LLVM  6.0.0svn
Error.h
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1 //===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines an API used to report recoverable errors.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_ERROR_H
15 #define LLVM_SUPPORT_ERROR_H
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/STLExtras.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"
26 #include "llvm/Support/ErrorOr.h"
28 #include <algorithm>
29 #include <cassert>
30 #include <cstdint>
31 #include <cstdlib>
32 #include <functional>
33 #include <memory>
34 #include <new>
35 #include <string>
36 #include <system_error>
37 #include <type_traits>
38 #include <utility>
39 #include <vector>
40 
41 namespace llvm {
42 
43 class ErrorSuccess;
44 
45 /// Base class for error info classes. Do not extend this directly: Extend
46 /// the ErrorInfo template subclass instead.
48 public:
49  virtual ~ErrorInfoBase() = default;
50 
51  /// Print an error message to an output stream.
52  virtual void log(raw_ostream &OS) const = 0;
53 
54  /// Return the error message as a string.
55  virtual std::string message() const {
56  std::string Msg;
57  raw_string_ostream OS(Msg);
58  log(OS);
59  return OS.str();
60  }
61 
62  /// Convert this error to a std::error_code.
63  ///
64  /// This is a temporary crutch to enable interaction with code still
65  /// using std::error_code. It will be removed in the future.
66  virtual std::error_code convertToErrorCode() const = 0;
67 
68  // Returns the class ID for this type.
69  static const void *classID() { return &ID; }
70 
71  // Returns the class ID for the dynamic type of this ErrorInfoBase instance.
72  virtual const void *dynamicClassID() const = 0;
73 
74  // Check whether this instance is a subclass of the class identified by
75  // ClassID.
76  virtual bool isA(const void *const ClassID) const {
77  return ClassID == classID();
78  }
79 
80  // Check whether this instance is a subclass of ErrorInfoT.
81  template <typename ErrorInfoT> bool isA() const {
82  return isA(ErrorInfoT::classID());
83  }
84 
85 private:
86  virtual void anchor();
87 
88  static char ID;
89 };
90 
91 /// Lightweight error class with error context and mandatory checking.
92 ///
93 /// Instances of this class wrap a ErrorInfoBase pointer. Failure states
94 /// are represented by setting the pointer to a ErrorInfoBase subclass
95 /// instance containing information describing the failure. Success is
96 /// represented by a null pointer value.
97 ///
98 /// Instances of Error also contains a 'Checked' flag, which must be set
99 /// before the destructor is called, otherwise the destructor will trigger a
100 /// runtime error. This enforces at runtime the requirement that all Error
101 /// instances be checked or returned to the caller.
102 ///
103 /// There are two ways to set the checked flag, depending on what state the
104 /// Error instance is in. For Error instances indicating success, it
105 /// is sufficient to invoke the boolean conversion operator. E.g.:
106 ///
107 /// @code{.cpp}
108 /// Error foo(<...>);
109 ///
110 /// if (auto E = foo(<...>))
111 /// return E; // <- Return E if it is in the error state.
112 /// // We have verified that E was in the success state. It can now be safely
113 /// // destroyed.
114 /// @endcode
115 ///
116 /// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
117 /// without testing the return value will raise a runtime error, even if foo
118 /// returns success.
119 ///
120 /// For Error instances representing failure, you must use either the
121 /// handleErrors or handleAllErrors function with a typed handler. E.g.:
122 ///
123 /// @code{.cpp}
124 /// class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
125 /// // Custom error info.
126 /// };
127 ///
128 /// Error foo(<...>) { return make_error<MyErrorInfo>(...); }
129 ///
130 /// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
131 /// auto NewE =
132 /// handleErrors(E,
133 /// [](const MyErrorInfo &M) {
134 /// // Deal with the error.
135 /// },
136 /// [](std::unique_ptr<OtherError> M) -> Error {
137 /// if (canHandle(*M)) {
138 /// // handle error.
139 /// return Error::success();
140 /// }
141 /// // Couldn't handle this error instance. Pass it up the stack.
142 /// return Error(std::move(M));
143 /// );
144 /// // Note - we must check or return NewE in case any of the handlers
145 /// // returned a new error.
146 /// @endcode
147 ///
148 /// The handleAllErrors function is identical to handleErrors, except
149 /// that it has a void return type, and requires all errors to be handled and
150 /// no new errors be returned. It prevents errors (assuming they can all be
151 /// handled) from having to be bubbled all the way to the top-level.
152 ///
153 /// *All* Error instances must be checked before destruction, even if
154 /// they're moved-assigned or constructed from Success values that have already
155 /// been checked. This enforces checking through all levels of the call stack.
157  // ErrorList needs to be able to yank ErrorInfoBase pointers out of this
158  // class to add to the error list.
159  friend class ErrorList;
160 
161  // handleErrors needs to be able to set the Checked flag.
162  template <typename... HandlerTs>
163  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
164 
165  // Expected<T> needs to be able to steal the payload when constructed from an
166  // error.
167  template <typename T> friend class Expected;
168 
169 protected:
170  /// Create a success value. Prefer using 'Error::success()' for readability
171  Error() {
172  setPtr(nullptr);
173  setChecked(false);
174  }
175 
176 public:
177  /// Create a success value.
178  static ErrorSuccess success();
179 
180  // Errors are not copy-constructable.
181  Error(const Error &Other) = delete;
182 
183  /// Move-construct an error value. The newly constructed error is considered
184  /// unchecked, even if the source error had been checked. The original error
185  /// becomes a checked Success value, regardless of its original state.
186  Error(Error &&Other) {
187  setChecked(true);
188  *this = std::move(Other);
189  }
190 
191  /// Create an error value. Prefer using the 'make_error' function, but
192  /// this constructor can be useful when "re-throwing" errors from handlers.
193  Error(std::unique_ptr<ErrorInfoBase> Payload) {
194  setPtr(Payload.release());
195  setChecked(false);
196  }
197 
198  // Errors are not copy-assignable.
199  Error &operator=(const Error &Other) = delete;
200 
201  /// Move-assign an error value. The current error must represent success, you
202  /// you cannot overwrite an unhandled error. The current error is then
203  /// considered unchecked. The source error becomes a checked success value,
204  /// regardless of its original state.
205  Error &operator=(Error &&Other) {
206  // Don't allow overwriting of unchecked values.
207  assertIsChecked();
208  setPtr(Other.getPtr());
209 
210  // This Error is unchecked, even if the source error was checked.
211  setChecked(false);
212 
213  // Null out Other's payload and set its checked bit.
214  Other.setPtr(nullptr);
215  Other.setChecked(true);
216 
217  return *this;
218  }
219 
220  /// Destroy a Error. Fails with a call to abort() if the error is
221  /// unchecked.
222  ~Error() {
223  assertIsChecked();
224  delete getPtr();
225  }
226 
227  /// Bool conversion. Returns true if this Error is in a failure state,
228  /// and false if it is in an accept state. If the error is in a Success state
229  /// it will be considered checked.
230  explicit operator bool() {
231  setChecked(getPtr() == nullptr);
232  return getPtr() != nullptr;
233  }
234 
235  /// Check whether one error is a subclass of another.
236  template <typename ErrT> bool isA() const {
237  return getPtr() && getPtr()->isA(ErrT::classID());
238  }
239 
240  /// Returns the dynamic class id of this error, or null if this is a success
241  /// value.
242  const void* dynamicClassID() const {
243  if (!getPtr())
244  return nullptr;
245  return getPtr()->dynamicClassID();
246  }
247 
248 private:
249 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
250  // assertIsChecked() happens very frequently, but under normal circumstances
251  // is supposed to be a no-op. So we want it to be inlined, but having a bunch
252  // of debug prints can cause the function to be too large for inlining. So
253  // it's important that we define this function out of line so that it can't be
254  // inlined.
256  void fatalUncheckedError() const;
257 #endif
258 
259  void assertIsChecked() {
260 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
261  if (LLVM_UNLIKELY(!getChecked() || getPtr()))
262  fatalUncheckedError();
263 #endif
264  }
265 
266  ErrorInfoBase *getPtr() const {
267  return reinterpret_cast<ErrorInfoBase*>(
268  reinterpret_cast<uintptr_t>(Payload) &
269  ~static_cast<uintptr_t>(0x1));
270  }
271 
272  void setPtr(ErrorInfoBase *EI) {
273 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
274  Payload = reinterpret_cast<ErrorInfoBase*>(
275  (reinterpret_cast<uintptr_t>(EI) &
276  ~static_cast<uintptr_t>(0x1)) |
277  (reinterpret_cast<uintptr_t>(Payload) & 0x1));
278 #else
279  Payload = EI;
280 #endif
281  }
282 
283  bool getChecked() const {
284 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
285  return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
286 #else
287  return true;
288 #endif
289  }
290 
291  void setChecked(bool V) {
292  Payload = reinterpret_cast<ErrorInfoBase*>(
293  (reinterpret_cast<uintptr_t>(Payload) &
294  ~static_cast<uintptr_t>(0x1)) |
295  (V ? 0 : 1));
296  }
297 
298  std::unique_ptr<ErrorInfoBase> takePayload() {
299  std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
300  setPtr(nullptr);
301  setChecked(true);
302  return Tmp;
303  }
304 
305  ErrorInfoBase *Payload = nullptr;
306 };
307 
308 /// Subclass of Error for the sole purpose of identifying the success path in
309 /// the type system. This allows to catch invalid conversion to Expected<T> at
310 /// compile time.
311 class ErrorSuccess : public Error {};
312 
314 
315 /// Make a Error instance representing failure using the given error info
316 /// type.
317 template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
318  return Error(llvm::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
319 }
320 
321 /// Base class for user error types. Users should declare their error types
322 /// like:
323 ///
324 /// class MyError : public ErrorInfo<MyError> {
325 /// ....
326 /// };
327 ///
328 /// This class provides an implementation of the ErrorInfoBase::kind
329 /// method, which is used by the Error RTTI system.
330 template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
331 class ErrorInfo : public ParentErrT {
332 public:
333  static const void *classID() { return &ThisErrT::ID; }
334 
335  const void *dynamicClassID() const override { return &ThisErrT::ID; }
336 
337  bool isA(const void *const ClassID) const override {
338  return ClassID == classID() || ParentErrT::isA(ClassID);
339  }
340 };
341 
342 /// Special ErrorInfo subclass representing a list of ErrorInfos.
343 /// Instances of this class are constructed by joinError.
344 class ErrorList final : public ErrorInfo<ErrorList> {
345  // handleErrors needs to be able to iterate the payload list of an
346  // ErrorList.
347  template <typename... HandlerTs>
348  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
349 
350  // joinErrors is implemented in terms of join.
351  friend Error joinErrors(Error, Error);
352 
353 public:
354  void log(raw_ostream &OS) const override {
355  OS << "Multiple errors:\n";
356  for (auto &ErrPayload : Payloads) {
357  ErrPayload->log(OS);
358  OS << "\n";
359  }
360  }
361 
362  std::error_code convertToErrorCode() const override;
363 
364  // Used by ErrorInfo::classID.
365  static char ID;
366 
367 private:
368  ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
369  std::unique_ptr<ErrorInfoBase> Payload2) {
370  assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&
371  "ErrorList constructor payloads should be singleton errors");
372  Payloads.push_back(std::move(Payload1));
373  Payloads.push_back(std::move(Payload2));
374  }
375 
376  static Error join(Error E1, Error E2) {
377  if (!E1)
378  return E2;
379  if (!E2)
380  return E1;
381  if (E1.isA<ErrorList>()) {
382  auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
383  if (E2.isA<ErrorList>()) {
384  auto E2Payload = E2.takePayload();
385  auto &E2List = static_cast<ErrorList &>(*E2Payload);
386  for (auto &Payload : E2List.Payloads)
387  E1List.Payloads.push_back(std::move(Payload));
388  } else
389  E1List.Payloads.push_back(E2.takePayload());
390 
391  return E1;
392  }
393  if (E2.isA<ErrorList>()) {
394  auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
395  E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
396  return E2;
397  }
398  return Error(std::unique_ptr<ErrorList>(
399  new ErrorList(E1.takePayload(), E2.takePayload())));
400  }
401 
402  std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
403 };
404 
405 /// Concatenate errors. The resulting Error is unchecked, and contains the
406 /// ErrorInfo(s), if any, contained in E1, followed by the
407 /// ErrorInfo(s), if any, contained in E2.
408 inline Error joinErrors(Error E1, Error E2) {
409  return ErrorList::join(std::move(E1), std::move(E2));
410 }
411 
412 /// Tagged union holding either a T or a Error.
413 ///
414 /// This class parallels ErrorOr, but replaces error_code with Error. Since
415 /// Error cannot be copied, this class replaces getError() with
416 /// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
417 /// error class type.
418 template <class T> class LLVM_NODISCARD Expected {
419  template <class T1> friend class ExpectedAsOutParameter;
420  template <class OtherT> friend class Expected;
421 
422  static const bool isRef = std::is_reference<T>::value;
423 
425 
426  using error_type = std::unique_ptr<ErrorInfoBase>;
427 
428 public:
429  using storage_type = typename std::conditional<isRef, wrap, T>::type;
430  using value_type = T;
431 
432 private:
433  using reference = typename std::remove_reference<T>::type &;
434  using const_reference = const typename std::remove_reference<T>::type &;
435  using pointer = typename std::remove_reference<T>::type *;
436  using const_pointer = const typename std::remove_reference<T>::type *;
437 
438 public:
439  /// Create an Expected<T> error value from the given Error.
441  : HasError(true)
442 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
443  // Expected is unchecked upon construction in Debug builds.
444  , Unchecked(true)
445 #endif
446  {
447  assert(Err && "Cannot create Expected<T> from Error success value.");
448  new (getErrorStorage()) error_type(Err.takePayload());
449  }
450 
451  /// Forbid to convert from Error::success() implicitly, this avoids having
452  /// Expected<T> foo() { return Error::success(); } which compiles otherwise
453  /// but triggers the assertion above.
454  Expected(ErrorSuccess) = delete;
455 
456  /// Create an Expected<T> success value from the given OtherT value, which
457  /// must be convertible to T.
458  template <typename OtherT>
459  Expected(OtherT &&Val,
460  typename std::enable_if<std::is_convertible<OtherT, T>::value>::type
461  * = nullptr)
462  : HasError(false)
463 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
464  // Expected is unchecked upon construction in Debug builds.
465  , Unchecked(true)
466 #endif
467  {
468  new (getStorage()) storage_type(std::forward<OtherT>(Val));
469  }
470 
471  /// Move construct an Expected<T> value.
472  Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
473 
474  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
475  /// must be convertible to T.
476  template <class OtherT>
478  typename std::enable_if<std::is_convertible<OtherT, T>::value>::type
479  * = nullptr) {
480  moveConstruct(std::move(Other));
481  }
482 
483  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
484  /// isn't convertible to T.
485  template <class OtherT>
486  explicit Expected(
488  typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * =
489  nullptr) {
490  moveConstruct(std::move(Other));
491  }
492 
493  /// Move-assign from another Expected<T>.
494  Expected &operator=(Expected &&Other) {
495  moveAssign(std::move(Other));
496  return *this;
497  }
498 
499  /// Destroy an Expected<T>.
501  assertIsChecked();
502  if (!HasError)
503  getStorage()->~storage_type();
504  else
505  getErrorStorage()->~error_type();
506  }
507 
508  /// \brief Return false if there is an error.
509  explicit operator bool() {
510 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
511  Unchecked = HasError;
512 #endif
513  return !HasError;
514  }
515 
516  /// \brief Returns a reference to the stored T value.
517  reference get() {
518  assertIsChecked();
519  return *getStorage();
520  }
521 
522  /// \brief Returns a const reference to the stored T value.
523  const_reference get() const {
524  assertIsChecked();
525  return const_cast<Expected<T> *>(this)->get();
526  }
527 
528  /// \brief Check that this Expected<T> is an error of type ErrT.
529  template <typename ErrT> bool errorIsA() const {
530  return HasError && (*getErrorStorage())->template isA<ErrT>();
531  }
532 
533  /// \brief Take ownership of the stored error.
534  /// After calling this the Expected<T> is in an indeterminate state that can
535  /// only be safely destructed. No further calls (beside the destructor) should
536  /// be made on the Expected<T> vaule.
538 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
539  Unchecked = false;
540 #endif
541  return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
542  }
543 
544  /// \brief Returns a pointer to the stored T value.
545  pointer operator->() {
546  assertIsChecked();
547  return toPointer(getStorage());
548  }
549 
550  /// \brief Returns a const pointer to the stored T value.
551  const_pointer operator->() const {
552  assertIsChecked();
553  return toPointer(getStorage());
554  }
555 
556  /// \brief Returns a reference to the stored T value.
557  reference operator*() {
558  assertIsChecked();
559  return *getStorage();
560  }
561 
562  /// \brief Returns a const reference to the stored T value.
563  const_reference operator*() const {
564  assertIsChecked();
565  return *getStorage();
566  }
567 
568 private:
569  template <class T1>
570  static bool compareThisIfSameType(const T1 &a, const T1 &b) {
571  return &a == &b;
572  }
573 
574  template <class T1, class T2>
575  static bool compareThisIfSameType(const T1 &a, const T2 &b) {
576  return false;
577  }
578 
579  template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
580  HasError = Other.HasError;
581 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
582  Unchecked = true;
583  Other.Unchecked = false;
584 #endif
585 
586  if (!HasError)
587  new (getStorage()) storage_type(std::move(*Other.getStorage()));
588  else
589  new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
590  }
591 
592  template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
593  assertIsChecked();
594 
595  if (compareThisIfSameType(*this, Other))
596  return;
597 
598  this->~Expected();
599  new (this) Expected(std::move(Other));
600  }
601 
602  pointer toPointer(pointer Val) { return Val; }
603 
604  const_pointer toPointer(const_pointer Val) const { return Val; }
605 
606  pointer toPointer(wrap *Val) { return &Val->get(); }
607 
608  const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
609 
610  storage_type *getStorage() {
611  assert(!HasError && "Cannot get value when an error exists!");
612  return reinterpret_cast<storage_type *>(TStorage.buffer);
613  }
614 
615  const storage_type *getStorage() const {
616  assert(!HasError && "Cannot get value when an error exists!");
617  return reinterpret_cast<const storage_type *>(TStorage.buffer);
618  }
619 
620  error_type *getErrorStorage() {
621  assert(HasError && "Cannot get error when a value exists!");
622  return reinterpret_cast<error_type *>(ErrorStorage.buffer);
623  }
624 
625  const error_type *getErrorStorage() const {
626  assert(HasError && "Cannot get error when a value exists!");
627  return reinterpret_cast<const error_type *>(ErrorStorage.buffer);
628  }
629 
630  // Used by ExpectedAsOutParameter to reset the checked flag.
631  void setUnchecked() {
632 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
633  Unchecked = true;
634 #endif
635  }
636 
637 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
640  void fatalUncheckedExpected() const {
641  dbgs() << "Expected<T> must be checked before access or destruction.\n";
642  if (HasError) {
643  dbgs() << "Unchecked Expected<T> contained error:\n";
644  (*getErrorStorage())->log(dbgs());
645  } else
646  dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
647  "values in success mode must still be checked prior to being "
648  "destroyed).\n";
649  abort();
650  }
651 #endif
652 
653  void assertIsChecked() {
654 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
655  if (LLVM_UNLIKELY(Unchecked))
656  fatalUncheckedExpected();
657 #endif
658  }
659 
660  union {
663  };
664  bool HasError : 1;
665 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
666  bool Unchecked : 1;
667 #endif
668 };
669 
670 /// Report a serious error, calling any installed error handler. See
671 /// ErrorHandling.h.
673  bool gen_crash_diag = true);
674 
675 /// Report a fatal error if Err is a failure value.
676 ///
677 /// This function can be used to wrap calls to fallible functions ONLY when it
678 /// is known that the Error will always be a success value. E.g.
679 ///
680 /// @code{.cpp}
681 /// // foo only attempts the fallible operation if DoFallibleOperation is
682 /// // true. If DoFallibleOperation is false then foo always returns
683 /// // Error::success().
684 /// Error foo(bool DoFallibleOperation);
685 ///
686 /// cantFail(foo(false));
687 /// @endcode
688 inline void cantFail(Error Err, const char *Msg = nullptr) {
689  if (Err) {
690  if (!Msg)
691  Msg = "Failure value returned from cantFail wrapped call";
692  llvm_unreachable(Msg);
693  }
694 }
695 
696 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
697 /// returns the contained value.
698 ///
699 /// This function can be used to wrap calls to fallible functions ONLY when it
700 /// is known that the Error will always be a success value. E.g.
701 ///
702 /// @code{.cpp}
703 /// // foo only attempts the fallible operation if DoFallibleOperation is
704 /// // true. If DoFallibleOperation is false then foo always returns an int.
705 /// Expected<int> foo(bool DoFallibleOperation);
706 ///
707 /// int X = cantFail(foo(false));
708 /// @endcode
709 template <typename T>
710 T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
711  if (ValOrErr)
712  return std::move(*ValOrErr);
713  else {
714  if (!Msg)
715  Msg = "Failure value returned from cantFail wrapped call";
716  llvm_unreachable(Msg);
717  }
718 }
719 
720 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
721 /// returns the contained reference.
722 ///
723 /// This function can be used to wrap calls to fallible functions ONLY when it
724 /// is known that the Error will always be a success value. E.g.
725 ///
726 /// @code{.cpp}
727 /// // foo only attempts the fallible operation if DoFallibleOperation is
728 /// // true. If DoFallibleOperation is false then foo always returns a Bar&.
729 /// Expected<Bar&> foo(bool DoFallibleOperation);
730 ///
731 /// Bar &X = cantFail(foo(false));
732 /// @endcode
733 template <typename T>
734 T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
735  if (ValOrErr)
736  return *ValOrErr;
737  else {
738  if (!Msg)
739  Msg = "Failure value returned from cantFail wrapped call";
740  llvm_unreachable(Msg);
741  }
742 }
743 
744 /// Helper for testing applicability of, and applying, handlers for
745 /// ErrorInfo types.
746 template <typename HandlerT>
748  : public ErrorHandlerTraits<decltype(
749  &std::remove_reference<HandlerT>::type::operator())> {};
750 
751 // Specialization functions of the form 'Error (const ErrT&)'.
752 template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
753 public:
754  static bool appliesTo(const ErrorInfoBase &E) {
755  return E.template isA<ErrT>();
756  }
757 
758  template <typename HandlerT>
759  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
760  assert(appliesTo(*E) && "Applying incorrect handler");
761  return H(static_cast<ErrT &>(*E));
762  }
763 };
764 
765 // Specialization functions of the form 'void (const ErrT&)'.
766 template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
767 public:
768  static bool appliesTo(const ErrorInfoBase &E) {
769  return E.template isA<ErrT>();
770  }
771 
772  template <typename HandlerT>
773  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
774  assert(appliesTo(*E) && "Applying incorrect handler");
775  H(static_cast<ErrT &>(*E));
776  return Error::success();
777  }
778 };
779 
780 /// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
781 template <typename ErrT>
782 class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
783 public:
784  static bool appliesTo(const ErrorInfoBase &E) {
785  return E.template isA<ErrT>();
786  }
787 
788  template <typename HandlerT>
789  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
790  assert(appliesTo(*E) && "Applying incorrect handler");
791  std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
792  return H(std::move(SubE));
793  }
794 };
795 
796 /// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
797 template <typename ErrT>
798 class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
799 public:
800  static bool appliesTo(const ErrorInfoBase &E) {
801  return E.template isA<ErrT>();
802  }
803 
804  template <typename HandlerT>
805  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
806  assert(appliesTo(*E) && "Applying incorrect handler");
807  std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
808  H(std::move(SubE));
809  return Error::success();
810  }
811 };
812 
813 // Specialization for member functions of the form 'RetT (const ErrT&)'.
814 template <typename C, typename RetT, typename ErrT>
815 class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
816  : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
817 
818 // Specialization for member functions of the form 'RetT (const ErrT&) const'.
819 template <typename C, typename RetT, typename ErrT>
820 class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
821  : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
822 
823 // Specialization for member functions of the form 'RetT (const ErrT&)'.
824 template <typename C, typename RetT, typename ErrT>
825 class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
826  : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
827 
828 // Specialization for member functions of the form 'RetT (const ErrT&) const'.
829 template <typename C, typename RetT, typename ErrT>
830 class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
831  : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
832 
833 /// Specialization for member functions of the form
834 /// 'RetT (std::unique_ptr<ErrT>)'.
835 template <typename C, typename RetT, typename ErrT>
836 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
837  : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
838 
839 /// Specialization for member functions of the form
840 /// 'RetT (std::unique_ptr<ErrT>) const'.
841 template <typename C, typename RetT, typename ErrT>
842 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
843  : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
844 
845 inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
846  return Error(std::move(Payload));
847 }
848 
849 template <typename HandlerT, typename... HandlerTs>
850 Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
851  HandlerT &&Handler, HandlerTs &&... Handlers) {
853  return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
854  std::move(Payload));
855  return handleErrorImpl(std::move(Payload),
856  std::forward<HandlerTs>(Handlers)...);
857 }
858 
859 /// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
860 /// unhandled errors (or Errors returned by handlers) are re-concatenated and
861 /// returned.
862 /// Because this function returns an error, its result must also be checked
863 /// or returned. If you intend to handle all errors use handleAllErrors
864 /// (which returns void, and will abort() on unhandled errors) instead.
865 template <typename... HandlerTs>
866 Error handleErrors(Error E, HandlerTs &&... Hs) {
867  if (!E)
868  return Error::success();
869 
870  std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
871 
872  if (Payload->isA<ErrorList>()) {
873  ErrorList &List = static_cast<ErrorList &>(*Payload);
874  Error R;
875  for (auto &P : List.Payloads)
876  R = ErrorList::join(
877  std::move(R),
878  handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
879  return R;
880  }
881 
882  return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
883 }
884 
885 /// Behaves the same as handleErrors, except that it requires that all
886 /// errors be handled by the given handlers. If any unhandled error remains
887 /// after the handlers have run, report_fatal_error() will be called.
888 template <typename... HandlerTs>
889 void handleAllErrors(Error E, HandlerTs &&... Handlers) {
890  cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
891 }
892 
893 /// Check that E is a non-error, then drop it.
894 /// If E is an error report_fatal_error will be called.
895 inline void handleAllErrors(Error E) {
896  cantFail(std::move(E));
897 }
898 
899 /// Handle any errors (if present) in an Expected<T>, then try a recovery path.
900 ///
901 /// If the incoming value is a success value it is returned unmodified. If it
902 /// is a failure value then it the contained error is passed to handleErrors.
903 /// If handleErrors is able to handle the error then the RecoveryPath functor
904 /// is called to supply the final result. If handleErrors is not able to
905 /// handle all errors then the unhandled errors are returned.
906 ///
907 /// This utility enables the follow pattern:
908 ///
909 /// @code{.cpp}
910 /// enum FooStrategy { Aggressive, Conservative };
911 /// Expected<Foo> foo(FooStrategy S);
912 ///
913 /// auto ResultOrErr =
914 /// handleExpected(
915 /// foo(Aggressive),
916 /// []() { return foo(Conservative); },
917 /// [](AggressiveStrategyError&) {
918 /// // Implicitly conusme this - we'll recover by using a conservative
919 /// // strategy.
920 /// });
921 ///
922 /// @endcode
923 template <typename T, typename RecoveryFtor, typename... HandlerTs>
924 Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
925  HandlerTs &&... Handlers) {
926  if (ValOrErr)
927  return ValOrErr;
928 
929  if (auto Err = handleErrors(ValOrErr.takeError(),
930  std::forward<HandlerTs>(Handlers)...))
931  return std::move(Err);
932 
933  return RecoveryPath();
934 }
935 
936 /// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
937 /// will be printed before the first one is logged. A newline will be printed
938 /// after each error.
939 ///
940 /// This is useful in the base level of your program to allow clean termination
941 /// (allowing clean deallocation of resources, etc.), while reporting error
942 /// information to the user.
943 void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner);
944 
945 /// Write all error messages (if any) in E to a string. The newline character
946 /// is used to separate error messages.
947 inline std::string toString(Error E) {
949  handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) {
950  Errors.push_back(EI.message());
951  });
952  return join(Errors.begin(), Errors.end(), "\n");
953 }
954 
955 /// Consume a Error without doing anything. This method should be used
956 /// only where an error can be considered a reasonable and expected return
957 /// value.
958 ///
959 /// Uses of this method are potentially indicative of design problems: If it's
960 /// legitimate to do nothing while processing an "error", the error-producer
961 /// might be more clearly refactored to return an Optional<T>.
962 inline void consumeError(Error Err) {
963  handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
964 }
965 
966 /// Helper for Errors used as out-parameters.
967 ///
968 /// This helper is for use with the Error-as-out-parameter idiom, where an error
969 /// is passed to a function or method by reference, rather than being returned.
970 /// In such cases it is helpful to set the checked bit on entry to the function
971 /// so that the error can be written to (unchecked Errors abort on assignment)
972 /// and clear the checked bit on exit so that clients cannot accidentally forget
973 /// to check the result. This helper performs these actions automatically using
974 /// RAII:
975 ///
976 /// @code{.cpp}
977 /// Result foo(Error &Err) {
978 /// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
979 /// // <body of foo>
980 /// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
981 /// }
982 /// @endcode
983 ///
984 /// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
985 /// used with optional Errors (Error pointers that are allowed to be null). If
986 /// ErrorAsOutParameter took an Error reference, an instance would have to be
987 /// created inside every condition that verified that Error was non-null. By
988 /// taking an Error pointer we can just create one instance at the top of the
989 /// function.
991 public:
992  ErrorAsOutParameter(Error *Err) : Err(Err) {
993  // Raise the checked bit if Err is success.
994  if (Err)
995  (void)!!*Err;
996  }
997 
999  // Clear the checked bit.
1000  if (Err && !*Err)
1001  *Err = Error::success();
1002  }
1003 
1004 private:
1005  Error *Err;
1006 };
1007 
1008 /// Helper for Expected<T>s used as out-parameters.
1009 ///
1010 /// See ErrorAsOutParameter.
1011 template <typename T>
1013 public:
1015  : ValOrErr(ValOrErr) {
1016  if (ValOrErr)
1017  (void)!!*ValOrErr;
1018  }
1019 
1021  if (ValOrErr)
1022  ValOrErr->setUnchecked();
1023  }
1024 
1025 private:
1026  Expected<T> *ValOrErr;
1027 };
1028 
1029 /// This class wraps a std::error_code in a Error.
1030 ///
1031 /// This is useful if you're writing an interface that returns a Error
1032 /// (or Expected) and you want to call code that still returns
1033 /// std::error_codes.
1034 class ECError : public ErrorInfo<ECError> {
1035  friend Error errorCodeToError(std::error_code);
1036 
1037 public:
1038  void setErrorCode(std::error_code EC) { this->EC = EC; }
1039  std::error_code convertToErrorCode() const override { return EC; }
1040  void log(raw_ostream &OS) const override { OS << EC.message(); }
1041 
1042  // Used by ErrorInfo::classID.
1043  static char ID;
1044 
1045 protected:
1046  ECError() = default;
1047  ECError(std::error_code EC) : EC(EC) {}
1048 
1049  std::error_code EC;
1050 };
1051 
1052 /// The value returned by this function can be returned from convertToErrorCode
1053 /// for Error values where no sensible translation to std::error_code exists.
1054 /// It should only be used in this situation, and should never be used where a
1055 /// sensible conversion to std::error_code is available, as attempts to convert
1056 /// to/from this error will result in a fatal error. (i.e. it is a programmatic
1057 ///error to try to convert such a value).
1058 std::error_code inconvertibleErrorCode();
1059 
1060 /// Helper for converting an std::error_code to a Error.
1061 Error errorCodeToError(std::error_code EC);
1062 
1063 /// Helper for converting an ECError to a std::error_code.
1064 ///
1065 /// This method requires that Err be Error() or an ECError, otherwise it
1066 /// will trigger a call to abort().
1067 std::error_code errorToErrorCode(Error Err);
1068 
1069 /// Convert an ErrorOr<T> to an Expected<T>.
1070 template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1071  if (auto EC = EO.getError())
1072  return errorCodeToError(EC);
1073  return std::move(*EO);
1074 }
1075 
1076 /// Convert an Expected<T> to an ErrorOr<T>.
1077 template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1078  if (auto Err = E.takeError())
1079  return errorToErrorCode(std::move(Err));
1080  return std::move(*E);
1081 }
1082 
1083 /// This class wraps a string in an Error.
1084 ///
1085 /// StringError is useful in cases where the client is not expected to be able
1086 /// to consume the specific error message programmatically (for example, if the
1087 /// error message is to be presented to the user).
1088 class StringError : public ErrorInfo<StringError> {
1089 public:
1090  static char ID;
1091 
1092  StringError(const Twine &S, std::error_code EC);
1093 
1094  void log(raw_ostream &OS) const override;
1095  std::error_code convertToErrorCode() const override;
1096 
1097  const std::string &getMessage() const { return Msg; }
1098 
1099 private:
1100  std::string Msg;
1101  std::error_code EC;
1102 };
1103 
1104 /// Helper for check-and-exit error handling.
1105 ///
1106 /// For tool use only. NOT FOR USE IN LIBRARY CODE.
1107 ///
1109 public:
1110  /// Create an error on exit helper.
1111  ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
1112  : Banner(std::move(Banner)),
1113  GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1114 
1115  /// Set the banner string for any errors caught by operator().
1116  void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1117 
1118  /// Set the exit-code mapper function.
1119  void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1120  this->GetExitCode = std::move(GetExitCode);
1121  }
1122 
1123  /// Check Err. If it's in a failure state log the error(s) and exit.
1124  void operator()(Error Err) const { checkError(std::move(Err)); }
1125 
1126  /// Check E. If it's in a success state then return the contained value. If
1127  /// it's in a failure state log the error(s) and exit.
1128  template <typename T> T operator()(Expected<T> &&E) const {
1129  checkError(E.takeError());
1130  return std::move(*E);
1131  }
1132 
1133  /// Check E. If it's in a success state then return the contained reference. If
1134  /// it's in a failure state log the error(s) and exit.
1135  template <typename T> T& operator()(Expected<T&> &&E) const {
1136  checkError(E.takeError());
1137  return *E;
1138  }
1139 
1140 private:
1141  void checkError(Error Err) const {
1142  if (Err) {
1143  int ExitCode = GetExitCode(Err);
1144  logAllUnhandledErrors(std::move(Err), errs(), Banner);
1145  exit(ExitCode);
1146  }
1147  }
1148 
1149  std::string Banner;
1150  std::function<int(const Error &)> GetExitCode;
1151 };
1152 
1153 } // end namespace llvm
1154 
1155 #endif // LLVM_SUPPORT_ERROR_H
reference operator*()
Returns a reference to the stored T value.
Definition: Error.h:557
static const void * classID()
Definition: Error.h:69
void cantFail(Error Err, const char *Msg=nullptr)
Report a fatal error if Err is a failure value.
Definition: Error.h:688
uint64_t CallInst * C
bool errorIsA() const
Check that this Expected<T> is an error of type ErrT.
Definition: Error.h:529
Represents either an error or a value T.
Definition: ErrorOr.h:69
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
Error make_error(ArgTs &&... Args)
Make a Error instance representing failure using the given error info type.
Definition: Error.h:317
const void * dynamicClassID() const
Returns the dynamic class id of this error, or null if this is a success value.
Definition: Error.h:242
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:115
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
#define LLVM_UNLIKELY(EXPR)
Definition: Compiler.h:176
void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner)
Log all errors (if any) in E to OS.
Definition: Error.cpp:57
Subclass of Error for the sole purpose of identifying the success path in the type system...
Definition: Error.h:311
AlignedCharArrayUnion< storage_type > TStorage
Definition: Error.h:661
bool isA() const
Definition: Error.h:81
Helper for check-and-exit error handling.
Definition: Error.h:1108
static const char * getPtr(const MachOObjectFile &O, size_t Offset)
T & operator()(Expected< T &> &&E) const
Check E.
Definition: Error.h:1135
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:800
Helper for Expected<T>s used as out-parameters.
Definition: Error.h:1012
virtual std::string message() const
Return the error message as a string.
Definition: Error.h:55
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.h:354
ErrorOr< T > expectedToErrorOr(Expected< T > &&E)
Convert an Expected<T> to an ErrorOr<T>.
Definition: Error.h:1077
pointer operator->()
Returns a pointer to the stored T value.
Definition: Error.h:545
Error takeError()
Take ownership of the stored error.
Definition: Error.h:537
Expected< T > handleExpected(Expected< T > ValOrErr, RecoveryFtor &&RecoveryPath, HandlerTs &&... Handlers)
Handle any errors (if present) in an Expected<T>, then try a recovery path.
Definition: Error.h:924
Base class for error info classes.
Definition: Error.h:47
std::error_code convertToErrorCode() const override
Convert this error to a std::error_code.
Definition: Error.h:1039
Expected(Expected< OtherT > &&Other, typename std::enable_if<!std::is_convertible< OtherT, T >::value >::type *=nullptr)
Move construct an Expected<T> value from an Expected<OtherT>, where OtherT isn&#39;t convertible to T...
Definition: Error.h:486
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:789
Definition: BitVector.h:920
std::string toString(Error E)
Write all error messages (if any) in E to a string.
Definition: Error.h:947
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
~Error()
Destroy a Error.
Definition: Error.h:222
Expected(Expected &&Other)
Move construct an Expected<T> value.
Definition: Error.h:472
Expected(Expected< OtherT > &&Other, typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *=nullptr)
Move construct an Expected<T> value from an Expected<OtherT>, where OtherT must be convertible to T...
Definition: Error.h:477
virtual void log(raw_ostream &OS) const =0
Print an error message to an output stream.
static char ID
Definition: Error.h:365
void apply(Opt *O, const Mod &M, const Mods &... Ms)
Definition: CommandLine.h:1169
std::string join(IteratorT Begin, IteratorT End, StringRef Separator)
Joins the strings in the range [Begin, End), adding Separator between the elements.
Definition: StringExtras.h:327
~Expected()
Destroy an Expected<T>.
Definition: Error.h:500
Tagged union holding either a T or a Error.
Definition: CachePruning.h:23
virtual ~ErrorInfoBase()=default
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:736
const_reference operator*() const
Returns a const reference to the stored T value.
Definition: Error.h:563
const void * dynamicClassID() const override
Definition: Error.h:335
#define T
Error & operator=(Error &&Other)
Move-assign an error value.
Definition: Error.h:205
ErrorAsOutParameter(Error *Err)
Definition: Error.h:992
virtual const void * dynamicClassID() const =0
ECError(std::error_code EC)
Definition: Error.h:1047
void setExitCodeMapper(std::function< int(const Error &)> GetExitCode)
Set the exit-code mapper function.
Definition: Error.h:1119
#define P(N)
const_pointer operator->() const
Returns a const pointer to the stored T value.
Definition: Error.h:551
Expected(Error Err)
Create an Expected<T> error value from the given Error.
Definition: Error.h:440
* if(!EatIfPresent(lltok::kw_thread_local)) return false
ParseOptionalThreadLocal := /*empty.
void operator()(Error Err) const
Check Err. If it&#39;s in a failure state log the error(s) and exit.
Definition: Error.h:1124
AlignedCharArrayUnion< error_type > ErrorStorage
Definition: Error.h:662
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
Error errorCodeToError(std::error_code EC)
Helper for converting an std::error_code to a Error.
Definition: Error.cpp:78
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:116
#define H(x, y, z)
Definition: MD5.cpp:57
ExitOnError(std::string Banner="", int DefaultErrorExitCode=1)
Create an error on exit helper.
Definition: Error.h:1111
Expected< T > errorOrToExpected(ErrorOr< T > &&EO)
Convert an ErrorOr<T> to an Expected<T>.
Definition: Error.h:1070
void consumeError(Error Err)
Consume a Error without doing anything.
Definition: Error.h:962
const std::string & getMessage() const
Definition: Error.h:1097
std::string & str()
Flushes the stream contents to the target string and returns the string&#39;s reference.
Definition: raw_ostream.h:478
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:759
Special ErrorInfo subclass representing a list of ErrorInfos.
Definition: Error.h:344
static const void * classID()
Definition: Error.h:333
Error(std::unique_ptr< ErrorInfoBase > Payload)
Create an error value.
Definition: Error.h:193
void handleAllErrors(Error E, HandlerTs &&... Handlers)
Behaves the same as handleErrors, except that it requires that all errors be handled by the given han...
Definition: Error.h:889
static ErrorSuccess success()
Create a success value.
Definition: Error.h:313
T & get() const
Definition: ErrorOr.h:36
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:768
Expected(OtherT &&Val, typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *=nullptr)
Create an Expected<T> success value from the given OtherT value, which must be convertible to T...
Definition: Error.h:459
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:784
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
#define LLVM_ATTRIBUTE_NOINLINE
LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, mark a method "not for inl...
Definition: Compiler.h:186
static char ID
Definition: Error.h:1043
#define LLVM_ATTRIBUTE_NORETURN
Definition: Compiler.h:206
virtual std::error_code convertToErrorCode() const =0
Convert this error to a std::error_code.
T operator()(Expected< T > &&E) const
Check E.
Definition: Error.h:1128
Expected & operator=(Expected &&Other)
Move-assign from another Expected<T>.
Definition: Error.h:494
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
void setBanner(std::string Banner)
Set the banner string for any errors caught by operator().
Definition: Error.h:1116
Base class for user error types.
Definition: Error.h:331
Helper for Errors used as out-parameters.
Definition: Error.h:990
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:805
Error handleErrorImpl(std::unique_ptr< ErrorInfoBase > Payload)
Definition: Error.h:845
Basic Alias true
Error(Error &&Other)
Move-construct an error value.
Definition: Error.h:186
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:120
This class wraps a string in an Error.
Definition: Error.h:1088
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.h:1040
Error joinErrors(Error E1, Error E2)
Concatenate errors.
Definition: Error.h:408
bool isA(const void *const ClassID) const override
Definition: Error.h:337
const NodeList & List
Definition: RDFGraph.cpp:210
bool isA() const
Check whether one error is a subclass of another.
Definition: Error.h:236
void setErrorCode(std::error_code EC)
Definition: Error.h:1038
typename std::conditional< isRef, wrap, T >::type storage_type
Definition: Error.h:429
Stores a reference that can be changed.
Definition: ErrorOr.h:29
ExpectedAsOutParameter(Expected< T > *ValOrErr)
Definition: Error.h:1014
#define LLVM_NODISCARD
LLVM_NODISCARD - Warn if a type or return value is discarded.
Definition: Compiler.h:126
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:773
Provides ErrorOr<T> smart pointer.
Error()
Create a success value. Prefer using &#39;Error::success()&#39; for readability.
Definition: Error.h:171
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:754
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
A raw_ostream that writes to an std::string.
Definition: raw_ostream.h:462
aarch64 promote const
Lightweight error class with error context and mandatory checking.
Definition: Error.h:156
Error handleErrors(Error E, HandlerTs &&... Hs)
Pass the ErrorInfo(s) contained in E to their respective handlers.
Definition: Error.h:866
std::error_code EC
Definition: Error.h:1049
This class wraps a std::error_code in a Error.
Definition: Error.h:1034
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:44
Helper for testing applicability of, and applying, handlers for ErrorInfo types.
Definition: Error.h:747
print Print MemDeps of function
static char ID
Definition: Error.h:1090
std::error_code errorToErrorCode(Error Err)
Helper for converting an ECError to a std::error_code.
Definition: Error.cpp:84
virtual bool isA(const void *const ClassID) const
Definition: Error.h:76
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
#define T1
std::error_code inconvertibleErrorCode()
The value returned by this function can be returned from convertToErrorCode for Error values where no...
Definition: Error.cpp:73