SemaChecking.cpp revision db9e9e61f8311d8852bd15730f78e56f3ffa0508
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 if (Literal->containsNonAsciiOrNull()) { 556 llvm::StringRef String = Literal->getString(); 557 unsigned NumBytes = String.size(); 558 llvm::SmallVector<UTF16, 128> ToBuf(NumBytes); 559 const UTF8 *FromPtr = (UTF8 *)String.data(); 560 UTF16 *ToPtr = &ToBuf[0]; 561 562 ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, 563 &ToPtr, ToPtr + NumBytes, 564 strictConversion); 565 // Check for conversion failure. 566 if (Result != conversionOK) 567 Diag(Arg->getLocStart(), 568 diag::warn_cfstring_truncated) << Arg->getSourceRange(); 569 } 570 return false; 571} 572 573/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 574/// Emit an error and return true on failure, return false on success. 575bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 576 Expr *Fn = TheCall->getCallee(); 577 if (TheCall->getNumArgs() > 2) { 578 Diag(TheCall->getArg(2)->getLocStart(), 579 diag::err_typecheck_call_too_many_args) 580 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 581 << Fn->getSourceRange() 582 << SourceRange(TheCall->getArg(2)->getLocStart(), 583 (*(TheCall->arg_end()-1))->getLocEnd()); 584 return true; 585 } 586 587 if (TheCall->getNumArgs() < 2) { 588 return Diag(TheCall->getLocEnd(), 589 diag::err_typecheck_call_too_few_args_at_least) 590 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 591 } 592 593 // Determine whether the current function is variadic or not. 594 BlockScopeInfo *CurBlock = getCurBlock(); 595 bool isVariadic; 596 if (CurBlock) 597 isVariadic = CurBlock->TheDecl->isVariadic(); 598 else if (FunctionDecl *FD = getCurFunctionDecl()) 599 isVariadic = FD->isVariadic(); 600 else 601 isVariadic = getCurMethodDecl()->isVariadic(); 602 603 if (!isVariadic) { 604 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 605 return true; 606 } 607 608 // Verify that the second argument to the builtin is the last argument of the 609 // current function or method. 610 bool SecondArgIsLastNamedArgument = false; 611 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 612 613 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 614 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 615 // FIXME: This isn't correct for methods (results in bogus warning). 616 // Get the last formal in the current function. 617 const ParmVarDecl *LastArg; 618 if (CurBlock) 619 LastArg = *(CurBlock->TheDecl->param_end()-1); 620 else if (FunctionDecl *FD = getCurFunctionDecl()) 621 LastArg = *(FD->param_end()-1); 622 else 623 LastArg = *(getCurMethodDecl()->param_end()-1); 624 SecondArgIsLastNamedArgument = PV == LastArg; 625 } 626 } 627 628 if (!SecondArgIsLastNamedArgument) 629 Diag(TheCall->getArg(1)->getLocStart(), 630 diag::warn_second_parameter_of_va_start_not_last_named_argument); 631 return false; 632} 633 634/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 635/// friends. This is declared to take (...), so we have to check everything. 636bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 637 if (TheCall->getNumArgs() < 2) 638 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 639 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 640 if (TheCall->getNumArgs() > 2) 641 return Diag(TheCall->getArg(2)->getLocStart(), 642 diag::err_typecheck_call_too_many_args) 643 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 644 << SourceRange(TheCall->getArg(2)->getLocStart(), 645 (*(TheCall->arg_end()-1))->getLocEnd()); 646 647 Expr *OrigArg0 = TheCall->getArg(0); 648 Expr *OrigArg1 = TheCall->getArg(1); 649 650 // Do standard promotions between the two arguments, returning their common 651 // type. 652 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 653 654 // Make sure any conversions are pushed back into the call; this is 655 // type safe since unordered compare builtins are declared as "_Bool 656 // foo(...)". 657 TheCall->setArg(0, OrigArg0); 658 TheCall->setArg(1, OrigArg1); 659 660 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 661 return false; 662 663 // If the common type isn't a real floating type, then the arguments were 664 // invalid for this operation. 665 if (!Res->isRealFloatingType()) 666 return Diag(OrigArg0->getLocStart(), 667 diag::err_typecheck_call_invalid_ordered_compare) 668 << OrigArg0->getType() << OrigArg1->getType() 669 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 670 671 return false; 672} 673 674/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 675/// __builtin_isnan and friends. This is declared to take (...), so we have 676/// to check everything. We expect the last argument to be a floating point 677/// value. 678bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 679 if (TheCall->getNumArgs() < NumArgs) 680 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 681 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 682 if (TheCall->getNumArgs() > NumArgs) 683 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 684 diag::err_typecheck_call_too_many_args) 685 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 686 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 687 (*(TheCall->arg_end()-1))->getLocEnd()); 688 689 Expr *OrigArg = TheCall->getArg(NumArgs-1); 690 691 if (OrigArg->isTypeDependent()) 692 return false; 693 694 // This operation requires a non-_Complex floating-point number. 695 if (!OrigArg->getType()->isRealFloatingType()) 696 return Diag(OrigArg->getLocStart(), 697 diag::err_typecheck_call_invalid_unary_fp) 698 << OrigArg->getType() << OrigArg->getSourceRange(); 699 700 // If this is an implicit conversion from float -> double, remove it. 701 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 702 Expr *CastArg = Cast->getSubExpr(); 703 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 704 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 705 "promotion from float to double is the only expected cast here"); 706 Cast->setSubExpr(0); 707 TheCall->setArg(NumArgs-1, CastArg); 708 OrigArg = CastArg; 709 } 710 } 711 712 return false; 713} 714 715/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 716// This is declared to take (...), so we have to check everything. 717ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 718 if (TheCall->getNumArgs() < 2) 719 return ExprError(Diag(TheCall->getLocEnd(), 720 diag::err_typecheck_call_too_few_args_at_least) 721 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 722 << TheCall->getSourceRange()); 723 724 // Determine which of the following types of shufflevector we're checking: 725 // 1) unary, vector mask: (lhs, mask) 726 // 2) binary, vector mask: (lhs, rhs, mask) 727 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 728 QualType resType = TheCall->getArg(0)->getType(); 729 unsigned numElements = 0; 730 731 if (!TheCall->getArg(0)->isTypeDependent() && 732 !TheCall->getArg(1)->isTypeDependent()) { 733 QualType LHSType = TheCall->getArg(0)->getType(); 734 QualType RHSType = TheCall->getArg(1)->getType(); 735 736 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 737 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 738 << SourceRange(TheCall->getArg(0)->getLocStart(), 739 TheCall->getArg(1)->getLocEnd()); 740 return ExprError(); 741 } 742 743 numElements = LHSType->getAs<VectorType>()->getNumElements(); 744 unsigned numResElements = TheCall->getNumArgs() - 2; 745 746 // Check to see if we have a call with 2 vector arguments, the unary shuffle 747 // with mask. If so, verify that RHS is an integer vector type with the 748 // same number of elts as lhs. 749 if (TheCall->getNumArgs() == 2) { 750 if (!RHSType->hasIntegerRepresentation() || 751 RHSType->getAs<VectorType>()->getNumElements() != numElements) 752 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 753 << SourceRange(TheCall->getArg(1)->getLocStart(), 754 TheCall->getArg(1)->getLocEnd()); 755 numResElements = numElements; 756 } 757 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 758 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 759 << SourceRange(TheCall->getArg(0)->getLocStart(), 760 TheCall->getArg(1)->getLocEnd()); 761 return ExprError(); 762 } else if (numElements != numResElements) { 763 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 764 resType = Context.getVectorType(eltType, numResElements, 765 VectorType::GenericVector); 766 } 767 } 768 769 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 770 if (TheCall->getArg(i)->isTypeDependent() || 771 TheCall->getArg(i)->isValueDependent()) 772 continue; 773 774 llvm::APSInt Result(32); 775 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 776 return ExprError(Diag(TheCall->getLocStart(), 777 diag::err_shufflevector_nonconstant_argument) 778 << TheCall->getArg(i)->getSourceRange()); 779 780 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 781 return ExprError(Diag(TheCall->getLocStart(), 782 diag::err_shufflevector_argument_too_large) 783 << TheCall->getArg(i)->getSourceRange()); 784 } 785 786 llvm::SmallVector<Expr*, 32> exprs; 787 788 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 789 exprs.push_back(TheCall->getArg(i)); 790 TheCall->setArg(i, 0); 791 } 792 793 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 794 exprs.size(), resType, 795 TheCall->getCallee()->getLocStart(), 796 TheCall->getRParenLoc())); 797} 798 799/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 800// This is declared to take (const void*, ...) and can take two 801// optional constant int args. 802bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 803 unsigned NumArgs = TheCall->getNumArgs(); 804 805 if (NumArgs > 3) 806 return Diag(TheCall->getLocEnd(), 807 diag::err_typecheck_call_too_many_args_at_most) 808 << 0 /*function call*/ << 3 << NumArgs 809 << TheCall->getSourceRange(); 810 811 // Argument 0 is checked for us and the remaining arguments must be 812 // constant integers. 813 for (unsigned i = 1; i != NumArgs; ++i) { 814 Expr *Arg = TheCall->getArg(i); 815 816 llvm::APSInt Result; 817 if (SemaBuiltinConstantArg(TheCall, i, Result)) 818 return true; 819 820 // FIXME: gcc issues a warning and rewrites these to 0. These 821 // seems especially odd for the third argument since the default 822 // is 3. 823 if (i == 1) { 824 if (Result.getLimitedValue() > 1) 825 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 826 << "0" << "1" << Arg->getSourceRange(); 827 } else { 828 if (Result.getLimitedValue() > 3) 829 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 830 << "0" << "3" << Arg->getSourceRange(); 831 } 832 } 833 834 return false; 835} 836 837/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 838/// TheCall is a constant expression. 839bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 840 llvm::APSInt &Result) { 841 Expr *Arg = TheCall->getArg(ArgNum); 842 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 843 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 844 845 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 846 847 if (!Arg->isIntegerConstantExpr(Result, Context)) 848 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 849 << FDecl->getDeclName() << Arg->getSourceRange(); 850 851 return false; 852} 853 854/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 855/// int type). This simply type checks that type is one of the defined 856/// constants (0-3). 857// For compatability check 0-3, llvm only handles 0 and 2. 858bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 859 llvm::APSInt Result; 860 861 // Check constant-ness first. 862 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 863 return true; 864 865 Expr *Arg = TheCall->getArg(1); 866 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 867 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 868 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 869 } 870 871 return false; 872} 873 874/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 875/// This checks that val is a constant 1. 876bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 877 Expr *Arg = TheCall->getArg(1); 878 llvm::APSInt Result; 879 880 // TODO: This is less than ideal. Overload this to take a value. 881 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 882 return true; 883 884 if (Result != 1) 885 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 886 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 887 888 return false; 889} 890 891// Handle i > 1 ? "x" : "y", recursively. 892bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 893 bool HasVAListArg, 894 unsigned format_idx, unsigned firstDataArg, 895 bool isPrintf) { 896 tryAgain: 897 if (E->isTypeDependent() || E->isValueDependent()) 898 return false; 899 900 switch (E->getStmtClass()) { 901 case Stmt::BinaryConditionalOperatorClass: 902 case Stmt::ConditionalOperatorClass: { 903 const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); 904 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 905 format_idx, firstDataArg, isPrintf) 906 && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg, 907 format_idx, firstDataArg, isPrintf); 908 } 909 910 case Stmt::IntegerLiteralClass: 911 // Technically -Wformat-nonliteral does not warn about this case. 912 // The behavior of printf and friends in this case is implementation 913 // dependent. Ideally if the format string cannot be null then 914 // it should have a 'nonnull' attribute in the function prototype. 915 return true; 916 917 case Stmt::ImplicitCastExprClass: { 918 E = cast<ImplicitCastExpr>(E)->getSubExpr(); 919 goto tryAgain; 920 } 921 922 case Stmt::ParenExprClass: { 923 E = cast<ParenExpr>(E)->getSubExpr(); 924 goto tryAgain; 925 } 926 927 case Stmt::OpaqueValueExprClass: 928 if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { 929 E = src; 930 goto tryAgain; 931 } 932 return false; 933 934 case Stmt::PredefinedExprClass: 935 // While __func__, etc., are technically not string literals, they 936 // cannot contain format specifiers and thus are not a security 937 // liability. 938 return true; 939 940 case Stmt::DeclRefExprClass: { 941 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 942 943 // As an exception, do not flag errors for variables binding to 944 // const string literals. 945 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 946 bool isConstant = false; 947 QualType T = DR->getType(); 948 949 if (const ArrayType *AT = Context.getAsArrayType(T)) { 950 isConstant = AT->getElementType().isConstant(Context); 951 } else if (const PointerType *PT = T->getAs<PointerType>()) { 952 isConstant = T.isConstant(Context) && 953 PT->getPointeeType().isConstant(Context); 954 } 955 956 if (isConstant) { 957 if (const Expr *Init = VD->getAnyInitializer()) 958 return SemaCheckStringLiteral(Init, TheCall, 959 HasVAListArg, format_idx, firstDataArg, 960 isPrintf); 961 } 962 963 // For vprintf* functions (i.e., HasVAListArg==true), we add a 964 // special check to see if the format string is a function parameter 965 // of the function calling the printf function. If the function 966 // has an attribute indicating it is a printf-like function, then we 967 // should suppress warnings concerning non-literals being used in a call 968 // to a vprintf function. For example: 969 // 970 // void 971 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 972 // va_list ap; 973 // va_start(ap, fmt); 974 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 975 // ... 976 // 977 // 978 // FIXME: We don't have full attribute support yet, so just check to see 979 // if the argument is a DeclRefExpr that references a parameter. We'll 980 // add proper support for checking the attribute later. 981 if (HasVAListArg) 982 if (isa<ParmVarDecl>(VD)) 983 return true; 984 } 985 986 return false; 987 } 988 989 case Stmt::CallExprClass: { 990 const CallExpr *CE = cast<CallExpr>(E); 991 if (const ImplicitCastExpr *ICE 992 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 993 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 994 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 995 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 996 unsigned ArgIndex = FA->getFormatIdx(); 997 const Expr *Arg = CE->getArg(ArgIndex - 1); 998 999 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1000 format_idx, firstDataArg, isPrintf); 1001 } 1002 } 1003 } 1004 } 1005 1006 return false; 1007 } 1008 case Stmt::ObjCStringLiteralClass: 1009 case Stmt::StringLiteralClass: { 1010 const StringLiteral *StrE = NULL; 1011 1012 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1013 StrE = ObjCFExpr->getString(); 1014 else 1015 StrE = cast<StringLiteral>(E); 1016 1017 if (StrE) { 1018 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1019 firstDataArg, isPrintf); 1020 return true; 1021 } 1022 1023 return false; 1024 } 1025 1026 default: 1027 return false; 1028 } 1029} 1030 1031void 1032Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1033 const CallExpr *TheCall) { 1034 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1035 e = NonNull->args_end(); 1036 i != e; ++i) { 1037 const Expr *ArgExpr = TheCall->getArg(*i); 1038 if (ArgExpr->isNullPointerConstant(Context, 1039 Expr::NPC_ValueDependentIsNotNull)) 1040 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1041 << ArgExpr->getSourceRange(); 1042 } 1043} 1044 1045/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1046/// functions) for correct use of format strings. 1047void 1048Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1049 unsigned format_idx, unsigned firstDataArg, 1050 bool isPrintf) { 1051 1052 const Expr *Fn = TheCall->getCallee(); 1053 1054 // The way the format attribute works in GCC, the implicit this argument 1055 // of member functions is counted. However, it doesn't appear in our own 1056 // lists, so decrement format_idx in that case. 1057 if (isa<CXXMemberCallExpr>(TheCall)) { 1058 const CXXMethodDecl *method_decl = 1059 dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl()); 1060 if (method_decl && method_decl->isInstance()) { 1061 // Catch a format attribute mistakenly referring to the object argument. 1062 if (format_idx == 0) 1063 return; 1064 --format_idx; 1065 if(firstDataArg != 0) 1066 --firstDataArg; 1067 } 1068 } 1069 1070 // CHECK: printf/scanf-like function is called with no format string. 1071 if (format_idx >= TheCall->getNumArgs()) { 1072 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1073 << Fn->getSourceRange(); 1074 return; 1075 } 1076 1077 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1078 1079 // CHECK: format string is not a string literal. 1080 // 1081 // Dynamically generated format strings are difficult to 1082 // automatically vet at compile time. Requiring that format strings 1083 // are string literals: (1) permits the checking of format strings by 1084 // the compiler and thereby (2) can practically remove the source of 1085 // many format string exploits. 1086 1087 // Format string can be either ObjC string (e.g. @"%d") or 1088 // C string (e.g. "%d") 1089 // ObjC string uses the same format specifiers as C string, so we can use 1090 // the same format string checking logic for both ObjC and C strings. 1091 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1092 firstDataArg, isPrintf)) 1093 return; // Literal format string found, check done! 1094 1095 // If there are no arguments specified, warn with -Wformat-security, otherwise 1096 // warn only with -Wformat-nonliteral. 1097 if (TheCall->getNumArgs() == format_idx+1) 1098 Diag(TheCall->getArg(format_idx)->getLocStart(), 1099 diag::warn_format_nonliteral_noargs) 1100 << OrigFormatExpr->getSourceRange(); 1101 else 1102 Diag(TheCall->getArg(format_idx)->getLocStart(), 1103 diag::warn_format_nonliteral) 1104 << OrigFormatExpr->getSourceRange(); 1105} 1106 1107namespace { 1108class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1109protected: 1110 Sema &S; 1111 const StringLiteral *FExpr; 1112 const Expr *OrigFormatExpr; 1113 const unsigned FirstDataArg; 1114 const unsigned NumDataArgs; 1115 const bool IsObjCLiteral; 1116 const char *Beg; // Start of format string. 1117 const bool HasVAListArg; 1118 const CallExpr *TheCall; 1119 unsigned FormatIdx; 1120 llvm::BitVector CoveredArgs; 1121 bool usesPositionalArgs; 1122 bool atFirstArg; 1123public: 1124 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1125 const Expr *origFormatExpr, unsigned firstDataArg, 1126 unsigned numDataArgs, bool isObjCLiteral, 1127 const char *beg, bool hasVAListArg, 1128 const CallExpr *theCall, unsigned formatIdx) 1129 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1130 FirstDataArg(firstDataArg), 1131 NumDataArgs(numDataArgs), 1132 IsObjCLiteral(isObjCLiteral), Beg(beg), 1133 HasVAListArg(hasVAListArg), 1134 TheCall(theCall), FormatIdx(formatIdx), 1135 usesPositionalArgs(false), atFirstArg(true) { 1136 CoveredArgs.resize(numDataArgs); 1137 CoveredArgs.reset(); 1138 } 1139 1140 void DoneProcessing(); 1141 1142 void HandleIncompleteSpecifier(const char *startSpecifier, 1143 unsigned specifierLen); 1144 1145 virtual void HandleInvalidPosition(const char *startSpecifier, 1146 unsigned specifierLen, 1147 analyze_format_string::PositionContext p); 1148 1149 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1150 1151 void HandleNullChar(const char *nullCharacter); 1152 1153protected: 1154 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1155 const char *startSpec, 1156 unsigned specifierLen, 1157 const char *csStart, unsigned csLen); 1158 1159 SourceRange getFormatStringRange(); 1160 CharSourceRange getSpecifierRange(const char *startSpecifier, 1161 unsigned specifierLen); 1162 SourceLocation getLocationOfByte(const char *x); 1163 1164 const Expr *getDataArg(unsigned i) const; 1165 1166 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1167 const analyze_format_string::ConversionSpecifier &CS, 1168 const char *startSpecifier, unsigned specifierLen, 1169 unsigned argIndex); 1170}; 1171} 1172 1173SourceRange CheckFormatHandler::getFormatStringRange() { 1174 return OrigFormatExpr->getSourceRange(); 1175} 1176 1177CharSourceRange CheckFormatHandler:: 1178getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1179 SourceLocation Start = getLocationOfByte(startSpecifier); 1180 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1181 1182 // Advance the end SourceLocation by one due to half-open ranges. 1183 End = End.getFileLocWithOffset(1); 1184 1185 return CharSourceRange::getCharRange(Start, End); 1186} 1187 1188SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1189 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1190} 1191 1192void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1193 unsigned specifierLen){ 1194 SourceLocation Loc = getLocationOfByte(startSpecifier); 1195 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1196 << getSpecifierRange(startSpecifier, specifierLen); 1197} 1198 1199void 1200CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1201 analyze_format_string::PositionContext p) { 1202 SourceLocation Loc = getLocationOfByte(startPos); 1203 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1204 << (unsigned) p << getSpecifierRange(startPos, posLen); 1205} 1206 1207void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1208 unsigned posLen) { 1209 SourceLocation Loc = getLocationOfByte(startPos); 1210 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1211 << getSpecifierRange(startPos, posLen); 1212} 1213 1214void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1215 if (!IsObjCLiteral) { 1216 // The presence of a null character is likely an error. 1217 S.Diag(getLocationOfByte(nullCharacter), 1218 diag::warn_printf_format_string_contains_null_char) 1219 << getFormatStringRange(); 1220 } 1221} 1222 1223const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1224 return TheCall->getArg(FirstDataArg + i); 1225} 1226 1227void CheckFormatHandler::DoneProcessing() { 1228 // Does the number of data arguments exceed the number of 1229 // format conversions in the format string? 1230 if (!HasVAListArg) { 1231 // Find any arguments that weren't covered. 1232 CoveredArgs.flip(); 1233 signed notCoveredArg = CoveredArgs.find_first(); 1234 if (notCoveredArg >= 0) { 1235 assert((unsigned)notCoveredArg < NumDataArgs); 1236 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1237 diag::warn_printf_data_arg_not_used) 1238 << getFormatStringRange(); 1239 } 1240 } 1241} 1242 1243bool 1244CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1245 SourceLocation Loc, 1246 const char *startSpec, 1247 unsigned specifierLen, 1248 const char *csStart, 1249 unsigned csLen) { 1250 1251 bool keepGoing = true; 1252 if (argIndex < NumDataArgs) { 1253 // Consider the argument coverered, even though the specifier doesn't 1254 // make sense. 1255 CoveredArgs.set(argIndex); 1256 } 1257 else { 1258 // If argIndex exceeds the number of data arguments we 1259 // don't issue a warning because that is just a cascade of warnings (and 1260 // they may have intended '%%' anyway). We don't want to continue processing 1261 // the format string after this point, however, as we will like just get 1262 // gibberish when trying to match arguments. 1263 keepGoing = false; 1264 } 1265 1266 S.Diag(Loc, diag::warn_format_invalid_conversion) 1267 << llvm::StringRef(csStart, csLen) 1268 << getSpecifierRange(startSpec, specifierLen); 1269 1270 return keepGoing; 1271} 1272 1273bool 1274CheckFormatHandler::CheckNumArgs( 1275 const analyze_format_string::FormatSpecifier &FS, 1276 const analyze_format_string::ConversionSpecifier &CS, 1277 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1278 1279 if (argIndex >= NumDataArgs) { 1280 if (FS.usesPositionalArg()) { 1281 S.Diag(getLocationOfByte(CS.getStart()), 1282 diag::warn_printf_positional_arg_exceeds_data_args) 1283 << (argIndex+1) << NumDataArgs 1284 << getSpecifierRange(startSpecifier, specifierLen); 1285 } 1286 else { 1287 S.Diag(getLocationOfByte(CS.getStart()), 1288 diag::warn_printf_insufficient_data_args) 1289 << getSpecifierRange(startSpecifier, specifierLen); 1290 } 1291 1292 return false; 1293 } 1294 return true; 1295} 1296 1297//===--- CHECK: Printf format string checking ------------------------------===// 1298 1299namespace { 1300class CheckPrintfHandler : public CheckFormatHandler { 1301public: 1302 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1303 const Expr *origFormatExpr, unsigned firstDataArg, 1304 unsigned numDataArgs, bool isObjCLiteral, 1305 const char *beg, bool hasVAListArg, 1306 const CallExpr *theCall, unsigned formatIdx) 1307 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1308 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1309 theCall, formatIdx) {} 1310 1311 1312 bool HandleInvalidPrintfConversionSpecifier( 1313 const analyze_printf::PrintfSpecifier &FS, 1314 const char *startSpecifier, 1315 unsigned specifierLen); 1316 1317 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1318 const char *startSpecifier, 1319 unsigned specifierLen); 1320 1321 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1322 const char *startSpecifier, unsigned specifierLen); 1323 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1324 const analyze_printf::OptionalAmount &Amt, 1325 unsigned type, 1326 const char *startSpecifier, unsigned specifierLen); 1327 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1328 const analyze_printf::OptionalFlag &flag, 1329 const char *startSpecifier, unsigned specifierLen); 1330 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1331 const analyze_printf::OptionalFlag &ignoredFlag, 1332 const analyze_printf::OptionalFlag &flag, 1333 const char *startSpecifier, unsigned specifierLen); 1334}; 1335} 1336 1337bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1338 const analyze_printf::PrintfSpecifier &FS, 1339 const char *startSpecifier, 1340 unsigned specifierLen) { 1341 const analyze_printf::PrintfConversionSpecifier &CS = 1342 FS.getConversionSpecifier(); 1343 1344 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1345 getLocationOfByte(CS.getStart()), 1346 startSpecifier, specifierLen, 1347 CS.getStart(), CS.getLength()); 1348} 1349 1350bool CheckPrintfHandler::HandleAmount( 1351 const analyze_format_string::OptionalAmount &Amt, 1352 unsigned k, const char *startSpecifier, 1353 unsigned specifierLen) { 1354 1355 if (Amt.hasDataArgument()) { 1356 if (!HasVAListArg) { 1357 unsigned argIndex = Amt.getArgIndex(); 1358 if (argIndex >= NumDataArgs) { 1359 S.Diag(getLocationOfByte(Amt.getStart()), 1360 diag::warn_printf_asterisk_missing_arg) 1361 << k << getSpecifierRange(startSpecifier, specifierLen); 1362 // Don't do any more checking. We will just emit 1363 // spurious errors. 1364 return false; 1365 } 1366 1367 // Type check the data argument. It should be an 'int'. 1368 // Although not in conformance with C99, we also allow the argument to be 1369 // an 'unsigned int' as that is a reasonably safe case. GCC also 1370 // doesn't emit a warning for that case. 1371 CoveredArgs.set(argIndex); 1372 const Expr *Arg = getDataArg(argIndex); 1373 QualType T = Arg->getType(); 1374 1375 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1376 assert(ATR.isValid()); 1377 1378 if (!ATR.matchesType(S.Context, T)) { 1379 S.Diag(getLocationOfByte(Amt.getStart()), 1380 diag::warn_printf_asterisk_wrong_type) 1381 << k 1382 << ATR.getRepresentativeType(S.Context) << T 1383 << getSpecifierRange(startSpecifier, specifierLen) 1384 << Arg->getSourceRange(); 1385 // Don't do any more checking. We will just emit 1386 // spurious errors. 1387 return false; 1388 } 1389 } 1390 } 1391 return true; 1392} 1393 1394void CheckPrintfHandler::HandleInvalidAmount( 1395 const analyze_printf::PrintfSpecifier &FS, 1396 const analyze_printf::OptionalAmount &Amt, 1397 unsigned type, 1398 const char *startSpecifier, 1399 unsigned specifierLen) { 1400 const analyze_printf::PrintfConversionSpecifier &CS = 1401 FS.getConversionSpecifier(); 1402 switch (Amt.getHowSpecified()) { 1403 case analyze_printf::OptionalAmount::Constant: 1404 S.Diag(getLocationOfByte(Amt.getStart()), 1405 diag::warn_printf_nonsensical_optional_amount) 1406 << type 1407 << CS.toString() 1408 << getSpecifierRange(startSpecifier, specifierLen) 1409 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1410 Amt.getConstantLength())); 1411 break; 1412 1413 default: 1414 S.Diag(getLocationOfByte(Amt.getStart()), 1415 diag::warn_printf_nonsensical_optional_amount) 1416 << type 1417 << CS.toString() 1418 << getSpecifierRange(startSpecifier, specifierLen); 1419 break; 1420 } 1421} 1422 1423void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1424 const analyze_printf::OptionalFlag &flag, 1425 const char *startSpecifier, 1426 unsigned specifierLen) { 1427 // Warn about pointless flag with a fixit removal. 1428 const analyze_printf::PrintfConversionSpecifier &CS = 1429 FS.getConversionSpecifier(); 1430 S.Diag(getLocationOfByte(flag.getPosition()), 1431 diag::warn_printf_nonsensical_flag) 1432 << flag.toString() << CS.toString() 1433 << getSpecifierRange(startSpecifier, specifierLen) 1434 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1435} 1436 1437void CheckPrintfHandler::HandleIgnoredFlag( 1438 const analyze_printf::PrintfSpecifier &FS, 1439 const analyze_printf::OptionalFlag &ignoredFlag, 1440 const analyze_printf::OptionalFlag &flag, 1441 const char *startSpecifier, 1442 unsigned specifierLen) { 1443 // Warn about ignored flag with a fixit removal. 1444 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1445 diag::warn_printf_ignored_flag) 1446 << ignoredFlag.toString() << flag.toString() 1447 << getSpecifierRange(startSpecifier, specifierLen) 1448 << FixItHint::CreateRemoval(getSpecifierRange( 1449 ignoredFlag.getPosition(), 1)); 1450} 1451 1452bool 1453CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1454 &FS, 1455 const char *startSpecifier, 1456 unsigned specifierLen) { 1457 1458 using namespace analyze_format_string; 1459 using namespace analyze_printf; 1460 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1461 1462 if (FS.consumesDataArgument()) { 1463 if (atFirstArg) { 1464 atFirstArg = false; 1465 usesPositionalArgs = FS.usesPositionalArg(); 1466 } 1467 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1468 // Cannot mix-and-match positional and non-positional arguments. 1469 S.Diag(getLocationOfByte(CS.getStart()), 1470 diag::warn_format_mix_positional_nonpositional_args) 1471 << getSpecifierRange(startSpecifier, specifierLen); 1472 return false; 1473 } 1474 } 1475 1476 // First check if the field width, precision, and conversion specifier 1477 // have matching data arguments. 1478 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1479 startSpecifier, specifierLen)) { 1480 return false; 1481 } 1482 1483 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1484 startSpecifier, specifierLen)) { 1485 return false; 1486 } 1487 1488 if (!CS.consumesDataArgument()) { 1489 // FIXME: Technically specifying a precision or field width here 1490 // makes no sense. Worth issuing a warning at some point. 1491 return true; 1492 } 1493 1494 // Consume the argument. 1495 unsigned argIndex = FS.getArgIndex(); 1496 if (argIndex < NumDataArgs) { 1497 // The check to see if the argIndex is valid will come later. 1498 // We set the bit here because we may exit early from this 1499 // function if we encounter some other error. 1500 CoveredArgs.set(argIndex); 1501 } 1502 1503 // Check for using an Objective-C specific conversion specifier 1504 // in a non-ObjC literal. 1505 if (!IsObjCLiteral && CS.isObjCArg()) { 1506 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1507 specifierLen); 1508 } 1509 1510 // Check for invalid use of field width 1511 if (!FS.hasValidFieldWidth()) { 1512 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1513 startSpecifier, specifierLen); 1514 } 1515 1516 // Check for invalid use of precision 1517 if (!FS.hasValidPrecision()) { 1518 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1519 startSpecifier, specifierLen); 1520 } 1521 1522 // Check each flag does not conflict with any other component. 1523 if (!FS.hasValidThousandsGroupingPrefix()) 1524 HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); 1525 if (!FS.hasValidLeadingZeros()) 1526 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1527 if (!FS.hasValidPlusPrefix()) 1528 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1529 if (!FS.hasValidSpacePrefix()) 1530 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1531 if (!FS.hasValidAlternativeForm()) 1532 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1533 if (!FS.hasValidLeftJustified()) 1534 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1535 1536 // Check that flags are not ignored by another flag 1537 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1538 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1539 startSpecifier, specifierLen); 1540 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1541 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1542 startSpecifier, specifierLen); 1543 1544 // Check the length modifier is valid with the given conversion specifier. 1545 const LengthModifier &LM = FS.getLengthModifier(); 1546 if (!FS.hasValidLengthModifier()) 1547 S.Diag(getLocationOfByte(LM.getStart()), 1548 diag::warn_format_nonsensical_length) 1549 << LM.toString() << CS.toString() 1550 << getSpecifierRange(startSpecifier, specifierLen) 1551 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1552 LM.getLength())); 1553 1554 // Are we using '%n'? 1555 if (CS.getKind() == ConversionSpecifier::nArg) { 1556 // Issue a warning about this being a possible security issue. 1557 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1558 << getSpecifierRange(startSpecifier, specifierLen); 1559 // Continue checking the other format specifiers. 1560 return true; 1561 } 1562 1563 // The remaining checks depend on the data arguments. 1564 if (HasVAListArg) 1565 return true; 1566 1567 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1568 return false; 1569 1570 // Now type check the data expression that matches the 1571 // format specifier. 1572 const Expr *Ex = getDataArg(argIndex); 1573 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1574 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1575 // Check if we didn't match because of an implicit cast from a 'char' 1576 // or 'short' to an 'int'. This is done because printf is a varargs 1577 // function. 1578 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1579 if (ICE->getType() == S.Context.IntTy) { 1580 // All further checking is done on the subexpression. 1581 Ex = ICE->getSubExpr(); 1582 if (ATR.matchesType(S.Context, Ex->getType())) 1583 return true; 1584 } 1585 1586 // We may be able to offer a FixItHint if it is a supported type. 1587 PrintfSpecifier fixedFS = FS; 1588 bool success = fixedFS.fixType(Ex->getType()); 1589 1590 if (success) { 1591 // Get the fix string from the fixed format specifier 1592 llvm::SmallString<128> buf; 1593 llvm::raw_svector_ostream os(buf); 1594 fixedFS.toString(os); 1595 1596 // FIXME: getRepresentativeType() perhaps should return a string 1597 // instead of a QualType to better handle when the representative 1598 // type is 'wint_t' (which is defined in the system headers). 1599 S.Diag(getLocationOfByte(CS.getStart()), 1600 diag::warn_printf_conversion_argument_type_mismatch) 1601 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1602 << getSpecifierRange(startSpecifier, specifierLen) 1603 << Ex->getSourceRange() 1604 << FixItHint::CreateReplacement( 1605 getSpecifierRange(startSpecifier, specifierLen), 1606 os.str()); 1607 } 1608 else { 1609 S.Diag(getLocationOfByte(CS.getStart()), 1610 diag::warn_printf_conversion_argument_type_mismatch) 1611 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1612 << getSpecifierRange(startSpecifier, specifierLen) 1613 << Ex->getSourceRange(); 1614 } 1615 } 1616 1617 return true; 1618} 1619 1620//===--- CHECK: Scanf format string checking ------------------------------===// 1621 1622namespace { 1623class CheckScanfHandler : public CheckFormatHandler { 1624public: 1625 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1626 const Expr *origFormatExpr, unsigned firstDataArg, 1627 unsigned numDataArgs, bool isObjCLiteral, 1628 const char *beg, bool hasVAListArg, 1629 const CallExpr *theCall, unsigned formatIdx) 1630 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1631 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1632 theCall, formatIdx) {} 1633 1634 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1635 const char *startSpecifier, 1636 unsigned specifierLen); 1637 1638 bool HandleInvalidScanfConversionSpecifier( 1639 const analyze_scanf::ScanfSpecifier &FS, 1640 const char *startSpecifier, 1641 unsigned specifierLen); 1642 1643 void HandleIncompleteScanList(const char *start, const char *end); 1644}; 1645} 1646 1647void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1648 const char *end) { 1649 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1650 << getSpecifierRange(start, end - start); 1651} 1652 1653bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1654 const analyze_scanf::ScanfSpecifier &FS, 1655 const char *startSpecifier, 1656 unsigned specifierLen) { 1657 1658 const analyze_scanf::ScanfConversionSpecifier &CS = 1659 FS.getConversionSpecifier(); 1660 1661 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1662 getLocationOfByte(CS.getStart()), 1663 startSpecifier, specifierLen, 1664 CS.getStart(), CS.getLength()); 1665} 1666 1667bool CheckScanfHandler::HandleScanfSpecifier( 1668 const analyze_scanf::ScanfSpecifier &FS, 1669 const char *startSpecifier, 1670 unsigned specifierLen) { 1671 1672 using namespace analyze_scanf; 1673 using namespace analyze_format_string; 1674 1675 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1676 1677 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1678 // be used to decide if we are using positional arguments consistently. 1679 if (FS.consumesDataArgument()) { 1680 if (atFirstArg) { 1681 atFirstArg = false; 1682 usesPositionalArgs = FS.usesPositionalArg(); 1683 } 1684 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1685 // Cannot mix-and-match positional and non-positional arguments. 1686 S.Diag(getLocationOfByte(CS.getStart()), 1687 diag::warn_format_mix_positional_nonpositional_args) 1688 << getSpecifierRange(startSpecifier, specifierLen); 1689 return false; 1690 } 1691 } 1692 1693 // Check if the field with is non-zero. 1694 const OptionalAmount &Amt = FS.getFieldWidth(); 1695 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1696 if (Amt.getConstantAmount() == 0) { 1697 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1698 Amt.getConstantLength()); 1699 S.Diag(getLocationOfByte(Amt.getStart()), 1700 diag::warn_scanf_nonzero_width) 1701 << R << FixItHint::CreateRemoval(R); 1702 } 1703 } 1704 1705 if (!FS.consumesDataArgument()) { 1706 // FIXME: Technically specifying a precision or field width here 1707 // makes no sense. Worth issuing a warning at some point. 1708 return true; 1709 } 1710 1711 // Consume the argument. 1712 unsigned argIndex = FS.getArgIndex(); 1713 if (argIndex < NumDataArgs) { 1714 // The check to see if the argIndex is valid will come later. 1715 // We set the bit here because we may exit early from this 1716 // function if we encounter some other error. 1717 CoveredArgs.set(argIndex); 1718 } 1719 1720 // Check the length modifier is valid with the given conversion specifier. 1721 const LengthModifier &LM = FS.getLengthModifier(); 1722 if (!FS.hasValidLengthModifier()) { 1723 S.Diag(getLocationOfByte(LM.getStart()), 1724 diag::warn_format_nonsensical_length) 1725 << LM.toString() << CS.toString() 1726 << getSpecifierRange(startSpecifier, specifierLen) 1727 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1728 LM.getLength())); 1729 } 1730 1731 // The remaining checks depend on the data arguments. 1732 if (HasVAListArg) 1733 return true; 1734 1735 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1736 return false; 1737 1738 // FIXME: Check that the argument type matches the format specifier. 1739 1740 return true; 1741} 1742 1743void Sema::CheckFormatString(const StringLiteral *FExpr, 1744 const Expr *OrigFormatExpr, 1745 const CallExpr *TheCall, bool HasVAListArg, 1746 unsigned format_idx, unsigned firstDataArg, 1747 bool isPrintf) { 1748 1749 // CHECK: is the format string a wide literal? 1750 if (FExpr->isWide()) { 1751 Diag(FExpr->getLocStart(), 1752 diag::warn_format_string_is_wide_literal) 1753 << OrigFormatExpr->getSourceRange(); 1754 return; 1755 } 1756 1757 // Str - The format string. NOTE: this is NOT null-terminated! 1758 llvm::StringRef StrRef = FExpr->getString(); 1759 const char *Str = StrRef.data(); 1760 unsigned StrLen = StrRef.size(); 1761 1762 // CHECK: empty format string? 1763 if (StrLen == 0) { 1764 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1765 << OrigFormatExpr->getSourceRange(); 1766 return; 1767 } 1768 1769 if (isPrintf) { 1770 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1771 TheCall->getNumArgs() - firstDataArg, 1772 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1773 HasVAListArg, TheCall, format_idx); 1774 1775 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1776 H.DoneProcessing(); 1777 } 1778 else { 1779 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1780 TheCall->getNumArgs() - firstDataArg, 1781 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1782 HasVAListArg, TheCall, format_idx); 1783 1784 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1785 H.DoneProcessing(); 1786 } 1787} 1788 1789//===--- CHECK: Return Address of Stack Variable --------------------------===// 1790 1791static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1792static Expr *EvalAddr(Expr* E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); 1793 1794/// CheckReturnStackAddr - Check if a return statement returns the address 1795/// of a stack variable. 1796void 1797Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1798 SourceLocation ReturnLoc) { 1799 1800 Expr *stackE = 0; 1801 llvm::SmallVector<DeclRefExpr *, 8> refVars; 1802 1803 // Perform checking for returned stack addresses, local blocks, 1804 // label addresses or references to temporaries. 1805 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1806 stackE = EvalAddr(RetValExp, refVars); 1807 } else if (lhsType->isReferenceType()) { 1808 stackE = EvalVal(RetValExp, refVars); 1809 } 1810 1811 if (stackE == 0) 1812 return; // Nothing suspicious was found. 1813 1814 SourceLocation diagLoc; 1815 SourceRange diagRange; 1816 if (refVars.empty()) { 1817 diagLoc = stackE->getLocStart(); 1818 diagRange = stackE->getSourceRange(); 1819 } else { 1820 // We followed through a reference variable. 'stackE' contains the 1821 // problematic expression but we will warn at the return statement pointing 1822 // at the reference variable. We will later display the "trail" of 1823 // reference variables using notes. 1824 diagLoc = refVars[0]->getLocStart(); 1825 diagRange = refVars[0]->getSourceRange(); 1826 } 1827 1828 if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. 1829 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref 1830 : diag::warn_ret_stack_addr) 1831 << DR->getDecl()->getDeclName() << diagRange; 1832 } else if (isa<BlockExpr>(stackE)) { // local block. 1833 Diag(diagLoc, diag::err_ret_local_block) << diagRange; 1834 } else if (isa<AddrLabelExpr>(stackE)) { // address of label. 1835 Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; 1836 } else { // local temporary. 1837 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref 1838 : diag::warn_ret_local_temp_addr) 1839 << diagRange; 1840 } 1841 1842 // Display the "trail" of reference variables that we followed until we 1843 // found the problematic expression using notes. 1844 for (unsigned i = 0, e = refVars.size(); i != e; ++i) { 1845 VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); 1846 // If this var binds to another reference var, show the range of the next 1847 // var, otherwise the var binds to the problematic expression, in which case 1848 // show the range of the expression. 1849 SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() 1850 : stackE->getSourceRange(); 1851 Diag(VD->getLocation(), diag::note_ref_var_local_bind) 1852 << VD->getDeclName() << range; 1853 } 1854} 1855 1856/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1857/// check if the expression in a return statement evaluates to an address 1858/// to a location on the stack, a local block, an address of a label, or a 1859/// reference to local temporary. The recursion is used to traverse the 1860/// AST of the return expression, with recursion backtracking when we 1861/// encounter a subexpression that (1) clearly does not lead to one of the 1862/// above problematic expressions (2) is something we cannot determine leads to 1863/// a problematic expression based on such local checking. 1864/// 1865/// Both EvalAddr and EvalVal follow through reference variables to evaluate 1866/// the expression that they point to. Such variables are added to the 1867/// 'refVars' vector so that we know what the reference variable "trail" was. 1868/// 1869/// EvalAddr processes expressions that are pointers that are used as 1870/// references (and not L-values). EvalVal handles all other values. 1871/// At the base case of the recursion is a check for the above problematic 1872/// expressions. 1873/// 1874/// This implementation handles: 1875/// 1876/// * pointer-to-pointer casts 1877/// * implicit conversions from array references to pointers 1878/// * taking the address of fields 1879/// * arbitrary interplay between "&" and "*" operators 1880/// * pointer arithmetic from an address of a stack variable 1881/// * taking the address of an array element where the array is on the stack 1882static Expr *EvalAddr(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 1883 if (E->isTypeDependent()) 1884 return NULL; 1885 1886 // We should only be called for evaluating pointer expressions. 1887 assert((E->getType()->isAnyPointerType() || 1888 E->getType()->isBlockPointerType() || 1889 E->getType()->isObjCQualifiedIdType()) && 1890 "EvalAddr only works on pointers"); 1891 1892 // Our "symbolic interpreter" is just a dispatch off the currently 1893 // viewed AST node. We then recursively traverse the AST by calling 1894 // EvalAddr and EvalVal appropriately. 1895 switch (E->getStmtClass()) { 1896 case Stmt::ParenExprClass: 1897 // Ignore parentheses. 1898 return EvalAddr(cast<ParenExpr>(E)->getSubExpr(), refVars); 1899 1900 case Stmt::DeclRefExprClass: { 1901 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1902 1903 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1904 // If this is a reference variable, follow through to the expression that 1905 // it points to. 1906 if (V->hasLocalStorage() && 1907 V->getType()->isReferenceType() && V->hasInit()) { 1908 // Add the reference variable to the "trail". 1909 refVars.push_back(DR); 1910 return EvalAddr(V->getInit(), refVars); 1911 } 1912 1913 return NULL; 1914 } 1915 1916 case Stmt::UnaryOperatorClass: { 1917 // The only unary operator that make sense to handle here 1918 // is AddrOf. All others don't make sense as pointers. 1919 UnaryOperator *U = cast<UnaryOperator>(E); 1920 1921 if (U->getOpcode() == UO_AddrOf) 1922 return EvalVal(U->getSubExpr(), refVars); 1923 else 1924 return NULL; 1925 } 1926 1927 case Stmt::BinaryOperatorClass: { 1928 // Handle pointer arithmetic. All other binary operators are not valid 1929 // in this context. 1930 BinaryOperator *B = cast<BinaryOperator>(E); 1931 BinaryOperatorKind op = B->getOpcode(); 1932 1933 if (op != BO_Add && op != BO_Sub) 1934 return NULL; 1935 1936 Expr *Base = B->getLHS(); 1937 1938 // Determine which argument is the real pointer base. It could be 1939 // the RHS argument instead of the LHS. 1940 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1941 1942 assert (Base->getType()->isPointerType()); 1943 return EvalAddr(Base, refVars); 1944 } 1945 1946 // For conditional operators we need to see if either the LHS or RHS are 1947 // valid DeclRefExpr*s. If one of them is valid, we return it. 1948 case Stmt::ConditionalOperatorClass: { 1949 ConditionalOperator *C = cast<ConditionalOperator>(E); 1950 1951 // Handle the GNU extension for missing LHS. 1952 if (Expr *lhsExpr = C->getLHS()) { 1953 // In C++, we can have a throw-expression, which has 'void' type. 1954 if (!lhsExpr->getType()->isVoidType()) 1955 if (Expr* LHS = EvalAddr(lhsExpr, refVars)) 1956 return LHS; 1957 } 1958 1959 // In C++, we can have a throw-expression, which has 'void' type. 1960 if (C->getRHS()->getType()->isVoidType()) 1961 return NULL; 1962 1963 return EvalAddr(C->getRHS(), refVars); 1964 } 1965 1966 case Stmt::BlockExprClass: 1967 if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) 1968 return E; // local block. 1969 return NULL; 1970 1971 case Stmt::AddrLabelExprClass: 1972 return E; // address of label. 1973 1974 // For casts, we need to handle conversions from arrays to 1975 // pointer values, and pointer-to-pointer conversions. 1976 case Stmt::ImplicitCastExprClass: 1977 case Stmt::CStyleCastExprClass: 1978 case Stmt::CXXFunctionalCastExprClass: { 1979 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1980 QualType T = SubExpr->getType(); 1981 1982 if (SubExpr->getType()->isPointerType() || 1983 SubExpr->getType()->isBlockPointerType() || 1984 SubExpr->getType()->isObjCQualifiedIdType()) 1985 return EvalAddr(SubExpr, refVars); 1986 else if (T->isArrayType()) 1987 return EvalVal(SubExpr, refVars); 1988 else 1989 return 0; 1990 } 1991 1992 // C++ casts. For dynamic casts, static casts, and const casts, we 1993 // are always converting from a pointer-to-pointer, so we just blow 1994 // through the cast. In the case the dynamic cast doesn't fail (and 1995 // return NULL), we take the conservative route and report cases 1996 // where we return the address of a stack variable. For Reinterpre 1997 // FIXME: The comment about is wrong; we're not always converting 1998 // from pointer to pointer. I'm guessing that this code should also 1999 // handle references to objects. 2000 case Stmt::CXXStaticCastExprClass: 2001 case Stmt::CXXDynamicCastExprClass: 2002 case Stmt::CXXConstCastExprClass: 2003 case Stmt::CXXReinterpretCastExprClass: { 2004 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 2005 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 2006 return EvalAddr(S, refVars); 2007 else 2008 return NULL; 2009 } 2010 2011 // Everything else: we simply don't reason about them. 2012 default: 2013 return NULL; 2014 } 2015} 2016 2017 2018/// EvalVal - This function is complements EvalAddr in the mutual recursion. 2019/// See the comments for EvalAddr for more details. 2020static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { 2021do { 2022 // We should only be called for evaluating non-pointer expressions, or 2023 // expressions with a pointer type that are not used as references but instead 2024 // are l-values (e.g., DeclRefExpr with a pointer type). 2025 2026 // Our "symbolic interpreter" is just a dispatch off the currently 2027 // viewed AST node. We then recursively traverse the AST by calling 2028 // EvalAddr and EvalVal appropriately. 2029 switch (E->getStmtClass()) { 2030 case Stmt::ImplicitCastExprClass: { 2031 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 2032 if (IE->getValueKind() == VK_LValue) { 2033 E = IE->getSubExpr(); 2034 continue; 2035 } 2036 return NULL; 2037 } 2038 2039 case Stmt::DeclRefExprClass: { 2040 // When we hit a DeclRefExpr we are looking at code that refers to a 2041 // variable's name. If it's not a reference variable we check if it has 2042 // local storage within the function, and if so, return the expression. 2043 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2044 2045 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2046 if (V->hasLocalStorage()) { 2047 if (!V->getType()->isReferenceType()) 2048 return DR; 2049 2050 // Reference variable, follow through to the expression that 2051 // it points to. 2052 if (V->hasInit()) { 2053 // Add the reference variable to the "trail". 2054 refVars.push_back(DR); 2055 return EvalVal(V->getInit(), refVars); 2056 } 2057 } 2058 2059 return NULL; 2060 } 2061 2062 case Stmt::ParenExprClass: { 2063 // Ignore parentheses. 2064 E = cast<ParenExpr>(E)->getSubExpr(); 2065 continue; 2066 } 2067 2068 case Stmt::UnaryOperatorClass: { 2069 // The only unary operator that make sense to handle here 2070 // is Deref. All others don't resolve to a "name." This includes 2071 // handling all sorts of rvalues passed to a unary operator. 2072 UnaryOperator *U = cast<UnaryOperator>(E); 2073 2074 if (U->getOpcode() == UO_Deref) 2075 return EvalAddr(U->getSubExpr(), refVars); 2076 2077 return NULL; 2078 } 2079 2080 case Stmt::ArraySubscriptExprClass: { 2081 // Array subscripts are potential references to data on the stack. We 2082 // retrieve the DeclRefExpr* for the array variable if it indeed 2083 // has local storage. 2084 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars); 2085 } 2086 2087 case Stmt::ConditionalOperatorClass: { 2088 // For conditional operators we need to see if either the LHS or RHS are 2089 // non-NULL Expr's. If one is non-NULL, we return it. 2090 ConditionalOperator *C = cast<ConditionalOperator>(E); 2091 2092 // Handle the GNU extension for missing LHS. 2093 if (Expr *lhsExpr = C->getLHS()) 2094 if (Expr *LHS = EvalVal(lhsExpr, refVars)) 2095 return LHS; 2096 2097 return EvalVal(C->getRHS(), refVars); 2098 } 2099 2100 // Accesses to members are potential references to data on the stack. 2101 case Stmt::MemberExprClass: { 2102 MemberExpr *M = cast<MemberExpr>(E); 2103 2104 // Check for indirect access. We only want direct field accesses. 2105 if (M->isArrow()) 2106 return NULL; 2107 2108 // Check whether the member type is itself a reference, in which case 2109 // we're not going to refer to the member, but to what the member refers to. 2110 if (M->getMemberDecl()->getType()->isReferenceType()) 2111 return NULL; 2112 2113 return EvalVal(M->getBase(), refVars); 2114 } 2115 2116 default: 2117 // Check that we don't return or take the address of a reference to a 2118 // temporary. This is only useful in C++. 2119 if (!E->isTypeDependent() && E->isRValue()) 2120 return E; 2121 2122 // Everything else: we simply don't reason about them. 2123 return NULL; 2124 } 2125} while (true); 2126} 2127 2128//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2129 2130/// Check for comparisons of floating point operands using != and ==. 2131/// Issue a warning if these are no self-comparisons, as they are not likely 2132/// to do what the programmer intended. 2133void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2134 bool EmitWarning = true; 2135 2136 Expr* LeftExprSansParen = lex->IgnoreParenImpCasts(); 2137 Expr* RightExprSansParen = rex->IgnoreParenImpCasts(); 2138 2139 // Special case: check for x == x (which is OK). 2140 // Do not emit warnings for such cases. 2141 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2142 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2143 if (DRL->getDecl() == DRR->getDecl()) 2144 EmitWarning = false; 2145 2146 2147 // Special case: check for comparisons against literals that can be exactly 2148 // represented by APFloat. In such cases, do not emit a warning. This 2149 // is a heuristic: often comparison against such literals are used to 2150 // detect if a value in a variable has not changed. This clearly can 2151 // lead to false negatives. 2152 if (EmitWarning) { 2153 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2154 if (FLL->isExact()) 2155 EmitWarning = false; 2156 } else 2157 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2158 if (FLR->isExact()) 2159 EmitWarning = false; 2160 } 2161 } 2162 2163 // Check for comparisons with builtin types. 2164 if (EmitWarning) 2165 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2166 if (CL->isBuiltinCall(Context)) 2167 EmitWarning = false; 2168 2169 if (EmitWarning) 2170 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2171 if (CR->isBuiltinCall(Context)) 2172 EmitWarning = false; 2173 2174 // Emit the diagnostic. 2175 if (EmitWarning) 2176 Diag(loc, diag::warn_floatingpoint_eq) 2177 << lex->getSourceRange() << rex->getSourceRange(); 2178} 2179 2180//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2181//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2182 2183namespace { 2184 2185/// Structure recording the 'active' range of an integer-valued 2186/// expression. 2187struct IntRange { 2188 /// The number of bits active in the int. 2189 unsigned Width; 2190 2191 /// True if the int is known not to have negative values. 2192 bool NonNegative; 2193 2194 IntRange(unsigned Width, bool NonNegative) 2195 : Width(Width), NonNegative(NonNegative) 2196 {} 2197 2198 /// Returns the range of the bool type. 2199 static IntRange forBoolType() { 2200 return IntRange(1, true); 2201 } 2202 2203 /// Returns the range of an opaque value of the given integral type. 2204 static IntRange forValueOfType(ASTContext &C, QualType T) { 2205 return forValueOfCanonicalType(C, 2206 T->getCanonicalTypeInternal().getTypePtr()); 2207 } 2208 2209 /// Returns the range of an opaque value of a canonical integral type. 2210 static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) { 2211 assert(T->isCanonicalUnqualified()); 2212 2213 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2214 T = VT->getElementType().getTypePtr(); 2215 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2216 T = CT->getElementType().getTypePtr(); 2217 2218 // For enum types, use the known bit width of the enumerators. 2219 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2220 EnumDecl *Enum = ET->getDecl(); 2221 if (!Enum->isDefinition()) 2222 return IntRange(C.getIntWidth(QualType(T, 0)), false); 2223 2224 unsigned NumPositive = Enum->getNumPositiveBits(); 2225 unsigned NumNegative = Enum->getNumNegativeBits(); 2226 2227 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2228 } 2229 2230 const BuiltinType *BT = cast<BuiltinType>(T); 2231 assert(BT->isInteger()); 2232 2233 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2234 } 2235 2236 /// Returns the "target" range of a canonical integral type, i.e. 2237 /// the range of values expressible in the type. 2238 /// 2239 /// This matches forValueOfCanonicalType except that enums have the 2240 /// full range of their type, not the range of their enumerators. 2241 static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) { 2242 assert(T->isCanonicalUnqualified()); 2243 2244 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2245 T = VT->getElementType().getTypePtr(); 2246 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2247 T = CT->getElementType().getTypePtr(); 2248 if (const EnumType *ET = dyn_cast<EnumType>(T)) 2249 T = ET->getDecl()->getIntegerType().getTypePtr(); 2250 2251 const BuiltinType *BT = cast<BuiltinType>(T); 2252 assert(BT->isInteger()); 2253 2254 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2255 } 2256 2257 /// Returns the supremum of two ranges: i.e. their conservative merge. 2258 static IntRange join(IntRange L, IntRange R) { 2259 return IntRange(std::max(L.Width, R.Width), 2260 L.NonNegative && R.NonNegative); 2261 } 2262 2263 /// Returns the infinum of two ranges: i.e. their aggressive merge. 2264 static IntRange meet(IntRange L, IntRange R) { 2265 return IntRange(std::min(L.Width, R.Width), 2266 L.NonNegative || R.NonNegative); 2267 } 2268}; 2269 2270IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2271 if (value.isSigned() && value.isNegative()) 2272 return IntRange(value.getMinSignedBits(), false); 2273 2274 if (value.getBitWidth() > MaxWidth) 2275 value = value.trunc(MaxWidth); 2276 2277 // isNonNegative() just checks the sign bit without considering 2278 // signedness. 2279 return IntRange(value.getActiveBits(), true); 2280} 2281 2282IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2283 unsigned MaxWidth) { 2284 if (result.isInt()) 2285 return GetValueRange(C, result.getInt(), MaxWidth); 2286 2287 if (result.isVector()) { 2288 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2289 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2290 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2291 R = IntRange::join(R, El); 2292 } 2293 return R; 2294 } 2295 2296 if (result.isComplexInt()) { 2297 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2298 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2299 return IntRange::join(R, I); 2300 } 2301 2302 // This can happen with lossless casts to intptr_t of "based" lvalues. 2303 // Assume it might use arbitrary bits. 2304 // FIXME: The only reason we need to pass the type in here is to get 2305 // the sign right on this one case. It would be nice if APValue 2306 // preserved this. 2307 assert(result.isLValue()); 2308 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2309} 2310 2311/// Pseudo-evaluate the given integer expression, estimating the 2312/// range of values it might take. 2313/// 2314/// \param MaxWidth - the width to which the value will be truncated 2315IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2316 E = E->IgnoreParens(); 2317 2318 // Try a full evaluation first. 2319 Expr::EvalResult result; 2320 if (E->Evaluate(result, C)) 2321 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2322 2323 // I think we only want to look through implicit casts here; if the 2324 // user has an explicit widening cast, we should treat the value as 2325 // being of the new, wider type. 2326 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2327 if (CE->getCastKind() == CK_NoOp) 2328 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2329 2330 IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); 2331 2332 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 2333 2334 // Assume that non-integer casts can span the full range of the type. 2335 if (!isIntegerCast) 2336 return OutputTypeRange; 2337 2338 IntRange SubRange 2339 = GetExprRange(C, CE->getSubExpr(), 2340 std::min(MaxWidth, OutputTypeRange.Width)); 2341 2342 // Bail out if the subexpr's range is as wide as the cast type. 2343 if (SubRange.Width >= OutputTypeRange.Width) 2344 return OutputTypeRange; 2345 2346 // Otherwise, we take the smaller width, and we're non-negative if 2347 // either the output type or the subexpr is. 2348 return IntRange(SubRange.Width, 2349 SubRange.NonNegative || OutputTypeRange.NonNegative); 2350 } 2351 2352 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2353 // If we can fold the condition, just take that operand. 2354 bool CondResult; 2355 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2356 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2357 : CO->getFalseExpr(), 2358 MaxWidth); 2359 2360 // Otherwise, conservatively merge. 2361 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2362 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2363 return IntRange::join(L, R); 2364 } 2365 2366 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2367 switch (BO->getOpcode()) { 2368 2369 // Boolean-valued operations are single-bit and positive. 2370 case BO_LAnd: 2371 case BO_LOr: 2372 case BO_LT: 2373 case BO_GT: 2374 case BO_LE: 2375 case BO_GE: 2376 case BO_EQ: 2377 case BO_NE: 2378 return IntRange::forBoolType(); 2379 2380 // The type of these compound assignments is the type of the LHS, 2381 // so the RHS is not necessarily an integer. 2382 case BO_MulAssign: 2383 case BO_DivAssign: 2384 case BO_RemAssign: 2385 case BO_AddAssign: 2386 case BO_SubAssign: 2387 return IntRange::forValueOfType(C, E->getType()); 2388 2389 // Operations with opaque sources are black-listed. 2390 case BO_PtrMemD: 2391 case BO_PtrMemI: 2392 return IntRange::forValueOfType(C, E->getType()); 2393 2394 // Bitwise-and uses the *infinum* of the two source ranges. 2395 case BO_And: 2396 case BO_AndAssign: 2397 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2398 GetExprRange(C, BO->getRHS(), MaxWidth)); 2399 2400 // Left shift gets black-listed based on a judgement call. 2401 case BO_Shl: 2402 // ...except that we want to treat '1 << (blah)' as logically 2403 // positive. It's an important idiom. 2404 if (IntegerLiteral *I 2405 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2406 if (I->getValue() == 1) { 2407 IntRange R = IntRange::forValueOfType(C, E->getType()); 2408 return IntRange(R.Width, /*NonNegative*/ true); 2409 } 2410 } 2411 // fallthrough 2412 2413 case BO_ShlAssign: 2414 return IntRange::forValueOfType(C, E->getType()); 2415 2416 // Right shift by a constant can narrow its left argument. 2417 case BO_Shr: 2418 case BO_ShrAssign: { 2419 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2420 2421 // If the shift amount is a positive constant, drop the width by 2422 // that much. 2423 llvm::APSInt shift; 2424 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2425 shift.isNonNegative()) { 2426 unsigned zext = shift.getZExtValue(); 2427 if (zext >= L.Width) 2428 L.Width = (L.NonNegative ? 0 : 1); 2429 else 2430 L.Width -= zext; 2431 } 2432 2433 return L; 2434 } 2435 2436 // Comma acts as its right operand. 2437 case BO_Comma: 2438 return GetExprRange(C, BO->getRHS(), MaxWidth); 2439 2440 // Black-list pointer subtractions. 2441 case BO_Sub: 2442 if (BO->getLHS()->getType()->isPointerType()) 2443 return IntRange::forValueOfType(C, E->getType()); 2444 // fallthrough 2445 2446 default: 2447 break; 2448 } 2449 2450 // Treat every other operator as if it were closed on the 2451 // narrowest type that encompasses both operands. 2452 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2453 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2454 return IntRange::join(L, R); 2455 } 2456 2457 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2458 switch (UO->getOpcode()) { 2459 // Boolean-valued operations are white-listed. 2460 case UO_LNot: 2461 return IntRange::forBoolType(); 2462 2463 // Operations with opaque sources are black-listed. 2464 case UO_Deref: 2465 case UO_AddrOf: // should be impossible 2466 return IntRange::forValueOfType(C, E->getType()); 2467 2468 default: 2469 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2470 } 2471 } 2472 2473 if (dyn_cast<OffsetOfExpr>(E)) { 2474 IntRange::forValueOfType(C, E->getType()); 2475 } 2476 2477 FieldDecl *BitField = E->getBitField(); 2478 if (BitField) { 2479 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2480 unsigned BitWidth = BitWidthAP.getZExtValue(); 2481 2482 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2483 } 2484 2485 return IntRange::forValueOfType(C, E->getType()); 2486} 2487 2488IntRange GetExprRange(ASTContext &C, Expr *E) { 2489 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2490} 2491 2492/// Checks whether the given value, which currently has the given 2493/// source semantics, has the same value when coerced through the 2494/// target semantics. 2495bool IsSameFloatAfterCast(const llvm::APFloat &value, 2496 const llvm::fltSemantics &Src, 2497 const llvm::fltSemantics &Tgt) { 2498 llvm::APFloat truncated = value; 2499 2500 bool ignored; 2501 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2502 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2503 2504 return truncated.bitwiseIsEqual(value); 2505} 2506 2507/// Checks whether the given value, which currently has the given 2508/// source semantics, has the same value when coerced through the 2509/// target semantics. 2510/// 2511/// The value might be a vector of floats (or a complex number). 2512bool IsSameFloatAfterCast(const APValue &value, 2513 const llvm::fltSemantics &Src, 2514 const llvm::fltSemantics &Tgt) { 2515 if (value.isFloat()) 2516 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2517 2518 if (value.isVector()) { 2519 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2520 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2521 return false; 2522 return true; 2523 } 2524 2525 assert(value.isComplexFloat()); 2526 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2527 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2528} 2529 2530void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC); 2531 2532static bool IsZero(Sema &S, Expr *E) { 2533 // Suppress cases where we are comparing against an enum constant. 2534 if (const DeclRefExpr *DR = 2535 dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) 2536 if (isa<EnumConstantDecl>(DR->getDecl())) 2537 return false; 2538 2539 // Suppress cases where the '0' value is expanded from a macro. 2540 if (E->getLocStart().isMacroID()) 2541 return false; 2542 2543 llvm::APSInt Value; 2544 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2545} 2546 2547static bool HasEnumType(Expr *E) { 2548 // Strip off implicit integral promotions. 2549 while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { 2550 if (ICE->getCastKind() != CK_IntegralCast && 2551 ICE->getCastKind() != CK_NoOp) 2552 break; 2553 E = ICE->getSubExpr(); 2554 } 2555 2556 return E->getType()->isEnumeralType(); 2557} 2558 2559void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2560 BinaryOperatorKind op = E->getOpcode(); 2561 if (E->isValueDependent()) 2562 return; 2563 2564 if (op == BO_LT && IsZero(S, E->getRHS())) { 2565 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2566 << "< 0" << "false" << HasEnumType(E->getLHS()) 2567 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2568 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 2569 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2570 << ">= 0" << "true" << HasEnumType(E->getLHS()) 2571 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2572 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 2573 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2574 << "0 >" << "false" << HasEnumType(E->getRHS()) 2575 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2576 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 2577 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2578 << "0 <=" << "true" << HasEnumType(E->getRHS()) 2579 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2580 } 2581} 2582 2583/// Analyze the operands of the given comparison. Implements the 2584/// fallback case from AnalyzeComparison. 2585void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2586 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2587 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2588} 2589 2590/// \brief Implements -Wsign-compare. 2591/// 2592/// \param lex the left-hand expression 2593/// \param rex the right-hand expression 2594/// \param OpLoc the location of the joining operator 2595/// \param BinOpc binary opcode or 0 2596void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2597 // The type the comparison is being performed in. 2598 QualType T = E->getLHS()->getType(); 2599 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2600 && "comparison with mismatched types"); 2601 2602 // We don't do anything special if this isn't an unsigned integral 2603 // comparison: we're only interested in integral comparisons, and 2604 // signed comparisons only happen in cases we don't care to warn about. 2605 // 2606 // We also don't care about value-dependent expressions or expressions 2607 // whose result is a constant. 2608 if (!T->hasUnsignedIntegerRepresentation() 2609 || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) 2610 return AnalyzeImpConvsInComparison(S, E); 2611 2612 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2613 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2614 2615 // Check to see if one of the (unmodified) operands is of different 2616 // signedness. 2617 Expr *signedOperand, *unsignedOperand; 2618 if (lex->getType()->hasSignedIntegerRepresentation()) { 2619 assert(!rex->getType()->hasSignedIntegerRepresentation() && 2620 "unsigned comparison between two signed integer expressions?"); 2621 signedOperand = lex; 2622 unsignedOperand = rex; 2623 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 2624 signedOperand = rex; 2625 unsignedOperand = lex; 2626 } else { 2627 CheckTrivialUnsignedComparison(S, E); 2628 return AnalyzeImpConvsInComparison(S, E); 2629 } 2630 2631 // Otherwise, calculate the effective range of the signed operand. 2632 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2633 2634 // Go ahead and analyze implicit conversions in the operands. Note 2635 // that we skip the implicit conversions on both sides. 2636 AnalyzeImplicitConversions(S, lex, E->getOperatorLoc()); 2637 AnalyzeImplicitConversions(S, rex, E->getOperatorLoc()); 2638 2639 // If the signed range is non-negative, -Wsign-compare won't fire, 2640 // but we should still check for comparisons which are always true 2641 // or false. 2642 if (signedRange.NonNegative) 2643 return CheckTrivialUnsignedComparison(S, E); 2644 2645 // For (in)equality comparisons, if the unsigned operand is a 2646 // constant which cannot collide with a overflowed signed operand, 2647 // then reinterpreting the signed operand as unsigned will not 2648 // change the result of the comparison. 2649 if (E->isEqualityOp()) { 2650 unsigned comparisonWidth = S.Context.getIntWidth(T); 2651 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2652 2653 // We should never be unable to prove that the unsigned operand is 2654 // non-negative. 2655 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2656 2657 if (unsignedRange.Width < comparisonWidth) 2658 return; 2659 } 2660 2661 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2662 << lex->getType() << rex->getType() 2663 << lex->getSourceRange() << rex->getSourceRange(); 2664} 2665 2666/// Analyzes an attempt to assign the given value to a bitfield. 2667/// 2668/// Returns true if there was something fishy about the attempt. 2669bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, 2670 SourceLocation InitLoc) { 2671 assert(Bitfield->isBitField()); 2672 if (Bitfield->isInvalidDecl()) 2673 return false; 2674 2675 // White-list bool bitfields. 2676 if (Bitfield->getType()->isBooleanType()) 2677 return false; 2678 2679 // Ignore value- or type-dependent expressions. 2680 if (Bitfield->getBitWidth()->isValueDependent() || 2681 Bitfield->getBitWidth()->isTypeDependent() || 2682 Init->isValueDependent() || 2683 Init->isTypeDependent()) 2684 return false; 2685 2686 Expr *OriginalInit = Init->IgnoreParenImpCasts(); 2687 2688 llvm::APSInt Width(32); 2689 Expr::EvalResult InitValue; 2690 if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) || 2691 !OriginalInit->Evaluate(InitValue, S.Context) || 2692 !InitValue.Val.isInt()) 2693 return false; 2694 2695 const llvm::APSInt &Value = InitValue.Val.getInt(); 2696 unsigned OriginalWidth = Value.getBitWidth(); 2697 unsigned FieldWidth = Width.getZExtValue(); 2698 2699 if (OriginalWidth <= FieldWidth) 2700 return false; 2701 2702 llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); 2703 2704 // It's fairly common to write values into signed bitfields 2705 // that, if sign-extended, would end up becoming a different 2706 // value. We don't want to warn about that. 2707 if (Value.isSigned() && Value.isNegative()) 2708 TruncatedValue = TruncatedValue.sext(OriginalWidth); 2709 else 2710 TruncatedValue = TruncatedValue.zext(OriginalWidth); 2711 2712 if (Value == TruncatedValue) 2713 return false; 2714 2715 std::string PrettyValue = Value.toString(10); 2716 std::string PrettyTrunc = TruncatedValue.toString(10); 2717 2718 S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) 2719 << PrettyValue << PrettyTrunc << OriginalInit->getType() 2720 << Init->getSourceRange(); 2721 2722 return true; 2723} 2724 2725/// Analyze the given simple or compound assignment for warning-worthy 2726/// operations. 2727void AnalyzeAssignment(Sema &S, BinaryOperator *E) { 2728 // Just recurse on the LHS. 2729 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 2730 2731 // We want to recurse on the RHS as normal unless we're assigning to 2732 // a bitfield. 2733 if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { 2734 if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), 2735 E->getOperatorLoc())) { 2736 // Recurse, ignoring any implicit conversions on the RHS. 2737 return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), 2738 E->getOperatorLoc()); 2739 } 2740 } 2741 2742 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 2743} 2744 2745/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2746void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext, 2747 unsigned diag) { 2748 S.Diag(E->getExprLoc(), diag) 2749 << E->getType() << T << E->getSourceRange() << SourceRange(CContext); 2750} 2751 2752/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2753void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 2754 SourceLocation CContext, unsigned diag) { 2755 S.Diag(E->getExprLoc(), diag) 2756 << SourceType << T << E->getSourceRange() << SourceRange(CContext); 2757} 2758 2759std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { 2760 if (!Range.Width) return "0"; 2761 2762 llvm::APSInt ValueInRange = Value; 2763 ValueInRange.setIsSigned(!Range.NonNegative); 2764 ValueInRange = ValueInRange.trunc(Range.Width); 2765 return ValueInRange.toString(10); 2766} 2767 2768static bool isFromSystemMacro(Sema &S, SourceLocation loc) { 2769 SourceManager &smgr = S.Context.getSourceManager(); 2770 return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc)); 2771} 2772 2773void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2774 SourceLocation CC, bool *ICContext = 0) { 2775 if (E->isTypeDependent() || E->isValueDependent()) return; 2776 2777 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2778 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2779 if (Source == Target) return; 2780 if (Target->isDependentType()) return; 2781 2782 // If the conversion context location is invalid don't complain. 2783 // We also don't want to emit a warning if the issue occurs from the 2784 // instantiation of a system macro. The problem is that 'getSpellingLoc()' 2785 // is slow, so we delay this check as long as possible. Once we detect 2786 // we are in that scenario, we just return. 2787 if (CC.isInvalid()) 2788 return; 2789 2790 // Never diagnose implicit casts to bool. 2791 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2792 return; 2793 2794 // Strip vector types. 2795 if (isa<VectorType>(Source)) { 2796 if (!isa<VectorType>(Target)) { 2797 if (isFromSystemMacro(S, CC)) 2798 return; 2799 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar); 2800 } 2801 2802 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2803 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2804 } 2805 2806 // Strip complex types. 2807 if (isa<ComplexType>(Source)) { 2808 if (!isa<ComplexType>(Target)) { 2809 if (isFromSystemMacro(S, CC)) 2810 return; 2811 2812 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar); 2813 } 2814 2815 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2816 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2817 } 2818 2819 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2820 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2821 2822 // If the source is floating point... 2823 if (SourceBT && SourceBT->isFloatingPoint()) { 2824 // ...and the target is floating point... 2825 if (TargetBT && TargetBT->isFloatingPoint()) { 2826 // ...then warn if we're dropping FP rank. 2827 2828 // Builtin FP kinds are ordered by increasing FP rank. 2829 if (SourceBT->getKind() > TargetBT->getKind()) { 2830 // Don't warn about float constants that are precisely 2831 // representable in the target type. 2832 Expr::EvalResult result; 2833 if (E->Evaluate(result, S.Context)) { 2834 // Value might be a float, a float vector, or a float complex. 2835 if (IsSameFloatAfterCast(result.Val, 2836 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2837 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2838 return; 2839 } 2840 2841 if (isFromSystemMacro(S, CC)) 2842 return; 2843 2844 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision); 2845 } 2846 return; 2847 } 2848 2849 // If the target is integral, always warn. 2850 if ((TargetBT && TargetBT->isInteger())) { 2851 if (isFromSystemMacro(S, CC)) 2852 return; 2853 2854 Expr *InnerE = E->IgnoreParenImpCasts(); 2855 if (FloatingLiteral *LiteralExpr = dyn_cast<FloatingLiteral>(InnerE)) { 2856 DiagnoseImpCast(S, LiteralExpr, T, CC, 2857 diag::warn_impcast_literal_float_to_integer); 2858 } else { 2859 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); 2860 } 2861 } 2862 2863 return; 2864 } 2865 2866 if (!Source->isIntegerType() || !Target->isIntegerType()) 2867 return; 2868 2869 IntRange SourceRange = GetExprRange(S.Context, E); 2870 IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); 2871 2872 if (SourceRange.Width > TargetRange.Width) { 2873 // If the source is a constant, use a default-on diagnostic. 2874 // TODO: this should happen for bitfield stores, too. 2875 llvm::APSInt Value(32); 2876 if (E->isIntegerConstantExpr(Value, S.Context)) { 2877 if (isFromSystemMacro(S, CC)) 2878 return; 2879 2880 std::string PrettySourceValue = Value.toString(10); 2881 std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); 2882 2883 S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant) 2884 << PrettySourceValue << PrettyTargetValue 2885 << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC); 2886 return; 2887 } 2888 2889 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2890 // and by god we'll let them. 2891 2892 if (isFromSystemMacro(S, CC)) 2893 return; 2894 2895 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2896 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32); 2897 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); 2898 } 2899 2900 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2901 (!TargetRange.NonNegative && SourceRange.NonNegative && 2902 SourceRange.Width == TargetRange.Width)) { 2903 2904 if (isFromSystemMacro(S, CC)) 2905 return; 2906 2907 unsigned DiagID = diag::warn_impcast_integer_sign; 2908 2909 // Traditionally, gcc has warned about this under -Wsign-compare. 2910 // We also want to warn about it in -Wconversion. 2911 // So if -Wconversion is off, use a completely identical diagnostic 2912 // in the sign-compare group. 2913 // The conditional-checking code will 2914 if (ICContext) { 2915 DiagID = diag::warn_impcast_integer_sign_conditional; 2916 *ICContext = true; 2917 } 2918 2919 return DiagnoseImpCast(S, E, T, CC, DiagID); 2920 } 2921 2922 // Diagnose conversions between different enumeration types. 2923 // In C, we pretend that the type of an EnumConstantDecl is its enumeration 2924 // type, to give us better diagnostics. 2925 QualType SourceType = E->getType(); 2926 if (!S.getLangOptions().CPlusPlus) { 2927 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 2928 if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) { 2929 EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext()); 2930 SourceType = S.Context.getTypeDeclType(Enum); 2931 Source = S.Context.getCanonicalType(SourceType).getTypePtr(); 2932 } 2933 } 2934 2935 if (const EnumType *SourceEnum = Source->getAs<EnumType>()) 2936 if (const EnumType *TargetEnum = Target->getAs<EnumType>()) 2937 if ((SourceEnum->getDecl()->getIdentifier() || 2938 SourceEnum->getDecl()->getTypedefForAnonDecl()) && 2939 (TargetEnum->getDecl()->getIdentifier() || 2940 TargetEnum->getDecl()->getTypedefForAnonDecl()) && 2941 SourceEnum != TargetEnum) { 2942 if (isFromSystemMacro(S, CC)) 2943 return; 2944 2945 return DiagnoseImpCast(S, E, SourceType, T, CC, 2946 diag::warn_impcast_different_enum_types); 2947 } 2948 2949 return; 2950} 2951 2952void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2953 2954void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2955 SourceLocation CC, bool &ICContext) { 2956 E = E->IgnoreParenImpCasts(); 2957 2958 if (isa<ConditionalOperator>(E)) 2959 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2960 2961 AnalyzeImplicitConversions(S, E, CC); 2962 if (E->getType() != T) 2963 return CheckImplicitConversion(S, E, T, CC, &ICContext); 2964 return; 2965} 2966 2967void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2968 SourceLocation CC = E->getQuestionLoc(); 2969 2970 AnalyzeImplicitConversions(S, E->getCond(), CC); 2971 2972 bool Suspicious = false; 2973 CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); 2974 CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious); 2975 2976 // If -Wconversion would have warned about either of the candidates 2977 // for a signedness conversion to the context type... 2978 if (!Suspicious) return; 2979 2980 // ...but it's currently ignored... 2981 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional, 2982 CC)) 2983 return; 2984 2985 // ...and -Wsign-compare isn't... 2986 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional, CC)) 2987 return; 2988 2989 // ...then check whether it would have warned about either of the 2990 // candidates for a signedness conversion to the condition type. 2991 if (E->getType() != T) { 2992 Suspicious = false; 2993 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2994 E->getType(), CC, &Suspicious); 2995 if (!Suspicious) 2996 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2997 E->getType(), CC, &Suspicious); 2998 if (!Suspicious) 2999 return; 3000 } 3001 3002 // If so, emit a diagnostic under -Wsign-compare. 3003 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 3004 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 3005 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 3006 << lex->getType() << rex->getType() 3007 << lex->getSourceRange() << rex->getSourceRange(); 3008} 3009 3010/// AnalyzeImplicitConversions - Find and report any interesting 3011/// implicit conversions in the given expression. There are a couple 3012/// of competing diagnostics here, -Wconversion and -Wsign-compare. 3013void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) { 3014 QualType T = OrigE->getType(); 3015 Expr *E = OrigE->IgnoreParenImpCasts(); 3016 3017 // For conditional operators, we analyze the arguments as if they 3018 // were being fed directly into the output. 3019 if (isa<ConditionalOperator>(E)) { 3020 ConditionalOperator *CO = cast<ConditionalOperator>(E); 3021 CheckConditionalOperator(S, CO, T); 3022 return; 3023 } 3024 3025 // Go ahead and check any implicit conversions we might have skipped. 3026 // The non-canonical typecheck is just an optimization; 3027 // CheckImplicitConversion will filter out dead implicit conversions. 3028 if (E->getType() != T) 3029 CheckImplicitConversion(S, E, T, CC); 3030 3031 // Now continue drilling into this expression. 3032 3033 // Skip past explicit casts. 3034 if (isa<ExplicitCastExpr>(E)) { 3035 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 3036 return AnalyzeImplicitConversions(S, E, CC); 3037 } 3038 3039 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 3040 // Do a somewhat different check with comparison operators. 3041 if (BO->isComparisonOp()) 3042 return AnalyzeComparison(S, BO); 3043 3044 // And with assignments and compound assignments. 3045 if (BO->isAssignmentOp()) 3046 return AnalyzeAssignment(S, BO); 3047 } 3048 3049 // These break the otherwise-useful invariant below. Fortunately, 3050 // we don't really need to recurse into them, because any internal 3051 // expressions should have been analyzed already when they were 3052 // built into statements. 3053 if (isa<StmtExpr>(E)) return; 3054 3055 // Don't descend into unevaluated contexts. 3056 if (isa<UnaryExprOrTypeTraitExpr>(E)) return; 3057 3058 // Now just recurse over the expression's children. 3059 CC = E->getExprLoc(); 3060 for (Stmt::child_range I = E->children(); I; ++I) 3061 AnalyzeImplicitConversions(S, cast<Expr>(*I), CC); 3062} 3063 3064} // end anonymous namespace 3065 3066/// Diagnoses "dangerous" implicit conversions within the given 3067/// expression (which is a full expression). Implements -Wconversion 3068/// and -Wsign-compare. 3069/// 3070/// \param CC the "context" location of the implicit conversion, i.e. 3071/// the most location of the syntactic entity requiring the implicit 3072/// conversion 3073void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { 3074 // Don't diagnose in unevaluated contexts. 3075 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 3076 return; 3077 3078 // Don't diagnose for value- or type-dependent expressions. 3079 if (E->isTypeDependent() || E->isValueDependent()) 3080 return; 3081 3082 // This is not the right CC for (e.g.) a variable initialization. 3083 AnalyzeImplicitConversions(*this, E, CC); 3084} 3085 3086void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, 3087 FieldDecl *BitField, 3088 Expr *Init) { 3089 (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); 3090} 3091 3092/// CheckParmsForFunctionDef - Check that the parameters of the given 3093/// function are appropriate for the definition of a function. This 3094/// takes care of any checks that cannot be performed on the 3095/// declaration itself, e.g., that the types of each of the function 3096/// parameters are complete. 3097bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd, 3098 bool CheckParameterNames) { 3099 bool HasInvalidParm = false; 3100 for (; P != PEnd; ++P) { 3101 ParmVarDecl *Param = *P; 3102 3103 // C99 6.7.5.3p4: the parameters in a parameter type list in a 3104 // function declarator that is part of a function definition of 3105 // that function shall not have incomplete type. 3106 // 3107 // This is also C++ [dcl.fct]p6. 3108 if (!Param->isInvalidDecl() && 3109 RequireCompleteType(Param->getLocation(), Param->getType(), 3110 diag::err_typecheck_decl_incomplete_type)) { 3111 Param->setInvalidDecl(); 3112 HasInvalidParm = true; 3113 } 3114 3115 // C99 6.9.1p5: If the declarator includes a parameter type list, the 3116 // declaration of each parameter shall include an identifier. 3117 if (CheckParameterNames && 3118 Param->getIdentifier() == 0 && 3119 !Param->isImplicit() && 3120 !getLangOptions().CPlusPlus) 3121 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 3122 3123 // C99 6.7.5.3p12: 3124 // If the function declarator is not part of a definition of that 3125 // function, parameters may have incomplete type and may use the [*] 3126 // notation in their sequences of declarator specifiers to specify 3127 // variable length array types. 3128 QualType PType = Param->getOriginalType(); 3129 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 3130 if (AT->getSizeModifier() == ArrayType::Star) { 3131 // FIXME: This diagnosic should point the the '[*]' if source-location 3132 // information is added for it. 3133 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 3134 } 3135 } 3136 } 3137 3138 return HasInvalidParm; 3139} 3140 3141/// CheckCastAlign - Implements -Wcast-align, which warns when a 3142/// pointer cast increases the alignment requirements. 3143void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 3144 // This is actually a lot of work to potentially be doing on every 3145 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 3146 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, 3147 TRange.getBegin()) 3148 == Diagnostic::Ignored) 3149 return; 3150 3151 // Ignore dependent types. 3152 if (T->isDependentType() || Op->getType()->isDependentType()) 3153 return; 3154 3155 // Require that the destination be a pointer type. 3156 const PointerType *DestPtr = T->getAs<PointerType>(); 3157 if (!DestPtr) return; 3158 3159 // If the destination has alignment 1, we're done. 3160 QualType DestPointee = DestPtr->getPointeeType(); 3161 if (DestPointee->isIncompleteType()) return; 3162 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 3163 if (DestAlign.isOne()) return; 3164 3165 // Require that the source be a pointer type. 3166 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 3167 if (!SrcPtr) return; 3168 QualType SrcPointee = SrcPtr->getPointeeType(); 3169 3170 // Whitelist casts from cv void*. We already implicitly 3171 // whitelisted casts to cv void*, since they have alignment 1. 3172 // Also whitelist casts involving incomplete types, which implicitly 3173 // includes 'void'. 3174 if (SrcPointee->isIncompleteType()) return; 3175 3176 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 3177 if (SrcAlign >= DestAlign) return; 3178 3179 Diag(TRange.getBegin(), diag::warn_cast_align) 3180 << Op->getType() << T 3181 << static_cast<unsigned>(SrcAlign.getQuantity()) 3182 << static_cast<unsigned>(DestAlign.getQuantity()) 3183 << TRange << Op->getSourceRange(); 3184} 3185 3186static void CheckArrayAccess_Check(Sema &S, 3187 const clang::ArraySubscriptExpr *E) { 3188 const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts(); 3189 const ConstantArrayType *ArrayTy = 3190 S.Context.getAsConstantArrayType(BaseExpr->getType()); 3191 if (!ArrayTy) 3192 return; 3193 3194 const Expr *IndexExpr = E->getIdx(); 3195 if (IndexExpr->isValueDependent()) 3196 return; 3197 llvm::APSInt index; 3198 if (!IndexExpr->isIntegerConstantExpr(index, S.Context)) 3199 return; 3200 3201 if (index.isUnsigned() || !index.isNegative()) { 3202 llvm::APInt size = ArrayTy->getSize(); 3203 if (!size.isStrictlyPositive()) 3204 return; 3205 if (size.getBitWidth() > index.getBitWidth()) 3206 index = index.sext(size.getBitWidth()); 3207 else if (size.getBitWidth() < index.getBitWidth()) 3208 size = size.sext(index.getBitWidth()); 3209 3210 if (index.slt(size)) 3211 return; 3212 3213 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3214 S.PDiag(diag::warn_array_index_exceeds_bounds) 3215 << index.toString(10, true) 3216 << size.toString(10, true) 3217 << IndexExpr->getSourceRange()); 3218 } else { 3219 S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr, 3220 S.PDiag(diag::warn_array_index_precedes_bounds) 3221 << index.toString(10, true) 3222 << IndexExpr->getSourceRange()); 3223 } 3224 3225 const NamedDecl *ND = NULL; 3226 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 3227 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 3228 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 3229 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 3230 if (ND) 3231 S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr, 3232 S.PDiag(diag::note_array_index_out_of_bounds) 3233 << ND->getDeclName()); 3234} 3235 3236void Sema::CheckArrayAccess(const Expr *expr) { 3237 while (true) 3238 switch (expr->getStmtClass()) { 3239 case Stmt::ParenExprClass: 3240 expr = cast<ParenExpr>(expr)->getSubExpr(); 3241 continue; 3242 case Stmt::ArraySubscriptExprClass: 3243 CheckArrayAccess_Check(*this, cast<ArraySubscriptExpr>(expr)); 3244 return; 3245 case Stmt::ConditionalOperatorClass: { 3246 const ConditionalOperator *cond = cast<ConditionalOperator>(expr); 3247 if (const Expr *lhs = cond->getLHS()) 3248 CheckArrayAccess(lhs); 3249 if (const Expr *rhs = cond->getRHS()) 3250 CheckArrayAccess(rhs); 3251 return; 3252 } 3253 default: 3254 return; 3255 } 3256} 3257