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(std::move(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 - The error passed to handleErrors will be marked as checked. If 143 /// // there is no matched handler, a new error with the same payload is 144 /// // created and returned. 145 /// // The handlers take the error checked by handleErrors as an argument, 146 /// // which can be used to retrieve more information. If a new error is 147 /// // created by a handler, it will be passed back to the caller of 148 /// // handleErrors and needs to be checked or return up to the stack. 149 /// // Otherwise, the passed-in error is considered consumed. 150 /// @endcode 151 /// 152 /// The handleAllErrors function is identical to handleErrors, except 153 /// that it has a void return type, and requires all errors to be handled and 154 /// no new errors be returned. It prevents errors (assuming they can all be 155 /// handled) from having to be bubbled all the way to the top-level. 156 /// 157 /// *All* Error instances must be checked before destruction, even if 158 /// they're moved-assigned or constructed from Success values that have already 159 /// been checked. This enforces checking through all levels of the call stack. 160 class [[nodiscard]] Error { 161 // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors 162 // to add to the error list. It can't rely on handleErrors for this, since 163 // handleErrors does not support ErrorList handlers. 164 friend class ErrorList; 165 166 // handleErrors needs to be able to set the Checked flag. 167 template <typename... HandlerTs> 168 friend Error handleErrors(Error E, HandlerTs &&... Handlers); 169 170 // Expected<T> needs to be able to steal the payload when constructed from an 171 // error. 172 template <typename T> friend class Expected; 173 174 // wrap needs to be able to steal the payload. 175 friend LLVMErrorRef wrap(Error); 176 177 protected: 178 /// Create a success value. Prefer using 'Error::success()' for readability 179 Error() { 180 setPtr(nullptr); 181 setChecked(false); 182 } 183 184 public: 185 /// Create a success value. 186 static ErrorSuccess success(); 187 188 // Errors are not copy-constructable. 189 Error(const Error &Other) = delete; 190 191 /// Move-construct an error value. The newly constructed error is considered 192 /// unchecked, even if the source error had been checked. The original error 193 /// becomes a checked Success value, regardless of its original state. 194 Error(Error &&Other) { 195 setChecked(true); 196 *this = std::move(Other); 197 } 198 199 /// Create an error value. Prefer using the 'make_error' function, but 200 /// this constructor can be useful when "re-throwing" errors from handlers. 201 Error(std::unique_ptr<ErrorInfoBase> Payload) { 202 setPtr(Payload.release()); 203 setChecked(false); 204 } 205 206 // Errors are not copy-assignable. 207 Error &operator=(const Error &Other) = delete; 208 209 /// Move-assign an error value. The current error must represent success, you 210 /// you cannot overwrite an unhandled error. The current error is then 211 /// considered unchecked. The source error becomes a checked success value, 212 /// regardless of its original state. 213 Error &operator=(Error &&Other) { 214 // Don't allow overwriting of unchecked values. 215 assertIsChecked(); 216 setPtr(Other.getPtr()); 217 218 // This Error is unchecked, even if the source error was checked. 219 setChecked(false); 220 221 // Null out Other's payload and set its checked bit. 222 Other.setPtr(nullptr); 223 Other.setChecked(true); 224 225 return *this; 226 } 227 228 /// Destroy a Error. Fails with a call to abort() if the error is 229 /// unchecked. 230 ~Error() { 231 assertIsChecked(); 232 delete getPtr(); 233 } 234 235 /// Bool conversion. Returns true if this Error is in a failure state, 236 /// and false if it is in an accept state. If the error is in a Success state 237 /// it will be considered checked. 238 explicit operator bool() { 239 setChecked(getPtr() == nullptr); 240 return getPtr() != nullptr; 241 } 242 243 /// Check whether one error is a subclass of another. 244 template <typename ErrT> bool isA() const { 245 return getPtr() && getPtr()->isA(ErrT::classID()); 246 } 247 248 /// Returns the dynamic class id of this error, or null if this is a success 249 /// value. 250 const void* dynamicClassID() const { 251 if (!getPtr()) 252 return nullptr; 253 return getPtr()->dynamicClassID(); 254 } 255 256 private: 257 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 258 // assertIsChecked() happens very frequently, but under normal circumstances 259 // is supposed to be a no-op. So we want it to be inlined, but having a bunch 260 // of debug prints can cause the function to be too large for inlining. So 261 // it's important that we define this function out of line so that it can't be 262 // inlined. 263 [[noreturn]] void fatalUncheckedError() const; 264 #endif 265 266 void assertIsChecked() { 267 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 268 if (LLVM_UNLIKELY(!getChecked() || getPtr())) 269 fatalUncheckedError(); 270 #endif 271 } 272 273 ErrorInfoBase *getPtr() const { 274 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 275 return reinterpret_cast<ErrorInfoBase*>( 276 reinterpret_cast<uintptr_t>(Payload) & 277 ~static_cast<uintptr_t>(0x1)); 278 #else 279 return Payload; 280 #endif 281 } 282 283 void setPtr(ErrorInfoBase *EI) { 284 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 285 Payload = reinterpret_cast<ErrorInfoBase*>( 286 (reinterpret_cast<uintptr_t>(EI) & 287 ~static_cast<uintptr_t>(0x1)) | 288 (reinterpret_cast<uintptr_t>(Payload) & 0x1)); 289 #else 290 Payload = EI; 291 #endif 292 } 293 294 bool getChecked() const { 295 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 296 return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0; 297 #else 298 return true; 299 #endif 300 } 301 302 void setChecked(bool V) { 303 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 304 Payload = reinterpret_cast<ErrorInfoBase*>( 305 (reinterpret_cast<uintptr_t>(Payload) & 306 ~static_cast<uintptr_t>(0x1)) | 307 (V ? 0 : 1)); 308 #endif 309 } 310 311 std::unique_ptr<ErrorInfoBase> takePayload() { 312 std::unique_ptr<ErrorInfoBase> Tmp(getPtr()); 313 setPtr(nullptr); 314 setChecked(true); 315 return Tmp; 316 } 317 318 friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) { 319 if (auto *P = E.getPtr()) 320 P->log(OS); 321 else 322 OS << "success"; 323 return OS; 324 } 325 326 ErrorInfoBase *Payload = nullptr; 327 }; 328 329 /// Subclass of Error for the sole purpose of identifying the success path in 330 /// the type system. This allows to catch invalid conversion to Expected<T> at 331 /// compile time. 332 class ErrorSuccess final : public Error {}; 333 334 inline ErrorSuccess Error::success() { return ErrorSuccess(); } 335 336 /// Make a Error instance representing failure using the given error info 337 /// type. 338 template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) { 339 return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...)); 340 } 341 342 /// Base class for user error types. Users should declare their error types 343 /// like: 344 /// 345 /// class MyError : public ErrorInfo<MyError> { 346 /// .... 347 /// }; 348 /// 349 /// This class provides an implementation of the ErrorInfoBase::kind 350 /// method, which is used by the Error RTTI system. 351 template <typename ThisErrT, typename ParentErrT = ErrorInfoBase> 352 class ErrorInfo : public ParentErrT { 353 public: 354 using ParentErrT::ParentErrT; // inherit constructors 355 356 static const void *classID() { return &ThisErrT::ID; } 357 358 const void *dynamicClassID() const override { return &ThisErrT::ID; } 359 360 bool isA(const void *const ClassID) const override { 361 return ClassID == classID() || ParentErrT::isA(ClassID); 362 } 363 }; 364 365 /// Special ErrorInfo subclass representing a list of ErrorInfos. 366 /// Instances of this class are constructed by joinError. 367 class ErrorList final : public ErrorInfo<ErrorList> { 368 // handleErrors needs to be able to iterate the payload list of an 369 // ErrorList. 370 template <typename... HandlerTs> 371 friend Error handleErrors(Error E, HandlerTs &&... Handlers); 372 373 // joinErrors is implemented in terms of join. 374 friend Error joinErrors(Error, Error); 375 376 public: 377 void log(raw_ostream &OS) const override { 378 OS << "Multiple errors:\n"; 379 for (const auto &ErrPayload : Payloads) { 380 ErrPayload->log(OS); 381 OS << "\n"; 382 } 383 } 384 385 std::error_code convertToErrorCode() const override; 386 387 // Used by ErrorInfo::classID. 388 static char ID; 389 390 private: 391 ErrorList(std::unique_ptr<ErrorInfoBase> Payload1, 392 std::unique_ptr<ErrorInfoBase> Payload2) { 393 assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() && 394 "ErrorList constructor payloads should be singleton errors"); 395 Payloads.push_back(std::move(Payload1)); 396 Payloads.push_back(std::move(Payload2)); 397 } 398 399 static Error join(Error E1, Error E2) { 400 if (!E1) 401 return E2; 402 if (!E2) 403 return E1; 404 if (E1.isA<ErrorList>()) { 405 auto &E1List = static_cast<ErrorList &>(*E1.getPtr()); 406 if (E2.isA<ErrorList>()) { 407 auto E2Payload = E2.takePayload(); 408 auto &E2List = static_cast<ErrorList &>(*E2Payload); 409 for (auto &Payload : E2List.Payloads) 410 E1List.Payloads.push_back(std::move(Payload)); 411 } else 412 E1List.Payloads.push_back(E2.takePayload()); 413 414 return E1; 415 } 416 if (E2.isA<ErrorList>()) { 417 auto &E2List = static_cast<ErrorList &>(*E2.getPtr()); 418 E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload()); 419 return E2; 420 } 421 return Error(std::unique_ptr<ErrorList>( 422 new ErrorList(E1.takePayload(), E2.takePayload()))); 423 } 424 425 std::vector<std::unique_ptr<ErrorInfoBase>> Payloads; 426 }; 427 428 /// Concatenate errors. The resulting Error is unchecked, and contains the 429 /// ErrorInfo(s), if any, contained in E1, followed by the 430 /// ErrorInfo(s), if any, contained in E2. 431 inline Error joinErrors(Error E1, Error E2) { 432 return ErrorList::join(std::move(E1), std::move(E2)); 433 } 434 435 /// Tagged union holding either a T or a Error. 436 /// 437 /// This class parallels ErrorOr, but replaces error_code with Error. Since 438 /// Error cannot be copied, this class replaces getError() with 439 /// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the 440 /// error class type. 441 /// 442 /// Example usage of 'Expected<T>' as a function return type: 443 /// 444 /// @code{.cpp} 445 /// Expected<int> myDivide(int A, int B) { 446 /// if (B == 0) { 447 /// // return an Error 448 /// return createStringError(inconvertibleErrorCode(), 449 /// "B must not be zero!"); 450 /// } 451 /// // return an integer 452 /// return A / B; 453 /// } 454 /// @endcode 455 /// 456 /// Checking the results of to a function returning 'Expected<T>': 457 /// @code{.cpp} 458 /// if (auto E = Result.takeError()) { 459 /// // We must consume the error. Typically one of: 460 /// // - return the error to our caller 461 /// // - toString(), when logging 462 /// // - consumeError(), to silently swallow the error 463 /// // - handleErrors(), to distinguish error types 464 /// errs() << "Problem with division " << toString(std::move(E)) << "\n"; 465 /// return; 466 /// } 467 /// // use the result 468 /// outs() << "The answer is " << *Result << "\n"; 469 /// @endcode 470 /// 471 /// For unit-testing a function returning an 'Expected<T>', see the 472 /// 'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h 473 474 template <class T> class [[nodiscard]] Expected { 475 template <class T1> friend class ExpectedAsOutParameter; 476 template <class OtherT> friend class Expected; 477 478 static constexpr bool isRef = std::is_reference_v<T>; 479 480 using wrap = std::reference_wrapper<std::remove_reference_t<T>>; 481 482 using error_type = std::unique_ptr<ErrorInfoBase>; 483 484 public: 485 using storage_type = std::conditional_t<isRef, wrap, T>; 486 using value_type = T; 487 488 private: 489 using reference = std::remove_reference_t<T> &; 490 using const_reference = const std::remove_reference_t<T> &; 491 using pointer = std::remove_reference_t<T> *; 492 using const_pointer = const std::remove_reference_t<T> *; 493 494 public: 495 /// Create an Expected<T> error value from the given Error. 496 Expected(Error Err) 497 : HasError(true) 498 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 499 // Expected is unchecked upon construction in Debug builds. 500 , Unchecked(true) 501 #endif 502 { 503 assert(Err && "Cannot create Expected<T> from Error success value."); 504 new (getErrorStorage()) error_type(Err.takePayload()); 505 } 506 507 /// Forbid to convert from Error::success() implicitly, this avoids having 508 /// Expected<T> foo() { return Error::success(); } which compiles otherwise 509 /// but triggers the assertion above. 510 Expected(ErrorSuccess) = delete; 511 512 /// Create an Expected<T> success value from the given OtherT value, which 513 /// must be convertible to T. 514 template <typename OtherT> 515 Expected(OtherT &&Val, 516 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) 517 : HasError(false) 518 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 519 // Expected is unchecked upon construction in Debug builds. 520 , 521 Unchecked(true) 522 #endif 523 { 524 new (getStorage()) storage_type(std::forward<OtherT>(Val)); 525 } 526 527 /// Move construct an Expected<T> value. 528 Expected(Expected &&Other) { moveConstruct(std::move(Other)); } 529 530 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 531 /// must be convertible to T. 532 template <class OtherT> 533 Expected(Expected<OtherT> &&Other, 534 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) { 535 moveConstruct(std::move(Other)); 536 } 537 538 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 539 /// isn't convertible to T. 540 template <class OtherT> 541 explicit Expected( 542 Expected<OtherT> &&Other, 543 std::enable_if_t<!std::is_convertible_v<OtherT, T>> * = nullptr) { 544 moveConstruct(std::move(Other)); 545 } 546 547 /// Move-assign from another Expected<T>. 548 Expected &operator=(Expected &&Other) { 549 moveAssign(std::move(Other)); 550 return *this; 551 } 552 553 /// Destroy an Expected<T>. 554 ~Expected() { 555 assertIsChecked(); 556 if (!HasError) 557 getStorage()->~storage_type(); 558 else 559 getErrorStorage()->~error_type(); 560 } 561 562 /// Return false if there is an error. 563 explicit operator bool() { 564 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 565 Unchecked = HasError; 566 #endif 567 return !HasError; 568 } 569 570 /// Returns a reference to the stored T value. 571 reference get() { 572 assertIsChecked(); 573 return *getStorage(); 574 } 575 576 /// Returns a const reference to the stored T value. 577 const_reference get() const { 578 assertIsChecked(); 579 return const_cast<Expected<T> *>(this)->get(); 580 } 581 582 /// Returns \a takeError() after moving the held T (if any) into \p V. 583 template <class OtherT> 584 Error moveInto( 585 OtherT &Value, 586 std::enable_if_t<std::is_assignable_v<OtherT &, T &&>> * = nullptr) && { 587 if (*this) 588 Value = std::move(get()); 589 return takeError(); 590 } 591 592 /// Check that this Expected<T> is an error of type ErrT. 593 template <typename ErrT> bool errorIsA() const { 594 return HasError && (*getErrorStorage())->template isA<ErrT>(); 595 } 596 597 /// Take ownership of the stored error. 598 /// After calling this the Expected<T> is in an indeterminate state that can 599 /// only be safely destructed. No further calls (beside the destructor) should 600 /// be made on the Expected<T> value. 601 Error takeError() { 602 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 603 Unchecked = false; 604 #endif 605 return HasError ? Error(std::move(*getErrorStorage())) : Error::success(); 606 } 607 608 /// Returns a pointer to the stored T value. 609 pointer operator->() { 610 assertIsChecked(); 611 return toPointer(getStorage()); 612 } 613 614 /// Returns a const pointer to the stored T value. 615 const_pointer operator->() const { 616 assertIsChecked(); 617 return toPointer(getStorage()); 618 } 619 620 /// Returns a reference to the stored T value. 621 reference operator*() { 622 assertIsChecked(); 623 return *getStorage(); 624 } 625 626 /// Returns a const reference to the stored T value. 627 const_reference operator*() const { 628 assertIsChecked(); 629 return *getStorage(); 630 } 631 632 private: 633 template <class T1> 634 static bool compareThisIfSameType(const T1 &a, const T1 &b) { 635 return &a == &b; 636 } 637 638 template <class T1, class T2> 639 static bool compareThisIfSameType(const T1 &, const T2 &) { 640 return false; 641 } 642 643 template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) { 644 HasError = Other.HasError; 645 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 646 Unchecked = true; 647 Other.Unchecked = false; 648 #endif 649 650 if (!HasError) 651 new (getStorage()) storage_type(std::move(*Other.getStorage())); 652 else 653 new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage())); 654 } 655 656 template <class OtherT> void moveAssign(Expected<OtherT> &&Other) { 657 assertIsChecked(); 658 659 if (compareThisIfSameType(*this, Other)) 660 return; 661 662 this->~Expected(); 663 new (this) Expected(std::move(Other)); 664 } 665 666 pointer toPointer(pointer Val) { return Val; } 667 668 const_pointer toPointer(const_pointer Val) const { return Val; } 669 670 pointer toPointer(wrap *Val) { return &Val->get(); } 671 672 const_pointer toPointer(const wrap *Val) const { return &Val->get(); } 673 674 storage_type *getStorage() { 675 assert(!HasError && "Cannot get value when an error exists!"); 676 return reinterpret_cast<storage_type *>(&TStorage); 677 } 678 679 const storage_type *getStorage() const { 680 assert(!HasError && "Cannot get value when an error exists!"); 681 return reinterpret_cast<const storage_type *>(&TStorage); 682 } 683 684 error_type *getErrorStorage() { 685 assert(HasError && "Cannot get error when a value exists!"); 686 return reinterpret_cast<error_type *>(&ErrorStorage); 687 } 688 689 const error_type *getErrorStorage() const { 690 assert(HasError && "Cannot get error when a value exists!"); 691 return reinterpret_cast<const error_type *>(&ErrorStorage); 692 } 693 694 // Used by ExpectedAsOutParameter to reset the checked flag. 695 void setUnchecked() { 696 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 697 Unchecked = true; 698 #endif 699 } 700 701 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 702 [[noreturn]] LLVM_ATTRIBUTE_NOINLINE void fatalUncheckedExpected() const { 703 dbgs() << "Expected<T> must be checked before access or destruction.\n"; 704 if (HasError) { 705 dbgs() << "Unchecked Expected<T> contained error:\n"; 706 (*getErrorStorage())->log(dbgs()); 707 } else 708 dbgs() << "Expected<T> value was in success state. (Note: Expected<T> " 709 "values in success mode must still be checked prior to being " 710 "destroyed).\n"; 711 abort(); 712 } 713 #endif 714 715 void assertIsChecked() const { 716 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 717 if (LLVM_UNLIKELY(Unchecked)) 718 fatalUncheckedExpected(); 719 #endif 720 } 721 722 union { 723 AlignedCharArrayUnion<storage_type> TStorage; 724 AlignedCharArrayUnion<error_type> ErrorStorage; 725 }; 726 bool HasError : 1; 727 #if LLVM_ENABLE_ABI_BREAKING_CHECKS 728 bool Unchecked : 1; 729 #endif 730 }; 731 732 /// Report a serious error, calling any installed error handler. See 733 /// ErrorHandling.h. 734 [[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true); 735 736 /// Report a fatal error if Err is a failure value. 737 /// 738 /// This function can be used to wrap calls to fallible functions ONLY when it 739 /// is known that the Error will always be a success value. E.g. 740 /// 741 /// @code{.cpp} 742 /// // foo only attempts the fallible operation if DoFallibleOperation is 743 /// // true. If DoFallibleOperation is false then foo always returns 744 /// // Error::success(). 745 /// Error foo(bool DoFallibleOperation); 746 /// 747 /// cantFail(foo(false)); 748 /// @endcode 749 inline void cantFail(Error Err, const char *Msg = nullptr) { 750 if (Err) { 751 if (!Msg) 752 Msg = "Failure value returned from cantFail wrapped call"; 753 #ifndef NDEBUG 754 std::string Str; 755 raw_string_ostream OS(Str); 756 OS << Msg << "\n" << Err; 757 Msg = OS.str().c_str(); 758 #endif 759 llvm_unreachable(Msg); 760 } 761 } 762 763 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 764 /// returns the contained value. 765 /// 766 /// This function can be used to wrap calls to fallible functions ONLY when it 767 /// is known that the Error will always be a success value. E.g. 768 /// 769 /// @code{.cpp} 770 /// // foo only attempts the fallible operation if DoFallibleOperation is 771 /// // true. If DoFallibleOperation is false then foo always returns an int. 772 /// Expected<int> foo(bool DoFallibleOperation); 773 /// 774 /// int X = cantFail(foo(false)); 775 /// @endcode 776 template <typename T> 777 T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) { 778 if (ValOrErr) 779 return std::move(*ValOrErr); 780 else { 781 if (!Msg) 782 Msg = "Failure value returned from cantFail wrapped call"; 783 #ifndef NDEBUG 784 std::string Str; 785 raw_string_ostream OS(Str); 786 auto E = ValOrErr.takeError(); 787 OS << Msg << "\n" << E; 788 Msg = OS.str().c_str(); 789 #endif 790 llvm_unreachable(Msg); 791 } 792 } 793 794 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 795 /// returns the contained reference. 796 /// 797 /// This function can be used to wrap calls to fallible functions ONLY when it 798 /// is known that the Error will always be a success value. E.g. 799 /// 800 /// @code{.cpp} 801 /// // foo only attempts the fallible operation if DoFallibleOperation is 802 /// // true. If DoFallibleOperation is false then foo always returns a Bar&. 803 /// Expected<Bar&> foo(bool DoFallibleOperation); 804 /// 805 /// Bar &X = cantFail(foo(false)); 806 /// @endcode 807 template <typename T> 808 T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) { 809 if (ValOrErr) 810 return *ValOrErr; 811 else { 812 if (!Msg) 813 Msg = "Failure value returned from cantFail wrapped call"; 814 #ifndef NDEBUG 815 std::string Str; 816 raw_string_ostream OS(Str); 817 auto E = ValOrErr.takeError(); 818 OS << Msg << "\n" << E; 819 Msg = OS.str().c_str(); 820 #endif 821 llvm_unreachable(Msg); 822 } 823 } 824 825 /// Helper for testing applicability of, and applying, handlers for 826 /// ErrorInfo types. 827 template <typename HandlerT> 828 class ErrorHandlerTraits 829 : public ErrorHandlerTraits< 830 decltype(&std::remove_reference_t<HandlerT>::operator())> {}; 831 832 // Specialization functions of the form 'Error (const ErrT&)'. 833 template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> { 834 public: 835 static bool appliesTo(const ErrorInfoBase &E) { 836 return E.template isA<ErrT>(); 837 } 838 839 template <typename HandlerT> 840 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 841 assert(appliesTo(*E) && "Applying incorrect handler"); 842 return H(static_cast<ErrT &>(*E)); 843 } 844 }; 845 846 // Specialization functions of the form 'void (const ErrT&)'. 847 template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> { 848 public: 849 static bool appliesTo(const ErrorInfoBase &E) { 850 return E.template isA<ErrT>(); 851 } 852 853 template <typename HandlerT> 854 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 855 assert(appliesTo(*E) && "Applying incorrect handler"); 856 H(static_cast<ErrT &>(*E)); 857 return Error::success(); 858 } 859 }; 860 861 /// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'. 862 template <typename ErrT> 863 class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> { 864 public: 865 static bool appliesTo(const ErrorInfoBase &E) { 866 return E.template isA<ErrT>(); 867 } 868 869 template <typename HandlerT> 870 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 871 assert(appliesTo(*E) && "Applying incorrect handler"); 872 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 873 return H(std::move(SubE)); 874 } 875 }; 876 877 /// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'. 878 template <typename ErrT> 879 class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> { 880 public: 881 static bool appliesTo(const ErrorInfoBase &E) { 882 return E.template isA<ErrT>(); 883 } 884 885 template <typename HandlerT> 886 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 887 assert(appliesTo(*E) && "Applying incorrect handler"); 888 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 889 H(std::move(SubE)); 890 return Error::success(); 891 } 892 }; 893 894 // Specialization for member functions of the form 'RetT (const ErrT&)'. 895 template <typename C, typename RetT, typename ErrT> 896 class ErrorHandlerTraits<RetT (C::*)(ErrT &)> 897 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 898 899 // Specialization for member functions of the form 'RetT (const ErrT&) const'. 900 template <typename C, typename RetT, typename ErrT> 901 class ErrorHandlerTraits<RetT (C::*)(ErrT &) const> 902 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 903 904 // Specialization for member functions of the form 'RetT (const ErrT&)'. 905 template <typename C, typename RetT, typename ErrT> 906 class ErrorHandlerTraits<RetT (C::*)(const ErrT &)> 907 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 908 909 // Specialization for member functions of the form 'RetT (const ErrT&) const'. 910 template <typename C, typename RetT, typename ErrT> 911 class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const> 912 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 913 914 /// Specialization for member functions of the form 915 /// 'RetT (std::unique_ptr<ErrT>)'. 916 template <typename C, typename RetT, typename ErrT> 917 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)> 918 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 919 920 /// Specialization for member functions of the form 921 /// 'RetT (std::unique_ptr<ErrT>) const'. 922 template <typename C, typename RetT, typename ErrT> 923 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const> 924 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 925 926 inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) { 927 return Error(std::move(Payload)); 928 } 929 930 template <typename HandlerT, typename... HandlerTs> 931 Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload, 932 HandlerT &&Handler, HandlerTs &&... Handlers) { 933 if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload)) 934 return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler), 935 std::move(Payload)); 936 return handleErrorImpl(std::move(Payload), 937 std::forward<HandlerTs>(Handlers)...); 938 } 939 940 /// Pass the ErrorInfo(s) contained in E to their respective handlers. Any 941 /// unhandled errors (or Errors returned by handlers) are re-concatenated and 942 /// returned. 943 /// Because this function returns an error, its result must also be checked 944 /// or returned. If you intend to handle all errors use handleAllErrors 945 /// (which returns void, and will abort() on unhandled errors) instead. 946 template <typename... HandlerTs> 947 Error handleErrors(Error E, HandlerTs &&... Hs) { 948 if (!E) 949 return Error::success(); 950 951 std::unique_ptr<ErrorInfoBase> Payload = E.takePayload(); 952 953 if (Payload->isA<ErrorList>()) { 954 ErrorList &List = static_cast<ErrorList &>(*Payload); 955 Error R; 956 for (auto &P : List.Payloads) 957 R = ErrorList::join( 958 std::move(R), 959 handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...)); 960 return R; 961 } 962 963 return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...); 964 } 965 966 /// Behaves the same as handleErrors, except that by contract all errors 967 /// *must* be handled by the given handlers (i.e. there must be no remaining 968 /// errors after running the handlers, or llvm_unreachable is called). 969 template <typename... HandlerTs> 970 void handleAllErrors(Error E, HandlerTs &&... Handlers) { 971 cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...)); 972 } 973 974 /// Check that E is a non-error, then drop it. 975 /// If E is an error, llvm_unreachable will be called. 976 inline void handleAllErrors(Error E) { 977 cantFail(std::move(E)); 978 } 979 980 /// Handle any errors (if present) in an Expected<T>, then try a recovery path. 981 /// 982 /// If the incoming value is a success value it is returned unmodified. If it 983 /// is a failure value then it the contained error is passed to handleErrors. 984 /// If handleErrors is able to handle the error then the RecoveryPath functor 985 /// is called to supply the final result. If handleErrors is not able to 986 /// handle all errors then the unhandled errors are returned. 987 /// 988 /// This utility enables the follow pattern: 989 /// 990 /// @code{.cpp} 991 /// enum FooStrategy { Aggressive, Conservative }; 992 /// Expected<Foo> foo(FooStrategy S); 993 /// 994 /// auto ResultOrErr = 995 /// handleExpected( 996 /// foo(Aggressive), 997 /// []() { return foo(Conservative); }, 998 /// [](AggressiveStrategyError&) { 999 /// // Implicitly conusme this - we'll recover by using a conservative 1000 /// // strategy. 1001 /// }); 1002 /// 1003 /// @endcode 1004 template <typename T, typename RecoveryFtor, typename... HandlerTs> 1005 Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath, 1006 HandlerTs &&... Handlers) { 1007 if (ValOrErr) 1008 return ValOrErr; 1009 1010 if (auto Err = handleErrors(ValOrErr.takeError(), 1011 std::forward<HandlerTs>(Handlers)...)) 1012 return std::move(Err); 1013 1014 return RecoveryPath(); 1015 } 1016 1017 /// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner 1018 /// will be printed before the first one is logged. A newline will be printed 1019 /// after each error. 1020 /// 1021 /// This function is compatible with the helpers from Support/WithColor.h. You 1022 /// can pass any of them as the OS. Please consider using them instead of 1023 /// including 'error: ' in the ErrorBanner. 1024 /// 1025 /// This is useful in the base level of your program to allow clean termination 1026 /// (allowing clean deallocation of resources, etc.), while reporting error 1027 /// information to the user. 1028 void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {}); 1029 1030 /// Write all error messages (if any) in E to a string. The newline character 1031 /// is used to separate error messages. 1032 std::string toString(Error E); 1033 1034 /// Consume a Error without doing anything. This method should be used 1035 /// only where an error can be considered a reasonable and expected return 1036 /// value. 1037 /// 1038 /// Uses of this method are potentially indicative of design problems: If it's 1039 /// legitimate to do nothing while processing an "error", the error-producer 1040 /// might be more clearly refactored to return an std::optional<T>. 1041 inline void consumeError(Error Err) { 1042 handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {}); 1043 } 1044 1045 /// Convert an Expected to an Optional without doing anything. This method 1046 /// should be used only where an error can be considered a reasonable and 1047 /// expected return value. 1048 /// 1049 /// Uses of this method are potentially indicative of problems: perhaps the 1050 /// error should be propagated further, or the error-producer should just 1051 /// return an Optional in the first place. 1052 template <typename T> std::optional<T> expectedToOptional(Expected<T> &&E) { 1053 if (E) 1054 return std::move(*E); 1055 consumeError(E.takeError()); 1056 return std::nullopt; 1057 } 1058 1059 template <typename T> std::optional<T> expectedToStdOptional(Expected<T> &&E) { 1060 if (E) 1061 return std::move(*E); 1062 consumeError(E.takeError()); 1063 return std::nullopt; 1064 } 1065 1066 /// Helper for converting an Error to a bool. 1067 /// 1068 /// This method returns true if Err is in an error state, or false if it is 1069 /// in a success state. Puts Err in a checked state in both cases (unlike 1070 /// Error::operator bool(), which only does this for success states). 1071 inline bool errorToBool(Error Err) { 1072 bool IsError = static_cast<bool>(Err); 1073 if (IsError) 1074 consumeError(std::move(Err)); 1075 return IsError; 1076 } 1077 1078 /// Helper for Errors used as out-parameters. 1079 /// 1080 /// This helper is for use with the Error-as-out-parameter idiom, where an error 1081 /// is passed to a function or method by reference, rather than being returned. 1082 /// In such cases it is helpful to set the checked bit on entry to the function 1083 /// so that the error can be written to (unchecked Errors abort on assignment) 1084 /// and clear the checked bit on exit so that clients cannot accidentally forget 1085 /// to check the result. This helper performs these actions automatically using 1086 /// RAII: 1087 /// 1088 /// @code{.cpp} 1089 /// Result foo(Error &Err) { 1090 /// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set 1091 /// // <body of foo> 1092 /// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed. 1093 /// } 1094 /// @endcode 1095 /// 1096 /// ErrorAsOutParameter takes an Error* rather than Error& so that it can be 1097 /// used with optional Errors (Error pointers that are allowed to be null). If 1098 /// ErrorAsOutParameter took an Error reference, an instance would have to be 1099 /// created inside every condition that verified that Error was non-null. By 1100 /// taking an Error pointer we can just create one instance at the top of the 1101 /// function. 1102 class ErrorAsOutParameter { 1103 public: 1104 ErrorAsOutParameter(Error *Err) : Err(Err) { 1105 // Raise the checked bit if Err is success. 1106 if (Err) 1107 (void)!!*Err; 1108 } 1109 1110 ~ErrorAsOutParameter() { 1111 // Clear the checked bit. 1112 if (Err && !*Err) 1113 *Err = Error::success(); 1114 } 1115 1116 private: 1117 Error *Err; 1118 }; 1119 1120 /// Helper for Expected<T>s used as out-parameters. 1121 /// 1122 /// See ErrorAsOutParameter. 1123 template <typename T> 1124 class ExpectedAsOutParameter { 1125 public: 1126 ExpectedAsOutParameter(Expected<T> *ValOrErr) 1127 : ValOrErr(ValOrErr) { 1128 if (ValOrErr) 1129 (void)!!*ValOrErr; 1130 } 1131 1132 ~ExpectedAsOutParameter() { 1133 if (ValOrErr) 1134 ValOrErr->setUnchecked(); 1135 } 1136 1137 private: 1138 Expected<T> *ValOrErr; 1139 }; 1140 1141 /// This class wraps a std::error_code in a Error. 1142 /// 1143 /// This is useful if you're writing an interface that returns a Error 1144 /// (or Expected) and you want to call code that still returns 1145 /// std::error_codes. 1146 class ECError : public ErrorInfo<ECError> { 1147 friend Error errorCodeToError(std::error_code); 1148 1149 void anchor() override; 1150 1151 public: 1152 void setErrorCode(std::error_code EC) { this->EC = EC; } 1153 std::error_code convertToErrorCode() const override { return EC; } 1154 void log(raw_ostream &OS) const override { OS << EC.message(); } 1155 1156 // Used by ErrorInfo::classID. 1157 static char ID; 1158 1159 protected: 1160 ECError() = default; 1161 ECError(std::error_code EC) : EC(EC) {} 1162 1163 std::error_code EC; 1164 }; 1165 1166 /// The value returned by this function can be returned from convertToErrorCode 1167 /// for Error values where no sensible translation to std::error_code exists. 1168 /// It should only be used in this situation, and should never be used where a 1169 /// sensible conversion to std::error_code is available, as attempts to convert 1170 /// to/from this error will result in a fatal error. (i.e. it is a programmatic 1171 /// error to try to convert such a value). 1172 std::error_code inconvertibleErrorCode(); 1173 1174 /// Helper for converting an std::error_code to a Error. 1175 Error errorCodeToError(std::error_code EC); 1176 1177 /// Helper for converting an ECError to a std::error_code. 1178 /// 1179 /// This method requires that Err be Error() or an ECError, otherwise it 1180 /// will trigger a call to abort(). 1181 std::error_code errorToErrorCode(Error Err); 1182 1183 /// Convert an ErrorOr<T> to an Expected<T>. 1184 template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) { 1185 if (auto EC = EO.getError()) 1186 return errorCodeToError(EC); 1187 return std::move(*EO); 1188 } 1189 1190 /// Convert an Expected<T> to an ErrorOr<T>. 1191 template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) { 1192 if (auto Err = E.takeError()) 1193 return errorToErrorCode(std::move(Err)); 1194 return std::move(*E); 1195 } 1196 1197 /// This class wraps a string in an Error. 1198 /// 1199 /// StringError is useful in cases where the client is not expected to be able 1200 /// to consume the specific error message programmatically (for example, if the 1201 /// error message is to be presented to the user). 1202 /// 1203 /// StringError can also be used when additional information is to be printed 1204 /// along with a error_code message. Depending on the constructor called, this 1205 /// class can either display: 1206 /// 1. the error_code message (ECError behavior) 1207 /// 2. a string 1208 /// 3. the error_code message and a string 1209 /// 1210 /// These behaviors are useful when subtyping is required; for example, when a 1211 /// specific library needs an explicit error type. In the example below, 1212 /// PDBError is derived from StringError: 1213 /// 1214 /// @code{.cpp} 1215 /// Expected<int> foo() { 1216 /// return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading, 1217 /// "Additional information"); 1218 /// } 1219 /// @endcode 1220 /// 1221 class StringError : public ErrorInfo<StringError> { 1222 public: 1223 static char ID; 1224 1225 // Prints EC + S and converts to EC 1226 StringError(std::error_code EC, const Twine &S = Twine()); 1227 1228 // Prints S and converts to EC 1229 StringError(const Twine &S, std::error_code EC); 1230 1231 void log(raw_ostream &OS) const override; 1232 std::error_code convertToErrorCode() const override; 1233 1234 const std::string &getMessage() const { return Msg; } 1235 1236 private: 1237 std::string Msg; 1238 std::error_code EC; 1239 const bool PrintMsgOnly = false; 1240 }; 1241 1242 /// Create formatted StringError object. 1243 template <typename... Ts> 1244 inline Error createStringError(std::error_code EC, char const *Fmt, 1245 const Ts &... Vals) { 1246 std::string Buffer; 1247 raw_string_ostream Stream(Buffer); 1248 Stream << format(Fmt, Vals...); 1249 return make_error<StringError>(Stream.str(), EC); 1250 } 1251 1252 Error createStringError(std::error_code EC, char const *Msg); 1253 1254 inline Error createStringError(std::error_code EC, const Twine &S) { 1255 return createStringError(EC, S.str().c_str()); 1256 } 1257 1258 template <typename... Ts> 1259 inline Error createStringError(std::errc EC, char const *Fmt, 1260 const Ts &... Vals) { 1261 return createStringError(std::make_error_code(EC), Fmt, Vals...); 1262 } 1263 1264 /// This class wraps a filename and another Error. 1265 /// 1266 /// In some cases, an error needs to live along a 'source' name, in order to 1267 /// show more detailed information to the user. 1268 class FileError final : public ErrorInfo<FileError> { 1269 1270 friend Error createFileError(const Twine &, Error); 1271 friend Error createFileError(const Twine &, size_t, Error); 1272 1273 public: 1274 void log(raw_ostream &OS) const override { 1275 assert(Err && "Trying to log after takeError()."); 1276 OS << "'" << FileName << "': "; 1277 if (Line) 1278 OS << "line " << *Line << ": "; 1279 Err->log(OS); 1280 } 1281 1282 std::string messageWithoutFileInfo() const { 1283 std::string Msg; 1284 raw_string_ostream OS(Msg); 1285 Err->log(OS); 1286 return OS.str(); 1287 } 1288 1289 StringRef getFileName() const { return FileName; } 1290 1291 Error takeError() { return Error(std::move(Err)); } 1292 1293 std::error_code convertToErrorCode() const override; 1294 1295 // Used by ErrorInfo::classID. 1296 static char ID; 1297 1298 private: 1299 FileError(const Twine &F, std::optional<size_t> LineNum, 1300 std::unique_ptr<ErrorInfoBase> E) { 1301 assert(E && "Cannot create FileError from Error success value."); 1302 FileName = F.str(); 1303 Err = std::move(E); 1304 Line = std::move(LineNum); 1305 } 1306 1307 static Error build(const Twine &F, std::optional<size_t> Line, Error E) { 1308 std::unique_ptr<ErrorInfoBase> Payload; 1309 handleAllErrors(std::move(E), 1310 [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error { 1311 Payload = std::move(EIB); 1312 return Error::success(); 1313 }); 1314 return Error( 1315 std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload)))); 1316 } 1317 1318 std::string FileName; 1319 std::optional<size_t> Line; 1320 std::unique_ptr<ErrorInfoBase> Err; 1321 }; 1322 1323 /// Concatenate a source file path and/or name with an Error. The resulting 1324 /// Error is unchecked. 1325 inline Error createFileError(const Twine &F, Error E) { 1326 return FileError::build(F, std::optional<size_t>(), std::move(E)); 1327 } 1328 1329 /// Concatenate a source file path and/or name with line number and an Error. 1330 /// The resulting Error is unchecked. 1331 inline Error createFileError(const Twine &F, size_t Line, Error E) { 1332 return FileError::build(F, std::optional<size_t>(Line), std::move(E)); 1333 } 1334 1335 /// Concatenate a source file path and/or name with a std::error_code 1336 /// to form an Error object. 1337 inline Error createFileError(const Twine &F, std::error_code EC) { 1338 return createFileError(F, errorCodeToError(EC)); 1339 } 1340 1341 /// Concatenate a source file path and/or name with line number and 1342 /// std::error_code to form an Error object. 1343 inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) { 1344 return createFileError(F, Line, errorCodeToError(EC)); 1345 } 1346 1347 Error createFileError(const Twine &F, ErrorSuccess) = delete; 1348 1349 /// Helper for check-and-exit error handling. 1350 /// 1351 /// For tool use only. NOT FOR USE IN LIBRARY CODE. 1352 /// 1353 class ExitOnError { 1354 public: 1355 /// Create an error on exit helper. 1356 ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1) 1357 : Banner(std::move(Banner)), 1358 GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {} 1359 1360 /// Set the banner string for any errors caught by operator(). 1361 void setBanner(std::string Banner) { this->Banner = std::move(Banner); } 1362 1363 /// Set the exit-code mapper function. 1364 void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) { 1365 this->GetExitCode = std::move(GetExitCode); 1366 } 1367 1368 /// Check Err. If it's in a failure state log the error(s) and exit. 1369 void operator()(Error Err) const { checkError(std::move(Err)); } 1370 1371 /// Check E. If it's in a success state then return the contained value. If 1372 /// it's in a failure state log the error(s) and exit. 1373 template <typename T> T operator()(Expected<T> &&E) const { 1374 checkError(E.takeError()); 1375 return std::move(*E); 1376 } 1377 1378 /// Check E. If it's in a success state then return the contained reference. If 1379 /// it's in a failure state log the error(s) and exit. 1380 template <typename T> T& operator()(Expected<T&> &&E) const { 1381 checkError(E.takeError()); 1382 return *E; 1383 } 1384 1385 private: 1386 void checkError(Error Err) const { 1387 if (Err) { 1388 int ExitCode = GetExitCode(Err); 1389 logAllUnhandledErrors(std::move(Err), errs(), Banner); 1390 exit(ExitCode); 1391 } 1392 } 1393 1394 std::string Banner; 1395 std::function<int(const Error &)> GetExitCode; 1396 }; 1397 1398 /// Conversion from Error to LLVMErrorRef for C error bindings. 1399 inline LLVMErrorRef wrap(Error Err) { 1400 return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release()); 1401 } 1402 1403 /// Conversion from LLVMErrorRef to Error for C error bindings. 1404 inline Error unwrap(LLVMErrorRef ErrRef) { 1405 return Error(std::unique_ptr<ErrorInfoBase>( 1406 reinterpret_cast<ErrorInfoBase *>(ErrRef))); 1407 } 1408 1409 } // end namespace llvm 1410 1411 #endif // LLVM_SUPPORT_ERROR_H 1412