1 //===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines an API used to report recoverable errors. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_SUPPORT_ERROR_H 14 #define LLVM_SUPPORT_ERROR_H 15 16 #include "llvm-c/Error.h" 17 #include "llvm/ADT/Twine.h" 18 #include "llvm/Config/abi-breaking.h" 19 #include "llvm/Support/AlignOf.h" 20 #include "llvm/Support/Compiler.h" 21 #include "llvm/Support/Debug.h" 22 #include "llvm/Support/ErrorHandling.h" 23 #include "llvm/Support/ErrorOr.h" 24 #include "llvm/Support/Format.h" 25 #include "llvm/Support/raw_ostream.h" 26 #include <cassert> 27 #include <cstdint> 28 #include <cstdlib> 29 #include <functional> 30 #include <memory> 31 #include <new> 32 #include <optional> 33 #include <string> 34 #include <system_error> 35 #include <type_traits> 36 #include <utility> 37 #include <vector> 38 39 namespace llvm { 40 41 class ErrorSuccess; 42 43 /// Base class for error info classes. Do not extend this directly: Extend 44 /// the ErrorInfo template subclass instead. 45 class ErrorInfoBase { 46 public: 47 virtual ~ErrorInfoBase() = default; 48 49 /// Print an error message to an output stream. 50 virtual void log(raw_ostream &OS) const = 0; 51 52 /// Return the error message as a string. 53 virtual std::string message() const { 54 std::string Msg; 55 raw_string_ostream OS(Msg); 56 log(OS); 57 return OS.str(); 58 } 59 60 /// Convert this error to a std::error_code. 61 /// 62 /// This is a temporary crutch to enable interaction with code still 63 /// using std::error_code. It will be removed in the future. 64 virtual std::error_code convertToErrorCode() const = 0; 65 66 // Returns the class ID for this type. 67 static const void *classID() { return &ID; } 68 69 // Returns the class ID for the dynamic type of this ErrorInfoBase instance. 70 virtual const void *dynamicClassID() const = 0; 71 72 // Check whether this instance is a subclass of the class identified by 73 // ClassID. 74 virtual bool isA(const void *const ClassID) const { 75 return ClassID == classID(); 76 } 77 78 // Check whether this instance is a subclass of ErrorInfoT. 79 template <typename ErrorInfoT> bool isA() const { 80 return isA(ErrorInfoT::classID()); 81 } 82 83 private: 84 virtual void anchor(); 85 86 static char ID; 87 }; 88 89 /// Lightweight error class with error context and mandatory checking. 90 /// 91 /// Instances of this class wrap a ErrorInfoBase pointer. Failure states 92 /// are represented by setting the pointer to a ErrorInfoBase subclass 93 /// instance containing information describing the failure. Success is 94 /// represented by a null pointer value. 95 /// 96 /// Instances of Error also contains a 'Checked' flag, which must be set 97 /// before the destructor is called, otherwise the destructor will trigger a 98 /// runtime error. This enforces at runtime the requirement that all Error 99 /// instances be checked or returned to the caller. 100 /// 101 /// There are two ways to set the checked flag, depending on what state the 102 /// Error instance is in. For Error instances indicating success, it 103 /// is sufficient to invoke the boolean conversion operator. E.g.: 104 /// 105 /// @code{.cpp} 106 /// Error foo(<...>); 107 /// 108 /// if (auto E = foo(<...>)) 109 /// return E; // <- Return E if it is in the error state. 110 /// // We have verified that E was in the success state. It can now be safely 111 /// // destroyed. 112 /// @endcode 113 /// 114 /// A success value *can not* be dropped. For example, just calling 'foo(<...>)' 115 /// without testing the return value will raise a runtime error, even if foo 116 /// returns success. 117 /// 118 /// For Error instances representing failure, you must use either the 119 /// handleErrors or handleAllErrors function with a typed handler. E.g.: 120 /// 121 /// @code{.cpp} 122 /// class MyErrorInfo : public ErrorInfo<MyErrorInfo> { 123 /// // Custom error info. 124 /// }; 125 /// 126 /// Error foo(<...>) { return make_error<MyErrorInfo>(...); } 127 /// 128 /// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo. 129 /// auto NewE = 130 /// handleErrors(E, 131 /// [](const MyErrorInfo &M) { 132 /// // Deal with the error. 133 /// }, 134 /// [](std::unique_ptr<OtherError> M) -> Error { 135 /// if (canHandle(*M)) { 136 /// // handle error. 137 /// return Error::success(); 138 /// } 139 /// // Couldn't handle this error instance. Pass it up the stack. 140 /// return Error(std::move(M)); 141 /// ); 142 /// // Note - we must check or return NewE in case any of the handlers 143 /// // returned a new error. 144 /// @endcode 145 /// 146 /// The handleAllErrors function is identical to handleErrors, except 147 /// that it has a void return type, and requires all errors to be handled and 148 /// no new errors be returned. It prevents errors (assuming they can all be 149 /// handled) from having to be bubbled all the way to the top-level. 150 /// 151 /// *All* Error instances must be checked before destruction, even if 152 /// they're moved-assigned or constructed from Success values that have already 153 /// been checked. This enforces checking through all levels of the call stack. 154 class [[nodiscard]] Error { 155 // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors 156 // to add to the error list. It can't rely on handleErrors for this, since 157 // handleErrors does not support ErrorList handlers. 158 friend class ErrorList; 159 160 // handleErrors needs to be able to set the Checked flag. 161 template <typename... HandlerTs> 162 friend Error handleErrors(Error E, HandlerTs &&... Handlers); 163 164 // Expected<T> needs to be able to steal the payload when constructed from an 165 // error. 166 template <typename T> friend class Expected; 167 168 // wrap needs to be able to steal the payload. 169 friend LLVMErrorRef wrap(Error); 170 171 protected: 172 /// Create a success value. Prefer using 'Error::success()' for readability 173 Error() { 174 setPtr(nullptr); 175 setChecked(false); 176 } 177 178 public: 179 /// Create a success value. 180 static ErrorSuccess success(); 181 182 // Errors are not copy-constructable. 183 Error(const Error &Other) = delete; 184 185 /// Move-construct an error value. The newly constructed error is considered 186 /// unchecked, even if the source error had been checked. The original error 187 /// becomes a checked Success value, regardless of its original state. 188 Error(Error &&Other) { 189 setChecked(true); 190 *this = std::move(Other); 191 } 192 193 /// Create an error value. Prefer using the 'make_error' function, but 194 /// this constructor can be useful when "re-throwing" errors from handlers. 195 Error(std::unique_ptr<ErrorInfoBase> Payload) { 196 setPtr(Payload.release()); 197 setChecked(false); 198 } 199 200 // Errors are not copy-assignable. 201 Error &operator=(const Error &Other) = delete; 202 203 /// Move-assign an error value. The current error must represent success, you 204 /// you cannot overwrite an unhandled error. The current error is then 205 /// considered unchecked. The source error becomes a checked success value, 206 /// regardless of its original state. 207 Error &operator=(Error &&Other) { 208 // Don't allow overwriting of unchecked values. 209 assertIsChecked(); 210 setPtr(Other.getPtr()); 211 212 // This Error is unchecked, even if the source error was checked. 213 setChecked(false); 214 215 // Null out Other's payload and set its checked bit. 216 Other.setPtr(nullptr); 217 Other.setChecked(true); 218 219 return *this; 220 } 221 222 /// Destroy a Error. Fails with a call to abort() if the error is 223 /// unchecked. 224 ~Error() { 225 assertIsChecked(); 226 delete getPtr(); 227 } 228 229 /// Bool conversion. Returns true if this Error is in a failure state, 230 /// and false if it is in an accept state. If the error is in a Success state 231 /// it will be considered checked. 232 explicit operator bool() { 233 setChecked(getPtr() == nullptr); 234 return getPtr() != nullptr; 235 } 236 237 /// Check whether one error is a subclass of another. 238 template <typename ErrT> bool isA() const { 239 return getPtr() && getPtr()->isA(ErrT::classID()); 240 } 241 242 /// Returns the dynamic class id of this error, or null if this is a success 243 /// value. 244 const void* dynamicClassID() const { 245 if (!getPtr()) 246 return nullptr; 247 return getPtr()->dynamicClassID(); 248 } 249 250 private: 251 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 252 // assertIsChecked() happens very frequently, but under normal circumstances 253 // is supposed to be a no-op. So we want it to be inlined, but having a bunch 254 // of debug prints can cause the function to be too large for inlining. So 255 // it's important that we define this function out of line so that it can't be 256 // inlined. 257 [[noreturn]] void fatalUncheckedError() const; 258 #endif 259 260 void assertIsChecked() { 261 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 262 if (LLVM_UNLIKELY(!getChecked() || getPtr())) 263 fatalUncheckedError(); 264 #endif 265 } 266 267 ErrorInfoBase *getPtr() const { 268 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 269 return reinterpret_cast<ErrorInfoBase*>( 270 reinterpret_cast<uintptr_t>(Payload) & 271 ~static_cast<uintptr_t>(0x1)); 272 #else 273 return Payload; 274 #endif 275 } 276 277 void setPtr(ErrorInfoBase *EI) { 278 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 279 Payload = reinterpret_cast<ErrorInfoBase*>( 280 (reinterpret_cast<uintptr_t>(EI) & 281 ~static_cast<uintptr_t>(0x1)) | 282 (reinterpret_cast<uintptr_t>(Payload) & 0x1)); 283 #else 284 Payload = EI; 285 #endif 286 } 287 288 bool getChecked() const { 289 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 290 return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0; 291 #else 292 return true; 293 #endif 294 } 295 296 void setChecked(bool V) { 297 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 298 Payload = reinterpret_cast<ErrorInfoBase*>( 299 (reinterpret_cast<uintptr_t>(Payload) & 300 ~static_cast<uintptr_t>(0x1)) | 301 (V ? 0 : 1)); 302 #endif 303 } 304 305 std::unique_ptr<ErrorInfoBase> takePayload() { 306 std::unique_ptr<ErrorInfoBase> Tmp(getPtr()); 307 setPtr(nullptr); 308 setChecked(true); 309 return Tmp; 310 } 311 312 friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) { 313 if (auto *P = E.getPtr()) 314 P->log(OS); 315 else 316 OS << "success"; 317 return OS; 318 } 319 320 ErrorInfoBase *Payload = nullptr; 321 }; 322 323 /// Subclass of Error for the sole purpose of identifying the success path in 324 /// the type system. This allows to catch invalid conversion to Expected<T> at 325 /// compile time. 326 class ErrorSuccess final : public Error {}; 327 328 inline ErrorSuccess Error::success() { return ErrorSuccess(); } 329 330 /// Make a Error instance representing failure using the given error info 331 /// type. 332 template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) { 333 return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...)); 334 } 335 336 /// Base class for user error types. Users should declare their error types 337 /// like: 338 /// 339 /// class MyError : public ErrorInfo<MyError> { 340 /// .... 341 /// }; 342 /// 343 /// This class provides an implementation of the ErrorInfoBase::kind 344 /// method, which is used by the Error RTTI system. 345 template <typename ThisErrT, typename ParentErrT = ErrorInfoBase> 346 class ErrorInfo : public ParentErrT { 347 public: 348 using ParentErrT::ParentErrT; // inherit constructors 349 350 static const void *classID() { return &ThisErrT::ID; } 351 352 const void *dynamicClassID() const override { return &ThisErrT::ID; } 353 354 bool isA(const void *const ClassID) const override { 355 return ClassID == classID() || ParentErrT::isA(ClassID); 356 } 357 }; 358 359 /// Special ErrorInfo subclass representing a list of ErrorInfos. 360 /// Instances of this class are constructed by joinError. 361 class ErrorList final : public ErrorInfo<ErrorList> { 362 // handleErrors needs to be able to iterate the payload list of an 363 // ErrorList. 364 template <typename... HandlerTs> 365 friend Error handleErrors(Error E, HandlerTs &&... Handlers); 366 367 // joinErrors is implemented in terms of join. 368 friend Error joinErrors(Error, Error); 369 370 public: 371 void log(raw_ostream &OS) const override { 372 OS << "Multiple errors:\n"; 373 for (const auto &ErrPayload : Payloads) { 374 ErrPayload->log(OS); 375 OS << "\n"; 376 } 377 } 378 379 std::error_code convertToErrorCode() const override; 380 381 // Used by ErrorInfo::classID. 382 static char ID; 383 384 private: 385 ErrorList(std::unique_ptr<ErrorInfoBase> Payload1, 386 std::unique_ptr<ErrorInfoBase> Payload2) { 387 assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() && 388 "ErrorList constructor payloads should be singleton errors"); 389 Payloads.push_back(std::move(Payload1)); 390 Payloads.push_back(std::move(Payload2)); 391 } 392 393 static Error join(Error E1, Error E2) { 394 if (!E1) 395 return E2; 396 if (!E2) 397 return E1; 398 if (E1.isA<ErrorList>()) { 399 auto &E1List = static_cast<ErrorList &>(*E1.getPtr()); 400 if (E2.isA<ErrorList>()) { 401 auto E2Payload = E2.takePayload(); 402 auto &E2List = static_cast<ErrorList &>(*E2Payload); 403 for (auto &Payload : E2List.Payloads) 404 E1List.Payloads.push_back(std::move(Payload)); 405 } else 406 E1List.Payloads.push_back(E2.takePayload()); 407 408 return E1; 409 } 410 if (E2.isA<ErrorList>()) { 411 auto &E2List = static_cast<ErrorList &>(*E2.getPtr()); 412 E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload()); 413 return E2; 414 } 415 return Error(std::unique_ptr<ErrorList>( 416 new ErrorList(E1.takePayload(), E2.takePayload()))); 417 } 418 419 std::vector<std::unique_ptr<ErrorInfoBase>> Payloads; 420 }; 421 422 /// Concatenate errors. The resulting Error is unchecked, and contains the 423 /// ErrorInfo(s), if any, contained in E1, followed by the 424 /// ErrorInfo(s), if any, contained in E2. 425 inline Error joinErrors(Error E1, Error E2) { 426 return ErrorList::join(std::move(E1), std::move(E2)); 427 } 428 429 /// Tagged union holding either a T or a Error. 430 /// 431 /// This class parallels ErrorOr, but replaces error_code with Error. Since 432 /// Error cannot be copied, this class replaces getError() with 433 /// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the 434 /// error class type. 435 /// 436 /// Example usage of 'Expected<T>' as a function return type: 437 /// 438 /// @code{.cpp} 439 /// Expected<int> myDivide(int A, int B) { 440 /// if (B == 0) { 441 /// // return an Error 442 /// return createStringError(inconvertibleErrorCode(), 443 /// "B must not be zero!"); 444 /// } 445 /// // return an integer 446 /// return A / B; 447 /// } 448 /// @endcode 449 /// 450 /// Checking the results of to a function returning 'Expected<T>': 451 /// @code{.cpp} 452 /// if (auto E = Result.takeError()) { 453 /// // We must consume the error. Typically one of: 454 /// // - return the error to our caller 455 /// // - toString(), when logging 456 /// // - consumeError(), to silently swallow the error 457 /// // - handleErrors(), to distinguish error types 458 /// errs() << "Problem with division " << toString(std::move(E)) << "\n"; 459 /// return; 460 /// } 461 /// // use the result 462 /// outs() << "The answer is " << *Result << "\n"; 463 /// @endcode 464 /// 465 /// For unit-testing a function returning an 'Expected<T>', see the 466 /// 'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h 467 468 template <class T> class [[nodiscard]] Expected { 469 template <class T1> friend class ExpectedAsOutParameter; 470 template <class OtherT> friend class Expected; 471 472 static constexpr bool isRef = std::is_reference_v<T>; 473 474 using wrap = std::reference_wrapper<std::remove_reference_t<T>>; 475 476 using error_type = std::unique_ptr<ErrorInfoBase>; 477 478 public: 479 using storage_type = std::conditional_t<isRef, wrap, T>; 480 using value_type = T; 481 482 private: 483 using reference = std::remove_reference_t<T> &; 484 using const_reference = const std::remove_reference_t<T> &; 485 using pointer = std::remove_reference_t<T> *; 486 using const_pointer = const std::remove_reference_t<T> *; 487 488 public: 489 /// Create an Expected<T> error value from the given Error. 490 Expected(Error Err) 491 : HasError(true) 492 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 493 // Expected is unchecked upon construction in Debug builds. 494 , Unchecked(true) 495 #endif 496 { 497 assert(Err && "Cannot create Expected<T> from Error success value."); 498 new (getErrorStorage()) error_type(Err.takePayload()); 499 } 500 501 /// Forbid to convert from Error::success() implicitly, this avoids having 502 /// Expected<T> foo() { return Error::success(); } which compiles otherwise 503 /// but triggers the assertion above. 504 Expected(ErrorSuccess) = delete; 505 506 /// Create an Expected<T> success value from the given OtherT value, which 507 /// must be convertible to T. 508 template <typename OtherT> 509 Expected(OtherT &&Val, 510 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) 511 : HasError(false) 512 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 513 // Expected is unchecked upon construction in Debug builds. 514 , 515 Unchecked(true) 516 #endif 517 { 518 new (getStorage()) storage_type(std::forward<OtherT>(Val)); 519 } 520 521 /// Move construct an Expected<T> value. 522 Expected(Expected &&Other) { moveConstruct(std::move(Other)); } 523 524 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 525 /// must be convertible to T. 526 template <class OtherT> 527 Expected(Expected<OtherT> &&Other, 528 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) { 529 moveConstruct(std::move(Other)); 530 } 531 532 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 533 /// isn't convertible to T. 534 template <class OtherT> 535 explicit Expected( 536 Expected<OtherT> &&Other, 537 std::enable_if_t<!std::is_convertible_v<OtherT, T>> * = nullptr) { 538 moveConstruct(std::move(Other)); 539 } 540 541 /// Move-assign from another Expected<T>. 542 Expected &operator=(Expected &&Other) { 543 moveAssign(std::move(Other)); 544 return *this; 545 } 546 547 /// Destroy an Expected<T>. 548 ~Expected() { 549 assertIsChecked(); 550 if (!HasError) 551 getStorage()->~storage_type(); 552 else 553 getErrorStorage()->~error_type(); 554 } 555 556 /// Return false if there is an error. 557 explicit operator bool() { 558 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 559 Unchecked = HasError; 560 #endif 561 return !HasError; 562 } 563 564 /// Returns a reference to the stored T value. 565 reference get() { 566 assertIsChecked(); 567 return *getStorage(); 568 } 569 570 /// Returns a const reference to the stored T value. 571 const_reference get() const { 572 assertIsChecked(); 573 return const_cast<Expected<T> *>(this)->get(); 574 } 575 576 /// Returns \a takeError() after moving the held T (if any) into \p V. 577 template <class OtherT> 578 Error moveInto( 579 OtherT &Value, 580 std::enable_if_t<std::is_assignable_v<OtherT &, T &&>> * = nullptr) && { 581 if (*this) 582 Value = std::move(get()); 583 return takeError(); 584 } 585 586 /// Check that this Expected<T> is an error of type ErrT. 587 template <typename ErrT> bool errorIsA() const { 588 return HasError && (*getErrorStorage())->template isA<ErrT>(); 589 } 590 591 /// Take ownership of the stored error. 592 /// After calling this the Expected<T> is in an indeterminate state that can 593 /// only be safely destructed. No further calls (beside the destructor) should 594 /// be made on the Expected<T> value. 595 Error takeError() { 596 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 597 Unchecked = false; 598 #endif 599 return HasError ? Error(std::move(*getErrorStorage())) : Error::success(); 600 } 601 602 /// Returns a pointer to the stored T value. 603 pointer operator->() { 604 assertIsChecked(); 605 return toPointer(getStorage()); 606 } 607 608 /// Returns a const pointer to the stored T value. 609 const_pointer operator->() const { 610 assertIsChecked(); 611 return toPointer(getStorage()); 612 } 613 614 /// Returns a reference to the stored T value. 615 reference operator*() { 616 assertIsChecked(); 617 return *getStorage(); 618 } 619 620 /// Returns a const reference to the stored T value. 621 const_reference operator*() const { 622 assertIsChecked(); 623 return *getStorage(); 624 } 625 626 private: 627 template <class T1> 628 static bool compareThisIfSameType(const T1 &a, const T1 &b) { 629 return &a == &b; 630 } 631 632 template <class T1, class T2> 633 static bool compareThisIfSameType(const T1 &, const T2 &) { 634 return false; 635 } 636 637 template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) { 638 HasError = Other.HasError; 639 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 640 Unchecked = true; 641 Other.Unchecked = false; 642 #endif 643 644 if (!HasError) 645 new (getStorage()) storage_type(std::move(*Other.getStorage())); 646 else 647 new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage())); 648 } 649 650 template <class OtherT> void moveAssign(Expected<OtherT> &&Other) { 651 assertIsChecked(); 652 653 if (compareThisIfSameType(*this, Other)) 654 return; 655 656 this->~Expected(); 657 new (this) Expected(std::move(Other)); 658 } 659 660 pointer toPointer(pointer Val) { return Val; } 661 662 const_pointer toPointer(const_pointer Val) const { return Val; } 663 664 pointer toPointer(wrap *Val) { return &Val->get(); } 665 666 const_pointer toPointer(const wrap *Val) const { return &Val->get(); } 667 668 storage_type *getStorage() { 669 assert(!HasError && "Cannot get value when an error exists!"); 670 return reinterpret_cast<storage_type *>(&TStorage); 671 } 672 673 const storage_type *getStorage() const { 674 assert(!HasError && "Cannot get value when an error exists!"); 675 return reinterpret_cast<const storage_type *>(&TStorage); 676 } 677 678 error_type *getErrorStorage() { 679 assert(HasError && "Cannot get error when a value exists!"); 680 return reinterpret_cast<error_type *>(&ErrorStorage); 681 } 682 683 const error_type *getErrorStorage() const { 684 assert(HasError && "Cannot get error when a value exists!"); 685 return reinterpret_cast<const error_type *>(&ErrorStorage); 686 } 687 688 // Used by ExpectedAsOutParameter to reset the checked flag. 689 void setUnchecked() { 690 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 691 Unchecked = true; 692 #endif 693 } 694 695 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 696 [[noreturn]] LLVM_ATTRIBUTE_NOINLINE void fatalUncheckedExpected() const { 697 dbgs() << "Expected<T> must be checked before access or destruction.\n"; 698 if (HasError) { 699 dbgs() << "Unchecked Expected<T> contained error:\n"; 700 (*getErrorStorage())->log(dbgs()); 701 } else 702 dbgs() << "Expected<T> value was in success state. (Note: Expected<T> " 703 "values in success mode must still be checked prior to being " 704 "destroyed).\n"; 705 abort(); 706 } 707 #endif 708 709 void assertIsChecked() const { 710 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 711 if (LLVM_UNLIKELY(Unchecked)) 712 fatalUncheckedExpected(); 713 #endif 714 } 715 716 union { 717 AlignedCharArrayUnion<storage_type> TStorage; 718 AlignedCharArrayUnion<error_type> ErrorStorage; 719 }; 720 bool HasError : 1; 721 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 722 bool Unchecked : 1; 723 #endif 724 }; 725 726 /// Report a serious error, calling any installed error handler. See 727 /// ErrorHandling.h. 728 [[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true); 729 730 /// Report a fatal error if Err is a failure value. 731 /// 732 /// This function can be used to wrap calls to fallible functions ONLY when it 733 /// is known that the Error will always be a success value. E.g. 734 /// 735 /// @code{.cpp} 736 /// // foo only attempts the fallible operation if DoFallibleOperation is 737 /// // true. If DoFallibleOperation is false then foo always returns 738 /// // Error::success(). 739 /// Error foo(bool DoFallibleOperation); 740 /// 741 /// cantFail(foo(false)); 742 /// @endcode 743 inline void cantFail(Error Err, const char *Msg = nullptr) { 744 if (Err) { 745 if (!Msg) 746 Msg = "Failure value returned from cantFail wrapped call"; 747 #ifndef NDEBUG 748 std::string Str; 749 raw_string_ostream OS(Str); 750 OS << Msg << "\n" << Err; 751 Msg = OS.str().c_str(); 752 #endif 753 llvm_unreachable(Msg); 754 } 755 } 756 757 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 758 /// returns the contained value. 759 /// 760 /// This function can be used to wrap calls to fallible functions ONLY when it 761 /// is known that the Error will always be a success value. E.g. 762 /// 763 /// @code{.cpp} 764 /// // foo only attempts the fallible operation if DoFallibleOperation is 765 /// // true. If DoFallibleOperation is false then foo always returns an int. 766 /// Expected<int> foo(bool DoFallibleOperation); 767 /// 768 /// int X = cantFail(foo(false)); 769 /// @endcode 770 template <typename T> 771 T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) { 772 if (ValOrErr) 773 return std::move(*ValOrErr); 774 else { 775 if (!Msg) 776 Msg = "Failure value returned from cantFail wrapped call"; 777 #ifndef NDEBUG 778 std::string Str; 779 raw_string_ostream OS(Str); 780 auto E = ValOrErr.takeError(); 781 OS << Msg << "\n" << E; 782 Msg = OS.str().c_str(); 783 #endif 784 llvm_unreachable(Msg); 785 } 786 } 787 788 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 789 /// returns the contained reference. 790 /// 791 /// This function can be used to wrap calls to fallible functions ONLY when it 792 /// is known that the Error will always be a success value. E.g. 793 /// 794 /// @code{.cpp} 795 /// // foo only attempts the fallible operation if DoFallibleOperation is 796 /// // true. If DoFallibleOperation is false then foo always returns a Bar&. 797 /// Expected<Bar&> foo(bool DoFallibleOperation); 798 /// 799 /// Bar &X = cantFail(foo(false)); 800 /// @endcode 801 template <typename T> 802 T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) { 803 if (ValOrErr) 804 return *ValOrErr; 805 else { 806 if (!Msg) 807 Msg = "Failure value returned from cantFail wrapped call"; 808 #ifndef NDEBUG 809 std::string Str; 810 raw_string_ostream OS(Str); 811 auto E = ValOrErr.takeError(); 812 OS << Msg << "\n" << E; 813 Msg = OS.str().c_str(); 814 #endif 815 llvm_unreachable(Msg); 816 } 817 } 818 819 /// Helper for testing applicability of, and applying, handlers for 820 /// ErrorInfo types. 821 template <typename HandlerT> 822 class ErrorHandlerTraits 823 : public ErrorHandlerTraits< 824 decltype(&std::remove_reference_t<HandlerT>::operator())> {}; 825 826 // Specialization functions of the form 'Error (const ErrT&)'. 827 template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> { 828 public: 829 static bool appliesTo(const ErrorInfoBase &E) { 830 return E.template isA<ErrT>(); 831 } 832 833 template <typename HandlerT> 834 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 835 assert(appliesTo(*E) && "Applying incorrect handler"); 836 return H(static_cast<ErrT &>(*E)); 837 } 838 }; 839 840 // Specialization functions of the form 'void (const ErrT&)'. 841 template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> { 842 public: 843 static bool appliesTo(const ErrorInfoBase &E) { 844 return E.template isA<ErrT>(); 845 } 846 847 template <typename HandlerT> 848 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 849 assert(appliesTo(*E) && "Applying incorrect handler"); 850 H(static_cast<ErrT &>(*E)); 851 return Error::success(); 852 } 853 }; 854 855 /// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'. 856 template <typename ErrT> 857 class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> { 858 public: 859 static bool appliesTo(const ErrorInfoBase &E) { 860 return E.template isA<ErrT>(); 861 } 862 863 template <typename HandlerT> 864 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 865 assert(appliesTo(*E) && "Applying incorrect handler"); 866 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 867 return H(std::move(SubE)); 868 } 869 }; 870 871 /// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'. 872 template <typename ErrT> 873 class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> { 874 public: 875 static bool appliesTo(const ErrorInfoBase &E) { 876 return E.template isA<ErrT>(); 877 } 878 879 template <typename HandlerT> 880 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 881 assert(appliesTo(*E) && "Applying incorrect handler"); 882 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 883 H(std::move(SubE)); 884 return Error::success(); 885 } 886 }; 887 888 // Specialization for member functions of the form 'RetT (const ErrT&)'. 889 template <typename C, typename RetT, typename ErrT> 890 class ErrorHandlerTraits<RetT (C::*)(ErrT &)> 891 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 892 893 // Specialization for member functions of the form 'RetT (const ErrT&) const'. 894 template <typename C, typename RetT, typename ErrT> 895 class ErrorHandlerTraits<RetT (C::*)(ErrT &) const> 896 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 897 898 // Specialization for member functions of the form 'RetT (const ErrT&)'. 899 template <typename C, typename RetT, typename ErrT> 900 class ErrorHandlerTraits<RetT (C::*)(const ErrT &)> 901 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 902 903 // Specialization for member functions of the form 'RetT (const ErrT&) const'. 904 template <typename C, typename RetT, typename ErrT> 905 class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const> 906 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 907 908 /// Specialization for member functions of the form 909 /// 'RetT (std::unique_ptr<ErrT>)'. 910 template <typename C, typename RetT, typename ErrT> 911 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)> 912 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 913 914 /// Specialization for member functions of the form 915 /// 'RetT (std::unique_ptr<ErrT>) const'. 916 template <typename C, typename RetT, typename ErrT> 917 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const> 918 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 919 920 inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) { 921 return Error(std::move(Payload)); 922 } 923 924 template <typename HandlerT, typename... HandlerTs> 925 Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload, 926 HandlerT &&Handler, HandlerTs &&... Handlers) { 927 if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload)) 928 return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler), 929 std::move(Payload)); 930 return handleErrorImpl(std::move(Payload), 931 std::forward<HandlerTs>(Handlers)...); 932 } 933 934 /// Pass the ErrorInfo(s) contained in E to their respective handlers. Any 935 /// unhandled errors (or Errors returned by handlers) are re-concatenated and 936 /// returned. 937 /// Because this function returns an error, its result must also be checked 938 /// or returned. If you intend to handle all errors use handleAllErrors 939 /// (which returns void, and will abort() on unhandled errors) instead. 940 template <typename... HandlerTs> 941 Error handleErrors(Error E, HandlerTs &&... Hs) { 942 if (!E) 943 return Error::success(); 944 945 std::unique_ptr<ErrorInfoBase> Payload = E.takePayload(); 946 947 if (Payload->isA<ErrorList>()) { 948 ErrorList &List = static_cast<ErrorList &>(*Payload); 949 Error R; 950 for (auto &P : List.Payloads) 951 R = ErrorList::join( 952 std::move(R), 953 handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...)); 954 return R; 955 } 956 957 return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...); 958 } 959 960 /// Behaves the same as handleErrors, except that by contract all errors 961 /// *must* be handled by the given handlers (i.e. there must be no remaining 962 /// errors after running the handlers, or llvm_unreachable is called). 963 template <typename... HandlerTs> 964 void handleAllErrors(Error E, HandlerTs &&... Handlers) { 965 cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...)); 966 } 967 968 /// Check that E is a non-error, then drop it. 969 /// If E is an error, llvm_unreachable will be called. 970 inline void handleAllErrors(Error E) { 971 cantFail(std::move(E)); 972 } 973 974 /// Handle any errors (if present) in an Expected<T>, then try a recovery path. 975 /// 976 /// If the incoming value is a success value it is returned unmodified. If it 977 /// is a failure value then it the contained error is passed to handleErrors. 978 /// If handleErrors is able to handle the error then the RecoveryPath functor 979 /// is called to supply the final result. If handleErrors is not able to 980 /// handle all errors then the unhandled errors are returned. 981 /// 982 /// This utility enables the follow pattern: 983 /// 984 /// @code{.cpp} 985 /// enum FooStrategy { Aggressive, Conservative }; 986 /// Expected<Foo> foo(FooStrategy S); 987 /// 988 /// auto ResultOrErr = 989 /// handleExpected( 990 /// foo(Aggressive), 991 /// []() { return foo(Conservative); }, 992 /// [](AggressiveStrategyError&) { 993 /// // Implicitly conusme this - we'll recover by using a conservative 994 /// // strategy. 995 /// }); 996 /// 997 /// @endcode 998 template <typename T, typename RecoveryFtor, typename... HandlerTs> 999 Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath, 1000 HandlerTs &&... Handlers) { 1001 if (ValOrErr) 1002 return ValOrErr; 1003 1004 if (auto Err = handleErrors(ValOrErr.takeError(), 1005 std::forward<HandlerTs>(Handlers)...)) 1006 return std::move(Err); 1007 1008 return RecoveryPath(); 1009 } 1010 1011 /// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner 1012 /// will be printed before the first one is logged. A newline will be printed 1013 /// after each error. 1014 /// 1015 /// This function is compatible with the helpers from Support/WithColor.h. You 1016 /// can pass any of them as the OS. Please consider using them instead of 1017 /// including 'error: ' in the ErrorBanner. 1018 /// 1019 /// This is useful in the base level of your program to allow clean termination 1020 /// (allowing clean deallocation of resources, etc.), while reporting error 1021 /// information to the user. 1022 void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {}); 1023 1024 /// Write all error messages (if any) in E to a string. The newline character 1025 /// is used to separate error messages. 1026 std::string toString(Error E); 1027 1028 /// Consume a Error without doing anything. This method should be used 1029 /// only where an error can be considered a reasonable and expected return 1030 /// value. 1031 /// 1032 /// Uses of this method are potentially indicative of design problems: If it's 1033 /// legitimate to do nothing while processing an "error", the error-producer 1034 /// might be more clearly refactored to return an std::optional<T>. 1035 inline void consumeError(Error Err) { 1036 handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {}); 1037 } 1038 1039 /// Convert an Expected to an Optional without doing anything. This method 1040 /// should be used only where an error can be considered a reasonable and 1041 /// expected return value. 1042 /// 1043 /// Uses of this method are potentially indicative of problems: perhaps the 1044 /// error should be propagated further, or the error-producer should just 1045 /// return an Optional in the first place. 1046 template <typename T> std::optional<T> expectedToOptional(Expected<T> &&E) { 1047 if (E) 1048 return std::move(*E); 1049 consumeError(E.takeError()); 1050 return std::nullopt; 1051 } 1052 1053 template <typename T> std::optional<T> expectedToStdOptional(Expected<T> &&E) { 1054 if (E) 1055 return std::move(*E); 1056 consumeError(E.takeError()); 1057 return std::nullopt; 1058 } 1059 1060 /// Helper for converting an Error to a bool. 1061 /// 1062 /// This method returns true if Err is in an error state, or false if it is 1063 /// in a success state. Puts Err in a checked state in both cases (unlike 1064 /// Error::operator bool(), which only does this for success states). 1065 inline bool errorToBool(Error Err) { 1066 bool IsError = static_cast<bool>(Err); 1067 if (IsError) 1068 consumeError(std::move(Err)); 1069 return IsError; 1070 } 1071 1072 /// Helper for Errors used as out-parameters. 1073 /// 1074 /// This helper is for use with the Error-as-out-parameter idiom, where an error 1075 /// is passed to a function or method by reference, rather than being returned. 1076 /// In such cases it is helpful to set the checked bit on entry to the function 1077 /// so that the error can be written to (unchecked Errors abort on assignment) 1078 /// and clear the checked bit on exit so that clients cannot accidentally forget 1079 /// to check the result. This helper performs these actions automatically using 1080 /// RAII: 1081 /// 1082 /// @code{.cpp} 1083 /// Result foo(Error &Err) { 1084 /// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set 1085 /// // <body of foo> 1086 /// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed. 1087 /// } 1088 /// @endcode 1089 /// 1090 /// ErrorAsOutParameter takes an Error* rather than Error& so that it can be 1091 /// used with optional Errors (Error pointers that are allowed to be null). If 1092 /// ErrorAsOutParameter took an Error reference, an instance would have to be 1093 /// created inside every condition that verified that Error was non-null. By 1094 /// taking an Error pointer we can just create one instance at the top of the 1095 /// function. 1096 class ErrorAsOutParameter { 1097 public: 1098 ErrorAsOutParameter(Error *Err) : Err(Err) { 1099 // Raise the checked bit if Err is success. 1100 if (Err) 1101 (void)!!*Err; 1102 } 1103 1104 ~ErrorAsOutParameter() { 1105 // Clear the checked bit. 1106 if (Err && !*Err) 1107 *Err = Error::success(); 1108 } 1109 1110 private: 1111 Error *Err; 1112 }; 1113 1114 /// Helper for Expected<T>s used as out-parameters. 1115 /// 1116 /// See ErrorAsOutParameter. 1117 template <typename T> 1118 class ExpectedAsOutParameter { 1119 public: 1120 ExpectedAsOutParameter(Expected<T> *ValOrErr) 1121 : ValOrErr(ValOrErr) { 1122 if (ValOrErr) 1123 (void)!!*ValOrErr; 1124 } 1125 1126 ~ExpectedAsOutParameter() { 1127 if (ValOrErr) 1128 ValOrErr->setUnchecked(); 1129 } 1130 1131 private: 1132 Expected<T> *ValOrErr; 1133 }; 1134 1135 /// This class wraps a std::error_code in a Error. 1136 /// 1137 /// This is useful if you're writing an interface that returns a Error 1138 /// (or Expected) and you want to call code that still returns 1139 /// std::error_codes. 1140 class ECError : public ErrorInfo<ECError> { 1141 friend Error errorCodeToError(std::error_code); 1142 1143 void anchor() override; 1144 1145 public: 1146 void setErrorCode(std::error_code EC) { this->EC = EC; } 1147 std::error_code convertToErrorCode() const override { return EC; } 1148 void log(raw_ostream &OS) const override { OS << EC.message(); } 1149 1150 // Used by ErrorInfo::classID. 1151 static char ID; 1152 1153 protected: 1154 ECError() = default; 1155 ECError(std::error_code EC) : EC(EC) {} 1156 1157 std::error_code EC; 1158 }; 1159 1160 /// The value returned by this function can be returned from convertToErrorCode 1161 /// for Error values where no sensible translation to std::error_code exists. 1162 /// It should only be used in this situation, and should never be used where a 1163 /// sensible conversion to std::error_code is available, as attempts to convert 1164 /// to/from this error will result in a fatal error. (i.e. it is a programmatic 1165 /// error to try to convert such a value). 1166 std::error_code inconvertibleErrorCode(); 1167 1168 /// Helper for converting an std::error_code to a Error. 1169 Error errorCodeToError(std::error_code EC); 1170 1171 /// Helper for converting an ECError to a std::error_code. 1172 /// 1173 /// This method requires that Err be Error() or an ECError, otherwise it 1174 /// will trigger a call to abort(). 1175 std::error_code errorToErrorCode(Error Err); 1176 1177 /// Convert an ErrorOr<T> to an Expected<T>. 1178 template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) { 1179 if (auto EC = EO.getError()) 1180 return errorCodeToError(EC); 1181 return std::move(*EO); 1182 } 1183 1184 /// Convert an Expected<T> to an ErrorOr<T>. 1185 template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) { 1186 if (auto Err = E.takeError()) 1187 return errorToErrorCode(std::move(Err)); 1188 return std::move(*E); 1189 } 1190 1191 /// This class wraps a string in an Error. 1192 /// 1193 /// StringError is useful in cases where the client is not expected to be able 1194 /// to consume the specific error message programmatically (for example, if the 1195 /// error message is to be presented to the user). 1196 /// 1197 /// StringError can also be used when additional information is to be printed 1198 /// along with a error_code message. Depending on the constructor called, this 1199 /// class can either display: 1200 /// 1. the error_code message (ECError behavior) 1201 /// 2. a string 1202 /// 3. the error_code message and a string 1203 /// 1204 /// These behaviors are useful when subtyping is required; for example, when a 1205 /// specific library needs an explicit error type. In the example below, 1206 /// PDBError is derived from StringError: 1207 /// 1208 /// @code{.cpp} 1209 /// Expected<int> foo() { 1210 /// return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading, 1211 /// "Additional information"); 1212 /// } 1213 /// @endcode 1214 /// 1215 class StringError : public ErrorInfo<StringError> { 1216 public: 1217 static char ID; 1218 1219 // Prints EC + S and converts to EC 1220 StringError(std::error_code EC, const Twine &S = Twine()); 1221 1222 // Prints S and converts to EC 1223 StringError(const Twine &S, std::error_code EC); 1224 1225 void log(raw_ostream &OS) const override; 1226 std::error_code convertToErrorCode() const override; 1227 1228 const std::string &getMessage() const { return Msg; } 1229 1230 private: 1231 std::string Msg; 1232 std::error_code EC; 1233 const bool PrintMsgOnly = false; 1234 }; 1235 1236 /// Create formatted StringError object. 1237 template <typename... Ts> 1238 inline Error createStringError(std::error_code EC, char const *Fmt, 1239 const Ts &... Vals) { 1240 std::string Buffer; 1241 raw_string_ostream Stream(Buffer); 1242 Stream << format(Fmt, Vals...); 1243 return make_error<StringError>(Stream.str(), EC); 1244 } 1245 1246 Error createStringError(std::error_code EC, char const *Msg); 1247 1248 inline Error createStringError(std::error_code EC, const Twine &S) { 1249 return createStringError(EC, S.str().c_str()); 1250 } 1251 1252 template <typename... Ts> 1253 inline Error createStringError(std::errc EC, char const *Fmt, 1254 const Ts &... Vals) { 1255 return createStringError(std::make_error_code(EC), Fmt, Vals...); 1256 } 1257 1258 /// This class wraps a filename and another Error. 1259 /// 1260 /// In some cases, an error needs to live along a 'source' name, in order to 1261 /// show more detailed information to the user. 1262 class FileError final : public ErrorInfo<FileError> { 1263 1264 friend Error createFileError(const Twine &, Error); 1265 friend Error createFileError(const Twine &, size_t, Error); 1266 1267 public: 1268 void log(raw_ostream &OS) const override { 1269 assert(Err && "Trying to log after takeError()."); 1270 OS << "'" << FileName << "': "; 1271 if (Line) 1272 OS << "line " << *Line << ": "; 1273 Err->log(OS); 1274 } 1275 1276 std::string messageWithoutFileInfo() const { 1277 std::string Msg; 1278 raw_string_ostream OS(Msg); 1279 Err->log(OS); 1280 return OS.str(); 1281 } 1282 1283 StringRef getFileName() const { return FileName; } 1284 1285 Error takeError() { return Error(std::move(Err)); } 1286 1287 std::error_code convertToErrorCode() const override; 1288 1289 // Used by ErrorInfo::classID. 1290 static char ID; 1291 1292 private: 1293 FileError(const Twine &F, std::optional<size_t> LineNum, 1294 std::unique_ptr<ErrorInfoBase> E) { 1295 assert(E && "Cannot create FileError from Error success value."); 1296 FileName = F.str(); 1297 Err = std::move(E); 1298 Line = std::move(LineNum); 1299 } 1300 1301 static Error build(const Twine &F, std::optional<size_t> Line, Error E) { 1302 std::unique_ptr<ErrorInfoBase> Payload; 1303 handleAllErrors(std::move(E), 1304 [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error { 1305 Payload = std::move(EIB); 1306 return Error::success(); 1307 }); 1308 return Error( 1309 std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload)))); 1310 } 1311 1312 std::string FileName; 1313 std::optional<size_t> Line; 1314 std::unique_ptr<ErrorInfoBase> Err; 1315 }; 1316 1317 /// Concatenate a source file path and/or name with an Error. The resulting 1318 /// Error is unchecked. 1319 inline Error createFileError(const Twine &F, Error E) { 1320 return FileError::build(F, std::optional<size_t>(), std::move(E)); 1321 } 1322 1323 /// Concatenate a source file path and/or name with line number and an Error. 1324 /// The resulting Error is unchecked. 1325 inline Error createFileError(const Twine &F, size_t Line, Error E) { 1326 return FileError::build(F, std::optional<size_t>(Line), std::move(E)); 1327 } 1328 1329 /// Concatenate a source file path and/or name with a std::error_code 1330 /// to form an Error object. 1331 inline Error createFileError(const Twine &F, std::error_code EC) { 1332 return createFileError(F, errorCodeToError(EC)); 1333 } 1334 1335 /// Concatenate a source file path and/or name with line number and 1336 /// std::error_code to form an Error object. 1337 inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) { 1338 return createFileError(F, Line, errorCodeToError(EC)); 1339 } 1340 1341 Error createFileError(const Twine &F, ErrorSuccess) = delete; 1342 1343 /// Helper for check-and-exit error handling. 1344 /// 1345 /// For tool use only. NOT FOR USE IN LIBRARY CODE. 1346 /// 1347 class ExitOnError { 1348 public: 1349 /// Create an error on exit helper. 1350 ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1) 1351 : Banner(std::move(Banner)), 1352 GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {} 1353 1354 /// Set the banner string for any errors caught by operator(). 1355 void setBanner(std::string Banner) { this->Banner = std::move(Banner); } 1356 1357 /// Set the exit-code mapper function. 1358 void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) { 1359 this->GetExitCode = std::move(GetExitCode); 1360 } 1361 1362 /// Check Err. If it's in a failure state log the error(s) and exit. 1363 void operator()(Error Err) const { checkError(std::move(Err)); } 1364 1365 /// Check E. If it's in a success state then return the contained value. If 1366 /// it's in a failure state log the error(s) and exit. 1367 template <typename T> T operator()(Expected<T> &&E) const { 1368 checkError(E.takeError()); 1369 return std::move(*E); 1370 } 1371 1372 /// Check E. If it's in a success state then return the contained reference. If 1373 /// it's in a failure state log the error(s) and exit. 1374 template <typename T> T& operator()(Expected<T&> &&E) const { 1375 checkError(E.takeError()); 1376 return *E; 1377 } 1378 1379 private: 1380 void checkError(Error Err) const { 1381 if (Err) { 1382 int ExitCode = GetExitCode(Err); 1383 logAllUnhandledErrors(std::move(Err), errs(), Banner); 1384 exit(ExitCode); 1385 } 1386 } 1387 1388 std::string Banner; 1389 std::function<int(const Error &)> GetExitCode; 1390 }; 1391 1392 /// Conversion from Error to LLVMErrorRef for C error bindings. 1393 inline LLVMErrorRef wrap(Error Err) { 1394 return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release()); 1395 } 1396 1397 /// Conversion from LLVMErrorRef to Error for C error bindings. 1398 inline Error unwrap(LLVMErrorRef ErrRef) { 1399 return Error(std::unique_ptr<ErrorInfoBase>( 1400 reinterpret_cast<ErrorInfoBase *>(ErrRef))); 1401 } 1402 1403 } // end namespace llvm 1404 1405 #endif // LLVM_SUPPORT_ERROR_H 1406