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/SemaInternal.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/CharUnits.h"
18#include "clang/AST/DeclCXX.h"
19#include "clang/AST/DeclObjC.h"
20#include "clang/AST/EvaluatedExprVisitor.h"
21#include "clang/AST/Expr.h"
22#include "clang/AST/ExprCXX.h"
23#include "clang/AST/ExprObjC.h"
24#include "clang/AST/StmtCXX.h"
25#include "clang/AST/StmtObjC.h"
26#include "clang/Analysis/Analyses/FormatString.h"
27#include "clang/Basic/CharInfo.h"
28#include "clang/Basic/TargetBuiltins.h"
29#include "clang/Basic/TargetInfo.h"
30#include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
31#include "clang/Sema/Initialization.h"
32#include "clang/Sema/Lookup.h"
33#include "clang/Sema/ScopeInfo.h"
34#include "clang/Sema/Sema.h"
35#include "llvm/ADT/STLExtras.h"
36#include "llvm/ADT/SmallBitVector.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/Support/ConvertUTF.h"
39#include "llvm/Support/raw_ostream.h"
40#include <limits>
41using namespace clang;
42using namespace sema;
43
44SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
45                                                    unsigned ByteNo) const {
46  return SL->getLocationOfByte(ByteNo, getSourceManager(), LangOpts,
47                               Context.getTargetInfo());
48}
49
50/// Checks that a call expression's argument count is the desired number.
51/// This is useful when doing custom type-checking.  Returns true on error.
52static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
53  unsigned argCount = call->getNumArgs();
54  if (argCount == desiredArgCount) return false;
55
56  if (argCount < desiredArgCount)
57    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
58        << 0 /*function call*/ << desiredArgCount << argCount
59        << call->getSourceRange();
60
61  // Highlight all the excess arguments.
62  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
63                    call->getArg(argCount - 1)->getLocEnd());
64
65  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
66    << 0 /*function call*/ << desiredArgCount << argCount
67    << call->getArg(1)->getSourceRange();
68}
69
70/// Check that the first argument to __builtin_annotation is an integer
71/// and the second argument is a non-wide string literal.
72static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
73  if (checkArgCount(S, TheCall, 2))
74    return true;
75
76  // First argument should be an integer.
77  Expr *ValArg = TheCall->getArg(0);
78  QualType Ty = ValArg->getType();
79  if (!Ty->isIntegerType()) {
80    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
81      << ValArg->getSourceRange();
82    return true;
83  }
84
85  // Second argument should be a constant string.
86  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
87  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
88  if (!Literal || !Literal->isAscii()) {
89    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
90      << StrArg->getSourceRange();
91    return true;
92  }
93
94  TheCall->setType(Ty);
95  return false;
96}
97
98/// Check that the argument to __builtin_addressof is a glvalue, and set the
99/// result type to the corresponding pointer type.
100static bool SemaBuiltinAddressof(Sema &S, CallExpr *TheCall) {
101  if (checkArgCount(S, TheCall, 1))
102    return true;
103
104  ExprResult Arg(TheCall->getArg(0));
105  QualType ResultType = S.CheckAddressOfOperand(Arg, TheCall->getLocStart());
106  if (ResultType.isNull())
107    return true;
108
109  TheCall->setArg(0, Arg.get());
110  TheCall->setType(ResultType);
111  return false;
112}
113
114static void SemaBuiltinMemChkCall(Sema &S, FunctionDecl *FDecl,
115		                  CallExpr *TheCall, unsigned SizeIdx,
116                                  unsigned DstSizeIdx) {
117  if (TheCall->getNumArgs() <= SizeIdx ||
118      TheCall->getNumArgs() <= DstSizeIdx)
119    return;
120
121  const Expr *SizeArg = TheCall->getArg(SizeIdx);
122  const Expr *DstSizeArg = TheCall->getArg(DstSizeIdx);
123
124  llvm::APSInt Size, DstSize;
125
126  // find out if both sizes are known at compile time
127  if (!SizeArg->EvaluateAsInt(Size, S.Context) ||
128      !DstSizeArg->EvaluateAsInt(DstSize, S.Context))
129    return;
130
131  if (Size.ule(DstSize))
132    return;
133
134  // confirmed overflow so generate the diagnostic.
135  IdentifierInfo *FnName = FDecl->getIdentifier();
136  SourceLocation SL = TheCall->getLocStart();
137  SourceRange SR = TheCall->getSourceRange();
138
139  S.Diag(SL, diag::warn_memcpy_chk_overflow) << SR << FnName;
140}
141
142static bool SemaBuiltinCallWithStaticChain(Sema &S, CallExpr *BuiltinCall) {
143  if (checkArgCount(S, BuiltinCall, 2))
144    return true;
145
146  SourceLocation BuiltinLoc = BuiltinCall->getLocStart();
147  Expr *Builtin = BuiltinCall->getCallee()->IgnoreImpCasts();
148  Expr *Call = BuiltinCall->getArg(0);
149  Expr *Chain = BuiltinCall->getArg(1);
150
151  if (Call->getStmtClass() != Stmt::CallExprClass) {
152    S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_not_call)
153        << Call->getSourceRange();
154    return true;
155  }
156
157  auto CE = cast<CallExpr>(Call);
158  if (CE->getCallee()->getType()->isBlockPointerType()) {
159    S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_block_call)
160        << Call->getSourceRange();
161    return true;
162  }
163
164  const Decl *TargetDecl = CE->getCalleeDecl();
165  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl))
166    if (FD->getBuiltinID()) {
167      S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_builtin_call)
168          << Call->getSourceRange();
169      return true;
170    }
171
172  if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens())) {
173    S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_pdtor_call)
174        << Call->getSourceRange();
175    return true;
176  }
177
178  ExprResult ChainResult = S.UsualUnaryConversions(Chain);
179  if (ChainResult.isInvalid())
180    return true;
181  if (!ChainResult.get()->getType()->isPointerType()) {
182    S.Diag(BuiltinLoc, diag::err_second_argument_to_cwsc_not_pointer)
183        << Chain->getSourceRange();
184    return true;
185  }
186
187  QualType ReturnTy = CE->getCallReturnType(S.Context);
188  QualType ArgTys[2] = { ReturnTy, ChainResult.get()->getType() };
189  QualType BuiltinTy = S.Context.getFunctionType(
190      ReturnTy, ArgTys, FunctionProtoType::ExtProtoInfo());
191  QualType BuiltinPtrTy = S.Context.getPointerType(BuiltinTy);
192
193  Builtin =
194      S.ImpCastExprToType(Builtin, BuiltinPtrTy, CK_BuiltinFnToFnPtr).get();
195
196  BuiltinCall->setType(CE->getType());
197  BuiltinCall->setValueKind(CE->getValueKind());
198  BuiltinCall->setObjectKind(CE->getObjectKind());
199  BuiltinCall->setCallee(Builtin);
200  BuiltinCall->setArg(1, ChainResult.get());
201
202  return false;
203}
204
205static bool SemaBuiltinSEHScopeCheck(Sema &SemaRef, CallExpr *TheCall,
206                                     Scope::ScopeFlags NeededScopeFlags,
207                                     unsigned DiagID) {
208  // Scopes aren't available during instantiation. Fortunately, builtin
209  // functions cannot be template args so they cannot be formed through template
210  // instantiation. Therefore checking once during the parse is sufficient.
211  if (!SemaRef.ActiveTemplateInstantiations.empty())
212    return false;
213
214  Scope *S = SemaRef.getCurScope();
215  while (S && !S->isSEHExceptScope())
216    S = S->getParent();
217  if (!S || !(S->getFlags() & NeededScopeFlags)) {
218    auto *DRE = cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
219    SemaRef.Diag(TheCall->getExprLoc(), DiagID)
220        << DRE->getDecl()->getIdentifier();
221    return true;
222  }
223
224  return false;
225}
226
227ExprResult
228Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
229                               CallExpr *TheCall) {
230  ExprResult TheCallResult(TheCall);
231
232  // Find out if any arguments are required to be integer constant expressions.
233  unsigned ICEArguments = 0;
234  ASTContext::GetBuiltinTypeError Error;
235  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
236  if (Error != ASTContext::GE_None)
237    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
238
239  // If any arguments are required to be ICE's, check and diagnose.
240  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
241    // Skip arguments not required to be ICE's.
242    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
243
244    llvm::APSInt Result;
245    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
246      return true;
247    ICEArguments &= ~(1 << ArgNo);
248  }
249
250  switch (BuiltinID) {
251  case Builtin::BI__builtin___CFStringMakeConstantString:
252    assert(TheCall->getNumArgs() == 1 &&
253           "Wrong # arguments to builtin CFStringMakeConstantString");
254    if (CheckObjCString(TheCall->getArg(0)))
255      return ExprError();
256    break;
257  case Builtin::BI__builtin_stdarg_start:
258  case Builtin::BI__builtin_va_start:
259    if (SemaBuiltinVAStart(TheCall))
260      return ExprError();
261    break;
262  case Builtin::BI__va_start: {
263    switch (Context.getTargetInfo().getTriple().getArch()) {
264    case llvm::Triple::arm:
265    case llvm::Triple::thumb:
266      if (SemaBuiltinVAStartARM(TheCall))
267        return ExprError();
268      break;
269    default:
270      if (SemaBuiltinVAStart(TheCall))
271        return ExprError();
272      break;
273    }
274    break;
275  }
276  case Builtin::BI__builtin_isgreater:
277  case Builtin::BI__builtin_isgreaterequal:
278  case Builtin::BI__builtin_isless:
279  case Builtin::BI__builtin_islessequal:
280  case Builtin::BI__builtin_islessgreater:
281  case Builtin::BI__builtin_isunordered:
282    if (SemaBuiltinUnorderedCompare(TheCall))
283      return ExprError();
284    break;
285  case Builtin::BI__builtin_fpclassify:
286    if (SemaBuiltinFPClassification(TheCall, 6))
287      return ExprError();
288    break;
289  case Builtin::BI__builtin_isfinite:
290  case Builtin::BI__builtin_isinf:
291  case Builtin::BI__builtin_isinf_sign:
292  case Builtin::BI__builtin_isnan:
293  case Builtin::BI__builtin_isnormal:
294    if (SemaBuiltinFPClassification(TheCall, 1))
295      return ExprError();
296    break;
297  case Builtin::BI__builtin_shufflevector:
298    return SemaBuiltinShuffleVector(TheCall);
299    // TheCall will be freed by the smart pointer here, but that's fine, since
300    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
301  case Builtin::BI__builtin_prefetch:
302    if (SemaBuiltinPrefetch(TheCall))
303      return ExprError();
304    break;
305  case Builtin::BI__assume:
306  case Builtin::BI__builtin_assume:
307    if (SemaBuiltinAssume(TheCall))
308      return ExprError();
309    break;
310  case Builtin::BI__builtin_assume_aligned:
311    if (SemaBuiltinAssumeAligned(TheCall))
312      return ExprError();
313    break;
314  case Builtin::BI__builtin_object_size:
315    if (SemaBuiltinConstantArgRange(TheCall, 1, 0, 3))
316      return ExprError();
317    break;
318  case Builtin::BI__builtin_longjmp:
319    if (SemaBuiltinLongjmp(TheCall))
320      return ExprError();
321    break;
322  case Builtin::BI__builtin_setjmp:
323    if (SemaBuiltinSetjmp(TheCall))
324      return ExprError();
325    break;
326  case Builtin::BI_setjmp:
327  case Builtin::BI_setjmpex:
328    if (checkArgCount(*this, TheCall, 1))
329      return true;
330    break;
331
332  case Builtin::BI__builtin_classify_type:
333    if (checkArgCount(*this, TheCall, 1)) return true;
334    TheCall->setType(Context.IntTy);
335    break;
336  case Builtin::BI__builtin_constant_p:
337    if (checkArgCount(*this, TheCall, 1)) return true;
338    TheCall->setType(Context.IntTy);
339    break;
340  case Builtin::BI__sync_fetch_and_add:
341  case Builtin::BI__sync_fetch_and_add_1:
342  case Builtin::BI__sync_fetch_and_add_2:
343  case Builtin::BI__sync_fetch_and_add_4:
344  case Builtin::BI__sync_fetch_and_add_8:
345  case Builtin::BI__sync_fetch_and_add_16:
346  case Builtin::BI__sync_fetch_and_sub:
347  case Builtin::BI__sync_fetch_and_sub_1:
348  case Builtin::BI__sync_fetch_and_sub_2:
349  case Builtin::BI__sync_fetch_and_sub_4:
350  case Builtin::BI__sync_fetch_and_sub_8:
351  case Builtin::BI__sync_fetch_and_sub_16:
352  case Builtin::BI__sync_fetch_and_or:
353  case Builtin::BI__sync_fetch_and_or_1:
354  case Builtin::BI__sync_fetch_and_or_2:
355  case Builtin::BI__sync_fetch_and_or_4:
356  case Builtin::BI__sync_fetch_and_or_8:
357  case Builtin::BI__sync_fetch_and_or_16:
358  case Builtin::BI__sync_fetch_and_and:
359  case Builtin::BI__sync_fetch_and_and_1:
360  case Builtin::BI__sync_fetch_and_and_2:
361  case Builtin::BI__sync_fetch_and_and_4:
362  case Builtin::BI__sync_fetch_and_and_8:
363  case Builtin::BI__sync_fetch_and_and_16:
364  case Builtin::BI__sync_fetch_and_xor:
365  case Builtin::BI__sync_fetch_and_xor_1:
366  case Builtin::BI__sync_fetch_and_xor_2:
367  case Builtin::BI__sync_fetch_and_xor_4:
368  case Builtin::BI__sync_fetch_and_xor_8:
369  case Builtin::BI__sync_fetch_and_xor_16:
370  case Builtin::BI__sync_fetch_and_nand:
371  case Builtin::BI__sync_fetch_and_nand_1:
372  case Builtin::BI__sync_fetch_and_nand_2:
373  case Builtin::BI__sync_fetch_and_nand_4:
374  case Builtin::BI__sync_fetch_and_nand_8:
375  case Builtin::BI__sync_fetch_and_nand_16:
376  case Builtin::BI__sync_add_and_fetch:
377  case Builtin::BI__sync_add_and_fetch_1:
378  case Builtin::BI__sync_add_and_fetch_2:
379  case Builtin::BI__sync_add_and_fetch_4:
380  case Builtin::BI__sync_add_and_fetch_8:
381  case Builtin::BI__sync_add_and_fetch_16:
382  case Builtin::BI__sync_sub_and_fetch:
383  case Builtin::BI__sync_sub_and_fetch_1:
384  case Builtin::BI__sync_sub_and_fetch_2:
385  case Builtin::BI__sync_sub_and_fetch_4:
386  case Builtin::BI__sync_sub_and_fetch_8:
387  case Builtin::BI__sync_sub_and_fetch_16:
388  case Builtin::BI__sync_and_and_fetch:
389  case Builtin::BI__sync_and_and_fetch_1:
390  case Builtin::BI__sync_and_and_fetch_2:
391  case Builtin::BI__sync_and_and_fetch_4:
392  case Builtin::BI__sync_and_and_fetch_8:
393  case Builtin::BI__sync_and_and_fetch_16:
394  case Builtin::BI__sync_or_and_fetch:
395  case Builtin::BI__sync_or_and_fetch_1:
396  case Builtin::BI__sync_or_and_fetch_2:
397  case Builtin::BI__sync_or_and_fetch_4:
398  case Builtin::BI__sync_or_and_fetch_8:
399  case Builtin::BI__sync_or_and_fetch_16:
400  case Builtin::BI__sync_xor_and_fetch:
401  case Builtin::BI__sync_xor_and_fetch_1:
402  case Builtin::BI__sync_xor_and_fetch_2:
403  case Builtin::BI__sync_xor_and_fetch_4:
404  case Builtin::BI__sync_xor_and_fetch_8:
405  case Builtin::BI__sync_xor_and_fetch_16:
406  case Builtin::BI__sync_nand_and_fetch:
407  case Builtin::BI__sync_nand_and_fetch_1:
408  case Builtin::BI__sync_nand_and_fetch_2:
409  case Builtin::BI__sync_nand_and_fetch_4:
410  case Builtin::BI__sync_nand_and_fetch_8:
411  case Builtin::BI__sync_nand_and_fetch_16:
412  case Builtin::BI__sync_val_compare_and_swap:
413  case Builtin::BI__sync_val_compare_and_swap_1:
414  case Builtin::BI__sync_val_compare_and_swap_2:
415  case Builtin::BI__sync_val_compare_and_swap_4:
416  case Builtin::BI__sync_val_compare_and_swap_8:
417  case Builtin::BI__sync_val_compare_and_swap_16:
418  case Builtin::BI__sync_bool_compare_and_swap:
419  case Builtin::BI__sync_bool_compare_and_swap_1:
420  case Builtin::BI__sync_bool_compare_and_swap_2:
421  case Builtin::BI__sync_bool_compare_and_swap_4:
422  case Builtin::BI__sync_bool_compare_and_swap_8:
423  case Builtin::BI__sync_bool_compare_and_swap_16:
424  case Builtin::BI__sync_lock_test_and_set:
425  case Builtin::BI__sync_lock_test_and_set_1:
426  case Builtin::BI__sync_lock_test_and_set_2:
427  case Builtin::BI__sync_lock_test_and_set_4:
428  case Builtin::BI__sync_lock_test_and_set_8:
429  case Builtin::BI__sync_lock_test_and_set_16:
430  case Builtin::BI__sync_lock_release:
431  case Builtin::BI__sync_lock_release_1:
432  case Builtin::BI__sync_lock_release_2:
433  case Builtin::BI__sync_lock_release_4:
434  case Builtin::BI__sync_lock_release_8:
435  case Builtin::BI__sync_lock_release_16:
436  case Builtin::BI__sync_swap:
437  case Builtin::BI__sync_swap_1:
438  case Builtin::BI__sync_swap_2:
439  case Builtin::BI__sync_swap_4:
440  case Builtin::BI__sync_swap_8:
441  case Builtin::BI__sync_swap_16:
442    return SemaBuiltinAtomicOverloaded(TheCallResult);
443#define BUILTIN(ID, TYPE, ATTRS)
444#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
445  case Builtin::BI##ID: \
446    return SemaAtomicOpsOverloaded(TheCallResult, AtomicExpr::AO##ID);
447#include "clang/Basic/Builtins.def"
448  case Builtin::BI__builtin_annotation:
449    if (SemaBuiltinAnnotation(*this, TheCall))
450      return ExprError();
451    break;
452  case Builtin::BI__builtin_addressof:
453    if (SemaBuiltinAddressof(*this, TheCall))
454      return ExprError();
455    break;
456  case Builtin::BI__builtin_operator_new:
457  case Builtin::BI__builtin_operator_delete:
458    if (!getLangOpts().CPlusPlus) {
459      Diag(TheCall->getExprLoc(), diag::err_builtin_requires_language)
460        << (BuiltinID == Builtin::BI__builtin_operator_new
461                ? "__builtin_operator_new"
462                : "__builtin_operator_delete")
463        << "C++";
464      return ExprError();
465    }
466    // CodeGen assumes it can find the global new and delete to call,
467    // so ensure that they are declared.
468    DeclareGlobalNewDelete();
469    break;
470
471  // check secure string manipulation functions where overflows
472  // are detectable at compile time
473  case Builtin::BI__builtin___memcpy_chk:
474  case Builtin::BI__builtin___memmove_chk:
475  case Builtin::BI__builtin___memset_chk:
476  case Builtin::BI__builtin___strlcat_chk:
477  case Builtin::BI__builtin___strlcpy_chk:
478  case Builtin::BI__builtin___strncat_chk:
479  case Builtin::BI__builtin___strncpy_chk:
480  case Builtin::BI__builtin___stpncpy_chk:
481    SemaBuiltinMemChkCall(*this, FDecl, TheCall, 2, 3);
482    break;
483  case Builtin::BI__builtin___memccpy_chk:
484    SemaBuiltinMemChkCall(*this, FDecl, TheCall, 3, 4);
485    break;
486  case Builtin::BI__builtin___snprintf_chk:
487  case Builtin::BI__builtin___vsnprintf_chk:
488    SemaBuiltinMemChkCall(*this, FDecl, TheCall, 1, 3);
489    break;
490
491  case Builtin::BI__builtin_call_with_static_chain:
492    if (SemaBuiltinCallWithStaticChain(*this, TheCall))
493      return ExprError();
494    break;
495
496  case Builtin::BI__exception_code:
497  case Builtin::BI_exception_code: {
498    if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHExceptScope,
499                                 diag::err_seh___except_block))
500      return ExprError();
501    break;
502  }
503  case Builtin::BI__exception_info:
504  case Builtin::BI_exception_info: {
505    if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHFilterScope,
506                                 diag::err_seh___except_filter))
507      return ExprError();
508    break;
509  }
510
511  case Builtin::BI__GetExceptionInfo:
512    if (checkArgCount(*this, TheCall, 1))
513      return ExprError();
514
515    if (CheckCXXThrowOperand(
516            TheCall->getLocStart(),
517            Context.getExceptionObjectType(FDecl->getParamDecl(0)->getType()),
518            TheCall))
519      return ExprError();
520
521    TheCall->setType(Context.VoidPtrTy);
522    break;
523
524  }
525
526  // Since the target specific builtins for each arch overlap, only check those
527  // of the arch we are compiling for.
528  if (BuiltinID >= Builtin::FirstTSBuiltin) {
529    switch (Context.getTargetInfo().getTriple().getArch()) {
530      case llvm::Triple::arm:
531      case llvm::Triple::armeb:
532      case llvm::Triple::thumb:
533      case llvm::Triple::thumbeb:
534        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
535          return ExprError();
536        break;
537      case llvm::Triple::aarch64:
538      case llvm::Triple::aarch64_be:
539        if (CheckAArch64BuiltinFunctionCall(BuiltinID, TheCall))
540          return ExprError();
541        break;
542      case llvm::Triple::mips:
543      case llvm::Triple::mipsel:
544      case llvm::Triple::mips64:
545      case llvm::Triple::mips64el:
546        if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
547          return ExprError();
548        break;
549      case llvm::Triple::systemz:
550        if (CheckSystemZBuiltinFunctionCall(BuiltinID, TheCall))
551          return ExprError();
552        break;
553      case llvm::Triple::x86:
554      case llvm::Triple::x86_64:
555        if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall))
556          return ExprError();
557        break;
558      case llvm::Triple::ppc:
559      case llvm::Triple::ppc64:
560      case llvm::Triple::ppc64le:
561        if (CheckPPCBuiltinFunctionCall(BuiltinID, TheCall))
562          return ExprError();
563        break;
564      default:
565        break;
566    }
567  }
568
569  return TheCallResult;
570}
571
572// Get the valid immediate range for the specified NEON type code.
573static unsigned RFT(unsigned t, bool shift = false, bool ForceQuad = false) {
574  NeonTypeFlags Type(t);
575  int IsQuad = ForceQuad ? true : Type.isQuad();
576  switch (Type.getEltType()) {
577  case NeonTypeFlags::Int8:
578  case NeonTypeFlags::Poly8:
579    return shift ? 7 : (8 << IsQuad) - 1;
580  case NeonTypeFlags::Int16:
581  case NeonTypeFlags::Poly16:
582    return shift ? 15 : (4 << IsQuad) - 1;
583  case NeonTypeFlags::Int32:
584    return shift ? 31 : (2 << IsQuad) - 1;
585  case NeonTypeFlags::Int64:
586  case NeonTypeFlags::Poly64:
587    return shift ? 63 : (1 << IsQuad) - 1;
588  case NeonTypeFlags::Poly128:
589    return shift ? 127 : (1 << IsQuad) - 1;
590  case NeonTypeFlags::Float16:
591    assert(!shift && "cannot shift float types!");
592    return (4 << IsQuad) - 1;
593  case NeonTypeFlags::Float32:
594    assert(!shift && "cannot shift float types!");
595    return (2 << IsQuad) - 1;
596  case NeonTypeFlags::Float64:
597    assert(!shift && "cannot shift float types!");
598    return (1 << IsQuad) - 1;
599  }
600  llvm_unreachable("Invalid NeonTypeFlag!");
601}
602
603/// getNeonEltType - Return the QualType corresponding to the elements of
604/// the vector type specified by the NeonTypeFlags.  This is used to check
605/// the pointer arguments for Neon load/store intrinsics.
606static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context,
607                               bool IsPolyUnsigned, bool IsInt64Long) {
608  switch (Flags.getEltType()) {
609  case NeonTypeFlags::Int8:
610    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
611  case NeonTypeFlags::Int16:
612    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
613  case NeonTypeFlags::Int32:
614    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
615  case NeonTypeFlags::Int64:
616    if (IsInt64Long)
617      return Flags.isUnsigned() ? Context.UnsignedLongTy : Context.LongTy;
618    else
619      return Flags.isUnsigned() ? Context.UnsignedLongLongTy
620                                : Context.LongLongTy;
621  case NeonTypeFlags::Poly8:
622    return IsPolyUnsigned ? Context.UnsignedCharTy : Context.SignedCharTy;
623  case NeonTypeFlags::Poly16:
624    return IsPolyUnsigned ? Context.UnsignedShortTy : Context.ShortTy;
625  case NeonTypeFlags::Poly64:
626    return Context.UnsignedLongTy;
627  case NeonTypeFlags::Poly128:
628    break;
629  case NeonTypeFlags::Float16:
630    return Context.HalfTy;
631  case NeonTypeFlags::Float32:
632    return Context.FloatTy;
633  case NeonTypeFlags::Float64:
634    return Context.DoubleTy;
635  }
636  llvm_unreachable("Invalid NeonTypeFlag!");
637}
638
639bool Sema::CheckNeonBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
640  llvm::APSInt Result;
641  uint64_t mask = 0;
642  unsigned TV = 0;
643  int PtrArgNum = -1;
644  bool HasConstPtr = false;
645  switch (BuiltinID) {
646#define GET_NEON_OVERLOAD_CHECK
647#include "clang/Basic/arm_neon.inc"
648#undef GET_NEON_OVERLOAD_CHECK
649  }
650
651  // For NEON intrinsics which are overloaded on vector element type, validate
652  // the immediate which specifies which variant to emit.
653  unsigned ImmArg = TheCall->getNumArgs()-1;
654  if (mask) {
655    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
656      return true;
657
658    TV = Result.getLimitedValue(64);
659    if ((TV > 63) || (mask & (1ULL << TV)) == 0)
660      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
661        << TheCall->getArg(ImmArg)->getSourceRange();
662  }
663
664  if (PtrArgNum >= 0) {
665    // Check that pointer arguments have the specified type.
666    Expr *Arg = TheCall->getArg(PtrArgNum);
667    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
668      Arg = ICE->getSubExpr();
669    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
670    QualType RHSTy = RHS.get()->getType();
671
672    llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
673    bool IsPolyUnsigned = Arch == llvm::Triple::aarch64;
674    bool IsInt64Long =
675        Context.getTargetInfo().getInt64Type() == TargetInfo::SignedLong;
676    QualType EltTy =
677        getNeonEltType(NeonTypeFlags(TV), Context, IsPolyUnsigned, IsInt64Long);
678    if (HasConstPtr)
679      EltTy = EltTy.withConst();
680    QualType LHSTy = Context.getPointerType(EltTy);
681    AssignConvertType ConvTy;
682    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
683    if (RHS.isInvalid())
684      return true;
685    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
686                                 RHS.get(), AA_Assigning))
687      return true;
688  }
689
690  // For NEON intrinsics which take an immediate value as part of the
691  // instruction, range check them here.
692  unsigned i = 0, l = 0, u = 0;
693  switch (BuiltinID) {
694  default:
695    return false;
696#define GET_NEON_IMMEDIATE_CHECK
697#include "clang/Basic/arm_neon.inc"
698#undef GET_NEON_IMMEDIATE_CHECK
699  }
700
701  return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
702}
703
704bool Sema::CheckARMBuiltinExclusiveCall(unsigned BuiltinID, CallExpr *TheCall,
705                                        unsigned MaxWidth) {
706  assert((BuiltinID == ARM::BI__builtin_arm_ldrex ||
707          BuiltinID == ARM::BI__builtin_arm_ldaex ||
708          BuiltinID == ARM::BI__builtin_arm_strex ||
709          BuiltinID == ARM::BI__builtin_arm_stlex ||
710          BuiltinID == AArch64::BI__builtin_arm_ldrex ||
711          BuiltinID == AArch64::BI__builtin_arm_ldaex ||
712          BuiltinID == AArch64::BI__builtin_arm_strex ||
713          BuiltinID == AArch64::BI__builtin_arm_stlex) &&
714         "unexpected ARM builtin");
715  bool IsLdrex = BuiltinID == ARM::BI__builtin_arm_ldrex ||
716                 BuiltinID == ARM::BI__builtin_arm_ldaex ||
717                 BuiltinID == AArch64::BI__builtin_arm_ldrex ||
718                 BuiltinID == AArch64::BI__builtin_arm_ldaex;
719
720  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
721
722  // Ensure that we have the proper number of arguments.
723  if (checkArgCount(*this, TheCall, IsLdrex ? 1 : 2))
724    return true;
725
726  // Inspect the pointer argument of the atomic builtin.  This should always be
727  // a pointer type, whose element is an integral scalar or pointer type.
728  // Because it is a pointer type, we don't have to worry about any implicit
729  // casts here.
730  Expr *PointerArg = TheCall->getArg(IsLdrex ? 0 : 1);
731  ExprResult PointerArgRes = DefaultFunctionArrayLvalueConversion(PointerArg);
732  if (PointerArgRes.isInvalid())
733    return true;
734  PointerArg = PointerArgRes.get();
735
736  const PointerType *pointerType = PointerArg->getType()->getAs<PointerType>();
737  if (!pointerType) {
738    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
739      << PointerArg->getType() << PointerArg->getSourceRange();
740    return true;
741  }
742
743  // ldrex takes a "const volatile T*" and strex takes a "volatile T*". Our next
744  // task is to insert the appropriate casts into the AST. First work out just
745  // what the appropriate type is.
746  QualType ValType = pointerType->getPointeeType();
747  QualType AddrType = ValType.getUnqualifiedType().withVolatile();
748  if (IsLdrex)
749    AddrType.addConst();
750
751  // Issue a warning if the cast is dodgy.
752  CastKind CastNeeded = CK_NoOp;
753  if (!AddrType.isAtLeastAsQualifiedAs(ValType)) {
754    CastNeeded = CK_BitCast;
755    Diag(DRE->getLocStart(), diag::ext_typecheck_convert_discards_qualifiers)
756      << PointerArg->getType()
757      << Context.getPointerType(AddrType)
758      << AA_Passing << PointerArg->getSourceRange();
759  }
760
761  // Finally, do the cast and replace the argument with the corrected version.
762  AddrType = Context.getPointerType(AddrType);
763  PointerArgRes = ImpCastExprToType(PointerArg, AddrType, CastNeeded);
764  if (PointerArgRes.isInvalid())
765    return true;
766  PointerArg = PointerArgRes.get();
767
768  TheCall->setArg(IsLdrex ? 0 : 1, PointerArg);
769
770  // In general, we allow ints, floats and pointers to be loaded and stored.
771  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
772      !ValType->isBlockPointerType() && !ValType->isFloatingType()) {
773    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intfltptr)
774      << PointerArg->getType() << PointerArg->getSourceRange();
775    return true;
776  }
777
778  // But ARM doesn't have instructions to deal with 128-bit versions.
779  if (Context.getTypeSize(ValType) > MaxWidth) {
780    assert(MaxWidth == 64 && "Diagnostic unexpectedly inaccurate");
781    Diag(DRE->getLocStart(), diag::err_atomic_exclusive_builtin_pointer_size)
782      << PointerArg->getType() << PointerArg->getSourceRange();
783    return true;
784  }
785
786  switch (ValType.getObjCLifetime()) {
787  case Qualifiers::OCL_None:
788  case Qualifiers::OCL_ExplicitNone:
789    // okay
790    break;
791
792  case Qualifiers::OCL_Weak:
793  case Qualifiers::OCL_Strong:
794  case Qualifiers::OCL_Autoreleasing:
795    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
796      << ValType << PointerArg->getSourceRange();
797    return true;
798  }
799
800
801  if (IsLdrex) {
802    TheCall->setType(ValType);
803    return false;
804  }
805
806  // Initialize the argument to be stored.
807  ExprResult ValArg = TheCall->getArg(0);
808  InitializedEntity Entity = InitializedEntity::InitializeParameter(
809      Context, ValType, /*consume*/ false);
810  ValArg = PerformCopyInitialization(Entity, SourceLocation(), ValArg);
811  if (ValArg.isInvalid())
812    return true;
813  TheCall->setArg(0, ValArg.get());
814
815  // __builtin_arm_strex always returns an int. It's marked as such in the .def,
816  // but the custom checker bypasses all default analysis.
817  TheCall->setType(Context.IntTy);
818  return false;
819}
820
821bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
822  llvm::APSInt Result;
823
824  if (BuiltinID == ARM::BI__builtin_arm_ldrex ||
825      BuiltinID == ARM::BI__builtin_arm_ldaex ||
826      BuiltinID == ARM::BI__builtin_arm_strex ||
827      BuiltinID == ARM::BI__builtin_arm_stlex) {
828    return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 64);
829  }
830
831  if (BuiltinID == ARM::BI__builtin_arm_prefetch) {
832    return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
833      SemaBuiltinConstantArgRange(TheCall, 2, 0, 1);
834  }
835
836  if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
837    return true;
838
839  // For intrinsics which take an immediate value as part of the instruction,
840  // range check them here.
841  unsigned i = 0, l = 0, u = 0;
842  switch (BuiltinID) {
843  default: return false;
844  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
845  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
846  case ARM::BI__builtin_arm_vcvtr_f:
847  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
848  case ARM::BI__builtin_arm_dmb:
849  case ARM::BI__builtin_arm_dsb:
850  case ARM::BI__builtin_arm_isb:
851  case ARM::BI__builtin_arm_dbg: l = 0; u = 15; break;
852  }
853
854  // FIXME: VFP Intrinsics should error if VFP not present.
855  return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
856}
857
858bool Sema::CheckAArch64BuiltinFunctionCall(unsigned BuiltinID,
859                                         CallExpr *TheCall) {
860  llvm::APSInt Result;
861
862  if (BuiltinID == AArch64::BI__builtin_arm_ldrex ||
863      BuiltinID == AArch64::BI__builtin_arm_ldaex ||
864      BuiltinID == AArch64::BI__builtin_arm_strex ||
865      BuiltinID == AArch64::BI__builtin_arm_stlex) {
866    return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 128);
867  }
868
869  if (BuiltinID == AArch64::BI__builtin_arm_prefetch) {
870    return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
871      SemaBuiltinConstantArgRange(TheCall, 2, 0, 2) ||
872      SemaBuiltinConstantArgRange(TheCall, 3, 0, 1) ||
873      SemaBuiltinConstantArgRange(TheCall, 4, 0, 1);
874  }
875
876  if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
877    return true;
878
879  // For intrinsics which take an immediate value as part of the instruction,
880  // range check them here.
881  unsigned i = 0, l = 0, u = 0;
882  switch (BuiltinID) {
883  default: return false;
884  case AArch64::BI__builtin_arm_dmb:
885  case AArch64::BI__builtin_arm_dsb:
886  case AArch64::BI__builtin_arm_isb: l = 0; u = 15; break;
887  }
888
889  return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
890}
891
892bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
893  unsigned i = 0, l = 0, u = 0;
894  switch (BuiltinID) {
895  default: return false;
896  case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
897  case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
898  case Mips::BI__builtin_mips_append: i = 2; l = 0; u = 31; break;
899  case Mips::BI__builtin_mips_balign: i = 2; l = 0; u = 3; break;
900  case Mips::BI__builtin_mips_precr_sra_ph_w: i = 2; l = 0; u = 31; break;
901  case Mips::BI__builtin_mips_precr_sra_r_ph_w: i = 2; l = 0; u = 31; break;
902  case Mips::BI__builtin_mips_prepend: i = 2; l = 0; u = 31; break;
903  }
904
905  return SemaBuiltinConstantArgRange(TheCall, i, l, u);
906}
907
908bool Sema::CheckPPCBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
909  unsigned i = 0, l = 0, u = 0;
910  bool Is64BitBltin = BuiltinID == PPC::BI__builtin_divde ||
911                      BuiltinID == PPC::BI__builtin_divdeu ||
912                      BuiltinID == PPC::BI__builtin_bpermd;
913  bool IsTarget64Bit = Context.getTargetInfo()
914                              .getTypeWidth(Context
915                                            .getTargetInfo()
916                                            .getIntPtrType()) == 64;
917  bool IsBltinExtDiv = BuiltinID == PPC::BI__builtin_divwe ||
918                       BuiltinID == PPC::BI__builtin_divweu ||
919                       BuiltinID == PPC::BI__builtin_divde ||
920                       BuiltinID == PPC::BI__builtin_divdeu;
921
922  if (Is64BitBltin && !IsTarget64Bit)
923      return Diag(TheCall->getLocStart(), diag::err_64_bit_builtin_32_bit_tgt)
924             << TheCall->getSourceRange();
925
926  if ((IsBltinExtDiv && !Context.getTargetInfo().hasFeature("extdiv")) ||
927      (BuiltinID == PPC::BI__builtin_bpermd &&
928       !Context.getTargetInfo().hasFeature("bpermd")))
929    return Diag(TheCall->getLocStart(), diag::err_ppc_builtin_only_on_pwr7)
930           << TheCall->getSourceRange();
931
932  switch (BuiltinID) {
933  default: return false;
934  case PPC::BI__builtin_altivec_crypto_vshasigmaw:
935  case PPC::BI__builtin_altivec_crypto_vshasigmad:
936    return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
937           SemaBuiltinConstantArgRange(TheCall, 2, 0, 15);
938  case PPC::BI__builtin_tbegin:
939  case PPC::BI__builtin_tend: i = 0; l = 0; u = 1; break;
940  case PPC::BI__builtin_tsr: i = 0; l = 0; u = 7; break;
941  case PPC::BI__builtin_tabortwc:
942  case PPC::BI__builtin_tabortdc: i = 0; l = 0; u = 31; break;
943  case PPC::BI__builtin_tabortwci:
944  case PPC::BI__builtin_tabortdci:
945    return SemaBuiltinConstantArgRange(TheCall, 0, 0, 31) ||
946           SemaBuiltinConstantArgRange(TheCall, 2, 0, 31);
947  }
948  return SemaBuiltinConstantArgRange(TheCall, i, l, u);
949}
950
951bool Sema::CheckSystemZBuiltinFunctionCall(unsigned BuiltinID,
952                                           CallExpr *TheCall) {
953  if (BuiltinID == SystemZ::BI__builtin_tabort) {
954    Expr *Arg = TheCall->getArg(0);
955    llvm::APSInt AbortCode(32);
956    if (Arg->isIntegerConstantExpr(AbortCode, Context) &&
957        AbortCode.getSExtValue() >= 0 && AbortCode.getSExtValue() < 256)
958      return Diag(Arg->getLocStart(), diag::err_systemz_invalid_tabort_code)
959             << Arg->getSourceRange();
960  }
961
962  return false;
963}
964
965bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
966  unsigned i = 0, l = 0, u = 0;
967  switch (BuiltinID) {
968  default: return false;
969  case X86::BI_mm_prefetch: i = 1; l = 0; u = 3; break;
970  case X86::BI__builtin_ia32_sha1rnds4: i = 2, l = 0; u = 3; break;
971  case X86::BI__builtin_ia32_vpermil2pd:
972  case X86::BI__builtin_ia32_vpermil2pd256:
973  case X86::BI__builtin_ia32_vpermil2ps:
974  case X86::BI__builtin_ia32_vpermil2ps256: i = 3, l = 0; u = 3; break;
975  case X86::BI__builtin_ia32_cmpb128_mask:
976  case X86::BI__builtin_ia32_cmpw128_mask:
977  case X86::BI__builtin_ia32_cmpd128_mask:
978  case X86::BI__builtin_ia32_cmpq128_mask:
979  case X86::BI__builtin_ia32_cmpb256_mask:
980  case X86::BI__builtin_ia32_cmpw256_mask:
981  case X86::BI__builtin_ia32_cmpd256_mask:
982  case X86::BI__builtin_ia32_cmpq256_mask:
983  case X86::BI__builtin_ia32_cmpb512_mask:
984  case X86::BI__builtin_ia32_cmpw512_mask:
985  case X86::BI__builtin_ia32_cmpd512_mask:
986  case X86::BI__builtin_ia32_cmpq512_mask:
987  case X86::BI__builtin_ia32_ucmpb128_mask:
988  case X86::BI__builtin_ia32_ucmpw128_mask:
989  case X86::BI__builtin_ia32_ucmpd128_mask:
990  case X86::BI__builtin_ia32_ucmpq128_mask:
991  case X86::BI__builtin_ia32_ucmpb256_mask:
992  case X86::BI__builtin_ia32_ucmpw256_mask:
993  case X86::BI__builtin_ia32_ucmpd256_mask:
994  case X86::BI__builtin_ia32_ucmpq256_mask:
995  case X86::BI__builtin_ia32_ucmpb512_mask:
996  case X86::BI__builtin_ia32_ucmpw512_mask:
997  case X86::BI__builtin_ia32_ucmpd512_mask:
998  case X86::BI__builtin_ia32_ucmpq512_mask: i = 2; l = 0; u = 7; break;
999  case X86::BI__builtin_ia32_roundps:
1000  case X86::BI__builtin_ia32_roundpd:
1001  case X86::BI__builtin_ia32_roundps256:
1002  case X86::BI__builtin_ia32_roundpd256: i = 1, l = 0; u = 15; break;
1003  case X86::BI__builtin_ia32_roundss:
1004  case X86::BI__builtin_ia32_roundsd: i = 2, l = 0; u = 15; break;
1005  case X86::BI__builtin_ia32_cmpps:
1006  case X86::BI__builtin_ia32_cmpss:
1007  case X86::BI__builtin_ia32_cmppd:
1008  case X86::BI__builtin_ia32_cmpsd:
1009  case X86::BI__builtin_ia32_cmpps256:
1010  case X86::BI__builtin_ia32_cmppd256:
1011  case X86::BI__builtin_ia32_cmpps512_mask:
1012  case X86::BI__builtin_ia32_cmppd512_mask: i = 2; l = 0; u = 31; break;
1013  case X86::BI__builtin_ia32_vpcomub:
1014  case X86::BI__builtin_ia32_vpcomuw:
1015  case X86::BI__builtin_ia32_vpcomud:
1016  case X86::BI__builtin_ia32_vpcomuq:
1017  case X86::BI__builtin_ia32_vpcomb:
1018  case X86::BI__builtin_ia32_vpcomw:
1019  case X86::BI__builtin_ia32_vpcomd:
1020  case X86::BI__builtin_ia32_vpcomq: i = 2; l = 0; u = 7; break;
1021  }
1022  return SemaBuiltinConstantArgRange(TheCall, i, l, u);
1023}
1024
1025/// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
1026/// parameter with the FormatAttr's correct format_idx and firstDataArg.
1027/// Returns true when the format fits the function and the FormatStringInfo has
1028/// been populated.
1029bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
1030                               FormatStringInfo *FSI) {
1031  FSI->HasVAListArg = Format->getFirstArg() == 0;
1032  FSI->FormatIdx = Format->getFormatIdx() - 1;
1033  FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
1034
1035  // The way the format attribute works in GCC, the implicit this argument
1036  // of member functions is counted. However, it doesn't appear in our own
1037  // lists, so decrement format_idx in that case.
1038  if (IsCXXMember) {
1039    if(FSI->FormatIdx == 0)
1040      return false;
1041    --FSI->FormatIdx;
1042    if (FSI->FirstDataArg != 0)
1043      --FSI->FirstDataArg;
1044  }
1045  return true;
1046}
1047
1048/// Checks if a the given expression evaluates to null.
1049///
1050/// \brief Returns true if the value evaluates to null.
1051static bool CheckNonNullExpr(Sema &S,
1052                             const Expr *Expr) {
1053  // As a special case, transparent unions initialized with zero are
1054  // considered null for the purposes of the nonnull attribute.
1055  if (const RecordType *UT = Expr->getType()->getAsUnionType()) {
1056    if (UT->getDecl()->hasAttr<TransparentUnionAttr>())
1057      if (const CompoundLiteralExpr *CLE =
1058          dyn_cast<CompoundLiteralExpr>(Expr))
1059        if (const InitListExpr *ILE =
1060            dyn_cast<InitListExpr>(CLE->getInitializer()))
1061          Expr = ILE->getInit(0);
1062  }
1063
1064  bool Result;
1065  return (!Expr->isValueDependent() &&
1066          Expr->EvaluateAsBooleanCondition(Result, S.Context) &&
1067          !Result);
1068}
1069
1070static void CheckNonNullArgument(Sema &S,
1071                                 const Expr *ArgExpr,
1072                                 SourceLocation CallSiteLoc) {
1073  if (CheckNonNullExpr(S, ArgExpr))
1074    S.Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1075}
1076
1077bool Sema::GetFormatNSStringIdx(const FormatAttr *Format, unsigned &Idx) {
1078  FormatStringInfo FSI;
1079  if ((GetFormatStringType(Format) == FST_NSString) &&
1080      getFormatStringInfo(Format, false, &FSI)) {
1081    Idx = FSI.FormatIdx;
1082    return true;
1083  }
1084  return false;
1085}
1086/// \brief Diagnose use of %s directive in an NSString which is being passed
1087/// as formatting string to formatting method.
1088static void
1089DiagnoseCStringFormatDirectiveInCFAPI(Sema &S,
1090                                        const NamedDecl *FDecl,
1091                                        Expr **Args,
1092                                        unsigned NumArgs) {
1093  unsigned Idx = 0;
1094  bool Format = false;
1095  ObjCStringFormatFamily SFFamily = FDecl->getObjCFStringFormattingFamily();
1096  if (SFFamily == ObjCStringFormatFamily::SFF_CFString) {
1097    Idx = 2;
1098    Format = true;
1099  }
1100  else
1101    for (const auto *I : FDecl->specific_attrs<FormatAttr>()) {
1102      if (S.GetFormatNSStringIdx(I, Idx)) {
1103        Format = true;
1104        break;
1105      }
1106    }
1107  if (!Format || NumArgs <= Idx)
1108    return;
1109  const Expr *FormatExpr = Args[Idx];
1110  if (const CStyleCastExpr *CSCE = dyn_cast<CStyleCastExpr>(FormatExpr))
1111    FormatExpr = CSCE->getSubExpr();
1112  const StringLiteral *FormatString;
1113  if (const ObjCStringLiteral *OSL =
1114      dyn_cast<ObjCStringLiteral>(FormatExpr->IgnoreParenImpCasts()))
1115    FormatString = OSL->getString();
1116  else
1117    FormatString = dyn_cast<StringLiteral>(FormatExpr->IgnoreParenImpCasts());
1118  if (!FormatString)
1119    return;
1120  if (S.FormatStringHasSArg(FormatString)) {
1121    S.Diag(FormatExpr->getExprLoc(), diag::warn_objc_cdirective_format_string)
1122      << "%s" << 1 << 1;
1123    S.Diag(FDecl->getLocation(), diag::note_entity_declared_at)
1124      << FDecl->getDeclName();
1125  }
1126}
1127
1128static void CheckNonNullArguments(Sema &S,
1129                                  const NamedDecl *FDecl,
1130                                  ArrayRef<const Expr *> Args,
1131                                  SourceLocation CallSiteLoc) {
1132  // Check the attributes attached to the method/function itself.
1133  llvm::SmallBitVector NonNullArgs;
1134  for (const auto *NonNull : FDecl->specific_attrs<NonNullAttr>()) {
1135    if (!NonNull->args_size()) {
1136      // Easy case: all pointer arguments are nonnull.
1137      for (const auto *Arg : Args)
1138        if (S.isValidPointerAttrType(Arg->getType()))
1139          CheckNonNullArgument(S, Arg, CallSiteLoc);
1140      return;
1141    }
1142
1143    for (unsigned Val : NonNull->args()) {
1144      if (Val >= Args.size())
1145        continue;
1146      if (NonNullArgs.empty())
1147        NonNullArgs.resize(Args.size());
1148      NonNullArgs.set(Val);
1149    }
1150  }
1151
1152  // Check the attributes on the parameters.
1153  ArrayRef<ParmVarDecl*> parms;
1154  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FDecl))
1155    parms = FD->parameters();
1156  else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(FDecl))
1157    parms = MD->parameters();
1158
1159  unsigned ArgIndex = 0;
1160  for (ArrayRef<ParmVarDecl*>::iterator I = parms.begin(), E = parms.end();
1161       I != E; ++I, ++ArgIndex) {
1162    const ParmVarDecl *PVD = *I;
1163    if (PVD->hasAttr<NonNullAttr>() ||
1164        (ArgIndex < NonNullArgs.size() && NonNullArgs[ArgIndex]))
1165      CheckNonNullArgument(S, Args[ArgIndex], CallSiteLoc);
1166  }
1167
1168  // In case this is a variadic call, check any remaining arguments.
1169  for (/**/; ArgIndex < NonNullArgs.size(); ++ArgIndex)
1170    if (NonNullArgs[ArgIndex])
1171      CheckNonNullArgument(S, Args[ArgIndex], CallSiteLoc);
1172}
1173
1174/// Handles the checks for format strings, non-POD arguments to vararg
1175/// functions, and NULL arguments passed to non-NULL parameters.
1176void Sema::checkCall(NamedDecl *FDecl, ArrayRef<const Expr *> Args,
1177                     unsigned NumParams, bool IsMemberFunction,
1178                     SourceLocation Loc, SourceRange Range,
1179                     VariadicCallType CallType) {
1180  // FIXME: We should check as much as we can in the template definition.
1181  if (CurContext->isDependentContext())
1182    return;
1183
1184  // Printf and scanf checking.
1185  llvm::SmallBitVector CheckedVarArgs;
1186  if (FDecl) {
1187    for (const auto *I : FDecl->specific_attrs<FormatAttr>()) {
1188      // Only create vector if there are format attributes.
1189      CheckedVarArgs.resize(Args.size());
1190
1191      CheckFormatArguments(I, Args, IsMemberFunction, CallType, Loc, Range,
1192                           CheckedVarArgs);
1193    }
1194  }
1195
1196  // Refuse POD arguments that weren't caught by the format string
1197  // checks above.
1198  if (CallType != VariadicDoesNotApply) {
1199    for (unsigned ArgIdx = NumParams; ArgIdx < Args.size(); ++ArgIdx) {
1200      // Args[ArgIdx] can be null in malformed code.
1201      if (const Expr *Arg = Args[ArgIdx]) {
1202        if (CheckedVarArgs.empty() || !CheckedVarArgs[ArgIdx])
1203          checkVariadicArgument(Arg, CallType);
1204      }
1205    }
1206  }
1207
1208  if (FDecl) {
1209    CheckNonNullArguments(*this, FDecl, Args, Loc);
1210
1211    // Type safety checking.
1212    for (const auto *I : FDecl->specific_attrs<ArgumentWithTypeTagAttr>())
1213      CheckArgumentWithTypeTag(I, Args.data());
1214  }
1215}
1216
1217/// CheckConstructorCall - Check a constructor call for correctness and safety
1218/// properties not enforced by the C type system.
1219void Sema::CheckConstructorCall(FunctionDecl *FDecl,
1220                                ArrayRef<const Expr *> Args,
1221                                const FunctionProtoType *Proto,
1222                                SourceLocation Loc) {
1223  VariadicCallType CallType =
1224    Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
1225  checkCall(FDecl, Args, Proto->getNumParams(),
1226            /*IsMemberFunction=*/true, Loc, SourceRange(), CallType);
1227}
1228
1229/// CheckFunctionCall - Check a direct function call for various correctness
1230/// and safety properties not strictly enforced by the C type system.
1231bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
1232                             const FunctionProtoType *Proto) {
1233  bool IsMemberOperatorCall = isa<CXXOperatorCallExpr>(TheCall) &&
1234                              isa<CXXMethodDecl>(FDecl);
1235  bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall) ||
1236                          IsMemberOperatorCall;
1237  VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
1238                                                  TheCall->getCallee());
1239  unsigned NumParams = Proto ? Proto->getNumParams() : 0;
1240  Expr** Args = TheCall->getArgs();
1241  unsigned NumArgs = TheCall->getNumArgs();
1242  if (IsMemberOperatorCall) {
1243    // If this is a call to a member operator, hide the first argument
1244    // from checkCall.
1245    // FIXME: Our choice of AST representation here is less than ideal.
1246    ++Args;
1247    --NumArgs;
1248  }
1249  checkCall(FDecl, llvm::makeArrayRef(Args, NumArgs), NumParams,
1250            IsMemberFunction, TheCall->getRParenLoc(),
1251            TheCall->getCallee()->getSourceRange(), CallType);
1252
1253  IdentifierInfo *FnInfo = FDecl->getIdentifier();
1254  // None of the checks below are needed for functions that don't have
1255  // simple names (e.g., C++ conversion functions).
1256  if (!FnInfo)
1257    return false;
1258
1259  CheckAbsoluteValueFunction(TheCall, FDecl, FnInfo);
1260  if (getLangOpts().ObjC1)
1261    DiagnoseCStringFormatDirectiveInCFAPI(*this, FDecl, Args, NumArgs);
1262
1263  unsigned CMId = FDecl->getMemoryFunctionKind();
1264  if (CMId == 0)
1265    return false;
1266
1267  // Handle memory setting and copying functions.
1268  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
1269    CheckStrlcpycatArguments(TheCall, FnInfo);
1270  else if (CMId == Builtin::BIstrncat)
1271    CheckStrncatArguments(TheCall, FnInfo);
1272  else
1273    CheckMemaccessArguments(TheCall, CMId, FnInfo);
1274
1275  return false;
1276}
1277
1278bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
1279                               ArrayRef<const Expr *> Args) {
1280  VariadicCallType CallType =
1281      Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
1282
1283  checkCall(Method, Args, Method->param_size(),
1284            /*IsMemberFunction=*/false,
1285            lbrac, Method->getSourceRange(), CallType);
1286
1287  return false;
1288}
1289
1290bool Sema::CheckPointerCall(NamedDecl *NDecl, CallExpr *TheCall,
1291                            const FunctionProtoType *Proto) {
1292  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
1293  if (!V)
1294    return false;
1295
1296  QualType Ty = V->getType();
1297  if (!Ty->isBlockPointerType() && !Ty->isFunctionPointerType())
1298    return false;
1299
1300  VariadicCallType CallType;
1301  if (!Proto || !Proto->isVariadic()) {
1302    CallType = VariadicDoesNotApply;
1303  } else if (Ty->isBlockPointerType()) {
1304    CallType = VariadicBlock;
1305  } else { // Ty->isFunctionPointerType()
1306    CallType = VariadicFunction;
1307  }
1308  unsigned NumParams = Proto ? Proto->getNumParams() : 0;
1309
1310  checkCall(NDecl, llvm::makeArrayRef(TheCall->getArgs(),
1311                                      TheCall->getNumArgs()),
1312            NumParams, /*IsMemberFunction=*/false, TheCall->getRParenLoc(),
1313            TheCall->getCallee()->getSourceRange(), CallType);
1314
1315  return false;
1316}
1317
1318/// Checks function calls when a FunctionDecl or a NamedDecl is not available,
1319/// such as function pointers returned from functions.
1320bool Sema::CheckOtherCall(CallExpr *TheCall, const FunctionProtoType *Proto) {
1321  VariadicCallType CallType = getVariadicCallType(/*FDecl=*/nullptr, Proto,
1322                                                  TheCall->getCallee());
1323  unsigned NumParams = Proto ? Proto->getNumParams() : 0;
1324
1325  checkCall(/*FDecl=*/nullptr,
1326            llvm::makeArrayRef(TheCall->getArgs(), TheCall->getNumArgs()),
1327            NumParams, /*IsMemberFunction=*/false, TheCall->getRParenLoc(),
1328            TheCall->getCallee()->getSourceRange(), CallType);
1329
1330  return false;
1331}
1332
1333static bool isValidOrderingForOp(int64_t Ordering, AtomicExpr::AtomicOp Op) {
1334  if (Ordering < AtomicExpr::AO_ABI_memory_order_relaxed ||
1335      Ordering > AtomicExpr::AO_ABI_memory_order_seq_cst)
1336    return false;
1337
1338  switch (Op) {
1339  case AtomicExpr::AO__c11_atomic_init:
1340    llvm_unreachable("There is no ordering argument for an init");
1341
1342  case AtomicExpr::AO__c11_atomic_load:
1343  case AtomicExpr::AO__atomic_load_n:
1344  case AtomicExpr::AO__atomic_load:
1345    return Ordering != AtomicExpr::AO_ABI_memory_order_release &&
1346           Ordering != AtomicExpr::AO_ABI_memory_order_acq_rel;
1347
1348  case AtomicExpr::AO__c11_atomic_store:
1349  case AtomicExpr::AO__atomic_store:
1350  case AtomicExpr::AO__atomic_store_n:
1351    return Ordering != AtomicExpr::AO_ABI_memory_order_consume &&
1352           Ordering != AtomicExpr::AO_ABI_memory_order_acquire &&
1353           Ordering != AtomicExpr::AO_ABI_memory_order_acq_rel;
1354
1355  default:
1356    return true;
1357  }
1358}
1359
1360ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
1361                                         AtomicExpr::AtomicOp Op) {
1362  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
1363  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1364
1365  // All these operations take one of the following forms:
1366  enum {
1367    // C    __c11_atomic_init(A *, C)
1368    Init,
1369    // C    __c11_atomic_load(A *, int)
1370    Load,
1371    // void __atomic_load(A *, CP, int)
1372    Copy,
1373    // C    __c11_atomic_add(A *, M, int)
1374    Arithmetic,
1375    // C    __atomic_exchange_n(A *, CP, int)
1376    Xchg,
1377    // void __atomic_exchange(A *, C *, CP, int)
1378    GNUXchg,
1379    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
1380    C11CmpXchg,
1381    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
1382    GNUCmpXchg
1383  } Form = Init;
1384  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
1385  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
1386  // where:
1387  //   C is an appropriate type,
1388  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
1389  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
1390  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
1391  //   the int parameters are for orderings.
1392
1393  static_assert(AtomicExpr::AO__c11_atomic_init == 0 &&
1394                    AtomicExpr::AO__c11_atomic_fetch_xor + 1 ==
1395                        AtomicExpr::AO__atomic_load,
1396                "need to update code for modified C11 atomics");
1397  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
1398               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
1399  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
1400             Op == AtomicExpr::AO__atomic_store_n ||
1401             Op == AtomicExpr::AO__atomic_exchange_n ||
1402             Op == AtomicExpr::AO__atomic_compare_exchange_n;
1403  bool IsAddSub = false;
1404
1405  switch (Op) {
1406  case AtomicExpr::AO__c11_atomic_init:
1407    Form = Init;
1408    break;
1409
1410  case AtomicExpr::AO__c11_atomic_load:
1411  case AtomicExpr::AO__atomic_load_n:
1412    Form = Load;
1413    break;
1414
1415  case AtomicExpr::AO__c11_atomic_store:
1416  case AtomicExpr::AO__atomic_load:
1417  case AtomicExpr::AO__atomic_store:
1418  case AtomicExpr::AO__atomic_store_n:
1419    Form = Copy;
1420    break;
1421
1422  case AtomicExpr::AO__c11_atomic_fetch_add:
1423  case AtomicExpr::AO__c11_atomic_fetch_sub:
1424  case AtomicExpr::AO__atomic_fetch_add:
1425  case AtomicExpr::AO__atomic_fetch_sub:
1426  case AtomicExpr::AO__atomic_add_fetch:
1427  case AtomicExpr::AO__atomic_sub_fetch:
1428    IsAddSub = true;
1429    // Fall through.
1430  case AtomicExpr::AO__c11_atomic_fetch_and:
1431  case AtomicExpr::AO__c11_atomic_fetch_or:
1432  case AtomicExpr::AO__c11_atomic_fetch_xor:
1433  case AtomicExpr::AO__atomic_fetch_and:
1434  case AtomicExpr::AO__atomic_fetch_or:
1435  case AtomicExpr::AO__atomic_fetch_xor:
1436  case AtomicExpr::AO__atomic_fetch_nand:
1437  case AtomicExpr::AO__atomic_and_fetch:
1438  case AtomicExpr::AO__atomic_or_fetch:
1439  case AtomicExpr::AO__atomic_xor_fetch:
1440  case AtomicExpr::AO__atomic_nand_fetch:
1441    Form = Arithmetic;
1442    break;
1443
1444  case AtomicExpr::AO__c11_atomic_exchange:
1445  case AtomicExpr::AO__atomic_exchange_n:
1446    Form = Xchg;
1447    break;
1448
1449  case AtomicExpr::AO__atomic_exchange:
1450    Form = GNUXchg;
1451    break;
1452
1453  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
1454  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
1455    Form = C11CmpXchg;
1456    break;
1457
1458  case AtomicExpr::AO__atomic_compare_exchange:
1459  case AtomicExpr::AO__atomic_compare_exchange_n:
1460    Form = GNUCmpXchg;
1461    break;
1462  }
1463
1464  // Check we have the right number of arguments.
1465  if (TheCall->getNumArgs() < NumArgs[Form]) {
1466    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1467      << 0 << NumArgs[Form] << TheCall->getNumArgs()
1468      << TheCall->getCallee()->getSourceRange();
1469    return ExprError();
1470  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
1471    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
1472         diag::err_typecheck_call_too_many_args)
1473      << 0 << NumArgs[Form] << TheCall->getNumArgs()
1474      << TheCall->getCallee()->getSourceRange();
1475    return ExprError();
1476  }
1477
1478  // Inspect the first argument of the atomic operation.
1479  Expr *Ptr = TheCall->getArg(0);
1480  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
1481  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
1482  if (!pointerType) {
1483    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
1484      << Ptr->getType() << Ptr->getSourceRange();
1485    return ExprError();
1486  }
1487
1488  // For a __c11 builtin, this should be a pointer to an _Atomic type.
1489  QualType AtomTy = pointerType->getPointeeType(); // 'A'
1490  QualType ValType = AtomTy; // 'C'
1491  if (IsC11) {
1492    if (!AtomTy->isAtomicType()) {
1493      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
1494        << Ptr->getType() << Ptr->getSourceRange();
1495      return ExprError();
1496    }
1497    if (AtomTy.isConstQualified()) {
1498      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
1499        << Ptr->getType() << Ptr->getSourceRange();
1500      return ExprError();
1501    }
1502    ValType = AtomTy->getAs<AtomicType>()->getValueType();
1503  }
1504
1505  // For an arithmetic operation, the implied arithmetic must be well-formed.
1506  if (Form == Arithmetic) {
1507    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
1508    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
1509      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
1510        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
1511      return ExprError();
1512    }
1513    if (!IsAddSub && !ValType->isIntegerType()) {
1514      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
1515        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
1516      return ExprError();
1517    }
1518    if (IsC11 && ValType->isPointerType() &&
1519        RequireCompleteType(Ptr->getLocStart(), ValType->getPointeeType(),
1520                            diag::err_incomplete_type)) {
1521      return ExprError();
1522    }
1523  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
1524    // For __atomic_*_n operations, the value type must be a scalar integral or
1525    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
1526    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
1527      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
1528    return ExprError();
1529  }
1530
1531  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context) &&
1532      !AtomTy->isScalarType()) {
1533    // For GNU atomics, require a trivially-copyable type. This is not part of
1534    // the GNU atomics specification, but we enforce it for sanity.
1535    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
1536      << Ptr->getType() << Ptr->getSourceRange();
1537    return ExprError();
1538  }
1539
1540  // FIXME: For any builtin other than a load, the ValType must not be
1541  // const-qualified.
1542
1543  switch (ValType.getObjCLifetime()) {
1544  case Qualifiers::OCL_None:
1545  case Qualifiers::OCL_ExplicitNone:
1546    // okay
1547    break;
1548
1549  case Qualifiers::OCL_Weak:
1550  case Qualifiers::OCL_Strong:
1551  case Qualifiers::OCL_Autoreleasing:
1552    // FIXME: Can this happen? By this point, ValType should be known
1553    // to be trivially copyable.
1554    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1555      << ValType << Ptr->getSourceRange();
1556    return ExprError();
1557  }
1558
1559  QualType ResultType = ValType;
1560  if (Form == Copy || Form == GNUXchg || Form == Init)
1561    ResultType = Context.VoidTy;
1562  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
1563    ResultType = Context.BoolTy;
1564
1565  // The type of a parameter passed 'by value'. In the GNU atomics, such
1566  // arguments are actually passed as pointers.
1567  QualType ByValType = ValType; // 'CP'
1568  if (!IsC11 && !IsN)
1569    ByValType = Ptr->getType();
1570
1571  // The first argument --- the pointer --- has a fixed type; we
1572  // deduce the types of the rest of the arguments accordingly.  Walk
1573  // the remaining arguments, converting them to the deduced value type.
1574  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
1575    QualType Ty;
1576    if (i < NumVals[Form] + 1) {
1577      switch (i) {
1578      case 1:
1579        // The second argument is the non-atomic operand. For arithmetic, this
1580        // is always passed by value, and for a compare_exchange it is always
1581        // passed by address. For the rest, GNU uses by-address and C11 uses
1582        // by-value.
1583        assert(Form != Load);
1584        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
1585          Ty = ValType;
1586        else if (Form == Copy || Form == Xchg)
1587          Ty = ByValType;
1588        else if (Form == Arithmetic)
1589          Ty = Context.getPointerDiffType();
1590        else
1591          Ty = Context.getPointerType(ValType.getUnqualifiedType());
1592        break;
1593      case 2:
1594        // The third argument to compare_exchange / GNU exchange is a
1595        // (pointer to a) desired value.
1596        Ty = ByValType;
1597        break;
1598      case 3:
1599        // The fourth argument to GNU compare_exchange is a 'weak' flag.
1600        Ty = Context.BoolTy;
1601        break;
1602      }
1603    } else {
1604      // The order(s) are always converted to int.
1605      Ty = Context.IntTy;
1606    }
1607
1608    InitializedEntity Entity =
1609        InitializedEntity::InitializeParameter(Context, Ty, false);
1610    ExprResult Arg = TheCall->getArg(i);
1611    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1612    if (Arg.isInvalid())
1613      return true;
1614    TheCall->setArg(i, Arg.get());
1615  }
1616
1617  // Permute the arguments into a 'consistent' order.
1618  SmallVector<Expr*, 5> SubExprs;
1619  SubExprs.push_back(Ptr);
1620  switch (Form) {
1621  case Init:
1622    // Note, AtomicExpr::getVal1() has a special case for this atomic.
1623    SubExprs.push_back(TheCall->getArg(1)); // Val1
1624    break;
1625  case Load:
1626    SubExprs.push_back(TheCall->getArg(1)); // Order
1627    break;
1628  case Copy:
1629  case Arithmetic:
1630  case Xchg:
1631    SubExprs.push_back(TheCall->getArg(2)); // Order
1632    SubExprs.push_back(TheCall->getArg(1)); // Val1
1633    break;
1634  case GNUXchg:
1635    // Note, AtomicExpr::getVal2() has a special case for this atomic.
1636    SubExprs.push_back(TheCall->getArg(3)); // Order
1637    SubExprs.push_back(TheCall->getArg(1)); // Val1
1638    SubExprs.push_back(TheCall->getArg(2)); // Val2
1639    break;
1640  case C11CmpXchg:
1641    SubExprs.push_back(TheCall->getArg(3)); // Order
1642    SubExprs.push_back(TheCall->getArg(1)); // Val1
1643    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
1644    SubExprs.push_back(TheCall->getArg(2)); // Val2
1645    break;
1646  case GNUCmpXchg:
1647    SubExprs.push_back(TheCall->getArg(4)); // Order
1648    SubExprs.push_back(TheCall->getArg(1)); // Val1
1649    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
1650    SubExprs.push_back(TheCall->getArg(2)); // Val2
1651    SubExprs.push_back(TheCall->getArg(3)); // Weak
1652    break;
1653  }
1654
1655  if (SubExprs.size() >= 2 && Form != Init) {
1656    llvm::APSInt Result(32);
1657    if (SubExprs[1]->isIntegerConstantExpr(Result, Context) &&
1658        !isValidOrderingForOp(Result.getSExtValue(), Op))
1659      Diag(SubExprs[1]->getLocStart(),
1660           diag::warn_atomic_op_has_invalid_memory_order)
1661          << SubExprs[1]->getSourceRange();
1662  }
1663
1664  AtomicExpr *AE = new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
1665                                            SubExprs, ResultType, Op,
1666                                            TheCall->getRParenLoc());
1667
1668  if ((Op == AtomicExpr::AO__c11_atomic_load ||
1669       (Op == AtomicExpr::AO__c11_atomic_store)) &&
1670      Context.AtomicUsesUnsupportedLibcall(AE))
1671    Diag(AE->getLocStart(), diag::err_atomic_load_store_uses_lib) <<
1672    ((Op == AtomicExpr::AO__c11_atomic_load) ? 0 : 1);
1673
1674  return AE;
1675}
1676
1677
1678/// checkBuiltinArgument - Given a call to a builtin function, perform
1679/// normal type-checking on the given argument, updating the call in
1680/// place.  This is useful when a builtin function requires custom
1681/// type-checking for some of its arguments but not necessarily all of
1682/// them.
1683///
1684/// Returns true on error.
1685static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
1686  FunctionDecl *Fn = E->getDirectCallee();
1687  assert(Fn && "builtin call without direct callee!");
1688
1689  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
1690  InitializedEntity Entity =
1691    InitializedEntity::InitializeParameter(S.Context, Param);
1692
1693  ExprResult Arg = E->getArg(0);
1694  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
1695  if (Arg.isInvalid())
1696    return true;
1697
1698  E->setArg(ArgIndex, Arg.get());
1699  return false;
1700}
1701
1702/// SemaBuiltinAtomicOverloaded - We have a call to a function like
1703/// __sync_fetch_and_add, which is an overloaded function based on the pointer
1704/// type of its first argument.  The main ActOnCallExpr routines have already
1705/// promoted the types of arguments because all of these calls are prototyped as
1706/// void(...).
1707///
1708/// This function goes through and does final semantic checking for these
1709/// builtins,
1710ExprResult
1711Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
1712  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
1713  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1714  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1715
1716  // Ensure that we have at least one argument to do type inference from.
1717  if (TheCall->getNumArgs() < 1) {
1718    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1719      << 0 << 1 << TheCall->getNumArgs()
1720      << TheCall->getCallee()->getSourceRange();
1721    return ExprError();
1722  }
1723
1724  // Inspect the first argument of the atomic builtin.  This should always be
1725  // a pointer type, whose element is an integral scalar or pointer type.
1726  // Because it is a pointer type, we don't have to worry about any implicit
1727  // casts here.
1728  // FIXME: We don't allow floating point scalars as input.
1729  Expr *FirstArg = TheCall->getArg(0);
1730  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
1731  if (FirstArgResult.isInvalid())
1732    return ExprError();
1733  FirstArg = FirstArgResult.get();
1734  TheCall->setArg(0, FirstArg);
1735
1736  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
1737  if (!pointerType) {
1738    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
1739      << FirstArg->getType() << FirstArg->getSourceRange();
1740    return ExprError();
1741  }
1742
1743  QualType ValType = pointerType->getPointeeType();
1744  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
1745      !ValType->isBlockPointerType()) {
1746    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
1747      << FirstArg->getType() << FirstArg->getSourceRange();
1748    return ExprError();
1749  }
1750
1751  switch (ValType.getObjCLifetime()) {
1752  case Qualifiers::OCL_None:
1753  case Qualifiers::OCL_ExplicitNone:
1754    // okay
1755    break;
1756
1757  case Qualifiers::OCL_Weak:
1758  case Qualifiers::OCL_Strong:
1759  case Qualifiers::OCL_Autoreleasing:
1760    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
1761      << ValType << FirstArg->getSourceRange();
1762    return ExprError();
1763  }
1764
1765  // Strip any qualifiers off ValType.
1766  ValType = ValType.getUnqualifiedType();
1767
1768  // The majority of builtins return a value, but a few have special return
1769  // types, so allow them to override appropriately below.
1770  QualType ResultType = ValType;
1771
1772  // We need to figure out which concrete builtin this maps onto.  For example,
1773  // __sync_fetch_and_add with a 2 byte object turns into
1774  // __sync_fetch_and_add_2.
1775#define BUILTIN_ROW(x) \
1776  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
1777    Builtin::BI##x##_8, Builtin::BI##x##_16 }
1778
1779  static const unsigned BuiltinIndices[][5] = {
1780    BUILTIN_ROW(__sync_fetch_and_add),
1781    BUILTIN_ROW(__sync_fetch_and_sub),
1782    BUILTIN_ROW(__sync_fetch_and_or),
1783    BUILTIN_ROW(__sync_fetch_and_and),
1784    BUILTIN_ROW(__sync_fetch_and_xor),
1785    BUILTIN_ROW(__sync_fetch_and_nand),
1786
1787    BUILTIN_ROW(__sync_add_and_fetch),
1788    BUILTIN_ROW(__sync_sub_and_fetch),
1789    BUILTIN_ROW(__sync_and_and_fetch),
1790    BUILTIN_ROW(__sync_or_and_fetch),
1791    BUILTIN_ROW(__sync_xor_and_fetch),
1792    BUILTIN_ROW(__sync_nand_and_fetch),
1793
1794    BUILTIN_ROW(__sync_val_compare_and_swap),
1795    BUILTIN_ROW(__sync_bool_compare_and_swap),
1796    BUILTIN_ROW(__sync_lock_test_and_set),
1797    BUILTIN_ROW(__sync_lock_release),
1798    BUILTIN_ROW(__sync_swap)
1799  };
1800#undef BUILTIN_ROW
1801
1802  // Determine the index of the size.
1803  unsigned SizeIndex;
1804  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
1805  case 1: SizeIndex = 0; break;
1806  case 2: SizeIndex = 1; break;
1807  case 4: SizeIndex = 2; break;
1808  case 8: SizeIndex = 3; break;
1809  case 16: SizeIndex = 4; break;
1810  default:
1811    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
1812      << FirstArg->getType() << FirstArg->getSourceRange();
1813    return ExprError();
1814  }
1815
1816  // Each of these builtins has one pointer argument, followed by some number of
1817  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
1818  // that we ignore.  Find out which row of BuiltinIndices to read from as well
1819  // as the number of fixed args.
1820  unsigned BuiltinID = FDecl->getBuiltinID();
1821  unsigned BuiltinIndex, NumFixed = 1;
1822  bool WarnAboutSemanticsChange = false;
1823  switch (BuiltinID) {
1824  default: llvm_unreachable("Unknown overloaded atomic builtin!");
1825  case Builtin::BI__sync_fetch_and_add:
1826  case Builtin::BI__sync_fetch_and_add_1:
1827  case Builtin::BI__sync_fetch_and_add_2:
1828  case Builtin::BI__sync_fetch_and_add_4:
1829  case Builtin::BI__sync_fetch_and_add_8:
1830  case Builtin::BI__sync_fetch_and_add_16:
1831    BuiltinIndex = 0;
1832    break;
1833
1834  case Builtin::BI__sync_fetch_and_sub:
1835  case Builtin::BI__sync_fetch_and_sub_1:
1836  case Builtin::BI__sync_fetch_and_sub_2:
1837  case Builtin::BI__sync_fetch_and_sub_4:
1838  case Builtin::BI__sync_fetch_and_sub_8:
1839  case Builtin::BI__sync_fetch_and_sub_16:
1840    BuiltinIndex = 1;
1841    break;
1842
1843  case Builtin::BI__sync_fetch_and_or:
1844  case Builtin::BI__sync_fetch_and_or_1:
1845  case Builtin::BI__sync_fetch_and_or_2:
1846  case Builtin::BI__sync_fetch_and_or_4:
1847  case Builtin::BI__sync_fetch_and_or_8:
1848  case Builtin::BI__sync_fetch_and_or_16:
1849    BuiltinIndex = 2;
1850    break;
1851
1852  case Builtin::BI__sync_fetch_and_and:
1853  case Builtin::BI__sync_fetch_and_and_1:
1854  case Builtin::BI__sync_fetch_and_and_2:
1855  case Builtin::BI__sync_fetch_and_and_4:
1856  case Builtin::BI__sync_fetch_and_and_8:
1857  case Builtin::BI__sync_fetch_and_and_16:
1858    BuiltinIndex = 3;
1859    break;
1860
1861  case Builtin::BI__sync_fetch_and_xor:
1862  case Builtin::BI__sync_fetch_and_xor_1:
1863  case Builtin::BI__sync_fetch_and_xor_2:
1864  case Builtin::BI__sync_fetch_and_xor_4:
1865  case Builtin::BI__sync_fetch_and_xor_8:
1866  case Builtin::BI__sync_fetch_and_xor_16:
1867    BuiltinIndex = 4;
1868    break;
1869
1870  case Builtin::BI__sync_fetch_and_nand:
1871  case Builtin::BI__sync_fetch_and_nand_1:
1872  case Builtin::BI__sync_fetch_and_nand_2:
1873  case Builtin::BI__sync_fetch_and_nand_4:
1874  case Builtin::BI__sync_fetch_and_nand_8:
1875  case Builtin::BI__sync_fetch_and_nand_16:
1876    BuiltinIndex = 5;
1877    WarnAboutSemanticsChange = true;
1878    break;
1879
1880  case Builtin::BI__sync_add_and_fetch:
1881  case Builtin::BI__sync_add_and_fetch_1:
1882  case Builtin::BI__sync_add_and_fetch_2:
1883  case Builtin::BI__sync_add_and_fetch_4:
1884  case Builtin::BI__sync_add_and_fetch_8:
1885  case Builtin::BI__sync_add_and_fetch_16:
1886    BuiltinIndex = 6;
1887    break;
1888
1889  case Builtin::BI__sync_sub_and_fetch:
1890  case Builtin::BI__sync_sub_and_fetch_1:
1891  case Builtin::BI__sync_sub_and_fetch_2:
1892  case Builtin::BI__sync_sub_and_fetch_4:
1893  case Builtin::BI__sync_sub_and_fetch_8:
1894  case Builtin::BI__sync_sub_and_fetch_16:
1895    BuiltinIndex = 7;
1896    break;
1897
1898  case Builtin::BI__sync_and_and_fetch:
1899  case Builtin::BI__sync_and_and_fetch_1:
1900  case Builtin::BI__sync_and_and_fetch_2:
1901  case Builtin::BI__sync_and_and_fetch_4:
1902  case Builtin::BI__sync_and_and_fetch_8:
1903  case Builtin::BI__sync_and_and_fetch_16:
1904    BuiltinIndex = 8;
1905    break;
1906
1907  case Builtin::BI__sync_or_and_fetch:
1908  case Builtin::BI__sync_or_and_fetch_1:
1909  case Builtin::BI__sync_or_and_fetch_2:
1910  case Builtin::BI__sync_or_and_fetch_4:
1911  case Builtin::BI__sync_or_and_fetch_8:
1912  case Builtin::BI__sync_or_and_fetch_16:
1913    BuiltinIndex = 9;
1914    break;
1915
1916  case Builtin::BI__sync_xor_and_fetch:
1917  case Builtin::BI__sync_xor_and_fetch_1:
1918  case Builtin::BI__sync_xor_and_fetch_2:
1919  case Builtin::BI__sync_xor_and_fetch_4:
1920  case Builtin::BI__sync_xor_and_fetch_8:
1921  case Builtin::BI__sync_xor_and_fetch_16:
1922    BuiltinIndex = 10;
1923    break;
1924
1925  case Builtin::BI__sync_nand_and_fetch:
1926  case Builtin::BI__sync_nand_and_fetch_1:
1927  case Builtin::BI__sync_nand_and_fetch_2:
1928  case Builtin::BI__sync_nand_and_fetch_4:
1929  case Builtin::BI__sync_nand_and_fetch_8:
1930  case Builtin::BI__sync_nand_and_fetch_16:
1931    BuiltinIndex = 11;
1932    WarnAboutSemanticsChange = true;
1933    break;
1934
1935  case Builtin::BI__sync_val_compare_and_swap:
1936  case Builtin::BI__sync_val_compare_and_swap_1:
1937  case Builtin::BI__sync_val_compare_and_swap_2:
1938  case Builtin::BI__sync_val_compare_and_swap_4:
1939  case Builtin::BI__sync_val_compare_and_swap_8:
1940  case Builtin::BI__sync_val_compare_and_swap_16:
1941    BuiltinIndex = 12;
1942    NumFixed = 2;
1943    break;
1944
1945  case Builtin::BI__sync_bool_compare_and_swap:
1946  case Builtin::BI__sync_bool_compare_and_swap_1:
1947  case Builtin::BI__sync_bool_compare_and_swap_2:
1948  case Builtin::BI__sync_bool_compare_and_swap_4:
1949  case Builtin::BI__sync_bool_compare_and_swap_8:
1950  case Builtin::BI__sync_bool_compare_and_swap_16:
1951    BuiltinIndex = 13;
1952    NumFixed = 2;
1953    ResultType = Context.BoolTy;
1954    break;
1955
1956  case Builtin::BI__sync_lock_test_and_set:
1957  case Builtin::BI__sync_lock_test_and_set_1:
1958  case Builtin::BI__sync_lock_test_and_set_2:
1959  case Builtin::BI__sync_lock_test_and_set_4:
1960  case Builtin::BI__sync_lock_test_and_set_8:
1961  case Builtin::BI__sync_lock_test_and_set_16:
1962    BuiltinIndex = 14;
1963    break;
1964
1965  case Builtin::BI__sync_lock_release:
1966  case Builtin::BI__sync_lock_release_1:
1967  case Builtin::BI__sync_lock_release_2:
1968  case Builtin::BI__sync_lock_release_4:
1969  case Builtin::BI__sync_lock_release_8:
1970  case Builtin::BI__sync_lock_release_16:
1971    BuiltinIndex = 15;
1972    NumFixed = 0;
1973    ResultType = Context.VoidTy;
1974    break;
1975
1976  case Builtin::BI__sync_swap:
1977  case Builtin::BI__sync_swap_1:
1978  case Builtin::BI__sync_swap_2:
1979  case Builtin::BI__sync_swap_4:
1980  case Builtin::BI__sync_swap_8:
1981  case Builtin::BI__sync_swap_16:
1982    BuiltinIndex = 16;
1983    break;
1984  }
1985
1986  // Now that we know how many fixed arguments we expect, first check that we
1987  // have at least that many.
1988  if (TheCall->getNumArgs() < 1+NumFixed) {
1989    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1990      << 0 << 1+NumFixed << TheCall->getNumArgs()
1991      << TheCall->getCallee()->getSourceRange();
1992    return ExprError();
1993  }
1994
1995  if (WarnAboutSemanticsChange) {
1996    Diag(TheCall->getLocEnd(), diag::warn_sync_fetch_and_nand_semantics_change)
1997      << TheCall->getCallee()->getSourceRange();
1998  }
1999
2000  // Get the decl for the concrete builtin from this, we can tell what the
2001  // concrete integer type we should convert to is.
2002  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
2003  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
2004  FunctionDecl *NewBuiltinDecl;
2005  if (NewBuiltinID == BuiltinID)
2006    NewBuiltinDecl = FDecl;
2007  else {
2008    // Perform builtin lookup to avoid redeclaring it.
2009    DeclarationName DN(&Context.Idents.get(NewBuiltinName));
2010    LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
2011    LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
2012    assert(Res.getFoundDecl());
2013    NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
2014    if (!NewBuiltinDecl)
2015      return ExprError();
2016  }
2017
2018  // The first argument --- the pointer --- has a fixed type; we
2019  // deduce the types of the rest of the arguments accordingly.  Walk
2020  // the remaining arguments, converting them to the deduced value type.
2021  for (unsigned i = 0; i != NumFixed; ++i) {
2022    ExprResult Arg = TheCall->getArg(i+1);
2023
2024    // GCC does an implicit conversion to the pointer or integer ValType.  This
2025    // can fail in some cases (1i -> int**), check for this error case now.
2026    // Initialize the argument.
2027    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
2028                                                   ValType, /*consume*/ false);
2029    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
2030    if (Arg.isInvalid())
2031      return ExprError();
2032
2033    // Okay, we have something that *can* be converted to the right type.  Check
2034    // to see if there is a potentially weird extension going on here.  This can
2035    // happen when you do an atomic operation on something like an char* and
2036    // pass in 42.  The 42 gets converted to char.  This is even more strange
2037    // for things like 45.123 -> char, etc.
2038    // FIXME: Do this check.
2039    TheCall->setArg(i+1, Arg.get());
2040  }
2041
2042  ASTContext& Context = this->getASTContext();
2043
2044  // Create a new DeclRefExpr to refer to the new decl.
2045  DeclRefExpr* NewDRE = DeclRefExpr::Create(
2046      Context,
2047      DRE->getQualifierLoc(),
2048      SourceLocation(),
2049      NewBuiltinDecl,
2050      /*enclosing*/ false,
2051      DRE->getLocation(),
2052      Context.BuiltinFnTy,
2053      DRE->getValueKind());
2054
2055  // Set the callee in the CallExpr.
2056  // FIXME: This loses syntactic information.
2057  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
2058  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
2059                                              CK_BuiltinFnToFnPtr);
2060  TheCall->setCallee(PromotedCall.get());
2061
2062  // Change the result type of the call to match the original value type. This
2063  // is arbitrary, but the codegen for these builtins ins design to handle it
2064  // gracefully.
2065  TheCall->setType(ResultType);
2066
2067  return TheCallResult;
2068}
2069
2070/// CheckObjCString - Checks that the argument to the builtin
2071/// CFString constructor is correct
2072/// Note: It might also make sense to do the UTF-16 conversion here (would
2073/// simplify the backend).
2074bool Sema::CheckObjCString(Expr *Arg) {
2075  Arg = Arg->IgnoreParenCasts();
2076  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
2077
2078  if (!Literal || !Literal->isAscii()) {
2079    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
2080      << Arg->getSourceRange();
2081    return true;
2082  }
2083
2084  if (Literal->containsNonAsciiOrNull()) {
2085    StringRef String = Literal->getString();
2086    unsigned NumBytes = String.size();
2087    SmallVector<UTF16, 128> ToBuf(NumBytes);
2088    const UTF8 *FromPtr = (const UTF8 *)String.data();
2089    UTF16 *ToPtr = &ToBuf[0];
2090
2091    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
2092                                                 &ToPtr, ToPtr + NumBytes,
2093                                                 strictConversion);
2094    // Check for conversion failure.
2095    if (Result != conversionOK)
2096      Diag(Arg->getLocStart(),
2097           diag::warn_cfstring_truncated) << Arg->getSourceRange();
2098  }
2099  return false;
2100}
2101
2102/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
2103/// Emit an error and return true on failure, return false on success.
2104bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
2105  Expr *Fn = TheCall->getCallee();
2106  if (TheCall->getNumArgs() > 2) {
2107    Diag(TheCall->getArg(2)->getLocStart(),
2108         diag::err_typecheck_call_too_many_args)
2109      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
2110      << Fn->getSourceRange()
2111      << SourceRange(TheCall->getArg(2)->getLocStart(),
2112                     (*(TheCall->arg_end()-1))->getLocEnd());
2113    return true;
2114  }
2115
2116  if (TheCall->getNumArgs() < 2) {
2117    return Diag(TheCall->getLocEnd(),
2118      diag::err_typecheck_call_too_few_args_at_least)
2119      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
2120  }
2121
2122  // Type-check the first argument normally.
2123  if (checkBuiltinArgument(*this, TheCall, 0))
2124    return true;
2125
2126  // Determine whether the current function is variadic or not.
2127  BlockScopeInfo *CurBlock = getCurBlock();
2128  bool isVariadic;
2129  if (CurBlock)
2130    isVariadic = CurBlock->TheDecl->isVariadic();
2131  else if (FunctionDecl *FD = getCurFunctionDecl())
2132    isVariadic = FD->isVariadic();
2133  else
2134    isVariadic = getCurMethodDecl()->isVariadic();
2135
2136  if (!isVariadic) {
2137    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
2138    return true;
2139  }
2140
2141  // Verify that the second argument to the builtin is the last argument of the
2142  // current function or method.
2143  bool SecondArgIsLastNamedArgument = false;
2144  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
2145
2146  // These are valid if SecondArgIsLastNamedArgument is false after the next
2147  // block.
2148  QualType Type;
2149  SourceLocation ParamLoc;
2150
2151  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
2152    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
2153      // FIXME: This isn't correct for methods (results in bogus warning).
2154      // Get the last formal in the current function.
2155      const ParmVarDecl *LastArg;
2156      if (CurBlock)
2157        LastArg = *(CurBlock->TheDecl->param_end()-1);
2158      else if (FunctionDecl *FD = getCurFunctionDecl())
2159        LastArg = *(FD->param_end()-1);
2160      else
2161        LastArg = *(getCurMethodDecl()->param_end()-1);
2162      SecondArgIsLastNamedArgument = PV == LastArg;
2163
2164      Type = PV->getType();
2165      ParamLoc = PV->getLocation();
2166    }
2167  }
2168
2169  if (!SecondArgIsLastNamedArgument)
2170    Diag(TheCall->getArg(1)->getLocStart(),
2171         diag::warn_second_parameter_of_va_start_not_last_named_argument);
2172  else if (Type->isReferenceType()) {
2173    Diag(Arg->getLocStart(),
2174         diag::warn_va_start_of_reference_type_is_undefined);
2175    Diag(ParamLoc, diag::note_parameter_type) << Type;
2176  }
2177
2178  TheCall->setType(Context.VoidTy);
2179  return false;
2180}
2181
2182bool Sema::SemaBuiltinVAStartARM(CallExpr *Call) {
2183  // void __va_start(va_list *ap, const char *named_addr, size_t slot_size,
2184  //                 const char *named_addr);
2185
2186  Expr *Func = Call->getCallee();
2187
2188  if (Call->getNumArgs() < 3)
2189    return Diag(Call->getLocEnd(),
2190                diag::err_typecheck_call_too_few_args_at_least)
2191           << 0 /*function call*/ << 3 << Call->getNumArgs();
2192
2193  // Determine whether the current function is variadic or not.
2194  bool IsVariadic;
2195  if (BlockScopeInfo *CurBlock = getCurBlock())
2196    IsVariadic = CurBlock->TheDecl->isVariadic();
2197  else if (FunctionDecl *FD = getCurFunctionDecl())
2198    IsVariadic = FD->isVariadic();
2199  else if (ObjCMethodDecl *MD = getCurMethodDecl())
2200    IsVariadic = MD->isVariadic();
2201  else
2202    llvm_unreachable("unexpected statement type");
2203
2204  if (!IsVariadic) {
2205    Diag(Func->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
2206    return true;
2207  }
2208
2209  // Type-check the first argument normally.
2210  if (checkBuiltinArgument(*this, Call, 0))
2211    return true;
2212
2213  const struct {
2214    unsigned ArgNo;
2215    QualType Type;
2216  } ArgumentTypes[] = {
2217    { 1, Context.getPointerType(Context.CharTy.withConst()) },
2218    { 2, Context.getSizeType() },
2219  };
2220
2221  for (const auto &AT : ArgumentTypes) {
2222    const Expr *Arg = Call->getArg(AT.ArgNo)->IgnoreParens();
2223    if (Arg->getType().getCanonicalType() == AT.Type.getCanonicalType())
2224      continue;
2225    Diag(Arg->getLocStart(), diag::err_typecheck_convert_incompatible)
2226      << Arg->getType() << AT.Type << 1 /* different class */
2227      << 0 /* qualifier difference */ << 3 /* parameter mismatch */
2228      << AT.ArgNo + 1 << Arg->getType() << AT.Type;
2229  }
2230
2231  return false;
2232}
2233
2234/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
2235/// friends.  This is declared to take (...), so we have to check everything.
2236bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
2237  if (TheCall->getNumArgs() < 2)
2238    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
2239      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
2240  if (TheCall->getNumArgs() > 2)
2241    return Diag(TheCall->getArg(2)->getLocStart(),
2242                diag::err_typecheck_call_too_many_args)
2243      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
2244      << SourceRange(TheCall->getArg(2)->getLocStart(),
2245                     (*(TheCall->arg_end()-1))->getLocEnd());
2246
2247  ExprResult OrigArg0 = TheCall->getArg(0);
2248  ExprResult OrigArg1 = TheCall->getArg(1);
2249
2250  // Do standard promotions between the two arguments, returning their common
2251  // type.
2252  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
2253  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
2254    return true;
2255
2256  // Make sure any conversions are pushed back into the call; this is
2257  // type safe since unordered compare builtins are declared as "_Bool
2258  // foo(...)".
2259  TheCall->setArg(0, OrigArg0.get());
2260  TheCall->setArg(1, OrigArg1.get());
2261
2262  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
2263    return false;
2264
2265  // If the common type isn't a real floating type, then the arguments were
2266  // invalid for this operation.
2267  if (Res.isNull() || !Res->isRealFloatingType())
2268    return Diag(OrigArg0.get()->getLocStart(),
2269                diag::err_typecheck_call_invalid_ordered_compare)
2270      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
2271      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
2272
2273  return false;
2274}
2275
2276/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
2277/// __builtin_isnan and friends.  This is declared to take (...), so we have
2278/// to check everything. We expect the last argument to be a floating point
2279/// value.
2280bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
2281  if (TheCall->getNumArgs() < NumArgs)
2282    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
2283      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
2284  if (TheCall->getNumArgs() > NumArgs)
2285    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
2286                diag::err_typecheck_call_too_many_args)
2287      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
2288      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
2289                     (*(TheCall->arg_end()-1))->getLocEnd());
2290
2291  Expr *OrigArg = TheCall->getArg(NumArgs-1);
2292
2293  if (OrigArg->isTypeDependent())
2294    return false;
2295
2296  // This operation requires a non-_Complex floating-point number.
2297  if (!OrigArg->getType()->isRealFloatingType())
2298    return Diag(OrigArg->getLocStart(),
2299                diag::err_typecheck_call_invalid_unary_fp)
2300      << OrigArg->getType() << OrigArg->getSourceRange();
2301
2302  // If this is an implicit conversion from float -> double, remove it.
2303  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
2304    Expr *CastArg = Cast->getSubExpr();
2305    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
2306      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
2307             "promotion from float to double is the only expected cast here");
2308      Cast->setSubExpr(nullptr);
2309      TheCall->setArg(NumArgs-1, CastArg);
2310    }
2311  }
2312
2313  return false;
2314}
2315
2316/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
2317// This is declared to take (...), so we have to check everything.
2318ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
2319  if (TheCall->getNumArgs() < 2)
2320    return ExprError(Diag(TheCall->getLocEnd(),
2321                          diag::err_typecheck_call_too_few_args_at_least)
2322                     << 0 /*function call*/ << 2 << TheCall->getNumArgs()
2323                     << TheCall->getSourceRange());
2324
2325  // Determine which of the following types of shufflevector we're checking:
2326  // 1) unary, vector mask: (lhs, mask)
2327  // 2) binary, vector mask: (lhs, rhs, mask)
2328  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
2329  QualType resType = TheCall->getArg(0)->getType();
2330  unsigned numElements = 0;
2331
2332  if (!TheCall->getArg(0)->isTypeDependent() &&
2333      !TheCall->getArg(1)->isTypeDependent()) {
2334    QualType LHSType = TheCall->getArg(0)->getType();
2335    QualType RHSType = TheCall->getArg(1)->getType();
2336
2337    if (!LHSType->isVectorType() || !RHSType->isVectorType())
2338      return ExprError(Diag(TheCall->getLocStart(),
2339                            diag::err_shufflevector_non_vector)
2340                       << SourceRange(TheCall->getArg(0)->getLocStart(),
2341                                      TheCall->getArg(1)->getLocEnd()));
2342
2343    numElements = LHSType->getAs<VectorType>()->getNumElements();
2344    unsigned numResElements = TheCall->getNumArgs() - 2;
2345
2346    // Check to see if we have a call with 2 vector arguments, the unary shuffle
2347    // with mask.  If so, verify that RHS is an integer vector type with the
2348    // same number of elts as lhs.
2349    if (TheCall->getNumArgs() == 2) {
2350      if (!RHSType->hasIntegerRepresentation() ||
2351          RHSType->getAs<VectorType>()->getNumElements() != numElements)
2352        return ExprError(Diag(TheCall->getLocStart(),
2353                              diag::err_shufflevector_incompatible_vector)
2354                         << SourceRange(TheCall->getArg(1)->getLocStart(),
2355                                        TheCall->getArg(1)->getLocEnd()));
2356    } else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
2357      return ExprError(Diag(TheCall->getLocStart(),
2358                            diag::err_shufflevector_incompatible_vector)
2359                       << SourceRange(TheCall->getArg(0)->getLocStart(),
2360                                      TheCall->getArg(1)->getLocEnd()));
2361    } else if (numElements != numResElements) {
2362      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
2363      resType = Context.getVectorType(eltType, numResElements,
2364                                      VectorType::GenericVector);
2365    }
2366  }
2367
2368  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
2369    if (TheCall->getArg(i)->isTypeDependent() ||
2370        TheCall->getArg(i)->isValueDependent())
2371      continue;
2372
2373    llvm::APSInt Result(32);
2374    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
2375      return ExprError(Diag(TheCall->getLocStart(),
2376                            diag::err_shufflevector_nonconstant_argument)
2377                       << TheCall->getArg(i)->getSourceRange());
2378
2379    // Allow -1 which will be translated to undef in the IR.
2380    if (Result.isSigned() && Result.isAllOnesValue())
2381      continue;
2382
2383    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
2384      return ExprError(Diag(TheCall->getLocStart(),
2385                            diag::err_shufflevector_argument_too_large)
2386                       << TheCall->getArg(i)->getSourceRange());
2387  }
2388
2389  SmallVector<Expr*, 32> exprs;
2390
2391  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
2392    exprs.push_back(TheCall->getArg(i));
2393    TheCall->setArg(i, nullptr);
2394  }
2395
2396  return new (Context) ShuffleVectorExpr(Context, exprs, resType,
2397                                         TheCall->getCallee()->getLocStart(),
2398                                         TheCall->getRParenLoc());
2399}
2400
2401/// SemaConvertVectorExpr - Handle __builtin_convertvector
2402ExprResult Sema::SemaConvertVectorExpr(Expr *E, TypeSourceInfo *TInfo,
2403                                       SourceLocation BuiltinLoc,
2404                                       SourceLocation RParenLoc) {
2405  ExprValueKind VK = VK_RValue;
2406  ExprObjectKind OK = OK_Ordinary;
2407  QualType DstTy = TInfo->getType();
2408  QualType SrcTy = E->getType();
2409
2410  if (!SrcTy->isVectorType() && !SrcTy->isDependentType())
2411    return ExprError(Diag(BuiltinLoc,
2412                          diag::err_convertvector_non_vector)
2413                     << E->getSourceRange());
2414  if (!DstTy->isVectorType() && !DstTy->isDependentType())
2415    return ExprError(Diag(BuiltinLoc,
2416                          diag::err_convertvector_non_vector_type));
2417
2418  if (!SrcTy->isDependentType() && !DstTy->isDependentType()) {
2419    unsigned SrcElts = SrcTy->getAs<VectorType>()->getNumElements();
2420    unsigned DstElts = DstTy->getAs<VectorType>()->getNumElements();
2421    if (SrcElts != DstElts)
2422      return ExprError(Diag(BuiltinLoc,
2423                            diag::err_convertvector_incompatible_vector)
2424                       << E->getSourceRange());
2425  }
2426
2427  return new (Context)
2428      ConvertVectorExpr(E, TInfo, DstTy, VK, OK, BuiltinLoc, RParenLoc);
2429}
2430
2431/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
2432// This is declared to take (const void*, ...) and can take two
2433// optional constant int args.
2434bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
2435  unsigned NumArgs = TheCall->getNumArgs();
2436
2437  if (NumArgs > 3)
2438    return Diag(TheCall->getLocEnd(),
2439             diag::err_typecheck_call_too_many_args_at_most)
2440             << 0 /*function call*/ << 3 << NumArgs
2441             << TheCall->getSourceRange();
2442
2443  // Argument 0 is checked for us and the remaining arguments must be
2444  // constant integers.
2445  for (unsigned i = 1; i != NumArgs; ++i)
2446    if (SemaBuiltinConstantArgRange(TheCall, i, 0, i == 1 ? 1 : 3))
2447      return true;
2448
2449  return false;
2450}
2451
2452/// SemaBuiltinAssume - Handle __assume (MS Extension).
2453// __assume does not evaluate its arguments, and should warn if its argument
2454// has side effects.
2455bool Sema::SemaBuiltinAssume(CallExpr *TheCall) {
2456  Expr *Arg = TheCall->getArg(0);
2457  if (Arg->isInstantiationDependent()) return false;
2458
2459  if (Arg->HasSideEffects(Context))
2460    Diag(Arg->getLocStart(), diag::warn_assume_side_effects)
2461      << Arg->getSourceRange()
2462      << cast<FunctionDecl>(TheCall->getCalleeDecl())->getIdentifier();
2463
2464  return false;
2465}
2466
2467/// Handle __builtin_assume_aligned. This is declared
2468/// as (const void*, size_t, ...) and can take one optional constant int arg.
2469bool Sema::SemaBuiltinAssumeAligned(CallExpr *TheCall) {
2470  unsigned NumArgs = TheCall->getNumArgs();
2471
2472  if (NumArgs > 3)
2473    return Diag(TheCall->getLocEnd(),
2474             diag::err_typecheck_call_too_many_args_at_most)
2475             << 0 /*function call*/ << 3 << NumArgs
2476             << TheCall->getSourceRange();
2477
2478  // The alignment must be a constant integer.
2479  Expr *Arg = TheCall->getArg(1);
2480
2481  // We can't check the value of a dependent argument.
2482  if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
2483    llvm::APSInt Result;
2484    if (SemaBuiltinConstantArg(TheCall, 1, Result))
2485      return true;
2486
2487    if (!Result.isPowerOf2())
2488      return Diag(TheCall->getLocStart(),
2489                  diag::err_alignment_not_power_of_two)
2490           << Arg->getSourceRange();
2491  }
2492
2493  if (NumArgs > 2) {
2494    ExprResult Arg(TheCall->getArg(2));
2495    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
2496      Context.getSizeType(), false);
2497    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
2498    if (Arg.isInvalid()) return true;
2499    TheCall->setArg(2, Arg.get());
2500  }
2501
2502  return false;
2503}
2504
2505/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
2506/// TheCall is a constant expression.
2507bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
2508                                  llvm::APSInt &Result) {
2509  Expr *Arg = TheCall->getArg(ArgNum);
2510  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
2511  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
2512
2513  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
2514
2515  if (!Arg->isIntegerConstantExpr(Result, Context))
2516    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
2517                << FDecl->getDeclName() <<  Arg->getSourceRange();
2518
2519  return false;
2520}
2521
2522/// SemaBuiltinConstantArgRange - Handle a check if argument ArgNum of CallExpr
2523/// TheCall is a constant expression in the range [Low, High].
2524bool Sema::SemaBuiltinConstantArgRange(CallExpr *TheCall, int ArgNum,
2525                                       int Low, int High) {
2526  llvm::APSInt Result;
2527
2528  // We can't check the value of a dependent argument.
2529  Expr *Arg = TheCall->getArg(ArgNum);
2530  if (Arg->isTypeDependent() || Arg->isValueDependent())
2531    return false;
2532
2533  // Check constant-ness first.
2534  if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
2535    return true;
2536
2537  if (Result.getSExtValue() < Low || Result.getSExtValue() > High)
2538    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
2539      << Low << High << Arg->getSourceRange();
2540
2541  return false;
2542}
2543
2544/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
2545/// This checks that the target supports __builtin_longjmp and
2546/// that val is a constant 1.
2547bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
2548  if (!Context.getTargetInfo().hasSjLjLowering())
2549    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_unsupported)
2550             << SourceRange(TheCall->getLocStart(), TheCall->getLocEnd());
2551
2552  Expr *Arg = TheCall->getArg(1);
2553  llvm::APSInt Result;
2554
2555  // TODO: This is less than ideal. Overload this to take a value.
2556  if (SemaBuiltinConstantArg(TheCall, 1, Result))
2557    return true;
2558
2559  if (Result != 1)
2560    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
2561             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
2562
2563  return false;
2564}
2565
2566
2567/// SemaBuiltinSetjmp - Handle __builtin_setjmp(void *env[5]).
2568/// This checks that the target supports __builtin_setjmp.
2569bool Sema::SemaBuiltinSetjmp(CallExpr *TheCall) {
2570  if (!Context.getTargetInfo().hasSjLjLowering())
2571    return Diag(TheCall->getLocStart(), diag::err_builtin_setjmp_unsupported)
2572             << SourceRange(TheCall->getLocStart(), TheCall->getLocEnd());
2573  return false;
2574}
2575
2576namespace {
2577enum StringLiteralCheckType {
2578  SLCT_NotALiteral,
2579  SLCT_UncheckedLiteral,
2580  SLCT_CheckedLiteral
2581};
2582}
2583
2584// Determine if an expression is a string literal or constant string.
2585// If this function returns false on the arguments to a function expecting a
2586// format string, we will usually need to emit a warning.
2587// True string literals are then checked by CheckFormatString.
2588static StringLiteralCheckType
2589checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
2590                      bool HasVAListArg, unsigned format_idx,
2591                      unsigned firstDataArg, Sema::FormatStringType Type,
2592                      Sema::VariadicCallType CallType, bool InFunctionCall,
2593                      llvm::SmallBitVector &CheckedVarArgs) {
2594 tryAgain:
2595  if (E->isTypeDependent() || E->isValueDependent())
2596    return SLCT_NotALiteral;
2597
2598  E = E->IgnoreParenCasts();
2599
2600  if (E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull))
2601    // Technically -Wformat-nonliteral does not warn about this case.
2602    // The behavior of printf and friends in this case is implementation
2603    // dependent.  Ideally if the format string cannot be null then
2604    // it should have a 'nonnull' attribute in the function prototype.
2605    return SLCT_UncheckedLiteral;
2606
2607  switch (E->getStmtClass()) {
2608  case Stmt::BinaryConditionalOperatorClass:
2609  case Stmt::ConditionalOperatorClass: {
2610    // The expression is a literal if both sub-expressions were, and it was
2611    // completely checked only if both sub-expressions were checked.
2612    const AbstractConditionalOperator *C =
2613        cast<AbstractConditionalOperator>(E);
2614    StringLiteralCheckType Left =
2615        checkFormatStringExpr(S, C->getTrueExpr(), Args,
2616                              HasVAListArg, format_idx, firstDataArg,
2617                              Type, CallType, InFunctionCall, CheckedVarArgs);
2618    if (Left == SLCT_NotALiteral)
2619      return SLCT_NotALiteral;
2620    StringLiteralCheckType Right =
2621        checkFormatStringExpr(S, C->getFalseExpr(), Args,
2622                              HasVAListArg, format_idx, firstDataArg,
2623                              Type, CallType, InFunctionCall, CheckedVarArgs);
2624    return Left < Right ? Left : Right;
2625  }
2626
2627  case Stmt::ImplicitCastExprClass: {
2628    E = cast<ImplicitCastExpr>(E)->getSubExpr();
2629    goto tryAgain;
2630  }
2631
2632  case Stmt::OpaqueValueExprClass:
2633    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
2634      E = src;
2635      goto tryAgain;
2636    }
2637    return SLCT_NotALiteral;
2638
2639  case Stmt::PredefinedExprClass:
2640    // While __func__, etc., are technically not string literals, they
2641    // cannot contain format specifiers and thus are not a security
2642    // liability.
2643    return SLCT_UncheckedLiteral;
2644
2645  case Stmt::DeclRefExprClass: {
2646    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
2647
2648    // As an exception, do not flag errors for variables binding to
2649    // const string literals.
2650    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
2651      bool isConstant = false;
2652      QualType T = DR->getType();
2653
2654      if (const ArrayType *AT = S.Context.getAsArrayType(T)) {
2655        isConstant = AT->getElementType().isConstant(S.Context);
2656      } else if (const PointerType *PT = T->getAs<PointerType>()) {
2657        isConstant = T.isConstant(S.Context) &&
2658                     PT->getPointeeType().isConstant(S.Context);
2659      } else if (T->isObjCObjectPointerType()) {
2660        // In ObjC, there is usually no "const ObjectPointer" type,
2661        // so don't check if the pointee type is constant.
2662        isConstant = T.isConstant(S.Context);
2663      }
2664
2665      if (isConstant) {
2666        if (const Expr *Init = VD->getAnyInitializer()) {
2667          // Look through initializers like const char c[] = { "foo" }
2668          if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
2669            if (InitList->isStringLiteralInit())
2670              Init = InitList->getInit(0)->IgnoreParenImpCasts();
2671          }
2672          return checkFormatStringExpr(S, Init, Args,
2673                                       HasVAListArg, format_idx,
2674                                       firstDataArg, Type, CallType,
2675                                       /*InFunctionCall*/false, CheckedVarArgs);
2676        }
2677      }
2678
2679      // For vprintf* functions (i.e., HasVAListArg==true), we add a
2680      // special check to see if the format string is a function parameter
2681      // of the function calling the printf function.  If the function
2682      // has an attribute indicating it is a printf-like function, then we
2683      // should suppress warnings concerning non-literals being used in a call
2684      // to a vprintf function.  For example:
2685      //
2686      // void
2687      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
2688      //      va_list ap;
2689      //      va_start(ap, fmt);
2690      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
2691      //      ...
2692      // }
2693      if (HasVAListArg) {
2694        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
2695          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
2696            int PVIndex = PV->getFunctionScopeIndex() + 1;
2697            for (const auto *PVFormat : ND->specific_attrs<FormatAttr>()) {
2698              // adjust for implicit parameter
2699              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
2700                if (MD->isInstance())
2701                  ++PVIndex;
2702              // We also check if the formats are compatible.
2703              // We can't pass a 'scanf' string to a 'printf' function.
2704              if (PVIndex == PVFormat->getFormatIdx() &&
2705                  Type == S.GetFormatStringType(PVFormat))
2706                return SLCT_UncheckedLiteral;
2707            }
2708          }
2709        }
2710      }
2711    }
2712
2713    return SLCT_NotALiteral;
2714  }
2715
2716  case Stmt::CallExprClass:
2717  case Stmt::CXXMemberCallExprClass: {
2718    const CallExpr *CE = cast<CallExpr>(E);
2719    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
2720      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
2721        unsigned ArgIndex = FA->getFormatIdx();
2722        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
2723          if (MD->isInstance())
2724            --ArgIndex;
2725        const Expr *Arg = CE->getArg(ArgIndex - 1);
2726
2727        return checkFormatStringExpr(S, Arg, Args,
2728                                     HasVAListArg, format_idx, firstDataArg,
2729                                     Type, CallType, InFunctionCall,
2730                                     CheckedVarArgs);
2731      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
2732        unsigned BuiltinID = FD->getBuiltinID();
2733        if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
2734            BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
2735          const Expr *Arg = CE->getArg(0);
2736          return checkFormatStringExpr(S, Arg, Args,
2737                                       HasVAListArg, format_idx,
2738                                       firstDataArg, Type, CallType,
2739                                       InFunctionCall, CheckedVarArgs);
2740        }
2741      }
2742    }
2743
2744    return SLCT_NotALiteral;
2745  }
2746  case Stmt::ObjCStringLiteralClass:
2747  case Stmt::StringLiteralClass: {
2748    const StringLiteral *StrE = nullptr;
2749
2750    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
2751      StrE = ObjCFExpr->getString();
2752    else
2753      StrE = cast<StringLiteral>(E);
2754
2755    if (StrE) {
2756      S.CheckFormatString(StrE, E, Args, HasVAListArg, format_idx, firstDataArg,
2757                          Type, InFunctionCall, CallType, CheckedVarArgs);
2758      return SLCT_CheckedLiteral;
2759    }
2760
2761    return SLCT_NotALiteral;
2762  }
2763
2764  default:
2765    return SLCT_NotALiteral;
2766  }
2767}
2768
2769Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
2770  return llvm::StringSwitch<FormatStringType>(Format->getType()->getName())
2771  .Case("scanf", FST_Scanf)
2772  .Cases("printf", "printf0", FST_Printf)
2773  .Cases("NSString", "CFString", FST_NSString)
2774  .Case("strftime", FST_Strftime)
2775  .Case("strfmon", FST_Strfmon)
2776  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
2777  .Case("freebsd_kprintf", FST_FreeBSDKPrintf)
2778  .Case("os_trace", FST_OSTrace)
2779  .Default(FST_Unknown);
2780}
2781
2782/// CheckFormatArguments - Check calls to printf and scanf (and similar
2783/// functions) for correct use of format strings.
2784/// Returns true if a format string has been fully checked.
2785bool Sema::CheckFormatArguments(const FormatAttr *Format,
2786                                ArrayRef<const Expr *> Args,
2787                                bool IsCXXMember,
2788                                VariadicCallType CallType,
2789                                SourceLocation Loc, SourceRange Range,
2790                                llvm::SmallBitVector &CheckedVarArgs) {
2791  FormatStringInfo FSI;
2792  if (getFormatStringInfo(Format, IsCXXMember, &FSI))
2793    return CheckFormatArguments(Args, FSI.HasVAListArg, FSI.FormatIdx,
2794                                FSI.FirstDataArg, GetFormatStringType(Format),
2795                                CallType, Loc, Range, CheckedVarArgs);
2796  return false;
2797}
2798
2799bool Sema::CheckFormatArguments(ArrayRef<const Expr *> Args,
2800                                bool HasVAListArg, unsigned format_idx,
2801                                unsigned firstDataArg, FormatStringType Type,
2802                                VariadicCallType CallType,
2803                                SourceLocation Loc, SourceRange Range,
2804                                llvm::SmallBitVector &CheckedVarArgs) {
2805  // CHECK: printf/scanf-like function is called with no format string.
2806  if (format_idx >= Args.size()) {
2807    Diag(Loc, diag::warn_missing_format_string) << Range;
2808    return false;
2809  }
2810
2811  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
2812
2813  // CHECK: format string is not a string literal.
2814  //
2815  // Dynamically generated format strings are difficult to
2816  // automatically vet at compile time.  Requiring that format strings
2817  // are string literals: (1) permits the checking of format strings by
2818  // the compiler and thereby (2) can practically remove the source of
2819  // many format string exploits.
2820
2821  // Format string can be either ObjC string (e.g. @"%d") or
2822  // C string (e.g. "%d")
2823  // ObjC string uses the same format specifiers as C string, so we can use
2824  // the same format string checking logic for both ObjC and C strings.
2825  StringLiteralCheckType CT =
2826      checkFormatStringExpr(*this, OrigFormatExpr, Args, HasVAListArg,
2827                            format_idx, firstDataArg, Type, CallType,
2828                            /*IsFunctionCall*/true, CheckedVarArgs);
2829  if (CT != SLCT_NotALiteral)
2830    // Literal format string found, check done!
2831    return CT == SLCT_CheckedLiteral;
2832
2833  // Strftime is particular as it always uses a single 'time' argument,
2834  // so it is safe to pass a non-literal string.
2835  if (Type == FST_Strftime)
2836    return false;
2837
2838  // Do not emit diag when the string param is a macro expansion and the
2839  // format is either NSString or CFString. This is a hack to prevent
2840  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
2841  // which are usually used in place of NS and CF string literals.
2842  if (Type == FST_NSString &&
2843      SourceMgr.isInSystemMacro(Args[format_idx]->getLocStart()))
2844    return false;
2845
2846  // If there are no arguments specified, warn with -Wformat-security, otherwise
2847  // warn only with -Wformat-nonliteral.
2848  if (Args.size() == firstDataArg)
2849    Diag(Args[format_idx]->getLocStart(),
2850         diag::warn_format_nonliteral_noargs)
2851      << OrigFormatExpr->getSourceRange();
2852  else
2853    Diag(Args[format_idx]->getLocStart(),
2854         diag::warn_format_nonliteral)
2855           << OrigFormatExpr->getSourceRange();
2856  return false;
2857}
2858
2859namespace {
2860class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
2861protected:
2862  Sema &S;
2863  const StringLiteral *FExpr;
2864  const Expr *OrigFormatExpr;
2865  const unsigned FirstDataArg;
2866  const unsigned NumDataArgs;
2867  const char *Beg; // Start of format string.
2868  const bool HasVAListArg;
2869  ArrayRef<const Expr *> Args;
2870  unsigned FormatIdx;
2871  llvm::SmallBitVector CoveredArgs;
2872  bool usesPositionalArgs;
2873  bool atFirstArg;
2874  bool inFunctionCall;
2875  Sema::VariadicCallType CallType;
2876  llvm::SmallBitVector &CheckedVarArgs;
2877public:
2878  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
2879                     const Expr *origFormatExpr, unsigned firstDataArg,
2880                     unsigned numDataArgs, const char *beg, bool hasVAListArg,
2881                     ArrayRef<const Expr *> Args,
2882                     unsigned formatIdx, bool inFunctionCall,
2883                     Sema::VariadicCallType callType,
2884                     llvm::SmallBitVector &CheckedVarArgs)
2885    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
2886      FirstDataArg(firstDataArg), NumDataArgs(numDataArgs),
2887      Beg(beg), HasVAListArg(hasVAListArg),
2888      Args(Args), FormatIdx(formatIdx),
2889      usesPositionalArgs(false), atFirstArg(true),
2890      inFunctionCall(inFunctionCall), CallType(callType),
2891      CheckedVarArgs(CheckedVarArgs) {
2892    CoveredArgs.resize(numDataArgs);
2893    CoveredArgs.reset();
2894  }
2895
2896  void DoneProcessing();
2897
2898  void HandleIncompleteSpecifier(const char *startSpecifier,
2899                                 unsigned specifierLen) override;
2900
2901  void HandleInvalidLengthModifier(
2902                           const analyze_format_string::FormatSpecifier &FS,
2903                           const analyze_format_string::ConversionSpecifier &CS,
2904                           const char *startSpecifier, unsigned specifierLen,
2905                           unsigned DiagID);
2906
2907  void HandleNonStandardLengthModifier(
2908                    const analyze_format_string::FormatSpecifier &FS,
2909                    const char *startSpecifier, unsigned specifierLen);
2910
2911  void HandleNonStandardConversionSpecifier(
2912                    const analyze_format_string::ConversionSpecifier &CS,
2913                    const char *startSpecifier, unsigned specifierLen);
2914
2915  void HandlePosition(const char *startPos, unsigned posLen) override;
2916
2917  void HandleInvalidPosition(const char *startSpecifier,
2918                             unsigned specifierLen,
2919                             analyze_format_string::PositionContext p) override;
2920
2921  void HandleZeroPosition(const char *startPos, unsigned posLen) override;
2922
2923  void HandleNullChar(const char *nullCharacter) override;
2924
2925  template <typename Range>
2926  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
2927                                   const Expr *ArgumentExpr,
2928                                   PartialDiagnostic PDiag,
2929                                   SourceLocation StringLoc,
2930                                   bool IsStringLocation, Range StringRange,
2931                                   ArrayRef<FixItHint> Fixit = None);
2932
2933protected:
2934  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
2935                                        const char *startSpec,
2936                                        unsigned specifierLen,
2937                                        const char *csStart, unsigned csLen);
2938
2939  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
2940                                         const char *startSpec,
2941                                         unsigned specifierLen);
2942
2943  SourceRange getFormatStringRange();
2944  CharSourceRange getSpecifierRange(const char *startSpecifier,
2945                                    unsigned specifierLen);
2946  SourceLocation getLocationOfByte(const char *x);
2947
2948  const Expr *getDataArg(unsigned i) const;
2949
2950  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
2951                    const analyze_format_string::ConversionSpecifier &CS,
2952                    const char *startSpecifier, unsigned specifierLen,
2953                    unsigned argIndex);
2954
2955  template <typename Range>
2956  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
2957                            bool IsStringLocation, Range StringRange,
2958                            ArrayRef<FixItHint> Fixit = None);
2959};
2960}
2961
2962SourceRange CheckFormatHandler::getFormatStringRange() {
2963  return OrigFormatExpr->getSourceRange();
2964}
2965
2966CharSourceRange CheckFormatHandler::
2967getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
2968  SourceLocation Start = getLocationOfByte(startSpecifier);
2969  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
2970
2971  // Advance the end SourceLocation by one due to half-open ranges.
2972  End = End.getLocWithOffset(1);
2973
2974  return CharSourceRange::getCharRange(Start, End);
2975}
2976
2977SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
2978  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
2979}
2980
2981void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
2982                                                   unsigned specifierLen){
2983  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
2984                       getLocationOfByte(startSpecifier),
2985                       /*IsStringLocation*/true,
2986                       getSpecifierRange(startSpecifier, specifierLen));
2987}
2988
2989void CheckFormatHandler::HandleInvalidLengthModifier(
2990    const analyze_format_string::FormatSpecifier &FS,
2991    const analyze_format_string::ConversionSpecifier &CS,
2992    const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
2993  using namespace analyze_format_string;
2994
2995  const LengthModifier &LM = FS.getLengthModifier();
2996  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
2997
2998  // See if we know how to fix this length modifier.
2999  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
3000  if (FixedLM) {
3001    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
3002                         getLocationOfByte(LM.getStart()),
3003                         /*IsStringLocation*/true,
3004                         getSpecifierRange(startSpecifier, specifierLen));
3005
3006    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
3007      << FixedLM->toString()
3008      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
3009
3010  } else {
3011    FixItHint Hint;
3012    if (DiagID == diag::warn_format_nonsensical_length)
3013      Hint = FixItHint::CreateRemoval(LMRange);
3014
3015    EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
3016                         getLocationOfByte(LM.getStart()),
3017                         /*IsStringLocation*/true,
3018                         getSpecifierRange(startSpecifier, specifierLen),
3019                         Hint);
3020  }
3021}
3022
3023void CheckFormatHandler::HandleNonStandardLengthModifier(
3024    const analyze_format_string::FormatSpecifier &FS,
3025    const char *startSpecifier, unsigned specifierLen) {
3026  using namespace analyze_format_string;
3027
3028  const LengthModifier &LM = FS.getLengthModifier();
3029  CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
3030
3031  // See if we know how to fix this length modifier.
3032  Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
3033  if (FixedLM) {
3034    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
3035                           << LM.toString() << 0,
3036                         getLocationOfByte(LM.getStart()),
3037                         /*IsStringLocation*/true,
3038                         getSpecifierRange(startSpecifier, specifierLen));
3039
3040    S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
3041      << FixedLM->toString()
3042      << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
3043
3044  } else {
3045    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
3046                           << LM.toString() << 0,
3047                         getLocationOfByte(LM.getStart()),
3048                         /*IsStringLocation*/true,
3049                         getSpecifierRange(startSpecifier, specifierLen));
3050  }
3051}
3052
3053void CheckFormatHandler::HandleNonStandardConversionSpecifier(
3054    const analyze_format_string::ConversionSpecifier &CS,
3055    const char *startSpecifier, unsigned specifierLen) {
3056  using namespace analyze_format_string;
3057
3058  // See if we know how to fix this conversion specifier.
3059  Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
3060  if (FixedCS) {
3061    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
3062                          << CS.toString() << /*conversion specifier*/1,
3063                         getLocationOfByte(CS.getStart()),
3064                         /*IsStringLocation*/true,
3065                         getSpecifierRange(startSpecifier, specifierLen));
3066
3067    CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
3068    S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
3069      << FixedCS->toString()
3070      << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
3071  } else {
3072    EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
3073                          << CS.toString() << /*conversion specifier*/1,
3074                         getLocationOfByte(CS.getStart()),
3075                         /*IsStringLocation*/true,
3076                         getSpecifierRange(startSpecifier, specifierLen));
3077  }
3078}
3079
3080void CheckFormatHandler::HandlePosition(const char *startPos,
3081                                        unsigned posLen) {
3082  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
3083                               getLocationOfByte(startPos),
3084                               /*IsStringLocation*/true,
3085                               getSpecifierRange(startPos, posLen));
3086}
3087
3088void
3089CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
3090                                     analyze_format_string::PositionContext p) {
3091  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
3092                         << (unsigned) p,
3093                       getLocationOfByte(startPos), /*IsStringLocation*/true,
3094                       getSpecifierRange(startPos, posLen));
3095}
3096
3097void CheckFormatHandler::HandleZeroPosition(const char *startPos,
3098                                            unsigned posLen) {
3099  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
3100                               getLocationOfByte(startPos),
3101                               /*IsStringLocation*/true,
3102                               getSpecifierRange(startPos, posLen));
3103}
3104
3105void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
3106  if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
3107    // The presence of a null character is likely an error.
3108    EmitFormatDiagnostic(
3109      S.PDiag(diag::warn_printf_format_string_contains_null_char),
3110      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
3111      getFormatStringRange());
3112  }
3113}
3114
3115// Note that this may return NULL if there was an error parsing or building
3116// one of the argument expressions.
3117const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
3118  return Args[FirstDataArg + i];
3119}
3120
3121void CheckFormatHandler::DoneProcessing() {
3122    // Does the number of data arguments exceed the number of
3123    // format conversions in the format string?
3124  if (!HasVAListArg) {
3125      // Find any arguments that weren't covered.
3126    CoveredArgs.flip();
3127    signed notCoveredArg = CoveredArgs.find_first();
3128    if (notCoveredArg >= 0) {
3129      assert((unsigned)notCoveredArg < NumDataArgs);
3130      if (const Expr *E = getDataArg((unsigned) notCoveredArg)) {
3131        SourceLocation Loc = E->getLocStart();
3132        if (!S.getSourceManager().isInSystemMacro(Loc)) {
3133          EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
3134                               Loc, /*IsStringLocation*/false,
3135                               getFormatStringRange());
3136        }
3137      }
3138    }
3139  }
3140}
3141
3142bool
3143CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
3144                                                     SourceLocation Loc,
3145                                                     const char *startSpec,
3146                                                     unsigned specifierLen,
3147                                                     const char *csStart,
3148                                                     unsigned csLen) {
3149
3150  bool keepGoing = true;
3151  if (argIndex < NumDataArgs) {
3152    // Consider the argument coverered, even though the specifier doesn't
3153    // make sense.
3154    CoveredArgs.set(argIndex);
3155  }
3156  else {
3157    // If argIndex exceeds the number of data arguments we
3158    // don't issue a warning because that is just a cascade of warnings (and
3159    // they may have intended '%%' anyway). We don't want to continue processing
3160    // the format string after this point, however, as we will like just get
3161    // gibberish when trying to match arguments.
3162    keepGoing = false;
3163  }
3164
3165  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
3166                         << StringRef(csStart, csLen),
3167                       Loc, /*IsStringLocation*/true,
3168                       getSpecifierRange(startSpec, specifierLen));
3169
3170  return keepGoing;
3171}
3172
3173void
3174CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
3175                                                      const char *startSpec,
3176                                                      unsigned specifierLen) {
3177  EmitFormatDiagnostic(
3178    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
3179    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
3180}
3181
3182bool
3183CheckFormatHandler::CheckNumArgs(
3184  const analyze_format_string::FormatSpecifier &FS,
3185  const analyze_format_string::ConversionSpecifier &CS,
3186  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
3187
3188  if (argIndex >= NumDataArgs) {
3189    PartialDiagnostic PDiag = FS.usesPositionalArg()
3190      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
3191           << (argIndex+1) << NumDataArgs)
3192      : S.PDiag(diag::warn_printf_insufficient_data_args);
3193    EmitFormatDiagnostic(
3194      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
3195      getSpecifierRange(startSpecifier, specifierLen));
3196    return false;
3197  }
3198  return true;
3199}
3200
3201template<typename Range>
3202void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
3203                                              SourceLocation Loc,
3204                                              bool IsStringLocation,
3205                                              Range StringRange,
3206                                              ArrayRef<FixItHint> FixIt) {
3207  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
3208                       Loc, IsStringLocation, StringRange, FixIt);
3209}
3210
3211/// \brief If the format string is not within the funcion call, emit a note
3212/// so that the function call and string are in diagnostic messages.
3213///
3214/// \param InFunctionCall if true, the format string is within the function
3215/// call and only one diagnostic message will be produced.  Otherwise, an
3216/// extra note will be emitted pointing to location of the format string.
3217///
3218/// \param ArgumentExpr the expression that is passed as the format string
3219/// argument in the function call.  Used for getting locations when two
3220/// diagnostics are emitted.
3221///
3222/// \param PDiag the callee should already have provided any strings for the
3223/// diagnostic message.  This function only adds locations and fixits
3224/// to diagnostics.
3225///
3226/// \param Loc primary location for diagnostic.  If two diagnostics are
3227/// required, one will be at Loc and a new SourceLocation will be created for
3228/// the other one.
3229///
3230/// \param IsStringLocation if true, Loc points to the format string should be
3231/// used for the note.  Otherwise, Loc points to the argument list and will
3232/// be used with PDiag.
3233///
3234/// \param StringRange some or all of the string to highlight.  This is
3235/// templated so it can accept either a CharSourceRange or a SourceRange.
3236///
3237/// \param FixIt optional fix it hint for the format string.
3238template<typename Range>
3239void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
3240                                              const Expr *ArgumentExpr,
3241                                              PartialDiagnostic PDiag,
3242                                              SourceLocation Loc,
3243                                              bool IsStringLocation,
3244                                              Range StringRange,
3245                                              ArrayRef<FixItHint> FixIt) {
3246  if (InFunctionCall) {
3247    const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
3248    D << StringRange;
3249    D << FixIt;
3250  } else {
3251    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
3252      << ArgumentExpr->getSourceRange();
3253
3254    const Sema::SemaDiagnosticBuilder &Note =
3255      S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
3256             diag::note_format_string_defined);
3257
3258    Note << StringRange;
3259    Note << FixIt;
3260  }
3261}
3262
3263//===--- CHECK: Printf format string checking ------------------------------===//
3264
3265namespace {
3266class CheckPrintfHandler : public CheckFormatHandler {
3267  bool ObjCContext;
3268public:
3269  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
3270                     const Expr *origFormatExpr, unsigned firstDataArg,
3271                     unsigned numDataArgs, bool isObjC,
3272                     const char *beg, bool hasVAListArg,
3273                     ArrayRef<const Expr *> Args,
3274                     unsigned formatIdx, bool inFunctionCall,
3275                     Sema::VariadicCallType CallType,
3276                     llvm::SmallBitVector &CheckedVarArgs)
3277    : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
3278                         numDataArgs, beg, hasVAListArg, Args,
3279                         formatIdx, inFunctionCall, CallType, CheckedVarArgs),
3280      ObjCContext(isObjC)
3281  {}
3282
3283
3284  bool HandleInvalidPrintfConversionSpecifier(
3285                                      const analyze_printf::PrintfSpecifier &FS,
3286                                      const char *startSpecifier,
3287                                      unsigned specifierLen) override;
3288
3289  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
3290                             const char *startSpecifier,
3291                             unsigned specifierLen) override;
3292  bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
3293                       const char *StartSpecifier,
3294                       unsigned SpecifierLen,
3295                       const Expr *E);
3296
3297  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
3298                    const char *startSpecifier, unsigned specifierLen);
3299  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
3300                           const analyze_printf::OptionalAmount &Amt,
3301                           unsigned type,
3302                           const char *startSpecifier, unsigned specifierLen);
3303  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
3304                  const analyze_printf::OptionalFlag &flag,
3305                  const char *startSpecifier, unsigned specifierLen);
3306  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
3307                         const analyze_printf::OptionalFlag &ignoredFlag,
3308                         const analyze_printf::OptionalFlag &flag,
3309                         const char *startSpecifier, unsigned specifierLen);
3310  bool checkForCStrMembers(const analyze_printf::ArgType &AT,
3311                           const Expr *E);
3312
3313};
3314}
3315
3316bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
3317                                      const analyze_printf::PrintfSpecifier &FS,
3318                                      const char *startSpecifier,
3319                                      unsigned specifierLen) {
3320  const analyze_printf::PrintfConversionSpecifier &CS =
3321    FS.getConversionSpecifier();
3322
3323  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
3324                                          getLocationOfByte(CS.getStart()),
3325                                          startSpecifier, specifierLen,
3326                                          CS.getStart(), CS.getLength());
3327}
3328
3329bool CheckPrintfHandler::HandleAmount(
3330                               const analyze_format_string::OptionalAmount &Amt,
3331                               unsigned k, const char *startSpecifier,
3332                               unsigned specifierLen) {
3333
3334  if (Amt.hasDataArgument()) {
3335    if (!HasVAListArg) {
3336      unsigned argIndex = Amt.getArgIndex();
3337      if (argIndex >= NumDataArgs) {
3338        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
3339                               << k,
3340                             getLocationOfByte(Amt.getStart()),
3341                             /*IsStringLocation*/true,
3342                             getSpecifierRange(startSpecifier, specifierLen));
3343        // Don't do any more checking.  We will just emit
3344        // spurious errors.
3345        return false;
3346      }
3347
3348      // Type check the data argument.  It should be an 'int'.
3349      // Although not in conformance with C99, we also allow the argument to be
3350      // an 'unsigned int' as that is a reasonably safe case.  GCC also
3351      // doesn't emit a warning for that case.
3352      CoveredArgs.set(argIndex);
3353      const Expr *Arg = getDataArg(argIndex);
3354      if (!Arg)
3355        return false;
3356
3357      QualType T = Arg->getType();
3358
3359      const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
3360      assert(AT.isValid());
3361
3362      if (!AT.matchesType(S.Context, T)) {
3363        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
3364                               << k << AT.getRepresentativeTypeName(S.Context)
3365                               << T << Arg->getSourceRange(),
3366                             getLocationOfByte(Amt.getStart()),
3367                             /*IsStringLocation*/true,
3368                             getSpecifierRange(startSpecifier, specifierLen));
3369        // Don't do any more checking.  We will just emit
3370        // spurious errors.
3371        return false;
3372      }
3373    }
3374  }
3375  return true;
3376}
3377
3378void CheckPrintfHandler::HandleInvalidAmount(
3379                                      const analyze_printf::PrintfSpecifier &FS,
3380                                      const analyze_printf::OptionalAmount &Amt,
3381                                      unsigned type,
3382                                      const char *startSpecifier,
3383                                      unsigned specifierLen) {
3384  const analyze_printf::PrintfConversionSpecifier &CS =
3385    FS.getConversionSpecifier();
3386
3387  FixItHint fixit =
3388    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
3389      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
3390                                 Amt.getConstantLength()))
3391      : FixItHint();
3392
3393  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
3394                         << type << CS.toString(),
3395                       getLocationOfByte(Amt.getStart()),
3396                       /*IsStringLocation*/true,
3397                       getSpecifierRange(startSpecifier, specifierLen),
3398                       fixit);
3399}
3400
3401void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
3402                                    const analyze_printf::OptionalFlag &flag,
3403                                    const char *startSpecifier,
3404                                    unsigned specifierLen) {
3405  // Warn about pointless flag with a fixit removal.
3406  const analyze_printf::PrintfConversionSpecifier &CS =
3407    FS.getConversionSpecifier();
3408  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
3409                         << flag.toString() << CS.toString(),
3410                       getLocationOfByte(flag.getPosition()),
3411                       /*IsStringLocation*/true,
3412                       getSpecifierRange(startSpecifier, specifierLen),
3413                       FixItHint::CreateRemoval(
3414                         getSpecifierRange(flag.getPosition(), 1)));
3415}
3416
3417void CheckPrintfHandler::HandleIgnoredFlag(
3418                                const analyze_printf::PrintfSpecifier &FS,
3419                                const analyze_printf::OptionalFlag &ignoredFlag,
3420                                const analyze_printf::OptionalFlag &flag,
3421                                const char *startSpecifier,
3422                                unsigned specifierLen) {
3423  // Warn about ignored flag with a fixit removal.
3424  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
3425                         << ignoredFlag.toString() << flag.toString(),
3426                       getLocationOfByte(ignoredFlag.getPosition()),
3427                       /*IsStringLocation*/true,
3428                       getSpecifierRange(startSpecifier, specifierLen),
3429                       FixItHint::CreateRemoval(
3430                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
3431}
3432
3433// Determines if the specified is a C++ class or struct containing
3434// a member with the specified name and kind (e.g. a CXXMethodDecl named
3435// "c_str()").
3436template<typename MemberKind>
3437static llvm::SmallPtrSet<MemberKind*, 1>
3438CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
3439  const RecordType *RT = Ty->getAs<RecordType>();
3440  llvm::SmallPtrSet<MemberKind*, 1> Results;
3441
3442  if (!RT)
3443    return Results;
3444  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
3445  if (!RD || !RD->getDefinition())
3446    return Results;
3447
3448  LookupResult R(S, &S.Context.Idents.get(Name), SourceLocation(),
3449                 Sema::LookupMemberName);
3450  R.suppressDiagnostics();
3451
3452  // We just need to include all members of the right kind turned up by the
3453  // filter, at this point.
3454  if (S.LookupQualifiedName(R, RT->getDecl()))
3455    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
3456      NamedDecl *decl = (*I)->getUnderlyingDecl();
3457      if (MemberKind *FK = dyn_cast<MemberKind>(decl))
3458        Results.insert(FK);
3459    }
3460  return Results;
3461}
3462
3463/// Check if we could call '.c_str()' on an object.
3464///
3465/// FIXME: This returns the wrong results in some cases (if cv-qualifiers don't
3466/// allow the call, or if it would be ambiguous).
3467bool Sema::hasCStrMethod(const Expr *E) {
3468  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
3469  MethodSet Results =
3470      CXXRecordMembersNamed<CXXMethodDecl>("c_str", *this, E->getType());
3471  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
3472       MI != ME; ++MI)
3473    if ((*MI)->getMinRequiredArguments() == 0)
3474      return true;
3475  return false;
3476}
3477
3478// Check if a (w)string was passed when a (w)char* was needed, and offer a
3479// better diagnostic if so. AT is assumed to be valid.
3480// Returns true when a c_str() conversion method is found.
3481bool CheckPrintfHandler::checkForCStrMembers(
3482    const analyze_printf::ArgType &AT, const Expr *E) {
3483  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
3484
3485  MethodSet Results =
3486      CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
3487
3488  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
3489       MI != ME; ++MI) {
3490    const CXXMethodDecl *Method = *MI;
3491    if (Method->getMinRequiredArguments() == 0 &&
3492        AT.matchesType(S.Context, Method->getReturnType())) {
3493      // FIXME: Suggest parens if the expression needs them.
3494      SourceLocation EndLoc = S.getLocForEndOfToken(E->getLocEnd());
3495      S.Diag(E->getLocStart(), diag::note_printf_c_str)
3496          << "c_str()"
3497          << FixItHint::CreateInsertion(EndLoc, ".c_str()");
3498      return true;
3499    }
3500  }
3501
3502  return false;
3503}
3504
3505bool
3506CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
3507                                            &FS,
3508                                          const char *startSpecifier,
3509                                          unsigned specifierLen) {
3510
3511  using namespace analyze_format_string;
3512  using namespace analyze_printf;
3513  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
3514
3515  if (FS.consumesDataArgument()) {
3516    if (atFirstArg) {
3517        atFirstArg = false;
3518        usesPositionalArgs = FS.usesPositionalArg();
3519    }
3520    else if (usesPositionalArgs != FS.usesPositionalArg()) {
3521      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
3522                                        startSpecifier, specifierLen);
3523      return false;
3524    }
3525  }
3526
3527  // First check if the field width, precision, and conversion specifier
3528  // have matching data arguments.
3529  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
3530                    startSpecifier, specifierLen)) {
3531    return false;
3532  }
3533
3534  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
3535                    startSpecifier, specifierLen)) {
3536    return false;
3537  }
3538
3539  if (!CS.consumesDataArgument()) {
3540    // FIXME: Technically specifying a precision or field width here
3541    // makes no sense.  Worth issuing a warning at some point.
3542    return true;
3543  }
3544
3545  // Consume the argument.
3546  unsigned argIndex = FS.getArgIndex();
3547  if (argIndex < NumDataArgs) {
3548    // The check to see if the argIndex is valid will come later.
3549    // We set the bit here because we may exit early from this
3550    // function if we encounter some other error.
3551    CoveredArgs.set(argIndex);
3552  }
3553
3554  // FreeBSD kernel extensions.
3555  if (CS.getKind() == ConversionSpecifier::FreeBSDbArg ||
3556      CS.getKind() == ConversionSpecifier::FreeBSDDArg) {
3557    // We need at least two arguments.
3558    if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex + 1))
3559      return false;
3560
3561    // Claim the second argument.
3562    CoveredArgs.set(argIndex + 1);
3563
3564    // Type check the first argument (int for %b, pointer for %D)
3565    const Expr *Ex = getDataArg(argIndex);
3566    const analyze_printf::ArgType &AT =
3567      (CS.getKind() == ConversionSpecifier::FreeBSDbArg) ?
3568        ArgType(S.Context.IntTy) : ArgType::CPointerTy;
3569    if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType()))
3570      EmitFormatDiagnostic(
3571        S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
3572        << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
3573        << false << Ex->getSourceRange(),
3574        Ex->getLocStart(), /*IsStringLocation*/false,
3575        getSpecifierRange(startSpecifier, specifierLen));
3576
3577    // Type check the second argument (char * for both %b and %D)
3578    Ex = getDataArg(argIndex + 1);
3579    const analyze_printf::ArgType &AT2 = ArgType::CStrTy;
3580    if (AT2.isValid() && !AT2.matchesType(S.Context, Ex->getType()))
3581      EmitFormatDiagnostic(
3582        S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
3583        << AT2.getRepresentativeTypeName(S.Context) << Ex->getType()
3584        << false << Ex->getSourceRange(),
3585        Ex->getLocStart(), /*IsStringLocation*/false,
3586        getSpecifierRange(startSpecifier, specifierLen));
3587
3588     return true;
3589  }
3590
3591  // Check for using an Objective-C specific conversion specifier
3592  // in a non-ObjC literal.
3593  if (!ObjCContext && CS.isObjCArg()) {
3594    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
3595                                                  specifierLen);
3596  }
3597
3598  // Check for invalid use of field width
3599  if (!FS.hasValidFieldWidth()) {
3600    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
3601        startSpecifier, specifierLen);
3602  }
3603
3604  // Check for invalid use of precision
3605  if (!FS.hasValidPrecision()) {
3606    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
3607        startSpecifier, specifierLen);
3608  }
3609
3610  // Check each flag does not conflict with any other component.
3611  if (!FS.hasValidThousandsGroupingPrefix())
3612    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
3613  if (!FS.hasValidLeadingZeros())
3614    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
3615  if (!FS.hasValidPlusPrefix())
3616    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
3617  if (!FS.hasValidSpacePrefix())
3618    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
3619  if (!FS.hasValidAlternativeForm())
3620    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
3621  if (!FS.hasValidLeftJustified())
3622    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
3623
3624  // Check that flags are not ignored by another flag
3625  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
3626    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
3627        startSpecifier, specifierLen);
3628  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
3629    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
3630            startSpecifier, specifierLen);
3631
3632  // Check the length modifier is valid with the given conversion specifier.
3633  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
3634    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3635                                diag::warn_format_nonsensical_length);
3636  else if (!FS.hasStandardLengthModifier())
3637    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
3638  else if (!FS.hasStandardLengthConversionCombination())
3639    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
3640                                diag::warn_format_non_standard_conversion_spec);
3641
3642  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
3643    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
3644
3645  // The remaining checks depend on the data arguments.
3646  if (HasVAListArg)
3647    return true;
3648
3649  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
3650    return false;
3651
3652  const Expr *Arg = getDataArg(argIndex);
3653  if (!Arg)
3654    return true;
3655
3656  return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
3657}
3658
3659static bool requiresParensToAddCast(const Expr *E) {
3660  // FIXME: We should have a general way to reason about operator
3661  // precedence and whether parens are actually needed here.
3662  // Take care of a few common cases where they aren't.
3663  const Expr *Inside = E->IgnoreImpCasts();
3664  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
3665    Inside = POE->getSyntacticForm()->IgnoreImpCasts();
3666
3667  switch (Inside->getStmtClass()) {
3668  case Stmt::ArraySubscriptExprClass:
3669  case Stmt::CallExprClass:
3670  case Stmt::CharacterLiteralClass:
3671  case Stmt::CXXBoolLiteralExprClass:
3672  case Stmt::DeclRefExprClass:
3673  case Stmt::FloatingLiteralClass:
3674  case Stmt::IntegerLiteralClass:
3675  case Stmt::MemberExprClass:
3676  case Stmt::ObjCArrayLiteralClass:
3677  case Stmt::ObjCBoolLiteralExprClass:
3678  case Stmt::ObjCBoxedExprClass:
3679  case Stmt::ObjCDictionaryLiteralClass:
3680  case Stmt::ObjCEncodeExprClass:
3681  case Stmt::ObjCIvarRefExprClass:
3682  case Stmt::ObjCMessageExprClass:
3683  case Stmt::ObjCPropertyRefExprClass:
3684  case Stmt::ObjCStringLiteralClass:
3685  case Stmt::ObjCSubscriptRefExprClass:
3686  case Stmt::ParenExprClass:
3687  case Stmt::StringLiteralClass:
3688  case Stmt::UnaryOperatorClass:
3689    return false;
3690  default:
3691    return true;
3692  }
3693}
3694
3695static std::pair<QualType, StringRef>
3696shouldNotPrintDirectly(const ASTContext &Context,
3697                       QualType IntendedTy,
3698                       const Expr *E) {
3699  // Use a 'while' to peel off layers of typedefs.
3700  QualType TyTy = IntendedTy;
3701  while (const TypedefType *UserTy = TyTy->getAs<TypedefType>()) {
3702    StringRef Name = UserTy->getDecl()->getName();
3703    QualType CastTy = llvm::StringSwitch<QualType>(Name)
3704      .Case("NSInteger", Context.LongTy)
3705      .Case("NSUInteger", Context.UnsignedLongTy)
3706      .Case("SInt32", Context.IntTy)
3707      .Case("UInt32", Context.UnsignedIntTy)
3708      .Default(QualType());
3709
3710    if (!CastTy.isNull())
3711      return std::make_pair(CastTy, Name);
3712
3713    TyTy = UserTy->desugar();
3714  }
3715
3716  // Strip parens if necessary.
3717  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
3718    return shouldNotPrintDirectly(Context,
3719                                  PE->getSubExpr()->getType(),
3720                                  PE->getSubExpr());
3721
3722  // If this is a conditional expression, then its result type is constructed
3723  // via usual arithmetic conversions and thus there might be no necessary
3724  // typedef sugar there.  Recurse to operands to check for NSInteger &
3725  // Co. usage condition.
3726  if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3727    QualType TrueTy, FalseTy;
3728    StringRef TrueName, FalseName;
3729
3730    std::tie(TrueTy, TrueName) =
3731      shouldNotPrintDirectly(Context,
3732                             CO->getTrueExpr()->getType(),
3733                             CO->getTrueExpr());
3734    std::tie(FalseTy, FalseName) =
3735      shouldNotPrintDirectly(Context,
3736                             CO->getFalseExpr()->getType(),
3737                             CO->getFalseExpr());
3738
3739    if (TrueTy == FalseTy)
3740      return std::make_pair(TrueTy, TrueName);
3741    else if (TrueTy.isNull())
3742      return std::make_pair(FalseTy, FalseName);
3743    else if (FalseTy.isNull())
3744      return std::make_pair(TrueTy, TrueName);
3745  }
3746
3747  return std::make_pair(QualType(), StringRef());
3748}
3749
3750bool
3751CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
3752                                    const char *StartSpecifier,
3753                                    unsigned SpecifierLen,
3754                                    const Expr *E) {
3755  using namespace analyze_format_string;
3756  using namespace analyze_printf;
3757  // Now type check the data expression that matches the
3758  // format specifier.
3759  const analyze_printf::ArgType &AT = FS.getArgType(S.Context,
3760                                                    ObjCContext);
3761  if (!AT.isValid())
3762    return true;
3763
3764  QualType ExprTy = E->getType();
3765  while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
3766    ExprTy = TET->getUnderlyingExpr()->getType();
3767  }
3768
3769  analyze_printf::ArgType::MatchKind match = AT.matchesType(S.Context, ExprTy);
3770
3771  if (match == analyze_printf::ArgType::Match) {
3772    return true;
3773  }
3774
3775  // Look through argument promotions for our error message's reported type.
3776  // This includes the integral and floating promotions, but excludes array
3777  // and function pointer decay; seeing that an argument intended to be a
3778  // string has type 'char [6]' is probably more confusing than 'char *'.
3779  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
3780    if (ICE->getCastKind() == CK_IntegralCast ||
3781        ICE->getCastKind() == CK_FloatingCast) {
3782      E = ICE->getSubExpr();
3783      ExprTy = E->getType();
3784
3785      // Check if we didn't match because of an implicit cast from a 'char'
3786      // or 'short' to an 'int'.  This is done because printf is a varargs
3787      // function.
3788      if (ICE->getType() == S.Context.IntTy ||
3789          ICE->getType() == S.Context.UnsignedIntTy) {
3790        // All further checking is done on the subexpression.
3791        if (AT.matchesType(S.Context, ExprTy))
3792          return true;
3793      }
3794    }
3795  } else if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) {
3796    // Special case for 'a', which has type 'int' in C.
3797    // Note, however, that we do /not/ want to treat multibyte constants like
3798    // 'MooV' as characters! This form is deprecated but still exists.
3799    if (ExprTy == S.Context.IntTy)
3800      if (llvm::isUIntN(S.Context.getCharWidth(), CL->getValue()))
3801        ExprTy = S.Context.CharTy;
3802  }
3803
3804  // Look through enums to their underlying type.
3805  bool IsEnum = false;
3806  if (auto EnumTy = ExprTy->getAs<EnumType>()) {
3807    ExprTy = EnumTy->getDecl()->getIntegerType();
3808    IsEnum = true;
3809  }
3810
3811  // %C in an Objective-C context prints a unichar, not a wchar_t.
3812  // If the argument is an integer of some kind, believe the %C and suggest
3813  // a cast instead of changing the conversion specifier.
3814  QualType IntendedTy = ExprTy;
3815  if (ObjCContext &&
3816      FS.getConversionSpecifier().getKind() == ConversionSpecifier::CArg) {
3817    if (ExprTy->isIntegralOrUnscopedEnumerationType() &&
3818        !ExprTy->isCharType()) {
3819      // 'unichar' is defined as a typedef of unsigned short, but we should
3820      // prefer using the typedef if it is visible.
3821      IntendedTy = S.Context.UnsignedShortTy;
3822
3823      // While we are here, check if the value is an IntegerLiteral that happens
3824      // to be within the valid range.
3825      if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E)) {
3826        const llvm::APInt &V = IL->getValue();
3827        if (V.getActiveBits() <= S.Context.getTypeSize(IntendedTy))
3828          return true;
3829      }
3830
3831      LookupResult Result(S, &S.Context.Idents.get("unichar"), E->getLocStart(),
3832                          Sema::LookupOrdinaryName);
3833      if (S.LookupName(Result, S.getCurScope())) {
3834        NamedDecl *ND = Result.getFoundDecl();
3835        if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(ND))
3836          if (TD->getUnderlyingType() == IntendedTy)
3837            IntendedTy = S.Context.getTypedefType(TD);
3838      }
3839    }
3840  }
3841
3842  // Special-case some of Darwin's platform-independence types by suggesting
3843  // casts to primitive types that are known to be large enough.
3844  bool ShouldNotPrintDirectly = false; StringRef CastTyName;
3845  if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
3846    QualType CastTy;
3847    std::tie(CastTy, CastTyName) = shouldNotPrintDirectly(S.Context, IntendedTy, E);
3848    if (!CastTy.isNull()) {
3849      IntendedTy = CastTy;
3850      ShouldNotPrintDirectly = true;
3851    }
3852  }
3853
3854  // We may be able to offer a FixItHint if it is a supported type.
3855  PrintfSpecifier fixedFS = FS;
3856  bool success = fixedFS.fixType(IntendedTy, S.getLangOpts(),
3857                                 S.Context, ObjCContext);
3858
3859  if (success) {
3860    // Get the fix string from the fixed format specifier
3861    SmallString<16> buf;
3862    llvm::raw_svector_ostream os(buf);
3863    fixedFS.toString(os);
3864
3865    CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
3866
3867    if (IntendedTy == ExprTy && !ShouldNotPrintDirectly) {
3868      unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
3869      if (match == analyze_format_string::ArgType::NoMatchPedantic) {
3870        diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
3871      }
3872      // In this case, the specifier is wrong and should be changed to match
3873      // the argument.
3874      EmitFormatDiagnostic(S.PDiag(diag)
3875                               << AT.getRepresentativeTypeName(S.Context)
3876                               << IntendedTy << IsEnum << E->getSourceRange(),
3877                           E->getLocStart(),
3878                           /*IsStringLocation*/ false, SpecRange,
3879                           FixItHint::CreateReplacement(SpecRange, os.str()));
3880
3881    } else {
3882      // The canonical type for formatting this value is different from the
3883      // actual type of the expression. (This occurs, for example, with Darwin's
3884      // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
3885      // should be printed as 'long' for 64-bit compatibility.)
3886      // Rather than emitting a normal format/argument mismatch, we want to
3887      // add a cast to the recommended type (and correct the format string
3888      // if necessary).
3889      SmallString<16> CastBuf;
3890      llvm::raw_svector_ostream CastFix(CastBuf);
3891      CastFix << "(";
3892      IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
3893      CastFix << ")";
3894
3895      SmallVector<FixItHint,4> Hints;
3896      if (!AT.matchesType(S.Context, IntendedTy))
3897        Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
3898
3899      if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
3900        // If there's already a cast present, just replace it.
3901        SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
3902        Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
3903
3904      } else if (!requiresParensToAddCast(E)) {
3905        // If the expression has high enough precedence,
3906        // just write the C-style cast.
3907        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
3908                                                   CastFix.str()));
3909      } else {
3910        // Otherwise, add parens around the expression as well as the cast.
3911        CastFix << "(";
3912        Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
3913                                                   CastFix.str()));
3914
3915        SourceLocation After = S.getLocForEndOfToken(E->getLocEnd());
3916        Hints.push_back(FixItHint::CreateInsertion(After, ")"));
3917      }
3918
3919      if (ShouldNotPrintDirectly) {
3920        // The expression has a type that should not be printed directly.
3921        // We extract the name from the typedef because we don't want to show
3922        // the underlying type in the diagnostic.
3923        StringRef Name;
3924        if (const TypedefType *TypedefTy = dyn_cast<TypedefType>(ExprTy))
3925          Name = TypedefTy->getDecl()->getName();
3926        else
3927          Name = CastTyName;
3928        EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
3929                               << Name << IntendedTy << IsEnum
3930                               << E->getSourceRange(),
3931                             E->getLocStart(), /*IsStringLocation=*/false,
3932                             SpecRange, Hints);
3933      } else {
3934        // In this case, the expression could be printed using a different
3935        // specifier, but we've decided that the specifier is probably correct
3936        // and we should cast instead. Just use the normal warning message.
3937        EmitFormatDiagnostic(
3938          S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
3939            << AT.getRepresentativeTypeName(S.Context) << ExprTy << IsEnum
3940            << E->getSourceRange(),
3941          E->getLocStart(), /*IsStringLocation*/false,
3942          SpecRange, Hints);
3943      }
3944    }
3945  } else {
3946    const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
3947                                                   SpecifierLen);
3948    // Since the warning for passing non-POD types to variadic functions
3949    // was deferred until now, we emit a warning for non-POD
3950    // arguments here.
3951    switch (S.isValidVarArgType(ExprTy)) {
3952    case Sema::VAK_Valid:
3953    case Sema::VAK_ValidInCXX11: {
3954      unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
3955      if (match == analyze_printf::ArgType::NoMatchPedantic) {
3956        diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
3957      }
3958
3959      EmitFormatDiagnostic(
3960          S.PDiag(diag) << AT.getRepresentativeTypeName(S.Context) << ExprTy
3961                        << IsEnum << CSR << E->getSourceRange(),
3962          E->getLocStart(), /*IsStringLocation*/ false, CSR);
3963      break;
3964    }
3965    case Sema::VAK_Undefined:
3966    case Sema::VAK_MSVCUndefined:
3967      EmitFormatDiagnostic(
3968        S.PDiag(diag::warn_non_pod_vararg_with_format_string)
3969          << S.getLangOpts().CPlusPlus11
3970          << ExprTy
3971          << CallType
3972          << AT.getRepresentativeTypeName(S.Context)
3973          << CSR
3974          << E->getSourceRange(),
3975        E->getLocStart(), /*IsStringLocation*/false, CSR);
3976      checkForCStrMembers(AT, E);
3977      break;
3978
3979    case Sema::VAK_Invalid:
3980      if (ExprTy->isObjCObjectType())
3981        EmitFormatDiagnostic(
3982          S.PDiag(diag::err_cannot_pass_objc_interface_to_vararg_format)
3983            << S.getLangOpts().CPlusPlus11
3984            << ExprTy
3985            << CallType
3986            << AT.getRepresentativeTypeName(S.Context)
3987            << CSR
3988            << E->getSourceRange(),
3989          E->getLocStart(), /*IsStringLocation*/false, CSR);
3990      else
3991        // FIXME: If this is an initializer list, suggest removing the braces
3992        // or inserting a cast to the target type.
3993        S.Diag(E->getLocStart(), diag::err_cannot_pass_to_vararg_format)
3994          << isa<InitListExpr>(E) << ExprTy << CallType
3995          << AT.getRepresentativeTypeName(S.Context)
3996          << E->getSourceRange();
3997      break;
3998    }
3999
4000    assert(FirstDataArg + FS.getArgIndex() < CheckedVarArgs.size() &&
4001           "format string specifier index out of range");
4002    CheckedVarArgs[FirstDataArg + FS.getArgIndex()] = true;
4003  }
4004
4005  return true;
4006}
4007
4008//===--- CHECK: Scanf format string checking ------------------------------===//
4009
4010namespace {
4011class CheckScanfHandler : public CheckFormatHandler {
4012public:
4013  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
4014                    const Expr *origFormatExpr, unsigned firstDataArg,
4015                    unsigned numDataArgs, const char *beg, bool hasVAListArg,
4016                    ArrayRef<const Expr *> Args,
4017                    unsigned formatIdx, bool inFunctionCall,
4018                    Sema::VariadicCallType CallType,
4019                    llvm::SmallBitVector &CheckedVarArgs)
4020    : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
4021                         numDataArgs, beg, hasVAListArg,
4022                         Args, formatIdx, inFunctionCall, CallType,
4023                         CheckedVarArgs)
4024  {}
4025
4026  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
4027                            const char *startSpecifier,
4028                            unsigned specifierLen) override;
4029
4030  bool HandleInvalidScanfConversionSpecifier(
4031          const analyze_scanf::ScanfSpecifier &FS,
4032          const char *startSpecifier,
4033          unsigned specifierLen) override;
4034
4035  void HandleIncompleteScanList(const char *start, const char *end) override;
4036};
4037}
4038
4039void CheckScanfHandler::HandleIncompleteScanList(const char *start,
4040                                                 const char *end) {
4041  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
4042                       getLocationOfByte(end), /*IsStringLocation*/true,
4043                       getSpecifierRange(start, end - start));
4044}
4045
4046bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
4047                                        const analyze_scanf::ScanfSpecifier &FS,
4048                                        const char *startSpecifier,
4049                                        unsigned specifierLen) {
4050
4051  const analyze_scanf::ScanfConversionSpecifier &CS =
4052    FS.getConversionSpecifier();
4053
4054  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
4055                                          getLocationOfByte(CS.getStart()),
4056                                          startSpecifier, specifierLen,
4057                                          CS.getStart(), CS.getLength());
4058}
4059
4060bool CheckScanfHandler::HandleScanfSpecifier(
4061                                       const analyze_scanf::ScanfSpecifier &FS,
4062                                       const char *startSpecifier,
4063                                       unsigned specifierLen) {
4064
4065  using namespace analyze_scanf;
4066  using namespace analyze_format_string;
4067
4068  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
4069
4070  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
4071  // be used to decide if we are using positional arguments consistently.
4072  if (FS.consumesDataArgument()) {
4073    if (atFirstArg) {
4074      atFirstArg = false;
4075      usesPositionalArgs = FS.usesPositionalArg();
4076    }
4077    else if (usesPositionalArgs != FS.usesPositionalArg()) {
4078      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
4079                                        startSpecifier, specifierLen);
4080      return false;
4081    }
4082  }
4083
4084  // Check if the field with is non-zero.
4085  const OptionalAmount &Amt = FS.getFieldWidth();
4086  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
4087    if (Amt.getConstantAmount() == 0) {
4088      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
4089                                                   Amt.getConstantLength());
4090      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
4091                           getLocationOfByte(Amt.getStart()),
4092                           /*IsStringLocation*/true, R,
4093                           FixItHint::CreateRemoval(R));
4094    }
4095  }
4096
4097  if (!FS.consumesDataArgument()) {
4098    // FIXME: Technically specifying a precision or field width here
4099    // makes no sense.  Worth issuing a warning at some point.
4100    return true;
4101  }
4102
4103  // Consume the argument.
4104  unsigned argIndex = FS.getArgIndex();
4105  if (argIndex < NumDataArgs) {
4106      // The check to see if the argIndex is valid will come later.
4107      // We set the bit here because we may exit early from this
4108      // function if we encounter some other error.
4109    CoveredArgs.set(argIndex);
4110  }
4111
4112  // Check the length modifier is valid with the given conversion specifier.
4113  if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
4114    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
4115                                diag::warn_format_nonsensical_length);
4116  else if (!FS.hasStandardLengthModifier())
4117    HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
4118  else if (!FS.hasStandardLengthConversionCombination())
4119    HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
4120                                diag::warn_format_non_standard_conversion_spec);
4121
4122  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
4123    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
4124
4125  // The remaining checks depend on the data arguments.
4126  if (HasVAListArg)
4127    return true;
4128
4129  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
4130    return false;
4131
4132  // Check that the argument type matches the format specifier.
4133  const Expr *Ex = getDataArg(argIndex);
4134  if (!Ex)
4135    return true;
4136
4137  const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
4138
4139  if (!AT.isValid()) {
4140    return true;
4141  }
4142
4143  analyze_format_string::ArgType::MatchKind match =
4144      AT.matchesType(S.Context, Ex->getType());
4145  if (match == analyze_format_string::ArgType::Match) {
4146    return true;
4147  }
4148
4149  ScanfSpecifier fixedFS = FS;
4150  bool success = fixedFS.fixType(Ex->getType(), Ex->IgnoreImpCasts()->getType(),
4151                                 S.getLangOpts(), S.Context);
4152
4153  unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
4154  if (match == analyze_format_string::ArgType::NoMatchPedantic) {
4155    diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
4156  }
4157
4158  if (success) {
4159    // Get the fix string from the fixed format specifier.
4160    SmallString<128> buf;
4161    llvm::raw_svector_ostream os(buf);
4162    fixedFS.toString(os);
4163
4164    EmitFormatDiagnostic(
4165        S.PDiag(diag) << AT.getRepresentativeTypeName(S.Context)
4166                      << Ex->getType() << false << Ex->getSourceRange(),
4167        Ex->getLocStart(),
4168        /*IsStringLocation*/ false,
4169        getSpecifierRange(startSpecifier, specifierLen),
4170        FixItHint::CreateReplacement(
4171            getSpecifierRange(startSpecifier, specifierLen), os.str()));
4172  } else {
4173    EmitFormatDiagnostic(S.PDiag(diag)
4174                             << AT.getRepresentativeTypeName(S.Context)
4175                             << Ex->getType() << false << Ex->getSourceRange(),
4176                         Ex->getLocStart(),
4177                         /*IsStringLocation*/ false,
4178                         getSpecifierRange(startSpecifier, specifierLen));
4179  }
4180
4181  return true;
4182}
4183
4184void Sema::CheckFormatString(const StringLiteral *FExpr,
4185                             const Expr *OrigFormatExpr,
4186                             ArrayRef<const Expr *> Args,
4187                             bool HasVAListArg, unsigned format_idx,
4188                             unsigned firstDataArg, FormatStringType Type,
4189                             bool inFunctionCall, VariadicCallType CallType,
4190                             llvm::SmallBitVector &CheckedVarArgs) {
4191
4192  // CHECK: is the format string a wide literal?
4193  if (!FExpr->isAscii() && !FExpr->isUTF8()) {
4194    CheckFormatHandler::EmitFormatDiagnostic(
4195      *this, inFunctionCall, Args[format_idx],
4196      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
4197      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
4198    return;
4199  }
4200
4201  // Str - The format string.  NOTE: this is NOT null-terminated!
4202  StringRef StrRef = FExpr->getString();
4203  const char *Str = StrRef.data();
4204  // Account for cases where the string literal is truncated in a declaration.
4205  const ConstantArrayType *T = Context.getAsConstantArrayType(FExpr->getType());
4206  assert(T && "String literal not of constant array type!");
4207  size_t TypeSize = T->getSize().getZExtValue();
4208  size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
4209  const unsigned numDataArgs = Args.size() - firstDataArg;
4210
4211  // Emit a warning if the string literal is truncated and does not contain an
4212  // embedded null character.
4213  if (TypeSize <= StrRef.size() &&
4214      StrRef.substr(0, TypeSize).find('\0') == StringRef::npos) {
4215    CheckFormatHandler::EmitFormatDiagnostic(
4216        *this, inFunctionCall, Args[format_idx],
4217        PDiag(diag::warn_printf_format_string_not_null_terminated),
4218        FExpr->getLocStart(),
4219        /*IsStringLocation=*/true, OrigFormatExpr->getSourceRange());
4220    return;
4221  }
4222
4223  // CHECK: empty format string?
4224  if (StrLen == 0 && numDataArgs > 0) {
4225    CheckFormatHandler::EmitFormatDiagnostic(
4226      *this, inFunctionCall, Args[format_idx],
4227      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
4228      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
4229    return;
4230  }
4231
4232  if (Type == FST_Printf || Type == FST_NSString ||
4233      Type == FST_FreeBSDKPrintf || Type == FST_OSTrace) {
4234    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
4235                         numDataArgs, (Type == FST_NSString || Type == FST_OSTrace),
4236                         Str, HasVAListArg, Args, format_idx,
4237                         inFunctionCall, CallType, CheckedVarArgs);
4238
4239    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
4240                                                  getLangOpts(),
4241                                                  Context.getTargetInfo(),
4242                                                  Type == FST_FreeBSDKPrintf))
4243      H.DoneProcessing();
4244  } else if (Type == FST_Scanf) {
4245    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, numDataArgs,
4246                        Str, HasVAListArg, Args, format_idx,
4247                        inFunctionCall, CallType, CheckedVarArgs);
4248
4249    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
4250                                                 getLangOpts(),
4251                                                 Context.getTargetInfo()))
4252      H.DoneProcessing();
4253  } // TODO: handle other formats
4254}
4255
4256bool Sema::FormatStringHasSArg(const StringLiteral *FExpr) {
4257  // Str - The format string.  NOTE: this is NOT null-terminated!
4258  StringRef StrRef = FExpr->getString();
4259  const char *Str = StrRef.data();
4260  // Account for cases where the string literal is truncated in a declaration.
4261  const ConstantArrayType *T = Context.getAsConstantArrayType(FExpr->getType());
4262  assert(T && "String literal not of constant array type!");
4263  size_t TypeSize = T->getSize().getZExtValue();
4264  size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
4265  return analyze_format_string::ParseFormatStringHasSArg(Str, Str + StrLen,
4266                                                         getLangOpts(),
4267                                                         Context.getTargetInfo());
4268}
4269
4270//===--- CHECK: Warn on use of wrong absolute value function. -------------===//
4271
4272// Returns the related absolute value function that is larger, of 0 if one
4273// does not exist.
4274static unsigned getLargerAbsoluteValueFunction(unsigned AbsFunction) {
4275  switch (AbsFunction) {
4276  default:
4277    return 0;
4278
4279  case Builtin::BI__builtin_abs:
4280    return Builtin::BI__builtin_labs;
4281  case Builtin::BI__builtin_labs:
4282    return Builtin::BI__builtin_llabs;
4283  case Builtin::BI__builtin_llabs:
4284    return 0;
4285
4286  case Builtin::BI__builtin_fabsf:
4287    return Builtin::BI__builtin_fabs;
4288  case Builtin::BI__builtin_fabs:
4289    return Builtin::BI__builtin_fabsl;
4290  case Builtin::BI__builtin_fabsl:
4291    return 0;
4292
4293  case Builtin::BI__builtin_cabsf:
4294    return Builtin::BI__builtin_cabs;
4295  case Builtin::BI__builtin_cabs:
4296    return Builtin::BI__builtin_cabsl;
4297  case Builtin::BI__builtin_cabsl:
4298    return 0;
4299
4300  case Builtin::BIabs:
4301    return Builtin::BIlabs;
4302  case Builtin::BIlabs:
4303    return Builtin::BIllabs;
4304  case Builtin::BIllabs:
4305    return 0;
4306
4307  case Builtin::BIfabsf:
4308    return Builtin::BIfabs;
4309  case Builtin::BIfabs:
4310    return Builtin::BIfabsl;
4311  case Builtin::BIfabsl:
4312    return 0;
4313
4314  case Builtin::BIcabsf:
4315   return Builtin::BIcabs;
4316  case Builtin::BIcabs:
4317    return Builtin::BIcabsl;
4318  case Builtin::BIcabsl:
4319    return 0;
4320  }
4321}
4322
4323// Returns the argument type of the absolute value function.
4324static QualType getAbsoluteValueArgumentType(ASTContext &Context,
4325                                             unsigned AbsType) {
4326  if (AbsType == 0)
4327    return QualType();
4328
4329  ASTContext::GetBuiltinTypeError Error = ASTContext::GE_None;
4330  QualType BuiltinType = Context.GetBuiltinType(AbsType, Error);
4331  if (Error != ASTContext::GE_None)
4332    return QualType();
4333
4334  const FunctionProtoType *FT = BuiltinType->getAs<FunctionProtoType>();
4335  if (!FT)
4336    return QualType();
4337
4338  if (FT->getNumParams() != 1)
4339    return QualType();
4340
4341  return FT->getParamType(0);
4342}
4343
4344// Returns the best absolute value function, or zero, based on type and
4345// current absolute value function.
4346static unsigned getBestAbsFunction(ASTContext &Context, QualType ArgType,
4347                                   unsigned AbsFunctionKind) {
4348  unsigned BestKind = 0;
4349  uint64_t ArgSize = Context.getTypeSize(ArgType);
4350  for (unsigned Kind = AbsFunctionKind; Kind != 0;
4351       Kind = getLargerAbsoluteValueFunction(Kind)) {
4352    QualType ParamType = getAbsoluteValueArgumentType(Context, Kind);
4353    if (Context.getTypeSize(ParamType) >= ArgSize) {
4354      if (BestKind == 0)
4355        BestKind = Kind;
4356      else if (Context.hasSameType(ParamType, ArgType)) {
4357        BestKind = Kind;
4358        break;
4359      }
4360    }
4361  }
4362  return BestKind;
4363}
4364
4365enum AbsoluteValueKind {
4366  AVK_Integer,
4367  AVK_Floating,
4368  AVK_Complex
4369};
4370
4371static AbsoluteValueKind getAbsoluteValueKind(QualType T) {
4372  if (T->isIntegralOrEnumerationType())
4373    return AVK_Integer;
4374  if (T->isRealFloatingType())
4375    return AVK_Floating;
4376  if (T->isAnyComplexType())
4377    return AVK_Complex;
4378
4379  llvm_unreachable("Type not integer, floating, or complex");
4380}
4381
4382// Changes the absolute value function to a different type.  Preserves whether
4383// the function is a builtin.
4384static unsigned changeAbsFunction(unsigned AbsKind,
4385                                  AbsoluteValueKind ValueKind) {
4386  switch (ValueKind) {
4387  case AVK_Integer:
4388    switch (AbsKind) {
4389    default:
4390      return 0;
4391    case Builtin::BI__builtin_fabsf:
4392    case Builtin::BI__builtin_fabs:
4393    case Builtin::BI__builtin_fabsl:
4394    case Builtin::BI__builtin_cabsf:
4395    case Builtin::BI__builtin_cabs:
4396    case Builtin::BI__builtin_cabsl:
4397      return Builtin::BI__builtin_abs;
4398    case Builtin::BIfabsf:
4399    case Builtin::BIfabs:
4400    case Builtin::BIfabsl:
4401    case Builtin::BIcabsf:
4402    case Builtin::BIcabs:
4403    case Builtin::BIcabsl:
4404      return Builtin::BIabs;
4405    }
4406  case AVK_Floating:
4407    switch (AbsKind) {
4408    default:
4409      return 0;
4410    case Builtin::BI__builtin_abs:
4411    case Builtin::BI__builtin_labs:
4412    case Builtin::BI__builtin_llabs:
4413    case Builtin::BI__builtin_cabsf:
4414    case Builtin::BI__builtin_cabs:
4415    case Builtin::BI__builtin_cabsl:
4416      return Builtin::BI__builtin_fabsf;
4417    case Builtin::BIabs:
4418    case Builtin::BIlabs:
4419    case Builtin::BIllabs:
4420    case Builtin::BIcabsf:
4421    case Builtin::BIcabs:
4422    case Builtin::BIcabsl:
4423      return Builtin::BIfabsf;
4424    }
4425  case AVK_Complex:
4426    switch (AbsKind) {
4427    default:
4428      return 0;
4429    case Builtin::BI__builtin_abs:
4430    case Builtin::BI__builtin_labs:
4431    case Builtin::BI__builtin_llabs:
4432    case Builtin::BI__builtin_fabsf:
4433    case Builtin::BI__builtin_fabs:
4434    case Builtin::BI__builtin_fabsl:
4435      return Builtin::BI__builtin_cabsf;
4436    case Builtin::BIabs:
4437    case Builtin::BIlabs:
4438    case Builtin::BIllabs:
4439    case Builtin::BIfabsf:
4440    case Builtin::BIfabs:
4441    case Builtin::BIfabsl:
4442      return Builtin::BIcabsf;
4443    }
4444  }
4445  llvm_unreachable("Unable to convert function");
4446}
4447
4448static unsigned getAbsoluteValueFunctionKind(const FunctionDecl *FDecl) {
4449  const IdentifierInfo *FnInfo = FDecl->getIdentifier();
4450  if (!FnInfo)
4451    return 0;
4452
4453  switch (FDecl->getBuiltinID()) {
4454  default:
4455    return 0;
4456  case Builtin::BI__builtin_abs:
4457  case Builtin::BI__builtin_fabs:
4458  case Builtin::BI__builtin_fabsf:
4459  case Builtin::BI__builtin_fabsl:
4460  case Builtin::BI__builtin_labs:
4461  case Builtin::BI__builtin_llabs:
4462  case Builtin::BI__builtin_cabs:
4463  case Builtin::BI__builtin_cabsf:
4464  case Builtin::BI__builtin_cabsl:
4465  case Builtin::BIabs:
4466  case Builtin::BIlabs:
4467  case Builtin::BIllabs:
4468  case Builtin::BIfabs:
4469  case Builtin::BIfabsf:
4470  case Builtin::BIfabsl:
4471  case Builtin::BIcabs:
4472  case Builtin::BIcabsf:
4473  case Builtin::BIcabsl:
4474    return FDecl->getBuiltinID();
4475  }
4476  llvm_unreachable("Unknown Builtin type");
4477}
4478
4479// If the replacement is valid, emit a note with replacement function.
4480// Additionally, suggest including the proper header if not already included.
4481static void emitReplacement(Sema &S, SourceLocation Loc, SourceRange Range,
4482                            unsigned AbsKind, QualType ArgType) {
4483  bool EmitHeaderHint = true;
4484  const char *HeaderName = nullptr;
4485  const char *FunctionName = nullptr;
4486  if (S.getLangOpts().CPlusPlus && !ArgType->isAnyComplexType()) {
4487    FunctionName = "std::abs";
4488    if (ArgType->isIntegralOrEnumerationType()) {
4489      HeaderName = "cstdlib";
4490    } else if (ArgType->isRealFloatingType()) {
4491      HeaderName = "cmath";
4492    } else {
4493      llvm_unreachable("Invalid Type");
4494    }
4495
4496    // Lookup all std::abs
4497    if (NamespaceDecl *Std = S.getStdNamespace()) {
4498      LookupResult R(S, &S.Context.Idents.get("abs"), Loc, Sema::LookupAnyName);
4499      R.suppressDiagnostics();
4500      S.LookupQualifiedName(R, Std);
4501
4502      for (const auto *I : R) {
4503        const FunctionDecl *FDecl = nullptr;
4504        if (const UsingShadowDecl *UsingD = dyn_cast<UsingShadowDecl>(I)) {
4505          FDecl = dyn_cast<FunctionDecl>(UsingD->getTargetDecl());
4506        } else {
4507          FDecl = dyn_cast<FunctionDecl>(I);
4508        }
4509        if (!FDecl)
4510          continue;
4511
4512        // Found std::abs(), check that they are the right ones.
4513        if (FDecl->getNumParams() != 1)
4514          continue;
4515
4516        // Check that the parameter type can handle the argument.
4517        QualType ParamType = FDecl->getParamDecl(0)->getType();
4518        if (getAbsoluteValueKind(ArgType) == getAbsoluteValueKind(ParamType) &&
4519            S.Context.getTypeSize(ArgType) <=
4520                S.Context.getTypeSize(ParamType)) {
4521          // Found a function, don't need the header hint.
4522          EmitHeaderHint = false;
4523          break;
4524        }
4525      }
4526    }
4527  } else {
4528    FunctionName = S.Context.BuiltinInfo.GetName(AbsKind);
4529    HeaderName = S.Context.BuiltinInfo.getHeaderName(AbsKind);
4530
4531    if (HeaderName) {
4532      DeclarationName DN(&S.Context.Idents.get(FunctionName));
4533      LookupResult R(S, DN, Loc, Sema::LookupAnyName);
4534      R.suppressDiagnostics();
4535      S.LookupName(R, S.getCurScope());
4536
4537      if (R.isSingleResult()) {
4538        FunctionDecl *FD = dyn_cast<FunctionDecl>(R.getFoundDecl());
4539        if (FD && FD->getBuiltinID() == AbsKind) {
4540          EmitHeaderHint = false;
4541        } else {
4542          return;
4543        }
4544      } else if (!R.empty()) {
4545        return;
4546      }
4547    }
4548  }
4549
4550  S.Diag(Loc, diag::note_replace_abs_function)
4551      << FunctionName << FixItHint::CreateReplacement(Range, FunctionName);
4552
4553  if (!HeaderName)
4554    return;
4555
4556  if (!EmitHeaderHint)
4557    return;
4558
4559  S.Diag(Loc, diag::note_include_header_or_declare) << HeaderName
4560                                                    << FunctionName;
4561}
4562
4563static bool IsFunctionStdAbs(const FunctionDecl *FDecl) {
4564  if (!FDecl)
4565    return false;
4566
4567  if (!FDecl->getIdentifier() || !FDecl->getIdentifier()->isStr("abs"))
4568    return false;
4569
4570  const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(FDecl->getDeclContext());
4571
4572  while (ND && ND->isInlineNamespace()) {
4573    ND = dyn_cast<NamespaceDecl>(ND->getDeclContext());
4574  }
4575
4576  if (!ND || !ND->getIdentifier() || !ND->getIdentifier()->isStr("std"))
4577    return false;
4578
4579  if (!isa<TranslationUnitDecl>(ND->getDeclContext()))
4580    return false;
4581
4582  return true;
4583}
4584
4585// Warn when using the wrong abs() function.
4586void Sema::CheckAbsoluteValueFunction(const CallExpr *Call,
4587                                      const FunctionDecl *FDecl,
4588                                      IdentifierInfo *FnInfo) {
4589  if (Call->getNumArgs() != 1)
4590    return;
4591
4592  unsigned AbsKind = getAbsoluteValueFunctionKind(FDecl);
4593  bool IsStdAbs = IsFunctionStdAbs(FDecl);
4594  if (AbsKind == 0 && !IsStdAbs)
4595    return;
4596
4597  QualType ArgType = Call->getArg(0)->IgnoreParenImpCasts()->getType();
4598  QualType ParamType = Call->getArg(0)->getType();
4599
4600  // Unsigned types cannot be negative.  Suggest removing the absolute value
4601  // function call.
4602  if (ArgType->isUnsignedIntegerType()) {
4603    const char *FunctionName =
4604        IsStdAbs ? "std::abs" : Context.BuiltinInfo.GetName(AbsKind);
4605    Diag(Call->getExprLoc(), diag::warn_unsigned_abs) << ArgType << ParamType;
4606    Diag(Call->getExprLoc(), diag::note_remove_abs)
4607        << FunctionName
4608        << FixItHint::CreateRemoval(Call->getCallee()->getSourceRange());
4609    return;
4610  }
4611
4612  // std::abs has overloads which prevent most of the absolute value problems
4613  // from occurring.
4614  if (IsStdAbs)
4615    return;
4616
4617  AbsoluteValueKind ArgValueKind = getAbsoluteValueKind(ArgType);
4618  AbsoluteValueKind ParamValueKind = getAbsoluteValueKind(ParamType);
4619
4620  // The argument and parameter are the same kind.  Check if they are the right
4621  // size.
4622  if (ArgValueKind == ParamValueKind) {
4623    if (Context.getTypeSize(ArgType) <= Context.getTypeSize(ParamType))
4624      return;
4625
4626    unsigned NewAbsKind = getBestAbsFunction(Context, ArgType, AbsKind);
4627    Diag(Call->getExprLoc(), diag::warn_abs_too_small)
4628        << FDecl << ArgType << ParamType;
4629
4630    if (NewAbsKind == 0)
4631      return;
4632
4633    emitReplacement(*this, Call->getExprLoc(),
4634                    Call->getCallee()->getSourceRange(), NewAbsKind, ArgType);
4635    return;
4636  }
4637
4638  // ArgValueKind != ParamValueKind
4639  // The wrong type of absolute value function was used.  Attempt to find the
4640  // proper one.
4641  unsigned NewAbsKind = changeAbsFunction(AbsKind, ArgValueKind);
4642  NewAbsKind = getBestAbsFunction(Context, ArgType, NewAbsKind);
4643  if (NewAbsKind == 0)
4644    return;
4645
4646  Diag(Call->getExprLoc(), diag::warn_wrong_absolute_value_type)
4647      << FDecl << ParamValueKind << ArgValueKind;
4648
4649  emitReplacement(*this, Call->getExprLoc(),
4650                  Call->getCallee()->getSourceRange(), NewAbsKind, ArgType);
4651  return;
4652}
4653
4654//===--- CHECK: Standard memory functions ---------------------------------===//
4655
4656/// \brief Takes the expression passed to the size_t parameter of functions
4657/// such as memcmp, strncat, etc and warns if it's a comparison.
4658///
4659/// This is to catch typos like `if (memcmp(&a, &b, sizeof(a) > 0))`.
4660static bool CheckMemorySizeofForComparison(Sema &S, const Expr *E,
4661                                           IdentifierInfo *FnName,
4662                                           SourceLocation FnLoc,
4663                                           SourceLocation RParenLoc) {
4664  const BinaryOperator *Size = dyn_cast<BinaryOperator>(E);
4665  if (!Size)
4666    return false;
4667
4668  // if E is binop and op is >, <, >=, <=, ==, &&, ||:
4669  if (!Size->isComparisonOp() && !Size->isEqualityOp() && !Size->isLogicalOp())
4670    return false;
4671
4672  SourceRange SizeRange = Size->getSourceRange();
4673  S.Diag(Size->getOperatorLoc(), diag::warn_memsize_comparison)
4674      << SizeRange << FnName;
4675  S.Diag(FnLoc, diag::note_memsize_comparison_paren)
4676      << FnName << FixItHint::CreateInsertion(
4677                       S.getLocForEndOfToken(Size->getLHS()->getLocEnd()), ")")
4678      << FixItHint::CreateRemoval(RParenLoc);
4679  S.Diag(SizeRange.getBegin(), diag::note_memsize_comparison_cast_silence)
4680      << FixItHint::CreateInsertion(SizeRange.getBegin(), "(size_t)(")
4681      << FixItHint::CreateInsertion(S.getLocForEndOfToken(SizeRange.getEnd()),
4682                                    ")");
4683
4684  return true;
4685}
4686
4687/// \brief Determine whether the given type is or contains a dynamic class type
4688/// (e.g., whether it has a vtable).
4689static const CXXRecordDecl *getContainedDynamicClass(QualType T,
4690                                                     bool &IsContained) {
4691  // Look through array types while ignoring qualifiers.
4692  const Type *Ty = T->getBaseElementTypeUnsafe();
4693  IsContained = false;
4694
4695  const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
4696  RD = RD ? RD->getDefinition() : nullptr;
4697  if (!RD)
4698    return nullptr;
4699
4700  if (RD->isDynamicClass())
4701    return RD;
4702
4703  // Check all the fields.  If any bases were dynamic, the class is dynamic.
4704  // It's impossible for a class to transitively contain itself by value, so
4705  // infinite recursion is impossible.
4706  for (auto *FD : RD->fields()) {
4707    bool SubContained;
4708    if (const CXXRecordDecl *ContainedRD =
4709            getContainedDynamicClass(FD->getType(), SubContained)) {
4710      IsContained = true;
4711      return ContainedRD;
4712    }
4713  }
4714
4715  return nullptr;
4716}
4717
4718/// \brief If E is a sizeof expression, returns its argument expression,
4719/// otherwise returns NULL.
4720static const Expr *getSizeOfExprArg(const Expr *E) {
4721  if (const UnaryExprOrTypeTraitExpr *SizeOf =
4722      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
4723    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
4724      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
4725
4726  return nullptr;
4727}
4728
4729/// \brief If E is a sizeof expression, returns its argument type.
4730static QualType getSizeOfArgType(const Expr *E) {
4731  if (const UnaryExprOrTypeTraitExpr *SizeOf =
4732      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
4733    if (SizeOf->getKind() == clang::UETT_SizeOf)
4734      return SizeOf->getTypeOfArgument();
4735
4736  return QualType();
4737}
4738
4739/// \brief Check for dangerous or invalid arguments to memset().
4740///
4741/// This issues warnings on known problematic, dangerous or unspecified
4742/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
4743/// function calls.
4744///
4745/// \param Call The call expression to diagnose.
4746void Sema::CheckMemaccessArguments(const CallExpr *Call,
4747                                   unsigned BId,
4748                                   IdentifierInfo *FnName) {
4749  assert(BId != 0);
4750
4751  // It is possible to have a non-standard definition of memset.  Validate
4752  // we have enough arguments, and if not, abort further checking.
4753  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
4754  if (Call->getNumArgs() < ExpectedNumArgs)
4755    return;
4756
4757  unsigned LastArg = (BId == Builtin::BImemset ||
4758                      BId == Builtin::BIstrndup ? 1 : 2);
4759  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
4760  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
4761
4762  if (CheckMemorySizeofForComparison(*this, LenExpr, FnName,
4763                                     Call->getLocStart(), Call->getRParenLoc()))
4764    return;
4765
4766  // We have special checking when the length is a sizeof expression.
4767  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
4768  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
4769  llvm::FoldingSetNodeID SizeOfArgID;
4770
4771  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
4772    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
4773    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
4774
4775    QualType DestTy = Dest->getType();
4776    QualType PointeeTy;
4777    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
4778      PointeeTy = DestPtrTy->getPointeeType();
4779
4780      // Never warn about void type pointers. This can be used to suppress
4781      // false positives.
4782      if (PointeeTy->isVoidType())
4783        continue;
4784
4785      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
4786      // actually comparing the expressions for equality. Because computing the
4787      // expression IDs can be expensive, we only do this if the diagnostic is
4788      // enabled.
4789      if (SizeOfArg &&
4790          !Diags.isIgnored(diag::warn_sizeof_pointer_expr_memaccess,
4791                           SizeOfArg->getExprLoc())) {
4792        // We only compute IDs for expressions if the warning is enabled, and
4793        // cache the sizeof arg's ID.
4794        if (SizeOfArgID == llvm::FoldingSetNodeID())
4795          SizeOfArg->Profile(SizeOfArgID, Context, true);
4796        llvm::FoldingSetNodeID DestID;
4797        Dest->Profile(DestID, Context, true);
4798        if (DestID == SizeOfArgID) {
4799          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
4800          //       over sizeof(src) as well.
4801          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
4802          StringRef ReadableName = FnName->getName();
4803
4804          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
4805            if (UnaryOp->getOpcode() == UO_AddrOf)
4806              ActionIdx = 1; // If its an address-of operator, just remove it.
4807          if (!PointeeTy->isIncompleteType() &&
4808              (Context.getTypeSize(PointeeTy) == Context.getCharWidth()))
4809            ActionIdx = 2; // If the pointee's size is sizeof(char),
4810                           // suggest an explicit length.
4811
4812          // If the function is defined as a builtin macro, do not show macro
4813          // expansion.
4814          SourceLocation SL = SizeOfArg->getExprLoc();
4815          SourceRange DSR = Dest->getSourceRange();
4816          SourceRange SSR = SizeOfArg->getSourceRange();
4817          SourceManager &SM = getSourceManager();
4818
4819          if (SM.isMacroArgExpansion(SL)) {
4820            ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
4821            SL = SM.getSpellingLoc(SL);
4822            DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
4823                             SM.getSpellingLoc(DSR.getEnd()));
4824            SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
4825                             SM.getSpellingLoc(SSR.getEnd()));
4826          }
4827
4828          DiagRuntimeBehavior(SL, SizeOfArg,
4829                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
4830                                << ReadableName
4831                                << PointeeTy
4832                                << DestTy
4833                                << DSR
4834                                << SSR);
4835          DiagRuntimeBehavior(SL, SizeOfArg,
4836                         PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
4837                                << ActionIdx
4838                                << SSR);
4839
4840          break;
4841        }
4842      }
4843
4844      // Also check for cases where the sizeof argument is the exact same
4845      // type as the memory argument, and where it points to a user-defined
4846      // record type.
4847      if (SizeOfArgTy != QualType()) {
4848        if (PointeeTy->isRecordType() &&
4849            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
4850          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
4851                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
4852                                << FnName << SizeOfArgTy << ArgIdx
4853                                << PointeeTy << Dest->getSourceRange()
4854                                << LenExpr->getSourceRange());
4855          break;
4856        }
4857      }
4858    } else if (DestTy->isArrayType()) {
4859      PointeeTy = DestTy;
4860    }
4861
4862    if (PointeeTy == QualType())
4863      continue;
4864
4865    // Always complain about dynamic classes.
4866    bool IsContained;
4867    if (const CXXRecordDecl *ContainedRD =
4868            getContainedDynamicClass(PointeeTy, IsContained)) {
4869
4870      unsigned OperationType = 0;
4871      // "overwritten" if we're warning about the destination for any call
4872      // but memcmp; otherwise a verb appropriate to the call.
4873      if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
4874        if (BId == Builtin::BImemcpy)
4875          OperationType = 1;
4876        else if(BId == Builtin::BImemmove)
4877          OperationType = 2;
4878        else if (BId == Builtin::BImemcmp)
4879          OperationType = 3;
4880      }
4881
4882      DiagRuntimeBehavior(
4883        Dest->getExprLoc(), Dest,
4884        PDiag(diag::warn_dyn_class_memaccess)
4885          << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
4886          << FnName << IsContained << ContainedRD << OperationType
4887          << Call->getCallee()->getSourceRange());
4888    } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
4889             BId != Builtin::BImemset)
4890      DiagRuntimeBehavior(
4891        Dest->getExprLoc(), Dest,
4892        PDiag(diag::warn_arc_object_memaccess)
4893          << ArgIdx << FnName << PointeeTy
4894          << Call->getCallee()->getSourceRange());
4895    else
4896      continue;
4897
4898    DiagRuntimeBehavior(
4899      Dest->getExprLoc(), Dest,
4900      PDiag(diag::note_bad_memaccess_silence)
4901        << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
4902    break;
4903  }
4904
4905}
4906
4907// A little helper routine: ignore addition and subtraction of integer literals.
4908// This intentionally does not ignore all integer constant expressions because
4909// we don't want to remove sizeof().
4910static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
4911  Ex = Ex->IgnoreParenCasts();
4912
4913  for (;;) {
4914    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
4915    if (!BO || !BO->isAdditiveOp())
4916      break;
4917
4918    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
4919    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
4920
4921    if (isa<IntegerLiteral>(RHS))
4922      Ex = LHS;
4923    else if (isa<IntegerLiteral>(LHS))
4924      Ex = RHS;
4925    else
4926      break;
4927  }
4928
4929  return Ex;
4930}
4931
4932static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
4933                                                      ASTContext &Context) {
4934  // Only handle constant-sized or VLAs, but not flexible members.
4935  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
4936    // Only issue the FIXIT for arrays of size > 1.
4937    if (CAT->getSize().getSExtValue() <= 1)
4938      return false;
4939  } else if (!Ty->isVariableArrayType()) {
4940    return false;
4941  }
4942  return true;
4943}
4944
4945// Warn if the user has made the 'size' argument to strlcpy or strlcat
4946// be the size of the source, instead of the destination.
4947void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
4948                                    IdentifierInfo *FnName) {
4949
4950  // Don't crash if the user has the wrong number of arguments
4951  unsigned NumArgs = Call->getNumArgs();
4952  if ((NumArgs != 3) && (NumArgs != 4))
4953    return;
4954
4955  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
4956  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
4957  const Expr *CompareWithSrc = nullptr;
4958
4959  if (CheckMemorySizeofForComparison(*this, SizeArg, FnName,
4960                                     Call->getLocStart(), Call->getRParenLoc()))
4961    return;
4962
4963  // Look for 'strlcpy(dst, x, sizeof(x))'
4964  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
4965    CompareWithSrc = Ex;
4966  else {
4967    // Look for 'strlcpy(dst, x, strlen(x))'
4968    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
4969      if (SizeCall->getBuiltinCallee() == Builtin::BIstrlen &&
4970          SizeCall->getNumArgs() == 1)
4971        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
4972    }
4973  }
4974
4975  if (!CompareWithSrc)
4976    return;
4977
4978  // Determine if the argument to sizeof/strlen is equal to the source
4979  // argument.  In principle there's all kinds of things you could do
4980  // here, for instance creating an == expression and evaluating it with
4981  // EvaluateAsBooleanCondition, but this uses a more direct technique:
4982  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
4983  if (!SrcArgDRE)
4984    return;
4985
4986  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
4987  if (!CompareWithSrcDRE ||
4988      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
4989    return;
4990
4991  const Expr *OriginalSizeArg = Call->getArg(2);
4992  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
4993    << OriginalSizeArg->getSourceRange() << FnName;
4994
4995  // Output a FIXIT hint if the destination is an array (rather than a
4996  // pointer to an array).  This could be enhanced to handle some
4997  // pointers if we know the actual size, like if DstArg is 'array+2'
4998  // we could say 'sizeof(array)-2'.
4999  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
5000  if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
5001    return;
5002
5003  SmallString<128> sizeString;
5004  llvm::raw_svector_ostream OS(sizeString);
5005  OS << "sizeof(";
5006  DstArg->printPretty(OS, nullptr, getPrintingPolicy());
5007  OS << ")";
5008
5009  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
5010    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
5011                                    OS.str());
5012}
5013
5014/// Check if two expressions refer to the same declaration.
5015static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
5016  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
5017    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
5018      return D1->getDecl() == D2->getDecl();
5019  return false;
5020}
5021
5022static const Expr *getStrlenExprArg(const Expr *E) {
5023  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
5024    const FunctionDecl *FD = CE->getDirectCallee();
5025    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
5026      return nullptr;
5027    return CE->getArg(0)->IgnoreParenCasts();
5028  }
5029  return nullptr;
5030}
5031
5032// Warn on anti-patterns as the 'size' argument to strncat.
5033// The correct size argument should look like following:
5034//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
5035void Sema::CheckStrncatArguments(const CallExpr *CE,
5036                                 IdentifierInfo *FnName) {
5037  // Don't crash if the user has the wrong number of arguments.
5038  if (CE->getNumArgs() < 3)
5039    return;
5040  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
5041  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
5042  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
5043
5044  if (CheckMemorySizeofForComparison(*this, LenArg, FnName, CE->getLocStart(),
5045                                     CE->getRParenLoc()))
5046    return;
5047
5048  // Identify common expressions, which are wrongly used as the size argument
5049  // to strncat and may lead to buffer overflows.
5050  unsigned PatternType = 0;
5051  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
5052    // - sizeof(dst)
5053    if (referToTheSameDecl(SizeOfArg, DstArg))
5054      PatternType = 1;
5055    // - sizeof(src)
5056    else if (referToTheSameDecl(SizeOfArg, SrcArg))
5057      PatternType = 2;
5058  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
5059    if (BE->getOpcode() == BO_Sub) {
5060      const Expr *L = BE->getLHS()->IgnoreParenCasts();
5061      const Expr *R = BE->getRHS()->IgnoreParenCasts();
5062      // - sizeof(dst) - strlen(dst)
5063      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
5064          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
5065        PatternType = 1;
5066      // - sizeof(src) - (anything)
5067      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
5068        PatternType = 2;
5069    }
5070  }
5071
5072  if (PatternType == 0)
5073    return;
5074
5075  // Generate the diagnostic.
5076  SourceLocation SL = LenArg->getLocStart();
5077  SourceRange SR = LenArg->getSourceRange();
5078  SourceManager &SM = getSourceManager();
5079
5080  // If the function is defined as a builtin macro, do not show macro expansion.
5081  if (SM.isMacroArgExpansion(SL)) {
5082    SL = SM.getSpellingLoc(SL);
5083    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
5084                     SM.getSpellingLoc(SR.getEnd()));
5085  }
5086
5087  // Check if the destination is an array (rather than a pointer to an array).
5088  QualType DstTy = DstArg->getType();
5089  bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
5090                                                                    Context);
5091  if (!isKnownSizeArray) {
5092    if (PatternType == 1)
5093      Diag(SL, diag::warn_strncat_wrong_size) << SR;
5094    else
5095      Diag(SL, diag::warn_strncat_src_size) << SR;
5096    return;
5097  }
5098
5099  if (PatternType == 1)
5100    Diag(SL, diag::warn_strncat_large_size) << SR;
5101  else
5102    Diag(SL, diag::warn_strncat_src_size) << SR;
5103
5104  SmallString<128> sizeString;
5105  llvm::raw_svector_ostream OS(sizeString);
5106  OS << "sizeof(";
5107  DstArg->printPretty(OS, nullptr, getPrintingPolicy());
5108  OS << ") - ";
5109  OS << "strlen(";
5110  DstArg->printPretty(OS, nullptr, getPrintingPolicy());
5111  OS << ") - 1";
5112
5113  Diag(SL, diag::note_strncat_wrong_size)
5114    << FixItHint::CreateReplacement(SR, OS.str());
5115}
5116
5117//===--- CHECK: Return Address of Stack Variable --------------------------===//
5118
5119static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
5120                     Decl *ParentDecl);
5121static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
5122                      Decl *ParentDecl);
5123
5124/// CheckReturnStackAddr - Check if a return statement returns the address
5125///   of a stack variable.
5126static void
5127CheckReturnStackAddr(Sema &S, Expr *RetValExp, QualType lhsType,
5128                     SourceLocation ReturnLoc) {
5129
5130  Expr *stackE = nullptr;
5131  SmallVector<DeclRefExpr *, 8> refVars;
5132
5133  // Perform checking for returned stack addresses, local blocks,
5134  // label addresses or references to temporaries.
5135  if (lhsType->isPointerType() ||
5136      (!S.getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
5137    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/nullptr);
5138  } else if (lhsType->isReferenceType()) {
5139    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/nullptr);
5140  }
5141
5142  if (!stackE)
5143    return; // Nothing suspicious was found.
5144
5145  SourceLocation diagLoc;
5146  SourceRange diagRange;
5147  if (refVars.empty()) {
5148    diagLoc = stackE->getLocStart();
5149    diagRange = stackE->getSourceRange();
5150  } else {
5151    // We followed through a reference variable. 'stackE' contains the
5152    // problematic expression but we will warn at the return statement pointing
5153    // at the reference variable. We will later display the "trail" of
5154    // reference variables using notes.
5155    diagLoc = refVars[0]->getLocStart();
5156    diagRange = refVars[0]->getSourceRange();
5157  }
5158
5159  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
5160    S.Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
5161                                             : diag::warn_ret_stack_addr)
5162     << DR->getDecl()->getDeclName() << diagRange;
5163  } else if (isa<BlockExpr>(stackE)) { // local block.
5164    S.Diag(diagLoc, diag::err_ret_local_block) << diagRange;
5165  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
5166    S.Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
5167  } else { // local temporary.
5168    S.Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
5169                                               : diag::warn_ret_local_temp_addr)
5170     << diagRange;
5171  }
5172
5173  // Display the "trail" of reference variables that we followed until we
5174  // found the problematic expression using notes.
5175  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
5176    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
5177    // If this var binds to another reference var, show the range of the next
5178    // var, otherwise the var binds to the problematic expression, in which case
5179    // show the range of the expression.
5180    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
5181                                  : stackE->getSourceRange();
5182    S.Diag(VD->getLocation(), diag::note_ref_var_local_bind)
5183        << VD->getDeclName() << range;
5184  }
5185}
5186
5187/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
5188///  check if the expression in a return statement evaluates to an address
5189///  to a location on the stack, a local block, an address of a label, or a
5190///  reference to local temporary. The recursion is used to traverse the
5191///  AST of the return expression, with recursion backtracking when we
5192///  encounter a subexpression that (1) clearly does not lead to one of the
5193///  above problematic expressions (2) is something we cannot determine leads to
5194///  a problematic expression based on such local checking.
5195///
5196///  Both EvalAddr and EvalVal follow through reference variables to evaluate
5197///  the expression that they point to. Such variables are added to the
5198///  'refVars' vector so that we know what the reference variable "trail" was.
5199///
5200///  EvalAddr processes expressions that are pointers that are used as
5201///  references (and not L-values).  EvalVal handles all other values.
5202///  At the base case of the recursion is a check for the above problematic
5203///  expressions.
5204///
5205///  This implementation handles:
5206///
5207///   * pointer-to-pointer casts
5208///   * implicit conversions from array references to pointers
5209///   * taking the address of fields
5210///   * arbitrary interplay between "&" and "*" operators
5211///   * pointer arithmetic from an address of a stack variable
5212///   * taking the address of an array element where the array is on the stack
5213static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
5214                      Decl *ParentDecl) {
5215  if (E->isTypeDependent())
5216    return nullptr;
5217
5218  // We should only be called for evaluating pointer expressions.
5219  assert((E->getType()->isAnyPointerType() ||
5220          E->getType()->isBlockPointerType() ||
5221          E->getType()->isObjCQualifiedIdType()) &&
5222         "EvalAddr only works on pointers");
5223
5224  E = E->IgnoreParens();
5225
5226  // Our "symbolic interpreter" is just a dispatch off the currently
5227  // viewed AST node.  We then recursively traverse the AST by calling
5228  // EvalAddr and EvalVal appropriately.
5229  switch (E->getStmtClass()) {
5230  case Stmt::DeclRefExprClass: {
5231    DeclRefExpr *DR = cast<DeclRefExpr>(E);
5232
5233    // If we leave the immediate function, the lifetime isn't about to end.
5234    if (DR->refersToEnclosingVariableOrCapture())
5235      return nullptr;
5236
5237    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
5238      // If this is a reference variable, follow through to the expression that
5239      // it points to.
5240      if (V->hasLocalStorage() &&
5241          V->getType()->isReferenceType() && V->hasInit()) {
5242        // Add the reference variable to the "trail".
5243        refVars.push_back(DR);
5244        return EvalAddr(V->getInit(), refVars, ParentDecl);
5245      }
5246
5247    return nullptr;
5248  }
5249
5250  case Stmt::UnaryOperatorClass: {
5251    // The only unary operator that make sense to handle here
5252    // is AddrOf.  All others don't make sense as pointers.
5253    UnaryOperator *U = cast<UnaryOperator>(E);
5254
5255    if (U->getOpcode() == UO_AddrOf)
5256      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
5257    else
5258      return nullptr;
5259  }
5260
5261  case Stmt::BinaryOperatorClass: {
5262    // Handle pointer arithmetic.  All other binary operators are not valid
5263    // in this context.
5264    BinaryOperator *B = cast<BinaryOperator>(E);
5265    BinaryOperatorKind op = B->getOpcode();
5266
5267    if (op != BO_Add && op != BO_Sub)
5268      return nullptr;
5269
5270    Expr *Base = B->getLHS();
5271
5272    // Determine which argument is the real pointer base.  It could be
5273    // the RHS argument instead of the LHS.
5274    if (!Base->getType()->isPointerType()) Base = B->getRHS();
5275
5276    assert (Base->getType()->isPointerType());
5277    return EvalAddr(Base, refVars, ParentDecl);
5278  }
5279
5280  // For conditional operators we need to see if either the LHS or RHS are
5281  // valid DeclRefExpr*s.  If one of them is valid, we return it.
5282  case Stmt::ConditionalOperatorClass: {
5283    ConditionalOperator *C = cast<ConditionalOperator>(E);
5284
5285    // Handle the GNU extension for missing LHS.
5286    // FIXME: That isn't a ConditionalOperator, so doesn't get here.
5287    if (Expr *LHSExpr = C->getLHS()) {
5288      // In C++, we can have a throw-expression, which has 'void' type.
5289      if (!LHSExpr->getType()->isVoidType())
5290        if (Expr *LHS = EvalAddr(LHSExpr, refVars, ParentDecl))
5291          return LHS;
5292    }
5293
5294    // In C++, we can have a throw-expression, which has 'void' type.
5295    if (C->getRHS()->getType()->isVoidType())
5296      return nullptr;
5297
5298    return EvalAddr(C->getRHS(), refVars, ParentDecl);
5299  }
5300
5301  case Stmt::BlockExprClass:
5302    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
5303      return E; // local block.
5304    return nullptr;
5305
5306  case Stmt::AddrLabelExprClass:
5307    return E; // address of label.
5308
5309  case Stmt::ExprWithCleanupsClass:
5310    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
5311                    ParentDecl);
5312
5313  // For casts, we need to handle conversions from arrays to
5314  // pointer values, and pointer-to-pointer conversions.
5315  case Stmt::ImplicitCastExprClass:
5316  case Stmt::CStyleCastExprClass:
5317  case Stmt::CXXFunctionalCastExprClass:
5318  case Stmt::ObjCBridgedCastExprClass:
5319  case Stmt::CXXStaticCastExprClass:
5320  case Stmt::CXXDynamicCastExprClass:
5321  case Stmt::CXXConstCastExprClass:
5322  case Stmt::CXXReinterpretCastExprClass: {
5323    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
5324    switch (cast<CastExpr>(E)->getCastKind()) {
5325    case CK_LValueToRValue:
5326    case CK_NoOp:
5327    case CK_BaseToDerived:
5328    case CK_DerivedToBase:
5329    case CK_UncheckedDerivedToBase:
5330    case CK_Dynamic:
5331    case CK_CPointerToObjCPointerCast:
5332    case CK_BlockPointerToObjCPointerCast:
5333    case CK_AnyPointerToBlockPointerCast:
5334      return EvalAddr(SubExpr, refVars, ParentDecl);
5335
5336    case CK_ArrayToPointerDecay:
5337      return EvalVal(SubExpr, refVars, ParentDecl);
5338
5339    case CK_BitCast:
5340      if (SubExpr->getType()->isAnyPointerType() ||
5341          SubExpr->getType()->isBlockPointerType() ||
5342          SubExpr->getType()->isObjCQualifiedIdType())
5343        return EvalAddr(SubExpr, refVars, ParentDecl);
5344      else
5345        return nullptr;
5346
5347    default:
5348      return nullptr;
5349    }
5350  }
5351
5352  case Stmt::MaterializeTemporaryExprClass:
5353    if (Expr *Result = EvalAddr(
5354                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
5355                                refVars, ParentDecl))
5356      return Result;
5357
5358    return E;
5359
5360  // Everything else: we simply don't reason about them.
5361  default:
5362    return nullptr;
5363  }
5364}
5365
5366
5367///  EvalVal - This function is complements EvalAddr in the mutual recursion.
5368///   See the comments for EvalAddr for more details.
5369static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
5370                     Decl *ParentDecl) {
5371do {
5372  // We should only be called for evaluating non-pointer expressions, or
5373  // expressions with a pointer type that are not used as references but instead
5374  // are l-values (e.g., DeclRefExpr with a pointer type).
5375
5376  // Our "symbolic interpreter" is just a dispatch off the currently
5377  // viewed AST node.  We then recursively traverse the AST by calling
5378  // EvalAddr and EvalVal appropriately.
5379
5380  E = E->IgnoreParens();
5381  switch (E->getStmtClass()) {
5382  case Stmt::ImplicitCastExprClass: {
5383    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
5384    if (IE->getValueKind() == VK_LValue) {
5385      E = IE->getSubExpr();
5386      continue;
5387    }
5388    return nullptr;
5389  }
5390
5391  case Stmt::ExprWithCleanupsClass:
5392    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
5393
5394  case Stmt::DeclRefExprClass: {
5395    // When we hit a DeclRefExpr we are looking at code that refers to a
5396    // variable's name. If it's not a reference variable we check if it has
5397    // local storage within the function, and if so, return the expression.
5398    DeclRefExpr *DR = cast<DeclRefExpr>(E);
5399
5400    // If we leave the immediate function, the lifetime isn't about to end.
5401    if (DR->refersToEnclosingVariableOrCapture())
5402      return nullptr;
5403
5404    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
5405      // Check if it refers to itself, e.g. "int& i = i;".
5406      if (V == ParentDecl)
5407        return DR;
5408
5409      if (V->hasLocalStorage()) {
5410        if (!V->getType()->isReferenceType())
5411          return DR;
5412
5413        // Reference variable, follow through to the expression that
5414        // it points to.
5415        if (V->hasInit()) {
5416          // Add the reference variable to the "trail".
5417          refVars.push_back(DR);
5418          return EvalVal(V->getInit(), refVars, V);
5419        }
5420      }
5421    }
5422
5423    return nullptr;
5424  }
5425
5426  case Stmt::UnaryOperatorClass: {
5427    // The only unary operator that make sense to handle here
5428    // is Deref.  All others don't resolve to a "name."  This includes
5429    // handling all sorts of rvalues passed to a unary operator.
5430    UnaryOperator *U = cast<UnaryOperator>(E);
5431
5432    if (U->getOpcode() == UO_Deref)
5433      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
5434
5435    return nullptr;
5436  }
5437
5438  case Stmt::ArraySubscriptExprClass: {
5439    // Array subscripts are potential references to data on the stack.  We
5440    // retrieve the DeclRefExpr* for the array variable if it indeed
5441    // has local storage.
5442    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
5443  }
5444
5445  case Stmt::ConditionalOperatorClass: {
5446    // For conditional operators we need to see if either the LHS or RHS are
5447    // non-NULL Expr's.  If one is non-NULL, we return it.
5448    ConditionalOperator *C = cast<ConditionalOperator>(E);
5449
5450    // Handle the GNU extension for missing LHS.
5451    if (Expr *LHSExpr = C->getLHS()) {
5452      // In C++, we can have a throw-expression, which has 'void' type.
5453      if (!LHSExpr->getType()->isVoidType())
5454        if (Expr *LHS = EvalVal(LHSExpr, refVars, ParentDecl))
5455          return LHS;
5456    }
5457
5458    // In C++, we can have a throw-expression, which has 'void' type.
5459    if (C->getRHS()->getType()->isVoidType())
5460      return nullptr;
5461
5462    return EvalVal(C->getRHS(), refVars, ParentDecl);
5463  }
5464
5465  // Accesses to members are potential references to data on the stack.
5466  case Stmt::MemberExprClass: {
5467    MemberExpr *M = cast<MemberExpr>(E);
5468
5469    // Check for indirect access.  We only want direct field accesses.
5470    if (M->isArrow())
5471      return nullptr;
5472
5473    // Check whether the member type is itself a reference, in which case
5474    // we're not going to refer to the member, but to what the member refers to.
5475    if (M->getMemberDecl()->getType()->isReferenceType())
5476      return nullptr;
5477
5478    return EvalVal(M->getBase(), refVars, ParentDecl);
5479  }
5480
5481  case Stmt::MaterializeTemporaryExprClass:
5482    if (Expr *Result = EvalVal(
5483                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
5484                               refVars, ParentDecl))
5485      return Result;
5486
5487    return E;
5488
5489  default:
5490    // Check that we don't return or take the address of a reference to a
5491    // temporary. This is only useful in C++.
5492    if (!E->isTypeDependent() && E->isRValue())
5493      return E;
5494
5495    // Everything else: we simply don't reason about them.
5496    return nullptr;
5497  }
5498} while (true);
5499}
5500
5501void
5502Sema::CheckReturnValExpr(Expr *RetValExp, QualType lhsType,
5503                         SourceLocation ReturnLoc,
5504                         bool isObjCMethod,
5505                         const AttrVec *Attrs,
5506                         const FunctionDecl *FD) {
5507  CheckReturnStackAddr(*this, RetValExp, lhsType, ReturnLoc);
5508
5509  // Check if the return value is null but should not be.
5510  if (Attrs && hasSpecificAttr<ReturnsNonNullAttr>(*Attrs) &&
5511      CheckNonNullExpr(*this, RetValExp))
5512    Diag(ReturnLoc, diag::warn_null_ret)
5513      << (isObjCMethod ? 1 : 0) << RetValExp->getSourceRange();
5514
5515  // C++11 [basic.stc.dynamic.allocation]p4:
5516  //   If an allocation function declared with a non-throwing
5517  //   exception-specification fails to allocate storage, it shall return
5518  //   a null pointer. Any other allocation function that fails to allocate
5519  //   storage shall indicate failure only by throwing an exception [...]
5520  if (FD) {
5521    OverloadedOperatorKind Op = FD->getOverloadedOperator();
5522    if (Op == OO_New || Op == OO_Array_New) {
5523      const FunctionProtoType *Proto
5524        = FD->getType()->castAs<FunctionProtoType>();
5525      if (!Proto->isNothrow(Context, /*ResultIfDependent*/true) &&
5526          CheckNonNullExpr(*this, RetValExp))
5527        Diag(ReturnLoc, diag::warn_operator_new_returns_null)
5528          << FD << getLangOpts().CPlusPlus11;
5529    }
5530  }
5531}
5532
5533//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
5534
5535/// Check for comparisons of floating point operands using != and ==.
5536/// Issue a warning if these are no self-comparisons, as they are not likely
5537/// to do what the programmer intended.
5538void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
5539  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
5540  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
5541
5542  // Special case: check for x == x (which is OK).
5543  // Do not emit warnings for such cases.
5544  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
5545    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
5546      if (DRL->getDecl() == DRR->getDecl())
5547        return;
5548
5549
5550  // Special case: check for comparisons against literals that can be exactly
5551  //  represented by APFloat.  In such cases, do not emit a warning.  This
5552  //  is a heuristic: often comparison against such literals are used to
5553  //  detect if a value in a variable has not changed.  This clearly can
5554  //  lead to false negatives.
5555  if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
5556    if (FLL->isExact())
5557      return;
5558  } else
5559    if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
5560      if (FLR->isExact())
5561        return;
5562
5563  // Check for comparisons with builtin types.
5564  if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
5565    if (CL->getBuiltinCallee())
5566      return;
5567
5568  if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
5569    if (CR->getBuiltinCallee())
5570      return;
5571
5572  // Emit the diagnostic.
5573  Diag(Loc, diag::warn_floatingpoint_eq)
5574    << LHS->getSourceRange() << RHS->getSourceRange();
5575}
5576
5577//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
5578//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
5579
5580namespace {
5581
5582/// Structure recording the 'active' range of an integer-valued
5583/// expression.
5584struct IntRange {
5585  /// The number of bits active in the int.
5586  unsigned Width;
5587
5588  /// True if the int is known not to have negative values.
5589  bool NonNegative;
5590
5591  IntRange(unsigned Width, bool NonNegative)
5592    : Width(Width), NonNegative(NonNegative)
5593  {}
5594
5595  /// Returns the range of the bool type.
5596  static IntRange forBoolType() {
5597    return IntRange(1, true);
5598  }
5599
5600  /// Returns the range of an opaque value of the given integral type.
5601  static IntRange forValueOfType(ASTContext &C, QualType T) {
5602    return forValueOfCanonicalType(C,
5603                          T->getCanonicalTypeInternal().getTypePtr());
5604  }
5605
5606  /// Returns the range of an opaque value of a canonical integral type.
5607  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
5608    assert(T->isCanonicalUnqualified());
5609
5610    if (const VectorType *VT = dyn_cast<VectorType>(T))
5611      T = VT->getElementType().getTypePtr();
5612    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
5613      T = CT->getElementType().getTypePtr();
5614    if (const AtomicType *AT = dyn_cast<AtomicType>(T))
5615      T = AT->getValueType().getTypePtr();
5616
5617    // For enum types, use the known bit width of the enumerators.
5618    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
5619      EnumDecl *Enum = ET->getDecl();
5620      if (!Enum->isCompleteDefinition())
5621        return IntRange(C.getIntWidth(QualType(T, 0)), false);
5622
5623      unsigned NumPositive = Enum->getNumPositiveBits();
5624      unsigned NumNegative = Enum->getNumNegativeBits();
5625
5626      if (NumNegative == 0)
5627        return IntRange(NumPositive, true/*NonNegative*/);
5628      else
5629        return IntRange(std::max(NumPositive + 1, NumNegative),
5630                        false/*NonNegative*/);
5631    }
5632
5633    const BuiltinType *BT = cast<BuiltinType>(T);
5634    assert(BT->isInteger());
5635
5636    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
5637  }
5638
5639  /// Returns the "target" range of a canonical integral type, i.e.
5640  /// the range of values expressible in the type.
5641  ///
5642  /// This matches forValueOfCanonicalType except that enums have the
5643  /// full range of their type, not the range of their enumerators.
5644  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
5645    assert(T->isCanonicalUnqualified());
5646
5647    if (const VectorType *VT = dyn_cast<VectorType>(T))
5648      T = VT->getElementType().getTypePtr();
5649    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
5650      T = CT->getElementType().getTypePtr();
5651    if (const AtomicType *AT = dyn_cast<AtomicType>(T))
5652      T = AT->getValueType().getTypePtr();
5653    if (const EnumType *ET = dyn_cast<EnumType>(T))
5654      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
5655
5656    const BuiltinType *BT = cast<BuiltinType>(T);
5657    assert(BT->isInteger());
5658
5659    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
5660  }
5661
5662  /// Returns the supremum of two ranges: i.e. their conservative merge.
5663  static IntRange join(IntRange L, IntRange R) {
5664    return IntRange(std::max(L.Width, R.Width),
5665                    L.NonNegative && R.NonNegative);
5666  }
5667
5668  /// Returns the infinum of two ranges: i.e. their aggressive merge.
5669  static IntRange meet(IntRange L, IntRange R) {
5670    return IntRange(std::min(L.Width, R.Width),
5671                    L.NonNegative || R.NonNegative);
5672  }
5673};
5674
5675static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
5676                              unsigned MaxWidth) {
5677  if (value.isSigned() && value.isNegative())
5678    return IntRange(value.getMinSignedBits(), false);
5679
5680  if (value.getBitWidth() > MaxWidth)
5681    value = value.trunc(MaxWidth);
5682
5683  // isNonNegative() just checks the sign bit without considering
5684  // signedness.
5685  return IntRange(value.getActiveBits(), true);
5686}
5687
5688static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
5689                              unsigned MaxWidth) {
5690  if (result.isInt())
5691    return GetValueRange(C, result.getInt(), MaxWidth);
5692
5693  if (result.isVector()) {
5694    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
5695    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
5696      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
5697      R = IntRange::join(R, El);
5698    }
5699    return R;
5700  }
5701
5702  if (result.isComplexInt()) {
5703    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
5704    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
5705    return IntRange::join(R, I);
5706  }
5707
5708  // This can happen with lossless casts to intptr_t of "based" lvalues.
5709  // Assume it might use arbitrary bits.
5710  // FIXME: The only reason we need to pass the type in here is to get
5711  // the sign right on this one case.  It would be nice if APValue
5712  // preserved this.
5713  assert(result.isLValue() || result.isAddrLabelDiff());
5714  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
5715}
5716
5717static QualType GetExprType(Expr *E) {
5718  QualType Ty = E->getType();
5719  if (const AtomicType *AtomicRHS = Ty->getAs<AtomicType>())
5720    Ty = AtomicRHS->getValueType();
5721  return Ty;
5722}
5723
5724/// Pseudo-evaluate the given integer expression, estimating the
5725/// range of values it might take.
5726///
5727/// \param MaxWidth - the width to which the value will be truncated
5728static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
5729  E = E->IgnoreParens();
5730
5731  // Try a full evaluation first.
5732  Expr::EvalResult result;
5733  if (E->EvaluateAsRValue(result, C))
5734    return GetValueRange(C, result.Val, GetExprType(E), MaxWidth);
5735
5736  // I think we only want to look through implicit casts here; if the
5737  // user has an explicit widening cast, we should treat the value as
5738  // being of the new, wider type.
5739  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
5740    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
5741      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
5742
5743    IntRange OutputTypeRange = IntRange::forValueOfType(C, GetExprType(CE));
5744
5745    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
5746
5747    // Assume that non-integer casts can span the full range of the type.
5748    if (!isIntegerCast)
5749      return OutputTypeRange;
5750
5751    IntRange SubRange
5752      = GetExprRange(C, CE->getSubExpr(),
5753                     std::min(MaxWidth, OutputTypeRange.Width));
5754
5755    // Bail out if the subexpr's range is as wide as the cast type.
5756    if (SubRange.Width >= OutputTypeRange.Width)
5757      return OutputTypeRange;
5758
5759    // Otherwise, we take the smaller width, and we're non-negative if
5760    // either the output type or the subexpr is.
5761    return IntRange(SubRange.Width,
5762                    SubRange.NonNegative || OutputTypeRange.NonNegative);
5763  }
5764
5765  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
5766    // If we can fold the condition, just take that operand.
5767    bool CondResult;
5768    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
5769      return GetExprRange(C, CondResult ? CO->getTrueExpr()
5770                                        : CO->getFalseExpr(),
5771                          MaxWidth);
5772
5773    // Otherwise, conservatively merge.
5774    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
5775    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
5776    return IntRange::join(L, R);
5777  }
5778
5779  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
5780    switch (BO->getOpcode()) {
5781
5782    // Boolean-valued operations are single-bit and positive.
5783    case BO_LAnd:
5784    case BO_LOr:
5785    case BO_LT:
5786    case BO_GT:
5787    case BO_LE:
5788    case BO_GE:
5789    case BO_EQ:
5790    case BO_NE:
5791      return IntRange::forBoolType();
5792
5793    // The type of the assignments is the type of the LHS, so the RHS
5794    // is not necessarily the same type.
5795    case BO_MulAssign:
5796    case BO_DivAssign:
5797    case BO_RemAssign:
5798    case BO_AddAssign:
5799    case BO_SubAssign:
5800    case BO_XorAssign:
5801    case BO_OrAssign:
5802      // TODO: bitfields?
5803      return IntRange::forValueOfType(C, GetExprType(E));
5804
5805    // Simple assignments just pass through the RHS, which will have
5806    // been coerced to the LHS type.
5807    case BO_Assign:
5808      // TODO: bitfields?
5809      return GetExprRange(C, BO->getRHS(), MaxWidth);
5810
5811    // Operations with opaque sources are black-listed.
5812    case BO_PtrMemD:
5813    case BO_PtrMemI:
5814      return IntRange::forValueOfType(C, GetExprType(E));
5815
5816    // Bitwise-and uses the *infinum* of the two source ranges.
5817    case BO_And:
5818    case BO_AndAssign:
5819      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
5820                            GetExprRange(C, BO->getRHS(), MaxWidth));
5821
5822    // Left shift gets black-listed based on a judgement call.
5823    case BO_Shl:
5824      // ...except that we want to treat '1 << (blah)' as logically
5825      // positive.  It's an important idiom.
5826      if (IntegerLiteral *I
5827            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
5828        if (I->getValue() == 1) {
5829          IntRange R = IntRange::forValueOfType(C, GetExprType(E));
5830          return IntRange(R.Width, /*NonNegative*/ true);
5831        }
5832      }
5833      // fallthrough
5834
5835    case BO_ShlAssign:
5836      return IntRange::forValueOfType(C, GetExprType(E));
5837
5838    // Right shift by a constant can narrow its left argument.
5839    case BO_Shr:
5840    case BO_ShrAssign: {
5841      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
5842
5843      // If the shift amount is a positive constant, drop the width by
5844      // that much.
5845      llvm::APSInt shift;
5846      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
5847          shift.isNonNegative()) {
5848        unsigned zext = shift.getZExtValue();
5849        if (zext >= L.Width)
5850          L.Width = (L.NonNegative ? 0 : 1);
5851        else
5852          L.Width -= zext;
5853      }
5854
5855      return L;
5856    }
5857
5858    // Comma acts as its right operand.
5859    case BO_Comma:
5860      return GetExprRange(C, BO->getRHS(), MaxWidth);
5861
5862    // Black-list pointer subtractions.
5863    case BO_Sub:
5864      if (BO->getLHS()->getType()->isPointerType())
5865        return IntRange::forValueOfType(C, GetExprType(E));
5866      break;
5867
5868    // The width of a division result is mostly determined by the size
5869    // of the LHS.
5870    case BO_Div: {
5871      // Don't 'pre-truncate' the operands.
5872      unsigned opWidth = C.getIntWidth(GetExprType(E));
5873      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
5874
5875      // If the divisor is constant, use that.
5876      llvm::APSInt divisor;
5877      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
5878        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
5879        if (log2 >= L.Width)
5880          L.Width = (L.NonNegative ? 0 : 1);
5881        else
5882          L.Width = std::min(L.Width - log2, MaxWidth);
5883        return L;
5884      }
5885
5886      // Otherwise, just use the LHS's width.
5887      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
5888      return IntRange(L.Width, L.NonNegative && R.NonNegative);
5889    }
5890
5891    // The result of a remainder can't be larger than the result of
5892    // either side.
5893    case BO_Rem: {
5894      // Don't 'pre-truncate' the operands.
5895      unsigned opWidth = C.getIntWidth(GetExprType(E));
5896      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
5897      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
5898
5899      IntRange meet = IntRange::meet(L, R);
5900      meet.Width = std::min(meet.Width, MaxWidth);
5901      return meet;
5902    }
5903
5904    // The default behavior is okay for these.
5905    case BO_Mul:
5906    case BO_Add:
5907    case BO_Xor:
5908    case BO_Or:
5909      break;
5910    }
5911
5912    // The default case is to treat the operation as if it were closed
5913    // on the narrowest type that encompasses both operands.
5914    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
5915    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
5916    return IntRange::join(L, R);
5917  }
5918
5919  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
5920    switch (UO->getOpcode()) {
5921    // Boolean-valued operations are white-listed.
5922    case UO_LNot:
5923      return IntRange::forBoolType();
5924
5925    // Operations with opaque sources are black-listed.
5926    case UO_Deref:
5927    case UO_AddrOf: // should be impossible
5928      return IntRange::forValueOfType(C, GetExprType(E));
5929
5930    default:
5931      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
5932    }
5933  }
5934
5935  if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E))
5936    return GetExprRange(C, OVE->getSourceExpr(), MaxWidth);
5937
5938  if (FieldDecl *BitField = E->getSourceBitField())
5939    return IntRange(BitField->getBitWidthValue(C),
5940                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
5941
5942  return IntRange::forValueOfType(C, GetExprType(E));
5943}
5944
5945static IntRange GetExprRange(ASTContext &C, Expr *E) {
5946  return GetExprRange(C, E, C.getIntWidth(GetExprType(E)));
5947}
5948
5949/// Checks whether the given value, which currently has the given
5950/// source semantics, has the same value when coerced through the
5951/// target semantics.
5952static bool IsSameFloatAfterCast(const llvm::APFloat &value,
5953                                 const llvm::fltSemantics &Src,
5954                                 const llvm::fltSemantics &Tgt) {
5955  llvm::APFloat truncated = value;
5956
5957  bool ignored;
5958  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
5959  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
5960
5961  return truncated.bitwiseIsEqual(value);
5962}
5963
5964/// Checks whether the given value, which currently has the given
5965/// source semantics, has the same value when coerced through the
5966/// target semantics.
5967///
5968/// The value might be a vector of floats (or a complex number).
5969static bool IsSameFloatAfterCast(const APValue &value,
5970                                 const llvm::fltSemantics &Src,
5971                                 const llvm::fltSemantics &Tgt) {
5972  if (value.isFloat())
5973    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
5974
5975  if (value.isVector()) {
5976    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
5977      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
5978        return false;
5979    return true;
5980  }
5981
5982  assert(value.isComplexFloat());
5983  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
5984          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
5985}
5986
5987static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
5988
5989static bool IsZero(Sema &S, Expr *E) {
5990  // Suppress cases where we are comparing against an enum constant.
5991  if (const DeclRefExpr *DR =
5992      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
5993    if (isa<EnumConstantDecl>(DR->getDecl()))
5994      return false;
5995
5996  // Suppress cases where the '0' value is expanded from a macro.
5997  if (E->getLocStart().isMacroID())
5998    return false;
5999
6000  llvm::APSInt Value;
6001  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
6002}
6003
6004static bool HasEnumType(Expr *E) {
6005  // Strip off implicit integral promotions.
6006  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
6007    if (ICE->getCastKind() != CK_IntegralCast &&
6008        ICE->getCastKind() != CK_NoOp)
6009      break;
6010    E = ICE->getSubExpr();
6011  }
6012
6013  return E->getType()->isEnumeralType();
6014}
6015
6016static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
6017  // Disable warning in template instantiations.
6018  if (!S.ActiveTemplateInstantiations.empty())
6019    return;
6020
6021  BinaryOperatorKind op = E->getOpcode();
6022  if (E->isValueDependent())
6023    return;
6024
6025  if (op == BO_LT && IsZero(S, E->getRHS())) {
6026    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
6027      << "< 0" << "false" << HasEnumType(E->getLHS())
6028      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
6029  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
6030    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
6031      << ">= 0" << "true" << HasEnumType(E->getLHS())
6032      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
6033  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
6034    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
6035      << "0 >" << "false" << HasEnumType(E->getRHS())
6036      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
6037  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
6038    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
6039      << "0 <=" << "true" << HasEnumType(E->getRHS())
6040      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
6041  }
6042}
6043
6044static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
6045                                         Expr *Constant, Expr *Other,
6046                                         llvm::APSInt Value,
6047                                         bool RhsConstant) {
6048  // Disable warning in template instantiations.
6049  if (!S.ActiveTemplateInstantiations.empty())
6050    return;
6051
6052  // TODO: Investigate using GetExprRange() to get tighter bounds
6053  // on the bit ranges.
6054  QualType OtherT = Other->getType();
6055  if (const AtomicType *AT = dyn_cast<AtomicType>(OtherT))
6056    OtherT = AT->getValueType();
6057  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
6058  unsigned OtherWidth = OtherRange.Width;
6059
6060  bool OtherIsBooleanType = Other->isKnownToHaveBooleanValue();
6061
6062  // 0 values are handled later by CheckTrivialUnsignedComparison().
6063  if ((Value == 0) && (!OtherIsBooleanType))
6064    return;
6065
6066  BinaryOperatorKind op = E->getOpcode();
6067  bool IsTrue = true;
6068
6069  // Used for diagnostic printout.
6070  enum {
6071    LiteralConstant = 0,
6072    CXXBoolLiteralTrue,
6073    CXXBoolLiteralFalse
6074  } LiteralOrBoolConstant = LiteralConstant;
6075
6076  if (!OtherIsBooleanType) {
6077    QualType ConstantT = Constant->getType();
6078    QualType CommonT = E->getLHS()->getType();
6079
6080    if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
6081      return;
6082    assert((OtherT->isIntegerType() && ConstantT->isIntegerType()) &&
6083           "comparison with non-integer type");
6084
6085    bool ConstantSigned = ConstantT->isSignedIntegerType();
6086    bool CommonSigned = CommonT->isSignedIntegerType();
6087
6088    bool EqualityOnly = false;
6089
6090    if (CommonSigned) {
6091      // The common type is signed, therefore no signed to unsigned conversion.
6092      if (!OtherRange.NonNegative) {
6093        // Check that the constant is representable in type OtherT.
6094        if (ConstantSigned) {
6095          if (OtherWidth >= Value.getMinSignedBits())
6096            return;
6097        } else { // !ConstantSigned
6098          if (OtherWidth >= Value.getActiveBits() + 1)
6099            return;
6100        }
6101      } else { // !OtherSigned
6102               // Check that the constant is representable in type OtherT.
6103        // Negative values are out of range.
6104        if (ConstantSigned) {
6105          if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
6106            return;
6107        } else { // !ConstantSigned
6108          if (OtherWidth >= Value.getActiveBits())
6109            return;
6110        }
6111      }
6112    } else { // !CommonSigned
6113      if (OtherRange.NonNegative) {
6114        if (OtherWidth >= Value.getActiveBits())
6115          return;
6116      } else { // OtherSigned
6117        assert(!ConstantSigned &&
6118               "Two signed types converted to unsigned types.");
6119        // Check to see if the constant is representable in OtherT.
6120        if (OtherWidth > Value.getActiveBits())
6121          return;
6122        // Check to see if the constant is equivalent to a negative value
6123        // cast to CommonT.
6124        if (S.Context.getIntWidth(ConstantT) ==
6125                S.Context.getIntWidth(CommonT) &&
6126            Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
6127          return;
6128        // The constant value rests between values that OtherT can represent
6129        // after conversion.  Relational comparison still works, but equality
6130        // comparisons will be tautological.
6131        EqualityOnly = true;
6132      }
6133    }
6134
6135    bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
6136
6137    if (op == BO_EQ || op == BO_NE) {
6138      IsTrue = op == BO_NE;
6139    } else if (EqualityOnly) {
6140      return;
6141    } else if (RhsConstant) {
6142      if (op == BO_GT || op == BO_GE)
6143        IsTrue = !PositiveConstant;
6144      else // op == BO_LT || op == BO_LE
6145        IsTrue = PositiveConstant;
6146    } else {
6147      if (op == BO_LT || op == BO_LE)
6148        IsTrue = !PositiveConstant;
6149      else // op == BO_GT || op == BO_GE
6150        IsTrue = PositiveConstant;
6151    }
6152  } else {
6153    // Other isKnownToHaveBooleanValue
6154    enum CompareBoolWithConstantResult { AFals, ATrue, Unkwn };
6155    enum ConstantValue { LT_Zero, Zero, One, GT_One, SizeOfConstVal };
6156    enum ConstantSide { Lhs, Rhs, SizeOfConstSides };
6157
6158    static const struct LinkedConditions {
6159      CompareBoolWithConstantResult BO_LT_OP[SizeOfConstSides][SizeOfConstVal];
6160      CompareBoolWithConstantResult BO_GT_OP[SizeOfConstSides][SizeOfConstVal];
6161      CompareBoolWithConstantResult BO_LE_OP[SizeOfConstSides][SizeOfConstVal];
6162      CompareBoolWithConstantResult BO_GE_OP[SizeOfConstSides][SizeOfConstVal];
6163      CompareBoolWithConstantResult BO_EQ_OP[SizeOfConstSides][SizeOfConstVal];
6164      CompareBoolWithConstantResult BO_NE_OP[SizeOfConstSides][SizeOfConstVal];
6165
6166    } TruthTable = {
6167        // Constant on LHS.              | Constant on RHS.              |
6168        // LT_Zero| Zero  | One   |GT_One| LT_Zero| Zero  | One   |GT_One|
6169        { { ATrue, Unkwn, AFals, AFals }, { AFals, AFals, Unkwn, ATrue } },
6170        { { AFals, AFals, Unkwn, ATrue }, { ATrue, Unkwn, AFals, AFals } },
6171        { { ATrue, ATrue, Unkwn, AFals }, { AFals, Unkwn, ATrue, ATrue } },
6172        { { AFals, Unkwn, ATrue, ATrue }, { ATrue, ATrue, Unkwn, AFals } },
6173        { { AFals, Unkwn, Unkwn, AFals }, { AFals, Unkwn, Unkwn, AFals } },
6174        { { ATrue, Unkwn, Unkwn, ATrue }, { ATrue, Unkwn, Unkwn, ATrue } }
6175      };
6176
6177    bool ConstantIsBoolLiteral = isa<CXXBoolLiteralExpr>(Constant);
6178
6179    enum ConstantValue ConstVal = Zero;
6180    if (Value.isUnsigned() || Value.isNonNegative()) {
6181      if (Value == 0) {
6182        LiteralOrBoolConstant =
6183            ConstantIsBoolLiteral ? CXXBoolLiteralFalse : LiteralConstant;
6184        ConstVal = Zero;
6185      } else if (Value == 1) {
6186        LiteralOrBoolConstant =
6187            ConstantIsBoolLiteral ? CXXBoolLiteralTrue : LiteralConstant;
6188        ConstVal = One;
6189      } else {
6190        LiteralOrBoolConstant = LiteralConstant;
6191        ConstVal = GT_One;
6192      }
6193    } else {
6194      ConstVal = LT_Zero;
6195    }
6196
6197    CompareBoolWithConstantResult CmpRes;
6198
6199    switch (op) {
6200    case BO_LT:
6201      CmpRes = TruthTable.BO_LT_OP[RhsConstant][ConstVal];
6202      break;
6203    case BO_GT:
6204      CmpRes = TruthTable.BO_GT_OP[RhsConstant][ConstVal];
6205      break;
6206    case BO_LE:
6207      CmpRes = TruthTable.BO_LE_OP[RhsConstant][ConstVal];
6208      break;
6209    case BO_GE:
6210      CmpRes = TruthTable.BO_GE_OP[RhsConstant][ConstVal];
6211      break;
6212    case BO_EQ:
6213      CmpRes = TruthTable.BO_EQ_OP[RhsConstant][ConstVal];
6214      break;
6215    case BO_NE:
6216      CmpRes = TruthTable.BO_NE_OP[RhsConstant][ConstVal];
6217      break;
6218    default:
6219      CmpRes = Unkwn;
6220      break;
6221    }
6222
6223    if (CmpRes == AFals) {
6224      IsTrue = false;
6225    } else if (CmpRes == ATrue) {
6226      IsTrue = true;
6227    } else {
6228      return;
6229    }
6230  }
6231
6232  // If this is a comparison to an enum constant, include that
6233  // constant in the diagnostic.
6234  const EnumConstantDecl *ED = nullptr;
6235  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
6236    ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
6237
6238  SmallString<64> PrettySourceValue;
6239  llvm::raw_svector_ostream OS(PrettySourceValue);
6240  if (ED)
6241    OS << '\'' << *ED << "' (" << Value << ")";
6242  else
6243    OS << Value;
6244
6245  S.DiagRuntimeBehavior(
6246    E->getOperatorLoc(), E,
6247    S.PDiag(diag::warn_out_of_range_compare)
6248        << OS.str() << LiteralOrBoolConstant
6249        << OtherT << (OtherIsBooleanType && !OtherT->isBooleanType()) << IsTrue
6250        << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
6251}
6252
6253/// Analyze the operands of the given comparison.  Implements the
6254/// fallback case from AnalyzeComparison.
6255static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
6256  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
6257  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
6258}
6259
6260/// \brief Implements -Wsign-compare.
6261///
6262/// \param E the binary operator to check for warnings
6263static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
6264  // The type the comparison is being performed in.
6265  QualType T = E->getLHS()->getType();
6266
6267  // Only analyze comparison operators where both sides have been converted to
6268  // the same type.
6269  if (!S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()))
6270    return AnalyzeImpConvsInComparison(S, E);
6271
6272  // Don't analyze value-dependent comparisons directly.
6273  if (E->isValueDependent())
6274    return AnalyzeImpConvsInComparison(S, E);
6275
6276  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
6277  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
6278
6279  bool IsComparisonConstant = false;
6280
6281  // Check whether an integer constant comparison results in a value
6282  // of 'true' or 'false'.
6283  if (T->isIntegralType(S.Context)) {
6284    llvm::APSInt RHSValue;
6285    bool IsRHSIntegralLiteral =
6286      RHS->isIntegerConstantExpr(RHSValue, S.Context);
6287    llvm::APSInt LHSValue;
6288    bool IsLHSIntegralLiteral =
6289      LHS->isIntegerConstantExpr(LHSValue, S.Context);
6290    if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
6291        DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
6292    else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
6293      DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
6294    else
6295      IsComparisonConstant =
6296        (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
6297  } else if (!T->hasUnsignedIntegerRepresentation())
6298      IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
6299
6300  // We don't do anything special if this isn't an unsigned integral
6301  // comparison:  we're only interested in integral comparisons, and
6302  // signed comparisons only happen in cases we don't care to warn about.
6303  //
6304  // We also don't care about value-dependent expressions or expressions
6305  // whose result is a constant.
6306  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
6307    return AnalyzeImpConvsInComparison(S, E);
6308
6309  // Check to see if one of the (unmodified) operands is of different
6310  // signedness.
6311  Expr *signedOperand, *unsignedOperand;
6312  if (LHS->getType()->hasSignedIntegerRepresentation()) {
6313    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
6314           "unsigned comparison between two signed integer expressions?");
6315    signedOperand = LHS;
6316    unsignedOperand = RHS;
6317  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
6318    signedOperand = RHS;
6319    unsignedOperand = LHS;
6320  } else {
6321    CheckTrivialUnsignedComparison(S, E);
6322    return AnalyzeImpConvsInComparison(S, E);
6323  }
6324
6325  // Otherwise, calculate the effective range of the signed operand.
6326  IntRange signedRange = GetExprRange(S.Context, signedOperand);
6327
6328  // Go ahead and analyze implicit conversions in the operands.  Note
6329  // that we skip the implicit conversions on both sides.
6330  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
6331  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
6332
6333  // If the signed range is non-negative, -Wsign-compare won't fire,
6334  // but we should still check for comparisons which are always true
6335  // or false.
6336  if (signedRange.NonNegative)
6337    return CheckTrivialUnsignedComparison(S, E);
6338
6339  // For (in)equality comparisons, if the unsigned operand is a
6340  // constant which cannot collide with a overflowed signed operand,
6341  // then reinterpreting the signed operand as unsigned will not
6342  // change the result of the comparison.
6343  if (E->isEqualityOp()) {
6344    unsigned comparisonWidth = S.Context.getIntWidth(T);
6345    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
6346
6347    // We should never be unable to prove that the unsigned operand is
6348    // non-negative.
6349    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
6350
6351    if (unsignedRange.Width < comparisonWidth)
6352      return;
6353  }
6354
6355  S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
6356    S.PDiag(diag::warn_mixed_sign_comparison)
6357      << LHS->getType() << RHS->getType()
6358      << LHS->getSourceRange() << RHS->getSourceRange());
6359}
6360
6361/// Analyzes an attempt to assign the given value to a bitfield.
6362///
6363/// Returns true if there was something fishy about the attempt.
6364static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
6365                                      SourceLocation InitLoc) {
6366  assert(Bitfield->isBitField());
6367  if (Bitfield->isInvalidDecl())
6368    return false;
6369
6370  // White-list bool bitfields.
6371  if (Bitfield->getType()->isBooleanType())
6372    return false;
6373
6374  // Ignore value- or type-dependent expressions.
6375  if (Bitfield->getBitWidth()->isValueDependent() ||
6376      Bitfield->getBitWidth()->isTypeDependent() ||
6377      Init->isValueDependent() ||
6378      Init->isTypeDependent())
6379    return false;
6380
6381  Expr *OriginalInit = Init->IgnoreParenImpCasts();
6382
6383  llvm::APSInt Value;
6384  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
6385    return false;
6386
6387  unsigned OriginalWidth = Value.getBitWidth();
6388  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
6389
6390  if (OriginalWidth <= FieldWidth)
6391    return false;
6392
6393  // Compute the value which the bitfield will contain.
6394  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
6395  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
6396
6397  // Check whether the stored value is equal to the original value.
6398  TruncatedValue = TruncatedValue.extend(OriginalWidth);
6399  if (llvm::APSInt::isSameValue(Value, TruncatedValue))
6400    return false;
6401
6402  // Special-case bitfields of width 1: booleans are naturally 0/1, and
6403  // therefore don't strictly fit into a signed bitfield of width 1.
6404  if (FieldWidth == 1 && Value == 1)
6405    return false;
6406
6407  std::string PrettyValue = Value.toString(10);
6408  std::string PrettyTrunc = TruncatedValue.toString(10);
6409
6410  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
6411    << PrettyValue << PrettyTrunc << OriginalInit->getType()
6412    << Init->getSourceRange();
6413
6414  return true;
6415}
6416
6417/// Analyze the given simple or compound assignment for warning-worthy
6418/// operations.
6419static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
6420  // Just recurse on the LHS.
6421  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
6422
6423  // We want to recurse on the RHS as normal unless we're assigning to
6424  // a bitfield.
6425  if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
6426    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
6427                                  E->getOperatorLoc())) {
6428      // Recurse, ignoring any implicit conversions on the RHS.
6429      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
6430                                        E->getOperatorLoc());
6431    }
6432  }
6433
6434  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
6435}
6436
6437/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
6438static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
6439                            SourceLocation CContext, unsigned diag,
6440                            bool pruneControlFlow = false) {
6441  if (pruneControlFlow) {
6442    S.DiagRuntimeBehavior(E->getExprLoc(), E,
6443                          S.PDiag(diag)
6444                            << SourceType << T << E->getSourceRange()
6445                            << SourceRange(CContext));
6446    return;
6447  }
6448  S.Diag(E->getExprLoc(), diag)
6449    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
6450}
6451
6452/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
6453static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
6454                            SourceLocation CContext, unsigned diag,
6455                            bool pruneControlFlow = false) {
6456  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
6457}
6458
6459/// Diagnose an implicit cast from a literal expression. Does not warn when the
6460/// cast wouldn't lose information.
6461void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
6462                                    SourceLocation CContext) {
6463  // Try to convert the literal exactly to an integer. If we can, don't warn.
6464  bool isExact = false;
6465  const llvm::APFloat &Value = FL->getValue();
6466  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
6467                            T->hasUnsignedIntegerRepresentation());
6468  if (Value.convertToInteger(IntegerValue,
6469                             llvm::APFloat::rmTowardZero, &isExact)
6470      == llvm::APFloat::opOK && isExact)
6471    return;
6472
6473  // FIXME: Force the precision of the source value down so we don't print
6474  // digits which are usually useless (we don't really care here if we
6475  // truncate a digit by accident in edge cases).  Ideally, APFloat::toString
6476  // would automatically print the shortest representation, but it's a bit
6477  // tricky to implement.
6478  SmallString<16> PrettySourceValue;
6479  unsigned precision = llvm::APFloat::semanticsPrecision(Value.getSemantics());
6480  precision = (precision * 59 + 195) / 196;
6481  Value.toString(PrettySourceValue, precision);
6482
6483  SmallString<16> PrettyTargetValue;
6484  if (T->isSpecificBuiltinType(BuiltinType::Bool))
6485    PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
6486  else
6487    IntegerValue.toString(PrettyTargetValue);
6488
6489  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
6490    << FL->getType() << T.getUnqualifiedType() << PrettySourceValue
6491    << PrettyTargetValue << FL->getSourceRange() << SourceRange(CContext);
6492}
6493
6494std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
6495  if (!Range.Width) return "0";
6496
6497  llvm::APSInt ValueInRange = Value;
6498  ValueInRange.setIsSigned(!Range.NonNegative);
6499  ValueInRange = ValueInRange.trunc(Range.Width);
6500  return ValueInRange.toString(10);
6501}
6502
6503static bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
6504  if (!isa<ImplicitCastExpr>(Ex))
6505    return false;
6506
6507  Expr *InnerE = Ex->IgnoreParenImpCasts();
6508  const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
6509  const Type *Source =
6510    S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
6511  if (Target->isDependentType())
6512    return false;
6513
6514  const BuiltinType *FloatCandidateBT =
6515    dyn_cast<BuiltinType>(ToBool ? Source : Target);
6516  const Type *BoolCandidateType = ToBool ? Target : Source;
6517
6518  return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
6519          FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
6520}
6521
6522void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
6523                                      SourceLocation CC) {
6524  unsigned NumArgs = TheCall->getNumArgs();
6525  for (unsigned i = 0; i < NumArgs; ++i) {
6526    Expr *CurrA = TheCall->getArg(i);
6527    if (!IsImplicitBoolFloatConversion(S, CurrA, true))
6528      continue;
6529
6530    bool IsSwapped = ((i > 0) &&
6531        IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
6532    IsSwapped |= ((i < (NumArgs - 1)) &&
6533        IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
6534    if (IsSwapped) {
6535      // Warn on this floating-point to bool conversion.
6536      DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
6537                      CurrA->getType(), CC,
6538                      diag::warn_impcast_floating_point_to_bool);
6539    }
6540  }
6541}
6542
6543static void DiagnoseNullConversion(Sema &S, Expr *E, QualType T,
6544                                   SourceLocation CC) {
6545  if (S.Diags.isIgnored(diag::warn_impcast_null_pointer_to_integer,
6546                        E->getExprLoc()))
6547    return;
6548
6549  // Check for NULL (GNUNull) or nullptr (CXX11_nullptr).
6550  const Expr::NullPointerConstantKind NullKind =
6551      E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull);
6552  if (NullKind != Expr::NPCK_GNUNull && NullKind != Expr::NPCK_CXX11_nullptr)
6553    return;
6554
6555  // Return if target type is a safe conversion.
6556  if (T->isAnyPointerType() || T->isBlockPointerType() ||
6557      T->isMemberPointerType() || !T->isScalarType() || T->isNullPtrType())
6558    return;
6559
6560  SourceLocation Loc = E->getSourceRange().getBegin();
6561
6562  // __null is usually wrapped in a macro.  Go up a macro if that is the case.
6563  if (NullKind == Expr::NPCK_GNUNull) {
6564    if (Loc.isMacroID())
6565      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
6566  }
6567
6568  // Only warn if the null and context location are in the same macro expansion.
6569  if (S.SourceMgr.getFileID(Loc) != S.SourceMgr.getFileID(CC))
6570    return;
6571
6572  S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
6573      << (NullKind == Expr::NPCK_CXX11_nullptr) << T << clang::SourceRange(CC)
6574      << FixItHint::CreateReplacement(Loc,
6575                                      S.getFixItZeroLiteralForType(T, Loc));
6576}
6577
6578void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
6579                             SourceLocation CC, bool *ICContext = nullptr) {
6580  if (E->isTypeDependent() || E->isValueDependent()) return;
6581
6582  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
6583  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
6584  if (Source == Target) return;
6585  if (Target->isDependentType()) return;
6586
6587  // If the conversion context location is invalid don't complain. We also
6588  // don't want to emit a warning if the issue occurs from the expansion of
6589  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
6590  // delay this check as long as possible. Once we detect we are in that
6591  // scenario, we just return.
6592  if (CC.isInvalid())
6593    return;
6594
6595  // Diagnose implicit casts to bool.
6596  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
6597    if (isa<StringLiteral>(E))
6598      // Warn on string literal to bool.  Checks for string literals in logical
6599      // and expressions, for instance, assert(0 && "error here"), are
6600      // prevented by a check in AnalyzeImplicitConversions().
6601      return DiagnoseImpCast(S, E, T, CC,
6602                             diag::warn_impcast_string_literal_to_bool);
6603    if (isa<ObjCStringLiteral>(E) || isa<ObjCArrayLiteral>(E) ||
6604        isa<ObjCDictionaryLiteral>(E) || isa<ObjCBoxedExpr>(E)) {
6605      // This covers the literal expressions that evaluate to Objective-C
6606      // objects.
6607      return DiagnoseImpCast(S, E, T, CC,
6608                             diag::warn_impcast_objective_c_literal_to_bool);
6609    }
6610    if (Source->isPointerType() || Source->canDecayToPointerType()) {
6611      // Warn on pointer to bool conversion that is always true.
6612      S.DiagnoseAlwaysNonNullPointer(E, Expr::NPCK_NotNull, /*IsEqual*/ false,
6613                                     SourceRange(CC));
6614    }
6615  }
6616
6617  // Strip vector types.
6618  if (isa<VectorType>(Source)) {
6619    if (!isa<VectorType>(Target)) {
6620      if (S.SourceMgr.isInSystemMacro(CC))
6621        return;
6622      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
6623    }
6624
6625    // If the vector cast is cast between two vectors of the same size, it is
6626    // a bitcast, not a conversion.
6627    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
6628      return;
6629
6630    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
6631    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
6632  }
6633  if (auto VecTy = dyn_cast<VectorType>(Target))
6634    Target = VecTy->getElementType().getTypePtr();
6635
6636  // Strip complex types.
6637  if (isa<ComplexType>(Source)) {
6638    if (!isa<ComplexType>(Target)) {
6639      if (S.SourceMgr.isInSystemMacro(CC))
6640        return;
6641
6642      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
6643    }
6644
6645    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
6646    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
6647  }
6648
6649  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
6650  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
6651
6652  // If the source is floating point...
6653  if (SourceBT && SourceBT->isFloatingPoint()) {
6654    // ...and the target is floating point...
6655    if (TargetBT && TargetBT->isFloatingPoint()) {
6656      // ...then warn if we're dropping FP rank.
6657
6658      // Builtin FP kinds are ordered by increasing FP rank.
6659      if (SourceBT->getKind() > TargetBT->getKind()) {
6660        // Don't warn about float constants that are precisely
6661        // representable in the target type.
6662        Expr::EvalResult result;
6663        if (E->EvaluateAsRValue(result, S.Context)) {
6664          // Value might be a float, a float vector, or a float complex.
6665          if (IsSameFloatAfterCast(result.Val,
6666                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
6667                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
6668            return;
6669        }
6670
6671        if (S.SourceMgr.isInSystemMacro(CC))
6672          return;
6673
6674        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
6675      }
6676      return;
6677    }
6678
6679    // If the target is integral, always warn.
6680    if (TargetBT && TargetBT->isInteger()) {
6681      if (S.SourceMgr.isInSystemMacro(CC))
6682        return;
6683
6684      Expr *InnerE = E->IgnoreParenImpCasts();
6685      // We also want to warn on, e.g., "int i = -1.234"
6686      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
6687        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
6688          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
6689
6690      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
6691        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
6692      } else {
6693        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
6694      }
6695    }
6696
6697    // If the target is bool, warn if expr is a function or method call.
6698    if (Target->isSpecificBuiltinType(BuiltinType::Bool) &&
6699        isa<CallExpr>(E)) {
6700      // Check last argument of function call to see if it is an
6701      // implicit cast from a type matching the type the result
6702      // is being cast to.
6703      CallExpr *CEx = cast<CallExpr>(E);
6704      unsigned NumArgs = CEx->getNumArgs();
6705      if (NumArgs > 0) {
6706        Expr *LastA = CEx->getArg(NumArgs - 1);
6707        Expr *InnerE = LastA->IgnoreParenImpCasts();
6708        const Type *InnerType =
6709          S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
6710        if (isa<ImplicitCastExpr>(LastA) && (InnerType == Target)) {
6711          // Warn on this floating-point to bool conversion
6712          DiagnoseImpCast(S, E, T, CC,
6713                          diag::warn_impcast_floating_point_to_bool);
6714        }
6715      }
6716    }
6717    return;
6718  }
6719
6720  DiagnoseNullConversion(S, E, T, CC);
6721
6722  if (!Source->isIntegerType() || !Target->isIntegerType())
6723    return;
6724
6725  // TODO: remove this early return once the false positives for constant->bool
6726  // in templates, macros, etc, are reduced or removed.
6727  if (Target->isSpecificBuiltinType(BuiltinType::Bool))
6728    return;
6729
6730  IntRange SourceRange = GetExprRange(S.Context, E);
6731  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
6732
6733  if (SourceRange.Width > TargetRange.Width) {
6734    // If the source is a constant, use a default-on diagnostic.
6735    // TODO: this should happen for bitfield stores, too.
6736    llvm::APSInt Value(32);
6737    if (E->isIntegerConstantExpr(Value, S.Context)) {
6738      if (S.SourceMgr.isInSystemMacro(CC))
6739        return;
6740
6741      std::string PrettySourceValue = Value.toString(10);
6742      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
6743
6744      S.DiagRuntimeBehavior(E->getExprLoc(), E,
6745        S.PDiag(diag::warn_impcast_integer_precision_constant)
6746            << PrettySourceValue << PrettyTargetValue
6747            << E->getType() << T << E->getSourceRange()
6748            << clang::SourceRange(CC));
6749      return;
6750    }
6751
6752    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
6753    if (S.SourceMgr.isInSystemMacro(CC))
6754      return;
6755
6756    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
6757      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
6758                             /* pruneControlFlow */ true);
6759    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
6760  }
6761
6762  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
6763      (!TargetRange.NonNegative && SourceRange.NonNegative &&
6764       SourceRange.Width == TargetRange.Width)) {
6765
6766    if (S.SourceMgr.isInSystemMacro(CC))
6767      return;
6768
6769    unsigned DiagID = diag::warn_impcast_integer_sign;
6770
6771    // Traditionally, gcc has warned about this under -Wsign-compare.
6772    // We also want to warn about it in -Wconversion.
6773    // So if -Wconversion is off, use a completely identical diagnostic
6774    // in the sign-compare group.
6775    // The conditional-checking code will
6776    if (ICContext) {
6777      DiagID = diag::warn_impcast_integer_sign_conditional;
6778      *ICContext = true;
6779    }
6780
6781    return DiagnoseImpCast(S, E, T, CC, DiagID);
6782  }
6783
6784  // Diagnose conversions between different enumeration types.
6785  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
6786  // type, to give us better diagnostics.
6787  QualType SourceType = E->getType();
6788  if (!S.getLangOpts().CPlusPlus) {
6789    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
6790      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
6791        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
6792        SourceType = S.Context.getTypeDeclType(Enum);
6793        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
6794      }
6795  }
6796
6797  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
6798    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
6799      if (SourceEnum->getDecl()->hasNameForLinkage() &&
6800          TargetEnum->getDecl()->hasNameForLinkage() &&
6801          SourceEnum != TargetEnum) {
6802        if (S.SourceMgr.isInSystemMacro(CC))
6803          return;
6804
6805        return DiagnoseImpCast(S, E, SourceType, T, CC,
6806                               diag::warn_impcast_different_enum_types);
6807      }
6808
6809  return;
6810}
6811
6812void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
6813                              SourceLocation CC, QualType T);
6814
6815void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
6816                             SourceLocation CC, bool &ICContext) {
6817  E = E->IgnoreParenImpCasts();
6818
6819  if (isa<ConditionalOperator>(E))
6820    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
6821
6822  AnalyzeImplicitConversions(S, E, CC);
6823  if (E->getType() != T)
6824    return CheckImplicitConversion(S, E, T, CC, &ICContext);
6825  return;
6826}
6827
6828void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
6829                              SourceLocation CC, QualType T) {
6830  AnalyzeImplicitConversions(S, E->getCond(), E->getQuestionLoc());
6831
6832  bool Suspicious = false;
6833  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
6834  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
6835
6836  // If -Wconversion would have warned about either of the candidates
6837  // for a signedness conversion to the context type...
6838  if (!Suspicious) return;
6839
6840  // ...but it's currently ignored...
6841  if (!S.Diags.isIgnored(diag::warn_impcast_integer_sign_conditional, CC))
6842    return;
6843
6844  // ...then check whether it would have warned about either of the
6845  // candidates for a signedness conversion to the condition type.
6846  if (E->getType() == T) return;
6847
6848  Suspicious = false;
6849  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
6850                          E->getType(), CC, &Suspicious);
6851  if (!Suspicious)
6852    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
6853                            E->getType(), CC, &Suspicious);
6854}
6855
6856/// CheckBoolLikeConversion - Check conversion of given expression to boolean.
6857/// Input argument E is a logical expression.
6858static void CheckBoolLikeConversion(Sema &S, Expr *E, SourceLocation CC) {
6859  if (S.getLangOpts().Bool)
6860    return;
6861  CheckImplicitConversion(S, E->IgnoreParenImpCasts(), S.Context.BoolTy, CC);
6862}
6863
6864/// AnalyzeImplicitConversions - Find and report any interesting
6865/// implicit conversions in the given expression.  There are a couple
6866/// of competing diagnostics here, -Wconversion and -Wsign-compare.
6867void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
6868  QualType T = OrigE->getType();
6869  Expr *E = OrigE->IgnoreParenImpCasts();
6870
6871  if (E->isTypeDependent() || E->isValueDependent())
6872    return;
6873
6874  // For conditional operators, we analyze the arguments as if they
6875  // were being fed directly into the output.
6876  if (isa<ConditionalOperator>(E)) {
6877    ConditionalOperator *CO = cast<ConditionalOperator>(E);
6878    CheckConditionalOperator(S, CO, CC, T);
6879    return;
6880  }
6881
6882  // Check implicit argument conversions for function calls.
6883  if (CallExpr *Call = dyn_cast<CallExpr>(E))
6884    CheckImplicitArgumentConversions(S, Call, CC);
6885
6886  // Go ahead and check any implicit conversions we might have skipped.
6887  // The non-canonical typecheck is just an optimization;
6888  // CheckImplicitConversion will filter out dead implicit conversions.
6889  if (E->getType() != T)
6890    CheckImplicitConversion(S, E, T, CC);
6891
6892  // Now continue drilling into this expression.
6893
6894  if (PseudoObjectExpr * POE = dyn_cast<PseudoObjectExpr>(E)) {
6895    if (POE->getResultExpr())
6896      E = POE->getResultExpr();
6897  }
6898
6899  if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E)) {
6900    if (OVE->getSourceExpr())
6901      AnalyzeImplicitConversions(S, OVE->getSourceExpr(), CC);
6902    return;
6903  }
6904
6905  // Skip past explicit casts.
6906  if (isa<ExplicitCastExpr>(E)) {
6907    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
6908    return AnalyzeImplicitConversions(S, E, CC);
6909  }
6910
6911  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
6912    // Do a somewhat different check with comparison operators.
6913    if (BO->isComparisonOp())
6914      return AnalyzeComparison(S, BO);
6915
6916    // And with simple assignments.
6917    if (BO->getOpcode() == BO_Assign)
6918      return AnalyzeAssignment(S, BO);
6919  }
6920
6921  // These break the otherwise-useful invariant below.  Fortunately,
6922  // we don't really need to recurse into them, because any internal
6923  // expressions should have been analyzed already when they were
6924  // built into statements.
6925  if (isa<StmtExpr>(E)) return;
6926
6927  // Don't descend into unevaluated contexts.
6928  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
6929
6930  // Now just recurse over the expression's children.
6931  CC = E->getExprLoc();
6932  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
6933  bool IsLogicalAndOperator = BO && BO->getOpcode() == BO_LAnd;
6934  for (Stmt::child_range I = E->children(); I; ++I) {
6935    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
6936    if (!ChildExpr)
6937      continue;
6938
6939    if (IsLogicalAndOperator &&
6940        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
6941      // Ignore checking string literals that are in logical and operators.
6942      // This is a common pattern for asserts.
6943      continue;
6944    AnalyzeImplicitConversions(S, ChildExpr, CC);
6945  }
6946
6947  if (BO && BO->isLogicalOp()) {
6948    Expr *SubExpr = BO->getLHS()->IgnoreParenImpCasts();
6949    if (!IsLogicalAndOperator || !isa<StringLiteral>(SubExpr))
6950      ::CheckBoolLikeConversion(S, SubExpr, BO->getExprLoc());
6951
6952    SubExpr = BO->getRHS()->IgnoreParenImpCasts();
6953    if (!IsLogicalAndOperator || !isa<StringLiteral>(SubExpr))
6954      ::CheckBoolLikeConversion(S, SubExpr, BO->getExprLoc());
6955  }
6956
6957  if (const UnaryOperator *U = dyn_cast<UnaryOperator>(E))
6958    if (U->getOpcode() == UO_LNot)
6959      ::CheckBoolLikeConversion(S, U->getSubExpr(), CC);
6960}
6961
6962} // end anonymous namespace
6963
6964enum {
6965  AddressOf,
6966  FunctionPointer,
6967  ArrayPointer
6968};
6969
6970// Helper function for Sema::DiagnoseAlwaysNonNullPointer.
6971// Returns true when emitting a warning about taking the address of a reference.
6972static bool CheckForReference(Sema &SemaRef, const Expr *E,
6973                              PartialDiagnostic PD) {
6974  E = E->IgnoreParenImpCasts();
6975
6976  const FunctionDecl *FD = nullptr;
6977
6978  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
6979    if (!DRE->getDecl()->getType()->isReferenceType())
6980      return false;
6981  } else if (const MemberExpr *M = dyn_cast<MemberExpr>(E)) {
6982    if (!M->getMemberDecl()->getType()->isReferenceType())
6983      return false;
6984  } else if (const CallExpr *Call = dyn_cast<CallExpr>(E)) {
6985    if (!Call->getCallReturnType(SemaRef.Context)->isReferenceType())
6986      return false;
6987    FD = Call->getDirectCallee();
6988  } else {
6989    return false;
6990  }
6991
6992  SemaRef.Diag(E->getExprLoc(), PD);
6993
6994  // If possible, point to location of function.
6995  if (FD) {
6996    SemaRef.Diag(FD->getLocation(), diag::note_reference_is_return_value) << FD;
6997  }
6998
6999  return true;
7000}
7001
7002// Returns true if the SourceLocation is expanded from any macro body.
7003// Returns false if the SourceLocation is invalid, is from not in a macro
7004// expansion, or is from expanded from a top-level macro argument.
7005static bool IsInAnyMacroBody(const SourceManager &SM, SourceLocation Loc) {
7006  if (Loc.isInvalid())
7007    return false;
7008
7009  while (Loc.isMacroID()) {
7010    if (SM.isMacroBodyExpansion(Loc))
7011      return true;
7012    Loc = SM.getImmediateMacroCallerLoc(Loc);
7013  }
7014
7015  return false;
7016}
7017
7018/// \brief Diagnose pointers that are always non-null.
7019/// \param E the expression containing the pointer
7020/// \param NullKind NPCK_NotNull if E is a cast to bool, otherwise, E is
7021/// compared to a null pointer
7022/// \param IsEqual True when the comparison is equal to a null pointer
7023/// \param Range Extra SourceRange to highlight in the diagnostic
7024void Sema::DiagnoseAlwaysNonNullPointer(Expr *E,
7025                                        Expr::NullPointerConstantKind NullKind,
7026                                        bool IsEqual, SourceRange Range) {
7027  if (!E)
7028    return;
7029
7030  // Don't warn inside macros.
7031  if (E->getExprLoc().isMacroID()) {
7032    const SourceManager &SM = getSourceManager();
7033    if (IsInAnyMacroBody(SM, E->getExprLoc()) ||
7034        IsInAnyMacroBody(SM, Range.getBegin()))
7035      return;
7036  }
7037  E = E->IgnoreImpCasts();
7038
7039  const bool IsCompare = NullKind != Expr::NPCK_NotNull;
7040
7041  if (isa<CXXThisExpr>(E)) {
7042    unsigned DiagID = IsCompare ? diag::warn_this_null_compare
7043                                : diag::warn_this_bool_conversion;
7044    Diag(E->getExprLoc(), DiagID) << E->getSourceRange() << Range << IsEqual;
7045    return;
7046  }
7047
7048  bool IsAddressOf = false;
7049
7050  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
7051    if (UO->getOpcode() != UO_AddrOf)
7052      return;
7053    IsAddressOf = true;
7054    E = UO->getSubExpr();
7055  }
7056
7057  if (IsAddressOf) {
7058    unsigned DiagID = IsCompare
7059                          ? diag::warn_address_of_reference_null_compare
7060                          : diag::warn_address_of_reference_bool_conversion;
7061    PartialDiagnostic PD = PDiag(DiagID) << E->getSourceRange() << Range
7062                                         << IsEqual;
7063    if (CheckForReference(*this, E, PD)) {
7064      return;
7065    }
7066  }
7067
7068  // Expect to find a single Decl.  Skip anything more complicated.
7069  ValueDecl *D = nullptr;
7070  if (DeclRefExpr *R = dyn_cast<DeclRefExpr>(E)) {
7071    D = R->getDecl();
7072  } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
7073    D = M->getMemberDecl();
7074  }
7075
7076  // Weak Decls can be null.
7077  if (!D || D->isWeak())
7078    return;
7079
7080  // Check for parameter decl with nonnull attribute
7081  if (const ParmVarDecl* PV = dyn_cast<ParmVarDecl>(D)) {
7082    if (getCurFunction() && !getCurFunction()->ModifiedNonNullParams.count(PV))
7083      if (const FunctionDecl* FD = dyn_cast<FunctionDecl>(PV->getDeclContext())) {
7084        unsigned NumArgs = FD->getNumParams();
7085        llvm::SmallBitVector AttrNonNull(NumArgs);
7086        for (const auto *NonNull : FD->specific_attrs<NonNullAttr>()) {
7087          if (!NonNull->args_size()) {
7088            AttrNonNull.set(0, NumArgs);
7089            break;
7090          }
7091          for (unsigned Val : NonNull->args()) {
7092            if (Val >= NumArgs)
7093              continue;
7094            AttrNonNull.set(Val);
7095          }
7096        }
7097        if (!AttrNonNull.empty())
7098          for (unsigned i = 0; i < NumArgs; ++i)
7099            if (FD->getParamDecl(i) == PV &&
7100                (AttrNonNull[i] || PV->hasAttr<NonNullAttr>())) {
7101              std::string Str;
7102              llvm::raw_string_ostream S(Str);
7103              E->printPretty(S, nullptr, getPrintingPolicy());
7104              unsigned DiagID = IsCompare ? diag::warn_nonnull_parameter_compare
7105                                          : diag::warn_cast_nonnull_to_bool;
7106              Diag(E->getExprLoc(), DiagID) << S.str() << E->getSourceRange()
7107                << Range << IsEqual;
7108              return;
7109            }
7110      }
7111    }
7112
7113  QualType T = D->getType();
7114  const bool IsArray = T->isArrayType();
7115  const bool IsFunction = T->isFunctionType();
7116
7117  // Address of function is used to silence the function warning.
7118  if (IsAddressOf && IsFunction) {
7119    return;
7120  }
7121
7122  // Found nothing.
7123  if (!IsAddressOf && !IsFunction && !IsArray)
7124    return;
7125
7126  // Pretty print the expression for the diagnostic.
7127  std::string Str;
7128  llvm::raw_string_ostream S(Str);
7129  E->printPretty(S, nullptr, getPrintingPolicy());
7130
7131  unsigned DiagID = IsCompare ? diag::warn_null_pointer_compare
7132                              : diag::warn_impcast_pointer_to_bool;
7133  unsigned DiagType;
7134  if (IsAddressOf)
7135    DiagType = AddressOf;
7136  else if (IsFunction)
7137    DiagType = FunctionPointer;
7138  else if (IsArray)
7139    DiagType = ArrayPointer;
7140  else
7141    llvm_unreachable("Could not determine diagnostic.");
7142  Diag(E->getExprLoc(), DiagID) << DiagType << S.str() << E->getSourceRange()
7143                                << Range << IsEqual;
7144
7145  if (!IsFunction)
7146    return;
7147
7148  // Suggest '&' to silence the function warning.
7149  Diag(E->getExprLoc(), diag::note_function_warning_silence)
7150      << FixItHint::CreateInsertion(E->getLocStart(), "&");
7151
7152  // Check to see if '()' fixit should be emitted.
7153  QualType ReturnType;
7154  UnresolvedSet<4> NonTemplateOverloads;
7155  tryExprAsCall(*E, ReturnType, NonTemplateOverloads);
7156  if (ReturnType.isNull())
7157    return;
7158
7159  if (IsCompare) {
7160    // There are two cases here.  If there is null constant, the only suggest
7161    // for a pointer return type.  If the null is 0, then suggest if the return
7162    // type is a pointer or an integer type.
7163    if (!ReturnType->isPointerType()) {
7164      if (NullKind == Expr::NPCK_ZeroExpression ||
7165          NullKind == Expr::NPCK_ZeroLiteral) {
7166        if (!ReturnType->isIntegerType())
7167          return;
7168      } else {
7169        return;
7170      }
7171    }
7172  } else { // !IsCompare
7173    // For function to bool, only suggest if the function pointer has bool
7174    // return type.
7175    if (!ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
7176      return;
7177  }
7178  Diag(E->getExprLoc(), diag::note_function_to_function_call)
7179      << FixItHint::CreateInsertion(getLocForEndOfToken(E->getLocEnd()), "()");
7180}
7181
7182
7183/// Diagnoses "dangerous" implicit conversions within the given
7184/// expression (which is a full expression).  Implements -Wconversion
7185/// and -Wsign-compare.
7186///
7187/// \param CC the "context" location of the implicit conversion, i.e.
7188///   the most location of the syntactic entity requiring the implicit
7189///   conversion
7190void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
7191  // Don't diagnose in unevaluated contexts.
7192  if (isUnevaluatedContext())
7193    return;
7194
7195  // Don't diagnose for value- or type-dependent expressions.
7196  if (E->isTypeDependent() || E->isValueDependent())
7197    return;
7198
7199  // Check for array bounds violations in cases where the check isn't triggered
7200  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
7201  // ArraySubscriptExpr is on the RHS of a variable initialization.
7202  CheckArrayAccess(E);
7203
7204  // This is not the right CC for (e.g.) a variable initialization.
7205  AnalyzeImplicitConversions(*this, E, CC);
7206}
7207
7208/// CheckBoolLikeConversion - Check conversion of given expression to boolean.
7209/// Input argument E is a logical expression.
7210void Sema::CheckBoolLikeConversion(Expr *E, SourceLocation CC) {
7211  ::CheckBoolLikeConversion(*this, E, CC);
7212}
7213
7214/// Diagnose when expression is an integer constant expression and its evaluation
7215/// results in integer overflow
7216void Sema::CheckForIntOverflow (Expr *E) {
7217  if (isa<BinaryOperator>(E->IgnoreParenCasts()))
7218    E->IgnoreParenCasts()->EvaluateForOverflow(Context);
7219}
7220
7221namespace {
7222/// \brief Visitor for expressions which looks for unsequenced operations on the
7223/// same object.
7224class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
7225  typedef EvaluatedExprVisitor<SequenceChecker> Base;
7226
7227  /// \brief A tree of sequenced regions within an expression. Two regions are
7228  /// unsequenced if one is an ancestor or a descendent of the other. When we
7229  /// finish processing an expression with sequencing, such as a comma
7230  /// expression, we fold its tree nodes into its parent, since they are
7231  /// unsequenced with respect to nodes we will visit later.
7232  class SequenceTree {
7233    struct Value {
7234      explicit Value(unsigned Parent) : Parent(Parent), Merged(false) {}
7235      unsigned Parent : 31;
7236      bool Merged : 1;
7237    };
7238    SmallVector<Value, 8> Values;
7239
7240  public:
7241    /// \brief A region within an expression which may be sequenced with respect
7242    /// to some other region.
7243    class Seq {
7244      explicit Seq(unsigned N) : Index(N) {}
7245      unsigned Index;
7246      friend class SequenceTree;
7247    public:
7248      Seq() : Index(0) {}
7249    };
7250
7251    SequenceTree() { Values.push_back(Value(0)); }
7252    Seq root() const { return Seq(0); }
7253
7254    /// \brief Create a new sequence of operations, which is an unsequenced
7255    /// subset of \p Parent. This sequence of operations is sequenced with
7256    /// respect to other children of \p Parent.
7257    Seq allocate(Seq Parent) {
7258      Values.push_back(Value(Parent.Index));
7259      return Seq(Values.size() - 1);
7260    }
7261
7262    /// \brief Merge a sequence of operations into its parent.
7263    void merge(Seq S) {
7264      Values[S.Index].Merged = true;
7265    }
7266
7267    /// \brief Determine whether two operations are unsequenced. This operation
7268    /// is asymmetric: \p Cur should be the more recent sequence, and \p Old
7269    /// should have been merged into its parent as appropriate.
7270    bool isUnsequenced(Seq Cur, Seq Old) {
7271      unsigned C = representative(Cur.Index);
7272      unsigned Target = representative(Old.Index);
7273      while (C >= Target) {
7274        if (C == Target)
7275          return true;
7276        C = Values[C].Parent;
7277      }
7278      return false;
7279    }
7280
7281  private:
7282    /// \brief Pick a representative for a sequence.
7283    unsigned representative(unsigned K) {
7284      if (Values[K].Merged)
7285        // Perform path compression as we go.
7286        return Values[K].Parent = representative(Values[K].Parent);
7287      return K;
7288    }
7289  };
7290
7291  /// An object for which we can track unsequenced uses.
7292  typedef NamedDecl *Object;
7293
7294  /// Different flavors of object usage which we track. We only track the
7295  /// least-sequenced usage of each kind.
7296  enum UsageKind {
7297    /// A read of an object. Multiple unsequenced reads are OK.
7298    UK_Use,
7299    /// A modification of an object which is sequenced before the value
7300    /// computation of the expression, such as ++n in C++.
7301    UK_ModAsValue,
7302    /// A modification of an object which is not sequenced before the value
7303    /// computation of the expression, such as n++.
7304    UK_ModAsSideEffect,
7305
7306    UK_Count = UK_ModAsSideEffect + 1
7307  };
7308
7309  struct Usage {
7310    Usage() : Use(nullptr), Seq() {}
7311    Expr *Use;
7312    SequenceTree::Seq Seq;
7313  };
7314
7315  struct UsageInfo {
7316    UsageInfo() : Diagnosed(false) {}
7317    Usage Uses[UK_Count];
7318    /// Have we issued a diagnostic for this variable already?
7319    bool Diagnosed;
7320  };
7321  typedef llvm::SmallDenseMap<Object, UsageInfo, 16> UsageInfoMap;
7322
7323  Sema &SemaRef;
7324  /// Sequenced regions within the expression.
7325  SequenceTree Tree;
7326  /// Declaration modifications and references which we have seen.
7327  UsageInfoMap UsageMap;
7328  /// The region we are currently within.
7329  SequenceTree::Seq Region;
7330  /// Filled in with declarations which were modified as a side-effect
7331  /// (that is, post-increment operations).
7332  SmallVectorImpl<std::pair<Object, Usage> > *ModAsSideEffect;
7333  /// Expressions to check later. We defer checking these to reduce
7334  /// stack usage.
7335  SmallVectorImpl<Expr *> &WorkList;
7336
7337  /// RAII object wrapping the visitation of a sequenced subexpression of an
7338  /// expression. At the end of this process, the side-effects of the evaluation
7339  /// become sequenced with respect to the value computation of the result, so
7340  /// we downgrade any UK_ModAsSideEffect within the evaluation to
7341  /// UK_ModAsValue.
7342  struct SequencedSubexpression {
7343    SequencedSubexpression(SequenceChecker &Self)
7344      : Self(Self), OldModAsSideEffect(Self.ModAsSideEffect) {
7345      Self.ModAsSideEffect = &ModAsSideEffect;
7346    }
7347    ~SequencedSubexpression() {
7348      for (auto MI = ModAsSideEffect.rbegin(), ME = ModAsSideEffect.rend();
7349           MI != ME; ++MI) {
7350        UsageInfo &U = Self.UsageMap[MI->first];
7351        auto &SideEffectUsage = U.Uses[UK_ModAsSideEffect];
7352        Self.addUsage(U, MI->first, SideEffectUsage.Use, UK_ModAsValue);
7353        SideEffectUsage = MI->second;
7354      }
7355      Self.ModAsSideEffect = OldModAsSideEffect;
7356    }
7357
7358    SequenceChecker &Self;
7359    SmallVector<std::pair<Object, Usage>, 4> ModAsSideEffect;
7360    SmallVectorImpl<std::pair<Object, Usage> > *OldModAsSideEffect;
7361  };
7362
7363  /// RAII object wrapping the visitation of a subexpression which we might
7364  /// choose to evaluate as a constant. If any subexpression is evaluated and
7365  /// found to be non-constant, this allows us to suppress the evaluation of
7366  /// the outer expression.
7367  class EvaluationTracker {
7368  public:
7369    EvaluationTracker(SequenceChecker &Self)
7370        : Self(Self), Prev(Self.EvalTracker), EvalOK(true) {
7371      Self.EvalTracker = this;
7372    }
7373    ~EvaluationTracker() {
7374      Self.EvalTracker = Prev;
7375      if (Prev)
7376        Prev->EvalOK &= EvalOK;
7377    }
7378
7379    bool evaluate(const Expr *E, bool &Result) {
7380      if (!EvalOK || E->isValueDependent())
7381        return false;
7382      EvalOK = E->EvaluateAsBooleanCondition(Result, Self.SemaRef.Context);
7383      return EvalOK;
7384    }
7385
7386  private:
7387    SequenceChecker &Self;
7388    EvaluationTracker *Prev;
7389    bool EvalOK;
7390  } *EvalTracker;
7391
7392  /// \brief Find the object which is produced by the specified expression,
7393  /// if any.
7394  Object getObject(Expr *E, bool Mod) const {
7395    E = E->IgnoreParenCasts();
7396    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
7397      if (Mod && (UO->getOpcode() == UO_PreInc || UO->getOpcode() == UO_PreDec))
7398        return getObject(UO->getSubExpr(), Mod);
7399    } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
7400      if (BO->getOpcode() == BO_Comma)
7401        return getObject(BO->getRHS(), Mod);
7402      if (Mod && BO->isAssignmentOp())
7403        return getObject(BO->getLHS(), Mod);
7404    } else if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
7405      // FIXME: Check for more interesting cases, like "x.n = ++x.n".
7406      if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenCasts()))
7407        return ME->getMemberDecl();
7408    } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
7409      // FIXME: If this is a reference, map through to its value.
7410      return DRE->getDecl();
7411    return nullptr;
7412  }
7413
7414  /// \brief Note that an object was modified or used by an expression.
7415  void addUsage(UsageInfo &UI, Object O, Expr *Ref, UsageKind UK) {
7416    Usage &U = UI.Uses[UK];
7417    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq)) {
7418      if (UK == UK_ModAsSideEffect && ModAsSideEffect)
7419        ModAsSideEffect->push_back(std::make_pair(O, U));
7420      U.Use = Ref;
7421      U.Seq = Region;
7422    }
7423  }
7424  /// \brief Check whether a modification or use conflicts with a prior usage.
7425  void checkUsage(Object O, UsageInfo &UI, Expr *Ref, UsageKind OtherKind,
7426                  bool IsModMod) {
7427    if (UI.Diagnosed)
7428      return;
7429
7430    const Usage &U = UI.Uses[OtherKind];
7431    if (!U.Use || !Tree.isUnsequenced(Region, U.Seq))
7432      return;
7433
7434    Expr *Mod = U.Use;
7435    Expr *ModOrUse = Ref;
7436    if (OtherKind == UK_Use)
7437      std::swap(Mod, ModOrUse);
7438
7439    SemaRef.Diag(Mod->getExprLoc(),
7440                 IsModMod ? diag::warn_unsequenced_mod_mod
7441                          : diag::warn_unsequenced_mod_use)
7442      << O << SourceRange(ModOrUse->getExprLoc());
7443    UI.Diagnosed = true;
7444  }
7445
7446  void notePreUse(Object O, Expr *Use) {
7447    UsageInfo &U = UsageMap[O];
7448    // Uses conflict with other modifications.
7449    checkUsage(O, U, Use, UK_ModAsValue, false);
7450  }
7451  void notePostUse(Object O, Expr *Use) {
7452    UsageInfo &U = UsageMap[O];
7453    checkUsage(O, U, Use, UK_ModAsSideEffect, false);
7454    addUsage(U, O, Use, UK_Use);
7455  }
7456
7457  void notePreMod(Object O, Expr *Mod) {
7458    UsageInfo &U = UsageMap[O];
7459    // Modifications conflict with other modifications and with uses.
7460    checkUsage(O, U, Mod, UK_ModAsValue, true);
7461    checkUsage(O, U, Mod, UK_Use, false);
7462  }
7463  void notePostMod(Object O, Expr *Use, UsageKind UK) {
7464    UsageInfo &U = UsageMap[O];
7465    checkUsage(O, U, Use, UK_ModAsSideEffect, true);
7466    addUsage(U, O, Use, UK);
7467  }
7468
7469public:
7470  SequenceChecker(Sema &S, Expr *E, SmallVectorImpl<Expr *> &WorkList)
7471      : Base(S.Context), SemaRef(S), Region(Tree.root()),
7472        ModAsSideEffect(nullptr), WorkList(WorkList), EvalTracker(nullptr) {
7473    Visit(E);
7474  }
7475
7476  void VisitStmt(Stmt *S) {
7477    // Skip all statements which aren't expressions for now.
7478  }
7479
7480  void VisitExpr(Expr *E) {
7481    // By default, just recurse to evaluated subexpressions.
7482    Base::VisitStmt(E);
7483  }
7484
7485  void VisitCastExpr(CastExpr *E) {
7486    Object O = Object();
7487    if (E->getCastKind() == CK_LValueToRValue)
7488      O = getObject(E->getSubExpr(), false);
7489
7490    if (O)
7491      notePreUse(O, E);
7492    VisitExpr(E);
7493    if (O)
7494      notePostUse(O, E);
7495  }
7496
7497  void VisitBinComma(BinaryOperator *BO) {
7498    // C++11 [expr.comma]p1:
7499    //   Every value computation and side effect associated with the left
7500    //   expression is sequenced before every value computation and side
7501    //   effect associated with the right expression.
7502    SequenceTree::Seq LHS = Tree.allocate(Region);
7503    SequenceTree::Seq RHS = Tree.allocate(Region);
7504    SequenceTree::Seq OldRegion = Region;
7505
7506    {
7507      SequencedSubexpression SeqLHS(*this);
7508      Region = LHS;
7509      Visit(BO->getLHS());
7510    }
7511
7512    Region = RHS;
7513    Visit(BO->getRHS());
7514
7515    Region = OldRegion;
7516
7517    // Forget that LHS and RHS are sequenced. They are both unsequenced
7518    // with respect to other stuff.
7519    Tree.merge(LHS);
7520    Tree.merge(RHS);
7521  }
7522
7523  void VisitBinAssign(BinaryOperator *BO) {
7524    // The modification is sequenced after the value computation of the LHS
7525    // and RHS, so check it before inspecting the operands and update the
7526    // map afterwards.
7527    Object O = getObject(BO->getLHS(), true);
7528    if (!O)
7529      return VisitExpr(BO);
7530
7531    notePreMod(O, BO);
7532
7533    // C++11 [expr.ass]p7:
7534    //   E1 op= E2 is equivalent to E1 = E1 op E2, except that E1 is evaluated
7535    //   only once.
7536    //
7537    // Therefore, for a compound assignment operator, O is considered used
7538    // everywhere except within the evaluation of E1 itself.
7539    if (isa<CompoundAssignOperator>(BO))
7540      notePreUse(O, BO);
7541
7542    Visit(BO->getLHS());
7543
7544    if (isa<CompoundAssignOperator>(BO))
7545      notePostUse(O, BO);
7546
7547    Visit(BO->getRHS());
7548
7549    // C++11 [expr.ass]p1:
7550    //   the assignment is sequenced [...] before the value computation of the
7551    //   assignment expression.
7552    // C11 6.5.16/3 has no such rule.
7553    notePostMod(O, BO, SemaRef.getLangOpts().CPlusPlus ? UK_ModAsValue
7554                                                       : UK_ModAsSideEffect);
7555  }
7556  void VisitCompoundAssignOperator(CompoundAssignOperator *CAO) {
7557    VisitBinAssign(CAO);
7558  }
7559
7560  void VisitUnaryPreInc(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
7561  void VisitUnaryPreDec(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
7562  void VisitUnaryPreIncDec(UnaryOperator *UO) {
7563    Object O = getObject(UO->getSubExpr(), true);
7564    if (!O)
7565      return VisitExpr(UO);
7566
7567    notePreMod(O, UO);
7568    Visit(UO->getSubExpr());
7569    // C++11 [expr.pre.incr]p1:
7570    //   the expression ++x is equivalent to x+=1
7571    notePostMod(O, UO, SemaRef.getLangOpts().CPlusPlus ? UK_ModAsValue
7572                                                       : UK_ModAsSideEffect);
7573  }
7574
7575  void VisitUnaryPostInc(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
7576  void VisitUnaryPostDec(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
7577  void VisitUnaryPostIncDec(UnaryOperator *UO) {
7578    Object O = getObject(UO->getSubExpr(), true);
7579    if (!O)
7580      return VisitExpr(UO);
7581
7582    notePreMod(O, UO);
7583    Visit(UO->getSubExpr());
7584    notePostMod(O, UO, UK_ModAsSideEffect);
7585  }
7586
7587  /// Don't visit the RHS of '&&' or '||' if it might not be evaluated.
7588  void VisitBinLOr(BinaryOperator *BO) {
7589    // The side-effects of the LHS of an '&&' are sequenced before the
7590    // value computation of the RHS, and hence before the value computation
7591    // of the '&&' itself, unless the LHS evaluates to zero. We treat them
7592    // as if they were unconditionally sequenced.
7593    EvaluationTracker Eval(*this);
7594    {
7595      SequencedSubexpression Sequenced(*this);
7596      Visit(BO->getLHS());
7597    }
7598
7599    bool Result;
7600    if (Eval.evaluate(BO->getLHS(), Result)) {
7601      if (!Result)
7602        Visit(BO->getRHS());
7603    } else {
7604      // Check for unsequenced operations in the RHS, treating it as an
7605      // entirely separate evaluation.
7606      //
7607      // FIXME: If there are operations in the RHS which are unsequenced
7608      // with respect to operations outside the RHS, and those operations
7609      // are unconditionally evaluated, diagnose them.
7610      WorkList.push_back(BO->getRHS());
7611    }
7612  }
7613  void VisitBinLAnd(BinaryOperator *BO) {
7614    EvaluationTracker Eval(*this);
7615    {
7616      SequencedSubexpression Sequenced(*this);
7617      Visit(BO->getLHS());
7618    }
7619
7620    bool Result;
7621    if (Eval.evaluate(BO->getLHS(), Result)) {
7622      if (Result)
7623        Visit(BO->getRHS());
7624    } else {
7625      WorkList.push_back(BO->getRHS());
7626    }
7627  }
7628
7629  // Only visit the condition, unless we can be sure which subexpression will
7630  // be chosen.
7631  void VisitAbstractConditionalOperator(AbstractConditionalOperator *CO) {
7632    EvaluationTracker Eval(*this);
7633    {
7634      SequencedSubexpression Sequenced(*this);
7635      Visit(CO->getCond());
7636    }
7637
7638    bool Result;
7639    if (Eval.evaluate(CO->getCond(), Result))
7640      Visit(Result ? CO->getTrueExpr() : CO->getFalseExpr());
7641    else {
7642      WorkList.push_back(CO->getTrueExpr());
7643      WorkList.push_back(CO->getFalseExpr());
7644    }
7645  }
7646
7647  void VisitCallExpr(CallExpr *CE) {
7648    // C++11 [intro.execution]p15:
7649    //   When calling a function [...], every value computation and side effect
7650    //   associated with any argument expression, or with the postfix expression
7651    //   designating the called function, is sequenced before execution of every
7652    //   expression or statement in the body of the function [and thus before
7653    //   the value computation of its result].
7654    SequencedSubexpression Sequenced(*this);
7655    Base::VisitCallExpr(CE);
7656
7657    // FIXME: CXXNewExpr and CXXDeleteExpr implicitly call functions.
7658  }
7659
7660  void VisitCXXConstructExpr(CXXConstructExpr *CCE) {
7661    // This is a call, so all subexpressions are sequenced before the result.
7662    SequencedSubexpression Sequenced(*this);
7663
7664    if (!CCE->isListInitialization())
7665      return VisitExpr(CCE);
7666
7667    // In C++11, list initializations are sequenced.
7668    SmallVector<SequenceTree::Seq, 32> Elts;
7669    SequenceTree::Seq Parent = Region;
7670    for (CXXConstructExpr::arg_iterator I = CCE->arg_begin(),
7671                                        E = CCE->arg_end();
7672         I != E; ++I) {
7673      Region = Tree.allocate(Parent);
7674      Elts.push_back(Region);
7675      Visit(*I);
7676    }
7677
7678    // Forget that the initializers are sequenced.
7679    Region = Parent;
7680    for (unsigned I = 0; I < Elts.size(); ++I)
7681      Tree.merge(Elts[I]);
7682  }
7683
7684  void VisitInitListExpr(InitListExpr *ILE) {
7685    if (!SemaRef.getLangOpts().CPlusPlus11)
7686      return VisitExpr(ILE);
7687
7688    // In C++11, list initializations are sequenced.
7689    SmallVector<SequenceTree::Seq, 32> Elts;
7690    SequenceTree::Seq Parent = Region;
7691    for (unsigned I = 0; I < ILE->getNumInits(); ++I) {
7692      Expr *E = ILE->getInit(I);
7693      if (!E) continue;
7694      Region = Tree.allocate(Parent);
7695      Elts.push_back(Region);
7696      Visit(E);
7697    }
7698
7699    // Forget that the initializers are sequenced.
7700    Region = Parent;
7701    for (unsigned I = 0; I < Elts.size(); ++I)
7702      Tree.merge(Elts[I]);
7703  }
7704};
7705}
7706
7707void Sema::CheckUnsequencedOperations(Expr *E) {
7708  SmallVector<Expr *, 8> WorkList;
7709  WorkList.push_back(E);
7710  while (!WorkList.empty()) {
7711    Expr *Item = WorkList.pop_back_val();
7712    SequenceChecker(*this, Item, WorkList);
7713  }
7714}
7715
7716void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
7717                              bool IsConstexpr) {
7718  CheckImplicitConversions(E, CheckLoc);
7719  CheckUnsequencedOperations(E);
7720  if (!IsConstexpr && !E->isValueDependent())
7721    CheckForIntOverflow(E);
7722}
7723
7724void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
7725                                       FieldDecl *BitField,
7726                                       Expr *Init) {
7727  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
7728}
7729
7730static void diagnoseArrayStarInParamType(Sema &S, QualType PType,
7731                                         SourceLocation Loc) {
7732  if (!PType->isVariablyModifiedType())
7733    return;
7734  if (const auto *PointerTy = dyn_cast<PointerType>(PType)) {
7735    diagnoseArrayStarInParamType(S, PointerTy->getPointeeType(), Loc);
7736    return;
7737  }
7738  if (const auto *ReferenceTy = dyn_cast<ReferenceType>(PType)) {
7739    diagnoseArrayStarInParamType(S, ReferenceTy->getPointeeType(), Loc);
7740    return;
7741  }
7742  if (const auto *ParenTy = dyn_cast<ParenType>(PType)) {
7743    diagnoseArrayStarInParamType(S, ParenTy->getInnerType(), Loc);
7744    return;
7745  }
7746
7747  const ArrayType *AT = S.Context.getAsArrayType(PType);
7748  if (!AT)
7749    return;
7750
7751  if (AT->getSizeModifier() != ArrayType::Star) {
7752    diagnoseArrayStarInParamType(S, AT->getElementType(), Loc);
7753    return;
7754  }
7755
7756  S.Diag(Loc, diag::err_array_star_in_function_definition);
7757}
7758
7759/// CheckParmsForFunctionDef - Check that the parameters of the given
7760/// function are appropriate for the definition of a function. This
7761/// takes care of any checks that cannot be performed on the
7762/// declaration itself, e.g., that the types of each of the function
7763/// parameters are complete.
7764bool Sema::CheckParmsForFunctionDef(ParmVarDecl *const *P,
7765                                    ParmVarDecl *const *PEnd,
7766                                    bool CheckParameterNames) {
7767  bool HasInvalidParm = false;
7768  for (; P != PEnd; ++P) {
7769    ParmVarDecl *Param = *P;
7770
7771    // C99 6.7.5.3p4: the parameters in a parameter type list in a
7772    // function declarator that is part of a function definition of
7773    // that function shall not have incomplete type.
7774    //
7775    // This is also C++ [dcl.fct]p6.
7776    if (!Param->isInvalidDecl() &&
7777        RequireCompleteType(Param->getLocation(), Param->getType(),
7778                            diag::err_typecheck_decl_incomplete_type)) {
7779      Param->setInvalidDecl();
7780      HasInvalidParm = true;
7781    }
7782
7783    // C99 6.9.1p5: If the declarator includes a parameter type list, the
7784    // declaration of each parameter shall include an identifier.
7785    if (CheckParameterNames &&
7786        Param->getIdentifier() == nullptr &&
7787        !Param->isImplicit() &&
7788        !getLangOpts().CPlusPlus)
7789      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
7790
7791    // C99 6.7.5.3p12:
7792    //   If the function declarator is not part of a definition of that
7793    //   function, parameters may have incomplete type and may use the [*]
7794    //   notation in their sequences of declarator specifiers to specify
7795    //   variable length array types.
7796    QualType PType = Param->getOriginalType();
7797    // FIXME: This diagnostic should point the '[*]' if source-location
7798    // information is added for it.
7799    diagnoseArrayStarInParamType(*this, PType, Param->getLocation());
7800
7801    // MSVC destroys objects passed by value in the callee.  Therefore a
7802    // function definition which takes such a parameter must be able to call the
7803    // object's destructor.  However, we don't perform any direct access check
7804    // on the dtor.
7805    if (getLangOpts().CPlusPlus && Context.getTargetInfo()
7806                                       .getCXXABI()
7807                                       .areArgsDestroyedLeftToRightInCallee()) {
7808      if (!Param->isInvalidDecl()) {
7809        if (const RecordType *RT = Param->getType()->getAs<RecordType>()) {
7810          CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
7811          if (!ClassDecl->isInvalidDecl() &&
7812              !ClassDecl->hasIrrelevantDestructor() &&
7813              !ClassDecl->isDependentContext()) {
7814            CXXDestructorDecl *Destructor = LookupDestructor(ClassDecl);
7815            MarkFunctionReferenced(Param->getLocation(), Destructor);
7816            DiagnoseUseOfDecl(Destructor, Param->getLocation());
7817          }
7818        }
7819      }
7820    }
7821  }
7822
7823  return HasInvalidParm;
7824}
7825
7826/// CheckCastAlign - Implements -Wcast-align, which warns when a
7827/// pointer cast increases the alignment requirements.
7828void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
7829  // This is actually a lot of work to potentially be doing on every
7830  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
7831  if (getDiagnostics().isIgnored(diag::warn_cast_align, TRange.getBegin()))
7832    return;
7833
7834  // Ignore dependent types.
7835  if (T->isDependentType() || Op->getType()->isDependentType())
7836    return;
7837
7838  // Require that the destination be a pointer type.
7839  const PointerType *DestPtr = T->getAs<PointerType>();
7840  if (!DestPtr) return;
7841
7842  // If the destination has alignment 1, we're done.
7843  QualType DestPointee = DestPtr->getPointeeType();
7844  if (DestPointee->isIncompleteType()) return;
7845  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
7846  if (DestAlign.isOne()) return;
7847
7848  // Require that the source be a pointer type.
7849  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
7850  if (!SrcPtr) return;
7851  QualType SrcPointee = SrcPtr->getPointeeType();
7852
7853  // Whitelist casts from cv void*.  We already implicitly
7854  // whitelisted casts to cv void*, since they have alignment 1.
7855  // Also whitelist casts involving incomplete types, which implicitly
7856  // includes 'void'.
7857  if (SrcPointee->isIncompleteType()) return;
7858
7859  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
7860  if (SrcAlign >= DestAlign) return;
7861
7862  Diag(TRange.getBegin(), diag::warn_cast_align)
7863    << Op->getType() << T
7864    << static_cast<unsigned>(SrcAlign.getQuantity())
7865    << static_cast<unsigned>(DestAlign.getQuantity())
7866    << TRange << Op->getSourceRange();
7867}
7868
7869static const Type* getElementType(const Expr *BaseExpr) {
7870  const Type* EltType = BaseExpr->getType().getTypePtr();
7871  if (EltType->isAnyPointerType())
7872    return EltType->getPointeeType().getTypePtr();
7873  else if (EltType->isArrayType())
7874    return EltType->getBaseElementTypeUnsafe();
7875  return EltType;
7876}
7877
7878/// \brief Check whether this array fits the idiom of a size-one tail padded
7879/// array member of a struct.
7880///
7881/// We avoid emitting out-of-bounds access warnings for such arrays as they are
7882/// commonly used to emulate flexible arrays in C89 code.
7883static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
7884                                    const NamedDecl *ND) {
7885  if (Size != 1 || !ND) return false;
7886
7887  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
7888  if (!FD) return false;
7889
7890  // Don't consider sizes resulting from macro expansions or template argument
7891  // substitution to form C89 tail-padded arrays.
7892
7893  TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
7894  while (TInfo) {
7895    TypeLoc TL = TInfo->getTypeLoc();
7896    // Look through typedefs.
7897    if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
7898      const TypedefNameDecl *TDL = TTL.getTypedefNameDecl();
7899      TInfo = TDL->getTypeSourceInfo();
7900      continue;
7901    }
7902    if (ConstantArrayTypeLoc CTL = TL.getAs<ConstantArrayTypeLoc>()) {
7903      const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
7904      if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
7905        return false;
7906    }
7907    break;
7908  }
7909
7910  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
7911  if (!RD) return false;
7912  if (RD->isUnion()) return false;
7913  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
7914    if (!CRD->isStandardLayout()) return false;
7915  }
7916
7917  // See if this is the last field decl in the record.
7918  const Decl *D = FD;
7919  while ((D = D->getNextDeclInContext()))
7920    if (isa<FieldDecl>(D))
7921      return false;
7922  return true;
7923}
7924
7925void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
7926                            const ArraySubscriptExpr *ASE,
7927                            bool AllowOnePastEnd, bool IndexNegated) {
7928  IndexExpr = IndexExpr->IgnoreParenImpCasts();
7929  if (IndexExpr->isValueDependent())
7930    return;
7931
7932  const Type *EffectiveType = getElementType(BaseExpr);
7933  BaseExpr = BaseExpr->IgnoreParenCasts();
7934  const ConstantArrayType *ArrayTy =
7935    Context.getAsConstantArrayType(BaseExpr->getType());
7936  if (!ArrayTy)
7937    return;
7938
7939  llvm::APSInt index;
7940  if (!IndexExpr->EvaluateAsInt(index, Context))
7941    return;
7942  if (IndexNegated)
7943    index = -index;
7944
7945  const NamedDecl *ND = nullptr;
7946  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
7947    ND = dyn_cast<NamedDecl>(DRE->getDecl());
7948  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
7949    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
7950
7951  if (index.isUnsigned() || !index.isNegative()) {
7952    llvm::APInt size = ArrayTy->getSize();
7953    if (!size.isStrictlyPositive())
7954      return;
7955
7956    const Type* BaseType = getElementType(BaseExpr);
7957    if (BaseType != EffectiveType) {
7958      // Make sure we're comparing apples to apples when comparing index to size
7959      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
7960      uint64_t array_typesize = Context.getTypeSize(BaseType);
7961      // Handle ptrarith_typesize being zero, such as when casting to void*
7962      if (!ptrarith_typesize) ptrarith_typesize = 1;
7963      if (ptrarith_typesize != array_typesize) {
7964        // There's a cast to a different size type involved
7965        uint64_t ratio = array_typesize / ptrarith_typesize;
7966        // TODO: Be smarter about handling cases where array_typesize is not a
7967        // multiple of ptrarith_typesize
7968        if (ptrarith_typesize * ratio == array_typesize)
7969          size *= llvm::APInt(size.getBitWidth(), ratio);
7970      }
7971    }
7972
7973    if (size.getBitWidth() > index.getBitWidth())
7974      index = index.zext(size.getBitWidth());
7975    else if (size.getBitWidth() < index.getBitWidth())
7976      size = size.zext(index.getBitWidth());
7977
7978    // For array subscripting the index must be less than size, but for pointer
7979    // arithmetic also allow the index (offset) to be equal to size since
7980    // computing the next address after the end of the array is legal and
7981    // commonly done e.g. in C++ iterators and range-based for loops.
7982    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
7983      return;
7984
7985    // Also don't warn for arrays of size 1 which are members of some
7986    // structure. These are often used to approximate flexible arrays in C89
7987    // code.
7988    if (IsTailPaddedMemberArray(*this, size, ND))
7989      return;
7990
7991    // Suppress the warning if the subscript expression (as identified by the
7992    // ']' location) and the index expression are both from macro expansions
7993    // within a system header.
7994    if (ASE) {
7995      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
7996          ASE->getRBracketLoc());
7997      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
7998        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
7999            IndexExpr->getLocStart());
8000        if (SourceMgr.isWrittenInSameFile(RBracketLoc, IndexLoc))
8001          return;
8002      }
8003    }
8004
8005    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
8006    if (ASE)
8007      DiagID = diag::warn_array_index_exceeds_bounds;
8008
8009    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
8010                        PDiag(DiagID) << index.toString(10, true)
8011                          << size.toString(10, true)
8012                          << (unsigned)size.getLimitedValue(~0U)
8013                          << IndexExpr->getSourceRange());
8014  } else {
8015    unsigned DiagID = diag::warn_array_index_precedes_bounds;
8016    if (!ASE) {
8017      DiagID = diag::warn_ptr_arith_precedes_bounds;
8018      if (index.isNegative()) index = -index;
8019    }
8020
8021    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
8022                        PDiag(DiagID) << index.toString(10, true)
8023                          << IndexExpr->getSourceRange());
8024  }
8025
8026  if (!ND) {
8027    // Try harder to find a NamedDecl to point at in the note.
8028    while (const ArraySubscriptExpr *ASE =
8029           dyn_cast<ArraySubscriptExpr>(BaseExpr))
8030      BaseExpr = ASE->getBase()->IgnoreParenCasts();
8031    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
8032      ND = dyn_cast<NamedDecl>(DRE->getDecl());
8033    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
8034      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
8035  }
8036
8037  if (ND)
8038    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
8039                        PDiag(diag::note_array_index_out_of_bounds)
8040                          << ND->getDeclName());
8041}
8042
8043void Sema::CheckArrayAccess(const Expr *expr) {
8044  int AllowOnePastEnd = 0;
8045  while (expr) {
8046    expr = expr->IgnoreParenImpCasts();
8047    switch (expr->getStmtClass()) {
8048      case Stmt::ArraySubscriptExprClass: {
8049        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
8050        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
8051                         AllowOnePastEnd > 0);
8052        return;
8053      }
8054      case Stmt::UnaryOperatorClass: {
8055        // Only unwrap the * and & unary operators
8056        const UnaryOperator *UO = cast<UnaryOperator>(expr);
8057        expr = UO->getSubExpr();
8058        switch (UO->getOpcode()) {
8059          case UO_AddrOf:
8060            AllowOnePastEnd++;
8061            break;
8062          case UO_Deref:
8063            AllowOnePastEnd--;
8064            break;
8065          default:
8066            return;
8067        }
8068        break;
8069      }
8070      case Stmt::ConditionalOperatorClass: {
8071        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
8072        if (const Expr *lhs = cond->getLHS())
8073          CheckArrayAccess(lhs);
8074        if (const Expr *rhs = cond->getRHS())
8075          CheckArrayAccess(rhs);
8076        return;
8077      }
8078      default:
8079        return;
8080    }
8081  }
8082}
8083
8084//===--- CHECK: Objective-C retain cycles ----------------------------------//
8085
8086namespace {
8087  struct RetainCycleOwner {
8088    RetainCycleOwner() : Variable(nullptr), Indirect(false) {}
8089    VarDecl *Variable;
8090    SourceRange Range;
8091    SourceLocation Loc;
8092    bool Indirect;
8093
8094    void setLocsFrom(Expr *e) {
8095      Loc = e->getExprLoc();
8096      Range = e->getSourceRange();
8097    }
8098  };
8099}
8100
8101/// Consider whether capturing the given variable can possibly lead to
8102/// a retain cycle.
8103static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
8104  // In ARC, it's captured strongly iff the variable has __strong
8105  // lifetime.  In MRR, it's captured strongly if the variable is
8106  // __block and has an appropriate type.
8107  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
8108    return false;
8109
8110  owner.Variable = var;
8111  if (ref)
8112    owner.setLocsFrom(ref);
8113  return true;
8114}
8115
8116static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
8117  while (true) {
8118    e = e->IgnoreParens();
8119    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
8120      switch (cast->getCastKind()) {
8121      case CK_BitCast:
8122      case CK_LValueBitCast:
8123      case CK_LValueToRValue:
8124      case CK_ARCReclaimReturnedObject:
8125        e = cast->getSubExpr();
8126        continue;
8127
8128      default:
8129        return false;
8130      }
8131    }
8132
8133    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
8134      ObjCIvarDecl *ivar = ref->getDecl();
8135      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
8136        return false;
8137
8138      // Try to find a retain cycle in the base.
8139      if (!findRetainCycleOwner(S, ref->getBase(), owner))
8140        return false;
8141
8142      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
8143      owner.Indirect = true;
8144      return true;
8145    }
8146
8147    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
8148      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
8149      if (!var) return false;
8150      return considerVariable(var, ref, owner);
8151    }
8152
8153    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
8154      if (member->isArrow()) return false;
8155
8156      // Don't count this as an indirect ownership.
8157      e = member->getBase();
8158      continue;
8159    }
8160
8161    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
8162      // Only pay attention to pseudo-objects on property references.
8163      ObjCPropertyRefExpr *pre
8164        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
8165                                              ->IgnoreParens());
8166      if (!pre) return false;
8167      if (pre->isImplicitProperty()) return false;
8168      ObjCPropertyDecl *property = pre->getExplicitProperty();
8169      if (!property->isRetaining() &&
8170          !(property->getPropertyIvarDecl() &&
8171            property->getPropertyIvarDecl()->getType()
8172              .getObjCLifetime() == Qualifiers::OCL_Strong))
8173          return false;
8174
8175      owner.Indirect = true;
8176      if (pre->isSuperReceiver()) {
8177        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
8178        if (!owner.Variable)
8179          return false;
8180        owner.Loc = pre->getLocation();
8181        owner.Range = pre->getSourceRange();
8182        return true;
8183      }
8184      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
8185                              ->getSourceExpr());
8186      continue;
8187    }
8188
8189    // Array ivars?
8190
8191    return false;
8192  }
8193}
8194
8195namespace {
8196  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
8197    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
8198      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
8199        Context(Context), Variable(variable), Capturer(nullptr),
8200        VarWillBeReased(false) {}
8201    ASTContext &Context;
8202    VarDecl *Variable;
8203    Expr *Capturer;
8204    bool VarWillBeReased;
8205
8206    void VisitDeclRefExpr(DeclRefExpr *ref) {
8207      if (ref->getDecl() == Variable && !Capturer)
8208        Capturer = ref;
8209    }
8210
8211    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
8212      if (Capturer) return;
8213      Visit(ref->getBase());
8214      if (Capturer && ref->isFreeIvar())
8215        Capturer = ref;
8216    }
8217
8218    void VisitBlockExpr(BlockExpr *block) {
8219      // Look inside nested blocks
8220      if (block->getBlockDecl()->capturesVariable(Variable))
8221        Visit(block->getBlockDecl()->getBody());
8222    }
8223
8224    void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
8225      if (Capturer) return;
8226      if (OVE->getSourceExpr())
8227        Visit(OVE->getSourceExpr());
8228    }
8229    void VisitBinaryOperator(BinaryOperator *BinOp) {
8230      if (!Variable || VarWillBeReased || BinOp->getOpcode() != BO_Assign)
8231        return;
8232      Expr *LHS = BinOp->getLHS();
8233      if (const DeclRefExpr *DRE = dyn_cast_or_null<DeclRefExpr>(LHS)) {
8234        if (DRE->getDecl() != Variable)
8235          return;
8236        if (Expr *RHS = BinOp->getRHS()) {
8237          RHS = RHS->IgnoreParenCasts();
8238          llvm::APSInt Value;
8239          VarWillBeReased =
8240            (RHS && RHS->isIntegerConstantExpr(Value, Context) && Value == 0);
8241        }
8242      }
8243    }
8244  };
8245}
8246
8247/// Check whether the given argument is a block which captures a
8248/// variable.
8249static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
8250  assert(owner.Variable && owner.Loc.isValid());
8251
8252  e = e->IgnoreParenCasts();
8253
8254  // Look through [^{...} copy] and Block_copy(^{...}).
8255  if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
8256    Selector Cmd = ME->getSelector();
8257    if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
8258      e = ME->getInstanceReceiver();
8259      if (!e)
8260        return nullptr;
8261      e = e->IgnoreParenCasts();
8262    }
8263  } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
8264    if (CE->getNumArgs() == 1) {
8265      FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
8266      if (Fn) {
8267        const IdentifierInfo *FnI = Fn->getIdentifier();
8268        if (FnI && FnI->isStr("_Block_copy")) {
8269          e = CE->getArg(0)->IgnoreParenCasts();
8270        }
8271      }
8272    }
8273  }
8274
8275  BlockExpr *block = dyn_cast<BlockExpr>(e);
8276  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
8277    return nullptr;
8278
8279  FindCaptureVisitor visitor(S.Context, owner.Variable);
8280  visitor.Visit(block->getBlockDecl()->getBody());
8281  return visitor.VarWillBeReased ? nullptr : visitor.Capturer;
8282}
8283
8284static void diagnoseRetainCycle(Sema &S, Expr *capturer,
8285                                RetainCycleOwner &owner) {
8286  assert(capturer);
8287  assert(owner.Variable && owner.Loc.isValid());
8288
8289  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
8290    << owner.Variable << capturer->getSourceRange();
8291  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
8292    << owner.Indirect << owner.Range;
8293}
8294
8295/// Check for a keyword selector that starts with the word 'add' or
8296/// 'set'.
8297static bool isSetterLikeSelector(Selector sel) {
8298  if (sel.isUnarySelector()) return false;
8299
8300  StringRef str = sel.getNameForSlot(0);
8301  while (!str.empty() && str.front() == '_') str = str.substr(1);
8302  if (str.startswith("set"))
8303    str = str.substr(3);
8304  else if (str.startswith("add")) {
8305    // Specially whitelist 'addOperationWithBlock:'.
8306    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
8307      return false;
8308    str = str.substr(3);
8309  }
8310  else
8311    return false;
8312
8313  if (str.empty()) return true;
8314  return !isLowercase(str.front());
8315}
8316
8317static Optional<int> GetNSMutableArrayArgumentIndex(Sema &S,
8318                                                    ObjCMessageExpr *Message) {
8319  if (S.NSMutableArrayPointer.isNull()) {
8320    IdentifierInfo *NSMutableArrayId =
8321      S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSMutableArray);
8322    NamedDecl *IF = S.LookupSingleName(S.TUScope, NSMutableArrayId,
8323                                       Message->getLocStart(),
8324                                       Sema::LookupOrdinaryName);
8325    ObjCInterfaceDecl *InterfaceDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
8326    if (!InterfaceDecl) {
8327      return None;
8328    }
8329    QualType NSMutableArrayObject =
8330      S.Context.getObjCInterfaceType(InterfaceDecl);
8331    S.NSMutableArrayPointer =
8332      S.Context.getObjCObjectPointerType(NSMutableArrayObject);
8333  }
8334
8335  if (S.NSMutableArrayPointer != Message->getReceiverType()) {
8336    return None;
8337  }
8338
8339  Selector Sel = Message->getSelector();
8340
8341  Optional<NSAPI::NSArrayMethodKind> MKOpt =
8342    S.NSAPIObj->getNSArrayMethodKind(Sel);
8343  if (!MKOpt) {
8344    return None;
8345  }
8346
8347  NSAPI::NSArrayMethodKind MK = *MKOpt;
8348
8349  switch (MK) {
8350    case NSAPI::NSMutableArr_addObject:
8351    case NSAPI::NSMutableArr_insertObjectAtIndex:
8352    case NSAPI::NSMutableArr_setObjectAtIndexedSubscript:
8353      return 0;
8354    case NSAPI::NSMutableArr_replaceObjectAtIndex:
8355      return 1;
8356
8357    default:
8358      return None;
8359  }
8360
8361  return None;
8362}
8363
8364static
8365Optional<int> GetNSMutableDictionaryArgumentIndex(Sema &S,
8366                                                  ObjCMessageExpr *Message) {
8367
8368  if (S.NSMutableDictionaryPointer.isNull()) {
8369    IdentifierInfo *NSMutableDictionaryId =
8370      S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSMutableDictionary);
8371    NamedDecl *IF = S.LookupSingleName(S.TUScope, NSMutableDictionaryId,
8372                                       Message->getLocStart(),
8373                                       Sema::LookupOrdinaryName);
8374    ObjCInterfaceDecl *InterfaceDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
8375    if (!InterfaceDecl) {
8376      return None;
8377    }
8378    QualType NSMutableDictionaryObject =
8379      S.Context.getObjCInterfaceType(InterfaceDecl);
8380    S.NSMutableDictionaryPointer =
8381      S.Context.getObjCObjectPointerType(NSMutableDictionaryObject);
8382  }
8383
8384  if (S.NSMutableDictionaryPointer != Message->getReceiverType()) {
8385    return None;
8386  }
8387
8388  Selector Sel = Message->getSelector();
8389
8390  Optional<NSAPI::NSDictionaryMethodKind> MKOpt =
8391    S.NSAPIObj->getNSDictionaryMethodKind(Sel);
8392  if (!MKOpt) {
8393    return None;
8394  }
8395
8396  NSAPI::NSDictionaryMethodKind MK = *MKOpt;
8397
8398  switch (MK) {
8399    case NSAPI::NSMutableDict_setObjectForKey:
8400    case NSAPI::NSMutableDict_setValueForKey:
8401    case NSAPI::NSMutableDict_setObjectForKeyedSubscript:
8402      return 0;
8403
8404    default:
8405      return None;
8406  }
8407
8408  return None;
8409}
8410
8411static Optional<int> GetNSSetArgumentIndex(Sema &S, ObjCMessageExpr *Message) {
8412
8413  ObjCInterfaceDecl *InterfaceDecl;
8414  if (S.NSMutableSetPointer.isNull()) {
8415    IdentifierInfo *NSMutableSetId =
8416      S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSMutableSet);
8417    NamedDecl *IF = S.LookupSingleName(S.TUScope, NSMutableSetId,
8418                                       Message->getLocStart(),
8419                                       Sema::LookupOrdinaryName);
8420    InterfaceDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
8421    if (InterfaceDecl) {
8422      QualType NSMutableSetObject =
8423        S.Context.getObjCInterfaceType(InterfaceDecl);
8424      S.NSMutableSetPointer =
8425        S.Context.getObjCObjectPointerType(NSMutableSetObject);
8426    }
8427  }
8428
8429  if (S.NSCountedSetPointer.isNull()) {
8430    IdentifierInfo *NSCountedSetId =
8431      S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSCountedSet);
8432    NamedDecl *IF = S.LookupSingleName(S.TUScope, NSCountedSetId,
8433                                       Message->getLocStart(),
8434                                       Sema::LookupOrdinaryName);
8435    InterfaceDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
8436    if (InterfaceDecl) {
8437      QualType NSCountedSetObject =
8438        S.Context.getObjCInterfaceType(InterfaceDecl);
8439      S.NSCountedSetPointer =
8440        S.Context.getObjCObjectPointerType(NSCountedSetObject);
8441    }
8442  }
8443
8444  if (S.NSMutableOrderedSetPointer.isNull()) {
8445    IdentifierInfo *NSOrderedSetId =
8446      S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSMutableOrderedSet);
8447    NamedDecl *IF = S.LookupSingleName(S.TUScope, NSOrderedSetId,
8448                                       Message->getLocStart(),
8449                                       Sema::LookupOrdinaryName);
8450    InterfaceDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
8451    if (InterfaceDecl) {
8452      QualType NSOrderedSetObject =
8453        S.Context.getObjCInterfaceType(InterfaceDecl);
8454      S.NSMutableOrderedSetPointer =
8455        S.Context.getObjCObjectPointerType(NSOrderedSetObject);
8456    }
8457  }
8458
8459  QualType ReceiverType = Message->getReceiverType();
8460
8461  bool IsMutableSet = !S.NSMutableSetPointer.isNull() &&
8462    ReceiverType == S.NSMutableSetPointer;
8463  bool IsMutableOrderedSet = !S.NSMutableOrderedSetPointer.isNull() &&
8464    ReceiverType == S.NSMutableOrderedSetPointer;
8465  bool IsCountedSet = !S.NSCountedSetPointer.isNull() &&
8466    ReceiverType == S.NSCountedSetPointer;
8467
8468  if (!IsMutableSet && !IsMutableOrderedSet && !IsCountedSet) {
8469    return None;
8470  }
8471
8472  Selector Sel = Message->getSelector();
8473
8474  Optional<NSAPI::NSSetMethodKind> MKOpt = S.NSAPIObj->getNSSetMethodKind(Sel);
8475  if (!MKOpt) {
8476    return None;
8477  }
8478
8479  NSAPI::NSSetMethodKind MK = *MKOpt;
8480
8481  switch (MK) {
8482    case NSAPI::NSMutableSet_addObject:
8483    case NSAPI::NSOrderedSet_setObjectAtIndex:
8484    case NSAPI::NSOrderedSet_setObjectAtIndexedSubscript:
8485    case NSAPI::NSOrderedSet_insertObjectAtIndex:
8486      return 0;
8487    case NSAPI::NSOrderedSet_replaceObjectAtIndexWithObject:
8488      return 1;
8489  }
8490
8491  return None;
8492}
8493
8494void Sema::CheckObjCCircularContainer(ObjCMessageExpr *Message) {
8495  if (!Message->isInstanceMessage()) {
8496    return;
8497  }
8498
8499  Optional<int> ArgOpt;
8500
8501  if (!(ArgOpt = GetNSMutableArrayArgumentIndex(*this, Message)) &&
8502      !(ArgOpt = GetNSMutableDictionaryArgumentIndex(*this, Message)) &&
8503      !(ArgOpt = GetNSSetArgumentIndex(*this, Message))) {
8504    return;
8505  }
8506
8507  int ArgIndex = *ArgOpt;
8508
8509  Expr *Receiver = Message->getInstanceReceiver()->IgnoreImpCasts();
8510  if (OpaqueValueExpr *OE = dyn_cast<OpaqueValueExpr>(Receiver)) {
8511    Receiver = OE->getSourceExpr()->IgnoreImpCasts();
8512  }
8513
8514  Expr *Arg = Message->getArg(ArgIndex)->IgnoreImpCasts();
8515  if (OpaqueValueExpr *OE = dyn_cast<OpaqueValueExpr>(Arg)) {
8516    Arg = OE->getSourceExpr()->IgnoreImpCasts();
8517  }
8518
8519  if (DeclRefExpr *ReceiverRE = dyn_cast<DeclRefExpr>(Receiver)) {
8520    if (DeclRefExpr *ArgRE = dyn_cast<DeclRefExpr>(Arg)) {
8521      if (ReceiverRE->getDecl() == ArgRE->getDecl()) {
8522        ValueDecl *Decl = ReceiverRE->getDecl();
8523        Diag(Message->getSourceRange().getBegin(),
8524             diag::warn_objc_circular_container)
8525          << Decl->getName();
8526        Diag(Decl->getLocation(),
8527             diag::note_objc_circular_container_declared_here)
8528          << Decl->getName();
8529      }
8530    }
8531  } else if (ObjCIvarRefExpr *IvarRE = dyn_cast<ObjCIvarRefExpr>(Receiver)) {
8532    if (ObjCIvarRefExpr *IvarArgRE = dyn_cast<ObjCIvarRefExpr>(Arg)) {
8533      if (IvarRE->getDecl() == IvarArgRE->getDecl()) {
8534        ObjCIvarDecl *Decl = IvarRE->getDecl();
8535        Diag(Message->getSourceRange().getBegin(),
8536             diag::warn_objc_circular_container)
8537          << Decl->getName();
8538        Diag(Decl->getLocation(),
8539             diag::note_objc_circular_container_declared_here)
8540          << Decl->getName();
8541      }
8542    }
8543  }
8544
8545}
8546
8547/// Check a message send to see if it's likely to cause a retain cycle.
8548void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
8549  // Only check instance methods whose selector looks like a setter.
8550  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
8551    return;
8552
8553  // Try to find a variable that the receiver is strongly owned by.
8554  RetainCycleOwner owner;
8555  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
8556    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
8557      return;
8558  } else {
8559    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
8560    owner.Variable = getCurMethodDecl()->getSelfDecl();
8561    owner.Loc = msg->getSuperLoc();
8562    owner.Range = msg->getSuperLoc();
8563  }
8564
8565  // Check whether the receiver is captured by any of the arguments.
8566  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
8567    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
8568      return diagnoseRetainCycle(*this, capturer, owner);
8569}
8570
8571/// Check a property assign to see if it's likely to cause a retain cycle.
8572void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
8573  RetainCycleOwner owner;
8574  if (!findRetainCycleOwner(*this, receiver, owner))
8575    return;
8576
8577  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
8578    diagnoseRetainCycle(*this, capturer, owner);
8579}
8580
8581void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
8582  RetainCycleOwner Owner;
8583  if (!considerVariable(Var, /*DeclRefExpr=*/nullptr, Owner))
8584    return;
8585
8586  // Because we don't have an expression for the variable, we have to set the
8587  // location explicitly here.
8588  Owner.Loc = Var->getLocation();
8589  Owner.Range = Var->getSourceRange();
8590
8591  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
8592    diagnoseRetainCycle(*this, Capturer, Owner);
8593}
8594
8595static bool checkUnsafeAssignLiteral(Sema &S, SourceLocation Loc,
8596                                     Expr *RHS, bool isProperty) {
8597  // Check if RHS is an Objective-C object literal, which also can get
8598  // immediately zapped in a weak reference.  Note that we explicitly
8599  // allow ObjCStringLiterals, since those are designed to never really die.
8600  RHS = RHS->IgnoreParenImpCasts();
8601
8602  // This enum needs to match with the 'select' in
8603  // warn_objc_arc_literal_assign (off-by-1).
8604  Sema::ObjCLiteralKind Kind = S.CheckLiteralKind(RHS);
8605  if (Kind == Sema::LK_String || Kind == Sema::LK_None)
8606    return false;
8607
8608  S.Diag(Loc, diag::warn_arc_literal_assign)
8609    << (unsigned) Kind
8610    << (isProperty ? 0 : 1)
8611    << RHS->getSourceRange();
8612
8613  return true;
8614}
8615
8616static bool checkUnsafeAssignObject(Sema &S, SourceLocation Loc,
8617                                    Qualifiers::ObjCLifetime LT,
8618                                    Expr *RHS, bool isProperty) {
8619  // Strip off any implicit cast added to get to the one ARC-specific.
8620  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
8621    if (cast->getCastKind() == CK_ARCConsumeObject) {
8622      S.Diag(Loc, diag::warn_arc_retained_assign)
8623        << (LT == Qualifiers::OCL_ExplicitNone)
8624        << (isProperty ? 0 : 1)
8625        << RHS->getSourceRange();
8626      return true;
8627    }
8628    RHS = cast->getSubExpr();
8629  }
8630
8631  if (LT == Qualifiers::OCL_Weak &&
8632      checkUnsafeAssignLiteral(S, Loc, RHS, isProperty))
8633    return true;
8634
8635  return false;
8636}
8637
8638bool Sema::checkUnsafeAssigns(SourceLocation Loc,
8639                              QualType LHS, Expr *RHS) {
8640  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
8641
8642  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
8643    return false;
8644
8645  if (checkUnsafeAssignObject(*this, Loc, LT, RHS, false))
8646    return true;
8647
8648  return false;
8649}
8650
8651void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
8652                              Expr *LHS, Expr *RHS) {
8653  QualType LHSType;
8654  // PropertyRef on LHS type need be directly obtained from
8655  // its declaration as it has a PseudoType.
8656  ObjCPropertyRefExpr *PRE
8657    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
8658  if (PRE && !PRE->isImplicitProperty()) {
8659    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
8660    if (PD)
8661      LHSType = PD->getType();
8662  }
8663
8664  if (LHSType.isNull())
8665    LHSType = LHS->getType();
8666
8667  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
8668
8669  if (LT == Qualifiers::OCL_Weak) {
8670    if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, Loc))
8671      getCurFunction()->markSafeWeakUse(LHS);
8672  }
8673
8674  if (checkUnsafeAssigns(Loc, LHSType, RHS))
8675    return;
8676
8677  // FIXME. Check for other life times.
8678  if (LT != Qualifiers::OCL_None)
8679    return;
8680
8681  if (PRE) {
8682    if (PRE->isImplicitProperty())
8683      return;
8684    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
8685    if (!PD)
8686      return;
8687
8688    unsigned Attributes = PD->getPropertyAttributes();
8689    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
8690      // when 'assign' attribute was not explicitly specified
8691      // by user, ignore it and rely on property type itself
8692      // for lifetime info.
8693      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
8694      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
8695          LHSType->isObjCRetainableType())
8696        return;
8697
8698      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
8699        if (cast->getCastKind() == CK_ARCConsumeObject) {
8700          Diag(Loc, diag::warn_arc_retained_property_assign)
8701          << RHS->getSourceRange();
8702          return;
8703        }
8704        RHS = cast->getSubExpr();
8705      }
8706    }
8707    else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
8708      if (checkUnsafeAssignObject(*this, Loc, Qualifiers::OCL_Weak, RHS, true))
8709        return;
8710    }
8711  }
8712}
8713
8714//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
8715
8716namespace {
8717bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
8718                                 SourceLocation StmtLoc,
8719                                 const NullStmt *Body) {
8720  // Do not warn if the body is a macro that expands to nothing, e.g:
8721  //
8722  // #define CALL(x)
8723  // if (condition)
8724  //   CALL(0);
8725  //
8726  if (Body->hasLeadingEmptyMacro())
8727    return false;
8728
8729  // Get line numbers of statement and body.
8730  bool StmtLineInvalid;
8731  unsigned StmtLine = SourceMgr.getPresumedLineNumber(StmtLoc,
8732                                                      &StmtLineInvalid);
8733  if (StmtLineInvalid)
8734    return false;
8735
8736  bool BodyLineInvalid;
8737  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
8738                                                      &BodyLineInvalid);
8739  if (BodyLineInvalid)
8740    return false;
8741
8742  // Warn if null statement and body are on the same line.
8743  if (StmtLine != BodyLine)
8744    return false;
8745
8746  return true;
8747}
8748} // Unnamed namespace
8749
8750void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
8751                                 const Stmt *Body,
8752                                 unsigned DiagID) {
8753  // Since this is a syntactic check, don't emit diagnostic for template
8754  // instantiations, this just adds noise.
8755  if (CurrentInstantiationScope)
8756    return;
8757
8758  // The body should be a null statement.
8759  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
8760  if (!NBody)
8761    return;
8762
8763  // Do the usual checks.
8764  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
8765    return;
8766
8767  Diag(NBody->getSemiLoc(), DiagID);
8768  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
8769}
8770
8771void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
8772                                 const Stmt *PossibleBody) {
8773  assert(!CurrentInstantiationScope); // Ensured by caller
8774
8775  SourceLocation StmtLoc;
8776  const Stmt *Body;
8777  unsigned DiagID;
8778  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
8779    StmtLoc = FS->getRParenLoc();
8780    Body = FS->getBody();
8781    DiagID = diag::warn_empty_for_body;
8782  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
8783    StmtLoc = WS->getCond()->getSourceRange().getEnd();
8784    Body = WS->getBody();
8785    DiagID = diag::warn_empty_while_body;
8786  } else
8787    return; // Neither `for' nor `while'.
8788
8789  // The body should be a null statement.
8790  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
8791  if (!NBody)
8792    return;
8793
8794  // Skip expensive checks if diagnostic is disabled.
8795  if (Diags.isIgnored(DiagID, NBody->getSemiLoc()))
8796    return;
8797
8798  // Do the usual checks.
8799  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
8800    return;
8801
8802  // `for(...);' and `while(...);' are popular idioms, so in order to keep
8803  // noise level low, emit diagnostics only if for/while is followed by a
8804  // CompoundStmt, e.g.:
8805  //    for (int i = 0; i < n; i++);
8806  //    {
8807  //      a(i);
8808  //    }
8809  // or if for/while is followed by a statement with more indentation
8810  // than for/while itself:
8811  //    for (int i = 0; i < n; i++);
8812  //      a(i);
8813  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
8814  if (!ProbableTypo) {
8815    bool BodyColInvalid;
8816    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
8817                             PossibleBody->getLocStart(),
8818                             &BodyColInvalid);
8819    if (BodyColInvalid)
8820      return;
8821
8822    bool StmtColInvalid;
8823    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
8824                             S->getLocStart(),
8825                             &StmtColInvalid);
8826    if (StmtColInvalid)
8827      return;
8828
8829    if (BodyCol > StmtCol)
8830      ProbableTypo = true;
8831  }
8832
8833  if (ProbableTypo) {
8834    Diag(NBody->getSemiLoc(), DiagID);
8835    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
8836  }
8837}
8838
8839//===--- CHECK: Warn on self move with std::move. -------------------------===//
8840
8841/// DiagnoseSelfMove - Emits a warning if a value is moved to itself.
8842void Sema::DiagnoseSelfMove(const Expr *LHSExpr, const Expr *RHSExpr,
8843                             SourceLocation OpLoc) {
8844
8845  if (Diags.isIgnored(diag::warn_sizeof_pointer_expr_memaccess, OpLoc))
8846    return;
8847
8848  if (!ActiveTemplateInstantiations.empty())
8849    return;
8850
8851  // Strip parens and casts away.
8852  LHSExpr = LHSExpr->IgnoreParenImpCasts();
8853  RHSExpr = RHSExpr->IgnoreParenImpCasts();
8854
8855  // Check for a call expression
8856  const CallExpr *CE = dyn_cast<CallExpr>(RHSExpr);
8857  if (!CE || CE->getNumArgs() != 1)
8858    return;
8859
8860  // Check for a call to std::move
8861  const FunctionDecl *FD = CE->getDirectCallee();
8862  if (!FD || !FD->isInStdNamespace() || !FD->getIdentifier() ||
8863      !FD->getIdentifier()->isStr("move"))
8864    return;
8865
8866  // Get argument from std::move
8867  RHSExpr = CE->getArg(0);
8868
8869  const DeclRefExpr *LHSDeclRef = dyn_cast<DeclRefExpr>(LHSExpr);
8870  const DeclRefExpr *RHSDeclRef = dyn_cast<DeclRefExpr>(RHSExpr);
8871
8872  // Two DeclRefExpr's, check that the decls are the same.
8873  if (LHSDeclRef && RHSDeclRef) {
8874    if (!LHSDeclRef->getDecl() || !RHSDeclRef->getDecl())
8875      return;
8876    if (LHSDeclRef->getDecl()->getCanonicalDecl() !=
8877        RHSDeclRef->getDecl()->getCanonicalDecl())
8878      return;
8879
8880    Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
8881                                        << LHSExpr->getSourceRange()
8882                                        << RHSExpr->getSourceRange();
8883    return;
8884  }
8885
8886  // Member variables require a different approach to check for self moves.
8887  // MemberExpr's are the same if every nested MemberExpr refers to the same
8888  // Decl and that the base Expr's are DeclRefExpr's with the same Decl or
8889  // the base Expr's are CXXThisExpr's.
8890  const Expr *LHSBase = LHSExpr;
8891  const Expr *RHSBase = RHSExpr;
8892  const MemberExpr *LHSME = dyn_cast<MemberExpr>(LHSExpr);
8893  const MemberExpr *RHSME = dyn_cast<MemberExpr>(RHSExpr);
8894  if (!LHSME || !RHSME)
8895    return;
8896
8897  while (LHSME && RHSME) {
8898    if (LHSME->getMemberDecl()->getCanonicalDecl() !=
8899        RHSME->getMemberDecl()->getCanonicalDecl())
8900      return;
8901
8902    LHSBase = LHSME->getBase();
8903    RHSBase = RHSME->getBase();
8904    LHSME = dyn_cast<MemberExpr>(LHSBase);
8905    RHSME = dyn_cast<MemberExpr>(RHSBase);
8906  }
8907
8908  LHSDeclRef = dyn_cast<DeclRefExpr>(LHSBase);
8909  RHSDeclRef = dyn_cast<DeclRefExpr>(RHSBase);
8910  if (LHSDeclRef && RHSDeclRef) {
8911    if (!LHSDeclRef->getDecl() || !RHSDeclRef->getDecl())
8912      return;
8913    if (LHSDeclRef->getDecl()->getCanonicalDecl() !=
8914        RHSDeclRef->getDecl()->getCanonicalDecl())
8915      return;
8916
8917    Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
8918                                        << LHSExpr->getSourceRange()
8919                                        << RHSExpr->getSourceRange();
8920    return;
8921  }
8922
8923  if (isa<CXXThisExpr>(LHSBase) && isa<CXXThisExpr>(RHSBase))
8924    Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
8925                                        << LHSExpr->getSourceRange()
8926                                        << RHSExpr->getSourceRange();
8927}
8928
8929//===--- Layout compatibility ----------------------------------------------//
8930
8931namespace {
8932
8933bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
8934
8935/// \brief Check if two enumeration types are layout-compatible.
8936bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
8937  // C++11 [dcl.enum] p8:
8938  // Two enumeration types are layout-compatible if they have the same
8939  // underlying type.
8940  return ED1->isComplete() && ED2->isComplete() &&
8941         C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
8942}
8943
8944/// \brief Check if two fields are layout-compatible.
8945bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
8946  if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
8947    return false;
8948
8949  if (Field1->isBitField() != Field2->isBitField())
8950    return false;
8951
8952  if (Field1->isBitField()) {
8953    // Make sure that the bit-fields are the same length.
8954    unsigned Bits1 = Field1->getBitWidthValue(C);
8955    unsigned Bits2 = Field2->getBitWidthValue(C);
8956
8957    if (Bits1 != Bits2)
8958      return false;
8959  }
8960
8961  return true;
8962}
8963
8964/// \brief Check if two standard-layout structs are layout-compatible.
8965/// (C++11 [class.mem] p17)
8966bool isLayoutCompatibleStruct(ASTContext &C,
8967                              RecordDecl *RD1,
8968                              RecordDecl *RD2) {
8969  // If both records are C++ classes, check that base classes match.
8970  if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
8971    // If one of records is a CXXRecordDecl we are in C++ mode,
8972    // thus the other one is a CXXRecordDecl, too.
8973    const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
8974    // Check number of base classes.
8975    if (D1CXX->getNumBases() != D2CXX->getNumBases())
8976      return false;
8977
8978    // Check the base classes.
8979    for (CXXRecordDecl::base_class_const_iterator
8980               Base1 = D1CXX->bases_begin(),
8981           BaseEnd1 = D1CXX->bases_end(),
8982              Base2 = D2CXX->bases_begin();
8983         Base1 != BaseEnd1;
8984         ++Base1, ++Base2) {
8985      if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
8986        return false;
8987    }
8988  } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
8989    // If only RD2 is a C++ class, it should have zero base classes.
8990    if (D2CXX->getNumBases() > 0)
8991      return false;
8992  }
8993
8994  // Check the fields.
8995  RecordDecl::field_iterator Field2 = RD2->field_begin(),
8996                             Field2End = RD2->field_end(),
8997                             Field1 = RD1->field_begin(),
8998                             Field1End = RD1->field_end();
8999  for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
9000    if (!isLayoutCompatible(C, *Field1, *Field2))
9001      return false;
9002  }
9003  if (Field1 != Field1End || Field2 != Field2End)
9004    return false;
9005
9006  return true;
9007}
9008
9009/// \brief Check if two standard-layout unions are layout-compatible.
9010/// (C++11 [class.mem] p18)
9011bool isLayoutCompatibleUnion(ASTContext &C,
9012                             RecordDecl *RD1,
9013                             RecordDecl *RD2) {
9014  llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
9015  for (auto *Field2 : RD2->fields())
9016    UnmatchedFields.insert(Field2);
9017
9018  for (auto *Field1 : RD1->fields()) {
9019    llvm::SmallPtrSet<FieldDecl *, 8>::iterator
9020        I = UnmatchedFields.begin(),
9021        E = UnmatchedFields.end();
9022
9023    for ( ; I != E; ++I) {
9024      if (isLayoutCompatible(C, Field1, *I)) {
9025        bool Result = UnmatchedFields.erase(*I);
9026        (void) Result;
9027        assert(Result);
9028        break;
9029      }
9030    }
9031    if (I == E)
9032      return false;
9033  }
9034
9035  return UnmatchedFields.empty();
9036}
9037
9038bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
9039  if (RD1->isUnion() != RD2->isUnion())
9040    return false;
9041
9042  if (RD1->isUnion())
9043    return isLayoutCompatibleUnion(C, RD1, RD2);
9044  else
9045    return isLayoutCompatibleStruct(C, RD1, RD2);
9046}
9047
9048/// \brief Check if two types are layout-compatible in C++11 sense.
9049bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
9050  if (T1.isNull() || T2.isNull())
9051    return false;
9052
9053  // C++11 [basic.types] p11:
9054  // If two types T1 and T2 are the same type, then T1 and T2 are
9055  // layout-compatible types.
9056  if (C.hasSameType(T1, T2))
9057    return true;
9058
9059  T1 = T1.getCanonicalType().getUnqualifiedType();
9060  T2 = T2.getCanonicalType().getUnqualifiedType();
9061
9062  const Type::TypeClass TC1 = T1->getTypeClass();
9063  const Type::TypeClass TC2 = T2->getTypeClass();
9064
9065  if (TC1 != TC2)
9066    return false;
9067
9068  if (TC1 == Type::Enum) {
9069    return isLayoutCompatible(C,
9070                              cast<EnumType>(T1)->getDecl(),
9071                              cast<EnumType>(T2)->getDecl());
9072  } else if (TC1 == Type::Record) {
9073    if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
9074      return false;
9075
9076    return isLayoutCompatible(C,
9077                              cast<RecordType>(T1)->getDecl(),
9078                              cast<RecordType>(T2)->getDecl());
9079  }
9080
9081  return false;
9082}
9083}
9084
9085//===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
9086
9087namespace {
9088/// \brief Given a type tag expression find the type tag itself.
9089///
9090/// \param TypeExpr Type tag expression, as it appears in user's code.
9091///
9092/// \param VD Declaration of an identifier that appears in a type tag.
9093///
9094/// \param MagicValue Type tag magic value.
9095bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
9096                     const ValueDecl **VD, uint64_t *MagicValue) {
9097  while(true) {
9098    if (!TypeExpr)
9099      return false;
9100
9101    TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
9102
9103    switch (TypeExpr->getStmtClass()) {
9104    case Stmt::UnaryOperatorClass: {
9105      const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
9106      if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
9107        TypeExpr = UO->getSubExpr();
9108        continue;
9109      }
9110      return false;
9111    }
9112
9113    case Stmt::DeclRefExprClass: {
9114      const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
9115      *VD = DRE->getDecl();
9116      return true;
9117    }
9118
9119    case Stmt::IntegerLiteralClass: {
9120      const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
9121      llvm::APInt MagicValueAPInt = IL->getValue();
9122      if (MagicValueAPInt.getActiveBits() <= 64) {
9123        *MagicValue = MagicValueAPInt.getZExtValue();
9124        return true;
9125      } else
9126        return false;
9127    }
9128
9129    case Stmt::BinaryConditionalOperatorClass:
9130    case Stmt::ConditionalOperatorClass: {
9131      const AbstractConditionalOperator *ACO =
9132          cast<AbstractConditionalOperator>(TypeExpr);
9133      bool Result;
9134      if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
9135        if (Result)
9136          TypeExpr = ACO->getTrueExpr();
9137        else
9138          TypeExpr = ACO->getFalseExpr();
9139        continue;
9140      }
9141      return false;
9142    }
9143
9144    case Stmt::BinaryOperatorClass: {
9145      const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
9146      if (BO->getOpcode() == BO_Comma) {
9147        TypeExpr = BO->getRHS();
9148        continue;
9149      }
9150      return false;
9151    }
9152
9153    default:
9154      return false;
9155    }
9156  }
9157}
9158
9159/// \brief Retrieve the C type corresponding to type tag TypeExpr.
9160///
9161/// \param TypeExpr Expression that specifies a type tag.
9162///
9163/// \param MagicValues Registered magic values.
9164///
9165/// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
9166///        kind.
9167///
9168/// \param TypeInfo Information about the corresponding C type.
9169///
9170/// \returns true if the corresponding C type was found.
9171bool GetMatchingCType(
9172        const IdentifierInfo *ArgumentKind,
9173        const Expr *TypeExpr, const ASTContext &Ctx,
9174        const llvm::DenseMap<Sema::TypeTagMagicValue,
9175                             Sema::TypeTagData> *MagicValues,
9176        bool &FoundWrongKind,
9177        Sema::TypeTagData &TypeInfo) {
9178  FoundWrongKind = false;
9179
9180  // Variable declaration that has type_tag_for_datatype attribute.
9181  const ValueDecl *VD = nullptr;
9182
9183  uint64_t MagicValue;
9184
9185  if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
9186    return false;
9187
9188  if (VD) {
9189    if (TypeTagForDatatypeAttr *I = VD->getAttr<TypeTagForDatatypeAttr>()) {
9190      if (I->getArgumentKind() != ArgumentKind) {
9191        FoundWrongKind = true;
9192        return false;
9193      }
9194      TypeInfo.Type = I->getMatchingCType();
9195      TypeInfo.LayoutCompatible = I->getLayoutCompatible();
9196      TypeInfo.MustBeNull = I->getMustBeNull();
9197      return true;
9198    }
9199    return false;
9200  }
9201
9202  if (!MagicValues)
9203    return false;
9204
9205  llvm::DenseMap<Sema::TypeTagMagicValue,
9206                 Sema::TypeTagData>::const_iterator I =
9207      MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
9208  if (I == MagicValues->end())
9209    return false;
9210
9211  TypeInfo = I->second;
9212  return true;
9213}
9214} // unnamed namespace
9215
9216void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
9217                                      uint64_t MagicValue, QualType Type,
9218                                      bool LayoutCompatible,
9219                                      bool MustBeNull) {
9220  if (!TypeTagForDatatypeMagicValues)
9221    TypeTagForDatatypeMagicValues.reset(
9222        new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
9223
9224  TypeTagMagicValue Magic(ArgumentKind, MagicValue);
9225  (*TypeTagForDatatypeMagicValues)[Magic] =
9226      TypeTagData(Type, LayoutCompatible, MustBeNull);
9227}
9228
9229namespace {
9230bool IsSameCharType(QualType T1, QualType T2) {
9231  const BuiltinType *BT1 = T1->getAs<BuiltinType>();
9232  if (!BT1)
9233    return false;
9234
9235  const BuiltinType *BT2 = T2->getAs<BuiltinType>();
9236  if (!BT2)
9237    return false;
9238
9239  BuiltinType::Kind T1Kind = BT1->getKind();
9240  BuiltinType::Kind T2Kind = BT2->getKind();
9241
9242  return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
9243         (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
9244         (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
9245         (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
9246}
9247} // unnamed namespace
9248
9249void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
9250                                    const Expr * const *ExprArgs) {
9251  const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
9252  bool IsPointerAttr = Attr->getIsPointer();
9253
9254  const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
9255  bool FoundWrongKind;
9256  TypeTagData TypeInfo;
9257  if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
9258                        TypeTagForDatatypeMagicValues.get(),
9259                        FoundWrongKind, TypeInfo)) {
9260    if (FoundWrongKind)
9261      Diag(TypeTagExpr->getExprLoc(),
9262           diag::warn_type_tag_for_datatype_wrong_kind)
9263        << TypeTagExpr->getSourceRange();
9264    return;
9265  }
9266
9267  const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
9268  if (IsPointerAttr) {
9269    // Skip implicit cast of pointer to `void *' (as a function argument).
9270    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
9271      if (ICE->getType()->isVoidPointerType() &&
9272          ICE->getCastKind() == CK_BitCast)
9273        ArgumentExpr = ICE->getSubExpr();
9274  }
9275  QualType ArgumentType = ArgumentExpr->getType();
9276
9277  // Passing a `void*' pointer shouldn't trigger a warning.
9278  if (IsPointerAttr && ArgumentType->isVoidPointerType())
9279    return;
9280
9281  if (TypeInfo.MustBeNull) {
9282    // Type tag with matching void type requires a null pointer.
9283    if (!ArgumentExpr->isNullPointerConstant(Context,
9284                                             Expr::NPC_ValueDependentIsNotNull)) {
9285      Diag(ArgumentExpr->getExprLoc(),
9286           diag::warn_type_safety_null_pointer_required)
9287          << ArgumentKind->getName()
9288          << ArgumentExpr->getSourceRange()
9289          << TypeTagExpr->getSourceRange();
9290    }
9291    return;
9292  }
9293
9294  QualType RequiredType = TypeInfo.Type;
9295  if (IsPointerAttr)
9296    RequiredType = Context.getPointerType(RequiredType);
9297
9298  bool mismatch = false;
9299  if (!TypeInfo.LayoutCompatible) {
9300    mismatch = !Context.hasSameType(ArgumentType, RequiredType);
9301
9302    // C++11 [basic.fundamental] p1:
9303    // Plain char, signed char, and unsigned char are three distinct types.
9304    //
9305    // But we treat plain `char' as equivalent to `signed char' or `unsigned
9306    // char' depending on the current char signedness mode.
9307    if (mismatch)
9308      if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
9309                                           RequiredType->getPointeeType())) ||
9310          (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
9311        mismatch = false;
9312  } else
9313    if (IsPointerAttr)
9314      mismatch = !isLayoutCompatible(Context,
9315                                     ArgumentType->getPointeeType(),
9316                                     RequiredType->getPointeeType());
9317    else
9318      mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
9319
9320  if (mismatch)
9321    Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
9322        << ArgumentType << ArgumentKind
9323        << TypeInfo.LayoutCompatible << RequiredType
9324        << ArgumentExpr->getSourceRange()
9325        << TypeTagExpr->getSourceRange();
9326}
9327
9328