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