Error.h revision 327952
1321369Sdim//===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===// 2303231Sdim// 3303231Sdim// The LLVM Compiler Infrastructure 4303231Sdim// 5303231Sdim// This file is distributed under the University of Illinois Open Source 6303231Sdim// License. See LICENSE.TXT for details. 7303231Sdim// 8303231Sdim//===----------------------------------------------------------------------===// 9303231Sdim// 10303231Sdim// This file defines an API used to report recoverable errors. 11303231Sdim// 12303231Sdim//===----------------------------------------------------------------------===// 13303231Sdim 14303231Sdim#ifndef LLVM_SUPPORT_ERROR_H 15303231Sdim#define LLVM_SUPPORT_ERROR_H 16303231Sdim 17314564Sdim#include "llvm/ADT/SmallVector.h" 18303231Sdim#include "llvm/ADT/STLExtras.h" 19303231Sdim#include "llvm/ADT/StringExtras.h" 20303231Sdim#include "llvm/ADT/Twine.h" 21314564Sdim#include "llvm/Config/abi-breaking.h" 22314564Sdim#include "llvm/Support/AlignOf.h" 23314564Sdim#include "llvm/Support/Compiler.h" 24303231Sdim#include "llvm/Support/Debug.h" 25321369Sdim#include "llvm/Support/ErrorHandling.h" 26303231Sdim#include "llvm/Support/ErrorOr.h" 27303231Sdim#include "llvm/Support/raw_ostream.h" 28314564Sdim#include <algorithm> 29314564Sdim#include <cassert> 30314564Sdim#include <cstdint> 31314564Sdim#include <cstdlib> 32314564Sdim#include <functional> 33314564Sdim#include <memory> 34314564Sdim#include <new> 35314564Sdim#include <string> 36314564Sdim#include <system_error> 37314564Sdim#include <type_traits> 38314564Sdim#include <utility> 39303231Sdim#include <vector> 40303231Sdim 41303231Sdimnamespace llvm { 42303231Sdim 43314564Sdimclass ErrorSuccess; 44303231Sdim 45303231Sdim/// Base class for error info classes. Do not extend this directly: Extend 46303231Sdim/// the ErrorInfo template subclass instead. 47303231Sdimclass ErrorInfoBase { 48303231Sdimpublic: 49314564Sdim virtual ~ErrorInfoBase() = default; 50303231Sdim 51303231Sdim /// Print an error message to an output stream. 52303231Sdim virtual void log(raw_ostream &OS) const = 0; 53303231Sdim 54303231Sdim /// Return the error message as a string. 55303231Sdim virtual std::string message() const { 56303231Sdim std::string Msg; 57303231Sdim raw_string_ostream OS(Msg); 58303231Sdim log(OS); 59303231Sdim return OS.str(); 60303231Sdim } 61303231Sdim 62303231Sdim /// Convert this error to a std::error_code. 63303231Sdim /// 64303231Sdim /// This is a temporary crutch to enable interaction with code still 65303231Sdim /// using std::error_code. It will be removed in the future. 66303231Sdim virtual std::error_code convertToErrorCode() const = 0; 67303231Sdim 68321369Sdim // Returns the class ID for this type. 69321369Sdim static const void *classID() { return &ID; } 70321369Sdim 71321369Sdim // Returns the class ID for the dynamic type of this ErrorInfoBase instance. 72321369Sdim virtual const void *dynamicClassID() const = 0; 73321369Sdim 74303231Sdim // Check whether this instance is a subclass of the class identified by 75303231Sdim // ClassID. 76303231Sdim virtual bool isA(const void *const ClassID) const { 77303231Sdim return ClassID == classID(); 78303231Sdim } 79303231Sdim 80303231Sdim // Check whether this instance is a subclass of ErrorInfoT. 81303231Sdim template <typename ErrorInfoT> bool isA() const { 82303231Sdim return isA(ErrorInfoT::classID()); 83303231Sdim } 84303231Sdim 85303231Sdimprivate: 86303231Sdim virtual void anchor(); 87314564Sdim 88303231Sdim static char ID; 89303231Sdim}; 90303231Sdim 91303231Sdim/// Lightweight error class with error context and mandatory checking. 92303231Sdim/// 93303231Sdim/// Instances of this class wrap a ErrorInfoBase pointer. Failure states 94303231Sdim/// are represented by setting the pointer to a ErrorInfoBase subclass 95303231Sdim/// instance containing information describing the failure. Success is 96303231Sdim/// represented by a null pointer value. 97303231Sdim/// 98303231Sdim/// Instances of Error also contains a 'Checked' flag, which must be set 99303231Sdim/// before the destructor is called, otherwise the destructor will trigger a 100303231Sdim/// runtime error. This enforces at runtime the requirement that all Error 101303231Sdim/// instances be checked or returned to the caller. 102303231Sdim/// 103303231Sdim/// There are two ways to set the checked flag, depending on what state the 104303231Sdim/// Error instance is in. For Error instances indicating success, it 105303231Sdim/// is sufficient to invoke the boolean conversion operator. E.g.: 106303231Sdim/// 107314564Sdim/// @code{.cpp} 108303231Sdim/// Error foo(<...>); 109303231Sdim/// 110303231Sdim/// if (auto E = foo(<...>)) 111303231Sdim/// return E; // <- Return E if it is in the error state. 112303231Sdim/// // We have verified that E was in the success state. It can now be safely 113303231Sdim/// // destroyed. 114314564Sdim/// @endcode 115303231Sdim/// 116303231Sdim/// A success value *can not* be dropped. For example, just calling 'foo(<...>)' 117303231Sdim/// without testing the return value will raise a runtime error, even if foo 118303231Sdim/// returns success. 119303231Sdim/// 120303231Sdim/// For Error instances representing failure, you must use either the 121303231Sdim/// handleErrors or handleAllErrors function with a typed handler. E.g.: 122303231Sdim/// 123314564Sdim/// @code{.cpp} 124303231Sdim/// class MyErrorInfo : public ErrorInfo<MyErrorInfo> { 125303231Sdim/// // Custom error info. 126303231Sdim/// }; 127303231Sdim/// 128303231Sdim/// Error foo(<...>) { return make_error<MyErrorInfo>(...); } 129303231Sdim/// 130303231Sdim/// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo. 131303231Sdim/// auto NewE = 132303231Sdim/// handleErrors(E, 133303231Sdim/// [](const MyErrorInfo &M) { 134303231Sdim/// // Deal with the error. 135303231Sdim/// }, 136303231Sdim/// [](std::unique_ptr<OtherError> M) -> Error { 137303231Sdim/// if (canHandle(*M)) { 138303231Sdim/// // handle error. 139303231Sdim/// return Error::success(); 140303231Sdim/// } 141303231Sdim/// // Couldn't handle this error instance. Pass it up the stack. 142303231Sdim/// return Error(std::move(M)); 143303231Sdim/// ); 144303231Sdim/// // Note - we must check or return NewE in case any of the handlers 145303231Sdim/// // returned a new error. 146314564Sdim/// @endcode 147303231Sdim/// 148303231Sdim/// The handleAllErrors function is identical to handleErrors, except 149303231Sdim/// that it has a void return type, and requires all errors to be handled and 150303231Sdim/// no new errors be returned. It prevents errors (assuming they can all be 151303231Sdim/// handled) from having to be bubbled all the way to the top-level. 152303231Sdim/// 153303231Sdim/// *All* Error instances must be checked before destruction, even if 154303231Sdim/// they're moved-assigned or constructed from Success values that have already 155303231Sdim/// been checked. This enforces checking through all levels of the call stack. 156314564Sdimclass LLVM_NODISCARD Error { 157303231Sdim // ErrorList needs to be able to yank ErrorInfoBase pointers out of this 158303231Sdim // class to add to the error list. 159303231Sdim friend class ErrorList; 160303231Sdim 161303231Sdim // handleErrors needs to be able to set the Checked flag. 162303231Sdim template <typename... HandlerTs> 163303231Sdim friend Error handleErrors(Error E, HandlerTs &&... Handlers); 164303231Sdim 165303231Sdim // Expected<T> needs to be able to steal the payload when constructed from an 166303231Sdim // error. 167314564Sdim template <typename T> friend class Expected; 168303231Sdim 169314564Sdimprotected: 170303231Sdim /// Create a success value. Prefer using 'Error::success()' for readability 171321369Sdim Error() { 172303231Sdim setPtr(nullptr); 173303231Sdim setChecked(false); 174303231Sdim } 175303231Sdim 176314564Sdimpublic: 177314564Sdim /// Create a success value. 178314564Sdim static ErrorSuccess success(); 179303231Sdim 180303231Sdim // Errors are not copy-constructable. 181303231Sdim Error(const Error &Other) = delete; 182303231Sdim 183303231Sdim /// Move-construct an error value. The newly constructed error is considered 184303231Sdim /// unchecked, even if the source error had been checked. The original error 185303231Sdim /// becomes a checked Success value, regardless of its original state. 186321369Sdim Error(Error &&Other) { 187303231Sdim setChecked(true); 188303231Sdim *this = std::move(Other); 189303231Sdim } 190303231Sdim 191303231Sdim /// Create an error value. Prefer using the 'make_error' function, but 192303231Sdim /// this constructor can be useful when "re-throwing" errors from handlers. 193303231Sdim Error(std::unique_ptr<ErrorInfoBase> Payload) { 194303231Sdim setPtr(Payload.release()); 195303231Sdim setChecked(false); 196303231Sdim } 197303231Sdim 198303231Sdim // Errors are not copy-assignable. 199303231Sdim Error &operator=(const Error &Other) = delete; 200303231Sdim 201303231Sdim /// Move-assign an error value. The current error must represent success, you 202303231Sdim /// you cannot overwrite an unhandled error. The current error is then 203303231Sdim /// considered unchecked. The source error becomes a checked success value, 204303231Sdim /// regardless of its original state. 205303231Sdim Error &operator=(Error &&Other) { 206303231Sdim // Don't allow overwriting of unchecked values. 207303231Sdim assertIsChecked(); 208303231Sdim setPtr(Other.getPtr()); 209303231Sdim 210303231Sdim // This Error is unchecked, even if the source error was checked. 211303231Sdim setChecked(false); 212303231Sdim 213303231Sdim // Null out Other's payload and set its checked bit. 214303231Sdim Other.setPtr(nullptr); 215303231Sdim Other.setChecked(true); 216303231Sdim 217303231Sdim return *this; 218303231Sdim } 219303231Sdim 220303231Sdim /// Destroy a Error. Fails with a call to abort() if the error is 221303231Sdim /// unchecked. 222303231Sdim ~Error() { 223303231Sdim assertIsChecked(); 224303231Sdim delete getPtr(); 225303231Sdim } 226303231Sdim 227303231Sdim /// Bool conversion. Returns true if this Error is in a failure state, 228303231Sdim /// and false if it is in an accept state. If the error is in a Success state 229303231Sdim /// it will be considered checked. 230303231Sdim explicit operator bool() { 231303231Sdim setChecked(getPtr() == nullptr); 232303231Sdim return getPtr() != nullptr; 233303231Sdim } 234303231Sdim 235303231Sdim /// Check whether one error is a subclass of another. 236303231Sdim template <typename ErrT> bool isA() const { 237303231Sdim return getPtr() && getPtr()->isA(ErrT::classID()); 238303231Sdim } 239303231Sdim 240321369Sdim /// Returns the dynamic class id of this error, or null if this is a success 241321369Sdim /// value. 242321369Sdim const void* dynamicClassID() const { 243321369Sdim if (!getPtr()) 244321369Sdim return nullptr; 245321369Sdim return getPtr()->dynamicClassID(); 246321369Sdim } 247321369Sdim 248303231Sdimprivate: 249327952Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 250327952Sdim // assertIsChecked() happens very frequently, but under normal circumstances 251327952Sdim // is supposed to be a no-op. So we want it to be inlined, but having a bunch 252327952Sdim // of debug prints can cause the function to be too large for inlining. So 253327952Sdim // it's important that we define this function out of line so that it can't be 254327952Sdim // inlined. 255327952Sdim LLVM_ATTRIBUTE_NORETURN 256327952Sdim void fatalUncheckedError() const; 257327952Sdim#endif 258327952Sdim 259303231Sdim void assertIsChecked() { 260314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 261327952Sdim if (LLVM_UNLIKELY(!getChecked() || getPtr())) 262327952Sdim fatalUncheckedError(); 263303231Sdim#endif 264303231Sdim } 265303231Sdim 266303231Sdim ErrorInfoBase *getPtr() const { 267314564Sdim return reinterpret_cast<ErrorInfoBase*>( 268314564Sdim reinterpret_cast<uintptr_t>(Payload) & 269314564Sdim ~static_cast<uintptr_t>(0x1)); 270303231Sdim } 271303231Sdim 272303231Sdim void setPtr(ErrorInfoBase *EI) { 273314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 274314564Sdim Payload = reinterpret_cast<ErrorInfoBase*>( 275314564Sdim (reinterpret_cast<uintptr_t>(EI) & 276314564Sdim ~static_cast<uintptr_t>(0x1)) | 277314564Sdim (reinterpret_cast<uintptr_t>(Payload) & 0x1)); 278303231Sdim#else 279303231Sdim Payload = EI; 280303231Sdim#endif 281303231Sdim } 282303231Sdim 283303231Sdim bool getChecked() const { 284314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 285314564Sdim return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0; 286303231Sdim#else 287303231Sdim return true; 288303231Sdim#endif 289303231Sdim } 290303231Sdim 291303231Sdim void setChecked(bool V) { 292314564Sdim Payload = reinterpret_cast<ErrorInfoBase*>( 293314564Sdim (reinterpret_cast<uintptr_t>(Payload) & 294314564Sdim ~static_cast<uintptr_t>(0x1)) | 295314564Sdim (V ? 0 : 1)); 296303231Sdim } 297303231Sdim 298303231Sdim std::unique_ptr<ErrorInfoBase> takePayload() { 299303231Sdim std::unique_ptr<ErrorInfoBase> Tmp(getPtr()); 300303231Sdim setPtr(nullptr); 301303231Sdim setChecked(true); 302303231Sdim return Tmp; 303303231Sdim } 304303231Sdim 305321369Sdim ErrorInfoBase *Payload = nullptr; 306303231Sdim}; 307303231Sdim 308314564Sdim/// Subclass of Error for the sole purpose of identifying the success path in 309314564Sdim/// the type system. This allows to catch invalid conversion to Expected<T> at 310314564Sdim/// compile time. 311314564Sdimclass ErrorSuccess : public Error {}; 312314564Sdim 313314564Sdiminline ErrorSuccess Error::success() { return ErrorSuccess(); } 314314564Sdim 315303231Sdim/// Make a Error instance representing failure using the given error info 316303231Sdim/// type. 317303231Sdimtemplate <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) { 318303231Sdim return Error(llvm::make_unique<ErrT>(std::forward<ArgTs>(Args)...)); 319303231Sdim} 320303231Sdim 321303231Sdim/// Base class for user error types. Users should declare their error types 322303231Sdim/// like: 323303231Sdim/// 324303231Sdim/// class MyError : public ErrorInfo<MyError> { 325303231Sdim/// .... 326303231Sdim/// }; 327303231Sdim/// 328303231Sdim/// This class provides an implementation of the ErrorInfoBase::kind 329303231Sdim/// method, which is used by the Error RTTI system. 330303231Sdimtemplate <typename ThisErrT, typename ParentErrT = ErrorInfoBase> 331303231Sdimclass ErrorInfo : public ParentErrT { 332303231Sdimpublic: 333321369Sdim static const void *classID() { return &ThisErrT::ID; } 334321369Sdim 335321369Sdim const void *dynamicClassID() const override { return &ThisErrT::ID; } 336321369Sdim 337303231Sdim bool isA(const void *const ClassID) const override { 338303231Sdim return ClassID == classID() || ParentErrT::isA(ClassID); 339303231Sdim } 340303231Sdim}; 341303231Sdim 342303231Sdim/// Special ErrorInfo subclass representing a list of ErrorInfos. 343303231Sdim/// Instances of this class are constructed by joinError. 344303231Sdimclass ErrorList final : public ErrorInfo<ErrorList> { 345303231Sdim // handleErrors needs to be able to iterate the payload list of an 346303231Sdim // ErrorList. 347303231Sdim template <typename... HandlerTs> 348303231Sdim friend Error handleErrors(Error E, HandlerTs &&... Handlers); 349303231Sdim 350303231Sdim // joinErrors is implemented in terms of join. 351303231Sdim friend Error joinErrors(Error, Error); 352303231Sdim 353303231Sdimpublic: 354303231Sdim void log(raw_ostream &OS) const override { 355303231Sdim OS << "Multiple errors:\n"; 356303231Sdim for (auto &ErrPayload : Payloads) { 357303231Sdim ErrPayload->log(OS); 358303231Sdim OS << "\n"; 359303231Sdim } 360303231Sdim } 361303231Sdim 362303231Sdim std::error_code convertToErrorCode() const override; 363303231Sdim 364303231Sdim // Used by ErrorInfo::classID. 365303231Sdim static char ID; 366303231Sdim 367303231Sdimprivate: 368303231Sdim ErrorList(std::unique_ptr<ErrorInfoBase> Payload1, 369303231Sdim std::unique_ptr<ErrorInfoBase> Payload2) { 370303231Sdim assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() && 371303231Sdim "ErrorList constructor payloads should be singleton errors"); 372303231Sdim Payloads.push_back(std::move(Payload1)); 373303231Sdim Payloads.push_back(std::move(Payload2)); 374303231Sdim } 375303231Sdim 376303231Sdim static Error join(Error E1, Error E2) { 377303231Sdim if (!E1) 378303231Sdim return E2; 379303231Sdim if (!E2) 380303231Sdim return E1; 381303231Sdim if (E1.isA<ErrorList>()) { 382303231Sdim auto &E1List = static_cast<ErrorList &>(*E1.getPtr()); 383303231Sdim if (E2.isA<ErrorList>()) { 384303231Sdim auto E2Payload = E2.takePayload(); 385303231Sdim auto &E2List = static_cast<ErrorList &>(*E2Payload); 386303231Sdim for (auto &Payload : E2List.Payloads) 387303231Sdim E1List.Payloads.push_back(std::move(Payload)); 388303231Sdim } else 389303231Sdim E1List.Payloads.push_back(E2.takePayload()); 390303231Sdim 391303231Sdim return E1; 392303231Sdim } 393303231Sdim if (E2.isA<ErrorList>()) { 394303231Sdim auto &E2List = static_cast<ErrorList &>(*E2.getPtr()); 395303231Sdim E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload()); 396303231Sdim return E2; 397303231Sdim } 398303231Sdim return Error(std::unique_ptr<ErrorList>( 399303231Sdim new ErrorList(E1.takePayload(), E2.takePayload()))); 400303231Sdim } 401303231Sdim 402303231Sdim std::vector<std::unique_ptr<ErrorInfoBase>> Payloads; 403303231Sdim}; 404303231Sdim 405303231Sdim/// Concatenate errors. The resulting Error is unchecked, and contains the 406303231Sdim/// ErrorInfo(s), if any, contained in E1, followed by the 407303231Sdim/// ErrorInfo(s), if any, contained in E2. 408303231Sdiminline Error joinErrors(Error E1, Error E2) { 409303231Sdim return ErrorList::join(std::move(E1), std::move(E2)); 410303231Sdim} 411303231Sdim 412303231Sdim/// Tagged union holding either a T or a Error. 413303231Sdim/// 414303231Sdim/// This class parallels ErrorOr, but replaces error_code with Error. Since 415303231Sdim/// Error cannot be copied, this class replaces getError() with 416303231Sdim/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the 417303231Sdim/// error class type. 418314564Sdimtemplate <class T> class LLVM_NODISCARD Expected { 419321369Sdim template <class T1> friend class ExpectedAsOutParameter; 420303231Sdim template <class OtherT> friend class Expected; 421321369Sdim 422303231Sdim static const bool isRef = std::is_reference<T>::value; 423303231Sdim 424321369Sdim using wrap = ReferenceStorage<typename std::remove_reference<T>::type>; 425303231Sdim 426321369Sdim using error_type = std::unique_ptr<ErrorInfoBase>; 427321369Sdim 428303231Sdimpublic: 429321369Sdim using storage_type = typename std::conditional<isRef, wrap, T>::type; 430321369Sdim using value_type = T; 431303231Sdim 432303231Sdimprivate: 433321369Sdim using reference = typename std::remove_reference<T>::type &; 434321369Sdim using const_reference = const typename std::remove_reference<T>::type &; 435321369Sdim using pointer = typename std::remove_reference<T>::type *; 436321369Sdim using const_pointer = const typename std::remove_reference<T>::type *; 437303231Sdim 438303231Sdimpublic: 439303231Sdim /// Create an Expected<T> error value from the given Error. 440303231Sdim Expected(Error Err) 441303231Sdim : HasError(true) 442314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 443314564Sdim // Expected is unchecked upon construction in Debug builds. 444314564Sdim , Unchecked(true) 445303231Sdim#endif 446303231Sdim { 447303231Sdim assert(Err && "Cannot create Expected<T> from Error success value."); 448314564Sdim new (getErrorStorage()) error_type(Err.takePayload()); 449303231Sdim } 450303231Sdim 451314564Sdim /// Forbid to convert from Error::success() implicitly, this avoids having 452314564Sdim /// Expected<T> foo() { return Error::success(); } which compiles otherwise 453314564Sdim /// but triggers the assertion above. 454314564Sdim Expected(ErrorSuccess) = delete; 455314564Sdim 456303231Sdim /// Create an Expected<T> success value from the given OtherT value, which 457303231Sdim /// must be convertible to T. 458303231Sdim template <typename OtherT> 459303231Sdim Expected(OtherT &&Val, 460303231Sdim typename std::enable_if<std::is_convertible<OtherT, T>::value>::type 461303231Sdim * = nullptr) 462303231Sdim : HasError(false) 463314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 464314564Sdim // Expected is unchecked upon construction in Debug builds. 465314564Sdim , Unchecked(true) 466303231Sdim#endif 467303231Sdim { 468303231Sdim new (getStorage()) storage_type(std::forward<OtherT>(Val)); 469303231Sdim } 470303231Sdim 471303231Sdim /// Move construct an Expected<T> value. 472303231Sdim Expected(Expected &&Other) { moveConstruct(std::move(Other)); } 473303231Sdim 474303231Sdim /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 475303231Sdim /// must be convertible to T. 476303231Sdim template <class OtherT> 477303231Sdim Expected(Expected<OtherT> &&Other, 478303231Sdim typename std::enable_if<std::is_convertible<OtherT, T>::value>::type 479303231Sdim * = nullptr) { 480303231Sdim moveConstruct(std::move(Other)); 481303231Sdim } 482303231Sdim 483303231Sdim /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT 484303231Sdim /// isn't convertible to T. 485303231Sdim template <class OtherT> 486303231Sdim explicit Expected( 487303231Sdim Expected<OtherT> &&Other, 488303231Sdim typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * = 489303231Sdim nullptr) { 490303231Sdim moveConstruct(std::move(Other)); 491303231Sdim } 492303231Sdim 493303231Sdim /// Move-assign from another Expected<T>. 494303231Sdim Expected &operator=(Expected &&Other) { 495303231Sdim moveAssign(std::move(Other)); 496303231Sdim return *this; 497303231Sdim } 498303231Sdim 499303231Sdim /// Destroy an Expected<T>. 500303231Sdim ~Expected() { 501303231Sdim assertIsChecked(); 502303231Sdim if (!HasError) 503303231Sdim getStorage()->~storage_type(); 504303231Sdim else 505303231Sdim getErrorStorage()->~error_type(); 506303231Sdim } 507303231Sdim 508303231Sdim /// \brief Return false if there is an error. 509303231Sdim explicit operator bool() { 510314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 511314564Sdim Unchecked = HasError; 512303231Sdim#endif 513303231Sdim return !HasError; 514303231Sdim } 515303231Sdim 516303231Sdim /// \brief Returns a reference to the stored T value. 517303231Sdim reference get() { 518303231Sdim assertIsChecked(); 519303231Sdim return *getStorage(); 520303231Sdim } 521303231Sdim 522303231Sdim /// \brief Returns a const reference to the stored T value. 523303231Sdim const_reference get() const { 524303231Sdim assertIsChecked(); 525303231Sdim return const_cast<Expected<T> *>(this)->get(); 526303231Sdim } 527303231Sdim 528303231Sdim /// \brief Check that this Expected<T> is an error of type ErrT. 529303231Sdim template <typename ErrT> bool errorIsA() const { 530321369Sdim return HasError && (*getErrorStorage())->template isA<ErrT>(); 531303231Sdim } 532303231Sdim 533303231Sdim /// \brief Take ownership of the stored error. 534303231Sdim /// After calling this the Expected<T> is in an indeterminate state that can 535303231Sdim /// only be safely destructed. No further calls (beside the destructor) should 536303231Sdim /// be made on the Expected<T> vaule. 537303231Sdim Error takeError() { 538314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 539314564Sdim Unchecked = false; 540303231Sdim#endif 541303231Sdim return HasError ? Error(std::move(*getErrorStorage())) : Error::success(); 542303231Sdim } 543303231Sdim 544303231Sdim /// \brief Returns a pointer to the stored T value. 545303231Sdim pointer operator->() { 546303231Sdim assertIsChecked(); 547303231Sdim return toPointer(getStorage()); 548303231Sdim } 549303231Sdim 550303231Sdim /// \brief Returns a const pointer to the stored T value. 551303231Sdim const_pointer operator->() const { 552303231Sdim assertIsChecked(); 553303231Sdim return toPointer(getStorage()); 554303231Sdim } 555303231Sdim 556303231Sdim /// \brief Returns a reference to the stored T value. 557303231Sdim reference operator*() { 558303231Sdim assertIsChecked(); 559303231Sdim return *getStorage(); 560303231Sdim } 561303231Sdim 562303231Sdim /// \brief Returns a const reference to the stored T value. 563303231Sdim const_reference operator*() const { 564303231Sdim assertIsChecked(); 565303231Sdim return *getStorage(); 566303231Sdim } 567303231Sdim 568303231Sdimprivate: 569303231Sdim template <class T1> 570303231Sdim static bool compareThisIfSameType(const T1 &a, const T1 &b) { 571303231Sdim return &a == &b; 572303231Sdim } 573303231Sdim 574303231Sdim template <class T1, class T2> 575303231Sdim static bool compareThisIfSameType(const T1 &a, const T2 &b) { 576303231Sdim return false; 577303231Sdim } 578303231Sdim 579303231Sdim template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) { 580303231Sdim HasError = Other.HasError; 581314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 582314564Sdim Unchecked = true; 583314564Sdim Other.Unchecked = false; 584303231Sdim#endif 585303231Sdim 586303231Sdim if (!HasError) 587303231Sdim new (getStorage()) storage_type(std::move(*Other.getStorage())); 588303231Sdim else 589303231Sdim new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage())); 590303231Sdim } 591303231Sdim 592303231Sdim template <class OtherT> void moveAssign(Expected<OtherT> &&Other) { 593303231Sdim assertIsChecked(); 594303231Sdim 595303231Sdim if (compareThisIfSameType(*this, Other)) 596303231Sdim return; 597303231Sdim 598303231Sdim this->~Expected(); 599303231Sdim new (this) Expected(std::move(Other)); 600303231Sdim } 601303231Sdim 602303231Sdim pointer toPointer(pointer Val) { return Val; } 603303231Sdim 604303231Sdim const_pointer toPointer(const_pointer Val) const { return Val; } 605303231Sdim 606303231Sdim pointer toPointer(wrap *Val) { return &Val->get(); } 607303231Sdim 608303231Sdim const_pointer toPointer(const wrap *Val) const { return &Val->get(); } 609303231Sdim 610303231Sdim storage_type *getStorage() { 611303231Sdim assert(!HasError && "Cannot get value when an error exists!"); 612303231Sdim return reinterpret_cast<storage_type *>(TStorage.buffer); 613303231Sdim } 614303231Sdim 615303231Sdim const storage_type *getStorage() const { 616303231Sdim assert(!HasError && "Cannot get value when an error exists!"); 617303231Sdim return reinterpret_cast<const storage_type *>(TStorage.buffer); 618303231Sdim } 619303231Sdim 620303231Sdim error_type *getErrorStorage() { 621303231Sdim assert(HasError && "Cannot get error when a value exists!"); 622303231Sdim return reinterpret_cast<error_type *>(ErrorStorage.buffer); 623303231Sdim } 624303231Sdim 625321369Sdim const error_type *getErrorStorage() const { 626321369Sdim assert(HasError && "Cannot get error when a value exists!"); 627321369Sdim return reinterpret_cast<const error_type *>(ErrorStorage.buffer); 628321369Sdim } 629321369Sdim 630321369Sdim // Used by ExpectedAsOutParameter to reset the checked flag. 631321369Sdim void setUnchecked() { 632321369Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 633321369Sdim Unchecked = true; 634321369Sdim#endif 635321369Sdim } 636321369Sdim 637327952Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 638327952Sdim LLVM_ATTRIBUTE_NORETURN 639327952Sdim LLVM_ATTRIBUTE_NOINLINE 640327952Sdim void fatalUncheckedExpected() const { 641327952Sdim dbgs() << "Expected<T> must be checked before access or destruction.\n"; 642327952Sdim if (HasError) { 643327952Sdim dbgs() << "Unchecked Expected<T> contained error:\n"; 644327952Sdim (*getErrorStorage())->log(dbgs()); 645327952Sdim } else 646327952Sdim dbgs() << "Expected<T> value was in success state. (Note: Expected<T> " 647327952Sdim "values in success mode must still be checked prior to being " 648327952Sdim "destroyed).\n"; 649327952Sdim abort(); 650327952Sdim } 651327952Sdim#endif 652327952Sdim 653303231Sdim void assertIsChecked() { 654314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 655327952Sdim if (LLVM_UNLIKELY(Unchecked)) 656327952Sdim fatalUncheckedExpected(); 657303231Sdim#endif 658303231Sdim } 659303231Sdim 660303231Sdim union { 661303231Sdim AlignedCharArrayUnion<storage_type> TStorage; 662303231Sdim AlignedCharArrayUnion<error_type> ErrorStorage; 663303231Sdim }; 664303231Sdim bool HasError : 1; 665314564Sdim#if LLVM_ENABLE_ABI_BREAKING_CHECKS 666314564Sdim bool Unchecked : 1; 667303231Sdim#endif 668303231Sdim}; 669303231Sdim 670327952Sdim/// Report a serious error, calling any installed error handler. See 671327952Sdim/// ErrorHandling.h. 672327952SdimLLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, 673327952Sdim bool gen_crash_diag = true); 674327952Sdim 675327952Sdim/// Report a fatal error if Err is a failure value. 676327952Sdim/// 677327952Sdim/// This function can be used to wrap calls to fallible functions ONLY when it 678327952Sdim/// is known that the Error will always be a success value. E.g. 679327952Sdim/// 680327952Sdim/// @code{.cpp} 681327952Sdim/// // foo only attempts the fallible operation if DoFallibleOperation is 682327952Sdim/// // true. If DoFallibleOperation is false then foo always returns 683327952Sdim/// // Error::success(). 684327952Sdim/// Error foo(bool DoFallibleOperation); 685327952Sdim/// 686327952Sdim/// cantFail(foo(false)); 687327952Sdim/// @endcode 688327952Sdiminline void cantFail(Error Err, const char *Msg = nullptr) { 689327952Sdim if (Err) { 690327952Sdim if (!Msg) 691327952Sdim Msg = "Failure value returned from cantFail wrapped call"; 692327952Sdim llvm_unreachable(Msg); 693327952Sdim } 694327952Sdim} 695327952Sdim 696327952Sdim/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 697327952Sdim/// returns the contained value. 698327952Sdim/// 699327952Sdim/// This function can be used to wrap calls to fallible functions ONLY when it 700327952Sdim/// is known that the Error will always be a success value. E.g. 701327952Sdim/// 702327952Sdim/// @code{.cpp} 703327952Sdim/// // foo only attempts the fallible operation if DoFallibleOperation is 704327952Sdim/// // true. If DoFallibleOperation is false then foo always returns an int. 705327952Sdim/// Expected<int> foo(bool DoFallibleOperation); 706327952Sdim/// 707327952Sdim/// int X = cantFail(foo(false)); 708327952Sdim/// @endcode 709327952Sdimtemplate <typename T> 710327952SdimT cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) { 711327952Sdim if (ValOrErr) 712327952Sdim return std::move(*ValOrErr); 713327952Sdim else { 714327952Sdim if (!Msg) 715327952Sdim Msg = "Failure value returned from cantFail wrapped call"; 716327952Sdim llvm_unreachable(Msg); 717327952Sdim } 718327952Sdim} 719327952Sdim 720327952Sdim/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and 721327952Sdim/// returns the contained reference. 722327952Sdim/// 723327952Sdim/// This function can be used to wrap calls to fallible functions ONLY when it 724327952Sdim/// is known that the Error will always be a success value. E.g. 725327952Sdim/// 726327952Sdim/// @code{.cpp} 727327952Sdim/// // foo only attempts the fallible operation if DoFallibleOperation is 728327952Sdim/// // true. If DoFallibleOperation is false then foo always returns a Bar&. 729327952Sdim/// Expected<Bar&> foo(bool DoFallibleOperation); 730327952Sdim/// 731327952Sdim/// Bar &X = cantFail(foo(false)); 732327952Sdim/// @endcode 733327952Sdimtemplate <typename T> 734327952SdimT& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) { 735327952Sdim if (ValOrErr) 736327952Sdim return *ValOrErr; 737327952Sdim else { 738327952Sdim if (!Msg) 739327952Sdim Msg = "Failure value returned from cantFail wrapped call"; 740327952Sdim llvm_unreachable(Msg); 741327952Sdim } 742327952Sdim} 743327952Sdim 744327952Sdim/// Helper for testing applicability of, and applying, handlers for 745327952Sdim/// ErrorInfo types. 746327952Sdimtemplate <typename HandlerT> 747327952Sdimclass ErrorHandlerTraits 748327952Sdim : public ErrorHandlerTraits<decltype( 749327952Sdim &std::remove_reference<HandlerT>::type::operator())> {}; 750327952Sdim 751327952Sdim// Specialization functions of the form 'Error (const ErrT&)'. 752327952Sdimtemplate <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> { 753327952Sdimpublic: 754327952Sdim static bool appliesTo(const ErrorInfoBase &E) { 755327952Sdim return E.template isA<ErrT>(); 756327952Sdim } 757327952Sdim 758327952Sdim template <typename HandlerT> 759327952Sdim static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 760327952Sdim assert(appliesTo(*E) && "Applying incorrect handler"); 761327952Sdim return H(static_cast<ErrT &>(*E)); 762327952Sdim } 763327952Sdim}; 764327952Sdim 765327952Sdim// Specialization functions of the form 'void (const ErrT&)'. 766327952Sdimtemplate <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> { 767327952Sdimpublic: 768327952Sdim static bool appliesTo(const ErrorInfoBase &E) { 769327952Sdim return E.template isA<ErrT>(); 770327952Sdim } 771327952Sdim 772327952Sdim template <typename HandlerT> 773327952Sdim static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 774327952Sdim assert(appliesTo(*E) && "Applying incorrect handler"); 775327952Sdim H(static_cast<ErrT &>(*E)); 776327952Sdim return Error::success(); 777327952Sdim } 778327952Sdim}; 779327952Sdim 780327952Sdim/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'. 781327952Sdimtemplate <typename ErrT> 782327952Sdimclass ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> { 783327952Sdimpublic: 784327952Sdim static bool appliesTo(const ErrorInfoBase &E) { 785327952Sdim return E.template isA<ErrT>(); 786327952Sdim } 787327952Sdim 788327952Sdim template <typename HandlerT> 789327952Sdim static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 790327952Sdim assert(appliesTo(*E) && "Applying incorrect handler"); 791327952Sdim std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 792327952Sdim return H(std::move(SubE)); 793327952Sdim } 794327952Sdim}; 795327952Sdim 796327952Sdim/// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'. 797327952Sdimtemplate <typename ErrT> 798327952Sdimclass ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> { 799327952Sdimpublic: 800327952Sdim static bool appliesTo(const ErrorInfoBase &E) { 801327952Sdim return E.template isA<ErrT>(); 802327952Sdim } 803327952Sdim 804327952Sdim template <typename HandlerT> 805327952Sdim static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) { 806327952Sdim assert(appliesTo(*E) && "Applying incorrect handler"); 807327952Sdim std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release())); 808327952Sdim H(std::move(SubE)); 809327952Sdim return Error::success(); 810327952Sdim } 811327952Sdim}; 812327952Sdim 813327952Sdim// Specialization for member functions of the form 'RetT (const ErrT&)'. 814327952Sdimtemplate <typename C, typename RetT, typename ErrT> 815327952Sdimclass ErrorHandlerTraits<RetT (C::*)(ErrT &)> 816327952Sdim : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 817327952Sdim 818327952Sdim// Specialization for member functions of the form 'RetT (const ErrT&) const'. 819327952Sdimtemplate <typename C, typename RetT, typename ErrT> 820327952Sdimclass ErrorHandlerTraits<RetT (C::*)(ErrT &) const> 821327952Sdim : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 822327952Sdim 823327952Sdim// Specialization for member functions of the form 'RetT (const ErrT&)'. 824327952Sdimtemplate <typename C, typename RetT, typename ErrT> 825327952Sdimclass ErrorHandlerTraits<RetT (C::*)(const ErrT &)> 826327952Sdim : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 827327952Sdim 828327952Sdim// Specialization for member functions of the form 'RetT (const ErrT&) const'. 829327952Sdimtemplate <typename C, typename RetT, typename ErrT> 830327952Sdimclass ErrorHandlerTraits<RetT (C::*)(const ErrT &) const> 831327952Sdim : public ErrorHandlerTraits<RetT (&)(ErrT &)> {}; 832327952Sdim 833327952Sdim/// Specialization for member functions of the form 834327952Sdim/// 'RetT (std::unique_ptr<ErrT>)'. 835327952Sdimtemplate <typename C, typename RetT, typename ErrT> 836327952Sdimclass ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)> 837327952Sdim : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 838327952Sdim 839327952Sdim/// Specialization for member functions of the form 840327952Sdim/// 'RetT (std::unique_ptr<ErrT>) const'. 841327952Sdimtemplate <typename C, typename RetT, typename ErrT> 842327952Sdimclass ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const> 843327952Sdim : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {}; 844327952Sdim 845327952Sdiminline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) { 846327952Sdim return Error(std::move(Payload)); 847327952Sdim} 848327952Sdim 849327952Sdimtemplate <typename HandlerT, typename... HandlerTs> 850327952SdimError handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload, 851327952Sdim HandlerT &&Handler, HandlerTs &&... Handlers) { 852327952Sdim if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload)) 853327952Sdim return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler), 854327952Sdim std::move(Payload)); 855327952Sdim return handleErrorImpl(std::move(Payload), 856327952Sdim std::forward<HandlerTs>(Handlers)...); 857327952Sdim} 858327952Sdim 859327952Sdim/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any 860327952Sdim/// unhandled errors (or Errors returned by handlers) are re-concatenated and 861327952Sdim/// returned. 862327952Sdim/// Because this function returns an error, its result must also be checked 863327952Sdim/// or returned. If you intend to handle all errors use handleAllErrors 864327952Sdim/// (which returns void, and will abort() on unhandled errors) instead. 865327952Sdimtemplate <typename... HandlerTs> 866327952SdimError handleErrors(Error E, HandlerTs &&... Hs) { 867327952Sdim if (!E) 868327952Sdim return Error::success(); 869327952Sdim 870327952Sdim std::unique_ptr<ErrorInfoBase> Payload = E.takePayload(); 871327952Sdim 872327952Sdim if (Payload->isA<ErrorList>()) { 873327952Sdim ErrorList &List = static_cast<ErrorList &>(*Payload); 874327952Sdim Error R; 875327952Sdim for (auto &P : List.Payloads) 876327952Sdim R = ErrorList::join( 877327952Sdim std::move(R), 878327952Sdim handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...)); 879327952Sdim return R; 880327952Sdim } 881327952Sdim 882327952Sdim return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...); 883327952Sdim} 884327952Sdim 885327952Sdim/// Behaves the same as handleErrors, except that it requires that all 886327952Sdim/// errors be handled by the given handlers. If any unhandled error remains 887327952Sdim/// after the handlers have run, report_fatal_error() will be called. 888327952Sdimtemplate <typename... HandlerTs> 889327952Sdimvoid handleAllErrors(Error E, HandlerTs &&... Handlers) { 890327952Sdim cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...)); 891327952Sdim} 892327952Sdim 893327952Sdim/// Check that E is a non-error, then drop it. 894327952Sdim/// If E is an error report_fatal_error will be called. 895327952Sdiminline void handleAllErrors(Error E) { 896327952Sdim cantFail(std::move(E)); 897327952Sdim} 898327952Sdim 899327952Sdim/// Handle any errors (if present) in an Expected<T>, then try a recovery path. 900327952Sdim/// 901327952Sdim/// If the incoming value is a success value it is returned unmodified. If it 902327952Sdim/// is a failure value then it the contained error is passed to handleErrors. 903327952Sdim/// If handleErrors is able to handle the error then the RecoveryPath functor 904327952Sdim/// is called to supply the final result. If handleErrors is not able to 905327952Sdim/// handle all errors then the unhandled errors are returned. 906327952Sdim/// 907327952Sdim/// This utility enables the follow pattern: 908327952Sdim/// 909327952Sdim/// @code{.cpp} 910327952Sdim/// enum FooStrategy { Aggressive, Conservative }; 911327952Sdim/// Expected<Foo> foo(FooStrategy S); 912327952Sdim/// 913327952Sdim/// auto ResultOrErr = 914327952Sdim/// handleExpected( 915327952Sdim/// foo(Aggressive), 916327952Sdim/// []() { return foo(Conservative); }, 917327952Sdim/// [](AggressiveStrategyError&) { 918327952Sdim/// // Implicitly conusme this - we'll recover by using a conservative 919327952Sdim/// // strategy. 920327952Sdim/// }); 921327952Sdim/// 922327952Sdim/// @endcode 923327952Sdimtemplate <typename T, typename RecoveryFtor, typename... HandlerTs> 924327952SdimExpected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath, 925327952Sdim HandlerTs &&... Handlers) { 926327952Sdim if (ValOrErr) 927327952Sdim return ValOrErr; 928327952Sdim 929327952Sdim if (auto Err = handleErrors(ValOrErr.takeError(), 930327952Sdim std::forward<HandlerTs>(Handlers)...)) 931327952Sdim return std::move(Err); 932327952Sdim 933327952Sdim return RecoveryPath(); 934327952Sdim} 935327952Sdim 936327952Sdim/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner 937327952Sdim/// will be printed before the first one is logged. A newline will be printed 938327952Sdim/// after each error. 939327952Sdim/// 940327952Sdim/// This is useful in the base level of your program to allow clean termination 941327952Sdim/// (allowing clean deallocation of resources, etc.), while reporting error 942327952Sdim/// information to the user. 943327952Sdimvoid logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner); 944327952Sdim 945327952Sdim/// Write all error messages (if any) in E to a string. The newline character 946327952Sdim/// is used to separate error messages. 947327952Sdiminline std::string toString(Error E) { 948327952Sdim SmallVector<std::string, 2> Errors; 949327952Sdim handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) { 950327952Sdim Errors.push_back(EI.message()); 951327952Sdim }); 952327952Sdim return join(Errors.begin(), Errors.end(), "\n"); 953327952Sdim} 954327952Sdim 955327952Sdim/// Consume a Error without doing anything. This method should be used 956327952Sdim/// only where an error can be considered a reasonable and expected return 957327952Sdim/// value. 958327952Sdim/// 959327952Sdim/// Uses of this method are potentially indicative of design problems: If it's 960327952Sdim/// legitimate to do nothing while processing an "error", the error-producer 961327952Sdim/// might be more clearly refactored to return an Optional<T>. 962327952Sdiminline void consumeError(Error Err) { 963327952Sdim handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {}); 964327952Sdim} 965327952Sdim 966327952Sdim/// Helper for Errors used as out-parameters. 967327952Sdim/// 968327952Sdim/// This helper is for use with the Error-as-out-parameter idiom, where an error 969327952Sdim/// is passed to a function or method by reference, rather than being returned. 970327952Sdim/// In such cases it is helpful to set the checked bit on entry to the function 971327952Sdim/// so that the error can be written to (unchecked Errors abort on assignment) 972327952Sdim/// and clear the checked bit on exit so that clients cannot accidentally forget 973327952Sdim/// to check the result. This helper performs these actions automatically using 974327952Sdim/// RAII: 975327952Sdim/// 976327952Sdim/// @code{.cpp} 977327952Sdim/// Result foo(Error &Err) { 978327952Sdim/// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set 979327952Sdim/// // <body of foo> 980327952Sdim/// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed. 981327952Sdim/// } 982327952Sdim/// @endcode 983327952Sdim/// 984327952Sdim/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be 985327952Sdim/// used with optional Errors (Error pointers that are allowed to be null). If 986327952Sdim/// ErrorAsOutParameter took an Error reference, an instance would have to be 987327952Sdim/// created inside every condition that verified that Error was non-null. By 988327952Sdim/// taking an Error pointer we can just create one instance at the top of the 989327952Sdim/// function. 990327952Sdimclass ErrorAsOutParameter { 991327952Sdimpublic: 992327952Sdim ErrorAsOutParameter(Error *Err) : Err(Err) { 993327952Sdim // Raise the checked bit if Err is success. 994327952Sdim if (Err) 995327952Sdim (void)!!*Err; 996327952Sdim } 997327952Sdim 998327952Sdim ~ErrorAsOutParameter() { 999327952Sdim // Clear the checked bit. 1000327952Sdim if (Err && !*Err) 1001327952Sdim *Err = Error::success(); 1002327952Sdim } 1003327952Sdim 1004327952Sdimprivate: 1005327952Sdim Error *Err; 1006327952Sdim}; 1007327952Sdim 1008321369Sdim/// Helper for Expected<T>s used as out-parameters. 1009321369Sdim/// 1010321369Sdim/// See ErrorAsOutParameter. 1011321369Sdimtemplate <typename T> 1012321369Sdimclass ExpectedAsOutParameter { 1013321369Sdimpublic: 1014321369Sdim ExpectedAsOutParameter(Expected<T> *ValOrErr) 1015321369Sdim : ValOrErr(ValOrErr) { 1016321369Sdim if (ValOrErr) 1017321369Sdim (void)!!*ValOrErr; 1018321369Sdim } 1019321369Sdim 1020321369Sdim ~ExpectedAsOutParameter() { 1021321369Sdim if (ValOrErr) 1022321369Sdim ValOrErr->setUnchecked(); 1023321369Sdim } 1024321369Sdim 1025321369Sdimprivate: 1026321369Sdim Expected<T> *ValOrErr; 1027321369Sdim}; 1028321369Sdim 1029303231Sdim/// This class wraps a std::error_code in a Error. 1030303231Sdim/// 1031303231Sdim/// This is useful if you're writing an interface that returns a Error 1032303231Sdim/// (or Expected) and you want to call code that still returns 1033303231Sdim/// std::error_codes. 1034303231Sdimclass ECError : public ErrorInfo<ECError> { 1035303231Sdim friend Error errorCodeToError(std::error_code); 1036314564Sdim 1037303231Sdimpublic: 1038303231Sdim void setErrorCode(std::error_code EC) { this->EC = EC; } 1039303231Sdim std::error_code convertToErrorCode() const override { return EC; } 1040303231Sdim void log(raw_ostream &OS) const override { OS << EC.message(); } 1041303231Sdim 1042303231Sdim // Used by ErrorInfo::classID. 1043303231Sdim static char ID; 1044303231Sdim 1045303231Sdimprotected: 1046303231Sdim ECError() = default; 1047303231Sdim ECError(std::error_code EC) : EC(EC) {} 1048314564Sdim 1049303231Sdim std::error_code EC; 1050303231Sdim}; 1051303231Sdim 1052303231Sdim/// The value returned by this function can be returned from convertToErrorCode 1053303231Sdim/// for Error values where no sensible translation to std::error_code exists. 1054303231Sdim/// It should only be used in this situation, and should never be used where a 1055303231Sdim/// sensible conversion to std::error_code is available, as attempts to convert 1056303231Sdim/// to/from this error will result in a fatal error. (i.e. it is a programmatic 1057303231Sdim///error to try to convert such a value). 1058303231Sdimstd::error_code inconvertibleErrorCode(); 1059303231Sdim 1060303231Sdim/// Helper for converting an std::error_code to a Error. 1061303231SdimError errorCodeToError(std::error_code EC); 1062303231Sdim 1063303231Sdim/// Helper for converting an ECError to a std::error_code. 1064303231Sdim/// 1065303231Sdim/// This method requires that Err be Error() or an ECError, otherwise it 1066303231Sdim/// will trigger a call to abort(). 1067303231Sdimstd::error_code errorToErrorCode(Error Err); 1068303231Sdim 1069303231Sdim/// Convert an ErrorOr<T> to an Expected<T>. 1070303231Sdimtemplate <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) { 1071303231Sdim if (auto EC = EO.getError()) 1072303231Sdim return errorCodeToError(EC); 1073303231Sdim return std::move(*EO); 1074303231Sdim} 1075303231Sdim 1076303231Sdim/// Convert an Expected<T> to an ErrorOr<T>. 1077303231Sdimtemplate <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) { 1078303231Sdim if (auto Err = E.takeError()) 1079303231Sdim return errorToErrorCode(std::move(Err)); 1080303231Sdim return std::move(*E); 1081303231Sdim} 1082303231Sdim 1083303231Sdim/// This class wraps a string in an Error. 1084303231Sdim/// 1085303231Sdim/// StringError is useful in cases where the client is not expected to be able 1086303231Sdim/// to consume the specific error message programmatically (for example, if the 1087303231Sdim/// error message is to be presented to the user). 1088303231Sdimclass StringError : public ErrorInfo<StringError> { 1089303231Sdimpublic: 1090303231Sdim static char ID; 1091314564Sdim 1092303231Sdim StringError(const Twine &S, std::error_code EC); 1093314564Sdim 1094303231Sdim void log(raw_ostream &OS) const override; 1095303231Sdim std::error_code convertToErrorCode() const override; 1096314564Sdim 1097321369Sdim const std::string &getMessage() const { return Msg; } 1098321369Sdim 1099303231Sdimprivate: 1100303231Sdim std::string Msg; 1101303231Sdim std::error_code EC; 1102303231Sdim}; 1103303231Sdim 1104303231Sdim/// Helper for check-and-exit error handling. 1105303231Sdim/// 1106303231Sdim/// For tool use only. NOT FOR USE IN LIBRARY CODE. 1107303231Sdim/// 1108303231Sdimclass ExitOnError { 1109303231Sdimpublic: 1110303231Sdim /// Create an error on exit helper. 1111303231Sdim ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1) 1112303231Sdim : Banner(std::move(Banner)), 1113303231Sdim GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {} 1114303231Sdim 1115303231Sdim /// Set the banner string for any errors caught by operator(). 1116303231Sdim void setBanner(std::string Banner) { this->Banner = std::move(Banner); } 1117303231Sdim 1118303231Sdim /// Set the exit-code mapper function. 1119303231Sdim void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) { 1120303231Sdim this->GetExitCode = std::move(GetExitCode); 1121303231Sdim } 1122303231Sdim 1123303231Sdim /// Check Err. If it's in a failure state log the error(s) and exit. 1124303231Sdim void operator()(Error Err) const { checkError(std::move(Err)); } 1125303231Sdim 1126303231Sdim /// Check E. If it's in a success state then return the contained value. If 1127303231Sdim /// it's in a failure state log the error(s) and exit. 1128303231Sdim template <typename T> T operator()(Expected<T> &&E) const { 1129303231Sdim checkError(E.takeError()); 1130303231Sdim return std::move(*E); 1131303231Sdim } 1132303231Sdim 1133303231Sdim /// Check E. If it's in a success state then return the contained reference. If 1134303231Sdim /// it's in a failure state log the error(s) and exit. 1135303231Sdim template <typename T> T& operator()(Expected<T&> &&E) const { 1136303231Sdim checkError(E.takeError()); 1137303231Sdim return *E; 1138303231Sdim } 1139303231Sdim 1140303231Sdimprivate: 1141303231Sdim void checkError(Error Err) const { 1142303231Sdim if (Err) { 1143303231Sdim int ExitCode = GetExitCode(Err); 1144303231Sdim logAllUnhandledErrors(std::move(Err), errs(), Banner); 1145303231Sdim exit(ExitCode); 1146303231Sdim } 1147303231Sdim } 1148303231Sdim 1149303231Sdim std::string Banner; 1150303231Sdim std::function<int(const Error &)> GetExitCode; 1151303231Sdim}; 1152303231Sdim 1153314564Sdim} // end namespace llvm 1154303231Sdim 1155303231Sdim#endif // LLVM_SUPPORT_ERROR_H 1156