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/Twine.h"
18#include "llvm/Config/abi-breaking.h"
19#include "llvm/Support/AlignOf.h"
20#include "llvm/Support/Compiler.h"
21#include "llvm/Support/Debug.h"
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Support/ErrorOr.h"
24#include "llvm/Support/Format.h"
25#include "llvm/Support/raw_ostream.h"
26#include <cassert>
27#include <cstdint>
28#include <cstdlib>
29#include <functional>
30#include <memory>
31#include <new>
32#include <optional>
33#include <string>
34#include <system_error>
35#include <type_traits>
36#include <utility>
37#include <vector>
38
39namespace llvm {
40
41class ErrorSuccess;
42
43/// Base class for error info classes. Do not extend this directly: Extend
44/// the ErrorInfo template subclass instead.
45class ErrorInfoBase {
46public:
47 virtual ~ErrorInfoBase() = default;
48
49 /// Print an error message to an output stream.
50 virtual void log(raw_ostream &OS) const = 0;
51
52 /// Return the error message as a string.
53 virtual std::string message() const {
54 std::string Msg;
55 raw_string_ostream OS(Msg);
56 log(OS);
57 return OS.str();
58 }
59
60 /// Convert this error to a std::error_code.
61 ///
62 /// This is a temporary crutch to enable interaction with code still
63 /// using std::error_code. It will be removed in the future.
64 virtual std::error_code convertToErrorCode() const = 0;
65
66 // Returns the class ID for this type.
67 static const void *classID() { return &ID; }
68
69 // Returns the class ID for the dynamic type of this ErrorInfoBase instance.
70 virtual const void *dynamicClassID() const = 0;
71
72 // Check whether this instance is a subclass of the class identified by
73 // ClassID.
74 virtual bool isA(const void *const ClassID) const {
75 return ClassID == classID();
76 }
77
78 // Check whether this instance is a subclass of ErrorInfoT.
79 template <typename ErrorInfoT> bool isA() const {
80 return isA(ErrorInfoT::classID());
81 }
82
83private:
84 virtual void anchor();
85
86 static char ID;
87};
88
89/// Lightweight error class with error context and mandatory checking.
90///
91/// Instances of this class wrap a ErrorInfoBase pointer. Failure states
92/// are represented by setting the pointer to a ErrorInfoBase subclass
93/// instance containing information describing the failure. Success is
94/// represented by a null pointer value.
95///
96/// Instances of Error also contains a 'Checked' flag, which must be set
97/// before the destructor is called, otherwise the destructor will trigger a
98/// runtime error. This enforces at runtime the requirement that all Error
99/// instances be checked or returned to the caller.
100///
101/// There are two ways to set the checked flag, depending on what state the
102/// Error instance is in. For Error instances indicating success, it
103/// is sufficient to invoke the boolean conversion operator. E.g.:
104///
105/// @code{.cpp}
106/// Error foo(<...>);
107///
108/// if (auto E = foo(<...>))
109/// return E; // <- Return E if it is in the error state.
110/// // We have verified that E was in the success state. It can now be safely
111/// // destroyed.
112/// @endcode
113///
114/// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
115/// without testing the return value will raise a runtime error, even if foo
116/// returns success.
117///
118/// For Error instances representing failure, you must use either the
119/// handleErrors or handleAllErrors function with a typed handler. E.g.:
120///
121/// @code{.cpp}
122/// class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
123/// // Custom error info.
124/// };
125///
126/// Error foo(<...>) { return make_error<MyErrorInfo>(...); }
127///
128/// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
129/// auto NewE =
130/// handleErrors(std::move(E),
131/// [](const MyErrorInfo &M) {
132/// // Deal with the error.
133/// },
134/// [](std::unique_ptr<OtherError> M) -> Error {
135/// if (canHandle(*M)) {
136/// // handle error.
137/// return Error::success();
138/// }
139/// // Couldn't handle this error instance. Pass it up the stack.
140/// return Error(std::move(M));
141/// });
142/// // Note - The error passed to handleErrors will be marked as checked. If
143/// // there is no matched handler, a new error with the same payload is
144/// // created and returned.
145/// // The handlers take the error checked by handleErrors as an argument,
146/// // which can be used to retrieve more information. If a new error is
147/// // created by a handler, it will be passed back to the caller of
148/// // handleErrors and needs to be checked or return up to the stack.
149/// // Otherwise, the passed-in error is considered consumed.
150/// @endcode
151///
152/// The handleAllErrors function is identical to handleErrors, except
153/// that it has a void return type, and requires all errors to be handled and
154/// no new errors be returned. It prevents errors (assuming they can all be
155/// handled) from having to be bubbled all the way to the top-level.
156///
157/// *All* Error instances must be checked before destruction, even if
158/// they're moved-assigned or constructed from Success values that have already
159/// been checked. This enforces checking through all levels of the call stack.
160class [[nodiscard]] Error {
161 // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors
162 // to add to the error list. It can't rely on handleErrors for this, since
163 // handleErrors does not support ErrorList handlers.
164 friend class ErrorList;
165
166 // handleErrors needs to be able to set the Checked flag.
167 template <typename... HandlerTs>
168 friend Error handleErrors(Error E, HandlerTs &&... Handlers);
169
170 // Expected<T> needs to be able to steal the payload when constructed from an
171 // error.
172 template <typename T> friend class Expected;
173
174 // wrap needs to be able to steal the payload.
175 friend LLVMErrorRef wrap(Error);
176
177protected:
178 /// Create a success value. Prefer using 'Error::success()' for readability
179 Error() {
180 setPtr(nullptr);
181 setChecked(false);
182 }
183
184public:
185 /// Create a success value.
186 static ErrorSuccess success();
187
188 // Errors are not copy-constructable.
189 Error(const Error &Other) = delete;
190
191 /// Move-construct an error value. The newly constructed error is considered
192 /// unchecked, even if the source error had been checked. The original error
193 /// becomes a checked Success value, regardless of its original state.
194 Error(Error &&Other) {
195 setChecked(true);
196 *this = std::move(Other);
197 }
198
199 /// Create an error value. Prefer using the 'make_error' function, but
200 /// this constructor can be useful when "re-throwing" errors from handlers.
201 Error(std::unique_ptr<ErrorInfoBase> Payload) {
202 setPtr(Payload.release());
203 setChecked(false);
204 }
205
206 // Errors are not copy-assignable.
207 Error &operator=(const Error &Other) = delete;
208
209 /// Move-assign an error value. The current error must represent success, you
210 /// you cannot overwrite an unhandled error. The current error is then
211 /// considered unchecked. The source error becomes a checked success value,
212 /// regardless of its original state.
213 Error &operator=(Error &&Other) {
214 // Don't allow overwriting of unchecked values.
215 assertIsChecked();
216 setPtr(Other.getPtr());
217
218 // This Error is unchecked, even if the source error was checked.
219 setChecked(false);
220
221 // Null out Other's payload and set its checked bit.
222 Other.setPtr(nullptr);
223 Other.setChecked(true);
224
225 return *this;
226 }
227
228 /// Destroy a Error. Fails with a call to abort() if the error is
229 /// unchecked.
230 ~Error() {
231 assertIsChecked();
232 delete getPtr();
233 }
234
235 /// Bool conversion. Returns true if this Error is in a failure state,
236 /// and false if it is in an accept state. If the error is in a Success state
237 /// it will be considered checked.
238 explicit operator bool() {
239 setChecked(getPtr() == nullptr);
240 return getPtr() != nullptr;
241 }
242
243 /// Check whether one error is a subclass of another.
244 template <typename ErrT> bool isA() const {
245 return getPtr() && getPtr()->isA(ErrT::classID());
246 }
247
248 /// Returns the dynamic class id of this error, or null if this is a success
249 /// value.
250 const void* dynamicClassID() const {
251 if (!getPtr())
252 return nullptr;
253 return getPtr()->dynamicClassID();
254 }
255
256private:
257#if LLVM_ENABLE_ABI_BREAKING_CHECKS
258 // assertIsChecked() happens very frequently, but under normal circumstances
259 // is supposed to be a no-op. So we want it to be inlined, but having a bunch
260 // of debug prints can cause the function to be too large for inlining. So
261 // it's important that we define this function out of line so that it can't be
262 // inlined.
263 [[noreturn]] void fatalUncheckedError() const;
264#endif
265
266 void assertIsChecked() {
267#if LLVM_ENABLE_ABI_BREAKING_CHECKS
268 if (LLVM_UNLIKELY(!getChecked() || getPtr()))
269 fatalUncheckedError();
270#endif
271 }
272
273 ErrorInfoBase *getPtr() const {
274#if LLVM_ENABLE_ABI_BREAKING_CHECKS
275 return reinterpret_cast<ErrorInfoBase*>(
276 reinterpret_cast<uintptr_t>(Payload) &
277 ~static_cast<uintptr_t>(0x1));
278#else
279 return Payload;
280#endif
281 }
282
283 void setPtr(ErrorInfoBase *EI) {
284#if LLVM_ENABLE_ABI_BREAKING_CHECKS
285 Payload = reinterpret_cast<ErrorInfoBase*>(
286 (reinterpret_cast<uintptr_t>(EI) &
287 ~static_cast<uintptr_t>(0x1)) |
288 (reinterpret_cast<uintptr_t>(Payload) & 0x1));
289#else
290 Payload = EI;
291#endif
292 }
293
294 bool getChecked() const {
295#if LLVM_ENABLE_ABI_BREAKING_CHECKS
296 return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
297#else
298 return true;
299#endif
300 }
301
302 void setChecked(bool V) {
303#if LLVM_ENABLE_ABI_BREAKING_CHECKS
304 Payload = reinterpret_cast<ErrorInfoBase*>(
305 (reinterpret_cast<uintptr_t>(Payload) &
306 ~static_cast<uintptr_t>(0x1)) |
307 (V ? 0 : 1));
308#endif
309 }
310
311 std::unique_ptr<ErrorInfoBase> takePayload() {
312 std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
313 setPtr(nullptr);
314 setChecked(true);
315 return Tmp;
316 }
317
318 friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) {
319 if (auto *P = E.getPtr())
320 P->log(OS);
321 else
322 OS << "success";
323 return OS;
324 }
325
326 ErrorInfoBase *Payload = nullptr;
327};
328
329/// Subclass of Error for the sole purpose of identifying the success path in
330/// the type system. This allows to catch invalid conversion to Expected<T> at
331/// compile time.
332class ErrorSuccess final : public Error {};
333
334inline ErrorSuccess Error::success() { return ErrorSuccess(); }
335
336/// Make a Error instance representing failure using the given error info
337/// type.
338template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
339 return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
340}
341
342/// Base class for user error types. Users should declare their error types
343/// like:
344///
345/// class MyError : public ErrorInfo<MyError> {
346/// ....
347/// };
348///
349/// This class provides an implementation of the ErrorInfoBase::kind
350/// method, which is used by the Error RTTI system.
351template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
352class ErrorInfo : public ParentErrT {
353public:
354 using ParentErrT::ParentErrT; // inherit constructors
355
356 static const void *classID() { return &ThisErrT::ID; }
357
358 const void *dynamicClassID() const override { return &ThisErrT::ID; }
359
360 bool isA(const void *const ClassID) const override {
361 return ClassID == classID() || ParentErrT::isA(ClassID);
362 }
363};
364
365/// Special ErrorInfo subclass representing a list of ErrorInfos.
366/// Instances of this class are constructed by joinError.
367class ErrorList final : public ErrorInfo<ErrorList> {
368 // handleErrors needs to be able to iterate the payload list of an
369 // ErrorList.
370 template <typename... HandlerTs>
371 friend Error handleErrors(Error E, HandlerTs &&... Handlers);
372
373 // joinErrors is implemented in terms of join.
374 friend Error joinErrors(Error, Error);
375
376public:
377 void log(raw_ostream &OS) const override {
378 OS << "Multiple errors:\n";
379 for (const auto &ErrPayload : Payloads) {
380 ErrPayload->log(OS);
381 OS << "\n";
382 }
383 }
384
385 std::error_code convertToErrorCode() const override;
386
387 // Used by ErrorInfo::classID.
388 static char ID;
389
390private:
391 ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
392 std::unique_ptr<ErrorInfoBase> Payload2) {
393 assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&
394 "ErrorList constructor payloads should be singleton errors");
395 Payloads.push_back(x: std::move(Payload1));
396 Payloads.push_back(x: std::move(Payload2));
397 }
398
399 static Error join(Error E1, Error E2) {
400 if (!E1)
401 return E2;
402 if (!E2)
403 return E1;
404 if (E1.isA<ErrorList>()) {
405 auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
406 if (E2.isA<ErrorList>()) {
407 auto E2Payload = E2.takePayload();
408 auto &E2List = static_cast<ErrorList &>(*E2Payload);
409 for (auto &Payload : E2List.Payloads)
410 E1List.Payloads.push_back(x: std::move(Payload));
411 } else
412 E1List.Payloads.push_back(x: E2.takePayload());
413
414 return E1;
415 }
416 if (E2.isA<ErrorList>()) {
417 auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
418 E2List.Payloads.insert(position: E2List.Payloads.begin(), x: E1.takePayload());
419 return E2;
420 }
421 return Error(std::unique_ptr<ErrorList>(
422 new ErrorList(E1.takePayload(), E2.takePayload())));
423 }
424
425 std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
426};
427
428/// Concatenate errors. The resulting Error is unchecked, and contains the
429/// ErrorInfo(s), if any, contained in E1, followed by the
430/// ErrorInfo(s), if any, contained in E2.
431inline Error joinErrors(Error E1, Error E2) {
432 return ErrorList::join(E1: std::move(E1), E2: std::move(E2));
433}
434
435/// Tagged union holding either a T or a Error.
436///
437/// This class parallels ErrorOr, but replaces error_code with Error. Since
438/// Error cannot be copied, this class replaces getError() with
439/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
440/// error class type.
441///
442/// Example usage of 'Expected<T>' as a function return type:
443///
444/// @code{.cpp}
445/// Expected<int> myDivide(int A, int B) {
446/// if (B == 0) {
447/// // return an Error
448/// return createStringError(inconvertibleErrorCode(),
449/// "B must not be zero!");
450/// }
451/// // return an integer
452/// return A / B;
453/// }
454/// @endcode
455///
456/// Checking the results of to a function returning 'Expected<T>':
457/// @code{.cpp}
458/// if (auto E = Result.takeError()) {
459/// // We must consume the error. Typically one of:
460/// // - return the error to our caller
461/// // - toString(), when logging
462/// // - consumeError(), to silently swallow the error
463/// // - handleErrors(), to distinguish error types
464/// errs() << "Problem with division " << toString(std::move(E)) << "\n";
465/// return;
466/// }
467/// // use the result
468/// outs() << "The answer is " << *Result << "\n";
469/// @endcode
470///
471/// For unit-testing a function returning an 'Expected<T>', see the
472/// 'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h
473
474template <class T> class [[nodiscard]] Expected {
475 template <class T1> friend class ExpectedAsOutParameter;
476 template <class OtherT> friend class Expected;
477
478 static constexpr bool isRef = std::is_reference_v<T>;
479
480 using wrap = std::reference_wrapper<std::remove_reference_t<T>>;
481
482 using error_type = std::unique_ptr<ErrorInfoBase>;
483
484public:
485 using storage_type = std::conditional_t<isRef, wrap, T>;
486 using value_type = T;
487
488private:
489 using reference = std::remove_reference_t<T> &;
490 using const_reference = const std::remove_reference_t<T> &;
491 using pointer = std::remove_reference_t<T> *;
492 using const_pointer = const std::remove_reference_t<T> *;
493
494public:
495 /// Create an Expected<T> error value from the given Error.
496 Expected(Error Err)
497 : HasError(true)
498#if LLVM_ENABLE_ABI_BREAKING_CHECKS
499 // Expected is unchecked upon construction in Debug builds.
500 , Unchecked(true)
501#endif
502 {
503 assert(Err && "Cannot create Expected<T> from Error success value.");
504 new (getErrorStorage()) error_type(Err.takePayload());
505 }
506
507 /// Forbid to convert from Error::success() implicitly, this avoids having
508 /// Expected<T> foo() { return Error::success(); } which compiles otherwise
509 /// but triggers the assertion above.
510 Expected(ErrorSuccess) = delete;
511
512 /// Create an Expected<T> success value from the given OtherT value, which
513 /// must be convertible to T.
514 template <typename OtherT>
515 Expected(OtherT &&Val,
516 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr)
517 : HasError(false)
518#if LLVM_ENABLE_ABI_BREAKING_CHECKS
519 // Expected is unchecked upon construction in Debug builds.
520 ,
521 Unchecked(true)
522#endif
523 {
524 new (getStorage()) storage_type(std::forward<OtherT>(Val));
525 }
526
527 /// Move construct an Expected<T> value.
528 Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
529
530 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
531 /// must be convertible to T.
532 template <class OtherT>
533 Expected(Expected<OtherT> &&Other,
534 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) {
535 moveConstruct(std::move(Other));
536 }
537
538 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
539 /// isn't convertible to T.
540 template <class OtherT>
541 explicit Expected(
542 Expected<OtherT> &&Other,
543 std::enable_if_t<!std::is_convertible_v<OtherT, T>> * = nullptr) {
544 moveConstruct(std::move(Other));
545 }
546
547 /// Move-assign from another Expected<T>.
548 Expected &operator=(Expected &&Other) {
549 moveAssign(std::move(Other));
550 return *this;
551 }
552
553 /// Destroy an Expected<T>.
554 ~Expected() {
555 assertIsChecked();
556 if (!HasError)
557 getStorage()->~storage_type();
558 else
559 getErrorStorage()->~error_type();
560 }
561
562 /// Return false if there is an error.
563 explicit operator bool() {
564#if LLVM_ENABLE_ABI_BREAKING_CHECKS
565 Unchecked = HasError;
566#endif
567 return !HasError;
568 }
569
570 /// Returns a reference to the stored T value.
571 reference get() {
572 assertIsChecked();
573 return *getStorage();
574 }
575
576 /// Returns a const reference to the stored T value.
577 const_reference get() const {
578 assertIsChecked();
579 return const_cast<Expected<T> *>(this)->get();
580 }
581
582 /// Returns \a takeError() after moving the held T (if any) into \p V.
583 template <class OtherT>
584 Error moveInto(
585 OtherT &Value,
586 std::enable_if_t<std::is_assignable_v<OtherT &, T &&>> * = nullptr) && {
587 if (*this)
588 Value = std::move(get());
589 return takeError();
590 }
591
592 /// Check that this Expected<T> is an error of type ErrT.
593 template <typename ErrT> bool errorIsA() const {
594 return HasError && (*getErrorStorage())->template isA<ErrT>();
595 }
596
597 /// Take ownership of the stored error.
598 /// After calling this the Expected<T> is in an indeterminate state that can
599 /// only be safely destructed. No further calls (beside the destructor) should
600 /// be made on the Expected<T> value.
601 Error takeError() {
602#if LLVM_ENABLE_ABI_BREAKING_CHECKS
603 Unchecked = false;
604#endif
605 return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
606 }
607
608 /// Returns a pointer to the stored T value.
609 pointer operator->() {
610 assertIsChecked();
611 return toPointer(getStorage());
612 }
613
614 /// Returns a const pointer to the stored T value.
615 const_pointer operator->() const {
616 assertIsChecked();
617 return toPointer(getStorage());
618 }
619
620 /// Returns a reference to the stored T value.
621 reference operator*() {
622 assertIsChecked();
623 return *getStorage();
624 }
625
626 /// Returns a const reference to the stored T value.
627 const_reference operator*() const {
628 assertIsChecked();
629 return *getStorage();
630 }
631
632private:
633 template <class T1>
634 static bool compareThisIfSameType(const T1 &a, const T1 &b) {
635 return &a == &b;
636 }
637
638 template <class T1, class T2>
639 static bool compareThisIfSameType(const T1 &, const T2 &) {
640 return false;
641 }
642
643 template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
644 HasError = Other.HasError;
645#if LLVM_ENABLE_ABI_BREAKING_CHECKS
646 Unchecked = true;
647 Other.Unchecked = false;
648#endif
649
650 if (!HasError)
651 new (getStorage()) storage_type(std::move(*Other.getStorage()));
652 else
653 new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
654 }
655
656 template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
657 assertIsChecked();
658
659 if (compareThisIfSameType(*this, Other))
660 return;
661
662 this->~Expected();
663 new (this) Expected(std::move(Other));
664 }
665
666 pointer toPointer(pointer Val) { return Val; }
667
668 const_pointer toPointer(const_pointer Val) const { return Val; }
669
670 pointer toPointer(wrap *Val) { return &Val->get(); }
671
672 const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
673
674 storage_type *getStorage() {
675 assert(!HasError && "Cannot get value when an error exists!");
676 return reinterpret_cast<storage_type *>(&TStorage);
677 }
678
679 const storage_type *getStorage() const {
680 assert(!HasError && "Cannot get value when an error exists!");
681 return reinterpret_cast<const storage_type *>(&TStorage);
682 }
683
684 error_type *getErrorStorage() {
685 assert(HasError && "Cannot get error when a value exists!");
686 return reinterpret_cast<error_type *>(&ErrorStorage);
687 }
688
689 const error_type *getErrorStorage() const {
690 assert(HasError && "Cannot get error when a value exists!");
691 return reinterpret_cast<const error_type *>(&ErrorStorage);
692 }
693
694 // Used by ExpectedAsOutParameter to reset the checked flag.
695 void setUnchecked() {
696#if LLVM_ENABLE_ABI_BREAKING_CHECKS
697 Unchecked = true;
698#endif
699 }
700
701#if LLVM_ENABLE_ABI_BREAKING_CHECKS
702 [[noreturn]] LLVM_ATTRIBUTE_NOINLINE void fatalUncheckedExpected() const {
703 dbgs() << "Expected<T> must be checked before access or destruction.\n";
704 if (HasError) {
705 dbgs() << "Unchecked Expected<T> contained error:\n";
706 (*getErrorStorage())->log(dbgs());
707 } else
708 dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
709 "values in success mode must still be checked prior to being "
710 "destroyed).\n";
711 abort();
712 }
713#endif
714
715 void assertIsChecked() const {
716#if LLVM_ENABLE_ABI_BREAKING_CHECKS
717 if (LLVM_UNLIKELY(Unchecked))
718 fatalUncheckedExpected();
719#endif
720 }
721
722 union {
723 AlignedCharArrayUnion<storage_type> TStorage;
724 AlignedCharArrayUnion<error_type> ErrorStorage;
725 };
726 bool HasError : 1;
727#if LLVM_ENABLE_ABI_BREAKING_CHECKS
728 bool Unchecked : 1;
729#endif
730};
731
732/// Report a serious error, calling any installed error handler. See
733/// ErrorHandling.h.
734[[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true);
735
736/// Report a fatal error if Err is a failure value.
737///
738/// This function can be used to wrap calls to fallible functions ONLY when it
739/// is known that the Error will always be a success value. E.g.
740///
741/// @code{.cpp}
742/// // foo only attempts the fallible operation if DoFallibleOperation is
743/// // true. If DoFallibleOperation is false then foo always returns
744/// // Error::success().
745/// Error foo(bool DoFallibleOperation);
746///
747/// cantFail(foo(false));
748/// @endcode
749inline void cantFail(Error Err, const char *Msg = nullptr) {
750 if (Err) {
751 if (!Msg)
752 Msg = "Failure value returned from cantFail wrapped call";
753#ifndef NDEBUG
754 std::string Str;
755 raw_string_ostream OS(Str);
756 OS << Msg << "\n" << Err;
757 Msg = OS.str().c_str();
758#endif
759 llvm_unreachable(Msg);
760 }
761}
762
763/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
764/// returns the contained value.
765///
766/// This function can be used to wrap calls to fallible functions ONLY when it
767/// is known that the Error will always be a success value. E.g.
768///
769/// @code{.cpp}
770/// // foo only attempts the fallible operation if DoFallibleOperation is
771/// // true. If DoFallibleOperation is false then foo always returns an int.
772/// Expected<int> foo(bool DoFallibleOperation);
773///
774/// int X = cantFail(foo(false));
775/// @endcode
776template <typename T>
777T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
778 if (ValOrErr)
779 return std::move(*ValOrErr);
780 else {
781 if (!Msg)
782 Msg = "Failure value returned from cantFail wrapped call";
783#ifndef NDEBUG
784 std::string Str;
785 raw_string_ostream OS(Str);
786 auto E = ValOrErr.takeError();
787 OS << Msg << "\n" << E;
788 Msg = OS.str().c_str();
789#endif
790 llvm_unreachable(Msg);
791 }
792}
793
794/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
795/// returns the contained reference.
796///
797/// This function can be used to wrap calls to fallible functions ONLY when it
798/// is known that the Error will always be a success value. E.g.
799///
800/// @code{.cpp}
801/// // foo only attempts the fallible operation if DoFallibleOperation is
802/// // true. If DoFallibleOperation is false then foo always returns a Bar&.
803/// Expected<Bar&> foo(bool DoFallibleOperation);
804///
805/// Bar &X = cantFail(foo(false));
806/// @endcode
807template <typename T>
808T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
809 if (ValOrErr)
810 return *ValOrErr;
811 else {
812 if (!Msg)
813 Msg = "Failure value returned from cantFail wrapped call";
814#ifndef NDEBUG
815 std::string Str;
816 raw_string_ostream OS(Str);
817 auto E = ValOrErr.takeError();
818 OS << Msg << "\n" << E;
819 Msg = OS.str().c_str();
820#endif
821 llvm_unreachable(Msg);
822 }
823}
824
825/// Helper for testing applicability of, and applying, handlers for
826/// ErrorInfo types.
827template <typename HandlerT>
828class ErrorHandlerTraits
829 : public ErrorHandlerTraits<
830 decltype(&std::remove_reference_t<HandlerT>::operator())> {};
831
832// Specialization functions of the form 'Error (const ErrT&)'.
833template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
834public:
835 static bool appliesTo(const ErrorInfoBase &E) {
836 return E.template isA<ErrT>();
837 }
838
839 template <typename HandlerT>
840 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
841 assert(appliesTo(*E) && "Applying incorrect handler");
842 return H(static_cast<ErrT &>(*E));
843 }
844};
845
846// Specialization functions of the form 'void (const ErrT&)'.
847template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
848public:
849 static bool appliesTo(const ErrorInfoBase &E) {
850 return E.template isA<ErrT>();
851 }
852
853 template <typename HandlerT>
854 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
855 assert(appliesTo(*E) && "Applying incorrect handler");
856 H(static_cast<ErrT &>(*E));
857 return Error::success();
858 }
859};
860
861/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
862template <typename ErrT>
863class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
864public:
865 static bool appliesTo(const ErrorInfoBase &E) {
866 return E.template isA<ErrT>();
867 }
868
869 template <typename HandlerT>
870 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
871 assert(appliesTo(*E) && "Applying incorrect handler");
872 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
873 return H(std::move(SubE));
874 }
875};
876
877/// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
878template <typename ErrT>
879class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
880public:
881 static bool appliesTo(const ErrorInfoBase &E) {
882 return E.template isA<ErrT>();
883 }
884
885 template <typename HandlerT>
886 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
887 assert(appliesTo(*E) && "Applying incorrect handler");
888 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
889 H(std::move(SubE));
890 return Error::success();
891 }
892};
893
894// Specialization for member functions of the form 'RetT (const ErrT&)'.
895template <typename C, typename RetT, typename ErrT>
896class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
897 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
898
899// Specialization for member functions of the form 'RetT (const ErrT&) const'.
900template <typename C, typename RetT, typename ErrT>
901class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
902 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
903
904// Specialization for member functions of the form 'RetT (const ErrT&)'.
905template <typename C, typename RetT, typename ErrT>
906class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
907 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
908
909// Specialization for member functions of the form 'RetT (const ErrT&) const'.
910template <typename C, typename RetT, typename ErrT>
911class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
912 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
913
914/// Specialization for member functions of the form
915/// 'RetT (std::unique_ptr<ErrT>)'.
916template <typename C, typename RetT, typename ErrT>
917class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
918 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
919
920/// Specialization for member functions of the form
921/// 'RetT (std::unique_ptr<ErrT>) const'.
922template <typename C, typename RetT, typename ErrT>
923class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
924 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
925
926inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
927 return Error(std::move(Payload));
928}
929
930template <typename HandlerT, typename... HandlerTs>
931Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
932 HandlerT &&Handler, HandlerTs &&... Handlers) {
933 if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload))
934 return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
935 std::move(Payload));
936 return handleErrorImpl(std::move(Payload),
937 std::forward<HandlerTs>(Handlers)...);
938}
939
940/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
941/// unhandled errors (or Errors returned by handlers) are re-concatenated and
942/// returned.
943/// Because this function returns an error, its result must also be checked
944/// or returned. If you intend to handle all errors use handleAllErrors
945/// (which returns void, and will abort() on unhandled errors) instead.
946template <typename... HandlerTs>
947Error handleErrors(Error E, HandlerTs &&... Hs) {
948 if (!E)
949 return Error::success();
950
951 std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
952
953 if (Payload->isA<ErrorList>()) {
954 ErrorList &List = static_cast<ErrorList &>(*Payload);
955 Error R;
956 for (auto &P : List.Payloads)
957 R = ErrorList::join(
958 E1: std::move(R),
959 E2: handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
960 return R;
961 }
962
963 return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
964}
965
966/// Behaves the same as handleErrors, except that by contract all errors
967/// *must* be handled by the given handlers (i.e. there must be no remaining
968/// errors after running the handlers, or llvm_unreachable is called).
969template <typename... HandlerTs>
970void handleAllErrors(Error E, HandlerTs &&... Handlers) {
971 cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
972}
973
974/// Check that E is a non-error, then drop it.
975/// If E is an error, llvm_unreachable will be called.
976inline void handleAllErrors(Error E) {
977 cantFail(Err: std::move(E));
978}
979
980/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
981///
982/// If the incoming value is a success value it is returned unmodified. If it
983/// is a failure value then it the contained error is passed to handleErrors.
984/// If handleErrors is able to handle the error then the RecoveryPath functor
985/// is called to supply the final result. If handleErrors is not able to
986/// handle all errors then the unhandled errors are returned.
987///
988/// This utility enables the follow pattern:
989///
990/// @code{.cpp}
991/// enum FooStrategy { Aggressive, Conservative };
992/// Expected<Foo> foo(FooStrategy S);
993///
994/// auto ResultOrErr =
995/// handleExpected(
996/// foo(Aggressive),
997/// []() { return foo(Conservative); },
998/// [](AggressiveStrategyError&) {
999/// // Implicitly conusme this - we'll recover by using a conservative
1000/// // strategy.
1001/// });
1002///
1003/// @endcode
1004template <typename T, typename RecoveryFtor, typename... HandlerTs>
1005Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
1006 HandlerTs &&... Handlers) {
1007 if (ValOrErr)
1008 return ValOrErr;
1009
1010 if (auto Err = handleErrors(ValOrErr.takeError(),
1011 std::forward<HandlerTs>(Handlers)...))
1012 return std::move(Err);
1013
1014 return RecoveryPath();
1015}
1016
1017/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
1018/// will be printed before the first one is logged. A newline will be printed
1019/// after each error.
1020///
1021/// This function is compatible with the helpers from Support/WithColor.h. You
1022/// can pass any of them as the OS. Please consider using them instead of
1023/// including 'error: ' in the ErrorBanner.
1024///
1025/// This is useful in the base level of your program to allow clean termination
1026/// (allowing clean deallocation of resources, etc.), while reporting error
1027/// information to the user.
1028void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {});
1029
1030/// Write all error messages (if any) in E to a string. The newline character
1031/// is used to separate error messages.
1032std::string toString(Error E);
1033
1034/// Consume a Error without doing anything. This method should be used
1035/// only where an error can be considered a reasonable and expected return
1036/// value.
1037///
1038/// Uses of this method are potentially indicative of design problems: If it's
1039/// legitimate to do nothing while processing an "error", the error-producer
1040/// might be more clearly refactored to return an std::optional<T>.
1041inline void consumeError(Error Err) {
1042 handleAllErrors(E: std::move(Err), Handlers: [](const ErrorInfoBase &) {});
1043}
1044
1045/// Convert an Expected to an Optional without doing anything. This method
1046/// should be used only where an error can be considered a reasonable and
1047/// expected return value.
1048///
1049/// Uses of this method are potentially indicative of problems: perhaps the
1050/// error should be propagated further, or the error-producer should just
1051/// return an Optional in the first place.
1052template <typename T> std::optional<T> expectedToOptional(Expected<T> &&E) {
1053 if (E)
1054 return std::move(*E);
1055 consumeError(E.takeError());
1056 return std::nullopt;
1057}
1058
1059template <typename T> std::optional<T> expectedToStdOptional(Expected<T> &&E) {
1060 if (E)
1061 return std::move(*E);
1062 consumeError(E.takeError());
1063 return std::nullopt;
1064}
1065
1066/// Helper for converting an Error to a bool.
1067///
1068/// This method returns true if Err is in an error state, or false if it is
1069/// in a success state. Puts Err in a checked state in both cases (unlike
1070/// Error::operator bool(), which only does this for success states).
1071inline bool errorToBool(Error Err) {
1072 bool IsError = static_cast<bool>(Err);
1073 if (IsError)
1074 consumeError(Err: std::move(Err));
1075 return IsError;
1076}
1077
1078/// Helper for Errors used as out-parameters.
1079///
1080/// This helper is for use with the Error-as-out-parameter idiom, where an error
1081/// is passed to a function or method by reference, rather than being returned.
1082/// In such cases it is helpful to set the checked bit on entry to the function
1083/// so that the error can be written to (unchecked Errors abort on assignment)
1084/// and clear the checked bit on exit so that clients cannot accidentally forget
1085/// to check the result. This helper performs these actions automatically using
1086/// RAII:
1087///
1088/// @code{.cpp}
1089/// Result foo(Error &Err) {
1090/// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
1091/// // <body of foo>
1092/// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
1093/// }
1094/// @endcode
1095///
1096/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
1097/// used with optional Errors (Error pointers that are allowed to be null). If
1098/// ErrorAsOutParameter took an Error reference, an instance would have to be
1099/// created inside every condition that verified that Error was non-null. By
1100/// taking an Error pointer we can just create one instance at the top of the
1101/// function.
1102class ErrorAsOutParameter {
1103public:
1104 ErrorAsOutParameter(Error *Err) : Err(Err) {
1105 // Raise the checked bit if Err is success.
1106 if (Err)
1107 (void)!!*Err;
1108 }
1109
1110 ~ErrorAsOutParameter() {
1111 // Clear the checked bit.
1112 if (Err && !*Err)
1113 *Err = Error::success();
1114 }
1115
1116private:
1117 Error *Err;
1118};
1119
1120/// Helper for Expected<T>s used as out-parameters.
1121///
1122/// See ErrorAsOutParameter.
1123template <typename T>
1124class ExpectedAsOutParameter {
1125public:
1126 ExpectedAsOutParameter(Expected<T> *ValOrErr)
1127 : ValOrErr(ValOrErr) {
1128 if (ValOrErr)
1129 (void)!!*ValOrErr;
1130 }
1131
1132 ~ExpectedAsOutParameter() {
1133 if (ValOrErr)
1134 ValOrErr->setUnchecked();
1135 }
1136
1137private:
1138 Expected<T> *ValOrErr;
1139};
1140
1141/// This class wraps a std::error_code in a Error.
1142///
1143/// This is useful if you're writing an interface that returns a Error
1144/// (or Expected) and you want to call code that still returns
1145/// std::error_codes.
1146class ECError : public ErrorInfo<ECError> {
1147 friend Error errorCodeToError(std::error_code);
1148
1149 void anchor() override;
1150
1151public:
1152 void setErrorCode(std::error_code EC) { this->EC = EC; }
1153 std::error_code convertToErrorCode() const override { return EC; }
1154 void log(raw_ostream &OS) const override { OS << EC.message(); }
1155
1156 // Used by ErrorInfo::classID.
1157 static char ID;
1158
1159protected:
1160 ECError() = default;
1161 ECError(std::error_code EC) : EC(EC) {}
1162
1163 std::error_code EC;
1164};
1165
1166/// The value returned by this function can be returned from convertToErrorCode
1167/// for Error values where no sensible translation to std::error_code exists.
1168/// It should only be used in this situation, and should never be used where a
1169/// sensible conversion to std::error_code is available, as attempts to convert
1170/// to/from this error will result in a fatal error. (i.e. it is a programmatic
1171/// error to try to convert such a value).
1172std::error_code inconvertibleErrorCode();
1173
1174/// Helper for converting an std::error_code to a Error.
1175Error errorCodeToError(std::error_code EC);
1176
1177/// Helper for converting an ECError to a std::error_code.
1178///
1179/// This method requires that Err be Error() or an ECError, otherwise it
1180/// will trigger a call to abort().
1181std::error_code errorToErrorCode(Error Err);
1182
1183/// Helper to get errno as an std::error_code.
1184///
1185/// errno should always be represented using the generic category as that's what
1186/// both libc++ and libstdc++ do. On POSIX systems you can also represent them
1187/// using the system category, however this makes them compare differently for
1188/// values outside of those used by `std::errc` if one is generic and the other
1189/// is system.
1190///
1191/// See the libc++ and libstdc++ implementations of `default_error_condition` on
1192/// the system category for more details on what the difference is.
1193inline std::error_code errnoAsErrorCode() {
1194 return std::error_code(errno, std::generic_category());
1195}
1196
1197/// Convert an ErrorOr<T> to an Expected<T>.
1198template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1199 if (auto EC = EO.getError())
1200 return errorCodeToError(EC);
1201 return std::move(*EO);
1202}
1203
1204/// Convert an Expected<T> to an ErrorOr<T>.
1205template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1206 if (auto Err = E.takeError())
1207 return errorToErrorCode(std::move(Err));
1208 return std::move(*E);
1209}
1210
1211/// This class wraps a string in an Error.
1212///
1213/// StringError is useful in cases where the client is not expected to be able
1214/// to consume the specific error message programmatically (for example, if the
1215/// error message is to be presented to the user).
1216///
1217/// StringError can also be used when additional information is to be printed
1218/// along with a error_code message. Depending on the constructor called, this
1219/// class can either display:
1220/// 1. the error_code message (ECError behavior)
1221/// 2. a string
1222/// 3. the error_code message and a string
1223///
1224/// These behaviors are useful when subtyping is required; for example, when a
1225/// specific library needs an explicit error type. In the example below,
1226/// PDBError is derived from StringError:
1227///
1228/// @code{.cpp}
1229/// Expected<int> foo() {
1230/// return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading,
1231/// "Additional information");
1232/// }
1233/// @endcode
1234///
1235class StringError : public ErrorInfo<StringError> {
1236public:
1237 static char ID;
1238
1239 // Prints EC + S and converts to EC
1240 StringError(std::error_code EC, const Twine &S = Twine());
1241
1242 // Prints S and converts to EC
1243 StringError(const Twine &S, std::error_code EC);
1244
1245 void log(raw_ostream &OS) const override;
1246 std::error_code convertToErrorCode() const override;
1247
1248 const std::string &getMessage() const { return Msg; }
1249
1250private:
1251 std::string Msg;
1252 std::error_code EC;
1253 const bool PrintMsgOnly = false;
1254};
1255
1256/// Create formatted StringError object.
1257template <typename... Ts>
1258inline Error createStringError(std::error_code EC, char const *Fmt,
1259 const Ts &... Vals) {
1260 std::string Buffer;
1261 raw_string_ostream Stream(Buffer);
1262 Stream << format(Fmt, Vals...);
1263 return make_error<StringError>(Args&: Stream.str(), Args&: EC);
1264}
1265
1266Error createStringError(std::error_code EC, char const *Msg);
1267
1268inline Error createStringError(std::error_code EC, const Twine &S) {
1269 return createStringError(EC, Msg: S.str().c_str());
1270}
1271
1272template <typename... Ts>
1273inline Error createStringError(std::errc EC, char const *Fmt,
1274 const Ts &... Vals) {
1275 return createStringError(std::make_error_code(e: EC), Fmt, Vals...);
1276}
1277
1278/// This class wraps a filename and another Error.
1279///
1280/// In some cases, an error needs to live along a 'source' name, in order to
1281/// show more detailed information to the user.
1282class FileError final : public ErrorInfo<FileError> {
1283
1284 friend Error createFileError(const Twine &, Error);
1285 friend Error createFileError(const Twine &, size_t, Error);
1286
1287public:
1288 void log(raw_ostream &OS) const override {
1289 assert(Err && "Trying to log after takeError().");
1290 OS << "'" << FileName << "': ";
1291 if (Line)
1292 OS << "line " << *Line << ": ";
1293 Err->log(OS);
1294 }
1295
1296 std::string messageWithoutFileInfo() const {
1297 std::string Msg;
1298 raw_string_ostream OS(Msg);
1299 Err->log(OS);
1300 return OS.str();
1301 }
1302
1303 StringRef getFileName() const { return FileName; }
1304
1305 Error takeError() { return Error(std::move(Err)); }
1306
1307 std::error_code convertToErrorCode() const override;
1308
1309 // Used by ErrorInfo::classID.
1310 static char ID;
1311
1312private:
1313 FileError(const Twine &F, std::optional<size_t> LineNum,
1314 std::unique_ptr<ErrorInfoBase> E) {
1315 assert(E && "Cannot create FileError from Error success value.");
1316 FileName = F.str();
1317 Err = std::move(E);
1318 Line = std::move(LineNum);
1319 }
1320
1321 static Error build(const Twine &F, std::optional<size_t> Line, Error E) {
1322 std::unique_ptr<ErrorInfoBase> Payload;
1323 handleAllErrors(E: std::move(E),
1324 Handlers: [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error {
1325 Payload = std::move(EIB);
1326 return Error::success();
1327 });
1328 return Error(
1329 std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload))));
1330 }
1331
1332 std::string FileName;
1333 std::optional<size_t> Line;
1334 std::unique_ptr<ErrorInfoBase> Err;
1335};
1336
1337/// Concatenate a source file path and/or name with an Error. The resulting
1338/// Error is unchecked.
1339inline Error createFileError(const Twine &F, Error E) {
1340 return FileError::build(F, Line: std::optional<size_t>(), E: std::move(E));
1341}
1342
1343/// Concatenate a source file path and/or name with line number and an Error.
1344/// The resulting Error is unchecked.
1345inline Error createFileError(const Twine &F, size_t Line, Error E) {
1346 return FileError::build(F, Line: std::optional<size_t>(Line), E: std::move(E));
1347}
1348
1349/// Concatenate a source file path and/or name with a std::error_code
1350/// to form an Error object.
1351inline Error createFileError(const Twine &F, std::error_code EC) {
1352 return createFileError(F, E: errorCodeToError(EC));
1353}
1354
1355/// Concatenate a source file path and/or name with line number and
1356/// std::error_code to form an Error object.
1357inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) {
1358 return createFileError(F, Line, E: errorCodeToError(EC));
1359}
1360
1361Error createFileError(const Twine &F, ErrorSuccess) = delete;
1362
1363/// Helper for check-and-exit error handling.
1364///
1365/// For tool use only. NOT FOR USE IN LIBRARY CODE.
1366///
1367class ExitOnError {
1368public:
1369 /// Create an error on exit helper.
1370 ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
1371 : Banner(std::move(Banner)),
1372 GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1373
1374 /// Set the banner string for any errors caught by operator().
1375 void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1376
1377 /// Set the exit-code mapper function.
1378 void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1379 this->GetExitCode = std::move(GetExitCode);
1380 }
1381
1382 /// Check Err. If it's in a failure state log the error(s) and exit.
1383 void operator()(Error Err) const { checkError(Err: std::move(Err)); }
1384
1385 /// Check E. If it's in a success state then return the contained value. If
1386 /// it's in a failure state log the error(s) and exit.
1387 template <typename T> T operator()(Expected<T> &&E) const {
1388 checkError(Err: E.takeError());
1389 return std::move(*E);
1390 }
1391
1392 /// Check E. If it's in a success state then return the contained reference. If
1393 /// it's in a failure state log the error(s) and exit.
1394 template <typename T> T& operator()(Expected<T&> &&E) const {
1395 checkError(Err: E.takeError());
1396 return *E;
1397 }
1398
1399private:
1400 void checkError(Error Err) const {
1401 if (Err) {
1402 int ExitCode = GetExitCode(Err);
1403 logAllUnhandledErrors(E: std::move(Err), OS&: errs(), ErrorBanner: Banner);
1404 exit(status: ExitCode);
1405 }
1406 }
1407
1408 std::string Banner;
1409 std::function<int(const Error &)> GetExitCode;
1410};
1411
1412/// Conversion from Error to LLVMErrorRef for C error bindings.
1413inline LLVMErrorRef wrap(Error Err) {
1414 return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
1415}
1416
1417/// Conversion from LLVMErrorRef to Error for C error bindings.
1418inline Error unwrap(LLVMErrorRef ErrRef) {
1419 return Error(std::unique_ptr<ErrorInfoBase>(
1420 reinterpret_cast<ErrorInfoBase *>(ErrRef)));
1421}
1422
1423} // end namespace llvm
1424
1425#endif // LLVM_SUPPORT_ERROR_H
1426

source code of llvm/include/llvm/Support/Error.h