break;
884
885  case Builtin::BI__sync_val_compare_and_swap:
886  case Builtin::BI__sync_val_compare_and_swap_1:
887  case Builtin::BI__sync_val_compare_and_swap_2:
888  case Builtin::BI__sync_val_compare_and_swap_4:
889  case Builtin::BI__sync_val_compare_and_swap_8:
890  case Builtin::BI__sync_val_compare_and_swap_16:
891    BuiltinIndex = 10;
892    NumFixed = 2;
893    break;
894
895  case Builtin::BI__sync_bool_compare_and_swap:
896  case Builtin::BI__sync_bool_compare_and_swap_1:
897  case Builtin::BI__sync_bool_compare_and_swap_2:
898  case Builtin::BI__sync_bool_compare_and_swap_4:
899  case Builtin::BI__sync_bool_compare_and_swap_8:
900  case Builtin::BI__sync_bool_compare_and_swap_16:
901    BuiltinIndex = 11;
902    NumFixed = 2;
903    ResultType = Context.BoolTy;
904    break;
905
906  case Builtin::BI__sync_lock_test_and_set:
907  case Builtin::BI__sync_lock_test_and_set_1:
908  case Builtin::BI__sync_lock_test_and_set_2:
909  case Builtin::BI__sync_lock_test_and_set_4:
910  case Builtin::BI__sync_lock_test_and_set_8:
911  case Builtin::BI__sync_lock_test_and_set_16:
912    BuiltinIndex = 12;
913    break;
914
915  case Builtin::BI__sync_lock_release:
916  case Builtin::BI__sync_lock_release_1:
917  case Builtin::BI__sync_lock_release_2:
918  case Builtin::BI__sync_lock_release_4:
919  case Builtin::BI__sync_lock_release_8:
920  case Builtin::BI__sync_lock_release_16:
921    BuiltinIndex = 13;
922    NumFixed = 0;
923    ResultType = Context.VoidTy;
924    break;
925
926  case Builtin::BI__sync_swap:
927  case Builtin::BI__sync_swap_1:
928  case Builtin::BI__sync_swap_2:
929  case Builtin::BI__sync_swap_4:
930  case Builtin::BI__sync_swap_8:
931  case Builtin::BI__sync_swap_16:
932    BuiltinIndex = 14;
933    break;
934  }
935
936  // Now that we know how many fixed arguments we expect, first check that we
937  // have at least that many.
938  if (TheCall->getNumArgs() < 1+NumFixed) {
939    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
940      << 0 << 1+NumFixed << TheCall->getNumArgs()
941      << TheCall->getCallee()->getSourceRange();
942    return ExprError();
943  }
944
945  // Get the decl for the concrete builtin from this, we can tell what the
946  // concrete integer type we should convert to is.
947  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
948  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
949  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
950  FunctionDecl *NewBuiltinDecl =
951    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
952                                           TUScope, false, DRE->getLocStart()));
953
954  // The first argument --- the pointer --- has a fixed type; we
955  // deduce the types of the rest of the arguments accordingly.  Walk
956  // the remaining arguments, converting them to the deduced value type.
957  for (unsigned i = 0; i != NumFixed; ++i) {
958    ExprResult Arg = TheCall->getArg(i+1);
959
960    // GCC does an implicit conversion to the pointer or integer ValType.  This
961    // can fail in some cases (1i -> int**), check for this error case now.
962    // Initialize the argument.
963    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
964                                                   ValType, /*consume*/ false);
965    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
966    if (Arg.isInvalid())
967      return ExprError();
968
969    // Okay, we have something that *can* be converted to the right type.  Check
970    // to see if there is a potentially weird extension going on here.  This can
971    // happen when you do an atomic operation on something like an char* and
972    // pass in 42.  The 42 gets converted to char.  This is even more strange
973    // for things like 45.123 -> char, etc.
974    // FIXME: Do this check.
975    TheCall->setArg(i+1, Arg.take());
976  }
977
978  ASTContext& Context = this->getASTContext();
979
980  // Create a new DeclRefExpr to refer to the new decl.
981  DeclRefExpr* NewDRE = DeclRefExpr::Create(
982      Context,
983      DRE->getQualifierLoc(),
984      SourceLocation(),
985      NewBuiltinDecl,
986      /*enclosing*/ false,
987      DRE->getLocation(),
988      NewBuiltinDecl->getType(),
989      DRE->getValueKind());
990
991  // Set the callee in the CallExpr.
992  // FIXME: This leaks the original parens and implicit casts.
993  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
994  if (PromotedCall.isInvalid())
995    return ExprError();
996  TheCall->setCallee(PromotedCall.take());
997
998  // Change the result type of the call to match the original value type. This
999  // is arbitrary, but the codegen for these builtins ins design to handle it
1000  // gracefully.
1001  TheCall->setType(ResultType);
1002
1003  return move(TheCallResult);
1004}
1005
1006/// CheckObjCString - Checks that the argument to the builtin
1007/// CFString constructor is correct
1008/// Note: It might also make sense to do the UTF-16 conversion here (would
1009/// simplify the backend).
1010bool Sema::CheckObjCString(Expr *Arg) {
1011  Arg = Arg->IgnoreParenCasts();
1012  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1013
1014  if (!Literal || !Literal->isAscii()) {
1015    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1016      << Arg->getSourceRange();
1017    return true;
1018  }
1019
1020  if (Literal->containsNonAsciiOrNull()) {
1021    StringRef String = Literal->getString();
1022    unsigned NumBytes = String.size();
1023    SmallVector<UTF16, 128> ToBuf(NumBytes);
1024    const UTF8 *FromPtr = (UTF8 *)String.data();
1025    UTF16 *ToPtr = &ToBuf[0];
1026
1027    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1028                                                 &ToPtr, ToPtr + NumBytes,
1029                                                 strictConversion);
1030    // Check for conversion failure.
1031    if (Result != conversionOK)
1032      Diag(Arg->getLocStart(),
1033           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1034  }
1035  return false;
1036}
1037
1038/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1039/// Emit an error and return true on failure, return false on success.
1040bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1041  Expr *Fn = TheCall->getCallee();
1042  if (TheCall->getNumArgs() > 2) {
1043    Diag(TheCall->getArg(2)->getLocStart(),
1044         diag::err_typecheck_call_too_many_args)
1045      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1046      << Fn->getSourceRange()
1047      << SourceRange(TheCall->getArg(2)->getLocStart(),
1048                     (*(TheCall->arg_end()-1))->getLocEnd());
1049    return true;
1050  }
1051
1052  if (TheCall->getNumArgs() < 2) {
1053    return Diag(TheCall->getLocEnd(),
1054      diag::err_typecheck_call_too_few_args_at_least)
1055      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1056  }
1057
1058  // Type-check the first argument normally.
1059  if (checkBuiltinArgument(*this, TheCall, 0))
1060    return true;
1061
1062  // Determine whether the current function is variadic or not.
1063  BlockScopeInfo *CurBlock = getCurBlock();
1064  bool isVariadic;
1065  if (CurBlock)
1066    isVariadic = CurBlock->TheDecl->isVariadic();
1067  else if (FunctionDecl *FD = getCurFunctionDecl())
1068    isVariadic = FD->isVariadic();
1069  else
1070    isVariadic = getCurMethodDecl()->isVariadic();
1071
1072  if (!isVariadic) {
1073    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1074    return true;
1075  }
1076
1077  // Verify that the second argument to the builtin is the last argument of the
1078  // current function or method.
1079  bool SecondArgIsLastNamedArgument = false;
1080  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1081
1082  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1083    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1084      // FIXME: This isn't correct for methods (results in bogus warning).
1085      // Get the last formal in the current function.
1086      const ParmVarDecl *LastArg;
1087      if (CurBlock)
1088        LastArg = *(CurBlock->TheDecl->param_end()-1);
1089      else if (FunctionDecl *FD = getCurFunctionDecl())
1090        LastArg = *(FD->param_end()-1);
1091      else
1092        LastArg = *(getCurMethodDecl()->param_end()-1);
1093      SecondArgIsLastNamedArgument = PV == LastArg;
1094    }
1095  }
1096
1097  if (!SecondArgIsLastNamedArgument)
1098    Diag(TheCall->getArg(1)->getLocStart(),
1099         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1100  return false;
1101}
1102
1103/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1104/// friends.  This is declared to take (...), so we have to check everything.
1105bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1106  if (TheCall->getNumArgs() < 2)
1107    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1108      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1109  if (TheCall->getNumArgs() > 2)
1110    return Diag(TheCall->getArg(2)->getLocStart(),
1111                diag::err_typecheck_call_too_many_args)
1112      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1113      << SourceRange(TheCall->getArg(2)->getLocStart(),
1114                     (*(TheCall->arg_end()-1))->getLocEnd());
1115
1116  ExprResult OrigArg0 = TheCall->getArg(0);
1117  ExprResult OrigArg1 = TheCall->getArg(1);
1118
1119  // Do standard promotions between the two arguments, returning their common
1120  // type.
1121  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1122  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1123    return true;
1124
1125  // Make sure any conversions are pushed back into the call; this is
1126  // type safe since unordered compare builtins are declared as "_Bool
1127  // foo(...)".
1128  TheCall->setArg(0, OrigArg0.get());
1129  TheCall->setArg(1, OrigArg1.get());
1130
1131  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1132    return false;
1133
1134  // If the common type isn't a real floating type, then the arguments were
1135  // invalid for this operation.
1136  if (!Res->isRealFloatingType())
1137    return Diag(OrigArg0.get()->getLocStart(),
1138                diag::err_typecheck_call_invalid_ordered_compare)
1139      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1140      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1141
1142  return false;
1143}
1144
1145/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1146/// __builtin_isnan and friends.  This is declared to take (...), so we have
1147/// to check everything. We expect the last argument to be a floating point
1148/// value.
1149bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1150  if (TheCall->getNumArgs() < NumArgs)
1151    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1152      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1153  if (TheCall->getNumArgs() > NumArgs)
1154    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1155                diag::err_typecheck_call_too_many_args)
1156      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1157      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1158                     (*(TheCall->arg_end()-1))->getLocEnd());
1159
1160  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1161
1162  if (OrigArg->isTypeDependent())
1163    return false;
1164
1165  // This operation requires a non-_Complex floating-point number.
1166  if (!OrigArg->getType()->isRealFloatingType())
1167    return Diag(OrigArg->getLocStart(),
1168                diag::err_typecheck_call_invalid_unary_fp)
1169      << OrigArg->getType() << OrigArg->getSourceRange();
1170
1171  // If this is an implicit conversion from float -> double, remove it.
1172  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1173    Expr *CastArg = Cast->getSubExpr();
1174    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1175      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1176             "promotion from float to double is the only expected cast here");
1177      Cast->setSubExpr(0);
1178      TheCall->setArg(NumArgs-1, CastArg);
1179      OrigArg = CastArg;
1180    }
1181  }
1182
1183  return false;
1184}
1185
1186/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1187// This is declared to take (...), so we have to check everything.
1188ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1189  if (TheCall->getNumArgs() < 2)
1190    return ExprError(Diag(TheCall->getLocEnd(),
1191                          diag::err_typecheck_call_too_few_args_at_least)
1192      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1193      << TheCall->getSourceRange());
1194
1195  // Determine which of the following types of shufflevector we're checking:
1196  // 1) unary, vector mask: (lhs, mask)
1197  // 2) binary, vector mask: (lhs, rhs, mask)
1198  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1199  QualType resType = TheCall->getArg(0)->getType();
1200  unsigned numElements = 0;
1201
1202  if (!TheCall->getArg(0)->isTypeDependent() &&
1203      !TheCall->getArg(1)->isTypeDependent()) {
1204    QualType LHSType = TheCall->getArg(0)->getType();
1205    QualType RHSType = TheCall->getArg(1)->getType();
1206
1207    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1208      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1209        << SourceRange(TheCall->getArg(0)->getLocStart(),
1210                       TheCall->getArg(1)->getLocEnd());
1211      return ExprError();
1212    }
1213
1214    numElements = LHSType->getAs<VectorType>()->getNumElements();
1215    unsigned numResElements = TheCall->getNumArgs() - 2;
1216
1217    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1218    // with mask.  If so, verify that RHS is an integer vector type with the
1219    // same number of elts as lhs.
1220    if (TheCall->getNumArgs() == 2) {
1221      if (!RHSType->hasIntegerRepresentation() ||
1222          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1223        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1224          << SourceRange(TheCall->getArg(1)->getLocStart(),
1225                         TheCall->getArg(1)->getLocEnd());
1226      numResElements = numElements;
1227    }
1228    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1229      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1230        << SourceRange(TheCall->getArg(0)->getLocStart(),
1231                       TheCall->getArg(1)->getLocEnd());
1232      return ExprError();
1233    } else if (numElements != numResElements) {
1234      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1235      resType = Context.getVectorType(eltType, numResElements,
1236                                      VectorType::GenericVector);
1237    }
1238  }
1239
1240  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1241    if (TheCall->getArg(i)->isTypeDependent() ||
1242        TheCall->getArg(i)->isValueDependent())
1243      continue;
1244
1245    llvm::APSInt Result(32);
1246    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1247      return ExprError(Diag(TheCall->getLocStart(),
1248                  diag::err_shufflevector_nonconstant_argument)
1249                << TheCall->getArg(i)->getSourceRange());
1250
1251    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1252      return ExprError(Diag(TheCall->getLocStart(),
1253                  diag::err_shufflevector_argument_too_large)
1254               << TheCall->getArg(i)->getSourceRange());
1255  }
1256
1257  SmallVector<Expr*, 32> exprs;
1258
1259  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1260    exprs.push_back(TheCall->getArg(i));
1261    TheCall->setArg(i, 0);
1262  }
1263
1264  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
1265                                            exprs.size(), resType,
1266                                            TheCall->getCallee()->getLocStart(),
1267                                            TheCall->getRParenLoc()));
1268}
1269
1270/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1271// This is declared to take (const void*, ...) and can take two
1272// optional constant int args.
1273bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1274  unsigned NumArgs = TheCall->getNumArgs();
1275
1276  if (NumArgs > 3)
1277    return Diag(TheCall->getLocEnd(),
1278             diag::err_typecheck_call_too_many_args_at_most)
1279             << 0 /*function call*/ << 3 << NumArgs
1280             << TheCall->getSourceRange();
1281
1282  // Argument 0 is checked for us and the remaining arguments must be
1283  // constant integers.
1284  for (unsigned i = 1; i != NumArgs; ++i) {
1285    Expr *Arg = TheCall->getArg(i);
1286
1287    llvm::APSInt Result;
1288    if (SemaBuiltinConstantArg(TheCall, i, Result))
1289      return true;
1290
1291    // FIXME: gcc issues a warning and rewrites these to 0. These
1292    // seems especially odd for the third argument since the default
1293    // is 3.
1294    if (i == 1) {
1295      if (Result.getLimitedValue() > 1)
1296        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1297             << "0" << "1" << Arg->getSourceRange();
1298    } else {
1299      if (Result.getLimitedValue() > 3)
1300        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1301            << "0" << "3" << Arg->getSourceRange();
1302    }
1303  }
1304
1305  return false;
1306}
1307
1308/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1309/// TheCall is a constant expression.
1310bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1311                                  llvm::APSInt &Result) {
1312  Expr *Arg = TheCall->getArg(ArgNum);
1313  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1314  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1315
1316  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1317
1318  if (!Arg->isIntegerConstantExpr(Result, Context))
1319    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1320                << FDecl->getDeclName() <<  Arg->getSourceRange();
1321
1322  return false;
1323}
1324
1325/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1326/// int type). This simply type checks that type is one of the defined
1327/// constants (0-3).
1328// For compatibility check 0-3, llvm only handles 0 and 2.
1329bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1330  llvm::APSInt Result;
1331
1332  // Check constant-ness first.
1333  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1334    return true;
1335
1336  Expr *Arg = TheCall->getArg(1);
1337  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1338    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1339             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1340  }
1341
1342  return false;
1343}
1344
1345/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1346/// This checks that val is a constant 1.
1347bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1348  Expr *Arg = TheCall->getArg(1);
1349  llvm::APSInt Result;
1350
1351  // TODO: This is less than ideal. Overload this to take a value.
1352  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1353    return true;
1354
1355  if (Result != 1)
1356    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1357             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1358
1359  return false;
1360}
1361
1362// Handle i > 1 ? "x" : "y", recursively.
1363bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
1364                                  unsigned NumArgs, bool HasVAListArg,
1365                                  unsigned format_idx, unsigned firstDataArg,
1366                                  FormatStringType Type, bool inFunctionCall) {
1367 tryAgain:
1368  if (E->isTypeDependent() || E->isValueDependent())
1369    return false;
1370
1371  E = E->IgnoreParenCasts();
1372
1373  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1374    // Technically -Wformat-nonliteral does not warn about this case.
1375    // The behavior of printf and friends in this case is implementation
1376    // dependent.  Ideally if the format string cannot be null then
1377    // it should have a 'nonnull' attribute in the function prototype.
1378    return true;
1379
1380  switch (E->getStmtClass()) {
1381  case Stmt::BinaryConditionalOperatorClass:
1382  case Stmt::ConditionalOperatorClass: {
1383    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
1384    return SemaCheckStringLiteral(C->getTrueExpr(), Args, NumArgs, HasVAListArg,
1385                                  format_idx, firstDataArg, Type,
1386                                  inFunctionCall)
1387       && SemaCheckStringLiteral(C->getFalseExpr(), Args, NumArgs, HasVAListArg,
1388                                 format_idx, firstDataArg, Type,
1389                                 inFunctionCall);
1390  }
1391
1392  case Stmt::ImplicitCastExprClass: {
1393    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1394    goto tryAgain;
1395  }
1396
1397  case Stmt::OpaqueValueExprClass:
1398    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1399      E = src;
1400      goto tryAgain;
1401    }
1402    return false;
1403
1404  case Stmt::PredefinedExprClass:
1405    // While __func__, etc., are technically not string literals, they
1406    // cannot contain format specifiers and thus are not a security
1407    // liability.
1408    return true;
1409
1410  case Stmt::DeclRefExprClass: {
1411    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1412
1413    // As an exception, do not flag errors for variables binding to
1414    // const string literals.
1415    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1416      bool isConstant = false;
1417      QualType T = DR->getType();
1418
1419      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1420        isConstant = AT->getElementType().isConstant(Context);
1421      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1422        isConstant = T.isConstant(Context) &&
1423                     PT->getPointeeType().isConstant(Context);
1424      } else if (T->isObjCObjectPointerType()) {
1425        // In ObjC, there is usually no "const ObjectPointer" type,
1426        // so don't check if the pointee type is constant.
1427        isConstant = T.isConstant(Context);
1428      }
1429
1430      if (isConstant) {
1431        if (const Expr *Init = VD->getAnyInitializer())
1432          return SemaCheckStringLiteral(Init, Args, NumArgs,
1433                                        HasVAListArg, format_idx, firstDataArg,
1434                                        Type, /*inFunctionCall*/false);
1435      }
1436
1437      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1438      // special check to see if the format string is a function parameter
1439      // of the function calling the printf function.  If the function
1440      // has an attribute indicating it is a printf-like function, then we
1441      // should suppress warnings concerning non-literals being used in a call
1442      // to a vprintf function.  For example:
1443      //
1444      // void
1445      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1446      //      va_list ap;
1447      //      va_start(ap, fmt);
1448      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1449      //      ...
1450      //
1451      if (HasVAListArg) {
1452        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1453          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1454            int PVIndex = PV->getFunctionScopeIndex() + 1;
1455            for (specific_attr_iterator<FormatAttr>
1456                 i = ND->specific_attr_begin<FormatAttr>(),
1457                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1458              FormatAttr *PVFormat = *i;
1459              // adjust for implicit parameter
1460              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1461                if (MD->isInstance())
1462                  ++PVIndex;
1463              // We also check if the formats are compatible.
1464              // We can't pass a 'scanf' string to a 'printf' function.
1465              if (PVIndex == PVFormat->getFormatIdx() &&
1466                  Type == GetFormatStringType(PVFormat))
1467                return true;
1468            }
1469          }
1470        }
1471      }
1472    }
1473
1474    return false;
1475  }
1476
1477  case Stmt::CallExprClass:
1478  case Stmt::CXXMemberCallExprClass: {
1479    const CallExpr *CE = cast<CallExpr>(E);
1480    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1481      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1482        unsigned ArgIndex = FA->getFormatIdx();
1483        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1484          if (MD->isInstance())
1485            --ArgIndex;
1486        const Expr *Arg = CE->getArg(ArgIndex - 1);
1487
1488        return SemaCheckStringLiteral(Arg, Args, NumArgs, HasVAListArg,
1489                                      format_idx, firstDataArg, Type,
1490                                      inFunctionCall);
1491      }
1492    }
1493
1494    return false;
1495  }
1496  case Stmt::ObjCStringLiteralClass:
1497  case Stmt::StringLiteralClass: {
1498    const StringLiteral *StrE = NULL;
1499
1500    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1501      StrE = ObjCFExpr->getString();
1502    else
1503      StrE = cast<StringLiteral>(E);
1504
1505    if (StrE) {
1506      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
1507                        firstDataArg, Type, inFunctionCall);
1508      return true;
1509    }
1510
1511    return false;
1512  }
1513
1514  default:
1515    return false;
1516  }
1517}
1518
1519void
1520Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1521                            const Expr * const *ExprArgs,
1522                            SourceLocation CallSiteLoc) {
1523  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1524                                  e = NonNull->args_end();
1525       i != e; ++i) {
1526    const Expr *ArgExpr = ExprArgs[*i];
1527    if (ArgExpr->isNullPointerConstant(Context,
1528                                       Expr::NPC_ValueDependentIsNotNull))
1529      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1530  }
1531}
1532
1533Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1534  return llvm::StringSwitch<FormatStringType>(Format->getType())
1535  .Case("scanf", FST_Scanf)
1536  .Cases("printf", "printf0", FST_Printf)
1537  .Cases("NSString", "CFString", FST_NSString)
1538  .Case("strftime", FST_Strftime)
1539  .Case("strfmon", FST_Strfmon)
1540  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1541  .Default(FST_Unknown);
1542}
1543
1544/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
1545/// functions) for correct use of format strings.
1546void Sema::CheckFormatArguments(const FormatAttr *Format, CallExpr *TheCall) {
1547  bool IsCXXMember = false;
1548  // The way the format attribute works in GCC, the implicit this argument
1549  // of member functions is counted. However, it doesn't appear in our own
1550  // lists, so decrement format_idx in that case.
1551  IsCXXMember = isa<CXXMemberCallExpr>(TheCall);
1552  CheckFormatArguments(Format, TheCall->getArgs(), TheCall->getNumArgs(),
1553                       IsCXXMember, TheCall->getRParenLoc(),
1554                       TheCall->getCallee()->getSourceRange());
1555}
1556
1557void Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
1558                                unsigned NumArgs, bool IsCXXMember,
1559                                SourceLocation Loc, SourceRange Range) {
1560  bool HasVAListArg = Format->getFirstArg() == 0;
1561  unsigned format_idx = Format->getFormatIdx() - 1;
1562  unsigned firstDataArg = HasVAListArg ? 0 : Format->getFirstArg() - 1;
1563  if (IsCXXMember) {
1564    if (format_idx == 0)
1565      return;
1566    --format_idx;
1567    if(firstDataArg != 0)
1568      --firstDataArg;
1569  }
1570  CheckFormatArguments(Args, NumArgs, HasVAListArg, format_idx,
1571                       firstDataArg, GetFormatStringType(Format), Loc, Range);
1572}
1573
1574void Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
1575                                bool HasVAListArg, unsigned format_idx,
1576                                unsigned firstDataArg, FormatStringType Type,
1577                                SourceLocation Loc, SourceRange Range) {
1578  // CHECK: printf/scanf-like function is called with no format string.
1579  if (format_idx >= NumArgs) {
1580    Diag(Loc, diag::warn_missing_format_string) << Range;
1581    return;
1582  }
1583
1584  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1585
1586  // CHECK: format string is not a string literal.
1587  //
1588  // Dynamically generated format strings are difficult to
1589  // automatically vet at compile time.  Requiring that format strings
1590  // are string literals: (1) permits the checking of format strings by
1591  // the compiler and thereby (2) can practically remove the source of
1592  // many format string exploits.
1593
1594  // Format string can be either ObjC string (e.g. @"%d") or
1595  // C string (e.g. "%d")
1596  // ObjC string uses the same format specifiers as C string, so we can use
1597  // the same format string checking logic for both ObjC and C strings.
1598  if (SemaCheckStringLiteral(OrigFormatExpr, Args, NumArgs, HasVAListArg,
1599                             format_idx, firstDataArg, Type))
1600    return;  // Literal format string found, check done!
1601
1602  // Strftime is particular as it always uses a single 'time' argument,
1603  // so it is safe to pass a non-literal string.
1604  if (Type == FST_Strftime)
1605    return;
1606
1607  // Do not emit diag when the string param is a macro expansion and the
1608  // format is either NSString or CFString. This is a hack to prevent
1609  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1610  // which are usually used in place of NS and CF string literals.
1611  if (Type == FST_NSString && Args[format_idx]->getLocStart().isMacroID())
1612    return;
1613
1614  // If there are no arguments specified, warn with -Wformat-security, otherwise
1615  // warn only with -Wformat-nonliteral.
1616  if (NumArgs == format_idx+1)
1617    Diag(Args[format_idx]->getLocStart(),
1618         diag::warn_format_nonliteral_noargs)
1619      << OrigFormatExpr->getSourceRange();
1620  else
1621    Diag(Args[format_idx]->getLocStart(),
1622         diag::warn_format_nonliteral)
1623           << OrigFormatExpr->getSourceRange();
1624}
1625
1626namespace {
1627class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1628protected:
1629  Sema &S;
1630  const StringLiteral *FExpr;
1631  const Expr *OrigFormatExpr;
1632  const unsigned FirstDataArg;
1633  const unsigned NumDataArgs;
1634  const bool IsObjCLiteral;
1635  const char *Beg; // Start of format string.
1636  const bool HasVAListArg;
1637  const Expr * const *Args;
1638  const unsigned NumArgs;
1639  unsigned FormatIdx;
1640  llvm::BitVector CoveredArgs;
1641  bool usesPositionalArgs;
1642  bool atFirstArg;
1643  bool inFunctionCall;
1644public:
1645  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1646                     const Expr *origFormatExpr, unsigned firstDataArg,
1647                     unsigned numDataArgs, bool isObjCLiteral,
1648                     const char *beg, bool hasVAListArg,
1649                     Expr **args, unsigned numArgs,
1650                     unsigned formatIdx, bool inFunctionCall)
1651    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1652      FirstDataArg(firstDataArg),
1653      NumDataArgs(numDataArgs),
1654      IsObjCLiteral(isObjCLiteral), Beg(beg),
1655      HasVAListArg(hasVAListArg),
1656      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
1657      usesPositionalArgs(false), atFirstArg(true),
1658      inFunctionCall(inFunctionCall) {
1659        CoveredArgs.resize(numDataArgs);
1660        CoveredArgs.reset();
1661      }
1662
1663  void DoneProcessing();
1664
1665  void HandleIncompleteSpecifier(const char *startSpecifier,
1666                                 unsigned specifierLen);
1667
1668  void HandleNonStandardLengthModifier(
1669      const analyze_format_string::LengthModifier &LM,
1670      const char *startSpecifier, unsigned specifierLen);
1671
1672  void HandleNonStandardConversionSpecifier(
1673      const analyze_format_string::ConversionSpecifier &CS,
1674      const char *startSpecifier, unsigned specifierLen);
1675
1676  void HandleNonStandardConversionSpecification(
1677      const analyze_format_string::LengthModifier &LM,
1678      const analyze_format_string::ConversionSpecifier &CS,
1679      const char *startSpecifier, unsigned specifierLen);
1680
1681  virtual void HandlePosition(const char *startPos, unsigned posLen);
1682
1683  virtual void HandleInvalidPosition(const char *startSpecifier,
1684                                     unsigned specifierLen,
1685                                     analyze_format_string::PositionContext p);
1686
1687  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1688
1689  void HandleNullChar(const char *nullCharacter);
1690
1691  template <typename Range>
1692  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1693                                   const Expr *ArgumentExpr,
1694                                   PartialDiagnostic PDiag,
1695                                   SourceLocation StringLoc,
1696                                   bool IsStringLocation, Range StringRange,
1697                                   FixItHint Fixit = FixItHint());
1698
1699protected:
1700  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1701                                        const char *startSpec,
1702                                        unsigned specifierLen,
1703                                        const char *csStart, unsigned csLen);
1704
1705  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
1706                                         const char *startSpec,
1707                                         unsigned specifierLen);
1708
1709  SourceRange getFormatStringRange();
1710  CharSourceRange getSpecifierRange(const char *startSpecifier,
1711                                    unsigned specifierLen);
1712  SourceLocation getLocationOfByte(const char *x);
1713
1714  const Expr *getDataArg(unsigned i) const;
1715
1716  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1717                    const analyze_format_string::ConversionSpecifier &CS,
1718                    const char *startSpecifier, unsigned specifierLen,
1719                    unsigned argIndex);
1720
1721  template <typename Range>
1722  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
1723                            bool IsStringLocation, Range StringRange,
1724                            FixItHint Fixit = FixItHint());
1725
1726  void CheckPositionalAndNonpositionalArgs(
1727      const analyze_format_string::FormatSpecifier *FS);
1728};
1729}
1730
1731SourceRange CheckFormatHandler::getFormatStringRange() {
1732  return OrigFormatExpr->getSourceRange();
1733}
1734
1735CharSourceRange CheckFormatHandler::
1736getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
1737  SourceLocation Start = getLocationOfByte(startSpecifier);
1738  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
1739
1740  // Advance the end SourceLocation by one due to half-open ranges.
1741  End = End.getLocWithOffset(1);
1742
1743  return CharSourceRange::getCharRange(Start, End);
1744}
1745
1746SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
1747  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
1748}
1749
1750void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
1751                                                   unsigned specifierLen){
1752  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
1753                       getLocationOfByte(startSpecifier),
1754                       /*IsStringLocation*/true,
1755                       getSpecifierRange(startSpecifier, specifierLen));
1756}
1757
1758void CheckFormatHandler::HandleNonStandardLengthModifier(
1759    const analyze_format_string::LengthModifier &LM,
1760    const char *startSpecifier, unsigned specifierLen) {
1761  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
1762                       << 0,
1763                       getLocationOfByte(LM.getStart()),
1764                       /*IsStringLocation*/true,
1765                       getSpecifierRange(startSpecifier, specifierLen));
1766}
1767
1768void CheckFormatHandler::HandleNonStandardConversionSpecifier(
1769    const analyze_format_string::ConversionSpecifier &CS,
1770    const char *startSpecifier, unsigned specifierLen) {
1771  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
1772                       << 1,
1773                       getLocationOfByte(CS.getStart()),
1774                       /*IsStringLocation*/true,
1775                       getSpecifierRange(startSpecifier, specifierLen));
1776}
1777
1778void CheckFormatHandler::HandleNonStandardConversionSpecification(
1779    const analyze_format_string::LengthModifier &LM,
1780    const analyze_format_string::ConversionSpecifier &CS,
1781    const char *startSpecifier, unsigned specifierLen) {
1782  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
1783                       << LM.toString() << CS.toString(),
1784                       getLocationOfByte(LM.getStart()),
1785                       /*IsStringLocation*/true,
1786                       getSpecifierRange(startSpecifier, specifierLen));
1787}
1788
1789void CheckFormatHandler::HandlePosition(const char *startPos,
1790                                        unsigned posLen) {
1791  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
1792                               getLocationOfByte(startPos),
1793                               /*IsStringLocation*/true,
1794                               getSpecifierRange(startPos, posLen));
1795}
1796
1797void
1798CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
1799                                     analyze_format_string::PositionContext p) {
1800  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
1801                         << (unsigned) p,
1802                       getLocationOfByte(startPos), /*IsStringLocation*/true,
1803                       getSpecifierRange(startPos, posLen));
1804}
1805
1806void CheckFormatHandler::HandleZeroPosition(const char *startPos,
1807                                            unsigned posLen) {
1808  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
1809                               getLocationOfByte(startPos),
1810                               /*IsStringLocation*/true,
1811                               getSpecifierRange(startPos, posLen));
1812}
1813
1814void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
1815  if (!IsObjCLiteral) {
1816    // The presence of a null character is likely an error.
1817    EmitFormatDiagnostic(
1818      S.PDiag(diag::warn_printf_format_string_contains_null_char),
1819      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
1820      getFormatStringRange());
1821  }
1822}
1823
1824const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
1825  return Args[FirstDataArg + i];
1826}
1827
1828void CheckFormatHandler::DoneProcessing() {
1829    // Does the number of data arguments exceed the number of
1830    // format conversions in the format string?
1831  if (!HasVAListArg) {
1832      // Find any arguments that weren't covered.
1833    CoveredArgs.flip();
1834    signed notCoveredArg = CoveredArgs.find_first();
1835    if (notCoveredArg >= 0) {
1836      assert((unsigned)notCoveredArg < NumDataArgs);
1837      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
1838                           getDataArg((unsigned) notCoveredArg)->getLocStart(),
1839                           /*IsStringLocation*/false, getFormatStringRange());
1840    }
1841  }
1842}
1843
1844bool
1845CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
1846                                                     SourceLocation Loc,
1847                                                     const char *startSpec,
1848                                                     unsigned specifierLen,
1849                                                     const char *csStart,
1850                                                     unsigned csLen) {
1851
1852  bool keepGoing = true;
1853  if (argIndex < NumDataArgs) {
1854    // Consider the argument coverered, even though the specifier doesn't
1855    // make sense.
1856    CoveredArgs.set(argIndex);
1857  }
1858  else {
1859    // If argIndex exceeds the number of data arguments we
1860    // don't issue a warning because that is just a cascade of warnings (and
1861    // they may have intended '%%' anyway). We don't want to continue processing
1862    // the format string after this point, however, as we will like just get
1863    // gibberish when trying to match arguments.
1864    keepGoing = false;
1865  }
1866
1867  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
1868                         << StringRef(csStart, csLen),
1869                       Loc, /*IsStringLocation*/true,
1870                       getSpecifierRange(startSpec, specifierLen));
1871
1872  return keepGoing;
1873}
1874
1875void
1876CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
1877                                                      const char *startSpec,
1878                                                      unsigned specifierLen) {
1879  EmitFormatDiagnostic(
1880    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
1881    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
1882}
1883
1884bool
1885CheckFormatHandler::CheckNumArgs(
1886  const analyze_format_string::FormatSpecifier &FS,
1887  const analyze_format_string::ConversionSpecifier &CS,
1888  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
1889
1890  if (argIndex >= NumDataArgs) {
1891    PartialDiagnostic PDiag = FS.usesPositionalArg()
1892      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
1893           << (argIndex+1) << NumDataArgs)
1894      : S.PDiag(diag::warn_printf_insufficient_data_args);
1895    EmitFormatDiagnostic(
1896      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
1897      getSpecifierRange(startSpecifier, specifierLen));
1898    return false;
1899  }
1900  return true;
1901}
1902
1903template<typename Range>
1904void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
1905                                              SourceLocation Loc,
1906                                              bool IsStringLocation,
1907                                              Range StringRange,
1908                                              FixItHint FixIt) {
1909  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
1910                       Loc, IsStringLocation, StringRange, FixIt);
1911}
1912
1913/// \brief If the format string is not within the funcion call, emit a note
1914/// so that the function call and string are in diagnostic messages.
1915///
1916/// \param inFunctionCall if true, the format string is within the function
1917/// call and only one diagnostic message will be produced.  Otherwise, an
1918/// extra note will be emitted pointing to location of the format string.
1919///
1920/// \param ArgumentExpr the expression that is passed as the format string
1921/// argument in the function call.  Used for getting locations when two
1922/// diagnostics are emitted.
1923///
1924/// \param PDiag the callee should already have provided any strings for the
1925/// diagnostic message.  This function only adds locations and fixits
1926/// to diagnostics.
1927///
1928/// \param Loc primary location for diagnostic.  If two diagnostics are
1929/// required, one will be at Loc and a new SourceLocation will be created for
1930/// the other one.
1931///
1932/// \param IsStringLocation if true, Loc points to the format string should be
1933/// used for the note.  Otherwise, Loc points to the argument list and will
1934/// be used with PDiag.
1935///
1936/// \param StringRange some or all of the string to highlight.  This is
1937/// templated so it can accept either a CharSourceRange or a SourceRange.
1938///
1939/// \param Fixit optional fix it hint for the format string.
1940template<typename Range>
1941void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
1942                                              const Expr *ArgumentExpr,
1943                                              PartialDiagnostic PDiag,
1944                                              SourceLocation Loc,
1945                                              bool IsStringLocation,
1946                                              Range StringRange,
1947                                              FixItHint FixIt) {
1948  if (InFunctionCall)
1949    S.Diag(Loc, PDiag) << StringRange << FixIt;
1950  else {
1951    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
1952      << ArgumentExpr->getSourceRange();
1953    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
1954           diag::note_format_string_defined)
1955      << StringRange << FixIt;
1956  }
1957}
1958
1959//===--- CHECK: Printf format string checking ------------------------------===//
1960
1961namespace {
1962class CheckPrintfHandler : public CheckFormatHandler {
1963public:
1964  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
1965                     const Expr *origFormatExpr, unsigned firstDataArg,
1966                     unsigned numDataArgs, bool isObjCLiteral,
1967                     const char *beg, bool hasVAListArg,
1968                     Expr **Args, unsigned NumArgs,
1969                     unsigned formatIdx, bool inFunctionCall)
1970  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
1971                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
1972                       Args, NumArgs, formatIdx, inFunctionCall) {}
1973
1974
1975  bool HandleInvalidPrintfConversionSpecifier(
1976                                      const analyze_printf::PrintfSpecifier &FS,
1977                                      const char *startSpecifier,
1978                                      unsigned specifierLen);
1979
1980  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
1981                             const char *startSpecifier,
1982                             unsigned specifierLen);
1983
1984  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
1985                    const char *startSpecifier, unsigned specifierLen);
1986  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
1987                           const analyze_printf::OptionalAmount &Amt,
1988                           unsigned type,
1989                           const char *startSpecifier, unsigned specifierLen);
1990  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
1991                  const analyze_printf::OptionalFlag &flag,
1992                  const char *startSpecifier, unsigned specifierLen);
1993  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
1994                         const analyze_printf::OptionalFlag &ignoredFlag,
1995                         const analyze_printf::OptionalFlag &flag,
1996                         const char *startSpecifier, unsigned specifierLen);
1997};
1998}
1999
2000bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2001                                      const analyze_printf::PrintfSpecifier &FS,
2002                                      const char *startSpecifier,
2003                                      unsigned specifierLen) {
2004  const analyze_printf::PrintfConversionSpecifier &CS =
2005    FS.getConversionSpecifier();
2006
2007  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2008                                          getLocationOfByte(CS.getStart()),
2009                                          startSpecifier, specifierLen,
2010                                          CS.getStart(), CS.getLength());
2011}
2012
2013bool CheckPrintfHandler::HandleAmount(
2014                               const analyze_format_string::OptionalAmount &Amt,
2015                               unsigned k, const char *startSpecifier,
2016                               unsigned specifierLen) {
2017
2018  if (Amt.hasDataArgument()) {
2019    if (!HasVAListArg) {
2020      unsigned argIndex = Amt.getArgIndex();
2021      if (argIndex >= NumDataArgs) {
2022        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2023                               << k,
2024                             getLocationOfByte(Amt.getStart()),
2025                             /*IsStringLocation*/true,
2026                             getSpecifierRange(startSpecifier, specifierLen));
2027        // Don't do any more checking.  We will just emit
2028        // spurious errors.
2029        return false;
2030      }
2031
2032      // Type check the data argument.  It should be an 'int'.
2033      // Although not in conformance with C99, we also allow the argument to be
2034      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2035      // doesn't emit a warning for that case.
2036      CoveredArgs.set(argIndex);
2037      const Expr *Arg = getDataArg(argIndex);
2038      QualType T = Arg->getType();
2039
2040      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
2041      assert(ATR.isValid());
2042
2043      if (!ATR.matchesType(S.Context, T)) {
2044        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2045                               << k << ATR.getRepresentativeTypeName(S.Context)
2046                               << T << Arg->getSourceRange(),
2047                             getLocationOfByte(Amt.getStart()),
2048                             /*IsStringLocation*/true,
2049                             getSpecifierRange(startSpecifier, specifierLen));
2050        // Don't do any more checking.  We will just emit
2051        // spurious errors.
2052        return false;
2053      }
2054    }
2055  }
2056  return true;
2057}
2058
2059void CheckPrintfHandler::HandleInvalidAmount(
2060                                      const analyze_printf::PrintfSpecifier &FS,
2061                                      const analyze_printf::OptionalAmount &Amt,
2062                                      unsigned type,
2063                                      const char *startSpecifier,
2064                                      unsigned specifierLen) {
2065  const analyze_printf::PrintfConversionSpecifier &CS =
2066    FS.getConversionSpecifier();
2067
2068  FixItHint fixit =
2069    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2070      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2071                                 Amt.getConstantLength()))
2072      : FixItHint();
2073
2074  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2075                         << type << CS.toString(),
2076                       getLocationOfByte(Amt.getStart()),
2077                       /*IsStringLocation*/true,
2078                       getSpecifierRange(startSpecifier, specifierLen),
2079                       fixit);
2080}
2081
2082void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2083                                    const analyze_printf::OptionalFlag &flag,
2084                                    const char *startSpecifier,
2085                                    unsigned specifierLen) {
2086  // Warn about pointless flag with a fixit removal.
2087  const analyze_printf::PrintfConversionSpecifier &CS =
2088    FS.getConversionSpecifier();
2089  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2090                         << flag.toString() << CS.toString(),
2091                       getLocationOfByte(flag.getPosition()),
2092                       /*IsStringLocation*/true,
2093                       getSpecifierRange(startSpecifier, specifierLen),
2094                       FixItHint::CreateRemoval(
2095                         getSpecifierRange(flag.getPosition(), 1)));
2096}
2097
2098void CheckPrintfHandler::HandleIgnoredFlag(
2099                                const analyze_printf::PrintfSpecifier &FS,
2100                                const analyze_printf::OptionalFlag &ignoredFlag,
2101                                const analyze_printf::OptionalFlag &flag,
2102                                const char *startSpecifier,
2103                                unsigned specifierLen) {
2104  // Warn about ignored flag with a fixit removal.
2105  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2106                         << ignoredFlag.toString() << flag.toString(),
2107                       getLocationOfByte(ignoredFlag.getPosition()),
2108                       /*IsStringLocation*/true,
2109                       getSpecifierRange(startSpecifier, specifierLen),
2110                       FixItHint::CreateRemoval(
2111                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2112}
2113
2114bool
2115CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2116                                            &FS,
2117                                          const char *startSpecifier,
2118                                          unsigned specifierLen) {
2119
2120  using namespace analyze_format_string;
2121  using namespace analyze_printf;
2122  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2123
2124  if (FS.consumesDataArgument()) {
2125    if (atFirstArg) {
2126        atFirstArg = false;
2127        usesPositionalArgs = FS.usesPositionalArg();
2128    }
2129    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2130      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2131                                        startSpecifier, specifierLen);
2132      return false;
2133    }
2134  }
2135
2136  // First check if the field width, precision, and conversion specifier
2137  // have matching data arguments.
2138  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2139                    startSpecifier, specifierLen)) {
2140    return false;
2141  }
2142
2143  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2144                    startSpecifier, specifierLen)) {
2145    return false;
2146  }
2147
2148  if (!CS.consumesDataArgument()) {
2149    // FIXME: Technically specifying a precision or field width here
2150    // makes no sense.  Worth issuing a warning at some point.
2151    return true;
2152  }
2153
2154  // Consume the argument.
2155  unsigned argIndex = FS.getArgIndex();
2156  if (argIndex < NumDataArgs) {
2157    // The check to see if the argIndex is valid will come later.
2158    // We set the bit here because we may exit early from this
2159    // function if we encounter some other error.
2160    CoveredArgs.set(argIndex);
2161  }
2162
2163  // Check for using an Objective-C specific conversion specifier
2164  // in a non-ObjC literal.
2165  if (!IsObjCLiteral && CS.isObjCArg()) {
2166    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2167                                                  specifierLen);
2168  }
2169
2170  // Check for invalid use of field width
2171  if (!FS.hasValidFieldWidth()) {
2172    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2173        startSpecifier, specifierLen);
2174  }
2175
2176  // Check for invalid use of precision
2177  if (!FS.hasValidPrecision()) {
2178    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2179        startSpecifier, specifierLen);
2180  }
2181
2182  // Check each flag does not conflict with any other component.
2183  if (!FS.hasValidThousandsGroupingPrefix())
2184    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2185  if (!FS.hasValidLeadingZeros())
2186    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2187  if (!FS.hasValidPlusPrefix())
2188    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2189  if (!FS.hasValidSpacePrefix())
2190    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2191  if (!FS.hasValidAlternativeForm())
2192    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2193  if (!FS.hasValidLeftJustified())
2194    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2195
2196  // Check that flags are not ignored by another flag
2197  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2198    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2199        startSpecifier, specifierLen);
2200  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2201    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2202            startSpecifier, specifierLen);
2203
2204  // Check the length modifier is valid with the given conversion specifier.
2205  const LengthModifier &LM = FS.getLengthModifier();
2206  if (!FS.hasValidLengthModifier())
2207    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2208                           << LM.toString() << CS.toString(),
2209                         getLocationOfByte(LM.getStart()),
2210                         /*IsStringLocation*/true,
2211                         getSpecifierRange(startSpecifier, specifierLen),
2212                         FixItHint::CreateRemoval(
2213                           getSpecifierRange(LM.getStart(),
2214                                             LM.getLength())));
2215  if (!FS.hasStandardLengthModifier())
2216    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2217  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2218    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2219  if (!FS.hasStandardLengthConversionCombination())
2220    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2221                                             specifierLen);
2222
2223  // Are we using '%n'?
2224  if (CS.getKind() == ConversionSpecifier::nArg) {
2225    // Issue a warning about this being a possible security issue.
2226    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
2227                         getLocationOfByte(CS.getStart()),
2228                         /*IsStringLocation*/true,
2229                         getSpecifierRange(startSpecifier, specifierLen));
2230    // Continue checking the other format specifiers.
2231    return true;
2232  }
2233
2234  // The remaining checks depend on the data arguments.
2235  if (HasVAListArg)
2236    return true;
2237
2238  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2239    return false;
2240
2241  // Now type check the data expression that matches the
2242  // format specifier.
2243  const Expr *Ex = getDataArg(argIndex);
2244  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context,
2245                                                           IsObjCLiteral);
2246  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2247    // Check if we didn't match because of an implicit cast from a 'char'
2248    // or 'short' to an 'int'.  This is done because printf is a varargs
2249    // function.
2250    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
2251      if (ICE->getType() == S.Context.IntTy) {
2252        // All further checking is done on the subexpression.
2253        Ex = ICE->getSubExpr();
2254        if (ATR.matchesType(S.Context, Ex->getType()))
2255          return true;
2256      }
2257
2258    // We may be able to offer a FixItHint if it is a supported type.
2259    PrintfSpecifier fixedFS = FS;
2260    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2261                                   S.Context, IsObjCLiteral);
2262
2263    if (success) {
2264      // Get the fix string from the fixed format specifier
2265      SmallString<128> buf;
2266      llvm::raw_svector_ostream os(buf);
2267      fixedFS.toString(os);
2268
2269      EmitFormatDiagnostic(
2270        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2271          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2272          << Ex->getSourceRange(),
2273        getLocationOfByte(CS.getStart()),
2274        /*IsStringLocation*/true,
2275        getSpecifierRange(startSpecifier, specifierLen),
2276        FixItHint::CreateReplacement(
2277          getSpecifierRange(startSpecifier, specifierLen),
2278          os.str()));
2279    }
2280    else {
2281      EmitFormatDiagnostic(
2282        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2283          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2284          << getSpecifierRange(startSpecifier, specifierLen)
2285          << Ex->getSourceRange(),
2286        getLocationOfByte(CS.getStart()),
2287        true,
2288        getSpecifierRange(startSpecifier, specifierLen));
2289    }
2290  }
2291
2292  return true;
2293}
2294
2295//===--- CHECK: Scanf format string checking ------------------------------===//
2296
2297namespace {
2298class CheckScanfHandler : public CheckFormatHandler {
2299public:
2300  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2301                    const Expr *origFormatExpr, unsigned firstDataArg,
2302                    unsigned numDataArgs, bool isObjCLiteral,
2303                    const char *beg, bool hasVAListArg,
2304                    Expr **Args, unsigned NumArgs,
2305                    unsigned formatIdx, bool inFunctionCall)
2306  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2307                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
2308                       Args, NumArgs, formatIdx, inFunctionCall) {}
2309
2310  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2311                            const char *startSpecifier,
2312                            unsigned specifierLen);
2313
2314  bool HandleInvalidScanfConversionSpecifier(
2315          const analyze_scanf::ScanfSpecifier &FS,
2316          const char *startSpecifier,
2317          unsigned specifierLen);
2318
2319  void HandleIncompleteScanList(const char *start, const char *end);
2320};
2321}
2322
2323void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2324                                                 const char *end) {
2325  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2326                       getLocationOfByte(end), /*IsStringLocation*/true,
2327                       getSpecifierRange(start, end - start));
2328}
2329
2330bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2331                                        const analyze_scanf::ScanfSpecifier &FS,
2332                                        const char *startSpecifier,
2333                                        unsigned specifierLen) {
2334
2335  const analyze_scanf::ScanfConversionSpecifier &CS =
2336    FS.getConversionSpecifier();
2337
2338  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2339                                          getLocationOfByte(CS.getStart()),
2340                                          startSpecifier, specifierLen,
2341                                          CS.getStart(), CS.getLength());
2342}
2343
2344bool CheckScanfHandler::HandleScanfSpecifier(
2345                                       const analyze_scanf::ScanfSpecifier &FS,
2346                                       const char *startSpecifier,
2347                                       unsigned specifierLen) {
2348
2349  using namespace analyze_scanf;
2350  using namespace analyze_format_string;
2351
2352  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2353
2354  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2355  // be used to decide if we are using positional arguments consistently.
2356  if (FS.consumesDataArgument()) {
2357    if (atFirstArg) {
2358      atFirstArg = false;
2359      usesPositionalArgs = FS.usesPositionalArg();
2360    }
2361    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2362      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2363                                        startSpecifier, specifierLen);
2364      return false;
2365    }
2366  }
2367
2368  // Check if the field with is non-zero.
2369  const OptionalAmount &Amt = FS.getFieldWidth();
2370  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2371    if (Amt.getConstantAmount() == 0) {
2372      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2373                                                   Amt.getConstantLength());
2374      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2375                           getLocationOfByte(Amt.getStart()),
2376                           /*IsStringLocation*/true, R,
2377                           FixItHint::CreateRemoval(R));
2378    }
2379  }
2380
2381  if (!FS.consumesDataArgument()) {
2382    // FIXME: Technically specifying a precision or field width here
2383    // makes no sense.  Worth issuing a warning at some point.
2384    return true;
2385  }
2386
2387  // Consume the argument.
2388  unsigned argIndex = FS.getArgIndex();
2389  if (argIndex < NumDataArgs) {
2390      // The check to see if the argIndex is valid will come later.
2391      // We set the bit here because we may exit early from this
2392      // function if we encounter some other error.
2393    CoveredArgs.set(argIndex);
2394  }
2395
2396  // Check the length modifier is valid with the given conversion specifier.
2397  const LengthModifier &LM = FS.getLengthModifier();
2398  if (!FS.hasValidLengthModifier()) {
2399    const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength());
2400    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2401                         << LM.toString() << CS.toString()
2402                         << getSpecifierRange(startSpecifier, specifierLen),
2403                         getLocationOfByte(LM.getStart()),
2404                         /*IsStringLocation*/true, R,
2405                         FixItHint::CreateRemoval(R));
2406  }
2407
2408  if (!FS.hasStandardLengthModifier())
2409    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2410  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2411    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2412  if (!FS.hasStandardLengthConversionCombination())
2413    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2414                                             specifierLen);
2415
2416  // The remaining checks depend on the data arguments.
2417  if (HasVAListArg)
2418    return true;
2419
2420  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2421    return false;
2422
2423  // Check that the argument type matches the format specifier.
2424  const Expr *Ex = getDataArg(argIndex);
2425  const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context);
2426  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2427    ScanfSpecifier fixedFS = FS;
2428    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2429                                   S.Context);
2430
2431    if (success) {
2432      // Get the fix string from the fixed format specifier.
2433      SmallString<128> buf;
2434      llvm::raw_svector_ostream os(buf);
2435      fixedFS.toString(os);
2436
2437      EmitFormatDiagnostic(
2438        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2439          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2440          << Ex->getSourceRange(),
2441        getLocationOfByte(CS.getStart()),
2442        /*IsStringLocation*/true,
2443        getSpecifierRange(startSpecifier, specifierLen),
2444        FixItHint::CreateReplacement(
2445          getSpecifierRange(startSpecifier, specifierLen),
2446          os.str()));
2447    } else {
2448      EmitFormatDiagnostic(
2449        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2450          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2451          << Ex->getSourceRange(),
2452        getLocationOfByte(CS.getStart()),
2453        /*IsStringLocation*/true,
2454        getSpecifierRange(startSpecifier, specifierLen));
2455    }
2456  }
2457
2458  return true;
2459}
2460
2461void Sema::CheckFormatString(const StringLiteral *FExpr,
2462                             const Expr *OrigFormatExpr,
2463                             Expr **Args, unsigned NumArgs,
2464                             bool HasVAListArg, unsigned format_idx,
2465                             unsigned firstDataArg, FormatStringType Type,
2466                             bool inFunctionCall) {
2467
2468  // CHECK: is the format string a wide literal?
2469  if (!FExpr->isAscii()) {
2470    CheckFormatHandler::EmitFormatDiagnostic(
2471      *this, inFunctionCall, Args[format_idx],
2472      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
2473      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2474    return;
2475  }
2476
2477  // Str - The format string.  NOTE: this is NOT null-terminated!
2478  StringRef StrRef = FExpr->getString();
2479  const char *Str = StrRef.data();
2480  unsigned StrLen = StrRef.size();
2481  const unsigned numDataArgs = NumArgs - firstDataArg;
2482
2483  // CHECK: empty format string?
2484  if (StrLen == 0 && numDataArgs > 0) {
2485    CheckFormatHandler::EmitFormatDiagnostic(
2486      *this, inFunctionCall, Args[format_idx],
2487      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
2488      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2489    return;
2490  }
2491
2492  if (Type == FST_Printf || Type == FST_NSString) {
2493    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2494                         numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2495                         Str, HasVAListArg, Args, NumArgs, format_idx,
2496                         inFunctionCall);
2497
2498    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
2499                                                  getLangOpts()))
2500      H.DoneProcessing();
2501  } else if (Type == FST_Scanf) {
2502    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2503                        numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2504                        Str, HasVAListArg, Args, NumArgs, format_idx,
2505                        inFunctionCall);
2506
2507    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
2508                                                 getLangOpts()))
2509      H.DoneProcessing();
2510  } // TODO: handle other formats
2511}
2512
2513//===--- CHECK: Standard memory functions ---------------------------------===//
2514
2515/// \brief Determine whether the given type is a dynamic class type (e.g.,
2516/// whether it has a vtable).
2517static bool isDynamicClassType(QualType T) {
2518  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
2519    if (CXXRecordDecl *Definition = Record->getDefinition())
2520      if (Definition->isDynamicClass())
2521        return true;
2522
2523  return false;
2524}
2525
2526/// \brief If E is a sizeof expression, returns its argument expression,
2527/// otherwise returns NULL.
2528static const Expr *getSizeOfExprArg(const Expr* E) {
2529  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2530      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2531    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
2532      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
2533
2534  return 0;
2535}
2536
2537/// \brief If E is a sizeof expression, returns its argument type.
2538static QualType getSizeOfArgType(const Expr* E) {
2539  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2540      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2541    if (SizeOf->getKind() == clang::UETT_SizeOf)
2542      return SizeOf->getTypeOfArgument();
2543
2544  return QualType();
2545}
2546
2547/// \brief Check for dangerous or invalid arguments to memset().
2548///
2549/// This issues warnings on known problematic, dangerous or unspecified
2550/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
2551/// function calls.
2552///
2553/// \param Call The call expression to diagnose.
2554void Sema::CheckMemaccessArguments(const CallExpr *Call,
2555                                   unsigned BId,
2556                                   IdentifierInfo *FnName) {
2557  assert(BId != 0);
2558
2559  // It is possible to have a non-standard definition of memset.  Validate
2560  // we have enough arguments, and if not, abort further checking.
2561  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
2562  if (Call->getNumArgs() < ExpectedNumArgs)
2563    return;
2564
2565  unsigned LastArg = (BId == Builtin::BImemset ||
2566                      BId == Builtin::BIstrndup ? 1 : 2);
2567  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
2568  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
2569
2570  // We have special checking when the length is a sizeof expression.
2571  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
2572  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
2573  llvm::FoldingSetNodeID SizeOfArgID;
2574
2575  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
2576    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
2577    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
2578
2579    QualType DestTy = Dest->getType();
2580    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
2581      QualType PointeeTy = DestPtrTy->getPointeeType();
2582
2583      // Never warn about void type pointers. This can be used to suppress
2584      // false positives.
2585      if (PointeeTy->isVoidType())
2586        continue;
2587
2588      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
2589      // actually comparing the expressions for equality. Because computing the
2590      // expression IDs can be expensive, we only do this if the diagnostic is
2591      // enabled.
2592      if (SizeOfArg &&
2593          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
2594                                   SizeOfArg->getExprLoc())) {
2595        // We only compute IDs for expressions if the warning is enabled, and
2596        // cache the sizeof arg's ID.
2597        if (SizeOfArgID == llvm::FoldingSetNodeID())
2598          SizeOfArg->Profile(SizeOfArgID, Context, true);
2599        llvm::FoldingSetNodeID DestID;
2600        Dest->Profile(DestID, Context, true);
2601        if (DestID == SizeOfArgID) {
2602          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
2603          //       over sizeof(src) as well.
2604          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
2605          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
2606            if (UnaryOp->getOpcode() == UO_AddrOf)
2607              ActionIdx = 1; // If its an address-of operator, just remove it.
2608          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
2609            ActionIdx = 2; // If the pointee's size is sizeof(char),
2610                           // suggest an explicit length.
2611          unsigned DestSrcSelect =
2612            (BId == Builtin::BIstrndup ? 1 : ArgIdx);
2613          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
2614                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
2615                                << FnName << DestSrcSelect << ActionIdx
2616                                << Dest->getSourceRange()
2617                                << SizeOfArg->getSourceRange());
2618          break;
2619        }
2620      }
2621
2622      // Also check for cases where the sizeof argument is the exact same
2623      // type as the memory argument, and where it points to a user-defined
2624      // record type.
2625      if (SizeOfArgTy != QualType()) {
2626        if (PointeeTy->isRecordType() &&
2627            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
2628          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
2629                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
2630                                << FnName << SizeOfArgTy << ArgIdx
2631                                << PointeeTy << Dest->getSourceRange()
2632                                << LenExpr->getSourceRange());
2633          break;
2634        }
2635      }
2636
2637      // Always complain about dynamic classes.
2638      if (isDynamicClassType(PointeeTy)) {
2639
2640        unsigned OperationType = 0;
2641        // "overwritten" if we're warning about the destination for any call
2642        // but memcmp; otherwise a verb appropriate to the call.
2643        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
2644          if (BId == Builtin::BImemcpy)
2645            OperationType = 1;
2646          else if(BId == Builtin::BImemmove)
2647            OperationType = 2;
2648          else if (BId == Builtin::BImemcmp)
2649            OperationType = 3;
2650        }
2651
2652        DiagRuntimeBehavior(
2653          Dest->getExprLoc(), Dest,
2654          PDiag(diag::warn_dyn_class_memaccess)
2655            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
2656            << FnName << PointeeTy
2657            << OperationType
2658            << Call->getCallee()->getSourceRange());
2659      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
2660               BId != Builtin::BImemset)
2661        DiagRuntimeBehavior(
2662          Dest->getExprLoc(), Dest,
2663          PDiag(diag::warn_arc_object_memaccess)
2664            << ArgIdx << FnName << PointeeTy
2665            << Call->getCallee()->getSourceRange());
2666      else
2667        continue;
2668
2669      DiagRuntimeBehavior(
2670        Dest->getExprLoc(), Dest,
2671        PDiag(diag::note_bad_memaccess_silence)
2672          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
2673      break;
2674    }
2675  }
2676}
2677
2678// A little helper routine: ignore addition and subtraction of integer literals.
2679// This intentionally does not ignore all integer constant expressions because
2680// we don't want to remove sizeof().
2681static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
2682  Ex = Ex->IgnoreParenCasts();
2683
2684  for (;;) {
2685    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
2686    if (!BO || !BO->isAdditiveOp())
2687      break;
2688
2689    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
2690    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
2691
2692    if (isa<IntegerLiteral>(RHS))
2693      Ex = LHS;
2694    else if (isa<IntegerLiteral>(LHS))
2695      Ex = RHS;
2696    else
2697      break;
2698  }
2699
2700  return Ex;
2701}
2702
2703// Warn if the user has made the 'size' argument to strlcpy or strlcat
2704// be the size of the source, instead of the destination.
2705void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
2706                                    IdentifierInfo *FnName) {
2707
2708  // Don't crash if the user has the wrong number of arguments
2709  if (Call->getNumArgs() != 3)
2710    return;
2711
2712  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
2713  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
2714  const Expr *CompareWithSrc = NULL;
2715
2716  // Look for 'strlcpy(dst, x, sizeof(x))'
2717  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
2718    CompareWithSrc = Ex;
2719  else {
2720    // Look for 'strlcpy(dst, x, strlen(x))'
2721    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
2722      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
2723          && SizeCall->getNumArgs() == 1)
2724        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
2725    }
2726  }
2727
2728  if (!CompareWithSrc)
2729    return;
2730
2731  // Determine if the argument to sizeof/strlen is equal to the source
2732  // argument.  In principle there's all kinds of things you could do
2733  // here, for instance creating an == expression and evaluating it with
2734  // EvaluateAsBooleanCondition, but this uses a more direct technique:
2735  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
2736  if (!SrcArgDRE)
2737    return;
2738
2739  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
2740  if (!CompareWithSrcDRE ||
2741      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
2742    return;
2743
2744  const Expr *OriginalSizeArg = Call->getArg(2);
2745  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
2746    << OriginalSizeArg->getSourceRange() << FnName;
2747
2748  // Output a FIXIT hint if the destination is an array (rather than a
2749  // pointer to an array).  This could be enhanced to handle some
2750  // pointers if we know the actual size, like if DstArg is 'array+2'
2751  // we could say 'sizeof(array)-2'.
2752  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
2753  QualType DstArgTy = DstArg->getType();
2754
2755  // Only handle constant-sized or VLAs, but not flexible members.
2756  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2757    // Only issue the FIXIT for arrays of size > 1.
2758    if (CAT->getSize().getSExtValue() <= 1)
2759      return;
2760  } else if (!DstArgTy->isVariableArrayType()) {
2761    return;
2762  }
2763
2764  SmallString<128> sizeString;
2765  llvm::raw_svector_ostream OS(sizeString);
2766  OS << "sizeof(";
2767  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2768  OS << ")";
2769
2770  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
2771    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
2772                                    OS.str());
2773}
2774
2775/// Check if two expressions refer to the same declaration.
2776static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
2777  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
2778    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
2779      return D1->getDecl() == D2->getDecl();
2780  return false;
2781}
2782
2783static const Expr *getStrlenExprArg(const Expr *E) {
2784  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
2785    const FunctionDecl *FD = CE->getDirectCallee();
2786    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
2787      return 0;
2788    return CE->getArg(0)->IgnoreParenCasts();
2789  }
2790  return 0;
2791}
2792
2793// Warn on anti-patterns as the 'size' argument to strncat.
2794// The correct size argument should look like following:
2795//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
2796void Sema::CheckStrncatArguments(const CallExpr *CE,
2797                                 IdentifierInfo *FnName) {
2798  // Don't crash if the user has the wrong number of arguments.
2799  if (CE->getNumArgs() < 3)
2800    return;
2801  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
2802  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
2803  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
2804
2805  // Identify common expressions, which are wrongly used as the size argument
2806  // to strncat and may lead to buffer overflows.
2807  unsigned PatternType = 0;
2808  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
2809    // - sizeof(dst)
2810    if (referToTheSameDecl(SizeOfArg, DstArg))
2811      PatternType = 1;
2812    // - sizeof(src)
2813    else if (referToTheSameDecl(SizeOfArg, SrcArg))
2814      PatternType = 2;
2815  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
2816    if (BE->getOpcode() == BO_Sub) {
2817      const Expr *L = BE->getLHS()->IgnoreParenCasts();
2818      const Expr *R = BE->getRHS()->IgnoreParenCasts();
2819      // - sizeof(dst) - strlen(dst)
2820      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
2821          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
2822        PatternType = 1;
2823      // - sizeof(src) - (anything)
2824      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
2825        PatternType = 2;
2826    }
2827  }
2828
2829  if (PatternType == 0)
2830    return;
2831
2832  // Generate the diagnostic.
2833  SourceLocation SL = LenArg->getLocStart();
2834  SourceRange SR = LenArg->getSourceRange();
2835  SourceManager &SM  = PP.getSourceManager();
2836
2837  // If the function is defined as a builtin macro, do not show macro expansion.
2838  if (SM.isMacroArgExpansion(SL)) {
2839    SL = SM.getSpellingLoc(SL);
2840    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
2841                     SM.getSpellingLoc(SR.getEnd()));
2842  }
2843
2844  if (PatternType == 1)
2845    Diag(SL, diag::warn_strncat_large_size) << SR;
2846  else
2847    Diag(SL, diag::warn_strncat_src_size) << SR;
2848
2849  // Output a FIXIT hint if the destination is an array (rather than a
2850  // pointer to an array).  This could be enhanced to handle some
2851  // pointers if we know the actual size, like if DstArg is 'array+2'
2852  // we could say 'sizeof(array)-2'.
2853  QualType DstArgTy = DstArg->getType();
2854
2855  // Only handle constant-sized or VLAs, but not flexible members.
2856  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2857    // Only issue the FIXIT for arrays of size > 1.
2858    if (CAT->getSize().getSExtValue() <= 1)
2859      return;
2860  } else if (!DstArgTy->isVariableArrayType()) {
2861    return;
2862  }
2863
2864  SmallString<128> sizeString;
2865  llvm::raw_svector_ostream OS(sizeString);
2866  OS << "sizeof(";
2867  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2868  OS << ") - ";
2869  OS << "strlen(";
2870  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2871  OS << ") - 1";
2872
2873  Diag(SL, diag::note_strncat_wrong_size)
2874    << FixItHint::CreateReplacement(SR, OS.str());
2875}
2876
2877//===--- CHECK: Return Address of Stack Variable --------------------------===//
2878
2879static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars);
2880static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars);
2881
2882/// CheckReturnStackAddr - Check if a return statement returns the address
2883///   of a stack variable.
2884void
2885Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
2886                           SourceLocation ReturnLoc) {
2887
2888  Expr *stackE = 0;
2889  SmallVector<DeclRefExpr *, 8> refVars;
2890
2891  // Perform checking for returned stack addresses, local blocks,
2892  // label addresses or references to temporaries.
2893  if (lhsType->isPointerType() ||
2894      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
2895    stackE = EvalAddr(RetValExp, refVars);
2896  } else if (lhsType->isReferenceType()) {
2897    stackE = EvalVal(RetValExp, refVars);
2898  }
2899
2900  if (stackE == 0)
2901    return; // Nothing suspicious was found.
2902
2903  SourceLocation diagLoc;
2904  SourceRange diagRange;
2905  if (refVars.empty()) {
2906    diagLoc = stackE->getLocStart();
2907    diagRange = stackE->getSourceRange();
2908  } else {
2909    // We followed through a reference variable. 'stackE' contains the
2910    // problematic expression but we will warn at the return statement pointing
2911    // at the reference variable. We will later display the "trail" of
2912    // reference variables using notes.
2913    diagLoc = refVars[0]->getLocStart();
2914    diagRange = refVars[0]->getSourceRange();
2915  }
2916
2917  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
2918    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
2919                                             : diag::warn_ret_stack_addr)
2920     << DR->getDecl()->getDeclName() << diagRange;
2921  } else if (isa<BlockExpr>(stackE)) { // local block.
2922    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
2923  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
2924    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
2925  } else { // local temporary.
2926    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
2927                                             : diag::warn_ret_local_temp_addr)
2928     << diagRange;
2929  }
2930
2931  // Display the "trail" of reference variables that we followed until we
2932  // found the problematic expression using notes.
2933  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
2934    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
2935    // If this var binds to another reference var, show the range of the next
2936    // var, otherwise the var binds to the problematic expression, in which case
2937    // show the range of the expression.
2938    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
2939                                  : stackE->getSourceRange();
2940    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
2941      << VD->getDeclName() << range;
2942  }
2943}
2944
2945/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
2946///  check if the expression in a return statement evaluates to an address
2947///  to a location on the stack, a local block, an address of a label, or a
2948///  reference to local temporary. The recursion is used to traverse the
2949///  AST of the return expression, with recursion backtracking when we
2950///  encounter a subexpression that (1) clearly does not lead to one of the
2951///  above problematic expressions (2) is something we cannot determine leads to
2952///  a problematic expression based on such local checking.
2953///
2954///  Both EvalAddr and EvalVal follow through reference variables to evaluate
2955///  the expression that they point to. Such variables are added to the
2956///  'refVars' vector so that we know what the reference variable "trail" was.
2957///
2958///  EvalAddr processes expressions that are pointers that are used as
2959///  references (and not L-values).  EvalVal handles all other values.
2960///  At the base case of the recursion is a check for the above problematic
2961///  expressions.
2962///
2963///  This implementation handles:
2964///
2965///   * pointer-to-pointer casts
2966///   * implicit conversions from array references to pointers
2967///   * taking the address of fields
2968///   * arbitrary interplay between "&" and "*" operators
2969///   * pointer arithmetic from an address of a stack variable
2970///   * taking the address of an array element where the array is on the stack
2971static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
2972  if (E->isTypeDependent())
2973      return NULL;
2974
2975  // We should only be called for evaluating pointer expressions.
2976  assert((E->getType()->isAnyPointerType() ||
2977          E->getType()->isBlockPointerType() ||
2978          E->getType()->isObjCQualifiedIdType()) &&
2979         "EvalAddr only works on pointers");
2980
2981  E = E->IgnoreParens();
2982
2983  // Our "symbolic interpreter" is just a dispatch off the currently
2984  // viewed AST node.  We then recursively traverse the AST by calling
2985  // EvalAddr and EvalVal appropriately.
2986  switch (E->getStmtClass()) {
2987  case Stmt::DeclRefExprClass: {
2988    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2989
2990    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2991      // If this is a reference variable, follow through to the expression that
2992      // it points to.
2993      if (V->hasLocalStorage() &&
2994          V->getType()->isReferenceType() && V->hasInit()) {
2995        // Add the reference variable to the "trail".
2996        refVars.push_back(DR);
2997        return EvalAddr(V->getInit(), refVars);
2998      }
2999
3000    return NULL;
3001  }
3002
3003  case Stmt::UnaryOperatorClass: {
3004    // The only unary operator that make sense to handle here
3005    // is AddrOf.  All others don't make sense as pointers.
3006    UnaryOperator *U = cast<UnaryOperator>(E);
3007
3008    if (U->getOpcode() == UO_AddrOf)
3009      return EvalVal(U->getSubExpr(), refVars);
3010    else
3011      return NULL;
3012  }
3013
3014  case Stmt::BinaryOperatorClass: {
3015    // Handle pointer arithmetic.  All other binary operators are not valid
3016    // in this context.
3017    BinaryOperator *B = cast<BinaryOperator>(E);
3018    BinaryOperatorKind op = B->getOpcode();
3019
3020    if (op != BO_Add && op != BO_Sub)
3021      return NULL;
3022
3023    Expr *Base = B->getLHS();
3024
3025    // Determine which argument is the real pointer base.  It could be
3026    // the RHS argument instead of the LHS.
3027    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3028
3029    assert (Base->getType()->isPointerType());
3030    return EvalAddr(Base, refVars);
3031  }
3032
3033  // For conditional operators we need to see if either the LHS or RHS are
3034  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3035  case Stmt::ConditionalOperatorClass: {
3036    ConditionalOperator *C = cast<ConditionalOperator>(E);
3037
3038    // Handle the GNU extension for missing LHS.
3039    if (Expr *lhsExpr = C->getLHS()) {
3040    // In C++, we can have a throw-expression, which has 'void' type.
3041      if (!lhsExpr->getType()->isVoidType())
3042        if (Expr* LHS = EvalAddr(lhsExpr, refVars))
3043          return LHS;
3044    }
3045
3046    // In C++, we can have a throw-expression, which has 'void' type.
3047    if (C->getRHS()->getType()->isVoidType())
3048      return NULL;
3049
3050    return EvalAddr(C->getRHS(), refVars);
3051  }
3052
3053  case Stmt::BlockExprClass:
3054    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3055      return E; // local block.
3056    return NULL;
3057
3058  case Stmt::AddrLabelExprClass:
3059    return E; // address of label.
3060
3061  case Stmt::ExprWithCleanupsClass:
3062    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
3063
3064  // For casts, we need to handle conversions from arrays to
3065  // pointer values, and pointer-to-pointer conversions.
3066  case Stmt::ImplicitCastExprClass:
3067  case Stmt::CStyleCastExprClass:
3068  case Stmt::CXXFunctionalCastExprClass:
3069  case Stmt::ObjCBridgedCastExprClass:
3070  case Stmt::CXXStaticCastExprClass:
3071  case Stmt::CXXDynamicCastExprClass:
3072  case Stmt::CXXConstCastExprClass:
3073  case Stmt::CXXReinterpretCastExprClass: {
3074    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3075    switch (cast<CastExpr>(E)->getCastKind()) {
3076    case CK_BitCast:
3077    case CK_LValueToRValue:
3078    case CK_NoOp:
3079    case CK_BaseToDerived:
3080    case CK_DerivedToBase:
3081    case CK_UncheckedDerivedToBase:
3082    case CK_Dynamic:
3083    case CK_CPointerToObjCPointerCast:
3084    case CK_BlockPointerToObjCPointerCast:
3085    case CK_AnyPointerToBlockPointerCast:
3086      return EvalAddr(SubExpr, refVars);
3087
3088    case CK_ArrayToPointerDecay:
3089      return EvalVal(SubExpr, refVars);
3090
3091    default:
3092      return 0;
3093    }
3094  }
3095
3096  case Stmt::MaterializeTemporaryExprClass:
3097    if (Expr *Result = EvalAddr(
3098                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3099                                refVars))
3100      return Result;
3101
3102    return E;
3103
3104  // Everything else: we simply don't reason about them.
3105  default:
3106    return NULL;
3107  }
3108}
3109
3110
3111///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3112///   See the comments for EvalAddr for more details.
3113static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
3114do {
3115  // We should only be called for evaluating non-pointer expressions, or
3116  // expressions with a pointer type that are not used as references but instead
3117  // are l-values (e.g., DeclRefExpr with a pointer type).
3118
3119  // Our "symbolic interpreter" is just a dispatch off the currently
3120  // viewed AST node.  We then recursively traverse the AST by calling
3121  // EvalAddr and EvalVal appropriately.
3122
3123  E = E->IgnoreParens();
3124  switch (E->getStmtClass()) {
3125  case Stmt::ImplicitCastExprClass: {
3126    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3127    if (IE->getValueKind() == VK_LValue) {
3128      E = IE->getSubExpr();
3129      continue;
3130    }
3131    return NULL;
3132  }
3133
3134  case Stmt::ExprWithCleanupsClass:
3135    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
3136
3137  case Stmt::DeclRefExprClass: {
3138    // When we hit a DeclRefExpr we are looking at code that refers to a
3139    // variable's name. If it's not a reference variable we check if it has
3140    // local storage within the function, and if so, return the expression.
3141    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3142
3143    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3144      if (V->hasLocalStorage()) {
3145        if (!V->getType()->isReferenceType())
3146          return DR;
3147
3148        // Reference variable, follow through to the expression that
3149        // it points to.
3150        if (V->hasInit()) {
3151          // Add the reference variable to the "trail".
3152          refVars.push_back(DR);
3153          return EvalVal(V->getInit(), refVars);
3154        }
3155      }
3156
3157    return NULL;
3158  }
3159
3160  case Stmt::UnaryOperatorClass: {
3161    // The only unary operator that make sense to handle here
3162    // is Deref.  All others don't resolve to a "name."  This includes
3163    // handling all sorts of rvalues passed to a unary operator.
3164    UnaryOperator *U = cast<UnaryOperator>(E);
3165
3166    if (U->getOpcode() == UO_Deref)
3167      return EvalAddr(U->getSubExpr(), refVars);
3168
3169    return NULL;
3170  }
3171
3172  case Stmt::ArraySubscriptExprClass: {
3173    // Array subscripts are potential references to data on the stack.  We
3174    // retrieve the DeclRefExpr* for the array variable if it indeed
3175    // has local storage.
3176    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars);
3177  }
3178
3179  case Stmt::ConditionalOperatorClass: {
3180    // For conditional operators we need to see if either the LHS or RHS are
3181    // non-NULL Expr's.  If one is non-NULL, we return it.
3182    ConditionalOperator *C = cast<ConditionalOperator>(E);
3183
3184    // Handle the GNU extension for missing LHS.
3185    if (Expr *lhsExpr = C->getLHS())
3186      if (Expr *LHS = EvalVal(lhsExpr, refVars))
3187        return LHS;
3188
3189    return EvalVal(C->getRHS(), refVars);
3190  }
3191
3192  // Accesses to members are potential references to data on the stack.
3193  case Stmt::MemberExprClass: {
3194    MemberExpr *M = cast<MemberExpr>(E);
3195
3196    // Check for indirect access.  We only want direct field accesses.
3197    if (M->isArrow())
3198      return NULL;
3199
3200    // Check whether the member type is itself a reference, in which case
3201    // we're not going to refer to the member, but to what the member refers to.
3202    if (M->getMemberDecl()->getType()->isReferenceType())
3203      return NULL;
3204
3205    return EvalVal(M->getBase(), refVars);
3206  }
3207
3208  case Stmt::MaterializeTemporaryExprClass:
3209    if (Expr *Result = EvalVal(
3210                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3211                               refVars))
3212      return Result;
3213
3214    return E;
3215
3216  default:
3217    // Check that we don't return or take the address of a reference to a
3218    // temporary. This is only useful in C++.
3219    if (!E->isTypeDependent() && E->isRValue())
3220      return E;
3221
3222    // Everything else: we simply don't reason about them.
3223    return NULL;
3224  }
3225} while (true);
3226}
3227
3228//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3229
3230/// Check for comparisons of floating point operands using != and ==.
3231/// Issue a warning if these are no self-comparisons, as they are not likely
3232/// to do what the programmer intended.
3233void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3234  bool EmitWarning = true;
3235
3236  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3237  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3238
3239  // Special case: check for x == x (which is OK).
3240  // Do not emit warnings for such cases.
3241  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3242    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3243      if (DRL->getDecl() == DRR->getDecl())
3244        EmitWarning = false;
3245
3246
3247  // Special case: check for comparisons against literals that can be exactly
3248  //  represented by APFloat.  In such cases, do not emit a warning.  This
3249  //  is a heuristic: often comparison against such literals are used to
3250  //  detect if a value in a variable has not changed.  This clearly can
3251  //  lead to false negatives.
3252  if (EmitWarning) {
3253    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3254      if (FLL->isExact())
3255        EmitWarning = false;
3256    } else
3257      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
3258        if (FLR->isExact())
3259          EmitWarning = false;
3260    }
3261  }
3262
3263  // Check for comparisons with builtin types.
3264  if (EmitWarning)
3265    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3266      if (CL->isBuiltinCall())
3267        EmitWarning = false;
3268
3269  if (EmitWarning)
3270    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3271      if (CR->isBuiltinCall())
3272        EmitWarning = false;
3273
3274  // Emit the diagnostic.
3275  if (EmitWarning)
3276    Diag(Loc, diag::warn_floatingpoint_eq)
3277      << LHS->getSourceRange() << RHS->getSourceRange();
3278}
3279
3280//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3281//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3282
3283namespace {
3284
3285/// Structure recording the 'active' range of an integer-valued
3286/// expression.
3287struct IntRange {
3288  /// The number of bits active in the int.
3289  unsigned Width;
3290
3291  /// True if the int is known not to have negative values.
3292  bool NonNegative;
3293
3294  IntRange(unsigned Width, bool NonNegative)
3295    : Width(Width), NonNegative(NonNegative)
3296  {}
3297
3298  /// Returns the range of the bool type.
3299  static IntRange forBoolType() {
3300    return IntRange(1, true);
3301  }
3302
3303  /// Returns the range of an opaque value of the given integral type.
3304  static IntRange forValueOfType(ASTContext &C, QualType T) {
3305    return forValueOfCanonicalType(C,
3306                          T->getCanonicalTypeInternal().getTypePtr());
3307  }
3308
3309  /// Returns the range of an opaque value of a canonical integral type.
3310  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3311    assert(T->isCanonicalUnqualified());
3312
3313    if (const VectorType *VT = dyn_cast<VectorType>(T))
3314      T = VT->getElementType().getTypePtr();
3315    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3316      T = CT->getElementType().getTypePtr();
3317
3318    // For enum types, use the known bit width of the enumerators.
3319    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3320      EnumDecl *Enum = ET->getDecl();
3321      if (!Enum->isCompleteDefinition())
3322        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3323
3324      unsigned NumPositive = Enum->getNumPositiveBits();
3325      unsigned NumNegative = Enum->getNumNegativeBits();
3326
3327      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3328    }
3329
3330    const BuiltinType *BT = cast<BuiltinType>(T);
3331    assert(BT->isInteger());
3332
3333    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3334  }
3335
3336  /// Returns the "target" range of a canonical integral type, i.e.
3337  /// the range of values expressible in the type.
3338  ///
3339  /// This matches forValueOfCanonicalType except that enums have the
3340  /// full range of their type, not the range of their enumerators.
3341  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3342    assert(T->isCanonicalUnqualified());
3343
3344    if (const VectorType *VT = dyn_cast<VectorType>(T))
3345      T = VT->getElementType().getTypePtr();
3346    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3347      T = CT->getElementType().getTypePtr();
3348    if (const EnumType *ET = dyn_cast<EnumType>(T))
3349      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3350
3351    const BuiltinType *BT = cast<BuiltinType>(T);
3352    assert(BT->isInteger());
3353
3354    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3355  }
3356
3357  /// Returns the supremum of two ranges: i.e. their conservative merge.
3358  static IntRange join(IntRange L, IntRange R) {
3359    return IntRange(std::max(L.Width, R.Width),
3360                    L.NonNegative && R.NonNegative);
3361  }
3362
3363  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3364  static IntRange meet(IntRange L, IntRange R) {
3365    return IntRange(std::min(L.Width, R.Width),
3366                    L.NonNegative || R.NonNegative);
3367  }
3368};
3369
3370static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
3371                              unsigned MaxWidth) {
3372  if (value.isSigned() && value.isNegative())
3373    return IntRange(value.getMinSignedBits(), false);
3374
3375  if (value.getBitWidth() > MaxWidth)
3376    value = value.trunc(MaxWidth);
3377
3378  // isNonNegative() just checks the sign bit without considering
3379  // signedness.
3380  return IntRange(value.getActiveBits(), true);
3381}
3382
3383static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3384                              unsigned MaxWidth) {
3385  if (result.isInt())
3386    return GetValueRange(C, result.getInt(), MaxWidth);
3387
3388  if (result.isVector()) {
3389    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3390    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3391      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3392      R = IntRange::join(R, El);
3393    }
3394    return R;
3395  }
3396
3397  if (result.isComplexInt()) {
3398    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3399    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3400    return IntRange::join(R, I);
3401  }
3402
3403  // This can happen with lossless casts to intptr_t of "based" lvalues.
3404  // Assume it might use arbitrary bits.
3405  // FIXME: The only reason we need to pass the type in here is to get
3406  // the sign right on this one case.  It would be nice if APValue
3407  // preserved this.
3408  assert(result.isLValue() || result.isAddrLabelDiff());
3409  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
3410}
3411
3412/// Pseudo-evaluate the given integer expression, estimating the
3413/// range of values it might take.
3414///
3415/// \param MaxWidth - the width to which the value will be truncated
3416static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
3417  E = E->IgnoreParens();
3418
3419  // Try a full evaluation first.
3420  Expr::EvalResult result;
3421  if (E->EvaluateAsRValue(result, C))
3422    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
3423
3424  // I think we only want to look through implicit casts here; if the
3425  // user has an explicit widening cast, we should treat the value as
3426  // being of the new, wider type.
3427  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
3428    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
3429      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
3430
3431    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
3432
3433    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
3434
3435    // Assume that non-integer casts can span the full range of the type.
3436    if (!isIntegerCast)
3437      return OutputTypeRange;
3438
3439    IntRange SubRange
3440      = GetExprRange(C, CE->getSubExpr(),
3441                     std::min(MaxWidth, OutputTypeRange.Width));
3442
3443    // Bail out if the subexpr's range is as wide as the cast type.
3444    if (SubRange.Width >= OutputTypeRange.Width)
3445      return OutputTypeRange;
3446
3447    // Otherwise, we take the smaller width, and we're non-negative if
3448    // either the output type or the subexpr is.
3449    return IntRange(SubRange.Width,
3450                    SubRange.NonNegative || OutputTypeRange.NonNegative);
3451  }
3452
3453  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3454    // If we can fold the condition, just take that operand.
3455    bool CondResult;
3456    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
3457      return GetExprRange(C, CondResult ? CO->getTrueExpr()
3458                                        : CO->getFalseExpr(),
3459                          MaxWidth);
3460
3461    // Otherwise, conservatively merge.
3462    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
3463    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
3464    return IntRange::join(L, R);
3465  }
3466
3467  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3468    switch (BO->getOpcode()) {
3469
3470    // Boolean-valued operations are single-bit and positive.
3471    case BO_LAnd:
3472    case BO_LOr:
3473    case BO_LT:
3474    case BO_GT:
3475    case BO_LE:
3476    case BO_GE:
3477    case BO_EQ:
3478    case BO_NE:
3479      return IntRange::forBoolType();
3480
3481    // The type of the assignments is the type of the LHS, so the RHS
3482    // is not necessarily the same type.
3483    case BO_MulAssign:
3484    case BO_DivAssign:
3485    case BO_RemAssign:
3486    case BO_AddAssign:
3487    case BO_SubAssign:
3488    case BO_XorAssign:
3489    case BO_OrAssign:
3490      // TODO: bitfields?
3491      return IntRange::forValueOfType(C, E->getType());
3492
3493    // Simple assignments just pass through the RHS, which will have
3494    // been coerced to the LHS type.
3495    case BO_Assign:
3496      // TODO: bitfields?
3497      return GetExprRange(C, BO->getRHS(), MaxWidth);
3498
3499    // Operations with opaque sources are black-listed.
3500    case BO_PtrMemD:
3501    case BO_PtrMemI:
3502      return IntRange::forValueOfType(C, E->getType());
3503
3504    // Bitwise-and uses the *infinum* of the two source ranges.
3505    case BO_And:
3506    case BO_AndAssign:
3507      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
3508                            GetExprRange(C, BO->getRHS(), MaxWidth));
3509
3510    // Left shift gets black-listed based on a judgement call.
3511    case BO_Shl:
3512      // ...except that we want to treat '1 << (blah)' as logically
3513      // positive.  It's an important idiom.
3514      if (IntegerLiteral *I
3515            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
3516        if (I->getValue() == 1) {
3517          IntRange R = IntRange::forValueOfType(C, E->getType());
3518          return IntRange(R.Width, /*NonNegative*/ true);
3519        }
3520      }
3521      // fallthrough
3522
3523    case BO_ShlAssign:
3524      return IntRange::forValueOfType(C, E->getType());
3525
3526    // Right shift by a constant can narrow its left argument.
3527    case BO_Shr:
3528    case BO_ShrAssign: {
3529      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3530
3531      // If the shift amount is a positive constant, drop the width by
3532      // that much.
3533      llvm::APSInt shift;
3534      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
3535          shift.isNonNegative()) {
3536        unsigned zext = shift.getZExtValue();
3537        if (zext >= L.Width)
3538          L.Width = (L.NonNegative ? 0 : 1);
3539        else
3540          L.Width -= zext;
3541      }
3542
3543      return L;
3544    }
3545
3546    // Comma acts as its right operand.
3547    case BO_Comma:
3548      return GetExprRange(C, BO->getRHS(), MaxWidth);
3549
3550    // Black-list pointer subtractions.
3551    case BO_Sub:
3552      if (BO->getLHS()->getType()->isPointerType())
3553        return IntRange::forValueOfType(C, E->getType());
3554      break;
3555
3556    // The width of a division result is mostly determined by the size
3557    // of the LHS.
3558    case BO_Div: {
3559      // Don't 'pre-truncate' the operands.
3560      unsigned opWidth = C.getIntWidth(E->getType());
3561      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3562
3563      // If the divisor is constant, use that.
3564      llvm::APSInt divisor;
3565      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
3566        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
3567        if (log2 >= L.Width)
3568          L.Width = (L.NonNegative ? 0 : 1);
3569        else
3570          L.Width = std::min(L.Width - log2, MaxWidth);
3571        return L;
3572      }
3573
3574      // Otherwise, just use the LHS's width.
3575      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3576      return IntRange(L.Width, L.NonNegative && R.NonNegative);
3577    }
3578
3579    // The result of a remainder can't be larger than the result of
3580    // either side.
3581    case BO_Rem: {
3582      // Don't 'pre-truncate' the operands.
3583      unsigned opWidth = C.getIntWidth(E->getType());
3584      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3585      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3586
3587      IntRange meet = IntRange::meet(L, R);
3588      meet.Width = std::min(meet.Width, MaxWidth);
3589      return meet;
3590    }
3591
3592    // The default behavior is okay for these.
3593    case BO_Mul:
3594    case BO_Add:
3595    case BO_Xor:
3596    case BO_Or:
3597      break;
3598    }
3599
3600    // The default case is to treat the operation as if it were closed
3601    // on the narrowest type that encompasses both operands.
3602    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3603    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
3604    return IntRange::join(L, R);
3605  }
3606
3607  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
3608    switch (UO->getOpcode()) {
3609    // Boolean-valued operations are white-listed.
3610    case UO_LNot:
3611      return IntRange::forBoolType();
3612
3613    // Operations with opaque sources are black-listed.
3614    case UO_Deref:
3615    case UO_AddrOf: // should be impossible
3616      return IntRange::forValueOfType(C, E->getType());
3617
3618    default:
3619      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
3620    }
3621  }
3622
3623  if (dyn_cast<OffsetOfExpr>(E)) {
3624    IntRange::forValueOfType(C, E->getType());
3625  }
3626
3627  if (FieldDecl *BitField = E->getBitField())
3628    return IntRange(BitField->getBitWidthValue(C),
3629                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
3630
3631  return IntRange::forValueOfType(C, E->getType());
3632}
3633
3634static IntRange GetExprRange(ASTContext &C, Expr *E) {
3635  return GetExprRange(C, E, C.getIntWidth(E->getType()));
3636}
3637
3638/// Checks whether the given value, which currently has the given
3639/// source semantics, has the same value when coerced through the
3640/// target semantics.
3641static bool IsSameFloatAfterCast(const llvm::APFloat &value,
3642                                 const llvm::fltSemantics &Src,
3643                                 const llvm::fltSemantics &Tgt) {
3644  llvm::APFloat truncated = value;
3645
3646  bool ignored;
3647  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
3648  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
3649
3650  return truncated.bitwiseIsEqual(value);
3651}
3652
3653/// Checks whether the given value, which currently has the given
3654/// source semantics, has the same value when coerced through the
3655/// target semantics.
3656///
3657/// The value might be a vector of floats (or a complex number).
3658static bool IsSameFloatAfterCast(const APValue &value,
3659                                 const llvm::fltSemantics &Src,
3660                                 const llvm::fltSemantics &Tgt) {
3661  if (value.isFloat())
3662    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
3663
3664  if (value.isVector()) {
3665    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
3666      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
3667        return false;
3668    return true;
3669  }
3670
3671  assert(value.isComplexFloat());
3672  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
3673          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
3674}
3675
3676static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
3677
3678static bool IsZero(Sema &S, Expr *E) {
3679  // Suppress cases where we are comparing against an enum constant.
3680  if (const DeclRefExpr *DR =
3681      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
3682    if (isa<EnumConstantDecl>(DR->getDecl()))
3683      return false;
3684
3685  // Suppress cases where the '0' value is expanded from a macro.
3686  if (E->getLocStart().isMacroID())
3687    return false;
3688
3689  llvm::APSInt Value;
3690  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
3691}
3692
3693static bool HasEnumType(Expr *E) {
3694  // Strip off implicit integral promotions.
3695  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
3696    if (ICE->getCastKind() != CK_IntegralCast &&
3697        ICE->getCastKind() != CK_NoOp)
3698      break;
3699    E = ICE->getSubExpr();
3700  }
3701
3702  return E->getType()->isEnumeralType();
3703}
3704
3705static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
3706  BinaryOperatorKind op = E->getOpcode();
3707  if (E->isValueDependent())
3708    return;
3709
3710  if (op == BO_LT && IsZero(S, E->getRHS())) {
3711    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3712      << "< 0" << "false" << HasEnumType(E->getLHS())
3713      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3714  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
3715    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3716      << ">= 0" << "true" << HasEnumType(E->getLHS())
3717      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3718  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
3719    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3720      << "0 >" << "false" << HasEnumType(E->getRHS())
3721      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3722  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
3723    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3724      << "0 <=" << "true" << HasEnumType(E->getRHS())
3725      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3726  }
3727}
3728
3729/// Analyze the operands of the given comparison.  Implements the
3730/// fallback case from AnalyzeComparison.
3731static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
3732  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3733  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3734}
3735
3736/// \brief Implements -Wsign-compare.
3737///
3738/// \param E the binary operator to check for warnings
3739static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
3740  // The type the comparison is being performed in.
3741  QualType T = E->getLHS()->getType();
3742  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
3743         && "comparison with mismatched types");
3744
3745  // We don't do anything special if this isn't an unsigned integral
3746  // comparison:  we're only interested in integral comparisons, and
3747  // signed comparisons only happen in cases we don't care to warn about.
3748  //
3749  // We also don't care about value-dependent expressions or expressions
3750  // whose result is a constant.
3751  if (!T->hasUnsignedIntegerRepresentation()
3752      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
3753    return AnalyzeImpConvsInComparison(S, E);
3754
3755  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
3756  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
3757
3758  // Check to see if one of the (unmodified) operands is of different
3759  // signedness.
3760  Expr *signedOperand, *unsignedOperand;
3761  if (LHS->getType()->hasSignedIntegerRepresentation()) {
3762    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
3763           "unsigned comparison between two signed integer expressions?");
3764    signedOperand = LHS;
3765    unsignedOperand = RHS;
3766  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
3767    signedOperand = RHS;
3768    unsignedOperand = LHS;
3769  } else {
3770    CheckTrivialUnsignedComparison(S, E);
3771    return AnalyzeImpConvsInComparison(S, E);
3772  }
3773
3774  // Otherwise, calculate the effective range of the signed operand.
3775  IntRange signedRange = GetExprRange(S.Context, signedOperand);
3776
3777  // Go ahead and analyze implicit conversions in the operands.  Note
3778  // that we skip the implicit conversions on both sides.
3779  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
3780  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
3781
3782  // If the signed range is non-negative, -Wsign-compare won't fire,
3783  // but we should still check for comparisons which are always true
3784  // or false.
3785  if (signedRange.NonNegative)
3786    return CheckTrivialUnsignedComparison(S, E);
3787
3788  // For (in)equality comparisons, if the unsigned operand is a
3789  // constant which cannot collide with a overflowed signed operand,
3790  // then reinterpreting the signed operand as unsigned will not
3791  // change the result of the comparison.
3792  if (E->isEqualityOp()) {
3793    unsigned comparisonWidth = S.Context.getIntWidth(T);
3794    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
3795
3796    // We should never be unable to prove that the unsigned operand is
3797    // non-negative.
3798    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
3799
3800    if (unsignedRange.Width < comparisonWidth)
3801      return;
3802  }
3803
3804  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
3805    << LHS->getType() << RHS->getType()
3806    << LHS->getSourceRange() << RHS->getSourceRange();
3807}
3808
3809/// Analyzes an attempt to assign the given value to a bitfield.
3810///
3811/// Returns true if there was something fishy about the attempt.
3812static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
3813                                      SourceLocation InitLoc) {
3814  assert(Bitfield->isBitField());
3815  if (Bitfield->isInvalidDecl())
3816    return false;
3817
3818  // White-list bool bitfields.
3819  if (Bitfield->getType()->isBooleanType())
3820    return false;
3821
3822  // Ignore value- or type-dependent expressions.
3823  if (Bitfield->getBitWidth()->isValueDependent() ||
3824      Bitfield->getBitWidth()->isTypeDependent() ||
3825      Init->isValueDependent() ||
3826      Init->isTypeDependent())
3827    return false;
3828
3829  Expr *OriginalInit = Init->IgnoreParenImpCasts();
3830
3831  llvm::APSInt Value;
3832  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
3833    return false;
3834
3835  unsigned OriginalWidth = Value.getBitWidth();
3836  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
3837
3838  if (OriginalWidth <= FieldWidth)
3839    return false;
3840
3841  // Compute the value which the bitfield will contain.
3842  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
3843  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
3844
3845  // Check whether the stored value is equal to the original value.
3846  TruncatedValue = TruncatedValue.extend(OriginalWidth);
3847  if (Value == TruncatedValue)
3848    return false;
3849
3850  // Special-case bitfields of width 1: booleans are naturally 0/1, and
3851  // therefore don't strictly fit into a signed bitfield of width 1.
3852  if (FieldWidth == 1 && Value == 1)
3853    return false;
3854
3855  std::string PrettyValue = Value.toString(10);
3856  std::string PrettyTrunc = TruncatedValue.toString(10);
3857
3858  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
3859    << PrettyValue << PrettyTrunc << OriginalInit->getType()
3860    << Init->getSourceRange();
3861
3862  return true;
3863}
3864
3865/// Analyze the given simple or compound assignment for warning-worthy
3866/// operations.
3867static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
3868  // Just recurse on the LHS.
3869  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3870
3871  // We want to recurse on the RHS as normal unless we're assigning to
3872  // a bitfield.
3873  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
3874    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
3875                                  E->getOperatorLoc())) {
3876      // Recurse, ignoring any implicit conversions on the RHS.
3877      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
3878                                        E->getOperatorLoc());
3879    }
3880  }
3881
3882  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3883}
3884
3885/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3886static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
3887                            SourceLocation CContext, unsigned diag,
3888                            bool pruneControlFlow = false) {
3889  if (pruneControlFlow) {
3890    S.DiagRuntimeBehavior(E->getExprLoc(), E,
3891                          S.PDiag(diag)
3892                            << SourceType << T << E->getSourceRange()
3893                            << SourceRange(CContext));
3894    return;
3895  }
3896  S.Diag(E->getExprLoc(), diag)
3897    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
3898}
3899
3900/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3901static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
3902                            SourceLocation CContext, unsigned diag,
3903                            bool pruneControlFlow = false) {
3904  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
3905}
3906
3907/// Diagnose an implicit cast from a literal expression. Does not warn when the
3908/// cast wouldn't lose information.
3909void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
3910                                    SourceLocation CContext) {
3911  // Try to convert the literal exactly to an integer. If we can, don't warn.
3912  bool isExact = false;
3913  const llvm::APFloat &Value = FL->getValue();
3914  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
3915                            T->hasUnsignedIntegerRepresentation());
3916  if (Value.convertToInteger(IntegerValue,
3917                             llvm::APFloat::rmTowardZero, &isExact)
3918      == llvm::APFloat::opOK && isExact)
3919    return;
3920
3921  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
3922    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
3923}
3924
3925std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
3926  if (!Range.Width) return "0";
3927
3928  llvm::APSInt ValueInRange = Value;
3929  ValueInRange.setIsSigned(!Range.NonNegative);
3930  ValueInRange = ValueInRange.trunc(Range.Width);
3931  return ValueInRange.toString(10);
3932}
3933
3934void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
3935                             SourceLocation CC, bool *ICContext = 0) {
3936  if (E->isTypeDependent() || E->isValueDependent()) return;
3937
3938  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
3939  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
3940  if (Source == Target) return;
3941  if (Target->isDependentType()) return;
3942
3943  // If the conversion context location is invalid don't complain. We also
3944  // don't want to emit a warning if the issue occurs from the expansion of
3945  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
3946  // delay this check as long as possible. Once we detect we are in that
3947  // scenario, we just return.
3948  if (CC.isInvalid())
3949    return;
3950
3951  // Diagnose implicit casts to bool.
3952  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
3953    if (isa<StringLiteral>(E))
3954      // Warn on string literal to bool.  Checks for string literals in logical
3955      // expressions, for instances, assert(0 && "error here"), is prevented
3956      // by a check in AnalyzeImplicitConversions().
3957      return DiagnoseImpCast(S, E, T, CC,
3958                             diag::warn_impcast_string_literal_to_bool);
3959    if (Source->isFunctionType()) {
3960      // Warn on function to bool. Checks free functions and static member
3961      // functions. Weakly imported functions are excluded from the check,
3962      // since it's common to test their value to check whether the linker
3963      // found a definition for them.
3964      ValueDecl *D = 0;
3965      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
3966        D = R->getDecl();
3967      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
3968        D = M->getMemberDecl();
3969      }
3970
3971      if (D && !D->isWeak()) {
3972        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
3973          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
3974            << F << E->getSourceRange() << SourceRange(CC);
3975          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
3976            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
3977          QualType ReturnType;
3978          UnresolvedSet<4> NonTemplateOverloads;
3979          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
3980          if (!ReturnType.isNull()
3981              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
3982            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
3983              << FixItHint::CreateInsertion(
3984                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
3985          return;
3986        }
3987      }
3988    }
3989    return; // Other casts to bool are not checked.
3990  }
3991
3992  // Strip vector types.
3993  if (isa<VectorType>(Source)) {
3994    if (!isa<VectorType>(Target)) {
3995      if (S.SourceMgr.isInSystemMacro(CC))
3996        return;
3997      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
3998    }
3999
4000    // If the vector cast is cast between two vectors of the same size, it is
4001    // a bitcast, not a conversion.
4002    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4003      return;
4004
4005    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4006    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4007  }
4008
4009  // Strip complex types.
4010  if (isa<ComplexType>(Source)) {
4011    if (!isa<ComplexType>(Target)) {
4012      if (S.SourceMgr.isInSystemMacro(CC))
4013        return;
4014
4015      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4016    }
4017
4018    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4019    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4020  }
4021
4022  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4023  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4024
4025  // If the source is floating point...
4026  if (SourceBT && SourceBT->isFloatingPoint()) {
4027    // ...and the target is floating point...
4028    if (TargetBT && TargetBT->isFloatingPoint()) {
4029      // ...then warn if we're dropping FP rank.
4030
4031      // Builtin FP kinds are ordered by increasing FP rank.
4032      if (SourceBT->getKind() > TargetBT->getKind()) {
4033        // Don't warn about float constants that are precisely
4034        // representable in the target type.
4035        Expr::EvalResult result;
4036        if (E->EvaluateAsRValue(result, S.Context)) {
4037          // Value might be a float, a float vector, or a float complex.
4038          if (IsSameFloatAfterCast(result.Val,
4039                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4040                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4041            return;
4042        }
4043
4044        if (S.SourceMgr.isInSystemMacro(CC))
4045          return;
4046
4047        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4048      }
4049      return;
4050    }
4051
4052    // If the target is integral, always warn.
4053    if ((TargetBT && TargetBT->isInteger())) {
4054      if (S.SourceMgr.isInSystemMacro(CC))
4055        return;
4056
4057      Expr *InnerE = E->IgnoreParenImpCasts();
4058      // We also want to warn on, e.g., "int i = -1.234"
4059      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4060        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4061          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4062
4063      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4064        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4065      } else {
4066        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4067      }
4068    }
4069
4070    return;
4071  }
4072
4073  if (!Source->isIntegerType() || !Target->isIntegerType())
4074    return;
4075
4076  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4077           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
4078    SourceLocation Loc = E->getSourceRange().getBegin();
4079    if (Loc.isMacroID())
4080      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4081    S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4082        << T << Loc << clang::SourceRange(CC);
4083    return;
4084  }
4085
4086  IntRange SourceRange = GetExprRange(S.Context, E);
4087  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
4088
4089  if (SourceRange.Width > TargetRange.Width) {
4090    // If the source is a constant, use a default-on diagnostic.
4091    // TODO: this should happen for bitfield stores, too.
4092    llvm::APSInt Value(32);
4093    if (E->isIntegerConstantExpr(Value, S.Context)) {
4094      if (S.SourceMgr.isInSystemMacro(CC))
4095        return;
4096
4097      std::string PrettySourceValue = Value.toString(10);
4098      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
4099
4100      S.DiagRuntimeBehavior(E->getExprLoc(), E,
4101        S.PDiag(diag::warn_impcast_integer_precision_constant)
4102            << PrettySourceValue << PrettyTargetValue
4103            << E->getType() << T << E->getSourceRange()
4104            << clang::SourceRange(CC));
4105      return;
4106    }
4107
4108    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
4109    if (S.SourceMgr.isInSystemMacro(CC))
4110      return;
4111
4112    if (SourceRange.Width == 64 && TargetRange.Width == 32)
4113      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
4114                             /* pruneControlFlow */ true);
4115    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
4116  }
4117
4118  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
4119      (!TargetRange.NonNegative && SourceRange.NonNegative &&
4120       SourceRange.Width == TargetRange.Width)) {
4121
4122    if (S.SourceMgr.isInSystemMacro(CC))
4123      return;
4124
4125    unsigned DiagID = diag::warn_impcast_integer_sign;
4126
4127    // Traditionally, gcc has warned about this under -Wsign-compare.
4128    // We also want to warn about it in -Wconversion.
4129    // So if -Wconversion is off, use a completely identical diagnostic
4130    // in the sign-compare group.
4131    // The conditional-checking code will
4132    if (ICContext) {
4133      DiagID = diag::warn_impcast_integer_sign_conditional;
4134      *ICContext = true;
4135    }
4136
4137    return DiagnoseImpCast(S, E, T, CC, DiagID);
4138  }
4139
4140  // Diagnose conversions between different enumeration types.
4141  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
4142  // type, to give us better diagnostics.
4143  QualType SourceType = E->getType();
4144  if (!S.getLangOpts().CPlusPlus) {
4145    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
4146      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
4147        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
4148        SourceType = S.Context.getTypeDeclType(Enum);
4149        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
4150      }
4151  }
4152
4153  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
4154    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
4155      if ((SourceEnum->getDecl()->getIdentifier() ||
4156           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4157          (TargetEnum->getDecl()->getIdentifier() ||
4158           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4159          SourceEnum != TargetEnum) {
4160        if (S.SourceMgr.isInSystemMacro(CC))
4161          return;
4162
4163        return DiagnoseImpCast(S, E, SourceType, T, CC,
4164                               diag::warn_impcast_different_enum_types);
4165      }
4166
4167  return;
4168}
4169
4170void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
4171
4172void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
4173                             SourceLocation CC, bool &ICContext) {
4174  E = E->IgnoreParenImpCasts();
4175
4176  if (isa<ConditionalOperator>(E))
4177    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
4178
4179  AnalyzeImplicitConversions(S, E, CC);
4180  if (E->getType() != T)
4181    return CheckImplicitConversion(S, E, T, CC, &ICContext);
4182  return;
4183}
4184
4185void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
4186  SourceLocation CC = E->getQuestionLoc();
4187
4188  AnalyzeImplicitConversions(S, E->getCond(), CC);
4189
4190  bool Suspicious = false;
4191  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
4192  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
4193
4194  // If -Wconversion would have warned about either of the candidates
4195  // for a signedness conversion to the context type...
4196  if (!Suspicious) return;
4197
4198  // ...but it's currently ignored...
4199  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
4200                                 CC))
4201    return;
4202
4203  // ...then check whether it would have warned about either of the
4204  // candidates for a signedness conversion to the condition type.
4205  if (E->getType() == T) return;
4206
4207  Suspicious = false;
4208  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
4209                          E->getType(), CC, &Suspicious);
4210  if (!Suspicious)
4211    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
4212                            E->getType(), CC, &Suspicious);
4213}
4214
4215/// AnalyzeImplicitConversions - Find and report any interesting
4216/// implicit conversions in the given expression.  There are a couple
4217/// of competing diagnostics here, -Wconversion and -Wsign-compare.
4218void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
4219  QualType T = OrigE->getType();
4220  Expr *E = OrigE->IgnoreParenImpCasts();
4221
4222  if (E->isTypeDependent() || E->isValueDependent())
4223    return;
4224
4225  // For conditional operators, we analyze the arguments as if they
4226  // were being fed directly into the output.
4227  if (isa<ConditionalOperator>(E)) {
4228    ConditionalOperator *CO = cast<ConditionalOperator>(E);
4229    CheckConditionalOperator(S, CO, T);
4230    return;
4231  }
4232
4233  // Go ahead and check any implicit conversions we might have skipped.
4234  // The non-canonical typecheck is just an optimization;
4235  // CheckImplicitConversion will filter out dead implicit conversions.
4236  if (E->getType() != T)
4237    CheckImplicitConversion(S, E, T, CC);
4238
4239  // Now continue drilling into this expression.
4240
4241  // Skip past explicit casts.
4242  if (isa<ExplicitCastExpr>(E)) {
4243    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4244    return AnalyzeImplicitConversions(S, E, CC);
4245  }
4246
4247  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4248    // Do a somewhat different check with comparison operators.
4249    if (BO->isComparisonOp())
4250      return AnalyzeComparison(S, BO);
4251
4252    // And with simple assignments.
4253    if (BO->getOpcode() == BO_Assign)
4254      return AnalyzeAssignment(S, BO);
4255  }
4256
4257  // These break the otherwise-useful invariant below.  Fortunately,
4258  // we don't really need to recurse into them, because any internal
4259  // expressions should have been analyzed already when they were
4260  // built into statements.
4261  if (isa<StmtExpr>(E)) return;
4262
4263  // Don't descend into unevaluated contexts.
4264  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
4265
4266  // Now just recurse over the expression's children.
4267  CC = E->getExprLoc();
4268  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
4269  bool IsLogicalOperator = BO && BO->isLogicalOp();
4270  for (Stmt::child_range I = E->children(); I; ++I) {
4271    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
4272    if (!ChildExpr)
4273      continue;
4274
4275    if (IsLogicalOperator &&
4276        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
4277      // Ignore checking string literals that are in logical operators.
4278      continue;
4279    AnalyzeImplicitConversions(S, ChildExpr, CC);
4280  }
4281}
4282
4283} // end anonymous namespace
4284
4285/// Diagnoses "dangerous" implicit conversions within the given
4286/// expression (which is a full expression).  Implements -Wconversion
4287/// and -Wsign-compare.
4288///
4289/// \param CC the "context" location of the implicit conversion, i.e.
4290///   the most location of the syntactic entity requiring the implicit
4291///   conversion
4292void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
4293  // Don't diagnose in unevaluated contexts.
4294  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
4295    return;
4296
4297  // Don't diagnose for value- or type-dependent expressions.
4298  if (E->isTypeDependent() || E->isValueDependent())
4299    return;
4300
4301  // Check for array bounds violations in cases where the check isn't triggered
4302  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
4303  // ArraySubscriptExpr is on the RHS of a variable initialization.
4304  CheckArrayAccess(E);
4305
4306  // This is not the right CC for (e.g.) a variable initialization.
4307  AnalyzeImplicitConversions(*this, E, CC);
4308}
4309
4310void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
4311                                       FieldDecl *BitField,
4312                                       Expr *Init) {
4313  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
4314}
4315
4316/// CheckParmsForFunctionDef - Check that the parameters of the given
4317/// function are appropriate for the definition of a function. This
4318/// takes care of any checks that cannot be performed on the
4319/// declaration itself, e.g., that the types of each of the function
4320/// parameters are complete.
4321bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
4322                                    bool CheckParameterNames) {
4323  bool HasInvalidParm = false;
4324  for (; P != PEnd; ++P) {
4325    ParmVarDecl *Param = *P;
4326
4327    // C99 6.7.5.3p4: the parameters in a parameter type list in a
4328    // function declarator that is part of a function definition of
4329    // that function shall not have incomplete type.
4330    //
4331    // This is also C++ [dcl.fct]p6.
4332    if (!Param->isInvalidDecl() &&
4333        RequireCompleteType(Param->getLocation(), Param->getType(),
4334                               diag::err_typecheck_decl_incomplete_type)) {
4335      Param->setInvalidDecl();
4336      HasInvalidParm = true;
4337    }
4338
4339    // C99 6.9.1p5: If the declarator includes a parameter type list, the
4340    // declaration of each parameter shall include an identifier.
4341    if (CheckParameterNames &&
4342        Param->getIdentifier() == 0 &&
4343        !Param->isImplicit() &&
4344        !getLangOpts().CPlusPlus)
4345      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
4346
4347    // C99 6.7.5.3p12:
4348    //   If the function declarator is not part of a definition of that
4349    //   function, parameters may have incomplete type and may use the [*]
4350    //   notation in their sequences of declarator specifiers to specify
4351    //   variable length array types.
4352    QualType PType = Param->getOriginalType();
4353    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
4354      if (AT->getSizeModifier() == ArrayType::Star) {
4355        // FIXME: This diagnosic should point the the '[*]' if source-location
4356        // information is added for it.
4357        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
4358      }
4359    }
4360  }
4361
4362  return HasInvalidParm;
4363}
4364
4365/// CheckCastAlign - Implements -Wcast-align, which warns when a
4366/// pointer cast increases the alignment requirements.
4367void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
4368  // This is actually a lot of work to potentially be doing on every
4369  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
4370  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
4371                                          TRange.getBegin())
4372        == DiagnosticsEngine::Ignored)
4373    return;
4374
4375  // Ignore dependent types.
4376  if (T->isDependentType() || Op->getType()->isDependentType())
4377    return;
4378
4379  // Require that the destination be a pointer type.
4380  const PointerType *DestPtr = T->getAs<PointerType>();
4381  if (!DestPtr) return;
4382
4383  // If the destination has alignment 1, we're done.
4384  QualType DestPointee = DestPtr->getPointeeType();
4385  if (DestPointee->isIncompleteType()) return;
4386  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
4387  if (DestAlign.isOne()) return;
4388
4389  // Require that the source be a pointer type.
4390  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
4391  if (!SrcPtr) return;
4392  QualType SrcPointee = SrcPtr->getPointeeType();
4393
4394  // Whitelist casts from cv void*.  We already implicitly
4395  // whitelisted casts to cv void*, since they have alignment 1.
4396  // Also whitelist casts involving incomplete types, which implicitly
4397  // includes 'void'.
4398  if (SrcPointee->isIncompleteType()) return;
4399
4400  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
4401  if (SrcAlign >= DestAlign) return;
4402
4403  Diag(TRange.getBegin(), diag::warn_cast_align)
4404    << Op->getType() << T
4405    << static_cast<unsigned>(SrcAlign.getQuantity())
4406    << static_cast<unsigned>(DestAlign.getQuantity())
4407    << TRange << Op->getSourceRange();
4408}
4409
4410static const Type* getElementType(const Expr *BaseExpr) {
4411  const Type* EltType = BaseExpr->getType().getTypePtr();
4412  if (EltType->isAnyPointerType())
4413    return EltType->getPointeeType().getTypePtr();
4414  else if (EltType->isArrayType())
4415    return EltType->getBaseElementTypeUnsafe();
4416  return EltType;
4417}
4418
4419/// \brief Check whether this array fits the idiom of a size-one tail padded
4420/// array member of a struct.
4421///
4422/// We avoid emitting out-of-bounds access warnings for such arrays as they are
4423/// commonly used to emulate flexible arrays in C89 code.
4424static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
4425                                    const NamedDecl *ND) {
4426  if (Size != 1 || !ND) return false;
4427
4428  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
4429  if (!FD) return false;
4430
4431  // Don't consider sizes resulting from macro expansions or template argument
4432  // substitution to form C89 tail-padded arrays.
4433  ConstantArrayTypeLoc TL =
4434    cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc());
4435  const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr());
4436  if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
4437    return false;
4438
4439  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
4440  if (!RD) return false;
4441  if (RD->isUnion()) return false;
4442  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
4443    if (!CRD->isStandardLayout()) return false;
4444  }
4445
4446  // See if this is the last field decl in the record.
4447  const Decl *D = FD;
4448  while ((D = D->getNextDeclInContext()))
4449    if (isa<FieldDecl>(D))
4450      return false;
4451  return true;
4452}
4453
4454void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
4455                            const ArraySubscriptExpr *ASE,
4456                            bool AllowOnePastEnd, bool IndexNegated) {
4457  IndexExpr = IndexExpr->IgnoreParenImpCasts();
4458  if (IndexExpr->isValueDependent())
4459    return;
4460
4461  const Type *EffectiveType = getElementType(BaseExpr);
4462  BaseExpr = BaseExpr->IgnoreParenCasts();
4463  const ConstantArrayType *ArrayTy =
4464    Context.getAsConstantArrayType(BaseExpr->getType());
4465  if (!ArrayTy)
4466    return;
4467
4468  llvm::APSInt index;
4469  if (!IndexExpr->EvaluateAsInt(index, Context))
4470    return;
4471  if (IndexNegated)
4472    index = -index;
4473
4474  const NamedDecl *ND = NULL;
4475  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4476    ND = dyn_cast<NamedDecl>(DRE->getDecl());
4477  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4478    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4479
4480  if (index.isUnsigned() || !index.isNegative()) {
4481    llvm::APInt size = ArrayTy->getSize();
4482    if (!size.isStrictlyPositive())
4483      return;
4484
4485    const Type* BaseType = getElementType(BaseExpr);
4486    if (BaseType != EffectiveType) {
4487      // Make sure we're comparing apples to apples when comparing index to size
4488      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
4489      uint64_t array_typesize = Context.getTypeSize(BaseType);
4490      // Handle ptrarith_typesize being zero, such as when casting to void*
4491      if (!ptrarith_typesize) ptrarith_typesize = 1;
4492      if (ptrarith_typesize != array_typesize) {
4493        // There's a cast to a different size type involved
4494        uint64_t ratio = array_typesize / ptrarith_typesize;
4495        // TODO: Be smarter about handling cases where array_typesize is not a
4496        // multiple of ptrarith_typesize
4497        if (ptrarith_typesize * ratio == array_typesize)
4498          size *= llvm::APInt(size.getBitWidth(), ratio);
4499      }
4500    }
4501
4502    if (size.getBitWidth() > index.getBitWidth())
4503      index = index.zext(size.getBitWidth());
4504    else if (size.getBitWidth() < index.getBitWidth())
4505      size = size.zext(index.getBitWidth());
4506
4507    // For array subscripting the index must be less than size, but for pointer
4508    // arithmetic also allow the index (offset) to be equal to size since
4509    // computing the next address after the end of the array is legal and
4510    // commonly done e.g. in C++ iterators and range-based for loops.
4511    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
4512      return;
4513
4514    // Also don't warn for arrays of size 1 which are members of some
4515    // structure. These are often used to approximate flexible arrays in C89
4516    // code.
4517    if (IsTailPaddedMemberArray(*this, size, ND))
4518      return;
4519
4520    // Suppress the warning if the subscript expression (as identified by the
4521    // ']' location) and the index expression are both from macro expansions
4522    // within a system header.
4523    if (ASE) {
4524      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
4525          ASE->getRBracketLoc());
4526      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
4527        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
4528            IndexExpr->getLocStart());
4529        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
4530          return;
4531      }
4532    }
4533
4534    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
4535    if (ASE)
4536      DiagID = diag::warn_array_index_exceeds_bounds;
4537
4538    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4539                        PDiag(DiagID) << index.toString(10, true)
4540                          << size.toString(10, true)
4541                          << (unsigned)size.getLimitedValue(~0U)
4542                          << IndexExpr->getSourceRange());
4543  } else {
4544    unsigned DiagID = diag::warn_array_index_precedes_bounds;
4545    if (!ASE) {
4546      DiagID = diag::warn_ptr_arith_precedes_bounds;
4547      if (index.isNegative()) index = -index;
4548    }
4549
4550    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4551                        PDiag(DiagID) << index.toString(10, true)
4552                          << IndexExpr->getSourceRange());
4553  }
4554
4555  if (!ND) {
4556    // Try harder to find a NamedDecl to point at in the note.
4557    while (const ArraySubscriptExpr *ASE =
4558           dyn_cast<ArraySubscriptExpr>(BaseExpr))
4559      BaseExpr = ASE->getBase()->IgnoreParenCasts();
4560    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4561      ND = dyn_cast<NamedDecl>(DRE->getDecl());
4562    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4563      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4564  }
4565
4566  if (ND)
4567    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
4568                        PDiag(diag::note_array_index_out_of_bounds)
4569                          << ND->getDeclName());
4570}
4571
4572void Sema::CheckArrayAccess(const Expr *expr) {
4573  int AllowOnePastEnd = 0;
4574  while (expr) {
4575    expr = expr->IgnoreParenImpCasts();
4576    switch (expr->getStmtClass()) {
4577      case Stmt::ArraySubscriptExprClass: {
4578        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
4579        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
4580                         AllowOnePastEnd > 0);
4581        return;
4582      }
4583      case Stmt::UnaryOperatorClass: {
4584        // Only unwrap the * and & unary operators
4585        const UnaryOperator *UO = cast<UnaryOperator>(expr);
4586        expr = UO->getSubExpr();
4587        switch (UO->getOpcode()) {
4588          case UO_AddrOf:
4589            AllowOnePastEnd++;
4590            break;
4591          case UO_Deref:
4592            AllowOnePastEnd--;
4593            break;
4594          default:
4595            return;
4596        }
4597        break;
4598      }
4599      case Stmt::ConditionalOperatorClass: {
4600        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
4601        if (const Expr *lhs = cond->getLHS())
4602          CheckArrayAccess(lhs);
4603        if (const Expr *rhs = cond->getRHS())
4604          CheckArrayAccess(rhs);
4605        return;
4606      }
4607      default:
4608        return;
4609    }
4610  }
4611}
4612
4613//===--- CHECK: Objective-C retain cycles ----------------------------------//
4614
4615namespace {
4616  struct RetainCycleOwner {
4617    RetainCycleOwner() : Variable(0), Indirect(false) {}
4618    VarDecl *Variable;
4619    SourceRange Range;
4620    SourceLocation Loc;
4621    bool Indirect;
4622
4623    void setLocsFrom(Expr *e) {
4624      Loc = e->getExprLoc();
4625      Range = e->getSourceRange();
4626    }
4627  };
4628}
4629
4630/// Consider whether capturing the given variable can possibly lead to
4631/// a retain cycle.
4632static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
4633  // In ARC, it's captured strongly iff the variable has __strong
4634  // lifetime.  In MRR, it's captured strongly if the variable is
4635  // __block and has an appropriate type.
4636  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4637    return false;
4638
4639  owner.Variable = var;
4640  owner.setLocsFrom(ref);
4641  return true;
4642}
4643
4644static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
4645  while (true) {
4646    e = e->IgnoreParens();
4647    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
4648      switch (cast->getCastKind()) {
4649      case CK_BitCast:
4650      case CK_LValueBitCast:
4651      case CK_LValueToRValue:
4652      case CK_ARCReclaimReturnedObject:
4653        e = cast->getSubExpr();
4654        continue;
4655
4656      default:
4657        return false;
4658      }
4659    }
4660
4661    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
4662      ObjCIvarDecl *ivar = ref->getDecl();
4663      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4664        return false;
4665
4666      // Try to find a retain cycle in the base.
4667      if (!findRetainCycleOwner(S, ref->getBase(), owner))
4668        return false;
4669
4670      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
4671      owner.Indirect = true;
4672      return true;
4673    }
4674
4675    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
4676      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
4677      if (!var) return false;
4678      return considerVariable(var, ref, owner);
4679    }
4680
4681    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
4682      if (member->isArrow()) return false;
4683
4684      // Don't count this as an indirect ownership.
4685      e = member->getBase();
4686      continue;
4687    }
4688
4689    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
4690      // Only pay attention to pseudo-objects on property references.
4691      ObjCPropertyRefExpr *pre
4692        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
4693                                              ->IgnoreParens());
4694      if (!pre) return false;
4695      if (pre->isImplicitProperty()) return false;
4696      ObjCPropertyDecl *property = pre->getExplicitProperty();
4697      if (!property->isRetaining() &&
4698          !(property->getPropertyIvarDecl() &&
4699            property->getPropertyIvarDecl()->getType()
4700              .getObjCLifetime() == Qualifiers::OCL_Strong))
4701          return false;
4702
4703      owner.Indirect = true;
4704      if (pre->isSuperReceiver()) {
4705        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
4706        if (!owner.Variable)
4707          return false;
4708        owner.Loc = pre->getLocation();
4709        owner.Range = pre->getSourceRange();
4710        return true;
4711      }
4712      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
4713                              ->getSourceExpr());
4714      continue;
4715    }
4716
4717    // Array ivars?
4718
4719    return false;
4720  }
4721}
4722
4723namespace {
4724  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
4725    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
4726      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
4727        Variable(variable), Capturer(0) {}
4728
4729    VarDecl *Variable;
4730    Expr *Capturer;
4731
4732    void VisitDeclRefExpr(DeclRefExpr *ref) {
4733      if (ref->getDecl() == Variable && !Capturer)
4734        Capturer = ref;
4735    }
4736
4737    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
4738      if (Capturer) return;
4739      Visit(ref->getBase());
4740      if (Capturer && ref->isFreeIvar())
4741        Capturer = ref;
4742    }
4743
4744    void VisitBlockExpr(BlockExpr *block) {
4745      // Look inside nested blocks
4746      if (block->getBlockDecl()->capturesVariable(Variable))
4747        Visit(block->getBlockDecl()->getBody());
4748    }
4749  };
4750}
4751
4752/// Check whether the given argument is a block which captures a
4753/// variable.
4754static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
4755  assert(owner.Variable && owner.Loc.isValid());
4756
4757  e = e->IgnoreParenCasts();
4758  BlockExpr *block = dyn_cast<BlockExpr>(e);
4759  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
4760    return 0;
4761
4762  FindCaptureVisitor visitor(S.Context, owner.Variable);
4763  visitor.Visit(block->getBlockDecl()->getBody());
4764  return visitor.Capturer;
4765}
4766
4767static void diagnoseRetainCycle(Sema &S, Expr *capturer,
4768                                RetainCycleOwner &owner) {
4769  assert(capturer);
4770  assert(owner.Variable && owner.Loc.isValid());
4771
4772  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
4773    << owner.Variable << capturer->getSourceRange();
4774  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
4775    << owner.Indirect << owner.Range;
4776}
4777
4778/// Check for a keyword selector that starts with the word 'add' or
4779/// 'set'.
4780static bool isSetterLikeSelector(Selector sel) {
4781  if (sel.isUnarySelector()) return false;
4782
4783  StringRef str = sel.getNameForSlot(0);
4784  while (!str.empty() && str.front() == '_') str = str.substr(1);
4785  if (str.startswith("set"))
4786    str = str.substr(3);
4787  else if (str.startswith("add")) {
4788    // Specially whitelist 'addOperationWithBlock:'.
4789    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
4790      return false;
4791    str = str.substr(3);
4792  }
4793  else
4794    return false;
4795
4796  if (str.empty()) return true;
4797  return !islower(str.front());
4798}
4799
4800/// Check a message send to see if it's likely to cause a retain cycle.
4801void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
4802  // Only check instance methods whose selector looks like a setter.
4803  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
4804    return;
4805
4806  // Try to find a variable that the receiver is strongly owned by.
4807  RetainCycleOwner owner;
4808  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
4809    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
4810      return;
4811  } else {
4812    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
4813    owner.Variable = getCurMethodDecl()->getSelfDecl();
4814    owner.Loc = msg->getSuperLoc();
4815    owner.Range = msg->getSuperLoc();
4816  }
4817
4818  // Check whether the receiver is captured by any of the arguments.
4819  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
4820    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
4821      return diagnoseRetainCycle(*this, capturer, owner);
4822}
4823
4824/// Check a property assign to see if it's likely to cause a retain cycle.
4825void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
4826  RetainCycleOwner owner;
4827  if (!findRetainCycleOwner(*this, receiver, owner))
4828    return;
4829
4830  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
4831    diagnoseRetainCycle(*this, capturer, owner);
4832}
4833
4834bool Sema::checkUnsafeAssigns(SourceLocation Loc,
4835                              QualType LHS, Expr *RHS) {
4836  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
4837  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
4838    return false;
4839  // strip off any implicit cast added to get to the one arc-specific
4840  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4841    if (cast->getCastKind() == CK_ARCConsumeObject) {
4842      Diag(Loc, diag::warn_arc_retained_assign)
4843        << (LT == Qualifiers::OCL_ExplicitNone)
4844        << RHS->getSourceRange();
4845      return true;
4846    }
4847    RHS = cast->getSubExpr();
4848  }
4849  return false;
4850}
4851
4852void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
4853                              Expr *LHS, Expr *RHS) {
4854  QualType LHSType;
4855  // PropertyRef on LHS type need be directly obtained from
4856  // its declaration as it has a PsuedoType.
4857  ObjCPropertyRefExpr *PRE
4858    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
4859  if (PRE && !PRE->isImplicitProperty()) {
4860    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
4861    if (PD)
4862      LHSType = PD->getType();
4863  }
4864
4865  if (LHSType.isNull())
4866    LHSType = LHS->getType();
4867  if (checkUnsafeAssigns(Loc, LHSType, RHS))
4868    return;
4869  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
4870  // FIXME. Check for other life times.
4871  if (LT != Qualifiers::OCL_None)
4872    return;
4873
4874  if (PRE) {
4875    if (PRE->isImplicitProperty())
4876      return;
4877    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
4878    if (!PD)
4879      return;
4880
4881    unsigned Attributes = PD->getPropertyAttributes();
4882    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
4883      // when 'assign' attribute was not explicitly specified
4884      // by user, ignore it and rely on property type itself
4885      // for lifetime info.
4886      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
4887      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
4888          LHSType->isObjCRetainableType())
4889        return;
4890
4891      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4892        if (cast->getCastKind() == CK_ARCConsumeObject) {
4893          Diag(Loc, diag::warn_arc_retained_property_assign)
4894          << RHS->getSourceRange();
4895          return;
4896        }
4897        RHS = cast->getSubExpr();
4898      }
4899    }
4900  }
4901}
4902
4903//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
4904
4905namespace {
4906bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
4907                                 SourceLocation StmtLoc,
4908                                 const NullStmt *Body) {
4909  // Do not warn if the body is a macro that expands to nothing, e.g:
4910  //
4911  // #define CALL(x)
4912  // if (condition)
4913  //   CALL(0);
4914  //
4915  if (Body->hasLeadingEmptyMacro())
4916    return false;
4917
4918  // Get line numbers of statement and body.
4919  bool StmtLineInvalid;
4920  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
4921                                                      &StmtLineInvalid);
4922  if (StmtLineInvalid)
4923    return false;
4924
4925  bool BodyLineInvalid;
4926  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
4927                                                      &BodyLineInvalid);
4928  if (BodyLineInvalid)
4929    return false;
4930
4931  // Warn if null statement and body are on the same line.
4932  if (StmtLine != BodyLine)
4933    return false;
4934
4935  return true;
4936}
4937} // Unnamed namespace
4938
4939void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
4940                                 const Stmt *Body,
4941                                 unsigned DiagID) {
4942  // Since this is a syntactic check, don't emit diagnostic for template
4943  // instantiations, this just adds noise.
4944  if (CurrentInstantiationScope)
4945    return;
4946
4947  // The body should be a null statement.
4948  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
4949  if (!NBody)
4950    return;
4951
4952  // Do the usual checks.
4953  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
4954    return;
4955
4956  Diag(NBody->getSemiLoc(), DiagID);
4957  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
4958}
4959
4960void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
4961                                 const Stmt *PossibleBody) {
4962  assert(!CurrentInstantiationScope); // Ensured by caller
4963
4964  SourceLocation StmtLoc;
4965  const Stmt *Body;
4966  unsigned DiagID;
4967  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
4968    StmtLoc = FS->getRParenLoc();
4969    Body = FS->getBody();
4970    DiagID = diag::warn_empty_for_body;
4971  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
4972    StmtLoc = WS->getCond()->getSourceRange().getEnd();
4973    Body = WS->getBody();
4974    DiagID = diag::warn_empty_while_body;
4975  } else
4976    return; // Neither `for' nor `while'.
4977
4978  // The body should be a null statement.
4979  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
4980  if (!NBody)
4981    return;
4982
4983  // Skip expensive checks if diagnostic is disabled.
4984  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
4985          DiagnosticsEngine::Ignored)
4986    return;
4987
4988  // Do the usual checks.
4989  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
4990    return;
4991
4992  // `for(...);' and `while(...);' are popular idioms, so in order to keep
4993  // noise level low, emit diagnostics only if for/while is followed by a
4994  // CompoundStmt, e.g.:
4995  //    for (int i = 0; i < n; i++);
4996  //    {
4997  //      a(i);
4998  //    }
4999  // or if for/while is followed by a statement with more indentation
5000  // than for/while itself:
5001  //    for (int i = 0; i < n; i++);
5002  //      a(i);
5003  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
5004  if (!ProbableTypo) {
5005    bool BodyColInvalid;
5006    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
5007                             PossibleBody->getLocStart(),
5008                             &BodyColInvalid);
5009    if (BodyColInvalid)
5010      return;
5011
5012    bool StmtColInvalid;
5013    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
5014                             S->getLocStart(),
5015                             &StmtColInvalid);
5016    if (StmtColInvalid)
5017      return;
5018
5019    if (BodyCol > StmtCol)
5020      ProbableTypo = true;
5021  }
5022
5023  if (ProbableTypo) {
5024    Diag(NBody->getSemiLoc(), DiagID);
5025    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5026  }
5027}
5028