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

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