SemaChecking.cpp revision ac1303eca6cbe3e623fb5ec6fe7ec184ef4b0dfa
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements extra semantic analysis beyond what is enforced 11// by the C type system. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Sema/Initialization.h" 16#include "clang/Sema/Sema.h" 17#include "clang/Sema/SemaInternal.h" 18#include "clang/Sema/Initialization.h" 19#include "clang/Sema/ScopeInfo.h" 20#include "clang/Analysis/Analyses/FormatString.h" 21#include "clang/AST/ASTContext.h" 22#include "clang/AST/CharUnits.h" 23#include "clang/AST/DeclCXX.h" 24#include "clang/AST/DeclObjC.h" 25#include "clang/AST/ExprCXX.h" 26#include "clang/AST/ExprObjC.h" 27#include "clang/AST/EvaluatedExprVisitor.h" 28#include "clang/AST/DeclObjC.h" 29#include "clang/AST/StmtCXX.h" 30#include "clang/AST/StmtObjC.h" 31#include "clang/Lex/Preprocessor.h" 32#include "llvm/ADT/BitVector.h" 33#include "llvm/ADT/SmallString.h" 34#include "llvm/ADT/STLExtras.h" 35#include "llvm/Support/raw_ostream.h" 36#include "clang/Basic/TargetBuiltins.h" 37#include "clang/Basic/TargetInfo.h" 38#include "clang/Basic/ConvertUTF.h" 39#include <limits> 40using namespace clang; 41using namespace sema; 42 43SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 44 unsigned ByteNo) const { 45 return SL->getLocationOfByte(ByteNo, PP.getSourceManager(), 46 PP.getLangOptions(), PP.getTargetInfo()); 47} 48 49/// Checks that a call expression's argument count is the desired number. 50/// This is useful when doing custom type-checking. Returns true on error. 51static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) { 52 unsigned argCount = call->getNumArgs(); 53 if (argCount == desiredArgCount) return false; 54 55 if (argCount < desiredArgCount) 56 return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args) 57 << 0 /*function call*/ << desiredArgCount << argCount 58 << call->getSourceRange(); 59 60 // Highlight all the excess arguments. 61 SourceRange range(call->getArg(desiredArgCount)->getLocStart(), 62 call->getArg(argCount - 1)->getLocEnd()); 63 64 return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args) 65 << 0 /*function call*/ << desiredArgCount << argCount 66 << call->getArg(1)->getSourceRange(); 67} 68 69/// CheckBuiltinAnnotationString - Checks that string argument to the builtin 70/// annotation is a non wide string literal. 71static bool CheckBuiltinAnnotationString(Sema &S, Expr *Arg) { 72 Arg = Arg->IgnoreParenCasts(); 73 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 74 if (!Literal || !Literal->isAscii()) { 75 S.Diag(Arg->getLocStart(), diag::err_builtin_annotation_not_string_constant) 76 << Arg->getSourceRange(); 77 return true; 78 } 79 return false; 80} 81 82ExprResult 83Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 84 ExprResult TheCallResult(Owned(TheCall)); 85 86 // Find out if any arguments are required to be integer constant expressions. 87 unsigned ICEArguments = 0; 88 ASTContext::GetBuiltinTypeError Error; 89 Context.GetBuiltinType(BuiltinID, Error, &ICEArguments); 90 if (Error != ASTContext::GE_None) 91 ICEArguments = 0; // Don't diagnose previously diagnosed errors. 92 93 // If any arguments are required to be ICE's, check and diagnose. 94 for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) { 95 // Skip arguments not required to be ICE's. 96 if ((ICEArguments & (1 << ArgNo)) == 0) continue; 97 98 llvm::APSInt Result; 99 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 100 return true; 101 ICEArguments &= ~(1 << ArgNo); 102 } 103 104 switch (BuiltinID) { 105 case Builtin::BI__builtin___CFStringMakeConstantString: 106 assert(TheCall->getNumArgs() == 1 && 107 "Wrong # arguments to builtin CFStringMakeConstantString"); 108 if (CheckObjCString(TheCall->getArg(0))) 109 return ExprError(); 110 break; 111 case Builtin::BI__builtin_stdarg_start: 112 case Builtin::BI__builtin_va_start: 113 if (SemaBuiltinVAStart(TheCall)) 114 return ExprError(); 115 break; 116 case Builtin::BI__builtin_isgreater: 117 case Builtin::BI__builtin_isgreaterequal: 118 case Builtin::BI__builtin_isless: 119 case Builtin::BI__builtin_islessequal: 120 case Builtin::BI__builtin_islessgreater: 121 case Builtin::BI__builtin_isunordered: 122 if (SemaBuiltinUnorderedCompare(TheCall)) 123 return ExprError(); 124 break; 125 case Builtin::BI__builtin_fpclassify: 126 if (SemaBuiltinFPClassification(TheCall, 6)) 127 return ExprError(); 128 break; 129 case Builtin::BI__builtin_isfinite: 130 case Builtin::BI__builtin_isinf: 131 case Builtin::BI__builtin_isinf_sign: 132 case Builtin::BI__builtin_isnan: 133 case Builtin::BI__builtin_isnormal: 134 if (SemaBuiltinFPClassification(TheCall, 1)) 135 return ExprError(); 136 break; 137 case Builtin::BI__builtin_shufflevector: 138 return SemaBuiltinShuffleVector(TheCall); 139 // TheCall will be freed by the smart pointer here, but that's fine, since 140 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 141 case Builtin::BI__builtin_prefetch: 142 if (SemaBuiltinPrefetch(TheCall)) 143 return ExprError(); 144 break; 145 case Builtin::BI__builtin_object_size: 146 if (SemaBuiltinObjectSize(TheCall)) 147 return ExprError(); 148 break; 149 case Builtin::BI__builtin_longjmp: 150 if (SemaBuiltinLongjmp(TheCall)) 151 return ExprError(); 152 break; 153 154 case Builtin::BI__builtin_classify_type: 155 if (checkArgCount(*this, TheCall, 1)) return true; 156 TheCall->setType(Context.IntTy); 157 break; 158 case Builtin::BI__builtin_constant_p: 159 if (checkArgCount(*this, TheCall, 1)) return true; 160 TheCall->setType(Context.IntTy); 161 break; 162 case Builtin::BI__sync_fetch_and_add: 163 case Builtin::BI__sync_fetch_and_add_1: 164 case Builtin::BI__sync_fetch_and_add_2: 165 case Builtin::BI__sync_fetch_and_add_4: 166 case Builtin::BI__sync_fetch_and_add_8: 167 case Builtin::BI__sync_fetch_and_add_16: 168 case Builtin::BI__sync_fetch_and_sub: 169 case Builtin::BI__sync_fetch_and_sub_1: 170 case Builtin::BI__sync_fetch_and_sub_2: 171 case Builtin::BI__sync_fetch_and_sub_4: 172 case Builtin::BI__sync_fetch_and_sub_8: 173 case Builtin::BI__sync_fetch_and_sub_16: 174 case Builtin::BI__sync_fetch_and_or: 175 case Builtin::BI__sync_fetch_and_or_1: 176 case Builtin::BI__sync_fetch_and_or_2: 177 case Builtin::BI__sync_fetch_and_or_4: 178 case Builtin::BI__sync_fetch_and_or_8: 179 case Builtin::BI__sync_fetch_and_or_16: 180 case Builtin::BI__sync_fetch_and_and: 181 case Builtin::BI__sync_fetch_and_and_1: 182 case Builtin::BI__sync_fetch_and_and_2: 183 case Builtin::BI__sync_fetch_and_and_4: 184 case Builtin::BI__sync_fetch_and_and_8: 185 case Builtin::BI__sync_fetch_and_and_16: 186 case Builtin::BI__sync_fetch_and_xor: 187 case Builtin::BI__sync_fetch_and_xor_1: 188 case Builtin::BI__sync_fetch_and_xor_2: 189 case Builtin::BI__sync_fetch_and_xor_4: 190 case Builtin::BI__sync_fetch_and_xor_8: 191 case Builtin::BI__sync_fetch_and_xor_16: 192 case Builtin::BI__sync_add_and_fetch: 193 case Builtin::BI__sync_add_and_fetch_1: 194 case Builtin::BI__sync_add_and_fetch_2: 195 case Builtin::BI__sync_add_and_fetch_4: 196 case Builtin::BI__sync_add_and_fetch_8: 197 case Builtin::BI__sync_add_and_fetch_16: 198 case Builtin::BI__sync_sub_and_fetch: 199 case Builtin::BI__sync_sub_and_fetch_1: 200 case Builtin::BI__sync_sub_and_fetch_2: 201 case Builtin::BI__sync_sub_and_fetch_4: 202 case Builtin::BI__sync_sub_and_fetch_8: 203 case Builtin::BI__sync_sub_and_fetch_16: 204 case Builtin::BI__sync_and_and_fetch: 205 case Builtin::BI__sync_and_and_fetch_1: 206 case Builtin::BI__sync_and_and_fetch_2: 207 case Builtin::BI__sync_and_and_fetch_4: 208 case Builtin::BI__sync_and_and_fetch_8: 209 case Builtin::BI__sync_and_and_fetch_16: 210 case Builtin::BI__sync_or_and_fetch: 211 case Builtin::BI__sync_or_and_fetch_1: 212 case Builtin::BI__sync_or_and_fetch_2: 213 case Builtin::BI__sync_or_and_fetch_4: 214 case Builtin::BI__sync_or_and_fetch_8: 215 case Builtin::BI__sync_or_and_fetch_16: 216 case Builtin::BI__sync_xor_and_fetch: 217 case Builtin::BI__sync_xor_and_fetch_1: 218 case Builtin::BI__sync_xor_and_fetch_2: 219 case Builtin::BI__sync_xor_and_fetch_4: 220 case Builtin::BI__sync_xor_and_fetch_8: 221 case Builtin::BI__sync_xor_and_fetch_16: 222 case Builtin::BI__sync_val_compare_and_swap: 223 case Builtin::BI__sync_val_compare_and_swap_1: 224 case Builtin::BI__sync_val_compare_and_swap_2: 225 case Builtin::BI__sync_val_compare_and_swap_4: 226 case Builtin::BI__sync_val_compare_and_swap_8: 227 case Builtin::BI__sync_val_compare_and_swap_16: 228 case Builtin::BI__sync_bool_compare_and_swap: 229 case Builtin::BI__sync_bool_compare_and_swap_1: 230 case Builtin::BI__sync_bool_compare_and_swap_2: 231 case Builtin::BI__sync_bool_compare_and_swap_4: 232 case Builtin::BI__sync_bool_compare_and_swap_8: 233 case Builtin::BI__sync_bool_compare_and_swap_16: 234 case Builtin::BI__sync_lock_test_and_set: 235 case Builtin::BI__sync_lock_test_and_set_1: 236 case Builtin::BI__sync_lock_test_and_set_2: 237 case Builtin::BI__sync_lock_test_and_set_4: 238 case Builtin::BI__sync_lock_test_and_set_8: 239 case Builtin::BI__sync_lock_test_and_set_16: 240 case Builtin::BI__sync_lock_release: 241 case Builtin::BI__sync_lock_release_1: 242 case Builtin::BI__sync_lock_release_2: 243 case Builtin::BI__sync_lock_release_4: 244 case Builtin::BI__sync_lock_release_8: 245 case Builtin::BI__sync_lock_release_16: 246 case Builtin::BI__sync_swap: 247 case Builtin::BI__sync_swap_1: 248 case Builtin::BI__sync_swap_2: 249 case Builtin::BI__sync_swap_4: 250 case Builtin::BI__sync_swap_8: 251 case Builtin::BI__sync_swap_16: 252 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 253 case Builtin::BI__atomic_load: 254 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Load); 255 case Builtin::BI__atomic_store: 256 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Store); 257 case Builtin::BI__atomic_init: 258 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Init); 259 case Builtin::BI__atomic_exchange: 260 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xchg); 261 case Builtin::BI__atomic_compare_exchange_strong: 262 return SemaAtomicOpsOverloaded(move(TheCallResult), 263 AtomicExpr::CmpXchgStrong); 264 case Builtin::BI__atomic_compare_exchange_weak: 265 return SemaAtomicOpsOverloaded(move(TheCallResult), 266 AtomicExpr::CmpXchgWeak); 267 case Builtin::BI__atomic_fetch_add: 268 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Add); 269 case Builtin::BI__atomic_fetch_sub: 270 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Sub); 271 case Builtin::BI__atomic_fetch_and: 272 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::And); 273 case Builtin::BI__atomic_fetch_or: 274 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Or); 275 case Builtin::BI__atomic_fetch_xor: 276 return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::Xor); 277 case Builtin::BI__builtin_annotation: 278 if (CheckBuiltinAnnotationString(*this, TheCall->getArg(1))) 279 return ExprError(); 280 break; 281 } 282 283 // Since the target specific builtins for each arch overlap, only check those 284 // of the arch we are compiling for. 285 if (BuiltinID >= Builtin::FirstTSBuiltin) { 286 switch (Context.getTargetInfo().getTriple().getArch()) { 287 case llvm::Triple::arm: 288 case llvm::Triple::thumb: 289 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 290 return ExprError(); 291 break; 292 default: 293 break; 294 } 295 } 296 297 return move(TheCallResult); 298} 299 300// Get the valid immediate range for the specified NEON type code. 301static unsigned RFT(unsigned t, bool shift = false) { 302 NeonTypeFlags Type(t); 303 int IsQuad = Type.isQuad(); 304 switch (Type.getEltType()) { 305 case NeonTypeFlags::Int8: 306 case NeonTypeFlags::Poly8: 307 return shift ? 7 : (8 << IsQuad) - 1; 308 case NeonTypeFlags::Int16: 309 case NeonTypeFlags::Poly16: 310 return shift ? 15 : (4 << IsQuad) - 1; 311 case NeonTypeFlags::Int32: 312 return shift ? 31 : (2 << IsQuad) - 1; 313 case NeonTypeFlags::Int64: 314 return shift ? 63 : (1 << IsQuad) - 1; 315 case NeonTypeFlags::Float16: 316 assert(!shift && "cannot shift float types!"); 317 return (4 << IsQuad) - 1; 318 case NeonTypeFlags::Float32: 319 assert(!shift && "cannot shift float types!"); 320 return (2 << IsQuad) - 1; 321 } 322 llvm_unreachable("Invalid NeonTypeFlag!"); 323} 324 325/// getNeonEltType - Return the QualType corresponding to the elements of 326/// the vector type specified by the NeonTypeFlags. This is used to check 327/// the pointer arguments for Neon load/store intrinsics. 328static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) { 329 switch (Flags.getEltType()) { 330 case NeonTypeFlags::Int8: 331 return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy; 332 case NeonTypeFlags::Int16: 333 return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy; 334 case NeonTypeFlags::Int32: 335 return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy; 336 case NeonTypeFlags::Int64: 337 return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy; 338 case NeonTypeFlags::Poly8: 339 return Context.SignedCharTy; 340 case NeonTypeFlags::Poly16: 341 return Context.ShortTy; 342 case NeonTypeFlags::Float16: 343 return Context.UnsignedShortTy; 344 case NeonTypeFlags::Float32: 345 return Context.FloatTy; 346 } 347 llvm_unreachable("Invalid NeonTypeFlag!"); 348} 349 350bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 351 llvm::APSInt Result; 352 353 unsigned mask = 0; 354 unsigned TV = 0; 355 int PtrArgNum = -1; 356 bool HasConstPtr = false; 357 switch (BuiltinID) { 358#define GET_NEON_OVERLOAD_CHECK 359#include "clang/Basic/arm_neon.inc" 360#undef GET_NEON_OVERLOAD_CHECK 361 } 362 363 // For NEON intrinsics which are overloaded on vector element type, validate 364 // the immediate which specifies which variant to emit. 365 unsigned ImmArg = TheCall->getNumArgs()-1; 366 if (mask) { 367 if (SemaBuiltinConstantArg(TheCall, ImmArg, Result)) 368 return true; 369 370 TV = Result.getLimitedValue(64); 371 if ((TV > 63) || (mask & (1 << TV)) == 0) 372 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 373 << TheCall->getArg(ImmArg)->getSourceRange(); 374 } 375 376 if (PtrArgNum >= 0) { 377 // Check that pointer arguments have the specified type. 378 Expr *Arg = TheCall->getArg(PtrArgNum); 379 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) 380 Arg = ICE->getSubExpr(); 381 ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg); 382 QualType RHSTy = RHS.get()->getType(); 383 QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context); 384 if (HasConstPtr) 385 EltTy = EltTy.withConst(); 386 QualType LHSTy = Context.getPointerType(EltTy); 387 AssignConvertType ConvTy; 388 ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS); 389 if (RHS.isInvalid()) 390 return true; 391 if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy, 392 RHS.get(), AA_Assigning)) 393 return true; 394 } 395 396 // For NEON intrinsics which take an immediate value as part of the 397 // instruction, range check them here. 398 unsigned i = 0, l = 0, u = 0; 399 switch (BuiltinID) { 400 default: return false; 401 case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; 402 case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; 403 case ARM::BI__builtin_arm_vcvtr_f: 404 case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; 405#define GET_NEON_IMMEDIATE_CHECK 406#include "clang/Basic/arm_neon.inc" 407#undef GET_NEON_IMMEDIATE_CHECK 408 }; 409 410 // Check that the immediate argument is actually a constant. 411 if (SemaBuiltinConstantArg(TheCall, i, Result)) 412 return true; 413 414 // Range check against the upper/lower values for this isntruction. 415 unsigned Val = Result.getZExtValue(); 416 if (Val < l || Val > (u + l)) 417 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 418 << l << u+l << TheCall->getArg(i)->getSourceRange(); 419 420 // FIXME: VFP Intrinsics should error if VFP not present. 421 return false; 422} 423 424/// CheckFunctionCall - Check a direct function call for various correctness 425/// and safety properties not strictly enforced by the C type system. 426bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 427 // Get the IdentifierInfo* for the called function. 428 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 429 430 // None of the checks below are needed for functions that don't have 431 // simple names (e.g., C++ conversion functions). 432 if (!FnInfo) 433 return false; 434 435 // FIXME: This mechanism should be abstracted to be less fragile and 436 // more efficient. For example, just map function ids to custom 437 // handlers. 438 439 // Printf and scanf checking. 440 for (specific_attr_iterator<FormatAttr> 441 i = FDecl->specific_attr_begin<FormatAttr>(), 442 e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { 443 CheckFormatArguments(*i, TheCall); 444 } 445 446 for (specific_attr_iterator<NonNullAttr> 447 i = FDecl->specific_attr_begin<NonNullAttr>(), 448 e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) { 449 CheckNonNullArguments(*i, TheCall->getArgs(), 450 TheCall->getCallee()->getLocStart()); 451 } 452 453 unsigned CMId = FDecl->getMemoryFunctionKind(); 454 if (CMId == 0) 455 return false; 456 457 // Handle memory setting and copying functions. 458 if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat) 459 CheckStrlcpycatArguments(TheCall, FnInfo); 460 else if (CMId == Builtin::BIstrncat) 461 CheckStrncatArguments(TheCall, FnInfo); 462 else 463 CheckMemaccessArguments(TheCall, CMId, FnInfo); 464 465 return false; 466} 467 468bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac, 469 Expr **Args, unsigned NumArgs) { 470 for (specific_attr_iterator<FormatAttr> 471 i = Method->specific_attr_begin<FormatAttr>(), 472 e = Method->specific_attr_end<FormatAttr>(); i != e ; ++i) { 473 474 CheckFormatArguments(*i, Args, NumArgs, false, lbrac, 475 Method->getSourceRange()); 476 } 477 478 // diagnose nonnull arguments. 479 for (specific_attr_iterator<NonNullAttr> 480 i = Method->specific_attr_begin<NonNullAttr>(), 481 e = Method->specific_attr_end<NonNullAttr>(); i != e; ++i) { 482 CheckNonNullArguments(*i, Args, lbrac); 483 } 484 485 return false; 486} 487 488bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 489 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 490 if (!V) 491 return false; 492 493 QualType Ty = V->getType(); 494 if (!Ty->isBlockPointerType()) 495 return false; 496 497 // format string checking. 498 for (specific_attr_iterator<FormatAttr> 499 i = NDecl->specific_attr_begin<FormatAttr>(), 500 e = NDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { 501 CheckFormatArguments(*i, TheCall); 502 } 503 504 return false; 505} 506 507ExprResult 508Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, AtomicExpr::AtomicOp Op) { 509 CallExpr *TheCall = cast<CallExpr>(TheCallResult.get()); 510 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 511 512 // All these operations take one of the following four forms: 513 // T __atomic_load(_Atomic(T)*, int) (loads) 514 // T* __atomic_add(_Atomic(T*)*, ptrdiff_t, int) (pointer add/sub) 515 // int __atomic_compare_exchange_strong(_Atomic(T)*, T*, T, int, int) 516 // (cmpxchg) 517 // T __atomic_exchange(_Atomic(T)*, T, int) (everything else) 518 // where T is an appropriate type, and the int paremeterss are for orderings. 519 unsigned NumVals = 1; 520 unsigned NumOrders = 1; 521 if (Op == AtomicExpr::Load) { 522 NumVals = 0; 523 } else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong) { 524 NumVals = 2; 525 NumOrders = 2; 526 } 527 if (Op == AtomicExpr::Init) 528 NumOrders = 0; 529 530 if (TheCall->getNumArgs() < NumVals+NumOrders+1) { 531 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 532 << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs() 533 << TheCall->getCallee()->getSourceRange(); 534 return ExprError(); 535 } else if (TheCall->getNumArgs() > NumVals+NumOrders+1) { 536 Diag(TheCall->getArg(NumVals+NumOrders+1)->getLocStart(), 537 diag::err_typecheck_call_too_many_args) 538 << 0 << NumVals+NumOrders+1 << TheCall->getNumArgs() 539 << TheCall->getCallee()->getSourceRange(); 540 return ExprError(); 541 } 542 543 // Inspect the first argument of the atomic operation. This should always be 544 // a pointer to an _Atomic type. 545 Expr *Ptr = TheCall->getArg(0); 546 Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get(); 547 const PointerType *pointerType = Ptr->getType()->getAs<PointerType>(); 548 if (!pointerType) { 549 Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic) 550 << Ptr->getType() << Ptr->getSourceRange(); 551 return ExprError(); 552 } 553 554 QualType AtomTy = pointerType->getPointeeType(); 555 if (!AtomTy->isAtomicType()) { 556 Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic) 557 << Ptr->getType() << Ptr->getSourceRange(); 558 return ExprError(); 559 } 560 QualType ValType = AtomTy->getAs<AtomicType>()->getValueType(); 561 562 if ((Op == AtomicExpr::Add || Op == AtomicExpr::Sub) && 563 !ValType->isIntegerType() && !ValType->isPointerType()) { 564 Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr) 565 << Ptr->getType() << Ptr->getSourceRange(); 566 return ExprError(); 567 } 568 569 if (!ValType->isIntegerType() && 570 (Op == AtomicExpr::And || Op == AtomicExpr::Or || Op == AtomicExpr::Xor)){ 571 Diag(DRE->getLocStart(), diag::err_atomic_op_logical_needs_atomic_int) 572 << Ptr->getType() << Ptr->getSourceRange(); 573 return ExprError(); 574 } 575 576 switch (ValType.getObjCLifetime()) { 577 case Qualifiers::OCL_None: 578 case Qualifiers::OCL_ExplicitNone: 579 // okay 580 break; 581 582 case Qualifiers::OCL_Weak: 583 case Qualifiers::OCL_Strong: 584 case Qualifiers::OCL_Autoreleasing: 585 Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership) 586 << ValType << Ptr->getSourceRange(); 587 return ExprError(); 588 } 589 590 QualType ResultType = ValType; 591 if (Op == AtomicExpr::Store || Op == AtomicExpr::Init) 592 ResultType = Context.VoidTy; 593 else if (Op == AtomicExpr::CmpXchgWeak || Op == AtomicExpr::CmpXchgStrong) 594 ResultType = Context.BoolTy; 595 596 // The first argument --- the pointer --- has a fixed type; we 597 // deduce the types of the rest of the arguments accordingly. Walk 598 // the remaining arguments, converting them to the deduced value type. 599 for (unsigned i = 1; i != NumVals+NumOrders+1; ++i) { 600 ExprResult Arg = TheCall->getArg(i); 601 QualType Ty; 602 if (i < NumVals+1) { 603 // The second argument to a cmpxchg is a pointer to the data which will 604 // be exchanged. The second argument to a pointer add/subtract is the 605 // amount to add/subtract, which must be a ptrdiff_t. The third 606 // argument to a cmpxchg and the second argument in all other cases 607 // is the type of the value. 608 if (i == 1 && (Op == AtomicExpr::CmpXchgWeak || 609 Op == AtomicExpr::CmpXchgStrong)) 610 Ty = Context.getPointerType(ValType.getUnqualifiedType()); 611 else if (!ValType->isIntegerType() && 612 (Op == AtomicExpr::Add || Op == AtomicExpr::Sub)) 613 Ty = Context.getPointerDiffType(); 614 else 615 Ty = ValType; 616 } else { 617 // The order(s) are always converted to int. 618 Ty = Context.IntTy; 619 } 620 InitializedEntity Entity = 621 InitializedEntity::InitializeParameter(Context, Ty, false); 622 Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg); 623 if (Arg.isInvalid()) 624 return true; 625 TheCall->setArg(i, Arg.get()); 626 } 627 628 SmallVector<Expr*, 5> SubExprs; 629 SubExprs.push_back(Ptr); 630 if (Op == AtomicExpr::Load) { 631 SubExprs.push_back(TheCall->getArg(1)); // Order 632 } else if (Op == AtomicExpr::Init) { 633 SubExprs.push_back(TheCall->getArg(1)); // Val1 634 } else if (Op != AtomicExpr::CmpXchgWeak && Op != AtomicExpr::CmpXchgStrong) { 635 SubExprs.push_back(TheCall->getArg(2)); // Order 636 SubExprs.push_back(TheCall->getArg(1)); // Val1 637 } else { 638 SubExprs.push_back(TheCall->getArg(3)); // Order 639 SubExprs.push_back(TheCall->getArg(1)); // Val1 640 SubExprs.push_back(TheCall->getArg(2)); // Val2 641 SubExprs.push_back(TheCall->getArg(4)); // OrderFail 642 } 643 644 return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(), 645 SubExprs.data(), SubExprs.size(), 646 ResultType, Op, 647 TheCall->getRParenLoc())); 648} 649 650 651/// checkBuiltinArgument - Given a call to a builtin function, perform 652/// normal type-checking on the given argument, updating the call in 653/// place. This is useful when a builtin function requires custom 654/// type-checking for some of its arguments but not necessarily all of 655/// them. 656/// 657/// Returns true on error. 658static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) { 659 FunctionDecl *Fn = E->getDirectCallee(); 660 assert(Fn && "builtin call without direct callee!"); 661 662 ParmVarDecl *Param = Fn->getParamDecl(ArgIndex); 663 InitializedEntity Entity = 664 InitializedEntity::InitializeParameter(S.Context, Param); 665 666 ExprResult Arg = E->getArg(0); 667 Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg); 668 if (Arg.isInvalid()) 669 return true; 670 671 E->setArg(ArgIndex, Arg.take()); 672 return false; 673} 674 675/// SemaBuiltinAtomicOverloaded - We have a call to a function like 676/// __sync_fetch_and_add, which is an overloaded function based on the pointer 677/// type of its first argument. The main ActOnCallExpr routines have already 678/// promoted the types of arguments because all of these calls are prototyped as 679/// void(...). 680/// 681/// This function goes through and does final semantic checking for these 682/// builtins, 683ExprResult 684Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { 685 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 686 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 687 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 688 689 // Ensure that we have at least one argument to do type inference from. 690 if (TheCall->getNumArgs() < 1) { 691 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 692 << 0 << 1 << TheCall->getNumArgs() 693 << TheCall->getCallee()->getSourceRange(); 694 return ExprError(); 695 } 696 697 // Inspect the first argument of the atomic builtin. This should always be 698 // a pointer type, whose element is an integral scalar or pointer type. 699 // Because it is a pointer type, we don't have to worry about any implicit 700 // casts here. 701 // FIXME: We don't allow floating point scalars as input. 702 Expr *FirstArg = TheCall->getArg(0); 703 ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg); 704 if (FirstArgResult.isInvalid()) 705 return ExprError(); 706 FirstArg = FirstArgResult.take(); 707 TheCall->setArg(0, FirstArg); 708 709 const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>(); 710 if (!pointerType) { 711 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 712 << FirstArg->getType() << FirstArg->getSourceRange(); 713 return ExprError(); 714 } 715 716 QualType ValType = pointerType->getPointeeType(); 717 if (!ValType->isIntegerType() && !ValType->isAnyPointerType() && 718 !ValType->isBlockPointerType()) { 719 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 720 << FirstArg->getType() << FirstArg->getSourceRange(); 721 return ExprError(); 722 } 723 724 switch (ValType.getObjCLifetime()) { 725 case Qualifiers::OCL_None: 726 case Qualifiers::OCL_ExplicitNone: 727 // okay 728 break; 729 730 case Qualifiers::OCL_Weak: 731 case Qualifiers::OCL_Strong: 732 case Qualifiers::OCL_Autoreleasing: 733 Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership) 734 << ValType << FirstArg->getSourceRange(); 735 return ExprError(); 736 } 737 738 // Strip any qualifiers off ValType. 739 ValType = ValType.getUnqualifiedType(); 740 741 // The majority of builtins return a value, but a few have special return 742 // types, so allow them to override appropriately below. 743 QualType ResultType = ValType; 744 745 // We need to figure out which concrete builtin this maps onto. For example, 746 // __sync_fetch_and_add with a 2 byte object turns into 747 // __sync_fetch_and_add_2. 748#define BUILTIN_ROW(x) \ 749 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 750 Builtin::BI##x##_8, Builtin::BI##x##_16 } 751 752 static const unsigned BuiltinIndices[][5] = { 753 BUILTIN_ROW(__sync_fetch_and_add), 754 BUILTIN_ROW(__sync_fetch_and_sub), 755 BUILTIN_ROW(__sync_fetch_and_or), 756 BUILTIN_ROW(__sync_fetch_and_and), 757 BUILTIN_ROW(__sync_fetch_and_xor), 758 759 BUILTIN_ROW(__sync_add_and_fetch), 760 BUILTIN_ROW(__sync_sub_and_fetch), 761 BUILTIN_ROW(__sync_and_and_fetch), 762 BUILTIN_ROW(__sync_or_and_fetch), 763 BUILTIN_ROW(__sync_xor_and_fetch), 764 765 BUILTIN_ROW(__sync_val_compare_and_swap), 766 BUILTIN_ROW(__sync_bool_compare_and_swap), 767 BUILTIN_ROW(__sync_lock_test_and_set), 768 BUILTIN_ROW(__sync_lock_release), 769 BUILTIN_ROW(__sync_swap) 770 }; 771#undef BUILTIN_ROW 772 773 // Determine the index of the size. 774 unsigned SizeIndex; 775 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 776 case 1: SizeIndex = 0; break; 777 case 2: SizeIndex = 1; break; 778 case 4: SizeIndex = 2; break; 779 case 8: SizeIndex = 3; break; 780 case 16: SizeIndex = 4; break; 781 default: 782 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 783 << FirstArg->getType() << FirstArg->getSourceRange(); 784 return ExprError(); 785 } 786 787 // Each of these builtins has one pointer argument, followed by some number of 788 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 789 // that we ignore. Find out which row of BuiltinIndices to read from as well 790 // as the number of fixed args. 791 unsigned BuiltinID = FDecl->getBuiltinID(); 792 unsigned BuiltinIndex, NumFixed = 1; 793 switch (BuiltinID) { 794 default: llvm_unreachable("Unknown overloaded atomic builtin!"); 795 case Builtin::BI__sync_fetch_and_add: 796 case Builtin::BI__sync_fetch_and_add_1: 797 case Builtin::BI__sync_fetch_and_add_2: 798 case Builtin::BI__sync_fetch_and_add_4: 799 case Builtin::BI__sync_fetch_and_add_8: 800 case Builtin::BI__sync_fetch_and_add_16: 801 BuiltinIndex = 0; 802 break; 803 804 case Builtin::BI__sync_fetch_and_sub: 805 case Builtin::BI__sync_fetch_and_sub_1: 806 case Builtin::BI__sync_fetch_and_sub_2: 807 case Builtin::BI__sync_fetch_and_sub_4: 808 case Builtin::BI__sync_fetch_and_sub_8: 809 case Builtin::BI__sync_fetch_and_sub_16: 810 BuiltinIndex = 1; 811 break; 812 813 case Builtin::BI__sync_fetch_and_or: 814 case Builtin::BI__sync_fetch_and_or_1: 815 case Builtin::BI__sync_fetch_and_or_2: 816 case Builtin::BI__sync_fetch_and_or_4: 817 case Builtin::BI__sync_fetch_and_or_8: 818 case Builtin::BI__sync_fetch_and_or_16: 819 BuiltinIndex = 2; 820 break; 821 822 case Builtin::BI__sync_fetch_and_and: 823 case Builtin::BI__sync_fetch_and_and_1: 824 case Builtin::BI__sync_fetch_and_and_2: 825 case Builtin::BI__sync_fetch_and_and_4: 826 case Builtin::BI__sync_fetch_and_and_8: 827 case Builtin::BI__sync_fetch_and_and_16: 828 BuiltinIndex = 3; 829 break; 830 831 case Builtin::BI__sync_fetch_and_xor: 832 case Builtin::BI__sync_fetch_and_xor_1: 833 case Builtin::BI__sync_fetch_and_xor_2: 834 case Builtin::BI__sync_fetch_and_xor_4: 835 case Builtin::BI__sync_fetch_and_xor_8: 836 case Builtin::BI__sync_fetch_and_xor_16: 837 BuiltinIndex = 4; 838 break; 839 840 case Builtin::BI__sync_add_and_fetch: 841 case Builtin::BI__sync_add_and_fetch_1: 842 case Builtin::BI__sync_add_and_fetch_2: 843 case Builtin::BI__sync_add_and_fetch_4: 844 case Builtin::BI__sync_add_and_fetch_8: 845 case Builtin::BI__sync_add_and_fetch_16: 846 BuiltinIndex = 5; 847 break; 848 849 case Builtin::BI__sync_sub_and_fetch: 850 case Builtin::BI__sync_sub_and_fetch_1: 851 case Builtin::BI__sync_sub_and_fetch_2: 852 case Builtin::BI__sync_sub_and_fetch_4: 853 case Builtin::BI__sync_sub_and_fetch_8: 854 case Builtin::BI__sync_sub_and_fetch_16: 855 BuiltinIndex = 6; 856 break; 857 858 case Builtin::BI__sync_and_and_fetch: 859 case Builtin::BI__sync_and_and_fetch_1: 860 case Builtin::BI__sync_and_and_fetch_2: 861 case Builtin::BI__sync_and_and_fetch_4: 862 case Builtin::BI__sync_and_and_fetch_8: 863 case Builtin::BI__sync_and_and_fetch_16: 864 BuiltinIndex = 7; 865 break; 866 867 case Builtin::BI__sync_or_and_fetch: 868 case Builtin::BI__sync_or_and_fetch_1: 869 case Builtin::BI__sync_or_and_fetch_2: 870 case Builtin::BI__sync_or_and_fetch_4: 871 case Builtin::BI__sync_or_and_fetch_8: 872 case Builtin::BI__sync_or_and_fetch_16: 873 BuiltinIndex = 8; 874 break; 875 876 case Builtin::BI__sync_xor_and_fetch: 877 case Builtin::BI__sync_xor_and_fetch_1: 878 case Builtin::BI__sync_xor_and_fetch_2: 879 case Builtin::BI__sync_xor_and_fetch_4: 880 case Builtin::BI__sync_xor_and_fetch_8: 881 case Builtin::BI__sync_xor_and_fetch_16: 882 BuiltinIndex = 9; 883 break; 884 885 case Builtin::BI__sync_val_compare_and_swap: 886 case Builtin::BI__sync_val_compare_and_swap_1: 887 case Builtin::BI__sync_val_compare_and_swap_2: 888 case Builtin::BI__sync_val_compare_and_swap_4: 889 case Builtin::BI__sync_val_compare_and_swap_8: 890 case Builtin::BI__sync_val_compare_and_swap_16: 891 BuiltinIndex = 10; 892 NumFixed = 2; 893 break; 894 895 case Builtin::BI__sync_bool_compare_and_swap: 896 case Builtin::BI__sync_bool_compare_and_swap_1: 897 case Builtin::BI__sync_bool_compare_and_swap_2: 898 case Builtin::BI__sync_bool_compare_and_swap_4: 899 case Builtin::BI__sync_bool_compare_and_swap_8: 900 case Builtin::BI__sync_bool_compare_and_swap_16: 901 BuiltinIndex = 11; 902 NumFixed = 2; 903 ResultType = Context.BoolTy; 904 break; 905 906 case Builtin::BI__sync_lock_test_and_set: 907 case Builtin::BI__sync_lock_test_and_set_1: 908 case Builtin::BI__sync_lock_test_and_set_2: 909 case Builtin::BI__sync_lock_test_and_set_4: 910 case Builtin::BI__sync_lock_test_and_set_8: 911 case Builtin::BI__sync_lock_test_and_set_16: 912 BuiltinIndex = 12; 913 break; 914 915 case Builtin::BI__sync_lock_release: 916 case Builtin::BI__sync_lock_release_1: 917 case Builtin::BI__sync_lock_release_2: 918 case Builtin::BI__sync_lock_release_4: 919 case Builtin::BI__sync_lock_release_8: 920 case Builtin::BI__sync_lock_release_16: 921 BuiltinIndex = 13; 922 NumFixed = 0; 923 ResultType = Context.VoidTy; 924 break; 925 926 case Builtin::BI__sync_swap: 927 case Builtin::BI__sync_swap_1: 928 case Builtin::BI__sync_swap_2: 929 case Builtin::BI__sync_swap_4: 930 case Builtin::BI__sync_swap_8: 931 case Builtin::BI__sync_swap_16: 932 BuiltinIndex = 14; 933 break; 934 } 935 936 // Now that we know how many fixed arguments we expect, first check that we 937 // have at least that many. 938 if (TheCall->getNumArgs() < 1+NumFixed) { 939 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 940 << 0 << 1+NumFixed << TheCall->getNumArgs() 941 << TheCall->getCallee()->getSourceRange(); 942 return ExprError(); 943 } 944 945 // Get the decl for the concrete builtin from this, we can tell what the 946 // concrete integer type we should convert to is. 947 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 948 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 949 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 950 FunctionDecl *NewBuiltinDecl = 951 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 952 TUScope, false, DRE->getLocStart())); 953 954 // The first argument --- the pointer --- has a fixed type; we 955 // deduce the types of the rest of the arguments accordingly. Walk 956 // the remaining arguments, converting them to the deduced value type. 957 for (unsigned i = 0; i != NumFixed; ++i) { 958 ExprResult Arg = TheCall->getArg(i+1); 959 960 // GCC does an implicit conversion to the pointer or integer ValType. This 961 // can fail in some cases (1i -> int**), check for this error case now. 962 // Initialize the argument. 963 InitializedEntity Entity = InitializedEntity::InitializeParameter(Context, 964 ValType, /*consume*/ false); 965 Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg); 966 if (Arg.isInvalid()) 967 return ExprError(); 968 969 // Okay, we have something that *can* be converted to the right type. Check 970 // to see if there is a potentially weird extension going on here. This can 971 // happen when you do an atomic operation on something like an char* and 972 // pass in 42. The 42 gets converted to char. This is even more strange 973 // for things like 45.123 -> char, etc. 974 // FIXME: Do this check. 975 TheCall->setArg(i+1, Arg.take()); 976 } 977 978 ASTContext& Context = this->getASTContext(); 979 980 // Create a new DeclRefExpr to refer to the new decl. 981 DeclRefExpr* NewDRE = DeclRefExpr::Create( 982 Context, 983 DRE->getQualifierLoc(), 984 SourceLocation(), 985 NewBuiltinDecl, 986 DRE->getLocation(), 987 NewBuiltinDecl->getType(), 988 DRE->getValueKind()); 989 990 // Set the callee in the CallExpr. 991 // FIXME: This leaks the original parens and implicit casts. 992 ExprResult PromotedCall = UsualUnaryConversions(NewDRE); 993 if (PromotedCall.isInvalid()) 994 return ExprError(); 995 TheCall->setCallee(PromotedCall.take()); 996 997 // Change the result type of the call to match the original value type. This 998 // is arbitrary, but the codegen for these builtins ins design to handle it 999 // gracefully. 1000 TheCall->setType(ResultType); 1001 1002 return move(TheCallResult); 1003} 1004 1005/// CheckObjCString - Checks that the argument to the builtin 1006/// CFString constructor is correct 1007/// Note: It might also make sense to do the UTF-16 conversion here (would 1008/// simplify the backend). 1009bool Sema::CheckObjCString(Expr *Arg) { 1010 Arg = Arg->IgnoreParenCasts(); 1011 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 1012 1013 if (!Literal || !Literal->isAscii()) { 1014 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 1015 << Arg->getSourceRange(); 1016 return true; 1017 } 1018 1019 if (Literal->containsNonAsciiOrNull()) { 1020 StringRef String = Literal->getString(); 1021 unsigned NumBytes = String.size(); 1022 SmallVector<UTF16, 128> ToBuf(NumBytes); 1023 const UTF8 *FromPtr = (UTF8 *)String.data(); 1024 UTF16 *ToPtr = &ToBuf[0]; 1025 1026 ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, 1027 &ToPtr, ToPtr + NumBytes, 1028 strictConversion); 1029 // Check for conversion failure. 1030 if (Result != conversionOK) 1031 Diag(Arg->getLocStart(), 1032 diag::warn_cfstring_truncated) << Arg->getSourceRange(); 1033 } 1034 return false; 1035} 1036 1037/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 1038/// Emit an error and return true on failure, return false on success. 1039bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 1040 Expr *Fn = TheCall->getCallee(); 1041 if (TheCall->getNumArgs() > 2) { 1042 Diag(TheCall->getArg(2)->getLocStart(), 1043 diag::err_typecheck_call_too_many_args) 1044 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 1045 << Fn->getSourceRange() 1046 << SourceRange(TheCall->getArg(2)->getLocStart(), 1047 (*(TheCall->arg_end()-1))->getLocEnd()); 1048 return true; 1049 } 1050 1051 if (TheCall->getNumArgs() < 2) { 1052 return Diag(TheCall->getLocEnd(), 1053 diag::err_typecheck_call_too_few_args_at_least) 1054 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 1055 } 1056 1057 // Type-check the first argument normally. 1058 if (checkBuiltinArgument(*this, TheCall, 0)) 1059 return true; 1060 1061 // Determine whether the current function is variadic or not. 1062 BlockScopeInfo *CurBlock = getCurBlock(); 1063 bool isVariadic; 1064 if (CurBlock) 1065 isVariadic = CurBlock->TheDecl->isVariadic(); 1066 else if (FunctionDecl *FD = getCurFunctionDecl()) 1067 isVariadic = FD->isVariadic(); 1068 else 1069 isVariadic = getCurMethodDecl()->isVariadic(); 1070 1071 if (!isVariadic) { 1072 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 1073 return true; 1074 } 1075 1076 // Verify that the second argument to the builtin is the last argument of the 1077 // current function or method. 1078 bool SecondArgIsLastNamedArgument = false; 1079 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 1080 1081 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 1082 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 1083 // FIXME: This isn't correct for methods (results in bogus warning). 1084 // Get the last formal in the current function. 1085 const ParmVarDecl *LastArg; 1086 if (CurBlock) 1087 LastArg = *(CurBlock->TheDecl->param_end()-1); 1088 else if (FunctionDecl *FD = getCurFunctionDecl()) 1089 LastArg = *(FD->param_end()-1); 1090 else 1091 LastArg = *(getCurMethodDecl()->param_end()-1); 1092 SecondArgIsLastNamedArgument = PV == LastArg; 1093 } 1094 } 1095 1096 if (!SecondArgIsLastNamedArgument) 1097 Diag(TheCall->getArg(1)->getLocStart(), 1098 diag::warn_second_parameter_of_va_start_not_last_named_argument); 1099 return false; 1100} 1101 1102/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 1103/// friends. This is declared to take (...), so we have to check everything. 1104bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 1105 if (TheCall->getNumArgs() < 2) 1106 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 1107 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 1108 if (TheCall->getNumArgs() > 2) 1109 return Diag(TheCall->getArg(2)->getLocStart(), 1110 diag::err_typecheck_call_too_many_args) 1111 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 1112 << SourceRange(TheCall->getArg(2)->getLocStart(), 1113 (*(TheCall->arg_end()-1))->getLocEnd()); 1114 1115 ExprResult OrigArg0 = TheCall->getArg(0); 1116 ExprResult OrigArg1 = TheCall->getArg(1); 1117 1118 // Do standard promotions between the two arguments, returning their common 1119 // type. 1120 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 1121 if (OrigArg0.isInvalid() || OrigArg1.isInvalid()) 1122 return true; 1123 1124 // Make sure any conversions are pushed back into the call; this is 1125 // type safe since unordered compare builtins are declared as "_Bool 1126 // foo(...)". 1127 TheCall->setArg(0, OrigArg0.get()); 1128 TheCall->setArg(1, OrigArg1.get()); 1129 1130 if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent()) 1131 return false; 1132 1133 // If the common type isn't a real floating type, then the arguments were 1134 // invalid for this operation. 1135 if (!Res->isRealFloatingType()) 1136 return Diag(OrigArg0.get()->getLocStart(), 1137 diag::err_typecheck_call_invalid_ordered_compare) 1138 << OrigArg0.get()->getType() << OrigArg1.get()->getType() 1139 << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd()); 1140 1141 return false; 1142} 1143 1144/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 1145/// __builtin_isnan and friends. This is declared to take (...), so we have 1146/// to check everything. We expect the last argument to be a floating point 1147/// value. 1148bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 1149 if (TheCall->getNumArgs() < NumArgs) 1150 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 1151 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 1152 if (TheCall->getNumArgs() > NumArgs) 1153 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 1154 diag::err_typecheck_call_too_many_args) 1155 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 1156 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 1157 (*(TheCall->arg_end()-1))->getLocEnd()); 1158 1159 Expr *OrigArg = TheCall->getArg(NumArgs-1); 1160 1161 if (OrigArg->isTypeDependent()) 1162 return false; 1163 1164 // This operation requires a non-_Complex floating-point number. 1165 if (!OrigArg->getType()->isRealFloatingType()) 1166 return Diag(OrigArg->getLocStart(), 1167 diag::err_typecheck_call_invalid_unary_fp) 1168 << OrigArg->getType() << OrigArg->getSourceRange(); 1169 1170 // If this is an implicit conversion from float -> double, remove it. 1171 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 1172 Expr *CastArg = Cast->getSubExpr(); 1173 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 1174 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 1175 "promotion from float to double is the only expected cast here"); 1176 Cast->setSubExpr(0); 1177 TheCall->setArg(NumArgs-1, CastArg); 1178 OrigArg = CastArg; 1179 } 1180 } 1181 1182 return false; 1183} 1184 1185/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 1186// This is declared to take (...), so we have to check everything. 1187ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 1188 if (TheCall->getNumArgs() < 2) 1189 return ExprError(Diag(TheCall->getLocEnd(), 1190 diag::err_typecheck_call_too_few_args_at_least) 1191 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 1192 << TheCall->getSourceRange()); 1193 1194 // Determine which of the following types of shufflevector we're checking: 1195 // 1) unary, vector mask: (lhs, mask) 1196 // 2) binary, vector mask: (lhs, rhs, mask) 1197 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 1198 QualType resType = TheCall->getArg(0)->getType(); 1199 unsigned numElements = 0; 1200 1201 if (!TheCall->getArg(0)->isTypeDependent() && 1202 !TheCall->getArg(1)->isTypeDependent()) { 1203 QualType LHSType = TheCall->getArg(0)->getType(); 1204 QualType RHSType = TheCall->getArg(1)->getType(); 1205 1206 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 1207 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 1208 << SourceRange(TheCall->getArg(0)->getLocStart(), 1209 TheCall->getArg(1)->getLocEnd()); 1210 return ExprError(); 1211 } 1212 1213 numElements = LHSType->getAs<VectorType>()->getNumElements(); 1214 unsigned numResElements = TheCall->getNumArgs() - 2; 1215 1216 // Check to see if we have a call with 2 vector arguments, the unary shuffle 1217 // with mask. If so, verify that RHS is an integer vector type with the 1218 // same number of elts as lhs. 1219 if (TheCall->getNumArgs() == 2) { 1220 if (!RHSType->hasIntegerRepresentation() || 1221 RHSType->getAs<VectorType>()->getNumElements() != numElements) 1222 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 1223 << SourceRange(TheCall->getArg(1)->getLocStart(), 1224 TheCall->getArg(1)->getLocEnd()); 1225 numResElements = numElements; 1226 } 1227 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 1228 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 1229 << SourceRange(TheCall->getArg(0)->getLocStart(), 1230 TheCall->getArg(1)->getLocEnd()); 1231 return ExprError(); 1232 } else if (numElements != numResElements) { 1233 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 1234 resType = Context.getVectorType(eltType, numResElements, 1235 VectorType::GenericVector); 1236 } 1237 } 1238 1239 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 1240 if (TheCall->getArg(i)->isTypeDependent() || 1241 TheCall->getArg(i)->isValueDependent()) 1242 continue; 1243 1244 llvm::APSInt Result(32); 1245 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 1246 return ExprError(Diag(TheCall->getLocStart(), 1247 diag::err_shufflevector_nonconstant_argument) 1248 << TheCall->getArg(i)->getSourceRange()); 1249 1250 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 1251 return ExprError(Diag(TheCall->getLocStart(), 1252 diag::err_shufflevector_argument_too_large) 1253 << TheCall->getArg(i)->getSourceRange()); 1254 } 1255 1256 SmallVector<Expr*, 32> exprs; 1257 1258 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 1259 exprs.push_back(TheCall->getArg(i)); 1260 TheCall->setArg(i, 0); 1261 } 1262 1263 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 1264 exprs.size(), resType, 1265 TheCall->getCallee()->getLocStart(), 1266 TheCall->getRParenLoc())); 1267} 1268 1269/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 1270// This is declared to take (const void*, ...) and can take two 1271// optional constant int args. 1272bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 1273 unsigned NumArgs = TheCall->getNumArgs(); 1274 1275 if (NumArgs > 3) 1276 return Diag(TheCall->getLocEnd(), 1277 diag::err_typecheck_call_too_many_args_at_most) 1278 << 0 /*function call*/ << 3 << NumArgs 1279 << TheCall->getSourceRange(); 1280 1281 // Argument 0 is checked for us and the remaining arguments must be 1282 // constant integers. 1283 for (unsigned i = 1; i != NumArgs; ++i) { 1284 Expr *Arg = TheCall->getArg(i); 1285 1286 llvm::APSInt Result; 1287 if (SemaBuiltinConstantArg(TheCall, i, Result)) 1288 return true; 1289 1290 // FIXME: gcc issues a warning and rewrites these to 0. These 1291 // seems especially odd for the third argument since the default 1292 // is 3. 1293 if (i == 1) { 1294 if (Result.getLimitedValue() > 1) 1295 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 1296 << "0" << "1" << Arg->getSourceRange(); 1297 } else { 1298 if (Result.getLimitedValue() > 3) 1299 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 1300 << "0" << "3" << Arg->getSourceRange(); 1301 } 1302 } 1303 1304 return false; 1305} 1306 1307/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 1308/// TheCall is a constant expression. 1309bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 1310 llvm::APSInt &Result) { 1311 Expr *Arg = TheCall->getArg(ArgNum); 1312 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 1313 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 1314 1315 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 1316 1317 if (!Arg->isIntegerConstantExpr(Result, Context)) 1318 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 1319 << FDecl->getDeclName() << Arg->getSourceRange(); 1320 1321 return false; 1322} 1323 1324/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 1325/// int type). This simply type checks that type is one of the defined 1326/// constants (0-3). 1327// For compatibility check 0-3, llvm only handles 0 and 2. 1328bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 1329 llvm::APSInt Result; 1330 1331 // Check constant-ness first. 1332 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 1333 return true; 1334 1335 Expr *Arg = TheCall->getArg(1); 1336 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 1337 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 1338 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 1339 } 1340 1341 return false; 1342} 1343 1344/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 1345/// This checks that val is a constant 1. 1346bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 1347 Expr *Arg = TheCall->getArg(1); 1348 llvm::APSInt Result; 1349 1350 // TODO: This is less than ideal. Overload this to take a value. 1351 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 1352 return true; 1353 1354 if (Result != 1) 1355 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 1356 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 1357 1358 return false; 1359} 1360 1361// Handle i > 1 ? "x" : "y", recursively. 1362bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args, 1363 unsigned NumArgs, bool HasVAListArg, 1364 unsigned format_idx, unsigned firstDataArg, 1365 FormatStringType Type, bool inFunctionCall) { 1366 tryAgain: 1367 if (E->isTypeDependent() || E->isValueDependent()) 1368 return false; 1369 1370 E = E->IgnoreParenCasts(); 1371 1372 if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull)) 1373 // Technically -Wformat-nonliteral does not warn about this case. 1374 // The behavior of printf and friends in this case is implementation 1375 // dependent. Ideally if the format string cannot be null then 1376 // it should have a 'nonnull' attribute in the function prototype. 1377 return true; 1378 1379 switch (E->getStmtClass()) { 1380 case Stmt::BinaryConditionalOperatorClass: 1381 case Stmt::ConditionalOperatorClass: { 1382 const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); 1383 return SemaCheckStringLiteral(C->getTrueExpr(), Args, NumArgs, HasVAListArg, 1384 format_idx, firstDataArg, Type, 1385 inFunctionCall) 1386 && SemaCheckStringLiteral(C->getFalseExpr(), Args, NumArgs, HasVAListArg, 1387 format_idx, firstDataArg, Type, 1388 inFunctionCall); 1389 } 1390 1391 case Stmt::ImplicitCastExprClass: { 1392 E = cast<ImplicitCastExpr>(E)->getSubExpr(); 1393 goto tryAgain; 1394 } 1395 1396 case Stmt::OpaqueValueExprClass: 1397 if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { 1398 E = src; 1399 goto tryAgain; 1400 } 1401 return false; 1402 1403 case Stmt::PredefinedExprClass: 1404 // While __func__, etc., are technically not string literals, they 1405 // cannot contain format specifiers and thus are not a security 1406 // liability. 1407 return true; 1408 1409 case Stmt::DeclRefExprClass: { 1410 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 1411 1412 // As an exception, do not flag errors for variables binding to 1413 // const string literals. 1414 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 1415 bool isConstant = false; 1416 QualType T = DR->getType(); 1417 1418 if (const ArrayType *AT = Context.getAsArrayType(T)) { 1419 isConstant = AT->getElementType().isConstant(Context); 1420 } else if (const PointerType *PT = T->getAs<PointerType>()) { 1421 isConstant = T.isConstant(Context) && 1422 PT->getPointeeType().isConstant(Context); 1423 } else if (T->isObjCObjectPointerType()) { 1424 // In ObjC, there is usually no "const ObjectPointer" type, 1425 // so don't check if the pointee type is constant. 1426 isConstant = T.isConstant(Context); 1427 } 1428 1429 if (isConstant) { 1430 if (const Expr *Init = VD->getAnyInitializer()) 1431 return SemaCheckStringLiteral(Init, Args, NumArgs, 1432 HasVAListArg, format_idx, firstDataArg, 1433 Type, /*inFunctionCall*/false); 1434 } 1435 1436 // For vprintf* functions (i.e., HasVAListArg==true), we add a 1437 // special check to see if the format string is a function parameter 1438 // of the function calling the printf function. If the function 1439 // has an attribute indicating it is a printf-like function, then we 1440 // should suppress warnings concerning non-literals being used in a call 1441 // to a vprintf function. For example: 1442 // 1443 // void 1444 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 1445 // va_list ap; 1446 // va_start(ap, fmt); 1447 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 1448 // ... 1449 // 1450 if (HasVAListArg) { 1451 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) { 1452 if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) { 1453 int PVIndex = PV->getFunctionScopeIndex() + 1; 1454 for (specific_attr_iterator<FormatAttr> 1455 i = ND->specific_attr_begin<FormatAttr>(), 1456 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) { 1457 FormatAttr *PVFormat = *i; 1458 // adjust for implicit parameter 1459 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND)) 1460 if (MD->isInstance()) 1461 ++PVIndex; 1462 // We also check if the formats are compatible. 1463 // We can't pass a 'scanf' string to a 'printf' function. 1464 if (PVIndex == PVFormat->getFormatIdx() && 1465 Type == GetFormatStringType(PVFormat)) 1466 return true; 1467 } 1468 } 1469 } 1470 } 1471 } 1472 1473 return false; 1474 } 1475 1476 case Stmt::CallExprClass: 1477 case Stmt::CXXMemberCallExprClass: { 1478 const CallExpr *CE = cast<CallExpr>(E); 1479 if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) { 1480 if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) { 1481 unsigned ArgIndex = FA->getFormatIdx(); 1482 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND)) 1483 if (MD->isInstance()) 1484 --ArgIndex; 1485 const Expr *Arg = CE->getArg(ArgIndex - 1); 1486 1487 return SemaCheckStringLiteral(Arg, Args, NumArgs, HasVAListArg, 1488 format_idx, firstDataArg, Type, 1489 inFunctionCall); 1490 } 1491 } 1492 1493 return false; 1494 } 1495 case Stmt::ObjCStringLiteralClass: 1496 case Stmt::StringLiteralClass: { 1497 const StringLiteral *StrE = NULL; 1498 1499 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1500 StrE = ObjCFExpr->getString(); 1501 else 1502 StrE = cast<StringLiteral>(E); 1503 1504 if (StrE) { 1505 CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx, 1506 firstDataArg, Type, inFunctionCall); 1507 return true; 1508 } 1509 1510 return false; 1511 } 1512 1513 default: 1514 return false; 1515 } 1516} 1517 1518void 1519Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1520 const Expr * const *ExprArgs, 1521 SourceLocation CallSiteLoc) { 1522 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1523 e = NonNull->args_end(); 1524 i != e; ++i) { 1525 const Expr *ArgExpr = ExprArgs[*i]; 1526 if (ArgExpr->isNullPointerConstant(Context, 1527 Expr::NPC_ValueDependentIsNotNull)) 1528 Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange(); 1529 } 1530} 1531 1532Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) { 1533 return llvm::StringSwitch<FormatStringType>(Format->getType()) 1534 .Case("scanf", FST_Scanf) 1535 .Cases("printf", "printf0", FST_Printf) 1536 .Cases("NSString", "CFString", FST_NSString) 1537 .Case("strftime", FST_Strftime) 1538 .Case("strfmon", FST_Strfmon) 1539 .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf) 1540 .Default(FST_Unknown); 1541} 1542 1543/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1544/// functions) for correct use of format strings. 1545void Sema::CheckFormatArguments(const FormatAttr *Format, CallExpr *TheCall) { 1546 bool IsCXXMember = false; 1547 // The way the format attribute works in GCC, the implicit this argument 1548 // of member functions is counted. However, it doesn't appear in our own 1549 // lists, so decrement format_idx in that case. 1550 IsCXXMember = isa<CXXMemberCallExpr>(TheCall); 1551 CheckFormatArguments(Format, TheCall->getArgs(), TheCall->getNumArgs(), 1552 IsCXXMember, TheCall->getRParenLoc(), 1553 TheCall->getCallee()->getSourceRange()); 1554} 1555 1556void Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args, 1557 unsigned NumArgs, bool IsCXXMember, 1558 SourceLocation Loc, SourceRange Range) { 1559 bool HasVAListArg = Format->getFirstArg() == 0; 1560 unsigned format_idx = Format->getFormatIdx() - 1; 1561 unsigned firstDataArg = HasVAListArg ? 0 : Format->getFirstArg() - 1; 1562 if (IsCXXMember) { 1563 if (format_idx == 0) 1564 return; 1565 --format_idx; 1566 if(firstDataArg != 0) 1567 --firstDataArg; 1568 } 1569 CheckFormatArguments(Args, NumArgs, HasVAListArg, format_idx, 1570 firstDataArg, GetFormatStringType(Format), Loc, Range); 1571} 1572 1573void Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs, 1574 bool HasVAListArg, unsigned format_idx, 1575 unsigned firstDataArg, FormatStringType Type, 1576 SourceLocation Loc, SourceRange Range) { 1577 // CHECK: printf/scanf-like function is called with no format string. 1578 if (format_idx >= NumArgs) { 1579 Diag(Loc, diag::warn_missing_format_string) << Range; 1580 return; 1581 } 1582 1583 const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts(); 1584 1585 // CHECK: format string is not a string literal. 1586 // 1587 // Dynamically generated format strings are difficult to 1588 // automatically vet at compile time. Requiring that format strings 1589 // are string literals: (1) permits the checking of format strings by 1590 // the compiler and thereby (2) can practically remove the source of 1591 // many format string exploits. 1592 1593 // Format string can be either ObjC string (e.g. @"%d") or 1594 // C string (e.g. "%d") 1595 // ObjC string uses the same format specifiers as C string, so we can use 1596 // the same format string checking logic for both ObjC and C strings. 1597 if (SemaCheckStringLiteral(OrigFormatExpr, Args, NumArgs, HasVAListArg, 1598 format_idx, firstDataArg, Type)) 1599 return; // Literal format string found, check done! 1600 1601 // Strftime is particular as it always uses a single 'time' argument, 1602 // so it is safe to pass a non-literal string. 1603 if (Type == FST_Strftime) 1604 return; 1605 1606 // Do not emit diag when the string param is a macro expansion and the 1607 // format is either NSString or CFString. This is a hack to prevent 1608 // diag when using the NSLocalizedString and CFCopyLocalizedString macros 1609 // which are usually used in place of NS and CF string literals. 1610 if (Type == FST_NSString && Args[format_idx]->getLocStart().isMacroID()) 1611 return; 1612 1613 // If there are no arguments specified, warn with -Wformat-security, otherwise 1614 // warn only with -Wformat-nonliteral. 1615 if (NumArgs == format_idx+1) 1616 Diag(Args[format_idx]->getLocStart(), 1617 diag::warn_format_nonliteral_noargs) 1618 << OrigFormatExpr->getSourceRange(); 1619 else 1620 Diag(Args[format_idx]->getLocStart(), 1621 diag::warn_format_nonliteral) 1622 << OrigFormatExpr->getSourceRange(); 1623} 1624 1625namespace { 1626class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1627protected: 1628 Sema &S; 1629 const StringLiteral *FExpr; 1630 const Expr *OrigFormatExpr; 1631 const unsigned FirstDataArg; 1632 const unsigned NumDataArgs; 1633 const bool IsObjCLiteral; 1634 const char *Beg; // Start of format string. 1635 const bool HasVAListArg; 1636 const Expr * const *Args; 1637 const unsigned NumArgs; 1638 unsigned FormatIdx; 1639 llvm::BitVector CoveredArgs; 1640 bool usesPositionalArgs; 1641 bool atFirstArg; 1642 bool inFunctionCall; 1643public: 1644 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1645 const Expr *origFormatExpr, unsigned firstDataArg, 1646 unsigned numDataArgs, bool isObjCLiteral, 1647 const char *beg, bool hasVAListArg, 1648 Expr **args, unsigned numArgs, 1649 unsigned formatIdx, bool inFunctionCall) 1650 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1651 FirstDataArg(firstDataArg), 1652 NumDataArgs(numDataArgs), 1653 IsObjCLiteral(isObjCLiteral), Beg(beg), 1654 HasVAListArg(hasVAListArg), 1655 Args(args), NumArgs(numArgs), FormatIdx(formatIdx), 1656 usesPositionalArgs(false), atFirstArg(true), 1657 inFunctionCall(inFunctionCall) { 1658 CoveredArgs.resize(numDataArgs); 1659 CoveredArgs.reset(); 1660 } 1661 1662 void DoneProcessing(); 1663 1664 void HandleIncompleteSpecifier(const char *startSpecifier, 1665 unsigned specifierLen); 1666 1667 virtual void HandleInvalidPosition(const char *startSpecifier, 1668 unsigned specifierLen, 1669 analyze_format_string::PositionContext p); 1670 1671 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1672 1673 void HandleNullChar(const char *nullCharacter); 1674 1675 template <typename Range> 1676 static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall, 1677 const Expr *ArgumentExpr, 1678 PartialDiagnostic PDiag, 1679 SourceLocation StringLoc, 1680 bool IsStringLocation, Range StringRange, 1681 FixItHint Fixit = FixItHint()); 1682 1683protected: 1684 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1685 const char *startSpec, 1686 unsigned specifierLen, 1687 const char *csStart, unsigned csLen); 1688 1689 void HandlePositionalNonpositionalArgs(SourceLocation Loc, 1690 const char *startSpec, 1691 unsigned specifierLen); 1692 1693 SourceRange getFormatStringRange(); 1694 CharSourceRange getSpecifierRange(const char *startSpecifier, 1695 unsigned specifierLen); 1696 SourceLocation getLocationOfByte(const char *x); 1697 1698 const Expr *getDataArg(unsigned i) const; 1699 1700 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1701 const analyze_format_string::ConversionSpecifier &CS, 1702 const char *startSpecifier, unsigned specifierLen, 1703 unsigned argIndex); 1704 1705 template <typename Range> 1706 void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc, 1707 bool IsStringLocation, Range StringRange, 1708 FixItHint Fixit = FixItHint()); 1709 1710 void CheckPositionalAndNonpositionalArgs( 1711 const analyze_format_string::FormatSpecifier *FS); 1712}; 1713} 1714 1715SourceRange CheckFormatHandler::getFormatStringRange() { 1716 return OrigFormatExpr->getSourceRange(); 1717} 1718 1719CharSourceRange CheckFormatHandler:: 1720getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1721 SourceLocation Start = getLocationOfByte(startSpecifier); 1722 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1723 1724 // Advance the end SourceLocation by one due to half-open ranges. 1725 End = End.getLocWithOffset(1); 1726 1727 return CharSourceRange::getCharRange(Start, End); 1728} 1729 1730SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1731 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1732} 1733 1734void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1735 unsigned specifierLen){ 1736 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier), 1737 getLocationOfByte(startSpecifier), 1738 /*IsStringLocation*/true, 1739 getSpecifierRange(startSpecifier, specifierLen)); 1740} 1741 1742void 1743CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1744 analyze_format_string::PositionContext p) { 1745 EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier) 1746 << (unsigned) p, 1747 getLocationOfByte(startPos), /*IsStringLocation*/true, 1748 getSpecifierRange(startPos, posLen)); 1749} 1750 1751void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1752 unsigned posLen) { 1753 EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier), 1754 getLocationOfByte(startPos), 1755 /*IsStringLocation*/true, 1756 getSpecifierRange(startPos, posLen)); 1757} 1758 1759void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1760 if (!IsObjCLiteral) { 1761 // The presence of a null character is likely an error. 1762 EmitFormatDiagnostic( 1763 S.PDiag(diag::warn_printf_format_string_contains_null_char), 1764 getLocationOfByte(nullCharacter), /*IsStringLocation*/true, 1765 getFormatStringRange()); 1766 } 1767} 1768 1769const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1770 return Args[FirstDataArg + i]; 1771} 1772 1773void CheckFormatHandler::DoneProcessing() { 1774 // Does the number of data arguments exceed the number of 1775 // format conversions in the format string? 1776 if (!HasVAListArg) { 1777 // Find any arguments that weren't covered. 1778 CoveredArgs.flip(); 1779 signed notCoveredArg = CoveredArgs.find_first(); 1780 if (notCoveredArg >= 0) { 1781 assert((unsigned)notCoveredArg < NumDataArgs); 1782 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used), 1783 getDataArg((unsigned) notCoveredArg)->getLocStart(), 1784 /*IsStringLocation*/false, getFormatStringRange()); 1785 } 1786 } 1787} 1788 1789bool 1790CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1791 SourceLocation Loc, 1792 const char *startSpec, 1793 unsigned specifierLen, 1794 const char *csStart, 1795 unsigned csLen) { 1796 1797 bool keepGoing = true; 1798 if (argIndex < NumDataArgs) { 1799 // Consider the argument coverered, even though the specifier doesn't 1800 // make sense. 1801 CoveredArgs.set(argIndex); 1802 } 1803 else { 1804 // If argIndex exceeds the number of data arguments we 1805 // don't issue a warning because that is just a cascade of warnings (and 1806 // they may have intended '%%' anyway). We don't want to continue processing 1807 // the format string after this point, however, as we will like just get 1808 // gibberish when trying to match arguments. 1809 keepGoing = false; 1810 } 1811 1812 EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion) 1813 << StringRef(csStart, csLen), 1814 Loc, /*IsStringLocation*/true, 1815 getSpecifierRange(startSpec, specifierLen)); 1816 1817 return keepGoing; 1818} 1819 1820void 1821CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc, 1822 const char *startSpec, 1823 unsigned specifierLen) { 1824 EmitFormatDiagnostic( 1825 S.PDiag(diag::warn_format_mix_positional_nonpositional_args), 1826 Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen)); 1827} 1828 1829bool 1830CheckFormatHandler::CheckNumArgs( 1831 const analyze_format_string::FormatSpecifier &FS, 1832 const analyze_format_string::ConversionSpecifier &CS, 1833 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1834 1835 if (argIndex >= NumDataArgs) { 1836 PartialDiagnostic PDiag = FS.usesPositionalArg() 1837 ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args) 1838 << (argIndex+1) << NumDataArgs) 1839 : S.PDiag(diag::warn_printf_insufficient_data_args); 1840 EmitFormatDiagnostic( 1841 PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true, 1842 getSpecifierRange(startSpecifier, specifierLen)); 1843 return false; 1844 } 1845 return true; 1846} 1847 1848template<typename Range> 1849void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag, 1850 SourceLocation Loc, 1851 bool IsStringLocation, 1852 Range StringRange, 1853 FixItHint FixIt) { 1854 EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag, 1855 Loc, IsStringLocation, StringRange, FixIt); 1856} 1857 1858/// \brief If the format string is not within the funcion call, emit a note 1859/// so that the function call and string are in diagnostic messages. 1860/// 1861/// \param inFunctionCall if true, the format string is within the function 1862/// call and only one diagnostic message will be produced. Otherwise, an 1863/// extra note will be emitted pointing to location of the format string. 1864/// 1865/// \param ArgumentExpr the expression that is passed as the format string 1866/// argument in the function call. Used for getting locations when two 1867/// diagnostics are emitted. 1868/// 1869/// \param PDiag the callee should already have provided any strings for the 1870/// diagnostic message. This function only adds locations and fixits 1871/// to diagnostics. 1872/// 1873/// \param Loc primary location for diagnostic. If two diagnostics are 1874/// required, one will be at Loc and a new SourceLocation will be created for 1875/// the other one. 1876/// 1877/// \param IsStringLocation if true, Loc points to the format string should be 1878/// used for the note. Otherwise, Loc points to the argument list and will 1879/// be used with PDiag. 1880/// 1881/// \param StringRange some or all of the string to highlight. This is 1882/// templated so it can accept either a CharSourceRange or a SourceRange. 1883/// 1884/// \param Fixit optional fix it hint for the format string. 1885template<typename Range> 1886void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall, 1887 const Expr *ArgumentExpr, 1888 PartialDiagnostic PDiag, 1889 SourceLocation Loc, 1890 bool IsStringLocation, 1891 Range StringRange, 1892 FixItHint FixIt) { 1893 if (InFunctionCall) 1894 S.Diag(Loc, PDiag) << StringRange << FixIt; 1895 else { 1896 S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag) 1897 << ArgumentExpr->getSourceRange(); 1898 S.Diag(IsStringLocation ? Loc : StringRange.getBegin(), 1899 diag::note_format_string_defined) 1900 << StringRange << FixIt; 1901 } 1902} 1903 1904//===--- CHECK: Printf format string checking ------------------------------===// 1905 1906namespace { 1907class CheckPrintfHandler : public CheckFormatHandler { 1908public: 1909 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1910 const Expr *origFormatExpr, unsigned firstDataArg, 1911 unsigned numDataArgs, bool isObjCLiteral, 1912 const char *beg, bool hasVAListArg, 1913 Expr **Args, unsigned NumArgs, 1914 unsigned formatIdx, bool inFunctionCall) 1915 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1916 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1917 Args, NumArgs, formatIdx, inFunctionCall) {} 1918 1919 1920 bool HandleInvalidPrintfConversionSpecifier( 1921 const analyze_printf::PrintfSpecifier &FS, 1922 const char *startSpecifier, 1923 unsigned specifierLen); 1924 1925 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1926 const char *startSpecifier, 1927 unsigned specifierLen); 1928 1929 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1930 const char *startSpecifier, unsigned specifierLen); 1931 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1932 const analyze_printf::OptionalAmount &Amt, 1933 unsigned type, 1934 const char *startSpecifier, unsigned specifierLen); 1935 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1936 const analyze_printf::OptionalFlag &flag, 1937 const char *startSpecifier, unsigned specifierLen); 1938 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1939 const analyze_printf::OptionalFlag &ignoredFlag, 1940 const analyze_printf::OptionalFlag &flag, 1941 const char *startSpecifier, unsigned specifierLen); 1942}; 1943} 1944 1945bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1946 const analyze_printf::PrintfSpecifier &FS, 1947 const char *startSpecifier, 1948 unsigned specifierLen) { 1949 const analyze_printf::PrintfConversionSpecifier &CS = 1950 FS.getConversionSpecifier(); 1951 1952 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1953 getLocationOfByte(CS.getStart()), 1954 startSpecifier, specifierLen, 1955 CS.getStart(), CS.getLength()); 1956} 1957 1958bool CheckPrintfHandler::HandleAmount( 1959 const analyze_format_string::OptionalAmount &Amt, 1960 unsigned k, const char *startSpecifier, 1961 unsigned specifierLen) { 1962 1963 if (Amt.hasDataArgument()) { 1964 if (!HasVAListArg) { 1965 unsigned argIndex = Amt.getArgIndex(); 1966 if (argIndex >= NumDataArgs) { 1967 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg) 1968 << k, 1969 getLocationOfByte(Amt.getStart()), 1970 /*IsStringLocation*/true, 1971 getSpecifierRange(startSpecifier, specifierLen)); 1972 // Don't do any more checking. We will just emit 1973 // spurious errors. 1974 return false; 1975 } 1976 1977 // Type check the data argument. It should be an 'int'. 1978 // Although not in conformance with C99, we also allow the argument to be 1979 // an 'unsigned int' as that is a reasonably safe case. GCC also 1980 // doesn't emit a warning for that case. 1981 CoveredArgs.set(argIndex); 1982 const Expr *Arg = getDataArg(argIndex); 1983 QualType T = Arg->getType(); 1984 1985 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1986 assert(ATR.isValid()); 1987 1988 if (!ATR.matchesType(S.Context, T)) { 1989 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type) 1990 << k << ATR.getRepresentativeTypeName(S.Context) 1991 << T << Arg->getSourceRange(), 1992 getLocationOfByte(Amt.getStart()), 1993 /*IsStringLocation*/true, 1994 getSpecifierRange(startSpecifier, specifierLen)); 1995 // Don't do any more checking. We will just emit 1996 // spurious errors. 1997 return false; 1998 } 1999 } 2000 } 2001 return true; 2002} 2003 2004void CheckPrintfHandler::HandleInvalidAmount( 2005 const analyze_printf::PrintfSpecifier &FS, 2006 const analyze_printf::OptionalAmount &Amt, 2007 unsigned type, 2008 const char *startSpecifier, 2009 unsigned specifierLen) { 2010 const analyze_printf::PrintfConversionSpecifier &CS = 2011 FS.getConversionSpecifier(); 2012 2013 FixItHint fixit = 2014 Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant 2015 ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 2016 Amt.getConstantLength())) 2017 : FixItHint(); 2018 2019 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount) 2020 << type << CS.toString(), 2021 getLocationOfByte(Amt.getStart()), 2022 /*IsStringLocation*/true, 2023 getSpecifierRange(startSpecifier, specifierLen), 2024 fixit); 2025} 2026 2027void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 2028 const analyze_printf::OptionalFlag &flag, 2029 const char *startSpecifier, 2030 unsigned specifierLen) { 2031 // Warn about pointless flag with a fixit removal. 2032 const analyze_printf::PrintfConversionSpecifier &CS = 2033 FS.getConversionSpecifier(); 2034 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag) 2035 << flag.toString() << CS.toString(), 2036 getLocationOfByte(flag.getPosition()), 2037 /*IsStringLocation*/true, 2038 getSpecifierRange(startSpecifier, specifierLen), 2039 FixItHint::CreateRemoval( 2040 getSpecifierRange(flag.getPosition(), 1))); 2041} 2042 2043void CheckPrintfHandler::HandleIgnoredFlag( 2044 const analyze_printf::PrintfSpecifier &FS, 2045 const analyze_printf::OptionalFlag &ignoredFlag, 2046 const analyze_printf::OptionalFlag &flag, 2047 const char *startSpecifier, 2048 unsigned specifierLen) { 2049 // Warn about ignored flag with a fixit removal. 2050 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag) 2051 << ignoredFlag.toString() << flag.toString(), 2052 getLocationOfByte(ignoredFlag.getPosition()), 2053 /*IsStringLocation*/true, 2054 getSpecifierRange(startSpecifier, specifierLen), 2055 FixItHint::CreateRemoval( 2056 getSpecifierRange(ignoredFlag.getPosition(), 1))); 2057} 2058 2059bool 2060CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 2061 &FS, 2062 const char *startSpecifier, 2063 unsigned specifierLen) { 2064 2065 using namespace analyze_format_string; 2066 using namespace analyze_printf; 2067 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 2068 2069 if (FS.consumesDataArgument()) { 2070 if (atFirstArg) { 2071 atFirstArg = false; 2072 usesPositionalArgs = FS.usesPositionalArg(); 2073 } 2074 else if (usesPositionalArgs != FS.usesPositionalArg()) { 2075 HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()), 2076 startSpecifier, specifierLen); 2077 return false; 2078 } 2079 } 2080 2081 // First check if the field width, precision, and conversion specifier 2082 // have matching data arguments. 2083 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 2084 startSpecifier, specifierLen)) { 2085 return false; 2086 } 2087 2088 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 2089 startSpecifier, specifierLen)) { 2090 return false; 2091 } 2092 2093 if (!CS.consumesDataArgument()) { 2094 // FIXME: Technically specifying a precision or field width here 2095 // makes no sense. Worth issuing a warning at some point. 2096 return true; 2097 } 2098 2099 // Consume the argument. 2100 unsigned argIndex = FS.getArgIndex(); 2101 if (argIndex < NumDataArgs) { 2102 // The check to see if the argIndex is valid will come later. 2103 // We set the bit here because we may exit early from this 2104 // function if we encounter some other error. 2105 CoveredArgs.set(argIndex); 2106 } 2107 2108 // Check for using an Objective-C specific conversion specifier 2109 // in a non-ObjC literal. 2110 if (!IsObjCLiteral && CS.isObjCArg()) { 2111 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 2112 specifierLen); 2113 } 2114 2115 // Check for invalid use of field width 2116 if (!FS.hasValidFieldWidth()) { 2117 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 2118 startSpecifier, specifierLen); 2119 } 2120 2121 // Check for invalid use of precision 2122 if (!FS.hasValidPrecision()) { 2123 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 2124 startSpecifier, specifierLen); 2125 } 2126 2127 // Check each flag does not conflict with any other component. 2128 if (!FS.hasValidThousandsGroupingPrefix()) 2129 HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); 2130 if (!FS.hasValidLeadingZeros()) 2131 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 2132 if (!FS.hasValidPlusPrefix()) 2133 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 2134 if (!FS.hasValidSpacePrefix()) 2135 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 2136 if (!FS.hasValidAlternativeForm()) 2137 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 2138 if (!FS.hasValidLeftJustified()) 2139 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 2140 2141 // Check that flags are not ignored by another flag 2142 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 2143 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 2144 startSpecifier, specifierLen); 2145 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 2146 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 2147 startSpecifier, specifierLen); 2148 2149 // Check the length modifier is valid with the given conversion specifier. 2150 const LengthModifier &LM = FS.getLengthModifier(); 2151 if (!FS.hasValidLengthModifier()) 2152 EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length) 2153 << LM.toString() << CS.toString(), 2154 getLocationOfByte(LM.getStart()), 2155 /*IsStringLocation*/true, 2156 getSpecifierRange(startSpecifier, specifierLen), 2157 FixItHint::CreateRemoval( 2158 getSpecifierRange(LM.getStart(), 2159 LM.getLength()))); 2160 2161 // Are we using '%n'? 2162 if (CS.getKind() == ConversionSpecifier::nArg) { 2163 // Issue a warning about this being a possible security issue. 2164 EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back), 2165 getLocationOfByte(CS.getStart()), 2166 /*IsStringLocation*/true, 2167 getSpecifierRange(startSpecifier, specifierLen)); 2168 // Continue checking the other format specifiers. 2169 return true; 2170 } 2171 2172 // The remaining checks depend on the data arguments. 2173 if (HasVAListArg) 2174 return true; 2175 2176 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 2177 return false; 2178 2179 // Now type check the data expression that matches the 2180 // format specifier. 2181 const Expr *Ex = getDataArg(argIndex); 2182 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context, 2183 IsObjCLiteral); 2184 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 2185 // Check if we didn't match because of an implicit cast from a 'char' 2186 // or 'short' to an 'int'. This is done because printf is a varargs 2187 // function. 2188 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 2189 if (ICE->getType() == S.Context.IntTy) { 2190 // All further checking is done on the subexpression. 2191 Ex = ICE->getSubExpr(); 2192 if (ATR.matchesType(S.Context, Ex->getType())) 2193 return true; 2194 } 2195 2196 // We may be able to offer a FixItHint if it is a supported type. 2197 PrintfSpecifier fixedFS = FS; 2198 bool success = fixedFS.fixType(Ex->getType(), S.getLangOptions(), 2199 S.Context, IsObjCLiteral); 2200 2201 if (success) { 2202 // Get the fix string from the fixed format specifier 2203 SmallString<128> buf; 2204 llvm::raw_svector_ostream os(buf); 2205 fixedFS.toString(os); 2206 2207 EmitFormatDiagnostic( 2208 S.PDiag(diag::warn_printf_conversion_argument_type_mismatch) 2209 << ATR.getRepresentativeTypeName(S.Context) << Ex->getType() 2210 << Ex->getSourceRange(), 2211 getLocationOfByte(CS.getStart()), 2212 /*IsStringLocation*/true, 2213 getSpecifierRange(startSpecifier, specifierLen), 2214 FixItHint::CreateReplacement( 2215 getSpecifierRange(startSpecifier, specifierLen), 2216 os.str())); 2217 } 2218 else { 2219 EmitFormatDiagnostic( 2220 S.PDiag(diag::warn_printf_conversion_argument_type_mismatch) 2221 << ATR.getRepresentativeTypeName(S.Context) << Ex->getType() 2222 << getSpecifierRange(startSpecifier, specifierLen) 2223 << Ex->getSourceRange(), 2224 getLocationOfByte(CS.getStart()), 2225 true, 2226 getSpecifierRange(startSpecifier, specifierLen)); 2227 } 2228 } 2229 2230 return true; 2231} 2232 2233//===--- CHECK: Scanf format string checking ------------------------------===// 2234 2235namespace { 2236class CheckScanfHandler : public CheckFormatHandler { 2237public: 2238 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 2239 const Expr *origFormatExpr, unsigned firstDataArg, 2240 unsigned numDataArgs, bool isObjCLiteral, 2241 const char *beg, bool hasVAListArg, 2242 Expr **Args, unsigned NumArgs, 2243 unsigned formatIdx, bool inFunctionCall) 2244 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 2245 numDataArgs, isObjCLiteral, beg, hasVAListArg, 2246 Args, NumArgs, formatIdx, inFunctionCall) {} 2247 2248 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 2249 const char *startSpecifier, 2250 unsigned specifierLen); 2251 2252 bool HandleInvalidScanfConversionSpecifier( 2253 const analyze_scanf::ScanfSpecifier &FS, 2254 const char *startSpecifier, 2255 unsigned specifierLen); 2256 2257 void HandleIncompleteScanList(const char *start, const char *end); 2258}; 2259} 2260 2261void CheckScanfHandler::HandleIncompleteScanList(const char *start, 2262 const char *end) { 2263 EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete), 2264 getLocationOfByte(end), /*IsStringLocation*/true, 2265 getSpecifierRange(start, end - start)); 2266} 2267 2268bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 2269 const analyze_scanf::ScanfSpecifier &FS, 2270 const char *startSpecifier, 2271 unsigned specifierLen) { 2272 2273 const analyze_scanf::ScanfConversionSpecifier &CS = 2274 FS.getConversionSpecifier(); 2275 2276 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 2277 getLocationOfByte(CS.getStart()), 2278 startSpecifier, specifierLen, 2279 CS.getStart(), CS.getLength()); 2280} 2281 2282bool CheckScanfHandler::HandleScanfSpecifier( 2283 const analyze_scanf::ScanfSpecifier &FS, 2284 const char *startSpecifier, 2285 unsigned specifierLen) { 2286 2287 using namespace analyze_scanf; 2288 using namespace analyze_format_string; 2289 2290 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 2291 2292 // Handle case where '%' and '*' don't consume an argument. These shouldn't 2293 // be used to decide if we are using positional arguments consistently. 2294 if (FS.consumesDataArgument()) { 2295 if (atFirstArg) { 2296 atFirstArg = false; 2297 usesPositionalArgs = FS.usesPositionalArg(); 2298 } 2299 else if (usesPositionalArgs != FS.usesPositionalArg()) { 2300 HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()), 2301 startSpecifier, specifierLen); 2302 return false; 2303 } 2304 } 2305 2306 // Check if the field with is non-zero. 2307 const OptionalAmount &Amt = FS.getFieldWidth(); 2308 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 2309 if (Amt.getConstantAmount() == 0) { 2310 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 2311 Amt.getConstantLength()); 2312 EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width), 2313 getLocationOfByte(Amt.getStart()), 2314 /*IsStringLocation*/true, R, 2315 FixItHint::CreateRemoval(R)); 2316 } 2317 } 2318 2319 if (!FS.consumesDataArgument()) { 2320 // FIXME: Technically specifying a precision or field width here 2321 // makes no sense. Worth issuing a warning at some point. 2322 return true; 2323 } 2324 2325 // Consume the argument. 2326 unsigned argIndex = FS.getArgIndex(); 2327 if (argIndex < NumDataArgs) { 2328 // The check to see if the argIndex is valid will come later. 2329 // We set the bit here because we may exit early from this 2330 // function if we encounter some other error. 2331 CoveredArgs.set(argIndex); 2332 } 2333 2334 // Check the length modifier is valid with the given conversion specifier. 2335 const LengthModifier &LM = FS.getLengthModifier(); 2336 if (!FS.hasValidLengthModifier()) { 2337 const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength()); 2338 EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length) 2339 << LM.toString() << CS.toString() 2340 << getSpecifierRange(startSpecifier, specifierLen), 2341 getLocationOfByte(LM.getStart()), 2342 /*IsStringLocation*/true, R, 2343 FixItHint::CreateRemoval(R)); 2344 } 2345 2346 // The remaining checks depend on the data arguments. 2347 if (HasVAListArg) 2348 return true; 2349 2350 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 2351 return false; 2352 2353 // Check that the argument type matches the format specifier. 2354 const Expr *Ex = getDataArg(argIndex); 2355 const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context); 2356 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 2357 ScanfSpecifier fixedFS = FS; 2358 bool success = fixedFS.fixType(Ex->getType(), S.getLangOptions(), 2359 S.Context); 2360 2361 if (success) { 2362 // Get the fix string from the fixed format specifier. 2363 SmallString<128> buf; 2364 llvm::raw_svector_ostream os(buf); 2365 fixedFS.toString(os); 2366 2367 EmitFormatDiagnostic( 2368 S.PDiag(diag::warn_printf_conversion_argument_type_mismatch) 2369 << ATR.getRepresentativeTypeName(S.Context) << Ex->getType() 2370 << Ex->getSourceRange(), 2371 getLocationOfByte(CS.getStart()), 2372 /*IsStringLocation*/true, 2373 getSpecifierRange(startSpecifier, specifierLen), 2374 FixItHint::CreateReplacement( 2375 getSpecifierRange(startSpecifier, specifierLen), 2376 os.str())); 2377 } else { 2378 EmitFormatDiagnostic( 2379 S.PDiag(diag::warn_printf_conversion_argument_type_mismatch) 2380 << ATR.getRepresentativeTypeName(S.Context) << Ex->getType() 2381 << Ex->getSourceRange(), 2382 getLocationOfByte(CS.getStart()), 2383 /*IsStringLocation*/true, 2384 getSpecifierRange(startSpecifier, specifierLen)); 2385 } 2386 } 2387 2388 return true; 2389} 2390 2391void Sema::CheckFormatString(const StringLiteral *FExpr, 2392 const Expr *OrigFormatExpr, 2393 Expr **Args, unsigned NumArgs, 2394 bool HasVAListArg, unsigned format_idx, 2395 unsigned firstDataArg, FormatStringType Type, 2396 bool inFunctionCall) { 2397 2398 // CHECK: is the format string a wide literal? 2399 if (!FExpr->isAscii()) { 2400 CheckFormatHandler::EmitFormatDiagnostic( 2401 *this, inFunctionCall, Args[format_idx], 2402 PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(), 2403 /*IsStringLocation*/true, OrigFormatExpr->getSourceRange()); 2404 return; 2405 } 2406 2407 // Str - The format string. NOTE: this is NOT null-terminated! 2408 StringRef StrRef = FExpr->getString(); 2409 const char *Str = StrRef.data(); 2410 unsigned StrLen = StrRef.size(); 2411 const unsigned numDataArgs = NumArgs - firstDataArg; 2412 2413 // CHECK: empty format string? 2414 if (StrLen == 0 && numDataArgs > 0) { 2415 CheckFormatHandler::EmitFormatDiagnostic( 2416 *this, inFunctionCall, Args[format_idx], 2417 PDiag(diag::warn_empty_format_string), FExpr->getLocStart(), 2418 /*IsStringLocation*/true, OrigFormatExpr->getSourceRange()); 2419 return; 2420 } 2421 2422 if (Type == FST_Printf || Type == FST_NSString) { 2423 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 2424 numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr), 2425 Str, HasVAListArg, Args, NumArgs, format_idx, 2426 inFunctionCall); 2427 2428 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen, 2429 getLangOptions())) 2430 H.DoneProcessing(); 2431 } else if (Type == FST_Scanf) { 2432 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 2433 numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr), 2434 Str, HasVAListArg, Args, NumArgs, format_idx, 2435 inFunctionCall); 2436 2437 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen, 2438 getLangOptions())) 2439 H.DoneProcessing(); 2440 } // TODO: handle other formats 2441} 2442 2443//===--- CHECK: Standard memory functions ---------------------------------===// 2444 2445/// \brief Determine whether the given type is a dynamic class type (e.g., 2446/// whether it has a vtable). 2447static bool isDynamicClassType(QualType T) { 2448 if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) 2449 if (CXXRecordDecl *Definition = Record->getDefinition()) 2450 if (Definition->isDynamicClass()) 2451 return true; 2452 2453 return false; 2454} 2455 2456/// \brief If E is a sizeof expression, returns its argument expression, 2457/// otherwise returns NULL. 2458static const Expr *getSizeOfExprArg(const Expr* E) { 2459 if (const UnaryExprOrTypeTraitExpr *SizeOf = 2460 dyn_cast<UnaryExprOrTypeTraitExpr>(E)) 2461 if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType()) 2462 return SizeOf->getArgumentExpr()->IgnoreParenImpCasts(); 2463 2464 return 0; 2465} 2466 2467/// \brief If E is a sizeof expression, returns its argument type. 2468static QualType getSizeOfArgType(const Expr* E) { 2469 if (const UnaryExprOrTypeTraitExpr *SizeOf = 2470 dyn_cast<UnaryExprOrTypeTraitExpr>(E)) 2471 if (SizeOf->getKind() == clang::UETT_SizeOf) 2472 return SizeOf->getTypeOfArgument(); 2473 2474 return QualType(); 2475} 2476 2477/// \brief Check for dangerous or invalid arguments to memset(). 2478/// 2479/// This issues warnings on known problematic, dangerous or unspecified 2480/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp' 2481/// function calls. 2482/// 2483/// \param Call The call expression to diagnose. 2484void Sema::CheckMemaccessArguments(const CallExpr *Call, 2485 unsigned BId, 2486 IdentifierInfo *FnName) { 2487 assert(BId != 0); 2488 2489 // It is possible to have a non-standard definition of memset. Validate 2490 // we have enough arguments, and if not, abort further checking. 2491 unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3); 2492 if (Call->getNumArgs() < ExpectedNumArgs) 2493 return; 2494 2495 unsigned LastArg = (BId == Builtin::BImemset || 2496 BId == Builtin::BIstrndup ? 1 : 2); 2497 unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2); 2498 const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts(); 2499 2500 // We have special checking when the length is a sizeof expression. 2501 QualType SizeOfArgTy = getSizeOfArgType(LenExpr); 2502 const Expr *SizeOfArg = getSizeOfExprArg(LenExpr); 2503 llvm::FoldingSetNodeID SizeOfArgID; 2504 2505 for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) { 2506 const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts(); 2507 SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange(); 2508 2509 QualType DestTy = Dest->getType(); 2510 if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) { 2511 QualType PointeeTy = DestPtrTy->getPointeeType(); 2512 2513 // Never warn about void type pointers. This can be used to suppress 2514 // false positives. 2515 if (PointeeTy->isVoidType()) 2516 continue; 2517 2518 // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by 2519 // actually comparing the expressions for equality. Because computing the 2520 // expression IDs can be expensive, we only do this if the diagnostic is 2521 // enabled. 2522 if (SizeOfArg && 2523 Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess, 2524 SizeOfArg->getExprLoc())) { 2525 // We only compute IDs for expressions if the warning is enabled, and 2526 // cache the sizeof arg's ID. 2527 if (SizeOfArgID == llvm::FoldingSetNodeID()) 2528 SizeOfArg->Profile(SizeOfArgID, Context, true); 2529 llvm::FoldingSetNodeID DestID; 2530 Dest->Profile(DestID, Context, true); 2531 if (DestID == SizeOfArgID) { 2532 // TODO: For strncpy() and friends, this could suggest sizeof(dst) 2533 // over sizeof(src) as well. 2534 unsigned ActionIdx = 0; // Default is to suggest dereferencing. 2535 if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest)) 2536 if (UnaryOp->getOpcode() == UO_AddrOf) 2537 ActionIdx = 1; // If its an address-of operator, just remove it. 2538 if (Context.getTypeSize(PointeeTy) == Context.getCharWidth()) 2539 ActionIdx = 2; // If the pointee's size is sizeof(char), 2540 // suggest an explicit length. 2541 unsigned DestSrcSelect = 2542 (BId == Builtin::BIstrndup ? 1 : ArgIdx); 2543 DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest, 2544 PDiag(diag::warn_sizeof_pointer_expr_memaccess) 2545 << FnName << DestSrcSelect << ActionIdx 2546 << Dest->getSourceRange() 2547 << SizeOfArg->getSourceRange()); 2548 break; 2549 } 2550 } 2551 2552 // Also check for cases where the sizeof argument is the exact same 2553 // type as the memory argument, and where it points to a user-defined 2554 // record type. 2555 if (SizeOfArgTy != QualType()) { 2556 if (PointeeTy->isRecordType() && 2557 Context.typesAreCompatible(SizeOfArgTy, DestTy)) { 2558 DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest, 2559 PDiag(diag::warn_sizeof_pointer_type_memaccess) 2560 << FnName << SizeOfArgTy << ArgIdx 2561 << PointeeTy << Dest->getSourceRange() 2562 << LenExpr->getSourceRange()); 2563 break; 2564 } 2565 } 2566 2567 // Always complain about dynamic classes. 2568 if (isDynamicClassType(PointeeTy)) { 2569 2570 unsigned OperationType = 0; 2571 // "overwritten" if we're warning about the destination for any call 2572 // but memcmp; otherwise a verb appropriate to the call. 2573 if (ArgIdx != 0 || BId == Builtin::BImemcmp) { 2574 if (BId == Builtin::BImemcpy) 2575 OperationType = 1; 2576 else if(BId == Builtin::BImemmove) 2577 OperationType = 2; 2578 else if (BId == Builtin::BImemcmp) 2579 OperationType = 3; 2580 } 2581 2582 DiagRuntimeBehavior( 2583 Dest->getExprLoc(), Dest, 2584 PDiag(diag::warn_dyn_class_memaccess) 2585 << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx) 2586 << FnName << PointeeTy 2587 << OperationType 2588 << Call->getCallee()->getSourceRange()); 2589 } else if (PointeeTy.hasNonTrivialObjCLifetime() && 2590 BId != Builtin::BImemset) 2591 DiagRuntimeBehavior( 2592 Dest->getExprLoc(), Dest, 2593 PDiag(diag::warn_arc_object_memaccess) 2594 << ArgIdx << FnName << PointeeTy 2595 << Call->getCallee()->getSourceRange()); 2596 else 2597 continue; 2598 2599 DiagRuntimeBehavior( 2600 Dest->getExprLoc(), Dest, 2601 PDiag(diag::note_bad_memaccess_silence) 2602 << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)")); 2603 break; 2604 } 2605 } 2606} 2607 2608// A little helper routine: ignore addition and subtraction of integer literals. 2609// This intentionally does not ignore all integer constant expressions because 2610// we don't want to remove sizeof(). 2611static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) { 2612 Ex = Ex->IgnoreParenCasts(); 2613 2614 for (;;) { 2615 const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex); 2616 if (!BO || !BO->isAdditiveOp()) 2617 break; 2618 2619 const Expr *RHS = BO->getRHS()->IgnoreParenCasts(); 2620 const Expr *LHS = BO->getLHS()->IgnoreParenCasts(); 2621 2622 if (isa<IntegerLiteral>(RHS)) 2623 Ex = LHS; 2624 else if (isa<IntegerLiteral>(LHS)) 2625 Ex = RHS; 2626 else 2627 break; 2628 } 2629 2630 return Ex; 2631} 2632 2633// Warn if the user has made the 'size' argument to strlcpy or strlcat 2634// be the size of the source, instead of the destination. 2635void Sema::CheckStrlcpycatArguments(const CallExpr *Call, 2636 IdentifierInfo *FnName) { 2637 2638 // Don't crash if the user has the wrong number of arguments 2639 if (Call->getNumArgs() != 3) 2640 return; 2641 2642 const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context); 2643 const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context); 2644 const Expr *CompareWithSrc = NULL; 2645 2646 // Look for 'strlcpy(dst, x, sizeof(x))' 2647 if (const Expr *Ex = getSizeOfExprArg(SizeArg)) 2648 CompareWithSrc = Ex; 2649 else { 2650 // Look for 'strlcpy(dst, x, strlen(x))' 2651 if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) { 2652 if (SizeCall->isBuiltinCall() == Builtin::BIstrlen 2653 && SizeCall->getNumArgs() == 1) 2654 CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context); 2655 } 2656 } 2657 2658 if (!CompareWithSrc) 2659 return; 2660 2661 // Determine if the argument to sizeof/strlen is equal to the source 2662 // argument. In principle there's all kinds of things you could do 2663 // here, for instance creating an == expression and evaluating it with 2664 // EvaluateAsBooleanCondition, but this uses a more direct technique: 2665 const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg); 2666 if (!SrcArgDRE) 2667 return; 2668 2669 const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc); 2670 if (!CompareWithSrcDRE || 2671 SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl()) 2672 return; 2673 2674 const Expr *OriginalSizeArg = Call->getArg(2); 2675 Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size) 2676 << OriginalSizeArg->getSourceRange() << FnName; 2677 2678 // Output a FIXIT hint if the destination is an array (rather than a 2679 // pointer to an array). This could be enhanced to handle some 2680 // pointers if we know the actual size, like if DstArg is 'array+2' 2681 // we could say 'sizeof(array)-2'. 2682 const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts(); 2683 QualType DstArgTy = DstArg->getType(); 2684 2685 // Only handle constant-sized or VLAs, but not flexible members. 2686 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) { 2687 // Only issue the FIXIT for arrays of size > 1. 2688 if (CAT->getSize().getSExtValue() <= 1) 2689 return; 2690 } else if (!DstArgTy->isVariableArrayType()) { 2691 return; 2692 } 2693 2694 SmallString<128> sizeString; 2695 llvm::raw_svector_ostream OS(sizeString); 2696 OS << "sizeof("; 2697 DstArg->printPretty(OS, Context, 0, getPrintingPolicy()); 2698 OS << ")"; 2699 2700 Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size) 2701 << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(), 2702 OS.str()); 2703} 2704 2705/// Check if two expressions refer to the same declaration. 2706static bool referToTheSameDecl(const Expr *E1, const Expr *E2) { 2707 if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1)) 2708 if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2)) 2709 return D1->getDecl() == D2->getDecl(); 2710 return false; 2711} 2712 2713static const Expr *getStrlenExprArg(const Expr *E) { 2714 if (const CallExpr *CE = dyn_cast<CallExpr>(E)) { 2715 const FunctionDecl *FD = CE->getDirectCallee(); 2716 if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen) 2717 return 0; 2718 return CE->getArg(0)->IgnoreParenCasts(); 2719 } 2720 return 0; 2721} 2722 2723// Warn on anti-patterns as the 'size' argument to strncat. 2724// The correct size argument should look like following: 2725// strncat(dst, src, sizeof(dst) - strlen(dest) - 1); 2726void Sema::CheckStrncatArguments(const CallExpr *CE, 2727 IdentifierInfo *FnName) { 2728 // Don't crash if the user has the wrong number of arguments. 2729 if (CE->getNumArgs() < 3) 2730 return; 2731 const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts(); 2732 const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts(); 2733 const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts(); 2734 2735 // Identify common expressions, which are wrongly used as the size argument 2736 // to strncat and may lead to buffer overflows. 2737 unsigned PatternType = 0; 2738 if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) { 2739 // - sizeof(dst) 2740 if (referToTheSameDecl(SizeOfArg, DstArg)) 2741 PatternType = 1; 2742 // - sizeof(src) 2743 else if (referToTheSameDecl(SizeOfArg, SrcArg)) 2744 PatternType = 2; 2745 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) { 2746 if (BE->getOpcode() == BO_Sub) { 2747 const Expr *L = BE->getLHS()->IgnoreParenCasts(); 2748 const Expr *R = BE->getRHS()->IgnoreParenCasts(); 2749 // - sizeof(dst) - strlen(dst) 2750 if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) && 2751 referToTheSameDecl(DstArg, getStrlenExprArg(R))) 2752 PatternType = 1; 2753 // - sizeof(src) - (anything) 2754 else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L))) 2755 PatternType = 2; 2756 } 2757 } 2758 2759 if (PatternType == 0) 2760 return; 2761 2762 // Generate the diagnostic. 2763 SourceLocation SL = LenArg->getLocStart(); 2764 SourceRange SR = LenArg->getSourceRange(); 2765 SourceManager &SM = PP.getSourceManager(); 2766 2767 // If the function is defined as a builtin macro, do not show macro expansion. 2768 if (SM.isMacroArgExpansion(SL)) { 2769 SL = SM.getSpellingLoc(SL); 2770 SR = SourceRange(SM.getSpellingLoc(SR.getBegin()), 2771 SM.getSpellingLoc(SR.getEnd())); 2772 } 2773 2774 if (PatternType == 1) 2775 Diag(SL, diag::warn_strncat_large_size) << SR; 2776 else 2777 Diag(SL, diag::warn_strncat_src_size) << SR; 2778 2779 // Output a FIXIT hint if the destination is an array (rather than a 2780 // pointer to an array). This could be enhanced to handle some 2781 // pointers if we know the actual size, like if DstArg is 'array+2' 2782 // we could say 'sizeof(array)-2'. 2783 QualType DstArgTy = DstArg->getType(); 2784 2785 // Only handle constant-sized or VLAs, but not flexible members. 2786 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) { 2787 // Only issue the FIXIT for arrays of size > 1. 2788 if (CAT->getSize().getSExtValue() <= 1) 2789 return; 2790 } else if (!DstArgTy->isVariableArrayType()) { 2791 return; 2792 } 2793 2794 SmallString<128> sizeString; 2795 llvm::raw_svector_ostream OS(sizeString); 2796 OS << "sizeof("; 2797 DstArg->printPretty(OS, Context, 0, getPrintingPolicy()); 2798 OS << ") - "; 2799 OS << "strlen("; 2800 DstArg->printPretty(OS, Context, 0, getPrintingPolicy()); 2801 OS << ") - 1"; 2802 2803 Diag(SL, diag::note_strncat_wrong_size) 2804 << FixItHint::CreateReplacement(SR, OS.str()); 2805} 2806 2807//===--- CHECK: Return Address of Stack Variable --------------------------===// 2808 2809static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars); 2810static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars); 2811 2812/// CheckReturnStackAddr - Check if a return statement returns the address 2813/// of a stack variable. 2814void 2815Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 2816 SourceLocation ReturnLoc) { 2817 2818 Expr *stackE = 0; 2819 SmallVector<DeclRefExpr *, 8> refVars; 2820 2821 // Perform checking for returned stack addresses, local blocks, 2822 // label addresses or references to temporaries. 2823 if (lhsType->isPointerType() || 2824 (!getLangOptions().ObjCAutoRefCount && lhsType->isBlockPointerType())) { 2825 stackE = EvalAddr(RetValExp, refVars); 2826 } else if (lhsType->isReferenceType()) { 2827 stackE = EvalVal(RetValExp, refVars); 2828 } 2829 2830 if (stackE == 0) 2831 return; // Nothing suspicious was found. 2832 2833 SourceLocation diagLoc; 2834 SourceRange diagRange; 2835 if (refVars.empty()) { 2836 diagLoc = stackE->getLocStart(); 2837 diagRange = stackE->getSourceRange(); 2838 } else { 2839 // We followed through a reference variable. 'stackE' contains the 2840 // problematic expression but we will warn at the return statement pointing 2841 // at the reference variable. We will later display the "trail" of 2842 // reference variables using notes. 2843 diagLoc = refVars[0]->getLocStart(); 2844 diagRange = refVars[0]->getSourceRange(); 2845 } 2846 2847 if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. 2848 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref 2849 : diag::warn_ret_stack_addr) 2850 << DR->getDecl()->getDeclName() << diagRange; 2851 } else if (isa<BlockExpr>(stackE)) { // local block. 2852 Diag(diagLoc, diag::err_ret_local_block) << diagRange; 2853 } else if (isa<AddrLabelExpr>(stackE)) { // address of label. 2854 Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; 2855 } else { // local temporary. 2856 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref 2857 : diag::warn_ret_local_temp_addr) 2858 << diagRange; 2859 } 2860 2861 // Display the "trail" of reference variables that we followed until we 2862 // found the problematic expression using notes. 2863 for (unsigned i = 0, e = refVars.size(); i != e; ++i) { 2864 VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); 2865 // If this var binds to another reference var, show the range of the next 2866 // var, otherwise the var binds to the problematic expression, in which case 2867 // show the range of the expression. 2868 SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() 2869 : stackE->getSourceRange(); 2870 Diag(VD->getLocation(), diag::note_ref_var_local_bind) 2871 << VD->getDeclName() << range; 2872 } 2873} 2874 2875/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 2876/// check if the expression in a return statement evaluates to an address 2877/// to a location on the stack, a local block, an address of a label, or a 2878/// reference to local temporary. The recursion is used to traverse the 2879/// AST of the return expression, with recursion backtracking when we 2880/// encounter a subexpression that (1) clearly does not lead to one of the 2881/// above problematic expressions (2) is something we cannot determine leads to 2882/// a problematic expression based on such local checking. 2883/// 2884/// Both EvalAddr and EvalVal follow through reference variables to evaluate 2885/// the expression that they point to. Such variables are added to the 2886/// 'refVars' vector so that we know what the reference variable "trail" was. 2887/// 2888/// EvalAddr processes expressions that are pointers that are used as 2889/// references (and not L-values). EvalVal handles all other values. 2890/// At the base case of the recursion is a check for the above problematic 2891/// expressions. 2892/// 2893/// This implementation handles: 2894/// 2895/// * pointer-to-pointer casts 2896/// * implicit conversions from array references to pointers 2897/// * taking the address of fields 2898/// * arbitrary interplay between "&" and "*" operators 2899/// * pointer arithmetic from an address of a stack variable 2900/// * taking the address of an array element where the array is on the stack 2901static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) { 2902 if (E->isTypeDependent()) 2903 return NULL; 2904 2905 // We should only be called for evaluating pointer expressions. 2906 assert((E->getType()->isAnyPointerType() || 2907 E->getType()->isBlockPointerType() || 2908 E->getType()->isObjCQualifiedIdType()) && 2909 "EvalAddr only works on pointers"); 2910 2911 E = E->IgnoreParens(); 2912 2913 // Our "symbolic interpreter" is just a dispatch off the currently 2914 // viewed AST node. We then recursively traverse the AST by calling 2915 // EvalAddr and EvalVal appropriately. 2916 switch (E->getStmtClass()) { 2917 case Stmt::DeclRefExprClass: { 2918 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2919 2920 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2921 // If this is a reference variable, follow through to the expression that 2922 // it points to. 2923 if (V->hasLocalStorage() && 2924 V->getType()->isReferenceType() && V->hasInit()) { 2925 // Add the reference variable to the "trail". 2926 refVars.push_back(DR); 2927 return EvalAddr(V->getInit(), refVars); 2928 } 2929 2930 return NULL; 2931 } 2932 2933 case Stmt::UnaryOperatorClass: { 2934 // The only unary operator that make sense to handle here 2935 // is AddrOf. All others don't make sense as pointers. 2936 UnaryOperator *U = cast<UnaryOperator>(E); 2937 2938 if (U->getOpcode() == UO_AddrOf) 2939 return EvalVal(U->getSubExpr(), refVars); 2940 else 2941 return NULL; 2942 } 2943 2944 case Stmt::BinaryOperatorClass: { 2945 // Handle pointer arithmetic. All other binary operators are not valid 2946 // in this context. 2947 BinaryOperator *B = cast<BinaryOperator>(E); 2948 BinaryOperatorKind op = B->getOpcode(); 2949 2950 if (op != BO_Add && op != BO_Sub) 2951 return NULL; 2952 2953 Expr *Base = B->getLHS(); 2954 2955 // Determine which argument is the real pointer base. It could be 2956 // the RHS argument instead of the LHS. 2957 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 2958 2959 assert (Base->getType()->isPointerType()); 2960 return EvalAddr(Base, refVars); 2961 } 2962 2963 // For conditional operators we need to see if either the LHS or RHS are 2964 // valid DeclRefExpr*s. If one of them is valid, we return it. 2965 case Stmt::ConditionalOperatorClass: { 2966 ConditionalOperator *C = cast<ConditionalOperator>(E); 2967 2968 // Handle the GNU extension for missing LHS. 2969 if (Expr *lhsExpr = C->getLHS()) { 2970 // In C++, we can have a throw-expression, which has 'void' type. 2971 if (!lhsExpr->getType()->isVoidType()) 2972 if (Expr* LHS = EvalAddr(lhsExpr, refVars)) 2973 return LHS; 2974 } 2975 2976 // In C++, we can have a throw-expression, which has 'void' type. 2977 if (C->getRHS()->getType()->isVoidType()) 2978 return NULL; 2979 2980 return EvalAddr(C->getRHS(), refVars); 2981 } 2982 2983 case Stmt::BlockExprClass: 2984 if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) 2985 return E; // local block. 2986 return NULL; 2987 2988 case Stmt::AddrLabelExprClass: 2989 return E; // address of label. 2990 2991 case Stmt::ExprWithCleanupsClass: 2992 return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars); 2993 2994 // For casts, we need to handle conversions from arrays to 2995 // pointer values, and pointer-to-pointer conversions. 2996 case Stmt::ImplicitCastExprClass: 2997 case Stmt::CStyleCastExprClass: 2998 case Stmt::CXXFunctionalCastExprClass: 2999 case Stmt::ObjCBridgedCastExprClass: { 3000 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 3001 QualType T = SubExpr->getType(); 3002 3003 if (cast<CastExpr>(E)->getCastKind() == CK_CopyAndAutoreleaseBlockObject) 3004 return 0; 3005 else if (SubExpr->getType()->isPointerType() || 3006 SubExpr->getType()->isBlockPointerType() || 3007 SubExpr->getType()->isObjCQualifiedIdType()) 3008 return EvalAddr(SubExpr, refVars); 3009 else if (T->isArrayType()) 3010 return EvalVal(SubExpr, refVars); 3011 else 3012 return 0; 3013 } 3014 3015 // C++ casts. For dynamic casts, static casts, and const casts, we 3016 // are always converting from a pointer-to-pointer, so we just blow 3017 // through the cast. In the case the dynamic cast doesn't fail (and 3018 // return NULL), we take the conservative route and report cases 3019 // where we return the address of a stack variable. For Reinterpre 3020 // FIXME: The comment about is wrong; we're not always converting 3021 // from pointer to pointer. I'm guessing that this code should also 3022 // handle references to objects. 3023 case Stmt::CXXStaticCastExprClass: 3024 case Stmt::CXXDynamicCastExprClass: 3025 case Stmt::CXXConstCastExprClass: 3026 case Stmt::CXXReinterpretCastExprClass: { 3027 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 3028 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 3029 return EvalAddr(S, refVars); 3030 else 3031 return NULL; 3032 } 3033 3034 case Stmt::MaterializeTemporaryExprClass: 3035 if (Expr *Result = EvalAddr( 3036 cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(), 3037 refVars)) 3038 return Result; 3039 3040 return E; 3041 3042 // Everything else: we simply don't reason about them. 3043 default: 3044 return NULL; 3045 } 3046} 3047 3048 3049/// EvalVal - This function is complements EvalAddr in the mutual recursion. 3050/// See the comments for EvalAddr for more details. 3051static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) { 3052do { 3053 // We should only be called for evaluating non-pointer expressions, or 3054 // expressions with a pointer type that are not used as references but instead 3055 // are l-values (e.g., DeclRefExpr with a pointer type). 3056 3057 // Our "symbolic interpreter" is just a dispatch off the currently 3058 // viewed AST node. We then recursively traverse the AST by calling 3059 // EvalAddr and EvalVal appropriately. 3060 3061 E = E->IgnoreParens(); 3062 switch (E->getStmtClass()) { 3063 case Stmt::ImplicitCastExprClass: { 3064 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 3065 if (IE->getValueKind() == VK_LValue) { 3066 E = IE->getSubExpr(); 3067 continue; 3068 } 3069 return NULL; 3070 } 3071 3072 case Stmt::ExprWithCleanupsClass: 3073 return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars); 3074 3075 case Stmt::DeclRefExprClass: { 3076 // When we hit a DeclRefExpr we are looking at code that refers to a 3077 // variable's name. If it's not a reference variable we check if it has 3078 // local storage within the function, and if so, return the expression. 3079 DeclRefExpr *DR = cast<DeclRefExpr>(E); 3080 3081 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 3082 if (V->hasLocalStorage()) { 3083 if (!V->getType()->isReferenceType()) 3084 return DR; 3085 3086 // Reference variable, follow through to the expression that 3087 // it points to. 3088 if (V->hasInit()) { 3089 // Add the reference variable to the "trail". 3090 refVars.push_back(DR); 3091 return EvalVal(V->getInit(), refVars); 3092 } 3093 } 3094 3095 return NULL; 3096 } 3097 3098 case Stmt::UnaryOperatorClass: { 3099 // The only unary operator that make sense to handle here 3100 // is Deref. All others don't resolve to a "name." This includes 3101 // handling all sorts of rvalues passed to a unary operator. 3102 UnaryOperator *U = cast<UnaryOperator>(E); 3103 3104 if (U->getOpcode() == UO_Deref) 3105 return EvalAddr(U->getSubExpr(), refVars); 3106 3107 return NULL; 3108 } 3109 3110 case Stmt::ArraySubscriptExprClass: { 3111 // Array subscripts are potential references to data on the stack. We 3112 // retrieve the DeclRefExpr* for the array variable if it indeed 3113 // has local storage. 3114 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars); 3115 } 3116 3117 case Stmt::ConditionalOperatorClass: { 3118 // For conditional operators we need to see if either the LHS or RHS are 3119 // non-NULL Expr's. If one is non-NULL, we return it. 3120 ConditionalOperator *C = cast<ConditionalOperator>(E); 3121 3122 // Handle the GNU extension for missing LHS. 3123 if (Expr *lhsExpr = C->getLHS()) 3124 if (Expr *LHS = EvalVal(lhsExpr, refVars)) 3125 return LHS; 3126 3127 return EvalVal(C->getRHS(), refVars); 3128 } 3129 3130 // Accesses to members are potential references to data on the stack. 3131 case Stmt::MemberExprClass: { 3132 MemberExpr *M = cast<MemberExpr>(E); 3133 3134 // Check for indirect access. We only want direct field accesses. 3135 if (M->isArrow()) 3136 return NULL; 3137 3138 // Check whether the member type is itself a reference, in which case 3139 // we're not going to refer to the member, but to what the member refers to. 3140 if (M->getMemberDecl()->getType()->isReferenceType()) 3141 return NULL; 3142 3143 return EvalVal(M->getBase(), refVars); 3144 } 3145 3146 case Stmt::MaterializeTemporaryExprClass: 3147 if (Expr *Result = EvalVal( 3148 cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(), 3149 refVars)) 3150 return Result; 3151 3152 return E; 3153 3154 default: 3155 // Check that we don't return or take the address of a reference to a 3156 // temporary. This is only useful in C++. 3157 if (!E->isTypeDependent() && E->isRValue()) 3158 return E; 3159 3160 // Everything else: we simply don't reason about them. 3161 return NULL; 3162 } 3163} while (true); 3164} 3165 3166//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 3167 3168/// Check for comparisons of floating point operands using != and ==. 3169/// Issue a warning if these are no self-comparisons, as they are not likely 3170/// to do what the programmer intended. 3171void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) { 3172 bool EmitWarning = true; 3173 3174 Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts(); 3175 Expr* RightExprSansParen = RHS->IgnoreParenImpCasts(); 3176 3177 // Special case: check for x == x (which is OK). 3178 // Do not emit warnings for such cases. 3179 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 3180 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 3181 if (DRL->getDecl() == DRR->getDecl()) 3182 EmitWarning = false; 3183 3184 3185 // Special case: check for comparisons against literals that can be exactly 3186 // represented by APFloat. In such cases, do not emit a warning. This 3187 // is a heuristic: often comparison against such literals are used to 3188 // detect if a value in a variable has not changed. This clearly can 3189 // lead to false negatives. 3190 if (EmitWarning) { 3191 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 3192 if (FLL->isExact()) 3193 EmitWarning = false; 3194 } else 3195 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 3196 if (FLR->isExact()) 3197 EmitWarning = false; 3198 } 3199 } 3200 3201 // Check for comparisons with builtin types. 3202 if (EmitWarning) 3203 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 3204 if (CL->isBuiltinCall()) 3205 EmitWarning = false; 3206 3207 if (EmitWarning) 3208 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 3209 if (CR->isBuiltinCall()) 3210 EmitWarning = false; 3211 3212 // Emit the diagnostic. 3213 if (EmitWarning) 3214 Diag(Loc, diag::warn_floatingpoint_eq) 3215 << LHS->getSourceRange() << RHS->getSourceRange(); 3216} 3217 3218//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 3219//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 3220 3221namespace { 3222 3223/// Structure recording the 'active' range of an integer-valued 3224/// expression. 3225struct IntRange { 3226 /// The number of bits active in the int. 3227 unsigned Width; 3228 3229 /// True if the int is known not to have negative values. 3230 bool NonNegative; 3231 3232 IntRange(unsigned Width, bool NonNegative) 3233 : Width(Width), NonNegative(NonNegative) 3234 {} 3235 3236 /// Returns the range of the bool type. 3237 static IntRange forBoolType() { 3238 return IntRange(1, true); 3239 } 3240 3241 /// Returns the range of an opaque value of the given integral type. 3242 static IntRange forValueOfType(ASTContext &C, QualType T) { 3243 return forValueOfCanonicalType(C, 3244 T->getCanonicalTypeInternal().getTypePtr()); 3245 } 3246 3247 /// Returns the range of an opaque value of a canonical integral type. 3248 static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) { 3249 assert(T->isCanonicalUnqualified()); 3250 3251 if (const VectorType *VT = dyn_cast<VectorType>(T)) 3252 T = VT->getElementType().getTypePtr(); 3253 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 3254 T = CT->getElementType().getTypePtr(); 3255 3256 // For enum types, use the known bit width of the enumerators. 3257 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 3258 EnumDecl *Enum = ET->getDecl(); 3259 if (!Enum->isCompleteDefinition()) 3260 return IntRange(C.getIntWidth(QualType(T, 0)), false); 3261 3262 unsigned NumPositive = Enum->getNumPositiveBits(); 3263 unsigned NumNegative = Enum->getNumNegativeBits(); 3264 3265 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 3266 } 3267 3268 const BuiltinType *BT = cast<BuiltinType>(T); 3269 assert(BT->isInteger()); 3270 3271 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 3272 } 3273 3274 /// Returns the "target" range of a canonical integral type, i.e. 3275 /// the range of values expressible in the type. 3276 /// 3277 /// This matches forValueOfCanonicalType except that enums have the 3278 /// full range of their type, not the range of their enumerators. 3279 static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) { 3280 assert(T->isCanonicalUnqualified()); 3281 3282 if (const VectorType *VT = dyn_cast<VectorType>(T)) 3283 T = VT->getElementType().getTypePtr(); 3284 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 3285 T = CT->getElementType().getTypePtr(); 3286 if (const EnumType *ET = dyn_cast<EnumType>(T)) 3287 T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr(); 3288 3289 const BuiltinType *BT = cast<BuiltinType>(T); 3290 assert(BT->isInteger()); 3291 3292 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 3293 } 3294 3295 /// Returns the supremum of two ranges: i.e. their conservative merge. 3296 static IntRange join(IntRange L, IntRange R) { 3297 return IntRange(std::max(L.Width, R.Width), 3298 L.NonNegative && R.NonNegative); 3299 } 3300 3301 /// Returns the infinum of two ranges: i.e. their aggressive merge. 3302 static IntRange meet(IntRange L, IntRange R) { 3303 return IntRange(std::min(L.Width, R.Width), 3304 L.NonNegative || R.NonNegative); 3305 } 3306}; 3307 3308static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, 3309 unsigned MaxWidth) { 3310 if (value.isSigned() && value.isNegative()) 3311 return IntRange(value.getMinSignedBits(), false); 3312 3313 if (value.getBitWidth() > MaxWidth) 3314 value = value.trunc(MaxWidth); 3315 3316 // isNonNegative() just checks the sign bit without considering 3317 // signedness. 3318 return IntRange(value.getActiveBits(), true); 3319} 3320 3321static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 3322 unsigned MaxWidth) { 3323 if (result.isInt()) 3324 return GetValueRange(C, result.getInt(), MaxWidth); 3325 3326 if (result.isVector()) { 3327 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 3328 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 3329 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 3330 R = IntRange::join(R, El); 3331 } 3332 return R; 3333 } 3334 3335 if (result.isComplexInt()) { 3336 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 3337 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 3338 return IntRange::join(R, I); 3339 } 3340 3341 // This can happen with lossless casts to intptr_t of "based" lvalues. 3342 // Assume it might use arbitrary bits. 3343 // FIXME: The only reason we need to pass the type in here is to get 3344 // the sign right on this one case. It would be nice if APValue 3345 // preserved this. 3346 assert(result.isLValue() || result.isAddrLabelDiff()); 3347 return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType()); 3348} 3349 3350/// Pseudo-evaluate the given integer expression, estimating the 3351/// range of values it might take. 3352/// 3353/// \param MaxWidth - the width to which the value will be truncated 3354static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 3355 E = E->IgnoreParens(); 3356 3357 // Try a full evaluation first. 3358 Expr::EvalResult result; 3359 if (E->EvaluateAsRValue(result, C)) 3360 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 3361 3362 // I think we only want to look through implicit casts here; if the 3363 // user has an explicit widening cast, we should treat the value as 3364 // being of the new, wider type. 3365 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 3366 if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue) 3367 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 3368 3369 IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); 3370 3371 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 3372 3373 // Assume that non-integer casts can span the full range of the type. 3374 if (!isIntegerCast) 3375 return OutputTypeRange; 3376 3377 IntRange SubRange 3378 = GetExprRange(C, CE->getSubExpr(), 3379 std::min(MaxWidth, OutputTypeRange.Width)); 3380 3381 // Bail out if the subexpr's range is as wide as the cast type. 3382 if (SubRange.Width >= OutputTypeRange.Width) 3383 return OutputTypeRange; 3384 3385 // Otherwise, we take the smaller width, and we're non-negative if 3386 // either the output type or the subexpr is. 3387 return IntRange(SubRange.Width, 3388 SubRange.NonNegative || OutputTypeRange.NonNegative); 3389 } 3390 3391 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 3392 // If we can fold the condition, just take that operand. 3393 bool CondResult; 3394 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 3395 return GetExprRange(C, CondResult ? CO->getTrueExpr() 3396 : CO->getFalseExpr(), 3397 MaxWidth); 3398 3399 // Otherwise, conservatively merge. 3400 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 3401 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 3402 return IntRange::join(L, R); 3403 } 3404 3405 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 3406 switch (BO->getOpcode()) { 3407 3408 // Boolean-valued operations are single-bit and positive. 3409 case BO_LAnd: 3410 case BO_LOr: 3411 case BO_LT: 3412 case BO_GT: 3413 case BO_LE: 3414 case BO_GE: 3415 case BO_EQ: 3416 case BO_NE: 3417 return IntRange::forBoolType(); 3418 3419 // The type of the assignments is the type of the LHS, so the RHS 3420 // is not necessarily the same type. 3421 case BO_MulAssign: 3422 case BO_DivAssign: 3423 case BO_RemAssign: 3424 case BO_AddAssign: 3425 case BO_SubAssign: 3426 case BO_XorAssign: 3427 case BO_OrAssign: 3428 // TODO: bitfields? 3429 return IntRange::forValueOfType(C, E->getType()); 3430 3431 // Simple assignments just pass through the RHS, which will have 3432 // been coerced to the LHS type. 3433 case BO_Assign: 3434 // TODO: bitfields? 3435 return GetExprRange(C, BO->getRHS(), MaxWidth); 3436 3437 // Operations with opaque sources are black-listed. 3438 case BO_PtrMemD: 3439 case BO_PtrMemI: 3440 return IntRange::forValueOfType(C, E->getType()); 3441 3442 // Bitwise-and uses the *infinum* of the two source ranges. 3443 case BO_And: 3444 case BO_AndAssign: 3445 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 3446 GetExprRange(C, BO->getRHS(), MaxWidth)); 3447 3448 // Left shift gets black-listed based on a judgement call. 3449 case BO_Shl: 3450 // ...except that we want to treat '1 << (blah)' as logically 3451 // positive. It's an important idiom. 3452 if (IntegerLiteral *I 3453 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 3454 if (I->getValue() == 1) { 3455 IntRange R = IntRange::forValueOfType(C, E->getType()); 3456 return IntRange(R.Width, /*NonNegative*/ true); 3457 } 3458 } 3459 // fallthrough 3460 3461 case BO_ShlAssign: 3462 return IntRange::forValueOfType(C, E->getType()); 3463 3464 // Right shift by a constant can narrow its left argument. 3465 case BO_Shr: 3466 case BO_ShrAssign: { 3467 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 3468 3469 // If the shift amount is a positive constant, drop the width by 3470 // that much. 3471 llvm::APSInt shift; 3472 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 3473 shift.isNonNegative()) { 3474 unsigned zext = shift.getZExtValue(); 3475 if (zext >= L.Width) 3476 L.Width = (L.NonNegative ? 0 : 1); 3477 else 3478 L.Width -= zext; 3479 } 3480 3481 return L; 3482 } 3483 3484 // Comma acts as its right operand. 3485 case BO_Comma: 3486 return GetExprRange(C, BO->getRHS(), MaxWidth); 3487 3488 // Black-list pointer subtractions. 3489 case BO_Sub: 3490 if (BO->getLHS()->getType()->isPointerType()) 3491 return IntRange::forValueOfType(C, E->getType()); 3492 break; 3493 3494 // The width of a division result is mostly determined by the size 3495 // of the LHS. 3496 case BO_Div: { 3497 // Don't 'pre-truncate' the operands. 3498 unsigned opWidth = C.getIntWidth(E->getType()); 3499 IntRange L = GetExprRange(C, BO->getLHS(), opWidth); 3500 3501 // If the divisor is constant, use that. 3502 llvm::APSInt divisor; 3503 if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) { 3504 unsigned log2 = divisor.logBase2(); // floor(log_2(divisor)) 3505 if (log2 >= L.Width) 3506 L.Width = (L.NonNegative ? 0 : 1); 3507 else 3508 L.Width = std::min(L.Width - log2, MaxWidth); 3509 return L; 3510 } 3511 3512 // Otherwise, just use the LHS's width. 3513 IntRange R = GetExprRange(C, BO->getRHS(), opWidth); 3514 return IntRange(L.Width, L.NonNegative && R.NonNegative); 3515 } 3516 3517 // The result of a remainder can't be larger than the result of 3518 // either side. 3519 case BO_Rem: { 3520 // Don't 'pre-truncate' the operands. 3521 unsigned opWidth = C.getIntWidth(E->getType()); 3522 IntRange L = GetExprRange(C, BO->getLHS(), opWidth); 3523 IntRange R = GetExprRange(C, BO->getRHS(), opWidth); 3524 3525 IntRange meet = IntRange::meet(L, R); 3526 meet.Width = std::min(meet.Width, MaxWidth); 3527 return meet; 3528 } 3529 3530 // The default behavior is okay for these. 3531 case BO_Mul: 3532 case BO_Add: 3533 case BO_Xor: 3534 case BO_Or: 3535 break; 3536 } 3537 3538 // The default case is to treat the operation as if it were closed 3539 // on the narrowest type that encompasses both operands. 3540 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 3541 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 3542 return IntRange::join(L, R); 3543 } 3544 3545 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 3546 switch (UO->getOpcode()) { 3547 // Boolean-valued operations are white-listed. 3548 case UO_LNot: 3549 return IntRange::forBoolType(); 3550 3551 // Operations with opaque sources are black-listed. 3552 case UO_Deref: 3553 case UO_AddrOf: // should be impossible 3554 return IntRange::forValueOfType(C, E->getType()); 3555 3556 default: 3557 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 3558 } 3559 } 3560 3561 if (dyn_cast<OffsetOfExpr>(E)) { 3562 IntRange::forValueOfType(C, E->getType()); 3563 } 3564 3565 if (FieldDecl *BitField = E->getBitField()) 3566 return IntRange(BitField->getBitWidthValue(C), 3567 BitField->getType()->isUnsignedIntegerOrEnumerationType()); 3568 3569 return IntRange::forValueOfType(C, E->getType()); 3570} 3571 3572static IntRange GetExprRange(ASTContext &C, Expr *E) { 3573 return GetExprRange(C, E, C.getIntWidth(E->getType())); 3574} 3575 3576/// Checks whether the given value, which currently has the given 3577/// source semantics, has the same value when coerced through the 3578/// target semantics. 3579static bool IsSameFloatAfterCast(const llvm::APFloat &value, 3580 const llvm::fltSemantics &Src, 3581 const llvm::fltSemantics &Tgt) { 3582 llvm::APFloat truncated = value; 3583 3584 bool ignored; 3585 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 3586 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 3587 3588 return truncated.bitwiseIsEqual(value); 3589} 3590 3591/// Checks whether the given value, which currently has the given 3592/// source semantics, has the same value when coerced through the 3593/// target semantics. 3594/// 3595/// The value might be a vector of floats (or a complex number). 3596static bool IsSameFloatAfterCast(const APValue &value, 3597 const llvm::fltSemantics &Src, 3598 const llvm::fltSemantics &Tgt) { 3599 if (value.isFloat()) 3600 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 3601 3602 if (value.isVector()) { 3603 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 3604 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 3605 return false; 3606 return true; 3607 } 3608 3609 assert(value.isComplexFloat()); 3610 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 3611 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 3612} 3613 3614static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC); 3615 3616static bool IsZero(Sema &S, Expr *E) { 3617 // Suppress cases where we are comparing against an enum constant. 3618 if (const DeclRefExpr *DR = 3619 dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) 3620 if (isa<EnumConstantDecl>(DR->getDecl())) 3621 return false; 3622 3623 // Suppress cases where the '0' value is expanded from a macro. 3624 if (E->getLocStart().isMacroID()) 3625 return false; 3626 3627 llvm::APSInt Value; 3628 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 3629} 3630 3631static bool HasEnumType(Expr *E) { 3632 // Strip off implicit integral promotions. 3633 while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { 3634 if (ICE->getCastKind() != CK_IntegralCast && 3635 ICE->getCastKind() != CK_NoOp) 3636 break; 3637 E = ICE->getSubExpr(); 3638 } 3639 3640 return E->getType()->isEnumeralType(); 3641} 3642 3643static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 3644 BinaryOperatorKind op = E->getOpcode(); 3645 if (E->isValueDependent()) 3646 return; 3647 3648 if (op == BO_LT && IsZero(S, E->getRHS())) { 3649 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 3650 << "< 0" << "false" << HasEnumType(E->getLHS()) 3651 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3652 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 3653 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 3654 << ">= 0" << "true" << HasEnumType(E->getLHS()) 3655 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3656 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 3657 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 3658 << "0 >" << "false" << HasEnumType(E->getRHS()) 3659 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3660 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 3661 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 3662 << "0 <=" << "true" << HasEnumType(E->getRHS()) 3663 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3664 } 3665} 3666 3667/// Analyze the operands of the given comparison. Implements the 3668/// fallback case from AnalyzeComparison. 3669static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 3670 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 3671 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 3672} 3673 3674/// \brief Implements -Wsign-compare. 3675/// 3676/// \param E the binary operator to check for warnings 3677static void AnalyzeComparison(Sema &S, BinaryOperator *E) { 3678 // The type the comparison is being performed in. 3679 QualType T = E->getLHS()->getType(); 3680 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 3681 && "comparison with mismatched types"); 3682 3683 // We don't do anything special if this isn't an unsigned integral 3684 // comparison: we're only interested in integral comparisons, and 3685 // signed comparisons only happen in cases we don't care to warn about. 3686 // 3687 // We also don't care about value-dependent expressions or expressions 3688 // whose result is a constant. 3689 if (!T->hasUnsignedIntegerRepresentation() 3690 || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) 3691 return AnalyzeImpConvsInComparison(S, E); 3692 3693 Expr *LHS = E->getLHS()->IgnoreParenImpCasts(); 3694 Expr *RHS = E->getRHS()->IgnoreParenImpCasts(); 3695 3696 // Check to see if one of the (unmodified) operands is of different 3697 // signedness. 3698 Expr *signedOperand, *unsignedOperand; 3699 if (LHS->getType()->hasSignedIntegerRepresentation()) { 3700 assert(!RHS->getType()->hasSignedIntegerRepresentation() && 3701 "unsigned comparison between two signed integer expressions?"); 3702 signedOperand = LHS; 3703 unsignedOperand = RHS; 3704 } else if (RHS->getType()->hasSignedIntegerRepresentation()) { 3705 signedOperand = RHS; 3706 unsignedOperand = LHS; 3707 } else { 3708 CheckTrivialUnsignedComparison(S, E); 3709 return AnalyzeImpConvsInComparison(S, E); 3710 } 3711 3712 // Otherwise, calculate the effective range of the signed operand. 3713 IntRange signedRange = GetExprRange(S.Context, signedOperand); 3714 3715 // Go ahead and analyze implicit conversions in the operands. Note 3716 // that we skip the implicit conversions on both sides. 3717 AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc()); 3718 AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc()); 3719 3720 // If the signed range is non-negative, -Wsign-compare won't fire, 3721 // but we should still check for comparisons which are always true 3722 // or false. 3723 if (signedRange.NonNegative) 3724 return CheckTrivialUnsignedComparison(S, E); 3725 3726 // For (in)equality comparisons, if the unsigned operand is a 3727 // constant which cannot collide with a overflowed signed operand, 3728 // then reinterpreting the signed operand as unsigned will not 3729 // change the result of the comparison. 3730 if (E->isEqualityOp()) { 3731 unsigned comparisonWidth = S.Context.getIntWidth(T); 3732 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 3733 3734 // We should never be unable to prove that the unsigned operand is 3735 // non-negative. 3736 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 3737 3738 if (unsignedRange.Width < comparisonWidth) 3739 return; 3740 } 3741 3742 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 3743 << LHS->getType() << RHS->getType() 3744 << LHS->getSourceRange() << RHS->getSourceRange(); 3745} 3746 3747/// Analyzes an attempt to assign the given value to a bitfield. 3748/// 3749/// Returns true if there was something fishy about the attempt. 3750static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, 3751 SourceLocation InitLoc) { 3752 assert(Bitfield->isBitField()); 3753 if (Bitfield->isInvalidDecl()) 3754 return false; 3755 3756 // White-list bool bitfields. 3757 if (Bitfield->getType()->isBooleanType()) 3758 return false; 3759 3760 // Ignore value- or type-dependent expressions. 3761 if (Bitfield->getBitWidth()->isValueDependent() || 3762 Bitfield->getBitWidth()->isTypeDependent() || 3763 Init->isValueDependent() || 3764 Init->isTypeDependent()) 3765 return false; 3766 3767 Expr *OriginalInit = Init->IgnoreParenImpCasts(); 3768 3769 llvm::APSInt Value; 3770 if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) 3771 return false; 3772 3773 unsigned OriginalWidth = Value.getBitWidth(); 3774 unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context); 3775 3776 if (OriginalWidth <= FieldWidth) 3777 return false; 3778 3779 // Compute the value which the bitfield will contain. 3780 llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); 3781 TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType()); 3782 3783 // Check whether the stored value is equal to the original value. 3784 TruncatedValue = TruncatedValue.extend(OriginalWidth); 3785 if (Value == TruncatedValue) 3786 return false; 3787 3788 // Special-case bitfields of width 1: booleans are naturally 0/1, and 3789 // therefore don't strictly fit into a signed bitfield of width 1. 3790 if (FieldWidth == 1 && Value == 1) 3791 return false; 3792 3793 std::string PrettyValue = Value.toString(10); 3794 std::string PrettyTrunc = TruncatedValue.toString(10); 3795 3796 S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) 3797 << PrettyValue << PrettyTrunc << OriginalInit->getType() 3798 << Init->getSourceRange(); 3799 3800 return true; 3801} 3802 3803/// Analyze the given simple or compound assignment for warning-worthy 3804/// operations. 3805static void AnalyzeAssignment(Sema &S, BinaryOperator *E) { 3806 // Just recurse on the LHS. 3807 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 3808 3809 // We want to recurse on the RHS as normal unless we're assigning to 3810 // a bitfield. 3811 if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { 3812 if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), 3813 E->getOperatorLoc())) { 3814 // Recurse, ignoring any implicit conversions on the RHS. 3815 return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), 3816 E->getOperatorLoc()); 3817 } 3818 } 3819 3820 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 3821} 3822 3823/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 3824static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 3825 SourceLocation CContext, unsigned diag, 3826 bool pruneControlFlow = false) { 3827 if (pruneControlFlow) { 3828 S.DiagRuntimeBehavior(E->getExprLoc(), E, 3829 S.PDiag(diag) 3830 << SourceType << T << E->getSourceRange() 3831 << SourceRange(CContext)); 3832 return; 3833 } 3834 S.Diag(E->getExprLoc(), diag) 3835 << SourceType << T << E->getSourceRange() << SourceRange(CContext); 3836} 3837 3838/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 3839static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, 3840 SourceLocation CContext, unsigned diag, 3841 bool pruneControlFlow = false) { 3842 DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow); 3843} 3844 3845/// Diagnose an implicit cast from a literal expression. Does not warn when the 3846/// cast wouldn't lose information. 3847void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T, 3848 SourceLocation CContext) { 3849 // Try to convert the literal exactly to an integer. If we can, don't warn. 3850 bool isExact = false; 3851 const llvm::APFloat &Value = FL->getValue(); 3852 llvm::APSInt IntegerValue(S.Context.getIntWidth(T), 3853 T->hasUnsignedIntegerRepresentation()); 3854 if (Value.convertToInteger(IntegerValue, 3855 llvm::APFloat::rmTowardZero, &isExact) 3856 == llvm::APFloat::opOK && isExact) 3857 return; 3858 3859 S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer) 3860 << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext); 3861} 3862 3863std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { 3864 if (!Range.Width) return "0"; 3865 3866 llvm::APSInt ValueInRange = Value; 3867 ValueInRange.setIsSigned(!Range.NonNegative); 3868 ValueInRange = ValueInRange.trunc(Range.Width); 3869 return ValueInRange.toString(10); 3870} 3871 3872void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 3873 SourceLocation CC, bool *ICContext = 0) { 3874 if (E->isTypeDependent() || E->isValueDependent()) return; 3875 3876 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 3877 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 3878 if (Source == Target) return; 3879 if (Target->isDependentType()) return; 3880 3881 // If the conversion context location is invalid don't complain. We also 3882 // don't want to emit a warning if the issue occurs from the expansion of 3883 // a system macro. The problem is that 'getSpellingLoc()' is slow, so we 3884 // delay this check as long as possible. Once we detect we are in that 3885 // scenario, we just return. 3886 if (CC.isInvalid()) 3887 return; 3888 3889 // Diagnose implicit casts to bool. 3890 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) { 3891 if (isa<StringLiteral>(E)) 3892 // Warn on string literal to bool. Checks for string literals in logical 3893 // expressions, for instances, assert(0 && "error here"), is prevented 3894 // by a check in AnalyzeImplicitConversions(). 3895 return DiagnoseImpCast(S, E, T, CC, 3896 diag::warn_impcast_string_literal_to_bool); 3897 if (Source->isFunctionType()) { 3898 // Warn on function to bool. Checks free functions and static member 3899 // functions. Weakly imported functions are excluded from the check, 3900 // since it's common to test their value to check whether the linker 3901 // found a definition for them. 3902 ValueDecl *D = 0; 3903 if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) { 3904 D = R->getDecl(); 3905 } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) { 3906 D = M->getMemberDecl(); 3907 } 3908 3909 if (D && !D->isWeak()) { 3910 if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) { 3911 S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool) 3912 << F << E->getSourceRange() << SourceRange(CC); 3913 S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence) 3914 << FixItHint::CreateInsertion(E->getExprLoc(), "&"); 3915 QualType ReturnType; 3916 UnresolvedSet<4> NonTemplateOverloads; 3917 S.isExprCallable(*E, ReturnType, NonTemplateOverloads); 3918 if (!ReturnType.isNull() 3919 && ReturnType->isSpecificBuiltinType(BuiltinType::Bool)) 3920 S.Diag(E->getExprLoc(), diag::note_function_to_bool_call) 3921 << FixItHint::CreateInsertion( 3922 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()"); 3923 return; 3924 } 3925 } 3926 } 3927 return; // Other casts to bool are not checked. 3928 } 3929 3930 // Strip vector types. 3931 if (isa<VectorType>(Source)) { 3932 if (!isa<VectorType>(Target)) { 3933 if (S.SourceMgr.isInSystemMacro(CC)) 3934 return; 3935 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar); 3936 } 3937 3938 // If the vector cast is cast between two vectors of the same size, it is 3939 // a bitcast, not a conversion. 3940 if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target)) 3941 return; 3942 3943 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 3944 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 3945 } 3946 3947 // Strip complex types. 3948 if (isa<ComplexType>(Source)) { 3949 if (!isa<ComplexType>(Target)) { 3950 if (S.SourceMgr.isInSystemMacro(CC)) 3951 return; 3952 3953 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar); 3954 } 3955 3956 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 3957 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 3958 } 3959 3960 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 3961 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 3962 3963 // If the source is floating point... 3964 if (SourceBT && SourceBT->isFloatingPoint()) { 3965 // ...and the target is floating point... 3966 if (TargetBT && TargetBT->isFloatingPoint()) { 3967 // ...then warn if we're dropping FP rank. 3968 3969 // Builtin FP kinds are ordered by increasing FP rank. 3970 if (SourceBT->getKind() > TargetBT->getKind()) { 3971 // Don't warn about float constants that are precisely 3972 // representable in the target type. 3973 Expr::EvalResult result; 3974 if (E->EvaluateAsRValue(result, S.Context)) { 3975 // Value might be a float, a float vector, or a float complex. 3976 if (IsSameFloatAfterCast(result.Val, 3977 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 3978 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 3979 return; 3980 } 3981 3982 if (S.SourceMgr.isInSystemMacro(CC)) 3983 return; 3984 3985 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision); 3986 } 3987 return; 3988 } 3989 3990 // If the target is integral, always warn. 3991 if ((TargetBT && TargetBT->isInteger())) { 3992 if (S.SourceMgr.isInSystemMacro(CC)) 3993 return; 3994 3995 Expr *InnerE = E->IgnoreParenImpCasts(); 3996 // We also want to warn on, e.g., "int i = -1.234" 3997 if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE)) 3998 if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus) 3999 InnerE = UOp->getSubExpr()->IgnoreParenImpCasts(); 4000 4001 if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) { 4002 DiagnoseFloatingLiteralImpCast(S, FL, T, CC); 4003 } else { 4004 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); 4005 } 4006 } 4007 4008 return; 4009 } 4010 4011 if (!Source->isIntegerType() || !Target->isIntegerType()) 4012 return; 4013 4014 if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull) 4015 == Expr::NPCK_GNUNull) && Target->isIntegerType()) { 4016 S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer) 4017 << E->getSourceRange() << clang::SourceRange(CC); 4018 return; 4019 } 4020 4021 IntRange SourceRange = GetExprRange(S.Context, E); 4022 IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); 4023 4024 if (SourceRange.Width > TargetRange.Width) { 4025 // If the source is a constant, use a default-on diagnostic. 4026 // TODO: this should happen for bitfield stores, too. 4027 llvm::APSInt Value(32); 4028 if (E->isIntegerConstantExpr(Value, S.Context)) { 4029 if (S.SourceMgr.isInSystemMacro(CC)) 4030 return; 4031 4032 std::string PrettySourceValue = Value.toString(10); 4033 std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); 4034 4035 S.DiagRuntimeBehavior(E->getExprLoc(), E, 4036 S.PDiag(diag::warn_impcast_integer_precision_constant) 4037 << PrettySourceValue << PrettyTargetValue 4038 << E->getType() << T << E->getSourceRange() 4039 << clang::SourceRange(CC)); 4040 return; 4041 } 4042 4043 // People want to build with -Wshorten-64-to-32 and not -Wconversion. 4044 if (S.SourceMgr.isInSystemMacro(CC)) 4045 return; 4046 4047 if (SourceRange.Width == 64 && TargetRange.Width == 32) 4048 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32, 4049 /* pruneControlFlow */ true); 4050 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); 4051 } 4052 4053 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 4054 (!TargetRange.NonNegative && SourceRange.NonNegative && 4055 SourceRange.Width == TargetRange.Width)) { 4056 4057 if (S.SourceMgr.isInSystemMacro(CC)) 4058 return; 4059 4060 unsigned DiagID = diag::warn_impcast_integer_sign; 4061 4062 // Traditionally, gcc has warned about this under -Wsign-compare. 4063 // We also want to warn about it in -Wconversion. 4064 // So if -Wconversion is off, use a completely identical diagnostic 4065 // in the sign-compare group. 4066 // The conditional-checking code will 4067 if (ICContext) { 4068 DiagID = diag::warn_impcast_integer_sign_conditional; 4069 *ICContext = true; 4070 } 4071 4072 return DiagnoseImpCast(S, E, T, CC, DiagID); 4073 } 4074 4075 // Diagnose conversions between different enumeration types. 4076 // In C, we pretend that the type of an EnumConstantDecl is its enumeration 4077 // type, to give us better diagnostics. 4078 QualType SourceType = E->getType(); 4079 if (!S.getLangOptions().CPlusPlus) { 4080 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 4081 if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) { 4082 EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext()); 4083 SourceType = S.Context.getTypeDeclType(Enum); 4084 Source = S.Context.getCanonicalType(SourceType).getTypePtr(); 4085 } 4086 } 4087 4088 if (const EnumType *SourceEnum = Source->getAs<EnumType>()) 4089 if (const EnumType *TargetEnum = Target->getAs<EnumType>()) 4090 if ((SourceEnum->getDecl()->getIdentifier() || 4091 SourceEnum->getDecl()->getTypedefNameForAnonDecl()) && 4092 (TargetEnum->getDecl()->getIdentifier() || 4093 TargetEnum->getDecl()->getTypedefNameForAnonDecl()) && 4094 SourceEnum != TargetEnum) { 4095 if (S.SourceMgr.isInSystemMacro(CC)) 4096 return; 4097 4098 return DiagnoseImpCast(S, E, SourceType, T, CC, 4099 diag::warn_impcast_different_enum_types); 4100 } 4101 4102 return; 4103} 4104 4105void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 4106 4107void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 4108 SourceLocation CC, bool &ICContext) { 4109 E = E->IgnoreParenImpCasts(); 4110 4111 if (isa<ConditionalOperator>(E)) 4112 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 4113 4114 AnalyzeImplicitConversions(S, E, CC); 4115 if (E->getType() != T) 4116 return CheckImplicitConversion(S, E, T, CC, &ICContext); 4117 return; 4118} 4119 4120void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 4121 SourceLocation CC = E->getQuestionLoc(); 4122 4123 AnalyzeImplicitConversions(S, E->getCond(), CC); 4124 4125 bool Suspicious = false; 4126 CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); 4127 CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious); 4128 4129 // If -Wconversion would have warned about either of the candidates 4130 // for a signedness conversion to the context type... 4131 if (!Suspicious) return; 4132 4133 // ...but it's currently ignored... 4134 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional, 4135 CC)) 4136 return; 4137 4138 // ...then check whether it would have warned about either of the 4139 // candidates for a signedness conversion to the condition type. 4140 if (E->getType() == T) return; 4141 4142 Suspicious = false; 4143 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 4144 E->getType(), CC, &Suspicious); 4145 if (!Suspicious) 4146 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 4147 E->getType(), CC, &Suspicious); 4148} 4149 4150/// AnalyzeImplicitConversions - Find and report any interesting 4151/// implicit conversions in the given expression. There are a couple 4152/// of competing diagnostics here, -Wconversion and -Wsign-compare. 4153void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) { 4154 QualType T = OrigE->getType(); 4155 Expr *E = OrigE->IgnoreParenImpCasts(); 4156 4157 if (E->isTypeDependent() || E->isValueDependent()) 4158 return; 4159 4160 // For conditional operators, we analyze the arguments as if they 4161 // were being fed directly into the output. 4162 if (isa<ConditionalOperator>(E)) { 4163 ConditionalOperator *CO = cast<ConditionalOperator>(E); 4164 CheckConditionalOperator(S, CO, T); 4165 return; 4166 } 4167 4168 // Go ahead and check any implicit conversions we might have skipped. 4169 // The non-canonical typecheck is just an optimization; 4170 // CheckImplicitConversion will filter out dead implicit conversions. 4171 if (E->getType() != T) 4172 CheckImplicitConversion(S, E, T, CC); 4173 4174 // Now continue drilling into this expression. 4175 4176 // Skip past explicit casts. 4177 if (isa<ExplicitCastExpr>(E)) { 4178 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 4179 return AnalyzeImplicitConversions(S, E, CC); 4180 } 4181 4182 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 4183 // Do a somewhat different check with comparison operators. 4184 if (BO->isComparisonOp()) 4185 return AnalyzeComparison(S, BO); 4186 4187 // And with simple assignments. 4188 if (BO->getOpcode() == BO_Assign) 4189 return AnalyzeAssignment(S, BO); 4190 } 4191 4192 // These break the otherwise-useful invariant below. Fortunately, 4193 // we don't really need to recurse into them, because any internal 4194 // expressions should have been analyzed already when they were 4195 // built into statements. 4196 if (isa<StmtExpr>(E)) return; 4197 4198 // Don't descend into unevaluated contexts. 4199 if (isa<UnaryExprOrTypeTraitExpr>(E)) return; 4200 4201 // Now just recurse over the expression's children. 4202 CC = E->getExprLoc(); 4203 BinaryOperator *BO = dyn_cast<BinaryOperator>(E); 4204 bool IsLogicalOperator = BO && BO->isLogicalOp(); 4205 for (Stmt::child_range I = E->children(); I; ++I) { 4206 Expr *ChildExpr = dyn_cast_or_null<Expr>(*I); 4207 if (!ChildExpr) 4208 continue; 4209 4210 if (IsLogicalOperator && 4211 isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts())) 4212 // Ignore checking string literals that are in logical operators. 4213 continue; 4214 AnalyzeImplicitConversions(S, ChildExpr, CC); 4215 } 4216} 4217 4218} // end anonymous namespace 4219 4220/// Diagnoses "dangerous" implicit conversions within the given 4221/// expression (which is a full expression). Implements -Wconversion 4222/// and -Wsign-compare. 4223/// 4224/// \param CC the "context" location of the implicit conversion, i.e. 4225/// the most location of the syntactic entity requiring the implicit 4226/// conversion 4227void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { 4228 // Don't diagnose in unevaluated contexts. 4229 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 4230 return; 4231 4232 // Don't diagnose for value- or type-dependent expressions. 4233 if (E->isTypeDependent() || E->isValueDependent()) 4234 return; 4235 4236 // Check for array bounds violations in cases where the check isn't triggered 4237 // elsewhere for other Expr types (like BinaryOperators), e.g. when an 4238 // ArraySubscriptExpr is on the RHS of a variable initialization. 4239 CheckArrayAccess(E); 4240 4241 // This is not the right CC for (e.g.) a variable initialization. 4242 AnalyzeImplicitConversions(*this, E, CC); 4243} 4244 4245void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, 4246 FieldDecl *BitField, 4247 Expr *Init) { 4248 (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); 4249} 4250 4251/// CheckParmsForFunctionDef - Check that the parameters of the given 4252/// function are appropriate for the definition of a function. This 4253/// takes care of any checks that cannot be performed on the 4254/// declaration itself, e.g., that the types of each of the function 4255/// parameters are complete. 4256bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd, 4257 bool CheckParameterNames) { 4258 bool HasInvalidParm = false; 4259 for (; P != PEnd; ++P) { 4260 ParmVarDecl *Param = *P; 4261 4262 // C99 6.7.5.3p4: the parameters in a parameter type list in a 4263 // function declarator that is part of a function definition of 4264 // that function shall not have incomplete type. 4265 // 4266 // This is also C++ [dcl.fct]p6. 4267 if (!Param->isInvalidDecl() && 4268 RequireCompleteType(Param->getLocation(), Param->getType(), 4269 diag::err_typecheck_decl_incomplete_type)) { 4270 Param->setInvalidDecl(); 4271 HasInvalidParm = true; 4272 } 4273 4274 // C99 6.9.1p5: If the declarator includes a parameter type list, the 4275 // declaration of each parameter shall include an identifier. 4276 if (CheckParameterNames && 4277 Param->getIdentifier() == 0 && 4278 !Param->isImplicit() && 4279 !getLangOptions().CPlusPlus) 4280 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 4281 4282 // C99 6.7.5.3p12: 4283 // If the function declarator is not part of a definition of that 4284 // function, parameters may have incomplete type and may use the [*] 4285 // notation in their sequences of declarator specifiers to specify 4286 // variable length array types. 4287 QualType PType = Param->getOriginalType(); 4288 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 4289 if (AT->getSizeModifier() == ArrayType::Star) { 4290 // FIXME: This diagnosic should point the the '[*]' if source-location 4291 // information is added for it. 4292 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 4293 } 4294 } 4295 } 4296 4297 return HasInvalidParm; 4298} 4299 4300/// CheckCastAlign - Implements -Wcast-align, which warns when a 4301/// pointer cast increases the alignment requirements. 4302void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 4303 // This is actually a lot of work to potentially be doing on every 4304 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 4305 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, 4306 TRange.getBegin()) 4307 == DiagnosticsEngine::Ignored) 4308 return; 4309 4310 // Ignore dependent types. 4311 if (T->isDependentType() || Op->getType()->isDependentType()) 4312 return; 4313 4314 // Require that the destination be a pointer type. 4315 const PointerType *DestPtr = T->getAs<PointerType>(); 4316 if (!DestPtr) return; 4317 4318 // If the destination has alignment 1, we're done. 4319 QualType DestPointee = DestPtr->getPointeeType(); 4320 if (DestPointee->isIncompleteType()) return; 4321 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 4322 if (DestAlign.isOne()) return; 4323 4324 // Require that the source be a pointer type. 4325 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 4326 if (!SrcPtr) return; 4327 QualType SrcPointee = SrcPtr->getPointeeType(); 4328 4329 // Whitelist casts from cv void*. We already implicitly 4330 // whitelisted casts to cv void*, since they have alignment 1. 4331 // Also whitelist casts involving incomplete types, which implicitly 4332 // includes 'void'. 4333 if (SrcPointee->isIncompleteType()) return; 4334 4335 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 4336 if (SrcAlign >= DestAlign) return; 4337 4338 Diag(TRange.getBegin(), diag::warn_cast_align) 4339 << Op->getType() << T 4340 << static_cast<unsigned>(SrcAlign.getQuantity()) 4341 << static_cast<unsigned>(DestAlign.getQuantity()) 4342 << TRange << Op->getSourceRange(); 4343} 4344 4345static const Type* getElementType(const Expr *BaseExpr) { 4346 const Type* EltType = BaseExpr->getType().getTypePtr(); 4347 if (EltType->isAnyPointerType()) 4348 return EltType->getPointeeType().getTypePtr(); 4349 else if (EltType->isArrayType()) 4350 return EltType->getBaseElementTypeUnsafe(); 4351 return EltType; 4352} 4353 4354/// \brief Check whether this array fits the idiom of a size-one tail padded 4355/// array member of a struct. 4356/// 4357/// We avoid emitting out-of-bounds access warnings for such arrays as they are 4358/// commonly used to emulate flexible arrays in C89 code. 4359static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size, 4360 const NamedDecl *ND) { 4361 if (Size != 1 || !ND) return false; 4362 4363 const FieldDecl *FD = dyn_cast<FieldDecl>(ND); 4364 if (!FD) return false; 4365 4366 // Don't consider sizes resulting from macro expansions or template argument 4367 // substitution to form C89 tail-padded arrays. 4368 ConstantArrayTypeLoc TL = 4369 cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc()); 4370 const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr()); 4371 if (!SizeExpr || SizeExpr->getExprLoc().isMacroID()) 4372 return false; 4373 4374 const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext()); 4375 if (!RD) return false; 4376 if (RD->isUnion()) return false; 4377 if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) { 4378 if (!CRD->isStandardLayout()) return false; 4379 } 4380 4381 // See if this is the last field decl in the record. 4382 const Decl *D = FD; 4383 while ((D = D->getNextDeclInContext())) 4384 if (isa<FieldDecl>(D)) 4385 return false; 4386 return true; 4387} 4388 4389void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr, 4390 const ArraySubscriptExpr *ASE, 4391 bool AllowOnePastEnd, bool IndexNegated) { 4392 IndexExpr = IndexExpr->IgnoreParenCasts(); 4393 if (IndexExpr->isValueDependent()) 4394 return; 4395 4396 const Type *EffectiveType = getElementType(BaseExpr); 4397 BaseExpr = BaseExpr->IgnoreParenCasts(); 4398 const ConstantArrayType *ArrayTy = 4399 Context.getAsConstantArrayType(BaseExpr->getType()); 4400 if (!ArrayTy) 4401 return; 4402 4403 llvm::APSInt index; 4404 if (!IndexExpr->EvaluateAsInt(index, Context)) 4405 return; 4406 if (IndexNegated) 4407 index = -index; 4408 4409 const NamedDecl *ND = NULL; 4410 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 4411 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 4412 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 4413 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 4414 4415 if (index.isUnsigned() || !index.isNegative()) { 4416 llvm::APInt size = ArrayTy->getSize(); 4417 if (!size.isStrictlyPositive()) 4418 return; 4419 4420 const Type* BaseType = getElementType(BaseExpr); 4421 if (BaseType != EffectiveType) { 4422 // Make sure we're comparing apples to apples when comparing index to size 4423 uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType); 4424 uint64_t array_typesize = Context.getTypeSize(BaseType); 4425 // Handle ptrarith_typesize being zero, such as when casting to void* 4426 if (!ptrarith_typesize) ptrarith_typesize = 1; 4427 if (ptrarith_typesize != array_typesize) { 4428 // There's a cast to a different size type involved 4429 uint64_t ratio = array_typesize / ptrarith_typesize; 4430 // TODO: Be smarter about handling cases where array_typesize is not a 4431 // multiple of ptrarith_typesize 4432 if (ptrarith_typesize * ratio == array_typesize) 4433 size *= llvm::APInt(size.getBitWidth(), ratio); 4434 } 4435 } 4436 4437 if (size.getBitWidth() > index.getBitWidth()) 4438 index = index.sext(size.getBitWidth()); 4439 else if (size.getBitWidth() < index.getBitWidth()) 4440 size = size.sext(index.getBitWidth()); 4441 4442 // For array subscripting the index must be less than size, but for pointer 4443 // arithmetic also allow the index (offset) to be equal to size since 4444 // computing the next address after the end of the array is legal and 4445 // commonly done e.g. in C++ iterators and range-based for loops. 4446 if (AllowOnePastEnd ? index.sle(size) : index.slt(size)) 4447 return; 4448 4449 // Also don't warn for arrays of size 1 which are members of some 4450 // structure. These are often used to approximate flexible arrays in C89 4451 // code. 4452 if (IsTailPaddedMemberArray(*this, size, ND)) 4453 return; 4454 4455 // Suppress the warning if the subscript expression (as identified by the 4456 // ']' location) and the index expression are both from macro expansions 4457 // within a system header. 4458 if (ASE) { 4459 SourceLocation RBracketLoc = SourceMgr.getSpellingLoc( 4460 ASE->getRBracketLoc()); 4461 if (SourceMgr.isInSystemHeader(RBracketLoc)) { 4462 SourceLocation IndexLoc = SourceMgr.getSpellingLoc( 4463 IndexExpr->getLocStart()); 4464 if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc)) 4465 return; 4466 } 4467 } 4468 4469 unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds; 4470 if (ASE) 4471 DiagID = diag::warn_array_index_exceeds_bounds; 4472 4473 DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr, 4474 PDiag(DiagID) << index.toString(10, true) 4475 << size.toString(10, true) 4476 << (unsigned)size.getLimitedValue(~0U) 4477 << IndexExpr->getSourceRange()); 4478 } else { 4479 unsigned DiagID = diag::warn_array_index_precedes_bounds; 4480 if (!ASE) { 4481 DiagID = diag::warn_ptr_arith_precedes_bounds; 4482 if (index.isNegative()) index = -index; 4483 } 4484 4485 DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr, 4486 PDiag(DiagID) << index.toString(10, true) 4487 << IndexExpr->getSourceRange()); 4488 } 4489 4490 if (!ND) { 4491 // Try harder to find a NamedDecl to point at in the note. 4492 while (const ArraySubscriptExpr *ASE = 4493 dyn_cast<ArraySubscriptExpr>(BaseExpr)) 4494 BaseExpr = ASE->getBase()->IgnoreParenCasts(); 4495 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 4496 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 4497 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 4498 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 4499 } 4500 4501 if (ND) 4502 DiagRuntimeBehavior(ND->getLocStart(), BaseExpr, 4503 PDiag(diag::note_array_index_out_of_bounds) 4504 << ND->getDeclName()); 4505} 4506 4507void Sema::CheckArrayAccess(const Expr *expr) { 4508 int AllowOnePastEnd = 0; 4509 while (expr) { 4510 expr = expr->IgnoreParenImpCasts(); 4511 switch (expr->getStmtClass()) { 4512 case Stmt::ArraySubscriptExprClass: { 4513 const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr); 4514 CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE, 4515 AllowOnePastEnd > 0); 4516 return; 4517 } 4518 case Stmt::UnaryOperatorClass: { 4519 // Only unwrap the * and & unary operators 4520 const UnaryOperator *UO = cast<UnaryOperator>(expr); 4521 expr = UO->getSubExpr(); 4522 switch (UO->getOpcode()) { 4523 case UO_AddrOf: 4524 AllowOnePastEnd++; 4525 break; 4526 case UO_Deref: 4527 AllowOnePastEnd--; 4528 break; 4529 default: 4530 return; 4531 } 4532 break; 4533 } 4534 case Stmt::ConditionalOperatorClass: { 4535 const ConditionalOperator *cond = cast<ConditionalOperator>(expr); 4536 if (const Expr *lhs = cond->getLHS()) 4537 CheckArrayAccess(lhs); 4538 if (const Expr *rhs = cond->getRHS()) 4539 CheckArrayAccess(rhs); 4540 return; 4541 } 4542 default: 4543 return; 4544 } 4545 } 4546} 4547 4548//===--- CHECK: Objective-C retain cycles ----------------------------------// 4549 4550namespace { 4551 struct RetainCycleOwner { 4552 RetainCycleOwner() : Variable(0), Indirect(false) {} 4553 VarDecl *Variable; 4554 SourceRange Range; 4555 SourceLocation Loc; 4556 bool Indirect; 4557 4558 void setLocsFrom(Expr *e) { 4559 Loc = e->getExprLoc(); 4560 Range = e->getSourceRange(); 4561 } 4562 }; 4563} 4564 4565/// Consider whether capturing the given variable can possibly lead to 4566/// a retain cycle. 4567static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) { 4568 // In ARC, it's captured strongly iff the variable has __strong 4569 // lifetime. In MRR, it's captured strongly if the variable is 4570 // __block and has an appropriate type. 4571 if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong) 4572 return false; 4573 4574 owner.Variable = var; 4575 owner.setLocsFrom(ref); 4576 return true; 4577} 4578 4579static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) { 4580 while (true) { 4581 e = e->IgnoreParens(); 4582 if (CastExpr *cast = dyn_cast<CastExpr>(e)) { 4583 switch (cast->getCastKind()) { 4584 case CK_BitCast: 4585 case CK_LValueBitCast: 4586 case CK_LValueToRValue: 4587 case CK_ARCReclaimReturnedObject: 4588 e = cast->getSubExpr(); 4589 continue; 4590 4591 default: 4592 return false; 4593 } 4594 } 4595 4596 if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) { 4597 ObjCIvarDecl *ivar = ref->getDecl(); 4598 if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong) 4599 return false; 4600 4601 // Try to find a retain cycle in the base. 4602 if (!findRetainCycleOwner(S, ref->getBase(), owner)) 4603 return false; 4604 4605 if (ref->isFreeIvar()) owner.setLocsFrom(ref); 4606 owner.Indirect = true; 4607 return true; 4608 } 4609 4610 if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) { 4611 VarDecl *var = dyn_cast<VarDecl>(ref->getDecl()); 4612 if (!var) return false; 4613 return considerVariable(var, ref, owner); 4614 } 4615 4616 if (BlockDeclRefExpr *ref = dyn_cast<BlockDeclRefExpr>(e)) { 4617 owner.Variable = ref->getDecl(); 4618 owner.setLocsFrom(ref); 4619 return true; 4620 } 4621 4622 if (MemberExpr *member = dyn_cast<MemberExpr>(e)) { 4623 if (member->isArrow()) return false; 4624 4625 // Don't count this as an indirect ownership. 4626 e = member->getBase(); 4627 continue; 4628 } 4629 4630 if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) { 4631 // Only pay attention to pseudo-objects on property references. 4632 ObjCPropertyRefExpr *pre 4633 = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm() 4634 ->IgnoreParens()); 4635 if (!pre) return false; 4636 if (pre->isImplicitProperty()) return false; 4637 ObjCPropertyDecl *property = pre->getExplicitProperty(); 4638 if (!property->isRetaining() && 4639 !(property->getPropertyIvarDecl() && 4640 property->getPropertyIvarDecl()->getType() 4641 .getObjCLifetime() == Qualifiers::OCL_Strong)) 4642 return false; 4643 4644 owner.Indirect = true; 4645 if (pre->isSuperReceiver()) { 4646 owner.Variable = S.getCurMethodDecl()->getSelfDecl(); 4647 if (!owner.Variable) 4648 return false; 4649 owner.Loc = pre->getLocation(); 4650 owner.Range = pre->getSourceRange(); 4651 return true; 4652 } 4653 e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase()) 4654 ->getSourceExpr()); 4655 continue; 4656 } 4657 4658 // Array ivars? 4659 4660 return false; 4661 } 4662} 4663 4664namespace { 4665 struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> { 4666 FindCaptureVisitor(ASTContext &Context, VarDecl *variable) 4667 : EvaluatedExprVisitor<FindCaptureVisitor>(Context), 4668 Variable(variable), Capturer(0) {} 4669 4670 VarDecl *Variable; 4671 Expr *Capturer; 4672 4673 void VisitDeclRefExpr(DeclRefExpr *ref) { 4674 if (ref->getDecl() == Variable && !Capturer) 4675 Capturer = ref; 4676 } 4677 4678 void VisitBlockDeclRefExpr(BlockDeclRefExpr *ref) { 4679 if (ref->getDecl() == Variable && !Capturer) 4680 Capturer = ref; 4681 } 4682 4683 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) { 4684 if (Capturer) return; 4685 Visit(ref->getBase()); 4686 if (Capturer && ref->isFreeIvar()) 4687 Capturer = ref; 4688 } 4689 4690 void VisitBlockExpr(BlockExpr *block) { 4691 // Look inside nested blocks 4692 if (block->getBlockDecl()->capturesVariable(Variable)) 4693 Visit(block->getBlockDecl()->getBody()); 4694 } 4695 }; 4696} 4697 4698/// Check whether the given argument is a block which captures a 4699/// variable. 4700static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) { 4701 assert(owner.Variable && owner.Loc.isValid()); 4702 4703 e = e->IgnoreParenCasts(); 4704 BlockExpr *block = dyn_cast<BlockExpr>(e); 4705 if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable)) 4706 return 0; 4707 4708 FindCaptureVisitor visitor(S.Context, owner.Variable); 4709 visitor.Visit(block->getBlockDecl()->getBody()); 4710 return visitor.Capturer; 4711} 4712 4713static void diagnoseRetainCycle(Sema &S, Expr *capturer, 4714 RetainCycleOwner &owner) { 4715 assert(capturer); 4716 assert(owner.Variable && owner.Loc.isValid()); 4717 4718 S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle) 4719 << owner.Variable << capturer->getSourceRange(); 4720 S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner) 4721 << owner.Indirect << owner.Range; 4722} 4723 4724/// Check for a keyword selector that starts with the word 'add' or 4725/// 'set'. 4726static bool isSetterLikeSelector(Selector sel) { 4727 if (sel.isUnarySelector()) return false; 4728 4729 StringRef str = sel.getNameForSlot(0); 4730 while (!str.empty() && str.front() == '_') str = str.substr(1); 4731 if (str.startswith("set")) 4732 str = str.substr(3); 4733 else if (str.startswith("add")) { 4734 // Specially whitelist 'addOperationWithBlock:'. 4735 if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock")) 4736 return false; 4737 str = str.substr(3); 4738 } 4739 else 4740 return false; 4741 4742 if (str.empty()) return true; 4743 return !islower(str.front()); 4744} 4745 4746/// Check a message send to see if it's likely to cause a retain cycle. 4747void Sema::checkRetainCycles(ObjCMessageExpr *msg) { 4748 // Only check instance methods whose selector looks like a setter. 4749 if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector())) 4750 return; 4751 4752 // Try to find a variable that the receiver is strongly owned by. 4753 RetainCycleOwner owner; 4754 if (msg->getReceiverKind() == ObjCMessageExpr::Instance) { 4755 if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner)) 4756 return; 4757 } else { 4758 assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance); 4759 owner.Variable = getCurMethodDecl()->getSelfDecl(); 4760 owner.Loc = msg->getSuperLoc(); 4761 owner.Range = msg->getSuperLoc(); 4762 } 4763 4764 // Check whether the receiver is captured by any of the arguments. 4765 for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i) 4766 if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner)) 4767 return diagnoseRetainCycle(*this, capturer, owner); 4768} 4769 4770/// Check a property assign to see if it's likely to cause a retain cycle. 4771void Sema::checkRetainCycles(Expr *receiver, Expr *argument) { 4772 RetainCycleOwner owner; 4773 if (!findRetainCycleOwner(*this, receiver, owner)) 4774 return; 4775 4776 if (Expr *capturer = findCapturingExpr(*this, argument, owner)) 4777 diagnoseRetainCycle(*this, capturer, owner); 4778} 4779 4780bool Sema::checkUnsafeAssigns(SourceLocation Loc, 4781 QualType LHS, Expr *RHS) { 4782 Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime(); 4783 if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone) 4784 return false; 4785 // strip off any implicit cast added to get to the one arc-specific 4786 while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) { 4787 if (cast->getCastKind() == CK_ARCConsumeObject) { 4788 Diag(Loc, diag::warn_arc_retained_assign) 4789 << (LT == Qualifiers::OCL_ExplicitNone) 4790 << RHS->getSourceRange(); 4791 return true; 4792 } 4793 RHS = cast->getSubExpr(); 4794 } 4795 return false; 4796} 4797 4798void Sema::checkUnsafeExprAssigns(SourceLocation Loc, 4799 Expr *LHS, Expr *RHS) { 4800 QualType LHSType; 4801 // PropertyRef on LHS type need be directly obtained from 4802 // its declaration as it has a PsuedoType. 4803 ObjCPropertyRefExpr *PRE 4804 = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens()); 4805 if (PRE && !PRE->isImplicitProperty()) { 4806 const ObjCPropertyDecl *PD = PRE->getExplicitProperty(); 4807 if (PD) 4808 LHSType = PD->getType(); 4809 } 4810 4811 if (LHSType.isNull()) 4812 LHSType = LHS->getType(); 4813 if (checkUnsafeAssigns(Loc, LHSType, RHS)) 4814 return; 4815 Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime(); 4816 // FIXME. Check for other life times. 4817 if (LT != Qualifiers::OCL_None) 4818 return; 4819 4820 if (PRE) { 4821 if (PRE->isImplicitProperty()) 4822 return; 4823 const ObjCPropertyDecl *PD = PRE->getExplicitProperty(); 4824 if (!PD) 4825 return; 4826 4827 unsigned Attributes = PD->getPropertyAttributes(); 4828 if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) { 4829 // when 'assign' attribute was not explicitly specified 4830 // by user, ignore it and rely on property type itself 4831 // for lifetime info. 4832 unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten(); 4833 if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) && 4834 LHSType->isObjCRetainableType()) 4835 return; 4836 4837 while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) { 4838 if (cast->getCastKind() == CK_ARCConsumeObject) { 4839 Diag(Loc, diag::warn_arc_retained_property_assign) 4840 << RHS->getSourceRange(); 4841 return; 4842 } 4843 RHS = cast->getSubExpr(); 4844 } 4845 } 4846 } 4847} 4848 4849//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===// 4850 4851namespace { 4852bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr, 4853 SourceLocation StmtLoc, 4854 const NullStmt *Body) { 4855 // Do not warn if the body is a macro that expands to nothing, e.g: 4856 // 4857 // #define CALL(x) 4858 // if (condition) 4859 // CALL(0); 4860 // 4861 if (Body->hasLeadingEmptyMacro()) 4862 return false; 4863 4864 // Get line numbers of statement and body. 4865 bool StmtLineInvalid; 4866 unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc, 4867 &StmtLineInvalid); 4868 if (StmtLineInvalid) 4869 return false; 4870 4871 bool BodyLineInvalid; 4872 unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(), 4873 &BodyLineInvalid); 4874 if (BodyLineInvalid) 4875 return false; 4876 4877 // Warn if null statement and body are on the same line. 4878 if (StmtLine != BodyLine) 4879 return false; 4880 4881 return true; 4882} 4883} // Unnamed namespace 4884 4885void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc, 4886 const Stmt *Body, 4887 unsigned DiagID) { 4888 // Since this is a syntactic check, don't emit diagnostic for template 4889 // instantiations, this just adds noise. 4890 if (CurrentInstantiationScope) 4891 return; 4892 4893 // The body should be a null statement. 4894 const NullStmt *NBody = dyn_cast<NullStmt>(Body); 4895 if (!NBody) 4896 return; 4897 4898 // Do the usual checks. 4899 if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody)) 4900 return; 4901 4902 Diag(NBody->getSemiLoc(), DiagID); 4903 Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line); 4904} 4905 4906void Sema::DiagnoseEmptyLoopBody(const Stmt *S, 4907 const Stmt *PossibleBody) { 4908 assert(!CurrentInstantiationScope); // Ensured by caller 4909 4910 SourceLocation StmtLoc; 4911 const Stmt *Body; 4912 unsigned DiagID; 4913 if (const ForStmt *FS = dyn_cast<ForStmt>(S)) { 4914 StmtLoc = FS->getRParenLoc(); 4915 Body = FS->getBody(); 4916 DiagID = diag::warn_empty_for_body; 4917 } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) { 4918 StmtLoc = WS->getCond()->getSourceRange().getEnd(); 4919 Body = WS->getBody(); 4920 DiagID = diag::warn_empty_while_body; 4921 } else 4922 return; // Neither `for' nor `while'. 4923 4924 // The body should be a null statement. 4925 const NullStmt *NBody = dyn_cast<NullStmt>(Body); 4926 if (!NBody) 4927 return; 4928 4929 // Skip expensive checks if diagnostic is disabled. 4930 if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) == 4931 DiagnosticsEngine::Ignored) 4932 return; 4933 4934 // Do the usual checks. 4935 if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody)) 4936 return; 4937 4938 // `for(...);' and `while(...);' are popular idioms, so in order to keep 4939 // noise level low, emit diagnostics only if for/while is followed by a 4940 // CompoundStmt, e.g.: 4941 // for (int i = 0; i < n; i++); 4942 // { 4943 // a(i); 4944 // } 4945 // or if for/while is followed by a statement with more indentation 4946 // than for/while itself: 4947 // for (int i = 0; i < n; i++); 4948 // a(i); 4949 bool ProbableTypo = isa<CompoundStmt>(PossibleBody); 4950 if (!ProbableTypo) { 4951 bool BodyColInvalid; 4952 unsigned BodyCol = SourceMgr.getPresumedColumnNumber( 4953 PossibleBody->getLocStart(), 4954 &BodyColInvalid); 4955 if (BodyColInvalid) 4956 return; 4957 4958 bool StmtColInvalid; 4959 unsigned StmtCol = SourceMgr.getPresumedColumnNumber( 4960 S->getLocStart(), 4961 &StmtColInvalid); 4962 if (StmtColInvalid) 4963 return; 4964 4965 if (BodyCol > StmtCol) 4966 ProbableTypo = true; 4967 } 4968 4969 if (ProbableTypo) { 4970 Diag(NBody->getSemiLoc(), DiagID); 4971 Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line); 4972 } 4973} 4974 4975