SemaChecking.cpp revision 687b5df89d4ba91219df578d02087c68c09a0332 
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/STLExtras.h"
34#include "llvm/Support/raw_ostream.h"
35#include "clang/Basic/TargetBuiltins.h"
36#include "clang/Basic/TargetInfo.h"
37#include "clang/Basic/ConvertUTF.h"
38#include <limits>
39using namespace clang;
40using namespace sema;
41
42SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
43                                                    unsigned ByteNo) const {
44  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
45                               PP.getLangOptions(), PP.getTargetInfo());
46}
47
48
49/// CheckablePrintfAttr - does a function call have a "printf" attribute
50/// and arguments that merit checking?
51bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) {
52  if (Format->getType() == "printf") return true;
53  if (Format->getType() == "printf0") {
54    // printf0 allows null "format" string; if so don't check format/args
55    unsigned format_idx = Format->getFormatIdx() - 1;
56    // Does the index refer to the implicit object argument?
57    if (isa<CXXMemberCallExpr>(TheCall)) {
58      if (format_idx == 0)
59        return false;
60      --format_idx;
61    }
62    if (format_idx < TheCall->getNumArgs()) {
63      Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts();
64      if (!Format->isNullPointerConstant(Context,
65                                         Expr::NPC_ValueDependentIsNull))
66        return true;
67    }
68  }
69  return false;
70}
71
72/// Checks that a call expression's argument count is the desired number.
73/// This is useful when doing custom type-checking.  Returns true on error.
74static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
75  unsigned argCount = call->getNumArgs();
76  if (argCount == desiredArgCount) return false;
77
78  if (argCount < desiredArgCount)
79    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
80        << 0 /*function call*/ << desiredArgCount << argCount
81        << call->getSourceRange();
82
83  // Highlight all the excess arguments.
84  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
85                    call->getArg(argCount - 1)->getLocEnd());
86
87  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
88    << 0 /*function call*/ << desiredArgCount << argCount
89    << call->getArg(1)->getSourceRange();
90}
91
92/// CheckBuiltinAnnotationString - Checks that string argument to the builtin
93/// annotation is a non wide string literal.
94static bool CheckBuiltinAnnotationString(Sema &S, Expr *Arg) {
95  Arg = Arg->IgnoreParenCasts();
96  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
97  if (!Literal || !Literal->isAscii()) {
98    S.Diag(Arg->getLocStart(), diag::err_builtin_annotation_not_string_constant)
99      << Arg->getSourceRange();
100    return true;
101  }
102  return false;
103}
104
105ExprResult
106Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
107  ExprResult TheCallResult(Owned(TheCall));
108
109  // Find out if any arguments are required to be integer constant expressions.
110  unsigned ICEArguments = 0;
111  ASTContext::GetBuiltinTypeError Error;
112  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
113  if (Error != ASTContext::GE_None)
114    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
115
116  // If any arguments are required to be ICE's, check and diagnose.
117  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
118    // Skip arguments not required to be ICE's.
119    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
120
121    llvm::APSInt Result;
122    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
123      return true;
124    ICEArguments &= ~(1 << ArgNo);
125  }
126
127  switch (BuiltinID) {
128  case Builtin::BI__builtin___CFStringMakeConstantString:
129    assert(TheCall->getNumArgs() == 1 &&
130           "Wrong # arguments to builtin CFStringMakeConstantString");
131    if (CheckObjCString(TheCall->getArg(0)))
132      return ExprError();
133    break;
134  case Builtin::BI__builtin_stdarg_start:
135  case Builtin::BI__builtin_va_start:
136    if (SemaBuiltinVAStart(TheCall))
137      return ExprError();
138    break;
139  case Builtin::BI__builtin_isgreater:
140  case Builtin::BI__builtin_isgreaterequal:
141  case Builtin::BI__builtin_isless:
142  case Builtin::BI__builtin_islessequal:
143  case Builtin::BI__builtin_islessgreater:
144  case Builtin::BI__builtin_isunordered:
145    if (SemaBuiltinUnorderedCompare(TheCall))
146      return ExprError();
147    break;
148  case Builtin::BI__builtin_fpclassify:
149    if (SemaBuiltinFPClassification(TheCall, 6))
150      return ExprError();
151    break;
152  case Builtin::BI__builtin_isfinite:
153  case Builtin::BI__builtin_isinf:
154  case Builtin::BI__builtin_isinf_sign:
155  case Builtin::BI__builtin_isnan:
156  case Builtin::BI__builtin_isnormal:
157    if (SemaBuiltinFPClassification(TheCall, 1))
158      return ExprError();
159    break;
160  case Builtin::BI__builtin_shufflevector:
161    return SemaBuiltinShuffleVector(TheCall);
162    // TheCall will be freed by the smart pointer here, but that's fine, since
163    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
164  case Builtin::BI__builtin_prefetch:
165    if (SemaBuiltinPrefetch(TheCall))
166      return ExprError();
167    break;
168  case Builtin::BI__builtin_object_size:
169    if (SemaBuiltinObjectSize(TheCall))
170      return ExprError();
171    break;
172  case Builtin::BI__builtin_longjmp:
173    if (SemaBuiltinLongjmp(TheCall))
174      return ExprError();
175    break;
176
177  case Builtin::BI__builtin_classify_type:
178    if (checkArgCount(*this, TheCall, 1)) return true;
179    TheCall->setType(Context.IntTy);
180    break;
181  case Builtin::BI__builtin_constant_p:
182    if (checkArgCount(*this, TheCall, 1)) return true;
183    TheCall->setType(Context.IntTy);
184    break;
185  case Builtin::BI__sync_fetch_and_add:
186  case Builtin::BI__sync_fetch_and_add_1:
187  case Builtin::BI__sync_fetch_and_add_2:
188  case Builtin::BI__sync_fetch_and_add_4:
189  case Builtin::BI__sync_fetch_and_add_8:
190  case Builtin::BI__sync_fetch_and_add_16:
191  case Builtin::BI__sync_fetch_and_sub:
192  case Builtin::BI__sync_fetch_and_sub_1:
193  case Builtin::BI__sync_fetch_and_sub_2:
194  case Builtin::BI__sync_fetch_and_sub_4:
195  case Builtin::BI__sync_fetch_and_sub_8:
196  case Builtin::BI__sync_fetch_and_sub_16:
197  case Builtin::BI__sync_fetch_and_or:
198  case Builtin::BI__sync_fetch_and_or_1:
199  case Builtin::BI__sync_fetch_and_or_2:
200  case Builtin::BI__sync_fetch_and_or_4:
201  case Builtin::BI__sync_fetch_and_or_8:
202  case Builtin::BI__sync_fetch_and_or_16:
203  case Builtin::BI__sync_fetch_and_and:
204  case Builtin::BI__sync_fetch_and_and_1:
205  case Builtin::BI__sync_fetch_and_and_2:
206  case Builtin::BI__sync_fetch_and_and_4:
207  case Builtin::BI__sync_fetch_and_and_8:
208  case Builtin::BI__sync_fetch_and_and_16:
209  case Builtin::BI__sync_fetch_and_xor:
210  case Builtin::BI__sync_fetch_and_xor_1:
211  case Builtin::BI__sync_fetch_and_xor_2:
212  case Builtin::BI__sync_fetch_and_xor_4:
213  case Builtin::BI__sync_fetch_and_xor_8:
214  case Builtin::BI__sync_fetch_and_xor_16:
215  case Builtin::BI__sync_add_and_fetch:
216  case Builtin::BI__sync_add_and_fetch_1:
217  case Builtin::BI__sync_add_and_fetch_2:
218  case Builtin::BI__sync_add_and_fetch_4:
219  case Builtin::BI__sync_add_and_fetch_8:
220  case Builtin::BI__sync_add_and_fetch_16:
221  case Builtin::BI__sync_sub_and_fetch:
222  case Builtin::BI__sync_sub_and_fetch_1:
223  case Builtin::BI__sync_sub_and_fetch_2:
224  case Builtin::BI__sync_sub_and_fetch_4:
225  case Builtin::BI__sync_sub_and_fetch_8:
226  case Builtin::BI__sync_sub_and_fetch_16:
227  case Builtin::BI__sync_and_and_fetch:
228  case Builtin::BI__sync_and_and_fetch_1:
229  case Builtin::BI__sync_and_and_fetch_2:
230  case Builtin::BI__sync_and_and_fetch_4:
231  case Builtin::BI__sync_and_and_fetch_8:
232  case Builtin::BI__sync_and_and_fetch_16:
233  case Builtin::BI__sync_or_and_fetch:
234  case Builtin::BI__sync_or_and_fetch_1:
235  case Builtin::BI__sync_or_and_fetch_2:
236  case Builtin::BI__sync_or_and_fetch_4:
237  case Builtin::BI__sync_or_and_fetch_8:
238  case Builtin::BI__sync_or_and_fetch_16:
239  case Builtin::BI__sync_xor_and_fetch:
240  case Builtin::BI__sync_xor_and_fetch_1:
241  case Builtin::BI__sync_xor_and_fetch_2:
242  case Builtin::BI__sync_xor_and_fetch_4:
243  case Builtin::BI__sync_xor_and_fetch_8:
244  case Builtin::BI__sync_xor_and_fetch_16:
245  case Builtin::BI__sync_val_compare_and_swap:
246  case Builtin::BI__sync_val_compare_and_swap_1:
247  case Builtin::BI__sync_val_compare_and_swap_2:
248  case Builtin::BI__sync_val_compare_and_swap_4:
249  case Builtin::BI__sync_val_compare_and_swap_8:
250  case Builtin::BI__sync_val_compare_and_swap_16:
251  case Builtin::BI__sync_bool_compare_and_swap:
252  case Builtin::BI__sync_bool_compare_and_swap_1:
253  case Builtin::BI__sync_bool_compare_and_swap_2:
254  case Builtin::BI__sync_bool_compare_and_swap_4:
255  case Builtin::BI__sync_bool_compare_and_swap_8:
256  case Builtin::BI__sync_bool_compare_and_swap_16:
257  case Builtin::BI__sync_lock_test_and_set:
258  case Builtin::BI__sync_lock_test_and_set_1:
259  case Builtin::BI__sync_lock_test_and_set_2:
260  case Builtin::BI__sync_lock_test_and_set_4:
261  case Builtin::BI__sync_lock_test_and_set_8:
262  case Builtin::BI__sync_lock_test_and_set_16:
263  case Builtin::BI__sync_lock_release:
264  case Builtin::BI__sync_lock_release_1:
265  case Builtin::BI__sync_lock_release_2:
266  case Builtin::BI__sync_lock_release_4:
267  case Builtin::BI__sync_lock_release_8:
268  case Builtin::BI__sync_lock_release_16:
269  case Builtin::BI__sync_swap:
270  case Builtin::BI__sync_swap_1:
271  case Builtin::BI__sync_swap_2:
272  case Builtin::BI__sync_swap_4:
273  case Builtin::BI__sync_swap_8:
274  case Builtin::BI__sync_swap_16:
275    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
276  case Builtin::BI__atomic_load:
277    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Load);
278  case Builtin::BI__atomic_store:
279    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Store);
280  case Builtin::BI__atomic_exchange:
281    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xchg);
282  case Builtin::BI__atomic_compare_exchange_strong:
283    return SemaAtomicOpsOverloaded(move(TheCallResult),
284                                   AtomicExpr::CmpXchgStrong);
285  case Builtin::BI__atomic_compare_exchange_weak:
286    return SemaAtomicOpsOverloaded(move(TheCallResult),
287                                   AtomicExpr::CmpXchgWeak);
288  case Builtin::BI__atomic_fetch_add:
289    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Add);
290  case Builtin::BI__atomic_fetch_sub:
291    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Sub);
292  case Builtin::BI__atomic_fetch_and:
293    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::And);
294  case Builtin::BI__atomic_fetch_or:
295    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Or);
296  case Builtin::BI__atomic_fetch_xor:
297    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xor);
298  case Builtin::BI__builtin_annotation:
299    if (CheckBuiltinAnnotationString(*this, TheCall->getArg(1)))
300      return ExprError();
301    break;
302  }
303
304  // Since the target specific builtins for each arch overlap, only check those
305  // of the arch we are compiling for.
306  if (BuiltinID >= Builtin::FirstTSBuiltin) {
307    switch (Context.getTargetInfo().getTriple().getArch()) {
308      case llvm::Triple::arm:
309      case llvm::Triple::thumb:
310        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
311          return ExprError();
312        break;
313      default:
314        break;
315    }
316  }
317
318  return move(TheCallResult);
319}
320
321// Get the valid immediate range for the specified NEON type code.
322static unsigned RFT(unsigned t, bool shift = false) {
323  NeonTypeFlags Type(t);
324  int IsQuad = Type.isQuad();
325  switch (Type.getEltType()) {
326  case NeonTypeFlags::Int8:
327  case NeonTypeFlags::Poly8:
328    return shift ? 7 : (8 << IsQuad) - 1;
329  case NeonTypeFlags::Int16:
330  case NeonTypeFlags::Poly16:
331    return shift ? 15 : (4 << IsQuad) - 1;
332  case NeonTypeFlags::Int32:
333    return shift ? 31 : (2 << IsQuad) - 1;
334  case NeonTypeFlags::Int64:
335    return shift ? 63 : (1 << IsQuad) - 1;
336  case NeonTypeFlags::Float16:
337    assert(!shift && "cannot shift float types!");
338    return (4 << IsQuad) - 1;
339  case NeonTypeFlags::Float32:
340    assert(!shift && "cannot shift float types!");
341    return (2 << IsQuad) - 1;
342  }
343  return 0;
344}
345
346/// getNeonEltType - Return the QualType corresponding to the elements of
347/// the vector type specified by the NeonTypeFlags.  This is used to check
348/// the pointer arguments for Neon load/store intrinsics.
349static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
350  switch (Flags.getEltType()) {
351  case NeonTypeFlags::Int8:
352    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
353  case NeonTypeFlags::Int16:
354    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
355  case NeonTypeFlags::Int32:
356    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
357  case NeonTypeFlags::Int64:
358    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
359  case NeonTypeFlags::Poly8:
360    return Context.SignedCharTy;
361  case NeonTypeFlags::Poly16:
362    return Context.ShortTy;
363  case NeonTypeFlags::Float16:
364    return Context.UnsignedShortTy;
365  case NeonTypeFlags::Float32:
366    return Context.FloatTy;
367  }
368  return QualType();
369}
370
371bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
372  llvm::APSInt Result;
373
374  unsigned mask = 0;
375  unsigned TV = 0;
376  int PtrArgNum = -1;
377  bool HasConstPtr = false;
378  switch (BuiltinID) {
379#define GET_NEON_OVERLOAD_CHECK
380#include "clang/Basic/arm_neon.inc"
381#undef GET_NEON_OVERLOAD_CHECK
382  }
383
384  // For NEON intrinsics which are overloaded on vector element type, validate
385  // the immediate which specifies which variant to emit.
386  unsigned ImmArg = TheCall->getNumArgs()-1;
387  if (mask) {
388    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
389      return true;
390
391    TV = Result.getLimitedValue(64);
392    if ((TV > 63) || (mask & (1 << TV)) == 0)
393      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
394        << TheCall->getArg(ImmArg)->getSourceRange();
395  }
396
397  if (PtrArgNum >= 0) {
398    // Check that pointer arguments have the specified type.
399    Expr *Arg = TheCall->getArg(PtrArgNum);
400    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
401      Arg = ICE->getSubExpr();
402    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
403    QualType RHSTy = RHS.get()->getType();
404    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
405    if (HasConstPtr)
406      EltTy = EltTy.withConst();
407    QualType LHSTy = Context.getPointerType(EltTy);
408    AssignConvertType ConvTy;
409    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
410    if (RHS.isInvalid())
411      return true;
412    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
413                                 RHS.get(), AA_Assigning))
414      return true;
415  }
416
417  // For NEON intrinsics which take an immediate value as part of the
418  // instruction, range check them here.
419  unsigned i = 0, l = 0, u = 0;
420  switch (BuiltinID) {
421  default: return false;
422  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
423  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
424  case ARM::BI__builtin_arm_vcvtr_f:
425  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
426#define GET_NEON_IMMEDIATE_CHECK
427#include "clang/Basic/arm_neon.inc"
428#undef GET_NEON_IMMEDIATE_CHECK
429  };
430
431  // Check that the immediate argument is actually a constant.
432  if (SemaBuiltinConstantArg(TheCall, i, Result))
433    return true;
434
435  // Range check against the upper/lower values for this isntruction.
436  unsigned Val = Result.getZExtValue();
437  if (Val < l || Val > (u + l))
438    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
439      << l << u+l << TheCall->getArg(i)->getSourceRange();
440
441  // FIXME: VFP Intrinsics should error if VFP not present.
442  return false;
443}
444
445/// CheckFunctionCall - Check a direct function call for various correctness
446/// and safety properties not strictly enforced by the C type system.
447bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
448  // Get the IdentifierInfo* for the called function.
449  IdentifierInfo *FnInfo = FDecl->getIdentifier();
450
451  // None of the checks below are needed for functions that don't have
452  // simple names (e.g., C++ conversion functions).
453  if (!FnInfo)
454    return false;
455
456  // FIXME: This mechanism should be abstracted to be less fragile and
457  // more efficient. For example, just map function ids to custom
458  // handlers.
459
460  // Printf and scanf checking.
461  for (specific_attr_iterator<FormatAttr>
462         i = FDecl->specific_attr_begin<FormatAttr>(),
463         e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
464
465    const FormatAttr *Format = *i;
466    const bool b = Format->getType() == "scanf";
467    if (b || CheckablePrintfAttr(Format, TheCall)) {
468      bool HasVAListArg = Format->getFirstArg() == 0;
469      CheckPrintfScanfArguments(TheCall, HasVAListArg,
470                                Format->getFormatIdx() - 1,
471                                HasVAListArg ? 0 : Format->getFirstArg() - 1,
472                                !b);
473    }
474  }
475
476  for (specific_attr_iterator<NonNullAttr>
477         i = FDecl->specific_attr_begin<NonNullAttr>(),
478         e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) {
479    CheckNonNullArguments(*i, TheCall->getArgs(),
480                          TheCall->getCallee()->getLocStart());
481  }
482
483  // Builtin handling
484  int CMF = -1;
485  switch (FDecl->getBuiltinID()) {
486  case Builtin::BI__builtin_memset:
487  case Builtin::BI__builtin___memset_chk:
488  case Builtin::BImemset:
489    CMF = CMF_Memset;
490    break;
491
492  case Builtin::BI__builtin_memcpy:
493  case Builtin::BI__builtin___memcpy_chk:
494  case Builtin::BImemcpy:
495    CMF = CMF_Memcpy;
496    break;
497
498  case Builtin::BI__builtin_memmove:
499  case Builtin::BI__builtin___memmove_chk:
500  case Builtin::BImemmove:
501    CMF = CMF_Memmove;
502    break;
503
504  case Builtin::BIstrlcpy:
505  case Builtin::BIstrlcat:
506    CheckStrlcpycatArguments(TheCall, FnInfo);
507    break;
508
509  case Builtin::BI__builtin_memcmp:
510    CMF = CMF_Memcmp;
511    break;
512
513  case Builtin::BI__builtin_strncpy:
514  case Builtin::BI__builtin___strncpy_chk:
515  case Builtin::BIstrncpy:
516    CMF = CMF_Strncpy;
517    break;
518
519  case Builtin::BI__builtin_strncmp:
520    CMF = CMF_Strncmp;
521    break;
522
523  case Builtin::BI__builtin_strncasecmp:
524    CMF = CMF_Strncasecmp;
525    break;
526
527  case Builtin::BI__builtin_strncat:
528  case Builtin::BIstrncat:
529    CMF = CMF_Strncat;
530    break;
531
532  case Builtin::BI__builtin_strndup:
533  case Builtin::BIstrndup:
534    CMF = CMF_Strndup;
535    break;
536
537  default:
538    if (FDecl->getLinkage() == ExternalLinkage &&
539        (!getLangOptions().CPlusPlus || FDecl->isExternC())) {
540      if (FnInfo->isStr("memset"))
541        CMF = CMF_Memset;
542      else if (FnInfo->isStr("memcpy"))
543        CMF = CMF_Memcpy;
544      else if (FnInfo->isStr("memmove"))
545        CMF = CMF_Memmove;
546      else if (FnInfo->isStr("memcmp"))
547        CMF = CMF_Memcmp;
548      else if (FnInfo->isStr("strncpy"))
549        CMF = CMF_Strncpy;
550      else if (FnInfo->isStr("strncmp"))
551        CMF = CMF_Strncmp;
552      else if (FnInfo->isStr("strncasecmp"))
553        CMF = CMF_Strncasecmp;
554      else if (FnInfo->isStr("strncat"))
555        CMF = CMF_Strncat;
556      else if (FnInfo->isStr("strndup"))
557        CMF = CMF_Strndup;
558    }
559    break;
560  }
561
562  // Memset/memcpy/memmove handling
563  if (CMF != -1)
564    CheckMemaccessArguments(TheCall, CheckedMemoryFunction(CMF), FnInfo);
565
566  return false;
567}
568
569bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
570  // Printf checking.
571  const FormatAttr *Format = NDecl->getAttr<FormatAttr>();
572  if (!Format)
573    return false;
574
575  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
576  if (!V)
577    return false;
578
579  QualType Ty = V->getType();
580  if (!Ty->isBlockPointerType())
581    return false;
582
583  const bool b = Format->getType() == "scanf";
584  if (!b && !CheckablePrintfAttr(Format, TheCall))
585    return false;
586
587  bool HasVAListArg = Format->getFirstArg() == 0;
588  CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
589                            HasVAListArg ? 0 : Format->getFirstArg() - 1, !b);
590
591  return false;
592}
593
594ExprResult
595Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, AtomicExpr::AtomicOp Op) {
596  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
597  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
598
599  // All these operations take one of the following four forms:
600  // T   __atomic_load(_Atomic(T)*, int)                              (loads)
601  // T*  __atomic_add(_Atomic(T*)*, ptrdiff_t, int)         (pointer add/sub)
602  // int __atomic_compare_exchange_strong(_Atomic(T)*, T*, T, int, int)
603  //                                                                (cmpxchg)
604  // T   __atomic_exchange(_Atomic(T)*, T, int)             (everything else)
605  // where T is an appropriate type, and the int paremeterss are for orderings.
606  unsigned NumVals = 1;
607  unsigned NumOrders = 1;
608  if (Op == AtomicExpr::Load) {
609    NumVals = 0;
610  } else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong) {
611    NumVals = 2;
612    NumOrders = 2;
613  }
614
615  if (TheCall->getNumArgs() < NumVals+NumOrders+1) {
616    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
617      << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs()
618      << TheCall->getCallee()->getSourceRange();
619    return ExprError();
620  } else if (TheCall->getNumArgs() > NumVals+NumOrders+1) {
621    Diag(TheCall->getArg(NumVals+NumOrders+1)->getLocStart(),
622         diag::err_typecheck_call_too_many_args)
623      << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs()
624      << TheCall->getCallee()->getSourceRange();
625    return ExprError();
626  }
627
628  // Inspect the first argument of the atomic operation.  This should always be
629  // a pointer to an _Atomic type.
630  Expr *Ptr = TheCall->getArg(0);
631  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
632  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
633  if (!pointerType) {
634    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
635      << Ptr->getType() << Ptr->getSourceRange();
636    return ExprError();
637  }
638
639  QualType AtomTy = pointerType->getPointeeType();
640  if (!AtomTy->isAtomicType()) {
641    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
642      << Ptr->getType() << Ptr->getSourceRange();
643    return ExprError();
644  }
645  QualType ValType = AtomTy->getAs<AtomicType>()->getValueType();
646
647  if ((Op == AtomicExpr::Add || Op == AtomicExpr::Sub) &&
648      !ValType->isIntegerType() && !ValType->isPointerType()) {
649    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
650      << Ptr->getType() << Ptr->getSourceRange();
651    return ExprError();
652  }
653
654  if (!ValType->isIntegerType() &&
655      (Op == AtomicExpr::And || Op == AtomicExpr::Or || Op == AtomicExpr::Xor)){
656    Diag(DRE->getLocStart(), diag::err_atomic_op_logical_needs_atomic_int)
657      << Ptr->getType() << Ptr->getSourceRange();
658    return ExprError();
659  }
660
661  switch (ValType.getObjCLifetime()) {
662  case Qualifiers::OCL_None:
663  case Qualifiers::OCL_ExplicitNone:
664    // okay
665    break;
666
667  case Qualifiers::OCL_Weak:
668  case Qualifiers::OCL_Strong:
669  case Qualifiers::OCL_Autoreleasing:
670    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
671      << ValType << Ptr->getSourceRange();
672    return ExprError();
673  }
674
675  QualType ResultType = ValType;
676  if (Op == AtomicExpr::Store)
677    ResultType = Context.VoidTy;
678  else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong)
679    ResultType = Context.BoolTy;
680
681  // The first argument --- the pointer --- has a fixed type; we
682  // deduce the types of the rest of the arguments accordingly.  Walk
683  // the remaining arguments, converting them to the deduced value type.
684  for (unsigned i = 1; i != NumVals+NumOrders+1; ++i) {
685    ExprResult Arg = TheCall->getArg(i);
686    QualType Ty;
687    if (i < NumVals+1) {
688      // The second argument to a cmpxchg is a pointer to the data which will
689      // be exchanged. The second argument to a pointer add/subtract is the
690      // amount to add/subtract, which must be a ptrdiff_t.  The third
691      // argument to a cmpxchg and the second argument in all other cases
692      // is the type of the value.
693      if (i == 1 && (Op == AtomicExpr::CmpXchgWeak ||
694                     Op == AtomicExpr::CmpXchgStrong))
695         Ty = Context.getPointerType(ValType.getUnqualifiedType());
696      else if (!ValType->isIntegerType() &&
697               (Op == AtomicExpr::Add || Op == AtomicExpr::Sub))
698        Ty = Context.getPointerDiffType();
699      else
700        Ty = ValType;
701    } else {
702      // The order(s) are always converted to int.
703      Ty = Context.IntTy;
704    }
705    InitializedEntity Entity =
706        InitializedEntity::InitializeParameter(Context, Ty, false);
707    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
708    if (Arg.isInvalid())
709      return true;
710    TheCall->setArg(i, Arg.get());
711  }
712
713  SmallVector<Expr*, 5> SubExprs;
714  SubExprs.push_back(Ptr);
715  if (Op == AtomicExpr::Load) {
716    SubExprs.push_back(TheCall->getArg(1)); // Order
717  } else if (Op != AtomicExpr::CmpXchgWeak && Op != AtomicExpr::CmpXchgStrong) {
718    SubExprs.push_back(TheCall->getArg(2)); // Order
719    SubExprs.push_back(TheCall->getArg(1)); // Val1
720  } else {
721    SubExprs.push_back(TheCall->getArg(3)); // Order
722    SubExprs.push_back(TheCall->getArg(1)); // Val1
723    SubExprs.push_back(TheCall->getArg(2)); // Val2
724    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
725  }
726
727  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
728                                        SubExprs.data(), SubExprs.size(),
729                                        ResultType, Op,
730                                        TheCall->getRParenLoc()));
731}
732
733
734/// checkBuiltinArgument - Given a call to a builtin function, perform
735/// normal type-checking on the given argument, updating the call in
736/// place.  This is useful when a builtin function requires custom
737/// type-checking for some of its arguments but not necessarily all of
738/// them.
739///
740/// Returns true on error.
741static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
742  FunctionDecl *Fn = E->getDirectCallee();
743  assert(Fn && "builtin call without direct callee!");
744
745  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
746  InitializedEntity Entity =
747    InitializedEntity::InitializeParameter(S.Context, Param);
748
749  ExprResult Arg = E->getArg(0);
750  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
751  if (Arg.isInvalid())
752    return true;
753
754  E->setArg(ArgIndex, Arg.take());
755  return false;
756}
757
758/// SemaBuiltinAtomicOverloaded - We have a call to a function like
759/// __sync_fetch_and_add, which is an overloaded function based on the pointer
760/// type of its first argument.  The main ActOnCallExpr routines have already
761/// promoted the types of arguments because all of these calls are prototyped as
762/// void(...).
763///
764/// This function goes through and does final semantic checking for these
765/// builtins,
766ExprResult
767Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
768  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
769  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
770  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
771
772  // Ensure that we have at least one argument to do type inference from.
773  if (TheCall->getNumArgs() < 1) {
774    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
775      << 0 << 1 << TheCall->getNumArgs()
776      << TheCall->getCallee()->getSourceRange();
777    return ExprError();
778  }
779
780  // Inspect the first argument of the atomic builtin.  This should always be
781  // a pointer type, whose element is an integral scalar or pointer type.
782  // Because it is a pointer type, we don't have to worry about any implicit
783  // casts here.
784  // FIXME: We don't allow floating point scalars as input.
785  Expr *FirstArg = TheCall->getArg(0);
786  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
787  if (!pointerType) {
788    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
789      << FirstArg->getType() << FirstArg->getSourceRange();
790    return ExprError();
791  }
792
793  QualType ValType = pointerType->getPointeeType();
794  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
795      !ValType->isBlockPointerType()) {
796    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
797      << FirstArg->getType() << FirstArg->getSourceRange();
798    return ExprError();
799  }
800
801  switch (ValType.getObjCLifetime()) {
802  case Qualifiers::OCL_None:
803  case Qualifiers::OCL_ExplicitNone:
804    // okay
805    break;
806
807  case Qualifiers::OCL_Weak:
808  case Qualifiers::OCL_Strong:
809  case Qualifiers::OCL_Autoreleasing:
810    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
811      << ValType << FirstArg->getSourceRange();
812    return ExprError();
813  }
814
815  // Strip any qualifiers off ValType.
816  ValType = ValType.getUnqualifiedType();
817
818  // The majority of builtins return a value, but a few have special return
819  // types, so allow them to override appropriately below.
820  QualType ResultType = ValType;
821
822  // We need to figure out which concrete builtin this maps onto.  For example,
823  // __sync_fetch_and_add with a 2 byte object turns into
824  // __sync_fetch_and_add_2.
825#define BUILTIN_ROW(x) \
826  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
827    Builtin::BI##x##_8, Builtin::BI##x##_16 }
828
829  static const unsigned BuiltinIndices[][5] = {
830    BUILTIN_ROW(__sync_fetch_and_add),
831    BUILTIN_ROW(__sync_fetch_and_sub),
832    BUILTIN_ROW(__sync_fetch_and_or),
833    BUILTIN_ROW(__sync_fetch_and_and),
834    BUILTIN_ROW(__sync_fetch_and_xor),
835
836    BUILTIN_ROW(__sync_add_and_fetch),
837    BUILTIN_ROW(__sync_sub_and_fetch),
838    BUILTIN_ROW(__sync_and_and_fetch),
839    BUILTIN_ROW(__sync_or_and_fetch),
840    BUILTIN_ROW(__sync_xor_and_fetch),
841
842    BUILTIN_ROW(__sync_val_compare_and_swap),
843    BUILTIN_ROW(__sync_bool_compare_and_swap),
844    BUILTIN_ROW(__sync_lock_test_and_set),
845    BUILTIN_ROW(__sync_lock_release),
846    BUILTIN_ROW(__sync_swap)
847  };
848#undef BUILTIN_ROW
849
850  // Determine the index of the size.
851  unsigned SizeIndex;
852  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
853  case 1: SizeIndex = 0; break;
854  case 2: SizeIndex = 1; break;
855  case 4: SizeIndex = 2; break;
856  case 8: SizeIndex = 3; break;
857  case 16: SizeIndex = 4; break;
858  default:
859    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
860      << FirstArg->getType() << FirstArg->getSourceRange();
861    return ExprError();
862  }
863
864  // Each of these builtins has one pointer argument, followed by some number of
865  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
866  // that we ignore.  Find out which row of BuiltinIndices to read from as well
867  // as the number of fixed args.
868  unsigned BuiltinID = FDecl->getBuiltinID();
869  unsigned BuiltinIndex, NumFixed = 1;
870  switch (BuiltinID) {
871  default: llvm_unreachable("Unknown overloaded atomic builtin!");
872  case Builtin::BI__sync_fetch_and_add:
873  case Builtin::BI__sync_fetch_and_add_1:
874  case Builtin::BI__sync_fetch_and_add_2:
875  case Builtin::BI__sync_fetch_and_add_4:
876  case Builtin::BI__sync_fetch_and_add_8:
877  case Builtin::BI__sync_fetch_and_add_16:
878    BuiltinIndex = 0;
879    break;
880
881  case Builtin::BI__sync_fetch_and_sub:
882  case Builtin::BI__sync_fetch_and_sub_1:
883  case Builtin::BI__sync_fetch_and_sub_2:
884  case Builtin::BI__sync_fetch_and_sub_4:
885  case Builtin::BI__sync_fetch_and_sub_8:
886  case Builtin::BI__sync_fetch_and_sub_16:
887    BuiltinIndex = 1;
888    break;
889
890  case Builtin::BI__sync_fetch_and_or:
891  case Builtin::BI__sync_fetch_and_or_1:
892  case Builtin::BI__sync_fetch_and_or_2:
893  case Builtin::BI__sync_fetch_and_or_4:
894  case Builtin::BI__sync_fetch_and_or_8:
895  case Builtin::BI__sync_fetch_and_or_16:
896    BuiltinIndex = 2;
897    break;
898
899  case Builtin::BI__sync_fetch_and_and:
900  case Builtin::BI__sync_fetch_and_and_1:
901  case Builtin::BI__sync_fetch_and_and_2:
902  case Builtin::BI__sync_fetch_and_and_4:
903  case Builtin::BI__sync_fetch_and_and_8:
904  case Builtin::BI__sync_fetch_and_and_16:
905    BuiltinIndex = 3;
906    break;
907
908  case Builtin::BI__sync_fetch_and_xor:
909  case Builtin::BI__sync_fetch_and_xor_1:
910  case Builtin::BI__sync_fetch_and_xor_2:
911  case Builtin::BI__sync_fetch_and_xor_4:
912  case Builtin::BI__sync_fetch_and_xor_8:
913  case Builtin::BI__sync_fetch_and_xor_16:
914    BuiltinIndex = 4;
915    break;
916
917  case Builtin::BI__sync_add_and_fetch:
918  case Builtin::BI__sync_add_and_fetch_1:
919  case Builtin::BI__sync_add_and_fetch_2:
920  case Builtin::BI__sync_add_and_fetch_4:
921  case Builtin::BI__sync_add_and_fetch_8:
922  case Builtin::BI__sync_add_and_fetch_16:
923    BuiltinIndex = 5;
924    break;
925
926  case Builtin::BI__sync_sub_and_fetch:
927  case Builtin::BI__sync_sub_and_fetch_1:
928  case Builtin::BI__sync_sub_and_fetch_2:
929  case Builtin::BI__sync_sub_and_fetch_4:
930  case Builtin::BI__sync_sub_and_fetch_8:
931  case Builtin::BI__sync_sub_and_fetch_16:
932    BuiltinIndex = 6;
933    break;
934
935  case Builtin::BI__sync_and_and_fetch:
936  case Builtin::BI__sync_and_and_fetch_1:
937  case Builtin::BI__sync_and_and_fetch_2:
938  case Builtin::BI__sync_and_and_fetch_4:
939  case Builtin::BI__sync_and_and_fetch_8:
940  case Builtin::BI__sync_and_and_fetch_16:
941    BuiltinIndex = 7;
942    break;
943
944  case Builtin::BI__sync_or_and_fetch:
945  case Builtin::BI__sync_or_and_fetch_1:
946  case Builtin::BI__sync_or_and_fetch_2:
947  case Builtin::BI__sync_or_and_fetch_4:
948  case Builtin::BI__sync_or_and_fetch_8:
949  case Builtin::BI__sync_or_and_fetch_16:
950    BuiltinIndex = 8;
951    break;
952
953  case Builtin::BI__sync_xor_and_fetch:
954  case Builtin::BI__sync_xor_and_fetch_1:
955  case Builtin::BI__sync_xor_and_fetch_2:
956  case Builtin::BI__sync_xor_and_fetch_4:
957  case Builtin::BI__sync_xor_and_fetch_8:
958  case Builtin::BI__sync_xor_and_fetch_16:
959    BuiltinIndex = 9;
960    break;
961
962  case Builtin::BI__sync_val_compare_and_swap:
963  case Builtin::BI__sync_val_compare_and_swap_1:
964  case Builtin::BI__sync_val_compare_and_swap_2:
965  case Builtin::BI__sync_val_compare_and_swap_4:
966  case Builtin::BI__sync_val_compare_and_swap_8:
967  case Builtin::BI__sync_val_compare_and_swap_16:
968    BuiltinIndex = 10;
969    NumFixed = 2;
970    break;
971
972  case Builtin::BI__sync_bool_compare_and_swap:
973  case Builtin::BI__sync_bool_compare_and_swap_1:
974  case Builtin::BI__sync_bool_compare_and_swap_2:
975  case Builtin::BI__sync_bool_compare_and_swap_4:
976  case Builtin::BI__sync_bool_compare_and_swap_8:
977  case Builtin::BI__sync_bool_compare_and_swap_16:
978    BuiltinIndex = 11;
979    NumFixed = 2;
980    ResultType = Context.BoolTy;
981    break;
982
983  case Builtin::BI__sync_lock_test_and_set:
984  case Builtin::BI__sync_lock_test_and_set_1:
985  case Builtin::BI__sync_lock_test_and_set_2:
986  case Builtin::BI__sync_lock_test_and_set_4:
987  case Builtin::BI__sync_lock_test_and_set_8:
988  case Builtin::BI__sync_lock_test_and_set_16:
989    BuiltinIndex = 12;
990    break;
991
992  case Builtin::BI__sync_lock_release:
993  case Builtin::BI__sync_lock_release_1:
994  case Builtin::BI__sync_lock_release_2:
995  case Builtin::BI__sync_lock_release_4:
996  case Builtin::BI__sync_lock_release_8:
997  case Builtin::BI__sync_lock_release_16:
998    BuiltinIndex = 13;
999    NumFixed = 0;
1000    ResultType = Context.VoidTy;
1001    break;
1002
1003  case Builtin::BI__sync_swap:
1004  case Builtin::BI__sync_swap_1:
1005  case Builtin::BI__sync_swap_2:
1006  case Builtin::BI__sync_swap_4:
1007  case Builtin::BI__sync_swap_8:
1008  case Builtin::BI__sync_swap_16:
1009    BuiltinIndex = 14;
1010    break;
1011  }
1012
1013  // Now that we know how many fixed arguments we expect, first check that we
1014  // have at least that many.
1015  if (TheCall->getNumArgs() < 1+NumFixed) {
1016    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1017      << 0 << 1+NumFixed << TheCall->getNumArgs()
1018      << TheCall->getCallee()->getSourceRange();
1019    return ExprError();
1020  }
1021
1022  // Get the decl for the concrete builtin from this, we can tell what the
1023  // concrete integer type we should convert to is.
1024  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1025  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1026  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
1027  FunctionDecl *NewBuiltinDecl =
1028    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
1029                                           TUScope, false, DRE->getLocStart()));
1030
1031  // The first argument --- the pointer --- has a fixed type; we
1032  // deduce the types of the rest of the arguments accordingly.  Walk
1033  // the remaining arguments, converting them to the deduced value type.
1034  for (unsigned i = 0; i != NumFixed; ++i) {
1035    ExprResult Arg = TheCall->getArg(i+1);
1036
1037    // GCC does an implicit conversion to the pointer or integer ValType.  This
1038    // can fail in some cases (1i -> int**), check for this error case now.
1039    // Initialize the argument.
1040    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1041                                                   ValType, /*consume*/ false);
1042    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1043    if (Arg.isInvalid())
1044      return ExprError();
1045
1046    // Okay, we have something that *can* be converted to the right type.  Check
1047    // to see if there is a potentially weird extension going on here.  This can
1048    // happen when you do an atomic operation on something like an char* and
1049    // pass in 42.  The 42 gets converted to char.  This is even more strange
1050    // for things like 45.123 -> char, etc.
1051    // FIXME: Do this check.
1052    TheCall->setArg(i+1, Arg.take());
1053  }
1054
1055  ASTContext& Context = this->getASTContext();
1056
1057  // Create a new DeclRefExpr to refer to the new decl.
1058  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1059      Context,
1060      DRE->getQualifierLoc(),
1061      NewBuiltinDecl,
1062      DRE->getLocation(),
1063      NewBuiltinDecl->getType(),
1064      DRE->getValueKind());
1065
1066  // Set the callee in the CallExpr.
1067  // FIXME: This leaks the original parens and implicit casts.
1068  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
1069  if (PromotedCall.isInvalid())
1070    return ExprError();
1071  TheCall->setCallee(PromotedCall.take());
1072
1073  // Change the result type of the call to match the original value type. This
1074  // is arbitrary, but the codegen for these builtins ins design to handle it
1075  // gracefully.
1076  TheCall->setType(ResultType);
1077
1078  return move(TheCallResult);
1079}
1080
1081/// CheckObjCString - Checks that the argument to the builtin
1082/// CFString constructor is correct
1083/// Note: It might also make sense to do the UTF-16 conversion here (would
1084/// simplify the backend).
1085bool Sema::CheckObjCString(Expr *Arg) {
1086  Arg = Arg->IgnoreParenCasts();
1087  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1088
1089  if (!Literal || !Literal->isAscii()) {
1090    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1091      << Arg->getSourceRange();
1092    return true;
1093  }
1094
1095  if (Literal->containsNonAsciiOrNull()) {
1096    StringRef String = Literal->getString();
1097    unsigned NumBytes = String.size();
1098    SmallVector<UTF16, 128> ToBuf(NumBytes);
1099    const UTF8 *FromPtr = (UTF8 *)String.data();
1100    UTF16 *ToPtr = &ToBuf[0];
1101
1102    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1103                                                 &ToPtr, ToPtr + NumBytes,
1104                                                 strictConversion);
1105    // Check for conversion failure.
1106    if (Result != conversionOK)
1107      Diag(Arg->getLocStart(),
1108           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1109  }
1110  return false;
1111}
1112
1113/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1114/// Emit an error and return true on failure, return false on success.
1115bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1116  Expr *Fn = TheCall->getCallee();
1117  if (TheCall->getNumArgs() > 2) {
1118    Diag(TheCall->getArg(2)->getLocStart(),
1119         diag::err_typecheck_call_too_many_args)
1120      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1121      << Fn->getSourceRange()
1122      << SourceRange(TheCall->getArg(2)->getLocStart(),
1123                     (*(TheCall->arg_end()-1))->getLocEnd());
1124    return true;
1125  }
1126
1127  if (TheCall->getNumArgs() < 2) {
1128    return Diag(TheCall->getLocEnd(),
1129      diag::err_typecheck_call_too_few_args_at_least)
1130      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1131  }
1132
1133  // Type-check the first argument normally.
1134  if (checkBuiltinArgument(*this, TheCall, 0))
1135    return true;
1136
1137  // Determine whether the current function is variadic or not.
1138  BlockScopeInfo *CurBlock = getCurBlock();
1139  bool isVariadic;
1140  if (CurBlock)
1141    isVariadic = CurBlock->TheDecl->isVariadic();
1142  else if (FunctionDecl *FD = getCurFunctionDecl())
1143    isVariadic = FD->isVariadic();
1144  else
1145    isVariadic = getCurMethodDecl()->isVariadic();
1146
1147  if (!isVariadic) {
1148    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1149    return true;
1150  }
1151
1152  // Verify that the second argument to the builtin is the last argument of the
1153  // current function or method.
1154  bool SecondArgIsLastNamedArgument = false;
1155  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1156
1157  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1158    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1159      // FIXME: This isn't correct for methods (results in bogus warning).
1160      // Get the last formal in the current function.
1161      const ParmVarDecl *LastArg;
1162      if (CurBlock)
1163        LastArg = *(CurBlock->TheDecl->param_end()-1);
1164      else if (FunctionDecl *FD = getCurFunctionDecl())
1165        LastArg = *(FD->param_end()-1);
1166      else
1167        LastArg = *(getCurMethodDecl()->param_end()-1);
1168      SecondArgIsLastNamedArgument = PV == LastArg;
1169    }
1170  }
1171
1172  if (!SecondArgIsLastNamedArgument)
1173    Diag(TheCall->getArg(1)->getLocStart(),
1174         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1175  return false;
1176}
1177
1178/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1179/// friends.  This is declared to take (...), so we have to check everything.
1180bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1181  if (TheCall->getNumArgs() < 2)
1182    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1183      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1184  if (TheCall->getNumArgs() > 2)
1185    return Diag(TheCall->getArg(2)->getLocStart(),
1186                diag::err_typecheck_call_too_many_args)
1187      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1188      << SourceRange(TheCall->getArg(2)->getLocStart(),
1189                     (*(TheCall->arg_end()-1))->getLocEnd());
1190
1191  ExprResult OrigArg0 = TheCall->getArg(0);
1192  ExprResult OrigArg1 = TheCall->getArg(1);
1193
1194  // Do standard promotions between the two arguments, returning their common
1195  // type.
1196  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1197  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1198    return true;
1199
1200  // Make sure any conversions are pushed back into the call; this is
1201  // type safe since unordered compare builtins are declared as "_Bool
1202  // foo(...)".
1203  TheCall->setArg(0, OrigArg0.get());
1204  TheCall->setArg(1, OrigArg1.get());
1205
1206  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1207    return false;
1208
1209  // If the common type isn't a real floating type, then the arguments were
1210  // invalid for this operation.
1211  if (!Res->isRealFloatingType())
1212    return Diag(OrigArg0.get()->getLocStart(),
1213                diag::err_typecheck_call_invalid_ordered_compare)
1214      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1215      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1216
1217  return false;
1218}
1219
1220/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1221/// __builtin_isnan and friends.  This is declared to take (...), so we have
1222/// to check everything. We expect the last argument to be a floating point
1223/// value.
1224bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1225  if (TheCall->getNumArgs() < NumArgs)
1226    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1227      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1228  if (TheCall->getNumArgs() > NumArgs)
1229    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1230                diag::err_typecheck_call_too_many_args)
1231      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1232      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1233                     (*(TheCall->arg_end()-1))->getLocEnd());
1234
1235  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1236
1237  if (OrigArg->isTypeDependent())
1238    return false;
1239
1240  // This operation requires a non-_Complex floating-point number.
1241  if (!OrigArg->getType()->isRealFloatingType())
1242    return Diag(OrigArg->getLocStart(),
1243                diag::err_typecheck_call_invalid_unary_fp)
1244      << OrigArg->getType() << OrigArg->getSourceRange();
1245
1246  // If this is an implicit conversion from float -> double, remove it.
1247  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1248    Expr *CastArg = Cast->getSubExpr();
1249    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1250      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1251             "promotion from float to double is the only expected cast here");
1252      Cast->setSubExpr(0);
1253      TheCall->setArg(NumArgs-1, CastArg);
1254      OrigArg = CastArg;
1255    }
1256  }
1257
1258  return false;
1259}
1260
1261/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1262// This is declared to take (...), so we have to check everything.
1263ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1264  if (TheCall->getNumArgs() < 2)
1265    return ExprError(Diag(TheCall->getLocEnd(),
1266                          diag::err_typecheck_call_too_few_args_at_least)
1267      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1268      << TheCall->getSourceRange());
1269
1270  // Determine which of the following types of shufflevector we're checking:
1271  // 1) unary, vector mask: (lhs, mask)
1272  // 2) binary, vector mask: (lhs, rhs, mask)
1273  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1274  QualType resType = TheCall->getArg(0)->getType();
1275  unsigned numElements = 0;
1276
1277  if (!TheCall->getArg(0)->isTypeDependent() &&
1278      !TheCall->getArg(1)->isTypeDependent()) {
1279    QualType LHSType = TheCall->getArg(0)->getType();
1280    QualType RHSType = TheCall->getArg(1)->getType();
1281
1282    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1283      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1284        << SourceRange(TheCall->getArg(0)->getLocStart(),
1285                       TheCall->getArg(1)->getLocEnd());
1286      return ExprError();
1287    }
1288
1289    numElements = LHSType->getAs<VectorType>()->getNumElements();
1290    unsigned numResElements = TheCall->getNumArgs() - 2;
1291
1292    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1293    // with mask.  If so, verify that RHS is an integer vector type with the
1294    // same number of elts as lhs.
1295    if (TheCall->getNumArgs() == 2) {
1296      if (!RHSType->hasIntegerRepresentation() ||
1297          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1298        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1299          << SourceRange(TheCall->getArg(1)->getLocStart(),
1300                         TheCall->getArg(1)->getLocEnd());
1301      numResElements = numElements;
1302    }
1303    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1304      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1305        << SourceRange(TheCall->getArg(0)->getLocStart(),
1306                       TheCall->getArg(1)->getLocEnd());
1307      return ExprError();
1308    } else if (numElements != numResElements) {
1309      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1310      resType = Context.getVectorType(eltType, numResElements,
1311                                      VectorType::GenericVector);
1312    }
1313  }
1314
1315  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1316    if (TheCall->getArg(i)->isTypeDependent() ||
1317        TheCall->getArg(i)->isValueDependent())
1318      continue;
1319
1320    llvm::APSInt Result(32);
1321    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1322      return ExprError(Diag(TheCall->getLocStart(),
1323                  diag::err_shufflevector_nonconstant_argument)
1324                << TheCall->getArg(i)->getSourceRange());
1325
1326    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1327      return ExprError(Diag(TheCall->getLocStart(),
1328                  diag::err_shufflevector_argument_too_large)
1329               << TheCall->getArg(i)->getSourceRange());
1330  }
1331
1332  SmallVector<Expr*, 32> exprs;
1333
1334  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1335    exprs.push_back(TheCall->getArg(i));
1336    TheCall->setArg(i, 0);
1337  }
1338
1339  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
1340                                            exprs.size(), resType,
1341                                            TheCall->getCallee()->getLocStart(),
1342                                            TheCall->getRParenLoc()));
1343}
1344
1345/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1346// This is declared to take (const void*, ...) and can take two
1347// optional constant int args.
1348bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1349  unsigned NumArgs = TheCall->getNumArgs();
1350
1351  if (NumArgs > 3)
1352    return Diag(TheCall->getLocEnd(),
1353             diag::err_typecheck_call_too_many_args_at_most)
1354             << 0 /*function call*/ << 3 << NumArgs
1355             << TheCall->getSourceRange();
1356
1357  // Argument 0 is checked for us and the remaining arguments must be
1358  // constant integers.
1359  for (unsigned i = 1; i != NumArgs; ++i) {
1360    Expr *Arg = TheCall->getArg(i);
1361
1362    llvm::APSInt Result;
1363    if (SemaBuiltinConstantArg(TheCall, i, Result))
1364      return true;
1365
1366    // FIXME: gcc issues a warning and rewrites these to 0. These
1367    // seems especially odd for the third argument since the default
1368    // is 3.
1369    if (i == 1) {
1370      if (Result.getLimitedValue() > 1)
1371        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1372             << "0" << "1" << Arg->getSourceRange();
1373    } else {
1374      if (Result.getLimitedValue() > 3)
1375        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1376            << "0" << "3" << Arg->getSourceRange();
1377    }
1378  }
1379
1380  return false;
1381}
1382
1383/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1384/// TheCall is a constant expression.
1385bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1386                                  llvm::APSInt &Result) {
1387  Expr *Arg = TheCall->getArg(ArgNum);
1388  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1389  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1390
1391  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1392
1393  if (!Arg->isIntegerConstantExpr(Result, Context))
1394    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1395                << FDecl->getDeclName() <<  Arg->getSourceRange();
1396
1397  return false;
1398}
1399
1400/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1401/// int type). This simply type checks that type is one of the defined
1402/// constants (0-3).
1403// For compatibility check 0-3, llvm only handles 0 and 2.
1404bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1405  llvm::APSInt Result;
1406
1407  // Check constant-ness first.
1408  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1409    return true;
1410
1411  Expr *Arg = TheCall->getArg(1);
1412  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1413    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1414             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1415  }
1416
1417  return false;
1418}
1419
1420/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1421/// This checks that val is a constant 1.
1422bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1423  Expr *Arg = TheCall->getArg(1);
1424  llvm::APSInt Result;
1425
1426  // TODO: This is less than ideal. Overload this to take a value.
1427  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1428    return true;
1429
1430  if (Result != 1)
1431    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1432             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1433
1434  return false;
1435}
1436
1437// Handle i > 1 ? "x" : "y", recursively.
1438bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall,
1439                                  bool HasVAListArg,
1440                                  unsigned format_idx, unsigned firstDataArg,
1441                                  bool isPrintf, bool inFunctionCall) {
1442 tryAgain:
1443  if (E->isTypeDependent() || E->isValueDependent())
1444    return false;
1445
1446  E = E->IgnoreParens();
1447
1448  switch (E->getStmtClass()) {
1449  case Stmt::BinaryConditionalOperatorClass:
1450  case Stmt::ConditionalOperatorClass: {
1451    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
1452    return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg,
1453                                  format_idx, firstDataArg, isPrintf,
1454                                  inFunctionCall)
1455        && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg,
1456                                  format_idx, firstDataArg, isPrintf,
1457                                  inFunctionCall);
1458  }
1459
1460  case Stmt::IntegerLiteralClass:
1461    // Technically -Wformat-nonliteral does not warn about this case.
1462    // The behavior of printf and friends in this case is implementation
1463    // dependent.  Ideally if the format string cannot be null then
1464    // it should have a 'nonnull' attribute in the function prototype.
1465    return true;
1466
1467  case Stmt::ImplicitCastExprClass: {
1468    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1469    goto tryAgain;
1470  }
1471
1472  case Stmt::OpaqueValueExprClass:
1473    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1474      E = src;
1475      goto tryAgain;
1476    }
1477    return false;
1478
1479  case Stmt::PredefinedExprClass:
1480    // While __func__, etc., are technically not string literals, they
1481    // cannot contain format specifiers and thus are not a security
1482    // liability.
1483    return true;
1484
1485  case Stmt::DeclRefExprClass: {
1486    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1487
1488    // As an exception, do not flag errors for variables binding to
1489    // const string literals.
1490    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1491      bool isConstant = false;
1492      QualType T = DR->getType();
1493
1494      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1495        isConstant = AT->getElementType().isConstant(Context);
1496      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1497        isConstant = T.isConstant(Context) &&
1498                     PT->getPointeeType().isConstant(Context);
1499      }
1500
1501      if (isConstant) {
1502        if (const Expr *Init = VD->getAnyInitializer())
1503          return SemaCheckStringLiteral(Init, TheCall,
1504                                        HasVAListArg, format_idx, firstDataArg,
1505                                        isPrintf, /*inFunctionCall*/false);
1506      }
1507
1508      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1509      // special check to see if the format string is a function parameter
1510      // of the function calling the printf function.  If the function
1511      // has an attribute indicating it is a printf-like function, then we
1512      // should suppress warnings concerning non-literals being used in a call
1513      // to a vprintf function.  For example:
1514      //
1515      // void
1516      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1517      //      va_list ap;
1518      //      va_start(ap, fmt);
1519      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1520      //      ...
1521      //
1522      //
1523      //  FIXME: We don't have full attribute support yet, so just check to see
1524      //    if the argument is a DeclRefExpr that references a parameter.  We'll
1525      //    add proper support for checking the attribute later.
1526      if (HasVAListArg)
1527        if (isa<ParmVarDecl>(VD))
1528          return true;
1529    }
1530
1531    return false;
1532  }
1533
1534  case Stmt::CallExprClass: {
1535    const CallExpr *CE = cast<CallExpr>(E);
1536    if (const ImplicitCastExpr *ICE
1537          = dyn_cast<ImplicitCastExpr>(CE->getCallee())) {
1538      if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) {
1539        if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
1540          if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) {
1541            unsigned ArgIndex = FA->getFormatIdx();
1542            const Expr *Arg = CE->getArg(ArgIndex - 1);
1543
1544            return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg,
1545                                          format_idx, firstDataArg, isPrintf,
1546                                          inFunctionCall);
1547          }
1548        }
1549      }
1550    }
1551
1552    return false;
1553  }
1554  case Stmt::ObjCStringLiteralClass:
1555  case Stmt::StringLiteralClass: {
1556    const StringLiteral *StrE = NULL;
1557
1558    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1559      StrE = ObjCFExpr->getString();
1560    else
1561      StrE = cast<StringLiteral>(E);
1562
1563    if (StrE) {
1564      CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx,
1565                        firstDataArg, isPrintf, inFunctionCall);
1566      return true;
1567    }
1568
1569    return false;
1570  }
1571
1572  default:
1573    return false;
1574  }
1575}
1576
1577void
1578Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1579                            const Expr * const *ExprArgs,
1580                            SourceLocation CallSiteLoc) {
1581  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1582                                  e = NonNull->args_end();
1583       i != e; ++i) {
1584    const Expr *ArgExpr = ExprArgs[*i];
1585    if (ArgExpr->isNullPointerConstant(Context,
1586                                       Expr::NPC_ValueDependentIsNotNull))
1587      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1588  }
1589}
1590
1591/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
1592/// functions) for correct use of format strings.
1593void
1594Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg,
1595                                unsigned format_idx, unsigned firstDataArg,
1596                                bool isPrintf) {
1597
1598  const Expr *Fn = TheCall->getCallee();
1599
1600  // The way the format attribute works in GCC, the implicit this argument
1601  // of member functions is counted. However, it doesn't appear in our own
1602  // lists, so decrement format_idx in that case.
1603  if (isa<CXXMemberCallExpr>(TheCall)) {
1604    const CXXMethodDecl *method_decl =
1605      dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl());
1606    if (method_decl && method_decl->isInstance()) {
1607      // Catch a format attribute mistakenly referring to the object argument.
1608      if (format_idx == 0)
1609        return;
1610      --format_idx;
1611      if(firstDataArg != 0)
1612        --firstDataArg;
1613    }
1614  }
1615
1616  // CHECK: printf/scanf-like function is called with no format string.
1617  if (format_idx >= TheCall->getNumArgs()) {
1618    Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string)
1619      << Fn->getSourceRange();
1620    return;
1621  }
1622
1623  const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts();
1624
1625  // CHECK: format string is not a string literal.
1626  //
1627  // Dynamically generated format strings are difficult to
1628  // automatically vet at compile time.  Requiring that format strings
1629  // are string literals: (1) permits the checking of format strings by
1630  // the compiler and thereby (2) can practically remove the source of
1631  // many format string exploits.
1632
1633  // Format string can be either ObjC string (e.g. @"%d") or
1634  // C string (e.g. "%d")
1635  // ObjC string uses the same format specifiers as C string, so we can use
1636  // the same format string checking logic for both ObjC and C strings.
1637  if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx,
1638                             firstDataArg, isPrintf))
1639    return;  // Literal format string found, check done!
1640
1641  // If there are no arguments specified, warn with -Wformat-security, otherwise
1642  // warn only with -Wformat-nonliteral.
1643  if (TheCall->getNumArgs() == format_idx+1)
1644    Diag(TheCall->getArg(format_idx)->getLocStart(),
1645         diag::warn_format_nonliteral_noargs)
1646      << OrigFormatExpr->getSourceRange();
1647  else
1648    Diag(TheCall->getArg(format_idx)->getLocStart(),
1649         diag::warn_format_nonliteral)
1650           << OrigFormatExpr->getSourceRange();
1651}
1652
1653namespace {
1654class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1655protected:
1656  Sema &S;
1657  const StringLiteral *FExpr;
1658  const Expr *OrigFormatExpr;
1659  const unsigned FirstDataArg;
1660  const unsigned NumDataArgs;
1661  const bool IsObjCLiteral;
1662  const char *Beg; // Start of format string.
1663  const bool HasVAListArg;
1664  const CallExpr *TheCall;
1665  unsigned FormatIdx;
1666  llvm::BitVector CoveredArgs;
1667  bool usesPositionalArgs;
1668  bool atFirstArg;
1669  bool inFunctionCall;
1670public:
1671  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1672                     const Expr *origFormatExpr, unsigned firstDataArg,
1673                     unsigned numDataArgs, bool isObjCLiteral,
1674                     const char *beg, bool hasVAListArg,
1675                     const CallExpr *theCall, unsigned formatIdx,
1676                     bool inFunctionCall)
1677    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1678      FirstDataArg(firstDataArg),
1679      NumDataArgs(numDataArgs),
1680      IsObjCLiteral(isObjCLiteral), Beg(beg),
1681      HasVAListArg(hasVAListArg),
1682      TheCall(theCall), FormatIdx(formatIdx),
1683      usesPositionalArgs(false), atFirstArg(true),
1684      inFunctionCall(inFunctionCall) {
1685        CoveredArgs.resize(numDataArgs);
1686        CoveredArgs.reset();
1687      }
1688
1689  void DoneProcessing();
1690
1691  void HandleIncompleteSpecifier(const char *startSpecifier,
1692                                 unsigned specifierLen);
1693
1694  virtual void HandleInvalidPosition(const char *startSpecifier,
1695                                     unsigned specifierLen,
1696                                     analyze_format_string::PositionContext p);
1697
1698  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1699
1700  void HandleNullChar(const char *nullCharacter);
1701
1702  template <typename Range>
1703  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1704                                   const Expr *ArgumentExpr,
1705                                   PartialDiagnostic PDiag,
1706                                   SourceLocation StringLoc,
1707                                   bool IsStringLocation, Range StringRange,
1708                                   FixItHint Fixit = FixItHint());
1709
1710protected:
1711  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1712                                        const char *startSpec,
1713                                        unsigned specifierLen,
1714                                        const char *csStart, unsigned csLen);
1715
1716  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
1717                                         const char *startSpec,
1718                                         unsigned specifierLen);
1719
1720  SourceRange getFormatStringRange();
1721  CharSourceRange getSpecifierRange(const char *startSpecifier,
1722                                    unsigned specifierLen);
1723  SourceLocation getLocationOfByte(const char *x);
1724
1725  const Expr *getDataArg(unsigned i) const;
1726
1727  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1728                    const analyze_format_string::ConversionSpecifier &CS,
1729                    const char *startSpecifier, unsigned specifierLen,
1730                    unsigned argIndex);
1731
1732  template <typename Range>
1733  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
1734                            bool IsStringLocation, Range StringRange,
1735                            FixItHint Fixit = FixItHint());
1736
1737  void CheckPositionalAndNonpositionalArgs(
1738      const analyze_format_string::FormatSpecifier *FS);
1739};
1740}
1741
1742SourceRange CheckFormatHandler::getFormatStringRange() {
1743  return OrigFormatExpr->getSourceRange();
1744}
1745
1746CharSourceRange CheckFormatHandler::
1747getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
1748  SourceLocation Start = getLocationOfByte(startSpecifier);
1749  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
1750
1751  // Advance the end SourceLocation by one due to half-open ranges.
1752  End = End.getLocWithOffset(1);
1753
1754  return CharSourceRange::getCharRange(Start, End);
1755}
1756
1757SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
1758  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
1759}
1760
1761void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
1762                                                   unsigned specifierLen){
1763  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
1764                       getLocationOfByte(startSpecifier),
1765                       /*IsStringLocation*/true,
1766                       getSpecifierRange(startSpecifier, specifierLen));
1767}
1768
1769void
1770CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
1771                                     analyze_format_string::PositionContext p) {
1772  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
1773                         << (unsigned) p,
1774                       getLocationOfByte(startPos), /*IsStringLocation*/true,
1775                       getSpecifierRange(startPos, posLen));
1776}
1777
1778void CheckFormatHandler::HandleZeroPosition(const char *startPos,
1779                                            unsigned posLen) {
1780  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
1781                               getLocationOfByte(startPos),
1782                               /*IsStringLocation*/true,
1783                               getSpecifierRange(startPos, posLen));
1784}
1785
1786void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
1787  if (!IsObjCLiteral) {
1788    // The presence of a null character is likely an error.
1789    EmitFormatDiagnostic(
1790      S.PDiag(diag::warn_printf_format_string_contains_null_char),
1791      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
1792      getFormatStringRange());
1793  }
1794}
1795
1796const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
1797  return TheCall->getArg(FirstDataArg + i);
1798}
1799
1800void CheckFormatHandler::DoneProcessing() {
1801    // Does the number of data arguments exceed the number of
1802    // format conversions in the format string?
1803  if (!HasVAListArg) {
1804      // Find any arguments that weren't covered.
1805    CoveredArgs.flip();
1806    signed notCoveredArg = CoveredArgs.find_first();
1807    if (notCoveredArg >= 0) {
1808      assert((unsigned)notCoveredArg < NumDataArgs);
1809      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
1810                           getDataArg((unsigned) notCoveredArg)->getLocStart(),
1811                           /*IsStringLocation*/false, getFormatStringRange());
1812    }
1813  }
1814}
1815
1816bool
1817CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
1818                                                     SourceLocation Loc,
1819                                                     const char *startSpec,
1820                                                     unsigned specifierLen,
1821                                                     const char *csStart,
1822                                                     unsigned csLen) {
1823
1824  bool keepGoing = true;
1825  if (argIndex < NumDataArgs) {
1826    // Consider the argument coverered, even though the specifier doesn't
1827    // make sense.
1828    CoveredArgs.set(argIndex);
1829  }
1830  else {
1831    // If argIndex exceeds the number of data arguments we
1832    // don't issue a warning because that is just a cascade of warnings (and
1833    // they may have intended '%%' anyway). We don't want to continue processing
1834    // the format string after this point, however, as we will like just get
1835    // gibberish when trying to match arguments.
1836    keepGoing = false;
1837  }
1838
1839  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
1840                         << StringRef(csStart, csLen),
1841                       Loc, /*IsStringLocation*/true,
1842                       getSpecifierRange(startSpec, specifierLen));
1843
1844  return keepGoing;
1845}
1846
1847void
1848CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
1849                                                      const char *startSpec,
1850                                                      unsigned specifierLen) {
1851  EmitFormatDiagnostic(
1852    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
1853    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
1854}
1855
1856bool
1857CheckFormatHandler::CheckNumArgs(
1858  const analyze_format_string::FormatSpecifier &FS,
1859  const analyze_format_string::ConversionSpecifier &CS,
1860  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
1861
1862  if (argIndex >= NumDataArgs) {
1863    PartialDiagnostic PDiag = FS.usesPositionalArg()
1864      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
1865           << (argIndex+1) << NumDataArgs)
1866      : S.PDiag(diag::warn_printf_insufficient_data_args);
1867    EmitFormatDiagnostic(
1868      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
1869      getSpecifierRange(startSpecifier, specifierLen));
1870    return false;
1871  }
1872  return true;
1873}
1874
1875template<typename Range>
1876void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
1877                                              SourceLocation Loc,
1878                                              bool IsStringLocation,
1879                                              Range StringRange,
1880                                              FixItHint FixIt) {
1881  EmitFormatDiagnostic(S, inFunctionCall, TheCall->getArg(FormatIdx), PDiag,
1882                       Loc, IsStringLocation, StringRange, FixIt);
1883}
1884
1885/// \brief If the format string is not within the funcion call, emit a note
1886/// so that the function call and string are in diagnostic messages.
1887///
1888/// \param inFunctionCall if true, the format string is within the function
1889/// call and only one diagnostic message will be produced.  Otherwise, an
1890/// extra note will be emitted pointing to location of the format string.
1891///
1892/// \param ArgumentExpr the expression that is passed as the format string
1893/// argument in the function call.  Used for getting locations when two
1894/// diagnostics are emitted.
1895///
1896/// \param PDiag the callee should already have provided any strings for the
1897/// diagnostic message.  This function only adds locations and fixits
1898/// to diagnostics.
1899///
1900/// \param Loc primary location for diagnostic.  If two diagnostics are
1901/// required, one will be at Loc and a new SourceLocation will be created for
1902/// the other one.
1903///
1904/// \param IsStringLocation if true, Loc points to the format string should be
1905/// used for the note.  Otherwise, Loc points to the argument list and will
1906/// be used with PDiag.
1907///
1908/// \param StringRange some or all of the string to highlight.  This is
1909/// templated so it can accept either a CharSourceRange or a SourceRange.
1910///
1911/// \param Fixit optional fix it hint for the format string.
1912template<typename Range>
1913void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
1914                                              const Expr *ArgumentExpr,
1915                                              PartialDiagnostic PDiag,
1916                                              SourceLocation Loc,
1917                                              bool IsStringLocation,
1918                                              Range StringRange,
1919                                              FixItHint FixIt) {
1920  if (InFunctionCall)
1921    S.Diag(Loc, PDiag) << StringRange << FixIt;
1922  else {
1923    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
1924      << ArgumentExpr->getSourceRange();
1925    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
1926           diag::note_format_string_defined)
1927      << StringRange << FixIt;
1928  }
1929}
1930
1931//===--- CHECK: Printf format string checking ------------------------------===//
1932
1933namespace {
1934class CheckPrintfHandler : public CheckFormatHandler {
1935public:
1936  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
1937                     const Expr *origFormatExpr, unsigned firstDataArg,
1938                     unsigned numDataArgs, bool isObjCLiteral,
1939                     const char *beg, bool hasVAListArg,
1940                     const CallExpr *theCall, unsigned formatIdx,
1941                     bool inFunctionCall)
1942  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
1943                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
1944                       theCall, formatIdx, inFunctionCall) {}
1945
1946
1947  bool HandleInvalidPrintfConversionSpecifier(
1948                                      const analyze_printf::PrintfSpecifier &FS,
1949                                      const char *startSpecifier,
1950                                      unsigned specifierLen);
1951
1952  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
1953                             const char *startSpecifier,
1954                             unsigned specifierLen);
1955
1956  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
1957                    const char *startSpecifier, unsigned specifierLen);
1958  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
1959                           const analyze_printf::OptionalAmount &Amt,
1960                           unsigned type,
1961                           const char *startSpecifier, unsigned specifierLen);
1962  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
1963                  const analyze_printf::OptionalFlag &flag,
1964                  const char *startSpecifier, unsigned specifierLen);
1965  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
1966                         const analyze_printf::OptionalFlag &ignoredFlag,
1967                         const analyze_printf::OptionalFlag &flag,
1968                         const char *startSpecifier, unsigned specifierLen);
1969};
1970}
1971
1972bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
1973                                      const analyze_printf::PrintfSpecifier &FS,
1974                                      const char *startSpecifier,
1975                                      unsigned specifierLen) {
1976  const analyze_printf::PrintfConversionSpecifier &CS =
1977    FS.getConversionSpecifier();
1978
1979  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
1980                                          getLocationOfByte(CS.getStart()),
1981                                          startSpecifier, specifierLen,
1982                                          CS.getStart(), CS.getLength());
1983}
1984
1985bool CheckPrintfHandler::HandleAmount(
1986                               const analyze_format_string::OptionalAmount &Amt,
1987                               unsigned k, const char *startSpecifier,
1988                               unsigned specifierLen) {
1989
1990  if (Amt.hasDataArgument()) {
1991    if (!HasVAListArg) {
1992      unsigned argIndex = Amt.getArgIndex();
1993      if (argIndex >= NumDataArgs) {
1994        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
1995                               << k,
1996                             getLocationOfByte(Amt.getStart()),
1997                             /*IsStringLocation*/true,
1998                             getSpecifierRange(startSpecifier, specifierLen));
1999        // Don't do any more checking.  We will just emit
2000        // spurious errors.
2001        return false;
2002      }
2003
2004      // Type check the data argument.  It should be an 'int'.
2005      // Although not in conformance with C99, we also allow the argument to be
2006      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2007      // doesn't emit a warning for that case.
2008      CoveredArgs.set(argIndex);
2009      const Expr *Arg = getDataArg(argIndex);
2010      QualType T = Arg->getType();
2011
2012      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
2013      assert(ATR.isValid());
2014
2015      if (!ATR.matchesType(S.Context, T)) {
2016        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2017                               << k << ATR.getRepresentativeType(S.Context)
2018                               << T << Arg->getSourceRange(),
2019                             getLocationOfByte(Amt.getStart()),
2020                             /*IsStringLocation*/true,
2021                             getSpecifierRange(startSpecifier, specifierLen));
2022        // Don't do any more checking.  We will just emit
2023        // spurious errors.
2024        return false;
2025      }
2026    }
2027  }
2028  return true;
2029}
2030
2031void CheckPrintfHandler::HandleInvalidAmount(
2032                                      const analyze_printf::PrintfSpecifier &FS,
2033                                      const analyze_printf::OptionalAmount &Amt,
2034                                      unsigned type,
2035                                      const char *startSpecifier,
2036                                      unsigned specifierLen) {
2037  const analyze_printf::PrintfConversionSpecifier &CS =
2038    FS.getConversionSpecifier();
2039
2040  FixItHint fixit =
2041    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2042      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2043                                 Amt.getConstantLength()))
2044      : FixItHint();
2045
2046  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2047                         << type << CS.toString(),
2048                       getLocationOfByte(Amt.getStart()),
2049                       /*IsStringLocation*/true,
2050                       getSpecifierRange(startSpecifier, specifierLen),
2051                       fixit);
2052}
2053
2054void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2055                                    const analyze_printf::OptionalFlag &flag,
2056                                    const char *startSpecifier,
2057                                    unsigned specifierLen) {
2058  // Warn about pointless flag with a fixit removal.
2059  const analyze_printf::PrintfConversionSpecifier &CS =
2060    FS.getConversionSpecifier();
2061  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2062                         << flag.toString() << CS.toString(),
2063                       getLocationOfByte(flag.getPosition()),
2064                       /*IsStringLocation*/true,
2065                       getSpecifierRange(startSpecifier, specifierLen),
2066                       FixItHint::CreateRemoval(
2067                         getSpecifierRange(flag.getPosition(), 1)));
2068}
2069
2070void CheckPrintfHandler::HandleIgnoredFlag(
2071                                const analyze_printf::PrintfSpecifier &FS,
2072                                const analyze_printf::OptionalFlag &ignoredFlag,
2073                                const analyze_printf::OptionalFlag &flag,
2074                                const char *startSpecifier,
2075                                unsigned specifierLen) {
2076  // Warn about ignored flag with a fixit removal.
2077  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2078                         << ignoredFlag.toString() << flag.toString(),
2079                       getLocationOfByte(ignoredFlag.getPosition()),
2080                       /*IsStringLocation*/true,
2081                       getSpecifierRange(startSpecifier, specifierLen),
2082                       FixItHint::CreateRemoval(
2083                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2084}
2085
2086bool
2087CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2088                                            &FS,
2089                                          const char *startSpecifier,
2090                                          unsigned specifierLen) {
2091
2092  using namespace analyze_format_string;
2093  using namespace analyze_printf;
2094  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2095
2096  if (FS.consumesDataArgument()) {
2097    if (atFirstArg) {
2098        atFirstArg = false;
2099        usesPositionalArgs = FS.usesPositionalArg();
2100    }
2101    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2102      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2103                                        startSpecifier, specifierLen);
2104      return false;
2105    }
2106  }
2107
2108  // First check if the field width, precision, and conversion specifier
2109  // have matching data arguments.
2110  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2111                    startSpecifier, specifierLen)) {
2112    return false;
2113  }
2114
2115  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2116                    startSpecifier, specifierLen)) {
2117    return false;
2118  }
2119
2120  if (!CS.consumesDataArgument()) {
2121    // FIXME: Technically specifying a precision or field width here
2122    // makes no sense.  Worth issuing a warning at some point.
2123    return true;
2124  }
2125
2126  // Consume the argument.
2127  unsigned argIndex = FS.getArgIndex();
2128  if (argIndex < NumDataArgs) {
2129    // The check to see if the argIndex is valid will come later.
2130    // We set the bit here because we may exit early from this
2131    // function if we encounter some other error.
2132    CoveredArgs.set(argIndex);
2133  }
2134
2135  // Check for using an Objective-C specific conversion specifier
2136  // in a non-ObjC literal.
2137  if (!IsObjCLiteral && CS.isObjCArg()) {
2138    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2139                                                  specifierLen);
2140  }
2141
2142  // Check for invalid use of field width
2143  if (!FS.hasValidFieldWidth()) {
2144    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2145        startSpecifier, specifierLen);
2146  }
2147
2148  // Check for invalid use of precision
2149  if (!FS.hasValidPrecision()) {
2150    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2151        startSpecifier, specifierLen);
2152  }
2153
2154  // Check each flag does not conflict with any other component.
2155  if (!FS.hasValidThousandsGroupingPrefix())
2156    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2157  if (!FS.hasValidLeadingZeros())
2158    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2159  if (!FS.hasValidPlusPrefix())
2160    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2161  if (!FS.hasValidSpacePrefix())
2162    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2163  if (!FS.hasValidAlternativeForm())
2164    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2165  if (!FS.hasValidLeftJustified())
2166    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2167
2168  // Check that flags are not ignored by another flag
2169  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2170    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2171        startSpecifier, specifierLen);
2172  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2173    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2174            startSpecifier, specifierLen);
2175
2176  // Check the length modifier is valid with the given conversion specifier.
2177  const LengthModifier &LM = FS.getLengthModifier();
2178  if (!FS.hasValidLengthModifier())
2179    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2180                           << LM.toString() << CS.toString(),
2181                         getLocationOfByte(LM.getStart()),
2182                         /*IsStringLocation*/true,
2183                         getSpecifierRange(startSpecifier, specifierLen),
2184                         FixItHint::CreateRemoval(
2185                           getSpecifierRange(LM.getStart(),
2186                                             LM.getLength())));
2187
2188  // Are we using '%n'?
2189  if (CS.getKind() == ConversionSpecifier::nArg) {
2190    // Issue a warning about this being a possible security issue.
2191    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
2192                         getLocationOfByte(CS.getStart()),
2193                         /*IsStringLocation*/true,
2194                         getSpecifierRange(startSpecifier, specifierLen));
2195    // Continue checking the other format specifiers.
2196    return true;
2197  }
2198
2199  // The remaining checks depend on the data arguments.
2200  if (HasVAListArg)
2201    return true;
2202
2203  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2204    return false;
2205
2206  // Now type check the data expression that matches the
2207  // format specifier.
2208  const Expr *Ex = getDataArg(argIndex);
2209  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context);
2210  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2211    // Check if we didn't match because of an implicit cast from a 'char'
2212    // or 'short' to an 'int'.  This is done because printf is a varargs
2213    // function.
2214    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
2215      if (ICE->getType() == S.Context.IntTy) {
2216        // All further checking is done on the subexpression.
2217        Ex = ICE->getSubExpr();
2218        if (ATR.matchesType(S.Context, Ex->getType()))
2219          return true;
2220      }
2221
2222    // We may be able to offer a FixItHint if it is a supported type.
2223    PrintfSpecifier fixedFS = FS;
2224    bool success = fixedFS.fixType(Ex->getType(), S.getLangOptions());
2225
2226    if (success) {
2227      // Get the fix string from the fixed format specifier
2228      llvm::SmallString<128> buf;
2229      llvm::raw_svector_ostream os(buf);
2230      fixedFS.toString(os);
2231
2232      // FIXME: getRepresentativeType() perhaps should return a string
2233      // instead of a QualType to better handle when the representative
2234      // type is 'wint_t' (which is defined in the system headers).
2235      EmitFormatDiagnostic(
2236        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2237          << ATR.getRepresentativeType(S.Context) << Ex->getType()
2238          << Ex->getSourceRange(),
2239        getLocationOfByte(CS.getStart()),
2240        /*IsStringLocation*/true,
2241        getSpecifierRange(startSpecifier, specifierLen),
2242        FixItHint::CreateReplacement(
2243          getSpecifierRange(startSpecifier, specifierLen),
2244          os.str()));
2245    }
2246    else {
2247      S.Diag(getLocationOfByte(CS.getStart()),
2248             diag::warn_printf_conversion_argument_type_mismatch)
2249        << ATR.getRepresentativeType(S.Context) << Ex->getType()
2250        << getSpecifierRange(startSpecifier, specifierLen)
2251        << Ex->getSourceRange();
2252    }
2253  }
2254
2255  return true;
2256}
2257
2258//===--- CHECK: Scanf format string checking ------------------------------===//
2259
2260namespace {
2261class CheckScanfHandler : public CheckFormatHandler {
2262public:
2263  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2264                    const Expr *origFormatExpr, unsigned firstDataArg,
2265                    unsigned numDataArgs, bool isObjCLiteral,
2266                    const char *beg, bool hasVAListArg,
2267                    const CallExpr *theCall, unsigned formatIdx,
2268                    bool inFunctionCall)
2269  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2270                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
2271                       theCall, formatIdx, inFunctionCall) {}
2272
2273  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2274                            const char *startSpecifier,
2275                            unsigned specifierLen);
2276
2277  bool HandleInvalidScanfConversionSpecifier(
2278          const analyze_scanf::ScanfSpecifier &FS,
2279          const char *startSpecifier,
2280          unsigned specifierLen);
2281
2282  void HandleIncompleteScanList(const char *start, const char *end);
2283};
2284}
2285
2286void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2287                                                 const char *end) {
2288  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2289                       getLocationOfByte(end), /*IsStringLocation*/true,
2290                       getSpecifierRange(start, end - start));
2291}
2292
2293bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2294                                        const analyze_scanf::ScanfSpecifier &FS,
2295                                        const char *startSpecifier,
2296                                        unsigned specifierLen) {
2297
2298  const analyze_scanf::ScanfConversionSpecifier &CS =
2299    FS.getConversionSpecifier();
2300
2301  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2302                                          getLocationOfByte(CS.getStart()),
2303                                          startSpecifier, specifierLen,
2304                                          CS.getStart(), CS.getLength());
2305}
2306
2307bool CheckScanfHandler::HandleScanfSpecifier(
2308                                       const analyze_scanf::ScanfSpecifier &FS,
2309                                       const char *startSpecifier,
2310                                       unsigned specifierLen) {
2311
2312  using namespace analyze_scanf;
2313  using namespace analyze_format_string;
2314
2315  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2316
2317  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2318  // be used to decide if we are using positional arguments consistently.
2319  if (FS.consumesDataArgument()) {
2320    if (atFirstArg) {
2321      atFirstArg = false;
2322      usesPositionalArgs = FS.usesPositionalArg();
2323    }
2324    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2325      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2326                                        startSpecifier, specifierLen);
2327      return false;
2328    }
2329  }
2330
2331  // Check if the field with is non-zero.
2332  const OptionalAmount &Amt = FS.getFieldWidth();
2333  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2334    if (Amt.getConstantAmount() == 0) {
2335      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2336                                                   Amt.getConstantLength());
2337      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2338                           getLocationOfByte(Amt.getStart()),
2339                           /*IsStringLocation*/true, R,
2340                           FixItHint::CreateRemoval(R));
2341    }
2342  }
2343
2344  if (!FS.consumesDataArgument()) {
2345    // FIXME: Technically specifying a precision or field width here
2346    // makes no sense.  Worth issuing a warning at some point.
2347    return true;
2348  }
2349
2350  // Consume the argument.
2351  unsigned argIndex = FS.getArgIndex();
2352  if (argIndex < NumDataArgs) {
2353      // The check to see if the argIndex is valid will come later.
2354      // We set the bit here because we may exit early from this
2355      // function if we encounter some other error.
2356    CoveredArgs.set(argIndex);
2357  }
2358
2359  // Check the length modifier is valid with the given conversion specifier.
2360  const LengthModifier &LM = FS.getLengthModifier();
2361  if (!FS.hasValidLengthModifier()) {
2362    S.Diag(getLocationOfByte(LM.getStart()),
2363           diag::warn_format_nonsensical_length)
2364      << LM.toString() << CS.toString()
2365      << getSpecifierRange(startSpecifier, specifierLen)
2366      << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(),
2367                                                    LM.getLength()));
2368  }
2369
2370  // The remaining checks depend on the data arguments.
2371  if (HasVAListArg)
2372    return true;
2373
2374  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2375    return false;
2376
2377  // FIXME: Check that the argument type matches the format specifier.
2378
2379  return true;
2380}
2381
2382void Sema::CheckFormatString(const StringLiteral *FExpr,
2383                             const Expr *OrigFormatExpr,
2384                             const CallExpr *TheCall, bool HasVAListArg,
2385                             unsigned format_idx, unsigned firstDataArg,
2386                             bool isPrintf, bool inFunctionCall) {
2387
2388  // CHECK: is the format string a wide literal?
2389  if (!FExpr->isAscii()) {
2390    CheckFormatHandler::EmitFormatDiagnostic(
2391      *this, inFunctionCall, TheCall->getArg(format_idx),
2392      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
2393      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2394    return;
2395  }
2396
2397  // Str - The format string.  NOTE: this is NOT null-terminated!
2398  StringRef StrRef = FExpr->getString();
2399  const char *Str = StrRef.data();
2400  unsigned StrLen = StrRef.size();
2401  const unsigned numDataArgs = TheCall->getNumArgs() - firstDataArg;
2402
2403  // CHECK: empty format string?
2404  if (StrLen == 0 && numDataArgs > 0) {
2405    CheckFormatHandler::EmitFormatDiagnostic(
2406      *this, inFunctionCall, TheCall->getArg(format_idx),
2407      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
2408      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2409    return;
2410  }
2411
2412  if (isPrintf) {
2413    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2414                         numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2415                         Str, HasVAListArg, TheCall, format_idx,
2416                         inFunctionCall);
2417
2418    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen))
2419      H.DoneProcessing();
2420  }
2421  else {
2422    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2423                        numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2424                        Str, HasVAListArg, TheCall, format_idx,
2425                        inFunctionCall);
2426
2427    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen))
2428      H.DoneProcessing();
2429  }
2430}
2431
2432//===--- CHECK: Standard memory functions ---------------------------------===//
2433
2434/// \brief Determine whether the given type is a dynamic class type (e.g.,
2435/// whether it has a vtable).
2436static bool isDynamicClassType(QualType T) {
2437  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
2438    if (CXXRecordDecl *Definition = Record->getDefinition())
2439      if (Definition->isDynamicClass())
2440        return true;
2441
2442  return false;
2443}
2444
2445/// \brief If E is a sizeof expression, returns its argument expression,
2446/// otherwise returns NULL.
2447static const Expr *getSizeOfExprArg(const Expr* E) {
2448  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2449      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2450    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
2451      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
2452
2453  return 0;
2454}
2455
2456/// \brief If E is a sizeof expression, returns its argument type.
2457static QualType getSizeOfArgType(const Expr* E) {
2458  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2459      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2460    if (SizeOf->getKind() == clang::UETT_SizeOf)
2461      return SizeOf->getTypeOfArgument();
2462
2463  return QualType();
2464}
2465
2466/// \brief Check for dangerous or invalid arguments to memset().
2467///
2468/// This issues warnings on known problematic, dangerous or unspecified
2469/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
2470/// function calls.
2471///
2472/// \param Call The call expression to diagnose.
2473void Sema::CheckMemaccessArguments(const CallExpr *Call,
2474                                   CheckedMemoryFunction CMF,
2475                                   IdentifierInfo *FnName) {
2476  // It is possible to have a non-standard definition of memset.  Validate
2477  // we have enough arguments, and if not, abort further checking.
2478  unsigned ExpectedNumArgs = (CMF == CMF_Strndup ? 2 : 3);
2479  if (Call->getNumArgs() < ExpectedNumArgs)
2480    return;
2481
2482  unsigned LastArg = (CMF == CMF_Memset || CMF == CMF_Strndup ? 1 : 2);
2483  unsigned LenArg = (CMF == CMF_Strndup ? 1 : 2);
2484  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
2485
2486  // We have special checking when the length is a sizeof expression.
2487  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
2488  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
2489  llvm::FoldingSetNodeID SizeOfArgID;
2490
2491  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
2492    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
2493    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
2494
2495    QualType DestTy = Dest->getType();
2496    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
2497      QualType PointeeTy = DestPtrTy->getPointeeType();
2498
2499      // Never warn about void type pointers. This can be used to suppress
2500      // false positives.
2501      if (PointeeTy->isVoidType())
2502        continue;
2503
2504      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
2505      // actually comparing the expressions for equality. Because computing the
2506      // expression IDs can be expensive, we only do this if the diagnostic is
2507      // enabled.
2508      if (SizeOfArg &&
2509          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
2510                                   SizeOfArg->getExprLoc())) {
2511        // We only compute IDs for expressions if the warning is enabled, and
2512        // cache the sizeof arg's ID.
2513        if (SizeOfArgID == llvm::FoldingSetNodeID())
2514          SizeOfArg->Profile(SizeOfArgID, Context, true);
2515        llvm::FoldingSetNodeID DestID;
2516        Dest->Profile(DestID, Context, true);
2517        if (DestID == SizeOfArgID) {
2518          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
2519          //       over sizeof(src) as well.
2520          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
2521          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
2522            if (UnaryOp->getOpcode() == UO_AddrOf)
2523              ActionIdx = 1; // If its an address-of operator, just remove it.
2524          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
2525            ActionIdx = 2; // If the pointee's size is sizeof(char),
2526                           // suggest an explicit length.
2527          unsigned DestSrcSelect = (CMF == CMF_Strndup ? 1 : ArgIdx);
2528          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
2529                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
2530                                << FnName << DestSrcSelect << ActionIdx
2531                                << Dest->getSourceRange()
2532                                << SizeOfArg->getSourceRange());
2533          break;
2534        }
2535      }
2536
2537      // Also check for cases where the sizeof argument is the exact same
2538      // type as the memory argument, and where it points to a user-defined
2539      // record type.
2540      if (SizeOfArgTy != QualType()) {
2541        if (PointeeTy->isRecordType() &&
2542            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
2543          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
2544                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
2545                                << FnName << SizeOfArgTy << ArgIdx
2546                                << PointeeTy << Dest->getSourceRange()
2547                                << LenExpr->getSourceRange());
2548          break;
2549        }
2550      }
2551
2552      // Always complain about dynamic classes.
2553      if (isDynamicClassType(PointeeTy))
2554        DiagRuntimeBehavior(
2555          Dest->getExprLoc(), Dest,
2556          PDiag(diag::warn_dyn_class_memaccess)
2557            << (CMF == CMF_Memcmp ? ArgIdx + 2 : ArgIdx) << FnName << PointeeTy
2558            // "overwritten" if we're warning about the destination for any call
2559            // but memcmp; otherwise a verb appropriate to the call.
2560            << (ArgIdx == 0 && CMF != CMF_Memcmp ? 0 : (unsigned)CMF)
2561            << Call->getCallee()->getSourceRange());
2562      else if (PointeeTy.hasNonTrivialObjCLifetime() && CMF != CMF_Memset)
2563        DiagRuntimeBehavior(
2564          Dest->getExprLoc(), Dest,
2565          PDiag(diag::warn_arc_object_memaccess)
2566            << ArgIdx << FnName << PointeeTy
2567            << Call->getCallee()->getSourceRange());
2568      else
2569        continue;
2570
2571      DiagRuntimeBehavior(
2572        Dest->getExprLoc(), Dest,
2573        PDiag(diag::note_bad_memaccess_silence)
2574          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
2575      break;
2576    }
2577  }
2578}
2579
2580// A little helper routine: ignore addition and subtraction of integer literals.
2581// This intentionally does not ignore all integer constant expressions because
2582// we don't want to remove sizeof().
2583static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
2584  Ex = Ex->IgnoreParenCasts();
2585
2586  for (;;) {
2587    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
2588    if (!BO || !BO->isAdditiveOp())
2589      break;
2590
2591    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
2592    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
2593
2594    if (isa<IntegerLiteral>(RHS))
2595      Ex = LHS;
2596    else if (isa<IntegerLiteral>(LHS))
2597      Ex = RHS;
2598    else
2599      break;
2600  }
2601
2602  return Ex;
2603}
2604
2605// Warn if the user has made the 'size' argument to strlcpy or strlcat
2606// be the size of the source, instead of the destination.
2607void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
2608                                    IdentifierInfo *FnName) {
2609
2610  // Don't crash if the user has the wrong number of arguments
2611  if (Call->getNumArgs() != 3)
2612    return;
2613
2614  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
2615  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
2616  const Expr *CompareWithSrc = NULL;
2617
2618  // Look for 'strlcpy(dst, x, sizeof(x))'
2619  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
2620    CompareWithSrc = Ex;
2621  else {
2622    // Look for 'strlcpy(dst, x, strlen(x))'
2623    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
2624      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
2625          && SizeCall->getNumArgs() == 1)
2626        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
2627    }
2628  }
2629
2630  if (!CompareWithSrc)
2631    return;
2632
2633  // Determine if the argument to sizeof/strlen is equal to the source
2634  // argument.  In principle there's all kinds of things you could do
2635  // here, for instance creating an == expression and evaluating it with
2636  // EvaluateAsBooleanCondition, but this uses a more direct technique:
2637  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
2638  if (!SrcArgDRE)
2639    return;
2640
2641  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
2642  if (!CompareWithSrcDRE ||
2643      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
2644    return;
2645
2646  const Expr *OriginalSizeArg = Call->getArg(2);
2647  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
2648    << OriginalSizeArg->getSourceRange() << FnName;
2649
2650  // Output a FIXIT hint if the destination is an array (rather than a
2651  // pointer to an array).  This could be enhanced to handle some
2652  // pointers if we know the actual size, like if DstArg is 'array+2'
2653  // we could say 'sizeof(array)-2'.
2654  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
2655  QualType DstArgTy = DstArg->getType();
2656
2657  // Only handle constant-sized or VLAs, but not flexible members.
2658  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2659    // Only issue the FIXIT for arrays of size > 1.
2660    if (CAT->getSize().getSExtValue() <= 1)
2661      return;
2662  } else if (!DstArgTy->isVariableArrayType()) {
2663    return;
2664  }
2665
2666  llvm::SmallString<128> sizeString;
2667  llvm::raw_svector_ostream OS(sizeString);
2668  OS << "sizeof(";
2669  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2670  OS << ")";
2671
2672  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
2673    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
2674                                    OS.str());
2675}
2676
2677//===--- CHECK: Return Address of Stack Variable --------------------------===//
2678
2679static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars);
2680static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars);
2681
2682/// CheckReturnStackAddr - Check if a return statement returns the address
2683///   of a stack variable.
2684void
2685Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
2686                           SourceLocation ReturnLoc) {
2687
2688  Expr *stackE = 0;
2689  SmallVector<DeclRefExpr *, 8> refVars;
2690
2691  // Perform checking for returned stack addresses, local blocks,
2692  // label addresses or references to temporaries.
2693  if (lhsType->isPointerType() ||
2694      (!getLangOptions().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
2695    stackE = EvalAddr(RetValExp, refVars);
2696  } else if (lhsType->isReferenceType()) {
2697    stackE = EvalVal(RetValExp, refVars);
2698  }
2699
2700  if (stackE == 0)
2701    return; // Nothing suspicious was found.
2702
2703  SourceLocation diagLoc;
2704  SourceRange diagRange;
2705  if (refVars.empty()) {
2706    diagLoc = stackE->getLocStart();
2707    diagRange = stackE->getSourceRange();
2708  } else {
2709    // We followed through a reference variable. 'stackE' contains the
2710    // problematic expression but we will warn at the return statement pointing
2711    // at the reference variable. We will later display the "trail" of
2712    // reference variables using notes.
2713    diagLoc = refVars[0]->getLocStart();
2714    diagRange = refVars[0]->getSourceRange();
2715  }
2716
2717  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
2718    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
2719                                             : diag::warn_ret_stack_addr)
2720     << DR->getDecl()->getDeclName() << diagRange;
2721  } else if (isa<BlockExpr>(stackE)) { // local block.
2722    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
2723  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
2724    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
2725  } else { // local temporary.
2726    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
2727                                             : diag::warn_ret_local_temp_addr)
2728     << diagRange;
2729  }
2730
2731  // Display the "trail" of reference variables that we followed until we
2732  // found the problematic expression using notes.
2733  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
2734    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
2735    // If this var binds to another reference var, show the range of the next
2736    // var, otherwise the var binds to the problematic expression, in which case
2737    // show the range of the expression.
2738    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
2739                                  : stackE->getSourceRange();
2740    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
2741      << VD->getDeclName() << range;
2742  }
2743}
2744
2745/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
2746///  check if the expression in a return statement evaluates to an address
2747///  to a location on the stack, a local block, an address of a label, or a
2748///  reference to local temporary. The recursion is used to traverse the
2749///  AST of the return expression, with recursion backtracking when we
2750///  encounter a subexpression that (1) clearly does not lead to one of the
2751///  above problematic expressions (2) is something we cannot determine leads to
2752///  a problematic expression based on such local checking.
2753///
2754///  Both EvalAddr and EvalVal follow through reference variables to evaluate
2755///  the expression that they point to. Such variables are added to the
2756///  'refVars' vector so that we know what the reference variable "trail" was.
2757///
2758///  EvalAddr processes expressions that are pointers that are used as
2759///  references (and not L-values).  EvalVal handles all other values.
2760///  At the base case of the recursion is a check for the above problematic
2761///  expressions.
2762///
2763///  This implementation handles:
2764///
2765///   * pointer-to-pointer casts
2766///   * implicit conversions from array references to pointers
2767///   * taking the address of fields
2768///   * arbitrary interplay between "&" and "*" operators
2769///   * pointer arithmetic from an address of a stack variable
2770///   * taking the address of an array element where the array is on the stack
2771static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
2772  if (E->isTypeDependent())
2773      return NULL;
2774
2775  // We should only be called for evaluating pointer expressions.
2776  assert((E->getType()->isAnyPointerType() ||
2777          E->getType()->isBlockPointerType() ||
2778          E->getType()->isObjCQualifiedIdType()) &&
2779         "EvalAddr only works on pointers");
2780
2781  E = E->IgnoreParens();
2782
2783  // Our "symbolic interpreter" is just a dispatch off the currently
2784  // viewed AST node.  We then recursively traverse the AST by calling
2785  // EvalAddr and EvalVal appropriately.
2786  switch (E->getStmtClass()) {
2787  case Stmt::DeclRefExprClass: {
2788    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2789
2790    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2791      // If this is a reference variable, follow through to the expression that
2792      // it points to.
2793      if (V->hasLocalStorage() &&
2794          V->getType()->isReferenceType() && V->hasInit()) {
2795        // Add the reference variable to the "trail".
2796        refVars.push_back(DR);
2797        return EvalAddr(V->getInit(), refVars);
2798      }
2799
2800    return NULL;
2801  }
2802
2803  case Stmt::UnaryOperatorClass: {
2804    // The only unary operator that make sense to handle here
2805    // is AddrOf.  All others don't make sense as pointers.
2806    UnaryOperator *U = cast<UnaryOperator>(E);
2807
2808    if (U->getOpcode() == UO_AddrOf)
2809      return EvalVal(U->getSubExpr(), refVars);
2810    else
2811      return NULL;
2812  }
2813
2814  case Stmt::BinaryOperatorClass: {
2815    // Handle pointer arithmetic.  All other binary operators are not valid
2816    // in this context.
2817    BinaryOperator *B = cast<BinaryOperator>(E);
2818    BinaryOperatorKind op = B->getOpcode();
2819
2820    if (op != BO_Add && op != BO_Sub)
2821      return NULL;
2822
2823    Expr *Base = B->getLHS();
2824
2825    // Determine which argument is the real pointer base.  It could be
2826    // the RHS argument instead of the LHS.
2827    if (!Base->getType()->isPointerType()) Base = B->getRHS();
2828
2829    assert (Base->getType()->isPointerType());
2830    return EvalAddr(Base, refVars);
2831  }
2832
2833  // For conditional operators we need to see if either the LHS or RHS are
2834  // valid DeclRefExpr*s.  If one of them is valid, we return it.
2835  case Stmt::ConditionalOperatorClass: {
2836    ConditionalOperator *C = cast<ConditionalOperator>(E);
2837
2838    // Handle the GNU extension for missing LHS.
2839    if (Expr *lhsExpr = C->getLHS()) {
2840    // In C++, we can have a throw-expression, which has 'void' type.
2841      if (!lhsExpr->getType()->isVoidType())
2842        if (Expr* LHS = EvalAddr(lhsExpr, refVars))
2843          return LHS;
2844    }
2845
2846    // In C++, we can have a throw-expression, which has 'void' type.
2847    if (C->getRHS()->getType()->isVoidType())
2848      return NULL;
2849
2850    return EvalAddr(C->getRHS(), refVars);
2851  }
2852
2853  case Stmt::BlockExprClass:
2854    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
2855      return E; // local block.
2856    return NULL;
2857
2858  case Stmt::AddrLabelExprClass:
2859    return E; // address of label.
2860
2861  case Stmt::ExprWithCleanupsClass:
2862    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
2863
2864  // For casts, we need to handle conversions from arrays to
2865  // pointer values, and pointer-to-pointer conversions.
2866  case Stmt::ImplicitCastExprClass:
2867  case Stmt::CStyleCastExprClass:
2868  case Stmt::CXXFunctionalCastExprClass:
2869  case Stmt::ObjCBridgedCastExprClass: {
2870    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
2871    QualType T = SubExpr->getType();
2872
2873    if (SubExpr->getType()->isPointerType() ||
2874        SubExpr->getType()->isBlockPointerType() ||
2875        SubExpr->getType()->isObjCQualifiedIdType())
2876      return EvalAddr(SubExpr, refVars);
2877    else if (T->isArrayType())
2878      return EvalVal(SubExpr, refVars);
2879    else
2880      return 0;
2881  }
2882
2883  // C++ casts.  For dynamic casts, static casts, and const casts, we
2884  // are always converting from a pointer-to-pointer, so we just blow
2885  // through the cast.  In the case the dynamic cast doesn't fail (and
2886  // return NULL), we take the conservative route and report cases
2887  // where we return the address of a stack variable.  For Reinterpre
2888  // FIXME: The comment about is wrong; we're not always converting
2889  // from pointer to pointer. I'm guessing that this code should also
2890  // handle references to objects.
2891  case Stmt::CXXStaticCastExprClass:
2892  case Stmt::CXXDynamicCastExprClass:
2893  case Stmt::CXXConstCastExprClass:
2894  case Stmt::CXXReinterpretCastExprClass: {
2895      Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr();
2896      if (S->getType()->isPointerType() || S->getType()->isBlockPointerType())
2897        return EvalAddr(S, refVars);
2898      else
2899        return NULL;
2900  }
2901
2902  case Stmt::MaterializeTemporaryExprClass:
2903    if (Expr *Result = EvalAddr(
2904                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
2905                                refVars))
2906      return Result;
2907
2908    return E;
2909
2910  // Everything else: we simply don't reason about them.
2911  default:
2912    return NULL;
2913  }
2914}
2915
2916
2917///  EvalVal - This function is complements EvalAddr in the mutual recursion.
2918///   See the comments for EvalAddr for more details.
2919static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) {
2920do {
2921  // We should only be called for evaluating non-pointer expressions, or
2922  // expressions with a pointer type that are not used as references but instead
2923  // are l-values (e.g., DeclRefExpr with a pointer type).
2924
2925  // Our "symbolic interpreter" is just a dispatch off the currently
2926  // viewed AST node.  We then recursively traverse the AST by calling
2927  // EvalAddr and EvalVal appropriately.
2928
2929  E = E->IgnoreParens();
2930  switch (E->getStmtClass()) {
2931  case Stmt::ImplicitCastExprClass: {
2932    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
2933    if (IE->getValueKind() == VK_LValue) {
2934      E = IE->getSubExpr();
2935      continue;
2936    }
2937    return NULL;
2938  }
2939
2940  case Stmt::ExprWithCleanupsClass:
2941    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars);
2942
2943  case Stmt::DeclRefExprClass: {
2944    // When we hit a DeclRefExpr we are looking at code that refers to a
2945    // variable's name. If it's not a reference variable we check if it has
2946    // local storage within the function, and if so, return the expression.
2947    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2948
2949    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2950      if (V->hasLocalStorage()) {
2951        if (!V->getType()->isReferenceType())
2952          return DR;
2953
2954        // Reference variable, follow through to the expression that
2955        // it points to.
2956        if (V->hasInit()) {
2957          // Add the reference variable to the "trail".
2958          refVars.push_back(DR);
2959          return EvalVal(V->getInit(), refVars);
2960        }
2961      }
2962
2963    return NULL;
2964  }
2965
2966  case Stmt::UnaryOperatorClass: {
2967    // The only unary operator that make sense to handle here
2968    // is Deref.  All others don't resolve to a "name."  This includes
2969    // handling all sorts of rvalues passed to a unary operator.
2970    UnaryOperator *U = cast<UnaryOperator>(E);
2971
2972    if (U->getOpcode() == UO_Deref)
2973      return EvalAddr(U->getSubExpr(), refVars);
2974
2975    return NULL;
2976  }
2977
2978  case Stmt::ArraySubscriptExprClass: {
2979    // Array subscripts are potential references to data on the stack.  We
2980    // retrieve the DeclRefExpr* for the array variable if it indeed
2981    // has local storage.
2982    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars);
2983  }
2984
2985  case Stmt::ConditionalOperatorClass: {
2986    // For conditional operators we need to see if either the LHS or RHS are
2987    // non-NULL Expr's.  If one is non-NULL, we return it.
2988    ConditionalOperator *C = cast<ConditionalOperator>(E);
2989
2990    // Handle the GNU extension for missing LHS.
2991    if (Expr *lhsExpr = C->getLHS())
2992      if (Expr *LHS = EvalVal(lhsExpr, refVars))
2993        return LHS;
2994
2995    return EvalVal(C->getRHS(), refVars);
2996  }
2997
2998  // Accesses to members are potential references to data on the stack.
2999  case Stmt::MemberExprClass: {
3000    MemberExpr *M = cast<MemberExpr>(E);
3001
3002    // Check for indirect access.  We only want direct field accesses.
3003    if (M->isArrow())
3004      return NULL;
3005
3006    // Check whether the member type is itself a reference, in which case
3007    // we're not going to refer to the member, but to what the member refers to.
3008    if (M->getMemberDecl()->getType()->isReferenceType())
3009      return NULL;
3010
3011    return EvalVal(M->getBase(), refVars);
3012  }
3013
3014  case Stmt::MaterializeTemporaryExprClass:
3015    if (Expr *Result = EvalVal(
3016                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3017                               refVars))
3018      return Result;
3019
3020    return E;
3021
3022  default:
3023    // Check that we don't return or take the address of a reference to a
3024    // temporary. This is only useful in C++.
3025    if (!E->isTypeDependent() && E->isRValue())
3026      return E;
3027
3028    // Everything else: we simply don't reason about them.
3029    return NULL;
3030  }
3031} while (true);
3032}
3033
3034//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3035
3036/// Check for comparisons of floating point operands using != and ==.
3037/// Issue a warning if these are no self-comparisons, as they are not likely
3038/// to do what the programmer intended.
3039void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3040  bool EmitWarning = true;
3041
3042  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3043  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3044
3045  // Special case: check for x == x (which is OK).
3046  // Do not emit warnings for such cases.
3047  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3048    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3049      if (DRL->getDecl() == DRR->getDecl())
3050        EmitWarning = false;
3051
3052
3053  // Special case: check for comparisons against literals that can be exactly
3054  //  represented by APFloat.  In such cases, do not emit a warning.  This
3055  //  is a heuristic: often comparison against such literals are used to
3056  //  detect if a value in a variable has not changed.  This clearly can
3057  //  lead to false negatives.
3058  if (EmitWarning) {
3059    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3060      if (FLL->isExact())
3061        EmitWarning = false;
3062    } else
3063      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
3064        if (FLR->isExact())
3065          EmitWarning = false;
3066    }
3067  }
3068
3069  // Check for comparisons with builtin types.
3070  if (EmitWarning)
3071    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3072      if (CL->isBuiltinCall())
3073        EmitWarning = false;
3074
3075  if (EmitWarning)
3076    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3077      if (CR->isBuiltinCall())
3078        EmitWarning = false;
3079
3080  // Emit the diagnostic.
3081  if (EmitWarning)
3082    Diag(Loc, diag::warn_floatingpoint_eq)
3083      << LHS->getSourceRange() << RHS->getSourceRange();
3084}
3085
3086//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3087//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3088
3089namespace {
3090
3091/// Structure recording the 'active' range of an integer-valued
3092/// expression.
3093struct IntRange {
3094  /// The number of bits active in the int.
3095  unsigned Width;
3096
3097  /// True if the int is known not to have negative values.
3098  bool NonNegative;
3099
3100  IntRange(unsigned Width, bool NonNegative)
3101    : Width(Width), NonNegative(NonNegative)
3102  {}
3103
3104  /// Returns the range of the bool type.
3105  static IntRange forBoolType() {
3106    return IntRange(1, true);
3107  }
3108
3109  /// Returns the range of an opaque value of the given integral type.
3110  static IntRange forValueOfType(ASTContext &C, QualType T) {
3111    return forValueOfCanonicalType(C,
3112                          T->getCanonicalTypeInternal().getTypePtr());
3113  }
3114
3115  /// Returns the range of an opaque value of a canonical integral type.
3116  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3117    assert(T->isCanonicalUnqualified());
3118
3119    if (const VectorType *VT = dyn_cast<VectorType>(T))
3120      T = VT->getElementType().getTypePtr();
3121    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3122      T = CT->getElementType().getTypePtr();
3123
3124    // For enum types, use the known bit width of the enumerators.
3125    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3126      EnumDecl *Enum = ET->getDecl();
3127      if (!Enum->isCompleteDefinition())
3128        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3129
3130      unsigned NumPositive = Enum->getNumPositiveBits();
3131      unsigned NumNegative = Enum->getNumNegativeBits();
3132
3133      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3134    }
3135
3136    const BuiltinType *BT = cast<BuiltinType>(T);
3137    assert(BT->isInteger());
3138
3139    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3140  }
3141
3142  /// Returns the "target" range of a canonical integral type, i.e.
3143  /// the range of values expressible in the type.
3144  ///
3145  /// This matches forValueOfCanonicalType except that enums have the
3146  /// full range of their type, not the range of their enumerators.
3147  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3148    assert(T->isCanonicalUnqualified());
3149
3150    if (const VectorType *VT = dyn_cast<VectorType>(T))
3151      T = VT->getElementType().getTypePtr();
3152    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3153      T = CT->getElementType().getTypePtr();
3154    if (const EnumType *ET = dyn_cast<EnumType>(T))
3155      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3156
3157    const BuiltinType *BT = cast<BuiltinType>(T);
3158    assert(BT->isInteger());
3159
3160    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3161  }
3162
3163  /// Returns the supremum of two ranges: i.e. their conservative merge.
3164  static IntRange join(IntRange L, IntRange R) {
3165    return IntRange(std::max(L.Width, R.Width),
3166                    L.NonNegative && R.NonNegative);
3167  }
3168
3169  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3170  static IntRange meet(IntRange L, IntRange R) {
3171    return IntRange(std::min(L.Width, R.Width),
3172                    L.NonNegative || R.NonNegative);
3173  }
3174};
3175
3176IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) {
3177  if (value.isSigned() && value.isNegative())
3178    return IntRange(value.getMinSignedBits(), false);
3179
3180  if (value.getBitWidth() > MaxWidth)
3181    value = value.trunc(MaxWidth);
3182
3183  // isNonNegative() just checks the sign bit without considering
3184  // signedness.
3185  return IntRange(value.getActiveBits(), true);
3186}
3187
3188IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3189                       unsigned MaxWidth) {
3190  if (result.isInt())
3191    return GetValueRange(C, result.getInt(), MaxWidth);
3192
3193  if (result.isVector()) {
3194    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3195    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3196      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3197      R = IntRange::join(R, El);
3198    }
3199    return R;
3200  }
3201
3202  if (result.isComplexInt()) {
3203    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3204    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3205    return IntRange::join(R, I);
3206  }
3207
3208  // This can happen with lossless casts to intptr_t of "based" lvalues.
3209  // Assume it might use arbitrary bits.
3210  // FIXME: The only reason we need to pass the type in here is to get
3211  // the sign right on this one case.  It would be nice if APValue
3212  // preserved this.
3213  assert(result.isLValue());
3214  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
3215}
3216
3217/// Pseudo-evaluate the given integer expression, estimating the
3218/// range of values it might take.
3219///
3220/// \param MaxWidth - the width to which the value will be truncated
3221IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
3222  E = E->IgnoreParens();
3223
3224  // Try a full evaluation first.
3225  Expr::EvalResult result;
3226  if (E->EvaluateAsRValue(result, C))
3227    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
3228
3229  // I think we only want to look through implicit casts here; if the
3230  // user has an explicit widening cast, we should treat the value as
3231  // being of the new, wider type.
3232  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
3233    if (CE->getCastKind() == CK_NoOp)
3234      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
3235
3236    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
3237
3238    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
3239
3240    // Assume that non-integer casts can span the full range of the type.
3241    if (!isIntegerCast)
3242      return OutputTypeRange;
3243
3244    IntRange SubRange
3245      = GetExprRange(C, CE->getSubExpr(),
3246                     std::min(MaxWidth, OutputTypeRange.Width));
3247
3248    // Bail out if the subexpr's range is as wide as the cast type.
3249    if (SubRange.Width >= OutputTypeRange.Width)
3250      return OutputTypeRange;
3251
3252    // Otherwise, we take the smaller width, and we're non-negative if
3253    // either the output type or the subexpr is.
3254    return IntRange(SubRange.Width,
3255                    SubRange.NonNegative || OutputTypeRange.NonNegative);
3256  }
3257
3258  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3259    // If we can fold the condition, just take that operand.
3260    bool CondResult;
3261    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
3262      return GetExprRange(C, CondResult ? CO->getTrueExpr()
3263                                        : CO->getFalseExpr(),
3264                          MaxWidth);
3265
3266    // Otherwise, conservatively merge.
3267    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
3268    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
3269    return IntRange::join(L, R);
3270  }
3271
3272  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3273    switch (BO->getOpcode()) {
3274
3275    // Boolean-valued operations are single-bit and positive.
3276    case BO_LAnd:
3277    case BO_LOr:
3278    case BO_LT:
3279    case BO_GT:
3280    case BO_LE:
3281    case BO_GE:
3282    case BO_EQ:
3283    case BO_NE:
3284      return IntRange::forBoolType();
3285
3286    // The type of the assignments is the type of the LHS, so the RHS
3287    // is not necessarily the same type.
3288    case BO_MulAssign:
3289    case BO_DivAssign:
3290    case BO_RemAssign:
3291    case BO_AddAssign:
3292    case BO_SubAssign:
3293    case BO_XorAssign:
3294    case BO_OrAssign:
3295      // TODO: bitfields?
3296      return IntRange::forValueOfType(C, E->getType());
3297
3298    // Simple assignments just pass through the RHS, which will have
3299    // been coerced to the LHS type.
3300    case BO_Assign:
3301      // TODO: bitfields?
3302      return GetExprRange(C, BO->getRHS(), MaxWidth);
3303
3304    // Operations with opaque sources are black-listed.
3305    case BO_PtrMemD:
3306    case BO_PtrMemI:
3307      return IntRange::forValueOfType(C, E->getType());
3308
3309    // Bitwise-and uses the *infinum* of the two source ranges.
3310    case BO_And:
3311    case BO_AndAssign:
3312      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
3313                            GetExprRange(C, BO->getRHS(), MaxWidth));
3314
3315    // Left shift gets black-listed based on a judgement call.
3316    case BO_Shl:
3317      // ...except that we want to treat '1 << (blah)' as logically
3318      // positive.  It's an important idiom.
3319      if (IntegerLiteral *I
3320            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
3321        if (I->getValue() == 1) {
3322          IntRange R = IntRange::forValueOfType(C, E->getType());
3323          return IntRange(R.Width, /*NonNegative*/ true);
3324        }
3325      }
3326      // fallthrough
3327
3328    case BO_ShlAssign:
3329      return IntRange::forValueOfType(C, E->getType());
3330
3331    // Right shift by a constant can narrow its left argument.
3332    case BO_Shr:
3333    case BO_ShrAssign: {
3334      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3335
3336      // If the shift amount is a positive constant, drop the width by
3337      // that much.
3338      llvm::APSInt shift;
3339      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
3340          shift.isNonNegative()) {
3341        unsigned zext = shift.getZExtValue();
3342        if (zext >= L.Width)
3343          L.Width = (L.NonNegative ? 0 : 1);
3344        else
3345          L.Width -= zext;
3346      }
3347
3348      return L;
3349    }
3350
3351    // Comma acts as its right operand.
3352    case BO_Comma:
3353      return GetExprRange(C, BO->getRHS(), MaxWidth);
3354
3355    // Black-list pointer subtractions.
3356    case BO_Sub:
3357      if (BO->getLHS()->getType()->isPointerType())
3358        return IntRange::forValueOfType(C, E->getType());
3359      break;
3360
3361    // The width of a division result is mostly determined by the size
3362    // of the LHS.
3363    case BO_Div: {
3364      // Don't 'pre-truncate' the operands.
3365      unsigned opWidth = C.getIntWidth(E->getType());
3366      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3367
3368      // If the divisor is constant, use that.
3369      llvm::APSInt divisor;
3370      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
3371        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
3372        if (log2 >= L.Width)
3373          L.Width = (L.NonNegative ? 0 : 1);
3374        else
3375          L.Width = std::min(L.Width - log2, MaxWidth);
3376        return L;
3377      }
3378
3379      // Otherwise, just use the LHS's width.
3380      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3381      return IntRange(L.Width, L.NonNegative && R.NonNegative);
3382    }
3383
3384    // The result of a remainder can't be larger than the result of
3385    // either side.
3386    case BO_Rem: {
3387      // Don't 'pre-truncate' the operands.
3388      unsigned opWidth = C.getIntWidth(E->getType());
3389      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3390      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3391
3392      IntRange meet = IntRange::meet(L, R);
3393      meet.Width = std::min(meet.Width, MaxWidth);
3394      return meet;
3395    }
3396
3397    // The default behavior is okay for these.
3398    case BO_Mul:
3399    case BO_Add:
3400    case BO_Xor:
3401    case BO_Or:
3402      break;
3403    }
3404
3405    // The default case is to treat the operation as if it were closed
3406    // on the narrowest type that encompasses both operands.
3407    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3408    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
3409    return IntRange::join(L, R);
3410  }
3411
3412  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
3413    switch (UO->getOpcode()) {
3414    // Boolean-valued operations are white-listed.
3415    case UO_LNot:
3416      return IntRange::forBoolType();
3417
3418    // Operations with opaque sources are black-listed.
3419    case UO_Deref:
3420    case UO_AddrOf: // should be impossible
3421      return IntRange::forValueOfType(C, E->getType());
3422
3423    default:
3424      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
3425    }
3426  }
3427
3428  if (dyn_cast<OffsetOfExpr>(E)) {
3429    IntRange::forValueOfType(C, E->getType());
3430  }
3431
3432  if (FieldDecl *BitField = E->getBitField())
3433    return IntRange(BitField->getBitWidthValue(C),
3434                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
3435
3436  return IntRange::forValueOfType(C, E->getType());
3437}
3438
3439IntRange GetExprRange(ASTContext &C, Expr *E) {
3440  return GetExprRange(C, E, C.getIntWidth(E->getType()));
3441}
3442
3443/// Checks whether the given value, which currently has the given
3444/// source semantics, has the same value when coerced through the
3445/// target semantics.
3446bool IsSameFloatAfterCast(const llvm::APFloat &value,
3447                          const llvm::fltSemantics &Src,
3448                          const llvm::fltSemantics &Tgt) {
3449  llvm::APFloat truncated = value;
3450
3451  bool ignored;
3452  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
3453  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
3454
3455  return truncated.bitwiseIsEqual(value);
3456}
3457
3458/// Checks whether the given value, which currently has the given
3459/// source semantics, has the same value when coerced through the
3460/// target semantics.
3461///
3462/// The value might be a vector of floats (or a complex number).
3463bool IsSameFloatAfterCast(const APValue &value,
3464                          const llvm::fltSemantics &Src,
3465                          const llvm::fltSemantics &Tgt) {
3466  if (value.isFloat())
3467    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
3468
3469  if (value.isVector()) {
3470    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
3471      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
3472        return false;
3473    return true;
3474  }
3475
3476  assert(value.isComplexFloat());
3477  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
3478          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
3479}
3480
3481void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
3482
3483static bool IsZero(Sema &S, Expr *E) {
3484  // Suppress cases where we are comparing against an enum constant.
3485  if (const DeclRefExpr *DR =
3486      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
3487    if (isa<EnumConstantDecl>(DR->getDecl()))
3488      return false;
3489
3490  // Suppress cases where the '0' value is expanded from a macro.
3491  if (E->getLocStart().isMacroID())
3492    return false;
3493
3494  llvm::APSInt Value;
3495  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
3496}
3497
3498static bool HasEnumType(Expr *E) {
3499  // Strip off implicit integral promotions.
3500  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
3501    if (ICE->getCastKind() != CK_IntegralCast &&
3502        ICE->getCastKind() != CK_NoOp)
3503      break;
3504    E = ICE->getSubExpr();
3505  }
3506
3507  return E->getType()->isEnumeralType();
3508}
3509
3510void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
3511  BinaryOperatorKind op = E->getOpcode();
3512  if (E->isValueDependent())
3513    return;
3514
3515  if (op == BO_LT && IsZero(S, E->getRHS())) {
3516    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3517      << "< 0" << "false" << HasEnumType(E->getLHS())
3518      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3519  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
3520    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3521      << ">= 0" << "true" << HasEnumType(E->getLHS())
3522      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3523  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
3524    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3525      << "0 >" << "false" << HasEnumType(E->getRHS())
3526      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3527  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
3528    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3529      << "0 <=" << "true" << HasEnumType(E->getRHS())
3530      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3531  }
3532}
3533
3534/// Analyze the operands of the given comparison.  Implements the
3535/// fallback case from AnalyzeComparison.
3536void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
3537  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3538  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3539}
3540
3541/// \brief Implements -Wsign-compare.
3542///
3543/// \param E the binary operator to check for warnings
3544void AnalyzeComparison(Sema &S, BinaryOperator *E) {
3545  // The type the comparison is being performed in.
3546  QualType T = E->getLHS()->getType();
3547  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
3548         && "comparison with mismatched types");
3549
3550  // We don't do anything special if this isn't an unsigned integral
3551  // comparison:  we're only interested in integral comparisons, and
3552  // signed comparisons only happen in cases we don't care to warn about.
3553  //
3554  // We also don't care about value-dependent expressions or expressions
3555  // whose result is a constant.
3556  if (!T->hasUnsignedIntegerRepresentation()
3557      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
3558    return AnalyzeImpConvsInComparison(S, E);
3559
3560  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
3561  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
3562
3563  // Check to see if one of the (unmodified) operands is of different
3564  // signedness.
3565  Expr *signedOperand, *unsignedOperand;
3566  if (LHS->getType()->hasSignedIntegerRepresentation()) {
3567    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
3568           "unsigned comparison between two signed integer expressions?");
3569    signedOperand = LHS;
3570    unsignedOperand = RHS;
3571  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
3572    signedOperand = RHS;
3573    unsignedOperand = LHS;
3574  } else {
3575    CheckTrivialUnsignedComparison(S, E);
3576    return AnalyzeImpConvsInComparison(S, E);
3577  }
3578
3579  // Otherwise, calculate the effective range of the signed operand.
3580  IntRange signedRange = GetExprRange(S.Context, signedOperand);
3581
3582  // Go ahead and analyze implicit conversions in the operands.  Note
3583  // that we skip the implicit conversions on both sides.
3584  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
3585  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
3586
3587  // If the signed range is non-negative, -Wsign-compare won't fire,
3588  // but we should still check for comparisons which are always true
3589  // or false.
3590  if (signedRange.NonNegative)
3591    return CheckTrivialUnsignedComparison(S, E);
3592
3593  // For (in)equality comparisons, if the unsigned operand is a
3594  // constant which cannot collide with a overflowed signed operand,
3595  // then reinterpreting the signed operand as unsigned will not
3596  // change the result of the comparison.
3597  if (E->isEqualityOp()) {
3598    unsigned comparisonWidth = S.Context.getIntWidth(T);
3599    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
3600
3601    // We should never be unable to prove that the unsigned operand is
3602    // non-negative.
3603    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
3604
3605    if (unsignedRange.Width < comparisonWidth)
3606      return;
3607  }
3608
3609  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
3610    << LHS->getType() << RHS->getType()
3611    << LHS->getSourceRange() << RHS->getSourceRange();
3612}
3613
3614/// Analyzes an attempt to assign the given value to a bitfield.
3615///
3616/// Returns true if there was something fishy about the attempt.
3617bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
3618                               SourceLocation InitLoc) {
3619  assert(Bitfield->isBitField());
3620  if (Bitfield->isInvalidDecl())
3621    return false;
3622
3623  // White-list bool bitfields.
3624  if (Bitfield->getType()->isBooleanType())
3625    return false;
3626
3627  // Ignore value- or type-dependent expressions.
3628  if (Bitfield->getBitWidth()->isValueDependent() ||
3629      Bitfield->getBitWidth()->isTypeDependent() ||
3630      Init->isValueDependent() ||
3631      Init->isTypeDependent())
3632    return false;
3633
3634  Expr *OriginalInit = Init->IgnoreParenImpCasts();
3635
3636  Expr::EvalResult InitValue;
3637  if (!OriginalInit->EvaluateAsRValue(InitValue, S.Context) ||
3638      !InitValue.Val.isInt())
3639    return false;
3640
3641  const llvm::APSInt &Value = InitValue.Val.getInt();
3642  unsigned OriginalWidth = Value.getBitWidth();
3643  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
3644
3645  if (OriginalWidth <= FieldWidth)
3646    return false;
3647
3648  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
3649
3650  // It's fairly common to write values into signed bitfields
3651  // that, if sign-extended, would end up becoming a different
3652  // value.  We don't want to warn about that.
3653  if (Value.isSigned() && Value.isNegative())
3654    TruncatedValue = TruncatedValue.sext(OriginalWidth);
3655  else
3656    TruncatedValue = TruncatedValue.zext(OriginalWidth);
3657
3658  if (Value == TruncatedValue)
3659    return false;
3660
3661  std::string PrettyValue = Value.toString(10);
3662  std::string PrettyTrunc = TruncatedValue.toString(10);
3663
3664  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
3665    << PrettyValue << PrettyTrunc << OriginalInit->getType()
3666    << Init->getSourceRange();
3667
3668  return true;
3669}
3670
3671/// Analyze the given simple or compound assignment for warning-worthy
3672/// operations.
3673void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
3674  // Just recurse on the LHS.
3675  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3676
3677  // We want to recurse on the RHS as normal unless we're assigning to
3678  // a bitfield.
3679  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
3680    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
3681                                  E->getOperatorLoc())) {
3682      // Recurse, ignoring any implicit conversions on the RHS.
3683      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
3684                                        E->getOperatorLoc());
3685    }
3686  }
3687
3688  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3689}
3690
3691/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3692void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
3693                     SourceLocation CContext, unsigned diag) {
3694  S.Diag(E->getExprLoc(), diag)
3695    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
3696}
3697
3698/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
3699void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext,
3700                     unsigned diag) {
3701  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag);
3702}
3703
3704/// Diagnose an implicit cast from a literal expression. Does not warn when the
3705/// cast wouldn't lose information.
3706void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
3707                                    SourceLocation CContext) {
3708  // Try to convert the literal exactly to an integer. If we can, don't warn.
3709  bool isExact = false;
3710  const llvm::APFloat &Value = FL->getValue();
3711  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
3712                            T->hasUnsignedIntegerRepresentation());
3713  if (Value.convertToInteger(IntegerValue,
3714                             llvm::APFloat::rmTowardZero, &isExact)
3715      == llvm::APFloat::opOK && isExact)
3716    return;
3717
3718  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
3719    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
3720}
3721
3722std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
3723  if (!Range.Width) return "0";
3724
3725  llvm::APSInt ValueInRange = Value;
3726  ValueInRange.setIsSigned(!Range.NonNegative);
3727  ValueInRange = ValueInRange.trunc(Range.Width);
3728  return ValueInRange.toString(10);
3729}
3730
3731static bool isFromSystemMacro(Sema &S, SourceLocation loc) {
3732  SourceManager &smgr = S.Context.getSourceManager();
3733  return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc));
3734}
3735
3736void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
3737                             SourceLocation CC, bool *ICContext = 0) {
3738  if (E->isTypeDependent() || E->isValueDependent()) return;
3739
3740  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
3741  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
3742  if (Source == Target) return;
3743  if (Target->isDependentType()) return;
3744
3745  // If the conversion context location is invalid don't complain. We also
3746  // don't want to emit a warning if the issue occurs from the expansion of
3747  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
3748  // delay this check as long as possible. Once we detect we are in that
3749  // scenario, we just return.
3750  if (CC.isInvalid())
3751    return;
3752
3753  // Diagnose implicit casts to bool.
3754  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
3755    if (isa<StringLiteral>(E))
3756      // Warn on string literal to bool.  Checks for string literals in logical
3757      // expressions, for instances, assert(0 && "error here"), is prevented
3758      // by a check in AnalyzeImplicitConversions().
3759      return DiagnoseImpCast(S, E, T, CC,
3760                             diag::warn_impcast_string_literal_to_bool);
3761    return; // Other casts to bool are not checked.
3762  }
3763
3764  // Strip vector types.
3765  if (isa<VectorType>(Source)) {
3766    if (!isa<VectorType>(Target)) {
3767      if (isFromSystemMacro(S, CC))
3768        return;
3769      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
3770    }
3771
3772    // If the vector cast is cast between two vectors of the same size, it is
3773    // a bitcast, not a conversion.
3774    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
3775      return;
3776
3777    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
3778    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
3779  }
3780
3781  // Strip complex types.
3782  if (isa<ComplexType>(Source)) {
3783    if (!isa<ComplexType>(Target)) {
3784      if (isFromSystemMacro(S, CC))
3785        return;
3786
3787      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
3788    }
3789
3790    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
3791    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
3792  }
3793
3794  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
3795  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
3796
3797  // If the source is floating point...
3798  if (SourceBT && SourceBT->isFloatingPoint()) {
3799    // ...and the target is floating point...
3800    if (TargetBT && TargetBT->isFloatingPoint()) {
3801      // ...then warn if we're dropping FP rank.
3802
3803      // Builtin FP kinds are ordered by increasing FP rank.
3804      if (SourceBT->getKind() > TargetBT->getKind()) {
3805        // Don't warn about float constants that are precisely
3806        // representable in the target type.
3807        Expr::EvalResult result;
3808        if (E->EvaluateAsRValue(result, S.Context)) {
3809          // Value might be a float, a float vector, or a float complex.
3810          if (IsSameFloatAfterCast(result.Val,
3811                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
3812                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
3813            return;
3814        }
3815
3816        if (isFromSystemMacro(S, CC))
3817          return;
3818
3819        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
3820      }
3821      return;
3822    }
3823
3824    // If the target is integral, always warn.
3825    if ((TargetBT && TargetBT->isInteger())) {
3826      if (isFromSystemMacro(S, CC))
3827        return;
3828
3829      Expr *InnerE = E->IgnoreParenImpCasts();
3830      // We also want to warn on, e.g., "int i = -1.234"
3831      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
3832        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
3833          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
3834
3835      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
3836        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
3837      } else {
3838        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
3839      }
3840    }
3841
3842    return;
3843  }
3844
3845  if (!Source->isIntegerType() || !Target->isIntegerType())
3846    return;
3847
3848  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
3849           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
3850    S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer)
3851        << E->getSourceRange() << clang::SourceRange(CC);
3852    return;
3853  }
3854
3855  IntRange SourceRange = GetExprRange(S.Context, E);
3856  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
3857
3858  if (SourceRange.Width > TargetRange.Width) {
3859    // If the source is a constant, use a default-on diagnostic.
3860    // TODO: this should happen for bitfield stores, too.
3861    llvm::APSInt Value(32);
3862    if (E->isIntegerConstantExpr(Value, S.Context)) {
3863      if (isFromSystemMacro(S, CC))
3864        return;
3865
3866      std::string PrettySourceValue = Value.toString(10);
3867      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
3868
3869      S.DiagRuntimeBehavior(E->getExprLoc(), E,
3870        S.PDiag(diag::warn_impcast_integer_precision_constant)
3871            << PrettySourceValue << PrettyTargetValue
3872            << E->getType() << T << E->getSourceRange()
3873            << clang::SourceRange(CC));
3874      return;
3875    }
3876
3877    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
3878    if (isFromSystemMacro(S, CC))
3879      return;
3880
3881    if (SourceRange.Width == 64 && TargetRange.Width == 32)
3882      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32);
3883    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
3884  }
3885
3886  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
3887      (!TargetRange.NonNegative && SourceRange.NonNegative &&
3888       SourceRange.Width == TargetRange.Width)) {
3889
3890    if (isFromSystemMacro(S, CC))
3891      return;
3892
3893    unsigned DiagID = diag::warn_impcast_integer_sign;
3894
3895    // Traditionally, gcc has warned about this under -Wsign-compare.
3896    // We also want to warn about it in -Wconversion.
3897    // So if -Wconversion is off, use a completely identical diagnostic
3898    // in the sign-compare group.
3899    // The conditional-checking code will
3900    if (ICContext) {
3901      DiagID = diag::warn_impcast_integer_sign_conditional;
3902      *ICContext = true;
3903    }
3904
3905    return DiagnoseImpCast(S, E, T, CC, DiagID);
3906  }
3907
3908  // Diagnose conversions between different enumeration types.
3909  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
3910  // type, to give us better diagnostics.
3911  QualType SourceType = E->getType();
3912  if (!S.getLangOptions().CPlusPlus) {
3913    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
3914      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
3915        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
3916        SourceType = S.Context.getTypeDeclType(Enum);
3917        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
3918      }
3919  }
3920
3921  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
3922    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
3923      if ((SourceEnum->getDecl()->getIdentifier() ||
3924           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
3925          (TargetEnum->getDecl()->getIdentifier() ||
3926           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
3927          SourceEnum != TargetEnum) {
3928        if (isFromSystemMacro(S, CC))
3929          return;
3930
3931        return DiagnoseImpCast(S, E, SourceType, T, CC,
3932                               diag::warn_impcast_different_enum_types);
3933      }
3934
3935  return;
3936}
3937
3938void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
3939
3940void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
3941                             SourceLocation CC, bool &ICContext) {
3942  E = E->IgnoreParenImpCasts();
3943
3944  if (isa<ConditionalOperator>(E))
3945    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
3946
3947  AnalyzeImplicitConversions(S, E, CC);
3948  if (E->getType() != T)
3949    return CheckImplicitConversion(S, E, T, CC, &ICContext);
3950  return;
3951}
3952
3953void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
3954  SourceLocation CC = E->getQuestionLoc();
3955
3956  AnalyzeImplicitConversions(S, E->getCond(), CC);
3957
3958  bool Suspicious = false;
3959  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
3960  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
3961
3962  // If -Wconversion would have warned about either of the candidates
3963  // for a signedness conversion to the context type...
3964  if (!Suspicious) return;
3965
3966  // ...but it's currently ignored...
3967  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
3968                                 CC))
3969    return;
3970
3971  // ...then check whether it would have warned about either of the
3972  // candidates for a signedness conversion to the condition type.
3973  if (E->getType() == T) return;
3974
3975  Suspicious = false;
3976  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
3977                          E->getType(), CC, &Suspicious);
3978  if (!Suspicious)
3979    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
3980                            E->getType(), CC, &Suspicious);
3981}
3982
3983/// AnalyzeImplicitConversions - Find and report any interesting
3984/// implicit conversions in the given expression.  There are a couple
3985/// of competing diagnostics here, -Wconversion and -Wsign-compare.
3986void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
3987  QualType T = OrigE->getType();
3988  Expr *E = OrigE->IgnoreParenImpCasts();
3989
3990  if (E->isTypeDependent() || E->isValueDependent())
3991    return;
3992
3993  // For conditional operators, we analyze the arguments as if they
3994  // were being fed directly into the output.
3995  if (isa<ConditionalOperator>(E)) {
3996    ConditionalOperator *CO = cast<ConditionalOperator>(E);
3997    CheckConditionalOperator(S, CO, T);
3998    return;
3999  }
4000
4001  // Go ahead and check any implicit conversions we might have skipped.
4002  // The non-canonical typecheck is just an optimization;
4003  // CheckImplicitConversion will filter out dead implicit conversions.
4004  if (E->getType() != T)
4005    CheckImplicitConversion(S, E, T, CC);
4006
4007  // Now continue drilling into this expression.
4008
4009  // Skip past explicit casts.
4010  if (isa<ExplicitCastExpr>(E)) {
4011    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4012    return AnalyzeImplicitConversions(S, E, CC);
4013  }
4014
4015  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4016    // Do a somewhat different check with comparison operators.
4017    if (BO->isComparisonOp())
4018      return AnalyzeComparison(S, BO);
4019
4020    // And with assignments and compound assignments.
4021    if (BO->isAssignmentOp())
4022      return AnalyzeAssignment(S, BO);
4023  }
4024
4025  // These break the otherwise-useful invariant below.  Fortunately,
4026  // we don't really need to recurse into them, because any internal
4027  // expressions should have been analyzed already when they were
4028  // built into statements.
4029  if (isa<StmtExpr>(E)) return;
4030
4031  // Don't descend into unevaluated contexts.
4032  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
4033
4034  // Now just recurse over the expression's children.
4035  CC = E->getExprLoc();
4036  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
4037  bool IsLogicalOperator = BO && BO->isLogicalOp();
4038  for (Stmt::child_range I = E->children(); I; ++I) {
4039    Expr *ChildExpr = cast<Expr>(*I);
4040    if (IsLogicalOperator &&
4041        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
4042      // Ignore checking string literals that are in logical operators.
4043      continue;
4044    AnalyzeImplicitConversions(S, ChildExpr, CC);
4045  }
4046}
4047
4048} // end anonymous namespace
4049
4050/// Diagnoses "dangerous" implicit conversions within the given
4051/// expression (which is a full expression).  Implements -Wconversion
4052/// and -Wsign-compare.
4053///
4054/// \param CC the "context" location of the implicit conversion, i.e.
4055///   the most location of the syntactic entity requiring the implicit
4056///   conversion
4057void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
4058  // Don't diagnose in unevaluated contexts.
4059  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
4060    return;
4061
4062  // Don't diagnose for value- or type-dependent expressions.
4063  if (E->isTypeDependent() || E->isValueDependent())
4064    return;
4065
4066  // Check for array bounds violations in cases where the check isn't triggered
4067  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
4068  // ArraySubscriptExpr is on the RHS of a variable initialization.
4069  CheckArrayAccess(E);
4070
4071  // This is not the right CC for (e.g.) a variable initialization.
4072  AnalyzeImplicitConversions(*this, E, CC);
4073}
4074
4075void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
4076                                       FieldDecl *BitField,
4077                                       Expr *Init) {
4078  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
4079}
4080
4081/// CheckParmsForFunctionDef - Check that the parameters of the given
4082/// function are appropriate for the definition of a function. This
4083/// takes care of any checks that cannot be performed on the
4084/// declaration itself, e.g., that the types of each of the function
4085/// parameters are complete.
4086bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
4087                                    bool CheckParameterNames) {
4088  bool HasInvalidParm = false;
4089  for (; P != PEnd; ++P) {
4090    ParmVarDecl *Param = *P;
4091
4092    // C99 6.7.5.3p4: the parameters in a parameter type list in a
4093    // function declarator that is part of a function definition of
4094    // that function shall not have incomplete type.
4095    //
4096    // This is also C++ [dcl.fct]p6.
4097    if (!Param->isInvalidDecl() &&
4098        RequireCompleteType(Param->getLocation(), Param->getType(),
4099                               diag::err_typecheck_decl_incomplete_type)) {
4100      Param->setInvalidDecl();
4101      HasInvalidParm = true;
4102    }
4103
4104    // C99 6.9.1p5: If the declarator includes a parameter type list, the
4105    // declaration of each parameter shall include an identifier.
4106    if (CheckParameterNames &&
4107        Param->getIdentifier() == 0 &&
4108        !Param->isImplicit() &&
4109        !getLangOptions().CPlusPlus)
4110      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
4111
4112    // C99 6.7.5.3p12:
4113    //   If the function declarator is not part of a definition of that
4114    //   function, parameters may have incomplete type and may use the [*]
4115    //   notation in their sequences of declarator specifiers to specify
4116    //   variable length array types.
4117    QualType PType = Param->getOriginalType();
4118    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
4119      if (AT->getSizeModifier() == ArrayType::Star) {
4120        // FIXME: This diagnosic should point the the '[*]' if source-location
4121        // information is added for it.
4122        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
4123      }
4124    }
4125  }
4126
4127  return HasInvalidParm;
4128}
4129
4130/// CheckCastAlign - Implements -Wcast-align, which warns when a
4131/// pointer cast increases the alignment requirements.
4132void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
4133  // This is actually a lot of work to potentially be doing on every
4134  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
4135  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
4136                                          TRange.getBegin())
4137        == DiagnosticsEngine::Ignored)
4138    return;
4139
4140  // Ignore dependent types.
4141  if (T->isDependentType() || Op->getType()->isDependentType())
4142    return;
4143
4144  // Require that the destination be a pointer type.
4145  const PointerType *DestPtr = T->getAs<PointerType>();
4146  if (!DestPtr) return;
4147
4148  // If the destination has alignment 1, we're done.
4149  QualType DestPointee = DestPtr->getPointeeType();
4150  if (DestPointee->isIncompleteType()) return;
4151  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
4152  if (DestAlign.isOne()) return;
4153
4154  // Require that the source be a pointer type.
4155  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
4156  if (!SrcPtr) return;
4157  QualType SrcPointee = SrcPtr->getPointeeType();
4158
4159  // Whitelist casts from cv void*.  We already implicitly
4160  // whitelisted casts to cv void*, since they have alignment 1.
4161  // Also whitelist casts involving incomplete types, which implicitly
4162  // includes 'void'.
4163  if (SrcPointee->isIncompleteType()) return;
4164
4165  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
4166  if (SrcAlign >= DestAlign) return;
4167
4168  Diag(TRange.getBegin(), diag::warn_cast_align)
4169    << Op->getType() << T
4170    << static_cast<unsigned>(SrcAlign.getQuantity())
4171    << static_cast<unsigned>(DestAlign.getQuantity())
4172    << TRange << Op->getSourceRange();
4173}
4174
4175static const Type* getElementType(const Expr *BaseExpr) {
4176  const Type* EltType = BaseExpr->getType().getTypePtr();
4177  if (EltType->isAnyPointerType())
4178    return EltType->getPointeeType().getTypePtr();
4179  else if (EltType->isArrayType())
4180    return EltType->getBaseElementTypeUnsafe();
4181  return EltType;
4182}
4183
4184/// \brief Check whether this array fits the idiom of a size-one tail padded
4185/// array member of a struct.
4186///
4187/// We avoid emitting out-of-bounds access warnings for such arrays as they are
4188/// commonly used to emulate flexible arrays in C89 code.
4189static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
4190                                    const NamedDecl *ND) {
4191  if (Size != 1 || !ND) return false;
4192
4193  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
4194  if (!FD) return false;
4195
4196  // Don't consider sizes resulting from macro expansions or template argument
4197  // substitution to form C89 tail-padded arrays.
4198  ConstantArrayTypeLoc TL =
4199    cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc());
4200  const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr());
4201  if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
4202    return false;
4203
4204  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
4205  if (!RD) return false;
4206  if (RD->isUnion()) return false;
4207  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
4208    if (!CRD->isStandardLayout()) return false;
4209  }
4210
4211  // See if this is the last field decl in the record.
4212  const Decl *D = FD;
4213  while ((D = D->getNextDeclInContext()))
4214    if (isa<FieldDecl>(D))
4215      return false;
4216  return true;
4217}
4218
4219void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
4220                            bool isSubscript, bool AllowOnePastEnd) {
4221  const Type* EffectiveType = getElementType(BaseExpr);
4222  BaseExpr = BaseExpr->IgnoreParenCasts();
4223  IndexExpr = IndexExpr->IgnoreParenCasts();
4224
4225  const ConstantArrayType *ArrayTy =
4226    Context.getAsConstantArrayType(BaseExpr->getType());
4227  if (!ArrayTy)
4228    return;
4229
4230  if (IndexExpr->isValueDependent())
4231    return;
4232  llvm::APSInt index;
4233  if (!IndexExpr->isIntegerConstantExpr(index, Context))
4234    return;
4235
4236  const NamedDecl *ND = NULL;
4237  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4238    ND = dyn_cast<NamedDecl>(DRE->getDecl());
4239  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4240    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4241
4242  if (index.isUnsigned() || !index.isNegative()) {
4243    llvm::APInt size = ArrayTy->getSize();
4244    if (!size.isStrictlyPositive())
4245      return;
4246
4247    const Type* BaseType = getElementType(BaseExpr);
4248    if (BaseType != EffectiveType) {
4249      // Make sure we're comparing apples to apples when comparing index to size
4250      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
4251      uint64_t array_typesize = Context.getTypeSize(BaseType);
4252      // Handle ptrarith_typesize being zero, such as when casting to void*
4253      if (!ptrarith_typesize) ptrarith_typesize = 1;
4254      if (ptrarith_typesize != array_typesize) {
4255        // There's a cast to a different size type involved
4256        uint64_t ratio = array_typesize / ptrarith_typesize;
4257        // TODO: Be smarter about handling cases where array_typesize is not a
4258        // multiple of ptrarith_typesize
4259        if (ptrarith_typesize * ratio == array_typesize)
4260          size *= llvm::APInt(size.getBitWidth(), ratio);
4261      }
4262    }
4263
4264    if (size.getBitWidth() > index.getBitWidth())
4265      index = index.sext(size.getBitWidth());
4266    else if (size.getBitWidth() < index.getBitWidth())
4267      size = size.sext(index.getBitWidth());
4268
4269    // For array subscripting the index must be less than size, but for pointer
4270    // arithmetic also allow the index (offset) to be equal to size since
4271    // computing the next address after the end of the array is legal and
4272    // commonly done e.g. in C++ iterators and range-based for loops.
4273    if (AllowOnePastEnd ? index.sle(size) : index.slt(size))
4274      return;
4275
4276    // Also don't warn for arrays of size 1 which are members of some
4277    // structure. These are often used to approximate flexible arrays in C89
4278    // code.
4279    if (IsTailPaddedMemberArray(*this, size, ND))
4280      return;
4281
4282    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
4283    if (isSubscript)
4284      DiagID = diag::warn_array_index_exceeds_bounds;
4285
4286    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4287                        PDiag(DiagID) << index.toString(10, true)
4288                          << size.toString(10, true)
4289                          << (unsigned)size.getLimitedValue(~0U)
4290                          << IndexExpr->getSourceRange());
4291  } else {
4292    unsigned DiagID = diag::warn_array_index_precedes_bounds;
4293    if (!isSubscript) {
4294      DiagID = diag::warn_ptr_arith_precedes_bounds;
4295      if (index.isNegative()) index = -index;
4296    }
4297
4298    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4299                        PDiag(DiagID) << index.toString(10, true)
4300                          << IndexExpr->getSourceRange());
4301  }
4302
4303  if (!ND) {
4304    // Try harder to find a NamedDecl to point at in the note.
4305    while (const ArraySubscriptExpr *ASE =
4306           dyn_cast<ArraySubscriptExpr>(BaseExpr))
4307      BaseExpr = ASE->getBase()->IgnoreParenCasts();
4308    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4309      ND = dyn_cast<NamedDecl>(DRE->getDecl());
4310    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4311      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4312  }
4313
4314  if (ND)
4315    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
4316                        PDiag(diag::note_array_index_out_of_bounds)
4317                          << ND->getDeclName());
4318}
4319
4320void Sema::CheckArrayAccess(const Expr *expr) {
4321  int AllowOnePastEnd = 0;
4322  while (expr) {
4323    expr = expr->IgnoreParenImpCasts();
4324    switch (expr->getStmtClass()) {
4325      case Stmt::ArraySubscriptExprClass: {
4326        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
4327        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), true,
4328                         AllowOnePastEnd > 0);
4329        return;
4330      }
4331      case Stmt::UnaryOperatorClass: {
4332        // Only unwrap the * and & unary operators
4333        const UnaryOperator *UO = cast<UnaryOperator>(expr);
4334        expr = UO->getSubExpr();
4335        switch (UO->getOpcode()) {
4336          case UO_AddrOf:
4337            AllowOnePastEnd++;
4338            break;
4339          case UO_Deref:
4340            AllowOnePastEnd--;
4341            break;
4342          default:
4343            return;
4344        }
4345        break;
4346      }
4347      case Stmt::ConditionalOperatorClass: {
4348        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
4349        if (const Expr *lhs = cond->getLHS())
4350          CheckArrayAccess(lhs);
4351        if (const Expr *rhs = cond->getRHS())
4352          CheckArrayAccess(rhs);
4353        return;
4354      }
4355      default:
4356        return;
4357    }
4358  }
4359}
4360
4361//===--- CHECK: Objective-C retain cycles ----------------------------------//
4362
4363namespace {
4364  struct RetainCycleOwner {
4365    RetainCycleOwner() : Variable(0), Indirect(false) {}
4366    VarDecl *Variable;
4367    SourceRange Range;
4368    SourceLocation Loc;
4369    bool Indirect;
4370
4371    void setLocsFrom(Expr *e) {
4372      Loc = e->getExprLoc();
4373      Range = e->getSourceRange();
4374    }
4375  };
4376}
4377
4378/// Consider whether capturing the given variable can possibly lead to
4379/// a retain cycle.
4380static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
4381  // In ARC, it's captured strongly iff the variable has __strong
4382  // lifetime.  In MRR, it's captured strongly if the variable is
4383  // __block and has an appropriate type.
4384  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4385    return false;
4386
4387  owner.Variable = var;
4388  owner.setLocsFrom(ref);
4389  return true;
4390}
4391
4392static bool findRetainCycleOwner(Expr *e, RetainCycleOwner &owner) {
4393  while (true) {
4394    e = e->IgnoreParens();
4395    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
4396      switch (cast->getCastKind()) {
4397      case CK_BitCast:
4398      case CK_LValueBitCast:
4399      case CK_LValueToRValue:
4400      case CK_ARCReclaimReturnedObject:
4401        e = cast->getSubExpr();
4402        continue;
4403
4404      default:
4405        return false;
4406      }
4407    }
4408
4409    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
4410      ObjCIvarDecl *ivar = ref->getDecl();
4411      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4412        return false;
4413
4414      // Try to find a retain cycle in the base.
4415      if (!findRetainCycleOwner(ref->getBase(), owner))
4416        return false;
4417
4418      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
4419      owner.Indirect = true;
4420      return true;
4421    }
4422
4423    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
4424      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
4425      if (!var) return false;
4426      return considerVariable(var, ref, owner);
4427    }
4428
4429    if (BlockDeclRefExpr *ref = dyn_cast<BlockDeclRefExpr>(e)) {
4430      owner.Variable = ref->getDecl();
4431      owner.setLocsFrom(ref);
4432      return true;
4433    }
4434
4435    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
4436      if (member->isArrow()) return false;
4437
4438      // Don't count this as an indirect ownership.
4439      e = member->getBase();
4440      continue;
4441    }
4442
4443    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
4444      // Only pay attention to pseudo-objects on property references.
4445      ObjCPropertyRefExpr *pre
4446        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
4447                                              ->IgnoreParens());
4448      if (!pre) return false;
4449      if (pre->isImplicitProperty()) return false;
4450      ObjCPropertyDecl *property = pre->getExplicitProperty();
4451      if (!property->isRetaining() &&
4452          !(property->getPropertyIvarDecl() &&
4453            property->getPropertyIvarDecl()->getType()
4454              .getObjCLifetime() == Qualifiers::OCL_Strong))
4455          return false;
4456
4457      owner.Indirect = true;
4458      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
4459                              ->getSourceExpr());
4460      continue;
4461    }
4462
4463    // Array ivars?
4464
4465    return false;
4466  }
4467}
4468
4469namespace {
4470  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
4471    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
4472      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
4473        Variable(variable), Capturer(0) {}
4474
4475    VarDecl *Variable;
4476    Expr *Capturer;
4477
4478    void VisitDeclRefExpr(DeclRefExpr *ref) {
4479      if (ref->getDecl() == Variable && !Capturer)
4480        Capturer = ref;
4481    }
4482
4483    void VisitBlockDeclRefExpr(BlockDeclRefExpr *ref) {
4484      if (ref->getDecl() == Variable && !Capturer)
4485        Capturer = ref;
4486    }
4487
4488    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
4489      if (Capturer) return;
4490      Visit(ref->getBase());
4491      if (Capturer && ref->isFreeIvar())
4492        Capturer = ref;
4493    }
4494
4495    void VisitBlockExpr(BlockExpr *block) {
4496      // Look inside nested blocks
4497      if (block->getBlockDecl()->capturesVariable(Variable))
4498        Visit(block->getBlockDecl()->getBody());
4499    }
4500  };
4501}
4502
4503/// Check whether the given argument is a block which captures a
4504/// variable.
4505static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
4506  assert(owner.Variable && owner.Loc.isValid());
4507
4508  e = e->IgnoreParenCasts();
4509  BlockExpr *block = dyn_cast<BlockExpr>(e);
4510  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
4511    return 0;
4512
4513  FindCaptureVisitor visitor(S.Context, owner.Variable);
4514  visitor.Visit(block->getBlockDecl()->getBody());
4515  return visitor.Capturer;
4516}
4517
4518static void diagnoseRetainCycle(Sema &S, Expr *capturer,
4519                                RetainCycleOwner &owner) {
4520  assert(capturer);
4521  assert(owner.Variable && owner.Loc.isValid());
4522
4523  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
4524    << owner.Variable << capturer->getSourceRange();
4525  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
4526    << owner.Indirect << owner.Range;
4527}
4528
4529/// Check for a keyword selector that starts with the word 'add' or
4530/// 'set'.
4531static bool isSetterLikeSelector(Selector sel) {
4532  if (sel.isUnarySelector()) return false;
4533
4534  StringRef str = sel.getNameForSlot(0);
4535  while (!str.empty() && str.front() == '_') str = str.substr(1);
4536  if (str.startswith("set"))
4537    str = str.substr(3);
4538  else if (str.startswith("add")) {
4539    // Specially whitelist 'addOperationWithBlock:'.
4540    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
4541      return false;
4542    str = str.substr(3);
4543  }
4544  else
4545    return false;
4546
4547  if (str.empty()) return true;
4548  return !islower(str.front());
4549}
4550
4551/// Check a message send to see if it's likely to cause a retain cycle.
4552void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
4553  // Only check instance methods whose selector looks like a setter.
4554  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
4555    return;
4556
4557  // Try to find a variable that the receiver is strongly owned by.
4558  RetainCycleOwner owner;
4559  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
4560    if (!findRetainCycleOwner(msg->getInstanceReceiver(), owner))
4561      return;
4562  } else {
4563    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
4564    owner.Variable = getCurMethodDecl()->getSelfDecl();
4565    owner.Loc = msg->getSuperLoc();
4566    owner.Range = msg->getSuperLoc();
4567  }
4568
4569  // Check whether the receiver is captured by any of the arguments.
4570  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
4571    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
4572      return diagnoseRetainCycle(*this, capturer, owner);
4573}
4574
4575/// Check a property assign to see if it's likely to cause a retain cycle.
4576void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
4577  RetainCycleOwner owner;
4578  if (!findRetainCycleOwner(receiver, owner))
4579    return;
4580
4581  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
4582    diagnoseRetainCycle(*this, capturer, owner);
4583}
4584
4585bool Sema::checkUnsafeAssigns(SourceLocation Loc,
4586                              QualType LHS, Expr *RHS) {
4587  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
4588  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
4589    return false;
4590  // strip off any implicit cast added to get to the one arc-specific
4591  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4592    if (cast->getCastKind() == CK_ARCConsumeObject) {
4593      Diag(Loc, diag::warn_arc_retained_assign)
4594        << (LT == Qualifiers::OCL_ExplicitNone)
4595        << RHS->getSourceRange();
4596      return true;
4597    }
4598    RHS = cast->getSubExpr();
4599  }
4600  return false;
4601}
4602
4603void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
4604                              Expr *LHS, Expr *RHS) {
4605  QualType LHSType = LHS->getType();
4606  if (checkUnsafeAssigns(Loc, LHSType, RHS))
4607    return;
4608  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
4609  // FIXME. Check for other life times.
4610  if (LT != Qualifiers::OCL_None)
4611    return;
4612
4613  if (ObjCPropertyRefExpr *PRE
4614        = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens())) {
4615    if (PRE->isImplicitProperty())
4616      return;
4617    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
4618    if (!PD)
4619      return;
4620
4621    unsigned Attributes = PD->getPropertyAttributes();
4622    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign)
4623      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4624        if (cast->getCastKind() == CK_ARCConsumeObject) {
4625          Diag(Loc, diag::warn_arc_retained_property_assign)
4626          << RHS->getSourceRange();
4627          return;
4628        }
4629        RHS = cast->getSubExpr();
4630      }
4631  }
4632}
4633