1 //===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines an API used to report recoverable errors.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_SUPPORT_ERROR_H
14 #define LLVM_SUPPORT_ERROR_H
15
16 #include "llvm-c/Error.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/Config/abi-breaking.h"
22 #include "llvm/Support/AlignOf.h"
23 #include "llvm/Support/Compiler.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/ErrorOr.h"
27 #include "llvm/Support/Format.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cstdint>
32 #include <cstdlib>
33 #include <functional>
34 #include <memory>
35 #include <new>
36 #include <string>
37 #include <system_error>
38 #include <type_traits>
39 #include <utility>
40 #include <vector>
41
42 namespace llvm {
43
44 class ErrorSuccess;
45
46 /// Base class for error info classes. Do not extend this directly: Extend
47 /// the ErrorInfo template subclass instead.
48 class ErrorInfoBase {
49 public:
50 virtual ~ErrorInfoBase() = default;
51
52 /// Print an error message to an output stream.
53 virtual void log(raw_ostream &OS) const = 0;
54
55 /// Return the error message as a string.
message()56 virtual std::string message() const {
57 std::string Msg;
58 raw_string_ostream OS(Msg);
59 log(OS);
60 return OS.str();
61 }
62
63 /// Convert this error to a std::error_code.
64 ///
65 /// This is a temporary crutch to enable interaction with code still
66 /// using std::error_code. It will be removed in the future.
67 virtual std::error_code convertToErrorCode() const = 0;
68
69 // Returns the class ID for this type.
classID()70 static const void *classID() { return &ID; }
71
72 // Returns the class ID for the dynamic type of this ErrorInfoBase instance.
73 virtual const void *dynamicClassID() const = 0;
74
75 // Check whether this instance is a subclass of the class identified by
76 // ClassID.
isA(const void * const ClassID)77 virtual bool isA(const void *const ClassID) const {
78 return ClassID == classID();
79 }
80
81 // Check whether this instance is a subclass of ErrorInfoT.
isA()82 template <typename ErrorInfoT> bool isA() const {
83 return isA(ErrorInfoT::classID());
84 }
85
86 private:
87 virtual void anchor();
88
89 static char ID;
90 };
91
92 /// Lightweight error class with error context and mandatory checking.
93 ///
94 /// Instances of this class wrap a ErrorInfoBase pointer. Failure states
95 /// are represented by setting the pointer to a ErrorInfoBase subclass
96 /// instance containing information describing the failure. Success is
97 /// represented by a null pointer value.
98 ///
99 /// Instances of Error also contains a 'Checked' flag, which must be set
100 /// before the destructor is called, otherwise the destructor will trigger a
101 /// runtime error. This enforces at runtime the requirement that all Error
102 /// instances be checked or returned to the caller.
103 ///
104 /// There are two ways to set the checked flag, depending on what state the
105 /// Error instance is in. For Error instances indicating success, it
106 /// is sufficient to invoke the boolean conversion operator. E.g.:
107 ///
108 /// @code{.cpp}
109 /// Error foo(<...>);
110 ///
111 /// if (auto E = foo(<...>))
112 /// return E; // <- Return E if it is in the error state.
113 /// // We have verified that E was in the success state. It can now be safely
114 /// // destroyed.
115 /// @endcode
116 ///
117 /// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
118 /// without testing the return value will raise a runtime error, even if foo
119 /// returns success.
120 ///
121 /// For Error instances representing failure, you must use either the
122 /// handleErrors or handleAllErrors function with a typed handler. E.g.:
123 ///
124 /// @code{.cpp}
125 /// class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
126 /// // Custom error info.
127 /// };
128 ///
129 /// Error foo(<...>) { return make_error<MyErrorInfo>(...); }
130 ///
131 /// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
132 /// auto NewE =
133 /// handleErrors(E,
134 /// [](const MyErrorInfo &M) {
135 /// // Deal with the error.
136 /// },
137 /// [](std::unique_ptr<OtherError> M) -> Error {
138 /// if (canHandle(*M)) {
139 /// // handle error.
140 /// return Error::success();
141 /// }
142 /// // Couldn't handle this error instance. Pass it up the stack.
143 /// return Error(std::move(M));
144 /// );
145 /// // Note - we must check or return NewE in case any of the handlers
146 /// // returned a new error.
147 /// @endcode
148 ///
149 /// The handleAllErrors function is identical to handleErrors, except
150 /// that it has a void return type, and requires all errors to be handled and
151 /// no new errors be returned. It prevents errors (assuming they can all be
152 /// handled) from having to be bubbled all the way to the top-level.
153 ///
154 /// *All* Error instances must be checked before destruction, even if
155 /// they're moved-assigned or constructed from Success values that have already
156 /// been checked. This enforces checking through all levels of the call stack.
157 class LLVM_NODISCARD Error {
158 // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors
159 // to add to the error list. It can't rely on handleErrors for this, since
160 // handleErrors does not support ErrorList handlers.
161 friend class ErrorList;
162
163 // handleErrors needs to be able to set the Checked flag.
164 template <typename... HandlerTs>
165 friend Error handleErrors(Error E, HandlerTs &&... Handlers);
166
167 // Expected<T> needs to be able to steal the payload when constructed from an
168 // error.
169 template <typename T> friend class Expected;
170
171 // wrap needs to be able to steal the payload.
172 friend LLVMErrorRef wrap(Error);
173
174 protected:
175 /// Create a success value. Prefer using 'Error::success()' for readability
Error()176 Error() {
177 setPtr(nullptr);
178 setChecked(false);
179 }
180
181 public:
182 /// Create a success value.
183 static ErrorSuccess success();
184
185 // Errors are not copy-constructable.
186 Error(const Error &Other) = delete;
187
188 /// Move-construct an error value. The newly constructed error is considered
189 /// unchecked, even if the source error had been checked. The original error
190 /// becomes a checked Success value, regardless of its original state.
Error(Error && Other)191 Error(Error &&Other) {
192 setChecked(true);
193 *this = std::move(Other);
194 }
195
196 /// Create an error value. Prefer using the 'make_error' function, but
197 /// this constructor can be useful when "re-throwing" errors from handlers.
Error(std::unique_ptr<ErrorInfoBase> Payload)198 Error(std::unique_ptr<ErrorInfoBase> Payload) {
199 setPtr(Payload.release());
200 setChecked(false);
201 }
202
203 // Errors are not copy-assignable.
204 Error &operator=(const Error &Other) = delete;
205
206 /// Move-assign an error value. The current error must represent success, you
207 /// you cannot overwrite an unhandled error. The current error is then
208 /// considered unchecked. The source error becomes a checked success value,
209 /// regardless of its original state.
210 Error &operator=(Error &&Other) {
211 // Don't allow overwriting of unchecked values.
212 assertIsChecked();
213 setPtr(Other.getPtr());
214
215 // This Error is unchecked, even if the source error was checked.
216 setChecked(false);
217
218 // Null out Other's payload and set its checked bit.
219 Other.setPtr(nullptr);
220 Other.setChecked(true);
221
222 return *this;
223 }
224
225 /// Destroy a Error. Fails with a call to abort() if the error is
226 /// unchecked.
~Error()227 ~Error() {
228 assertIsChecked();
229 delete getPtr();
230 }
231
232 /// Bool conversion. Returns true if this Error is in a failure state,
233 /// and false if it is in an accept state. If the error is in a Success state
234 /// it will be considered checked.
235 explicit operator bool() {
236 setChecked(getPtr() == nullptr);
237 return getPtr() != nullptr;
238 }
239
240 /// Check whether one error is a subclass of another.
isA()241 template <typename ErrT> bool isA() const {
242 return getPtr() && getPtr()->isA(ErrT::classID());
243 }
244
245 /// Returns the dynamic class id of this error, or null if this is a success
246 /// value.
dynamicClassID()247 const void* dynamicClassID() const {
248 if (!getPtr())
249 return nullptr;
250 return getPtr()->dynamicClassID();
251 }
252
253 private:
254 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
255 // assertIsChecked() happens very frequently, but under normal circumstances
256 // is supposed to be a no-op. So we want it to be inlined, but having a bunch
257 // of debug prints can cause the function to be too large for inlining. So
258 // it's important that we define this function out of line so that it can't be
259 // inlined.
260 LLVM_ATTRIBUTE_NORETURN
261 void fatalUncheckedError() const;
262 #endif
263
assertIsChecked()264 void assertIsChecked() {
265 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
266 if (LLVM_UNLIKELY(!getChecked() || getPtr()))
267 fatalUncheckedError();
268 #endif
269 }
270
getPtr()271 ErrorInfoBase *getPtr() const {
272 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
273 return reinterpret_cast<ErrorInfoBase*>(
274 reinterpret_cast<uintptr_t>(Payload) &
275 ~static_cast<uintptr_t>(0x1));
276 #else
277 return Payload;
278 #endif
279 }
280
setPtr(ErrorInfoBase * EI)281 void setPtr(ErrorInfoBase *EI) {
282 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
283 Payload = reinterpret_cast<ErrorInfoBase*>(
284 (reinterpret_cast<uintptr_t>(EI) &
285 ~static_cast<uintptr_t>(0x1)) |
286 (reinterpret_cast<uintptr_t>(Payload) & 0x1));
287 #else
288 Payload = EI;
289 #endif
290 }
291
getChecked()292 bool getChecked() const {
293 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
294 return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
295 #else
296 return true;
297 #endif
298 }
299
setChecked(bool V)300 void setChecked(bool V) {
301 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
302 Payload = reinterpret_cast<ErrorInfoBase*>(
303 (reinterpret_cast<uintptr_t>(Payload) &
304 ~static_cast<uintptr_t>(0x1)) |
305 (V ? 0 : 1));
306 #endif
307 }
308
takePayload()309 std::unique_ptr<ErrorInfoBase> takePayload() {
310 std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
311 setPtr(nullptr);
312 setChecked(true);
313 return Tmp;
314 }
315
316 friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) {
317 if (auto P = E.getPtr())
318 P->log(OS);
319 else
320 OS << "success";
321 return OS;
322 }
323
324 ErrorInfoBase *Payload = nullptr;
325 };
326
327 /// Subclass of Error for the sole purpose of identifying the success path in
328 /// the type system. This allows to catch invalid conversion to Expected<T> at
329 /// compile time.
330 class ErrorSuccess final : public Error {};
331
success()332 inline ErrorSuccess Error::success() { return ErrorSuccess(); }
333
334 /// Make a Error instance representing failure using the given error info
335 /// type.
make_error(ArgTs &&...Args)336 template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
337 return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
338 }
339
340 /// Base class for user error types. Users should declare their error types
341 /// like:
342 ///
343 /// class MyError : public ErrorInfo<MyError> {
344 /// ....
345 /// };
346 ///
347 /// This class provides an implementation of the ErrorInfoBase::kind
348 /// method, which is used by the Error RTTI system.
349 template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
350 class ErrorInfo : public ParentErrT {
351 public:
352 using ParentErrT::ParentErrT; // inherit constructors
353
classID()354 static const void *classID() { return &ThisErrT::ID; }
355
dynamicClassID()356 const void *dynamicClassID() const override { return &ThisErrT::ID; }
357
isA(const void * const ClassID)358 bool isA(const void *const ClassID) const override {
359 return ClassID == classID() || ParentErrT::isA(ClassID);
360 }
361 };
362
363 /// Special ErrorInfo subclass representing a list of ErrorInfos.
364 /// Instances of this class are constructed by joinError.
365 class ErrorList final : public ErrorInfo<ErrorList> {
366 // handleErrors needs to be able to iterate the payload list of an
367 // ErrorList.
368 template <typename... HandlerTs>
369 friend Error handleErrors(Error E, HandlerTs &&... Handlers);
370
371 // joinErrors is implemented in terms of join.
372 friend Error joinErrors(Error, Error);
373
374 public:
log(raw_ostream & OS)375 void log(raw_ostream &OS) const override {
376 OS << "Multiple errors:\n";
377 for (auto &ErrPayload : Payloads) {
378 ErrPayload->log(OS);
379 OS << "\n";
380 }
381 }
382
383 std::error_code convertToErrorCode() const override;
384
385 // Used by ErrorInfo::classID.
386 static char ID;
387
388 private:
ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,std::unique_ptr<ErrorInfoBase> Payload2)389 ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
390 std::unique_ptr<ErrorInfoBase> Payload2) {
391 assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&
392 "ErrorList constructor payloads should be singleton errors");
393 Payloads.push_back(std::move(Payload1));
394 Payloads.push_back(std::move(Payload2));
395 }
396
join(Error E1,Error E2)397 static Error join(Error E1, Error E2) {
398 if (!E1)
399 return E2;
400 if (!E2)
401 return E1;
402 if (E1.isA<ErrorList>()) {
403 auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
404 if (E2.isA<ErrorList>()) {
405 auto E2Payload = E2.takePayload();
406 auto &E2List = static_cast<ErrorList &>(*E2Payload);
407 for (auto &Payload : E2List.Payloads)
408 E1List.Payloads.push_back(std::move(Payload));
409 } else
410 E1List.Payloads.push_back(E2.takePayload());
411
412 return E1;
413 }
414 if (E2.isA<ErrorList>()) {
415 auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
416 E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
417 return E2;
418 }
419 return Error(std::unique_ptr<ErrorList>(
420 new ErrorList(E1.takePayload(), E2.takePayload())));
421 }
422
423 std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
424 };
425
426 /// Concatenate errors. The resulting Error is unchecked, and contains the
427 /// ErrorInfo(s), if any, contained in E1, followed by the
428 /// ErrorInfo(s), if any, contained in E2.
joinErrors(Error E1,Error E2)429 inline Error joinErrors(Error E1, Error E2) {
430 return ErrorList::join(std::move(E1), std::move(E2));
431 }
432
433 /// Tagged union holding either a T or a Error.
434 ///
435 /// This class parallels ErrorOr, but replaces error_code with Error. Since
436 /// Error cannot be copied, this class replaces getError() with
437 /// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
438 /// error class type.
439 template <class T> class LLVM_NODISCARD Expected {
440 template <class T1> friend class ExpectedAsOutParameter;
441 template <class OtherT> friend class Expected;
442
443 static constexpr bool isRef = std::is_reference<T>::value;
444
445 using wrap = std::reference_wrapper<std::remove_reference_t<T>>;
446
447 using error_type = std::unique_ptr<ErrorInfoBase>;
448
449 public:
450 using storage_type = std::conditional_t<isRef, wrap, T>;
451 using value_type = T;
452
453 private:
454 using reference = std::remove_reference_t<T> &;
455 using const_reference = const std::remove_reference_t<T> &;
456 using pointer = std::remove_reference_t<T> *;
457 using const_pointer = const std::remove_reference_t<T> *;
458
459 public:
460 /// Create an Expected<T> error value from the given Error.
Expected(Error Err)461 Expected(Error Err)
462 : HasError(true)
463 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
464 // Expected is unchecked upon construction in Debug builds.
465 , Unchecked(true)
466 #endif
467 {
468 assert(Err && "Cannot create Expected<T> from Error success value.");
469 new (getErrorStorage()) error_type(Err.takePayload());
470 }
471
472 /// Forbid to convert from Error::success() implicitly, this avoids having
473 /// Expected<T> foo() { return Error::success(); } which compiles otherwise
474 /// but triggers the assertion above.
475 Expected(ErrorSuccess) = delete;
476
477 /// Create an Expected<T> success value from the given OtherT value, which
478 /// must be convertible to T.
479 template <typename OtherT>
480 Expected(OtherT &&Val,
481 std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr)
HasError(false)482 : HasError(false)
483 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
484 // Expected is unchecked upon construction in Debug builds.
485 ,
486 Unchecked(true)
487 #endif
488 {
489 new (getStorage()) storage_type(std::forward<OtherT>(Val));
490 }
491
492 /// Move construct an Expected<T> value.
Expected(Expected && Other)493 Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
494
495 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
496 /// must be convertible to T.
497 template <class OtherT>
498 Expected(
499 Expected<OtherT> &&Other,
500 std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) {
501 moveConstruct(std::move(Other));
502 }
503
504 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
505 /// isn't convertible to T.
506 template <class OtherT>
507 explicit Expected(
508 Expected<OtherT> &&Other,
509 std::enable_if_t<!std::is_convertible<OtherT, T>::value> * = nullptr) {
510 moveConstruct(std::move(Other));
511 }
512
513 /// Move-assign from another Expected<T>.
514 Expected &operator=(Expected &&Other) {
515 moveAssign(std::move(Other));
516 return *this;
517 }
518
519 /// Destroy an Expected<T>.
~Expected()520 ~Expected() {
521 assertIsChecked();
522 if (!HasError)
523 getStorage()->~storage_type();
524 else
525 getErrorStorage()->~error_type();
526 }
527
528 /// Return false if there is an error.
529 explicit operator bool() {
530 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
531 Unchecked = HasError;
532 #endif
533 return !HasError;
534 }
535
536 /// Returns a reference to the stored T value.
get()537 reference get() {
538 assertIsChecked();
539 return *getStorage();
540 }
541
542 /// Returns a const reference to the stored T value.
get()543 const_reference get() const {
544 assertIsChecked();
545 return const_cast<Expected<T> *>(this)->get();
546 }
547
548 /// Check that this Expected<T> is an error of type ErrT.
errorIsA()549 template <typename ErrT> bool errorIsA() const {
550 return HasError && (*getErrorStorage())->template isA<ErrT>();
551 }
552
553 /// Take ownership of the stored error.
554 /// After calling this the Expected<T> is in an indeterminate state that can
555 /// only be safely destructed. No further calls (beside the destructor) should
556 /// be made on the Expected<T> value.
takeError()557 Error takeError() {
558 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
559 Unchecked = false;
560 #endif
561 return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
562 }
563
564 /// Returns a pointer to the stored T value.
565 pointer operator->() {
566 assertIsChecked();
567 return toPointer(getStorage());
568 }
569
570 /// Returns a const pointer to the stored T value.
571 const_pointer operator->() const {
572 assertIsChecked();
573 return toPointer(getStorage());
574 }
575
576 /// Returns a reference to the stored T value.
577 reference operator*() {
578 assertIsChecked();
579 return *getStorage();
580 }
581
582 /// Returns a const reference to the stored T value.
583 const_reference operator*() const {
584 assertIsChecked();
585 return *getStorage();
586 }
587
588 private:
589 template <class T1>
compareThisIfSameType(const T1 & a,const T1 & b)590 static bool compareThisIfSameType(const T1 &a, const T1 &b) {
591 return &a == &b;
592 }
593
594 template <class T1, class T2>
compareThisIfSameType(const T1 &,const T2 &)595 static bool compareThisIfSameType(const T1 &, const T2 &) {
596 return false;
597 }
598
moveConstruct(Expected<OtherT> && Other)599 template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
600 HasError = Other.HasError;
601 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
602 Unchecked = true;
603 Other.Unchecked = false;
604 #endif
605
606 if (!HasError)
607 new (getStorage()) storage_type(std::move(*Other.getStorage()));
608 else
609 new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
610 }
611
moveAssign(Expected<OtherT> && Other)612 template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
613 assertIsChecked();
614
615 if (compareThisIfSameType(*this, Other))
616 return;
617
618 this->~Expected();
619 new (this) Expected(std::move(Other));
620 }
621
toPointer(pointer Val)622 pointer toPointer(pointer Val) { return Val; }
623
toPointer(const_pointer Val)624 const_pointer toPointer(const_pointer Val) const { return Val; }
625
toPointer(wrap * Val)626 pointer toPointer(wrap *Val) { return &Val->get(); }
627
toPointer(const wrap * Val)628 const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
629
getStorage()630 storage_type *getStorage() {
631 assert(!HasError && "Cannot get value when an error exists!");
632 return reinterpret_cast<storage_type *>(&TStorage);
633 }
634
getStorage()635 const storage_type *getStorage() const {
636 assert(!HasError && "Cannot get value when an error exists!");
637 return reinterpret_cast<const storage_type *>(&TStorage);
638 }
639
getErrorStorage()640 error_type *getErrorStorage() {
641 assert(HasError && "Cannot get error when a value exists!");
642 return reinterpret_cast<error_type *>(&ErrorStorage);
643 }
644
getErrorStorage()645 const error_type *getErrorStorage() const {
646 assert(HasError && "Cannot get error when a value exists!");
647 return reinterpret_cast<const error_type *>(&ErrorStorage);
648 }
649
650 // Used by ExpectedAsOutParameter to reset the checked flag.
setUnchecked()651 void setUnchecked() {
652 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
653 Unchecked = true;
654 #endif
655 }
656
657 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
658 LLVM_ATTRIBUTE_NORETURN
659 LLVM_ATTRIBUTE_NOINLINE
fatalUncheckedExpected()660 void fatalUncheckedExpected() const {
661 dbgs() << "Expected<T> must be checked before access or destruction.\n";
662 if (HasError) {
663 dbgs() << "Unchecked Expected<T> contained error:\n";
664 (*getErrorStorage())->log(dbgs());
665 } else
666 dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
667 "values in success mode must still be checked prior to being "
668 "destroyed).\n";
669 abort();
670 }
671 #endif
672
assertIsChecked()673 void assertIsChecked() {
674 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
675 if (LLVM_UNLIKELY(Unchecked))
676 fatalUncheckedExpected();
677 #endif
678 }
679
680 union {
681 AlignedCharArrayUnion<storage_type> TStorage;
682 AlignedCharArrayUnion<error_type> ErrorStorage;
683 };
684 bool HasError : 1;
685 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
686 bool Unchecked : 1;
687 #endif
688 };
689
690 /// Report a serious error, calling any installed error handler. See
691 /// ErrorHandling.h.
692 LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err,
693 bool gen_crash_diag = true);
694
695 /// Report a fatal error if Err is a failure value.
696 ///
697 /// This function can be used to wrap calls to fallible functions ONLY when it
698 /// is known that the Error will always be a success value. E.g.
699 ///
700 /// @code{.cpp}
701 /// // foo only attempts the fallible operation if DoFallibleOperation is
702 /// // true. If DoFallibleOperation is false then foo always returns
703 /// // Error::success().
704 /// Error foo(bool DoFallibleOperation);
705 ///
706 /// cantFail(foo(false));
707 /// @endcode
708 inline void cantFail(Error Err, const char *Msg = nullptr) {
709 if (Err) {
710 if (!Msg)
711 Msg = "Failure value returned from cantFail wrapped call";
712 #ifndef NDEBUG
713 std::string Str;
714 raw_string_ostream OS(Str);
715 OS << Msg << "\n" << Err;
716 Msg = OS.str().c_str();
717 #endif
718 llvm_unreachable(Msg);
719 }
720 }
721
722 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
723 /// returns the contained value.
724 ///
725 /// This function can be used to wrap calls to fallible functions ONLY when it
726 /// is known that the Error will always be a success value. E.g.
727 ///
728 /// @code{.cpp}
729 /// // foo only attempts the fallible operation if DoFallibleOperation is
730 /// // true. If DoFallibleOperation is false then foo always returns an int.
731 /// Expected<int> foo(bool DoFallibleOperation);
732 ///
733 /// int X = cantFail(foo(false));
734 /// @endcode
735 template <typename T>
736 T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
737 if (ValOrErr)
738 return std::move(*ValOrErr);
739 else {
740 if (!Msg)
741 Msg = "Failure value returned from cantFail wrapped call";
742 #ifndef NDEBUG
743 std::string Str;
744 raw_string_ostream OS(Str);
745 auto E = ValOrErr.takeError();
746 OS << Msg << "\n" << E;
747 Msg = OS.str().c_str();
748 #endif
749 llvm_unreachable(Msg);
750 }
751 }
752
753 /// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
754 /// returns the contained reference.
755 ///
756 /// This function can be used to wrap calls to fallible functions ONLY when it
757 /// is known that the Error will always be a success value. E.g.
758 ///
759 /// @code{.cpp}
760 /// // foo only attempts the fallible operation if DoFallibleOperation is
761 /// // true. If DoFallibleOperation is false then foo always returns a Bar&.
762 /// Expected<Bar&> foo(bool DoFallibleOperation);
763 ///
764 /// Bar &X = cantFail(foo(false));
765 /// @endcode
766 template <typename T>
767 T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
768 if (ValOrErr)
769 return *ValOrErr;
770 else {
771 if (!Msg)
772 Msg = "Failure value returned from cantFail wrapped call";
773 #ifndef NDEBUG
774 std::string Str;
775 raw_string_ostream OS(Str);
776 auto E = ValOrErr.takeError();
777 OS << Msg << "\n" << E;
778 Msg = OS.str().c_str();
779 #endif
780 llvm_unreachable(Msg);
781 }
782 }
783
784 /// Helper for testing applicability of, and applying, handlers for
785 /// ErrorInfo types.
786 template <typename HandlerT>
787 class ErrorHandlerTraits
788 : public ErrorHandlerTraits<decltype(
789 &std::remove_reference<HandlerT>::type::operator())> {};
790
791 // Specialization functions of the form 'Error (const ErrT&)'.
792 template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
793 public:
appliesTo(const ErrorInfoBase & E)794 static bool appliesTo(const ErrorInfoBase &E) {
795 return E.template isA<ErrT>();
796 }
797
798 template <typename HandlerT>
apply(HandlerT && H,std::unique_ptr<ErrorInfoBase> E)799 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
800 assert(appliesTo(*E) && "Applying incorrect handler");
801 return H(static_cast<ErrT &>(*E));
802 }
803 };
804
805 // Specialization functions of the form 'void (const ErrT&)'.
806 template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
807 public:
appliesTo(const ErrorInfoBase & E)808 static bool appliesTo(const ErrorInfoBase &E) {
809 return E.template isA<ErrT>();
810 }
811
812 template <typename HandlerT>
apply(HandlerT && H,std::unique_ptr<ErrorInfoBase> E)813 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
814 assert(appliesTo(*E) && "Applying incorrect handler");
815 H(static_cast<ErrT &>(*E));
816 return Error::success();
817 }
818 };
819
820 /// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
821 template <typename ErrT>
822 class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
823 public:
appliesTo(const ErrorInfoBase & E)824 static bool appliesTo(const ErrorInfoBase &E) {
825 return E.template isA<ErrT>();
826 }
827
828 template <typename HandlerT>
apply(HandlerT && H,std::unique_ptr<ErrorInfoBase> E)829 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
830 assert(appliesTo(*E) && "Applying incorrect handler");
831 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
832 return H(std::move(SubE));
833 }
834 };
835
836 /// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
837 template <typename ErrT>
838 class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
839 public:
appliesTo(const ErrorInfoBase & E)840 static bool appliesTo(const ErrorInfoBase &E) {
841 return E.template isA<ErrT>();
842 }
843
844 template <typename HandlerT>
apply(HandlerT && H,std::unique_ptr<ErrorInfoBase> E)845 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
846 assert(appliesTo(*E) && "Applying incorrect handler");
847 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
848 H(std::move(SubE));
849 return Error::success();
850 }
851 };
852
853 // Specialization for member functions of the form 'RetT (const ErrT&)'.
854 template <typename C, typename RetT, typename ErrT>
855 class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
856 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
857
858 // Specialization for member functions of the form 'RetT (const ErrT&) const'.
859 template <typename C, typename RetT, typename ErrT>
860 class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
861 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
862
863 // Specialization for member functions of the form 'RetT (const ErrT&)'.
864 template <typename C, typename RetT, typename ErrT>
865 class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
866 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
867
868 // Specialization for member functions of the form 'RetT (const ErrT&) const'.
869 template <typename C, typename RetT, typename ErrT>
870 class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
871 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
872
873 /// Specialization for member functions of the form
874 /// 'RetT (std::unique_ptr<ErrT>)'.
875 template <typename C, typename RetT, typename ErrT>
876 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
877 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
878
879 /// Specialization for member functions of the form
880 /// 'RetT (std::unique_ptr<ErrT>) const'.
881 template <typename C, typename RetT, typename ErrT>
882 class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
883 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
884
handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload)885 inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
886 return Error(std::move(Payload));
887 }
888
889 template <typename HandlerT, typename... HandlerTs>
handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,HandlerT && Handler,HandlerTs &&...Handlers)890 Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
891 HandlerT &&Handler, HandlerTs &&... Handlers) {
892 if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload))
893 return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
894 std::move(Payload));
895 return handleErrorImpl(std::move(Payload),
896 std::forward<HandlerTs>(Handlers)...);
897 }
898
899 /// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
900 /// unhandled errors (or Errors returned by handlers) are re-concatenated and
901 /// returned.
902 /// Because this function returns an error, its result must also be checked
903 /// or returned. If you intend to handle all errors use handleAllErrors
904 /// (which returns void, and will abort() on unhandled errors) instead.
905 template <typename... HandlerTs>
handleErrors(Error E,HandlerTs &&...Hs)906 Error handleErrors(Error E, HandlerTs &&... Hs) {
907 if (!E)
908 return Error::success();
909
910 std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
911
912 if (Payload->isA<ErrorList>()) {
913 ErrorList &List = static_cast<ErrorList &>(*Payload);
914 Error R;
915 for (auto &P : List.Payloads)
916 R = ErrorList::join(
917 std::move(R),
918 handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
919 return R;
920 }
921
922 return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
923 }
924
925 /// Behaves the same as handleErrors, except that by contract all errors
926 /// *must* be handled by the given handlers (i.e. there must be no remaining
927 /// errors after running the handlers, or llvm_unreachable is called).
928 template <typename... HandlerTs>
handleAllErrors(Error E,HandlerTs &&...Handlers)929 void handleAllErrors(Error E, HandlerTs &&... Handlers) {
930 cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
931 }
932
933 /// Check that E is a non-error, then drop it.
934 /// If E is an error, llvm_unreachable will be called.
handleAllErrors(Error E)935 inline void handleAllErrors(Error E) {
936 cantFail(std::move(E));
937 }
938
939 /// Handle any errors (if present) in an Expected<T>, then try a recovery path.
940 ///
941 /// If the incoming value is a success value it is returned unmodified. If it
942 /// is a failure value then it the contained error is passed to handleErrors.
943 /// If handleErrors is able to handle the error then the RecoveryPath functor
944 /// is called to supply the final result. If handleErrors is not able to
945 /// handle all errors then the unhandled errors are returned.
946 ///
947 /// This utility enables the follow pattern:
948 ///
949 /// @code{.cpp}
950 /// enum FooStrategy { Aggressive, Conservative };
951 /// Expected<Foo> foo(FooStrategy S);
952 ///
953 /// auto ResultOrErr =
954 /// handleExpected(
955 /// foo(Aggressive),
956 /// []() { return foo(Conservative); },
957 /// [](AggressiveStrategyError&) {
958 /// // Implicitly conusme this - we'll recover by using a conservative
959 /// // strategy.
960 /// });
961 ///
962 /// @endcode
963 template <typename T, typename RecoveryFtor, typename... HandlerTs>
handleExpected(Expected<T> ValOrErr,RecoveryFtor && RecoveryPath,HandlerTs &&...Handlers)964 Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
965 HandlerTs &&... Handlers) {
966 if (ValOrErr)
967 return ValOrErr;
968
969 if (auto Err = handleErrors(ValOrErr.takeError(),
970 std::forward<HandlerTs>(Handlers)...))
971 return std::move(Err);
972
973 return RecoveryPath();
974 }
975
976 /// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
977 /// will be printed before the first one is logged. A newline will be printed
978 /// after each error.
979 ///
980 /// This function is compatible with the helpers from Support/WithColor.h. You
981 /// can pass any of them as the OS. Please consider using them instead of
982 /// including 'error: ' in the ErrorBanner.
983 ///
984 /// This is useful in the base level of your program to allow clean termination
985 /// (allowing clean deallocation of resources, etc.), while reporting error
986 /// information to the user.
987 void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {});
988
989 /// Write all error messages (if any) in E to a string. The newline character
990 /// is used to separate error messages.
toString(Error E)991 inline std::string toString(Error E) {
992 SmallVector<std::string, 2> Errors;
993 handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) {
994 Errors.push_back(EI.message());
995 });
996 return join(Errors.begin(), Errors.end(), "\n");
997 }
998
999 /// Consume a Error without doing anything. This method should be used
1000 /// only where an error can be considered a reasonable and expected return
1001 /// value.
1002 ///
1003 /// Uses of this method are potentially indicative of design problems: If it's
1004 /// legitimate to do nothing while processing an "error", the error-producer
1005 /// might be more clearly refactored to return an Optional<T>.
consumeError(Error Err)1006 inline void consumeError(Error Err) {
1007 handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
1008 }
1009
1010 /// Convert an Expected to an Optional without doing anything. This method
1011 /// should be used only where an error can be considered a reasonable and
1012 /// expected return value.
1013 ///
1014 /// Uses of this method are potentially indicative of problems: perhaps the
1015 /// error should be propagated further, or the error-producer should just
1016 /// return an Optional in the first place.
expectedToOptional(Expected<T> && E)1017 template <typename T> Optional<T> expectedToOptional(Expected<T> &&E) {
1018 if (E)
1019 return std::move(*E);
1020 consumeError(E.takeError());
1021 return None;
1022 }
1023
1024 /// Helper for converting an Error to a bool.
1025 ///
1026 /// This method returns true if Err is in an error state, or false if it is
1027 /// in a success state. Puts Err in a checked state in both cases (unlike
1028 /// Error::operator bool(), which only does this for success states).
errorToBool(Error Err)1029 inline bool errorToBool(Error Err) {
1030 bool IsError = static_cast<bool>(Err);
1031 if (IsError)
1032 consumeError(std::move(Err));
1033 return IsError;
1034 }
1035
1036 /// Helper for Errors used as out-parameters.
1037 ///
1038 /// This helper is for use with the Error-as-out-parameter idiom, where an error
1039 /// is passed to a function or method by reference, rather than being returned.
1040 /// In such cases it is helpful to set the checked bit on entry to the function
1041 /// so that the error can be written to (unchecked Errors abort on assignment)
1042 /// and clear the checked bit on exit so that clients cannot accidentally forget
1043 /// to check the result. This helper performs these actions automatically using
1044 /// RAII:
1045 ///
1046 /// @code{.cpp}
1047 /// Result foo(Error &Err) {
1048 /// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
1049 /// // <body of foo>
1050 /// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
1051 /// }
1052 /// @endcode
1053 ///
1054 /// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
1055 /// used with optional Errors (Error pointers that are allowed to be null). If
1056 /// ErrorAsOutParameter took an Error reference, an instance would have to be
1057 /// created inside every condition that verified that Error was non-null. By
1058 /// taking an Error pointer we can just create one instance at the top of the
1059 /// function.
1060 class ErrorAsOutParameter {
1061 public:
ErrorAsOutParameter(Error * Err)1062 ErrorAsOutParameter(Error *Err) : Err(Err) {
1063 // Raise the checked bit if Err is success.
1064 if (Err)
1065 (void)!!*Err;
1066 }
1067
~ErrorAsOutParameter()1068 ~ErrorAsOutParameter() {
1069 // Clear the checked bit.
1070 if (Err && !*Err)
1071 *Err = Error::success();
1072 }
1073
1074 private:
1075 Error *Err;
1076 };
1077
1078 /// Helper for Expected<T>s used as out-parameters.
1079 ///
1080 /// See ErrorAsOutParameter.
1081 template <typename T>
1082 class ExpectedAsOutParameter {
1083 public:
ExpectedAsOutParameter(Expected<T> * ValOrErr)1084 ExpectedAsOutParameter(Expected<T> *ValOrErr)
1085 : ValOrErr(ValOrErr) {
1086 if (ValOrErr)
1087 (void)!!*ValOrErr;
1088 }
1089
~ExpectedAsOutParameter()1090 ~ExpectedAsOutParameter() {
1091 if (ValOrErr)
1092 ValOrErr->setUnchecked();
1093 }
1094
1095 private:
1096 Expected<T> *ValOrErr;
1097 };
1098
1099 /// This class wraps a std::error_code in a Error.
1100 ///
1101 /// This is useful if you're writing an interface that returns a Error
1102 /// (or Expected) and you want to call code that still returns
1103 /// std::error_codes.
1104 class ECError : public ErrorInfo<ECError> {
1105 friend Error errorCodeToError(std::error_code);
1106
1107 virtual void anchor() override;
1108
1109 public:
setErrorCode(std::error_code EC)1110 void setErrorCode(std::error_code EC) { this->EC = EC; }
convertToErrorCode()1111 std::error_code convertToErrorCode() const override { return EC; }
log(raw_ostream & OS)1112 void log(raw_ostream &OS) const override { OS << EC.message(); }
1113
1114 // Used by ErrorInfo::classID.
1115 static char ID;
1116
1117 protected:
1118 ECError() = default;
ECError(std::error_code EC)1119 ECError(std::error_code EC) : EC(EC) {}
1120
1121 std::error_code EC;
1122 };
1123
1124 /// The value returned by this function can be returned from convertToErrorCode
1125 /// for Error values where no sensible translation to std::error_code exists.
1126 /// It should only be used in this situation, and should never be used where a
1127 /// sensible conversion to std::error_code is available, as attempts to convert
1128 /// to/from this error will result in a fatal error. (i.e. it is a programmatic
1129 ///error to try to convert such a value).
1130 std::error_code inconvertibleErrorCode();
1131
1132 /// Helper for converting an std::error_code to a Error.
1133 Error errorCodeToError(std::error_code EC);
1134
1135 /// Helper for converting an ECError to a std::error_code.
1136 ///
1137 /// This method requires that Err be Error() or an ECError, otherwise it
1138 /// will trigger a call to abort().
1139 std::error_code errorToErrorCode(Error Err);
1140
1141 /// Convert an ErrorOr<T> to an Expected<T>.
errorOrToExpected(ErrorOr<T> && EO)1142 template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1143 if (auto EC = EO.getError())
1144 return errorCodeToError(EC);
1145 return std::move(*EO);
1146 }
1147
1148 /// Convert an Expected<T> to an ErrorOr<T>.
expectedToErrorOr(Expected<T> && E)1149 template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1150 if (auto Err = E.takeError())
1151 return errorToErrorCode(std::move(Err));
1152 return std::move(*E);
1153 }
1154
1155 /// This class wraps a string in an Error.
1156 ///
1157 /// StringError is useful in cases where the client is not expected to be able
1158 /// to consume the specific error message programmatically (for example, if the
1159 /// error message is to be presented to the user).
1160 ///
1161 /// StringError can also be used when additional information is to be printed
1162 /// along with a error_code message. Depending on the constructor called, this
1163 /// class can either display:
1164 /// 1. the error_code message (ECError behavior)
1165 /// 2. a string
1166 /// 3. the error_code message and a string
1167 ///
1168 /// These behaviors are useful when subtyping is required; for example, when a
1169 /// specific library needs an explicit error type. In the example below,
1170 /// PDBError is derived from StringError:
1171 ///
1172 /// @code{.cpp}
1173 /// Expected<int> foo() {
1174 /// return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading,
1175 /// "Additional information");
1176 /// }
1177 /// @endcode
1178 ///
1179 class StringError : public ErrorInfo<StringError> {
1180 public:
1181 static char ID;
1182
1183 // Prints EC + S and converts to EC
1184 StringError(std::error_code EC, const Twine &S = Twine());
1185
1186 // Prints S and converts to EC
1187 StringError(const Twine &S, std::error_code EC);
1188
1189 void log(raw_ostream &OS) const override;
1190 std::error_code convertToErrorCode() const override;
1191
getMessage()1192 const std::string &getMessage() const { return Msg; }
1193
1194 private:
1195 std::string Msg;
1196 std::error_code EC;
1197 const bool PrintMsgOnly = false;
1198 };
1199
1200 /// Create formatted StringError object.
1201 template <typename... Ts>
createStringError(std::error_code EC,char const * Fmt,const Ts &...Vals)1202 inline Error createStringError(std::error_code EC, char const *Fmt,
1203 const Ts &... Vals) {
1204 std::string Buffer;
1205 raw_string_ostream Stream(Buffer);
1206 Stream << format(Fmt, Vals...);
1207 return make_error<StringError>(Stream.str(), EC);
1208 }
1209
1210 Error createStringError(std::error_code EC, char const *Msg);
1211
createStringError(std::error_code EC,const Twine & S)1212 inline Error createStringError(std::error_code EC, const Twine &S) {
1213 return createStringError(EC, S.str().c_str());
1214 }
1215
1216 template <typename... Ts>
createStringError(std::errc EC,char const * Fmt,const Ts &...Vals)1217 inline Error createStringError(std::errc EC, char const *Fmt,
1218 const Ts &... Vals) {
1219 return createStringError(std::make_error_code(EC), Fmt, Vals...);
1220 }
1221
1222 /// This class wraps a filename and another Error.
1223 ///
1224 /// In some cases, an error needs to live along a 'source' name, in order to
1225 /// show more detailed information to the user.
1226 class FileError final : public ErrorInfo<FileError> {
1227
1228 friend Error createFileError(const Twine &, Error);
1229 friend Error createFileError(const Twine &, size_t, Error);
1230
1231 public:
log(raw_ostream & OS)1232 void log(raw_ostream &OS) const override {
1233 assert(Err && !FileName.empty() && "Trying to log after takeError().");
1234 OS << "'" << FileName << "': ";
1235 if (Line.hasValue())
1236 OS << "line " << Line.getValue() << ": ";
1237 Err->log(OS);
1238 }
1239
getFileName()1240 StringRef getFileName() { return FileName; }
1241
takeError()1242 Error takeError() { return Error(std::move(Err)); }
1243
1244 std::error_code convertToErrorCode() const override;
1245
1246 // Used by ErrorInfo::classID.
1247 static char ID;
1248
1249 private:
FileError(const Twine & F,Optional<size_t> LineNum,std::unique_ptr<ErrorInfoBase> E)1250 FileError(const Twine &F, Optional<size_t> LineNum,
1251 std::unique_ptr<ErrorInfoBase> E) {
1252 assert(E && "Cannot create FileError from Error success value.");
1253 assert(!F.isTriviallyEmpty() &&
1254 "The file name provided to FileError must not be empty.");
1255 FileName = F.str();
1256 Err = std::move(E);
1257 Line = std::move(LineNum);
1258 }
1259
build(const Twine & F,Optional<size_t> Line,Error E)1260 static Error build(const Twine &F, Optional<size_t> Line, Error E) {
1261 std::unique_ptr<ErrorInfoBase> Payload;
1262 handleAllErrors(std::move(E),
1263 [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error {
1264 Payload = std::move(EIB);
1265 return Error::success();
1266 });
1267 return Error(
1268 std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload))));
1269 }
1270
1271 std::string FileName;
1272 Optional<size_t> Line;
1273 std::unique_ptr<ErrorInfoBase> Err;
1274 };
1275
1276 /// Concatenate a source file path and/or name with an Error. The resulting
1277 /// Error is unchecked.
createFileError(const Twine & F,Error E)1278 inline Error createFileError(const Twine &F, Error E) {
1279 return FileError::build(F, Optional<size_t>(), std::move(E));
1280 }
1281
1282 /// Concatenate a source file path and/or name with line number and an Error.
1283 /// The resulting Error is unchecked.
createFileError(const Twine & F,size_t Line,Error E)1284 inline Error createFileError(const Twine &F, size_t Line, Error E) {
1285 return FileError::build(F, Optional<size_t>(Line), std::move(E));
1286 }
1287
1288 /// Concatenate a source file path and/or name with a std::error_code
1289 /// to form an Error object.
createFileError(const Twine & F,std::error_code EC)1290 inline Error createFileError(const Twine &F, std::error_code EC) {
1291 return createFileError(F, errorCodeToError(EC));
1292 }
1293
1294 /// Concatenate a source file path and/or name with line number and
1295 /// std::error_code to form an Error object.
createFileError(const Twine & F,size_t Line,std::error_code EC)1296 inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) {
1297 return createFileError(F, Line, errorCodeToError(EC));
1298 }
1299
1300 Error createFileError(const Twine &F, ErrorSuccess) = delete;
1301
1302 /// Helper for check-and-exit error handling.
1303 ///
1304 /// For tool use only. NOT FOR USE IN LIBRARY CODE.
1305 ///
1306 class ExitOnError {
1307 public:
1308 /// Create an error on exit helper.
1309 ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
Banner(std::move (Banner))1310 : Banner(std::move(Banner)),
1311 GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1312
1313 /// Set the banner string for any errors caught by operator().
setBanner(std::string Banner)1314 void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1315
1316 /// Set the exit-code mapper function.
setExitCodeMapper(std::function<int (const Error &)> GetExitCode)1317 void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1318 this->GetExitCode = std::move(GetExitCode);
1319 }
1320
1321 /// Check Err. If it's in a failure state log the error(s) and exit.
operator()1322 void operator()(Error Err) const { checkError(std::move(Err)); }
1323
1324 /// Check E. If it's in a success state then return the contained value. If
1325 /// it's in a failure state log the error(s) and exit.
operator()1326 template <typename T> T operator()(Expected<T> &&E) const {
1327 checkError(E.takeError());
1328 return std::move(*E);
1329 }
1330
1331 /// Check E. If it's in a success state then return the contained reference. If
1332 /// it's in a failure state log the error(s) and exit.
operator()1333 template <typename T> T& operator()(Expected<T&> &&E) const {
1334 checkError(E.takeError());
1335 return *E;
1336 }
1337
1338 private:
checkError(Error Err)1339 void checkError(Error Err) const {
1340 if (Err) {
1341 int ExitCode = GetExitCode(Err);
1342 logAllUnhandledErrors(std::move(Err), errs(), Banner);
1343 exit(ExitCode);
1344 }
1345 }
1346
1347 std::string Banner;
1348 std::function<int(const Error &)> GetExitCode;
1349 };
1350
1351 /// Conversion from Error to LLVMErrorRef for C error bindings.
wrap(Error Err)1352 inline LLVMErrorRef wrap(Error Err) {
1353 return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
1354 }
1355
1356 /// Conversion from LLVMErrorRef to Error for C error bindings.
unwrap(LLVMErrorRef ErrRef)1357 inline Error unwrap(LLVMErrorRef ErrRef) {
1358 return Error(std::unique_ptr<ErrorInfoBase>(
1359 reinterpret_cast<ErrorInfoBase *>(ErrRef)));
1360 }
1361
1362 } // end namespace llvm
1363
1364 #endif // LLVM_SUPPORT_ERROR_H
1365