SemaChecking.cpp revision cec9ce49dcf4b4b768043f96c8ef8c1d4cdbb6b9 
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/Lookup.h"
20#include "clang/Sema/ScopeInfo.h"
21#include "clang/Analysis/Analyses/FormatString.h"
22#include "clang/AST/ASTContext.h"
23#include "clang/AST/CharUnits.h"
24#include "clang/AST/DeclCXX.h"
25#include "clang/AST/DeclObjC.h"
26#include "clang/AST/Expr.h"
27#include "clang/AST/ExprCXX.h"
28#include "clang/AST/ExprObjC.h"
29#include "clang/AST/EvaluatedExprVisitor.h"
30#include "clang/AST/DeclObjC.h"
31#include "clang/AST/StmtCXX.h"
32#include "clang/AST/StmtObjC.h"
33#include "clang/Lex/Preprocessor.h"
34#include "llvm/ADT/BitVector.h"
35#include "llvm/ADT/SmallString.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/Support/raw_ostream.h"
38#include "clang/Basic/TargetBuiltins.h"
39#include "clang/Basic/TargetInfo.h"
40#include "clang/Basic/ConvertUTF.h"
41#include <limits>
42using namespace clang;
43using namespace sema;
44
45SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
46                                                    unsigned ByteNo) const {
47  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
48                               PP.getLangOpts(), PP.getTargetInfo());
49}
50
51/// Checks that a call expression's argument count is the desired number.
52/// This is useful when doing custom type-checking.  Returns true on error.
53static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
54  unsigned argCount = call->getNumArgs();
55  if (argCount == desiredArgCount) return false;
56
57  if (argCount < desiredArgCount)
58    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
59        << 0 /*function call*/ << desiredArgCount << argCount
60        << call->getSourceRange();
61
62  // Highlight all the excess arguments.
63  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
64                    call->getArg(argCount - 1)->getLocEnd());
65
66  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
67    << 0 /*function call*/ << desiredArgCount << argCount
68    << call->getArg(1)->getSourceRange();
69}
70
71/// Check that the first argument to __builtin_annotation is an integer
72/// and the second argument is a non-wide string literal.
73static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
74  if (checkArgCount(S, TheCall, 2))
75    return true;
76
77  // First argument should be an integer.
78  Expr *ValArg = TheCall->getArg(0);
79  QualType Ty = ValArg->getType();
80  if (!Ty->isIntegerType()) {
81    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
82      << ValArg->getSourceRange();
83    return true;
84  }
85
86  // Second argument should be a constant string.
87  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
88  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
89  if (!Literal || !Literal->isAscii()) {
90    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
91      << StrArg->getSourceRange();
92    return true;
93  }
94
95  TheCall->setType(Ty);
96  return false;
97}
98
99ExprResult
100Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
101  ExprResult TheCallResult(Owned(TheCall));
102
103  // Find out if any arguments are required to be integer constant expressions.
104  unsigned ICEArguments = 0;
105  ASTContext::GetBuiltinTypeError Error;
106  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
107  if (Error != ASTContext::GE_None)
108    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
109
110  // If any arguments are required to be ICE's, check and diagnose.
111  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
112    // Skip arguments not required to be ICE's.
113    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
114
115    llvm::APSInt Result;
116    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
117      return true;
118    ICEArguments &= ~(1 << ArgNo);
119  }
120
121  switch (BuiltinID) {
122  case Builtin::BI__builtin___CFStringMakeConstantString:
123    assert(TheCall->getNumArgs() == 1 &&
124           "Wrong # arguments to builtin CFStringMakeConstantString");
125    if (CheckObjCString(TheCall->getArg(0)))
126      return ExprError();
127    break;
128  case Builtin::BI__builtin_stdarg_start:
129  case Builtin::BI__builtin_va_start:
130    if (SemaBuiltinVAStart(TheCall))
131      return ExprError();
132    break;
133  case Builtin::BI__builtin_isgreater:
134  case Builtin::BI__builtin_isgreaterequal:
135  case Builtin::BI__builtin_isless:
136  case Builtin::BI__builtin_islessequal:
137  case Builtin::BI__builtin_islessgreater:
138  case Builtin::BI__builtin_isunordered:
139    if (SemaBuiltinUnorderedCompare(TheCall))
140      return ExprError();
141    break;
142  case Builtin::BI__builtin_fpclassify:
143    if (SemaBuiltinFPClassification(TheCall, 6))
144      return ExprError();
145    break;
146  case Builtin::BI__builtin_isfinite:
147  case Builtin::BI__builtin_isinf:
148  case Builtin::BI__builtin_isinf_sign:
149  case Builtin::BI__builtin_isnan:
150  case Builtin::BI__builtin_isnormal:
151    if (SemaBuiltinFPClassification(TheCall, 1))
152      return ExprError();
153    break;
154  case Builtin::BI__builtin_shufflevector:
155    return SemaBuiltinShuffleVector(TheCall);
156    // TheCall will be freed by the smart pointer here, but that's fine, since
157    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
158  case Builtin::BI__builtin_prefetch:
159    if (SemaBuiltinPrefetch(TheCall))
160      return ExprError();
161    break;
162  case Builtin::BI__builtin_object_size:
163    if (SemaBuiltinObjectSize(TheCall))
164      return ExprError();
165    break;
166  case Builtin::BI__builtin_longjmp:
167    if (SemaBuiltinLongjmp(TheCall))
168      return ExprError();
169    break;
170
171  case Builtin::BI__builtin_classify_type:
172    if (checkArgCount(*this, TheCall, 1)) return true;
173    TheCall->setType(Context.IntTy);
174    break;
175  case Builtin::BI__builtin_constant_p:
176    if (checkArgCount(*this, TheCall, 1)) return true;
177    TheCall->setType(Context.IntTy);
178    break;
179  case Builtin::BI__sync_fetch_and_add:
180  case Builtin::BI__sync_fetch_and_add_1:
181  case Builtin::BI__sync_fetch_and_add_2:
182  case Builtin::BI__sync_fetch_and_add_4:
183  case Builtin::BI__sync_fetch_and_add_8:
184  case Builtin::BI__sync_fetch_and_add_16:
185  case Builtin::BI__sync_fetch_and_sub:
186  case Builtin::BI__sync_fetch_and_sub_1:
187  case Builtin::BI__sync_fetch_and_sub_2:
188  case Builtin::BI__sync_fetch_and_sub_4:
189  case Builtin::BI__sync_fetch_and_sub_8:
190  case Builtin::BI__sync_fetch_and_sub_16:
191  case Builtin::BI__sync_fetch_and_or:
192  case Builtin::BI__sync_fetch_and_or_1:
193  case Builtin::BI__sync_fetch_and_or_2:
194  case Builtin::BI__sync_fetch_and_or_4:
195  case Builtin::BI__sync_fetch_and_or_8:
196  case Builtin::BI__sync_fetch_and_or_16:
197  case Builtin::BI__sync_fetch_and_and:
198  case Builtin::BI__sync_fetch_and_and_1:
199  case Builtin::BI__sync_fetch_and_and_2:
200  case Builtin::BI__sync_fetch_and_and_4:
201  case Builtin::BI__sync_fetch_and_and_8:
202  case Builtin::BI__sync_fetch_and_and_16:
203  case Builtin::BI__sync_fetch_and_xor:
204  case Builtin::BI__sync_fetch_and_xor_1:
205  case Builtin::BI__sync_fetch_and_xor_2:
206  case Builtin::BI__sync_fetch_and_xor_4:
207  case Builtin::BI__sync_fetch_and_xor_8:
208  case Builtin::BI__sync_fetch_and_xor_16:
209  case Builtin::BI__sync_add_and_fetch:
210  case Builtin::BI__sync_add_and_fetch_1:
211  case Builtin::BI__sync_add_and_fetch_2:
212  case Builtin::BI__sync_add_and_fetch_4:
213  case Builtin::BI__sync_add_and_fetch_8:
214  case Builtin::BI__sync_add_and_fetch_16:
215  case Builtin::BI__sync_sub_and_fetch:
216  case Builtin::BI__sync_sub_and_fetch_1:
217  case Builtin::BI__sync_sub_and_fetch_2:
218  case Builtin::BI__sync_sub_and_fetch_4:
219  case Builtin::BI__sync_sub_and_fetch_8:
220  case Builtin::BI__sync_sub_and_fetch_16:
221  case Builtin::BI__sync_and_and_fetch:
222  case Builtin::BI__sync_and_and_fetch_1:
223  case Builtin::BI__sync_and_and_fetch_2:
224  case Builtin::BI__sync_and_and_fetch_4:
225  case Builtin::BI__sync_and_and_fetch_8:
226  case Builtin::BI__sync_and_and_fetch_16:
227  case Builtin::BI__sync_or_and_fetch:
228  case Builtin::BI__sync_or_and_fetch_1:
229  case Builtin::BI__sync_or_and_fetch_2:
230  case Builtin::BI__sync_or_and_fetch_4:
231  case Builtin::BI__sync_or_and_fetch_8:
232  case Builtin::BI__sync_or_and_fetch_16:
233  case Builtin::BI__sync_xor_and_fetch:
234  case Builtin::BI__sync_xor_and_fetch_1:
235  case Builtin::BI__sync_xor_and_fetch_2:
236  case Builtin::BI__sync_xor_and_fetch_4:
237  case Builtin::BI__sync_xor_and_fetch_8:
238  case Builtin::BI__sync_xor_and_fetch_16:
239  case Builtin::BI__sync_val_compare_and_swap:
240  case Builtin::BI__sync_val_compare_and_swap_1:
241  case Builtin::BI__sync_val_compare_and_swap_2:
242  case Builtin::BI__sync_val_compare_and_swap_4:
243  case Builtin::BI__sync_val_compare_and_swap_8:
244  case Builtin::BI__sync_val_compare_and_swap_16:
245  case Builtin::BI__sync_bool_compare_and_swap:
246  case Builtin::BI__sync_bool_compare_and_swap_1:
247  case Builtin::BI__sync_bool_compare_and_swap_2:
248  case Builtin::BI__sync_bool_compare_and_swap_4:
249  case Builtin::BI__sync_bool_compare_and_swap_8:
250  case Builtin::BI__sync_bool_compare_and_swap_16:
251  case Builtin::BI__sync_lock_test_and_set:
252  case Builtin::BI__sync_lock_test_and_set_1:
253  case Builtin::BI__sync_lock_test_and_set_2:
254  case Builtin::BI__sync_lock_test_and_set_4:
255  case Builtin::BI__sync_lock_test_and_set_8:
256  case Builtin::BI__sync_lock_test_and_set_16:
257  case Builtin::BI__sync_lock_release:
258  case Builtin::BI__sync_lock_release_1:
259  case Builtin::BI__sync_lock_release_2:
260  case Builtin::BI__sync_lock_release_4:
261  case Builtin::BI__sync_lock_release_8:
262  case Builtin::BI__sync_lock_release_16:
263  case Builtin::BI__sync_swap:
264  case Builtin::BI__sync_swap_1:
265  case Builtin::BI__sync_swap_2:
266  case Builtin::BI__sync_swap_4:
267  case Builtin::BI__sync_swap_8:
268  case Builtin::BI__sync_swap_16:
269    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
270#define BUILTIN(ID, TYPE, ATTRS)
271#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
272  case Builtin::BI##ID: \
273    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::AO##ID);
274#include "clang/Basic/Builtins.def"
275  case Builtin::BI__builtin_annotation:
276    if (SemaBuiltinAnnotation(*this, TheCall))
277      return ExprError();
278    break;
279  }
280
281  // Since the target specific builtins for each arch overlap, only check those
282  // of the arch we are compiling for.
283  if (BuiltinID >= Builtin::FirstTSBuiltin) {
284    switch (Context.getTargetInfo().getTriple().getArch()) {
285      case llvm::Triple::arm:
286      case llvm::Triple::thumb:
287        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
288          return ExprError();
289        break;
290      case llvm::Triple::mips:
291      case llvm::Triple::mipsel:
292      case llvm::Triple::mips64:
293      case llvm::Triple::mips64el:
294        if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
295          return ExprError();
296        break;
297      default:
298        break;
299    }
300  }
301
302  return move(TheCallResult);
303}
304
305// Get the valid immediate range for the specified NEON type code.
306static unsigned RFT(unsigned t, bool shift = false) {
307  NeonTypeFlags Type(t);
308  int IsQuad = Type.isQuad();
309  switch (Type.getEltType()) {
310  case NeonTypeFlags::Int8:
311  case NeonTypeFlags::Poly8:
312    return shift ? 7 : (8 << IsQuad) - 1;
313  case NeonTypeFlags::Int16:
314  case NeonTypeFlags::Poly16:
315    return shift ? 15 : (4 << IsQuad) - 1;
316  case NeonTypeFlags::Int32:
317    return shift ? 31 : (2 << IsQuad) - 1;
318  case NeonTypeFlags::Int64:
319    return shift ? 63 : (1 << IsQuad) - 1;
320  case NeonTypeFlags::Float16:
321    assert(!shift && "cannot shift float types!");
322    return (4 << IsQuad) - 1;
323  case NeonTypeFlags::Float32:
324    assert(!shift && "cannot shift float types!");
325    return (2 << IsQuad) - 1;
326  }
327  llvm_unreachable("Invalid NeonTypeFlag!");
328}
329
330/// getNeonEltType - Return the QualType corresponding to the elements of
331/// the vector type specified by the NeonTypeFlags.  This is used to check
332/// the pointer arguments for Neon load/store intrinsics.
333static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
334  switch (Flags.getEltType()) {
335  case NeonTypeFlags::Int8:
336    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
337  case NeonTypeFlags::Int16:
338    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
339  case NeonTypeFlags::Int32:
340    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
341  case NeonTypeFlags::Int64:
342    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
343  case NeonTypeFlags::Poly8:
344    return Context.SignedCharTy;
345  case NeonTypeFlags::Poly16:
346    return Context.ShortTy;
347  case NeonTypeFlags::Float16:
348    return Context.UnsignedShortTy;
349  case NeonTypeFlags::Float32:
350    return Context.FloatTy;
351  }
352  llvm_unreachable("Invalid NeonTypeFlag!");
353}
354
355bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
356  llvm::APSInt Result;
357
358  unsigned mask = 0;
359  unsigned TV = 0;
360  int PtrArgNum = -1;
361  bool HasConstPtr = false;
362  switch (BuiltinID) {
363#define GET_NEON_OVERLOAD_CHECK
364#include "clang/Basic/arm_neon.inc"
365#undef GET_NEON_OVERLOAD_CHECK
366  }
367
368  // For NEON intrinsics which are overloaded on vector element type, validate
369  // the immediate which specifies which variant to emit.
370  unsigned ImmArg = TheCall->getNumArgs()-1;
371  if (mask) {
372    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
373      return true;
374
375    TV = Result.getLimitedValue(64);
376    if ((TV > 63) || (mask & (1 << TV)) == 0)
377      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
378        << TheCall->getArg(ImmArg)->getSourceRange();
379  }
380
381  if (PtrArgNum >= 0) {
382    // Check that pointer arguments have the specified type.
383    Expr *Arg = TheCall->getArg(PtrArgNum);
384    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
385      Arg = ICE->getSubExpr();
386    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
387    QualType RHSTy = RHS.get()->getType();
388    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
389    if (HasConstPtr)
390      EltTy = EltTy.withConst();
391    QualType LHSTy = Context.getPointerType(EltTy);
392    AssignConvertType ConvTy;
393    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
394    if (RHS.isInvalid())
395      return true;
396    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
397                                 RHS.get(), AA_Assigning))
398      return true;
399  }
400
401  // For NEON intrinsics which take an immediate value as part of the
402  // instruction, range check them here.
403  unsigned i = 0, l = 0, u = 0;
404  switch (BuiltinID) {
405  default: return false;
406  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
407  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
408  case ARM::BI__builtin_arm_vcvtr_f:
409  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
410#define GET_NEON_IMMEDIATE_CHECK
411#include "clang/Basic/arm_neon.inc"
412#undef GET_NEON_IMMEDIATE_CHECK
413  };
414
415  // We can't check the value of a dependent argument.
416  if (TheCall->getArg(i)->isTypeDependent() ||
417      TheCall->getArg(i)->isValueDependent())
418    return false;
419
420  // Check that the immediate argument is actually a constant.
421  if (SemaBuiltinConstantArg(TheCall, i, Result))
422    return true;
423
424  // Range check against the upper/lower values for this isntruction.
425  unsigned Val = Result.getZExtValue();
426  if (Val < l || Val > (u + l))
427    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
428      << l << u+l << TheCall->getArg(i)->getSourceRange();
429
430  // FIXME: VFP Intrinsics should error if VFP not present.
431  return false;
432}
433
434bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
435  unsigned i = 0, l = 0, u = 0;
436  switch (BuiltinID) {
437  default: return false;
438  case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
439  case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
440  };
441
442  // We can't check the value of a dependent argument.
443  if (TheCall->getArg(i)->isTypeDependent() ||
444      TheCall->getArg(i)->isValueDependent())
445    return false;
446
447  // Check that the immediate argument is actually a constant.
448  llvm::APSInt Result;
449  if (SemaBuiltinConstantArg(TheCall, i, Result))
450    return true;
451
452  // Range check against the upper/lower values for this instruction.
453  unsigned Val = Result.getZExtValue();
454  if (Val < l || Val > u)
455    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
456      << l << u << TheCall->getArg(i)->getSourceRange();
457
458  return false;
459}
460
461/// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
462/// parameter with the FormatAttr's correct format_idx and firstDataArg.
463/// Returns true when the format fits the function and the FormatStringInfo has
464/// been populated.
465bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
466                               FormatStringInfo *FSI) {
467  FSI->HasVAListArg = Format->getFirstArg() == 0;
468  FSI->FormatIdx = Format->getFormatIdx() - 1;
469  FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
470
471  // The way the format attribute works in GCC, the implicit this argument
472  // of member functions is counted. However, it doesn't appear in our own
473  // lists, so decrement format_idx in that case.
474  if (IsCXXMember) {
475    if(FSI->FormatIdx == 0)
476      return false;
477    --FSI->FormatIdx;
478    if (FSI->FirstDataArg != 0)
479      --FSI->FirstDataArg;
480  }
481  return true;
482}
483
484/// Handles the checks for format strings, non-POD arguments to vararg
485/// functions, and NULL arguments passed to non-NULL parameters.
486void Sema::checkCall(NamedDecl *FDecl, Expr **Args,
487                     unsigned NumArgs,
488                     unsigned NumProtoArgs,
489                     bool IsMemberFunction,
490                     SourceLocation Loc,
491                     SourceRange Range,
492                     VariadicCallType CallType) {
493  // FIXME: This mechanism should be abstracted to be less fragile and
494  // more efficient. For example, just map function ids to custom
495  // handlers.
496
497  // Printf and scanf checking.
498  bool HandledFormatString = false;
499  for (specific_attr_iterator<FormatAttr>
500         I = FDecl->specific_attr_begin<FormatAttr>(),
501         E = FDecl->specific_attr_end<FormatAttr>(); I != E ; ++I)
502    if (CheckFormatArguments(*I, Args, NumArgs, IsMemberFunction, CallType,
503                             Loc, Range))
504        HandledFormatString = true;
505
506  // Refuse POD arguments that weren't caught by the format string
507  // checks above.
508  if (!HandledFormatString && CallType != VariadicDoesNotApply)
509    for (unsigned ArgIdx = NumProtoArgs; ArgIdx < NumArgs; ++ArgIdx)
510      variadicArgumentPODCheck(Args[ArgIdx], CallType);
511
512  for (specific_attr_iterator<NonNullAttr>
513         I = FDecl->specific_attr_begin<NonNullAttr>(),
514         E = FDecl->specific_attr_end<NonNullAttr>(); I != E; ++I)
515    CheckNonNullArguments(*I, Args, Loc);
516}
517
518/// CheckConstructorCall - Check a constructor call for correctness and safety
519/// properties not enforced by the C type system.
520void Sema::CheckConstructorCall(FunctionDecl *FDecl, Expr **Args,
521                                unsigned NumArgs,
522                                const FunctionProtoType *Proto,
523                                SourceLocation Loc) {
524  VariadicCallType CallType =
525    Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
526  checkCall(FDecl, Args, NumArgs, Proto->getNumArgs(),
527            /*IsMemberFunction=*/true, Loc, SourceRange(), CallType);
528}
529
530/// CheckFunctionCall - Check a direct function call for various correctness
531/// and safety properties not strictly enforced by the C type system.
532bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
533                             const FunctionProtoType *Proto) {
534  bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall);
535  VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
536                                                  TheCall->getCallee());
537  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
538  checkCall(FDecl, TheCall->getArgs(), TheCall->getNumArgs(), NumProtoArgs,
539            IsMemberFunction, TheCall->getRParenLoc(),
540            TheCall->getCallee()->getSourceRange(), CallType);
541
542  IdentifierInfo *FnInfo = FDecl->getIdentifier();
543  // None of the checks below are needed for functions that don't have
544  // simple names (e.g., C++ conversion functions).
545  if (!FnInfo)
546    return false;
547
548  unsigned CMId = FDecl->getMemoryFunctionKind();
549  if (CMId == 0)
550    return false;
551
552  // Handle memory setting and copying functions.
553  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
554    CheckStrlcpycatArguments(TheCall, FnInfo);
555  else if (CMId == Builtin::BIstrncat)
556    CheckStrncatArguments(TheCall, FnInfo);
557  else
558    CheckMemaccessArguments(TheCall, CMId, FnInfo);
559
560  return false;
561}
562
563bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
564                               Expr **Args, unsigned NumArgs) {
565  VariadicCallType CallType =
566      Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
567
568  checkCall(Method, Args, NumArgs, Method->param_size(),
569            /*IsMemberFunction=*/false,
570            lbrac, Method->getSourceRange(), CallType);
571
572  return false;
573}
574
575bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall,
576                          const FunctionProtoType *Proto) {
577  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
578  if (!V)
579    return false;
580
581  QualType Ty = V->getType();
582  if (!Ty->isBlockPointerType())
583    return false;
584
585  VariadicCallType CallType =
586      Proto && Proto->isVariadic() ? VariadicBlock : VariadicDoesNotApply ;
587  unsigned NumProtoArgs = Proto ? Proto->getNumArgs() : 0;
588
589  checkCall(NDecl, TheCall->getArgs(), TheCall->getNumArgs(),
590            NumProtoArgs, /*IsMemberFunction=*/false,
591            TheCall->getRParenLoc(),
592            TheCall->getCallee()->getSourceRange(), CallType);
593
594  return false;
595}
596
597ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
598                                         AtomicExpr::AtomicOp Op) {
599  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
600  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
601
602  // All these operations take one of the following forms:
603  enum {
604    // C    __c11_atomic_init(A *, C)
605    Init,
606    // C    __c11_atomic_load(A *, int)
607    Load,
608    // void __atomic_load(A *, CP, int)
609    Copy,
610    // C    __c11_atomic_add(A *, M, int)
611    Arithmetic,
612    // C    __atomic_exchange_n(A *, CP, int)
613    Xchg,
614    // void __atomic_exchange(A *, C *, CP, int)
615    GNUXchg,
616    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
617    C11CmpXchg,
618    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
619    GNUCmpXchg
620  } Form = Init;
621  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
622  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
623  // where:
624  //   C is an appropriate type,
625  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
626  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
627  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
628  //   the int parameters are for orderings.
629
630  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
631         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
632         && "need to update code for modified C11 atomics");
633  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
634               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
635  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
636             Op == AtomicExpr::AO__atomic_store_n ||
637             Op == AtomicExpr::AO__atomic_exchange_n ||
638             Op == AtomicExpr::AO__atomic_compare_exchange_n;
639  bool IsAddSub = false;
640
641  switch (Op) {
642  case AtomicExpr::AO__c11_atomic_init:
643    Form = Init;
644    break;
645
646  case AtomicExpr::AO__c11_atomic_load:
647  case AtomicExpr::AO__atomic_load_n:
648    Form = Load;
649    break;
650
651  case AtomicExpr::AO__c11_atomic_store:
652  case AtomicExpr::AO__atomic_load:
653  case AtomicExpr::AO__atomic_store:
654  case AtomicExpr::AO__atomic_store_n:
655    Form = Copy;
656    break;
657
658  case AtomicExpr::AO__c11_atomic_fetch_add:
659  case AtomicExpr::AO__c11_atomic_fetch_sub:
660  case AtomicExpr::AO__atomic_fetch_add:
661  case AtomicExpr::AO__atomic_fetch_sub:
662  case AtomicExpr::AO__atomic_add_fetch:
663  case AtomicExpr::AO__atomic_sub_fetch:
664    IsAddSub = true;
665    // Fall through.
666  case AtomicExpr::AO__c11_atomic_fetch_and:
667  case AtomicExpr::AO__c11_atomic_fetch_or:
668  case AtomicExpr::AO__c11_atomic_fetch_xor:
669  case AtomicExpr::AO__atomic_fetch_and:
670  case AtomicExpr::AO__atomic_fetch_or:
671  case AtomicExpr::AO__atomic_fetch_xor:
672  case AtomicExpr::AO__atomic_fetch_nand:
673  case AtomicExpr::AO__atomic_and_fetch:
674  case AtomicExpr::AO__atomic_or_fetch:
675  case AtomicExpr::AO__atomic_xor_fetch:
676  case AtomicExpr::AO__atomic_nand_fetch:
677    Form = Arithmetic;
678    break;
679
680  case AtomicExpr::AO__c11_atomic_exchange:
681  case AtomicExpr::AO__atomic_exchange_n:
682    Form = Xchg;
683    break;
684
685  case AtomicExpr::AO__atomic_exchange:
686    Form = GNUXchg;
687    break;
688
689  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
690  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
691    Form = C11CmpXchg;
692    break;
693
694  case AtomicExpr::AO__atomic_compare_exchange:
695  case AtomicExpr::AO__atomic_compare_exchange_n:
696    Form = GNUCmpXchg;
697    break;
698  }
699
700  // Check we have the right number of arguments.
701  if (TheCall->getNumArgs() < NumArgs[Form]) {
702    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
703      << 0 << NumArgs[Form] << TheCall->getNumArgs()
704      << TheCall->getCallee()->getSourceRange();
705    return ExprError();
706  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
707    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
708         diag::err_typecheck_call_too_many_args)
709      << 0 << NumArgs[Form] << TheCall->getNumArgs()
710      << TheCall->getCallee()->getSourceRange();
711    return ExprError();
712  }
713
714  // Inspect the first argument of the atomic operation.
715  Expr *Ptr = TheCall->getArg(0);
716  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
717  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
718  if (!pointerType) {
719    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
720      << Ptr->getType() << Ptr->getSourceRange();
721    return ExprError();
722  }
723
724  // For a __c11 builtin, this should be a pointer to an _Atomic type.
725  QualType AtomTy = pointerType->getPointeeType(); // 'A'
726  QualType ValType = AtomTy; // 'C'
727  if (IsC11) {
728    if (!AtomTy->isAtomicType()) {
729      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
730        << Ptr->getType() << Ptr->getSourceRange();
731      return ExprError();
732    }
733    ValType = AtomTy->getAs<AtomicType>()->getValueType();
734  }
735
736  // For an arithmetic operation, the implied arithmetic must be well-formed.
737  if (Form == Arithmetic) {
738    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
739    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
740      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
741        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
742      return ExprError();
743    }
744    if (!IsAddSub && !ValType->isIntegerType()) {
745      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
746        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
747      return ExprError();
748    }
749  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
750    // For __atomic_*_n operations, the value type must be a scalar integral or
751    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
752    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
753      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
754    return ExprError();
755  }
756
757  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
758    // For GNU atomics, require a trivially-copyable type. This is not part of
759    // the GNU atomics specification, but we enforce it for sanity.
760    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
761      << Ptr->getType() << Ptr->getSourceRange();
762    return ExprError();
763  }
764
765  // FIXME: For any builtin other than a load, the ValType must not be
766  // const-qualified.
767
768  switch (ValType.getObjCLifetime()) {
769  case Qualifiers::OCL_None:
770  case Qualifiers::OCL_ExplicitNone:
771    // okay
772    break;
773
774  case Qualifiers::OCL_Weak:
775  case Qualifiers::OCL_Strong:
776  case Qualifiers::OCL_Autoreleasing:
777    // FIXME: Can this happen? By this point, ValType should be known
778    // to be trivially copyable.
779    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
780      << ValType << Ptr->getSourceRange();
781    return ExprError();
782  }
783
784  QualType ResultType = ValType;
785  if (Form == Copy || Form == GNUXchg || Form == Init)
786    ResultType = Context.VoidTy;
787  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
788    ResultType = Context.BoolTy;
789
790  // The type of a parameter passed 'by value'. In the GNU atomics, such
791  // arguments are actually passed as pointers.
792  QualType ByValType = ValType; // 'CP'
793  if (!IsC11 && !IsN)
794    ByValType = Ptr->getType();
795
796  // The first argument --- the pointer --- has a fixed type; we
797  // deduce the types of the rest of the arguments accordingly.  Walk
798  // the remaining arguments, converting them to the deduced value type.
799  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
800    QualType Ty;
801    if (i < NumVals[Form] + 1) {
802      switch (i) {
803      case 1:
804        // The second argument is the non-atomic operand. For arithmetic, this
805        // is always passed by value, and for a compare_exchange it is always
806        // passed by address. For the rest, GNU uses by-address and C11 uses
807        // by-value.
808        assert(Form != Load);
809        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
810          Ty = ValType;
811        else if (Form == Copy || Form == Xchg)
812          Ty = ByValType;
813        else if (Form == Arithmetic)
814          Ty = Context.getPointerDiffType();
815        else
816          Ty = Context.getPointerType(ValType.getUnqualifiedType());
817        break;
818      case 2:
819        // The third argument to compare_exchange / GNU exchange is a
820        // (pointer to a) desired value.
821        Ty = ByValType;
822        break;
823      case 3:
824        // The fourth argument to GNU compare_exchange is a 'weak' flag.
825        Ty = Context.BoolTy;
826        break;
827      }
828    } else {
829      // The order(s) are always converted to int.
830      Ty = Context.IntTy;
831    }
832
833    InitializedEntity Entity =
834        InitializedEntity::InitializeParameter(Context, Ty, false);
835    ExprResult Arg = TheCall->getArg(i);
836    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
837    if (Arg.isInvalid())
838      return true;
839    TheCall->setArg(i, Arg.get());
840  }
841
842  // Permute the arguments into a 'consistent' order.
843  SmallVector<Expr*, 5> SubExprs;
844  SubExprs.push_back(Ptr);
845  switch (Form) {
846  case Init:
847    // Note, AtomicExpr::getVal1() has a special case for this atomic.
848    SubExprs.push_back(TheCall->getArg(1)); // Val1
849    break;
850  case Load:
851    SubExprs.push_back(TheCall->getArg(1)); // Order
852    break;
853  case Copy:
854  case Arithmetic:
855  case Xchg:
856    SubExprs.push_back(TheCall->getArg(2)); // Order
857    SubExprs.push_back(TheCall->getArg(1)); // Val1
858    break;
859  case GNUXchg:
860    // Note, AtomicExpr::getVal2() has a special case for this atomic.
861    SubExprs.push_back(TheCall->getArg(3)); // Order
862    SubExprs.push_back(TheCall->getArg(1)); // Val1
863    SubExprs.push_back(TheCall->getArg(2)); // Val2
864    break;
865  case C11CmpXchg:
866    SubExprs.push_back(TheCall->getArg(3)); // Order
867    SubExprs.push_back(TheCall->getArg(1)); // Val1
868    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
869    SubExprs.push_back(TheCall->getArg(2)); // Val2
870    break;
871  case GNUCmpXchg:
872    SubExprs.push_back(TheCall->getArg(4)); // Order
873    SubExprs.push_back(TheCall->getArg(1)); // Val1
874    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
875    SubExprs.push_back(TheCall->getArg(2)); // Val2
876    SubExprs.push_back(TheCall->getArg(3)); // Weak
877    break;
878  }
879
880  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
881                                        SubExprs.data(), SubExprs.size(),
882                                        ResultType, Op,
883                                        TheCall->getRParenLoc()));
884}
885
886
887/// checkBuiltinArgument - Given a call to a builtin function, perform
888/// normal type-checking on the given argument, updating the call in
889/// place.  This is useful when a builtin function requires custom
890/// type-checking for some of its arguments but not necessarily all of
891/// them.
892///
893/// Returns true on error.
894static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
895  FunctionDecl *Fn = E->getDirectCallee();
896  assert(Fn && "builtin call without direct callee!");
897
898  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
899  InitializedEntity Entity =
900    InitializedEntity::InitializeParameter(S.Context, Param);
901
902  ExprResult Arg = E->getArg(0);
903  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
904  if (Arg.isInvalid())
905    return true;
906
907  E->setArg(ArgIndex, Arg.take());
908  return false;
909}
910
911/// SemaBuiltinAtomicOverloaded - We have a call to a function like
912/// __sync_fetch_and_add, which is an overloaded function based on the pointer
913/// type of its first argument.  The main ActOnCallExpr routines have already
914/// promoted the types of arguments because all of these calls are prototyped as
915/// void(...).
916///
917/// This function goes through and does final semantic checking for these
918/// builtins,
919ExprResult
920Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
921  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
922  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
923  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
924
925  // Ensure that we have at least one argument to do type inference from.
926  if (TheCall->getNumArgs() < 1) {
927    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
928      << 0 << 1 << TheCall->getNumArgs()
929      << TheCall->getCallee()->getSourceRange();
930    return ExprError();
931  }
932
933  // Inspect the first argument of the atomic builtin.  This should always be
934  // a pointer type, whose element is an integral scalar or pointer type.
935  // Because it is a pointer type, we don't have to worry about any implicit
936  // casts here.
937  // FIXME: We don't allow floating point scalars as input.
938  Expr *FirstArg = TheCall->getArg(0);
939  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
940  if (FirstArgResult.isInvalid())
941    return ExprError();
942  FirstArg = FirstArgResult.take();
943  TheCall->setArg(0, FirstArg);
944
945  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
946  if (!pointerType) {
947    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
948      << FirstArg->getType() << FirstArg->getSourceRange();
949    return ExprError();
950  }
951
952  QualType ValType = pointerType->getPointeeType();
953  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
954      !ValType->isBlockPointerType()) {
955    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
956      << FirstArg->getType() << FirstArg->getSourceRange();
957    return ExprError();
958  }
959
960  switch (ValType.getObjCLifetime()) {
961  case Qualifiers::OCL_None:
962  case Qualifiers::OCL_ExplicitNone:
963    // okay
964    break;
965
966  case Qualifiers::OCL_Weak:
967  case Qualifiers::OCL_Strong:
968  case Qualifiers::OCL_Autoreleasing:
969    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
970      << ValType << FirstArg->getSourceRange();
971    return ExprError();
972  }
973
974  // Strip any qualifiers off ValType.
975  ValType = ValType.getUnqualifiedType();
976
977  // The majority of builtins return a value, but a few have special return
978  // types, so allow them to override appropriately below.
979  QualType ResultType = ValType;
980
981  // We need to figure out which concrete builtin this maps onto.  For example,
982  // __sync_fetch_and_add with a 2 byte object turns into
983  // __sync_fetch_and_add_2.
984#define BUILTIN_ROW(x) \
985  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
986    Builtin::BI##x##_8, Builtin::BI##x##_16 }
987
988  static const unsigned BuiltinIndices[][5] = {
989    BUILTIN_ROW(__sync_fetch_and_add),
990    BUILTIN_ROW(__sync_fetch_and_sub),
991    BUILTIN_ROW(__sync_fetch_and_or),
992    BUILTIN_ROW(__sync_fetch_and_and),
993    BUILTIN_ROW(__sync_fetch_and_xor),
994
995    BUILTIN_ROW(__sync_add_and_fetch),
996    BUILTIN_ROW(__sync_sub_and_fetch),
997    BUILTIN_ROW(__sync_and_and_fetch),
998    BUILTIN_ROW(__sync_or_and_fetch),
999    BUILTIN_ROW(__sync_xor_and_fetch),
1000
1001    BUILTIN_ROW(__sync_val_compare_and_swap),
1002    BUILTIN_ROW(__sync_bool_compare_and_swap),
1003    BUILTIN_ROW(__sync_lock_test_and_set),
1004    BUILTIN_ROW(__sync_lock_release),
1005    BUILTIN_ROW(__sync_swap)
1006  };
1007#undef BUILTIN_ROW
1008
1009  // Determine the index of the size.
1010  unsigned SizeIndex;
1011  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1012  case 1: SizeIndex = 0; break;
1013  case 2: SizeIndex = 1; break;
1014  case 4: SizeIndex = 2; break;
1015  case 8: SizeIndex = 3; break;
1016  case 16: SizeIndex = 4; break;
1017  default:
1018    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1019      << FirstArg->getType() << FirstArg->getSourceRange();
1020    return ExprError();
1021  }
1022
1023  // Each of these builtins has one pointer argument, followed by some number of
1024  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1025  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1026  // as the number of fixed args.
1027  unsigned BuiltinID = FDecl->getBuiltinID();
1028  unsigned BuiltinIndex, NumFixed = 1;
1029  switch (BuiltinID) {
1030  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1031  case Builtin::BI__sync_fetch_and_add:
1032  case Builtin::BI__sync_fetch_and_add_1:
1033  case Builtin::BI__sync_fetch_and_add_2:
1034  case Builtin::BI__sync_fetch_and_add_4:
1035  case Builtin::BI__sync_fetch_and_add_8:
1036  case Builtin::BI__sync_fetch_and_add_16:
1037    BuiltinIndex = 0;
1038    break;
1039
1040  case Builtin::BI__sync_fetch_and_sub:
1041  case Builtin::BI__sync_fetch_and_sub_1:
1042  case Builtin::BI__sync_fetch_and_sub_2:
1043  case Builtin::BI__sync_fetch_and_sub_4:
1044  case Builtin::BI__sync_fetch_and_sub_8:
1045  case Builtin::BI__sync_fetch_and_sub_16:
1046    BuiltinIndex = 1;
1047    break;
1048
1049  case Builtin::BI__sync_fetch_and_or:
1050  case Builtin::BI__sync_fetch_and_or_1:
1051  case Builtin::BI__sync_fetch_and_or_2:
1052  case Builtin::BI__sync_fetch_and_or_4:
1053  case Builtin::BI__sync_fetch_and_or_8:
1054  case Builtin::BI__sync_fetch_and_or_16:
1055    BuiltinIndex = 2;
1056    break;
1057
1058  case Builtin::BI__sync_fetch_and_and:
1059  case Builtin::BI__sync_fetch_and_and_1:
1060  case Builtin::BI__sync_fetch_and_and_2:
1061  case Builtin::BI__sync_fetch_and_and_4:
1062  case Builtin::BI__sync_fetch_and_and_8:
1063  case Builtin::BI__sync_fetch_and_and_16:
1064    BuiltinIndex = 3;
1065    break;
1066
1067  case Builtin::BI__sync_fetch_and_xor:
1068  case Builtin::BI__sync_fetch_and_xor_1:
1069  case Builtin::BI__sync_fetch_and_xor_2:
1070  case Builtin::BI__sync_fetch_and_xor_4:
1071  case Builtin::BI__sync_fetch_and_xor_8:
1072  case Builtin::BI__sync_fetch_and_xor_16:
1073    BuiltinIndex = 4;
1074    break;
1075
1076  case Builtin::BI__sync_add_and_fetch:
1077  case Builtin::BI__sync_add_and_fetch_1:
1078  case Builtin::BI__sync_add_and_fetch_2:
1079  case Builtin::BI__sync_add_and_fetch_4:
1080  case Builtin::BI__sync_add_and_fetch_8:
1081  case Builtin::BI__sync_add_and_fetch_16:
1082    BuiltinIndex = 5;
1083    break;
1084
1085  case Builtin::BI__sync_sub_and_fetch:
1086  case Builtin::BI__sync_sub_and_fetch_1:
1087  case Builtin::BI__sync_sub_and_fetch_2:
1088  case Builtin::BI__sync_sub_and_fetch_4:
1089  case Builtin::BI__sync_sub_and_fetch_8:
1090  case Builtin::BI__sync_sub_and_fetch_16:
1091    BuiltinIndex = 6;
1092    break;
1093
1094  case Builtin::BI__sync_and_and_fetch:
1095  case Builtin::BI__sync_and_and_fetch_1:
1096  case Builtin::BI__sync_and_and_fetch_2:
1097  case Builtin::BI__sync_and_and_fetch_4:
1098  case Builtin::BI__sync_and_and_fetch_8:
1099  case Builtin::BI__sync_and_and_fetch_16:
1100    BuiltinIndex = 7;
1101    break;
1102
1103  case Builtin::BI__sync_or_and_fetch:
1104  case Builtin::BI__sync_or_and_fetch_1:
1105  case Builtin::BI__sync_or_and_fetch_2:
1106  case Builtin::BI__sync_or_and_fetch_4:
1107  case Builtin::BI__sync_or_and_fetch_8:
1108  case Builtin::BI__sync_or_and_fetch_16:
1109    BuiltinIndex = 8;
1110    break;
1111
1112  case Builtin::BI__sync_xor_and_fetch:
1113  case Builtin::BI__sync_xor_and_fetch_1:
1114  case Builtin::BI__sync_xor_and_fetch_2:
1115  case Builtin::BI__sync_xor_and_fetch_4:
1116  case Builtin::BI__sync_xor_and_fetch_8:
1117  case Builtin::BI__sync_xor_and_fetch_16:
1118    BuiltinIndex = 9;
1119    break;
1120
1121  case Builtin::BI__sync_val_compare_and_swap:
1122  case Builtin::BI__sync_val_compare_and_swap_1:
1123  case Builtin::BI__sync_val_compare_and_swap_2:
1124  case Builtin::BI__sync_val_compare_and_swap_4:
1125  case Builtin::BI__sync_val_compare_and_swap_8:
1126  case Builtin::BI__sync_val_compare_and_swap_16:
1127    BuiltinIndex = 10;
1128    NumFixed = 2;
1129    break;
1130
1131  case Builtin::BI__sync_bool_compare_and_swap:
1132  case Builtin::BI__sync_bool_compare_and_swap_1:
1133  case Builtin::BI__sync_bool_compare_and_swap_2:
1134  case Builtin::BI__sync_bool_compare_and_swap_4:
1135  case Builtin::BI__sync_bool_compare_and_swap_8:
1136  case Builtin::BI__sync_bool_compare_and_swap_16:
1137    BuiltinIndex = 11;
1138    NumFixed = 2;
1139    ResultType = Context.BoolTy;
1140    break;
1141
1142  case Builtin::BI__sync_lock_test_and_set:
1143  case Builtin::BI__sync_lock_test_and_set_1:
1144  case Builtin::BI__sync_lock_test_and_set_2:
1145  case Builtin::BI__sync_lock_test_and_set_4:
1146  case Builtin::BI__sync_lock_test_and_set_8:
1147  case Builtin::BI__sync_lock_test_and_set_16:
1148    BuiltinIndex = 12;
1149    break;
1150
1151  case Builtin::BI__sync_lock_release:
1152  case Builtin::BI__sync_lock_release_1:
1153  case Builtin::BI__sync_lock_release_2:
1154  case Builtin::BI__sync_lock_release_4:
1155  case Builtin::BI__sync_lock_release_8:
1156  case Builtin::BI__sync_lock_release_16:
1157    BuiltinIndex = 13;
1158    NumFixed = 0;
1159    ResultType = Context.VoidTy;
1160    break;
1161
1162  case Builtin::BI__sync_swap:
1163  case Builtin::BI__sync_swap_1:
1164  case Builtin::BI__sync_swap_2:
1165  case Builtin::BI__sync_swap_4:
1166  case Builtin::BI__sync_swap_8:
1167  case Builtin::BI__sync_swap_16:
1168    BuiltinIndex = 14;
1169    break;
1170  }
1171
1172  // Now that we know how many fixed arguments we expect, first check that we
1173  // have at least that many.
1174  if (TheCall->getNumArgs() < 1+NumFixed) {
1175    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1176      << 0 << 1+NumFixed << TheCall->getNumArgs()
1177      << TheCall->getCallee()->getSourceRange();
1178    return ExprError();
1179  }
1180
1181  // Get the decl for the concrete builtin from this, we can tell what the
1182  // concrete integer type we should convert to is.
1183  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1184  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1185  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
1186  FunctionDecl *NewBuiltinDecl =
1187    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
1188                                           TUScope, false, DRE->getLocStart()));
1189
1190  // The first argument --- the pointer --- has a fixed type; we
1191  // deduce the types of the rest of the arguments accordingly.  Walk
1192  // the remaining arguments, converting them to the deduced value type.
1193  for (unsigned i = 0; i != NumFixed; ++i) {
1194    ExprResult Arg = TheCall->getArg(i+1);
1195
1196    // GCC does an implicit conversion to the pointer or integer ValType.  This
1197    // can fail in some cases (1i -> int**), check for this error case now.
1198    // Initialize the argument.
1199    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1200                                                   ValType, /*consume*/ false);
1201    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1202    if (Arg.isInvalid())
1203      return ExprError();
1204
1205    // Okay, we have something that *can* be converted to the right type.  Check
1206    // to see if there is a potentially weird extension going on here.  This can
1207    // happen when you do an atomic operation on something like an char* and
1208    // pass in 42.  The 42 gets converted to char.  This is even more strange
1209    // for things like 45.123 -> char, etc.
1210    // FIXME: Do this check.
1211    TheCall->setArg(i+1, Arg.take());
1212  }
1213
1214  ASTContext& Context = this->getASTContext();
1215
1216  // Create a new DeclRefExpr to refer to the new decl.
1217  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1218      Context,
1219      DRE->getQualifierLoc(),
1220      SourceLocation(),
1221      NewBuiltinDecl,
1222      /*enclosing*/ false,
1223      DRE->getLocation(),
1224      NewBuiltinDecl->getType(),
1225      DRE->getValueKind());
1226
1227  // Set the callee in the CallExpr.
1228  // FIXME: This leaks the original parens and implicit casts.
1229  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
1230  if (PromotedCall.isInvalid())
1231    return ExprError();
1232  TheCall->setCallee(PromotedCall.take());
1233
1234  // Change the result type of the call to match the original value type. This
1235  // is arbitrary, but the codegen for these builtins ins design to handle it
1236  // gracefully.
1237  TheCall->setType(ResultType);
1238
1239  return move(TheCallResult);
1240}
1241
1242/// CheckObjCString - Checks that the argument to the builtin
1243/// CFString constructor is correct
1244/// Note: It might also make sense to do the UTF-16 conversion here (would
1245/// simplify the backend).
1246bool Sema::CheckObjCString(Expr *Arg) {
1247  Arg = Arg->IgnoreParenCasts();
1248  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1249
1250  if (!Literal || !Literal->isAscii()) {
1251    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1252      << Arg->getSourceRange();
1253    return true;
1254  }
1255
1256  if (Literal->containsNonAsciiOrNull()) {
1257    StringRef String = Literal->getString();
1258    unsigned NumBytes = String.size();
1259    SmallVector<UTF16, 128> ToBuf(NumBytes);
1260    const UTF8 *FromPtr = (UTF8 *)String.data();
1261    UTF16 *ToPtr = &ToBuf[0];
1262
1263    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1264                                                 &ToPtr, ToPtr + NumBytes,
1265                                                 strictConversion);
1266    // Check for conversion failure.
1267    if (Result != conversionOK)
1268      Diag(Arg->getLocStart(),
1269           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1270  }
1271  return false;
1272}
1273
1274/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1275/// Emit an error and return true on failure, return false on success.
1276bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1277  Expr *Fn = TheCall->getCallee();
1278  if (TheCall->getNumArgs() > 2) {
1279    Diag(TheCall->getArg(2)->getLocStart(),
1280         diag::err_typecheck_call_too_many_args)
1281      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1282      << Fn->getSourceRange()
1283      << SourceRange(TheCall->getArg(2)->getLocStart(),
1284                     (*(TheCall->arg_end()-1))->getLocEnd());
1285    return true;
1286  }
1287
1288  if (TheCall->getNumArgs() < 2) {
1289    return Diag(TheCall->getLocEnd(),
1290      diag::err_typecheck_call_too_few_args_at_least)
1291      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1292  }
1293
1294  // Type-check the first argument normally.
1295  if (checkBuiltinArgument(*this, TheCall, 0))
1296    return true;
1297
1298  // Determine whether the current function is variadic or not.
1299  BlockScopeInfo *CurBlock = getCurBlock();
1300  bool isVariadic;
1301  if (CurBlock)
1302    isVariadic = CurBlock->TheDecl->isVariadic();
1303  else if (FunctionDecl *FD = getCurFunctionDecl())
1304    isVariadic = FD->isVariadic();
1305  else
1306    isVariadic = getCurMethodDecl()->isVariadic();
1307
1308  if (!isVariadic) {
1309    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1310    return true;
1311  }
1312
1313  // Verify that the second argument to the builtin is the last argument of the
1314  // current function or method.
1315  bool SecondArgIsLastNamedArgument = false;
1316  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1317
1318  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1319    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1320      // FIXME: This isn't correct for methods (results in bogus warning).
1321      // Get the last formal in the current function.
1322      const ParmVarDecl *LastArg;
1323      if (CurBlock)
1324        LastArg = *(CurBlock->TheDecl->param_end()-1);
1325      else if (FunctionDecl *FD = getCurFunctionDecl())
1326        LastArg = *(FD->param_end()-1);
1327      else
1328        LastArg = *(getCurMethodDecl()->param_end()-1);
1329      SecondArgIsLastNamedArgument = PV == LastArg;
1330    }
1331  }
1332
1333  if (!SecondArgIsLastNamedArgument)
1334    Diag(TheCall->getArg(1)->getLocStart(),
1335         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1336  return false;
1337}
1338
1339/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1340/// friends.  This is declared to take (...), so we have to check everything.
1341bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1342  if (TheCall->getNumArgs() < 2)
1343    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1344      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1345  if (TheCall->getNumArgs() > 2)
1346    return Diag(TheCall->getArg(2)->getLocStart(),
1347                diag::err_typecheck_call_too_many_args)
1348      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1349      << SourceRange(TheCall->getArg(2)->getLocStart(),
1350                     (*(TheCall->arg_end()-1))->getLocEnd());
1351
1352  ExprResult OrigArg0 = TheCall->getArg(0);
1353  ExprResult OrigArg1 = TheCall->getArg(1);
1354
1355  // Do standard promotions between the two arguments, returning their common
1356  // type.
1357  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1358  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1359    return true;
1360
1361  // Make sure any conversions are pushed back into the call; this is
1362  // type safe since unordered compare builtins are declared as "_Bool
1363  // foo(...)".
1364  TheCall->setArg(0, OrigArg0.get());
1365  TheCall->setArg(1, OrigArg1.get());
1366
1367  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1368    return false;
1369
1370  // If the common type isn't a real floating type, then the arguments were
1371  // invalid for this operation.
1372  if (Res.isNull() || !Res->isRealFloatingType())
1373    return Diag(OrigArg0.get()->getLocStart(),
1374                diag::err_typecheck_call_invalid_ordered_compare)
1375      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1376      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1377
1378  return false;
1379}
1380
1381/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1382/// __builtin_isnan and friends.  This is declared to take (...), so we have
1383/// to check everything. We expect the last argument to be a floating point
1384/// value.
1385bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1386  if (TheCall->getNumArgs() < NumArgs)
1387    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1388      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1389  if (TheCall->getNumArgs() > NumArgs)
1390    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1391                diag::err_typecheck_call_too_many_args)
1392      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1393      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1394                     (*(TheCall->arg_end()-1))->getLocEnd());
1395
1396  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1397
1398  if (OrigArg->isTypeDependent())
1399    return false;
1400
1401  // This operation requires a non-_Complex floating-point number.
1402  if (!OrigArg->getType()->isRealFloatingType())
1403    return Diag(OrigArg->getLocStart(),
1404                diag::err_typecheck_call_invalid_unary_fp)
1405      << OrigArg->getType() << OrigArg->getSourceRange();
1406
1407  // If this is an implicit conversion from float -> double, remove it.
1408  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1409    Expr *CastArg = Cast->getSubExpr();
1410    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1411      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1412             "promotion from float to double is the only expected cast here");
1413      Cast->setSubExpr(0);
1414      TheCall->setArg(NumArgs-1, CastArg);
1415    }
1416  }
1417
1418  return false;
1419}
1420
1421/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1422// This is declared to take (...), so we have to check everything.
1423ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1424  if (TheCall->getNumArgs() < 2)
1425    return ExprError(Diag(TheCall->getLocEnd(),
1426                          diag::err_typecheck_call_too_few_args_at_least)
1427      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1428      << TheCall->getSourceRange());
1429
1430  // Determine which of the following types of shufflevector we're checking:
1431  // 1) unary, vector mask: (lhs, mask)
1432  // 2) binary, vector mask: (lhs, rhs, mask)
1433  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1434  QualType resType = TheCall->getArg(0)->getType();
1435  unsigned numElements = 0;
1436
1437  if (!TheCall->getArg(0)->isTypeDependent() &&
1438      !TheCall->getArg(1)->isTypeDependent()) {
1439    QualType LHSType = TheCall->getArg(0)->getType();
1440    QualType RHSType = TheCall->getArg(1)->getType();
1441
1442    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1443      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1444        << SourceRange(TheCall->getArg(0)->getLocStart(),
1445                       TheCall->getArg(1)->getLocEnd());
1446      return ExprError();
1447    }
1448
1449    numElements = LHSType->getAs<VectorType>()->getNumElements();
1450    unsigned numResElements = TheCall->getNumArgs() - 2;
1451
1452    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1453    // with mask.  If so, verify that RHS is an integer vector type with the
1454    // same number of elts as lhs.
1455    if (TheCall->getNumArgs() == 2) {
1456      if (!RHSType->hasIntegerRepresentation() ||
1457          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1458        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1459          << SourceRange(TheCall->getArg(1)->getLocStart(),
1460                         TheCall->getArg(1)->getLocEnd());
1461      numResElements = numElements;
1462    }
1463    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1464      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1465        << SourceRange(TheCall->getArg(0)->getLocStart(),
1466                       TheCall->getArg(1)->getLocEnd());
1467      return ExprError();
1468    } else if (numElements != numResElements) {
1469      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1470      resType = Context.getVectorType(eltType, numResElements,
1471                                      VectorType::GenericVector);
1472    }
1473  }
1474
1475  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1476    if (TheCall->getArg(i)->isTypeDependent() ||
1477        TheCall->getArg(i)->isValueDependent())
1478      continue;
1479
1480    llvm::APSInt Result(32);
1481    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1482      return ExprError(Diag(TheCall->getLocStart(),
1483                  diag::err_shufflevector_nonconstant_argument)
1484                << TheCall->getArg(i)->getSourceRange());
1485
1486    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1487      return ExprError(Diag(TheCall->getLocStart(),
1488                  diag::err_shufflevector_argument_too_large)
1489               << TheCall->getArg(i)->getSourceRange());
1490  }
1491
1492  SmallVector<Expr*, 32> exprs;
1493
1494  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1495    exprs.push_back(TheCall->getArg(i));
1496    TheCall->setArg(i, 0);
1497  }
1498
1499  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
1500                                            exprs.size(), resType,
1501                                            TheCall->getCallee()->getLocStart(),
1502                                            TheCall->getRParenLoc()));
1503}
1504
1505/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1506// This is declared to take (const void*, ...) and can take two
1507// optional constant int args.
1508bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1509  unsigned NumArgs = TheCall->getNumArgs();
1510
1511  if (NumArgs > 3)
1512    return Diag(TheCall->getLocEnd(),
1513             diag::err_typecheck_call_too_many_args_at_most)
1514             << 0 /*function call*/ << 3 << NumArgs
1515             << TheCall->getSourceRange();
1516
1517  // Argument 0 is checked for us and the remaining arguments must be
1518  // constant integers.
1519  for (unsigned i = 1; i != NumArgs; ++i) {
1520    Expr *Arg = TheCall->getArg(i);
1521
1522    // We can't check the value of a dependent argument.
1523    if (Arg->isTypeDependent() || Arg->isValueDependent())
1524      continue;
1525
1526    llvm::APSInt Result;
1527    if (SemaBuiltinConstantArg(TheCall, i, Result))
1528      return true;
1529
1530    // FIXME: gcc issues a warning and rewrites these to 0. These
1531    // seems especially odd for the third argument since the default
1532    // is 3.
1533    if (i == 1) {
1534      if (Result.getLimitedValue() > 1)
1535        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1536             << "0" << "1" << Arg->getSourceRange();
1537    } else {
1538      if (Result.getLimitedValue() > 3)
1539        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1540            << "0" << "3" << Arg->getSourceRange();
1541    }
1542  }
1543
1544  return false;
1545}
1546
1547/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1548/// TheCall is a constant expression.
1549bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1550                                  llvm::APSInt &Result) {
1551  Expr *Arg = TheCall->getArg(ArgNum);
1552  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1553  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1554
1555  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1556
1557  if (!Arg->isIntegerConstantExpr(Result, Context))
1558    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1559                << FDecl->getDeclName() <<  Arg->getSourceRange();
1560
1561  return false;
1562}
1563
1564/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1565/// int type). This simply type checks that type is one of the defined
1566/// constants (0-3).
1567// For compatibility check 0-3, llvm only handles 0 and 2.
1568bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1569  llvm::APSInt Result;
1570
1571  // We can't check the value of a dependent argument.
1572  if (TheCall->getArg(1)->isTypeDependent() ||
1573      TheCall->getArg(1)->isValueDependent())
1574    return false;
1575
1576  // Check constant-ness first.
1577  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1578    return true;
1579
1580  Expr *Arg = TheCall->getArg(1);
1581  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1582    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1583             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1584  }
1585
1586  return false;
1587}
1588
1589/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1590/// This checks that val is a constant 1.
1591bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1592  Expr *Arg = TheCall->getArg(1);
1593  llvm::APSInt Result;
1594
1595  // TODO: This is less than ideal. Overload this to take a value.
1596  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1597    return true;
1598
1599  if (Result != 1)
1600    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1601             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1602
1603  return false;
1604}
1605
1606// Determine if an expression is a string literal or constant string.
1607// If this function returns false on the arguments to a function expecting a
1608// format string, we will usually need to emit a warning.
1609// True string literals are then checked by CheckFormatString.
1610Sema::StringLiteralCheckType
1611Sema::checkFormatStringExpr(const Expr *E, Expr **Args,
1612                            unsigned NumArgs, bool HasVAListArg,
1613                            unsigned format_idx, unsigned firstDataArg,
1614                            FormatStringType Type, VariadicCallType CallType,
1615                            bool inFunctionCall) {
1616 tryAgain:
1617  if (E->isTypeDependent() || E->isValueDependent())
1618    return SLCT_NotALiteral;
1619
1620  E = E->IgnoreParenCasts();
1621
1622  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1623    // Technically -Wformat-nonliteral does not warn about this case.
1624    // The behavior of printf and friends in this case is implementation
1625    // dependent.  Ideally if the format string cannot be null then
1626    // it should have a 'nonnull' attribute in the function prototype.
1627    return SLCT_CheckedLiteral;
1628
1629  switch (E->getStmtClass()) {
1630  case Stmt::BinaryConditionalOperatorClass:
1631  case Stmt::ConditionalOperatorClass: {
1632    // The expression is a literal if both sub-expressions were, and it was
1633    // completely checked only if both sub-expressions were checked.
1634    const AbstractConditionalOperator *C =
1635        cast<AbstractConditionalOperator>(E);
1636    StringLiteralCheckType Left =
1637        checkFormatStringExpr(C->getTrueExpr(), Args, NumArgs,
1638                              HasVAListArg, format_idx, firstDataArg,
1639                              Type, CallType, inFunctionCall);
1640    if (Left == SLCT_NotALiteral)
1641      return SLCT_NotALiteral;
1642    StringLiteralCheckType Right =
1643        checkFormatStringExpr(C->getFalseExpr(), Args, NumArgs,
1644                              HasVAListArg, format_idx, firstDataArg,
1645                              Type, CallType, inFunctionCall);
1646    return Left < Right ? Left : Right;
1647  }
1648
1649  case Stmt::ImplicitCastExprClass: {
1650    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1651    goto tryAgain;
1652  }
1653
1654  case Stmt::OpaqueValueExprClass:
1655    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1656      E = src;
1657      goto tryAgain;
1658    }
1659    return SLCT_NotALiteral;
1660
1661  case Stmt::PredefinedExprClass:
1662    // While __func__, etc., are technically not string literals, they
1663    // cannot contain format specifiers and thus are not a security
1664    // liability.
1665    return SLCT_UncheckedLiteral;
1666
1667  case Stmt::DeclRefExprClass: {
1668    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1669
1670    // As an exception, do not flag errors for variables binding to
1671    // const string literals.
1672    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1673      bool isConstant = false;
1674      QualType T = DR->getType();
1675
1676      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1677        isConstant = AT->getElementType().isConstant(Context);
1678      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1679        isConstant = T.isConstant(Context) &&
1680                     PT->getPointeeType().isConstant(Context);
1681      } else if (T->isObjCObjectPointerType()) {
1682        // In ObjC, there is usually no "const ObjectPointer" type,
1683        // so don't check if the pointee type is constant.
1684        isConstant = T.isConstant(Context);
1685      }
1686
1687      if (isConstant) {
1688        if (const Expr *Init = VD->getAnyInitializer()) {
1689          // Look through initializers like const char c[] = { "foo" }
1690          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
1691            if (InitList->isStringLiteralInit())
1692              Init = InitList->getInit(0)->IgnoreParenImpCasts();
1693          }
1694          return checkFormatStringExpr(Init, Args, NumArgs,
1695                                       HasVAListArg, format_idx,
1696                                       firstDataArg, Type, CallType,
1697                                       /*inFunctionCall*/false);
1698        }
1699      }
1700
1701      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1702      // special check to see if the format string is a function parameter
1703      // of the function calling the printf function.  If the function
1704      // has an attribute indicating it is a printf-like function, then we
1705      // should suppress warnings concerning non-literals being used in a call
1706      // to a vprintf function.  For example:
1707      //
1708      // void
1709      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1710      //      va_list ap;
1711      //      va_start(ap, fmt);
1712      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1713      //      ...
1714      //
1715      if (HasVAListArg) {
1716        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1717          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1718            int PVIndex = PV->getFunctionScopeIndex() + 1;
1719            for (specific_attr_iterator<FormatAttr>
1720                 i = ND->specific_attr_begin<FormatAttr>(),
1721                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1722              FormatAttr *PVFormat = *i;
1723              // adjust for implicit parameter
1724              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1725                if (MD->isInstance())
1726                  ++PVIndex;
1727              // We also check if the formats are compatible.
1728              // We can't pass a 'scanf' string to a 'printf' function.
1729              if (PVIndex == PVFormat->getFormatIdx() &&
1730                  Type == GetFormatStringType(PVFormat))
1731                return SLCT_UncheckedLiteral;
1732            }
1733          }
1734        }
1735      }
1736    }
1737
1738    return SLCT_NotALiteral;
1739  }
1740
1741  case Stmt::CallExprClass:
1742  case Stmt::CXXMemberCallExprClass: {
1743    const CallExpr *CE = cast<CallExpr>(E);
1744    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1745      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1746        unsigned ArgIndex = FA->getFormatIdx();
1747        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1748          if (MD->isInstance())
1749            --ArgIndex;
1750        const Expr *Arg = CE->getArg(ArgIndex - 1);
1751
1752        return checkFormatStringExpr(Arg, Args, NumArgs,
1753                                     HasVAListArg, format_idx, firstDataArg,
1754                                     Type, CallType, inFunctionCall);
1755      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
1756        unsigned BuiltinID = FD->getBuiltinID();
1757        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
1758            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
1759          const Expr *Arg = CE->getArg(0);
1760          return checkFormatStringExpr(Arg, Args, NumArgs,
1761                                       HasVAListArg, format_idx,
1762                                       firstDataArg, Type, CallType,
1763                                       inFunctionCall);
1764        }
1765      }
1766    }
1767
1768    return SLCT_NotALiteral;
1769  }
1770  case Stmt::ObjCStringLiteralClass:
1771  case Stmt::StringLiteralClass: {
1772    const StringLiteral *StrE = NULL;
1773
1774    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1775      StrE = ObjCFExpr->getString();
1776    else
1777      StrE = cast<StringLiteral>(E);
1778
1779    if (StrE) {
1780      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
1781                        firstDataArg, Type, inFunctionCall, CallType);
1782      return SLCT_CheckedLiteral;
1783    }
1784
1785    return SLCT_NotALiteral;
1786  }
1787
1788  default:
1789    return SLCT_NotALiteral;
1790  }
1791}
1792
1793void
1794Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1795                            const Expr * const *ExprArgs,
1796                            SourceLocation CallSiteLoc) {
1797  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1798                                  e = NonNull->args_end();
1799       i != e; ++i) {
1800    const Expr *ArgExpr = ExprArgs[*i];
1801    if (ArgExpr->isNullPointerConstant(Context,
1802                                       Expr::NPC_ValueDependentIsNotNull))
1803      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1804  }
1805}
1806
1807Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1808  return llvm::StringSwitch<FormatStringType>(Format->getType())
1809  .Case("scanf", FST_Scanf)
1810  .Cases("printf", "printf0", FST_Printf)
1811  .Cases("NSString", "CFString", FST_NSString)
1812  .Case("strftime", FST_Strftime)
1813  .Case("strfmon", FST_Strfmon)
1814  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1815  .Default(FST_Unknown);
1816}
1817
1818/// CheckFormatArguments - Check calls to printf and scanf (and similar
1819/// functions) for correct use of format strings.
1820/// Returns true if a format string has been fully checked.
1821bool Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
1822                                unsigned NumArgs, bool IsCXXMember,
1823                                VariadicCallType CallType,
1824                                SourceLocation Loc, SourceRange Range) {
1825  FormatStringInfo FSI;
1826  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
1827    return CheckFormatArguments(Args, NumArgs, FSI.HasVAListArg, FSI.FormatIdx,
1828                                FSI.FirstDataArg, GetFormatStringType(Format),
1829                                CallType, Loc, Range);
1830  return false;
1831}
1832
1833bool Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
1834                                bool HasVAListArg, unsigned format_idx,
1835                                unsigned firstDataArg, FormatStringType Type,
1836                                VariadicCallType CallType,
1837                                SourceLocation Loc, SourceRange Range) {
1838  // CHECK: printf/scanf-like function is called with no format string.
1839  if (format_idx >= NumArgs) {
1840    Diag(Loc, diag::warn_missing_format_string) << Range;
1841    return false;
1842  }
1843
1844  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1845
1846  // CHECK: format string is not a string literal.
1847  //
1848  // Dynamically generated format strings are difficult to
1849  // automatically vet at compile time.  Requiring that format strings
1850  // are string literals: (1) permits the checking of format strings by
1851  // the compiler and thereby (2) can practically remove the source of
1852  // many format string exploits.
1853
1854  // Format string can be either ObjC string (e.g. @"%d") or
1855  // C string (e.g. "%d")
1856  // ObjC string uses the same format specifiers as C string, so we can use
1857  // the same format string checking logic for both ObjC and C strings.
1858  StringLiteralCheckType CT =
1859      checkFormatStringExpr(OrigFormatExpr, Args, NumArgs, HasVAListArg,
1860                            format_idx, firstDataArg, Type, CallType);
1861  if (CT != SLCT_NotALiteral)
1862    // Literal format string found, check done!
1863    return CT == SLCT_CheckedLiteral;
1864
1865  // Strftime is particular as it always uses a single 'time' argument,
1866  // so it is safe to pass a non-literal string.
1867  if (Type == FST_Strftime)
1868    return false;
1869
1870  // Do not emit diag when the string param is a macro expansion and the
1871  // format is either NSString or CFString. This is a hack to prevent
1872  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1873  // which are usually used in place of NS and CF string literals.
1874  if (Type == FST_NSString &&
1875      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
1876    return false;
1877
1878  // If there are no arguments specified, warn with -Wformat-security, otherwise
1879  // warn only with -Wformat-nonliteral.
1880  if (NumArgs == format_idx+1)
1881    Diag(Args[format_idx]->getLocStart(),
1882         diag::warn_format_nonliteral_noargs)
1883      << OrigFormatExpr->getSourceRange();
1884  else
1885    Diag(Args[format_idx]->getLocStart(),
1886         diag::warn_format_nonliteral)
1887           << OrigFormatExpr->getSourceRange();
1888  return false;
1889}
1890
1891namespace {
1892class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1893protected:
1894  Sema &S;
1895  const StringLiteral *FExpr;
1896  const Expr *OrigFormatExpr;
1897  const unsigned FirstDataArg;
1898  const unsigned NumDataArgs;
1899  const char *Beg; // Start of format string.
1900  const bool HasVAListArg;
1901  const Expr * const *Args;
1902  const unsigned NumArgs;
1903  unsigned FormatIdx;
1904  llvm::BitVector CoveredArgs;
1905  bool usesPositionalArgs;
1906  bool atFirstArg;
1907  bool inFunctionCall;
1908  Sema::VariadicCallType CallType;
1909public:
1910  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1911                     const Expr *origFormatExpr, unsigned firstDataArg,
1912                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
1913                     Expr **args, unsigned numArgs,
1914                     unsigned formatIdx, bool inFunctionCall,
1915                     Sema::VariadicCallType callType)
1916    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1917      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
1918      Beg(beg), HasVAListArg(hasVAListArg),
1919      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
1920      usesPositionalArgs(false), atFirstArg(true),
1921      inFunctionCall(inFunctionCall), CallType(callType) {
1922        CoveredArgs.resize(numDataArgs);
1923        CoveredArgs.reset();
1924      }
1925
1926  void DoneProcessing();
1927
1928  void HandleIncompleteSpecifier(const char *startSpecifier,
1929                                 unsigned specifierLen);
1930
1931  void HandleNonStandardLengthModifier(
1932      const analyze_format_string::LengthModifier &LM,
1933      const char *startSpecifier, unsigned specifierLen);
1934
1935  void HandleNonStandardConversionSpecifier(
1936      const analyze_format_string::ConversionSpecifier &CS,
1937      const char *startSpecifier, unsigned specifierLen);
1938
1939  void HandleNonStandardConversionSpecification(
1940      const analyze_format_string::LengthModifier &LM,
1941      const analyze_format_string::ConversionSpecifier &CS,
1942      const char *startSpecifier, unsigned specifierLen);
1943
1944  virtual void HandlePosition(const char *startPos, unsigned posLen);
1945
1946  virtual void HandleInvalidPosition(const char *startSpecifier,
1947                                     unsigned specifierLen,
1948                                     analyze_format_string::PositionContext p);
1949
1950  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1951
1952  void HandleNullChar(const char *nullCharacter);
1953
1954  template <typename Range>
1955  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1956                                   const Expr *ArgumentExpr,
1957                                   PartialDiagnostic PDiag,
1958                                   SourceLocation StringLoc,
1959                                   bool IsStringLocation, Range StringRange,
1960                                   FixItHint Fixit = FixItHint());
1961
1962protected:
1963  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1964                                        const char *startSpec,
1965                                        unsigned specifierLen,
1966                                        const char *csStart, unsigned csLen);
1967
1968  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
1969                                         const char *startSpec,
1970                                         unsigned specifierLen);
1971
1972  SourceRange getFormatStringRange();
1973  CharSourceRange getSpecifierRange(const char *startSpecifier,
1974                                    unsigned specifierLen);
1975  SourceLocation getLocationOfByte(const char *x);
1976
1977  const Expr *getDataArg(unsigned i) const;
1978
1979  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1980                    const analyze_format_string::ConversionSpecifier &CS,
1981                    const char *startSpecifier, unsigned specifierLen,
1982                    unsigned argIndex);
1983
1984  template <typename Range>
1985  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
1986                            bool IsStringLocation, Range StringRange,
1987                            FixItHint Fixit = FixItHint());
1988
1989  void CheckPositionalAndNonpositionalArgs(
1990      const analyze_format_string::FormatSpecifier *FS);
1991};
1992}
1993
1994SourceRange CheckFormatHandler::getFormatStringRange() {
1995  return OrigFormatExpr->getSourceRange();
1996}
1997
1998CharSourceRange CheckFormatHandler::
1999getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2000  SourceLocation Start = getLocationOfByte(startSpecifier);
2001  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2002
2003  // Advance the end SourceLocation by one due to half-open ranges.
2004  End = End.getLocWithOffset(1);
2005
2006  return CharSourceRange::getCharRange(Start, End);
2007}
2008
2009SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2010  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2011}
2012
2013void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2014                                                   unsigned specifierLen){
2015  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2016                       getLocationOfByte(startSpecifier),
2017                       /*IsStringLocation*/true,
2018                       getSpecifierRange(startSpecifier, specifierLen));
2019}
2020
2021void CheckFormatHandler::HandleNonStandardLengthModifier(
2022    const analyze_format_string::LengthModifier &LM,
2023    const char *startSpecifier, unsigned specifierLen) {
2024  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
2025                       << 0,
2026                       getLocationOfByte(LM.getStart()),
2027                       /*IsStringLocation*/true,
2028                       getSpecifierRange(startSpecifier, specifierLen));
2029}
2030
2031void CheckFormatHandler::HandleNonStandardConversionSpecifier(
2032    const analyze_format_string::ConversionSpecifier &CS,
2033    const char *startSpecifier, unsigned specifierLen) {
2034  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
2035                       << 1,
2036                       getLocationOfByte(CS.getStart()),
2037                       /*IsStringLocation*/true,
2038                       getSpecifierRange(startSpecifier, specifierLen));
2039}
2040
2041void CheckFormatHandler::HandleNonStandardConversionSpecification(
2042    const analyze_format_string::LengthModifier &LM,
2043    const analyze_format_string::ConversionSpecifier &CS,
2044    const char *startSpecifier, unsigned specifierLen) {
2045  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
2046                       << LM.toString() << CS.toString(),
2047                       getLocationOfByte(LM.getStart()),
2048                       /*IsStringLocation*/true,
2049                       getSpecifierRange(startSpecifier, specifierLen));
2050}
2051
2052void CheckFormatHandler::HandlePosition(const char *startPos,
2053                                        unsigned posLen) {
2054  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
2055                               getLocationOfByte(startPos),
2056                               /*IsStringLocation*/true,
2057                               getSpecifierRange(startPos, posLen));
2058}
2059
2060void
2061CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
2062                                     analyze_format_string::PositionContext p) {
2063  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
2064                         << (unsigned) p,
2065                       getLocationOfByte(startPos), /*IsStringLocation*/true,
2066                       getSpecifierRange(startPos, posLen));
2067}
2068
2069void CheckFormatHandler::HandleZeroPosition(const char *startPos,
2070                                            unsigned posLen) {
2071  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
2072                               getLocationOfByte(startPos),
2073                               /*IsStringLocation*/true,
2074                               getSpecifierRange(startPos, posLen));
2075}
2076
2077void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
2078  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
2079    // The presence of a null character is likely an error.
2080    EmitFormatDiagnostic(
2081      S.PDiag(diag::warn_printf_format_string_contains_null_char),
2082      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
2083      getFormatStringRange());
2084  }
2085}
2086
2087// Note that this may return NULL if there was an error parsing or building
2088// one of the argument expressions.
2089const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
2090  return Args[FirstDataArg + i];
2091}
2092
2093void CheckFormatHandler::DoneProcessing() {
2094    // Does the number of data arguments exceed the number of
2095    // format conversions in the format string?
2096  if (!HasVAListArg) {
2097      // Find any arguments that weren't covered.
2098    CoveredArgs.flip();
2099    signed notCoveredArg = CoveredArgs.find_first();
2100    if (notCoveredArg >= 0) {
2101      assert((unsigned)notCoveredArg < NumDataArgs);
2102      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
2103        SourceLocation Loc = E->getLocStart();
2104        if (!S.getSourceManager().isInSystemMacro(Loc)) {
2105          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
2106                               Loc, /*IsStringLocation*/false,
2107                               getFormatStringRange());
2108        }
2109      }
2110    }
2111  }
2112}
2113
2114bool
2115CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
2116                                                     SourceLocation Loc,
2117                                                     const char *startSpec,
2118                                                     unsigned specifierLen,
2119                                                     const char *csStart,
2120                                                     unsigned csLen) {
2121
2122  bool keepGoing = true;
2123  if (argIndex < NumDataArgs) {
2124    // Consider the argument coverered, even though the specifier doesn't
2125    // make sense.
2126    CoveredArgs.set(argIndex);
2127  }
2128  else {
2129    // If argIndex exceeds the number of data arguments we
2130    // don't issue a warning because that is just a cascade of warnings (and
2131    // they may have intended '%%' anyway). We don't want to continue processing
2132    // the format string after this point, however, as we will like just get
2133    // gibberish when trying to match arguments.
2134    keepGoing = false;
2135  }
2136
2137  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2138                         << StringRef(csStart, csLen),
2139                       Loc, /*IsStringLocation*/true,
2140                       getSpecifierRange(startSpec, specifierLen));
2141
2142  return keepGoing;
2143}
2144
2145void
2146CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2147                                                      const char *startSpec,
2148                                                      unsigned specifierLen) {
2149  EmitFormatDiagnostic(
2150    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2151    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2152}
2153
2154bool
2155CheckFormatHandler::CheckNumArgs(
2156  const analyze_format_string::FormatSpecifier &FS,
2157  const analyze_format_string::ConversionSpecifier &CS,
2158  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2159
2160  if (argIndex >= NumDataArgs) {
2161    PartialDiagnostic PDiag = FS.usesPositionalArg()
2162      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2163           << (argIndex+1) << NumDataArgs)
2164      : S.PDiag(diag::warn_printf_insufficient_data_args);
2165    EmitFormatDiagnostic(
2166      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2167      getSpecifierRange(startSpecifier, specifierLen));
2168    return false;
2169  }
2170  return true;
2171}
2172
2173template<typename Range>
2174void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2175                                              SourceLocation Loc,
2176                                              bool IsStringLocation,
2177                                              Range StringRange,
2178                                              FixItHint FixIt) {
2179  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2180                       Loc, IsStringLocation, StringRange, FixIt);
2181}
2182
2183/// \brief If the format string is not within the funcion call, emit a note
2184/// so that the function call and string are in diagnostic messages.
2185///
2186/// \param inFunctionCall if true, the format string is within the function
2187/// call and only one diagnostic message will be produced.  Otherwise, an
2188/// extra note will be emitted pointing to location of the format string.
2189///
2190/// \param ArgumentExpr the expression that is passed as the format string
2191/// argument in the function call.  Used for getting locations when two
2192/// diagnostics are emitted.
2193///
2194/// \param PDiag the callee should already have provided any strings for the
2195/// diagnostic message.  This function only adds locations and fixits
2196/// to diagnostics.
2197///
2198/// \param Loc primary location for diagnostic.  If two diagnostics are
2199/// required, one will be at Loc and a new SourceLocation will be created for
2200/// the other one.
2201///
2202/// \param IsStringLocation if true, Loc points to the format string should be
2203/// used for the note.  Otherwise, Loc points to the argument list and will
2204/// be used with PDiag.
2205///
2206/// \param StringRange some or all of the string to highlight.  This is
2207/// templated so it can accept either a CharSourceRange or a SourceRange.
2208///
2209/// \param Fixit optional fix it hint for the format string.
2210template<typename Range>
2211void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2212                                              const Expr *ArgumentExpr,
2213                                              PartialDiagnostic PDiag,
2214                                              SourceLocation Loc,
2215                                              bool IsStringLocation,
2216                                              Range StringRange,
2217                                              FixItHint FixIt) {
2218  if (InFunctionCall)
2219    S.Diag(Loc, PDiag) << StringRange << FixIt;
2220  else {
2221    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2222      << ArgumentExpr->getSourceRange();
2223    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2224           diag::note_format_string_defined)
2225      << StringRange << FixIt;
2226  }
2227}
2228
2229//===--- CHECK: Printf format string checking ------------------------------===//
2230
2231namespace {
2232class CheckPrintfHandler : public CheckFormatHandler {
2233  bool ObjCContext;
2234public:
2235  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2236                     const Expr *origFormatExpr, unsigned firstDataArg,
2237                     unsigned numDataArgs, bool isObjC,
2238                     const char *beg, bool hasVAListArg,
2239                     Expr **Args, unsigned NumArgs,
2240                     unsigned formatIdx, bool inFunctionCall,
2241                     Sema::VariadicCallType CallType)
2242  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2243                       numDataArgs, beg, hasVAListArg, Args, NumArgs,
2244                       formatIdx, inFunctionCall, CallType), ObjCContext(isObjC)
2245  {}
2246
2247
2248  bool HandleInvalidPrintfConversionSpecifier(
2249                                      const analyze_printf::PrintfSpecifier &FS,
2250                                      const char *startSpecifier,
2251                                      unsigned specifierLen);
2252
2253  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2254                             const char *startSpecifier,
2255                             unsigned specifierLen);
2256  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2257                       const char *StartSpecifier,
2258                       unsigned SpecifierLen,
2259                       const Expr *E);
2260
2261  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2262                    const char *startSpecifier, unsigned specifierLen);
2263  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2264                           const analyze_printf::OptionalAmount &Amt,
2265                           unsigned type,
2266                           const char *startSpecifier, unsigned specifierLen);
2267  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2268                  const analyze_printf::OptionalFlag &flag,
2269                  const char *startSpecifier, unsigned specifierLen);
2270  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2271                         const analyze_printf::OptionalFlag &ignoredFlag,
2272                         const analyze_printf::OptionalFlag &flag,
2273                         const char *startSpecifier, unsigned specifierLen);
2274  bool checkForCStrMembers(const analyze_printf::ArgTypeResult &ATR,
2275                           const Expr *E, const CharSourceRange &CSR);
2276
2277};
2278}
2279
2280bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2281                                      const analyze_printf::PrintfSpecifier &FS,
2282                                      const char *startSpecifier,
2283                                      unsigned specifierLen) {
2284  const analyze_printf::PrintfConversionSpecifier &CS =
2285    FS.getConversionSpecifier();
2286
2287  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2288                                          getLocationOfByte(CS.getStart()),
2289                                          startSpecifier, specifierLen,
2290                                          CS.getStart(), CS.getLength());
2291}
2292
2293bool CheckPrintfHandler::HandleAmount(
2294                               const analyze_format_string::OptionalAmount &Amt,
2295                               unsigned k, const char *startSpecifier,
2296                               unsigned specifierLen) {
2297
2298  if (Amt.hasDataArgument()) {
2299    if (!HasVAListArg) {
2300      unsigned argIndex = Amt.getArgIndex();
2301      if (argIndex >= NumDataArgs) {
2302        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2303                               << k,
2304                             getLocationOfByte(Amt.getStart()),
2305                             /*IsStringLocation*/true,
2306                             getSpecifierRange(startSpecifier, specifierLen));
2307        // Don't do any more checking.  We will just emit
2308        // spurious errors.
2309        return false;
2310      }
2311
2312      // Type check the data argument.  It should be an 'int'.
2313      // Although not in conformance with C99, we also allow the argument to be
2314      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2315      // doesn't emit a warning for that case.
2316      CoveredArgs.set(argIndex);
2317      const Expr *Arg = getDataArg(argIndex);
2318      if (!Arg)
2319        return false;
2320
2321      QualType T = Arg->getType();
2322
2323      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
2324      assert(ATR.isValid());
2325
2326      if (!ATR.matchesType(S.Context, T)) {
2327        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2328                               << k << ATR.getRepresentativeTypeName(S.Context)
2329                               << T << Arg->getSourceRange(),
2330                             getLocationOfByte(Amt.getStart()),
2331                             /*IsStringLocation*/true,
2332                             getSpecifierRange(startSpecifier, specifierLen));
2333        // Don't do any more checking.  We will just emit
2334        // spurious errors.
2335        return false;
2336      }
2337    }
2338  }
2339  return true;
2340}
2341
2342void CheckPrintfHandler::HandleInvalidAmount(
2343                                      const analyze_printf::PrintfSpecifier &FS,
2344                                      const analyze_printf::OptionalAmount &Amt,
2345                                      unsigned type,
2346                                      const char *startSpecifier,
2347                                      unsigned specifierLen) {
2348  const analyze_printf::PrintfConversionSpecifier &CS =
2349    FS.getConversionSpecifier();
2350
2351  FixItHint fixit =
2352    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2353      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2354                                 Amt.getConstantLength()))
2355      : FixItHint();
2356
2357  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2358                         << type << CS.toString(),
2359                       getLocationOfByte(Amt.getStart()),
2360                       /*IsStringLocation*/true,
2361                       getSpecifierRange(startSpecifier, specifierLen),
2362                       fixit);
2363}
2364
2365void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2366                                    const analyze_printf::OptionalFlag &flag,
2367                                    const char *startSpecifier,
2368                                    unsigned specifierLen) {
2369  // Warn about pointless flag with a fixit removal.
2370  const analyze_printf::PrintfConversionSpecifier &CS =
2371    FS.getConversionSpecifier();
2372  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2373                         << flag.toString() << CS.toString(),
2374                       getLocationOfByte(flag.getPosition()),
2375                       /*IsStringLocation*/true,
2376                       getSpecifierRange(startSpecifier, specifierLen),
2377                       FixItHint::CreateRemoval(
2378                         getSpecifierRange(flag.getPosition(), 1)));
2379}
2380
2381void CheckPrintfHandler::HandleIgnoredFlag(
2382                                const analyze_printf::PrintfSpecifier &FS,
2383                                const analyze_printf::OptionalFlag &ignoredFlag,
2384                                const analyze_printf::OptionalFlag &flag,
2385                                const char *startSpecifier,
2386                                unsigned specifierLen) {
2387  // Warn about ignored flag with a fixit removal.
2388  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2389                         << ignoredFlag.toString() << flag.toString(),
2390                       getLocationOfByte(ignoredFlag.getPosition()),
2391                       /*IsStringLocation*/true,
2392                       getSpecifierRange(startSpecifier, specifierLen),
2393                       FixItHint::CreateRemoval(
2394                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2395}
2396
2397// Determines if the specified is a C++ class or struct containing
2398// a member with the specified name and kind (e.g. a CXXMethodDecl named
2399// "c_str()").
2400template<typename MemberKind>
2401static llvm::SmallPtrSet<MemberKind*, 1>
2402CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
2403  const RecordType *RT = Ty->getAs<RecordType>();
2404  llvm::SmallPtrSet<MemberKind*, 1> Results;
2405
2406  if (!RT)
2407    return Results;
2408  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
2409  if (!RD)
2410    return Results;
2411
2412  LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
2413                 Sema::LookupMemberName);
2414
2415  // We just need to include all members of the right kind turned up by the
2416  // filter, at this point.
2417  if (S.LookupQualifiedName(R, RT->getDecl()))
2418    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
2419      NamedDecl *decl = (*I)->getUnderlyingDecl();
2420      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
2421        Results.insert(FK);
2422    }
2423  return Results;
2424}
2425
2426// Check if a (w)string was passed when a (w)char* was needed, and offer a
2427// better diagnostic if so. ATR is assumed to be valid.
2428// Returns true when a c_str() conversion method is found.
2429bool CheckPrintfHandler::checkForCStrMembers(
2430    const analyze_printf::ArgTypeResult &ATR, const Expr *E,
2431    const CharSourceRange &CSR) {
2432  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
2433
2434  MethodSet Results =
2435      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
2436
2437  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
2438       MI != ME; ++MI) {
2439    const CXXMethodDecl *Method = *MI;
2440    if (Method->getNumParams() == 0 &&
2441          ATR.matchesType(S.Context, Method->getResultType())) {
2442      // FIXME: Suggest parens if the expression needs them.
2443      SourceLocation EndLoc =
2444          S.getPreprocessor().getLocForEndOfToken(E->getLocEnd());
2445      S.Diag(E->getLocStart(), diag::note_printf_c_str)
2446          << "c_str()"
2447          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
2448      return true;
2449    }
2450  }
2451
2452  return false;
2453}
2454
2455bool
2456CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2457                                            &FS,
2458                                          const char *startSpecifier,
2459                                          unsigned specifierLen) {
2460
2461  using namespace analyze_format_string;
2462  using namespace analyze_printf;
2463  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2464
2465  if (FS.consumesDataArgument()) {
2466    if (atFirstArg) {
2467        atFirstArg = false;
2468        usesPositionalArgs = FS.usesPositionalArg();
2469    }
2470    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2471      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2472                                        startSpecifier, specifierLen);
2473      return false;
2474    }
2475  }
2476
2477  // First check if the field width, precision, and conversion specifier
2478  // have matching data arguments.
2479  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2480                    startSpecifier, specifierLen)) {
2481    return false;
2482  }
2483
2484  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2485                    startSpecifier, specifierLen)) {
2486    return false;
2487  }
2488
2489  if (!CS.consumesDataArgument()) {
2490    // FIXME: Technically specifying a precision or field width here
2491    // makes no sense.  Worth issuing a warning at some point.
2492    return true;
2493  }
2494
2495  // Consume the argument.
2496  unsigned argIndex = FS.getArgIndex();
2497  if (argIndex < NumDataArgs) {
2498    // The check to see if the argIndex is valid will come later.
2499    // We set the bit here because we may exit early from this
2500    // function if we encounter some other error.
2501    CoveredArgs.set(argIndex);
2502  }
2503
2504  // Check for using an Objective-C specific conversion specifier
2505  // in a non-ObjC literal.
2506  if (!ObjCContext && CS.isObjCArg()) {
2507    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2508                                                  specifierLen);
2509  }
2510
2511  // Check for invalid use of field width
2512  if (!FS.hasValidFieldWidth()) {
2513    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2514        startSpecifier, specifierLen);
2515  }
2516
2517  // Check for invalid use of precision
2518  if (!FS.hasValidPrecision()) {
2519    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2520        startSpecifier, specifierLen);
2521  }
2522
2523  // Check each flag does not conflict with any other component.
2524  if (!FS.hasValidThousandsGroupingPrefix())
2525    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2526  if (!FS.hasValidLeadingZeros())
2527    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2528  if (!FS.hasValidPlusPrefix())
2529    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2530  if (!FS.hasValidSpacePrefix())
2531    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2532  if (!FS.hasValidAlternativeForm())
2533    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2534  if (!FS.hasValidLeftJustified())
2535    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2536
2537  // Check that flags are not ignored by another flag
2538  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2539    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2540        startSpecifier, specifierLen);
2541  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2542    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2543            startSpecifier, specifierLen);
2544
2545  // Check the length modifier is valid with the given conversion specifier.
2546  const LengthModifier &LM = FS.getLengthModifier();
2547  if (!FS.hasValidLengthModifier())
2548    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2549                           << LM.toString() << CS.toString(),
2550                         getLocationOfByte(LM.getStart()),
2551                         /*IsStringLocation*/true,
2552                         getSpecifierRange(startSpecifier, specifierLen),
2553                         FixItHint::CreateRemoval(
2554                           getSpecifierRange(LM.getStart(),
2555                                             LM.getLength())));
2556  if (!FS.hasStandardLengthModifier())
2557    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2558  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2559    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2560  if (!FS.hasStandardLengthConversionCombination())
2561    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2562                                             specifierLen);
2563
2564  // Are we using '%n'?
2565  if (CS.getKind() == ConversionSpecifier::nArg) {
2566    // Issue a warning about this being a possible security issue.
2567    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
2568                         getLocationOfByte(CS.getStart()),
2569                         /*IsStringLocation*/true,
2570                         getSpecifierRange(startSpecifier, specifierLen));
2571  }
2572
2573  // The remaining checks depend on the data arguments.
2574  if (HasVAListArg)
2575    return true;
2576
2577  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2578    return false;
2579
2580  const Expr *Arg = getDataArg(argIndex);
2581  if (!Arg)
2582    return true;
2583
2584  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
2585}
2586
2587bool
2588CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
2589                                    const char *StartSpecifier,
2590                                    unsigned SpecifierLen,
2591                                    const Expr *E) {
2592  using namespace analyze_format_string;
2593  using namespace analyze_printf;
2594  // Now type check the data expression that matches the
2595  // format specifier.
2596  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context,
2597                                                           ObjCContext);
2598  if (ATR.isValid() && !ATR.matchesType(S.Context, E->getType())) {
2599    // Look through argument promotions for our error message's reported type.
2600    // This includes the integral and floating promotions, but excludes array
2601    // and function pointer decay; seeing that an argument intended to be a
2602    // string has type 'char [6]' is probably more confusing than 'char *'.
2603    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2604      if (ICE->getCastKind() == CK_IntegralCast ||
2605          ICE->getCastKind() == CK_FloatingCast) {
2606        E = ICE->getSubExpr();
2607
2608        // Check if we didn't match because of an implicit cast from a 'char'
2609        // or 'short' to an 'int'.  This is done because printf is a varargs
2610        // function.
2611        if (ICE->getType() == S.Context.IntTy ||
2612            ICE->getType() == S.Context.UnsignedIntTy) {
2613          // All further checking is done on the subexpression.
2614          if (ATR.matchesType(S.Context, E->getType()))
2615            return true;
2616        }
2617      }
2618    }
2619
2620    // We may be able to offer a FixItHint if it is a supported type.
2621    PrintfSpecifier fixedFS = FS;
2622    bool success = fixedFS.fixType(E->getType(), S.getLangOpts(),
2623                                   S.Context, ObjCContext);
2624
2625    if (success) {
2626      // Get the fix string from the fixed format specifier
2627      SmallString<16> buf;
2628      llvm::raw_svector_ostream os(buf);
2629      fixedFS.toString(os);
2630
2631      EmitFormatDiagnostic(
2632        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2633          << ATR.getRepresentativeTypeName(S.Context) << E->getType()
2634          << E->getSourceRange(),
2635        E->getLocStart(),
2636        /*IsStringLocation*/false,
2637        getSpecifierRange(StartSpecifier, SpecifierLen),
2638        FixItHint::CreateReplacement(
2639          getSpecifierRange(StartSpecifier, SpecifierLen),
2640          os.str()));
2641    } else {
2642      const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
2643                                                     SpecifierLen);
2644      // Since the warning for passing non-POD types to variadic functions
2645      // was deferred until now, we emit a warning for non-POD
2646      // arguments here.
2647      if (S.isValidVarArgType(E->getType()) == Sema::VAK_Invalid) {
2648        unsigned DiagKind;
2649        if (E->getType()->isObjCObjectType())
2650          DiagKind = diag::err_cannot_pass_objc_interface_to_vararg_format;
2651        else
2652          DiagKind = diag::warn_non_pod_vararg_with_format_string;
2653
2654        EmitFormatDiagnostic(
2655          S.PDiag(DiagKind)
2656            << S.getLangOpts().CPlusPlus0x
2657            << E->getType()
2658            << CallType
2659            << ATR.getRepresentativeTypeName(S.Context)
2660            << CSR
2661            << E->getSourceRange(),
2662          E->getLocStart(), /*IsStringLocation*/false, CSR);
2663
2664        checkForCStrMembers(ATR, E, CSR);
2665      } else
2666        EmitFormatDiagnostic(
2667          S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2668            << ATR.getRepresentativeTypeName(S.Context) << E->getType()
2669            << CSR
2670            << E->getSourceRange(),
2671          E->getLocStart(), /*IsStringLocation*/false, CSR);
2672    }
2673  }
2674
2675  return true;
2676}
2677
2678//===--- CHECK: Scanf format string checking ------------------------------===//
2679
2680namespace {
2681class CheckScanfHandler : public CheckFormatHandler {
2682public:
2683  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2684                    const Expr *origFormatExpr, unsigned firstDataArg,
2685                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
2686                    Expr **Args, unsigned NumArgs,
2687                    unsigned formatIdx, bool inFunctionCall,
2688                    Sema::VariadicCallType CallType)
2689  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2690                       numDataArgs, beg, hasVAListArg,
2691                       Args, NumArgs, formatIdx, inFunctionCall, CallType)
2692  {}
2693
2694  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2695                            const char *startSpecifier,
2696                            unsigned specifierLen);
2697
2698  bool HandleInvalidScanfConversionSpecifier(
2699          const analyze_scanf::ScanfSpecifier &FS,
2700          const char *startSpecifier,
2701          unsigned specifierLen);
2702
2703  void HandleIncompleteScanList(const char *start, const char *end);
2704};
2705}
2706
2707void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2708                                                 const char *end) {
2709  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2710                       getLocationOfByte(end), /*IsStringLocation*/true,
2711                       getSpecifierRange(start, end - start));
2712}
2713
2714bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2715                                        const analyze_scanf::ScanfSpecifier &FS,
2716                                        const char *startSpecifier,
2717                                        unsigned specifierLen) {
2718
2719  const analyze_scanf::ScanfConversionSpecifier &CS =
2720    FS.getConversionSpecifier();
2721
2722  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2723                                          getLocationOfByte(CS.getStart()),
2724                                          startSpecifier, specifierLen,
2725                                          CS.getStart(), CS.getLength());
2726}
2727
2728bool CheckScanfHandler::HandleScanfSpecifier(
2729                                       const analyze_scanf::ScanfSpecifier &FS,
2730                                       const char *startSpecifier,
2731                                       unsigned specifierLen) {
2732
2733  using namespace analyze_scanf;
2734  using namespace analyze_format_string;
2735
2736  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2737
2738  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2739  // be used to decide if we are using positional arguments consistently.
2740  if (FS.consumesDataArgument()) {
2741    if (atFirstArg) {
2742      atFirstArg = false;
2743      usesPositionalArgs = FS.usesPositionalArg();
2744    }
2745    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2746      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2747                                        startSpecifier, specifierLen);
2748      return false;
2749    }
2750  }
2751
2752  // Check if the field with is non-zero.
2753  const OptionalAmount &Amt = FS.getFieldWidth();
2754  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2755    if (Amt.getConstantAmount() == 0) {
2756      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2757                                                   Amt.getConstantLength());
2758      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2759                           getLocationOfByte(Amt.getStart()),
2760                           /*IsStringLocation*/true, R,
2761                           FixItHint::CreateRemoval(R));
2762    }
2763  }
2764
2765  if (!FS.consumesDataArgument()) {
2766    // FIXME: Technically specifying a precision or field width here
2767    // makes no sense.  Worth issuing a warning at some point.
2768    return true;
2769  }
2770
2771  // Consume the argument.
2772  unsigned argIndex = FS.getArgIndex();
2773  if (argIndex < NumDataArgs) {
2774      // The check to see if the argIndex is valid will come later.
2775      // We set the bit here because we may exit early from this
2776      // function if we encounter some other error.
2777    CoveredArgs.set(argIndex);
2778  }
2779
2780  // Check the length modifier is valid with the given conversion specifier.
2781  const LengthModifier &LM = FS.getLengthModifier();
2782  if (!FS.hasValidLengthModifier()) {
2783    const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength());
2784    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2785                         << LM.toString() << CS.toString()
2786                         << getSpecifierRange(startSpecifier, specifierLen),
2787                         getLocationOfByte(LM.getStart()),
2788                         /*IsStringLocation*/true, R,
2789                         FixItHint::CreateRemoval(R));
2790  }
2791
2792  if (!FS.hasStandardLengthModifier())
2793    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2794  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2795    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2796  if (!FS.hasStandardLengthConversionCombination())
2797    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2798                                             specifierLen);
2799
2800  // The remaining checks depend on the data arguments.
2801  if (HasVAListArg)
2802    return true;
2803
2804  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2805    return false;
2806
2807  // Check that the argument type matches the format specifier.
2808  const Expr *Ex = getDataArg(argIndex);
2809  if (!Ex)
2810    return true;
2811
2812  const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context);
2813  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2814    ScanfSpecifier fixedFS = FS;
2815    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2816                                   S.Context);
2817
2818    if (success) {
2819      // Get the fix string from the fixed format specifier.
2820      SmallString<128> buf;
2821      llvm::raw_svector_ostream os(buf);
2822      fixedFS.toString(os);
2823
2824      EmitFormatDiagnostic(
2825        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2826          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2827          << Ex->getSourceRange(),
2828        Ex->getLocStart(),
2829        /*IsStringLocation*/false,
2830        getSpecifierRange(startSpecifier, specifierLen),
2831        FixItHint::CreateReplacement(
2832          getSpecifierRange(startSpecifier, specifierLen),
2833          os.str()));
2834    } else {
2835      EmitFormatDiagnostic(
2836        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2837          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2838          << Ex->getSourceRange(),
2839        Ex->getLocStart(),
2840        /*IsStringLocation*/false,
2841        getSpecifierRange(startSpecifier, specifierLen));
2842    }
2843  }
2844
2845  return true;
2846}
2847
2848void Sema::CheckFormatString(const StringLiteral *FExpr,
2849                             const Expr *OrigFormatExpr,
2850                             Expr **Args, unsigned NumArgs,
2851                             bool HasVAListArg, unsigned format_idx,
2852                             unsigned firstDataArg, FormatStringType Type,
2853                             bool inFunctionCall, VariadicCallType CallType) {
2854
2855  // CHECK: is the format string a wide literal?
2856  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
2857    CheckFormatHandler::EmitFormatDiagnostic(
2858      *this, inFunctionCall, Args[format_idx],
2859      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
2860      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2861    return;
2862  }
2863
2864  // Str - The format string.  NOTE: this is NOT null-terminated!
2865  StringRef StrRef = FExpr->getString();
2866  const char *Str = StrRef.data();
2867  unsigned StrLen = StrRef.size();
2868  const unsigned numDataArgs = NumArgs - firstDataArg;
2869
2870  // CHECK: empty format string?
2871  if (StrLen == 0 && numDataArgs > 0) {
2872    CheckFormatHandler::EmitFormatDiagnostic(
2873      *this, inFunctionCall, Args[format_idx],
2874      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
2875      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2876    return;
2877  }
2878
2879  if (Type == FST_Printf || Type == FST_NSString) {
2880    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2881                         numDataArgs, (Type == FST_NSString),
2882                         Str, HasVAListArg, Args, NumArgs, format_idx,
2883                         inFunctionCall, CallType);
2884
2885    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
2886                                                  getLangOpts()))
2887      H.DoneProcessing();
2888  } else if (Type == FST_Scanf) {
2889    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
2890                        Str, HasVAListArg, Args, NumArgs, format_idx,
2891                        inFunctionCall, CallType);
2892
2893    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
2894                                                 getLangOpts()))
2895      H.DoneProcessing();
2896  } // TODO: handle other formats
2897}
2898
2899//===--- CHECK: Standard memory functions ---------------------------------===//
2900
2901/// \brief Determine whether the given type is a dynamic class type (e.g.,
2902/// whether it has a vtable).
2903static bool isDynamicClassType(QualType T) {
2904  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
2905    if (CXXRecordDecl *Definition = Record->getDefinition())
2906      if (Definition->isDynamicClass())
2907        return true;
2908
2909  return false;
2910}
2911
2912/// \brief If E is a sizeof expression, returns its argument expression,
2913/// otherwise returns NULL.
2914static const Expr *getSizeOfExprArg(const Expr* E) {
2915  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2916      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2917    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
2918      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
2919
2920  return 0;
2921}
2922
2923/// \brief If E is a sizeof expression, returns its argument type.
2924static QualType getSizeOfArgType(const Expr* E) {
2925  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2926      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2927    if (SizeOf->getKind() == clang::UETT_SizeOf)
2928      return SizeOf->getTypeOfArgument();
2929
2930  return QualType();
2931}
2932
2933/// \brief Check for dangerous or invalid arguments to memset().
2934///
2935/// This issues warnings on known problematic, dangerous or unspecified
2936/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
2937/// function calls.
2938///
2939/// \param Call The call expression to diagnose.
2940void Sema::CheckMemaccessArguments(const CallExpr *Call,
2941                                   unsigned BId,
2942                                   IdentifierInfo *FnName) {
2943  assert(BId != 0);
2944
2945  // It is possible to have a non-standard definition of memset.  Validate
2946  // we have enough arguments, and if not, abort further checking.
2947  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
2948  if (Call->getNumArgs() < ExpectedNumArgs)
2949    return;
2950
2951  unsigned LastArg = (BId == Builtin::BImemset ||
2952                      BId == Builtin::BIstrndup ? 1 : 2);
2953  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
2954  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
2955
2956  // We have special checking when the length is a sizeof expression.
2957  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
2958  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
2959  llvm::FoldingSetNodeID SizeOfArgID;
2960
2961  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
2962    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
2963    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
2964
2965    QualType DestTy = Dest->getType();
2966    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
2967      QualType PointeeTy = DestPtrTy->getPointeeType();
2968
2969      // Never warn about void type pointers. This can be used to suppress
2970      // false positives.
2971      if (PointeeTy->isVoidType())
2972        continue;
2973
2974      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
2975      // actually comparing the expressions for equality. Because computing the
2976      // expression IDs can be expensive, we only do this if the diagnostic is
2977      // enabled.
2978      if (SizeOfArg &&
2979          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
2980                                   SizeOfArg->getExprLoc())) {
2981        // We only compute IDs for expressions if the warning is enabled, and
2982        // cache the sizeof arg's ID.
2983        if (SizeOfArgID == llvm::FoldingSetNodeID())
2984          SizeOfArg->Profile(SizeOfArgID, Context, true);
2985        llvm::FoldingSetNodeID DestID;
2986        Dest->Profile(DestID, Context, true);
2987        if (DestID == SizeOfArgID) {
2988          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
2989          //       over sizeof(src) as well.
2990          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
2991          StringRef ReadableName = FnName->getName();
2992
2993          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
2994            if (UnaryOp->getOpcode() == UO_AddrOf)
2995              ActionIdx = 1; // If its an address-of operator, just remove it.
2996          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
2997            ActionIdx = 2; // If the pointee's size is sizeof(char),
2998                           // suggest an explicit length.
2999
3000          // If the function is defined as a builtin macro, do not show macro
3001          // expansion.
3002          SourceLocation SL = SizeOfArg->getExprLoc();
3003          SourceRange DSR = Dest->getSourceRange();
3004          SourceRange SSR = SizeOfArg->getSourceRange();
3005          SourceManager &SM  = PP.getSourceManager();
3006
3007          if (SM.isMacroArgExpansion(SL)) {
3008            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
3009            SL = SM.getSpellingLoc(SL);
3010            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
3011                             SM.getSpellingLoc(DSR.getEnd()));
3012            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
3013                             SM.getSpellingLoc(SSR.getEnd()));
3014          }
3015
3016          DiagRuntimeBehavior(SL, SizeOfArg,
3017                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
3018                                << ReadableName
3019                                << PointeeTy
3020                                << DestTy
3021                                << DSR
3022                                << SSR);
3023          DiagRuntimeBehavior(SL, SizeOfArg,
3024                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
3025                                << ActionIdx
3026                                << SSR);
3027
3028          break;
3029        }
3030      }
3031
3032      // Also check for cases where the sizeof argument is the exact same
3033      // type as the memory argument, and where it points to a user-defined
3034      // record type.
3035      if (SizeOfArgTy != QualType()) {
3036        if (PointeeTy->isRecordType() &&
3037            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
3038          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
3039                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
3040                                << FnName << SizeOfArgTy << ArgIdx
3041                                << PointeeTy << Dest->getSourceRange()
3042                                << LenExpr->getSourceRange());
3043          break;
3044        }
3045      }
3046
3047      // Always complain about dynamic classes.
3048      if (isDynamicClassType(PointeeTy)) {
3049
3050        unsigned OperationType = 0;
3051        // "overwritten" if we're warning about the destination for any call
3052        // but memcmp; otherwise a verb appropriate to the call.
3053        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
3054          if (BId == Builtin::BImemcpy)
3055            OperationType = 1;
3056          else if(BId == Builtin::BImemmove)
3057            OperationType = 2;
3058          else if (BId == Builtin::BImemcmp)
3059            OperationType = 3;
3060        }
3061
3062        DiagRuntimeBehavior(
3063          Dest->getExprLoc(), Dest,
3064          PDiag(diag::warn_dyn_class_memaccess)
3065            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
3066            << FnName << PointeeTy
3067            << OperationType
3068            << Call->getCallee()->getSourceRange());
3069      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
3070               BId != Builtin::BImemset)
3071        DiagRuntimeBehavior(
3072          Dest->getExprLoc(), Dest,
3073          PDiag(diag::warn_arc_object_memaccess)
3074            << ArgIdx << FnName << PointeeTy
3075            << Call->getCallee()->getSourceRange());
3076      else
3077        continue;
3078
3079      DiagRuntimeBehavior(
3080        Dest->getExprLoc(), Dest,
3081        PDiag(diag::note_bad_memaccess_silence)
3082          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
3083      break;
3084    }
3085  }
3086}
3087
3088// A little helper routine: ignore addition and subtraction of integer literals.
3089// This intentionally does not ignore all integer constant expressions because
3090// we don't want to remove sizeof().
3091static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
3092  Ex = Ex->IgnoreParenCasts();
3093
3094  for (;;) {
3095    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
3096    if (!BO || !BO->isAdditiveOp())
3097      break;
3098
3099    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
3100    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
3101
3102    if (isa<IntegerLiteral>(RHS))
3103      Ex = LHS;
3104    else if (isa<IntegerLiteral>(LHS))
3105      Ex = RHS;
3106    else
3107      break;
3108  }
3109
3110  return Ex;
3111}
3112
3113// Warn if the user has made the 'size' argument to strlcpy or strlcat
3114// be the size of the source, instead of the destination.
3115void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
3116                                    IdentifierInfo *FnName) {
3117
3118  // Don't crash if the user has the wrong number of arguments
3119  if (Call->getNumArgs() != 3)
3120    return;
3121
3122  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
3123  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
3124  const Expr *CompareWithSrc = NULL;
3125
3126  // Look for 'strlcpy(dst, x, sizeof(x))'
3127  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
3128    CompareWithSrc = Ex;
3129  else {
3130    // Look for 'strlcpy(dst, x, strlen(x))'
3131    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
3132      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
3133          && SizeCall->getNumArgs() == 1)
3134        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
3135    }
3136  }
3137
3138  if (!CompareWithSrc)
3139    return;
3140
3141  // Determine if the argument to sizeof/strlen is equal to the source
3142  // argument.  In principle there's all kinds of things you could do
3143  // here, for instance creating an == expression and evaluating it with
3144  // EvaluateAsBooleanCondition, but this uses a more direct technique:
3145  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
3146  if (!SrcArgDRE)
3147    return;
3148
3149  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
3150  if (!CompareWithSrcDRE ||
3151      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
3152    return;
3153
3154  const Expr *OriginalSizeArg = Call->getArg(2);
3155  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
3156    << OriginalSizeArg->getSourceRange() << FnName;
3157
3158  // Output a FIXIT hint if the destination is an array (rather than a
3159  // pointer to an array).  This could be enhanced to handle some
3160  // pointers if we know the actual size, like if DstArg is 'array+2'
3161  // we could say 'sizeof(array)-2'.
3162  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
3163  QualType DstArgTy = DstArg->getType();
3164
3165  // Only handle constant-sized or VLAs, but not flexible members.
3166  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
3167    // Only issue the FIXIT for arrays of size > 1.
3168    if (CAT->getSize().getSExtValue() <= 1)
3169      return;
3170  } else if (!DstArgTy->isVariableArrayType()) {
3171    return;
3172  }
3173
3174  SmallString<128> sizeString;
3175  llvm::raw_svector_ostream OS(sizeString);
3176  OS << "sizeof(";
3177  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
3178  OS << ")";
3179
3180  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
3181    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
3182                                    OS.str());
3183}
3184
3185/// Check if two expressions refer to the same declaration.
3186static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
3187  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
3188    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
3189      return D1->getDecl() == D2->getDecl();
3190  return false;
3191}
3192
3193static const Expr *getStrlenExprArg(const Expr *E) {
3194  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
3195    const FunctionDecl *FD = CE->getDirectCallee();
3196    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
3197      return 0;
3198    return CE->getArg(0)->IgnoreParenCasts();
3199  }
3200  return 0;
3201}
3202
3203// Warn on anti-patterns as the 'size' argument to strncat.
3204// The correct size argument should look like following:
3205//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
3206void Sema::CheckStrncatArguments(const CallExpr *CE,
3207                                 IdentifierInfo *FnName) {
3208  // Don't crash if the user has the wrong number of arguments.
3209  if (CE->getNumArgs() < 3)
3210    return;
3211  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
3212  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
3213  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
3214
3215  // Identify common expressions, which are wrongly used as the size argument
3216  // to strncat and may lead to buffer overflows.
3217  unsigned PatternType = 0;
3218  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
3219    // - sizeof(dst)
3220    if (referToTheSameDecl(SizeOfArg, DstArg))
3221      PatternType = 1;
3222    // - sizeof(src)
3223    else if (referToTheSameDecl(SizeOfArg, SrcArg))
3224      PatternType = 2;
3225  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
3226    if (BE->getOpcode() == BO_Sub) {
3227      const Expr *L = BE->getLHS()->IgnoreParenCasts();
3228      const Expr *R = BE->getRHS()->IgnoreParenCasts();
3229      // - sizeof(dst) - strlen(dst)
3230      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
3231          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
3232        PatternType = 1;
3233      // - sizeof(src) - (anything)
3234      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
3235        PatternType = 2;
3236    }
3237  }
3238
3239  if (PatternType == 0)
3240    return;
3241
3242  // Generate the diagnostic.
3243  SourceLocation SL = LenArg->getLocStart();
3244  SourceRange SR = LenArg->getSourceRange();
3245  SourceManager &SM  = PP.getSourceManager();
3246
3247  // If the function is defined as a builtin macro, do not show macro expansion.
3248  if (SM.isMacroArgExpansion(SL)) {
3249    SL = SM.getSpellingLoc(SL);
3250    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
3251                     SM.getSpellingLoc(SR.getEnd()));
3252  }
3253
3254  if (PatternType == 1)
3255    Diag(SL, diag::warn_strncat_large_size) << SR;
3256  else
3257    Diag(SL, diag::warn_strncat_src_size) << SR;
3258
3259  // Output a FIXIT hint if the destination is an array (rather than a
3260  // pointer to an array).  This could be enhanced to handle some
3261  // pointers if we know the actual size, like if DstArg is 'array+2'
3262  // we could say 'sizeof(array)-2'.
3263  QualType DstArgTy = DstArg->getType();
3264
3265  // Only handle constant-sized or VLAs, but not flexible members.
3266  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
3267    // Only issue the FIXIT for arrays of size > 1.
3268    if (CAT->getSize().getSExtValue() <= 1)
3269      return;
3270  } else if (!DstArgTy->isVariableArrayType()) {
3271    return;
3272  }
3273
3274  SmallString<128> sizeString;
3275  llvm::raw_svector_ostream OS(sizeString);
3276  OS << "sizeof(";
3277  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
3278  OS << ") - ";
3279  OS << "strlen(";
3280  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
3281  OS << ") - 1";
3282
3283  Diag(SL, diag::note_strncat_wrong_size)
3284    << FixItHint::CreateReplacement(SR, OS.str());
3285}
3286
3287//===--- CHECK: Return Address of Stack Variable --------------------------===//
3288
3289static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3290                     Decl *ParentDecl);
3291static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3292                      Decl *ParentDecl);
3293
3294/// CheckReturnStackAddr - Check if a return statement returns the address
3295///   of a stack variable.
3296void
3297Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3298                           SourceLocation ReturnLoc) {
3299
3300  Expr *stackE = 0;
3301  SmallVector<DeclRefExpr *, 8> refVars;
3302
3303  // Perform checking for returned stack addresses, local blocks,
3304  // label addresses or references to temporaries.
3305  if (lhsType->isPointerType() ||
3306      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3307    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3308  } else if (lhsType->isReferenceType()) {
3309    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3310  }
3311
3312  if (stackE == 0)
3313    return; // Nothing suspicious was found.
3314
3315  SourceLocation diagLoc;
3316  SourceRange diagRange;
3317  if (refVars.empty()) {
3318    diagLoc = stackE->getLocStart();
3319    diagRange = stackE->getSourceRange();
3320  } else {
3321    // We followed through a reference variable. 'stackE' contains the
3322    // problematic expression but we will warn at the return statement pointing
3323    // at the reference variable. We will later display the "trail" of
3324    // reference variables using notes.
3325    diagLoc = refVars[0]->getLocStart();
3326    diagRange = refVars[0]->getSourceRange();
3327  }
3328
3329  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3330    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3331                                             : diag::warn_ret_stack_addr)
3332     << DR->getDecl()->getDeclName() << diagRange;
3333  } else if (isa<BlockExpr>(stackE)) { // local block.
3334    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3335  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3336    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3337  } else { // local temporary.
3338    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3339                                             : diag::warn_ret_local_temp_addr)
3340     << diagRange;
3341  }
3342
3343  // Display the "trail" of reference variables that we followed until we
3344  // found the problematic expression using notes.
3345  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3346    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3347    // If this var binds to another reference var, show the range of the next
3348    // var, otherwise the var binds to the problematic expression, in which case
3349    // show the range of the expression.
3350    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3351                                  : stackE->getSourceRange();
3352    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3353      << VD->getDeclName() << range;
3354  }
3355}
3356
3357/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3358///  check if the expression in a return statement evaluates to an address
3359///  to a location on the stack, a local block, an address of a label, or a
3360///  reference to local temporary. The recursion is used to traverse the
3361///  AST of the return expression, with recursion backtracking when we
3362///  encounter a subexpression that (1) clearly does not lead to one of the
3363///  above problematic expressions (2) is something we cannot determine leads to
3364///  a problematic expression based on such local checking.
3365///
3366///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3367///  the expression that they point to. Such variables are added to the
3368///  'refVars' vector so that we know what the reference variable "trail" was.
3369///
3370///  EvalAddr processes expressions that are pointers that are used as
3371///  references (and not L-values).  EvalVal handles all other values.
3372///  At the base case of the recursion is a check for the above problematic
3373///  expressions.
3374///
3375///  This implementation handles:
3376///
3377///   * pointer-to-pointer casts
3378///   * implicit conversions from array references to pointers
3379///   * taking the address of fields
3380///   * arbitrary interplay between "&" and "*" operators
3381///   * pointer arithmetic from an address of a stack variable
3382///   * taking the address of an array element where the array is on the stack
3383static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3384                      Decl *ParentDecl) {
3385  if (E->isTypeDependent())
3386      return NULL;
3387
3388  // We should only be called for evaluating pointer expressions.
3389  assert((E->getType()->isAnyPointerType() ||
3390          E->getType()->isBlockPointerType() ||
3391          E->getType()->isObjCQualifiedIdType()) &&
3392         "EvalAddr only works on pointers");
3393
3394  E = E->IgnoreParens();
3395
3396  // Our "symbolic interpreter" is just a dispatch off the currently
3397  // viewed AST node.  We then recursively traverse the AST by calling
3398  // EvalAddr and EvalVal appropriately.
3399  switch (E->getStmtClass()) {
3400  case Stmt::DeclRefExprClass: {
3401    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3402
3403    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3404      // If this is a reference variable, follow through to the expression that
3405      // it points to.
3406      if (V->hasLocalStorage() &&
3407          V->getType()->isReferenceType() && V->hasInit()) {
3408        // Add the reference variable to the "trail".
3409        refVars.push_back(DR);
3410        return EvalAddr(V->getInit(), refVars, ParentDecl);
3411      }
3412
3413    return NULL;
3414  }
3415
3416  case Stmt::UnaryOperatorClass: {
3417    // The only unary operator that make sense to handle here
3418    // is AddrOf.  All others don't make sense as pointers.
3419    UnaryOperator *U = cast<UnaryOperator>(E);
3420
3421    if (U->getOpcode() == UO_AddrOf)
3422      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3423    else
3424      return NULL;
3425  }
3426
3427  case Stmt::BinaryOperatorClass: {
3428    // Handle pointer arithmetic.  All other binary operators are not valid
3429    // in this context.
3430    BinaryOperator *B = cast<BinaryOperator>(E);
3431    BinaryOperatorKind op = B->getOpcode();
3432
3433    if (op != BO_Add && op != BO_Sub)
3434      return NULL;
3435
3436    Expr *Base = B->getLHS();
3437
3438    // Determine which argument is the real pointer base.  It could be
3439    // the RHS argument instead of the LHS.
3440    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3441
3442    assert (Base->getType()->isPointerType());
3443    return EvalAddr(Base, refVars, ParentDecl);
3444  }
3445
3446  // For conditional operators we need to see if either the LHS or RHS are
3447  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3448  case Stmt::ConditionalOperatorClass: {
3449    ConditionalOperator *C = cast<ConditionalOperator>(E);
3450
3451    // Handle the GNU extension for missing LHS.
3452    if (Expr *lhsExpr = C->getLHS()) {
3453    // In C++, we can have a throw-expression, which has 'void' type.
3454      if (!lhsExpr->getType()->isVoidType())
3455        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3456          return LHS;
3457    }
3458
3459    // In C++, we can have a throw-expression, which has 'void' type.
3460    if (C->getRHS()->getType()->isVoidType())
3461      return NULL;
3462
3463    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3464  }
3465
3466  case Stmt::BlockExprClass:
3467    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3468      return E; // local block.
3469    return NULL;
3470
3471  case Stmt::AddrLabelExprClass:
3472    return E; // address of label.
3473
3474  case Stmt::ExprWithCleanupsClass:
3475    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3476                    ParentDecl);
3477
3478  // For casts, we need to handle conversions from arrays to
3479  // pointer values, and pointer-to-pointer conversions.
3480  case Stmt::ImplicitCastExprClass:
3481  case Stmt::CStyleCastExprClass:
3482  case Stmt::CXXFunctionalCastExprClass:
3483  case Stmt::ObjCBridgedCastExprClass:
3484  case Stmt::CXXStaticCastExprClass:
3485  case Stmt::CXXDynamicCastExprClass:
3486  case Stmt::CXXConstCastExprClass:
3487  case Stmt::CXXReinterpretCastExprClass: {
3488    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3489    switch (cast<CastExpr>(E)->getCastKind()) {
3490    case CK_BitCast:
3491    case CK_LValueToRValue:
3492    case CK_NoOp:
3493    case CK_BaseToDerived:
3494    case CK_DerivedToBase:
3495    case CK_UncheckedDerivedToBase:
3496    case CK_Dynamic:
3497    case CK_CPointerToObjCPointerCast:
3498    case CK_BlockPointerToObjCPointerCast:
3499    case CK_AnyPointerToBlockPointerCast:
3500      return EvalAddr(SubExpr, refVars, ParentDecl);
3501
3502    case CK_ArrayToPointerDecay:
3503      return EvalVal(SubExpr, refVars, ParentDecl);
3504
3505    default:
3506      return 0;
3507    }
3508  }
3509
3510  case Stmt::MaterializeTemporaryExprClass:
3511    if (Expr *Result = EvalAddr(
3512                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3513                                refVars, ParentDecl))
3514      return Result;
3515
3516    return E;
3517
3518  // Everything else: we simply don't reason about them.
3519  default:
3520    return NULL;
3521  }
3522}
3523
3524
3525///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3526///   See the comments for EvalAddr for more details.
3527static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3528                     Decl *ParentDecl) {
3529do {
3530  // We should only be called for evaluating non-pointer expressions, or
3531  // expressions with a pointer type that are not used as references but instead
3532  // are l-values (e.g., DeclRefExpr with a pointer type).
3533
3534  // Our "symbolic interpreter" is just a dispatch off the currently
3535  // viewed AST node.  We then recursively traverse the AST by calling
3536  // EvalAddr and EvalVal appropriately.
3537
3538  E = E->IgnoreParens();
3539  switch (E->getStmtClass()) {
3540  case Stmt::ImplicitCastExprClass: {
3541    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3542    if (IE->getValueKind() == VK_LValue) {
3543      E = IE->getSubExpr();
3544      continue;
3545    }
3546    return NULL;
3547  }
3548
3549  case Stmt::ExprWithCleanupsClass:
3550    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3551
3552  case Stmt::DeclRefExprClass: {
3553    // When we hit a DeclRefExpr we are looking at code that refers to a
3554    // variable's name. If it's not a reference variable we check if it has
3555    // local storage within the function, and if so, return the expression.
3556    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3557
3558    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3559      // Check if it refers to itself, e.g. "int& i = i;".
3560      if (V == ParentDecl)
3561        return DR;
3562
3563      if (V->hasLocalStorage()) {
3564        if (!V->getType()->isReferenceType())
3565          return DR;
3566
3567        // Reference variable, follow through to the expression that
3568        // it points to.
3569        if (V->hasInit()) {
3570          // Add the reference variable to the "trail".
3571          refVars.push_back(DR);
3572          return EvalVal(V->getInit(), refVars, V);
3573        }
3574      }
3575    }
3576
3577    return NULL;
3578  }
3579
3580  case Stmt::UnaryOperatorClass: {
3581    // The only unary operator that make sense to handle here
3582    // is Deref.  All others don't resolve to a "name."  This includes
3583    // handling all sorts of rvalues passed to a unary operator.
3584    UnaryOperator *U = cast<UnaryOperator>(E);
3585
3586    if (U->getOpcode() == UO_Deref)
3587      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3588
3589    return NULL;
3590  }
3591
3592  case Stmt::ArraySubscriptExprClass: {
3593    // Array subscripts are potential references to data on the stack.  We
3594    // retrieve the DeclRefExpr* for the array variable if it indeed
3595    // has local storage.
3596    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3597  }
3598
3599  case Stmt::ConditionalOperatorClass: {
3600    // For conditional operators we need to see if either the LHS or RHS are
3601    // non-NULL Expr's.  If one is non-NULL, we return it.
3602    ConditionalOperator *C = cast<ConditionalOperator>(E);
3603
3604    // Handle the GNU extension for missing LHS.
3605    if (Expr *lhsExpr = C->getLHS())
3606      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3607        return LHS;
3608
3609    return EvalVal(C->getRHS(), refVars, ParentDecl);
3610  }
3611
3612  // Accesses to members are potential references to data on the stack.
3613  case Stmt::MemberExprClass: {
3614    MemberExpr *M = cast<MemberExpr>(E);
3615
3616    // Check for indirect access.  We only want direct field accesses.
3617    if (M->isArrow())
3618      return NULL;
3619
3620    // Check whether the member type is itself a reference, in which case
3621    // we're not going to refer to the member, but to what the member refers to.
3622    if (M->getMemberDecl()->getType()->isReferenceType())
3623      return NULL;
3624
3625    return EvalVal(M->getBase(), refVars, ParentDecl);
3626  }
3627
3628  case Stmt::MaterializeTemporaryExprClass:
3629    if (Expr *Result = EvalVal(
3630                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3631                               refVars, ParentDecl))
3632      return Result;
3633
3634    return E;
3635
3636  default:
3637    // Check that we don't return or take the address of a reference to a
3638    // temporary. This is only useful in C++.
3639    if (!E->isTypeDependent() && E->isRValue())
3640      return E;
3641
3642    // Everything else: we simply don't reason about them.
3643    return NULL;
3644  }
3645} while (true);
3646}
3647
3648//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3649
3650/// Check for comparisons of floating point operands using != and ==.
3651/// Issue a warning if these are no self-comparisons, as they are not likely
3652/// to do what the programmer intended.
3653void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3654  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3655  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3656
3657  // Special case: check for x == x (which is OK).
3658  // Do not emit warnings for such cases.
3659  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3660    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3661      if (DRL->getDecl() == DRR->getDecl())
3662        return;
3663
3664
3665  // Special case: check for comparisons against literals that can be exactly
3666  //  represented by APFloat.  In such cases, do not emit a warning.  This
3667  //  is a heuristic: often comparison against such literals are used to
3668  //  detect if a value in a variable has not changed.  This clearly can
3669  //  lead to false negatives.
3670  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3671    if (FLL->isExact())
3672      return;
3673  } else
3674    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
3675      if (FLR->isExact())
3676        return;
3677
3678  // Check for comparisons with builtin types.
3679  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3680    if (CL->isBuiltinCall())
3681      return;
3682
3683  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3684    if (CR->isBuiltinCall())
3685      return;
3686
3687  // Emit the diagnostic.
3688  Diag(Loc, diag::warn_floatingpoint_eq)
3689    << LHS->getSourceRange() << RHS->getSourceRange();
3690}
3691
3692//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3693//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3694
3695namespace {
3696
3697/// Structure recording the 'active' range of an integer-valued
3698/// expression.
3699struct IntRange {
3700  /// The number of bits active in the int.
3701  unsigned Width;
3702
3703  /// True if the int is known not to have negative values.
3704  bool NonNegative;
3705
3706  IntRange(unsigned Width, bool NonNegative)
3707    : Width(Width), NonNegative(NonNegative)
3708  {}
3709
3710  /// Returns the range of the bool type.
3711  static IntRange forBoolType() {
3712    return IntRange(1, true);
3713  }
3714
3715  /// Returns the range of an opaque value of the given integral type.
3716  static IntRange forValueOfType(ASTContext &C, QualType T) {
3717    return forValueOfCanonicalType(C,
3718                          T->getCanonicalTypeInternal().getTypePtr());
3719  }
3720
3721  /// Returns the range of an opaque value of a canonical integral type.
3722  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3723    assert(T->isCanonicalUnqualified());
3724
3725    if (const VectorType *VT = dyn_cast<VectorType>(T))
3726      T = VT->getElementType().getTypePtr();
3727    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3728      T = CT->getElementType().getTypePtr();
3729
3730    // For enum types, use the known bit width of the enumerators.
3731    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3732      EnumDecl *Enum = ET->getDecl();
3733      if (!Enum->isCompleteDefinition())
3734        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3735
3736      unsigned NumPositive = Enum->getNumPositiveBits();
3737      unsigned NumNegative = Enum->getNumNegativeBits();
3738
3739      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3740    }
3741
3742    const BuiltinType *BT = cast<BuiltinType>(T);
3743    assert(BT->isInteger());
3744
3745    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3746  }
3747
3748  /// Returns the "target" range of a canonical integral type, i.e.
3749  /// the range of values expressible in the type.
3750  ///
3751  /// This matches forValueOfCanonicalType except that enums have the
3752  /// full range of their type, not the range of their enumerators.
3753  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3754    assert(T->isCanonicalUnqualified());
3755
3756    if (const VectorType *VT = dyn_cast<VectorType>(T))
3757      T = VT->getElementType().getTypePtr();
3758    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3759      T = CT->getElementType().getTypePtr();
3760    if (const EnumType *ET = dyn_cast<EnumType>(T))
3761      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3762
3763    const BuiltinType *BT = cast<BuiltinType>(T);
3764    assert(BT->isInteger());
3765
3766    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3767  }
3768
3769  /// Returns the supremum of two ranges: i.e. their conservative merge.
3770  static IntRange join(IntRange L, IntRange R) {
3771    return IntRange(std::max(L.Width, R.Width),
3772                    L.NonNegative && R.NonNegative);
3773  }
3774
3775  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3776  static IntRange meet(IntRange L, IntRange R) {
3777    return IntRange(std::min(L.Width, R.Width),
3778                    L.NonNegative || R.NonNegative);
3779  }
3780};
3781
3782static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
3783                              unsigned MaxWidth) {
3784  if (value.isSigned() && value.isNegative())
3785    return IntRange(value.getMinSignedBits(), false);
3786
3787  if (value.getBitWidth() > MaxWidth)
3788    value = value.trunc(MaxWidth);
3789
3790  // isNonNegative() just checks the sign bit without considering
3791  // signedness.
3792  return IntRange(value.getActiveBits(), true);
3793}
3794
3795static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3796                              unsigned MaxWidth) {
3797  if (result.isInt())
3798    return GetValueRange(C, result.getInt(), MaxWidth);
3799
3800  if (result.isVector()) {
3801    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3802    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3803      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3804      R = IntRange::join(R, El);
3805    }
3806    return R;
3807  }
3808
3809  if (result.isComplexInt()) {
3810    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3811    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3812    return IntRange::join(R, I);
3813  }
3814
3815  // This can happen with lossless casts to intptr_t of "based" lvalues.
3816  // Assume it might use arbitrary bits.
3817  // FIXME: The only reason we need to pass the type in here is to get
3818  // the sign right on this one case.  It would be nice if APValue
3819  // preserved this.
3820  assert(result.isLValue() || result.isAddrLabelDiff());
3821  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
3822}
3823
3824/// Pseudo-evaluate the given integer expression, estimating the
3825/// range of values it might take.
3826///
3827/// \param MaxWidth - the width to which the value will be truncated
3828static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
3829  E = E->IgnoreParens();
3830
3831  // Try a full evaluation first.
3832  Expr::EvalResult result;
3833  if (E->EvaluateAsRValue(result, C))
3834    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
3835
3836  // I think we only want to look through implicit casts here; if the
3837  // user has an explicit widening cast, we should treat the value as
3838  // being of the new, wider type.
3839  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
3840    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
3841      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
3842
3843    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
3844
3845    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
3846
3847    // Assume that non-integer casts can span the full range of the type.
3848    if (!isIntegerCast)
3849      return OutputTypeRange;
3850
3851    IntRange SubRange
3852      = GetExprRange(C, CE->getSubExpr(),
3853                     std::min(MaxWidth, OutputTypeRange.Width));
3854
3855    // Bail out if the subexpr's range is as wide as the cast type.
3856    if (SubRange.Width >= OutputTypeRange.Width)
3857      return OutputTypeRange;
3858
3859    // Otherwise, we take the smaller width, and we're non-negative if
3860    // either the output type or the subexpr is.
3861    return IntRange(SubRange.Width,
3862                    SubRange.NonNegative || OutputTypeRange.NonNegative);
3863  }
3864
3865  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3866    // If we can fold the condition, just take that operand.
3867    bool CondResult;
3868    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
3869      return GetExprRange(C, CondResult ? CO->getTrueExpr()
3870                                        : CO->getFalseExpr(),
3871                          MaxWidth);
3872
3873    // Otherwise, conservatively merge.
3874    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
3875    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
3876    return IntRange::join(L, R);
3877  }
3878
3879  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3880    switch (BO->getOpcode()) {
3881
3882    // Boolean-valued operations are single-bit and positive.
3883    case BO_LAnd:
3884    case BO_LOr:
3885    case BO_LT:
3886    case BO_GT:
3887    case BO_LE:
3888    case BO_GE:
3889    case BO_EQ:
3890    case BO_NE:
3891      return IntRange::forBoolType();
3892
3893    // The type of the assignments is the type of the LHS, so the RHS
3894    // is not necessarily the same type.
3895    case BO_MulAssign:
3896    case BO_DivAssign:
3897    case BO_RemAssign:
3898    case BO_AddAssign:
3899    case BO_SubAssign:
3900    case BO_XorAssign:
3901    case BO_OrAssign:
3902      // TODO: bitfields?
3903      return IntRange::forValueOfType(C, E->getType());
3904
3905    // Simple assignments just pass through the RHS, which will have
3906    // been coerced to the LHS type.
3907    case BO_Assign:
3908      // TODO: bitfields?
3909      return GetExprRange(C, BO->getRHS(), MaxWidth);
3910
3911    // Operations with opaque sources are black-listed.
3912    case BO_PtrMemD:
3913    case BO_PtrMemI:
3914      return IntRange::forValueOfType(C, E->getType());
3915
3916    // Bitwise-and uses the *infinum* of the two source ranges.
3917    case BO_And:
3918    case BO_AndAssign:
3919      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
3920                            GetExprRange(C, BO->getRHS(), MaxWidth));
3921
3922    // Left shift gets black-listed based on a judgement call.
3923    case BO_Shl:
3924      // ...except that we want to treat '1 << (blah)' as logically
3925      // positive.  It's an important idiom.
3926      if (IntegerLiteral *I
3927            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
3928        if (I->getValue() == 1) {
3929          IntRange R = IntRange::forValueOfType(C, E->getType());
3930          return IntRange(R.Width, /*NonNegative*/ true);
3931        }
3932      }
3933      // fallthrough
3934
3935    case BO_ShlAssign:
3936      return IntRange::forValueOfType(C, E->getType());
3937
3938    // Right shift by a constant can narrow its left argument.
3939    case BO_Shr:
3940    case BO_ShrAssign: {
3941      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3942
3943      // If the shift amount is a positive constant, drop the width by
3944      // that much.
3945      llvm::APSInt shift;
3946      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
3947          shift.isNonNegative()) {
3948        unsigned zext = shift.getZExtValue();
3949        if (zext >= L.Width)
3950          L.Width = (L.NonNegative ? 0 : 1);
3951        else
3952          L.Width -= zext;
3953      }
3954
3955      return L;
3956    }
3957
3958    // Comma acts as its right operand.
3959    case BO_Comma:
3960      return GetExprRange(C, BO->getRHS(), MaxWidth);
3961
3962    // Black-list pointer subtractions.
3963    case BO_Sub:
3964      if (BO->getLHS()->getType()->isPointerType())
3965        return IntRange::forValueOfType(C, E->getType());
3966      break;
3967
3968    // The width of a division result is mostly determined by the size
3969    // of the LHS.
3970    case BO_Div: {
3971      // Don't 'pre-truncate' the operands.
3972      unsigned opWidth = C.getIntWidth(E->getType());
3973      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3974
3975      // If the divisor is constant, use that.
3976      llvm::APSInt divisor;
3977      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
3978        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
3979        if (log2 >= L.Width)
3980          L.Width = (L.NonNegative ? 0 : 1);
3981        else
3982          L.Width = std::min(L.Width - log2, MaxWidth);
3983        return L;
3984      }
3985
3986      // Otherwise, just use the LHS's width.
3987      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3988      return IntRange(L.Width, L.NonNegative && R.NonNegative);
3989    }
3990
3991    // The result of a remainder can't be larger than the result of
3992    // either side.
3993    case BO_Rem: {
3994      // Don't 'pre-truncate' the operands.
3995      unsigned opWidth = C.getIntWidth(E->getType());
3996      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3997      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3998
3999      IntRange meet = IntRange::meet(L, R);
4000      meet.Width = std::min(meet.Width, MaxWidth);
4001      return meet;
4002    }
4003
4004    // The default behavior is okay for these.
4005    case BO_Mul:
4006    case BO_Add:
4007    case BO_Xor:
4008    case BO_Or:
4009      break;
4010    }
4011
4012    // The default case is to treat the operation as if it were closed
4013    // on the narrowest type that encompasses both operands.
4014    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
4015    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
4016    return IntRange::join(L, R);
4017  }
4018
4019  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
4020    switch (UO->getOpcode()) {
4021    // Boolean-valued operations are white-listed.
4022    case UO_LNot:
4023      return IntRange::forBoolType();
4024
4025    // Operations with opaque sources are black-listed.
4026    case UO_Deref:
4027    case UO_AddrOf: // should be impossible
4028      return IntRange::forValueOfType(C, E->getType());
4029
4030    default:
4031      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
4032    }
4033  }
4034
4035  if (dyn_cast<OffsetOfExpr>(E)) {
4036    IntRange::forValueOfType(C, E->getType());
4037  }
4038
4039  if (FieldDecl *BitField = E->getBitField())
4040    return IntRange(BitField->getBitWidthValue(C),
4041                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
4042
4043  return IntRange::forValueOfType(C, E->getType());
4044}
4045
4046static IntRange GetExprRange(ASTContext &C, Expr *E) {
4047  return GetExprRange(C, E, C.getIntWidth(E->getType()));
4048}
4049
4050/// Checks whether the given value, which currently has the given
4051/// source semantics, has the same value when coerced through the
4052/// target semantics.
4053static bool IsSameFloatAfterCast(const llvm::APFloat &value,
4054                                 const llvm::fltSemantics &Src,
4055                                 const llvm::fltSemantics &Tgt) {
4056  llvm::APFloat truncated = value;
4057
4058  bool ignored;
4059  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
4060  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
4061
4062  return truncated.bitwiseIsEqual(value);
4063}
4064
4065/// Checks whether the given value, which currently has the given
4066/// source semantics, has the same value when coerced through the
4067/// target semantics.
4068///
4069/// The value might be a vector of floats (or a complex number).
4070static bool IsSameFloatAfterCast(const APValue &value,
4071                                 const llvm::fltSemantics &Src,
4072                                 const llvm::fltSemantics &Tgt) {
4073  if (value.isFloat())
4074    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
4075
4076  if (value.isVector()) {
4077    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
4078      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
4079        return false;
4080    return true;
4081  }
4082
4083  assert(value.isComplexFloat());
4084  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
4085          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
4086}
4087
4088static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
4089
4090static bool IsZero(Sema &S, Expr *E) {
4091  // Suppress cases where we are comparing against an enum constant.
4092  if (const DeclRefExpr *DR =
4093      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
4094    if (isa<EnumConstantDecl>(DR->getDecl()))
4095      return false;
4096
4097  // Suppress cases where the '0' value is expanded from a macro.
4098  if (E->getLocStart().isMacroID())
4099    return false;
4100
4101  llvm::APSInt Value;
4102  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
4103}
4104
4105static bool HasEnumType(Expr *E) {
4106  // Strip off implicit integral promotions.
4107  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
4108    if (ICE->getCastKind() != CK_IntegralCast &&
4109        ICE->getCastKind() != CK_NoOp)
4110      break;
4111    E = ICE->getSubExpr();
4112  }
4113
4114  return E->getType()->isEnumeralType();
4115}
4116
4117static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
4118  BinaryOperatorKind op = E->getOpcode();
4119  if (E->isValueDependent())
4120    return;
4121
4122  if (op == BO_LT && IsZero(S, E->getRHS())) {
4123    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4124      << "< 0" << "false" << HasEnumType(E->getLHS())
4125      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4126  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
4127    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
4128      << ">= 0" << "true" << HasEnumType(E->getLHS())
4129      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4130  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
4131    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4132      << "0 >" << "false" << HasEnumType(E->getRHS())
4133      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4134  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
4135    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
4136      << "0 <=" << "true" << HasEnumType(E->getRHS())
4137      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
4138  }
4139}
4140
4141/// Analyze the operands of the given comparison.  Implements the
4142/// fallback case from AnalyzeComparison.
4143static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
4144  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4145  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4146}
4147
4148/// \brief Implements -Wsign-compare.
4149///
4150/// \param E the binary operator to check for warnings
4151static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
4152  // The type the comparison is being performed in.
4153  QualType T = E->getLHS()->getType();
4154  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
4155         && "comparison with mismatched types");
4156
4157  // We don't do anything special if this isn't an unsigned integral
4158  // comparison:  we're only interested in integral comparisons, and
4159  // signed comparisons only happen in cases we don't care to warn about.
4160  //
4161  // We also don't care about value-dependent expressions or expressions
4162  // whose result is a constant.
4163  if (!T->hasUnsignedIntegerRepresentation()
4164      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
4165    return AnalyzeImpConvsInComparison(S, E);
4166
4167  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
4168  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
4169
4170  // Check to see if one of the (unmodified) operands is of different
4171  // signedness.
4172  Expr *signedOperand, *unsignedOperand;
4173  if (LHS->getType()->hasSignedIntegerRepresentation()) {
4174    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
4175           "unsigned comparison between two signed integer expressions?");
4176    signedOperand = LHS;
4177    unsignedOperand = RHS;
4178  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
4179    signedOperand = RHS;
4180    unsignedOperand = LHS;
4181  } else {
4182    CheckTrivialUnsignedComparison(S, E);
4183    return AnalyzeImpConvsInComparison(S, E);
4184  }
4185
4186  // Otherwise, calculate the effective range of the signed operand.
4187  IntRange signedRange = GetExprRange(S.Context, signedOperand);
4188
4189  // Go ahead and analyze implicit conversions in the operands.  Note
4190  // that we skip the implicit conversions on both sides.
4191  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
4192  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
4193
4194  // If the signed range is non-negative, -Wsign-compare won't fire,
4195  // but we should still check for comparisons which are always true
4196  // or false.
4197  if (signedRange.NonNegative)
4198    return CheckTrivialUnsignedComparison(S, E);
4199
4200  // For (in)equality comparisons, if the unsigned operand is a
4201  // constant which cannot collide with a overflowed signed operand,
4202  // then reinterpreting the signed operand as unsigned will not
4203  // change the result of the comparison.
4204  if (E->isEqualityOp()) {
4205    unsigned comparisonWidth = S.Context.getIntWidth(T);
4206    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
4207
4208    // We should never be unable to prove that the unsigned operand is
4209    // non-negative.
4210    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
4211
4212    if (unsignedRange.Width < comparisonWidth)
4213      return;
4214  }
4215
4216  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
4217    S.PDiag(diag::warn_mixed_sign_comparison)
4218      << LHS->getType() << RHS->getType()
4219      << LHS->getSourceRange() << RHS->getSourceRange());
4220}
4221
4222/// Analyzes an attempt to assign the given value to a bitfield.
4223///
4224/// Returns true if there was something fishy about the attempt.
4225static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
4226                                      SourceLocation InitLoc) {
4227  assert(Bitfield->isBitField());
4228  if (Bitfield->isInvalidDecl())
4229    return false;
4230
4231  // White-list bool bitfields.
4232  if (Bitfield->getType()->isBooleanType())
4233    return false;
4234
4235  // Ignore value- or type-dependent expressions.
4236  if (Bitfield->getBitWidth()->isValueDependent() ||
4237      Bitfield->getBitWidth()->isTypeDependent() ||
4238      Init->isValueDependent() ||
4239      Init->isTypeDependent())
4240    return false;
4241
4242  Expr *OriginalInit = Init->IgnoreParenImpCasts();
4243
4244  llvm::APSInt Value;
4245  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
4246    return false;
4247
4248  unsigned OriginalWidth = Value.getBitWidth();
4249  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
4250
4251  if (OriginalWidth <= FieldWidth)
4252    return false;
4253
4254  // Compute the value which the bitfield will contain.
4255  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
4256  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
4257
4258  // Check whether the stored value is equal to the original value.
4259  TruncatedValue = TruncatedValue.extend(OriginalWidth);
4260  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
4261    return false;
4262
4263  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4264  // therefore don't strictly fit into a signed bitfield of width 1.
4265  if (FieldWidth == 1 && Value == 1)
4266    return false;
4267
4268  std::string PrettyValue = Value.toString(10);
4269  std::string PrettyTrunc = TruncatedValue.toString(10);
4270
4271  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4272    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4273    << Init->getSourceRange();
4274
4275  return true;
4276}
4277
4278/// Analyze the given simple or compound assignment for warning-worthy
4279/// operations.
4280static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4281  // Just recurse on the LHS.
4282  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4283
4284  // We want to recurse on the RHS as normal unless we're assigning to
4285  // a bitfield.
4286  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
4287    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4288                                  E->getOperatorLoc())) {
4289      // Recurse, ignoring any implicit conversions on the RHS.
4290      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4291                                        E->getOperatorLoc());
4292    }
4293  }
4294
4295  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4296}
4297
4298/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4299static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4300                            SourceLocation CContext, unsigned diag,
4301                            bool pruneControlFlow = false) {
4302  if (pruneControlFlow) {
4303    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4304                          S.PDiag(diag)
4305                            << SourceType << T << E->getSourceRange()
4306                            << SourceRange(CContext));
4307    return;
4308  }
4309  S.Diag(E->getExprLoc(), diag)
4310    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4311}
4312
4313/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4314static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4315                            SourceLocation CContext, unsigned diag,
4316                            bool pruneControlFlow = false) {
4317  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4318}
4319
4320/// Diagnose an implicit cast from a literal expression. Does not warn when the
4321/// cast wouldn't lose information.
4322void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4323                                    SourceLocation CContext) {
4324  // Try to convert the literal exactly to an integer. If we can, don't warn.
4325  bool isExact = false;
4326  const llvm::APFloat &Value = FL->getValue();
4327  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4328                            T->hasUnsignedIntegerRepresentation());
4329  if (Value.convertToInteger(IntegerValue,
4330                             llvm::APFloat::rmTowardZero, &isExact)
4331      == llvm::APFloat::opOK && isExact)
4332    return;
4333
4334  SmallString<16> PrettySourceValue;
4335  Value.toString(PrettySourceValue);
4336  SmallString<16> PrettyTargetValue;
4337  if (T->isSpecificBuiltinType(BuiltinType::Bool))
4338    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
4339  else
4340    IntegerValue.toString(PrettyTargetValue);
4341
4342  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4343    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
4344    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
4345}
4346
4347std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4348  if (!Range.Width) return "0";
4349
4350  llvm::APSInt ValueInRange = Value;
4351  ValueInRange.setIsSigned(!Range.NonNegative);
4352  ValueInRange = ValueInRange.trunc(Range.Width);
4353  return ValueInRange.toString(10);
4354}
4355
4356void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4357                             SourceLocation CC, bool *ICContext = 0) {
4358  if (E->isTypeDependent() || E->isValueDependent()) return;
4359
4360  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4361  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4362  if (Source == Target) return;
4363  if (Target->isDependentType()) return;
4364
4365  // If the conversion context location is invalid don't complain. We also
4366  // don't want to emit a warning if the issue occurs from the expansion of
4367  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4368  // delay this check as long as possible. Once we detect we are in that
4369  // scenario, we just return.
4370  if (CC.isInvalid())
4371    return;
4372
4373  // Diagnose implicit casts to bool.
4374  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4375    if (isa<StringLiteral>(E))
4376      // Warn on string literal to bool.  Checks for string literals in logical
4377      // expressions, for instances, assert(0 && "error here"), is prevented
4378      // by a check in AnalyzeImplicitConversions().
4379      return DiagnoseImpCast(S, E, T, CC,
4380                             diag::warn_impcast_string_literal_to_bool);
4381    if (Source->isFunctionType()) {
4382      // Warn on function to bool. Checks free functions and static member
4383      // functions. Weakly imported functions are excluded from the check,
4384      // since it's common to test their value to check whether the linker
4385      // found a definition for them.
4386      ValueDecl *D = 0;
4387      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4388        D = R->getDecl();
4389      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4390        D = M->getMemberDecl();
4391      }
4392
4393      if (D && !D->isWeak()) {
4394        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4395          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4396            << F << E->getSourceRange() << SourceRange(CC);
4397          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4398            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4399          QualType ReturnType;
4400          UnresolvedSet<4> NonTemplateOverloads;
4401          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
4402          if (!ReturnType.isNull()
4403              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4404            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4405              << FixItHint::CreateInsertion(
4406                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4407          return;
4408        }
4409      }
4410    }
4411  }
4412
4413  // Strip vector types.
4414  if (isa<VectorType>(Source)) {
4415    if (!isa<VectorType>(Target)) {
4416      if (S.SourceMgr.isInSystemMacro(CC))
4417        return;
4418      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4419    }
4420
4421    // If the vector cast is cast between two vectors of the same size, it is
4422    // a bitcast, not a conversion.
4423    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4424      return;
4425
4426    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4427    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4428  }
4429
4430  // Strip complex types.
4431  if (isa<ComplexType>(Source)) {
4432    if (!isa<ComplexType>(Target)) {
4433      if (S.SourceMgr.isInSystemMacro(CC))
4434        return;
4435
4436      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4437    }
4438
4439    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4440    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4441  }
4442
4443  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4444  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4445
4446  // If the source is floating point...
4447  if (SourceBT && SourceBT->isFloatingPoint()) {
4448    // ...and the target is floating point...
4449    if (TargetBT && TargetBT->isFloatingPoint()) {
4450      // ...then warn if we're dropping FP rank.
4451
4452      // Builtin FP kinds are ordered by increasing FP rank.
4453      if (SourceBT->getKind() > TargetBT->getKind()) {
4454        // Don't warn about float constants that are precisely
4455        // representable in the target type.
4456        Expr::EvalResult result;
4457        if (E->EvaluateAsRValue(result, S.Context)) {
4458          // Value might be a float, a float vector, or a float complex.
4459          if (IsSameFloatAfterCast(result.Val,
4460                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4461                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4462            return;
4463        }
4464
4465        if (S.SourceMgr.isInSystemMacro(CC))
4466          return;
4467
4468        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4469      }
4470      return;
4471    }
4472
4473    // If the target is integral, always warn.
4474    if (TargetBT && TargetBT->isInteger()) {
4475      if (S.SourceMgr.isInSystemMacro(CC))
4476        return;
4477
4478      Expr *InnerE = E->IgnoreParenImpCasts();
4479      // We also want to warn on, e.g., "int i = -1.234"
4480      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4481        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4482          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4483
4484      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4485        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4486      } else {
4487        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4488      }
4489    }
4490
4491    return;
4492  }
4493
4494  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4495           == Expr::NPCK_GNUNull) && !Target->isAnyPointerType()
4496      && !Target->isBlockPointerType() && !Target->isMemberPointerType()) {
4497    SourceLocation Loc = E->getSourceRange().getBegin();
4498    if (Loc.isMacroID())
4499      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4500    if (!Loc.isMacroID() || CC.isMacroID())
4501      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4502          << T << clang::SourceRange(CC)
4503          << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
4504  }
4505
4506  if (!Source->isIntegerType() || !Target->isIntegerType())
4507    return;
4508
4509  // TODO: remove this early return once the false positives for constant->bool
4510  // in templates, macros, etc, are reduced or removed.
4511  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
4512    return;
4513
4514  IntRange SourceRange = GetExprRange(S.Context, E);
4515  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
4516
4517  if (SourceRange.Width > TargetRange.Width) {
4518    // If the source is a constant, use a default-on diagnostic.
4519    // TODO: this should happen for bitfield stores, too.
4520    llvm::APSInt Value(32);
4521    if (E->isIntegerConstantExpr(Value, S.Context)) {
4522      if (S.SourceMgr.isInSystemMacro(CC))
4523        return;
4524
4525      std::string PrettySourceValue = Value.toString(10);
4526      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
4527
4528      S.DiagRuntimeBehavior(E->getExprLoc(), E,
4529        S.PDiag(diag::warn_impcast_integer_precision_constant)
4530            << PrettySourceValue << PrettyTargetValue
4531            << E->getType() << T << E->getSourceRange()
4532            << clang::SourceRange(CC));
4533      return;
4534    }
4535
4536    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
4537    if (S.SourceMgr.isInSystemMacro(CC))
4538      return;
4539
4540    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
4541      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
4542                             /* pruneControlFlow */ true);
4543    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
4544  }
4545
4546  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
4547      (!TargetRange.NonNegative && SourceRange.NonNegative &&
4548       SourceRange.Width == TargetRange.Width)) {
4549
4550    if (S.SourceMgr.isInSystemMacro(CC))
4551      return;
4552
4553    unsigned DiagID = diag::warn_impcast_integer_sign;
4554
4555    // Traditionally, gcc has warned about this under -Wsign-compare.
4556    // We also want to warn about it in -Wconversion.
4557    // So if -Wconversion is off, use a completely identical diagnostic
4558    // in the sign-compare group.
4559    // The conditional-checking code will
4560    if (ICContext) {
4561      DiagID = diag::warn_impcast_integer_sign_conditional;
4562      *ICContext = true;
4563    }
4564
4565    return DiagnoseImpCast(S, E, T, CC, DiagID);
4566  }
4567
4568  // Diagnose conversions between different enumeration types.
4569  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
4570  // type, to give us better diagnostics.
4571  QualType SourceType = E->getType();
4572  if (!S.getLangOpts().CPlusPlus) {
4573    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
4574      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
4575        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
4576        SourceType = S.Context.getTypeDeclType(Enum);
4577        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
4578      }
4579  }
4580
4581  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
4582    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
4583      if ((SourceEnum->getDecl()->getIdentifier() ||
4584           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4585          (TargetEnum->getDecl()->getIdentifier() ||
4586           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4587          SourceEnum != TargetEnum) {
4588        if (S.SourceMgr.isInSystemMacro(CC))
4589          return;
4590
4591        return DiagnoseImpCast(S, E, SourceType, T, CC,
4592                               diag::warn_impcast_different_enum_types);
4593      }
4594
4595  return;
4596}
4597
4598void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
4599                              SourceLocation CC, QualType T);
4600
4601void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
4602                             SourceLocation CC, bool &ICContext) {
4603  E = E->IgnoreParenImpCasts();
4604
4605  if (isa<ConditionalOperator>(E))
4606    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
4607
4608  AnalyzeImplicitConversions(S, E, CC);
4609  if (E->getType() != T)
4610    return CheckImplicitConversion(S, E, T, CC, &ICContext);
4611  return;
4612}
4613
4614void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
4615                              SourceLocation CC, QualType T) {
4616  AnalyzeImplicitConversions(S, E->getCond(), CC);
4617
4618  bool Suspicious = false;
4619  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
4620  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
4621
4622  // If -Wconversion would have warned about either of the candidates
4623  // for a signedness conversion to the context type...
4624  if (!Suspicious) return;
4625
4626  // ...but it's currently ignored...
4627  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
4628                                 CC))
4629    return;
4630
4631  // ...then check whether it would have warned about either of the
4632  // candidates for a signedness conversion to the condition type.
4633  if (E->getType() == T) return;
4634
4635  Suspicious = false;
4636  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
4637                          E->getType(), CC, &Suspicious);
4638  if (!Suspicious)
4639    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
4640                            E->getType(), CC, &Suspicious);
4641}
4642
4643/// AnalyzeImplicitConversions - Find and report any interesting
4644/// implicit conversions in the given expression.  There are a couple
4645/// of competing diagnostics here, -Wconversion and -Wsign-compare.
4646void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
4647  QualType T = OrigE->getType();
4648  Expr *E = OrigE->IgnoreParenImpCasts();
4649
4650  if (E->isTypeDependent() || E->isValueDependent())
4651    return;
4652
4653  // For conditional operators, we analyze the arguments as if they
4654  // were being fed directly into the output.
4655  if (isa<ConditionalOperator>(E)) {
4656    ConditionalOperator *CO = cast<ConditionalOperator>(E);
4657    CheckConditionalOperator(S, CO, CC, T);
4658    return;
4659  }
4660
4661  // Go ahead and check any implicit conversions we might have skipped.
4662  // The non-canonical typecheck is just an optimization;
4663  // CheckImplicitConversion will filter out dead implicit conversions.
4664  if (E->getType() != T)
4665    CheckImplicitConversion(S, E, T, CC);
4666
4667  // Now continue drilling into this expression.
4668
4669  // Skip past explicit casts.
4670  if (isa<ExplicitCastExpr>(E)) {
4671    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4672    return AnalyzeImplicitConversions(S, E, CC);
4673  }
4674
4675  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4676    // Do a somewhat different check with comparison operators.
4677    if (BO->isComparisonOp())
4678      return AnalyzeComparison(S, BO);
4679
4680    // And with simple assignments.
4681    if (BO->getOpcode() == BO_Assign)
4682      return AnalyzeAssignment(S, BO);
4683  }
4684
4685  // These break the otherwise-useful invariant below.  Fortunately,
4686  // we don't really need to recurse into them, because any internal
4687  // expressions should have been analyzed already when they were
4688  // built into statements.
4689  if (isa<StmtExpr>(E)) return;
4690
4691  // Don't descend into unevaluated contexts.
4692  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
4693
4694  // Now just recurse over the expression's children.
4695  CC = E->getExprLoc();
4696  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
4697  bool IsLogicalOperator = BO && BO->isLogicalOp();
4698  for (Stmt::child_range I = E->children(); I; ++I) {
4699    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
4700    if (!ChildExpr)
4701      continue;
4702
4703    if (IsLogicalOperator &&
4704        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
4705      // Ignore checking string literals that are in logical operators.
4706      continue;
4707    AnalyzeImplicitConversions(S, ChildExpr, CC);
4708  }
4709}
4710
4711} // end anonymous namespace
4712
4713/// Diagnoses "dangerous" implicit conversions within the given
4714/// expression (which is a full expression).  Implements -Wconversion
4715/// and -Wsign-compare.
4716///
4717/// \param CC the "context" location of the implicit conversion, i.e.
4718///   the most location of the syntactic entity requiring the implicit
4719///   conversion
4720void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
4721  // Don't diagnose in unevaluated contexts.
4722  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
4723    return;
4724
4725  // Don't diagnose for value- or type-dependent expressions.
4726  if (E->isTypeDependent() || E->isValueDependent())
4727    return;
4728
4729  // Check for array bounds violations in cases where the check isn't triggered
4730  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
4731  // ArraySubscriptExpr is on the RHS of a variable initialization.
4732  CheckArrayAccess(E);
4733
4734  // This is not the right CC for (e.g.) a variable initialization.
4735  AnalyzeImplicitConversions(*this, E, CC);
4736}
4737
4738void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
4739                                       FieldDecl *BitField,
4740                                       Expr *Init) {
4741  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
4742}
4743
4744/// CheckParmsForFunctionDef - Check that the parameters of the given
4745/// function are appropriate for the definition of a function. This
4746/// takes care of any checks that cannot be performed on the
4747/// declaration itself, e.g., that the types of each of the function
4748/// parameters are complete.
4749bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
4750                                    bool CheckParameterNames) {
4751  bool HasInvalidParm = false;
4752  for (; P != PEnd; ++P) {
4753    ParmVarDecl *Param = *P;
4754
4755    // C99 6.7.5.3p4: the parameters in a parameter type list in a
4756    // function declarator that is part of a function definition of
4757    // that function shall not have incomplete type.
4758    //
4759    // This is also C++ [dcl.fct]p6.
4760    if (!Param->isInvalidDecl() &&
4761        RequireCompleteType(Param->getLocation(), Param->getType(),
4762                            diag::err_typecheck_decl_incomplete_type)) {
4763      Param->setInvalidDecl();
4764      HasInvalidParm = true;
4765    }
4766
4767    // C99 6.9.1p5: If the declarator includes a parameter type list, the
4768    // declaration of each parameter shall include an identifier.
4769    if (CheckParameterNames &&
4770        Param->getIdentifier() == 0 &&
4771        !Param->isImplicit() &&
4772        !getLangOpts().CPlusPlus)
4773      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
4774
4775    // C99 6.7.5.3p12:
4776    //   If the function declarator is not part of a definition of that
4777    //   function, parameters may have incomplete type and may use the [*]
4778    //   notation in their sequences of declarator specifiers to specify
4779    //   variable length array types.
4780    QualType PType = Param->getOriginalType();
4781    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
4782      if (AT->getSizeModifier() == ArrayType::Star) {
4783        // FIXME: This diagnosic should point the '[*]' if source-location
4784        // information is added for it.
4785        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
4786      }
4787    }
4788  }
4789
4790  return HasInvalidParm;
4791}
4792
4793/// CheckCastAlign - Implements -Wcast-align, which warns when a
4794/// pointer cast increases the alignment requirements.
4795void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
4796  // This is actually a lot of work to potentially be doing on every
4797  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
4798  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
4799                                          TRange.getBegin())
4800        == DiagnosticsEngine::Ignored)
4801    return;
4802
4803  // Ignore dependent types.
4804  if (T->isDependentType() || Op->getType()->isDependentType())
4805    return;
4806
4807  // Require that the destination be a pointer type.
4808  const PointerType *DestPtr = T->getAs<PointerType>();
4809  if (!DestPtr) return;
4810
4811  // If the destination has alignment 1, we're done.
4812  QualType DestPointee = DestPtr->getPointeeType();
4813  if (DestPointee->isIncompleteType()) return;
4814  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
4815  if (DestAlign.isOne()) return;
4816
4817  // Require that the source be a pointer type.
4818  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
4819  if (!SrcPtr) return;
4820  QualType SrcPointee = SrcPtr->getPointeeType();
4821
4822  // Whitelist casts from cv void*.  We already implicitly
4823  // whitelisted casts to cv void*, since they have alignment 1.
4824  // Also whitelist casts involving incomplete types, which implicitly
4825  // includes 'void'.
4826  if (SrcPointee->isIncompleteType()) return;
4827
4828  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
4829  if (SrcAlign >= DestAlign) return;
4830
4831  Diag(TRange.getBegin(), diag::warn_cast_align)
4832    << Op->getType() << T
4833    << static_cast<unsigned>(SrcAlign.getQuantity())
4834    << static_cast<unsigned>(DestAlign.getQuantity())
4835    << TRange << Op->getSourceRange();
4836}
4837
4838static const Type* getElementType(const Expr *BaseExpr) {
4839  const Type* EltType = BaseExpr->getType().getTypePtr();
4840  if (EltType->isAnyPointerType())
4841    return EltType->getPointeeType().getTypePtr();
4842  else if (EltType->isArrayType())
4843    return EltType->getBaseElementTypeUnsafe();
4844  return EltType;
4845}
4846
4847/// \brief Check whether this array fits the idiom of a size-one tail padded
4848/// array member of a struct.
4849///
4850/// We avoid emitting out-of-bounds access warnings for such arrays as they are
4851/// commonly used to emulate flexible arrays in C89 code.
4852static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
4853                                    const NamedDecl *ND) {
4854  if (Size != 1 || !ND) return false;
4855
4856  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
4857  if (!FD) return false;
4858
4859  // Don't consider sizes resulting from macro expansions or template argument
4860  // substitution to form C89 tail-padded arrays.
4861
4862  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
4863  while (TInfo) {
4864    TypeLoc TL = TInfo->getTypeLoc();
4865    // Look through typedefs.
4866    const TypedefTypeLoc *TTL = dyn_cast<TypedefTypeLoc>(&TL);
4867    if (TTL) {
4868      const TypedefNameDecl *TDL = TTL->getTypedefNameDecl();
4869      TInfo = TDL->getTypeSourceInfo();
4870      continue;
4871    }
4872    ConstantArrayTypeLoc CTL = cast<ConstantArrayTypeLoc>(TL);
4873    const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
4874    if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
4875      return false;
4876    break;
4877  }
4878
4879  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
4880  if (!RD) return false;
4881  if (RD->isUnion()) return false;
4882  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
4883    if (!CRD->isStandardLayout()) return false;
4884  }
4885
4886  // See if this is the last field decl in the record.
4887  const Decl *D = FD;
4888  while ((D = D->getNextDeclInContext()))
4889    if (isa<FieldDecl>(D))
4890      return false;
4891  return true;
4892}
4893
4894void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
4895                            const ArraySubscriptExpr *ASE,
4896                            bool AllowOnePastEnd, bool IndexNegated) {
4897  IndexExpr = IndexExpr->IgnoreParenImpCasts();
4898  if (IndexExpr->isValueDependent())
4899    return;
4900
4901  const Type *EffectiveType = getElementType(BaseExpr);
4902  BaseExpr = BaseExpr->IgnoreParenCasts();
4903  const ConstantArrayType *ArrayTy =
4904    Context.getAsConstantArrayType(BaseExpr->getType());
4905  if (!ArrayTy)
4906    return;
4907
4908  llvm::APSInt index;
4909  if (!IndexExpr->EvaluateAsInt(index, Context))
4910    return;
4911  if (IndexNegated)
4912    index = -index;
4913
4914  const NamedDecl *ND = NULL;
4915  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4916    ND = dyn_cast<NamedDecl>(DRE->getDecl());
4917  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4918    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4919
4920  if (index.isUnsigned() || !index.isNegative()) {
4921    llvm::APInt size = ArrayTy->getSize();
4922    if (!size.isStrictlyPositive())
4923      return;
4924
4925    const Type* BaseType = getElementType(BaseExpr);
4926    if (BaseType != EffectiveType) {
4927      // Make sure we're comparing apples to apples when comparing index to size
4928      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
4929      uint64_t array_typesize = Context.getTypeSize(BaseType);
4930      // Handle ptrarith_typesize being zero, such as when casting to void*
4931      if (!ptrarith_typesize) ptrarith_typesize = 1;
4932      if (ptrarith_typesize != array_typesize) {
4933        // There's a cast to a different size type involved
4934        uint64_t ratio = array_typesize / ptrarith_typesize;
4935        // TODO: Be smarter about handling cases where array_typesize is not a
4936        // multiple of ptrarith_typesize
4937        if (ptrarith_typesize * ratio == array_typesize)
4938          size *= llvm::APInt(size.getBitWidth(), ratio);
4939      }
4940    }
4941
4942    if (size.getBitWidth() > index.getBitWidth())
4943      index = index.zext(size.getBitWidth());
4944    else if (size.getBitWidth() < index.getBitWidth())
4945      size = size.zext(index.getBitWidth());
4946
4947    // For array subscripting the index must be less than size, but for pointer
4948    // arithmetic also allow the index (offset) to be equal to size since
4949    // computing the next address after the end of the array is legal and
4950    // commonly done e.g. in C++ iterators and range-based for loops.
4951    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
4952      return;
4953
4954    // Also don't warn for arrays of size 1 which are members of some
4955    // structure. These are often used to approximate flexible arrays in C89
4956    // code.
4957    if (IsTailPaddedMemberArray(*this, size, ND))
4958      return;
4959
4960    // Suppress the warning if the subscript expression (as identified by the
4961    // ']' location) and the index expression are both from macro expansions
4962    // within a system header.
4963    if (ASE) {
4964      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
4965          ASE->getRBracketLoc());
4966      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
4967        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
4968            IndexExpr->getLocStart());
4969        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
4970          return;
4971      }
4972    }
4973
4974    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
4975    if (ASE)
4976      DiagID = diag::warn_array_index_exceeds_bounds;
4977
4978    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4979                        PDiag(DiagID) << index.toString(10, true)
4980                          << size.toString(10, true)
4981                          << (unsigned)size.getLimitedValue(~0U)
4982                          << IndexExpr->getSourceRange());
4983  } else {
4984    unsigned DiagID = diag::warn_array_index_precedes_bounds;
4985    if (!ASE) {
4986      DiagID = diag::warn_ptr_arith_precedes_bounds;
4987      if (index.isNegative()) index = -index;
4988    }
4989
4990    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4991                        PDiag(DiagID) << index.toString(10, true)
4992                          << IndexExpr->getSourceRange());
4993  }
4994
4995  if (!ND) {
4996    // Try harder to find a NamedDecl to point at in the note.
4997    while (const ArraySubscriptExpr *ASE =
4998           dyn_cast<ArraySubscriptExpr>(BaseExpr))
4999      BaseExpr = ASE->getBase()->IgnoreParenCasts();
5000    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
5001      ND = dyn_cast<NamedDecl>(DRE->getDecl());
5002    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
5003      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
5004  }
5005
5006  if (ND)
5007    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
5008                        PDiag(diag::note_array_index_out_of_bounds)
5009                          << ND->getDeclName());
5010}
5011
5012void Sema::CheckArrayAccess(const Expr *expr) {
5013  int AllowOnePastEnd = 0;
5014  while (expr) {
5015    expr = expr->IgnoreParenImpCasts();
5016    switch (expr->getStmtClass()) {
5017      case Stmt::ArraySubscriptExprClass: {
5018        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
5019        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
5020                         AllowOnePastEnd > 0);
5021        return;
5022      }
5023      case Stmt::UnaryOperatorClass: {
5024        // Only unwrap the * and & unary operators
5025        const UnaryOperator *UO = cast<UnaryOperator>(expr);
5026        expr = UO->getSubExpr();
5027        switch (UO->getOpcode()) {
5028          case UO_AddrOf:
5029            AllowOnePastEnd++;
5030            break;
5031          case UO_Deref:
5032            AllowOnePastEnd--;
5033            break;
5034          default:
5035            return;
5036        }
5037        break;
5038      }
5039      case Stmt::ConditionalOperatorClass: {
5040        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
5041        if (const Expr *lhs = cond->getLHS())
5042          CheckArrayAccess(lhs);
5043        if (const Expr *rhs = cond->getRHS())
5044          CheckArrayAccess(rhs);
5045        return;
5046      }
5047      default:
5048        return;
5049    }
5050  }
5051}
5052
5053//===--- CHECK: Objective-C retain cycles ----------------------------------//
5054
5055namespace {
5056  struct RetainCycleOwner {
5057    RetainCycleOwner() : Variable(0), Indirect(false) {}
5058    VarDecl *Variable;
5059    SourceRange Range;
5060    SourceLocation Loc;
5061    bool Indirect;
5062
5063    void setLocsFrom(Expr *e) {
5064      Loc = e->getExprLoc();
5065      Range = e->getSourceRange();
5066    }
5067  };
5068}
5069
5070/// Consider whether capturing the given variable can possibly lead to
5071/// a retain cycle.
5072static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
5073  // In ARC, it's captured strongly iff the variable has __strong
5074  // lifetime.  In MRR, it's captured strongly if the variable is
5075  // __block and has an appropriate type.
5076  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
5077    return false;
5078
5079  owner.Variable = var;
5080  owner.setLocsFrom(ref);
5081  return true;
5082}
5083
5084static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
5085  while (true) {
5086    e = e->IgnoreParens();
5087    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
5088      switch (cast->getCastKind()) {
5089      case CK_BitCast:
5090      case CK_LValueBitCast:
5091      case CK_LValueToRValue:
5092      case CK_ARCReclaimReturnedObject:
5093        e = cast->getSubExpr();
5094        continue;
5095
5096      default:
5097        return false;
5098      }
5099    }
5100
5101    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
5102      ObjCIvarDecl *ivar = ref->getDecl();
5103      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
5104        return false;
5105
5106      // Try to find a retain cycle in the base.
5107      if (!findRetainCycleOwner(S, ref->getBase(), owner))
5108        return false;
5109
5110      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
5111      owner.Indirect = true;
5112      return true;
5113    }
5114
5115    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
5116      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
5117      if (!var) return false;
5118      return considerVariable(var, ref, owner);
5119    }
5120
5121    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
5122      if (member->isArrow()) return false;
5123
5124      // Don't count this as an indirect ownership.
5125      e = member->getBase();
5126      continue;
5127    }
5128
5129    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
5130      // Only pay attention to pseudo-objects on property references.
5131      ObjCPropertyRefExpr *pre
5132        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
5133                                              ->IgnoreParens());
5134      if (!pre) return false;
5135      if (pre->isImplicitProperty()) return false;
5136      ObjCPropertyDecl *property = pre->getExplicitProperty();
5137      if (!property->isRetaining() &&
5138          !(property->getPropertyIvarDecl() &&
5139            property->getPropertyIvarDecl()->getType()
5140              .getObjCLifetime() == Qualifiers::OCL_Strong))
5141          return false;
5142
5143      owner.Indirect = true;
5144      if (pre->isSuperReceiver()) {
5145        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
5146        if (!owner.Variable)
5147          return false;
5148        owner.Loc = pre->getLocation();
5149        owner.Range = pre->getSourceRange();
5150        return true;
5151      }
5152      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
5153                              ->getSourceExpr());
5154      continue;
5155    }
5156
5157    // Array ivars?
5158
5159    return false;
5160  }
5161}
5162
5163namespace {
5164  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
5165    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
5166      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
5167        Variable(variable), Capturer(0) {}
5168
5169    VarDecl *Variable;
5170    Expr *Capturer;
5171
5172    void VisitDeclRefExpr(DeclRefExpr *ref) {
5173      if (ref->getDecl() == Variable && !Capturer)
5174        Capturer = ref;
5175    }
5176
5177    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
5178      if (Capturer) return;
5179      Visit(ref->getBase());
5180      if (Capturer && ref->isFreeIvar())
5181        Capturer = ref;
5182    }
5183
5184    void VisitBlockExpr(BlockExpr *block) {
5185      // Look inside nested blocks
5186      if (block->getBlockDecl()->capturesVariable(Variable))
5187        Visit(block->getBlockDecl()->getBody());
5188    }
5189  };
5190}
5191
5192/// Check whether the given argument is a block which captures a
5193/// variable.
5194static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
5195  assert(owner.Variable && owner.Loc.isValid());
5196
5197  e = e->IgnoreParenCasts();
5198  BlockExpr *block = dyn_cast<BlockExpr>(e);
5199  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
5200    return 0;
5201
5202  FindCaptureVisitor visitor(S.Context, owner.Variable);
5203  visitor.Visit(block->getBlockDecl()->getBody());
5204  return visitor.Capturer;
5205}
5206
5207static void diagnoseRetainCycle(Sema &S, Expr *capturer,
5208                                RetainCycleOwner &owner) {
5209  assert(capturer);
5210  assert(owner.Variable && owner.Loc.isValid());
5211
5212  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
5213    << owner.Variable << capturer->getSourceRange();
5214  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
5215    << owner.Indirect << owner.Range;
5216}
5217
5218/// Check for a keyword selector that starts with the word 'add' or
5219/// 'set'.
5220static bool isSetterLikeSelector(Selector sel) {
5221  if (sel.isUnarySelector()) return false;
5222
5223  StringRef str = sel.getNameForSlot(0);
5224  while (!str.empty() && str.front() == '_') str = str.substr(1);
5225  if (str.startswith("set"))
5226    str = str.substr(3);
5227  else if (str.startswith("add")) {
5228    // Specially whitelist 'addOperationWithBlock:'.
5229    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
5230      return false;
5231    str = str.substr(3);
5232  }
5233  else
5234    return false;
5235
5236  if (str.empty()) return true;
5237  return !islower(str.front());
5238}
5239
5240/// Check a message send to see if it's likely to cause a retain cycle.
5241void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
5242  // Only check instance methods whose selector looks like a setter.
5243  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
5244    return;
5245
5246  // Try to find a variable that the receiver is strongly owned by.
5247  RetainCycleOwner owner;
5248  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
5249    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
5250      return;
5251  } else {
5252    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
5253    owner.Variable = getCurMethodDecl()->getSelfDecl();
5254    owner.Loc = msg->getSuperLoc();
5255    owner.Range = msg->getSuperLoc();
5256  }
5257
5258  // Check whether the receiver is captured by any of the arguments.
5259  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
5260    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
5261      return diagnoseRetainCycle(*this, capturer, owner);
5262}
5263
5264/// Check a property assign to see if it's likely to cause a retain cycle.
5265void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
5266  RetainCycleOwner owner;
5267  if (!findRetainCycleOwner(*this, receiver, owner))
5268    return;
5269
5270  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
5271    diagnoseRetainCycle(*this, capturer, owner);
5272}
5273
5274bool Sema::checkUnsafeAssigns(SourceLocation Loc,
5275                              QualType LHS, Expr *RHS) {
5276  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
5277  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
5278    return false;
5279  // strip off any implicit cast added to get to the one arc-specific
5280  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5281    if (cast->getCastKind() == CK_ARCConsumeObject) {
5282      Diag(Loc, diag::warn_arc_retained_assign)
5283        << (LT == Qualifiers::OCL_ExplicitNone) << 1
5284        << RHS->getSourceRange();
5285      return true;
5286    }
5287    RHS = cast->getSubExpr();
5288  }
5289  return false;
5290}
5291
5292void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
5293                              Expr *LHS, Expr *RHS) {
5294  QualType LHSType;
5295  // PropertyRef on LHS type need be directly obtained from
5296  // its declaration as it has a PsuedoType.
5297  ObjCPropertyRefExpr *PRE
5298    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
5299  if (PRE && !PRE->isImplicitProperty()) {
5300    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5301    if (PD)
5302      LHSType = PD->getType();
5303  }
5304
5305  if (LHSType.isNull())
5306    LHSType = LHS->getType();
5307  if (checkUnsafeAssigns(Loc, LHSType, RHS))
5308    return;
5309  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
5310  // FIXME. Check for other life times.
5311  if (LT != Qualifiers::OCL_None)
5312    return;
5313
5314  if (PRE) {
5315    if (PRE->isImplicitProperty())
5316      return;
5317    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5318    if (!PD)
5319      return;
5320
5321    unsigned Attributes = PD->getPropertyAttributes();
5322    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
5323      // when 'assign' attribute was not explicitly specified
5324      // by user, ignore it and rely on property type itself
5325      // for lifetime info.
5326      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
5327      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
5328          LHSType->isObjCRetainableType())
5329        return;
5330
5331      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5332        if (cast->getCastKind() == CK_ARCConsumeObject) {
5333          Diag(Loc, diag::warn_arc_retained_property_assign)
5334          << RHS->getSourceRange();
5335          return;
5336        }
5337        RHS = cast->getSubExpr();
5338      }
5339    }
5340    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
5341      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5342        if (cast->getCastKind() == CK_ARCConsumeObject) {
5343          Diag(Loc, diag::warn_arc_retained_assign)
5344          << 0 << 0<< RHS->getSourceRange();
5345          return;
5346        }
5347        RHS = cast->getSubExpr();
5348      }
5349    }
5350  }
5351}
5352
5353//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
5354
5355namespace {
5356bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
5357                                 SourceLocation StmtLoc,
5358                                 const NullStmt *Body) {
5359  // Do not warn if the body is a macro that expands to nothing, e.g:
5360  //
5361  // #define CALL(x)
5362  // if (condition)
5363  //   CALL(0);
5364  //
5365  if (Body->hasLeadingEmptyMacro())
5366    return false;
5367
5368  // Get line numbers of statement and body.
5369  bool StmtLineInvalid;
5370  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
5371                                                      &StmtLineInvalid);
5372  if (StmtLineInvalid)
5373    return false;
5374
5375  bool BodyLineInvalid;
5376  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
5377                                                      &BodyLineInvalid);
5378  if (BodyLineInvalid)
5379    return false;
5380
5381  // Warn if null statement and body are on the same line.
5382  if (StmtLine != BodyLine)
5383    return false;
5384
5385  return true;
5386}
5387} // Unnamed namespace
5388
5389void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
5390                                 const Stmt *Body,
5391                                 unsigned DiagID) {
5392  // Since this is a syntactic check, don't emit diagnostic for template
5393  // instantiations, this just adds noise.
5394  if (CurrentInstantiationScope)
5395    return;
5396
5397  // The body should be a null statement.
5398  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5399  if (!NBody)
5400    return;
5401
5402  // Do the usual checks.
5403  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5404    return;
5405
5406  Diag(NBody->getSemiLoc(), DiagID);
5407  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5408}
5409
5410void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
5411                                 const Stmt *PossibleBody) {
5412  assert(!CurrentInstantiationScope); // Ensured by caller
5413
5414  SourceLocation StmtLoc;
5415  const Stmt *Body;
5416  unsigned DiagID;
5417  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
5418    StmtLoc = FS->getRParenLoc();
5419    Body = FS->getBody();
5420    DiagID = diag::warn_empty_for_body;
5421  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
5422    StmtLoc = WS->getCond()->getSourceRange().getEnd();
5423    Body = WS->getBody();
5424    DiagID = diag::warn_empty_while_body;
5425  } else
5426    return; // Neither `for' nor `while'.
5427
5428  // The body should be a null statement.
5429  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5430  if (!NBody)
5431    return;
5432
5433  // Skip expensive checks if diagnostic is disabled.
5434  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
5435          DiagnosticsEngine::Ignored)
5436    return;
5437
5438  // Do the usual checks.
5439  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5440    return;
5441
5442  // `for(...);' and `while(...);' are popular idioms, so in order to keep
5443  // noise level low, emit diagnostics only if for/while is followed by a
5444  // CompoundStmt, e.g.:
5445  //    for (int i = 0; i < n; i++);
5446  //    {
5447  //      a(i);
5448  //    }
5449  // or if for/while is followed by a statement with more indentation
5450  // than for/while itself:
5451  //    for (int i = 0; i < n; i++);
5452  //      a(i);
5453  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
5454  if (!ProbableTypo) {
5455    bool BodyColInvalid;
5456    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
5457                             PossibleBody->getLocStart(),
5458                             &BodyColInvalid);
5459    if (BodyColInvalid)
5460      return;
5461
5462    bool StmtColInvalid;
5463    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
5464                             S->getLocStart(),
5465                             &StmtColInvalid);
5466    if (StmtColInvalid)
5467      return;
5468
5469    if (BodyCol > StmtCol)
5470      ProbableTypo = true;
5471  }
5472
5473  if (ProbableTypo) {
5474    Diag(NBody->getSemiLoc(), DiagID);
5475    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5476  }
5477}
5478