SemaChecking.cpp revision 862ff87c0d306af8dfdbe7ac59f181a5815546e5 
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/Sema.h"
16#include "clang/Sema/SemaInternal.h"
17#include "clang/Sema/ScopeInfo.h"
18#include "clang/Analysis/Analyses/FormatString.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/CharUnits.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/DeclObjC.h"
23#include "clang/AST/ExprCXX.h"
24#include "clang/AST/ExprObjC.h"
25#include "clang/AST/EvaluatedExprVisitor.h"
26#include "clang/AST/DeclObjC.h"
27#include "clang/AST/StmtCXX.h"
28#include "clang/AST/StmtObjC.h"
29#include "clang/Lex/Preprocessor.h"
30#include "llvm/ADT/BitVector.h"
31#include "llvm/ADT/STLExtras.h"
32#include "llvm/Support/raw_ostream.h"
33#include "clang/Basic/TargetBuiltins.h"
34#include "clang/Basic/TargetInfo.h"
35#include "clang/Basic/ConvertUTF.h"
36#include <limits>
37using namespace clang;
38using namespace sema;
39
40SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
41                                                    unsigned ByteNo) const {
42  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
43                               PP.getLangOptions(), PP.getTargetInfo());
44}
45
46
47/// CheckablePrintfAttr - does a function call have a "printf" attribute
48/// and arguments that merit checking?
49bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) {
50  if (Format->getType() == "printf") return true;
51  if (Format->getType() == "printf0") {
52    // printf0 allows null "format" string; if so don't check format/args
53    unsigned format_idx = Format->getFormatIdx() - 1;
54    // Does the index refer to the implicit object argument?
55    if (isa<CXXMemberCallExpr>(TheCall)) {
56      if (format_idx == 0)
57        return false;
58      --format_idx;
59    }
60    if (format_idx < TheCall->getNumArgs()) {
61      Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts();
62      if (!Format->isNullPointerConstant(Context,
63                                         Expr::NPC_ValueDependentIsNull))
64        return true;
65    }
66  }
67  return false;
68}
69
70/// Checks that a call expression's argument count is the desired number.
71/// This is useful when doing custom type-checking.  Returns true on error.
72static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
73  unsigned argCount = call->getNumArgs();
74  if (argCount == desiredArgCount) return false;
75
76  if (argCount < desiredArgCount)
77    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
78        << 0 /*function call*/ << desiredArgCount << argCount
79        << call->getSourceRange();
80
81  // Highlight all the excess arguments.
82  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
83                    call->getArg(argCount - 1)->getLocEnd());
84
85  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
86    << 0 /*function call*/ << desiredArgCount << argCount
87    << call->getArg(1)->getSourceRange();
88}
89
90ExprResult
91Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
92  ExprResult TheCallResult(Owned(TheCall));
93
94  // Find out if any arguments are required to be integer constant expressions.
95  unsigned ICEArguments = 0;
96  ASTContext::GetBuiltinTypeError Error;
97  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
98  if (Error != ASTContext::GE_None)
99    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
100
101  // If any arguments are required to be ICE's, check and diagnose.
102  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
103    // Skip arguments not required to be ICE's.
104    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
105
106    llvm::APSInt Result;
107    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
108      return true;
109    ICEArguments &= ~(1 << ArgNo);
110  }
111
112  switch (BuiltinID) {
113  case Builtin::BI__builtin___CFStringMakeConstantString:
114    assert(TheCall->getNumArgs() == 1 &&
115           "Wrong # arguments to builtin CFStringMakeConstantString");
116    if (CheckObjCString(TheCall->getArg(0)))
117      return ExprError();
118    break;
119  case Builtin::BI__builtin_stdarg_start:
120  case Builtin::BI__builtin_va_start:
121    if (SemaBuiltinVAStart(TheCall))
122      return ExprError();
123    break;
124  case Builtin::BI__builtin_isgreater:
125  case Builtin::BI__builtin_isgreaterequal:
126  case Builtin::BI__builtin_isless:
127  case Builtin::BI__builtin_islessequal:
128  case Builtin::BI__builtin_islessgreater:
129  case Builtin::BI__builtin_isunordered:
130    if (SemaBuiltinUnorderedCompare(TheCall))
131      return ExprError();
132    break;
133  case Builtin::BI__builtin_fpclassify:
134    if (SemaBuiltinFPClassification(TheCall, 6))
135      return ExprError();
136    break;
137  case Builtin::BI__builtin_isfinite:
138  case Builtin::BI__builtin_isinf:
139  case Builtin::BI__builtin_isinf_sign:
140  case Builtin::BI__builtin_isnan:
141  case Builtin::BI__builtin_isnormal:
142    if (SemaBuiltinFPClassification(TheCall, 1))
143      return ExprError();
144    break;
145  case Builtin::BI__builtin_shufflevector:
146    return SemaBuiltinShuffleVector(TheCall);
147    // TheCall will be freed by the smart pointer here, but that's fine, since
148    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
149  case Builtin::BI__builtin_prefetch:
150    if (SemaBuiltinPrefetch(TheCall))
151      return ExprError();
152    break;
153  case Builtin::BI__builtin_object_size:
154    if (SemaBuiltinObjectSize(TheCall))
155      return ExprError();
156    break;
157  case Builtin::BI__builtin_longjmp:
158    if (SemaBuiltinLongjmp(TheCall))
159      return ExprError();
160    break;
161
162  case Builtin::BI__builtin_classify_type:
163    if (checkArgCount(*this, TheCall, 1)) return true;
164    TheCall->setType(Context.IntTy);
165    break;
166  case Builtin::BI__builtin_constant_p:
167    if (checkArgCount(*this, TheCall, 1)) return true;
168    TheCall->setType(Context.IntTy);
169    break;
170  case Builtin::BI__sync_fetch_and_add:
171  case Builtin::BI__sync_fetch_and_sub:
172  case Builtin::BI__sync_fetch_and_or:
173  case Builtin::BI__sync_fetch_and_and:
174  case Builtin::BI__sync_fetch_and_xor:
175  case Builtin::BI__sync_add_and_fetch:
176  case Builtin::BI__sync_sub_and_fetch:
177  case Builtin::BI__sync_and_and_fetch:
178  case Builtin::BI__sync_or_and_fetch:
179  case Builtin::BI__sync_xor_and_fetch:
180  case Builtin::BI__sync_val_compare_and_swap:
181  case Builtin::BI__sync_bool_compare_and_swap:
182  case Builtin::BI__sync_lock_test_and_set:
183  case Builtin::BI__sync_lock_release:
184  case Builtin::BI__sync_swap:
185    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
186  }
187
188  // Since the target specific builtins for each arch overlap, only check those
189  // of the arch we are compiling for.
190  if (BuiltinID >= Builtin::FirstTSBuiltin) {
191    switch (Context.Target.getTriple().getArch()) {
192      case llvm::Triple::arm:
193      case llvm::Triple::thumb:
194        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
195          return ExprError();
196        break;
197      default:
198        break;
199    }
200  }
201
202  return move(TheCallResult);
203}
204
205// Get the valid immediate range for the specified NEON type code.
206static unsigned RFT(unsigned t, bool shift = false) {
207  bool quad = t & 0x10;
208
209  switch (t & 0x7) {
210    case 0: // i8
211      return shift ? 7 : (8 << (int)quad) - 1;
212    case 1: // i16
213      return shift ? 15 : (4 << (int)quad) - 1;
214    case 2: // i32
215      return shift ? 31 : (2 << (int)quad) - 1;
216    case 3: // i64
217      return shift ? 63 : (1 << (int)quad) - 1;
218    case 4: // f32
219      assert(!shift && "cannot shift float types!");
220      return (2 << (int)quad) - 1;
221    case 5: // poly8
222      return shift ? 7 : (8 << (int)quad) - 1;
223    case 6: // poly16
224      return shift ? 15 : (4 << (int)quad) - 1;
225    case 7: // float16
226      assert(!shift && "cannot shift float types!");
227      return (4 << (int)quad) - 1;
228  }
229  return 0;
230}
231
232bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
233  llvm::APSInt Result;
234
235  unsigned mask = 0;
236  unsigned TV = 0;
237  switch (BuiltinID) {
238#define GET_NEON_OVERLOAD_CHECK
239#include "clang/Basic/arm_neon.inc"
240#undef GET_NEON_OVERLOAD_CHECK
241  }
242
243  // For NEON intrinsics which are overloaded on vector element type, validate
244  // the immediate which specifies which variant to emit.
245  if (mask) {
246    unsigned ArgNo = TheCall->getNumArgs()-1;
247    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
248      return true;
249
250    TV = Result.getLimitedValue(32);
251    if ((TV > 31) || (mask & (1 << TV)) == 0)
252      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
253        << TheCall->getArg(ArgNo)->getSourceRange();
254  }
255
256  // For NEON intrinsics which take an immediate value as part of the
257  // instruction, range check them here.
258  unsigned i = 0, l = 0, u = 0;
259  switch (BuiltinID) {
260  default: return false;
261  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
262  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
263  case ARM::BI__builtin_arm_vcvtr_f:
264  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
265#define GET_NEON_IMMEDIATE_CHECK
266#include "clang/Basic/arm_neon.inc"
267#undef GET_NEON_IMMEDIATE_CHECK
268  };
269
270  // Check that the immediate argument is actually a constant.
271  if (SemaBuiltinConstantArg(TheCall, i, Result))
272    return true;
273
274  // Range check against the upper/lower values for this isntruction.
275  unsigned Val = Result.getZExtValue();
276  if (Val < l || Val > (u + l))
277    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
278      << l << u+l << TheCall->getArg(i)->getSourceRange();
279
280  // FIXME: VFP Intrinsics should error if VFP not present.
281  return false;
282}
283
284/// CheckFunctionCall - Check a direct function call for various correctness
285/// and safety properties not strictly enforced by the C type system.
286bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
287  // Get the IdentifierInfo* for the called function.
288  IdentifierInfo *FnInfo = FDecl->getIdentifier();
289
290  // None of the checks below are needed for functions that don't have
291  // simple names (e.g., C++ conversion functions).
292  if (!FnInfo)
293    return false;
294
295  // FIXME: This mechanism should be abstracted to be less fragile and
296  // more efficient. For example, just map function ids to custom
297  // handlers.
298
299  // Printf and scanf checking.
300  for (specific_attr_iterator<FormatAttr>
301         i = FDecl->specific_attr_begin<FormatAttr>(),
302         e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
303
304    const FormatAttr *Format = *i;
305    const bool b = Format->getType() == "scanf";
306    if (b || CheckablePrintfAttr(Format, TheCall)) {
307      bool HasVAListArg = Format->getFirstArg() == 0;
308      CheckPrintfScanfArguments(TheCall, HasVAListArg,
309                                Format->getFormatIdx() - 1,
310                                HasVAListArg ? 0 : Format->getFirstArg() - 1,
311                                !b);
312    }
313  }
314
315  for (specific_attr_iterator<NonNullAttr>
316         i = FDecl->specific_attr_begin<NonNullAttr>(),
317         e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) {
318    CheckNonNullArguments(*i, TheCall->getArgs(),
319                          TheCall->getCallee()->getLocStart());
320  }
321
322  // Memset/memcpy/memmove handling
323  int CMF = -1;
324  switch (FDecl->getBuiltinID()) {
325  case Builtin::BI__builtin_memset:
326  case Builtin::BI__builtin___memset_chk:
327  case Builtin::BImemset:
328    CMF = CMF_Memset;
329    break;
330
331  case Builtin::BI__builtin_memcpy:
332  case Builtin::BI__builtin___memcpy_chk:
333  case Builtin::BImemcpy:
334    CMF = CMF_Memcpy;
335    break;
336
337  case Builtin::BI__builtin_memmove:
338  case Builtin::BI__builtin___memmove_chk:
339  case Builtin::BImemmove:
340    CMF = CMF_Memmove;
341    break;
342
343  default:
344    if (FDecl->getLinkage() == ExternalLinkage &&
345        (!getLangOptions().CPlusPlus || FDecl->isExternC())) {
346      if (FnInfo->isStr("memset"))
347        CMF = CMF_Memset;
348      else if (FnInfo->isStr("memcpy"))
349        CMF = CMF_Memcpy;
350      else if (FnInfo->isStr("memmove"))
351        CMF = CMF_Memmove;
352    }
353    break;
354  }
355
356  if (CMF != -1)
357    CheckMemsetcpymoveArguments(TheCall, CheckedMemoryFunction(CMF), FnInfo);
358
359  return false;
360}
361
362bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
363  // Printf checking.
364  const FormatAttr *Format = NDecl->getAttr<FormatAttr>();
365  if (!Format)
366    return false;
367
368  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
369  if (!V)
370    return false;
371
372  QualType Ty = V->getType();
373  if (!Ty->isBlockPointerType())
374    return false;
375
376  const bool b = Format->getType() == "scanf";
377  if (!b && !CheckablePrintfAttr(Format, TheCall))
378    return false;
379
380  bool HasVAListArg = Format->getFirstArg() == 0;
381  CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
382                            HasVAListArg ? 0 : Format->getFirstArg() - 1, !b);
383
384  return false;
385}
386
387/// SemaBuiltinAtomicOverloaded - We have a call to a function like
388/// __sync_fetch_and_add, which is an overloaded function based on the pointer
389/// type of its first argument.  The main ActOnCallExpr routines have already
390/// promoted the types of arguments because all of these calls are prototyped as
391/// void(...).
392///
393/// This function goes through and does final semantic checking for these
394/// builtins,
395ExprResult
396Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
397  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
398  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
399  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
400
401  // Ensure that we have at least one argument to do type inference from.
402  if (TheCall->getNumArgs() < 1) {
403    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
404      << 0 << 1 << TheCall->getNumArgs()
405      << TheCall->getCallee()->getSourceRange();
406    return ExprError();
407  }
408
409  // Inspect the first argument of the atomic builtin.  This should always be
410  // a pointer type, whose element is an integral scalar or pointer type.
411  // Because it is a pointer type, we don't have to worry about any implicit
412  // casts here.
413  // FIXME: We don't allow floating point scalars as input.
414  Expr *FirstArg = TheCall->getArg(0);
415  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
416  if (!pointerType) {
417    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
418      << FirstArg->getType() << FirstArg->getSourceRange();
419    return ExprError();
420  }
421
422  QualType ValType = pointerType->getPointeeType();
423  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
424      !ValType->isBlockPointerType()) {
425    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
426      << FirstArg->getType() << FirstArg->getSourceRange();
427    return ExprError();
428  }
429
430  switch (ValType.getObjCLifetime()) {
431  case Qualifiers::OCL_None:
432  case Qualifiers::OCL_ExplicitNone:
433    // okay
434    break;
435
436  case Qualifiers::OCL_Weak:
437  case Qualifiers::OCL_Strong:
438  case Qualifiers::OCL_Autoreleasing:
439    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
440      << ValType << FirstArg->getSourceRange();
441    return ExprError();
442  }
443
444  // The majority of builtins return a value, but a few have special return
445  // types, so allow them to override appropriately below.
446  QualType ResultType = ValType;
447
448  // We need to figure out which concrete builtin this maps onto.  For example,
449  // __sync_fetch_and_add with a 2 byte object turns into
450  // __sync_fetch_and_add_2.
451#define BUILTIN_ROW(x) \
452  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
453    Builtin::BI##x##_8, Builtin::BI##x##_16 }
454
455  static const unsigned BuiltinIndices[][5] = {
456    BUILTIN_ROW(__sync_fetch_and_add),
457    BUILTIN_ROW(__sync_fetch_and_sub),
458    BUILTIN_ROW(__sync_fetch_and_or),
459    BUILTIN_ROW(__sync_fetch_and_and),
460    BUILTIN_ROW(__sync_fetch_and_xor),
461
462    BUILTIN_ROW(__sync_add_and_fetch),
463    BUILTIN_ROW(__sync_sub_and_fetch),
464    BUILTIN_ROW(__sync_and_and_fetch),
465    BUILTIN_ROW(__sync_or_and_fetch),
466    BUILTIN_ROW(__sync_xor_and_fetch),
467
468    BUILTIN_ROW(__sync_val_compare_and_swap),
469    BUILTIN_ROW(__sync_bool_compare_and_swap),
470    BUILTIN_ROW(__sync_lock_test_and_set),
471    BUILTIN_ROW(__sync_lock_release),
472    BUILTIN_ROW(__sync_swap)
473  };
474#undef BUILTIN_ROW
475
476  // Determine the index of the size.
477  unsigned SizeIndex;
478  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
479  case 1: SizeIndex = 0; break;
480  case 2: SizeIndex = 1; break;
481  case 4: SizeIndex = 2; break;
482  case 8: SizeIndex = 3; break;
483  case 16: SizeIndex = 4; break;
484  default:
485    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
486      << FirstArg->getType() << FirstArg->getSourceRange();
487    return ExprError();
488  }
489
490  // Each of these builtins has one pointer argument, followed by some number of
491  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
492  // that we ignore.  Find out which row of BuiltinIndices to read from as well
493  // as the number of fixed args.
494  unsigned BuiltinID = FDecl->getBuiltinID();
495  unsigned BuiltinIndex, NumFixed = 1;
496  switch (BuiltinID) {
497  default: assert(0 && "Unknown overloaded atomic builtin!");
498  case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break;
499  case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break;
500  case Builtin::BI__sync_fetch_and_or:  BuiltinIndex = 2; break;
501  case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break;
502  case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break;
503
504  case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break;
505  case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break;
506  case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break;
507  case Builtin::BI__sync_or_and_fetch:  BuiltinIndex = 8; break;
508  case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break;
509
510  case Builtin::BI__sync_val_compare_and_swap:
511    BuiltinIndex = 10;
512    NumFixed = 2;
513    break;
514  case Builtin::BI__sync_bool_compare_and_swap:
515    BuiltinIndex = 11;
516    NumFixed = 2;
517    ResultType = Context.BoolTy;
518    break;
519  case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break;
520  case Builtin::BI__sync_lock_release:
521    BuiltinIndex = 13;
522    NumFixed = 0;
523    ResultType = Context.VoidTy;
524    break;
525  case Builtin::BI__sync_swap: BuiltinIndex = 14; break;
526  }
527
528  // Now that we know how many fixed arguments we expect, first check that we
529  // have at least that many.
530  if (TheCall->getNumArgs() < 1+NumFixed) {
531    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
532      << 0 << 1+NumFixed << TheCall->getNumArgs()
533      << TheCall->getCallee()->getSourceRange();
534    return ExprError();
535  }
536
537  // Get the decl for the concrete builtin from this, we can tell what the
538  // concrete integer type we should convert to is.
539  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
540  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
541  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
542  FunctionDecl *NewBuiltinDecl =
543    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
544                                           TUScope, false, DRE->getLocStart()));
545
546  // The first argument --- the pointer --- has a fixed type; we
547  // deduce the types of the rest of the arguments accordingly.  Walk
548  // the remaining arguments, converting them to the deduced value type.
549  for (unsigned i = 0; i != NumFixed; ++i) {
550    ExprResult Arg = TheCall->getArg(i+1);
551
552    // If the argument is an implicit cast, then there was a promotion due to
553    // "...", just remove it now.
554    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg.get())) {
555      Arg = ICE->getSubExpr();
556      ICE->setSubExpr(0);
557      TheCall->setArg(i+1, Arg.get());
558    }
559
560    // GCC does an implicit conversion to the pointer or integer ValType.  This
561    // can fail in some cases (1i -> int**), check for this error case now.
562    CastKind Kind = CK_Invalid;
563    ExprValueKind VK = VK_RValue;
564    CXXCastPath BasePath;
565    Arg = CheckCastTypes(Arg.get()->getLocStart(), Arg.get()->getSourceRange(),
566                         ValType, Arg.take(), Kind, VK, BasePath);
567    if (Arg.isInvalid())
568      return ExprError();
569
570    // Okay, we have something that *can* be converted to the right type.  Check
571    // to see if there is a potentially weird extension going on here.  This can
572    // happen when you do an atomic operation on something like an char* and
573    // pass in 42.  The 42 gets converted to char.  This is even more strange
574    // for things like 45.123 -> char, etc.
575    // FIXME: Do this check.
576    Arg = ImpCastExprToType(Arg.take(), ValType, Kind, VK, &BasePath);
577    TheCall->setArg(i+1, Arg.get());
578  }
579
580  // Switch the DeclRefExpr to refer to the new decl.
581  DRE->setDecl(NewBuiltinDecl);
582  DRE->setType(NewBuiltinDecl->getType());
583
584  // Set the callee in the CallExpr.
585  // FIXME: This leaks the original parens and implicit casts.
586  ExprResult PromotedCall = UsualUnaryConversions(DRE);
587  if (PromotedCall.isInvalid())
588    return ExprError();
589  TheCall->setCallee(PromotedCall.take());
590
591  // Change the result type of the call to match the original value type. This
592  // is arbitrary, but the codegen for these builtins ins design to handle it
593  // gracefully.
594  TheCall->setType(ResultType);
595
596  return move(TheCallResult);
597}
598
599
600/// CheckObjCString - Checks that the argument to the builtin
601/// CFString constructor is correct
602/// Note: It might also make sense to do the UTF-16 conversion here (would
603/// simplify the backend).
604bool Sema::CheckObjCString(Expr *Arg) {
605  Arg = Arg->IgnoreParenCasts();
606  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
607
608  if (!Literal || Literal->isWide()) {
609    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
610      << Arg->getSourceRange();
611    return true;
612  }
613
614  if (Literal->containsNonAsciiOrNull()) {
615    llvm::StringRef String = Literal->getString();
616    unsigned NumBytes = String.size();
617    llvm::SmallVector<UTF16, 128> ToBuf(NumBytes);
618    const UTF8 *FromPtr = (UTF8 *)String.data();
619    UTF16 *ToPtr = &ToBuf[0];
620
621    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
622                                                 &ToPtr, ToPtr + NumBytes,
623                                                 strictConversion);
624    // Check for conversion failure.
625    if (Result != conversionOK)
626      Diag(Arg->getLocStart(),
627           diag::warn_cfstring_truncated) << Arg->getSourceRange();
628  }
629  return false;
630}
631
632/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
633/// Emit an error and return true on failure, return false on success.
634bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
635  Expr *Fn = TheCall->getCallee();
636  if (TheCall->getNumArgs() > 2) {
637    Diag(TheCall->getArg(2)->getLocStart(),
638         diag::err_typecheck_call_too_many_args)
639      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
640      << Fn->getSourceRange()
641      << SourceRange(TheCall->getArg(2)->getLocStart(),
642                     (*(TheCall->arg_end()-1))->getLocEnd());
643    return true;
644  }
645
646  if (TheCall->getNumArgs() < 2) {
647    return Diag(TheCall->getLocEnd(),
648      diag::err_typecheck_call_too_few_args_at_least)
649      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
650  }
651
652  // Determine whether the current function is variadic or not.
653  BlockScopeInfo *CurBlock = getCurBlock();
654  bool isVariadic;
655  if (CurBlock)
656    isVariadic = CurBlock->TheDecl->isVariadic();
657  else if (FunctionDecl *FD = getCurFunctionDecl())
658    isVariadic = FD->isVariadic();
659  else
660    isVariadic = getCurMethodDecl()->isVariadic();
661
662  if (!isVariadic) {
663    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
664    return true;
665  }
666
667  // Verify that the second argument to the builtin is the last argument of the
668  // current function or method.
669  bool SecondArgIsLastNamedArgument = false;
670  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
671
672  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
673    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
674      // FIXME: This isn't correct for methods (results in bogus warning).
675      // Get the last formal in the current function.
676      const ParmVarDecl *LastArg;
677      if (CurBlock)
678        LastArg = *(CurBlock->TheDecl->param_end()-1);
679      else if (FunctionDecl *FD = getCurFunctionDecl())
680        LastArg = *(FD->param_end()-1);
681      else
682        LastArg = *(getCurMethodDecl()->param_end()-1);
683      SecondArgIsLastNamedArgument = PV == LastArg;
684    }
685  }
686
687  if (!SecondArgIsLastNamedArgument)
688    Diag(TheCall->getArg(1)->getLocStart(),
689         diag::warn_second_parameter_of_va_start_not_last_named_argument);
690  return false;
691}
692
693/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
694/// friends.  This is declared to take (...), so we have to check everything.
695bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
696  if (TheCall->getNumArgs() < 2)
697    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
698      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
699  if (TheCall->getNumArgs() > 2)
700    return Diag(TheCall->getArg(2)->getLocStart(),
701                diag::err_typecheck_call_too_many_args)
702      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
703      << SourceRange(TheCall->getArg(2)->getLocStart(),
704                     (*(TheCall->arg_end()-1))->getLocEnd());
705
706  ExprResult OrigArg0 = TheCall->getArg(0);
707  ExprResult OrigArg1 = TheCall->getArg(1);
708
709  // Do standard promotions between the two arguments, returning their common
710  // type.
711  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
712  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
713    return true;
714
715  // Make sure any conversions are pushed back into the call; this is
716  // type safe since unordered compare builtins are declared as "_Bool
717  // foo(...)".
718  TheCall->setArg(0, OrigArg0.get());
719  TheCall->setArg(1, OrigArg1.get());
720
721  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
722    return false;
723
724  // If the common type isn't a real floating type, then the arguments were
725  // invalid for this operation.
726  if (!Res->isRealFloatingType())
727    return Diag(OrigArg0.get()->getLocStart(),
728                diag::err_typecheck_call_invalid_ordered_compare)
729      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
730      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
731
732  return false;
733}
734
735/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
736/// __builtin_isnan and friends.  This is declared to take (...), so we have
737/// to check everything. We expect the last argument to be a floating point
738/// value.
739bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
740  if (TheCall->getNumArgs() < NumArgs)
741    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
742      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
743  if (TheCall->getNumArgs() > NumArgs)
744    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
745                diag::err_typecheck_call_too_many_args)
746      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
747      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
748                     (*(TheCall->arg_end()-1))->getLocEnd());
749
750  Expr *OrigArg = TheCall->getArg(NumArgs-1);
751
752  if (OrigArg->isTypeDependent())
753    return false;
754
755  // This operation requires a non-_Complex floating-point number.
756  if (!OrigArg->getType()->isRealFloatingType())
757    return Diag(OrigArg->getLocStart(),
758                diag::err_typecheck_call_invalid_unary_fp)
759      << OrigArg->getType() << OrigArg->getSourceRange();
760
761  // If this is an implicit conversion from float -> double, remove it.
762  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
763    Expr *CastArg = Cast->getSubExpr();
764    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
765      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
766             "promotion from float to double is the only expected cast here");
767      Cast->setSubExpr(0);
768      TheCall->setArg(NumArgs-1, CastArg);
769      OrigArg = CastArg;
770    }
771  }
772
773  return false;
774}
775
776/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
777// This is declared to take (...), so we have to check everything.
778ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
779  if (TheCall->getNumArgs() < 2)
780    return ExprError(Diag(TheCall->getLocEnd(),
781                          diag::err_typecheck_call_too_few_args_at_least)
782      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
783      << TheCall->getSourceRange());
784
785  // Determine which of the following types of shufflevector we're checking:
786  // 1) unary, vector mask: (lhs, mask)
787  // 2) binary, vector mask: (lhs, rhs, mask)
788  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
789  QualType resType = TheCall->getArg(0)->getType();
790  unsigned numElements = 0;
791
792  if (!TheCall->getArg(0)->isTypeDependent() &&
793      !TheCall->getArg(1)->isTypeDependent()) {
794    QualType LHSType = TheCall->getArg(0)->getType();
795    QualType RHSType = TheCall->getArg(1)->getType();
796
797    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
798      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
799        << SourceRange(TheCall->getArg(0)->getLocStart(),
800                       TheCall->getArg(1)->getLocEnd());
801      return ExprError();
802    }
803
804    numElements = LHSType->getAs<VectorType>()->getNumElements();
805    unsigned numResElements = TheCall->getNumArgs() - 2;
806
807    // Check to see if we have a call with 2 vector arguments, the unary shuffle
808    // with mask.  If so, verify that RHS is an integer vector type with the
809    // same number of elts as lhs.
810    if (TheCall->getNumArgs() == 2) {
811      if (!RHSType->hasIntegerRepresentation() ||
812          RHSType->getAs<VectorType>()->getNumElements() != numElements)
813        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
814          << SourceRange(TheCall->getArg(1)->getLocStart(),
815                         TheCall->getArg(1)->getLocEnd());
816      numResElements = numElements;
817    }
818    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
819      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
820        << SourceRange(TheCall->getArg(0)->getLocStart(),
821                       TheCall->getArg(1)->getLocEnd());
822      return ExprError();
823    } else if (numElements != numResElements) {
824      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
825      resType = Context.getVectorType(eltType, numResElements,
826                                      VectorType::GenericVector);
827    }
828  }
829
830  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
831    if (TheCall->getArg(i)->isTypeDependent() ||
832        TheCall->getArg(i)->isValueDependent())
833      continue;
834
835    llvm::APSInt Result(32);
836    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
837      return ExprError(Diag(TheCall->getLocStart(),
838                  diag::err_shufflevector_nonconstant_argument)
839                << TheCall->getArg(i)->getSourceRange());
840
841    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
842      return ExprError(Diag(TheCall->getLocStart(),
843                  diag::err_shufflevector_argument_too_large)
844               << TheCall->getArg(i)->getSourceRange());
845  }
846
847  llvm::SmallVector<Expr*, 32> exprs;
848
849  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
850    exprs.push_back(TheCall->getArg(i));
851    TheCall->setArg(i, 0);
852  }
853
854  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
855                                            exprs.size(), resType,
856                                            TheCall->getCallee()->getLocStart(),
857                                            TheCall->getRParenLoc()));
858}
859
860/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
861// This is declared to take (const void*, ...) and can take two
862// optional constant int args.
863bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
864  unsigned NumArgs = TheCall->getNumArgs();
865
866  if (NumArgs > 3)
867    return Diag(TheCall->getLocEnd(),
868             diag::err_typecheck_call_too_many_args_at_most)
869             << 0 /*function call*/ << 3 << NumArgs
870             << TheCall->getSourceRange();
871
872  // Argument 0 is checked for us and the remaining arguments must be
873  // constant integers.
874  for (unsigned i = 1; i != NumArgs; ++i) {
875    Expr *Arg = TheCall->getArg(i);
876
877    llvm::APSInt Result;
878    if (SemaBuiltinConstantArg(TheCall, i, Result))
879      return true;
880
881    // FIXME: gcc issues a warning and rewrites these to 0. These
882    // seems especially odd for the third argument since the default
883    // is 3.
884    if (i == 1) {
885      if (Result.getLimitedValue() > 1)
886        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
887             << "0" << "1" << Arg->getSourceRange();
888    } else {
889      if (Result.getLimitedValue() > 3)
890        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
891            << "0" << "3" << Arg->getSourceRange();
892    }
893  }
894
895  return false;
896}
897
898/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
899/// TheCall is a constant expression.
900bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
901                                  llvm::APSInt &Result) {
902  Expr *Arg = TheCall->getArg(ArgNum);
903  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
904  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
905
906  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
907
908  if (!Arg->isIntegerConstantExpr(Result, Context))
909    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
910                << FDecl->getDeclName() <<  Arg->getSourceRange();
911
912  return false;
913}
914
915/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
916/// int type). This simply type checks that type is one of the defined
917/// constants (0-3).
918// For compatibility check 0-3, llvm only handles 0 and 2.
919bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
920  llvm::APSInt Result;
921
922  // Check constant-ness first.
923  if (SemaBuiltinConstantArg(TheCall, 1, Result))
924    return true;
925
926  Expr *Arg = TheCall->getArg(1);
927  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
928    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
929             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
930  }
931
932  return false;
933}
934
935/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
936/// This checks that val is a constant 1.
937bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
938  Expr *Arg = TheCall->getArg(1);
939  llvm::APSInt Result;
940
941  // TODO: This is less than ideal. Overload this to take a value.
942  if (SemaBuiltinConstantArg(TheCall, 1, Result))
943    return true;
944
945  if (Result != 1)
946    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
947             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
948
949  return false;
950}
951
952// Handle i > 1 ? "x" : "y", recursively.
953bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall,
954                                  bool HasVAListArg,
955                                  unsigned format_idx, unsigned firstDataArg,
956                                  bool isPrintf) {
957 tryAgain:
958  if (E->isTypeDependent() || E->isValueDependent())
959    return false;
960
961  E = E->IgnoreParens();
962
963  switch (E->getStmtClass()) {
964  case Stmt::BinaryConditionalOperatorClass:
965  case Stmt::ConditionalOperatorClass: {
966    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
967    return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg,
968                                  format_idx, firstDataArg, isPrintf)
969        && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg,
970                                  format_idx, firstDataArg, isPrintf);
971  }
972
973  case Stmt::IntegerLiteralClass:
974    // Technically -Wformat-nonliteral does not warn about this case.
975    // The behavior of printf and friends in this case is implementation
976    // dependent.  Ideally if the format string cannot be null then
977    // it should have a 'nonnull' attribute in the function prototype.
978    return true;
979
980  case Stmt::ImplicitCastExprClass: {
981    E = cast<ImplicitCastExpr>(E)->getSubExpr();
982    goto tryAgain;
983  }
984
985  case Stmt::OpaqueValueExprClass:
986    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
987      E = src;
988      goto tryAgain;
989    }
990    return false;
991
992  case Stmt::PredefinedExprClass:
993    // While __func__, etc., are technically not string literals, they
994    // cannot contain format specifiers and thus are not a security
995    // liability.
996    return true;
997
998  case Stmt::DeclRefExprClass: {
999    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1000
1001    // As an exception, do not flag errors for variables binding to
1002    // const string literals.
1003    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1004      bool isConstant = false;
1005      QualType T = DR->getType();
1006
1007      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1008        isConstant = AT->getElementType().isConstant(Context);
1009      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1010        isConstant = T.isConstant(Context) &&
1011                     PT->getPointeeType().isConstant(Context);
1012      }
1013
1014      if (isConstant) {
1015        if (const Expr *Init = VD->getAnyInitializer())
1016          return SemaCheckStringLiteral(Init, TheCall,
1017                                        HasVAListArg, format_idx, firstDataArg,
1018                                        isPrintf);
1019      }
1020
1021      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1022      // special check to see if the format string is a function parameter
1023      // of the function calling the printf function.  If the function
1024      // has an attribute indicating it is a printf-like function, then we
1025      // should suppress warnings concerning non-literals being used in a call
1026      // to a vprintf function.  For example:
1027      //
1028      // void
1029      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1030      //      va_list ap;
1031      //      va_start(ap, fmt);
1032      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1033      //      ...
1034      //
1035      //
1036      //  FIXME: We don't have full attribute support yet, so just check to see
1037      //    if the argument is a DeclRefExpr that references a parameter.  We'll
1038      //    add proper support for checking the attribute later.
1039      if (HasVAListArg)
1040        if (isa<ParmVarDecl>(VD))
1041          return true;
1042    }
1043
1044    return false;
1045  }
1046
1047  case Stmt::CallExprClass: {
1048    const CallExpr *CE = cast<CallExpr>(E);
1049    if (const ImplicitCastExpr *ICE
1050          = dyn_cast<ImplicitCastExpr>(CE->getCallee())) {
1051      if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) {
1052        if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
1053          if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) {
1054            unsigned ArgIndex = FA->getFormatIdx();
1055            const Expr *Arg = CE->getArg(ArgIndex - 1);
1056
1057            return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg,
1058                                          format_idx, firstDataArg, isPrintf);
1059          }
1060        }
1061      }
1062    }
1063
1064    return false;
1065  }
1066  case Stmt::ObjCStringLiteralClass:
1067  case Stmt::StringLiteralClass: {
1068    const StringLiteral *StrE = NULL;
1069
1070    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1071      StrE = ObjCFExpr->getString();
1072    else
1073      StrE = cast<StringLiteral>(E);
1074
1075    if (StrE) {
1076      CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx,
1077                        firstDataArg, isPrintf);
1078      return true;
1079    }
1080
1081    return false;
1082  }
1083
1084  default:
1085    return false;
1086  }
1087}
1088
1089void
1090Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1091                            const Expr * const *ExprArgs,
1092                            SourceLocation CallSiteLoc) {
1093  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1094                                  e = NonNull->args_end();
1095       i != e; ++i) {
1096    const Expr *ArgExpr = ExprArgs[*i];
1097    if (ArgExpr->isNullPointerConstant(Context,
1098                                       Expr::NPC_ValueDependentIsNotNull))
1099      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1100  }
1101}
1102
1103/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
1104/// functions) for correct use of format strings.
1105void
1106Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg,
1107                                unsigned format_idx, unsigned firstDataArg,
1108                                bool isPrintf) {
1109
1110  const Expr *Fn = TheCall->getCallee();
1111
1112  // The way the format attribute works in GCC, the implicit this argument
1113  // of member functions is counted. However, it doesn't appear in our own
1114  // lists, so decrement format_idx in that case.
1115  if (isa<CXXMemberCallExpr>(TheCall)) {
1116    const CXXMethodDecl *method_decl =
1117      dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl());
1118    if (method_decl && method_decl->isInstance()) {
1119      // Catch a format attribute mistakenly referring to the object argument.
1120      if (format_idx == 0)
1121        return;
1122      --format_idx;
1123      if(firstDataArg != 0)
1124        --firstDataArg;
1125    }
1126  }
1127
1128  // CHECK: printf/scanf-like function is called with no format string.
1129  if (format_idx >= TheCall->getNumArgs()) {
1130    Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string)
1131      << Fn->getSourceRange();
1132    return;
1133  }
1134
1135  const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts();
1136
1137  // CHECK: format string is not a string literal.
1138  //
1139  // Dynamically generated format strings are difficult to
1140  // automatically vet at compile time.  Requiring that format strings
1141  // are string literals: (1) permits the checking of format strings by
1142  // the compiler and thereby (2) can practically remove the source of
1143  // many format string exploits.
1144
1145  // Format string can be either ObjC string (e.g. @"%d") or
1146  // C string (e.g. "%d")
1147  // ObjC string uses the same format specifiers as C string, so we can use
1148  // the same format string checking logic for both ObjC and C strings.
1149  if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx,
1150                             firstDataArg, isPrintf))
1151    return;  // Literal format string found, check done!
1152
1153  // If there are no arguments specified, warn with -Wformat-security, otherwise
1154  // warn only with -Wformat-nonliteral.
1155  if (TheCall->getNumArgs() == format_idx+1)
1156    Diag(TheCall->getArg(format_idx)->getLocStart(),
1157         diag::warn_format_nonliteral_noargs)
1158      << OrigFormatExpr->getSourceRange();
1159  else
1160    Diag(TheCall->getArg(format_idx)->getLocStart(),
1161         diag::warn_format_nonliteral)
1162           << OrigFormatExpr->getSourceRange();
1163}
1164
1165namespace {
1166class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1167protected:
1168  Sema &S;
1169  const StringLiteral *FExpr;
1170  const Expr *OrigFormatExpr;
1171  const unsigned FirstDataArg;
1172  const unsigned NumDataArgs;
1173  const bool IsObjCLiteral;
1174  const char *Beg; // Start of format string.
1175  const bool HasVAListArg;
1176  const CallExpr *TheCall;
1177  unsigned FormatIdx;
1178  llvm::BitVector CoveredArgs;
1179  bool usesPositionalArgs;
1180  bool atFirstArg;
1181public:
1182  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1183                     const Expr *origFormatExpr, unsigned firstDataArg,
1184                     unsigned numDataArgs, bool isObjCLiteral,
1185                     const char *beg, bool hasVAListArg,
1186                     const CallExpr *theCall, unsigned formatIdx)
1187    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1188      FirstDataArg(firstDataArg),
1189      NumDataArgs(numDataArgs),
1190      IsObjCLiteral(isObjCLiteral), Beg(beg),
1191      HasVAListArg(hasVAListArg),
1192      TheCall(theCall), FormatIdx(formatIdx),
1193      usesPositionalArgs(false), atFirstArg(true) {
1194        CoveredArgs.resize(numDataArgs);
1195        CoveredArgs.reset();
1196      }
1197
1198  void DoneProcessing();
1199
1200  void HandleIncompleteSpecifier(const char *startSpecifier,
1201                                 unsigned specifierLen);
1202
1203  virtual void HandleInvalidPosition(const char *startSpecifier,
1204                                     unsigned specifierLen,
1205                                     analyze_format_string::PositionContext p);
1206
1207  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1208
1209  void HandleNullChar(const char *nullCharacter);
1210
1211protected:
1212  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1213                                        const char *startSpec,
1214                                        unsigned specifierLen,
1215                                        const char *csStart, unsigned csLen);
1216
1217  SourceRange getFormatStringRange();
1218  CharSourceRange getSpecifierRange(const char *startSpecifier,
1219                                    unsigned specifierLen);
1220  SourceLocation getLocationOfByte(const char *x);
1221
1222  const Expr *getDataArg(unsigned i) const;
1223
1224  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1225                    const analyze_format_string::ConversionSpecifier &CS,
1226                    const char *startSpecifier, unsigned specifierLen,
1227                    unsigned argIndex);
1228};
1229}
1230
1231SourceRange CheckFormatHandler::getFormatStringRange() {
1232  return OrigFormatExpr->getSourceRange();
1233}
1234
1235CharSourceRange CheckFormatHandler::
1236getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
1237  SourceLocation Start = getLocationOfByte(startSpecifier);
1238  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
1239
1240  // Advance the end SourceLocation by one due to half-open ranges.
1241  End = End.getFileLocWithOffset(1);
1242
1243  return CharSourceRange::getCharRange(Start, End);
1244}
1245
1246SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
1247  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
1248}
1249
1250void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
1251                                                   unsigned specifierLen){
1252  SourceLocation Loc = getLocationOfByte(startSpecifier);
1253  S.Diag(Loc, diag::warn_printf_incomplete_specifier)
1254    << getSpecifierRange(startSpecifier, specifierLen);
1255}
1256
1257void
1258CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
1259                                     analyze_format_string::PositionContext p) {
1260  SourceLocation Loc = getLocationOfByte(startPos);
1261  S.Diag(Loc, diag::warn_format_invalid_positional_specifier)
1262    << (unsigned) p << getSpecifierRange(startPos, posLen);
1263}
1264
1265void CheckFormatHandler::HandleZeroPosition(const char *startPos,
1266                                            unsigned posLen) {
1267  SourceLocation Loc = getLocationOfByte(startPos);
1268  S.Diag(Loc, diag::warn_format_zero_positional_specifier)
1269    << getSpecifierRange(startPos, posLen);
1270}
1271
1272void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
1273  if (!IsObjCLiteral) {
1274    // The presence of a null character is likely an error.
1275    S.Diag(getLocationOfByte(nullCharacter),
1276           diag::warn_printf_format_string_contains_null_char)
1277      << getFormatStringRange();
1278  }
1279}
1280
1281const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
1282  return TheCall->getArg(FirstDataArg + i);
1283}
1284
1285void CheckFormatHandler::DoneProcessing() {
1286    // Does the number of data arguments exceed the number of
1287    // format conversions in the format string?
1288  if (!HasVAListArg) {
1289      // Find any arguments that weren't covered.
1290    CoveredArgs.flip();
1291    signed notCoveredArg = CoveredArgs.find_first();
1292    if (notCoveredArg >= 0) {
1293      assert((unsigned)notCoveredArg < NumDataArgs);
1294      S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(),
1295             diag::warn_printf_data_arg_not_used)
1296      << getFormatStringRange();
1297    }
1298  }
1299}
1300
1301bool
1302CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
1303                                                     SourceLocation Loc,
1304                                                     const char *startSpec,
1305                                                     unsigned specifierLen,
1306                                                     const char *csStart,
1307                                                     unsigned csLen) {
1308
1309  bool keepGoing = true;
1310  if (argIndex < NumDataArgs) {
1311    // Consider the argument coverered, even though the specifier doesn't
1312    // make sense.
1313    CoveredArgs.set(argIndex);
1314  }
1315  else {
1316    // If argIndex exceeds the number of data arguments we
1317    // don't issue a warning because that is just a cascade of warnings (and
1318    // they may have intended '%%' anyway). We don't want to continue processing
1319    // the format string after this point, however, as we will like just get
1320    // gibberish when trying to match arguments.
1321    keepGoing = false;
1322  }
1323
1324  S.Diag(Loc, diag::warn_format_invalid_conversion)
1325    << llvm::StringRef(csStart, csLen)
1326    << getSpecifierRange(startSpec, specifierLen);
1327
1328  return keepGoing;
1329}
1330
1331bool
1332CheckFormatHandler::CheckNumArgs(
1333  const analyze_format_string::FormatSpecifier &FS,
1334  const analyze_format_string::ConversionSpecifier &CS,
1335  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
1336
1337  if (argIndex >= NumDataArgs) {
1338    if (FS.usesPositionalArg())  {
1339      S.Diag(getLocationOfByte(CS.getStart()),
1340             diag::warn_printf_positional_arg_exceeds_data_args)
1341      << (argIndex+1) << NumDataArgs
1342      << getSpecifierRange(startSpecifier, specifierLen);
1343    }
1344    else {
1345      S.Diag(getLocationOfByte(CS.getStart()),
1346             diag::warn_printf_insufficient_data_args)
1347      << getSpecifierRange(startSpecifier, specifierLen);
1348    }
1349
1350    return false;
1351  }
1352  return true;
1353}
1354
1355//===--- CHECK: Printf format string checking ------------------------------===//
1356
1357namespace {
1358class CheckPrintfHandler : public CheckFormatHandler {
1359public:
1360  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
1361                     const Expr *origFormatExpr, unsigned firstDataArg,
1362                     unsigned numDataArgs, bool isObjCLiteral,
1363                     const char *beg, bool hasVAListArg,
1364                     const CallExpr *theCall, unsigned formatIdx)
1365  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
1366                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
1367                       theCall, formatIdx) {}
1368
1369
1370  bool HandleInvalidPrintfConversionSpecifier(
1371                                      const analyze_printf::PrintfSpecifier &FS,
1372                                      const char *startSpecifier,
1373                                      unsigned specifierLen);
1374
1375  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
1376                             const char *startSpecifier,
1377                             unsigned specifierLen);
1378
1379  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
1380                    const char *startSpecifier, unsigned specifierLen);
1381  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
1382                           const analyze_printf::OptionalAmount &Amt,
1383                           unsigned type,
1384                           const char *startSpecifier, unsigned specifierLen);
1385  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
1386                  const analyze_printf::OptionalFlag &flag,
1387                  const char *startSpecifier, unsigned specifierLen);
1388  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
1389                         const analyze_printf::OptionalFlag &ignoredFlag,
1390                         const analyze_printf::OptionalFlag &flag,
1391                         const char *startSpecifier, unsigned specifierLen);
1392};
1393}
1394
1395bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
1396                                      const analyze_printf::PrintfSpecifier &FS,
1397                                      const char *startSpecifier,
1398                                      unsigned specifierLen) {
1399  const analyze_printf::PrintfConversionSpecifier &CS =
1400    FS.getConversionSpecifier();
1401
1402  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
1403                                          getLocationOfByte(CS.getStart()),
1404                                          startSpecifier, specifierLen,
1405                                          CS.getStart(), CS.getLength());
1406}
1407
1408bool CheckPrintfHandler::HandleAmount(
1409                               const analyze_format_string::OptionalAmount &Amt,
1410                               unsigned k, const char *startSpecifier,
1411                               unsigned specifierLen) {
1412
1413  if (Amt.hasDataArgument()) {
1414    if (!HasVAListArg) {
1415      unsigned argIndex = Amt.getArgIndex();
1416      if (argIndex >= NumDataArgs) {
1417        S.Diag(getLocationOfByte(Amt.getStart()),
1418               diag::warn_printf_asterisk_missing_arg)
1419          << k << getSpecifierRange(startSpecifier, specifierLen);
1420        // Don't do any more checking.  We will just emit
1421        // spurious errors.
1422        return false;
1423      }
1424
1425      // Type check the data argument.  It should be an 'int'.
1426      // Although not in conformance with C99, we also allow the argument to be
1427      // an 'unsigned int' as that is a reasonably safe case.  GCC also
1428      // doesn't emit a warning for that case.
1429      CoveredArgs.set(argIndex);
1430      const Expr *Arg = getDataArg(argIndex);
1431      QualType T = Arg->getType();
1432
1433      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
1434      assert(ATR.isValid());
1435
1436      if (!ATR.matchesType(S.Context, T)) {
1437        S.Diag(getLocationOfByte(Amt.getStart()),
1438               diag::warn_printf_asterisk_wrong_type)
1439          << k
1440          << ATR.getRepresentativeType(S.Context) << T
1441          << getSpecifierRange(startSpecifier, specifierLen)
1442          << Arg->getSourceRange();
1443        // Don't do any more checking.  We will just emit
1444        // spurious errors.
1445        return false;
1446      }
1447    }
1448  }
1449  return true;
1450}
1451
1452void CheckPrintfHandler::HandleInvalidAmount(
1453                                      const analyze_printf::PrintfSpecifier &FS,
1454                                      const analyze_printf::OptionalAmount &Amt,
1455                                      unsigned type,
1456                                      const char *startSpecifier,
1457                                      unsigned specifierLen) {
1458  const analyze_printf::PrintfConversionSpecifier &CS =
1459    FS.getConversionSpecifier();
1460  switch (Amt.getHowSpecified()) {
1461  case analyze_printf::OptionalAmount::Constant:
1462    S.Diag(getLocationOfByte(Amt.getStart()),
1463        diag::warn_printf_nonsensical_optional_amount)
1464      << type
1465      << CS.toString()
1466      << getSpecifierRange(startSpecifier, specifierLen)
1467      << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
1468          Amt.getConstantLength()));
1469    break;
1470
1471  default:
1472    S.Diag(getLocationOfByte(Amt.getStart()),
1473        diag::warn_printf_nonsensical_optional_amount)
1474      << type
1475      << CS.toString()
1476      << getSpecifierRange(startSpecifier, specifierLen);
1477    break;
1478  }
1479}
1480
1481void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
1482                                    const analyze_printf::OptionalFlag &flag,
1483                                    const char *startSpecifier,
1484                                    unsigned specifierLen) {
1485  // Warn about pointless flag with a fixit removal.
1486  const analyze_printf::PrintfConversionSpecifier &CS =
1487    FS.getConversionSpecifier();
1488  S.Diag(getLocationOfByte(flag.getPosition()),
1489      diag::warn_printf_nonsensical_flag)
1490    << flag.toString() << CS.toString()
1491    << getSpecifierRange(startSpecifier, specifierLen)
1492    << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1));
1493}
1494
1495void CheckPrintfHandler::HandleIgnoredFlag(
1496                                const analyze_printf::PrintfSpecifier &FS,
1497                                const analyze_printf::OptionalFlag &ignoredFlag,
1498                                const analyze_printf::OptionalFlag &flag,
1499                                const char *startSpecifier,
1500                                unsigned specifierLen) {
1501  // Warn about ignored flag with a fixit removal.
1502  S.Diag(getLocationOfByte(ignoredFlag.getPosition()),
1503      diag::warn_printf_ignored_flag)
1504    << ignoredFlag.toString() << flag.toString()
1505    << getSpecifierRange(startSpecifier, specifierLen)
1506    << FixItHint::CreateRemoval(getSpecifierRange(
1507        ignoredFlag.getPosition(), 1));
1508}
1509
1510bool
1511CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
1512                                            &FS,
1513                                          const char *startSpecifier,
1514                                          unsigned specifierLen) {
1515
1516  using namespace analyze_format_string;
1517  using namespace analyze_printf;
1518  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
1519
1520  if (FS.consumesDataArgument()) {
1521    if (atFirstArg) {
1522        atFirstArg = false;
1523        usesPositionalArgs = FS.usesPositionalArg();
1524    }
1525    else if (usesPositionalArgs != FS.usesPositionalArg()) {
1526      // Cannot mix-and-match positional and non-positional arguments.
1527      S.Diag(getLocationOfByte(CS.getStart()),
1528             diag::warn_format_mix_positional_nonpositional_args)
1529        << getSpecifierRange(startSpecifier, specifierLen);
1530      return false;
1531    }
1532  }
1533
1534  // First check if the field width, precision, and conversion specifier
1535  // have matching data arguments.
1536  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
1537                    startSpecifier, specifierLen)) {
1538    return false;
1539  }
1540
1541  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
1542                    startSpecifier, specifierLen)) {
1543    return false;
1544  }
1545
1546  if (!CS.consumesDataArgument()) {
1547    // FIXME: Technically specifying a precision or field width here
1548    // makes no sense.  Worth issuing a warning at some point.
1549    return true;
1550  }
1551
1552  // Consume the argument.
1553  unsigned argIndex = FS.getArgIndex();
1554  if (argIndex < NumDataArgs) {
1555    // The check to see if the argIndex is valid will come later.
1556    // We set the bit here because we may exit early from this
1557    // function if we encounter some other error.
1558    CoveredArgs.set(argIndex);
1559  }
1560
1561  // Check for using an Objective-C specific conversion specifier
1562  // in a non-ObjC literal.
1563  if (!IsObjCLiteral && CS.isObjCArg()) {
1564    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
1565                                                  specifierLen);
1566  }
1567
1568  // Check for invalid use of field width
1569  if (!FS.hasValidFieldWidth()) {
1570    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
1571        startSpecifier, specifierLen);
1572  }
1573
1574  // Check for invalid use of precision
1575  if (!FS.hasValidPrecision()) {
1576    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
1577        startSpecifier, specifierLen);
1578  }
1579
1580  // Check each flag does not conflict with any other component.
1581  if (!FS.hasValidThousandsGroupingPrefix())
1582    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
1583  if (!FS.hasValidLeadingZeros())
1584    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
1585  if (!FS.hasValidPlusPrefix())
1586    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
1587  if (!FS.hasValidSpacePrefix())
1588    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
1589  if (!FS.hasValidAlternativeForm())
1590    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
1591  if (!FS.hasValidLeftJustified())
1592    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
1593
1594  // Check that flags are not ignored by another flag
1595  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
1596    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
1597        startSpecifier, specifierLen);
1598  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
1599    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
1600            startSpecifier, specifierLen);
1601
1602  // Check the length modifier is valid with the given conversion specifier.
1603  const LengthModifier &LM = FS.getLengthModifier();
1604  if (!FS.hasValidLengthModifier())
1605    S.Diag(getLocationOfByte(LM.getStart()),
1606        diag::warn_format_nonsensical_length)
1607      << LM.toString() << CS.toString()
1608      << getSpecifierRange(startSpecifier, specifierLen)
1609      << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(),
1610          LM.getLength()));
1611
1612  // Are we using '%n'?
1613  if (CS.getKind() == ConversionSpecifier::nArg) {
1614    // Issue a warning about this being a possible security issue.
1615    S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back)
1616      << getSpecifierRange(startSpecifier, specifierLen);
1617    // Continue checking the other format specifiers.
1618    return true;
1619  }
1620
1621  // The remaining checks depend on the data arguments.
1622  if (HasVAListArg)
1623    return true;
1624
1625  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
1626    return false;
1627
1628  // Now type check the data expression that matches the
1629  // format specifier.
1630  const Expr *Ex = getDataArg(argIndex);
1631  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context);
1632  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
1633    // Check if we didn't match because of an implicit cast from a 'char'
1634    // or 'short' to an 'int'.  This is done because printf is a varargs
1635    // function.
1636    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
1637      if (ICE->getType() == S.Context.IntTy) {
1638        // All further checking is done on the subexpression.
1639        Ex = ICE->getSubExpr();
1640        if (ATR.matchesType(S.Context, Ex->getType()))
1641          return true;
1642      }
1643
1644    // We may be able to offer a FixItHint if it is a supported type.
1645    PrintfSpecifier fixedFS = FS;
1646    bool success = fixedFS.fixType(Ex->getType());
1647
1648    if (success) {
1649      // Get the fix string from the fixed format specifier
1650      llvm::SmallString<128> buf;
1651      llvm::raw_svector_ostream os(buf);
1652      fixedFS.toString(os);
1653
1654      // FIXME: getRepresentativeType() perhaps should return a string
1655      // instead of a QualType to better handle when the representative
1656      // type is 'wint_t' (which is defined in the system headers).
1657      S.Diag(getLocationOfByte(CS.getStart()),
1658          diag::warn_printf_conversion_argument_type_mismatch)
1659        << ATR.getRepresentativeType(S.Context) << Ex->getType()
1660        << getSpecifierRange(startSpecifier, specifierLen)
1661        << Ex->getSourceRange()
1662        << FixItHint::CreateReplacement(
1663            getSpecifierRange(startSpecifier, specifierLen),
1664            os.str());
1665    }
1666    else {
1667      S.Diag(getLocationOfByte(CS.getStart()),
1668             diag::warn_printf_conversion_argument_type_mismatch)
1669        << ATR.getRepresentativeType(S.Context) << Ex->getType()
1670        << getSpecifierRange(startSpecifier, specifierLen)
1671        << Ex->getSourceRange();
1672    }
1673  }
1674
1675  return true;
1676}
1677
1678//===--- CHECK: Scanf format string checking ------------------------------===//
1679
1680namespace {
1681class CheckScanfHandler : public CheckFormatHandler {
1682public:
1683  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
1684                    const Expr *origFormatExpr, unsigned firstDataArg,
1685                    unsigned numDataArgs, bool isObjCLiteral,
1686                    const char *beg, bool hasVAListArg,
1687                    const CallExpr *theCall, unsigned formatIdx)
1688  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
1689                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
1690                       theCall, formatIdx) {}
1691
1692  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
1693                            const char *startSpecifier,
1694                            unsigned specifierLen);
1695
1696  bool HandleInvalidScanfConversionSpecifier(
1697          const analyze_scanf::ScanfSpecifier &FS,
1698          const char *startSpecifier,
1699          unsigned specifierLen);
1700
1701  void HandleIncompleteScanList(const char *start, const char *end);
1702};
1703}
1704
1705void CheckScanfHandler::HandleIncompleteScanList(const char *start,
1706                                                 const char *end) {
1707  S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete)
1708    << getSpecifierRange(start, end - start);
1709}
1710
1711bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
1712                                        const analyze_scanf::ScanfSpecifier &FS,
1713                                        const char *startSpecifier,
1714                                        unsigned specifierLen) {
1715
1716  const analyze_scanf::ScanfConversionSpecifier &CS =
1717    FS.getConversionSpecifier();
1718
1719  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
1720                                          getLocationOfByte(CS.getStart()),
1721                                          startSpecifier, specifierLen,
1722                                          CS.getStart(), CS.getLength());
1723}
1724
1725bool CheckScanfHandler::HandleScanfSpecifier(
1726                                       const analyze_scanf::ScanfSpecifier &FS,
1727                                       const char *startSpecifier,
1728                                       unsigned specifierLen) {
1729
1730  using namespace analyze_scanf;
1731  using namespace analyze_format_string;
1732
1733  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
1734
1735  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
1736  // be used to decide if we are using positional arguments consistently.
1737  if (FS.consumesDataArgument()) {
1738    if (atFirstArg) {
1739      atFirstArg = false;
1740      usesPositionalArgs = FS.usesPositionalArg();
1741    }
1742    else if (usesPositionalArgs != FS.usesPositionalArg()) {
1743      // Cannot mix-and-match positional and non-positional arguments.
1744      S.Diag(getLocationOfByte(CS.getStart()),
1745             diag::warn_format_mix_positional_nonpositional_args)
1746        << getSpecifierRange(startSpecifier, specifierLen);
1747      return false;
1748    }
1749  }
1750
1751  // Check if the field with is non-zero.
1752  const OptionalAmount &Amt = FS.getFieldWidth();
1753  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
1754    if (Amt.getConstantAmount() == 0) {
1755      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
1756                                                   Amt.getConstantLength());
1757      S.Diag(getLocationOfByte(Amt.getStart()),
1758             diag::warn_scanf_nonzero_width)
1759        << R << FixItHint::CreateRemoval(R);
1760    }
1761  }
1762
1763  if (!FS.consumesDataArgument()) {
1764    // FIXME: Technically specifying a precision or field width here
1765    // makes no sense.  Worth issuing a warning at some point.
1766    return true;
1767  }
1768
1769  // Consume the argument.
1770  unsigned argIndex = FS.getArgIndex();
1771  if (argIndex < NumDataArgs) {
1772      // The check to see if the argIndex is valid will come later.
1773      // We set the bit here because we may exit early from this
1774      // function if we encounter some other error.
1775    CoveredArgs.set(argIndex);
1776  }
1777
1778  // Check the length modifier is valid with the given conversion specifier.
1779  const LengthModifier &LM = FS.getLengthModifier();
1780  if (!FS.hasValidLengthModifier()) {
1781    S.Diag(getLocationOfByte(LM.getStart()),
1782           diag::warn_format_nonsensical_length)
1783      << LM.toString() << CS.toString()
1784      << getSpecifierRange(startSpecifier, specifierLen)
1785      << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(),
1786                                                    LM.getLength()));
1787  }
1788
1789  // The remaining checks depend on the data arguments.
1790  if (HasVAListArg)
1791    return true;
1792
1793  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
1794    return false;
1795
1796  // FIXME: Check that the argument type matches the format specifier.
1797
1798  return true;
1799}
1800
1801void Sema::CheckFormatString(const StringLiteral *FExpr,
1802                             const Expr *OrigFormatExpr,
1803                             const CallExpr *TheCall, bool HasVAListArg,
1804                             unsigned format_idx, unsigned firstDataArg,
1805                             bool isPrintf) {
1806
1807  // CHECK: is the format string a wide literal?
1808  if (FExpr->isWide()) {
1809    Diag(FExpr->getLocStart(),
1810         diag::warn_format_string_is_wide_literal)
1811    << OrigFormatExpr->getSourceRange();
1812    return;
1813  }
1814
1815  // Str - The format string.  NOTE: this is NOT null-terminated!
1816  llvm::StringRef StrRef = FExpr->getString();
1817  const char *Str = StrRef.data();
1818  unsigned StrLen = StrRef.size();
1819
1820  // CHECK: empty format string?
1821  if (StrLen == 0) {
1822    Diag(FExpr->getLocStart(), diag::warn_empty_format_string)
1823    << OrigFormatExpr->getSourceRange();
1824    return;
1825  }
1826
1827  if (isPrintf) {
1828    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
1829                         TheCall->getNumArgs() - firstDataArg,
1830                         isa<ObjCStringLiteral>(OrigFormatExpr), Str,
1831                         HasVAListArg, TheCall, format_idx);
1832
1833    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen))
1834      H.DoneProcessing();
1835  }
1836  else {
1837    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
1838                        TheCall->getNumArgs() - firstDataArg,
1839                        isa<ObjCStringLiteral>(OrigFormatExpr), Str,
1840                        HasVAListArg, TheCall, format_idx);
1841
1842    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen))
1843      H.DoneProcessing();
1844  }
1845}
1846
1847//===--- CHECK: Standard memory functions ---------------------------------===//
1848
1849/// \brief Determine whether the given type is a dynamic class type (e.g.,
1850/// whether it has a vtable).
1851static bool isDynamicClassType(QualType T) {
1852  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
1853    if (CXXRecordDecl *Definition = Record->getDefinition())
1854      if (Definition->isDynamicClass())
1855        return true;
1856
1857  return false;
1858}
1859
1860/// \brief If E is a sizeof expression, returns its argument expression,
1861/// otherwise returns NULL.
1862static const Expr *getSizeOfExprArg(const Expr* E) {
1863  if (const UnaryExprOrTypeTraitExpr *SizeOf =
1864      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
1865    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
1866      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
1867
1868  return 0;
1869}
1870
1871/// \brief If E is a sizeof expression, returns its argument type.
1872static QualType getSizeOfArgType(const Expr* E) {
1873  if (const UnaryExprOrTypeTraitExpr *SizeOf =
1874      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
1875    if (SizeOf->getKind() == clang::UETT_SizeOf)
1876      return SizeOf->getTypeOfArgument();
1877
1878  return QualType();
1879}
1880
1881/// \brief Check for dangerous or invalid arguments to memset().
1882///
1883/// This issues warnings on known problematic, dangerous or unspecified
1884/// arguments to the standard 'memset', 'memcpy', and 'memmove' function calls.
1885///
1886/// \param Call The call expression to diagnose.
1887void Sema::CheckMemsetcpymoveArguments(const CallExpr *Call,
1888                                       CheckedMemoryFunction CMF,
1889                                       IdentifierInfo *FnName) {
1890  // It is possible to have a non-standard definition of memset.  Validate
1891  // we have enough arguments, and if not, abort further checking.
1892  if (Call->getNumArgs() < 3)
1893    return;
1894
1895  unsigned LastArg = (CMF == CMF_Memset? 1 : 2);
1896  const Expr *LenExpr = Call->getArg(2)->IgnoreParenImpCasts();
1897
1898  // We have special checking when the length is a sizeof expression.
1899  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
1900  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
1901  llvm::FoldingSetNodeID SizeOfArgID;
1902
1903  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
1904    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
1905    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
1906
1907    QualType DestTy = Dest->getType();
1908    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
1909      QualType PointeeTy = DestPtrTy->getPointeeType();
1910
1911      // Never warn about void type pointers. This can be used to suppress
1912      // false positives.
1913      if (PointeeTy->isVoidType())
1914        continue;
1915
1916      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
1917      // actually comparing the expressions for equality. Because computing the
1918      // expression IDs can be expensive, we only do this if the diagnostic is
1919      // enabled.
1920      if (SizeOfArg &&
1921          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
1922                                   SizeOfArg->getExprLoc())) {
1923        // We only compute IDs for expressions if the warning is enabled, and
1924        // cache the sizeof arg's ID.
1925        if (SizeOfArgID == llvm::FoldingSetNodeID())
1926          SizeOfArg->Profile(SizeOfArgID, Context, true);
1927        llvm::FoldingSetNodeID DestID;
1928        Dest->Profile(DestID, Context, true);
1929        if (DestID == SizeOfArgID) {
1930          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
1931          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
1932            if (UnaryOp->getOpcode() == UO_AddrOf)
1933              ActionIdx = 1; // If its an address-of operator, just remove it.
1934          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
1935            ActionIdx = 2; // If the pointee's size is sizeof(char),
1936                           // suggest an explicit length.
1937          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
1938                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
1939                                << FnName << ArgIdx << ActionIdx
1940                                << Dest->getSourceRange()
1941                                << SizeOfArg->getSourceRange());
1942          break;
1943        }
1944      }
1945
1946      // Also check for cases where the sizeof argument is the exact same
1947      // type as the memory argument, and where it points to a user-defined
1948      // record type.
1949      if (SizeOfArgTy != QualType()) {
1950        if (PointeeTy->isRecordType() &&
1951            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
1952          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
1953                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
1954                                << FnName << SizeOfArgTy << ArgIdx
1955                                << PointeeTy << Dest->getSourceRange()
1956                                << LenExpr->getSourceRange());
1957          break;
1958        }
1959      }
1960
1961      unsigned DiagID;
1962
1963      // Always complain about dynamic classes.
1964      if (isDynamicClassType(PointeeTy))
1965        DiagID = diag::warn_dyn_class_memaccess;
1966      else if (PointeeTy.hasNonTrivialObjCLifetime() && CMF != CMF_Memset)
1967        DiagID = diag::warn_arc_object_memaccess;
1968      else
1969        continue;
1970
1971      DiagRuntimeBehavior(
1972        Dest->getExprLoc(), Dest,
1973        PDiag(DiagID)
1974          << ArgIdx << FnName << PointeeTy
1975          << Call->getCallee()->getSourceRange());
1976
1977      DiagRuntimeBehavior(
1978        Dest->getExprLoc(), Dest,
1979        PDiag(diag::note_bad_memaccess_silence)
1980          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
1981      break;
1982    }
1983  }
1984}
1985
1986//===--- CHECK: Return Address of Stack Variable --------------------------===//
1987
1988static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars);
1989static Expr *EvalAddr(Expr* E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars);
1990
1991/// CheckReturnStackAddr - Check if a return statement returns the address
1992///   of a stack variable.
1993void
1994Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
1995                           SourceLocation ReturnLoc) {
1996
1997  Expr *stackE = 0;
1998  llvm::SmallVector<DeclRefExpr *, 8> refVars;
1999
2000  // Perform checking for returned stack addresses, local blocks,
2001  // label addresses or references to temporaries.
2002  if (lhsType->isPointerType() ||
2003      (!getLangOptions().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
2004    stackE = EvalAddr(RetValExp, refVars);
2005  } else if (lhsType->isReferenceType()) {
2006    stackE = EvalVal(RetValExp, refVars);
2007  }
2008
2009  if (stackE == 0)
2010    return; // Nothing suspicious was found.
2011
2012  SourceLocation diagLoc;
2013  SourceRange diagRange;
2014  if (refVars.empty()) {
2015    diagLoc = stackE->getLocStart();
2016    diagRange = stackE->getSourceRange();
2017  } else {
2018    // We followed through a reference variable. 'stackE' contains the
2019    // problematic expression but we will warn at the return statement pointing
2020    // at the reference variable. We will later display the "trail" of
2021    // reference variables using notes.
2022    diagLoc = refVars[0]->getLocStart();
2023    diagRange = refVars[0]->getSourceRange();
2024  }
2025
2026  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
2027    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
2028                                             : diag::warn_ret_stack_addr)
2029     << DR->getDecl()->getDeclName() << diagRange;
2030  } else if (isa<BlockExpr>(stackE)) { // local block.
2031    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
2032  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
2033    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
2034  } else { // local temporary.
2035    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
2036                                             : diag::warn_ret_local_temp_addr)
2037     << diagRange;
2038  }
2039
2040  // Display the "trail" of reference variables that we followed until we
2041  // found the problematic expression using notes.
2042  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
2043    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
2044    // If this var binds to another reference var, show the range of the next
2045    // var, otherwise the var binds to the problematic expression, in which case
2046    // show the range of the expression.
2047    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
2048                                  : stackE->getSourceRange();
2049    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
2050      << VD->getDeclName() << range;
2051  }
2052}
2053
2054/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
2055///  check if the expression in a return statement evaluates to an address
2056///  to a location on the stack, a local block, an address of a label, or a
2057///  reference to local temporary. The recursion is used to traverse the
2058///  AST of the return expression, with recursion backtracking when we
2059///  encounter a subexpression that (1) clearly does not lead to one of the
2060///  above problematic expressions (2) is something we cannot determine leads to
2061///  a problematic expression based on such local checking.
2062///
2063///  Both EvalAddr and EvalVal follow through reference variables to evaluate
2064///  the expression that they point to. Such variables are added to the
2065///  'refVars' vector so that we know what the reference variable "trail" was.
2066///
2067///  EvalAddr processes expressions that are pointers that are used as
2068///  references (and not L-values).  EvalVal handles all other values.
2069///  At the base case of the recursion is a check for the above problematic
2070///  expressions.
2071///
2072///  This implementation handles:
2073///
2074///   * pointer-to-pointer casts
2075///   * implicit conversions from array references to pointers
2076///   * taking the address of fields
2077///   * arbitrary interplay between "&" and "*" operators
2078///   * pointer arithmetic from an address of a stack variable
2079///   * taking the address of an array element where the array is on the stack
2080static Expr *EvalAddr(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) {
2081  if (E->isTypeDependent())
2082      return NULL;
2083
2084  // We should only be called for evaluating pointer expressions.
2085  assert((E->getType()->isAnyPointerType() ||
2086          E->getType()->isBlockPointerType() ||
2087          E->getType()->isObjCQualifiedIdType()) &&
2088         "EvalAddr only works on pointers");
2089
2090  E = E->IgnoreParens();
2091
2092  // Our "symbolic interpreter" is just a dispatch off the currently
2093  // viewed AST node.  We then recursively traverse the AST by calling
2094  // EvalAddr and EvalVal appropriately.
2095  switch (E->getStmtClass()) {
2096  case Stmt::DeclRefExprClass: {
2097    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2098
2099    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2100      // If this is a reference variable, follow through to the expression that
2101      // it points to.
2102      if (V->hasLocalStorage() &&
2103          V->getType()->isReferenceType() && V->hasInit()) {
2104        // Add the reference variable to the "trail".
2105        refVars.push_back(DR);
2106        return EvalAddr(V->getInit(), refVars);
2107      }
2108
2109    return NULL;
2110  }
2111
2112  case Stmt::UnaryOperatorClass: {
2113    // The only unary operator that make sense to handle here
2114    // is AddrOf.  All others don't make sense as pointers.
2115    UnaryOperator *U = cast<UnaryOperator>(E);
2116
2117    if (U->getOpcode() == UO_AddrOf)
2118      return EvalVal(U->getSubExpr(), refVars);
2119    else
2120      return NULL;
2121  }
2122
2123  case Stmt::BinaryOperatorClass: {
2124    // Handle pointer arithmetic.  All other binary operators are not valid
2125    // in this context.
2126    BinaryOperator *B = cast<BinaryOperator>(E);
2127    BinaryOperatorKind op = B->getOpcode();
2128
2129    if (op != BO_Add && op != BO_Sub)
2130      return NULL;
2131
2132    Expr *Base = B->getLHS();
2133
2134    // Determine which argument is the real pointer base.  It could be
2135    // the RHS argument instead of the LHS.
2136    if (!Base->getType()->isPointerType()) Base = B->getRHS();
2137
2138    assert (Base->getType()->isPointerType());
2139    return EvalAddr(Base, refVars);
2140  }
2141
2142  // For conditional operators we need to see if either the LHS or RHS are
2143  // valid DeclRefExpr*s.  If one of them is valid, we return it.
2144  case Stmt::ConditionalOperatorClass: {
2145    ConditionalOperator *C = cast<ConditionalOperator>(E);
2146
2147    // Handle the GNU extension for missing LHS.
2148    if (Expr *lhsExpr = C->getLHS()) {
2149    // In C++, we can have a throw-expression, which has 'void' type.
2150      if (!lhsExpr->getType()->isVoidType())
2151        if (Expr* LHS = EvalAddr(lhsExpr, refVars))
2152          return LHS;
2153    }
2154
2155    // In C++, we can have a throw-expression, which has 'void' type.
2156    if (C->getRHS()->getType()->isVoidType())
2157      return NULL;
2158
2159    return EvalAddr(C->getRHS(), refVars);
2160  }
2161
2162  case Stmt::BlockExprClass:
2163    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
2164      return E; // local block.
2165    return NULL;
2166
2167  case Stmt::AddrLabelExprClass:
2168    return E; // address of label.
2169
2170  // For casts, we need to handle conversions from arrays to
2171  // pointer values, and pointer-to-pointer conversions.
2172  case Stmt::ImplicitCastExprClass:
2173  case Stmt::CStyleCastExprClass:
2174  case Stmt::CXXFunctionalCastExprClass:
2175  case Stmt::ObjCBridgedCastExprClass: {
2176    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
2177    QualType T = SubExpr->getType();
2178
2179    if (SubExpr->getType()->isPointerType() ||
2180        SubExpr->getType()->isBlockPointerType() ||
2181        SubExpr->getType()->isObjCQualifiedIdType())
2182      return EvalAddr(SubExpr, refVars);
2183    else if (T->isArrayType())
2184      return EvalVal(SubExpr, refVars);
2185    else
2186      return 0;
2187  }
2188
2189  // C++ casts.  For dynamic casts, static casts, and const casts, we
2190  // are always converting from a pointer-to-pointer, so we just blow
2191  // through the cast.  In the case the dynamic cast doesn't fail (and
2192  // return NULL), we take the conservative route and report cases
2193  // where we return the address of a stack variable.  For Reinterpre
2194  // FIXME: The comment about is wrong; we're not always converting
2195  // from pointer to pointer. I'm guessing that this code should also
2196  // handle references to objects.
2197  case Stmt::CXXStaticCastExprClass:
2198  case Stmt::CXXDynamicCastExprClass:
2199  case Stmt::CXXConstCastExprClass:
2200  case Stmt::CXXReinterpretCastExprClass: {
2201      Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr();
2202      if (S->getType()->isPointerType() || S->getType()->isBlockPointerType())
2203        return EvalAddr(S, refVars);
2204      else
2205        return NULL;
2206  }
2207
2208  case Stmt::MaterializeTemporaryExprClass:
2209    if (Expr *Result = EvalAddr(
2210                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
2211                                refVars))
2212      return Result;
2213
2214    return E;
2215
2216  // Everything else: we simply don't reason about them.
2217  default:
2218    return NULL;
2219  }
2220}
2221
2222
2223///  EvalVal - This function is complements EvalAddr in the mutual recursion.
2224///   See the comments for EvalAddr for more details.
2225static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) {
2226do {
2227  // We should only be called for evaluating non-pointer expressions, or
2228  // expressions with a pointer type that are not used as references but instead
2229  // are l-values (e.g., DeclRefExpr with a pointer type).
2230
2231  // Our "symbolic interpreter" is just a dispatch off the currently
2232  // viewed AST node.  We then recursively traverse the AST by calling
2233  // EvalAddr and EvalVal appropriately.
2234
2235  E = E->IgnoreParens();
2236  switch (E->getStmtClass()) {
2237  case Stmt::ImplicitCastExprClass: {
2238    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
2239    if (IE->getValueKind() == VK_LValue) {
2240      E = IE->getSubExpr();
2241      continue;
2242    }
2243    return NULL;
2244  }
2245
2246  case Stmt::DeclRefExprClass: {
2247    // When we hit a DeclRefExpr we are looking at code that refers to a
2248    // variable's name. If it's not a reference variable we check if it has
2249    // local storage within the function, and if so, return the expression.
2250    DeclRefExpr *DR = cast<DeclRefExpr>(E);
2251
2252    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
2253      if (V->hasLocalStorage()) {
2254        if (!V->getType()->isReferenceType())
2255          return DR;
2256
2257        // Reference variable, follow through to the expression that
2258        // it points to.
2259        if (V->hasInit()) {
2260          // Add the reference variable to the "trail".
2261          refVars.push_back(DR);
2262          return EvalVal(V->getInit(), refVars);
2263        }
2264      }
2265
2266    return NULL;
2267  }
2268
2269  case Stmt::UnaryOperatorClass: {
2270    // The only unary operator that make sense to handle here
2271    // is Deref.  All others don't resolve to a "name."  This includes
2272    // handling all sorts of rvalues passed to a unary operator.
2273    UnaryOperator *U = cast<UnaryOperator>(E);
2274
2275    if (U->getOpcode() == UO_Deref)
2276      return EvalAddr(U->getSubExpr(), refVars);
2277
2278    return NULL;
2279  }
2280
2281  case Stmt::ArraySubscriptExprClass: {
2282    // Array subscripts are potential references to data on the stack.  We
2283    // retrieve the DeclRefExpr* for the array variable if it indeed
2284    // has local storage.
2285    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars);
2286  }
2287
2288  case Stmt::ConditionalOperatorClass: {
2289    // For conditional operators we need to see if either the LHS or RHS are
2290    // non-NULL Expr's.  If one is non-NULL, we return it.
2291    ConditionalOperator *C = cast<ConditionalOperator>(E);
2292
2293    // Handle the GNU extension for missing LHS.
2294    if (Expr *lhsExpr = C->getLHS())
2295      if (Expr *LHS = EvalVal(lhsExpr, refVars))
2296        return LHS;
2297
2298    return EvalVal(C->getRHS(), refVars);
2299  }
2300
2301  // Accesses to members are potential references to data on the stack.
2302  case Stmt::MemberExprClass: {
2303    MemberExpr *M = cast<MemberExpr>(E);
2304
2305    // Check for indirect access.  We only want direct field accesses.
2306    if (M->isArrow())
2307      return NULL;
2308
2309    // Check whether the member type is itself a reference, in which case
2310    // we're not going to refer to the member, but to what the member refers to.
2311    if (M->getMemberDecl()->getType()->isReferenceType())
2312      return NULL;
2313
2314    return EvalVal(M->getBase(), refVars);
2315  }
2316
2317  case Stmt::MaterializeTemporaryExprClass:
2318    if (Expr *Result = EvalVal(
2319                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
2320                               refVars))
2321      return Result;
2322
2323    return E;
2324
2325  default:
2326    // Check that we don't return or take the address of a reference to a
2327    // temporary. This is only useful in C++.
2328    if (!E->isTypeDependent() && E->isRValue())
2329      return E;
2330
2331    // Everything else: we simply don't reason about them.
2332    return NULL;
2333  }
2334} while (true);
2335}
2336
2337//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
2338
2339/// Check for comparisons of floating point operands using != and ==.
2340/// Issue a warning if these are no self-comparisons, as they are not likely
2341/// to do what the programmer intended.
2342void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) {
2343  bool EmitWarning = true;
2344
2345  Expr* LeftExprSansParen = lex->IgnoreParenImpCasts();
2346  Expr* RightExprSansParen = rex->IgnoreParenImpCasts();
2347
2348  // Special case: check for x == x (which is OK).
2349  // Do not emit warnings for such cases.
2350  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
2351    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
2352      if (DRL->getDecl() == DRR->getDecl())
2353        EmitWarning = false;
2354
2355
2356  // Special case: check for comparisons against literals that can be exactly
2357  //  represented by APFloat.  In such cases, do not emit a warning.  This
2358  //  is a heuristic: often comparison against such literals are used to
2359  //  detect if a value in a variable has not changed.  This clearly can
2360  //  lead to false negatives.
2361  if (EmitWarning) {
2362    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
2363      if (FLL->isExact())
2364        EmitWarning = false;
2365    } else
2366      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
2367        if (FLR->isExact())
2368          EmitWarning = false;
2369    }
2370  }
2371
2372  // Check for comparisons with builtin types.
2373  if (EmitWarning)
2374    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
2375      if (CL->isBuiltinCall(Context))
2376        EmitWarning = false;
2377
2378  if (EmitWarning)
2379    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
2380      if (CR->isBuiltinCall(Context))
2381        EmitWarning = false;
2382
2383  // Emit the diagnostic.
2384  if (EmitWarning)
2385    Diag(loc, diag::warn_floatingpoint_eq)
2386      << lex->getSourceRange() << rex->getSourceRange();
2387}
2388
2389//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
2390//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
2391
2392namespace {
2393
2394/// Structure recording the 'active' range of an integer-valued
2395/// expression.
2396struct IntRange {
2397  /// The number of bits active in the int.
2398  unsigned Width;
2399
2400  /// True if the int is known not to have negative values.
2401  bool NonNegative;
2402
2403  IntRange(unsigned Width, bool NonNegative)
2404    : Width(Width), NonNegative(NonNegative)
2405  {}
2406
2407  /// Returns the range of the bool type.
2408  static IntRange forBoolType() {
2409    return IntRange(1, true);
2410  }
2411
2412  /// Returns the range of an opaque value of the given integral type.
2413  static IntRange forValueOfType(ASTContext &C, QualType T) {
2414    return forValueOfCanonicalType(C,
2415                          T->getCanonicalTypeInternal().getTypePtr());
2416  }
2417
2418  /// Returns the range of an opaque value of a canonical integral type.
2419  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
2420    assert(T->isCanonicalUnqualified());
2421
2422    if (const VectorType *VT = dyn_cast<VectorType>(T))
2423      T = VT->getElementType().getTypePtr();
2424    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
2425      T = CT->getElementType().getTypePtr();
2426
2427    // For enum types, use the known bit width of the enumerators.
2428    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
2429      EnumDecl *Enum = ET->getDecl();
2430      if (!Enum->isDefinition())
2431        return IntRange(C.getIntWidth(QualType(T, 0)), false);
2432
2433      unsigned NumPositive = Enum->getNumPositiveBits();
2434      unsigned NumNegative = Enum->getNumNegativeBits();
2435
2436      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
2437    }
2438
2439    const BuiltinType *BT = cast<BuiltinType>(T);
2440    assert(BT->isInteger());
2441
2442    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
2443  }
2444
2445  /// Returns the "target" range of a canonical integral type, i.e.
2446  /// the range of values expressible in the type.
2447  ///
2448  /// This matches forValueOfCanonicalType except that enums have the
2449  /// full range of their type, not the range of their enumerators.
2450  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
2451    assert(T->isCanonicalUnqualified());
2452
2453    if (const VectorType *VT = dyn_cast<VectorType>(T))
2454      T = VT->getElementType().getTypePtr();
2455    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
2456      T = CT->getElementType().getTypePtr();
2457    if (const EnumType *ET = dyn_cast<EnumType>(T))
2458      T = ET->getDecl()->getIntegerType().getTypePtr();
2459
2460    const BuiltinType *BT = cast<BuiltinType>(T);
2461    assert(BT->isInteger());
2462
2463    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
2464  }
2465
2466  /// Returns the supremum of two ranges: i.e. their conservative merge.
2467  static IntRange join(IntRange L, IntRange R) {
2468    return IntRange(std::max(L.Width, R.Width),
2469                    L.NonNegative && R.NonNegative);
2470  }
2471
2472  /// Returns the infinum of two ranges: i.e. their aggressive merge.
2473  static IntRange meet(IntRange L, IntRange R) {
2474    return IntRange(std::min(L.Width, R.Width),
2475                    L.NonNegative || R.NonNegative);
2476  }
2477};
2478
2479IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) {
2480  if (value.isSigned() && value.isNegative())
2481    return IntRange(value.getMinSignedBits(), false);
2482
2483  if (value.getBitWidth() > MaxWidth)
2484    value = value.trunc(MaxWidth);
2485
2486  // isNonNegative() just checks the sign bit without considering
2487  // signedness.
2488  return IntRange(value.getActiveBits(), true);
2489}
2490
2491IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
2492                       unsigned MaxWidth) {
2493  if (result.isInt())
2494    return GetValueRange(C, result.getInt(), MaxWidth);
2495
2496  if (result.isVector()) {
2497    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
2498    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
2499      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
2500      R = IntRange::join(R, El);
2501    }
2502    return R;
2503  }
2504
2505  if (result.isComplexInt()) {
2506    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
2507    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
2508    return IntRange::join(R, I);
2509  }
2510
2511  // This can happen with lossless casts to intptr_t of "based" lvalues.
2512  // Assume it might use arbitrary bits.
2513  // FIXME: The only reason we need to pass the type in here is to get
2514  // the sign right on this one case.  It would be nice if APValue
2515  // preserved this.
2516  assert(result.isLValue());
2517  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
2518}
2519
2520/// Pseudo-evaluate the given integer expression, estimating the
2521/// range of values it might take.
2522///
2523/// \param MaxWidth - the width to which the value will be truncated
2524IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
2525  E = E->IgnoreParens();
2526
2527  // Try a full evaluation first.
2528  Expr::EvalResult result;
2529  if (E->Evaluate(result, C))
2530    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
2531
2532  // I think we only want to look through implicit casts here; if the
2533  // user has an explicit widening cast, we should treat the value as
2534  // being of the new, wider type.
2535  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
2536    if (CE->getCastKind() == CK_NoOp)
2537      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
2538
2539    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
2540
2541    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
2542
2543    // Assume that non-integer casts can span the full range of the type.
2544    if (!isIntegerCast)
2545      return OutputTypeRange;
2546
2547    IntRange SubRange
2548      = GetExprRange(C, CE->getSubExpr(),
2549                     std::min(MaxWidth, OutputTypeRange.Width));
2550
2551    // Bail out if the subexpr's range is as wide as the cast type.
2552    if (SubRange.Width >= OutputTypeRange.Width)
2553      return OutputTypeRange;
2554
2555    // Otherwise, we take the smaller width, and we're non-negative if
2556    // either the output type or the subexpr is.
2557    return IntRange(SubRange.Width,
2558                    SubRange.NonNegative || OutputTypeRange.NonNegative);
2559  }
2560
2561  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
2562    // If we can fold the condition, just take that operand.
2563    bool CondResult;
2564    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
2565      return GetExprRange(C, CondResult ? CO->getTrueExpr()
2566                                        : CO->getFalseExpr(),
2567                          MaxWidth);
2568
2569    // Otherwise, conservatively merge.
2570    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
2571    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
2572    return IntRange::join(L, R);
2573  }
2574
2575  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
2576    switch (BO->getOpcode()) {
2577
2578    // Boolean-valued operations are single-bit and positive.
2579    case BO_LAnd:
2580    case BO_LOr:
2581    case BO_LT:
2582    case BO_GT:
2583    case BO_LE:
2584    case BO_GE:
2585    case BO_EQ:
2586    case BO_NE:
2587      return IntRange::forBoolType();
2588
2589    // The type of the assignments is the type of the LHS, so the RHS
2590    // is not necessarily the same type.
2591    case BO_MulAssign:
2592    case BO_DivAssign:
2593    case BO_RemAssign:
2594    case BO_AddAssign:
2595    case BO_SubAssign:
2596    case BO_XorAssign:
2597    case BO_OrAssign:
2598      // TODO: bitfields?
2599      return IntRange::forValueOfType(C, E->getType());
2600
2601    // Simple assignments just pass through the RHS, which will have
2602    // been coerced to the LHS type.
2603    case BO_Assign:
2604      // TODO: bitfields?
2605      return GetExprRange(C, BO->getRHS(), MaxWidth);
2606
2607    // Operations with opaque sources are black-listed.
2608    case BO_PtrMemD:
2609    case BO_PtrMemI:
2610      return IntRange::forValueOfType(C, E->getType());
2611
2612    // Bitwise-and uses the *infinum* of the two source ranges.
2613    case BO_And:
2614    case BO_AndAssign:
2615      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
2616                            GetExprRange(C, BO->getRHS(), MaxWidth));
2617
2618    // Left shift gets black-listed based on a judgement call.
2619    case BO_Shl:
2620      // ...except that we want to treat '1 << (blah)' as logically
2621      // positive.  It's an important idiom.
2622      if (IntegerLiteral *I
2623            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
2624        if (I->getValue() == 1) {
2625          IntRange R = IntRange::forValueOfType(C, E->getType());
2626          return IntRange(R.Width, /*NonNegative*/ true);
2627        }
2628      }
2629      // fallthrough
2630
2631    case BO_ShlAssign:
2632      return IntRange::forValueOfType(C, E->getType());
2633
2634    // Right shift by a constant can narrow its left argument.
2635    case BO_Shr:
2636    case BO_ShrAssign: {
2637      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
2638
2639      // If the shift amount is a positive constant, drop the width by
2640      // that much.
2641      llvm::APSInt shift;
2642      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
2643          shift.isNonNegative()) {
2644        unsigned zext = shift.getZExtValue();
2645        if (zext >= L.Width)
2646          L.Width = (L.NonNegative ? 0 : 1);
2647        else
2648          L.Width -= zext;
2649      }
2650
2651      return L;
2652    }
2653
2654    // Comma acts as its right operand.
2655    case BO_Comma:
2656      return GetExprRange(C, BO->getRHS(), MaxWidth);
2657
2658    // Black-list pointer subtractions.
2659    case BO_Sub:
2660      if (BO->getLHS()->getType()->isPointerType())
2661        return IntRange::forValueOfType(C, E->getType());
2662      // fallthrough
2663
2664    default:
2665      break;
2666    }
2667
2668    // Treat every other operator as if it were closed on the
2669    // narrowest type that encompasses both operands.
2670    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
2671    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
2672    return IntRange::join(L, R);
2673  }
2674
2675  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
2676    switch (UO->getOpcode()) {
2677    // Boolean-valued operations are white-listed.
2678    case UO_LNot:
2679      return IntRange::forBoolType();
2680
2681    // Operations with opaque sources are black-listed.
2682    case UO_Deref:
2683    case UO_AddrOf: // should be impossible
2684      return IntRange::forValueOfType(C, E->getType());
2685
2686    default:
2687      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
2688    }
2689  }
2690
2691  if (dyn_cast<OffsetOfExpr>(E)) {
2692    IntRange::forValueOfType(C, E->getType());
2693  }
2694
2695  FieldDecl *BitField = E->getBitField();
2696  if (BitField) {
2697    llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C);
2698    unsigned BitWidth = BitWidthAP.getZExtValue();
2699
2700    return IntRange(BitWidth,
2701                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
2702  }
2703
2704  return IntRange::forValueOfType(C, E->getType());
2705}
2706
2707IntRange GetExprRange(ASTContext &C, Expr *E) {
2708  return GetExprRange(C, E, C.getIntWidth(E->getType()));
2709}
2710
2711/// Checks whether the given value, which currently has the given
2712/// source semantics, has the same value when coerced through the
2713/// target semantics.
2714bool IsSameFloatAfterCast(const llvm::APFloat &value,
2715                          const llvm::fltSemantics &Src,
2716                          const llvm::fltSemantics &Tgt) {
2717  llvm::APFloat truncated = value;
2718
2719  bool ignored;
2720  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
2721  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
2722
2723  return truncated.bitwiseIsEqual(value);
2724}
2725
2726/// Checks whether the given value, which currently has the given
2727/// source semantics, has the same value when coerced through the
2728/// target semantics.
2729///
2730/// The value might be a vector of floats (or a complex number).
2731bool IsSameFloatAfterCast(const APValue &value,
2732                          const llvm::fltSemantics &Src,
2733                          const llvm::fltSemantics &Tgt) {
2734  if (value.isFloat())
2735    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
2736
2737  if (value.isVector()) {
2738    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
2739      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
2740        return false;
2741    return true;
2742  }
2743
2744  assert(value.isComplexFloat());
2745  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
2746          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
2747}
2748
2749void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
2750
2751static bool IsZero(Sema &S, Expr *E) {
2752  // Suppress cases where we are comparing against an enum constant.
2753  if (const DeclRefExpr *DR =
2754      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
2755    if (isa<EnumConstantDecl>(DR->getDecl()))
2756      return false;
2757
2758  // Suppress cases where the '0' value is expanded from a macro.
2759  if (E->getLocStart().isMacroID())
2760    return false;
2761
2762  llvm::APSInt Value;
2763  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
2764}
2765
2766static bool HasEnumType(Expr *E) {
2767  // Strip off implicit integral promotions.
2768  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
2769    if (ICE->getCastKind() != CK_IntegralCast &&
2770        ICE->getCastKind() != CK_NoOp)
2771      break;
2772    E = ICE->getSubExpr();
2773  }
2774
2775  return E->getType()->isEnumeralType();
2776}
2777
2778void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
2779  BinaryOperatorKind op = E->getOpcode();
2780  if (E->isValueDependent())
2781    return;
2782
2783  if (op == BO_LT && IsZero(S, E->getRHS())) {
2784    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
2785      << "< 0" << "false" << HasEnumType(E->getLHS())
2786      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
2787  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
2788    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
2789      << ">= 0" << "true" << HasEnumType(E->getLHS())
2790      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
2791  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
2792    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
2793      << "0 >" << "false" << HasEnumType(E->getRHS())
2794      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
2795  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
2796    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
2797      << "0 <=" << "true" << HasEnumType(E->getRHS())
2798      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
2799  }
2800}
2801
2802/// Analyze the operands of the given comparison.  Implements the
2803/// fallback case from AnalyzeComparison.
2804void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
2805  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
2806  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
2807}
2808
2809/// \brief Implements -Wsign-compare.
2810///
2811/// \param lex the left-hand expression
2812/// \param rex the right-hand expression
2813/// \param OpLoc the location of the joining operator
2814/// \param BinOpc binary opcode or 0
2815void AnalyzeComparison(Sema &S, BinaryOperator *E) {
2816  // The type the comparison is being performed in.
2817  QualType T = E->getLHS()->getType();
2818  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
2819         && "comparison with mismatched types");
2820
2821  // We don't do anything special if this isn't an unsigned integral
2822  // comparison:  we're only interested in integral comparisons, and
2823  // signed comparisons only happen in cases we don't care to warn about.
2824  //
2825  // We also don't care about value-dependent expressions or expressions
2826  // whose result is a constant.
2827  if (!T->hasUnsignedIntegerRepresentation()
2828      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
2829    return AnalyzeImpConvsInComparison(S, E);
2830
2831  Expr *lex = E->getLHS()->IgnoreParenImpCasts();
2832  Expr *rex = E->getRHS()->IgnoreParenImpCasts();
2833
2834  // Check to see if one of the (unmodified) operands is of different
2835  // signedness.
2836  Expr *signedOperand, *unsignedOperand;
2837  if (lex->getType()->hasSignedIntegerRepresentation()) {
2838    assert(!rex->getType()->hasSignedIntegerRepresentation() &&
2839           "unsigned comparison between two signed integer expressions?");
2840    signedOperand = lex;
2841    unsignedOperand = rex;
2842  } else if (rex->getType()->hasSignedIntegerRepresentation()) {
2843    signedOperand = rex;
2844    unsignedOperand = lex;
2845  } else {
2846    CheckTrivialUnsignedComparison(S, E);
2847    return AnalyzeImpConvsInComparison(S, E);
2848  }
2849
2850  // Otherwise, calculate the effective range of the signed operand.
2851  IntRange signedRange = GetExprRange(S.Context, signedOperand);
2852
2853  // Go ahead and analyze implicit conversions in the operands.  Note
2854  // that we skip the implicit conversions on both sides.
2855  AnalyzeImplicitConversions(S, lex, E->getOperatorLoc());
2856  AnalyzeImplicitConversions(S, rex, E->getOperatorLoc());
2857
2858  // If the signed range is non-negative, -Wsign-compare won't fire,
2859  // but we should still check for comparisons which are always true
2860  // or false.
2861  if (signedRange.NonNegative)
2862    return CheckTrivialUnsignedComparison(S, E);
2863
2864  // For (in)equality comparisons, if the unsigned operand is a
2865  // constant which cannot collide with a overflowed signed operand,
2866  // then reinterpreting the signed operand as unsigned will not
2867  // change the result of the comparison.
2868  if (E->isEqualityOp()) {
2869    unsigned comparisonWidth = S.Context.getIntWidth(T);
2870    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
2871
2872    // We should never be unable to prove that the unsigned operand is
2873    // non-negative.
2874    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
2875
2876    if (unsignedRange.Width < comparisonWidth)
2877      return;
2878  }
2879
2880  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
2881    << lex->getType() << rex->getType()
2882    << lex->getSourceRange() << rex->getSourceRange();
2883}
2884
2885/// Analyzes an attempt to assign the given value to a bitfield.
2886///
2887/// Returns true if there was something fishy about the attempt.
2888bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
2889                               SourceLocation InitLoc) {
2890  assert(Bitfield->isBitField());
2891  if (Bitfield->isInvalidDecl())
2892    return false;
2893
2894  // White-list bool bitfields.
2895  if (Bitfield->getType()->isBooleanType())
2896    return false;
2897
2898  // Ignore value- or type-dependent expressions.
2899  if (Bitfield->getBitWidth()->isValueDependent() ||
2900      Bitfield->getBitWidth()->isTypeDependent() ||
2901      Init->isValueDependent() ||
2902      Init->isTypeDependent())
2903    return false;
2904
2905  Expr *OriginalInit = Init->IgnoreParenImpCasts();
2906
2907  llvm::APSInt Width(32);
2908  Expr::EvalResult InitValue;
2909  if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) ||
2910      !OriginalInit->Evaluate(InitValue, S.Context) ||
2911      !InitValue.Val.isInt())
2912    return false;
2913
2914  const llvm::APSInt &Value = InitValue.Val.getInt();
2915  unsigned OriginalWidth = Value.getBitWidth();
2916  unsigned FieldWidth = Width.getZExtValue();
2917
2918  if (OriginalWidth <= FieldWidth)
2919    return false;
2920
2921  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
2922
2923  // It's fairly common to write values into signed bitfields
2924  // that, if sign-extended, would end up becoming a different
2925  // value.  We don't want to warn about that.
2926  if (Value.isSigned() && Value.isNegative())
2927    TruncatedValue = TruncatedValue.sext(OriginalWidth);
2928  else
2929    TruncatedValue = TruncatedValue.zext(OriginalWidth);
2930
2931  if (Value == TruncatedValue)
2932    return false;
2933
2934  std::string PrettyValue = Value.toString(10);
2935  std::string PrettyTrunc = TruncatedValue.toString(10);
2936
2937  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
2938    << PrettyValue << PrettyTrunc << OriginalInit->getType()
2939    << Init->getSourceRange();
2940
2941  return true;
2942}
2943
2944/// Analyze the given simple or compound assignment for warning-worthy
2945/// operations.
2946void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
2947  // Just recurse on the LHS.
2948  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
2949
2950  // We want to recurse on the RHS as normal unless we're assigning to
2951  // a bitfield.
2952  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
2953    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
2954                                  E->getOperatorLoc())) {
2955      // Recurse, ignoring any implicit conversions on the RHS.
2956      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
2957                                        E->getOperatorLoc());
2958    }
2959  }
2960
2961  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
2962}
2963
2964/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
2965void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
2966                     SourceLocation CContext, unsigned diag) {
2967  S.Diag(E->getExprLoc(), diag)
2968    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
2969}
2970
2971/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
2972void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext,
2973                     unsigned diag) {
2974  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag);
2975}
2976
2977/// Diagnose an implicit cast from a literal expression. Also attemps to supply
2978/// fixit hints when the cast wouldn't lose information to simply write the
2979/// expression with the expected type.
2980void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
2981                                    SourceLocation CContext) {
2982  // Emit the primary warning first, then try to emit a fixit hint note if
2983  // reasonable.
2984  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
2985    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
2986
2987  const llvm::APFloat &Value = FL->getValue();
2988
2989  // Don't attempt to fix PPC double double literals.
2990  if (&Value.getSemantics() == &llvm::APFloat::PPCDoubleDouble)
2991    return;
2992
2993  // Try to convert this exactly to an 64-bit integer. FIXME: It would be
2994  // nice to support arbitrarily large integers here.
2995  bool isExact = false;
2996  uint64_t IntegerPart;
2997  if (Value.convertToInteger(&IntegerPart, 64, /*isSigned=*/true,
2998                             llvm::APFloat::rmTowardZero, &isExact)
2999      != llvm::APFloat::opOK || !isExact)
3000    return;
3001
3002  llvm::APInt IntegerValue(64, IntegerPart, /*isSigned=*/true);
3003
3004  std::string LiteralValue = IntegerValue.toString(10, /*isSigned=*/true);
3005  S.Diag(FL->getExprLoc(), diag::note_fix_integral_float_as_integer)
3006    << FixItHint::CreateReplacement(FL->getSourceRange(), LiteralValue);
3007}
3008
3009std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
3010  if (!Range.Width) return "0";
3011
3012  llvm::APSInt ValueInRange = Value;
3013  ValueInRange.setIsSigned(!Range.NonNegative);
3014  ValueInRange = ValueInRange.trunc(Range.Width);
3015  return ValueInRange.toString(10);
3016}
3017
3018static bool isFromSystemMacro(Sema &S, SourceLocation loc) {
3019  SourceManager &smgr = S.Context.getSourceManager();
3020  return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc));
3021}
3022
3023void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
3024                             SourceLocation CC, bool *ICContext = 0) {
3025  if (E->isTypeDependent() || E->isValueDependent()) return;
3026
3027  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
3028  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
3029  if (Source == Target) return;
3030  if (Target->isDependentType()) return;
3031
3032  // If the conversion context location is invalid don't complain.
3033  // We also don't want to emit a warning if the issue occurs from the
3034  // instantiation of a system macro.  The problem is that 'getSpellingLoc()'
3035  // is slow, so we delay this check as long as possible.  Once we detect
3036  // we are in that scenario, we just return.
3037  if (CC.isInvalid())
3038    return;
3039
3040  // Never diagnose implicit casts to bool.
3041  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
3042    return;
3043
3044  // Strip vector types.
3045  if (isa<VectorType>(Source)) {
3046    if (!isa<VectorType>(Target)) {
3047      if (isFromSystemMacro(S, CC))
3048        return;
3049      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
3050    }
3051
3052    // If the vector cast is cast between two vectors of the same size, it is
3053    // a bitcast, not a conversion.
3054    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
3055      return;
3056
3057    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
3058    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
3059  }
3060
3061  // Strip complex types.
3062  if (isa<ComplexType>(Source)) {
3063    if (!isa<ComplexType>(Target)) {
3064      if (isFromSystemMacro(S, CC))
3065        return;
3066
3067      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
3068    }
3069
3070    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
3071    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
3072  }
3073
3074  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
3075  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
3076
3077  // If the source is floating point...
3078  if (SourceBT && SourceBT->isFloatingPoint()) {
3079    // ...and the target is floating point...
3080    if (TargetBT && TargetBT->isFloatingPoint()) {
3081      // ...then warn if we're dropping FP rank.
3082
3083      // Builtin FP kinds are ordered by increasing FP rank.
3084      if (SourceBT->getKind() > TargetBT->getKind()) {
3085        // Don't warn about float constants that are precisely
3086        // representable in the target type.
3087        Expr::EvalResult result;
3088        if (E->Evaluate(result, S.Context)) {
3089          // Value might be a float, a float vector, or a float complex.
3090          if (IsSameFloatAfterCast(result.Val,
3091                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
3092                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
3093            return;
3094        }
3095
3096        if (isFromSystemMacro(S, CC))
3097          return;
3098
3099        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
3100      }
3101      return;
3102    }
3103
3104    // If the target is integral, always warn.
3105    if ((TargetBT && TargetBT->isInteger())) {
3106      if (isFromSystemMacro(S, CC))
3107        return;
3108
3109      Expr *InnerE = E->IgnoreParenImpCasts();
3110      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
3111        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
3112      } else {
3113        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
3114      }
3115    }
3116
3117    return;
3118  }
3119
3120  if (!Source->isIntegerType() || !Target->isIntegerType())
3121    return;
3122
3123  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
3124           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
3125    S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer)
3126        << E->getSourceRange() << clang::SourceRange(CC);
3127    return;
3128  }
3129
3130  IntRange SourceRange = GetExprRange(S.Context, E);
3131  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
3132
3133  if (SourceRange.Width > TargetRange.Width) {
3134    // If the source is a constant, use a default-on diagnostic.
3135    // TODO: this should happen for bitfield stores, too.
3136    llvm::APSInt Value(32);
3137    if (E->isIntegerConstantExpr(Value, S.Context)) {
3138      if (isFromSystemMacro(S, CC))
3139        return;
3140
3141      std::string PrettySourceValue = Value.toString(10);
3142      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
3143
3144      S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant)
3145        << PrettySourceValue << PrettyTargetValue
3146        << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC);
3147      return;
3148    }
3149
3150    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
3151    if (isFromSystemMacro(S, CC))
3152      return;
3153
3154    if (SourceRange.Width == 64 && TargetRange.Width == 32)
3155      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32);
3156    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
3157  }
3158
3159  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
3160      (!TargetRange.NonNegative && SourceRange.NonNegative &&
3161       SourceRange.Width == TargetRange.Width)) {
3162
3163    if (isFromSystemMacro(S, CC))
3164      return;
3165
3166    unsigned DiagID = diag::warn_impcast_integer_sign;
3167
3168    // Traditionally, gcc has warned about this under -Wsign-compare.
3169    // We also want to warn about it in -Wconversion.
3170    // So if -Wconversion is off, use a completely identical diagnostic
3171    // in the sign-compare group.
3172    // The conditional-checking code will
3173    if (ICContext) {
3174      DiagID = diag::warn_impcast_integer_sign_conditional;
3175      *ICContext = true;
3176    }
3177
3178    return DiagnoseImpCast(S, E, T, CC, DiagID);
3179  }
3180
3181  // Diagnose conversions between different enumeration types.
3182  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
3183  // type, to give us better diagnostics.
3184  QualType SourceType = E->getType();
3185  if (!S.getLangOptions().CPlusPlus) {
3186    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
3187      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
3188        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
3189        SourceType = S.Context.getTypeDeclType(Enum);
3190        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
3191      }
3192  }
3193
3194  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
3195    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
3196      if ((SourceEnum->getDecl()->getIdentifier() ||
3197           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
3198          (TargetEnum->getDecl()->getIdentifier() ||
3199           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
3200          SourceEnum != TargetEnum) {
3201        if (isFromSystemMacro(S, CC))
3202          return;
3203
3204        return DiagnoseImpCast(S, E, SourceType, T, CC,
3205                               diag::warn_impcast_different_enum_types);
3206      }
3207
3208  return;
3209}
3210
3211void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
3212
3213void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
3214                             SourceLocation CC, bool &ICContext) {
3215  E = E->IgnoreParenImpCasts();
3216
3217  if (isa<ConditionalOperator>(E))
3218    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
3219
3220  AnalyzeImplicitConversions(S, E, CC);
3221  if (E->getType() != T)
3222    return CheckImplicitConversion(S, E, T, CC, &ICContext);
3223  return;
3224}
3225
3226void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
3227  SourceLocation CC = E->getQuestionLoc();
3228
3229  AnalyzeImplicitConversions(S, E->getCond(), CC);
3230
3231  bool Suspicious = false;
3232  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
3233  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
3234
3235  // If -Wconversion would have warned about either of the candidates
3236  // for a signedness conversion to the context type...
3237  if (!Suspicious) return;
3238
3239  // ...but it's currently ignored...
3240  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
3241                                 CC))
3242    return;
3243
3244  // ...and -Wsign-compare isn't...
3245  if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional, CC))
3246    return;
3247
3248  // ...then check whether it would have warned about either of the
3249  // candidates for a signedness conversion to the condition type.
3250  if (E->getType() != T) {
3251    Suspicious = false;
3252    CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
3253                            E->getType(), CC, &Suspicious);
3254    if (!Suspicious)
3255      CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
3256                              E->getType(), CC, &Suspicious);
3257    if (!Suspicious)
3258      return;
3259  }
3260
3261  // If so, emit a diagnostic under -Wsign-compare.
3262  Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts();
3263  Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts();
3264  S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional)
3265    << lex->getType() << rex->getType()
3266    << lex->getSourceRange() << rex->getSourceRange();
3267}
3268
3269/// AnalyzeImplicitConversions - Find and report any interesting
3270/// implicit conversions in the given expression.  There are a couple
3271/// of competing diagnostics here, -Wconversion and -Wsign-compare.
3272void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
3273  QualType T = OrigE->getType();
3274  Expr *E = OrigE->IgnoreParenImpCasts();
3275
3276  // For conditional operators, we analyze the arguments as if they
3277  // were being fed directly into the output.
3278  if (isa<ConditionalOperator>(E)) {
3279    ConditionalOperator *CO = cast<ConditionalOperator>(E);
3280    CheckConditionalOperator(S, CO, T);
3281    return;
3282  }
3283
3284  // Go ahead and check any implicit conversions we might have skipped.
3285  // The non-canonical typecheck is just an optimization;
3286  // CheckImplicitConversion will filter out dead implicit conversions.
3287  if (E->getType() != T)
3288    CheckImplicitConversion(S, E, T, CC);
3289
3290  // Now continue drilling into this expression.
3291
3292  // Skip past explicit casts.
3293  if (isa<ExplicitCastExpr>(E)) {
3294    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
3295    return AnalyzeImplicitConversions(S, E, CC);
3296  }
3297
3298  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3299    // Do a somewhat different check with comparison operators.
3300    if (BO->isComparisonOp())
3301      return AnalyzeComparison(S, BO);
3302
3303    // And with assignments and compound assignments.
3304    if (BO->isAssignmentOp())
3305      return AnalyzeAssignment(S, BO);
3306  }
3307
3308  // These break the otherwise-useful invariant below.  Fortunately,
3309  // we don't really need to recurse into them, because any internal
3310  // expressions should have been analyzed already when they were
3311  // built into statements.
3312  if (isa<StmtExpr>(E)) return;
3313
3314  // Don't descend into unevaluated contexts.
3315  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
3316
3317  // Now just recurse over the expression's children.
3318  CC = E->getExprLoc();
3319  for (Stmt::child_range I = E->children(); I; ++I)
3320    AnalyzeImplicitConversions(S, cast<Expr>(*I), CC);
3321}
3322
3323} // end anonymous namespace
3324
3325/// Diagnoses "dangerous" implicit conversions within the given
3326/// expression (which is a full expression).  Implements -Wconversion
3327/// and -Wsign-compare.
3328///
3329/// \param CC the "context" location of the implicit conversion, i.e.
3330///   the most location of the syntactic entity requiring the implicit
3331///   conversion
3332void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
3333  // Don't diagnose in unevaluated contexts.
3334  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
3335    return;
3336
3337  // Don't diagnose for value- or type-dependent expressions.
3338  if (E->isTypeDependent() || E->isValueDependent())
3339    return;
3340
3341  // This is not the right CC for (e.g.) a variable initialization.
3342  AnalyzeImplicitConversions(*this, E, CC);
3343}
3344
3345void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
3346                                       FieldDecl *BitField,
3347                                       Expr *Init) {
3348  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
3349}
3350
3351/// CheckParmsForFunctionDef - Check that the parameters of the given
3352/// function are appropriate for the definition of a function. This
3353/// takes care of any checks that cannot be performed on the
3354/// declaration itself, e.g., that the types of each of the function
3355/// parameters are complete.
3356bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
3357                                    bool CheckParameterNames) {
3358  bool HasInvalidParm = false;
3359  for (; P != PEnd; ++P) {
3360    ParmVarDecl *Param = *P;
3361
3362    // C99 6.7.5.3p4: the parameters in a parameter type list in a
3363    // function declarator that is part of a function definition of
3364    // that function shall not have incomplete type.
3365    //
3366    // This is also C++ [dcl.fct]p6.
3367    if (!Param->isInvalidDecl() &&
3368        RequireCompleteType(Param->getLocation(), Param->getType(),
3369                               diag::err_typecheck_decl_incomplete_type)) {
3370      Param->setInvalidDecl();
3371      HasInvalidParm = true;
3372    }
3373
3374    // C99 6.9.1p5: If the declarator includes a parameter type list, the
3375    // declaration of each parameter shall include an identifier.
3376    if (CheckParameterNames &&
3377        Param->getIdentifier() == 0 &&
3378        !Param->isImplicit() &&
3379        !getLangOptions().CPlusPlus)
3380      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
3381
3382    // C99 6.7.5.3p12:
3383    //   If the function declarator is not part of a definition of that
3384    //   function, parameters may have incomplete type and may use the [*]
3385    //   notation in their sequences of declarator specifiers to specify
3386    //   variable length array types.
3387    QualType PType = Param->getOriginalType();
3388    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
3389      if (AT->getSizeModifier() == ArrayType::Star) {
3390        // FIXME: This diagnosic should point the the '[*]' if source-location
3391        // information is added for it.
3392        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
3393      }
3394    }
3395  }
3396
3397  return HasInvalidParm;
3398}
3399
3400/// CheckCastAlign - Implements -Wcast-align, which warns when a
3401/// pointer cast increases the alignment requirements.
3402void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
3403  // This is actually a lot of work to potentially be doing on every
3404  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
3405  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
3406                                          TRange.getBegin())
3407        == Diagnostic::Ignored)
3408    return;
3409
3410  // Ignore dependent types.
3411  if (T->isDependentType() || Op->getType()->isDependentType())
3412    return;
3413
3414  // Require that the destination be a pointer type.
3415  const PointerType *DestPtr = T->getAs<PointerType>();
3416  if (!DestPtr) return;
3417
3418  // If the destination has alignment 1, we're done.
3419  QualType DestPointee = DestPtr->getPointeeType();
3420  if (DestPointee->isIncompleteType()) return;
3421  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
3422  if (DestAlign.isOne()) return;
3423
3424  // Require that the source be a pointer type.
3425  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
3426  if (!SrcPtr) return;
3427  QualType SrcPointee = SrcPtr->getPointeeType();
3428
3429  // Whitelist casts from cv void*.  We already implicitly
3430  // whitelisted casts to cv void*, since they have alignment 1.
3431  // Also whitelist casts involving incomplete types, which implicitly
3432  // includes 'void'.
3433  if (SrcPointee->isIncompleteType()) return;
3434
3435  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
3436  if (SrcAlign >= DestAlign) return;
3437
3438  Diag(TRange.getBegin(), diag::warn_cast_align)
3439    << Op->getType() << T
3440    << static_cast<unsigned>(SrcAlign.getQuantity())
3441    << static_cast<unsigned>(DestAlign.getQuantity())
3442    << TRange << Op->getSourceRange();
3443}
3444
3445static void CheckArrayAccess_Check(Sema &S,
3446                                   const clang::ArraySubscriptExpr *E) {
3447  const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts();
3448  const ConstantArrayType *ArrayTy =
3449    S.Context.getAsConstantArrayType(BaseExpr->getType());
3450  if (!ArrayTy)
3451    return;
3452
3453  const Expr *IndexExpr = E->getIdx();
3454  if (IndexExpr->isValueDependent())
3455    return;
3456  llvm::APSInt index;
3457  if (!IndexExpr->isIntegerConstantExpr(index, S.Context))
3458    return;
3459
3460  if (index.isUnsigned() || !index.isNegative()) {
3461    llvm::APInt size = ArrayTy->getSize();
3462    if (!size.isStrictlyPositive())
3463      return;
3464    if (size.getBitWidth() > index.getBitWidth())
3465      index = index.sext(size.getBitWidth());
3466    else if (size.getBitWidth() < index.getBitWidth())
3467      size = size.sext(index.getBitWidth());
3468
3469    if (index.slt(size))
3470      return;
3471
3472    S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr,
3473                          S.PDiag(diag::warn_array_index_exceeds_bounds)
3474                            << index.toString(10, true)
3475                            << size.toString(10, true)
3476                            << IndexExpr->getSourceRange());
3477  } else {
3478    S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr,
3479                          S.PDiag(diag::warn_array_index_precedes_bounds)
3480                            << index.toString(10, true)
3481                            << IndexExpr->getSourceRange());
3482  }
3483
3484  const NamedDecl *ND = NULL;
3485  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
3486    ND = dyn_cast<NamedDecl>(DRE->getDecl());
3487  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
3488    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
3489  if (ND)
3490    S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
3491                          S.PDiag(diag::note_array_index_out_of_bounds)
3492                            << ND->getDeclName());
3493}
3494
3495void Sema::CheckArrayAccess(const Expr *expr) {
3496  while (true) {
3497    expr = expr->IgnoreParens();
3498    switch (expr->getStmtClass()) {
3499      case Stmt::ArraySubscriptExprClass:
3500        CheckArrayAccess_Check(*this, cast<ArraySubscriptExpr>(expr));
3501        return;
3502      case Stmt::ConditionalOperatorClass: {
3503        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
3504        if (const Expr *lhs = cond->getLHS())
3505          CheckArrayAccess(lhs);
3506        if (const Expr *rhs = cond->getRHS())
3507          CheckArrayAccess(rhs);
3508        return;
3509      }
3510      default:
3511        return;
3512    }
3513  }
3514}
3515
3516//===--- CHECK: Objective-C retain cycles ----------------------------------//
3517
3518namespace {
3519  struct RetainCycleOwner {
3520    RetainCycleOwner() : Variable(0), Indirect(false) {}
3521    VarDecl *Variable;
3522    SourceRange Range;
3523    SourceLocation Loc;
3524    bool Indirect;
3525
3526    void setLocsFrom(Expr *e) {
3527      Loc = e->getExprLoc();
3528      Range = e->getSourceRange();
3529    }
3530  };
3531}
3532
3533/// Consider whether capturing the given variable can possibly lead to
3534/// a retain cycle.
3535static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
3536  // In ARC, it's captured strongly iff the variable has __strong
3537  // lifetime.  In MRR, it's captured strongly if the variable is
3538  // __block and has an appropriate type.
3539  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
3540    return false;
3541
3542  owner.Variable = var;
3543  owner.setLocsFrom(ref);
3544  return true;
3545}
3546
3547static bool findRetainCycleOwner(Expr *e, RetainCycleOwner &owner) {
3548  while (true) {
3549    e = e->IgnoreParens();
3550    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
3551      switch (cast->getCastKind()) {
3552      case CK_BitCast:
3553      case CK_LValueBitCast:
3554      case CK_LValueToRValue:
3555      case CK_ObjCReclaimReturnedObject:
3556        e = cast->getSubExpr();
3557        continue;
3558
3559      case CK_GetObjCProperty: {
3560        // Bail out if this isn't a strong explicit property.
3561        const ObjCPropertyRefExpr *pre = cast->getSubExpr()->getObjCProperty();
3562        if (pre->isImplicitProperty()) return false;
3563        ObjCPropertyDecl *property = pre->getExplicitProperty();
3564        if (!(property->getPropertyAttributes() &
3565              (ObjCPropertyDecl::OBJC_PR_retain |
3566               ObjCPropertyDecl::OBJC_PR_copy |
3567               ObjCPropertyDecl::OBJC_PR_strong)) &&
3568            !(property->getPropertyIvarDecl() &&
3569              property->getPropertyIvarDecl()->getType()
3570                .getObjCLifetime() == Qualifiers::OCL_Strong))
3571          return false;
3572
3573        owner.Indirect = true;
3574        e = const_cast<Expr*>(pre->getBase());
3575        continue;
3576      }
3577
3578      default:
3579        return false;
3580      }
3581    }
3582
3583    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
3584      ObjCIvarDecl *ivar = ref->getDecl();
3585      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
3586        return false;
3587
3588      // Try to find a retain cycle in the base.
3589      if (!findRetainCycleOwner(ref->getBase(), owner))
3590        return false;
3591
3592      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
3593      owner.Indirect = true;
3594      return true;
3595    }
3596
3597    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
3598      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
3599      if (!var) return false;
3600      return considerVariable(var, ref, owner);
3601    }
3602
3603    if (BlockDeclRefExpr *ref = dyn_cast<BlockDeclRefExpr>(e)) {
3604      owner.Variable = ref->getDecl();
3605      owner.setLocsFrom(ref);
3606      return true;
3607    }
3608
3609    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
3610      if (member->isArrow()) return false;
3611
3612      // Don't count this as an indirect ownership.
3613      e = member->getBase();
3614      continue;
3615    }
3616
3617    // Array ivars?
3618
3619    return false;
3620  }
3621}
3622
3623namespace {
3624  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
3625    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
3626      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
3627        Variable(variable), Capturer(0) {}
3628
3629    VarDecl *Variable;
3630    Expr *Capturer;
3631
3632    void VisitDeclRefExpr(DeclRefExpr *ref) {
3633      if (ref->getDecl() == Variable && !Capturer)
3634        Capturer = ref;
3635    }
3636
3637    void VisitBlockDeclRefExpr(BlockDeclRefExpr *ref) {
3638      if (ref->getDecl() == Variable && !Capturer)
3639        Capturer = ref;
3640    }
3641
3642    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
3643      if (Capturer) return;
3644      Visit(ref->getBase());
3645      if (Capturer && ref->isFreeIvar())
3646        Capturer = ref;
3647    }
3648
3649    void VisitBlockExpr(BlockExpr *block) {
3650      // Look inside nested blocks
3651      if (block->getBlockDecl()->capturesVariable(Variable))
3652        Visit(block->getBlockDecl()->getBody());
3653    }
3654  };
3655}
3656
3657/// Check whether the given argument is a block which captures a
3658/// variable.
3659static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
3660  assert(owner.Variable && owner.Loc.isValid());
3661
3662  e = e->IgnoreParenCasts();
3663  BlockExpr *block = dyn_cast<BlockExpr>(e);
3664  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
3665    return 0;
3666
3667  FindCaptureVisitor visitor(S.Context, owner.Variable);
3668  visitor.Visit(block->getBlockDecl()->getBody());
3669  return visitor.Capturer;
3670}
3671
3672static void diagnoseRetainCycle(Sema &S, Expr *capturer,
3673                                RetainCycleOwner &owner) {
3674  assert(capturer);
3675  assert(owner.Variable && owner.Loc.isValid());
3676
3677  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
3678    << owner.Variable << capturer->getSourceRange();
3679  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
3680    << owner.Indirect << owner.Range;
3681}
3682
3683/// Check for a keyword selector that starts with the word 'add' or
3684/// 'set'.
3685static bool isSetterLikeSelector(Selector sel) {
3686  if (sel.isUnarySelector()) return false;
3687
3688  llvm::StringRef str = sel.getNameForSlot(0);
3689  while (!str.empty() && str.front() == '_') str = str.substr(1);
3690  if (str.startswith("set") || str.startswith("add"))
3691    str = str.substr(3);
3692  else
3693    return false;
3694
3695  if (str.empty()) return true;
3696  return !islower(str.front());
3697}
3698
3699/// Check a message send to see if it's likely to cause a retain cycle.
3700void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
3701  // Only check instance methods whose selector looks like a setter.
3702  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
3703    return;
3704
3705  // Try to find a variable that the receiver is strongly owned by.
3706  RetainCycleOwner owner;
3707  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
3708    if (!findRetainCycleOwner(msg->getInstanceReceiver(), owner))
3709      return;
3710  } else {
3711    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
3712    owner.Variable = getCurMethodDecl()->getSelfDecl();
3713    owner.Loc = msg->getSuperLoc();
3714    owner.Range = msg->getSuperLoc();
3715  }
3716
3717  // Check whether the receiver is captured by any of the arguments.
3718  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
3719    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
3720      return diagnoseRetainCycle(*this, capturer, owner);
3721}
3722
3723/// Check a property assign to see if it's likely to cause a retain cycle.
3724void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
3725  RetainCycleOwner owner;
3726  if (!findRetainCycleOwner(receiver, owner))
3727    return;
3728
3729  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
3730    diagnoseRetainCycle(*this, capturer, owner);
3731}
3732
3733bool Sema::checkUnsafeAssigns(SourceLocation Loc,
3734                              QualType LHS, Expr *RHS) {
3735  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
3736  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
3737    return false;
3738  // strip off any implicit cast added to get to the one arc-specific
3739  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
3740    if (cast->getCastKind() == CK_ObjCConsumeObject) {
3741      Diag(Loc, diag::warn_arc_retained_assign)
3742        << (LT == Qualifiers::OCL_ExplicitNone)
3743        << RHS->getSourceRange();
3744      return true;
3745    }
3746    RHS = cast->getSubExpr();
3747  }
3748  return false;
3749}
3750
3751void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
3752                              Expr *LHS, Expr *RHS) {
3753  QualType LHSType = LHS->getType();
3754  if (checkUnsafeAssigns(Loc, LHSType, RHS))
3755    return;
3756  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
3757  // FIXME. Check for other life times.
3758  if (LT != Qualifiers::OCL_None)
3759    return;
3760
3761  if (ObjCPropertyRefExpr *PRE = dyn_cast<ObjCPropertyRefExpr>(LHS)) {
3762    if (PRE->isImplicitProperty())
3763      return;
3764    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
3765    if (!PD)
3766      return;
3767
3768    unsigned Attributes = PD->getPropertyAttributes();
3769    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign)
3770      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
3771        if (cast->getCastKind() == CK_ObjCConsumeObject) {
3772          Diag(Loc, diag::warn_arc_retained_property_assign)
3773          << RHS->getSourceRange();
3774          return;
3775        }
3776        RHS = cast->getSubExpr();
3777      }
3778  }
3779}
3780