SemaChecking.cpp revision ef9ff88f54ff26ac9782d98a34b74aa424149be1
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 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 184 } 185 186 // Since the target specific builtins for each arch overlap, only check those 187 // of the arch we are compiling for. 188 if (BuiltinID >= Builtin::FirstTSBuiltin) { 189 switch (Context.Target.getTriple().getArch()) { 190 case llvm::Triple::arm: 191 case llvm::Triple::thumb: 192 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 193 return ExprError(); 194 break; 195 default: 196 break; 197 } 198 } 199 200 return move(TheCallResult); 201} 202 203// Get the valid immediate range for the specified NEON type code. 204static unsigned RFT(unsigned t, bool shift = false) { 205 bool quad = t & 0x10; 206 207 switch (t & 0x7) { 208 case 0: // i8 209 return shift ? 7 : (8 << (int)quad) - 1; 210 case 1: // i16 211 return shift ? 15 : (4 << (int)quad) - 1; 212 case 2: // i32 213 return shift ? 31 : (2 << (int)quad) - 1; 214 case 3: // i64 215 return shift ? 63 : (1 << (int)quad) - 1; 216 case 4: // f32 217 assert(!shift && "cannot shift float types!"); 218 return (2 << (int)quad) - 1; 219 case 5: // poly8 220 return shift ? 7 : (8 << (int)quad) - 1; 221 case 6: // poly16 222 return shift ? 15 : (4 << (int)quad) - 1; 223 case 7: // float16 224 assert(!shift && "cannot shift float types!"); 225 return (4 << (int)quad) - 1; 226 } 227 return 0; 228} 229 230bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 231 llvm::APSInt Result; 232 233 unsigned mask = 0; 234 unsigned TV = 0; 235 switch (BuiltinID) { 236#define GET_NEON_OVERLOAD_CHECK 237#include "clang/Basic/arm_neon.inc" 238#undef GET_NEON_OVERLOAD_CHECK 239 } 240 241 // For NEON intrinsics which are overloaded on vector element type, validate 242 // the immediate which specifies which variant to emit. 243 if (mask) { 244 unsigned ArgNo = TheCall->getNumArgs()-1; 245 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 246 return true; 247 248 TV = Result.getLimitedValue(32); 249 if ((TV > 31) || (mask & (1 << TV)) == 0) 250 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 251 << TheCall->getArg(ArgNo)->getSourceRange(); 252 } 253 254 // For NEON intrinsics which take an immediate value as part of the 255 // instruction, range check them here. 256 unsigned i = 0, l = 0, u = 0; 257 switch (BuiltinID) { 258 default: return false; 259 case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; 260 case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; 261 case ARM::BI__builtin_arm_vcvtr_f: 262 case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; 263#define GET_NEON_IMMEDIATE_CHECK 264#include "clang/Basic/arm_neon.inc" 265#undef GET_NEON_IMMEDIATE_CHECK 266 }; 267 268 // Check that the immediate argument is actually a constant. 269 if (SemaBuiltinConstantArg(TheCall, i, Result)) 270 return true; 271 272 // Range check against the upper/lower values for this isntruction. 273 unsigned Val = Result.getZExtValue(); 274 if (Val < l || Val > (u + l)) 275 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 276 << l << u+l << TheCall->getArg(i)->getSourceRange(); 277 278 // FIXME: VFP Intrinsics should error if VFP not present. 279 return false; 280} 281 282/// CheckFunctionCall - Check a direct function call for various correctness 283/// and safety properties not strictly enforced by the C type system. 284bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 285 // Get the IdentifierInfo* for the called function. 286 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 287 288 // None of the checks below are needed for functions that don't have 289 // simple names (e.g., C++ conversion functions). 290 if (!FnInfo) 291 return false; 292 293 // FIXME: This mechanism should be abstracted to be less fragile and 294 // more efficient. For example, just map function ids to custom 295 // handlers. 296 297 // Printf and scanf checking. 298 for (specific_attr_iterator<FormatAttr> 299 i = FDecl->specific_attr_begin<FormatAttr>(), 300 e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { 301 302 const FormatAttr *Format = *i; 303 const bool b = Format->getType() == "scanf"; 304 if (b || CheckablePrintfAttr(Format, TheCall)) { 305 bool HasVAListArg = Format->getFirstArg() == 0; 306 CheckPrintfScanfArguments(TheCall, HasVAListArg, 307 Format->getFormatIdx() - 1, 308 HasVAListArg ? 0 : Format->getFirstArg() - 1, 309 !b); 310 } 311 } 312 313 for (specific_attr_iterator<NonNullAttr> 314 i = FDecl->specific_attr_begin<NonNullAttr>(), 315 e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) { 316 CheckNonNullArguments(*i, TheCall); 317 } 318 319 return false; 320} 321 322bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 323 // Printf checking. 324 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 325 if (!Format) 326 return false; 327 328 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 329 if (!V) 330 return false; 331 332 QualType Ty = V->getType(); 333 if (!Ty->isBlockPointerType()) 334 return false; 335 336 const bool b = Format->getType() == "scanf"; 337 if (!b && !CheckablePrintfAttr(Format, TheCall)) 338 return false; 339 340 bool HasVAListArg = Format->getFirstArg() == 0; 341 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 342 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 343 344 return false; 345} 346 347/// SemaBuiltinAtomicOverloaded - We have a call to a function like 348/// __sync_fetch_and_add, which is an overloaded function based on the pointer 349/// type of its first argument. The main ActOnCallExpr routines have already 350/// promoted the types of arguments because all of these calls are prototyped as 351/// void(...). 352/// 353/// This function goes through and does final semantic checking for these 354/// builtins, 355ExprResult 356Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { 357 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 358 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 359 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 360 361 // Ensure that we have at least one argument to do type inference from. 362 if (TheCall->getNumArgs() < 1) { 363 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 364 << 0 << 1 << TheCall->getNumArgs() 365 << TheCall->getCallee()->getSourceRange(); 366 return ExprError(); 367 } 368 369 // Inspect the first argument of the atomic builtin. This should always be 370 // a pointer type, whose element is an integral scalar or pointer type. 371 // Because it is a pointer type, we don't have to worry about any implicit 372 // casts here. 373 // FIXME: We don't allow floating point scalars as input. 374 Expr *FirstArg = TheCall->getArg(0); 375 if (!FirstArg->getType()->isPointerType()) { 376 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 377 << FirstArg->getType() << FirstArg->getSourceRange(); 378 return ExprError(); 379 } 380 381 QualType ValType = 382 FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 383 if (!ValType->isIntegerType() && !ValType->isAnyPointerType() && 384 !ValType->isBlockPointerType()) { 385 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 386 << FirstArg->getType() << FirstArg->getSourceRange(); 387 return ExprError(); 388 } 389 390 // The majority of builtins return a value, but a few have special return 391 // types, so allow them to override appropriately below. 392 QualType ResultType = ValType; 393 394 // We need to figure out which concrete builtin this maps onto. For example, 395 // __sync_fetch_and_add with a 2 byte object turns into 396 // __sync_fetch_and_add_2. 397#define BUILTIN_ROW(x) \ 398 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 399 Builtin::BI##x##_8, Builtin::BI##x##_16 } 400 401 static const unsigned BuiltinIndices[][5] = { 402 BUILTIN_ROW(__sync_fetch_and_add), 403 BUILTIN_ROW(__sync_fetch_and_sub), 404 BUILTIN_ROW(__sync_fetch_and_or), 405 BUILTIN_ROW(__sync_fetch_and_and), 406 BUILTIN_ROW(__sync_fetch_and_xor), 407 408 BUILTIN_ROW(__sync_add_and_fetch), 409 BUILTIN_ROW(__sync_sub_and_fetch), 410 BUILTIN_ROW(__sync_and_and_fetch), 411 BUILTIN_ROW(__sync_or_and_fetch), 412 BUILTIN_ROW(__sync_xor_and_fetch), 413 414 BUILTIN_ROW(__sync_val_compare_and_swap), 415 BUILTIN_ROW(__sync_bool_compare_and_swap), 416 BUILTIN_ROW(__sync_lock_test_and_set), 417 BUILTIN_ROW(__sync_lock_release) 418 }; 419#undef BUILTIN_ROW 420 421 // Determine the index of the size. 422 unsigned SizeIndex; 423 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 424 case 1: SizeIndex = 0; break; 425 case 2: SizeIndex = 1; break; 426 case 4: SizeIndex = 2; break; 427 case 8: SizeIndex = 3; break; 428 case 16: SizeIndex = 4; break; 429 default: 430 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 431 << FirstArg->getType() << FirstArg->getSourceRange(); 432 return ExprError(); 433 } 434 435 // Each of these builtins has one pointer argument, followed by some number of 436 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 437 // that we ignore. Find out which row of BuiltinIndices to read from as well 438 // as the number of fixed args. 439 unsigned BuiltinID = FDecl->getBuiltinID(); 440 unsigned BuiltinIndex, NumFixed = 1; 441 switch (BuiltinID) { 442 default: assert(0 && "Unknown overloaded atomic builtin!"); 443 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 444 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 445 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 446 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 447 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 448 449 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 450 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 451 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 452 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 453 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 454 455 case Builtin::BI__sync_val_compare_and_swap: 456 BuiltinIndex = 10; 457 NumFixed = 2; 458 break; 459 case Builtin::BI__sync_bool_compare_and_swap: 460 BuiltinIndex = 11; 461 NumFixed = 2; 462 ResultType = Context.BoolTy; 463 break; 464 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 465 case Builtin::BI__sync_lock_release: 466 BuiltinIndex = 13; 467 NumFixed = 0; 468 ResultType = Context.VoidTy; 469 break; 470 } 471 472 // Now that we know how many fixed arguments we expect, first check that we 473 // have at least that many. 474 if (TheCall->getNumArgs() < 1+NumFixed) { 475 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 476 << 0 << 1+NumFixed << TheCall->getNumArgs() 477 << TheCall->getCallee()->getSourceRange(); 478 return ExprError(); 479 } 480 481 // Get the decl for the concrete builtin from this, we can tell what the 482 // concrete integer type we should convert to is. 483 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 484 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 485 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 486 FunctionDecl *NewBuiltinDecl = 487 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 488 TUScope, false, DRE->getLocStart())); 489 490 // The first argument --- the pointer --- has a fixed type; we 491 // deduce the types of the rest of the arguments accordingly. Walk 492 // the remaining arguments, converting them to the deduced value type. 493 for (unsigned i = 0; i != NumFixed; ++i) { 494 Expr *Arg = TheCall->getArg(i+1); 495 496 // If the argument is an implicit cast, then there was a promotion due to 497 // "...", just remove it now. 498 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 499 Arg = ICE->getSubExpr(); 500 ICE->setSubExpr(0); 501 TheCall->setArg(i+1, Arg); 502 } 503 504 // GCC does an implicit conversion to the pointer or integer ValType. This 505 // can fail in some cases (1i -> int**), check for this error case now. 506 CastKind Kind = CK_Invalid; 507 ExprValueKind VK = VK_RValue; 508 CXXCastPath BasePath; 509 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, VK, BasePath)) 510 return ExprError(); 511 512 // Okay, we have something that *can* be converted to the right type. Check 513 // to see if there is a potentially weird extension going on here. This can 514 // happen when you do an atomic operation on something like an char* and 515 // pass in 42. The 42 gets converted to char. This is even more strange 516 // for things like 45.123 -> char, etc. 517 // FIXME: Do this check. 518 ImpCastExprToType(Arg, ValType, Kind, VK, &BasePath); 519 TheCall->setArg(i+1, Arg); 520 } 521 522 // Switch the DeclRefExpr to refer to the new decl. 523 DRE->setDecl(NewBuiltinDecl); 524 DRE->setType(NewBuiltinDecl->getType()); 525 526 // Set the callee in the CallExpr. 527 // FIXME: This leaks the original parens and implicit casts. 528 Expr *PromotedCall = DRE; 529 UsualUnaryConversions(PromotedCall); 530 TheCall->setCallee(PromotedCall); 531 532 // Change the result type of the call to match the original value type. This 533 // is arbitrary, but the codegen for these builtins ins design to handle it 534 // gracefully. 535 TheCall->setType(ResultType); 536 537 return move(TheCallResult); 538} 539 540 541/// CheckObjCString - Checks that the argument to the builtin 542/// CFString constructor is correct 543/// Note: It might also make sense to do the UTF-16 conversion here (would 544/// simplify the backend). 545bool Sema::CheckObjCString(Expr *Arg) { 546 Arg = Arg->IgnoreParenCasts(); 547 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 548 549 if (!Literal || Literal->isWide()) { 550 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 551 << Arg->getSourceRange(); 552 return true; 553 } 554 555 size_t NulPos = Literal->getString().find('\0'); 556 if (NulPos != llvm::StringRef::npos) { 557 Diag(getLocationOfStringLiteralByte(Literal, NulPos), 558 diag::warn_cfstring_literal_contains_nul_character) 559 << Arg->getSourceRange(); 560 } 561 if (Literal->containsNonAsciiOrNull()) { 562 llvm::StringRef String = Literal->getString(); 563 unsigned NumBytes = String.size(); 564 llvm::SmallVector<UTF16, 128> ToBuf(NumBytes); 565 const UTF8 *FromPtr = (UTF8 *)String.data(); 566 UTF16 *ToPtr = &ToBuf[0]; 567 568 ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, 569 &ToPtr, ToPtr + NumBytes, 570 strictConversion); 571 // Check for conversion failure. 572 if (Result != conversionOK) 573 Diag(Arg->getLocStart(), 574 diag::warn_cfstring_truncated) << Arg->getSourceRange(); 575 } 576 return false; 577} 578 579/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 580/// Emit an error and return true on failure, return false on success. 581bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 582 Expr *Fn = TheCall->getCallee(); 583 if (TheCall->getNumArgs() > 2) { 584 Diag(TheCall->getArg(2)->getLocStart(), 585 diag::err_typecheck_call_too_many_args) 586 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 587 << Fn->getSourceRange() 588 << SourceRange(TheCall->getArg(2)->getLocStart(), 589 (*(TheCall->arg_end()-1))->getLocEnd()); 590 return true; 591 } 592 593 if (TheCall->getNumArgs() < 2) { 594 return Diag(TheCall->getLocEnd(), 595 diag::err_typecheck_call_too_few_args_at_least) 596 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 597 } 598 599 // Determine whether the current function is variadic or not. 600 BlockScopeInfo *CurBlock = getCurBlock(); 601 bool isVariadic; 602 if (CurBlock) 603 isVariadic = CurBlock->TheDecl->isVariadic(); 604 else if (FunctionDecl *FD = getCurFunctionDecl()) 605 isVariadic = FD->isVariadic(); 606 else 607 isVariadic = getCurMethodDecl()->isVariadic(); 608 609 if (!isVariadic) { 610 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 611 return true; 612 } 613 614 // Verify that the second argument to the builtin is the last argument of the 615 // current function or method. 616 bool SecondArgIsLastNamedArgument = false; 617 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 618 619 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 620 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 621 // FIXME: This isn't correct for methods (results in bogus warning). 622 // Get the last formal in the current function. 623 const ParmVarDecl *LastArg; 624 if (CurBlock) 625 LastArg = *(CurBlock->TheDecl->param_end()-1); 626 else if (FunctionDecl *FD = getCurFunctionDecl()) 627 LastArg = *(FD->param_end()-1); 628 else 629 LastArg = *(getCurMethodDecl()->param_end()-1); 630 SecondArgIsLastNamedArgument = PV == LastArg; 631 } 632 } 633 634 if (!SecondArgIsLastNamedArgument) 635 Diag(TheCall->getArg(1)->getLocStart(), 636 diag::warn_second_parameter_of_va_start_not_last_named_argument); 637 return false; 638} 639 640/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 641/// friends. This is declared to take (...), so we have to check everything. 642bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 643 if (TheCall->getNumArgs() < 2) 644 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 645 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 646 if (TheCall->getNumArgs() > 2) 647 return Diag(TheCall->getArg(2)->getLocStart(), 648 diag::err_typecheck_call_too_many_args) 649 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 650 << SourceRange(TheCall->getArg(2)->getLocStart(), 651 (*(TheCall->arg_end()-1))->getLocEnd()); 652 653 Expr *OrigArg0 = TheCall->getArg(0); 654 Expr *OrigArg1 = TheCall->getArg(1); 655 656 // Do standard promotions between the two arguments, returning their common 657 // type. 658 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 659 660 // Make sure any conversions are pushed back into the call; this is 661 // type safe since unordered compare builtins are declared as "_Bool 662 // foo(...)". 663 TheCall->setArg(0, OrigArg0); 664 TheCall->setArg(1, OrigArg1); 665 666 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 667 return false; 668 669 // If the common type isn't a real floating type, then the arguments were 670 // invalid for this operation. 671 if (!Res->isRealFloatingType()) 672 return Diag(OrigArg0->getLocStart(), 673 diag::err_typecheck_call_invalid_ordered_compare) 674 << OrigArg0->getType() << OrigArg1->getType() 675 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 676 677 return false; 678} 679 680/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 681/// __builtin_isnan and friends. This is declared to take (...), so we have 682/// to check everything. We expect the last argument to be a floating point 683/// value. 684bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 685 if (TheCall->getNumArgs() < NumArgs) 686 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 687 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 688 if (TheCall->getNumArgs() > NumArgs) 689 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 690 diag::err_typecheck_call_too_many_args) 691 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 692 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 693 (*(TheCall->arg_end()-1))->getLocEnd()); 694 695 Expr *OrigArg = TheCall->getArg(NumArgs-1); 696 697 if (OrigArg->isTypeDependent()) 698 return false; 699 700 // This operation requires a non-_Complex floating-point number. 701 if (!OrigArg->getType()->isRealFloatingType()) 702 return Diag(OrigArg->getLocStart(), 703 diag::err_typecheck_call_invalid_unary_fp) 704 << OrigArg->getType() << OrigArg->getSourceRange(); 705 706 // If this is an implicit conversion from float -> double, remove it. 707 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 708 Expr *CastArg = Cast->getSubExpr(); 709 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 710 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 711 "promotion from float to double is the only expected cast here"); 712 Cast->setSubExpr(0); 713 TheCall->setArg(NumArgs-1, CastArg); 714 OrigArg = CastArg; 715 } 716 } 717 718 return false; 719} 720 721/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 722// This is declared to take (...), so we have to check everything. 723ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 724 if (TheCall->getNumArgs() < 2) 725 return ExprError(Diag(TheCall->getLocEnd(), 726 diag::err_typecheck_call_too_few_args_at_least) 727 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 728 << TheCall->getSourceRange()); 729 730 // Determine which of the following types of shufflevector we're checking: 731 // 1) unary, vector mask: (lhs, mask) 732 // 2) binary, vector mask: (lhs, rhs, mask) 733 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 734 QualType resType = TheCall->getArg(0)->getType(); 735 unsigned numElements = 0; 736 737 if (!TheCall->getArg(0)->isTypeDependent() && 738 !TheCall->getArg(1)->isTypeDependent()) { 739 QualType LHSType = TheCall->getArg(0)->getType(); 740 QualType RHSType = TheCall->getArg(1)->getType(); 741 742 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 743 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 744 << SourceRange(TheCall->getArg(0)->getLocStart(), 745 TheCall->getArg(1)->getLocEnd()); 746 return ExprError(); 747 } 748 749 numElements = LHSType->getAs<VectorType>()->getNumElements(); 750 unsigned numResElements = TheCall->getNumArgs() - 2; 751 752 // Check to see if we have a call with 2 vector arguments, the unary shuffle 753 // with mask. If so, verify that RHS is an integer vector type with the 754 // same number of elts as lhs. 755 if (TheCall->getNumArgs() == 2) { 756 if (!RHSType->hasIntegerRepresentation() || 757 RHSType->getAs<VectorType>()->getNumElements() != numElements) 758 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 759 << SourceRange(TheCall->getArg(1)->getLocStart(), 760 TheCall->getArg(1)->getLocEnd()); 761 numResElements = numElements; 762 } 763 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 764 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 765 << SourceRange(TheCall->getArg(0)->getLocStart(), 766 TheCall->getArg(1)->getLocEnd()); 767 return ExprError(); 768 } else if (numElements != numResElements) { 769 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 770 resType = Context.getVectorType(eltType, numResElements, 771 VectorType::GenericVector); 772 } 773 } 774 775 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 776 if (TheCall->getArg(i)->isTypeDependent() || 777 TheCall->getArg(i)->isValueDependent()) 778 continue; 779 780 llvm::APSInt Result(32); 781 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 782 return ExprError(Diag(TheCall->getLocStart(), 783 diag::err_shufflevector_nonconstant_argument) 784 << TheCall->getArg(i)->getSourceRange()); 785 786 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 787 return ExprError(Diag(TheCall->getLocStart(), 788 diag::err_shufflevector_argument_too_large) 789 << TheCall->getArg(i)->getSourceRange()); 790 } 791 792 llvm::SmallVector<Expr*, 32> exprs; 793 794 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 795 exprs.push_back(TheCall->getArg(i)); 796 TheCall->setArg(i, 0); 797 } 798 799 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 800 exprs.size(), resType, 801 TheCall->getCallee()->getLocStart(), 802 TheCall->getRParenLoc())); 803} 804 805/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 806// This is declared to take (const void*, ...) and can take two 807// optional constant int args. 808bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 809 unsigned NumArgs = TheCall->getNumArgs(); 810 811 if (NumArgs > 3) 812 return Diag(TheCall->getLocEnd(), 813 diag::err_typecheck_call_too_many_args_at_most) 814 << 0 /*function call*/ << 3 << NumArgs 815 << TheCall->getSourceRange(); 816 817 // Argument 0 is checked for us and the remaining arguments must be 818 // constant integers. 819 for (unsigned i = 1; i != NumArgs; ++i) { 820 Expr *Arg = TheCall->getArg(i); 821 822 llvm::APSInt Result; 823 if (SemaBuiltinConstantArg(TheCall, i, Result)) 824 return true; 825 826 // FIXME: gcc issues a warning and rewrites these to 0. These 827 // seems especially odd for the third argument since the default 828 // is 3. 829 if (i == 1) { 830 if (Result.getLimitedValue() > 1) 831 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 832 << "0" << "1" << Arg->getSourceRange(); 833 } else { 834 if (Result.getLimitedValue() > 3) 835 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 836 << "0" << "3" << Arg->getSourceRange(); 837 } 838 } 839 840 return false; 841} 842 843/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 844/// TheCall is a constant expression. 845bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 846 llvm::APSInt &Result) { 847 Expr *Arg = TheCall->getArg(ArgNum); 848 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 849 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 850 851 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 852 853 if (!Arg->isIntegerConstantExpr(Result, Context)) 854 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 855 << FDecl->getDeclName() << Arg->getSourceRange(); 856 857 return false; 858} 859 860/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 861/// int type). This simply type checks that type is one of the defined 862/// constants (0-3). 863// For compatability check 0-3, llvm only handles 0 and 2. 864bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 865 llvm::APSInt Result; 866 867 // Check constant-ness first. 868 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 869 return true; 870 871 Expr *Arg = TheCall->getArg(1); 872 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 873 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 874 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 875 } 876 877 return false; 878} 879 880/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 881/// This checks that val is a constant 1. 882bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 883 Expr *Arg = TheCall->getArg(1); 884 llvm::APSInt Result; 885 886 // TODO: This is less than ideal. Overload this to take a value. 887 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 888 return true; 889 890 if (Result != 1) 891 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 892 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 893 894 return false; 895} 896 897// Handle i > 1 ? "x" : "y", recursively. 898bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 899 bool HasVAListArg, 900 unsigned format_idx, unsigned firstDataArg, 901 bool isPrintf) { 902 tryAgain: 903 if (E->isTypeDependent() || E->isValueDependent()) 904 return false; 905 906 switch (E->getStmtClass()) { 907 case Stmt::BinaryConditionalOperatorClass: 908 case Stmt::ConditionalOperatorClass: { 909 const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); 910 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 911 format_idx, firstDataArg, isPrintf) 912 && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg, 913 format_idx, firstDataArg, isPrintf); 914 } 915 916 case Stmt::IntegerLiteralClass: 917 // Technically -Wformat-nonliteral does not warn about this case. 918 // The behavior of printf and friends in this case is implementation 919 // dependent. Ideally if the format string cannot be null then 920 // it should have a 'nonnull' attribute in the function prototype. 921 return true; 922 923 case Stmt::ImplicitCastExprClass: { 924 E = cast<ImplicitCastExpr>(E)->getSubExpr(); 925 goto tryAgain; 926 } 927 928 case Stmt::ParenExprClass: { 929 E = cast<ParenExpr>(E)->getSubExpr(); 930 goto tryAgain; 931 } 932 933 case Stmt::OpaqueValueExprClass: 934 if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { 935 E = src; 936 goto tryAgain; 937 } 938 return false; 939 940 case Stmt::PredefinedExprClass: 941 // While __func__, etc., are technically not string literals, they 942 // cannot contain format specifiers and thus are not a security 943 // liability. 944 return true; 945 946 case Stmt::DeclRefExprClass: { 947 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 948 949 // As an exception, do not flag errors for variables binding to 950 // const string literals. 951 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 952 bool isConstant = false; 953 QualType T = DR->getType(); 954 955 if (const ArrayType *AT = Context.getAsArrayType(T)) { 956 isConstant = AT->getElementType().isConstant(Context); 957 } else if (const PointerType *PT = T->getAs<PointerType>()) { 958 isConstant = T.isConstant(Context) && 959 PT->getPointeeType().isConstant(Context); 960 } 961 962 if (isConstant) { 963 if (const Expr *Init = VD->getAnyInitializer()) 964 return SemaCheckStringLiteral(Init, TheCall, 965 HasVAListArg, format_idx, firstDataArg, 966 isPrintf); 967 } 968 969 // For vprintf* functions (i.e., HasVAListArg==true), we add a 970 // special check to see if the format string is a function parameter 971 // of the function calling the printf function. If the function 972 // has an attribute indicating it is a printf-like function, then we 973 // should suppress warnings concerning non-literals being used in a call 974 // to a vprintf function. For example: 975 // 976 // void 977 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 978 // va_list ap; 979 // va_start(ap, fmt); 980 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 981 // ... 982 // 983 // 984 // FIXME: We don't have full attribute support yet, so just check to see 985 // if the argument is a DeclRefExpr that references a parameter. We'll 986 // add proper support for checking the attribute later. 987 if (HasVAListArg) 988 if (isa<ParmVarDecl>(VD)) 989 return true; 990 } 991 992 return false; 993 } 994 995 case Stmt::CallExprClass: { 996 const CallExpr *CE = cast<CallExpr>(E); 997 if (const ImplicitCastExpr *ICE 998 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 999 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1000 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1001 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1002 unsigned ArgIndex = FA->getFormatIdx(); 1003 const Expr *Arg = CE->getArg(ArgIndex - 1); 1004 1005 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1006 format_idx, firstDataArg, isPrintf); 1007 } 1008 } 1009 } 1010 } 1011 1012 return false; 1013 } 1014 case Stmt::ObjCStringLiteralClass: 1015 case Stmt::StringLiteralClass: { 1016 const StringLiteral *StrE = NULL; 1017 1018 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1019 StrE = ObjCFExpr->getString(); 1020 else 1021 StrE = cast<StringLiteral>(E); 1022 1023 if (StrE) { 1024 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1025 firstDataArg, isPrintf); 1026 return true; 1027 } 1028 1029 return false; 1030 } 1031 1032 default: 1033 return false; 1034 } 1035} 1036 1037void 1038Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1039 const CallExpr *TheCall) { 1040 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1041 e = NonNull->args_end(); 1042 i != e; ++i) { 1043 const Expr *ArgExpr = TheCall->getArg(*i); 1044 if (ArgExpr->isNullPointerConstant(Context, 1045 Expr::NPC_ValueDependentIsNotNull)) 1046 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1047 << ArgExpr->getSourceRange(); 1048 } 1049} 1050 1051/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1052/// functions) for correct use of format strings. 1053void 1054Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1055 unsigned format_idx, unsigned firstDataArg, 1056 bool isPrintf) { 1057 1058 const Expr *Fn = TheCall->getCallee(); 1059 1060 // The way the format attribute works in GCC, the implicit this argument 1061 // of member functions is counted. However, it doesn't appear in our own 1062 // lists, so decrement format_idx in that case. 1063 if (isa<CXXMemberCallExpr>(TheCall)) { 1064 const CXXMethodDecl *method_decl = 1065 dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl()); 1066 if (method_decl && method_decl->isInstance()) { 1067 // Catch a format attribute mistakenly referring to the object argument. 1068 if (format_idx == 0) 1069 return; 1070 --format_idx; 1071 if(firstDataArg != 0) 1072 --firstDataArg; 1073 } 1074 } 1075 1076 // CHECK: printf/scanf-like function is called with no format string. 1077 if (format_idx >= TheCall->getNumArgs()) { 1078 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1079 << Fn->getSourceRange(); 1080 return; 1081 } 1082 1083 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1084 1085 // CHECK: format string is not a string literal. 1086 // 1087 // Dynamically generated format strings are difficult to 1088 // automatically vet at compile time. Requiring that format strings 1089 // are string literals: (1) permits the checking of format strings by 1090 // the compiler and thereby (2) can practically remove the source of 1091 // many format string exploits. 1092 1093 // Format string can be either ObjC string (e.g. @"%d") or 1094 // C string (e.g. "%d") 1095 // ObjC string uses the same format specifiers as C string, so we can use 1096 // the same format string checking logic for both ObjC and C strings. 1097 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1098 firstDataArg, isPrintf)) 1099 return; // Literal format string found, check done! 1100 1101 // If there are no arguments specified, warn with -Wformat-security, otherwise 1102 // warn only with -Wformat-nonliteral. 1103 if (TheCall->getNumArgs() == format_idx+1) 1104 Diag(TheCall->getArg(format_idx)->getLocStart(), 1105 diag::warn_format_nonliteral_noargs) 1106 << OrigFormatExpr->getSourceRange(); 1107 else 1108 Diag(TheCall->getArg(format_idx)->getLocStart(), 1109 diag::warn_format_nonliteral) 1110 << OrigFormatExpr->getSourceRange(); 1111} 1112 1113namespace { 1114class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1115protected: 1116 Sema &S; 1117 const StringLiteral *FExpr; 1118 const Expr *OrigFormatExpr; 1119 const unsigned FirstDataArg; 1120 const unsigned NumDataArgs; 1121 const bool IsObjCLiteral; 1122 const char *Beg; // Start of format string. 1123 const bool HasVAListArg; 1124 const CallExpr *TheCall; 1125 unsigned FormatIdx; 1126 llvm::BitVector CoveredArgs; 1127 bool usesPositionalArgs; 1128 bool atFirstArg; 1129public: 1130 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1131 const Expr *origFormatExpr, unsigned firstDataArg, 1132 unsigned numDataArgs, bool isObjCLiteral, 1133 const char *beg, bool hasVAListArg, 1134 const CallExpr *theCall, unsigned formatIdx) 1135 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1136 FirstDataArg(firstDataArg), 1137 NumDataArgs(numDataArgs), 1138 IsObjCLiteral(isObjCLiteral), Beg(beg), 1139 HasVAListArg(hasVAListArg), 1140 TheCall(theCall), FormatIdx(formatIdx), 1141 usesPositionalArgs(false), atFirstArg(true) { 1142 CoveredArgs.resize(numDataArgs); 1143 CoveredArgs.reset(); 1144 } 1145 1146 void DoneProcessing(); 1147 1148 void HandleIncompleteSpecifier(const char *startSpecifier, 1149 unsigned specifierLen); 1150 1151 virtual void HandleInvalidPosition(const char *startSpecifier, 1152 unsigned specifierLen, 1153 analyze_format_string::PositionContext p); 1154 1155 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1156 1157 void HandleNullChar(const char *nullCharacter); 1158 1159protected: 1160 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1161 const char *startSpec, 1162 unsigned specifierLen, 1163 const char *csStart, unsigned csLen); 1164 1165 SourceRange getFormatStringRange(); 1166 CharSourceRange getSpecifierRange(const char *startSpecifier, 1167 unsigned specifierLen); 1168 SourceLocation getLocationOfByte(const char *x); 1169 1170 const Expr *getDataArg(unsigned i) const; 1171 1172 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1173 const analyze_format_string::ConversionSpecifier &CS, 1174 const char *startSpecifier, unsigned specifierLen, 1175 unsigned argIndex); 1176}; 1177} 1178 1179SourceRange CheckFormatHandler::getFormatStringRange() { 1180 return OrigFormatExpr->getSourceRange(); 1181} 1182 1183CharSourceRange CheckFormatHandler:: 1184getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1185 SourceLocation Start = getLocationOfByte(startSpecifier); 1186 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1187 1188 // Advance the end SourceLocation by one due to half-open ranges. 1189 End = End.getFileLocWithOffset(1); 1190 1191 return CharSourceRange::getCharRange(Start, End); 1192} 1193 1194SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1195 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1196} 1197 1198void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1199 unsigned specifierLen){ 1200 SourceLocation Loc = getLocationOfByte(startSpecifier); 1201 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1202 << getSpecifierRange(startSpecifier, specifierLen); 1203} 1204 1205void 1206CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1207 analyze_format_string::PositionContext p) { 1208 SourceLocation Loc = getLocationOfByte(startPos); 1209 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1210 << (unsigned) p << getSpecifierRange(startPos, posLen); 1211} 1212 1213void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1214 unsigned posLen) { 1215 SourceLocation Loc = getLocationOfByte(startPos); 1216 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1217 << getSpecifierRange(startPos, posLen); 1218} 1219 1220void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1221 // The presence of a null character is likely an error. 1222 S.Diag(getLocationOfByte(nullCharacter), 1223 diag::warn_printf_format_string_contains_null_char) 1224 << getFormatStringRange(); 1225} 1226 1227const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1228 return TheCall->getArg(FirstDataArg + i); 1229} 1230 1231void CheckFormatHandler::DoneProcessing() { 1232 // Does the number of data arguments exceed the number of 1233 // format conversions in the format string? 1234 if (!HasVAListArg) { 1235 // Find any arguments that weren't covered. 1236 CoveredArgs.flip(); 1237 signed notCoveredArg = CoveredArgs.find_first(); 1238 if (notCoveredArg >= 0) { 1239 assert((unsigned)notCoveredArg < NumDataArgs); 1240 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1241 diag::warn_printf_data_arg_not_used) 1242 << getFormatStringRange(); 1243 } 1244 } 1245} 1246 1247bool 1248CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1249 SourceLocation Loc, 1250 const char *startSpec, 1251 unsigned specifierLen, 1252 const char *csStart, 1253 unsigned csLen) { 1254 1255 bool keepGoing = true; 1256 if (argIndex < NumDataArgs) { 1257 // Consider the argument coverered, even though the specifier doesn't 1258 // make sense. 1259 CoveredArgs.set(argIndex); 1260 } 1261 else { 1262 // If argIndex exceeds the number of data arguments we 1263 // don't issue a warning because that is just a cascade of warnings (and 1264 // they may have intended '%%' anyway). We don't want to continue processing 1265 // the format string after this point, however, as we will like just get 1266 // gibberish when trying to match arguments. 1267 keepGoing = false; 1268 } 1269 1270 S.Diag(Loc, diag::warn_format_invalid_conversion) 1271 << llvm::StringRef(csStart, csLen) 1272 << getSpecifierRange(startSpec, specifierLen); 1273 1274 return keepGoing; 1275} 1276 1277bool 1278CheckFormatHandler::CheckNumArgs( 1279 const analyze_format_string::FormatSpecifier &FS, 1280 const analyze_format_string::ConversionSpecifier &CS, 1281 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1282 1283 if (argIndex >= NumDataArgs) { 1284 if (FS.usesPositionalArg()) { 1285 S.Diag(getLocationOfByte(CS.getStart()), 1286 diag::warn_printf_positional_arg_exceeds_data_args) 1287 << (argIndex+1) << NumDataArgs 1288 << getSpecifierRange(startSpecifier, specifierLen); 1289 } 1290 else { 1291 S.Diag(getLocationOfByte(CS.getStart()), 1292 diag::warn_printf_insufficient_data_args) 1293 << getSpecifierRange(startSpecifier, specifierLen); 1294 } 1295 1296 return false; 1297 } 1298 return true; 1299} 1300 1301//===--- CHECK: Printf format string checking ------------------------------===// 1302 1303namespace { 1304class CheckPrintfHandler : public CheckFormatHandler { 1305public: 1306 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1307 const Expr *origFormatExpr, unsigned firstDataArg, 1308 unsigned numDataArgs, bool isObjCLiteral, 1309 const char *beg, bool hasVAListArg, 1310 const CallExpr *theCall, unsigned formatIdx) 1311 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1312 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1313 theCall, formatIdx) {} 1314 1315 1316 bool HandleInvalidPrintfConversionSpecifier( 1317 const analyze_printf::PrintfSpecifier &FS, 1318 const char *startSpecifier, 1319 unsigned specifierLen); 1320 1321 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1322 const char *startSpecifier, 1323 unsigned specifierLen); 1324 1325 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1326 const char *startSpecifier, unsigned specifierLen); 1327 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1328 const analyze_printf::OptionalAmount &Amt, 1329 unsigned type, 1330 const char *startSpecifier, unsigned specifierLen); 1331 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1332 const analyze_printf::OptionalFlag &flag, 1333 const char *startSpecifier, unsigned specifierLen); 1334 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1335 const analyze_printf::OptionalFlag &ignoredFlag, 1336 const analyze_printf::OptionalFlag &flag, 1337 const char *startSpecifier, unsigned specifierLen); 1338}; 1339} 1340 1341bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1342 const analyze_printf::PrintfSpecifier &FS, 1343 const char *startSpecifier, 1344 unsigned specifierLen) { 1345 const analyze_printf::PrintfConversionSpecifier &CS = 1346 FS.getConversionSpecifier(); 1347 1348 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1349 getLocationOfByte(CS.getStart()), 1350 startSpecifier, specifierLen, 1351 CS.getStart(), CS.getLength()); 1352} 1353 1354bool CheckPrintfHandler::HandleAmount( 1355 const analyze_format_string::OptionalAmount &Amt, 1356 unsigned k, const char *startSpecifier, 1357 unsigned specifierLen) { 1358 1359 if (Amt.hasDataArgument()) { 1360 if (!HasVAListArg) { 1361 unsigned argIndex = Amt.getArgIndex(); 1362 if (argIndex >= NumDataArgs) { 1363 S.Diag(getLocationOfByte(Amt.getStart()), 1364 diag::warn_printf_asterisk_missing_arg) 1365 << k << getSpecifierRange(startSpecifier, specifierLen); 1366 // Don't do any more checking. We will just emit 1367 // spurious errors. 1368 return false; 1369 } 1370 1371 // Type check the data argument. It should be an 'int'. 1372 // Although not in conformance with C99, we also allow the argument to be 1373 // an 'unsigned int' as that is a reasonably safe case. GCC also 1374 // doesn't emit a warning for that case. 1375 CoveredArgs.set(argIndex); 1376 const Expr *Arg = getDataArg(argIndex); 1377 QualType T = Arg->getType(); 1378 1379 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1380 assert(ATR.isValid()); 1381 1382 if (!ATR.matchesType(S.Context, T)) { 1383 S.Diag(getLocationOfByte(Amt.getStart()), 1384 diag::warn_printf_asterisk_wrong_type) 1385 << k 1386 << ATR.getRepresentativeType(S.Context) << T 1387 << getSpecifierRange(startSpecifier, specifierLen) 1388 << Arg->getSourceRange(); 1389 // Don't do any more checking. We will just emit 1390 // spurious errors. 1391 return false; 1392 } 1393 } 1394 } 1395 return true; 1396} 1397 1398void CheckPrintfHandler::HandleInvalidAmount( 1399 const analyze_printf::PrintfSpecifier &FS, 1400 const analyze_printf::OptionalAmount &Amt, 1401 unsigned type, 1402 const char *startSpecifier, 1403 unsigned specifierLen) { 1404 const analyze_printf::PrintfConversionSpecifier &CS = 1405 FS.getConversionSpecifier(); 1406 switch (Amt.getHowSpecified()) { 1407 case analyze_printf::OptionalAmount::Constant: 1408 S.Diag(getLocationOfByte(Amt.getStart()), 1409 diag::warn_printf_nonsensical_optional_amount) 1410 << type 1411 << CS.toString() 1412 << getSpecifierRange(startSpecifier, specifierLen) 1413 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1414 Amt.getConstantLength())); 1415 break; 1416 1417 default: 1418 S.Diag(getLocationOfByte(Amt.getStart()), 1419 diag::warn_printf_nonsensical_optional_amount) 1420 << type 1421 << CS.toString() 1422 << getSpecifierRange(startSpecifier, specifierLen); 1423 break; 1424 } 1425} 1426 1427void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1428 const analyze_printf::OptionalFlag &flag, 1429 const char *startSpecifier, 1430 unsigned specifierLen) { 1431 // Warn about pointless flag with a fixit removal. 1432 const analyze_printf::PrintfConversionSpecifier &CS = 1433 FS.getConversionSpecifier(); 1434 S.Diag(getLocationOfByte(flag.getPosition()), 1435 diag::warn_printf_nonsensical_flag) 1436 << flag.toString() << CS.toString() 1437 << getSpecifierRange(startSpecifier, specifierLen) 1438 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1439} 1440 1441void CheckPrintfHandler::HandleIgnoredFlag( 1442 const analyze_printf::PrintfSpecifier &FS, 1443 const analyze_printf::OptionalFlag &ignoredFlag, 1444 const analyze_printf::OptionalFlag &flag, 1445 const char *startSpecifier, 1446 unsigned specifierLen) { 1447 // Warn about ignored flag with a fixit removal. 1448 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1449 diag::warn_printf_ignored_flag) 1450 << ignoredFlag.toString() << flag.toString() 1451 << getSpecifierRange(startSpecifier, specifierLen) 1452 << FixItHint::CreateRemoval(getSpecifierRange( 1453 ignoredFlag.getPosition(), 1)); 1454} 1455 1456bool 1457CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1458 &FS, 1459 const char *startSpecifier, 1460 unsigned specifierLen) { 1461 1462 using namespace analyze_format_string; 1463 using namespace analyze_printf; 1464 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1465 1466 if (FS.consumesDataArgument()) { 1467 if (atFirstArg) { 1468 atFirstArg = false; 1469 usesPositionalArgs = FS.usesPositionalArg(); 1470 } 1471 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1472 // Cannot mix-and-match positional and non-positional arguments. 1473 S.Diag(getLocationOfByte(CS.getStart()), 1474 diag::warn_format_mix_positional_nonpositional_args) 1475 << getSpecifierRange(startSpecifier, specifierLen); 1476 return false; 1477 } 1478 } 1479 1480 // First check if the field width, precision, and conversion specifier 1481 // have matching data arguments. 1482 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1483 startSpecifier, specifierLen)) { 1484 return false; 1485 } 1486 1487 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1488 startSpecifier, specifierLen)) { 1489 return false; 1490 } 1491 1492 if (!CS.consumesDataArgument()) { 1493 // FIXME: Technically specifying a precision or field width here 1494 // makes no sense. Worth issuing a warning at some point. 1495 return true; 1496 } 1497 1498 // Consume the argument. 1499 unsigned argIndex = FS.getArgIndex(); 1500 if (argIndex < NumDataArgs) { 1501 // The check to see if the argIndex is valid will come later. 1502 // We set the bit here because we may exit early from this 1503 // function if we encounter some other error. 1504 CoveredArgs.set(argIndex); 1505 } 1506 1507 // Check for using an Objective-C specific conversion specifier 1508 // in a non-ObjC literal. 1509 if (!IsObjCLiteral && CS.isObjCArg()) { 1510 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1511 specifierLen); 1512 } 1513 1514 // Check for invalid use of field width 1515 if (!FS.hasValidFieldWidth()) { 1516 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1517 startSpecifier, specifierLen); 1518 } 1519 1520 // Check for invalid use of precision 1521 if (!FS.hasValidPrecision()) { 1522 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1523 startSpecifier, specifierLen); 1524 } 1525 1526 // Check each flag does not conflict with any other component. 1527 if (!FS.hasValidThousandsGroupingPrefix()) 1528 HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); 1529 if (!FS.hasValidLeadingZeros()) 1530 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1531 if (!FS.hasValidPlusPrefix()) 1532 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1533 if (!FS.hasValidSpacePrefix()) 1534 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1535 if (!FS.hasValidAlternativeForm()) 1536 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1537 if (!FS.hasValidLeftJustified()) 1538 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1539 1540 // Check that flags are not ignored by another flag 1541 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1542 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1543 startSpecifier, specifierLen); 1544 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1545 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1546 startSpecifier, specifierLen); 1547 1548 // Check the length modifier is valid with the given conversion specifier. 1549 const LengthModifier &LM = FS.getLengthModifier(); 1550 if (!FS.hasValidLengthModifier()) 1551 S.Diag(getLocationOfByte(LM.getStart()), 1552 diag::warn_format_nonsensical_length) 1553 << LM.toString() << CS.toString() 1554 << getSpecifierRange(startSpecifier, specifierLen) 1555 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1556 LM.getLength())); 1557 1558 // Are we using '%n'? 1559 if (CS.getKind() == ConversionSpecifier::nArg) { 1560 // Issue a warning about this being a possible security issue. 1561 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1562 << getSpecifierRange(startSpecifier, specifierLen); 1563 // Continue checking the other format specifiers. 1564 return true; 1565 } 1566 1567 // The remaining checks depend on the data arguments. 1568 if (HasVAListArg) 1569 return true; 1570 1571 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1572 return false; 1573 1574 // Now type check the data expression that matches the 1575 // format specifier. 1576 const Expr *Ex = getDataArg(argIndex); 1577 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1578 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1579 // Check if we didn't match because of an implicit cast from a 'char' 1580 // or 'short' to an 'int'. This is done because printf is a varargs 1581 // function. 1582 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1583 if (ICE->getType() == S.Context.IntTy) { 1584 // All further checking is done on the subexpression. 1585 Ex = ICE->getSubExpr(); 1586 if (ATR.matchesType(S.Context, Ex->getType())) 1587 return true; 1588 } 1589 1590 // We may be able to offer a FixItHint if it is a supported type. 1591 PrintfSpecifier fixedFS = FS; 1592 bool success = fixedFS.fixType(Ex->getType()); 1593 1594 if (success) { 1595 // Get the fix string from the fixed format specifier 1596 llvm::SmallString<128> buf; 1597 llvm::raw_svector_ostream os(buf); 1598 fixedFS.toString(os); 1599 1600 // FIXME: getRepresentativeType() perhaps should return a string 1601 // instead of a QualType to better handle when the representative 1602 // type is 'wint_t' (which is defined in the system headers). 1603 S.Diag(getLocationOfByte(CS.getStart()), 1604 diag::warn_printf_conversion_argument_type_mismatch) 1605 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1606 << getSpecifierRange(startSpecifier, specifierLen) 1607 << Ex->getSourceRange() 1608 << FixItHint::CreateReplacement( 1609 getSpecifierRange(startSpecifier, specifierLen), 1610 os.str()); 1611 } 1612 else { 1613 S.Diag(getLocationOfByte(CS.getStart()), 1614 diag::warn_printf_conversion_argument_type_mismatch) 1615 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1616 << getSpecifierRange(startSpecifier, specifierLen) 1617 << Ex->getSourceRange(); 1618 } 1619 } 1620 1621 return true; 1622} 1623 1624//===--- CHECK: Scanf format string checking ------------------------------===// 1625 1626namespace { 1627class CheckScanfHandler : public CheckFormatHandler { 1628public: 1629 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1630 const Expr *origFormatExpr, unsigned firstDataArg, 1631 unsigned numDataArgs, bool isObjCLiteral, 1632 const char *beg, bool hasVAListArg, 1633 const CallExpr *theCall, unsigned formatIdx) 1634 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1635 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1636 theCall, formatIdx) {} 1637 1638 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1639 const char *startSpecifier, 1640 unsigned specifierLen); 1641 1642 bool HandleInvalidScanfConversionSpecifier( 1643 const analyze_scanf::ScanfSpecifier &FS, 1644 const char *startSpecifier, 1645 unsigned specifierLen); 1646 1647 void HandleIncompleteScanList(const char *start, const char *end); 1648}; 1649} 1650 1651void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1652 const char *end) { 1653 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1654 << getSpecifierRange(start, end - start); 1655} 1656 1657bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1658 const analyze_scanf::ScanfSpecifier &FS, 1659 const char *startSpecifier, 1660 unsigned specifierLen) { 1661 1662 const analyze_scanf::ScanfConversionSpecifier &CS = 1663 FS.getConversionSpecifier(); 1664 1665 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1666 getLocationOfByte(CS.getStart()), 1667 startSpecifier, specifierLen, 1668 CS.getStart(), CS.getLength()); 1669} 1670 1671bool CheckScanfHandler::HandleScanfSpecifier( 1672 const analyze_scanf::ScanfSpecifier &FS, 1673 const char *startSpecifier, 1674 unsigned specifierLen) { 1675 1676 using namespace analyze_scanf; 1677 using namespace analyze_format_string; 1678 1679 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1680 1681 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1682 // be used to decide if we are using positional arguments consistently. 1683 if (FS.consumesDataArgument()) { 1684 if (atFirstArg) { 1685 atFirstArg = false; 1686 usesPositionalArgs = FS.usesPositionalArg(); 1687 } 1688 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1689 // Cannot mix-and-match positional and non-positional arguments. 1690 S.Diag(getLocationOfByte(CS.getStart()), 1691 diag::warn_format_mix_positional_nonpositional_args) 1692 << getSpecifierRange(startSpecifier, specifierLen); 1693 return false; 1694 } 1695 } 1696 1697 // Check if the field with is non-zero. 1698 const OptionalAmount &Amt = FS.getFieldWidth(); 1699 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1700 if (Amt.getConstantAmount() == 0) { 1701 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1702 Amt.getConstantLength()); 1703 S.Diag(getLocationOfByte(Amt.getStart()), 1704 diag::warn_scanf_nonzero_width) 1705 << R << FixItHint::CreateRemoval(R); 1706 } 1707 } 1708 1709 if (!FS.consumesDataArgument()) { 1710 // FIXME: Technically specifying a precision or field width here 1711 // makes no sense. Worth issuing a warning at some point. 1712 return true; 1713 } 1714 1715 // Consume the argument. 1716 unsigned argIndex = FS.getArgIndex(); 1717 if (argIndex < NumDataArgs) { 1718 // The check to see if the argIndex is valid will come later. 1719 // We set the bit here because we may exit early from this 1720 // function if we encounter some other error. 1721 CoveredArgs.set(argIndex); 1722 } 1723 1724 // Check the length modifier is valid with the given conversion specifier. 1725 const LengthModifier &LM = FS.getLengthModifier(); 1726 if (!FS.hasValidLengthModifier()) { 1727 S.Diag(getLocationOfByte(LM.getStart()), 1728 diag::warn_format_nonsensical_length) 1729 << LM.toString() << CS.toString() 1730 << getSpecifierRange(startSpecifier, specifierLen) 1731 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1732 LM.getLength())); 1733 } 1734 1735 // The remaining checks depend on the data arguments. 1736 if (HasVAListArg) 1737 return true; 1738 1739 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1740 return false; 1741 1742 // FIXME: Check that the argument type matches the format specifier. 1743 1744 return true; 1745} 1746 1747void Sema::CheckFormatString(const StringLiteral *FExpr, 1748 const Expr *OrigFormatExpr, 1749 const CallExpr *TheCall, bool HasVAListArg, 1750 unsigned format_idx, unsigned firstDataArg, 1751 bool isPrintf) { 1752 1753 // CHECK: is the format string a wide literal? 1754 if (FExpr->isWide()) { 1755 Diag(FExpr->getLocStart(), 1756 diag::warn_format_string_is_wide_literal) 1757 << OrigFormatExpr->getSourceRange(); 1758 return; 1759 } 1760 1761 // Str - The format string. NOTE: this is NOT null-terminated! 1762 llvm::StringRef StrRef = FExpr->getString(); 1763 const char *Str = StrRef.data(); 1764 unsigned StrLen = StrRef.size(); 1765 1766 // CHECK: empty format string? 1767 if (StrLen == 0) { 1768 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1769 << OrigFormatExpr->getSourceRange(); 1770 return; 1771 } 1772 1773 if (isPrintf) { 1774 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1775 TheCall->getNumArgs() - firstDataArg, 1776 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1777 HasVAListArg, TheCall, format_idx); 1778 1779 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1780 H.DoneProcessing(); 1781 } 1782 else { 1783 CheckScanfHandler 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::ParseScanfString(H, Str, Str + StrLen)) 1789 H.DoneProcessing(); 1790 } 1791} 1792 1793//===--- CHECK: Return Address of Stack Variable --------------------------===// 1794 1795static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1796static Expr *EvalAddr(Expr* E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1797 1798/// CheckReturnStackAddr - Check if a return statement returns the address 1799/// of a stack variable. 1800void 1801Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1802 SourceLocation ReturnLoc) { 1803 1804 Expr *stackE = 0; 1805 llvm::SmallVector<DeclRefExpr *, 8> refVars; 1806 1807 // Perform checking for returned stack addresses, local blocks, 1808 // label addresses or references to temporaries. 1809 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1810 stackE = EvalAddr(RetValExp, refVars); 1811 } else if (lhsType->isReferenceType()) { 1812 stackE = EvalVal(RetValExp, refVars); 1813 } 1814 1815 if (stackE == 0) 1816 return; // Nothing suspicious was found. 1817 1818 SourceLocation diagLoc; 1819 SourceRange diagRange; 1820 if (refVars.empty()) { 1821 diagLoc = stackE->getLocStart(); 1822 diagRange = stackE->getSourceRange(); 1823 } else { 1824 // We followed through a reference variable. 'stackE' contains the 1825 // problematic expression but we will warn at the return statement pointing 1826 // at the reference variable. We will later display the "trail" of 1827 // reference variables using notes. 1828 diagLoc = refVars[0]->getLocStart(); 1829 diagRange = refVars[0]->getSourceRange(); 1830 } 1831 1832 if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. 1833 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref 1834 : diag::warn_ret_stack_addr) 1835 << DR->getDecl()->getDeclName() << diagRange; 1836 } else if (isa<BlockExpr>(stackE)) { // local block. 1837 Diag(diagLoc, diag::err_ret_local_block) << diagRange; 1838 } else if (isa<AddrLabelExpr>(stackE)) { // address of label. 1839 Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; 1840 } else { // local temporary. 1841 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref 1842 : diag::warn_ret_local_temp_addr) 1843 << diagRange; 1844 } 1845 1846 // Display the "trail" of reference variables that we followed until we 1847 // found the problematic expression using notes. 1848 for (unsigned i = 0, e = refVars.size(); i != e; ++i) { 1849 VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); 1850 // If this var binds to another reference var, show the range of the next 1851 // var, otherwise the var binds to the problematic expression, in which case 1852 // show the range of the expression. 1853 SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() 1854 : stackE->getSourceRange(); 1855 Diag(VD->getLocation(), diag::note_ref_var_local_bind) 1856 << VD->getDeclName() << range; 1857 } 1858} 1859 1860/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1861/// check if the expression in a return statement evaluates to an address 1862/// to a location on the stack, a local block, an address of a label, or a 1863/// reference to local temporary. The recursion is used to traverse the 1864/// AST of the return expression, with recursion backtracking when we 1865/// encounter a subexpression that (1) clearly does not lead to one of the 1866/// above problematic expressions (2) is something we cannot determine leads to 1867/// a problematic expression based on such local checking. 1868/// 1869/// Both EvalAddr and EvalVal follow through reference variables to evaluate 1870/// the expression that they point to. Such variables are added to the 1871/// 'refVars' vector so that we know what the reference variable "trail" was. 1872/// 1873/// EvalAddr processes expressions that are pointers that are used as 1874/// references (and not L-values). EvalVal handles all other values. 1875/// At the base case of the recursion is a check for the above problematic 1876/// expressions. 1877/// 1878/// This implementation handles: 1879/// 1880/// * pointer-to-pointer casts 1881/// * implicit conversions from array references to pointers 1882/// * taking the address of fields 1883/// * arbitrary interplay between "&" and "*" operators 1884/// * pointer arithmetic from an address of a stack variable 1885/// * taking the address of an array element where the array is on the stack 1886static Expr *EvalAddr(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 1887 if (E->isTypeDependent()) 1888 return NULL; 1889 1890 // We should only be called for evaluating pointer expressions. 1891 assert((E->getType()->isAnyPointerType() || 1892 E->getType()->isBlockPointerType() || 1893 E->getType()->isObjCQualifiedIdType()) && 1894 "EvalAddr only works on pointers"); 1895 1896 // Our "symbolic interpreter" is just a dispatch off the currently 1897 // viewed AST node. We then recursively traverse the AST by calling 1898 // EvalAddr and EvalVal appropriately. 1899 switch (E->getStmtClass()) { 1900 case Stmt::ParenExprClass: 1901 // Ignore parentheses. 1902 return EvalAddr(cast<ParenExpr>(E)->getSubExpr(), refVars); 1903 1904 case Stmt::DeclRefExprClass: { 1905 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1906 1907 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1908 // If this is a reference variable, follow through to the expression that 1909 // it points to. 1910 if (V->hasLocalStorage() && 1911 V->getType()->isReferenceType() && V->hasInit()) { 1912 // Add the reference variable to the "trail". 1913 refVars.push_back(DR); 1914 return EvalAddr(V->getInit(), refVars); 1915 } 1916 1917 return NULL; 1918 } 1919 1920 case Stmt::UnaryOperatorClass: { 1921 // The only unary operator that make sense to handle here 1922 // is AddrOf. All others don't make sense as pointers. 1923 UnaryOperator *U = cast<UnaryOperator>(E); 1924 1925 if (U->getOpcode() == UO_AddrOf) 1926 return EvalVal(U->getSubExpr(), refVars); 1927 else 1928 return NULL; 1929 } 1930 1931 case Stmt::BinaryOperatorClass: { 1932 // Handle pointer arithmetic. All other binary operators are not valid 1933 // in this context. 1934 BinaryOperator *B = cast<BinaryOperator>(E); 1935 BinaryOperatorKind op = B->getOpcode(); 1936 1937 if (op != BO_Add && op != BO_Sub) 1938 return NULL; 1939 1940 Expr *Base = B->getLHS(); 1941 1942 // Determine which argument is the real pointer base. It could be 1943 // the RHS argument instead of the LHS. 1944 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1945 1946 assert (Base->getType()->isPointerType()); 1947 return EvalAddr(Base, refVars); 1948 } 1949 1950 // For conditional operators we need to see if either the LHS or RHS are 1951 // valid DeclRefExpr*s. If one of them is valid, we return it. 1952 case Stmt::ConditionalOperatorClass: { 1953 ConditionalOperator *C = cast<ConditionalOperator>(E); 1954 1955 // Handle the GNU extension for missing LHS. 1956 if (Expr *lhsExpr = C->getLHS()) { 1957 // In C++, we can have a throw-expression, which has 'void' type. 1958 if (!lhsExpr->getType()->isVoidType()) 1959 if (Expr* LHS = EvalAddr(lhsExpr, refVars)) 1960 return LHS; 1961 } 1962 1963 // In C++, we can have a throw-expression, which has 'void' type. 1964 if (C->getRHS()->getType()->isVoidType()) 1965 return NULL; 1966 1967 return EvalAddr(C->getRHS(), refVars); 1968 } 1969 1970 case Stmt::BlockExprClass: 1971 if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) 1972 return E; // local block. 1973 return NULL; 1974 1975 case Stmt::AddrLabelExprClass: 1976 return E; // address of label. 1977 1978 // For casts, we need to handle conversions from arrays to 1979 // pointer values, and pointer-to-pointer conversions. 1980 case Stmt::ImplicitCastExprClass: 1981 case Stmt::CStyleCastExprClass: 1982 case Stmt::CXXFunctionalCastExprClass: { 1983 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1984 QualType T = SubExpr->getType(); 1985 1986 if (SubExpr->getType()->isPointerType() || 1987 SubExpr->getType()->isBlockPointerType() || 1988 SubExpr->getType()->isObjCQualifiedIdType()) 1989 return EvalAddr(SubExpr, refVars); 1990 else if (T->isArrayType()) 1991 return EvalVal(SubExpr, refVars); 1992 else 1993 return 0; 1994 } 1995 1996 // C++ casts. For dynamic casts, static casts, and const casts, we 1997 // are always converting from a pointer-to-pointer, so we just blow 1998 // through the cast. In the case the dynamic cast doesn't fail (and 1999 // return NULL), we take the conservative route and report cases 2000 // where we return the address of a stack variable. For Reinterpre 2001 // FIXME: The comment about is wrong; we're not always converting 2002 // from pointer to pointer. I'm guessing that this code should also 2003 // handle references to objects. 2004 case Stmt::CXXStaticCastExprClass: 2005 case Stmt::CXXDynamicCastExprClass: 2006 case Stmt::CXXConstCastExprClass: 2007 case Stmt::CXXReinterpretCastExprClass: { 2008 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 2009 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 2010 return EvalAddr(S, refVars); 2011 else 2012 return NULL; 2013 } 2014 2015 // Everything else: we simply don't reason about them. 2016 default: 2017 return NULL; 2018 } 2019} 2020 2021 2022/// EvalVal - This function is complements EvalAddr in the mutual recursion. 2023/// See the comments for EvalAddr for more details. 2024static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 2025do { 2026 // We should only be called for evaluating non-pointer expressions, or 2027 // expressions with a pointer type that are not used as references but instead 2028 // are l-values (e.g., DeclRefExpr with a pointer type). 2029 2030 // Our "symbolic interpreter" is just a dispatch off the currently 2031 // viewed AST node. We then recursively traverse the AST by calling 2032 // EvalAddr and EvalVal appropriately. 2033 switch (E->getStmtClass()) { 2034 case Stmt::ImplicitCastExprClass: { 2035 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 2036 if (IE->getValueKind() == VK_LValue) { 2037 E = IE->getSubExpr(); 2038 continue; 2039 } 2040 return NULL; 2041 } 2042 2043 case Stmt::DeclRefExprClass: { 2044 // When we hit a DeclRefExpr we are looking at code that refers to a 2045 // variable's name. If it's not a reference variable we check if it has 2046 // local storage within the function, and if so, return the expression. 2047 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2048 2049 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2050 if (V->hasLocalStorage()) { 2051 if (!V->getType()->isReferenceType()) 2052 return DR; 2053 2054 // Reference variable, follow through to the expression that 2055 // it points to. 2056 if (V->hasInit()) { 2057 // Add the reference variable to the "trail". 2058 refVars.push_back(DR); 2059 return EvalVal(V->getInit(), refVars); 2060 } 2061 } 2062 2063 return NULL; 2064 } 2065 2066 case Stmt::ParenExprClass: { 2067 // Ignore parentheses. 2068 E = cast<ParenExpr>(E)->getSubExpr(); 2069 continue; 2070 } 2071 2072 case Stmt::UnaryOperatorClass: { 2073 // The only unary operator that make sense to handle here 2074 // is Deref. All others don't resolve to a "name." This includes 2075 // handling all sorts of rvalues passed to a unary operator. 2076 UnaryOperator *U = cast<UnaryOperator>(E); 2077 2078 if (U->getOpcode() == UO_Deref) 2079 return EvalAddr(U->getSubExpr(), refVars); 2080 2081 return NULL; 2082 } 2083 2084 case Stmt::ArraySubscriptExprClass: { 2085 // Array subscripts are potential references to data on the stack. We 2086 // retrieve the DeclRefExpr* for the array variable if it indeed 2087 // has local storage. 2088 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars); 2089 } 2090 2091 case Stmt::ConditionalOperatorClass: { 2092 // For conditional operators we need to see if either the LHS or RHS are 2093 // non-NULL Expr's. If one is non-NULL, we return it. 2094 ConditionalOperator *C = cast<ConditionalOperator>(E); 2095 2096 // Handle the GNU extension for missing LHS. 2097 if (Expr *lhsExpr = C->getLHS()) 2098 if (Expr *LHS = EvalVal(lhsExpr, refVars)) 2099 return LHS; 2100 2101 return EvalVal(C->getRHS(), refVars); 2102 } 2103 2104 // Accesses to members are potential references to data on the stack. 2105 case Stmt::MemberExprClass: { 2106 MemberExpr *M = cast<MemberExpr>(E); 2107 2108 // Check for indirect access. We only want direct field accesses. 2109 if (M->isArrow()) 2110 return NULL; 2111 2112 // Check whether the member type is itself a reference, in which case 2113 // we're not going to refer to the member, but to what the member refers to. 2114 if (M->getMemberDecl()->getType()->isReferenceType()) 2115 return NULL; 2116 2117 return EvalVal(M->getBase(), refVars); 2118 } 2119 2120 default: 2121 // Check that we don't return or take the address of a reference to a 2122 // temporary. This is only useful in C++. 2123 if (!E->isTypeDependent() && E->isRValue()) 2124 return E; 2125 2126 // Everything else: we simply don't reason about them. 2127 return NULL; 2128 } 2129} while (true); 2130} 2131 2132//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2133 2134/// Check for comparisons of floating point operands using != and ==. 2135/// Issue a warning if these are no self-comparisons, as they are not likely 2136/// to do what the programmer intended. 2137void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2138 bool EmitWarning = true; 2139 2140 Expr* LeftExprSansParen = lex->IgnoreParenImpCasts(); 2141 Expr* RightExprSansParen = rex->IgnoreParenImpCasts(); 2142 2143 // Special case: check for x == x (which is OK). 2144 // Do not emit warnings for such cases. 2145 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2146 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2147 if (DRL->getDecl() == DRR->getDecl()) 2148 EmitWarning = false; 2149 2150 2151 // Special case: check for comparisons against literals that can be exactly 2152 // represented by APFloat. In such cases, do not emit a warning. This 2153 // is a heuristic: often comparison against such literals are used to 2154 // detect if a value in a variable has not changed. This clearly can 2155 // lead to false negatives. 2156 if (EmitWarning) { 2157 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2158 if (FLL->isExact()) 2159 EmitWarning = false; 2160 } else 2161 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2162 if (FLR->isExact()) 2163 EmitWarning = false; 2164 } 2165 } 2166 2167 // Check for comparisons with builtin types. 2168 if (EmitWarning) 2169 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2170 if (CL->isBuiltinCall(Context)) 2171 EmitWarning = false; 2172 2173 if (EmitWarning) 2174 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2175 if (CR->isBuiltinCall(Context)) 2176 EmitWarning = false; 2177 2178 // Emit the diagnostic. 2179 if (EmitWarning) 2180 Diag(loc, diag::warn_floatingpoint_eq) 2181 << lex->getSourceRange() << rex->getSourceRange(); 2182} 2183 2184//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2185//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2186 2187namespace { 2188 2189/// Structure recording the 'active' range of an integer-valued 2190/// expression. 2191struct IntRange { 2192 /// The number of bits active in the int. 2193 unsigned Width; 2194 2195 /// True if the int is known not to have negative values. 2196 bool NonNegative; 2197 2198 IntRange(unsigned Width, bool NonNegative) 2199 : Width(Width), NonNegative(NonNegative) 2200 {} 2201 2202 /// Returns the range of the bool type. 2203 static IntRange forBoolType() { 2204 return IntRange(1, true); 2205 } 2206 2207 /// Returns the range of an opaque value of the given integral type. 2208 static IntRange forValueOfType(ASTContext &C, QualType T) { 2209 return forValueOfCanonicalType(C, 2210 T->getCanonicalTypeInternal().getTypePtr()); 2211 } 2212 2213 /// Returns the range of an opaque value of a canonical integral type. 2214 static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) { 2215 assert(T->isCanonicalUnqualified()); 2216 2217 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2218 T = VT->getElementType().getTypePtr(); 2219 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2220 T = CT->getElementType().getTypePtr(); 2221 2222 // For enum types, use the known bit width of the enumerators. 2223 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2224 EnumDecl *Enum = ET->getDecl(); 2225 if (!Enum->isDefinition()) 2226 return IntRange(C.getIntWidth(QualType(T, 0)), false); 2227 2228 unsigned NumPositive = Enum->getNumPositiveBits(); 2229 unsigned NumNegative = Enum->getNumNegativeBits(); 2230 2231 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2232 } 2233 2234 const BuiltinType *BT = cast<BuiltinType>(T); 2235 assert(BT->isInteger()); 2236 2237 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2238 } 2239 2240 /// Returns the "target" range of a canonical integral type, i.e. 2241 /// the range of values expressible in the type. 2242 /// 2243 /// This matches forValueOfCanonicalType except that enums have the 2244 /// full range of their type, not the range of their enumerators. 2245 static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) { 2246 assert(T->isCanonicalUnqualified()); 2247 2248 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2249 T = VT->getElementType().getTypePtr(); 2250 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2251 T = CT->getElementType().getTypePtr(); 2252 if (const EnumType *ET = dyn_cast<EnumType>(T)) 2253 T = ET->getDecl()->getIntegerType().getTypePtr(); 2254 2255 const BuiltinType *BT = cast<BuiltinType>(T); 2256 assert(BT->isInteger()); 2257 2258 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2259 } 2260 2261 /// Returns the supremum of two ranges: i.e. their conservative merge. 2262 static IntRange join(IntRange L, IntRange R) { 2263 return IntRange(std::max(L.Width, R.Width), 2264 L.NonNegative && R.NonNegative); 2265 } 2266 2267 /// Returns the infinum of two ranges: i.e. their aggressive merge. 2268 static IntRange meet(IntRange L, IntRange R) { 2269 return IntRange(std::min(L.Width, R.Width), 2270 L.NonNegative || R.NonNegative); 2271 } 2272}; 2273 2274IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2275 if (value.isSigned() && value.isNegative()) 2276 return IntRange(value.getMinSignedBits(), false); 2277 2278 if (value.getBitWidth() > MaxWidth) 2279 value = value.trunc(MaxWidth); 2280 2281 // isNonNegative() just checks the sign bit without considering 2282 // signedness. 2283 return IntRange(value.getActiveBits(), true); 2284} 2285 2286IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2287 unsigned MaxWidth) { 2288 if (result.isInt()) 2289 return GetValueRange(C, result.getInt(), MaxWidth); 2290 2291 if (result.isVector()) { 2292 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2293 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2294 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2295 R = IntRange::join(R, El); 2296 } 2297 return R; 2298 } 2299 2300 if (result.isComplexInt()) { 2301 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2302 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2303 return IntRange::join(R, I); 2304 } 2305 2306 // This can happen with lossless casts to intptr_t of "based" lvalues. 2307 // Assume it might use arbitrary bits. 2308 // FIXME: The only reason we need to pass the type in here is to get 2309 // the sign right on this one case. It would be nice if APValue 2310 // preserved this. 2311 assert(result.isLValue()); 2312 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2313} 2314 2315/// Pseudo-evaluate the given integer expression, estimating the 2316/// range of values it might take. 2317/// 2318/// \param MaxWidth - the width to which the value will be truncated 2319IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2320 E = E->IgnoreParens(); 2321 2322 // Try a full evaluation first. 2323 Expr::EvalResult result; 2324 if (E->Evaluate(result, C)) 2325 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2326 2327 // I think we only want to look through implicit casts here; if the 2328 // user has an explicit widening cast, we should treat the value as 2329 // being of the new, wider type. 2330 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2331 if (CE->getCastKind() == CK_NoOp) 2332 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2333 2334 IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); 2335 2336 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 2337 2338 // Assume that non-integer casts can span the full range of the type. 2339 if (!isIntegerCast) 2340 return OutputTypeRange; 2341 2342 IntRange SubRange 2343 = GetExprRange(C, CE->getSubExpr(), 2344 std::min(MaxWidth, OutputTypeRange.Width)); 2345 2346 // Bail out if the subexpr's range is as wide as the cast type. 2347 if (SubRange.Width >= OutputTypeRange.Width) 2348 return OutputTypeRange; 2349 2350 // Otherwise, we take the smaller width, and we're non-negative if 2351 // either the output type or the subexpr is. 2352 return IntRange(SubRange.Width, 2353 SubRange.NonNegative || OutputTypeRange.NonNegative); 2354 } 2355 2356 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2357 // If we can fold the condition, just take that operand. 2358 bool CondResult; 2359 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2360 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2361 : CO->getFalseExpr(), 2362 MaxWidth); 2363 2364 // Otherwise, conservatively merge. 2365 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2366 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2367 return IntRange::join(L, R); 2368 } 2369 2370 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2371 switch (BO->getOpcode()) { 2372 2373 // Boolean-valued operations are single-bit and positive. 2374 case BO_LAnd: 2375 case BO_LOr: 2376 case BO_LT: 2377 case BO_GT: 2378 case BO_LE: 2379 case BO_GE: 2380 case BO_EQ: 2381 case BO_NE: 2382 return IntRange::forBoolType(); 2383 2384 // The type of these compound assignments is the type of the LHS, 2385 // so the RHS is not necessarily an integer. 2386 case BO_MulAssign: 2387 case BO_DivAssign: 2388 case BO_RemAssign: 2389 case BO_AddAssign: 2390 case BO_SubAssign: 2391 return IntRange::forValueOfType(C, E->getType()); 2392 2393 // Operations with opaque sources are black-listed. 2394 case BO_PtrMemD: 2395 case BO_PtrMemI: 2396 return IntRange::forValueOfType(C, E->getType()); 2397 2398 // Bitwise-and uses the *infinum* of the two source ranges. 2399 case BO_And: 2400 case BO_AndAssign: 2401 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2402 GetExprRange(C, BO->getRHS(), MaxWidth)); 2403 2404 // Left shift gets black-listed based on a judgement call. 2405 case BO_Shl: 2406 // ...except that we want to treat '1 << (blah)' as logically 2407 // positive. It's an important idiom. 2408 if (IntegerLiteral *I 2409 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2410 if (I->getValue() == 1) { 2411 IntRange R = IntRange::forValueOfType(C, E->getType()); 2412 return IntRange(R.Width, /*NonNegative*/ true); 2413 } 2414 } 2415 // fallthrough 2416 2417 case BO_ShlAssign: 2418 return IntRange::forValueOfType(C, E->getType()); 2419 2420 // Right shift by a constant can narrow its left argument. 2421 case BO_Shr: 2422 case BO_ShrAssign: { 2423 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2424 2425 // If the shift amount is a positive constant, drop the width by 2426 // that much. 2427 llvm::APSInt shift; 2428 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2429 shift.isNonNegative()) { 2430 unsigned zext = shift.getZExtValue(); 2431 if (zext >= L.Width) 2432 L.Width = (L.NonNegative ? 0 : 1); 2433 else 2434 L.Width -= zext; 2435 } 2436 2437 return L; 2438 } 2439 2440 // Comma acts as its right operand. 2441 case BO_Comma: 2442 return GetExprRange(C, BO->getRHS(), MaxWidth); 2443 2444 // Black-list pointer subtractions. 2445 case BO_Sub: 2446 if (BO->getLHS()->getType()->isPointerType()) 2447 return IntRange::forValueOfType(C, E->getType()); 2448 // fallthrough 2449 2450 default: 2451 break; 2452 } 2453 2454 // Treat every other operator as if it were closed on the 2455 // narrowest type that encompasses both operands. 2456 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2457 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2458 return IntRange::join(L, R); 2459 } 2460 2461 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2462 switch (UO->getOpcode()) { 2463 // Boolean-valued operations are white-listed. 2464 case UO_LNot: 2465 return IntRange::forBoolType(); 2466 2467 // Operations with opaque sources are black-listed. 2468 case UO_Deref: 2469 case UO_AddrOf: // should be impossible 2470 return IntRange::forValueOfType(C, E->getType()); 2471 2472 default: 2473 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2474 } 2475 } 2476 2477 if (dyn_cast<OffsetOfExpr>(E)) { 2478 IntRange::forValueOfType(C, E->getType()); 2479 } 2480 2481 FieldDecl *BitField = E->getBitField(); 2482 if (BitField) { 2483 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2484 unsigned BitWidth = BitWidthAP.getZExtValue(); 2485 2486 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2487 } 2488 2489 return IntRange::forValueOfType(C, E->getType()); 2490} 2491 2492IntRange GetExprRange(ASTContext &C, Expr *E) { 2493 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2494} 2495 2496/// Checks whether the given value, which currently has the given 2497/// source semantics, has the same value when coerced through the 2498/// target semantics. 2499bool IsSameFloatAfterCast(const llvm::APFloat &value, 2500 const llvm::fltSemantics &Src, 2501 const llvm::fltSemantics &Tgt) { 2502 llvm::APFloat truncated = value; 2503 2504 bool ignored; 2505 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2506 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2507 2508 return truncated.bitwiseIsEqual(value); 2509} 2510 2511/// Checks whether the given value, which currently has the given 2512/// source semantics, has the same value when coerced through the 2513/// target semantics. 2514/// 2515/// The value might be a vector of floats (or a complex number). 2516bool IsSameFloatAfterCast(const APValue &value, 2517 const llvm::fltSemantics &Src, 2518 const llvm::fltSemantics &Tgt) { 2519 if (value.isFloat()) 2520 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2521 2522 if (value.isVector()) { 2523 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2524 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2525 return false; 2526 return true; 2527 } 2528 2529 assert(value.isComplexFloat()); 2530 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2531 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2532} 2533 2534void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC); 2535 2536static bool IsZero(Sema &S, Expr *E) { 2537 // Suppress cases where we are comparing against an enum constant. 2538 if (const DeclRefExpr *DR = 2539 dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) 2540 if (isa<EnumConstantDecl>(DR->getDecl())) 2541 return false; 2542 2543 // Suppress cases where the '0' value is expanded from a macro. 2544 if (E->getLocStart().isMacroID()) 2545 return false; 2546 2547 llvm::APSInt Value; 2548 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2549} 2550 2551static bool HasEnumType(Expr *E) { 2552 // Strip off implicit integral promotions. 2553 while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { 2554 if (ICE->getCastKind() != CK_IntegralCast && 2555 ICE->getCastKind() != CK_NoOp) 2556 break; 2557 E = ICE->getSubExpr(); 2558 } 2559 2560 return E->getType()->isEnumeralType(); 2561} 2562 2563void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2564 BinaryOperatorKind op = E->getOpcode(); 2565 if (E->isValueDependent()) 2566 return; 2567 2568 if (op == BO_LT && IsZero(S, E->getRHS())) { 2569 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2570 << "< 0" << "false" << HasEnumType(E->getLHS()) 2571 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2572 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 2573 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2574 << ">= 0" << "true" << HasEnumType(E->getLHS()) 2575 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2576 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 2577 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2578 << "0 >" << "false" << HasEnumType(E->getRHS()) 2579 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2580 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 2581 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2582 << "0 <=" << "true" << HasEnumType(E->getRHS()) 2583 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2584 } 2585} 2586 2587/// Analyze the operands of the given comparison. Implements the 2588/// fallback case from AnalyzeComparison. 2589void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2590 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2591 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2592} 2593 2594/// \brief Implements -Wsign-compare. 2595/// 2596/// \param lex the left-hand expression 2597/// \param rex the right-hand expression 2598/// \param OpLoc the location of the joining operator 2599/// \param BinOpc binary opcode or 0 2600void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2601 // The type the comparison is being performed in. 2602 QualType T = E->getLHS()->getType(); 2603 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2604 && "comparison with mismatched types"); 2605 2606 // We don't do anything special if this isn't an unsigned integral 2607 // comparison: we're only interested in integral comparisons, and 2608 // signed comparisons only happen in cases we don't care to warn about. 2609 // 2610 // We also don't care about value-dependent expressions or expressions 2611 // whose result is a constant. 2612 if (!T->hasUnsignedIntegerRepresentation() 2613 || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) 2614 return AnalyzeImpConvsInComparison(S, E); 2615 2616 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2617 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2618 2619 // Check to see if one of the (unmodified) operands is of different 2620 // signedness. 2621 Expr *signedOperand, *unsignedOperand; 2622 if (lex->getType()->hasSignedIntegerRepresentation()) { 2623 assert(!rex->getType()->hasSignedIntegerRepresentation() && 2624 "unsigned comparison between two signed integer expressions?"); 2625 signedOperand = lex; 2626 unsignedOperand = rex; 2627 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 2628 signedOperand = rex; 2629 unsignedOperand = lex; 2630 } else { 2631 CheckTrivialUnsignedComparison(S, E); 2632 return AnalyzeImpConvsInComparison(S, E); 2633 } 2634 2635 // Otherwise, calculate the effective range of the signed operand. 2636 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2637 2638 // Go ahead and analyze implicit conversions in the operands. Note 2639 // that we skip the implicit conversions on both sides. 2640 AnalyzeImplicitConversions(S, lex, E->getOperatorLoc()); 2641 AnalyzeImplicitConversions(S, rex, E->getOperatorLoc()); 2642 2643 // If the signed range is non-negative, -Wsign-compare won't fire, 2644 // but we should still check for comparisons which are always true 2645 // or false. 2646 if (signedRange.NonNegative) 2647 return CheckTrivialUnsignedComparison(S, E); 2648 2649 // For (in)equality comparisons, if the unsigned operand is a 2650 // constant which cannot collide with a overflowed signed operand, 2651 // then reinterpreting the signed operand as unsigned will not 2652 // change the result of the comparison. 2653 if (E->isEqualityOp()) { 2654 unsigned comparisonWidth = S.Context.getIntWidth(T); 2655 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2656 2657 // We should never be unable to prove that the unsigned operand is 2658 // non-negative. 2659 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2660 2661 if (unsignedRange.Width < comparisonWidth) 2662 return; 2663 } 2664 2665 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2666 << lex->getType() << rex->getType() 2667 << lex->getSourceRange() << rex->getSourceRange(); 2668} 2669 2670/// Analyzes an attempt to assign the given value to a bitfield. 2671/// 2672/// Returns true if there was something fishy about the attempt. 2673bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, 2674 SourceLocation InitLoc) { 2675 assert(Bitfield->isBitField()); 2676 if (Bitfield->isInvalidDecl()) 2677 return false; 2678 2679 // White-list bool bitfields. 2680 if (Bitfield->getType()->isBooleanType()) 2681 return false; 2682 2683 // Ignore value- or type-dependent expressions. 2684 if (Bitfield->getBitWidth()->isValueDependent() || 2685 Bitfield->getBitWidth()->isTypeDependent() || 2686 Init->isValueDependent() || 2687 Init->isTypeDependent()) 2688 return false; 2689 2690 Expr *OriginalInit = Init->IgnoreParenImpCasts(); 2691 2692 llvm::APSInt Width(32); 2693 Expr::EvalResult InitValue; 2694 if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) || 2695 !OriginalInit->Evaluate(InitValue, S.Context) || 2696 !InitValue.Val.isInt()) 2697 return false; 2698 2699 const llvm::APSInt &Value = InitValue.Val.getInt(); 2700 unsigned OriginalWidth = Value.getBitWidth(); 2701 unsigned FieldWidth = Width.getZExtValue(); 2702 2703 if (OriginalWidth <= FieldWidth) 2704 return false; 2705 2706 llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); 2707 2708 // It's fairly common to write values into signed bitfields 2709 // that, if sign-extended, would end up becoming a different 2710 // value. We don't want to warn about that. 2711 if (Value.isSigned() && Value.isNegative()) 2712 TruncatedValue = TruncatedValue.sext(OriginalWidth); 2713 else 2714 TruncatedValue = TruncatedValue.zext(OriginalWidth); 2715 2716 if (Value == TruncatedValue) 2717 return false; 2718 2719 std::string PrettyValue = Value.toString(10); 2720 std::string PrettyTrunc = TruncatedValue.toString(10); 2721 2722 S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) 2723 << PrettyValue << PrettyTrunc << OriginalInit->getType() 2724 << Init->getSourceRange(); 2725 2726 return true; 2727} 2728 2729/// Analyze the given simple or compound assignment for warning-worthy 2730/// operations. 2731void AnalyzeAssignment(Sema &S, BinaryOperator *E) { 2732 // Just recurse on the LHS. 2733 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2734 2735 // We want to recurse on the RHS as normal unless we're assigning to 2736 // a bitfield. 2737 if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { 2738 if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), 2739 E->getOperatorLoc())) { 2740 // Recurse, ignoring any implicit conversions on the RHS. 2741 return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), 2742 E->getOperatorLoc()); 2743 } 2744 } 2745 2746 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2747} 2748 2749/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2750void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext, 2751 unsigned diag) { 2752 S.Diag(E->getExprLoc(), diag) 2753 << E->getType() << T << E->getSourceRange() << SourceRange(CContext); 2754} 2755 2756std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { 2757 if (!Range.Width) return "0"; 2758 2759 llvm::APSInt ValueInRange = Value; 2760 ValueInRange.setIsSigned(!Range.NonNegative); 2761 ValueInRange = ValueInRange.trunc(Range.Width); 2762 return ValueInRange.toString(10); 2763} 2764 2765static bool isFromSystemMacro(Sema &S, SourceLocation loc) { 2766 SourceManager &smgr = S.Context.getSourceManager(); 2767 return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc)); 2768} 2769 2770void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2771 SourceLocation CC, bool *ICContext = 0) { 2772 if (E->isTypeDependent() || E->isValueDependent()) return; 2773 2774 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2775 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2776 if (Source == Target) return; 2777 if (Target->isDependentType()) return; 2778 2779 // If the conversion context location is invalid don't complain. 2780 // We also don't want to emit a warning if the issue occurs from the 2781 // instantiation of a system macro. The problem is that 'getSpellingLoc()' 2782 // is slow, so we delay this check as long as possible. Once we detect 2783 // we are in that scenario, we just return. 2784 if (CC.isInvalid()) 2785 return; 2786 2787 // Never diagnose implicit casts to bool. 2788 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2789 return; 2790 2791 // Strip vector types. 2792 if (isa<VectorType>(Source)) { 2793 if (!isa<VectorType>(Target)) { 2794 if (isFromSystemMacro(S, CC)) 2795 return; 2796 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar); 2797 } 2798 2799 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2800 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2801 } 2802 2803 // Strip complex types. 2804 if (isa<ComplexType>(Source)) { 2805 if (!isa<ComplexType>(Target)) { 2806 if (isFromSystemMacro(S, CC)) 2807 return; 2808 2809 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar); 2810 } 2811 2812 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2813 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2814 } 2815 2816 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2817 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2818 2819 // If the source is floating point... 2820 if (SourceBT && SourceBT->isFloatingPoint()) { 2821 // ...and the target is floating point... 2822 if (TargetBT && TargetBT->isFloatingPoint()) { 2823 // ...then warn if we're dropping FP rank. 2824 2825 // Builtin FP kinds are ordered by increasing FP rank. 2826 if (SourceBT->getKind() > TargetBT->getKind()) { 2827 // Don't warn about float constants that are precisely 2828 // representable in the target type. 2829 Expr::EvalResult result; 2830 if (E->Evaluate(result, S.Context)) { 2831 // Value might be a float, a float vector, or a float complex. 2832 if (IsSameFloatAfterCast(result.Val, 2833 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2834 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2835 return; 2836 } 2837 2838 if (isFromSystemMacro(S, CC)) 2839 return; 2840 2841 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision); 2842 } 2843 return; 2844 } 2845 2846 // If the target is integral, always warn. 2847 if ((TargetBT && TargetBT->isInteger())) { 2848 if (isFromSystemMacro(S, CC)) 2849 return; 2850 2851 Expr *InnerE = E->IgnoreParenImpCasts(); 2852 if (FloatingLiteral *LiteralExpr = dyn_cast<FloatingLiteral>(InnerE)) { 2853 DiagnoseImpCast(S, LiteralExpr, T, CC, 2854 diag::warn_impcast_literal_float_to_integer); 2855 } else { 2856 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); 2857 } 2858 } 2859 2860 return; 2861 } 2862 2863 if (!Source->isIntegerType() || !Target->isIntegerType()) 2864 return; 2865 2866 IntRange SourceRange = GetExprRange(S.Context, E); 2867 IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); 2868 2869 if (SourceRange.Width > TargetRange.Width) { 2870 // If the source is a constant, use a default-on diagnostic. 2871 // TODO: this should happen for bitfield stores, too. 2872 llvm::APSInt Value(32); 2873 if (E->isIntegerConstantExpr(Value, S.Context)) { 2874 if (isFromSystemMacro(S, CC)) 2875 return; 2876 2877 std::string PrettySourceValue = Value.toString(10); 2878 std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); 2879 2880 S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant) 2881 << PrettySourceValue << PrettyTargetValue 2882 << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC); 2883 return; 2884 } 2885 2886 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2887 // and by god we'll let them. 2888 2889 if (isFromSystemMacro(S, CC)) 2890 return; 2891 2892 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2893 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32); 2894 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); 2895 } 2896 2897 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2898 (!TargetRange.NonNegative && SourceRange.NonNegative && 2899 SourceRange.Width == TargetRange.Width)) { 2900 2901 if (isFromSystemMacro(S, CC)) 2902 return; 2903 2904 unsigned DiagID = diag::warn_impcast_integer_sign; 2905 2906 // Traditionally, gcc has warned about this under -Wsign-compare. 2907 // We also want to warn about it in -Wconversion. 2908 // So if -Wconversion is off, use a completely identical diagnostic 2909 // in the sign-compare group. 2910 // The conditional-checking code will 2911 if (ICContext) { 2912 DiagID = diag::warn_impcast_integer_sign_conditional; 2913 *ICContext = true; 2914 } 2915 2916 return DiagnoseImpCast(S, E, T, CC, DiagID); 2917 } 2918 2919 // Diagnose conversions between different enumeration types. 2920 if (const EnumType *SourceEnum = Source->getAs<EnumType>()) 2921 if (const EnumType *TargetEnum = Target->getAs<EnumType>()) 2922 if ((SourceEnum->getDecl()->getIdentifier() || 2923 SourceEnum->getDecl()->getTypedefForAnonDecl()) && 2924 (TargetEnum->getDecl()->getIdentifier() || 2925 TargetEnum->getDecl()->getTypedefForAnonDecl()) && 2926 SourceEnum != TargetEnum) { 2927 if (isFromSystemMacro(S, CC)) 2928 return; 2929 2930 return DiagnoseImpCast(S, E, T, CC, 2931 diag::warn_impcast_different_enum_types); 2932 } 2933 2934 return; 2935} 2936 2937void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2938 2939void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2940 SourceLocation CC, bool &ICContext) { 2941 E = E->IgnoreParenImpCasts(); 2942 2943 if (isa<ConditionalOperator>(E)) 2944 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2945 2946 AnalyzeImplicitConversions(S, E, CC); 2947 if (E->getType() != T) 2948 return CheckImplicitConversion(S, E, T, CC, &ICContext); 2949 return; 2950} 2951 2952void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2953 SourceLocation CC = E->getQuestionLoc(); 2954 2955 AnalyzeImplicitConversions(S, E->getCond(), CC); 2956 2957 bool Suspicious = false; 2958 CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); 2959 CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious); 2960 2961 // If -Wconversion would have warned about either of the candidates 2962 // for a signedness conversion to the context type... 2963 if (!Suspicious) return; 2964 2965 // ...but it's currently ignored... 2966 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional, 2967 CC)) 2968 return; 2969 2970 // ...and -Wsign-compare isn't... 2971 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional, CC)) 2972 return; 2973 2974 // ...then check whether it would have warned about either of the 2975 // candidates for a signedness conversion to the condition type. 2976 if (E->getType() != T) { 2977 Suspicious = false; 2978 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2979 E->getType(), CC, &Suspicious); 2980 if (!Suspicious) 2981 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2982 E->getType(), CC, &Suspicious); 2983 if (!Suspicious) 2984 return; 2985 } 2986 2987 // If so, emit a diagnostic under -Wsign-compare. 2988 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2989 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2990 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2991 << lex->getType() << rex->getType() 2992 << lex->getSourceRange() << rex->getSourceRange(); 2993} 2994 2995/// AnalyzeImplicitConversions - Find and report any interesting 2996/// implicit conversions in the given expression. There are a couple 2997/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2998void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) { 2999 QualType T = OrigE->getType(); 3000 Expr *E = OrigE->IgnoreParenImpCasts(); 3001 3002 // For conditional operators, we analyze the arguments as if they 3003 // were being fed directly into the output. 3004 if (isa<ConditionalOperator>(E)) { 3005 ConditionalOperator *CO = cast<ConditionalOperator>(E); 3006 CheckConditionalOperator(S, CO, T); 3007 return; 3008 } 3009 3010 // Go ahead and check any implicit conversions we might have skipped. 3011 // The non-canonical typecheck is just an optimization; 3012 // CheckImplicitConversion will filter out dead implicit conversions. 3013 if (E->getType() != T) 3014 CheckImplicitConversion(S, E, T, CC); 3015 3016 // Now continue drilling into this expression. 3017 3018 // Skip past explicit casts. 3019 if (isa<ExplicitCastExpr>(E)) { 3020 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 3021 return AnalyzeImplicitConversions(S, E, CC); 3022 } 3023 3024 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 3025 // Do a somewhat different check with comparison operators. 3026 if (BO->isComparisonOp()) 3027 return AnalyzeComparison(S, BO); 3028 3029 // And with assignments and compound assignments. 3030 if (BO->isAssignmentOp()) 3031 return AnalyzeAssignment(S, BO); 3032 } 3033 3034 // These break the otherwise-useful invariant below. Fortunately, 3035 // we don't really need to recurse into them, because any internal 3036 // expressions should have been analyzed already when they were 3037 // built into statements. 3038 if (isa<StmtExpr>(E)) return; 3039 3040 // Don't descend into unevaluated contexts. 3041 if (isa<SizeOfAlignOfExpr>(E)) return; 3042 3043 // Now just recurse over the expression's children. 3044 CC = E->getExprLoc(); 3045 for (Stmt::child_range I = E->children(); I; ++I) 3046 AnalyzeImplicitConversions(S, cast<Expr>(*I), CC); 3047} 3048 3049} // end anonymous namespace 3050 3051/// Diagnoses "dangerous" implicit conversions within the given 3052/// expression (which is a full expression). Implements -Wconversion 3053/// and -Wsign-compare. 3054/// 3055/// \param CC the "context" location of the implicit conversion, i.e. 3056/// the most location of the syntactic entity requiring the implicit 3057/// conversion 3058void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { 3059 // Don't diagnose in unevaluated contexts. 3060 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 3061 return; 3062 3063 // Don't diagnose for value- or type-dependent expressions. 3064 if (E->isTypeDependent() || E->isValueDependent()) 3065 return; 3066 3067 // This is not the right CC for (e.g.) a variable initialization. 3068 AnalyzeImplicitConversions(*this, E, CC); 3069} 3070 3071void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, 3072 FieldDecl *BitField, 3073 Expr *Init) { 3074 (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); 3075} 3076 3077/// CheckParmsForFunctionDef - Check that the parameters of the given 3078/// function are appropriate for the definition of a function. This 3079/// takes care of any checks that cannot be performed on the 3080/// declaration itself, e.g., that the types of each of the function 3081/// parameters are complete. 3082bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd, 3083 bool CheckParameterNames) { 3084 bool HasInvalidParm = false; 3085 for (; P != PEnd; ++P) { 3086 ParmVarDecl *Param = *P; 3087 3088 // C99 6.7.5.3p4: the parameters in a parameter type list in a 3089 // function declarator that is part of a function definition of 3090 // that function shall not have incomplete type. 3091 // 3092 // This is also C++ [dcl.fct]p6. 3093 if (!Param->isInvalidDecl() && 3094 RequireCompleteType(Param->getLocation(), Param->getType(), 3095 diag::err_typecheck_decl_incomplete_type)) { 3096 Param->setInvalidDecl(); 3097 HasInvalidParm = true; 3098 } 3099 3100 // C99 6.9.1p5: If the declarator includes a parameter type list, the 3101 // declaration of each parameter shall include an identifier. 3102 if (CheckParameterNames && 3103 Param->getIdentifier() == 0 && 3104 !Param->isImplicit() && 3105 !getLangOptions().CPlusPlus) 3106 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 3107 3108 // C99 6.7.5.3p12: 3109 // If the function declarator is not part of a definition of that 3110 // function, parameters may have incomplete type and may use the [*] 3111 // notation in their sequences of declarator specifiers to specify 3112 // variable length array types. 3113 QualType PType = Param->getOriginalType(); 3114 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 3115 if (AT->getSizeModifier() == ArrayType::Star) { 3116 // FIXME: This diagnosic should point the the '[*]' if source-location 3117 // information is added for it. 3118 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 3119 } 3120 } 3121 } 3122 3123 return HasInvalidParm; 3124} 3125 3126/// CheckCastAlign - Implements -Wcast-align, which warns when a 3127/// pointer cast increases the alignment requirements. 3128void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 3129 // This is actually a lot of work to potentially be doing on every 3130 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 3131 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, 3132 TRange.getBegin()) 3133 == Diagnostic::Ignored) 3134 return; 3135 3136 // Ignore dependent types. 3137 if (T->isDependentType() || Op->getType()->isDependentType()) 3138 return; 3139 3140 // Require that the destination be a pointer type. 3141 const PointerType *DestPtr = T->getAs<PointerType>(); 3142 if (!DestPtr) return; 3143 3144 // If the destination has alignment 1, we're done. 3145 QualType DestPointee = DestPtr->getPointeeType(); 3146 if (DestPointee->isIncompleteType()) return; 3147 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 3148 if (DestAlign.isOne()) return; 3149 3150 // Require that the source be a pointer type. 3151 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 3152 if (!SrcPtr) return; 3153 QualType SrcPointee = SrcPtr->getPointeeType(); 3154 3155 // Whitelist casts from cv void*. We already implicitly 3156 // whitelisted casts to cv void*, since they have alignment 1. 3157 // Also whitelist casts involving incomplete types, which implicitly 3158 // includes 'void'. 3159 if (SrcPointee->isIncompleteType()) return; 3160 3161 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 3162 if (SrcAlign >= DestAlign) return; 3163 3164 Diag(TRange.getBegin(), diag::warn_cast_align) 3165 << Op->getType() << T 3166 << static_cast<unsigned>(SrcAlign.getQuantity()) 3167 << static_cast<unsigned>(DestAlign.getQuantity()) 3168 << TRange << Op->getSourceRange(); 3169} 3170 3171static void CheckArrayAccess_Check(Sema &S, 3172 const clang::ArraySubscriptExpr *E) { 3173 const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts(); 3174 const ConstantArrayType *ArrayTy = 3175 S.Context.getAsConstantArrayType(BaseExpr->getType()); 3176 if (!ArrayTy) 3177 return; 3178 3179 const Expr *IndexExpr = E->getIdx(); 3180 if (IndexExpr->isValueDependent()) 3181 return; 3182 llvm::APSInt index; 3183 if (!IndexExpr->isIntegerConstantExpr(index, S.Context)) 3184 return; 3185 3186 if (index.isUnsigned() || !index.isNegative()) { 3187 llvm::APInt size = ArrayTy->getSize(); 3188 if (!size.isStrictlyPositive()) 3189 return; 3190 if (size.getBitWidth() > index.getBitWidth()) 3191 index = index.sext(size.getBitWidth()); 3192 else if (size.getBitWidth() < index.getBitWidth()) 3193 size = size.sext(index.getBitWidth()); 3194 3195 if (index.slt(size)) 3196 return; 3197 3198 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3199 S.PDiag(diag::warn_array_index_exceeds_bounds) 3200 << index.toString(10, true) 3201 << size.toString(10, true) 3202 << IndexExpr->getSourceRange()); 3203 } else { 3204 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3205 S.PDiag(diag::warn_array_index_precedes_bounds) 3206 << index.toString(10, true) 3207 << IndexExpr->getSourceRange()); 3208 } 3209 3210 const NamedDecl *ND = NULL; 3211 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 3212 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 3213 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 3214 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 3215 if (ND) 3216 S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr, 3217 S.PDiag(diag::note_array_index_out_of_bounds) 3218 << ND->getDeclName()); 3219} 3220 3221void Sema::CheckArrayAccess(const Expr *expr) { 3222 while (true) 3223 switch (expr->getStmtClass()) { 3224 case Stmt::ParenExprClass: 3225 expr = cast<ParenExpr>(expr)->getSubExpr(); 3226 continue; 3227 case Stmt::ArraySubscriptExprClass: 3228 CheckArrayAccess_Check(*this, cast<ArraySubscriptExpr>(expr)); 3229 return; 3230 case Stmt::ConditionalOperatorClass: { 3231 const ConditionalOperator *cond = cast<ConditionalOperator>(expr); 3232 if (const Expr *lhs = cond->getLHS()) 3233 CheckArrayAccess(lhs); 3234 if (const Expr *rhs = cond->getRHS()) 3235 CheckArrayAccess(rhs); 3236 return; 3237 } 3238 default: 3239 return; 3240 } 3241} 3242