SemaChecking.cpp revision 6c656c3d89523d8ddd143f96e11f6bc16c10c60b 
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    }
1180  }
1181
1182  return false;
1183}
1184
1185/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1186// This is declared to take (...), so we have to check everything.
1187ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1188  if (TheCall->getNumArgs() < 2)
1189    return ExprError(Diag(TheCall->getLocEnd(),
1190                          diag::err_typecheck_call_too_few_args_at_least)
1191      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1192      << TheCall->getSourceRange());
1193
1194  // Determine which of the following types of shufflevector we're checking:
1195  // 1) unary, vector mask: (lhs, mask)
1196  // 2) binary, vector mask: (lhs, rhs, mask)
1197  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1198  QualType resType = TheCall->getArg(0)->getType();
1199  unsigned numElements = 0;
1200
1201  if (!TheCall->getArg(0)->isTypeDependent() &&
1202      !TheCall->getArg(1)->isTypeDependent()) {
1203    QualType LHSType = TheCall->getArg(0)->getType();
1204    QualType RHSType = TheCall->getArg(1)->getType();
1205
1206    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1207      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1208        << SourceRange(TheCall->getArg(0)->getLocStart(),
1209                       TheCall->getArg(1)->getLocEnd());
1210      return ExprError();
1211    }
1212
1213    numElements = LHSType->getAs<VectorType>()->getNumElements();
1214    unsigned numResElements = TheCall->getNumArgs() - 2;
1215
1216    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1217    // with mask.  If so, verify that RHS is an integer vector type with the
1218    // same number of elts as lhs.
1219    if (TheCall->getNumArgs() == 2) {
1220      if (!RHSType->hasIntegerRepresentation() ||
1221          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1222        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1223          << SourceRange(TheCall->getArg(1)->getLocStart(),
1224                         TheCall->getArg(1)->getLocEnd());
1225      numResElements = numElements;
1226    }
1227    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1228      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1229        << SourceRange(TheCall->getArg(0)->getLocStart(),
1230                       TheCall->getArg(1)->getLocEnd());
1231      return ExprError();
1232    } else if (numElements != numResElements) {
1233      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1234      resType = Context.getVectorType(eltType, numResElements,
1235                                      VectorType::GenericVector);
1236    }
1237  }
1238
1239  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1240    if (TheCall->getArg(i)->isTypeDependent() ||
1241        TheCall->getArg(i)->isValueDependent())
1242      continue;
1243
1244    llvm::APSInt Result(32);
1245    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1246      return ExprError(Diag(TheCall->getLocStart(),
1247                  diag::err_shufflevector_nonconstant_argument)
1248                << TheCall->getArg(i)->getSourceRange());
1249
1250    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1251      return ExprError(Diag(TheCall->getLocStart(),
1252                  diag::err_shufflevector_argument_too_large)
1253               << TheCall->getArg(i)->getSourceRange());
1254  }
1255
1256  SmallVector<Expr*, 32> exprs;
1257
1258  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1259    exprs.push_back(TheCall->getArg(i));
1260    TheCall->setArg(i, 0);
1261  }
1262
1263  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
1264                                            exprs.size(), resType,
1265                                            TheCall->getCallee()->getLocStart(),
1266                                            TheCall->getRParenLoc()));
1267}
1268
1269/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1270// This is declared to take (const void*, ...) and can take two
1271// optional constant int args.
1272bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1273  unsigned NumArgs = TheCall->getNumArgs();
1274
1275  if (NumArgs > 3)
1276    return Diag(TheCall->getLocEnd(),
1277             diag::err_typecheck_call_too_many_args_at_most)
1278             << 0 /*function call*/ << 3 << NumArgs
1279             << TheCall->getSourceRange();
1280
1281  // Argument 0 is checked for us and the remaining arguments must be
1282  // constant integers.
1283  for (unsigned i = 1; i != NumArgs; ++i) {
1284    Expr *Arg = TheCall->getArg(i);
1285
1286    llvm::APSInt Result;
1287    if (SemaBuiltinConstantArg(TheCall, i, Result))
1288      return true;
1289
1290    // FIXME: gcc issues a warning and rewrites these to 0. These
1291    // seems especially odd for the third argument since the default
1292    // is 3.
1293    if (i == 1) {
1294      if (Result.getLimitedValue() > 1)
1295        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1296             << "0" << "1" << Arg->getSourceRange();
1297    } else {
1298      if (Result.getLimitedValue() > 3)
1299        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1300            << "0" << "3" << Arg->getSourceRange();
1301    }
1302  }
1303
1304  return false;
1305}
1306
1307/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1308/// TheCall is a constant expression.
1309bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1310                                  llvm::APSInt &Result) {
1311  Expr *Arg = TheCall->getArg(ArgNum);
1312  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1313  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1314
1315  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1316
1317  if (!Arg->isIntegerConstantExpr(Result, Context))
1318    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1319                << FDecl->getDeclName() <<  Arg->getSourceRange();
1320
1321  return false;
1322}
1323
1324/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1325/// int type). This simply type checks that type is one of the defined
1326/// constants (0-3).
1327// For compatibility check 0-3, llvm only handles 0 and 2.
1328bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1329  llvm::APSInt Result;
1330
1331  // Check constant-ness first.
1332  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1333    return true;
1334
1335  Expr *Arg = TheCall->getArg(1);
1336  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1337    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1338             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1339  }
1340
1341  return false;
1342}
1343
1344/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1345/// This checks that val is a constant 1.
1346bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1347  Expr *Arg = TheCall->getArg(1);
1348  llvm::APSInt Result;
1349
1350  // TODO: This is less than ideal. Overload this to take a value.
1351  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1352    return true;
1353
1354  if (Result != 1)
1355    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1356             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1357
1358  return false;
1359}
1360
1361// Handle i > 1 ? "x" : "y", recursively.
1362bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
1363                                  unsigned NumArgs, bool HasVAListArg,
1364                                  unsigned format_idx, unsigned firstDataArg,
1365                                  FormatStringType Type, bool inFunctionCall) {
1366 tryAgain:
1367  if (E->isTypeDependent() || E->isValueDependent())
1368    return false;
1369
1370  E = E->IgnoreParenCasts();
1371
1372  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1373    // Technically -Wformat-nonliteral does not warn about this case.
1374    // The behavior of printf and friends in this case is implementation
1375    // dependent.  Ideally if the format string cannot be null then
1376    // it should have a 'nonnull' attribute in the function prototype.
1377    return true;
1378
1379  switch (E->getStmtClass()) {
1380  case Stmt::BinaryConditionalOperatorClass:
1381  case Stmt::ConditionalOperatorClass: {
1382    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
1383    return SemaCheckStringLiteral(C->getTrueExpr(), Args, NumArgs, HasVAListArg,
1384                                  format_idx, firstDataArg, Type,
1385                                  inFunctionCall)
1386       && SemaCheckStringLiteral(C->getFalseExpr(), Args, NumArgs, HasVAListArg,
1387                                 format_idx, firstDataArg, Type,
1388                                 inFunctionCall);
1389  }
1390
1391  case Stmt::ImplicitCastExprClass: {
1392    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1393    goto tryAgain;
1394  }
1395
1396  case Stmt::OpaqueValueExprClass:
1397    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1398      E = src;
1399      goto tryAgain;
1400    }
1401    return false;
1402
1403  case Stmt::PredefinedExprClass:
1404    // While __func__, etc., are technically not string literals, they
1405    // cannot contain format specifiers and thus are not a security
1406    // liability.
1407    return true;
1408
1409  case Stmt::DeclRefExprClass: {
1410    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1411
1412    // As an exception, do not flag errors for variables binding to
1413    // const string literals.
1414    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1415      bool isConstant = false;
1416      QualType T = DR->getType();
1417
1418      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1419        isConstant = AT->getElementType().isConstant(Context);
1420      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1421        isConstant = T.isConstant(Context) &&
1422                     PT->getPointeeType().isConstant(Context);
1423      } else if (T->isObjCObjectPointerType()) {
1424        // In ObjC, there is usually no "const ObjectPointer" type,
1425        // so don't check if the pointee type is constant.
1426        isConstant = T.isConstant(Context);
1427      }
1428
1429      if (isConstant) {
1430        if (const Expr *Init = VD->getAnyInitializer())
1431          return SemaCheckStringLiteral(Init, Args, NumArgs,
1432                                        HasVAListArg, format_idx, firstDataArg,
1433                                        Type, /*inFunctionCall*/false);
1434      }
1435
1436      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1437      // special check to see if the format string is a function parameter
1438      // of the function calling the printf function.  If the function
1439      // has an attribute indicating it is a printf-like function, then we
1440      // should suppress warnings concerning non-literals being used in a call
1441      // to a vprintf function.  For example:
1442      //
1443      // void
1444      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1445      //      va_list ap;
1446      //      va_start(ap, fmt);
1447      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1448      //      ...
1449      //
1450      if (HasVAListArg) {
1451        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1452          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1453            int PVIndex = PV->getFunctionScopeIndex() + 1;
1454            for (specific_attr_iterator<FormatAttr>
1455                 i = ND->specific_attr_begin<FormatAttr>(),
1456                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1457              FormatAttr *PVFormat = *i;
1458              // adjust for implicit parameter
1459              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1460                if (MD->isInstance())
1461                  ++PVIndex;
1462              // We also check if the formats are compatible.
1463              // We can't pass a 'scanf' string to a 'printf' function.
1464              if (PVIndex == PVFormat->getFormatIdx() &&
1465                  Type == GetFormatStringType(PVFormat))
1466                return true;
1467            }
1468          }
1469        }
1470      }
1471    }
1472
1473    return false;
1474  }
1475
1476  case Stmt::CallExprClass:
1477  case Stmt::CXXMemberCallExprClass: {
1478    const CallExpr *CE = cast<CallExpr>(E);
1479    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1480      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1481        unsigned ArgIndex = FA->getFormatIdx();
1482        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1483          if (MD->isInstance())
1484            --ArgIndex;
1485        const Expr *Arg = CE->getArg(ArgIndex - 1);
1486
1487        return SemaCheckStringLiteral(Arg, Args, NumArgs, HasVAListArg,
1488                                      format_idx, firstDataArg, Type,
1489                                      inFunctionCall);
1490      }
1491    }
1492
1493    return false;
1494  }
1495  case Stmt::ObjCStringLiteralClass:
1496  case Stmt::StringLiteralClass: {
1497    const StringLiteral *StrE = NULL;
1498
1499    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1500      StrE = ObjCFExpr->getString();
1501    else
1502      StrE = cast<StringLiteral>(E);
1503
1504    if (StrE) {
1505      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
1506                        firstDataArg, Type, inFunctionCall);
1507      return true;
1508    }
1509
1510    return false;
1511  }
1512
1513  default:
1514    return false;
1515  }
1516}
1517
1518void
1519Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1520                            const Expr * const *ExprArgs,
1521                            SourceLocation CallSiteLoc) {
1522  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1523                                  e = NonNull->args_end();
1524       i != e; ++i) {
1525    const Expr *ArgExpr = ExprArgs[*i];
1526    if (ArgExpr->isNullPointerConstant(Context,
1527                                       Expr::NPC_ValueDependentIsNotNull))
1528      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1529  }
1530}
1531
1532Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1533  return llvm::StringSwitch<FormatStringType>(Format->getType())
1534  .Case("scanf", FST_Scanf)
1535  .Cases("printf", "printf0", FST_Printf)
1536  .Cases("NSString", "CFString", FST_NSString)
1537  .Case("strftime", FST_Strftime)
1538  .Case("strfmon", FST_Strfmon)
1539  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1540  .Default(FST_Unknown);
1541}
1542
1543/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
1544/// functions) for correct use of format strings.
1545void Sema::CheckFormatArguments(const FormatAttr *Format, CallExpr *TheCall) {
1546  bool IsCXXMember = false;
1547  // The way the format attribute works in GCC, the implicit this argument
1548  // of member functions is counted. However, it doesn't appear in our own
1549  // lists, so decrement format_idx in that case.
1550  IsCXXMember = isa<CXXMemberCallExpr>(TheCall);
1551  CheckFormatArguments(Format, TheCall->getArgs(), TheCall->getNumArgs(),
1552                       IsCXXMember, TheCall->getRParenLoc(),
1553                       TheCall->getCallee()->getSourceRange());
1554}
1555
1556void Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
1557                                unsigned NumArgs, bool IsCXXMember,
1558                                SourceLocation Loc, SourceRange Range) {
1559  bool HasVAListArg = Format->getFirstArg() == 0;
1560  unsigned format_idx = Format->getFormatIdx() - 1;
1561  unsigned firstDataArg = HasVAListArg ? 0 : Format->getFirstArg() - 1;
1562  if (IsCXXMember) {
1563    if (format_idx == 0)
1564      return;
1565    --format_idx;
1566    if(firstDataArg != 0)
1567      --firstDataArg;
1568  }
1569  CheckFormatArguments(Args, NumArgs, HasVAListArg, format_idx,
1570                       firstDataArg, GetFormatStringType(Format), Loc, Range);
1571}
1572
1573void Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
1574                                bool HasVAListArg, unsigned format_idx,
1575                                unsigned firstDataArg, FormatStringType Type,
1576                                SourceLocation Loc, SourceRange Range) {
1577  // CHECK: printf/scanf-like function is called with no format string.
1578  if (format_idx >= NumArgs) {
1579    Diag(Loc, diag::warn_missing_format_string) << Range;
1580    return;
1581  }
1582
1583  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1584
1585  // CHECK: format string is not a string literal.
1586  //
1587  // Dynamically generated format strings are difficult to
1588  // automatically vet at compile time.  Requiring that format strings
1589  // are string literals: (1) permits the checking of format strings by
1590  // the compiler and thereby (2) can practically remove the source of
1591  // many format string exploits.
1592
1593  // Format string can be either ObjC string (e.g. @"%d") or
1594  // C string (e.g. "%d")
1595  // ObjC string uses the same format specifiers as C string, so we can use
1596  // the same format string checking logic for both ObjC and C strings.
1597  if (SemaCheckStringLiteral(OrigFormatExpr, Args, NumArgs, HasVAListArg,
1598                             format_idx, firstDataArg, Type))
1599    return;  // Literal format string found, check done!
1600
1601  // Strftime is particular as it always uses a single 'time' argument,
1602  // so it is safe to pass a non-literal string.
1603  if (Type == FST_Strftime)
1604    return;
1605
1606  // Do not emit diag when the string param is a macro expansion and the
1607  // format is either NSString or CFString. This is a hack to prevent
1608  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1609  // which are usually used in place of NS and CF string literals.
1610  if (Type == FST_NSString && Args[format_idx]->getLocStart().isMacroID())
1611    return;
1612
1613  // If there are no arguments specified, warn with -Wformat-security, otherwise
1614  // warn only with -Wformat-nonliteral.
1615  if (NumArgs == format_idx+1)
1616    Diag(Args[format_idx]->getLocStart(),
1617         diag::warn_format_nonliteral_noargs)
1618      << OrigFormatExpr->getSourceRange();
1619  else
1620    Diag(Args[format_idx]->getLocStart(),
1621         diag::warn_format_nonliteral)
1622           << OrigFormatExpr->getSourceRange();
1623}
1624
1625namespace {
1626class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1627protected:
1628  Sema &S;
1629  const StringLiteral *FExpr;
1630  const Expr *OrigFormatExpr;
1631  const unsigned FirstDataArg;
1632  const unsigned NumDataArgs;
1633  const bool IsObjCLiteral;
1634  const char *Beg; // Start of format string.
1635  const bool HasVAListArg;
1636  const Expr * const *Args;
1637  const unsigned NumArgs;
1638  unsigned FormatIdx;
1639  llvm::BitVector CoveredArgs;
1640  bool usesPositionalArgs;
1641  bool atFirstArg;
1642  bool inFunctionCall;
1643public:
1644  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1645                     const Expr *origFormatExpr, unsigned firstDataArg,
1646                     unsigned numDataArgs, bool isObjCLiteral,
1647                     const char *beg, bool hasVAListArg,
1648                     Expr **args, unsigned numArgs,
1649                     unsigned formatIdx, bool inFunctionCall)
1650    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1651      FirstDataArg(firstDataArg),
1652      NumDataArgs(numDataArgs),
1653      IsObjCLiteral(isObjCLiteral), Beg(beg),
1654      HasVAListArg(hasVAListArg),
1655      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
1656      usesPositionalArgs(false), atFirstArg(true),
1657      inFunctionCall(inFunctionCall) {
1658        CoveredArgs.resize(numDataArgs);
1659        CoveredArgs.reset();
1660      }
1661
1662  void DoneProcessing();
1663
1664  void HandleIncompleteSpecifier(const char *startSpecifier,
1665                                 unsigned specifierLen);
1666
1667  void HandleNonStandardLengthModifier(
1668      const analyze_format_string::LengthModifier &LM,
1669      const char *startSpecifier, unsigned specifierLen);
1670
1671  void HandleNonStandardConversionSpecifier(
1672      const analyze_format_string::ConversionSpecifier &CS,
1673      const char *startSpecifier, unsigned specifierLen);
1674
1675  void HandleNonStandardConversionSpecification(
1676      const analyze_format_string::LengthModifier &LM,
1677      const analyze_format_string::ConversionSpecifier &CS,
1678      const char *startSpecifier, unsigned specifierLen);
1679
1680  virtual void HandlePosition(const char *startPos, unsigned posLen);
1681
1682  virtual void HandleInvalidPosition(const char *startSpecifier,
1683                                     unsigned specifierLen,
1684                                     analyze_format_string::PositionContext p);
1685
1686  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1687
1688  void HandleNullChar(const char *nullCharacter);
1689
1690  template <typename Range>
1691  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1692                                   const Expr *ArgumentExpr,
1693                                   PartialDiagnostic PDiag,
1694                                   SourceLocation StringLoc,
1695                                   bool IsStringLocation, Range StringRange,
1696                                   FixItHint Fixit = FixItHint());
1697
1698protected:
1699  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1700                                        const char *startSpec,
1701                                        unsigned specifierLen,
1702                                        const char *csStart, unsigned csLen);
1703
1704  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
1705                                         const char *startSpec,
1706                                         unsigned specifierLen);
1707
1708  SourceRange getFormatStringRange();
1709  CharSourceRange getSpecifierRange(const char *startSpecifier,
1710                                    unsigned specifierLen);
1711  SourceLocation getLocationOfByte(const char *x);
1712
1713  const Expr *getDataArg(unsigned i) const;
1714
1715  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1716                    const analyze_format_string::ConversionSpecifier &CS,
1717                    const char *startSpecifier, unsigned specifierLen,
1718                    unsigned argIndex);
1719
1720  template <typename Range>
1721  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
1722                            bool IsStringLocation, Range StringRange,
1723                            FixItHint Fixit = FixItHint());
1724
1725  void CheckPositionalAndNonpositionalArgs(
1726      const analyze_format_string::FormatSpecifier *FS);
1727};
1728}
1729
1730SourceRange CheckFormatHandler::getFormatStringRange() {
1731  return OrigFormatExpr->getSourceRange();
1732}
1733
1734CharSourceRange CheckFormatHandler::
1735getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
1736  SourceLocation Start = getLocationOfByte(startSpecifier);
1737  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
1738
1739  // Advance the end SourceLocation by one due to half-open ranges.
1740  End = End.getLocWithOffset(1);
1741
1742  return CharSourceRange::getCharRange(Start, End);
1743}
1744
1745SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
1746  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
1747}
1748
1749void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
1750                                                   unsigned specifierLen){
1751  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
1752                       getLocationOfByte(startSpecifier),
1753                       /*IsStringLocation*/true,
1754                       getSpecifierRange(startSpecifier, specifierLen));
1755}
1756
1757void CheckFormatHandler::HandleNonStandardLengthModifier(
1758    const analyze_format_string::LengthModifier &LM,
1759    const char *startSpecifier, unsigned specifierLen) {
1760  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
1761                       << 0,
1762                       getLocationOfByte(LM.getStart()),
1763                       /*IsStringLocation*/true,
1764                       getSpecifierRange(startSpecifier, specifierLen));
1765}
1766
1767void CheckFormatHandler::HandleNonStandardConversionSpecifier(
1768    const analyze_format_string::ConversionSpecifier &CS,
1769    const char *startSpecifier, unsigned specifierLen) {
1770  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
1771                       << 1,
1772                       getLocationOfByte(CS.getStart()),
1773                       /*IsStringLocation*/true,
1774                       getSpecifierRange(startSpecifier, specifierLen));
1775}
1776
1777void CheckFormatHandler::HandleNonStandardConversionSpecification(
1778    const analyze_format_string::LengthModifier &LM,
1779    const analyze_format_string::ConversionSpecifier &CS,
1780    const char *startSpecifier, unsigned specifierLen) {
1781  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
1782                       << LM.toString() << CS.toString(),
1783                       getLocationOfByte(LM.getStart()),
1784                       /*IsStringLocation*/true,
1785                       getSpecifierRange(startSpecifier, specifierLen));
1786}
1787
1788void CheckFormatHandler::HandlePosition(const char *startPos,
1789                                        unsigned posLen) {
1790  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
1791                               getLocationOfByte(startPos),
1792                               /*IsStringLocation*/true,
1793                               getSpecifierRange(startPos, posLen));
1794}
1795
1796void
1797CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
1798                                     analyze_format_string::PositionContext p) {
1799  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
1800                         << (unsigned) p,
1801                       getLocationOfByte(startPos), /*IsStringLocation*/true,
1802                       getSpecifierRange(startPos, posLen));
1803}
1804
1805void CheckFormatHandler::HandleZeroPosition(const char *startPos,
1806                                            unsigned posLen) {
1807  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
1808                               getLocationOfByte(startPos),
1809                               /*IsStringLocation*/true,
1810                               getSpecifierRange(startPos, posLen));
1811}
1812
1813void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
1814  if (!IsObjCLiteral) {
1815    // The presence of a null character is likely an error.
1816    EmitFormatDiagnostic(
1817      S.PDiag(diag::warn_printf_format_string_contains_null_char),
1818      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
1819      getFormatStringRange());
1820  }
1821}
1822
1823const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
1824  return Args[FirstDataArg + i];
1825}
1826
1827void CheckFormatHandler::DoneProcessing() {
1828    // Does the number of data arguments exceed the number of
1829    // format conversions in the format string?
1830  if (!HasVAListArg) {
1831      // Find any arguments that weren't covered.
1832    CoveredArgs.flip();
1833    signed notCoveredArg = CoveredArgs.find_first();
1834    if (notCoveredArg >= 0) {
1835      assert((unsigned)notCoveredArg < NumDataArgs);
1836      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
1837                           getDataArg((unsigned) notCoveredArg)->getLocStart(),
1838                           /*IsStringLocation*/false, getFormatStringRange());
1839    }
1840  }
1841}
1842
1843bool
1844CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
1845                                                     SourceLocation Loc,
1846                                                     const char *startSpec,
1847                                                     unsigned specifierLen,
1848                                                     const char *csStart,
1849                                                     unsigned csLen) {
1850
1851  bool keepGoing = true;
1852  if (argIndex < NumDataArgs) {
1853    // Consider the argument coverered, even though the specifier doesn't
1854    // make sense.
1855    CoveredArgs.set(argIndex);
1856  }
1857  else {
1858    // If argIndex exceeds the number of data arguments we
1859    // don't issue a warning because that is just a cascade of warnings (and
1860    // they may have intended '%%' anyway). We don't want to continue processing
1861    // the format string after this point, however, as we will like just get
1862    // gibberish when trying to match arguments.
1863    keepGoing = false;
1864  }
1865
1866  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
1867                         << StringRef(csStart, csLen),
1868                       Loc, /*IsStringLocation*/true,
1869                       getSpecifierRange(startSpec, specifierLen));
1870
1871  return keepGoing;
1872}
1873
1874void
1875CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
1876                                                      const char *startSpec,
1877                                                      unsigned specifierLen) {
1878  EmitFormatDiagnostic(
1879    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
1880    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
1881}
1882
1883bool
1884CheckFormatHandler::CheckNumArgs(
1885  const analyze_format_string::FormatSpecifier &FS,
1886  const analyze_format_string::ConversionSpecifier &CS,
1887  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
1888
1889  if (argIndex >= NumDataArgs) {
1890    PartialDiagnostic PDiag = FS.usesPositionalArg()
1891      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
1892           << (argIndex+1) << NumDataArgs)
1893      : S.PDiag(diag::warn_printf_insufficient_data_args);
1894    EmitFormatDiagnostic(
1895      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
1896      getSpecifierRange(startSpecifier, specifierLen));
1897    return false;
1898  }
1899  return true;
1900}
1901
1902template<typename Range>
1903void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
1904                                              SourceLocation Loc,
1905                                              bool IsStringLocation,
1906                                              Range StringRange,
1907                                              FixItHint FixIt) {
1908  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
1909                       Loc, IsStringLocation, StringRange, FixIt);
1910}
1911
1912/// \brief If the format string is not within the funcion call, emit a note
1913/// so that the function call and string are in diagnostic messages.
1914///
1915/// \param inFunctionCall if true, the format string is within the function
1916/// call and only one diagnostic message will be produced.  Otherwise, an
1917/// extra note will be emitted pointing to location of the format string.
1918///
1919/// \param ArgumentExpr the expression that is passed as the format string
1920/// argument in the function call.  Used for getting locations when two
1921/// diagnostics are emitted.
1922///
1923/// \param PDiag the callee should already have provided any strings for the
1924/// diagnostic message.  This function only adds locations and fixits
1925/// to diagnostics.
1926///
1927/// \param Loc primary location for diagnostic.  If two diagnostics are
1928/// required, one will be at Loc and a new SourceLocation will be created for
1929/// the other one.
1930///
1931/// \param IsStringLocation if true, Loc points to the format string should be
1932/// used for the note.  Otherwise, Loc points to the argument list and will
1933/// be used with PDiag.
1934///
1935/// \param StringRange some or all of the string to highlight.  This is
1936/// templated so it can accept either a CharSourceRange or a SourceRange.
1937///
1938/// \param Fixit optional fix it hint for the format string.
1939template<typename Range>
1940void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
1941                                              const Expr *ArgumentExpr,
1942                                              PartialDiagnostic PDiag,
1943                                              SourceLocation Loc,
1944                                              bool IsStringLocation,
1945                                              Range StringRange,
1946                                              FixItHint FixIt) {
1947  if (InFunctionCall)
1948    S.Diag(Loc, PDiag) << StringRange << FixIt;
1949  else {
1950    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
1951      << ArgumentExpr->getSourceRange();
1952    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
1953           diag::note_format_string_defined)
1954      << StringRange << FixIt;
1955  }
1956}
1957
1958//===--- CHECK: Printf format string checking ------------------------------===//
1959
1960namespace {
1961class CheckPrintfHandler : public CheckFormatHandler {
1962public:
1963  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
1964                     const Expr *origFormatExpr, unsigned firstDataArg,
1965                     unsigned numDataArgs, bool isObjCLiteral,
1966                     const char *beg, bool hasVAListArg,
1967                     Expr **Args, unsigned NumArgs,
1968                     unsigned formatIdx, bool inFunctionCall)
1969  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
1970                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
1971                       Args, NumArgs, formatIdx, inFunctionCall) {}
1972
1973
1974  bool HandleInvalidPrintfConversionSpecifier(
1975                                      const analyze_printf::PrintfSpecifier &FS,
1976                                      const char *startSpecifier,
1977                                      unsigned specifierLen);
1978
1979  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
1980                             const char *startSpecifier,
1981                             unsigned specifierLen);
1982
1983  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
1984                    const char *startSpecifier, unsigned specifierLen);
1985  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
1986                           const analyze_printf::OptionalAmount &Amt,
1987                           unsigned type,
1988                           const char *startSpecifier, unsigned specifierLen);
1989  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
1990                  const analyze_printf::OptionalFlag &flag,
1991                  const char *startSpecifier, unsigned specifierLen);
1992  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
1993                         const analyze_printf::OptionalFlag &ignoredFlag,
1994                         const analyze_printf::OptionalFlag &flag,
1995                         const char *startSpecifier, unsigned specifierLen);
1996};
1997}
1998
1999bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2000                                      const analyze_printf::PrintfSpecifier &FS,
2001                                      const char *startSpecifier,
2002                                      unsigned specifierLen) {
2003  const analyze_printf::PrintfConversionSpecifier &CS =
2004    FS.getConversionSpecifier();
2005
2006  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2007                                          getLocationOfByte(CS.getStart()),
2008                                          startSpecifier, specifierLen,
2009                                          CS.getStart(), CS.getLength());
2010}
2011
2012bool CheckPrintfHandler::HandleAmount(
2013                               const analyze_format_string::OptionalAmount &Amt,
2014                               unsigned k, const char *startSpecifier,
2015                               unsigned specifierLen) {
2016
2017  if (Amt.hasDataArgument()) {
2018    if (!HasVAListArg) {
2019      unsigned argIndex = Amt.getArgIndex();
2020      if (argIndex >= NumDataArgs) {
2021        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2022                               << k,
2023                             getLocationOfByte(Amt.getStart()),
2024                             /*IsStringLocation*/true,
2025                             getSpecifierRange(startSpecifier, specifierLen));
2026        // Don't do any more checking.  We will just emit
2027        // spurious errors.
2028        return false;
2029      }
2030
2031      // Type check the data argument.  It should be an 'int'.
2032      // Although not in conformance with C99, we also allow the argument to be
2033      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2034      // doesn't emit a warning for that case.
2035      CoveredArgs.set(argIndex);
2036      const Expr *Arg = getDataArg(argIndex);
2037      QualType T = Arg->getType();
2038
2039      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
2040      assert(ATR.isValid());
2041
2042      if (!ATR.matchesType(S.Context, T)) {
2043        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2044                               << k << ATR.getRepresentativeTypeName(S.Context)
2045                               << T << Arg->getSourceRange(),
2046                             getLocationOfByte(Amt.getStart()),
2047                             /*IsStringLocation*/true,
2048                             getSpecifierRange(startSpecifier, specifierLen));
2049        // Don't do any more checking.  We will just emit
2050        // spurious errors.
2051        return false;
2052      }
2053    }
2054  }
2055  return true;
2056}
2057
2058void CheckPrintfHandler::HandleInvalidAmount(
2059                                      const analyze_printf::PrintfSpecifier &FS,
2060                                      const analyze_printf::OptionalAmount &Amt,
2061                                      unsigned type,
2062                                      const char *startSpecifier,
2063                                      unsigned specifierLen) {
2064  const analyze_printf::PrintfConversionSpecifier &CS =
2065    FS.getConversionSpecifier();
2066
2067  FixItHint fixit =
2068    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2069      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2070                                 Amt.getConstantLength()))
2071      : FixItHint();
2072
2073  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2074                         << type << CS.toString(),
2075                       getLocationOfByte(Amt.getStart()),
2076                       /*IsStringLocation*/true,
2077                       getSpecifierRange(startSpecifier, specifierLen),
2078                       fixit);
2079}
2080
2081void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2082                                    const analyze_printf::OptionalFlag &flag,
2083                                    const char *startSpecifier,
2084                                    unsigned specifierLen) {
2085  // Warn about pointless flag with a fixit removal.
2086  const analyze_printf::PrintfConversionSpecifier &CS =
2087    FS.getConversionSpecifier();
2088  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2089                         << flag.toString() << CS.toString(),
2090                       getLocationOfByte(flag.getPosition()),
2091                       /*IsStringLocation*/true,
2092                       getSpecifierRange(startSpecifier, specifierLen),
2093                       FixItHint::CreateRemoval(
2094                         getSpecifierRange(flag.getPosition(), 1)));
2095}
2096
2097void CheckPrintfHandler::HandleIgnoredFlag(
2098                                const analyze_printf::PrintfSpecifier &FS,
2099                                const analyze_printf::OptionalFlag &ignoredFlag,
2100                                const analyze_printf::OptionalFlag &flag,
2101                                const char *startSpecifier,
2102                                unsigned specifierLen) {
2103  // Warn about ignored flag with a fixit removal.
2104  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2105                         << ignoredFlag.toString() << flag.toString(),
2106                       getLocationOfByte(ignoredFlag.getPosition()),
2107                       /*IsStringLocation*/true,
2108                       getSpecifierRange(startSpecifier, specifierLen),
2109                       FixItHint::CreateRemoval(
2110                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2111}
2112
2113bool
2114CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2115                                            &FS,
2116                                          const char *startSpecifier,
2117                                          unsigned specifierLen) {
2118
2119  using namespace analyze_format_string;
2120  using namespace analyze_printf;
2121  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2122
2123  if (FS.consumesDataArgument()) {
2124    if (atFirstArg) {
2125        atFirstArg = false;
2126        usesPositionalArgs = FS.usesPositionalArg();
2127    }
2128    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2129      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2130                                        startSpecifier, specifierLen);
2131      return false;
2132    }
2133  }
2134
2135  // First check if the field width, precision, and conversion specifier
2136  // have matching data arguments.
2137  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2138                    startSpecifier, specifierLen)) {
2139    return false;
2140  }
2141
2142  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2143                    startSpecifier, specifierLen)) {
2144    return false;
2145  }
2146
2147  if (!CS.consumesDataArgument()) {
2148    // FIXME: Technically specifying a precision or field width here
2149    // makes no sense.  Worth issuing a warning at some point.
2150    return true;
2151  }
2152
2153  // Consume the argument.
2154  unsigned argIndex = FS.getArgIndex();
2155  if (argIndex < NumDataArgs) {
2156    // The check to see if the argIndex is valid will come later.
2157    // We set the bit here because we may exit early from this
2158    // function if we encounter some other error.
2159    CoveredArgs.set(argIndex);
2160  }
2161
2162  // Check for using an Objective-C specific conversion specifier
2163  // in a non-ObjC literal.
2164  if (!IsObjCLiteral && CS.isObjCArg()) {
2165    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2166                                                  specifierLen);
2167  }
2168
2169  // Check for invalid use of field width
2170  if (!FS.hasValidFieldWidth()) {
2171    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2172        startSpecifier, specifierLen);
2173  }
2174
2175  // Check for invalid use of precision
2176  if (!FS.hasValidPrecision()) {
2177    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2178        startSpecifier, specifierLen);
2179  }
2180
2181  // Check each flag does not conflict with any other component.
2182  if (!FS.hasValidThousandsGroupingPrefix())
2183    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2184  if (!FS.hasValidLeadingZeros())
2185    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2186  if (!FS.hasValidPlusPrefix())
2187    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2188  if (!FS.hasValidSpacePrefix())
2189    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2190  if (!FS.hasValidAlternativeForm())
2191    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2192  if (!FS.hasValidLeftJustified())
2193    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2194
2195  // Check that flags are not ignored by another flag
2196  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2197    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2198        startSpecifier, specifierLen);
2199  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2200    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2201            startSpecifier, specifierLen);
2202
2203  // Check the length modifier is valid with the given conversion specifier.
2204  const LengthModifier &LM = FS.getLengthModifier();
2205  if (!FS.hasValidLengthModifier())
2206    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2207                           << LM.toString() << CS.toString(),
2208                         getLocationOfByte(LM.getStart()),
2209                         /*IsStringLocation*/true,
2210                         getSpecifierRange(startSpecifier, specifierLen),
2211                         FixItHint::CreateRemoval(
2212                           getSpecifierRange(LM.getStart(),
2213                                             LM.getLength())));
2214  if (!FS.hasStandardLengthModifier())
2215    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2216  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2217    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2218  if (!FS.hasStandardLengthConversionCombination())
2219    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2220                                             specifierLen);
2221
2222  // Are we using '%n'?
2223  if (CS.getKind() == ConversionSpecifier::nArg) {
2224    // Issue a warning about this being a possible security issue.
2225    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
2226                         getLocationOfByte(CS.getStart()),
2227                         /*IsStringLocation*/true,
2228                         getSpecifierRange(startSpecifier, specifierLen));
2229    // Continue checking the other format specifiers.
2230    return true;
2231  }
2232
2233  // The remaining checks depend on the data arguments.
2234  if (HasVAListArg)
2235    return true;
2236
2237  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2238    return false;
2239
2240  // Now type check the data expression that matches the
2241  // format specifier.
2242  const Expr *Ex = getDataArg(argIndex);
2243  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context,
2244                                                           IsObjCLiteral);
2245  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2246    // Check if we didn't match because of an implicit cast from a 'char'
2247    // or 'short' to an 'int'.  This is done because printf is a varargs
2248    // function.
2249    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
2250      if (ICE->getType() == S.Context.IntTy) {
2251        // All further checking is done on the subexpression.
2252        Ex = ICE->getSubExpr();
2253        if (ATR.matchesType(S.Context, Ex->getType()))
2254          return true;
2255      }
2256
2257    // We may be able to offer a FixItHint if it is a supported type.
2258    PrintfSpecifier fixedFS = FS;
2259    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2260                                   S.Context, IsObjCLiteral);
2261
2262    if (success) {
2263      // Get the fix string from the fixed format specifier
2264      SmallString<128> buf;
2265      llvm::raw_svector_ostream os(buf);
2266      fixedFS.toString(os);
2267
2268      EmitFormatDiagnostic(
2269        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2270          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2271          << Ex->getSourceRange(),
2272        getLocationOfByte(CS.getStart()),
2273        /*IsStringLocation*/true,
2274        getSpecifierRange(startSpecifier, specifierLen),
2275        FixItHint::CreateReplacement(
2276          getSpecifierRange(startSpecifier, specifierLen),
2277          os.str()));
2278    }
2279    else {
2280      EmitFormatDiagnostic(
2281        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2282          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2283          << getSpecifierRange(startSpecifier, specifierLen)
2284          << Ex->getSourceRange(),
2285        getLocationOfByte(CS.getStart()),
2286        true,
2287        getSpecifierRange(startSpecifier, specifierLen));
2288    }
2289  }
2290
2291  return true;
2292}
2293
2294//===--- CHECK: Scanf format string checking ------------------------------===//
2295
2296namespace {
2297class CheckScanfHandler : public CheckFormatHandler {
2298public:
2299  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2300                    const Expr *origFormatExpr, unsigned firstDataArg,
2301                    unsigned numDataArgs, bool isObjCLiteral,
2302                    const char *beg, bool hasVAListArg,
2303                    Expr **Args, unsigned NumArgs,
2304                    unsigned formatIdx, bool inFunctionCall)
2305  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2306                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
2307                       Args, NumArgs, formatIdx, inFunctionCall) {}
2308
2309  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2310                            const char *startSpecifier,
2311                            unsigned specifierLen);
2312
2313  bool HandleInvalidScanfConversionSpecifier(
2314          const analyze_scanf::ScanfSpecifier &FS,
2315          const char *startSpecifier,
2316          unsigned specifierLen);
2317
2318  void HandleIncompleteScanList(const char *start, const char *end);
2319};
2320}
2321
2322void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2323                                                 const char *end) {
2324  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2325                       getLocationOfByte(end), /*IsStringLocation*/true,
2326                       getSpecifierRange(start, end - start));
2327}
2328
2329bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2330                                        const analyze_scanf::ScanfSpecifier &FS,
2331                                        const char *startSpecifier,
2332                                        unsigned specifierLen) {
2333
2334  const analyze_scanf::ScanfConversionSpecifier &CS =
2335    FS.getConversionSpecifier();
2336
2337  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2338                                          getLocationOfByte(CS.getStart()),
2339                                          startSpecifier, specifierLen,
2340                                          CS.getStart(), CS.getLength());
2341}
2342
2343bool CheckScanfHandler::HandleScanfSpecifier(
2344                                       const analyze_scanf::ScanfSpecifier &FS,
2345                                       const char *startSpecifier,
2346                                       unsigned specifierLen) {
2347
2348  using namespace analyze_scanf;
2349  using namespace analyze_format_string;
2350
2351  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2352
2353  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2354  // be used to decide if we are using positional arguments consistently.
2355  if (FS.consumesDataArgument()) {
2356    if (atFirstArg) {
2357      atFirstArg = false;
2358      usesPositionalArgs = FS.usesPositionalArg();
2359    }
2360    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2361      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2362                                        startSpecifier, specifierLen);
2363      return false;
2364    }
2365  }
2366
2367  // Check if the field with is non-zero.
2368  const OptionalAmount &Amt = FS.getFieldWidth();
2369  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2370    if (Amt.getConstantAmount() == 0) {
2371      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2372                                                   Amt.getConstantLength());
2373      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2374                           getLocationOfByte(Amt.getStart()),
2375                           /*IsStringLocation*/true, R,
2376                           FixItHint::CreateRemoval(R));
2377    }
2378  }
2379
2380  if (!FS.consumesDataArgument()) {
2381    // FIXME: Technically specifying a precision or field width here
2382    // makes no sense.  Worth issuing a warning at some point.
2383    return true;
2384  }
2385
2386  // Consume the argument.
2387  unsigned argIndex = FS.getArgIndex();
2388  if (argIndex < NumDataArgs) {
2389      // The check to see if the argIndex is valid will come later.
2390      // We set the bit here because we may exit early from this
2391      // function if we encounter some other error.
2392    CoveredArgs.set(argIndex);
2393  }
2394
2395  // Check the length modifier is valid with the given conversion specifier.
2396  const LengthModifier &LM = FS.getLengthModifier();
2397  if (!FS.hasValidLengthModifier()) {
2398    const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength());
2399    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2400                         << LM.toString() << CS.toString()
2401                         << getSpecifierRange(startSpecifier, specifierLen),
2402                         getLocationOfByte(LM.getStart()),
2403                         /*IsStringLocation*/true, R,
2404                         FixItHint::CreateRemoval(R));
2405  }
2406
2407  if (!FS.hasStandardLengthModifier())
2408    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2409  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2410    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2411  if (!FS.hasStandardLengthConversionCombination())
2412    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2413                                             specifierLen);
2414
2415  // The remaining checks depend on the data arguments.
2416  if (HasVAListArg)
2417    return true;
2418
2419  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2420    return false;
2421
2422  // Check that the argument type matches the format specifier.
2423  const Expr *Ex = getDataArg(argIndex);
2424  const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context);
2425  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2426    ScanfSpecifier fixedFS = FS;
2427    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2428                                   S.Context);
2429
2430    if (success) {
2431      // Get the fix string from the fixed format specifier.
2432      SmallString<128> buf;
2433      llvm::raw_svector_ostream os(buf);
2434      fixedFS.toString(os);
2435
2436      EmitFormatDiagnostic(
2437        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2438          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2439          << Ex->getSourceRange(),
2440        getLocationOfByte(CS.getStart()),
2441        /*IsStringLocation*/true,
2442        getSpecifierRange(startSpecifier, specifierLen),
2443        FixItHint::CreateReplacement(
2444          getSpecifierRange(startSpecifier, specifierLen),
2445          os.str()));
2446    } else {
2447      EmitFormatDiagnostic(
2448        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2449          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2450          << Ex->getSourceRange(),
2451        getLocationOfByte(CS.getStart()),
2452        /*IsStringLocation*/true,
2453        getSpecifierRange(startSpecifier, specifierLen));
2454    }
2455  }
2456
2457  return true;
2458}
2459
2460void Sema::CheckFormatString(const StringLiteral *FExpr,
2461                             const Expr *OrigFormatExpr,
2462                             Expr **Args, unsigned NumArgs,
2463                             bool HasVAListArg, unsigned format_idx,
2464                             unsigned firstDataArg, FormatStringType Type,
2465                             bool inFunctionCall) {
2466
2467  // CHECK: is the format string a wide literal?
2468  if (!FExpr->isAscii()) {
2469    CheckFormatHandler::EmitFormatDiagnostic(
2470      *this, inFunctionCall, Args[format_idx],
2471      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
2472      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2473    return;
2474  }
2475
2476  // Str - The format string.  NOTE: this is NOT null-terminated!
2477  StringRef StrRef = FExpr->getString();
2478  const char *Str = StrRef.data();
2479  unsigned StrLen = StrRef.size();
2480  const unsigned numDataArgs = NumArgs - firstDataArg;
2481
2482  // CHECK: empty format string?
2483  if (StrLen == 0 && numDataArgs > 0) {
2484    CheckFormatHandler::EmitFormatDiagnostic(
2485      *this, inFunctionCall, Args[format_idx],
2486      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
2487      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2488    return;
2489  }
2490
2491  if (Type == FST_Printf || Type == FST_NSString) {
2492    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2493                         numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2494                         Str, HasVAListArg, Args, NumArgs, format_idx,
2495                         inFunctionCall);
2496
2497    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
2498                                                  getLangOpts()))
2499      H.DoneProcessing();
2500  } else if (Type == FST_Scanf) {
2501    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2502                        numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2503                        Str, HasVAListArg, Args, NumArgs, format_idx,
2504                        inFunctionCall);
2505
2506    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
2507                                                 getLangOpts()))
2508      H.DoneProcessing();
2509  } // TODO: handle other formats
2510}
2511
2512//===--- CHECK: Standard memory functions ---------------------------------===//
2513
2514/// \brief Determine whether the given type is a dynamic class type (e.g.,
2515/// whether it has a vtable).
2516static bool isDynamicClassType(QualType T) {
2517  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
2518    if (CXXRecordDecl *Definition = Record->getDefinition())
2519      if (Definition->isDynamicClass())
2520        return true;
2521
2522  return false;
2523}
2524
2525/// \brief If E is a sizeof expression, returns its argument expression,
2526/// otherwise returns NULL.
2527static const Expr *getSizeOfExprArg(const Expr* E) {
2528  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2529      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2530    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
2531      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
2532
2533  return 0;
2534}
2535
2536/// \brief If E is a sizeof expression, returns its argument type.
2537static QualType getSizeOfArgType(const Expr* E) {
2538  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2539      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2540    if (SizeOf->getKind() == clang::UETT_SizeOf)
2541      return SizeOf->getTypeOfArgument();
2542
2543  return QualType();
2544}
2545
2546/// \brief Check for dangerous or invalid arguments to memset().
2547///
2548/// This issues warnings on known problematic, dangerous or unspecified
2549/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
2550/// function calls.
2551///
2552/// \param Call The call expression to diagnose.
2553void Sema::CheckMemaccessArguments(const CallExpr *Call,
2554                                   unsigned BId,
2555                                   IdentifierInfo *FnName) {
2556  assert(BId != 0);
2557
2558  // It is possible to have a non-standard definition of memset.  Validate
2559  // we have enough arguments, and if not, abort further checking.
2560  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
2561  if (Call->getNumArgs() < ExpectedNumArgs)
2562    return;
2563
2564  unsigned LastArg = (BId == Builtin::BImemset ||
2565                      BId == Builtin::BIstrndup ? 1 : 2);
2566  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
2567  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
2568
2569  // We have special checking when the length is a sizeof expression.
2570  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
2571  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
2572  llvm::FoldingSetNodeID SizeOfArgID;
2573
2574  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
2575    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
2576    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
2577
2578    QualType DestTy = Dest->getType();
2579    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
2580      QualType PointeeTy = DestPtrTy->getPointeeType();
2581
2582      // Never warn about void type pointers. This can be used to suppress
2583      // false positives.
2584      if (PointeeTy->isVoidType())
2585        continue;
2586
2587      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
2588      // actually comparing the expressions for equality. Because computing the
2589      // expression IDs can be expensive, we only do this if the diagnostic is
2590      // enabled.
2591      if (SizeOfArg &&
2592          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
2593                                   SizeOfArg->getExprLoc())) {
2594        // We only compute IDs for expressions if the warning is enabled, and
2595        // cache the sizeof arg's ID.
2596        if (SizeOfArgID == llvm::FoldingSetNodeID())
2597          SizeOfArg->Profile(SizeOfArgID, Context, true);
2598        llvm::FoldingSetNodeID DestID;
2599        Dest->Profile(DestID, Context, true);
2600        if (DestID == SizeOfArgID) {
2601          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
2602          //       over sizeof(src) as well.
2603          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
2604          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
2605            if (UnaryOp->getOpcode() == UO_AddrOf)
2606              ActionIdx = 1; // If its an address-of operator, just remove it.
2607          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
2608            ActionIdx = 2; // If the pointee's size is sizeof(char),
2609                           // suggest an explicit length.
2610          unsigned DestSrcSelect =
2611            (BId == Builtin::BIstrndup ? 1 : ArgIdx);
2612          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
2613                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
2614                                << FnName << DestSrcSelect << ActionIdx
2615                                << Dest->getSourceRange()
2616                                << SizeOfArg->getSourceRange());
2617          break;
2618        }
2619      }
2620
2621      // Also check for cases where the sizeof argument is the exact same
2622      // type as the memory argument, and where it points to a user-defined
2623      // record type.
2624      if (SizeOfArgTy != QualType()) {
2625        if (PointeeTy->isRecordType() &&
2626            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
2627          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
2628                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
2629                                << FnName << SizeOfArgTy << ArgIdx
2630                                << PointeeTy << Dest->getSourceRange()
2631                                << LenExpr->getSourceRange());
2632          break;
2633        }
2634      }
2635
2636      // Always complain about dynamic classes.
2637      if (isDynamicClassType(PointeeTy)) {
2638
2639        unsigned OperationType = 0;
2640        // "overwritten" if we're warning about the destination for any call
2641        // but memcmp; otherwise a verb appropriate to the call.
2642        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
2643          if (BId == Builtin::BImemcpy)
2644            OperationType = 1;
2645          else if(BId == Builtin::BImemmove)
2646            OperationType = 2;
2647          else if (BId == Builtin::BImemcmp)
2648            OperationType = 3;
2649        }
2650
2651        DiagRuntimeBehavior(
2652          Dest->getExprLoc(), Dest,
2653          PDiag(diag::warn_dyn_class_memaccess)
2654            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
2655            << FnName << PointeeTy
2656            << OperationType
2657            << Call->getCallee()->getSourceRange());
2658      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
2659               BId != Builtin::BImemset)
2660        DiagRuntimeBehavior(
2661          Dest->getExprLoc(), Dest,
2662          PDiag(diag::warn_arc_object_memaccess)
2663            << ArgIdx << FnName << PointeeTy
2664            << Call->getCallee()->getSourceRange());
2665      else
2666        continue;
2667
2668      DiagRuntimeBehavior(
2669        Dest->getExprLoc(), Dest,
2670        PDiag(diag::note_bad_memaccess_silence)
2671          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
2672      break;
2673    }
2674  }
2675}
2676
2677// A little helper routine: ignore addition and subtraction of integer literals.
2678// This intentionally does not ignore all integer constant expressions because
2679// we don't want to remove sizeof().
2680static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
2681  Ex = Ex->IgnoreParenCasts();
2682
2683  for (;;) {
2684    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
2685    if (!BO || !BO->isAdditiveOp())
2686      break;
2687
2688    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
2689    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
2690
2691    if (isa<IntegerLiteral>(RHS))
2692      Ex = LHS;
2693    else if (isa<IntegerLiteral>(LHS))
2694      Ex = RHS;
2695    else
2696      break;
2697  }
2698
2699  return Ex;
2700}
2701
2702// Warn if the user has made the 'size' argument to strlcpy or strlcat
2703// be the size of the source, instead of the destination.
2704void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
2705                                    IdentifierInfo *FnName) {
2706
2707  // Don't crash if the user has the wrong number of arguments
2708  if (Call->getNumArgs() != 3)
2709    return;
2710
2711  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
2712  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
2713  const Expr *CompareWithSrc = NULL;
2714
2715  // Look for 'strlcpy(dst, x, sizeof(x))'
2716  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
2717    CompareWithSrc = Ex;
2718  else {
2719    // Look for 'strlcpy(dst, x, strlen(x))'
2720    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
2721      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
2722          && SizeCall->getNumArgs() == 1)
2723        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
2724    }
2725  }
2726
2727  if (!CompareWithSrc)
2728    return;
2729
2730  // Determine if the argument to sizeof/strlen is equal to the source
2731  // argument.  In principle there's all kinds of things you could do
2732  // here, for instance creating an == expression and evaluating it with
2733  // EvaluateAsBooleanCondition, but this uses a more direct technique:
2734  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
2735  if (!SrcArgDRE)
2736    return;
2737
2738  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
2739  if (!CompareWithSrcDRE ||
2740      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
2741    return;
2742
2743  const Expr *OriginalSizeArg = Call->getArg(2);
2744  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
2745    << OriginalSizeArg->getSourceRange() << FnName;
2746
2747  // Output a FIXIT hint if the destination is an array (rather than a
2748  // pointer to an array).  This could be enhanced to handle some
2749  // pointers if we know the actual size, like if DstArg is 'array+2'
2750  // we could say 'sizeof(array)-2'.
2751  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
2752  QualType DstArgTy = DstArg->getType();
2753
2754  // Only handle constant-sized or VLAs, but not flexible members.
2755  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2756    // Only issue the FIXIT for arrays of size > 1.
2757    if (CAT->getSize().getSExtValue() <= 1)
2758      return;
2759  } else if (!DstArgTy->isVariableArrayType()) {
2760    return;
2761  }
2762
2763  SmallString<128> sizeString;
2764  llvm::raw_svector_ostream OS(sizeString);
2765  OS << "sizeof(";
2766  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2767  OS << ")";
2768
2769  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
2770    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
2771                                    OS.str());
2772}
2773
2774/// Check if two expressions refer to the same declaration.
2775static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
2776  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
2777    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
2778      return D1->getDecl() == D2->getDecl();
2779  return false;
2780}
2781
2782static const Expr *getStrlenExprArg(const Expr *E) {
2783  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
2784    const FunctionDecl *FD = CE->getDirectCallee();
2785    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
2786      return 0;
2787    return CE->getArg(0)->IgnoreParenCasts();
2788  }
2789  return 0;
2790}
2791
2792// Warn on anti-patterns as the 'size' argument to strncat.
2793// The correct size argument should look like following:
2794//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
2795void Sema::CheckStrncatArguments(const CallExpr *CE,
2796                                 IdentifierInfo *FnName) {
2797  // Don't crash if the user has the wrong number of arguments.
2798  if (CE->getNumArgs() < 3)
2799    return;
2800  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
2801  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
2802  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
2803
2804  // Identify common expressions, which are wrongly used as the size argument
2805  // to strncat and may lead to buffer overflows.
2806  unsigned PatternType = 0;
2807  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
2808    // - sizeof(dst)
2809    if (referToTheSameDecl(SizeOfArg, DstArg))
2810      PatternType = 1;
2811    // - sizeof(src)
2812    else if (referToTheSameDecl(SizeOfArg, SrcArg))
2813      PatternType = 2;
2814  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
2815    if (BE->getOpcode() == BO_Sub) {
2816      const Expr *L = BE->getLHS()->IgnoreParenCasts();
2817      const Expr *R = BE->getRHS()->IgnoreParenCasts();
2818      // - sizeof(dst) - strlen(dst)
2819      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
2820          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
2821        PatternType = 1;
2822      // - sizeof(src) - (anything)
2823      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
2824        PatternType = 2;
2825    }
2826  }
2827
2828  if (PatternType == 0)
2829    return;
2830
2831  // Generate the diagnostic.
2832  SourceLocation SL = LenArg->getLocStart();
2833  SourceRange SR = LenArg->getSourceRange();
2834  SourceManager &SM  = PP.getSourceManager();
2835
2836  // If the function is defined as a builtin macro, do not show macro expansion.
2837  if (SM.isMacroArgExpansion(SL)) {
2838    SL = SM.getSpellingLoc(SL);
2839    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
2840                     SM.getSpellingLoc(SR.getEnd()));
2841  }
2842
2843  if (PatternType == 1)
2844    Diag(SL, diag::warn_strncat_large_size) << SR;
2845  else
2846    Diag(SL, diag::warn_strncat_src_size) << SR;
2847
2848  // Output a FIXIT hint if the destination is an array (rather than a
2849  // pointer to an array).  This could be enhanced to handle some
2850  // pointers if we know the actual size, like if DstArg is 'array+2'
2851  // we could say 'sizeof(array)-2'.
2852  QualType DstArgTy = DstArg->getType();
2853
2854  // Only handle constant-sized or VLAs, but not flexible members.
2855  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2856    // Only issue the FIXIT for arrays of size > 1.
2857    if (CAT->getSize().getSExtValue() <= 1)
2858      return;
2859  } else if (!DstArgTy->isVariableArrayType()) {
2860    return;
2861  }
2862
2863  SmallString<128> sizeString;
2864  llvm::raw_svector_ostream OS(sizeString);
2865  OS << "sizeof(";
2866  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2867  OS << ") - ";
2868  OS << "strlen(";
2869  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2870  OS << ") - 1";
2871
2872  Diag(SL, diag::note_strncat_wrong_size)
2873    << FixItHint::CreateReplacement(SR, OS.str());
2874}
2875
2876//===--- CHECK: Return Address of Stack Variable --------------------------===//
2877
2878static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars);
2879static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars);
2880
2881/// CheckReturnStackAddr - Check if a return statement returns the address
2882///   of a stack variable.
2883void
2884Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
2885                           SourceLocation ReturnLoc) {
2886
2887  Expr *stackE = 0;
2888  SmallVector<DeclRefExpr *, 8> refVars;
2889
2890  // Perform checking for returned stack addresses, local blocks,
2891  // label addresses or references to temporaries.
2892  if (lhsType->isPointerType() ||
2893      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
2894    stackE = EvalAddr(RetValExp, refVars);
2895  } else if (lhsType->isReferenceType()) {
2896    stackE = EvalVal(RetValExp, refVars);
2897  }
2898
2899  if (stackE == 0)
2900    return; // Nothing suspicious was found.
2901
2902  SourceLocation diagLoc;
2903  SourceRange diagRange;
2904  if (refVars.empty()) {
2905    diagLoc = stackE->getLocStart();
2906    diagRange = stackE->getSourceRange();
2907  } else {
2908    // We followed through a reference variable. 'stackE' contains the
2909    // problematic expression but we will warn at the return statement pointing
2910    // at the reference variable. We will later display the "trail" of
2911    // reference variables using notes.
2912    diagLoc = refVars[0]->getLocStart();
2913    diagRange = refVars[0]->getSourceRange();
2914  }
2915
2916  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
2917    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
2918                                             : diag::warn_ret_stack_addr)
2919     << DR->getDecl()->getDeclName() << diagRange;
2920  } else if (isa<BlockExpr>(stackE)) { // local block.
2921    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
2922  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
2923    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
2924  } else { // local temporary.
2925    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
2926                                             : diag::warn_ret_local_temp_addr)
2927     << diagRange;
2928  }
2929
2930  // Display the "trail" of reference variables that we followed until we
2931  // found the problematic expression using notes.
2932  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
2933    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
2934    // If this var binds to another reference var, show the range of the next
2935    // var, otherwise the var binds to the problematic expression, in which case
2936    // show the range of the expression.
2937    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
2938                                  : stackE->getSourceRange();
2939    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
2940      << VD->getDeclName() << range;
2941  }
2942}
2943
2944/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
2945///  check if the expression in a return statement evaluates to an address
2946///  to a location on the stack, a local block, an address of a label, or a
2947///  reference to local temporary. The recursion is used to traverse the
2948///  AST of the return expression, with recursion backtracking when we
2949///  encounter a subexpression that (1) clearly does not lead to one of the
2950///  above problematic expressions (2) is something we cannot determine leads to
2951///  a problematic expression based on such local checking.
2952///
2953///  Both EvalAddr and EvalVal follow through reference variables to evaluate
2954///  the expression that they point to. Such variables are added to the
2955///  'refVars' vector so that we know what the reference variable "trail" was.
2956///
2957///  EvalAddr processes expressions that are pointers that are used as
2958///  references (and not L-values).  EvalVal handles all other values.
2959///  At the base case of the recursion is a check for the above problematic
2960///  expressions.
2961///
2962///  This implementation handles:
2963///
2964///   * pointer-to-pointer casts
2965///   * implicit conversions from array references to pointers
2966///   * taking the address of fields
2967///   * arbitrary interplay between "&" and "*" operators
2968///   * pointer arithmetic from an address of a stack variable
2969///   * taking the address of an array element where the array is on the stack
2970static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
2971  if (E->isTypeDependent())
2972      return NULL;
2973
2974  // We should only be called for evaluating pointer expressions.
2975  assert((E->getType()->isAnyPointerType() ||
2976          E->getType()->isBlockPointerType() ||
2977          E->getType()->isObjCQualifiedIdType()) &&
2978         "EvalAddr only works on pointers");
2979
2980  E = E->IgnoreParens();
2981
2982  // Our "symbolic interpreter" is just a dispatch off the currently
2983  // viewed AST node.  We then recursively traverse the AST by calling
2984  // EvalAddr and EvalVal appropriately.
2985  switch (E->getStmtClass()) {
2986  case Stmt::DeclRefExprClass: {
2987    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2988
2989    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2990      // If this is a reference variable, follow through to the expression that
2991      // it points to.
2992      if (V->hasLocalStorage() &&
2993          V->getType()->isReferenceType() && V->hasInit()) {
2994        // Add the reference variable to the "trail".
2995        refVars.push_back(DR);
2996        return EvalAddr(V->getInit(), refVars);
2997      }
2998
2999    return NULL;
3000  }
3001
3002  case Stmt::UnaryOperatorClass: {
3003    // The only unary operator that make sense to handle here
3004    // is AddrOf.  All others don't make sense as pointers.
3005    UnaryOperator *U = cast<UnaryOperator>(E);
3006
3007    if (U->getOpcode() == UO_AddrOf)
3008      return EvalVal(U->getSubExpr(), refVars);
3009    else
3010      return NULL;
3011  }
3012
3013  case Stmt::BinaryOperatorClass: {
3014    // Handle pointer arithmetic.  All other binary operators are not valid
3015    // in this context.
3016    BinaryOperator *B = cast<BinaryOperator>(E);
3017    BinaryOperatorKind op = B->getOpcode();
3018
3019    if (op != BO_Add && op != BO_Sub)
3020      return NULL;
3021
3022    Expr *Base = B->getLHS();
3023
3024    // Determine which argument is the real pointer base.  It could be
3025    // the RHS argument instead of the LHS.
3026    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3027
3028    assert (Base->getType()->isPointerType());
3029    return EvalAddr(Base, refVars);
3030  }
3031
3032  // For conditional operators we need to see if either the LHS or RHS are
3033  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3034  case Stmt::ConditionalOperatorClass: {
3035    ConditionalOperator *C = cast<ConditionalOperator>(E);
3036
3037    // Handle the GNU extension for missing LHS.
3038    if (Expr *lhsExpr = C->getLHS()) {
3039    // In C++, we can have a throw-expression, which has 'void' type.
3040      if (!lhsExpr->getType()->isVoidType())
3041        if (Expr* LHS = EvalAddr(lhsExpr, refVars))
3042          return LHS;
3043    }
3044
3045    // In C++, we can have a throw-expression, which has 'void' type.
3046    if (C->getRHS()->getType()->isVoidType())
3047      return NULL;
3048
3049    return EvalAddr(C->getRHS(), refVars);
3050  }
3051
3052  case Stmt::BlockExprClass:
3053    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3054      return E; // local block.
3055    return NULL;
3056
3057  case Stmt::AddrLabelExprClass:
3058    return E; // address of label.
3059
3060  case Stmt::ExprWithCleanupsClass:
3061    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
3062
3063  // For casts, we need to handle conversions from arrays to
3064  // pointer values, and pointer-to-pointer conversions.
3065  case Stmt::ImplicitCastExprClass:
3066  case Stmt::CStyleCastExprClass:
3067  case Stmt::CXXFunctionalCastExprClass:
3068  case Stmt::ObjCBridgedCastExprClass:
3069  case Stmt::CXXStaticCastExprClass:
3070  case Stmt::CXXDynamicCastExprClass:
3071  case Stmt::CXXConstCastExprClass:
3072  case Stmt::CXXReinterpretCastExprClass: {
3073    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3074    switch (cast<CastExpr>(E)->getCastKind()) {
3075    case CK_BitCast:
3076    case CK_LValueToRValue:
3077    case CK_NoOp:
3078    case CK_BaseToDerived:
3079    case CK_DerivedToBase:
3080    case CK_UncheckedDerivedToBase:
3081    case CK_Dynamic:
3082    case CK_CPointerToObjCPointerCast:
3083    case CK_BlockPointerToObjCPointerCast:
3084    case CK_AnyPointerToBlockPointerCast:
3085      return EvalAddr(SubExpr, refVars);
3086
3087    case CK_ArrayToPointerDecay:
3088      return EvalVal(SubExpr, refVars);
3089
3090    default:
3091      return 0;
3092    }
3093  }
3094
3095  case Stmt::MaterializeTemporaryExprClass:
3096    if (Expr *Result = EvalAddr(
3097                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3098                                refVars))
3099      return Result;
3100
3101    return E;
3102
3103  // Everything else: we simply don't reason about them.
3104  default:
3105    return NULL;
3106  }
3107}
3108
3109
3110///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3111///   See the comments for EvalAddr for more details.
3112static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
3113do {
3114  // We should only be called for evaluating non-pointer expressions, or
3115  // expressions with a pointer type that are not used as references but instead
3116  // are l-values (e.g., DeclRefExpr with a pointer type).
3117
3118  // Our "symbolic interpreter" is just a dispatch off the currently
3119  // viewed AST node.  We then recursively traverse the AST by calling
3120  // EvalAddr and EvalVal appropriately.
3121
3122  E = E->IgnoreParens();
3123  switch (E->getStmtClass()) {
3124  case Stmt::ImplicitCastExprClass: {
3125    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3126    if (IE->getValueKind() == VK_LValue) {
3127      E = IE->getSubExpr();
3128      continue;
3129    }
3130    return NULL;
3131  }
3132
3133  case Stmt::ExprWithCleanupsClass:
3134    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
3135
3136  case Stmt::DeclRefExprClass: {
3137    // When we hit a DeclRefExpr we are looking at code that refers to a
3138    // variable's name. If it's not a reference variable we check if it has
3139    // local storage within the function, and if so, return the expression.
3140    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3141
3142    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3143      if (V->hasLocalStorage()) {
3144        if (!V->getType()->isReferenceType())
3145          return DR;
3146
3147        // Reference variable, follow through to the expression that
3148        // it points to.
3149        if (V->hasInit()) {
3150          // Add the reference variable to the "trail".
3151          refVars.push_back(DR);
3152          return EvalVal(V->getInit(), refVars);
3153        }
3154      }
3155
3156    return NULL;
3157  }
3158
3159  case Stmt::UnaryOperatorClass: {
3160    // The only unary operator that make sense to handle here
3161    // is Deref.  All others don't resolve to a "name."  This includes
3162    // handling all sorts of rvalues passed to a unary operator.
3163    UnaryOperator *U = cast<UnaryOperator>(E);
3164
3165    if (U->getOpcode() == UO_Deref)
3166      return EvalAddr(U->getSubExpr(), refVars);
3167
3168    return NULL;
3169  }
3170
3171  case Stmt::ArraySubscriptExprClass: {
3172    // Array subscripts are potential references to data on the stack.  We
3173    // retrieve the DeclRefExpr* for the array variable if it indeed
3174    // has local storage.
3175    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars);
3176  }
3177
3178  case Stmt::ConditionalOperatorClass: {
3179    // For conditional operators we need to see if either the LHS or RHS are
3180    // non-NULL Expr's.  If one is non-NULL, we return it.
3181    ConditionalOperator *C = cast<ConditionalOperator>(E);
3182
3183    // Handle the GNU extension for missing LHS.
3184    if (Expr *lhsExpr = C->getLHS())
3185      if (Expr *LHS = EvalVal(lhsExpr, refVars))
3186        return LHS;
3187
3188    return EvalVal(C->getRHS(), refVars);
3189  }
3190
3191  // Accesses to members are potential references to data on the stack.
3192  case Stmt::MemberExprClass: {
3193    MemberExpr *M = cast<MemberExpr>(E);
3194
3195    // Check for indirect access.  We only want direct field accesses.
3196    if (M->isArrow())
3197      return NULL;
3198
3199    // Check whether the member type is itself a reference, in which case
3200    // we're not going to refer to the member, but to what the member refers to.
3201    if (M->getMemberDecl()->getType()->isReferenceType())
3202      return NULL;
3203
3204    return EvalVal(M->getBase(), refVars);
3205  }
3206
3207  case Stmt::MaterializeTemporaryExprClass:
3208    if (Expr *Result = EvalVal(
3209                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3210                               refVars))
3211      return Result;
3212
3213    return E;
3214
3215  default:
3216    // Check that we don't return or take the address of a reference to a
3217    // temporary. This is only useful in C++.
3218    if (!E->isTypeDependent() && E->isRValue())
3219      return E;
3220
3221    // Everything else: we simply don't reason about them.
3222    return NULL;
3223  }
3224} while (true);
3225}
3226
3227//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3228
3229/// Check for comparisons of floating point operands using != and ==.
3230/// Issue a warning if these are no self-comparisons, as they are not likely
3231/// to do what the programmer intended.
3232void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3233  bool EmitWarning = true;
3234
3235  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3236  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3237
3238  // Special case: check for x == x (which is OK).
3239  // Do not emit warnings for such cases.
3240  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3241    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3242      if (DRL->getDecl() == DRR->getDecl())
3243        EmitWarning = false;
3244
3245
3246  // Special case: check for comparisons against literals that can be exactly
3247  //  represented by APFloat.  In such cases, do not emit a warning.  This
3248  //  is a heuristic: often comparison against such literals are used to
3249  //  detect if a value in a variable has not changed.  This clearly can
3250  //  lead to false negatives.
3251  if (EmitWarning) {
3252    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3253      if (FLL->isExact())
3254        EmitWarning = false;
3255    } else
3256      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
3257        if (FLR->isExact())
3258          EmitWarning = false;
3259    }
3260  }
3261
3262  // Check for comparisons with builtin types.
3263  if (EmitWarning)
3264    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3265      if (CL->isBuiltinCall())
3266        EmitWarning = false;
3267
3268  if (EmitWarning)
3269    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3270      if (CR->isBuiltinCall())
3271        EmitWarning = false;
3272
3273  // Emit the diagnostic.
3274  if (EmitWarning)
3275    Diag(Loc, diag::warn_floatingpoint_eq)
3276      << LHS->getSourceRange() << RHS->getSourceRange();
3277}
3278
3279//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3280//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3281
3282namespace {
3283
3284/// Structure recording the 'active' range of an integer-valued
3285/// expression.
3286struct IntRange {
3287  /// The number of bits active in the int.
3288  unsigned Width;
3289
3290  /// True if the int is known not to have negative values.
3291  bool NonNegative;
3292
3293  IntRange(unsigned Width, bool NonNegative)
3294    : Width(Width), NonNegative(NonNegative)
3295  {}
3296
3297  /// Returns the range of the bool type.
3298  static IntRange forBoolType() {
3299    return IntRange(1, true);
3300  }
3301
3302  /// Returns the range of an opaque value of the given integral type.
3303  static IntRange forValueOfType(ASTContext &C, QualType T) {
3304    return forValueOfCanonicalType(C,
3305                          T->getCanonicalTypeInternal().getTypePtr());
3306  }
3307
3308  /// Returns the range of an opaque value of a canonical integral type.
3309  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3310    assert(T->isCanonicalUnqualified());
3311
3312    if (const VectorType *VT = dyn_cast<VectorType>(T))
3313      T = VT->getElementType().getTypePtr();
3314    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3315      T = CT->getElementType().getTypePtr();
3316
3317    // For enum types, use the known bit width of the enumerators.
3318    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3319      EnumDecl *Enum = ET->getDecl();
3320      if (!Enum->isCompleteDefinition())
3321        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3322
3323      unsigned NumPositive = Enum->getNumPositiveBits();
3324      unsigned NumNegative = Enum->getNumNegativeBits();
3325
3326      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3327    }
3328
3329    const BuiltinType *BT = cast<BuiltinType>(T);
3330    assert(BT->isInteger());
3331
3332    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3333  }
3334
3335  /// Returns the "target" range of a canonical integral type, i.e.
3336  /// the range of values expressible in the type.
3337  ///
3338  /// This matches forValueOfCanonicalType except that enums have the
3339  /// full range of their type, not the range of their enumerators.
3340  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3341    assert(T->isCanonicalUnqualified());
3342
3343    if (const VectorType *VT = dyn_cast<VectorType>(T))
3344      T = VT->getElementType().getTypePtr();
3345    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3346      T = CT->getElementType().getTypePtr();
3347    if (const EnumType *ET = dyn_cast<EnumType>(T))
3348      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3349
3350    const BuiltinType *BT = cast<BuiltinType>(T);
3351    assert(BT->isInteger());
3352
3353    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3354  }
3355
3356  /// Returns the supremum of two ranges: i.e. their conservative merge.
3357  static IntRange join(IntRange L, IntRange R) {
3358    return IntRange(std::max(L.Width, R.Width),
3359                    L.NonNegative && R.NonNegative);
3360  }
3361
3362  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3363  static IntRange meet(IntRange L, IntRange R) {
3364    return IntRange(std::min(L.Width, R.Width),
3365                    L.NonNegative || R.NonNegative);
3366  }
3367};
3368
3369static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
3370                              unsigned MaxWidth) {
3371  if (value.isSigned() && value.isNegative())
3372    return IntRange(value.getMinSignedBits(), false);
3373
3374  if (value.getBitWidth() > MaxWidth)
3375    value = value.trunc(MaxWidth);
3376
3377  // isNonNegative() just checks the sign bit without considering
3378  // signedness.
3379  return IntRange(value.getActiveBits(), true);
3380}
3381
3382static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3383                              unsigned MaxWidth) {
3384  if (result.isInt())
3385    return GetValueRange(C, result.getInt(), MaxWidth);
3386
3387  if (result.isVector()) {
3388    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3389    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3390      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3391      R = IntRange::join(R, El);
3392    }
3393    return R;
3394  }
3395
3396  if (result.isComplexInt()) {
3397    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3398    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3399    return IntRange::join(R, I);
3400  }
3401
3402  // This can happen with lossless casts to intptr_t of "based" lvalues.
3403  // Assume it might use arbitrary bits.
3404  // FIXME: The only reason we need to pass the type in here is to get
3405  // the sign right on this one case.  It would be nice if APValue
3406  // preserved this.
3407  assert(result.isLValue() || result.isAddrLabelDiff());
3408  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
3409}
3410
3411/// Pseudo-evaluate the given integer expression, estimating the
3412/// range of values it might take.
3413///
3414/// \param MaxWidth - the width to which the value will be truncated
3415static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
3416  E = E->IgnoreParens();
3417
3418  // Try a full evaluation first.
3419  Expr::EvalResult result;
3420  if (E->EvaluateAsRValue(result, C))
3421    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
3422
3423  // I think we only want to look through implicit casts here; if the
3424  // user has an explicit widening cast, we should treat the value as
3425  // being of the new, wider type.
3426  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
3427    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
3428      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
3429
3430    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
3431
3432    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
3433
3434    // Assume that non-integer casts can span the full range of the type.
3435    if (!isIntegerCast)
3436      return OutputTypeRange;
3437
3438    IntRange SubRange
3439      = GetExprRange(C, CE->getSubExpr(),
3440                     std::min(MaxWidth, OutputTypeRange.Width));
3441
3442    // Bail out if the subexpr's range is as wide as the cast type.
3443    if (SubRange.Width >= OutputTypeRange.Width)
3444      return OutputTypeRange;
3445
3446    // Otherwise, we take the smaller width, and we're non-negative if
3447    // either the output type or the subexpr is.
3448    return IntRange(SubRange.Width,
3449                    SubRange.NonNegative || OutputTypeRange.NonNegative);
3450  }
3451
3452  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3453    // If we can fold the condition, just take that operand.
3454    bool CondResult;
3455    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
3456      return GetExprRange(C, CondResult ? CO->getTrueExpr()
3457                                        : CO->getFalseExpr(),
3458                          MaxWidth);
3459
3460    // Otherwise, conservatively merge.
3461    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
3462    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
3463    return IntRange::join(L, R);
3464  }
3465
3466  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3467    switch (BO->getOpcode()) {
3468
3469    // Boolean-valued operations are single-bit and positive.
3470    case BO_LAnd:
3471    case BO_LOr:
3472    case BO_LT:
3473    case BO_GT:
3474    case BO_LE:
3475    case BO_GE:
3476    case BO_EQ:
3477    case BO_NE:
3478      return IntRange::forBoolType();
3479
3480    // The type of the assignments is the type of the LHS, so the RHS
3481    // is not necessarily the same type.
3482    case BO_MulAssign:
3483    case BO_DivAssign:
3484    case BO_RemAssign:
3485    case BO_AddAssign:
3486    case BO_SubAssign:
3487    case BO_XorAssign:
3488    case BO_OrAssign:
3489      // TODO: bitfields?
3490      return IntRange::forValueOfType(C, E->getType());
3491
3492    // Simple assignments just pass through the RHS, which will have
3493    // been coerced to the LHS type.
3494    case BO_Assign:
3495      // TODO: bitfields?
3496      return GetExprRange(C, BO->getRHS(), MaxWidth);
3497
3498    // Operations with opaque sources are black-listed.
3499    case BO_PtrMemD:
3500    case BO_PtrMemI:
3501      return IntRange::forValueOfType(C, E->getType());
3502
3503    // Bitwise-and uses the *infinum* of the two source ranges.
3504    case BO_And:
3505    case BO_AndAssign:
3506      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
3507                            GetExprRange(C, BO->getRHS(), MaxWidth));
3508
3509    // Left shift gets black-listed based on a judgement call.
3510    case BO_Shl:
3511      // ...except that we want to treat '1 << (blah)' as logically
3512      // positive.  It's an important idiom.
3513      if (IntegerLiteral *I
3514            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
3515        if (I->getValue() == 1) {
3516          IntRange R = IntRange::forValueOfType(C, E->getType());
3517          return IntRange(R.Width, /*NonNegative*/ true);
3518        }
3519      }
3520      // fallthrough
3521
3522    case BO_ShlAssign:
3523      return IntRange::forValueOfType(C, E->getType());
3524
3525    // Right shift by a constant can narrow its left argument.
3526    case BO_Shr:
3527    case BO_ShrAssign: {
3528      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3529
3530      // If the shift amount is a positive constant, drop the width by
3531      // that much.
3532      llvm::APSInt shift;
3533      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
3534          shift.isNonNegative()) {
3535        unsigned zext = shift.getZExtValue();
3536        if (zext >= L.Width)
3537          L.Width = (L.NonNegative ? 0 : 1);
3538        else
3539          L.Width -= zext;
3540      }
3541
3542      return L;
3543    }
3544
3545    // Comma acts as its right operand.
3546    case BO_Comma:
3547      return GetExprRange(C, BO->getRHS(), MaxWidth);
3548
3549    // Black-list pointer subtractions.
3550    case BO_Sub:
3551      if (BO->getLHS()->getType()->isPointerType())
3552        return IntRange::forValueOfType(C, E->getType());
3553      break;
3554
3555    // The width of a division result is mostly determined by the size
3556    // of the LHS.
3557    case BO_Div: {
3558      // Don't 'pre-truncate' the operands.
3559      unsigned opWidth = C.getIntWidth(E->getType());
3560      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3561
3562      // If the divisor is constant, use that.
3563      llvm::APSInt divisor;
3564      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
3565        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
3566        if (log2 >= L.Width)
3567          L.Width = (L.NonNegative ? 0 : 1);
3568        else
3569          L.Width = std::min(L.Width - log2, MaxWidth);
3570        return L;
3571      }
3572
3573      // Otherwise, just use the LHS's width.
3574      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3575      return IntRange(L.Width, L.NonNegative && R.NonNegative);
3576    }
3577
3578    // The result of a remainder can't be larger than the result of
3579    // either side.
3580    case BO_Rem: {
3581      // Don't 'pre-truncate' the operands.
3582      unsigned opWidth = C.getIntWidth(E->getType());
3583      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3584      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3585
3586      IntRange meet = IntRange::meet(L, R);
3587      meet.Width = std::min(meet.Width, MaxWidth);
3588      return meet;
3589    }
3590
3591    // The default behavior is okay for these.
3592    case BO_Mul:
3593    case BO_Add:
3594    case BO_Xor:
3595    case BO_Or:
3596      break;
3597    }
3598
3599    // The default case is to treat the operation as if it were closed
3600    // on the narrowest type that encompasses both operands.
3601    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3602    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
3603    return IntRange::join(L, R);
3604  }
3605
3606  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
3607    switch (UO->getOpcode()) {
3608    // Boolean-valued operations are white-listed.
3609    case UO_LNot:
3610      return IntRange::forBoolType();
3611
3612    // Operations with opaque sources are black-listed.
3613    case UO_Deref:
3614    case UO_AddrOf: // should be impossible
3615      return IntRange::forValueOfType(C, E->getType());
3616
3617    default:
3618      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
3619    }
3620  }
3621
3622  if (dyn_cast<OffsetOfExpr>(E)) {
3623    IntRange::forValueOfType(C, E->getType());
3624  }
3625
3626  if (FieldDecl *BitField = E->getBitField())
3627    return IntRange(BitField->getBitWidthValue(C),
3628                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
3629
3630  return IntRange::forValueOfType(C, E->getType());
3631}
3632
3633static IntRange GetExprRange(ASTContext &C, Expr *E) {
3634  return GetExprRange(C, E, C.getIntWidth(E->getType()));
3635}
3636
3637/// Checks whether the given value, which currently has the given
3638/// source semantics, has the same value when coerced through the
3639/// target semantics.
3640static bool IsSameFloatAfterCast(const llvm::APFloat &value,
3641                                 const llvm::fltSemantics &Src,
3642                                 const llvm::fltSemantics &Tgt) {
3643  llvm::APFloat truncated = value;
3644
3645  bool ignored;
3646  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
3647  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
3648
3649  return truncated.bitwiseIsEqual(value);
3650}
3651
3652/// Checks whether the given value, which currently has the given
3653/// source semantics, has the same value when coerced through the
3654/// target semantics.
3655///
3656/// The value might be a vector of floats (or a complex number).
3657static bool IsSameFloatAfterCast(const APValue &value,
3658                                 const llvm::fltSemantics &Src,
3659                                 const llvm::fltSemantics &Tgt) {
3660  if (value.isFloat())
3661    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
3662
3663  if (value.isVector()) {
3664    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
3665      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
3666        return false;
3667    return true;
3668  }
3669
3670  assert(value.isComplexFloat());
3671  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
3672          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
3673}
3674
3675static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
3676
3677static bool IsZero(Sema &S, Expr *E) {
3678  // Suppress cases where we are comparing against an enum constant.
3679  if (const DeclRefExpr *DR =
3680      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
3681    if (isa<EnumConstantDecl>(DR->getDecl()))
3682      return false;
3683
3684  // Suppress cases where the '0' value is expanded from a macro.
3685  if (E->getLocStart().isMacroID())
3686    return false;
3687
3688  llvm::APSInt Value;
3689  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
3690}
3691
3692static bool HasEnumType(Expr *E) {
3693  // Strip off implicit integral promotions.
3694  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
3695    if (ICE->getCastKind() != CK_IntegralCast &&
3696        ICE->getCastKind() != CK_NoOp)
3697      break;
3698    E = ICE->getSubExpr();
3699  }
3700
3701  return E->getType()->isEnumeralType();
3702}
3703
3704static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
3705  BinaryOperatorKind op = E->getOpcode();
3706  if (E->isValueDependent())
3707    return;
3708
3709  if (op == BO_LT && IsZero(S, E->getRHS())) {
3710    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3711      << "< 0" << "false" << HasEnumType(E->getLHS())
3712      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3713  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
3714    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3715      << ">= 0" << "true" << HasEnumType(E->getLHS())
3716      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3717  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
3718    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3719      << "0 >" << "false" << HasEnumType(E->getRHS())
3720      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3721  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
3722    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3723      << "0 <=" << "true" << HasEnumType(E->getRHS())
3724      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3725  }
3726}
3727
3728/// Analyze the operands of the given comparison.  Implements the
3729/// fallback case from AnalyzeComparison.
3730static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
3731  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3732  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3733}
3734
3735/// \brief Implements -Wsign-compare.
3736///
3737/// \param E the binary operator to check for warnings
3738static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
3739  // The type the comparison is being performed in.
3740  QualType T = E->getLHS()->getType();
3741  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
3742         && "comparison with mismatched types");
3743
3744  // We don't do anything special if this isn't an unsigned integral
3745  // comparison:  we're only interested in integral comparisons, and
3746  // signed comparisons only happen in cases we don't care to warn about.
3747  //
3748  // We also don't care about value-dependent expressions or expressions
3749  // whose result is a constant.
3750  if (!T->hasUnsignedIntegerRepresentation()
3751      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
3752    return AnalyzeImpConvsInComparison(S, E);
3753
3754  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
3755  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
3756
3757  // Check to see if one of the (unmodified) operands is of different
3758  // signedness.
3759  Expr *signedOperand, *unsignedOperand;
3760  if (LHS->getType()->hasSignedIntegerRepresentation()) {
3761    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
3762           "unsigned comparison between two signed integer expressions?");
3763    signedOperand = LHS;
3764    unsignedOperand = RHS;
3765  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
3766    signedOperand = RHS;
3767    unsignedOperand = LHS;
3768  } else {
3769    CheckTrivialUnsignedComparison(S, E);
3770    return AnalyzeImpConvsInComparison(S, E);
3771  }
3772
3773  // Otherwise, calculate the effective range of the signed operand.
3774  IntRange signedRange = GetExprRange(S.Context, signedOperand);
3775
3776  // Go ahead and analyze implicit conversions in the operands.  Note
3777  // that we skip the implicit conversions on both sides.
3778  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
3779  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
3780
3781  // If the signed range is non-negative, -Wsign-compare won't fire,
3782  // but we should still check for comparisons which are always true
3783  // or false.
3784  if (signedRange.NonNegative)
3785    return CheckTrivialUnsignedComparison(S, E);
3786
3787  // For (in)equality comparisons, if the unsigned operand is a
3788  // constant which cannot collide with a overflowed signed operand,
3789  // then reinterpreting the signed operand as unsigned will not
3790  // change the result of the comparison.
3791  if (E->isEqualityOp()) {
3792    unsigned comparisonWidth = S.Context.getIntWidth(T);
3793    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
3794
3795    // We should never be unable to prove that the unsigned operand is
3796    // non-negative.
3797    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
3798
3799    if (unsignedRange.Width < comparisonWidth)
3800      return;
3801  }
3802
3803  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
3804    << LHS->getType() << RHS->getType()
3805    << LHS->getSourceRange() << RHS->getSourceRange();
3806}
3807
3808/// Analyzes an attempt to assign the given value to a bitfield.
3809///
3810/// Returns true if there was something fishy about the attempt.
3811static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
3812                                      SourceLocation InitLoc) {
3813  assert(Bitfield->isBitField());
3814  if (Bitfield->isInvalidDecl())
3815    return false;
3816
3817  // White-list bool bitfields.
3818  if (Bitfield->getType()->isBooleanType())
3819    return false;
3820
3821  // Ignore value- or type-dependent expressions.
3822  if (Bitfield->getBitWidth()->isValueDependent() ||
3823      Bitfield->getBitWidth()->isTypeDependent() ||
3824      Init->isValueDependent() ||
3825      Init->isTypeDependent())
3826    return false;
3827
3828  Expr *OriginalInit = Init->IgnoreParenImpCasts();
3829
3830  llvm::APSInt Value;
3831  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
3832    return false;
3833
3834  unsigned OriginalWidth = Value.getBitWidth();
3835  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
3836
3837  if (OriginalWidth <= FieldWidth)
3838    return false;
3839
3840  // Compute the value which the bitfield will contain.
3841  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
3842  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
3843
3844  // Check whether the stored value is equal to the original value.
3845  TruncatedValue = TruncatedValue.extend(OriginalWidth);
3846  if (Value == TruncatedValue)
3847    return false;
3848
3849  // Special-case bitfields of width 1: booleans are naturally 0/1, and
3850  // therefore don't strictly fit into a signed bitfield of width 1.
3851  if (FieldWidth == 1 && Value == 1)
3852    return false;
3853
3854  std::string PrettyValue = Value.toString(10);
3855  std::string PrettyTrunc = TruncatedValue.toString(10);
3856
3857  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
3858    << PrettyValue << PrettyTrunc << OriginalInit->getType()
3859    << Init->getSourceRange();
3860
3861  return true;
3862}
3863
3864/// Analyze the given simple or compound assignment for warning-worthy
3865/// operations.
3866static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
3867  // Just recurse on the LHS.
3868  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3869
3870  // We want to recurse on the RHS as normal unless we're assigning to
3871  // a bitfield.
3872  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
3873    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
3874                                  E->getOperatorLoc())) {
3875      // Recurse, ignoring any implicit conversions on the RHS.
3876      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
3877                                        E->getOperatorLoc());
3878    }
3879  }
3880
3881  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3882}
3883
3884/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3885static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
3886                            SourceLocation CContext, unsigned diag,
3887                            bool pruneControlFlow = false) {
3888  if (pruneControlFlow) {
3889    S.DiagRuntimeBehavior(E->getExprLoc(), E,
3890                          S.PDiag(diag)
3891                            << SourceType << T << E->getSourceRange()
3892                            << SourceRange(CContext));
3893    return;
3894  }
3895  S.Diag(E->getExprLoc(), diag)
3896    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
3897}
3898
3899/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3900static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
3901                            SourceLocation CContext, unsigned diag,
3902                            bool pruneControlFlow = false) {
3903  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
3904}
3905
3906/// Diagnose an implicit cast from a literal expression. Does not warn when the
3907/// cast wouldn't lose information.
3908void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
3909                                    SourceLocation CContext) {
3910  // Try to convert the literal exactly to an integer. If we can, don't warn.
3911  bool isExact = false;
3912  const llvm::APFloat &Value = FL->getValue();
3913  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
3914                            T->hasUnsignedIntegerRepresentation());
3915  if (Value.convertToInteger(IntegerValue,
3916                             llvm::APFloat::rmTowardZero, &isExact)
3917      == llvm::APFloat::opOK && isExact)
3918    return;
3919
3920  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
3921    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
3922}
3923
3924std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
3925  if (!Range.Width) return "0";
3926
3927  llvm::APSInt ValueInRange = Value;
3928  ValueInRange.setIsSigned(!Range.NonNegative);
3929  ValueInRange = ValueInRange.trunc(Range.Width);
3930  return ValueInRange.toString(10);
3931}
3932
3933void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
3934                             SourceLocation CC, bool *ICContext = 0) {
3935  if (E->isTypeDependent() || E->isValueDependent()) return;
3936
3937  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
3938  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
3939  if (Source == Target) return;
3940  if (Target->isDependentType()) return;
3941
3942  // If the conversion context location is invalid don't complain. We also
3943  // don't want to emit a warning if the issue occurs from the expansion of
3944  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
3945  // delay this check as long as possible. Once we detect we are in that
3946  // scenario, we just return.
3947  if (CC.isInvalid())
3948    return;
3949
3950  // Diagnose implicit casts to bool.
3951  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
3952    if (isa<StringLiteral>(E))
3953      // Warn on string literal to bool.  Checks for string literals in logical
3954      // expressions, for instances, assert(0 && "error here"), is prevented
3955      // by a check in AnalyzeImplicitConversions().
3956      return DiagnoseImpCast(S, E, T, CC,
3957                             diag::warn_impcast_string_literal_to_bool);
3958    if (Source->isFunctionType()) {
3959      // Warn on function to bool. Checks free functions and static member
3960      // functions. Weakly imported functions are excluded from the check,
3961      // since it's common to test their value to check whether the linker
3962      // found a definition for them.
3963      ValueDecl *D = 0;
3964      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
3965        D = R->getDecl();
3966      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
3967        D = M->getMemberDecl();
3968      }
3969
3970      if (D && !D->isWeak()) {
3971        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
3972          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
3973            << F << E->getSourceRange() << SourceRange(CC);
3974          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
3975            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
3976          QualType ReturnType;
3977          UnresolvedSet<4> NonTemplateOverloads;
3978          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
3979          if (!ReturnType.isNull()
3980              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
3981            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
3982              << FixItHint::CreateInsertion(
3983                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
3984          return;
3985        }
3986      }
3987    }
3988    return; // Other casts to bool are not checked.
3989  }
3990
3991  // Strip vector types.
3992  if (isa<VectorType>(Source)) {
3993    if (!isa<VectorType>(Target)) {
3994      if (S.SourceMgr.isInSystemMacro(CC))
3995        return;
3996      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
3997    }
3998
3999    // If the vector cast is cast between two vectors of the same size, it is
4000    // a bitcast, not a conversion.
4001    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4002      return;
4003
4004    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4005    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4006  }
4007
4008  // Strip complex types.
4009  if (isa<ComplexType>(Source)) {
4010    if (!isa<ComplexType>(Target)) {
4011      if (S.SourceMgr.isInSystemMacro(CC))
4012        return;
4013
4014      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4015    }
4016
4017    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4018    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4019  }
4020
4021  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4022  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4023
4024  // If the source is floating point...
4025  if (SourceBT && SourceBT->isFloatingPoint()) {
4026    // ...and the target is floating point...
4027    if (TargetBT && TargetBT->isFloatingPoint()) {
4028      // ...then warn if we're dropping FP rank.
4029
4030      // Builtin FP kinds are ordered by increasing FP rank.
4031      if (SourceBT->getKind() > TargetBT->getKind()) {
4032        // Don't warn about float constants that are precisely
4033        // representable in the target type.
4034        Expr::EvalResult result;
4035        if (E->EvaluateAsRValue(result, S.Context)) {
4036          // Value might be a float, a float vector, or a float complex.
4037          if (IsSameFloatAfterCast(result.Val,
4038                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4039                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4040            return;
4041        }
4042
4043        if (S.SourceMgr.isInSystemMacro(CC))
4044          return;
4045
4046        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4047      }
4048      return;
4049    }
4050
4051    // If the target is integral, always warn.
4052    if ((TargetBT && TargetBT->isInteger())) {
4053      if (S.SourceMgr.isInSystemMacro(CC))
4054        return;
4055
4056      Expr *InnerE = E->IgnoreParenImpCasts();
4057      // We also want to warn on, e.g., "int i = -1.234"
4058      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4059        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4060          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4061
4062      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4063        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4064      } else {
4065        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4066      }
4067    }
4068
4069    return;
4070  }
4071
4072  if (!Source->isIntegerType() || !Target->isIntegerType())
4073    return;
4074
4075  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4076           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
4077    SourceLocation Loc = E->getSourceRange().getBegin();
4078    if (Loc.isMacroID())
4079      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4080    S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4081        << T << Loc << clang::SourceRange(CC);
4082    return;
4083  }
4084
4085  IntRange SourceRange = GetExprRange(S.Context, E);
4086  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
4087
4088  if (SourceRange.Width > TargetRange.Width) {
4089    // If the source is a constant, use a default-on diagnostic.
4090    // TODO: this should happen for bitfield stores, too.
4091    llvm::APSInt Value(32);
4092    if (E->isIntegerConstantExpr(Value, S.Context)) {
4093      if (S.SourceMgr.isInSystemMacro(CC))
4094        return;
4095
4096      std::string PrettySourceValue = Value.toString(10);
4097      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
4098
4099      S.DiagRuntimeBehavior(E->getExprLoc(), E,
4100        S.PDiag(diag::warn_impcast_integer_precision_constant)
4101            << PrettySourceValue << PrettyTargetValue
4102            << E->getType() << T << E->getSourceRange()
4103            << clang::SourceRange(CC));
4104      return;
4105    }
4106
4107    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
4108    if (S.SourceMgr.isInSystemMacro(CC))
4109      return;
4110
4111    if (SourceRange.Width == 64 && TargetRange.Width == 32)
4112      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
4113                             /* pruneControlFlow */ true);
4114    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
4115  }
4116
4117  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
4118      (!TargetRange.NonNegative && SourceRange.NonNegative &&
4119       SourceRange.Width == TargetRange.Width)) {
4120
4121    if (S.SourceMgr.isInSystemMacro(CC))
4122      return;
4123
4124    unsigned DiagID = diag::warn_impcast_integer_sign;
4125
4126    // Traditionally, gcc has warned about this under -Wsign-compare.
4127    // We also want to warn about it in -Wconversion.
4128    // So if -Wconversion is off, use a completely identical diagnostic
4129    // in the sign-compare group.
4130    // The conditional-checking code will
4131    if (ICContext) {
4132      DiagID = diag::warn_impcast_integer_sign_conditional;
4133      *ICContext = true;
4134    }
4135
4136    return DiagnoseImpCast(S, E, T, CC, DiagID);
4137  }
4138
4139  // Diagnose conversions between different enumeration types.
4140  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
4141  // type, to give us better diagnostics.
4142  QualType SourceType = E->getType();
4143  if (!S.getLangOpts().CPlusPlus) {
4144    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
4145      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
4146        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
4147        SourceType = S.Context.getTypeDeclType(Enum);
4148        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
4149      }
4150  }
4151
4152  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
4153    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
4154      if ((SourceEnum->getDecl()->getIdentifier() ||
4155           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4156          (TargetEnum->getDecl()->getIdentifier() ||
4157           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4158          SourceEnum != TargetEnum) {
4159        if (S.SourceMgr.isInSystemMacro(CC))
4160          return;
4161
4162        return DiagnoseImpCast(S, E, SourceType, T, CC,
4163                               diag::warn_impcast_different_enum_types);
4164      }
4165
4166  return;
4167}
4168
4169void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
4170
4171void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
4172                             SourceLocation CC, bool &ICContext) {
4173  E = E->IgnoreParenImpCasts();
4174
4175  if (isa<ConditionalOperator>(E))
4176    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
4177
4178  AnalyzeImplicitConversions(S, E, CC);
4179  if (E->getType() != T)
4180    return CheckImplicitConversion(S, E, T, CC, &ICContext);
4181  return;
4182}
4183
4184void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
4185  SourceLocation CC = E->getQuestionLoc();
4186
4187  AnalyzeImplicitConversions(S, E->getCond(), CC);
4188
4189  bool Suspicious = false;
4190  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
4191  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
4192
4193  // If -Wconversion would have warned about either of the candidates
4194  // for a signedness conversion to the context type...
4195  if (!Suspicious) return;
4196
4197  // ...but it's currently ignored...
4198  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
4199                                 CC))
4200    return;
4201
4202  // ...then check whether it would have warned about either of the
4203  // candidates for a signedness conversion to the condition type.
4204  if (E->getType() == T) return;
4205
4206  Suspicious = false;
4207  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
4208                          E->getType(), CC, &Suspicious);
4209  if (!Suspicious)
4210    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
4211                            E->getType(), CC, &Suspicious);
4212}
4213
4214/// AnalyzeImplicitConversions - Find and report any interesting
4215/// implicit conversions in the given expression.  There are a couple
4216/// of competing diagnostics here, -Wconversion and -Wsign-compare.
4217void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
4218  QualType T = OrigE->getType();
4219  Expr *E = OrigE->IgnoreParenImpCasts();
4220
4221  if (E->isTypeDependent() || E->isValueDependent())
4222    return;
4223
4224  // For conditional operators, we analyze the arguments as if they
4225  // were being fed directly into the output.
4226  if (isa<ConditionalOperator>(E)) {
4227    ConditionalOperator *CO = cast<ConditionalOperator>(E);
4228    CheckConditionalOperator(S, CO, T);
4229    return;
4230  }
4231
4232  // Go ahead and check any implicit conversions we might have skipped.
4233  // The non-canonical typecheck is just an optimization;
4234  // CheckImplicitConversion will filter out dead implicit conversions.
4235  if (E->getType() != T)
4236    CheckImplicitConversion(S, E, T, CC);
4237
4238  // Now continue drilling into this expression.
4239
4240  // Skip past explicit casts.
4241  if (isa<ExplicitCastExpr>(E)) {
4242    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4243    return AnalyzeImplicitConversions(S, E, CC);
4244  }
4245
4246  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4247    // Do a somewhat different check with comparison operators.
4248    if (BO->isComparisonOp())
4249      return AnalyzeComparison(S, BO);
4250
4251    // And with simple assignments.
4252    if (BO->getOpcode() == BO_Assign)
4253      return AnalyzeAssignment(S, BO);
4254  }
4255
4256  // These break the otherwise-useful invariant below.  Fortunately,
4257  // we don't really need to recurse into them, because any internal
4258  // expressions should have been analyzed already when they were
4259  // built into statements.
4260  if (isa<StmtExpr>(E)) return;
4261
4262  // Don't descend into unevaluated contexts.
4263  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
4264
4265  // Now just recurse over the expression's children.
4266  CC = E->getExprLoc();
4267  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
4268  bool IsLogicalOperator = BO && BO->isLogicalOp();
4269  for (Stmt::child_range I = E->children(); I; ++I) {
4270    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
4271    if (!ChildExpr)
4272      continue;
4273
4274    if (IsLogicalOperator &&
4275        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
4276      // Ignore checking string literals that are in logical operators.
4277      continue;
4278    AnalyzeImplicitConversions(S, ChildExpr, CC);
4279  }
4280}
4281
4282} // end anonymous namespace
4283
4284/// Diagnoses "dangerous" implicit conversions within the given
4285/// expression (which is a full expression).  Implements -Wconversion
4286/// and -Wsign-compare.
4287///
4288/// \param CC the "context" location of the implicit conversion, i.e.
4289///   the most location of the syntactic entity requiring the implicit
4290///   conversion
4291void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
4292  // Don't diagnose in unevaluated contexts.
4293  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
4294    return;
4295
4296  // Don't diagnose for value- or type-dependent expressions.
4297  if (E->isTypeDependent() || E->isValueDependent())
4298    return;
4299
4300  // Check for array bounds violations in cases where the check isn't triggered
4301  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
4302  // ArraySubscriptExpr is on the RHS of a variable initialization.
4303  CheckArrayAccess(E);
4304
4305  // This is not the right CC for (e.g.) a variable initialization.
4306  AnalyzeImplicitConversions(*this, E, CC);
4307}
4308
4309void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
4310                                       FieldDecl *BitField,
4311                                       Expr *Init) {
4312  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
4313}
4314
4315/// CheckParmsForFunctionDef - Check that the parameters of the given
4316/// function are appropriate for the definition of a function. This
4317/// takes care of any checks that cannot be performed on the
4318/// declaration itself, e.g., that the types of each of the function
4319/// parameters are complete.
4320bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
4321                                    bool CheckParameterNames) {
4322  bool HasInvalidParm = false;
4323  for (; P != PEnd; ++P) {
4324    ParmVarDecl *Param = *P;
4325
4326    // C99 6.7.5.3p4: the parameters in a parameter type list in a
4327    // function declarator that is part of a function definition of
4328    // that function shall not have incomplete type.
4329    //
4330    // This is also C++ [dcl.fct]p6.
4331    if (!Param->isInvalidDecl() &&
4332        RequireCompleteType(Param->getLocation(), Param->getType(),
4333                               diag::err_typecheck_decl_incomplete_type)) {
4334      Param->setInvalidDecl();
4335      HasInvalidParm = true;
4336    }
4337
4338    // C99 6.9.1p5: If the declarator includes a parameter type list, the
4339    // declaration of each parameter shall include an identifier.
4340    if (CheckParameterNames &&
4341        Param->getIdentifier() == 0 &&
4342        !Param->isImplicit() &&
4343        !getLangOpts().CPlusPlus)
4344      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
4345
4346    // C99 6.7.5.3p12:
4347    //   If the function declarator is not part of a definition of that
4348    //   function, parameters may have incomplete type and may use the [*]
4349    //   notation in their sequences of declarator specifiers to specify
4350    //   variable length array types.
4351    QualType PType = Param->getOriginalType();
4352    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
4353      if (AT->getSizeModifier() == ArrayType::Star) {
4354        // FIXME: This diagnosic should point the the '[*]' if source-location
4355        // information is added for it.
4356        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
4357      }
4358    }
4359  }
4360
4361  return HasInvalidParm;
4362}
4363
4364/// CheckCastAlign - Implements -Wcast-align, which warns when a
4365/// pointer cast increases the alignment requirements.
4366void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
4367  // This is actually a lot of work to potentially be doing on every
4368  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
4369  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
4370                                          TRange.getBegin())
4371        == DiagnosticsEngine::Ignored)
4372    return;
4373
4374  // Ignore dependent types.
4375  if (T->isDependentType() || Op->getType()->isDependentType())
4376    return;
4377
4378  // Require that the destination be a pointer type.
4379  const PointerType *DestPtr = T->getAs<PointerType>();
4380  if (!DestPtr) return;
4381
4382  // If the destination has alignment 1, we're done.
4383  QualType DestPointee = DestPtr->getPointeeType();
4384  if (DestPointee->isIncompleteType()) return;
4385  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
4386  if (DestAlign.isOne()) return;
4387
4388  // Require that the source be a pointer type.
4389  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
4390  if (!SrcPtr) return;
4391  QualType SrcPointee = SrcPtr->getPointeeType();
4392
4393  // Whitelist casts from cv void*.  We already implicitly
4394  // whitelisted casts to cv void*, since they have alignment 1.
4395  // Also whitelist casts involving incomplete types, which implicitly
4396  // includes 'void'.
4397  if (SrcPointee->isIncompleteType()) return;
4398
4399  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
4400  if (SrcAlign >= DestAlign) return;
4401
4402  Diag(TRange.getBegin(), diag::warn_cast_align)
4403    << Op->getType() << T
4404    << static_cast<unsigned>(SrcAlign.getQuantity())
4405    << static_cast<unsigned>(DestAlign.getQuantity())
4406    << TRange << Op->getSourceRange();
4407}
4408
4409static const Type* getElementType(const Expr *BaseExpr) {
4410  const Type* EltType = BaseExpr->getType().getTypePtr();
4411  if (EltType->isAnyPointerType())
4412    return EltType->getPointeeType().getTypePtr();
4413  else if (EltType->isArrayType())
4414    return EltType->getBaseElementTypeUnsafe();
4415  return EltType;
4416}
4417
4418/// \brief Check whether this array fits the idiom of a size-one tail padded
4419/// array member of a struct.
4420///
4421/// We avoid emitting out-of-bounds access warnings for such arrays as they are
4422/// commonly used to emulate flexible arrays in C89 code.
4423static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
4424                                    const NamedDecl *ND) {
4425  if (Size != 1 || !ND) return false;
4426
4427  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
4428  if (!FD) return false;
4429
4430  // Don't consider sizes resulting from macro expansions or template argument
4431  // substitution to form C89 tail-padded arrays.
4432  ConstantArrayTypeLoc TL =
4433    cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc());
4434  const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr());
4435  if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
4436    return false;
4437
4438  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
4439  if (!RD) return false;
4440  if (RD->isUnion()) return false;
4441  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
4442    if (!CRD->isStandardLayout()) return false;
4443  }
4444
4445  // See if this is the last field decl in the record.
4446  const Decl *D = FD;
4447  while ((D = D->getNextDeclInContext()))
4448    if (isa<FieldDecl>(D))
4449      return false;
4450  return true;
4451}
4452
4453void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
4454                            const ArraySubscriptExpr *ASE,
4455                            bool AllowOnePastEnd, bool IndexNegated) {
4456  IndexExpr = IndexExpr->IgnoreParenImpCasts();
4457  if (IndexExpr->isValueDependent())
4458    return;
4459
4460  const Type *EffectiveType = getElementType(BaseExpr);
4461  BaseExpr = BaseExpr->IgnoreParenCasts();
4462  const ConstantArrayType *ArrayTy =
4463    Context.getAsConstantArrayType(BaseExpr->getType());
4464  if (!ArrayTy)
4465    return;
4466
4467  llvm::APSInt index;
4468  if (!IndexExpr->EvaluateAsInt(index, Context))
4469    return;
4470  if (IndexNegated)
4471    index = -index;
4472
4473  const NamedDecl *ND = NULL;
4474  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4475    ND = dyn_cast<NamedDecl>(DRE->getDecl());
4476  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4477    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4478
4479  if (index.isUnsigned() || !index.isNegative()) {
4480    llvm::APInt size = ArrayTy->getSize();
4481    if (!size.isStrictlyPositive())
4482      return;
4483
4484    const Type* BaseType = getElementType(BaseExpr);
4485    if (BaseType != EffectiveType) {
4486      // Make sure we're comparing apples to apples when comparing index to size
4487      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
4488      uint64_t array_typesize = Context.getTypeSize(BaseType);
4489      // Handle ptrarith_typesize being zero, such as when casting to void*
4490      if (!ptrarith_typesize) ptrarith_typesize = 1;
4491      if (ptrarith_typesize != array_typesize) {
4492        // There's a cast to a different size type involved
4493        uint64_t ratio = array_typesize / ptrarith_typesize;
4494        // TODO: Be smarter about handling cases where array_typesize is not a
4495        // multiple of ptrarith_typesize
4496        if (ptrarith_typesize * ratio == array_typesize)
4497          size *= llvm::APInt(size.getBitWidth(), ratio);
4498      }
4499    }
4500
4501    if (size.getBitWidth() > index.getBitWidth())
4502      index = index.zext(size.getBitWidth());
4503    else if (size.getBitWidth() < index.getBitWidth())
4504      size = size.zext(index.getBitWidth());
4505
4506    // For array subscripting the index must be less than size, but for pointer
4507    // arithmetic also allow the index (offset) to be equal to size since
4508    // computing the next address after the end of the array is legal and
4509    // commonly done e.g. in C++ iterators and range-based for loops.
4510    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
4511      return;
4512
4513    // Also don't warn for arrays of size 1 which are members of some
4514    // structure. These are often used to approximate flexible arrays in C89
4515    // code.
4516    if (IsTailPaddedMemberArray(*this, size, ND))
4517      return;
4518
4519    // Suppress the warning if the subscript expression (as identified by the
4520    // ']' location) and the index expression are both from macro expansions
4521    // within a system header.
4522    if (ASE) {
4523      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
4524          ASE->getRBracketLoc());
4525      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
4526        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
4527            IndexExpr->getLocStart());
4528        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
4529          return;
4530      }
4531    }
4532
4533    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
4534    if (ASE)
4535      DiagID = diag::warn_array_index_exceeds_bounds;
4536
4537    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4538                        PDiag(DiagID) << index.toString(10, true)
4539                          << size.toString(10, true)
4540                          << (unsigned)size.getLimitedValue(~0U)
4541                          << IndexExpr->getSourceRange());
4542  } else {
4543    unsigned DiagID = diag::warn_array_index_precedes_bounds;
4544    if (!ASE) {
4545      DiagID = diag::warn_ptr_arith_precedes_bounds;
4546      if (index.isNegative()) index = -index;
4547    }
4548
4549    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4550                        PDiag(DiagID) << index.toString(10, true)
4551                          << IndexExpr->getSourceRange());
4552  }
4553
4554  if (!ND) {
4555    // Try harder to find a NamedDecl to point at in the note.
4556    while (const ArraySubscriptExpr *ASE =
4557           dyn_cast<ArraySubscriptExpr>(BaseExpr))
4558      BaseExpr = ASE->getBase()->IgnoreParenCasts();
4559    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4560      ND = dyn_cast<NamedDecl>(DRE->getDecl());
4561    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4562      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4563  }
4564
4565  if (ND)
4566    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
4567                        PDiag(diag::note_array_index_out_of_bounds)
4568                          << ND->getDeclName());
4569}
4570
4571void Sema::CheckArrayAccess(const Expr *expr) {
4572  int AllowOnePastEnd = 0;
4573  while (expr) {
4574    expr = expr->IgnoreParenImpCasts();
4575    switch (expr->getStmtClass()) {
4576      case Stmt::ArraySubscriptExprClass: {
4577        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
4578        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
4579                         AllowOnePastEnd > 0);
4580        return;
4581      }
4582      case Stmt::UnaryOperatorClass: {
4583        // Only unwrap the * and & unary operators
4584        const UnaryOperator *UO = cast<UnaryOperator>(expr);
4585        expr = UO->getSubExpr();
4586        switch (UO->getOpcode()) {
4587          case UO_AddrOf:
4588            AllowOnePastEnd++;
4589            break;
4590          case UO_Deref:
4591            AllowOnePastEnd--;
4592            break;
4593          default:
4594            return;
4595        }
4596        break;
4597      }
4598      case Stmt::ConditionalOperatorClass: {
4599        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
4600        if (const Expr *lhs = cond->getLHS())
4601          CheckArrayAccess(lhs);
4602        if (const Expr *rhs = cond->getRHS())
4603          CheckArrayAccess(rhs);
4604        return;
4605      }
4606      default:
4607        return;
4608    }
4609  }
4610}
4611
4612//===--- CHECK: Objective-C retain cycles ----------------------------------//
4613
4614namespace {
4615  struct RetainCycleOwner {
4616    RetainCycleOwner() : Variable(0), Indirect(false) {}
4617    VarDecl *Variable;
4618    SourceRange Range;
4619    SourceLocation Loc;
4620    bool Indirect;
4621
4622    void setLocsFrom(Expr *e) {
4623      Loc = e->getExprLoc();
4624      Range = e->getSourceRange();
4625    }
4626  };
4627}
4628
4629/// Consider whether capturing the given variable can possibly lead to
4630/// a retain cycle.
4631static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
4632  // In ARC, it's captured strongly iff the variable has __strong
4633  // lifetime.  In MRR, it's captured strongly if the variable is
4634  // __block and has an appropriate type.
4635  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4636    return false;
4637
4638  owner.Variable = var;
4639  owner.setLocsFrom(ref);
4640  return true;
4641}
4642
4643static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
4644  while (true) {
4645    e = e->IgnoreParens();
4646    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
4647      switch (cast->getCastKind()) {
4648      case CK_BitCast:
4649      case CK_LValueBitCast:
4650      case CK_LValueToRValue:
4651      case CK_ARCReclaimReturnedObject:
4652        e = cast->getSubExpr();
4653        continue;
4654
4655      default:
4656        return false;
4657      }
4658    }
4659
4660    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
4661      ObjCIvarDecl *ivar = ref->getDecl();
4662      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4663        return false;
4664
4665      // Try to find a retain cycle in the base.
4666      if (!findRetainCycleOwner(S, ref->getBase(), owner))
4667        return false;
4668
4669      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
4670      owner.Indirect = true;
4671      return true;
4672    }
4673
4674    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
4675      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
4676      if (!var) return false;
4677      return considerVariable(var, ref, owner);
4678    }
4679
4680    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
4681      if (member->isArrow()) return false;
4682
4683      // Don't count this as an indirect ownership.
4684      e = member->getBase();
4685      continue;
4686    }
4687
4688    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
4689      // Only pay attention to pseudo-objects on property references.
4690      ObjCPropertyRefExpr *pre
4691        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
4692                                              ->IgnoreParens());
4693      if (!pre) return false;
4694      if (pre->isImplicitProperty()) return false;
4695      ObjCPropertyDecl *property = pre->getExplicitProperty();
4696      if (!property->isRetaining() &&
4697          !(property->getPropertyIvarDecl() &&
4698            property->getPropertyIvarDecl()->getType()
4699              .getObjCLifetime() == Qualifiers::OCL_Strong))
4700          return false;
4701
4702      owner.Indirect = true;
4703      if (pre->isSuperReceiver()) {
4704        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
4705        if (!owner.Variable)
4706          return false;
4707        owner.Loc = pre->getLocation();
4708        owner.Range = pre->getSourceRange();
4709        return true;
4710      }
4711      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
4712                              ->getSourceExpr());
4713      continue;
4714    }
4715
4716    // Array ivars?
4717
4718    return false;
4719  }
4720}
4721
4722namespace {
4723  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
4724    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
4725      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
4726        Variable(variable), Capturer(0) {}
4727
4728    VarDecl *Variable;
4729    Expr *Capturer;
4730
4731    void VisitDeclRefExpr(DeclRefExpr *ref) {
4732      if (ref->getDecl() == Variable && !Capturer)
4733        Capturer = ref;
4734    }
4735
4736    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
4737      if (Capturer) return;
4738      Visit(ref->getBase());
4739      if (Capturer && ref->isFreeIvar())
4740        Capturer = ref;
4741    }
4742
4743    void VisitBlockExpr(BlockExpr *block) {
4744      // Look inside nested blocks
4745      if (block->getBlockDecl()->capturesVariable(Variable))
4746        Visit(block->getBlockDecl()->getBody());
4747    }
4748  };
4749}
4750
4751/// Check whether the given argument is a block which captures a
4752/// variable.
4753static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
4754  assert(owner.Variable && owner.Loc.isValid());
4755
4756  e = e->IgnoreParenCasts();
4757  BlockExpr *block = dyn_cast<BlockExpr>(e);
4758  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
4759    return 0;
4760
4761  FindCaptureVisitor visitor(S.Context, owner.Variable);
4762  visitor.Visit(block->getBlockDecl()->getBody());
4763  return visitor.Capturer;
4764}
4765
4766static void diagnoseRetainCycle(Sema &S, Expr *capturer,
4767                                RetainCycleOwner &owner) {
4768  assert(capturer);
4769  assert(owner.Variable && owner.Loc.isValid());
4770
4771  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
4772    << owner.Variable << capturer->getSourceRange();
4773  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
4774    << owner.Indirect << owner.Range;
4775}
4776
4777/// Check for a keyword selector that starts with the word 'add' or
4778/// 'set'.
4779static bool isSetterLikeSelector(Selector sel) {
4780  if (sel.isUnarySelector()) return false;
4781
4782  StringRef str = sel.getNameForSlot(0);
4783  while (!str.empty() && str.front() == '_') str = str.substr(1);
4784  if (str.startswith("set"))
4785    str = str.substr(3);
4786  else if (str.startswith("add")) {
4787    // Specially whitelist 'addOperationWithBlock:'.
4788    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
4789      return false;
4790    str = str.substr(3);
4791  }
4792  else
4793    return false;
4794
4795  if (str.empty()) return true;
4796  return !islower(str.front());
4797}
4798
4799/// Check a message send to see if it's likely to cause a retain cycle.
4800void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
4801  // Only check instance methods whose selector looks like a setter.
4802  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
4803    return;
4804
4805  // Try to find a variable that the receiver is strongly owned by.
4806  RetainCycleOwner owner;
4807  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
4808    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
4809      return;
4810  } else {
4811    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
4812    owner.Variable = getCurMethodDecl()->getSelfDecl();
4813    owner.Loc = msg->getSuperLoc();
4814    owner.Range = msg->getSuperLoc();
4815  }
4816
4817  // Check whether the receiver is captured by any of the arguments.
4818  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
4819    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
4820      return diagnoseRetainCycle(*this, capturer, owner);
4821}
4822
4823/// Check a property assign to see if it's likely to cause a retain cycle.
4824void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
4825  RetainCycleOwner owner;
4826  if (!findRetainCycleOwner(*this, receiver, owner))
4827    return;
4828
4829  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
4830    diagnoseRetainCycle(*this, capturer, owner);
4831}
4832
4833bool Sema::checkUnsafeAssigns(SourceLocation Loc,
4834                              QualType LHS, Expr *RHS) {
4835  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
4836  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
4837    return false;
4838  // strip off any implicit cast added to get to the one arc-specific
4839  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4840    if (cast->getCastKind() == CK_ARCConsumeObject) {
4841      Diag(Loc, diag::warn_arc_retained_assign)
4842        << (LT == Qualifiers::OCL_ExplicitNone)
4843        << RHS->getSourceRange();
4844      return true;
4845    }
4846    RHS = cast->getSubExpr();
4847  }
4848  return false;
4849}
4850
4851void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
4852                              Expr *LHS, Expr *RHS) {
4853  QualType LHSType;
4854  // PropertyRef on LHS type need be directly obtained from
4855  // its declaration as it has a PsuedoType.
4856  ObjCPropertyRefExpr *PRE
4857    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
4858  if (PRE && !PRE->isImplicitProperty()) {
4859    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
4860    if (PD)
4861      LHSType = PD->getType();
4862  }
4863
4864  if (LHSType.isNull())
4865    LHSType = LHS->getType();
4866  if (checkUnsafeAssigns(Loc, LHSType, RHS))
4867    return;
4868  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
4869  // FIXME. Check for other life times.
4870  if (LT != Qualifiers::OCL_None)
4871    return;
4872
4873  if (PRE) {
4874    if (PRE->isImplicitProperty())
4875      return;
4876    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
4877    if (!PD)
4878      return;
4879
4880    unsigned Attributes = PD->getPropertyAttributes();
4881    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
4882      // when 'assign' attribute was not explicitly specified
4883      // by user, ignore it and rely on property type itself
4884      // for lifetime info.
4885      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
4886      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
4887          LHSType->isObjCRetainableType())
4888        return;
4889
4890      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4891        if (cast->getCastKind() == CK_ARCConsumeObject) {
4892          Diag(Loc, diag::warn_arc_retained_property_assign)
4893          << RHS->getSourceRange();
4894          return;
4895        }
4896        RHS = cast->getSubExpr();
4897      }
4898    }
4899  }
4900}
4901
4902//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
4903
4904namespace {
4905bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
4906                                 SourceLocation StmtLoc,
4907                                 const NullStmt *Body) {
4908  // Do not warn if the body is a macro that expands to nothing, e.g:
4909  //
4910  // #define CALL(x)
4911  // if (condition)
4912  //   CALL(0);
4913  //
4914  if (Body->hasLeadingEmptyMacro())
4915    return false;
4916
4917  // Get line numbers of statement and body.
4918  bool StmtLineInvalid;
4919  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
4920                                                      &StmtLineInvalid);
4921  if (StmtLineInvalid)
4922    return false;
4923
4924  bool BodyLineInvalid;
4925  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
4926                                                      &BodyLineInvalid);
4927  if (BodyLineInvalid)
4928    return false;
4929
4930  // Warn if null statement and body are on the same line.
4931  if (StmtLine != BodyLine)
4932    return false;
4933
4934  return true;
4935}
4936} // Unnamed namespace
4937
4938void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
4939                                 const Stmt *Body,
4940                                 unsigned DiagID) {
4941  // Since this is a syntactic check, don't emit diagnostic for template
4942  // instantiations, this just adds noise.
4943  if (CurrentInstantiationScope)
4944    return;
4945
4946  // The body should be a null statement.
4947  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
4948  if (!NBody)
4949    return;
4950
4951  // Do the usual checks.
4952  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
4953    return;
4954
4955  Diag(NBody->getSemiLoc(), DiagID);
4956  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
4957}
4958
4959void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
4960                                 const Stmt *PossibleBody) {
4961  assert(!CurrentInstantiationScope); // Ensured by caller
4962
4963  SourceLocation StmtLoc;
4964  const Stmt *Body;
4965  unsigned DiagID;
4966  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
4967    StmtLoc = FS->getRParenLoc();
4968    Body = FS->getBody();
4969    DiagID = diag::warn_empty_for_body;
4970  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
4971    StmtLoc = WS->getCond()->getSourceRange().getEnd();
4972    Body = WS->getBody();
4973    DiagID = diag::warn_empty_while_body;
4974  } else
4975    return; // Neither `for' nor `while'.
4976
4977  // The body should be a null statement.
4978  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
4979  if (!NBody)
4980    return;
4981
4982  // Skip expensive checks if diagnostic is disabled.
4983  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
4984          DiagnosticsEngine::Ignored)
4985    return;
4986
4987  // Do the usual checks.
4988  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
4989    return;
4990
4991  // `for(...);' and `while(...);' are popular idioms, so in order to keep
4992  // noise level low, emit diagnostics only if for/while is followed by a
4993  // CompoundStmt, e.g.:
4994  //    for (int i = 0; i < n; i++);
4995  //    {
4996  //      a(i);
4997  //    }
4998  // or if for/while is followed by a statement with more indentation
4999  // than for/while itself:
5000  //    for (int i = 0; i < n; i++);
5001  //      a(i);
5002  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
5003  if (!ProbableTypo) {
5004    bool BodyColInvalid;
5005    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
5006                             PossibleBody->getLocStart(),
5007                             &BodyColInvalid);
5008    if (BodyColInvalid)
5009      return;
5010
5011    bool StmtColInvalid;
5012    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
5013                             S->getLocStart(),
5014                             &StmtColInvalid);
5015    if (StmtColInvalid)
5016      return;
5017
5018    if (BodyCol > StmtCol)
5019      ProbableTypo = true;
5020  }
5021
5022  if (ProbableTypo) {
5023    Diag(NBody->getSemiLoc(), DiagID);
5024    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5025  }
5026}
5027