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