SemaChecking.cpp revision e4a1c64700304459ac436fe29cb498f2da3b6194
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements extra semantic analysis beyond what is enforced 11// by the C type system. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Sema/Sema.h" 16#include "clang/Sema/SemaInternal.h" 17#include "clang/Sema/ScopeInfo.h" 18#include "clang/Analysis/Analyses/FormatString.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/CharUnits.h" 21#include "clang/AST/DeclCXX.h" 22#include "clang/AST/DeclObjC.h" 23#include "clang/AST/ExprCXX.h" 24#include "clang/AST/ExprObjC.h" 25#include "clang/AST/DeclObjC.h" 26#include "clang/AST/StmtCXX.h" 27#include "clang/AST/StmtObjC.h" 28#include "clang/Lex/Preprocessor.h" 29#include "llvm/ADT/BitVector.h" 30#include "llvm/ADT/STLExtras.h" 31#include "llvm/Support/raw_ostream.h" 32#include "clang/Basic/TargetBuiltins.h" 33#include "clang/Basic/TargetInfo.h" 34#include "clang/Basic/ConvertUTF.h" 35#include <limits> 36using namespace clang; 37using namespace sema; 38 39SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 40 unsigned ByteNo) const { 41 return SL->getLocationOfByte(ByteNo, PP.getSourceManager(), 42 PP.getLangOptions(), PP.getTargetInfo()); 43} 44 45 46/// CheckablePrintfAttr - does a function call have a "printf" attribute 47/// and arguments that merit checking? 48bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 49 if (Format->getType() == "printf") return true; 50 if (Format->getType() == "printf0") { 51 // printf0 allows null "format" string; if so don't check format/args 52 unsigned format_idx = Format->getFormatIdx() - 1; 53 // Does the index refer to the implicit object argument? 54 if (isa<CXXMemberCallExpr>(TheCall)) { 55 if (format_idx == 0) 56 return false; 57 --format_idx; 58 } 59 if (format_idx < TheCall->getNumArgs()) { 60 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 61 if (!Format->isNullPointerConstant(Context, 62 Expr::NPC_ValueDependentIsNull)) 63 return true; 64 } 65 } 66 return false; 67} 68 69/// Checks that a call expression's argument count is the desired number. 70/// This is useful when doing custom type-checking. Returns true on error. 71static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) { 72 unsigned argCount = call->getNumArgs(); 73 if (argCount == desiredArgCount) return false; 74 75 if (argCount < desiredArgCount) 76 return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args) 77 << 0 /*function call*/ << desiredArgCount << argCount 78 << call->getSourceRange(); 79 80 // Highlight all the excess arguments. 81 SourceRange range(call->getArg(desiredArgCount)->getLocStart(), 82 call->getArg(argCount - 1)->getLocEnd()); 83 84 return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args) 85 << 0 /*function call*/ << desiredArgCount << argCount 86 << call->getArg(1)->getSourceRange(); 87} 88 89ExprResult 90Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 91 ExprResult TheCallResult(Owned(TheCall)); 92 93 // Find out if any arguments are required to be integer constant expressions. 94 unsigned ICEArguments = 0; 95 ASTContext::GetBuiltinTypeError Error; 96 Context.GetBuiltinType(BuiltinID, Error, &ICEArguments); 97 if (Error != ASTContext::GE_None) 98 ICEArguments = 0; // Don't diagnose previously diagnosed errors. 99 100 // If any arguments are required to be ICE's, check and diagnose. 101 for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) { 102 // Skip arguments not required to be ICE's. 103 if ((ICEArguments & (1 << ArgNo)) == 0) continue; 104 105 llvm::APSInt Result; 106 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 107 return true; 108 ICEArguments &= ~(1 << ArgNo); 109 } 110 111 switch (BuiltinID) { 112 case Builtin::BI__builtin___CFStringMakeConstantString: 113 assert(TheCall->getNumArgs() == 1 && 114 "Wrong # arguments to builtin CFStringMakeConstantString"); 115 if (CheckObjCString(TheCall->getArg(0))) 116 return ExprError(); 117 break; 118 case Builtin::BI__builtin_stdarg_start: 119 case Builtin::BI__builtin_va_start: 120 if (SemaBuiltinVAStart(TheCall)) 121 return ExprError(); 122 break; 123 case Builtin::BI__builtin_isgreater: 124 case Builtin::BI__builtin_isgreaterequal: 125 case Builtin::BI__builtin_isless: 126 case Builtin::BI__builtin_islessequal: 127 case Builtin::BI__builtin_islessgreater: 128 case Builtin::BI__builtin_isunordered: 129 if (SemaBuiltinUnorderedCompare(TheCall)) 130 return ExprError(); 131 break; 132 case Builtin::BI__builtin_fpclassify: 133 if (SemaBuiltinFPClassification(TheCall, 6)) 134 return ExprError(); 135 break; 136 case Builtin::BI__builtin_isfinite: 137 case Builtin::BI__builtin_isinf: 138 case Builtin::BI__builtin_isinf_sign: 139 case Builtin::BI__builtin_isnan: 140 case Builtin::BI__builtin_isnormal: 141 if (SemaBuiltinFPClassification(TheCall, 1)) 142 return ExprError(); 143 break; 144 case Builtin::BI__builtin_shufflevector: 145 return SemaBuiltinShuffleVector(TheCall); 146 // TheCall will be freed by the smart pointer here, but that's fine, since 147 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 148 case Builtin::BI__builtin_prefetch: 149 if (SemaBuiltinPrefetch(TheCall)) 150 return ExprError(); 151 break; 152 case Builtin::BI__builtin_object_size: 153 if (SemaBuiltinObjectSize(TheCall)) 154 return ExprError(); 155 break; 156 case Builtin::BI__builtin_longjmp: 157 if (SemaBuiltinLongjmp(TheCall)) 158 return ExprError(); 159 break; 160 161 case Builtin::BI__builtin_classify_type: 162 if (checkArgCount(*this, TheCall, 1)) return true; 163 TheCall->setType(Context.IntTy); 164 break; 165 case Builtin::BI__builtin_constant_p: 166 if (checkArgCount(*this, TheCall, 1)) return true; 167 TheCall->setType(Context.IntTy); 168 break; 169 case Builtin::BI__sync_fetch_and_add: 170 case Builtin::BI__sync_fetch_and_sub: 171 case Builtin::BI__sync_fetch_and_or: 172 case Builtin::BI__sync_fetch_and_and: 173 case Builtin::BI__sync_fetch_and_xor: 174 case Builtin::BI__sync_add_and_fetch: 175 case Builtin::BI__sync_sub_and_fetch: 176 case Builtin::BI__sync_and_and_fetch: 177 case Builtin::BI__sync_or_and_fetch: 178 case Builtin::BI__sync_xor_and_fetch: 179 case Builtin::BI__sync_val_compare_and_swap: 180 case Builtin::BI__sync_bool_compare_and_swap: 181 case Builtin::BI__sync_lock_test_and_set: 182 case Builtin::BI__sync_lock_release: 183 case Builtin::BI__sync_swap: 184 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 185 } 186 187 // Since the target specific builtins for each arch overlap, only check those 188 // of the arch we are compiling for. 189 if (BuiltinID >= Builtin::FirstTSBuiltin) { 190 switch (Context.Target.getTriple().getArch()) { 191 case llvm::Triple::arm: 192 case llvm::Triple::thumb: 193 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 194 return ExprError(); 195 break; 196 default: 197 break; 198 } 199 } 200 201 return move(TheCallResult); 202} 203 204// Get the valid immediate range for the specified NEON type code. 205static unsigned RFT(unsigned t, bool shift = false) { 206 bool quad = t & 0x10; 207 208 switch (t & 0x7) { 209 case 0: // i8 210 return shift ? 7 : (8 << (int)quad) - 1; 211 case 1: // i16 212 return shift ? 15 : (4 << (int)quad) - 1; 213 case 2: // i32 214 return shift ? 31 : (2 << (int)quad) - 1; 215 case 3: // i64 216 return shift ? 63 : (1 << (int)quad) - 1; 217 case 4: // f32 218 assert(!shift && "cannot shift float types!"); 219 return (2 << (int)quad) - 1; 220 case 5: // poly8 221 return shift ? 7 : (8 << (int)quad) - 1; 222 case 6: // poly16 223 return shift ? 15 : (4 << (int)quad) - 1; 224 case 7: // float16 225 assert(!shift && "cannot shift float types!"); 226 return (4 << (int)quad) - 1; 227 } 228 return 0; 229} 230 231bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 232 llvm::APSInt Result; 233 234 unsigned mask = 0; 235 unsigned TV = 0; 236 switch (BuiltinID) { 237#define GET_NEON_OVERLOAD_CHECK 238#include "clang/Basic/arm_neon.inc" 239#undef GET_NEON_OVERLOAD_CHECK 240 } 241 242 // For NEON intrinsics which are overloaded on vector element type, validate 243 // the immediate which specifies which variant to emit. 244 if (mask) { 245 unsigned ArgNo = TheCall->getNumArgs()-1; 246 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 247 return true; 248 249 TV = Result.getLimitedValue(32); 250 if ((TV > 31) || (mask & (1 << TV)) == 0) 251 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 252 << TheCall->getArg(ArgNo)->getSourceRange(); 253 } 254 255 // For NEON intrinsics which take an immediate value as part of the 256 // instruction, range check them here. 257 unsigned i = 0, l = 0, u = 0; 258 switch (BuiltinID) { 259 default: return false; 260 case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; 261 case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; 262 case ARM::BI__builtin_arm_vcvtr_f: 263 case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; 264#define GET_NEON_IMMEDIATE_CHECK 265#include "clang/Basic/arm_neon.inc" 266#undef GET_NEON_IMMEDIATE_CHECK 267 }; 268 269 // Check that the immediate argument is actually a constant. 270 if (SemaBuiltinConstantArg(TheCall, i, Result)) 271 return true; 272 273 // Range check against the upper/lower values for this isntruction. 274 unsigned Val = Result.getZExtValue(); 275 if (Val < l || Val > (u + l)) 276 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 277 << l << u+l << TheCall->getArg(i)->getSourceRange(); 278 279 // FIXME: VFP Intrinsics should error if VFP not present. 280 return false; 281} 282 283/// CheckFunctionCall - Check a direct function call for various correctness 284/// and safety properties not strictly enforced by the C type system. 285bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 286 // Get the IdentifierInfo* for the called function. 287 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 288 289 // None of the checks below are needed for functions that don't have 290 // simple names (e.g., C++ conversion functions). 291 if (!FnInfo) 292 return false; 293 294 // FIXME: This mechanism should be abstracted to be less fragile and 295 // more efficient. For example, just map function ids to custom 296 // handlers. 297 298 // Printf and scanf checking. 299 for (specific_attr_iterator<FormatAttr> 300 i = FDecl->specific_attr_begin<FormatAttr>(), 301 e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { 302 303 const FormatAttr *Format = *i; 304 const bool b = Format->getType() == "scanf"; 305 if (b || CheckablePrintfAttr(Format, TheCall)) { 306 bool HasVAListArg = Format->getFirstArg() == 0; 307 CheckPrintfScanfArguments(TheCall, HasVAListArg, 308 Format->getFormatIdx() - 1, 309 HasVAListArg ? 0 : Format->getFirstArg() - 1, 310 !b); 311 } 312 } 313 314 for (specific_attr_iterator<NonNullAttr> 315 i = FDecl->specific_attr_begin<NonNullAttr>(), 316 e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) { 317 CheckNonNullArguments(*i, TheCall->getArgs(), 318 TheCall->getCallee()->getLocStart()); 319 } 320 321 // Memset/memcpy/memmove handling 322 if (FDecl->getLinkage() == ExternalLinkage && 323 (!getLangOptions().CPlusPlus || FDecl->isExternC())) { 324 if (FnInfo->isStr("memset") || FnInfo->isStr("memcpy") || 325 FnInfo->isStr("memmove")) 326 CheckMemsetcpymoveArguments(TheCall, FnInfo); 327 } 328 329 return false; 330} 331 332bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 333 // Printf checking. 334 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 335 if (!Format) 336 return false; 337 338 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 339 if (!V) 340 return false; 341 342 QualType Ty = V->getType(); 343 if (!Ty->isBlockPointerType()) 344 return false; 345 346 const bool b = Format->getType() == "scanf"; 347 if (!b && !CheckablePrintfAttr(Format, TheCall)) 348 return false; 349 350 bool HasVAListArg = Format->getFirstArg() == 0; 351 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 352 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 353 354 return false; 355} 356 357/// SemaBuiltinAtomicOverloaded - We have a call to a function like 358/// __sync_fetch_and_add, which is an overloaded function based on the pointer 359/// type of its first argument. The main ActOnCallExpr routines have already 360/// promoted the types of arguments because all of these calls are prototyped as 361/// void(...). 362/// 363/// This function goes through and does final semantic checking for these 364/// builtins, 365ExprResult 366Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { 367 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 368 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 369 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 370 371 // Ensure that we have at least one argument to do type inference from. 372 if (TheCall->getNumArgs() < 1) { 373 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 374 << 0 << 1 << TheCall->getNumArgs() 375 << TheCall->getCallee()->getSourceRange(); 376 return ExprError(); 377 } 378 379 // Inspect the first argument of the atomic builtin. This should always be 380 // a pointer type, whose element is an integral scalar or pointer type. 381 // Because it is a pointer type, we don't have to worry about any implicit 382 // casts here. 383 // FIXME: We don't allow floating point scalars as input. 384 Expr *FirstArg = TheCall->getArg(0); 385 if (!FirstArg->getType()->isPointerType()) { 386 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 387 << FirstArg->getType() << FirstArg->getSourceRange(); 388 return ExprError(); 389 } 390 391 QualType ValType = 392 FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 393 if (!ValType->isIntegerType() && !ValType->isAnyPointerType() && 394 !ValType->isBlockPointerType()) { 395 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 396 << FirstArg->getType() << FirstArg->getSourceRange(); 397 return ExprError(); 398 } 399 400 // The majority of builtins return a value, but a few have special return 401 // types, so allow them to override appropriately below. 402 QualType ResultType = ValType; 403 404 // We need to figure out which concrete builtin this maps onto. For example, 405 // __sync_fetch_and_add with a 2 byte object turns into 406 // __sync_fetch_and_add_2. 407#define BUILTIN_ROW(x) \ 408 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 409 Builtin::BI##x##_8, Builtin::BI##x##_16 } 410 411 static const unsigned BuiltinIndices[][5] = { 412 BUILTIN_ROW(__sync_fetch_and_add), 413 BUILTIN_ROW(__sync_fetch_and_sub), 414 BUILTIN_ROW(__sync_fetch_and_or), 415 BUILTIN_ROW(__sync_fetch_and_and), 416 BUILTIN_ROW(__sync_fetch_and_xor), 417 418 BUILTIN_ROW(__sync_add_and_fetch), 419 BUILTIN_ROW(__sync_sub_and_fetch), 420 BUILTIN_ROW(__sync_and_and_fetch), 421 BUILTIN_ROW(__sync_or_and_fetch), 422 BUILTIN_ROW(__sync_xor_and_fetch), 423 424 BUILTIN_ROW(__sync_val_compare_and_swap), 425 BUILTIN_ROW(__sync_bool_compare_and_swap), 426 BUILTIN_ROW(__sync_lock_test_and_set), 427 BUILTIN_ROW(__sync_lock_release), 428 BUILTIN_ROW(__sync_swap) 429 }; 430#undef BUILTIN_ROW 431 432 // Determine the index of the size. 433 unsigned SizeIndex; 434 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 435 case 1: SizeIndex = 0; break; 436 case 2: SizeIndex = 1; break; 437 case 4: SizeIndex = 2; break; 438 case 8: SizeIndex = 3; break; 439 case 16: SizeIndex = 4; break; 440 default: 441 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 442 << FirstArg->getType() << FirstArg->getSourceRange(); 443 return ExprError(); 444 } 445 446 // Each of these builtins has one pointer argument, followed by some number of 447 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 448 // that we ignore. Find out which row of BuiltinIndices to read from as well 449 // as the number of fixed args. 450 unsigned BuiltinID = FDecl->getBuiltinID(); 451 unsigned BuiltinIndex, NumFixed = 1; 452 switch (BuiltinID) { 453 default: assert(0 && "Unknown overloaded atomic builtin!"); 454 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 455 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 456 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 457 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 458 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 459 460 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 461 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 462 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 463 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 464 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 465 466 case Builtin::BI__sync_val_compare_and_swap: 467 BuiltinIndex = 10; 468 NumFixed = 2; 469 break; 470 case Builtin::BI__sync_bool_compare_and_swap: 471 BuiltinIndex = 11; 472 NumFixed = 2; 473 ResultType = Context.BoolTy; 474 break; 475 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 476 case Builtin::BI__sync_lock_release: 477 BuiltinIndex = 13; 478 NumFixed = 0; 479 ResultType = Context.VoidTy; 480 break; 481 case Builtin::BI__sync_swap: BuiltinIndex = 14; break; 482 } 483 484 // Now that we know how many fixed arguments we expect, first check that we 485 // have at least that many. 486 if (TheCall->getNumArgs() < 1+NumFixed) { 487 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 488 << 0 << 1+NumFixed << TheCall->getNumArgs() 489 << TheCall->getCallee()->getSourceRange(); 490 return ExprError(); 491 } 492 493 // Get the decl for the concrete builtin from this, we can tell what the 494 // concrete integer type we should convert to is. 495 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 496 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 497 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 498 FunctionDecl *NewBuiltinDecl = 499 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 500 TUScope, false, DRE->getLocStart())); 501 502 // The first argument --- the pointer --- has a fixed type; we 503 // deduce the types of the rest of the arguments accordingly. Walk 504 // the remaining arguments, converting them to the deduced value type. 505 for (unsigned i = 0; i != NumFixed; ++i) { 506 ExprResult Arg = TheCall->getArg(i+1); 507 508 // If the argument is an implicit cast, then there was a promotion due to 509 // "...", just remove it now. 510 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg.get())) { 511 Arg = ICE->getSubExpr(); 512 ICE->setSubExpr(0); 513 TheCall->setArg(i+1, Arg.get()); 514 } 515 516 // GCC does an implicit conversion to the pointer or integer ValType. This 517 // can fail in some cases (1i -> int**), check for this error case now. 518 CastKind Kind = CK_Invalid; 519 ExprValueKind VK = VK_RValue; 520 CXXCastPath BasePath; 521 Arg = CheckCastTypes(Arg.get()->getSourceRange(), ValType, Arg.take(), Kind, VK, BasePath); 522 if (Arg.isInvalid()) 523 return ExprError(); 524 525 // Okay, we have something that *can* be converted to the right type. Check 526 // to see if there is a potentially weird extension going on here. This can 527 // happen when you do an atomic operation on something like an char* and 528 // pass in 42. The 42 gets converted to char. This is even more strange 529 // for things like 45.123 -> char, etc. 530 // FIXME: Do this check. 531 Arg = ImpCastExprToType(Arg.take(), ValType, Kind, VK, &BasePath); 532 TheCall->setArg(i+1, Arg.get()); 533 } 534 535 // Switch the DeclRefExpr to refer to the new decl. 536 DRE->setDecl(NewBuiltinDecl); 537 DRE->setType(NewBuiltinDecl->getType()); 538 539 // Set the callee in the CallExpr. 540 // FIXME: This leaks the original parens and implicit casts. 541 ExprResult PromotedCall = UsualUnaryConversions(DRE); 542 if (PromotedCall.isInvalid()) 543 return ExprError(); 544 TheCall->setCallee(PromotedCall.take()); 545 546 // Change the result type of the call to match the original value type. This 547 // is arbitrary, but the codegen for these builtins ins design to handle it 548 // gracefully. 549 TheCall->setType(ResultType); 550 551 return move(TheCallResult); 552} 553 554 555/// CheckObjCString - Checks that the argument to the builtin 556/// CFString constructor is correct 557/// Note: It might also make sense to do the UTF-16 conversion here (would 558/// simplify the backend). 559bool Sema::CheckObjCString(Expr *Arg) { 560 Arg = Arg->IgnoreParenCasts(); 561 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 562 563 if (!Literal || Literal->isWide()) { 564 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 565 << Arg->getSourceRange(); 566 return true; 567 } 568 569 if (Literal->containsNonAsciiOrNull()) { 570 llvm::StringRef String = Literal->getString(); 571 unsigned NumBytes = String.size(); 572 llvm::SmallVector<UTF16, 128> ToBuf(NumBytes); 573 const UTF8 *FromPtr = (UTF8 *)String.data(); 574 UTF16 *ToPtr = &ToBuf[0]; 575 576 ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, 577 &ToPtr, ToPtr + NumBytes, 578 strictConversion); 579 // Check for conversion failure. 580 if (Result != conversionOK) 581 Diag(Arg->getLocStart(), 582 diag::warn_cfstring_truncated) << Arg->getSourceRange(); 583 } 584 return false; 585} 586 587/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 588/// Emit an error and return true on failure, return false on success. 589bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 590 Expr *Fn = TheCall->getCallee(); 591 if (TheCall->getNumArgs() > 2) { 592 Diag(TheCall->getArg(2)->getLocStart(), 593 diag::err_typecheck_call_too_many_args) 594 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 595 << Fn->getSourceRange() 596 << SourceRange(TheCall->getArg(2)->getLocStart(), 597 (*(TheCall->arg_end()-1))->getLocEnd()); 598 return true; 599 } 600 601 if (TheCall->getNumArgs() < 2) { 602 return Diag(TheCall->getLocEnd(), 603 diag::err_typecheck_call_too_few_args_at_least) 604 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 605 } 606 607 // Determine whether the current function is variadic or not. 608 BlockScopeInfo *CurBlock = getCurBlock(); 609 bool isVariadic; 610 if (CurBlock) 611 isVariadic = CurBlock->TheDecl->isVariadic(); 612 else if (FunctionDecl *FD = getCurFunctionDecl()) 613 isVariadic = FD->isVariadic(); 614 else 615 isVariadic = getCurMethodDecl()->isVariadic(); 616 617 if (!isVariadic) { 618 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 619 return true; 620 } 621 622 // Verify that the second argument to the builtin is the last argument of the 623 // current function or method. 624 bool SecondArgIsLastNamedArgument = false; 625 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 626 627 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 628 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 629 // FIXME: This isn't correct for methods (results in bogus warning). 630 // Get the last formal in the current function. 631 const ParmVarDecl *LastArg; 632 if (CurBlock) 633 LastArg = *(CurBlock->TheDecl->param_end()-1); 634 else if (FunctionDecl *FD = getCurFunctionDecl()) 635 LastArg = *(FD->param_end()-1); 636 else 637 LastArg = *(getCurMethodDecl()->param_end()-1); 638 SecondArgIsLastNamedArgument = PV == LastArg; 639 } 640 } 641 642 if (!SecondArgIsLastNamedArgument) 643 Diag(TheCall->getArg(1)->getLocStart(), 644 diag::warn_second_parameter_of_va_start_not_last_named_argument); 645 return false; 646} 647 648/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 649/// friends. This is declared to take (...), so we have to check everything. 650bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 651 if (TheCall->getNumArgs() < 2) 652 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 653 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 654 if (TheCall->getNumArgs() > 2) 655 return Diag(TheCall->getArg(2)->getLocStart(), 656 diag::err_typecheck_call_too_many_args) 657 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 658 << SourceRange(TheCall->getArg(2)->getLocStart(), 659 (*(TheCall->arg_end()-1))->getLocEnd()); 660 661 ExprResult OrigArg0 = TheCall->getArg(0); 662 ExprResult OrigArg1 = TheCall->getArg(1); 663 664 // Do standard promotions between the two arguments, returning their common 665 // type. 666 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 667 if (OrigArg0.isInvalid() || OrigArg1.isInvalid()) 668 return true; 669 670 // Make sure any conversions are pushed back into the call; this is 671 // type safe since unordered compare builtins are declared as "_Bool 672 // foo(...)". 673 TheCall->setArg(0, OrigArg0.get()); 674 TheCall->setArg(1, OrigArg1.get()); 675 676 if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent()) 677 return false; 678 679 // If the common type isn't a real floating type, then the arguments were 680 // invalid for this operation. 681 if (!Res->isRealFloatingType()) 682 return Diag(OrigArg0.get()->getLocStart(), 683 diag::err_typecheck_call_invalid_ordered_compare) 684 << OrigArg0.get()->getType() << OrigArg1.get()->getType() 685 << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd()); 686 687 return false; 688} 689 690/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 691/// __builtin_isnan and friends. This is declared to take (...), so we have 692/// to check everything. We expect the last argument to be a floating point 693/// value. 694bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 695 if (TheCall->getNumArgs() < NumArgs) 696 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 697 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 698 if (TheCall->getNumArgs() > NumArgs) 699 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 700 diag::err_typecheck_call_too_many_args) 701 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 702 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 703 (*(TheCall->arg_end()-1))->getLocEnd()); 704 705 Expr *OrigArg = TheCall->getArg(NumArgs-1); 706 707 if (OrigArg->isTypeDependent()) 708 return false; 709 710 // This operation requires a non-_Complex floating-point number. 711 if (!OrigArg->getType()->isRealFloatingType()) 712 return Diag(OrigArg->getLocStart(), 713 diag::err_typecheck_call_invalid_unary_fp) 714 << OrigArg->getType() << OrigArg->getSourceRange(); 715 716 // If this is an implicit conversion from float -> double, remove it. 717 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 718 Expr *CastArg = Cast->getSubExpr(); 719 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 720 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 721 "promotion from float to double is the only expected cast here"); 722 Cast->setSubExpr(0); 723 TheCall->setArg(NumArgs-1, CastArg); 724 OrigArg = CastArg; 725 } 726 } 727 728 return false; 729} 730 731/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 732// This is declared to take (...), so we have to check everything. 733ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 734 if (TheCall->getNumArgs() < 2) 735 return ExprError(Diag(TheCall->getLocEnd(), 736 diag::err_typecheck_call_too_few_args_at_least) 737 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 738 << TheCall->getSourceRange()); 739 740 // Determine which of the following types of shufflevector we're checking: 741 // 1) unary, vector mask: (lhs, mask) 742 // 2) binary, vector mask: (lhs, rhs, mask) 743 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 744 QualType resType = TheCall->getArg(0)->getType(); 745 unsigned numElements = 0; 746 747 if (!TheCall->getArg(0)->isTypeDependent() && 748 !TheCall->getArg(1)->isTypeDependent()) { 749 QualType LHSType = TheCall->getArg(0)->getType(); 750 QualType RHSType = TheCall->getArg(1)->getType(); 751 752 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 753 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 754 << SourceRange(TheCall->getArg(0)->getLocStart(), 755 TheCall->getArg(1)->getLocEnd()); 756 return ExprError(); 757 } 758 759 numElements = LHSType->getAs<VectorType>()->getNumElements(); 760 unsigned numResElements = TheCall->getNumArgs() - 2; 761 762 // Check to see if we have a call with 2 vector arguments, the unary shuffle 763 // with mask. If so, verify that RHS is an integer vector type with the 764 // same number of elts as lhs. 765 if (TheCall->getNumArgs() == 2) { 766 if (!RHSType->hasIntegerRepresentation() || 767 RHSType->getAs<VectorType>()->getNumElements() != numElements) 768 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 769 << SourceRange(TheCall->getArg(1)->getLocStart(), 770 TheCall->getArg(1)->getLocEnd()); 771 numResElements = numElements; 772 } 773 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 774 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 775 << SourceRange(TheCall->getArg(0)->getLocStart(), 776 TheCall->getArg(1)->getLocEnd()); 777 return ExprError(); 778 } else if (numElements != numResElements) { 779 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 780 resType = Context.getVectorType(eltType, numResElements, 781 VectorType::GenericVector); 782 } 783 } 784 785 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 786 if (TheCall->getArg(i)->isTypeDependent() || 787 TheCall->getArg(i)->isValueDependent()) 788 continue; 789 790 llvm::APSInt Result(32); 791 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 792 return ExprError(Diag(TheCall->getLocStart(), 793 diag::err_shufflevector_nonconstant_argument) 794 << TheCall->getArg(i)->getSourceRange()); 795 796 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 797 return ExprError(Diag(TheCall->getLocStart(), 798 diag::err_shufflevector_argument_too_large) 799 << TheCall->getArg(i)->getSourceRange()); 800 } 801 802 llvm::SmallVector<Expr*, 32> exprs; 803 804 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 805 exprs.push_back(TheCall->getArg(i)); 806 TheCall->setArg(i, 0); 807 } 808 809 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 810 exprs.size(), resType, 811 TheCall->getCallee()->getLocStart(), 812 TheCall->getRParenLoc())); 813} 814 815/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 816// This is declared to take (const void*, ...) and can take two 817// optional constant int args. 818bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 819 unsigned NumArgs = TheCall->getNumArgs(); 820 821 if (NumArgs > 3) 822 return Diag(TheCall->getLocEnd(), 823 diag::err_typecheck_call_too_many_args_at_most) 824 << 0 /*function call*/ << 3 << NumArgs 825 << TheCall->getSourceRange(); 826 827 // Argument 0 is checked for us and the remaining arguments must be 828 // constant integers. 829 for (unsigned i = 1; i != NumArgs; ++i) { 830 Expr *Arg = TheCall->getArg(i); 831 832 llvm::APSInt Result; 833 if (SemaBuiltinConstantArg(TheCall, i, Result)) 834 return true; 835 836 // FIXME: gcc issues a warning and rewrites these to 0. These 837 // seems especially odd for the third argument since the default 838 // is 3. 839 if (i == 1) { 840 if (Result.getLimitedValue() > 1) 841 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 842 << "0" << "1" << Arg->getSourceRange(); 843 } else { 844 if (Result.getLimitedValue() > 3) 845 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 846 << "0" << "3" << Arg->getSourceRange(); 847 } 848 } 849 850 return false; 851} 852 853/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 854/// TheCall is a constant expression. 855bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 856 llvm::APSInt &Result) { 857 Expr *Arg = TheCall->getArg(ArgNum); 858 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 859 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 860 861 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 862 863 if (!Arg->isIntegerConstantExpr(Result, Context)) 864 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 865 << FDecl->getDeclName() << Arg->getSourceRange(); 866 867 return false; 868} 869 870/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 871/// int type). This simply type checks that type is one of the defined 872/// constants (0-3). 873// For compatibility check 0-3, llvm only handles 0 and 2. 874bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 875 llvm::APSInt Result; 876 877 // Check constant-ness first. 878 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 879 return true; 880 881 Expr *Arg = TheCall->getArg(1); 882 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 883 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 884 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 885 } 886 887 return false; 888} 889 890/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 891/// This checks that val is a constant 1. 892bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 893 Expr *Arg = TheCall->getArg(1); 894 llvm::APSInt Result; 895 896 // TODO: This is less than ideal. Overload this to take a value. 897 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 898 return true; 899 900 if (Result != 1) 901 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 902 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 903 904 return false; 905} 906 907// Handle i > 1 ? "x" : "y", recursively. 908bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 909 bool HasVAListArg, 910 unsigned format_idx, unsigned firstDataArg, 911 bool isPrintf) { 912 tryAgain: 913 if (E->isTypeDependent() || E->isValueDependent()) 914 return false; 915 916 E = E->IgnoreParens(); 917 918 switch (E->getStmtClass()) { 919 case Stmt::BinaryConditionalOperatorClass: 920 case Stmt::ConditionalOperatorClass: { 921 const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); 922 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 923 format_idx, firstDataArg, isPrintf) 924 && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg, 925 format_idx, firstDataArg, isPrintf); 926 } 927 928 case Stmt::IntegerLiteralClass: 929 // Technically -Wformat-nonliteral does not warn about this case. 930 // The behavior of printf and friends in this case is implementation 931 // dependent. Ideally if the format string cannot be null then 932 // it should have a 'nonnull' attribute in the function prototype. 933 return true; 934 935 case Stmt::ImplicitCastExprClass: { 936 E = cast<ImplicitCastExpr>(E)->getSubExpr(); 937 goto tryAgain; 938 } 939 940 case Stmt::OpaqueValueExprClass: 941 if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { 942 E = src; 943 goto tryAgain; 944 } 945 return false; 946 947 case Stmt::PredefinedExprClass: 948 // While __func__, etc., are technically not string literals, they 949 // cannot contain format specifiers and thus are not a security 950 // liability. 951 return true; 952 953 case Stmt::DeclRefExprClass: { 954 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 955 956 // As an exception, do not flag errors for variables binding to 957 // const string literals. 958 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 959 bool isConstant = false; 960 QualType T = DR->getType(); 961 962 if (const ArrayType *AT = Context.getAsArrayType(T)) { 963 isConstant = AT->getElementType().isConstant(Context); 964 } else if (const PointerType *PT = T->getAs<PointerType>()) { 965 isConstant = T.isConstant(Context) && 966 PT->getPointeeType().isConstant(Context); 967 } 968 969 if (isConstant) { 970 if (const Expr *Init = VD->getAnyInitializer()) 971 return SemaCheckStringLiteral(Init, TheCall, 972 HasVAListArg, format_idx, firstDataArg, 973 isPrintf); 974 } 975 976 // For vprintf* functions (i.e., HasVAListArg==true), we add a 977 // special check to see if the format string is a function parameter 978 // of the function calling the printf function. If the function 979 // has an attribute indicating it is a printf-like function, then we 980 // should suppress warnings concerning non-literals being used in a call 981 // to a vprintf function. For example: 982 // 983 // void 984 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 985 // va_list ap; 986 // va_start(ap, fmt); 987 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 988 // ... 989 // 990 // 991 // FIXME: We don't have full attribute support yet, so just check to see 992 // if the argument is a DeclRefExpr that references a parameter. We'll 993 // add proper support for checking the attribute later. 994 if (HasVAListArg) 995 if (isa<ParmVarDecl>(VD)) 996 return true; 997 } 998 999 return false; 1000 } 1001 1002 case Stmt::CallExprClass: { 1003 const CallExpr *CE = cast<CallExpr>(E); 1004 if (const ImplicitCastExpr *ICE 1005 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1006 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1007 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1008 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1009 unsigned ArgIndex = FA->getFormatIdx(); 1010 const Expr *Arg = CE->getArg(ArgIndex - 1); 1011 1012 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1013 format_idx, firstDataArg, isPrintf); 1014 } 1015 } 1016 } 1017 } 1018 1019 return false; 1020 } 1021 case Stmt::ObjCStringLiteralClass: 1022 case Stmt::StringLiteralClass: { 1023 const StringLiteral *StrE = NULL; 1024 1025 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1026 StrE = ObjCFExpr->getString(); 1027 else 1028 StrE = cast<StringLiteral>(E); 1029 1030 if (StrE) { 1031 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1032 firstDataArg, isPrintf); 1033 return true; 1034 } 1035 1036 return false; 1037 } 1038 1039 default: 1040 return false; 1041 } 1042} 1043 1044void 1045Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1046 const Expr * const *ExprArgs, 1047 SourceLocation CallSiteLoc) { 1048 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1049 e = NonNull->args_end(); 1050 i != e; ++i) { 1051 const Expr *ArgExpr = ExprArgs[*i]; 1052 if (ArgExpr->isNullPointerConstant(Context, 1053 Expr::NPC_ValueDependentIsNotNull)) 1054 Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange(); 1055 } 1056} 1057 1058/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1059/// functions) for correct use of format strings. 1060void 1061Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1062 unsigned format_idx, unsigned firstDataArg, 1063 bool isPrintf) { 1064 1065 const Expr *Fn = TheCall->getCallee(); 1066 1067 // The way the format attribute works in GCC, the implicit this argument 1068 // of member functions is counted. However, it doesn't appear in our own 1069 // lists, so decrement format_idx in that case. 1070 if (isa<CXXMemberCallExpr>(TheCall)) { 1071 const CXXMethodDecl *method_decl = 1072 dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl()); 1073 if (method_decl && method_decl->isInstance()) { 1074 // Catch a format attribute mistakenly referring to the object argument. 1075 if (format_idx == 0) 1076 return; 1077 --format_idx; 1078 if(firstDataArg != 0) 1079 --firstDataArg; 1080 } 1081 } 1082 1083 // CHECK: printf/scanf-like function is called with no format string. 1084 if (format_idx >= TheCall->getNumArgs()) { 1085 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1086 << Fn->getSourceRange(); 1087 return; 1088 } 1089 1090 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1091 1092 // CHECK: format string is not a string literal. 1093 // 1094 // Dynamically generated format strings are difficult to 1095 // automatically vet at compile time. Requiring that format strings 1096 // are string literals: (1) permits the checking of format strings by 1097 // the compiler and thereby (2) can practically remove the source of 1098 // many format string exploits. 1099 1100 // Format string can be either ObjC string (e.g. @"%d") or 1101 // C string (e.g. "%d") 1102 // ObjC string uses the same format specifiers as C string, so we can use 1103 // the same format string checking logic for both ObjC and C strings. 1104 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1105 firstDataArg, isPrintf)) 1106 return; // Literal format string found, check done! 1107 1108 // If there are no arguments specified, warn with -Wformat-security, otherwise 1109 // warn only with -Wformat-nonliteral. 1110 if (TheCall->getNumArgs() == format_idx+1) 1111 Diag(TheCall->getArg(format_idx)->getLocStart(), 1112 diag::warn_format_nonliteral_noargs) 1113 << OrigFormatExpr->getSourceRange(); 1114 else 1115 Diag(TheCall->getArg(format_idx)->getLocStart(), 1116 diag::warn_format_nonliteral) 1117 << OrigFormatExpr->getSourceRange(); 1118} 1119 1120namespace { 1121class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1122protected: 1123 Sema &S; 1124 const StringLiteral *FExpr; 1125 const Expr *OrigFormatExpr; 1126 const unsigned FirstDataArg; 1127 const unsigned NumDataArgs; 1128 const bool IsObjCLiteral; 1129 const char *Beg; // Start of format string. 1130 const bool HasVAListArg; 1131 const CallExpr *TheCall; 1132 unsigned FormatIdx; 1133 llvm::BitVector CoveredArgs; 1134 bool usesPositionalArgs; 1135 bool atFirstArg; 1136public: 1137 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1138 const Expr *origFormatExpr, unsigned firstDataArg, 1139 unsigned numDataArgs, bool isObjCLiteral, 1140 const char *beg, bool hasVAListArg, 1141 const CallExpr *theCall, unsigned formatIdx) 1142 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1143 FirstDataArg(firstDataArg), 1144 NumDataArgs(numDataArgs), 1145 IsObjCLiteral(isObjCLiteral), Beg(beg), 1146 HasVAListArg(hasVAListArg), 1147 TheCall(theCall), FormatIdx(formatIdx), 1148 usesPositionalArgs(false), atFirstArg(true) { 1149 CoveredArgs.resize(numDataArgs); 1150 CoveredArgs.reset(); 1151 } 1152 1153 void DoneProcessing(); 1154 1155 void HandleIncompleteSpecifier(const char *startSpecifier, 1156 unsigned specifierLen); 1157 1158 virtual void HandleInvalidPosition(const char *startSpecifier, 1159 unsigned specifierLen, 1160 analyze_format_string::PositionContext p); 1161 1162 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1163 1164 void HandleNullChar(const char *nullCharacter); 1165 1166protected: 1167 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1168 const char *startSpec, 1169 unsigned specifierLen, 1170 const char *csStart, unsigned csLen); 1171 1172 SourceRange getFormatStringRange(); 1173 CharSourceRange getSpecifierRange(const char *startSpecifier, 1174 unsigned specifierLen); 1175 SourceLocation getLocationOfByte(const char *x); 1176 1177 const Expr *getDataArg(unsigned i) const; 1178 1179 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1180 const analyze_format_string::ConversionSpecifier &CS, 1181 const char *startSpecifier, unsigned specifierLen, 1182 unsigned argIndex); 1183}; 1184} 1185 1186SourceRange CheckFormatHandler::getFormatStringRange() { 1187 return OrigFormatExpr->getSourceRange(); 1188} 1189 1190CharSourceRange CheckFormatHandler:: 1191getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1192 SourceLocation Start = getLocationOfByte(startSpecifier); 1193 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1194 1195 // Advance the end SourceLocation by one due to half-open ranges. 1196 End = End.getFileLocWithOffset(1); 1197 1198 return CharSourceRange::getCharRange(Start, End); 1199} 1200 1201SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1202 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1203} 1204 1205void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1206 unsigned specifierLen){ 1207 SourceLocation Loc = getLocationOfByte(startSpecifier); 1208 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1209 << getSpecifierRange(startSpecifier, specifierLen); 1210} 1211 1212void 1213CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1214 analyze_format_string::PositionContext p) { 1215 SourceLocation Loc = getLocationOfByte(startPos); 1216 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1217 << (unsigned) p << getSpecifierRange(startPos, posLen); 1218} 1219 1220void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1221 unsigned posLen) { 1222 SourceLocation Loc = getLocationOfByte(startPos); 1223 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1224 << getSpecifierRange(startPos, posLen); 1225} 1226 1227void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1228 if (!IsObjCLiteral) { 1229 // The presence of a null character is likely an error. 1230 S.Diag(getLocationOfByte(nullCharacter), 1231 diag::warn_printf_format_string_contains_null_char) 1232 << getFormatStringRange(); 1233 } 1234} 1235 1236const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1237 return TheCall->getArg(FirstDataArg + i); 1238} 1239 1240void CheckFormatHandler::DoneProcessing() { 1241 // Does the number of data arguments exceed the number of 1242 // format conversions in the format string? 1243 if (!HasVAListArg) { 1244 // Find any arguments that weren't covered. 1245 CoveredArgs.flip(); 1246 signed notCoveredArg = CoveredArgs.find_first(); 1247 if (notCoveredArg >= 0) { 1248 assert((unsigned)notCoveredArg < NumDataArgs); 1249 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1250 diag::warn_printf_data_arg_not_used) 1251 << getFormatStringRange(); 1252 } 1253 } 1254} 1255 1256bool 1257CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1258 SourceLocation Loc, 1259 const char *startSpec, 1260 unsigned specifierLen, 1261 const char *csStart, 1262 unsigned csLen) { 1263 1264 bool keepGoing = true; 1265 if (argIndex < NumDataArgs) { 1266 // Consider the argument coverered, even though the specifier doesn't 1267 // make sense. 1268 CoveredArgs.set(argIndex); 1269 } 1270 else { 1271 // If argIndex exceeds the number of data arguments we 1272 // don't issue a warning because that is just a cascade of warnings (and 1273 // they may have intended '%%' anyway). We don't want to continue processing 1274 // the format string after this point, however, as we will like just get 1275 // gibberish when trying to match arguments. 1276 keepGoing = false; 1277 } 1278 1279 S.Diag(Loc, diag::warn_format_invalid_conversion) 1280 << llvm::StringRef(csStart, csLen) 1281 << getSpecifierRange(startSpec, specifierLen); 1282 1283 return keepGoing; 1284} 1285 1286bool 1287CheckFormatHandler::CheckNumArgs( 1288 const analyze_format_string::FormatSpecifier &FS, 1289 const analyze_format_string::ConversionSpecifier &CS, 1290 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1291 1292 if (argIndex >= NumDataArgs) { 1293 if (FS.usesPositionalArg()) { 1294 S.Diag(getLocationOfByte(CS.getStart()), 1295 diag::warn_printf_positional_arg_exceeds_data_args) 1296 << (argIndex+1) << NumDataArgs 1297 << getSpecifierRange(startSpecifier, specifierLen); 1298 } 1299 else { 1300 S.Diag(getLocationOfByte(CS.getStart()), 1301 diag::warn_printf_insufficient_data_args) 1302 << getSpecifierRange(startSpecifier, specifierLen); 1303 } 1304 1305 return false; 1306 } 1307 return true; 1308} 1309 1310//===--- CHECK: Printf format string checking ------------------------------===// 1311 1312namespace { 1313class CheckPrintfHandler : public CheckFormatHandler { 1314public: 1315 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1316 const Expr *origFormatExpr, unsigned firstDataArg, 1317 unsigned numDataArgs, bool isObjCLiteral, 1318 const char *beg, bool hasVAListArg, 1319 const CallExpr *theCall, unsigned formatIdx) 1320 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1321 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1322 theCall, formatIdx) {} 1323 1324 1325 bool HandleInvalidPrintfConversionSpecifier( 1326 const analyze_printf::PrintfSpecifier &FS, 1327 const char *startSpecifier, 1328 unsigned specifierLen); 1329 1330 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1331 const char *startSpecifier, 1332 unsigned specifierLen); 1333 1334 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1335 const char *startSpecifier, unsigned specifierLen); 1336 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1337 const analyze_printf::OptionalAmount &Amt, 1338 unsigned type, 1339 const char *startSpecifier, unsigned specifierLen); 1340 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1341 const analyze_printf::OptionalFlag &flag, 1342 const char *startSpecifier, unsigned specifierLen); 1343 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1344 const analyze_printf::OptionalFlag &ignoredFlag, 1345 const analyze_printf::OptionalFlag &flag, 1346 const char *startSpecifier, unsigned specifierLen); 1347}; 1348} 1349 1350bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1351 const analyze_printf::PrintfSpecifier &FS, 1352 const char *startSpecifier, 1353 unsigned specifierLen) { 1354 const analyze_printf::PrintfConversionSpecifier &CS = 1355 FS.getConversionSpecifier(); 1356 1357 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1358 getLocationOfByte(CS.getStart()), 1359 startSpecifier, specifierLen, 1360 CS.getStart(), CS.getLength()); 1361} 1362 1363bool CheckPrintfHandler::HandleAmount( 1364 const analyze_format_string::OptionalAmount &Amt, 1365 unsigned k, const char *startSpecifier, 1366 unsigned specifierLen) { 1367 1368 if (Amt.hasDataArgument()) { 1369 if (!HasVAListArg) { 1370 unsigned argIndex = Amt.getArgIndex(); 1371 if (argIndex >= NumDataArgs) { 1372 S.Diag(getLocationOfByte(Amt.getStart()), 1373 diag::warn_printf_asterisk_missing_arg) 1374 << k << getSpecifierRange(startSpecifier, specifierLen); 1375 // Don't do any more checking. We will just emit 1376 // spurious errors. 1377 return false; 1378 } 1379 1380 // Type check the data argument. It should be an 'int'. 1381 // Although not in conformance with C99, we also allow the argument to be 1382 // an 'unsigned int' as that is a reasonably safe case. GCC also 1383 // doesn't emit a warning for that case. 1384 CoveredArgs.set(argIndex); 1385 const Expr *Arg = getDataArg(argIndex); 1386 QualType T = Arg->getType(); 1387 1388 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1389 assert(ATR.isValid()); 1390 1391 if (!ATR.matchesType(S.Context, T)) { 1392 S.Diag(getLocationOfByte(Amt.getStart()), 1393 diag::warn_printf_asterisk_wrong_type) 1394 << k 1395 << ATR.getRepresentativeType(S.Context) << T 1396 << getSpecifierRange(startSpecifier, specifierLen) 1397 << Arg->getSourceRange(); 1398 // Don't do any more checking. We will just emit 1399 // spurious errors. 1400 return false; 1401 } 1402 } 1403 } 1404 return true; 1405} 1406 1407void CheckPrintfHandler::HandleInvalidAmount( 1408 const analyze_printf::PrintfSpecifier &FS, 1409 const analyze_printf::OptionalAmount &Amt, 1410 unsigned type, 1411 const char *startSpecifier, 1412 unsigned specifierLen) { 1413 const analyze_printf::PrintfConversionSpecifier &CS = 1414 FS.getConversionSpecifier(); 1415 switch (Amt.getHowSpecified()) { 1416 case analyze_printf::OptionalAmount::Constant: 1417 S.Diag(getLocationOfByte(Amt.getStart()), 1418 diag::warn_printf_nonsensical_optional_amount) 1419 << type 1420 << CS.toString() 1421 << getSpecifierRange(startSpecifier, specifierLen) 1422 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1423 Amt.getConstantLength())); 1424 break; 1425 1426 default: 1427 S.Diag(getLocationOfByte(Amt.getStart()), 1428 diag::warn_printf_nonsensical_optional_amount) 1429 << type 1430 << CS.toString() 1431 << getSpecifierRange(startSpecifier, specifierLen); 1432 break; 1433 } 1434} 1435 1436void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1437 const analyze_printf::OptionalFlag &flag, 1438 const char *startSpecifier, 1439 unsigned specifierLen) { 1440 // Warn about pointless flag with a fixit removal. 1441 const analyze_printf::PrintfConversionSpecifier &CS = 1442 FS.getConversionSpecifier(); 1443 S.Diag(getLocationOfByte(flag.getPosition()), 1444 diag::warn_printf_nonsensical_flag) 1445 << flag.toString() << CS.toString() 1446 << getSpecifierRange(startSpecifier, specifierLen) 1447 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1448} 1449 1450void CheckPrintfHandler::HandleIgnoredFlag( 1451 const analyze_printf::PrintfSpecifier &FS, 1452 const analyze_printf::OptionalFlag &ignoredFlag, 1453 const analyze_printf::OptionalFlag &flag, 1454 const char *startSpecifier, 1455 unsigned specifierLen) { 1456 // Warn about ignored flag with a fixit removal. 1457 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1458 diag::warn_printf_ignored_flag) 1459 << ignoredFlag.toString() << flag.toString() 1460 << getSpecifierRange(startSpecifier, specifierLen) 1461 << FixItHint::CreateRemoval(getSpecifierRange( 1462 ignoredFlag.getPosition(), 1)); 1463} 1464 1465bool 1466CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1467 &FS, 1468 const char *startSpecifier, 1469 unsigned specifierLen) { 1470 1471 using namespace analyze_format_string; 1472 using namespace analyze_printf; 1473 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1474 1475 if (FS.consumesDataArgument()) { 1476 if (atFirstArg) { 1477 atFirstArg = false; 1478 usesPositionalArgs = FS.usesPositionalArg(); 1479 } 1480 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1481 // Cannot mix-and-match positional and non-positional arguments. 1482 S.Diag(getLocationOfByte(CS.getStart()), 1483 diag::warn_format_mix_positional_nonpositional_args) 1484 << getSpecifierRange(startSpecifier, specifierLen); 1485 return false; 1486 } 1487 } 1488 1489 // First check if the field width, precision, and conversion specifier 1490 // have matching data arguments. 1491 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1492 startSpecifier, specifierLen)) { 1493 return false; 1494 } 1495 1496 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1497 startSpecifier, specifierLen)) { 1498 return false; 1499 } 1500 1501 if (!CS.consumesDataArgument()) { 1502 // FIXME: Technically specifying a precision or field width here 1503 // makes no sense. Worth issuing a warning at some point. 1504 return true; 1505 } 1506 1507 // Consume the argument. 1508 unsigned argIndex = FS.getArgIndex(); 1509 if (argIndex < NumDataArgs) { 1510 // The check to see if the argIndex is valid will come later. 1511 // We set the bit here because we may exit early from this 1512 // function if we encounter some other error. 1513 CoveredArgs.set(argIndex); 1514 } 1515 1516 // Check for using an Objective-C specific conversion specifier 1517 // in a non-ObjC literal. 1518 if (!IsObjCLiteral && CS.isObjCArg()) { 1519 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1520 specifierLen); 1521 } 1522 1523 // Check for invalid use of field width 1524 if (!FS.hasValidFieldWidth()) { 1525 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1526 startSpecifier, specifierLen); 1527 } 1528 1529 // Check for invalid use of precision 1530 if (!FS.hasValidPrecision()) { 1531 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1532 startSpecifier, specifierLen); 1533 } 1534 1535 // Check each flag does not conflict with any other component. 1536 if (!FS.hasValidThousandsGroupingPrefix()) 1537 HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); 1538 if (!FS.hasValidLeadingZeros()) 1539 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1540 if (!FS.hasValidPlusPrefix()) 1541 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1542 if (!FS.hasValidSpacePrefix()) 1543 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1544 if (!FS.hasValidAlternativeForm()) 1545 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1546 if (!FS.hasValidLeftJustified()) 1547 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1548 1549 // Check that flags are not ignored by another flag 1550 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1551 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1552 startSpecifier, specifierLen); 1553 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1554 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1555 startSpecifier, specifierLen); 1556 1557 // Check the length modifier is valid with the given conversion specifier. 1558 const LengthModifier &LM = FS.getLengthModifier(); 1559 if (!FS.hasValidLengthModifier()) 1560 S.Diag(getLocationOfByte(LM.getStart()), 1561 diag::warn_format_nonsensical_length) 1562 << LM.toString() << CS.toString() 1563 << getSpecifierRange(startSpecifier, specifierLen) 1564 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1565 LM.getLength())); 1566 1567 // Are we using '%n'? 1568 if (CS.getKind() == ConversionSpecifier::nArg) { 1569 // Issue a warning about this being a possible security issue. 1570 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1571 << getSpecifierRange(startSpecifier, specifierLen); 1572 // Continue checking the other format specifiers. 1573 return true; 1574 } 1575 1576 // The remaining checks depend on the data arguments. 1577 if (HasVAListArg) 1578 return true; 1579 1580 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1581 return false; 1582 1583 // Now type check the data expression that matches the 1584 // format specifier. 1585 const Expr *Ex = getDataArg(argIndex); 1586 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1587 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1588 // Check if we didn't match because of an implicit cast from a 'char' 1589 // or 'short' to an 'int'. This is done because printf is a varargs 1590 // function. 1591 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1592 if (ICE->getType() == S.Context.IntTy) { 1593 // All further checking is done on the subexpression. 1594 Ex = ICE->getSubExpr(); 1595 if (ATR.matchesType(S.Context, Ex->getType())) 1596 return true; 1597 } 1598 1599 // We may be able to offer a FixItHint if it is a supported type. 1600 PrintfSpecifier fixedFS = FS; 1601 bool success = fixedFS.fixType(Ex->getType()); 1602 1603 if (success) { 1604 // Get the fix string from the fixed format specifier 1605 llvm::SmallString<128> buf; 1606 llvm::raw_svector_ostream os(buf); 1607 fixedFS.toString(os); 1608 1609 // FIXME: getRepresentativeType() perhaps should return a string 1610 // instead of a QualType to better handle when the representative 1611 // type is 'wint_t' (which is defined in the system headers). 1612 S.Diag(getLocationOfByte(CS.getStart()), 1613 diag::warn_printf_conversion_argument_type_mismatch) 1614 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1615 << getSpecifierRange(startSpecifier, specifierLen) 1616 << Ex->getSourceRange() 1617 << FixItHint::CreateReplacement( 1618 getSpecifierRange(startSpecifier, specifierLen), 1619 os.str()); 1620 } 1621 else { 1622 S.Diag(getLocationOfByte(CS.getStart()), 1623 diag::warn_printf_conversion_argument_type_mismatch) 1624 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1625 << getSpecifierRange(startSpecifier, specifierLen) 1626 << Ex->getSourceRange(); 1627 } 1628 } 1629 1630 return true; 1631} 1632 1633//===--- CHECK: Scanf format string checking ------------------------------===// 1634 1635namespace { 1636class CheckScanfHandler : public CheckFormatHandler { 1637public: 1638 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1639 const Expr *origFormatExpr, unsigned firstDataArg, 1640 unsigned numDataArgs, bool isObjCLiteral, 1641 const char *beg, bool hasVAListArg, 1642 const CallExpr *theCall, unsigned formatIdx) 1643 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1644 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1645 theCall, formatIdx) {} 1646 1647 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1648 const char *startSpecifier, 1649 unsigned specifierLen); 1650 1651 bool HandleInvalidScanfConversionSpecifier( 1652 const analyze_scanf::ScanfSpecifier &FS, 1653 const char *startSpecifier, 1654 unsigned specifierLen); 1655 1656 void HandleIncompleteScanList(const char *start, const char *end); 1657}; 1658} 1659 1660void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1661 const char *end) { 1662 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1663 << getSpecifierRange(start, end - start); 1664} 1665 1666bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1667 const analyze_scanf::ScanfSpecifier &FS, 1668 const char *startSpecifier, 1669 unsigned specifierLen) { 1670 1671 const analyze_scanf::ScanfConversionSpecifier &CS = 1672 FS.getConversionSpecifier(); 1673 1674 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1675 getLocationOfByte(CS.getStart()), 1676 startSpecifier, specifierLen, 1677 CS.getStart(), CS.getLength()); 1678} 1679 1680bool CheckScanfHandler::HandleScanfSpecifier( 1681 const analyze_scanf::ScanfSpecifier &FS, 1682 const char *startSpecifier, 1683 unsigned specifierLen) { 1684 1685 using namespace analyze_scanf; 1686 using namespace analyze_format_string; 1687 1688 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1689 1690 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1691 // be used to decide if we are using positional arguments consistently. 1692 if (FS.consumesDataArgument()) { 1693 if (atFirstArg) { 1694 atFirstArg = false; 1695 usesPositionalArgs = FS.usesPositionalArg(); 1696 } 1697 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1698 // Cannot mix-and-match positional and non-positional arguments. 1699 S.Diag(getLocationOfByte(CS.getStart()), 1700 diag::warn_format_mix_positional_nonpositional_args) 1701 << getSpecifierRange(startSpecifier, specifierLen); 1702 return false; 1703 } 1704 } 1705 1706 // Check if the field with is non-zero. 1707 const OptionalAmount &Amt = FS.getFieldWidth(); 1708 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1709 if (Amt.getConstantAmount() == 0) { 1710 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1711 Amt.getConstantLength()); 1712 S.Diag(getLocationOfByte(Amt.getStart()), 1713 diag::warn_scanf_nonzero_width) 1714 << R << FixItHint::CreateRemoval(R); 1715 } 1716 } 1717 1718 if (!FS.consumesDataArgument()) { 1719 // FIXME: Technically specifying a precision or field width here 1720 // makes no sense. Worth issuing a warning at some point. 1721 return true; 1722 } 1723 1724 // Consume the argument. 1725 unsigned argIndex = FS.getArgIndex(); 1726 if (argIndex < NumDataArgs) { 1727 // The check to see if the argIndex is valid will come later. 1728 // We set the bit here because we may exit early from this 1729 // function if we encounter some other error. 1730 CoveredArgs.set(argIndex); 1731 } 1732 1733 // Check the length modifier is valid with the given conversion specifier. 1734 const LengthModifier &LM = FS.getLengthModifier(); 1735 if (!FS.hasValidLengthModifier()) { 1736 S.Diag(getLocationOfByte(LM.getStart()), 1737 diag::warn_format_nonsensical_length) 1738 << LM.toString() << CS.toString() 1739 << getSpecifierRange(startSpecifier, specifierLen) 1740 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1741 LM.getLength())); 1742 } 1743 1744 // The remaining checks depend on the data arguments. 1745 if (HasVAListArg) 1746 return true; 1747 1748 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1749 return false; 1750 1751 // FIXME: Check that the argument type matches the format specifier. 1752 1753 return true; 1754} 1755 1756void Sema::CheckFormatString(const StringLiteral *FExpr, 1757 const Expr *OrigFormatExpr, 1758 const CallExpr *TheCall, bool HasVAListArg, 1759 unsigned format_idx, unsigned firstDataArg, 1760 bool isPrintf) { 1761 1762 // CHECK: is the format string a wide literal? 1763 if (FExpr->isWide()) { 1764 Diag(FExpr->getLocStart(), 1765 diag::warn_format_string_is_wide_literal) 1766 << OrigFormatExpr->getSourceRange(); 1767 return; 1768 } 1769 1770 // Str - The format string. NOTE: this is NOT null-terminated! 1771 llvm::StringRef StrRef = FExpr->getString(); 1772 const char *Str = StrRef.data(); 1773 unsigned StrLen = StrRef.size(); 1774 1775 // CHECK: empty format string? 1776 if (StrLen == 0) { 1777 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1778 << OrigFormatExpr->getSourceRange(); 1779 return; 1780 } 1781 1782 if (isPrintf) { 1783 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1784 TheCall->getNumArgs() - firstDataArg, 1785 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1786 HasVAListArg, TheCall, format_idx); 1787 1788 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1789 H.DoneProcessing(); 1790 } 1791 else { 1792 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1793 TheCall->getNumArgs() - firstDataArg, 1794 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1795 HasVAListArg, TheCall, format_idx); 1796 1797 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1798 H.DoneProcessing(); 1799 } 1800} 1801 1802//===--- CHECK: Standard memory functions ---------------------------------===// 1803 1804/// \brief Determine whether the given type is a dynamic class type (e.g., 1805/// whether it has a vtable). 1806static bool isDynamicClassType(QualType T) { 1807 if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) 1808 if (CXXRecordDecl *Definition = Record->getDefinition()) 1809 if (Definition->isDynamicClass()) 1810 return true; 1811 1812 return false; 1813} 1814 1815/// \brief If E is a sizeof expression, returns the expression's type in 1816/// OutType. 1817static bool sizeofExprType(const Expr* E, QualType *OutType) { 1818 if (const UnaryExprOrTypeTraitExpr *SizeOf = 1819 dyn_cast<UnaryExprOrTypeTraitExpr>(E)) { 1820 if (SizeOf->getKind() != clang::UETT_SizeOf) 1821 return false; 1822 1823 *OutType = SizeOf->getTypeOfArgument(); 1824 return true; 1825 } 1826 return false; 1827} 1828 1829/// \brief Check for dangerous or invalid arguments to memset(). 1830/// 1831/// This issues warnings on known problematic, dangerous or unspecified 1832/// arguments to the standard 'memset', 'memcpy', and 'memmove' function calls. 1833/// 1834/// \param Call The call expression to diagnose. 1835void Sema::CheckMemsetcpymoveArguments(const CallExpr *Call, 1836 const IdentifierInfo *FnName) { 1837 // It is possible to have a non-standard definition of memset. Validate 1838 // we have the proper number of arguments, and if not, abort further 1839 // checking. 1840 if (Call->getNumArgs() != 3) 1841 return; 1842 1843 unsigned LastArg = FnName->isStr("memset")? 1 : 2; 1844 const Expr *LenExpr = Call->getArg(2)->IgnoreParenImpCasts(); 1845 for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) { 1846 const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts(); 1847 SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange(); 1848 1849 QualType DestTy = Dest->getType(); 1850 if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) { 1851 QualType PointeeTy = DestPtrTy->getPointeeType(); 1852 if (PointeeTy->isVoidType()) 1853 continue; 1854 1855 // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). 1856 QualType SizeofTy; 1857 if (sizeofExprType(LenExpr, &SizeofTy) && 1858 Context.typesAreCompatible(SizeofTy, DestTy)) { 1859 // Note: This complains about sizeof(typeof(p)) as well. 1860 SourceLocation loc = LenExpr->getSourceRange().getBegin(); 1861 Diag(loc, diag::warn_sizeof_pointer) 1862 << SizeofTy << PointeeTy << ArgIdx << FnName; 1863 break; 1864 } 1865 1866 // Always complain about dynamic classes. 1867 if (isDynamicClassType(PointeeTy)) { 1868 DiagRuntimeBehavior( 1869 Dest->getExprLoc(), Dest, 1870 PDiag(diag::warn_dyn_class_memaccess) 1871 << ArgIdx << FnName << PointeeTy 1872 << Call->getCallee()->getSourceRange()); 1873 } else { 1874 continue; 1875 } 1876 1877 DiagRuntimeBehavior( 1878 Dest->getExprLoc(), Dest, 1879 PDiag(diag::note_bad_memaccess_silence) 1880 << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)")); 1881 break; 1882 } 1883 } 1884} 1885 1886//===--- CHECK: Return Address of Stack Variable --------------------------===// 1887 1888static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1889static Expr *EvalAddr(Expr* E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1890 1891/// CheckReturnStackAddr - Check if a return statement returns the address 1892/// of a stack variable. 1893void 1894Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1895 SourceLocation ReturnLoc) { 1896 1897 Expr *stackE = 0; 1898 llvm::SmallVector<DeclRefExpr *, 8> refVars; 1899 1900 // Perform checking for returned stack addresses, local blocks, 1901 // label addresses or references to temporaries. 1902 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1903 stackE = EvalAddr(RetValExp, refVars); 1904 } else if (lhsType->isReferenceType()) { 1905 stackE = EvalVal(RetValExp, refVars); 1906 } 1907 1908 if (stackE == 0) 1909 return; // Nothing suspicious was found. 1910 1911 SourceLocation diagLoc; 1912 SourceRange diagRange; 1913 if (refVars.empty()) { 1914 diagLoc = stackE->getLocStart(); 1915 diagRange = stackE->getSourceRange(); 1916 } else { 1917 // We followed through a reference variable. 'stackE' contains the 1918 // problematic expression but we will warn at the return statement pointing 1919 // at the reference variable. We will later display the "trail" of 1920 // reference variables using notes. 1921 diagLoc = refVars[0]->getLocStart(); 1922 diagRange = refVars[0]->getSourceRange(); 1923 } 1924 1925 if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. 1926 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref 1927 : diag::warn_ret_stack_addr) 1928 << DR->getDecl()->getDeclName() << diagRange; 1929 } else if (isa<BlockExpr>(stackE)) { // local block. 1930 Diag(diagLoc, diag::err_ret_local_block) << diagRange; 1931 } else if (isa<AddrLabelExpr>(stackE)) { // address of label. 1932 Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; 1933 } else { // local temporary. 1934 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref 1935 : diag::warn_ret_local_temp_addr) 1936 << diagRange; 1937 } 1938 1939 // Display the "trail" of reference variables that we followed until we 1940 // found the problematic expression using notes. 1941 for (unsigned i = 0, e = refVars.size(); i != e; ++i) { 1942 VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); 1943 // If this var binds to another reference var, show the range of the next 1944 // var, otherwise the var binds to the problematic expression, in which case 1945 // show the range of the expression. 1946 SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() 1947 : stackE->getSourceRange(); 1948 Diag(VD->getLocation(), diag::note_ref_var_local_bind) 1949 << VD->getDeclName() << range; 1950 } 1951} 1952 1953/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1954/// check if the expression in a return statement evaluates to an address 1955/// to a location on the stack, a local block, an address of a label, or a 1956/// reference to local temporary. The recursion is used to traverse the 1957/// AST of the return expression, with recursion backtracking when we 1958/// encounter a subexpression that (1) clearly does not lead to one of the 1959/// above problematic expressions (2) is something we cannot determine leads to 1960/// a problematic expression based on such local checking. 1961/// 1962/// Both EvalAddr and EvalVal follow through reference variables to evaluate 1963/// the expression that they point to. Such variables are added to the 1964/// 'refVars' vector so that we know what the reference variable "trail" was. 1965/// 1966/// EvalAddr processes expressions that are pointers that are used as 1967/// references (and not L-values). EvalVal handles all other values. 1968/// At the base case of the recursion is a check for the above problematic 1969/// expressions. 1970/// 1971/// This implementation handles: 1972/// 1973/// * pointer-to-pointer casts 1974/// * implicit conversions from array references to pointers 1975/// * taking the address of fields 1976/// * arbitrary interplay between "&" and "*" operators 1977/// * pointer arithmetic from an address of a stack variable 1978/// * taking the address of an array element where the array is on the stack 1979static Expr *EvalAddr(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 1980 if (E->isTypeDependent()) 1981 return NULL; 1982 1983 // We should only be called for evaluating pointer expressions. 1984 assert((E->getType()->isAnyPointerType() || 1985 E->getType()->isBlockPointerType() || 1986 E->getType()->isObjCQualifiedIdType()) && 1987 "EvalAddr only works on pointers"); 1988 1989 E = E->IgnoreParens(); 1990 1991 // Our "symbolic interpreter" is just a dispatch off the currently 1992 // viewed AST node. We then recursively traverse the AST by calling 1993 // EvalAddr and EvalVal appropriately. 1994 switch (E->getStmtClass()) { 1995 case Stmt::DeclRefExprClass: { 1996 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1997 1998 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1999 // If this is a reference variable, follow through to the expression that 2000 // it points to. 2001 if (V->hasLocalStorage() && 2002 V->getType()->isReferenceType() && V->hasInit()) { 2003 // Add the reference variable to the "trail". 2004 refVars.push_back(DR); 2005 return EvalAddr(V->getInit(), refVars); 2006 } 2007 2008 return NULL; 2009 } 2010 2011 case Stmt::UnaryOperatorClass: { 2012 // The only unary operator that make sense to handle here 2013 // is AddrOf. All others don't make sense as pointers. 2014 UnaryOperator *U = cast<UnaryOperator>(E); 2015 2016 if (U->getOpcode() == UO_AddrOf) 2017 return EvalVal(U->getSubExpr(), refVars); 2018 else 2019 return NULL; 2020 } 2021 2022 case Stmt::BinaryOperatorClass: { 2023 // Handle pointer arithmetic. All other binary operators are not valid 2024 // in this context. 2025 BinaryOperator *B = cast<BinaryOperator>(E); 2026 BinaryOperatorKind op = B->getOpcode(); 2027 2028 if (op != BO_Add && op != BO_Sub) 2029 return NULL; 2030 2031 Expr *Base = B->getLHS(); 2032 2033 // Determine which argument is the real pointer base. It could be 2034 // the RHS argument instead of the LHS. 2035 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 2036 2037 assert (Base->getType()->isPointerType()); 2038 return EvalAddr(Base, refVars); 2039 } 2040 2041 // For conditional operators we need to see if either the LHS or RHS are 2042 // valid DeclRefExpr*s. If one of them is valid, we return it. 2043 case Stmt::ConditionalOperatorClass: { 2044 ConditionalOperator *C = cast<ConditionalOperator>(E); 2045 2046 // Handle the GNU extension for missing LHS. 2047 if (Expr *lhsExpr = C->getLHS()) { 2048 // In C++, we can have a throw-expression, which has 'void' type. 2049 if (!lhsExpr->getType()->isVoidType()) 2050 if (Expr* LHS = EvalAddr(lhsExpr, refVars)) 2051 return LHS; 2052 } 2053 2054 // In C++, we can have a throw-expression, which has 'void' type. 2055 if (C->getRHS()->getType()->isVoidType()) 2056 return NULL; 2057 2058 return EvalAddr(C->getRHS(), refVars); 2059 } 2060 2061 case Stmt::BlockExprClass: 2062 if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) 2063 return E; // local block. 2064 return NULL; 2065 2066 case Stmt::AddrLabelExprClass: 2067 return E; // address of label. 2068 2069 // For casts, we need to handle conversions from arrays to 2070 // pointer values, and pointer-to-pointer conversions. 2071 case Stmt::ImplicitCastExprClass: 2072 case Stmt::CStyleCastExprClass: 2073 case Stmt::CXXFunctionalCastExprClass: { 2074 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 2075 QualType T = SubExpr->getType(); 2076 2077 if (SubExpr->getType()->isPointerType() || 2078 SubExpr->getType()->isBlockPointerType() || 2079 SubExpr->getType()->isObjCQualifiedIdType()) 2080 return EvalAddr(SubExpr, refVars); 2081 else if (T->isArrayType()) 2082 return EvalVal(SubExpr, refVars); 2083 else 2084 return 0; 2085 } 2086 2087 // C++ casts. For dynamic casts, static casts, and const casts, we 2088 // are always converting from a pointer-to-pointer, so we just blow 2089 // through the cast. In the case the dynamic cast doesn't fail (and 2090 // return NULL), we take the conservative route and report cases 2091 // where we return the address of a stack variable. For Reinterpre 2092 // FIXME: The comment about is wrong; we're not always converting 2093 // from pointer to pointer. I'm guessing that this code should also 2094 // handle references to objects. 2095 case Stmt::CXXStaticCastExprClass: 2096 case Stmt::CXXDynamicCastExprClass: 2097 case Stmt::CXXConstCastExprClass: 2098 case Stmt::CXXReinterpretCastExprClass: { 2099 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 2100 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 2101 return EvalAddr(S, refVars); 2102 else 2103 return NULL; 2104 } 2105 2106 // Everything else: we simply don't reason about them. 2107 default: 2108 return NULL; 2109 } 2110} 2111 2112 2113/// EvalVal - This function is complements EvalAddr in the mutual recursion. 2114/// See the comments for EvalAddr for more details. 2115static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 2116do { 2117 // We should only be called for evaluating non-pointer expressions, or 2118 // expressions with a pointer type that are not used as references but instead 2119 // are l-values (e.g., DeclRefExpr with a pointer type). 2120 2121 // Our "symbolic interpreter" is just a dispatch off the currently 2122 // viewed AST node. We then recursively traverse the AST by calling 2123 // EvalAddr and EvalVal appropriately. 2124 2125 E = E->IgnoreParens(); 2126 switch (E->getStmtClass()) { 2127 case Stmt::ImplicitCastExprClass: { 2128 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 2129 if (IE->getValueKind() == VK_LValue) { 2130 E = IE->getSubExpr(); 2131 continue; 2132 } 2133 return NULL; 2134 } 2135 2136 case Stmt::DeclRefExprClass: { 2137 // When we hit a DeclRefExpr we are looking at code that refers to a 2138 // variable's name. If it's not a reference variable we check if it has 2139 // local storage within the function, and if so, return the expression. 2140 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2141 2142 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2143 if (V->hasLocalStorage()) { 2144 if (!V->getType()->isReferenceType()) 2145 return DR; 2146 2147 // Reference variable, follow through to the expression that 2148 // it points to. 2149 if (V->hasInit()) { 2150 // Add the reference variable to the "trail". 2151 refVars.push_back(DR); 2152 return EvalVal(V->getInit(), refVars); 2153 } 2154 } 2155 2156 return NULL; 2157 } 2158 2159 case Stmt::UnaryOperatorClass: { 2160 // The only unary operator that make sense to handle here 2161 // is Deref. All others don't resolve to a "name." This includes 2162 // handling all sorts of rvalues passed to a unary operator. 2163 UnaryOperator *U = cast<UnaryOperator>(E); 2164 2165 if (U->getOpcode() == UO_Deref) 2166 return EvalAddr(U->getSubExpr(), refVars); 2167 2168 return NULL; 2169 } 2170 2171 case Stmt::ArraySubscriptExprClass: { 2172 // Array subscripts are potential references to data on the stack. We 2173 // retrieve the DeclRefExpr* for the array variable if it indeed 2174 // has local storage. 2175 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars); 2176 } 2177 2178 case Stmt::ConditionalOperatorClass: { 2179 // For conditional operators we need to see if either the LHS or RHS are 2180 // non-NULL Expr's. If one is non-NULL, we return it. 2181 ConditionalOperator *C = cast<ConditionalOperator>(E); 2182 2183 // Handle the GNU extension for missing LHS. 2184 if (Expr *lhsExpr = C->getLHS()) 2185 if (Expr *LHS = EvalVal(lhsExpr, refVars)) 2186 return LHS; 2187 2188 return EvalVal(C->getRHS(), refVars); 2189 } 2190 2191 // Accesses to members are potential references to data on the stack. 2192 case Stmt::MemberExprClass: { 2193 MemberExpr *M = cast<MemberExpr>(E); 2194 2195 // Check for indirect access. We only want direct field accesses. 2196 if (M->isArrow()) 2197 return NULL; 2198 2199 // Check whether the member type is itself a reference, in which case 2200 // we're not going to refer to the member, but to what the member refers to. 2201 if (M->getMemberDecl()->getType()->isReferenceType()) 2202 return NULL; 2203 2204 return EvalVal(M->getBase(), refVars); 2205 } 2206 2207 default: 2208 // Check that we don't return or take the address of a reference to a 2209 // temporary. This is only useful in C++. 2210 if (!E->isTypeDependent() && E->isRValue()) 2211 return E; 2212 2213 // Everything else: we simply don't reason about them. 2214 return NULL; 2215 } 2216} while (true); 2217} 2218 2219//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2220 2221/// Check for comparisons of floating point operands using != and ==. 2222/// Issue a warning if these are no self-comparisons, as they are not likely 2223/// to do what the programmer intended. 2224void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2225 bool EmitWarning = true; 2226 2227 Expr* LeftExprSansParen = lex->IgnoreParenImpCasts(); 2228 Expr* RightExprSansParen = rex->IgnoreParenImpCasts(); 2229 2230 // Special case: check for x == x (which is OK). 2231 // Do not emit warnings for such cases. 2232 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2233 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2234 if (DRL->getDecl() == DRR->getDecl()) 2235 EmitWarning = false; 2236 2237 2238 // Special case: check for comparisons against literals that can be exactly 2239 // represented by APFloat. In such cases, do not emit a warning. This 2240 // is a heuristic: often comparison against such literals are used to 2241 // detect if a value in a variable has not changed. This clearly can 2242 // lead to false negatives. 2243 if (EmitWarning) { 2244 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2245 if (FLL->isExact()) 2246 EmitWarning = false; 2247 } else 2248 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2249 if (FLR->isExact()) 2250 EmitWarning = false; 2251 } 2252 } 2253 2254 // Check for comparisons with builtin types. 2255 if (EmitWarning) 2256 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2257 if (CL->isBuiltinCall(Context)) 2258 EmitWarning = false; 2259 2260 if (EmitWarning) 2261 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2262 if (CR->isBuiltinCall(Context)) 2263 EmitWarning = false; 2264 2265 // Emit the diagnostic. 2266 if (EmitWarning) 2267 Diag(loc, diag::warn_floatingpoint_eq) 2268 << lex->getSourceRange() << rex->getSourceRange(); 2269} 2270 2271//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2272//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2273 2274namespace { 2275 2276/// Structure recording the 'active' range of an integer-valued 2277/// expression. 2278struct IntRange { 2279 /// The number of bits active in the int. 2280 unsigned Width; 2281 2282 /// True if the int is known not to have negative values. 2283 bool NonNegative; 2284 2285 IntRange(unsigned Width, bool NonNegative) 2286 : Width(Width), NonNegative(NonNegative) 2287 {} 2288 2289 /// Returns the range of the bool type. 2290 static IntRange forBoolType() { 2291 return IntRange(1, true); 2292 } 2293 2294 /// Returns the range of an opaque value of the given integral type. 2295 static IntRange forValueOfType(ASTContext &C, QualType T) { 2296 return forValueOfCanonicalType(C, 2297 T->getCanonicalTypeInternal().getTypePtr()); 2298 } 2299 2300 /// Returns the range of an opaque value of a canonical integral type. 2301 static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) { 2302 assert(T->isCanonicalUnqualified()); 2303 2304 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2305 T = VT->getElementType().getTypePtr(); 2306 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2307 T = CT->getElementType().getTypePtr(); 2308 2309 // For enum types, use the known bit width of the enumerators. 2310 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2311 EnumDecl *Enum = ET->getDecl(); 2312 if (!Enum->isDefinition()) 2313 return IntRange(C.getIntWidth(QualType(T, 0)), false); 2314 2315 unsigned NumPositive = Enum->getNumPositiveBits(); 2316 unsigned NumNegative = Enum->getNumNegativeBits(); 2317 2318 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2319 } 2320 2321 const BuiltinType *BT = cast<BuiltinType>(T); 2322 assert(BT->isInteger()); 2323 2324 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2325 } 2326 2327 /// Returns the "target" range of a canonical integral type, i.e. 2328 /// the range of values expressible in the type. 2329 /// 2330 /// This matches forValueOfCanonicalType except that enums have the 2331 /// full range of their type, not the range of their enumerators. 2332 static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) { 2333 assert(T->isCanonicalUnqualified()); 2334 2335 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2336 T = VT->getElementType().getTypePtr(); 2337 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2338 T = CT->getElementType().getTypePtr(); 2339 if (const EnumType *ET = dyn_cast<EnumType>(T)) 2340 T = ET->getDecl()->getIntegerType().getTypePtr(); 2341 2342 const BuiltinType *BT = cast<BuiltinType>(T); 2343 assert(BT->isInteger()); 2344 2345 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2346 } 2347 2348 /// Returns the supremum of two ranges: i.e. their conservative merge. 2349 static IntRange join(IntRange L, IntRange R) { 2350 return IntRange(std::max(L.Width, R.Width), 2351 L.NonNegative && R.NonNegative); 2352 } 2353 2354 /// Returns the infinum of two ranges: i.e. their aggressive merge. 2355 static IntRange meet(IntRange L, IntRange R) { 2356 return IntRange(std::min(L.Width, R.Width), 2357 L.NonNegative || R.NonNegative); 2358 } 2359}; 2360 2361IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2362 if (value.isSigned() && value.isNegative()) 2363 return IntRange(value.getMinSignedBits(), false); 2364 2365 if (value.getBitWidth() > MaxWidth) 2366 value = value.trunc(MaxWidth); 2367 2368 // isNonNegative() just checks the sign bit without considering 2369 // signedness. 2370 return IntRange(value.getActiveBits(), true); 2371} 2372 2373IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2374 unsigned MaxWidth) { 2375 if (result.isInt()) 2376 return GetValueRange(C, result.getInt(), MaxWidth); 2377 2378 if (result.isVector()) { 2379 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2380 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2381 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2382 R = IntRange::join(R, El); 2383 } 2384 return R; 2385 } 2386 2387 if (result.isComplexInt()) { 2388 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2389 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2390 return IntRange::join(R, I); 2391 } 2392 2393 // This can happen with lossless casts to intptr_t of "based" lvalues. 2394 // Assume it might use arbitrary bits. 2395 // FIXME: The only reason we need to pass the type in here is to get 2396 // the sign right on this one case. It would be nice if APValue 2397 // preserved this. 2398 assert(result.isLValue()); 2399 return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType()); 2400} 2401 2402/// Pseudo-evaluate the given integer expression, estimating the 2403/// range of values it might take. 2404/// 2405/// \param MaxWidth - the width to which the value will be truncated 2406IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2407 E = E->IgnoreParens(); 2408 2409 // Try a full evaluation first. 2410 Expr::EvalResult result; 2411 if (E->Evaluate(result, C)) 2412 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2413 2414 // I think we only want to look through implicit casts here; if the 2415 // user has an explicit widening cast, we should treat the value as 2416 // being of the new, wider type. 2417 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2418 if (CE->getCastKind() == CK_NoOp) 2419 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2420 2421 IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); 2422 2423 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 2424 2425 // Assume that non-integer casts can span the full range of the type. 2426 if (!isIntegerCast) 2427 return OutputTypeRange; 2428 2429 IntRange SubRange 2430 = GetExprRange(C, CE->getSubExpr(), 2431 std::min(MaxWidth, OutputTypeRange.Width)); 2432 2433 // Bail out if the subexpr's range is as wide as the cast type. 2434 if (SubRange.Width >= OutputTypeRange.Width) 2435 return OutputTypeRange; 2436 2437 // Otherwise, we take the smaller width, and we're non-negative if 2438 // either the output type or the subexpr is. 2439 return IntRange(SubRange.Width, 2440 SubRange.NonNegative || OutputTypeRange.NonNegative); 2441 } 2442 2443 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2444 // If we can fold the condition, just take that operand. 2445 bool CondResult; 2446 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2447 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2448 : CO->getFalseExpr(), 2449 MaxWidth); 2450 2451 // Otherwise, conservatively merge. 2452 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2453 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2454 return IntRange::join(L, R); 2455 } 2456 2457 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2458 switch (BO->getOpcode()) { 2459 2460 // Boolean-valued operations are single-bit and positive. 2461 case BO_LAnd: 2462 case BO_LOr: 2463 case BO_LT: 2464 case BO_GT: 2465 case BO_LE: 2466 case BO_GE: 2467 case BO_EQ: 2468 case BO_NE: 2469 return IntRange::forBoolType(); 2470 2471 // The type of these compound assignments is the type of the LHS, 2472 // so the RHS is not necessarily an integer. 2473 case BO_MulAssign: 2474 case BO_DivAssign: 2475 case BO_RemAssign: 2476 case BO_AddAssign: 2477 case BO_SubAssign: 2478 return IntRange::forValueOfType(C, E->getType()); 2479 2480 // Operations with opaque sources are black-listed. 2481 case BO_PtrMemD: 2482 case BO_PtrMemI: 2483 return IntRange::forValueOfType(C, E->getType()); 2484 2485 // Bitwise-and uses the *infinum* of the two source ranges. 2486 case BO_And: 2487 case BO_AndAssign: 2488 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2489 GetExprRange(C, BO->getRHS(), MaxWidth)); 2490 2491 // Left shift gets black-listed based on a judgement call. 2492 case BO_Shl: 2493 // ...except that we want to treat '1 << (blah)' as logically 2494 // positive. It's an important idiom. 2495 if (IntegerLiteral *I 2496 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2497 if (I->getValue() == 1) { 2498 IntRange R = IntRange::forValueOfType(C, E->getType()); 2499 return IntRange(R.Width, /*NonNegative*/ true); 2500 } 2501 } 2502 // fallthrough 2503 2504 case BO_ShlAssign: 2505 return IntRange::forValueOfType(C, E->getType()); 2506 2507 // Right shift by a constant can narrow its left argument. 2508 case BO_Shr: 2509 case BO_ShrAssign: { 2510 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2511 2512 // If the shift amount is a positive constant, drop the width by 2513 // that much. 2514 llvm::APSInt shift; 2515 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2516 shift.isNonNegative()) { 2517 unsigned zext = shift.getZExtValue(); 2518 if (zext >= L.Width) 2519 L.Width = (L.NonNegative ? 0 : 1); 2520 else 2521 L.Width -= zext; 2522 } 2523 2524 return L; 2525 } 2526 2527 // Comma acts as its right operand. 2528 case BO_Comma: 2529 return GetExprRange(C, BO->getRHS(), MaxWidth); 2530 2531 // Black-list pointer subtractions. 2532 case BO_Sub: 2533 if (BO->getLHS()->getType()->isPointerType()) 2534 return IntRange::forValueOfType(C, E->getType()); 2535 // fallthrough 2536 2537 default: 2538 break; 2539 } 2540 2541 // Treat every other operator as if it were closed on the 2542 // narrowest type that encompasses both operands. 2543 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2544 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2545 return IntRange::join(L, R); 2546 } 2547 2548 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2549 switch (UO->getOpcode()) { 2550 // Boolean-valued operations are white-listed. 2551 case UO_LNot: 2552 return IntRange::forBoolType(); 2553 2554 // Operations with opaque sources are black-listed. 2555 case UO_Deref: 2556 case UO_AddrOf: // should be impossible 2557 return IntRange::forValueOfType(C, E->getType()); 2558 2559 default: 2560 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2561 } 2562 } 2563 2564 if (dyn_cast<OffsetOfExpr>(E)) { 2565 IntRange::forValueOfType(C, E->getType()); 2566 } 2567 2568 FieldDecl *BitField = E->getBitField(); 2569 if (BitField) { 2570 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2571 unsigned BitWidth = BitWidthAP.getZExtValue(); 2572 2573 return IntRange(BitWidth, 2574 BitField->getType()->isUnsignedIntegerOrEnumerationType()); 2575 } 2576 2577 return IntRange::forValueOfType(C, E->getType()); 2578} 2579 2580IntRange GetExprRange(ASTContext &C, Expr *E) { 2581 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2582} 2583 2584/// Checks whether the given value, which currently has the given 2585/// source semantics, has the same value when coerced through the 2586/// target semantics. 2587bool IsSameFloatAfterCast(const llvm::APFloat &value, 2588 const llvm::fltSemantics &Src, 2589 const llvm::fltSemantics &Tgt) { 2590 llvm::APFloat truncated = value; 2591 2592 bool ignored; 2593 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2594 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2595 2596 return truncated.bitwiseIsEqual(value); 2597} 2598 2599/// Checks whether the given value, which currently has the given 2600/// source semantics, has the same value when coerced through the 2601/// target semantics. 2602/// 2603/// The value might be a vector of floats (or a complex number). 2604bool IsSameFloatAfterCast(const APValue &value, 2605 const llvm::fltSemantics &Src, 2606 const llvm::fltSemantics &Tgt) { 2607 if (value.isFloat()) 2608 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2609 2610 if (value.isVector()) { 2611 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2612 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2613 return false; 2614 return true; 2615 } 2616 2617 assert(value.isComplexFloat()); 2618 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2619 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2620} 2621 2622void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC); 2623 2624static bool IsZero(Sema &S, Expr *E) { 2625 // Suppress cases where we are comparing against an enum constant. 2626 if (const DeclRefExpr *DR = 2627 dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) 2628 if (isa<EnumConstantDecl>(DR->getDecl())) 2629 return false; 2630 2631 // Suppress cases where the '0' value is expanded from a macro. 2632 if (E->getLocStart().isMacroID()) 2633 return false; 2634 2635 llvm::APSInt Value; 2636 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2637} 2638 2639static bool HasEnumType(Expr *E) { 2640 // Strip off implicit integral promotions. 2641 while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { 2642 if (ICE->getCastKind() != CK_IntegralCast && 2643 ICE->getCastKind() != CK_NoOp) 2644 break; 2645 E = ICE->getSubExpr(); 2646 } 2647 2648 return E->getType()->isEnumeralType(); 2649} 2650 2651void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2652 BinaryOperatorKind op = E->getOpcode(); 2653 if (E->isValueDependent()) 2654 return; 2655 2656 if (op == BO_LT && IsZero(S, E->getRHS())) { 2657 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2658 << "< 0" << "false" << HasEnumType(E->getLHS()) 2659 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2660 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 2661 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2662 << ">= 0" << "true" << HasEnumType(E->getLHS()) 2663 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2664 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 2665 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2666 << "0 >" << "false" << HasEnumType(E->getRHS()) 2667 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2668 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 2669 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2670 << "0 <=" << "true" << HasEnumType(E->getRHS()) 2671 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2672 } 2673} 2674 2675/// Analyze the operands of the given comparison. Implements the 2676/// fallback case from AnalyzeComparison. 2677void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2678 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2679 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2680} 2681 2682/// \brief Implements -Wsign-compare. 2683/// 2684/// \param lex the left-hand expression 2685/// \param rex the right-hand expression 2686/// \param OpLoc the location of the joining operator 2687/// \param BinOpc binary opcode or 0 2688void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2689 // The type the comparison is being performed in. 2690 QualType T = E->getLHS()->getType(); 2691 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2692 && "comparison with mismatched types"); 2693 2694 // We don't do anything special if this isn't an unsigned integral 2695 // comparison: we're only interested in integral comparisons, and 2696 // signed comparisons only happen in cases we don't care to warn about. 2697 // 2698 // We also don't care about value-dependent expressions or expressions 2699 // whose result is a constant. 2700 if (!T->hasUnsignedIntegerRepresentation() 2701 || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) 2702 return AnalyzeImpConvsInComparison(S, E); 2703 2704 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2705 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2706 2707 // Check to see if one of the (unmodified) operands is of different 2708 // signedness. 2709 Expr *signedOperand, *unsignedOperand; 2710 if (lex->getType()->hasSignedIntegerRepresentation()) { 2711 assert(!rex->getType()->hasSignedIntegerRepresentation() && 2712 "unsigned comparison between two signed integer expressions?"); 2713 signedOperand = lex; 2714 unsignedOperand = rex; 2715 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 2716 signedOperand = rex; 2717 unsignedOperand = lex; 2718 } else { 2719 CheckTrivialUnsignedComparison(S, E); 2720 return AnalyzeImpConvsInComparison(S, E); 2721 } 2722 2723 // Otherwise, calculate the effective range of the signed operand. 2724 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2725 2726 // Go ahead and analyze implicit conversions in the operands. Note 2727 // that we skip the implicit conversions on both sides. 2728 AnalyzeImplicitConversions(S, lex, E->getOperatorLoc()); 2729 AnalyzeImplicitConversions(S, rex, E->getOperatorLoc()); 2730 2731 // If the signed range is non-negative, -Wsign-compare won't fire, 2732 // but we should still check for comparisons which are always true 2733 // or false. 2734 if (signedRange.NonNegative) 2735 return CheckTrivialUnsignedComparison(S, E); 2736 2737 // For (in)equality comparisons, if the unsigned operand is a 2738 // constant which cannot collide with a overflowed signed operand, 2739 // then reinterpreting the signed operand as unsigned will not 2740 // change the result of the comparison. 2741 if (E->isEqualityOp()) { 2742 unsigned comparisonWidth = S.Context.getIntWidth(T); 2743 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2744 2745 // We should never be unable to prove that the unsigned operand is 2746 // non-negative. 2747 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2748 2749 if (unsignedRange.Width < comparisonWidth) 2750 return; 2751 } 2752 2753 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2754 << lex->getType() << rex->getType() 2755 << lex->getSourceRange() << rex->getSourceRange(); 2756} 2757 2758/// Analyzes an attempt to assign the given value to a bitfield. 2759/// 2760/// Returns true if there was something fishy about the attempt. 2761bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, 2762 SourceLocation InitLoc) { 2763 assert(Bitfield->isBitField()); 2764 if (Bitfield->isInvalidDecl()) 2765 return false; 2766 2767 // White-list bool bitfields. 2768 if (Bitfield->getType()->isBooleanType()) 2769 return false; 2770 2771 // Ignore value- or type-dependent expressions. 2772 if (Bitfield->getBitWidth()->isValueDependent() || 2773 Bitfield->getBitWidth()->isTypeDependent() || 2774 Init->isValueDependent() || 2775 Init->isTypeDependent()) 2776 return false; 2777 2778 Expr *OriginalInit = Init->IgnoreParenImpCasts(); 2779 2780 llvm::APSInt Width(32); 2781 Expr::EvalResult InitValue; 2782 if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) || 2783 !OriginalInit->Evaluate(InitValue, S.Context) || 2784 !InitValue.Val.isInt()) 2785 return false; 2786 2787 const llvm::APSInt &Value = InitValue.Val.getInt(); 2788 unsigned OriginalWidth = Value.getBitWidth(); 2789 unsigned FieldWidth = Width.getZExtValue(); 2790 2791 if (OriginalWidth <= FieldWidth) 2792 return false; 2793 2794 llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); 2795 2796 // It's fairly common to write values into signed bitfields 2797 // that, if sign-extended, would end up becoming a different 2798 // value. We don't want to warn about that. 2799 if (Value.isSigned() && Value.isNegative()) 2800 TruncatedValue = TruncatedValue.sext(OriginalWidth); 2801 else 2802 TruncatedValue = TruncatedValue.zext(OriginalWidth); 2803 2804 if (Value == TruncatedValue) 2805 return false; 2806 2807 std::string PrettyValue = Value.toString(10); 2808 std::string PrettyTrunc = TruncatedValue.toString(10); 2809 2810 S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) 2811 << PrettyValue << PrettyTrunc << OriginalInit->getType() 2812 << Init->getSourceRange(); 2813 2814 return true; 2815} 2816 2817/// Analyze the given simple or compound assignment for warning-worthy 2818/// operations. 2819void AnalyzeAssignment(Sema &S, BinaryOperator *E) { 2820 // Just recurse on the LHS. 2821 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2822 2823 // We want to recurse on the RHS as normal unless we're assigning to 2824 // a bitfield. 2825 if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { 2826 if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), 2827 E->getOperatorLoc())) { 2828 // Recurse, ignoring any implicit conversions on the RHS. 2829 return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), 2830 E->getOperatorLoc()); 2831 } 2832 } 2833 2834 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2835} 2836 2837/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2838void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 2839 SourceLocation CContext, unsigned diag) { 2840 S.Diag(E->getExprLoc(), diag) 2841 << SourceType << T << E->getSourceRange() << SourceRange(CContext); 2842} 2843 2844/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2845void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext, 2846 unsigned diag) { 2847 DiagnoseImpCast(S, E, E->getType(), T, CContext, diag); 2848} 2849 2850/// Diagnose an implicit cast from a literal expression. Also attemps to supply 2851/// fixit hints when the cast wouldn't lose information to simply write the 2852/// expression with the expected type. 2853void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T, 2854 SourceLocation CContext) { 2855 // Emit the primary warning first, then try to emit a fixit hint note if 2856 // reasonable. 2857 S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer) 2858 << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext); 2859 2860 const llvm::APFloat &Value = FL->getValue(); 2861 2862 // Don't attempt to fix PPC double double literals. 2863 if (&Value.getSemantics() == &llvm::APFloat::PPCDoubleDouble) 2864 return; 2865 2866 // Try to convert this exactly to an 64-bit integer. FIXME: It would be 2867 // nice to support arbitrarily large integers here. 2868 bool isExact = false; 2869 uint64_t IntegerPart; 2870 if (Value.convertToInteger(&IntegerPart, 64, /*isSigned=*/true, 2871 llvm::APFloat::rmTowardZero, &isExact) 2872 != llvm::APFloat::opOK || !isExact) 2873 return; 2874 2875 llvm::APInt IntegerValue(64, IntegerPart, /*isSigned=*/true); 2876 2877 std::string LiteralValue = IntegerValue.toString(10, /*isSigned=*/true); 2878 S.Diag(FL->getExprLoc(), diag::note_fix_integral_float_as_integer) 2879 << FixItHint::CreateReplacement(FL->getSourceRange(), LiteralValue); 2880} 2881 2882std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { 2883 if (!Range.Width) return "0"; 2884 2885 llvm::APSInt ValueInRange = Value; 2886 ValueInRange.setIsSigned(!Range.NonNegative); 2887 ValueInRange = ValueInRange.trunc(Range.Width); 2888 return ValueInRange.toString(10); 2889} 2890 2891static bool isFromSystemMacro(Sema &S, SourceLocation loc) { 2892 SourceManager &smgr = S.Context.getSourceManager(); 2893 return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc)); 2894} 2895 2896void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2897 SourceLocation CC, bool *ICContext = 0) { 2898 if (E->isTypeDependent() || E->isValueDependent()) return; 2899 2900 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2901 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2902 if (Source == Target) return; 2903 if (Target->isDependentType()) return; 2904 2905 // If the conversion context location is invalid don't complain. 2906 // We also don't want to emit a warning if the issue occurs from the 2907 // instantiation of a system macro. The problem is that 'getSpellingLoc()' 2908 // is slow, so we delay this check as long as possible. Once we detect 2909 // we are in that scenario, we just return. 2910 if (CC.isInvalid()) 2911 return; 2912 2913 // Never diagnose implicit casts to bool. 2914 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2915 return; 2916 2917 // Strip vector types. 2918 if (isa<VectorType>(Source)) { 2919 if (!isa<VectorType>(Target)) { 2920 if (isFromSystemMacro(S, CC)) 2921 return; 2922 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar); 2923 } 2924 2925 // If the vector cast is cast between two vectors of the same size, it is 2926 // a bitcast, not a conversion. 2927 if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target)) 2928 return; 2929 2930 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2931 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2932 } 2933 2934 // Strip complex types. 2935 if (isa<ComplexType>(Source)) { 2936 if (!isa<ComplexType>(Target)) { 2937 if (isFromSystemMacro(S, CC)) 2938 return; 2939 2940 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar); 2941 } 2942 2943 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2944 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2945 } 2946 2947 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2948 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2949 2950 // If the source is floating point... 2951 if (SourceBT && SourceBT->isFloatingPoint()) { 2952 // ...and the target is floating point... 2953 if (TargetBT && TargetBT->isFloatingPoint()) { 2954 // ...then warn if we're dropping FP rank. 2955 2956 // Builtin FP kinds are ordered by increasing FP rank. 2957 if (SourceBT->getKind() > TargetBT->getKind()) { 2958 // Don't warn about float constants that are precisely 2959 // representable in the target type. 2960 Expr::EvalResult result; 2961 if (E->Evaluate(result, S.Context)) { 2962 // Value might be a float, a float vector, or a float complex. 2963 if (IsSameFloatAfterCast(result.Val, 2964 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2965 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2966 return; 2967 } 2968 2969 if (isFromSystemMacro(S, CC)) 2970 return; 2971 2972 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision); 2973 } 2974 return; 2975 } 2976 2977 // If the target is integral, always warn. 2978 if ((TargetBT && TargetBT->isInteger())) { 2979 if (isFromSystemMacro(S, CC)) 2980 return; 2981 2982 Expr *InnerE = E->IgnoreParenImpCasts(); 2983 if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) { 2984 DiagnoseFloatingLiteralImpCast(S, FL, T, CC); 2985 } else { 2986 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); 2987 } 2988 } 2989 2990 return; 2991 } 2992 2993 if (!Source->isIntegerType() || !Target->isIntegerType()) 2994 return; 2995 2996 if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull) 2997 == Expr::NPCK_GNUNull) && Target->isIntegerType()) { 2998 S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer) 2999 << E->getSourceRange() << clang::SourceRange(CC); 3000 return; 3001 } 3002 3003 IntRange SourceRange = GetExprRange(S.Context, E); 3004 IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); 3005 3006 if (SourceRange.Width > TargetRange.Width) { 3007 // If the source is a constant, use a default-on diagnostic. 3008 // TODO: this should happen for bitfield stores, too. 3009 llvm::APSInt Value(32); 3010 if (E->isIntegerConstantExpr(Value, S.Context)) { 3011 if (isFromSystemMacro(S, CC)) 3012 return; 3013 3014 std::string PrettySourceValue = Value.toString(10); 3015 std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); 3016 3017 S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant) 3018 << PrettySourceValue << PrettyTargetValue 3019 << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC); 3020 return; 3021 } 3022 3023 // People want to build with -Wshorten-64-to-32 and not -Wconversion. 3024 if (isFromSystemMacro(S, CC)) 3025 return; 3026 3027 if (SourceRange.Width == 64 && TargetRange.Width == 32) 3028 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32); 3029 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); 3030 } 3031 3032 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 3033 (!TargetRange.NonNegative && SourceRange.NonNegative && 3034 SourceRange.Width == TargetRange.Width)) { 3035 3036 if (isFromSystemMacro(S, CC)) 3037 return; 3038 3039 unsigned DiagID = diag::warn_impcast_integer_sign; 3040 3041 // Traditionally, gcc has warned about this under -Wsign-compare. 3042 // We also want to warn about it in -Wconversion. 3043 // So if -Wconversion is off, use a completely identical diagnostic 3044 // in the sign-compare group. 3045 // The conditional-checking code will 3046 if (ICContext) { 3047 DiagID = diag::warn_impcast_integer_sign_conditional; 3048 *ICContext = true; 3049 } 3050 3051 return DiagnoseImpCast(S, E, T, CC, DiagID); 3052 } 3053 3054 // Diagnose conversions between different enumeration types. 3055 // In C, we pretend that the type of an EnumConstantDecl is its enumeration 3056 // type, to give us better diagnostics. 3057 QualType SourceType = E->getType(); 3058 if (!S.getLangOptions().CPlusPlus) { 3059 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 3060 if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) { 3061 EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext()); 3062 SourceType = S.Context.getTypeDeclType(Enum); 3063 Source = S.Context.getCanonicalType(SourceType).getTypePtr(); 3064 } 3065 } 3066 3067 if (const EnumType *SourceEnum = Source->getAs<EnumType>()) 3068 if (const EnumType *TargetEnum = Target->getAs<EnumType>()) 3069 if ((SourceEnum->getDecl()->getIdentifier() || 3070 SourceEnum->getDecl()->getTypedefNameForAnonDecl()) && 3071 (TargetEnum->getDecl()->getIdentifier() || 3072 TargetEnum->getDecl()->getTypedefNameForAnonDecl()) && 3073 SourceEnum != TargetEnum) { 3074 if (isFromSystemMacro(S, CC)) 3075 return; 3076 3077 return DiagnoseImpCast(S, E, SourceType, T, CC, 3078 diag::warn_impcast_different_enum_types); 3079 } 3080 3081 return; 3082} 3083 3084void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 3085 3086void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 3087 SourceLocation CC, bool &ICContext) { 3088 E = E->IgnoreParenImpCasts(); 3089 3090 if (isa<ConditionalOperator>(E)) 3091 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 3092 3093 AnalyzeImplicitConversions(S, E, CC); 3094 if (E->getType() != T) 3095 return CheckImplicitConversion(S, E, T, CC, &ICContext); 3096 return; 3097} 3098 3099void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 3100 SourceLocation CC = E->getQuestionLoc(); 3101 3102 AnalyzeImplicitConversions(S, E->getCond(), CC); 3103 3104 bool Suspicious = false; 3105 CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); 3106 CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious); 3107 3108 // If -Wconversion would have warned about either of the candidates 3109 // for a signedness conversion to the context type... 3110 if (!Suspicious) return; 3111 3112 // ...but it's currently ignored... 3113 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional, 3114 CC)) 3115 return; 3116 3117 // ...and -Wsign-compare isn't... 3118 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional, CC)) 3119 return; 3120 3121 // ...then check whether it would have warned about either of the 3122 // candidates for a signedness conversion to the condition type. 3123 if (E->getType() != T) { 3124 Suspicious = false; 3125 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 3126 E->getType(), CC, &Suspicious); 3127 if (!Suspicious) 3128 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 3129 E->getType(), CC, &Suspicious); 3130 if (!Suspicious) 3131 return; 3132 } 3133 3134 // If so, emit a diagnostic under -Wsign-compare. 3135 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 3136 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 3137 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 3138 << lex->getType() << rex->getType() 3139 << lex->getSourceRange() << rex->getSourceRange(); 3140} 3141 3142/// AnalyzeImplicitConversions - Find and report any interesting 3143/// implicit conversions in the given expression. There are a couple 3144/// of competing diagnostics here, -Wconversion and -Wsign-compare. 3145void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) { 3146 QualType T = OrigE->getType(); 3147 Expr *E = OrigE->IgnoreParenImpCasts(); 3148 3149 // For conditional operators, we analyze the arguments as if they 3150 // were being fed directly into the output. 3151 if (isa<ConditionalOperator>(E)) { 3152 ConditionalOperator *CO = cast<ConditionalOperator>(E); 3153 CheckConditionalOperator(S, CO, T); 3154 return; 3155 } 3156 3157 // Go ahead and check any implicit conversions we might have skipped. 3158 // The non-canonical typecheck is just an optimization; 3159 // CheckImplicitConversion will filter out dead implicit conversions. 3160 if (E->getType() != T) 3161 CheckImplicitConversion(S, E, T, CC); 3162 3163 // Now continue drilling into this expression. 3164 3165 // Skip past explicit casts. 3166 if (isa<ExplicitCastExpr>(E)) { 3167 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 3168 return AnalyzeImplicitConversions(S, E, CC); 3169 } 3170 3171 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 3172 // Do a somewhat different check with comparison operators. 3173 if (BO->isComparisonOp()) 3174 return AnalyzeComparison(S, BO); 3175 3176 // And with assignments and compound assignments. 3177 if (BO->isAssignmentOp()) 3178 return AnalyzeAssignment(S, BO); 3179 } 3180 3181 // These break the otherwise-useful invariant below. Fortunately, 3182 // we don't really need to recurse into them, because any internal 3183 // expressions should have been analyzed already when they were 3184 // built into statements. 3185 if (isa<StmtExpr>(E)) return; 3186 3187 // Don't descend into unevaluated contexts. 3188 if (isa<UnaryExprOrTypeTraitExpr>(E)) return; 3189 3190 // Now just recurse over the expression's children. 3191 CC = E->getExprLoc(); 3192 for (Stmt::child_range I = E->children(); I; ++I) 3193 AnalyzeImplicitConversions(S, cast<Expr>(*I), CC); 3194} 3195 3196} // end anonymous namespace 3197 3198/// Diagnoses "dangerous" implicit conversions within the given 3199/// expression (which is a full expression). Implements -Wconversion 3200/// and -Wsign-compare. 3201/// 3202/// \param CC the "context" location of the implicit conversion, i.e. 3203/// the most location of the syntactic entity requiring the implicit 3204/// conversion 3205void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { 3206 // Don't diagnose in unevaluated contexts. 3207 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 3208 return; 3209 3210 // Don't diagnose for value- or type-dependent expressions. 3211 if (E->isTypeDependent() || E->isValueDependent()) 3212 return; 3213 3214 // This is not the right CC for (e.g.) a variable initialization. 3215 AnalyzeImplicitConversions(*this, E, CC); 3216} 3217 3218void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, 3219 FieldDecl *BitField, 3220 Expr *Init) { 3221 (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); 3222} 3223 3224/// CheckParmsForFunctionDef - Check that the parameters of the given 3225/// function are appropriate for the definition of a function. This 3226/// takes care of any checks that cannot be performed on the 3227/// declaration itself, e.g., that the types of each of the function 3228/// parameters are complete. 3229bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd, 3230 bool CheckParameterNames) { 3231 bool HasInvalidParm = false; 3232 for (; P != PEnd; ++P) { 3233 ParmVarDecl *Param = *P; 3234 3235 // C99 6.7.5.3p4: the parameters in a parameter type list in a 3236 // function declarator that is part of a function definition of 3237 // that function shall not have incomplete type. 3238 // 3239 // This is also C++ [dcl.fct]p6. 3240 if (!Param->isInvalidDecl() && 3241 RequireCompleteType(Param->getLocation(), Param->getType(), 3242 diag::err_typecheck_decl_incomplete_type)) { 3243 Param->setInvalidDecl(); 3244 HasInvalidParm = true; 3245 } 3246 3247 // C99 6.9.1p5: If the declarator includes a parameter type list, the 3248 // declaration of each parameter shall include an identifier. 3249 if (CheckParameterNames && 3250 Param->getIdentifier() == 0 && 3251 !Param->isImplicit() && 3252 !getLangOptions().CPlusPlus) 3253 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 3254 3255 // C99 6.7.5.3p12: 3256 // If the function declarator is not part of a definition of that 3257 // function, parameters may have incomplete type and may use the [*] 3258 // notation in their sequences of declarator specifiers to specify 3259 // variable length array types. 3260 QualType PType = Param->getOriginalType(); 3261 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 3262 if (AT->getSizeModifier() == ArrayType::Star) { 3263 // FIXME: This diagnosic should point the the '[*]' if source-location 3264 // information is added for it. 3265 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 3266 } 3267 } 3268 } 3269 3270 return HasInvalidParm; 3271} 3272 3273/// CheckCastAlign - Implements -Wcast-align, which warns when a 3274/// pointer cast increases the alignment requirements. 3275void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 3276 // This is actually a lot of work to potentially be doing on every 3277 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 3278 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, 3279 TRange.getBegin()) 3280 == Diagnostic::Ignored) 3281 return; 3282 3283 // Ignore dependent types. 3284 if (T->isDependentType() || Op->getType()->isDependentType()) 3285 return; 3286 3287 // Require that the destination be a pointer type. 3288 const PointerType *DestPtr = T->getAs<PointerType>(); 3289 if (!DestPtr) return; 3290 3291 // If the destination has alignment 1, we're done. 3292 QualType DestPointee = DestPtr->getPointeeType(); 3293 if (DestPointee->isIncompleteType()) return; 3294 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 3295 if (DestAlign.isOne()) return; 3296 3297 // Require that the source be a pointer type. 3298 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 3299 if (!SrcPtr) return; 3300 QualType SrcPointee = SrcPtr->getPointeeType(); 3301 3302 // Whitelist casts from cv void*. We already implicitly 3303 // whitelisted casts to cv void*, since they have alignment 1. 3304 // Also whitelist casts involving incomplete types, which implicitly 3305 // includes 'void'. 3306 if (SrcPointee->isIncompleteType()) return; 3307 3308 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 3309 if (SrcAlign >= DestAlign) return; 3310 3311 Diag(TRange.getBegin(), diag::warn_cast_align) 3312 << Op->getType() << T 3313 << static_cast<unsigned>(SrcAlign.getQuantity()) 3314 << static_cast<unsigned>(DestAlign.getQuantity()) 3315 << TRange << Op->getSourceRange(); 3316} 3317 3318static void CheckArrayAccess_Check(Sema &S, 3319 const clang::ArraySubscriptExpr *E) { 3320 const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts(); 3321 const ConstantArrayType *ArrayTy = 3322 S.Context.getAsConstantArrayType(BaseExpr->getType()); 3323 if (!ArrayTy) 3324 return; 3325 3326 const Expr *IndexExpr = E->getIdx(); 3327 if (IndexExpr->isValueDependent()) 3328 return; 3329 llvm::APSInt index; 3330 if (!IndexExpr->isIntegerConstantExpr(index, S.Context)) 3331 return; 3332 3333 if (index.isUnsigned() || !index.isNegative()) { 3334 llvm::APInt size = ArrayTy->getSize(); 3335 if (!size.isStrictlyPositive()) 3336 return; 3337 if (size.getBitWidth() > index.getBitWidth()) 3338 index = index.sext(size.getBitWidth()); 3339 else if (size.getBitWidth() < index.getBitWidth()) 3340 size = size.sext(index.getBitWidth()); 3341 3342 if (index.slt(size)) 3343 return; 3344 3345 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3346 S.PDiag(diag::warn_array_index_exceeds_bounds) 3347 << index.toString(10, true) 3348 << size.toString(10, true) 3349 << IndexExpr->getSourceRange()); 3350 } else { 3351 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3352 S.PDiag(diag::warn_array_index_precedes_bounds) 3353 << index.toString(10, true) 3354 << IndexExpr->getSourceRange()); 3355 } 3356 3357 const NamedDecl *ND = NULL; 3358 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 3359 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 3360 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 3361 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 3362 if (ND) 3363 S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr, 3364 S.PDiag(diag::note_array_index_out_of_bounds) 3365 << ND->getDeclName()); 3366} 3367 3368void Sema::CheckArrayAccess(const Expr *expr) { 3369 while (true) { 3370 expr = expr->IgnoreParens(); 3371 switch (expr->getStmtClass()) { 3372 case Stmt::ArraySubscriptExprClass: 3373 CheckArrayAccess_Check(*this, cast<ArraySubscriptExpr>(expr)); 3374 return; 3375 case Stmt::ConditionalOperatorClass: { 3376 const ConditionalOperator *cond = cast<ConditionalOperator>(expr); 3377 if (const Expr *lhs = cond->getLHS()) 3378 CheckArrayAccess(lhs); 3379 if (const Expr *rhs = cond->getRHS()) 3380 CheckArrayAccess(rhs); 3381 return; 3382 } 3383 default: 3384 return; 3385 } 3386 } 3387} 3388