LLVM 19.0.0git
Error.h
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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"
21#include "llvm/Support/Debug.h"
24#include "llvm/Support/Format.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.
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;
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 // visitErrors needs direct access to the payload.
170 template <typename HandlerT>
171 friend void visitErrors(const Error &E, HandlerT H);
172
173 // Expected<T> needs to be able to steal the payload when constructed from an
174 // error.
175 template <typename T> friend class Expected;
176
177 // wrap needs to be able to steal the payload.
178 friend LLVMErrorRef wrap(Error);
179
180protected:
181 /// Create a success value. Prefer using 'Error::success()' for readability
183 setPtr(nullptr);
184 setChecked(false);
185 }
186
187public:
188 /// Create a success value.
189 static ErrorSuccess success();
190
191 // Errors are not copy-constructable.
192 Error(const Error &Other) = delete;
193
194 /// Move-construct an error value. The newly constructed error is considered
195 /// unchecked, even if the source error had been checked. The original error
196 /// becomes a checked Success value, regardless of its original state.
198 setChecked(true);
199 *this = std::move(Other);
200 }
201
202 /// Create an error value. Prefer using the 'make_error' function, but
203 /// this constructor can be useful when "re-throwing" errors from handlers.
204 Error(std::unique_ptr<ErrorInfoBase> Payload) {
205 setPtr(Payload.release());
206 setChecked(false);
207 }
208
209 // Errors are not copy-assignable.
210 Error &operator=(const Error &Other) = delete;
211
212 /// Move-assign an error value. The current error must represent success, you
213 /// you cannot overwrite an unhandled error. The current error is then
214 /// considered unchecked. The source error becomes a checked success value,
215 /// regardless of its original state.
217 // Don't allow overwriting of unchecked values.
218 assertIsChecked();
219 setPtr(Other.getPtr());
220
221 // This Error is unchecked, even if the source error was checked.
222 setChecked(false);
223
224 // Null out Other's payload and set its checked bit.
225 Other.setPtr(nullptr);
226 Other.setChecked(true);
227
228 return *this;
229 }
230
231 /// Destroy a Error. Fails with a call to abort() if the error is
232 /// unchecked.
234 assertIsChecked();
235 delete getPtr();
236 }
237
238 /// Bool conversion. Returns true if this Error is in a failure state,
239 /// and false if it is in an accept state. If the error is in a Success state
240 /// it will be considered checked.
241 explicit operator bool() {
242 setChecked(getPtr() == nullptr);
243 return getPtr() != nullptr;
244 }
245
246 /// Check whether one error is a subclass of another.
247 template <typename ErrT> bool isA() const {
248 return getPtr() && getPtr()->isA(ErrT::classID());
249 }
250
251 /// Returns the dynamic class id of this error, or null if this is a success
252 /// value.
253 const void* dynamicClassID() const {
254 if (!getPtr())
255 return nullptr;
256 return getPtr()->dynamicClassID();
257 }
258
259private:
260#if LLVM_ENABLE_ABI_BREAKING_CHECKS
261 // assertIsChecked() happens very frequently, but under normal circumstances
262 // is supposed to be a no-op. So we want it to be inlined, but having a bunch
263 // of debug prints can cause the function to be too large for inlining. So
264 // it's important that we define this function out of line so that it can't be
265 // inlined.
266 [[noreturn]] void fatalUncheckedError() const;
267#endif
268
269 void assertIsChecked() {
270#if LLVM_ENABLE_ABI_BREAKING_CHECKS
271 if (LLVM_UNLIKELY(!getChecked() || getPtr()))
272 fatalUncheckedError();
273#endif
274 }
275
276 ErrorInfoBase *getPtr() const {
277#if LLVM_ENABLE_ABI_BREAKING_CHECKS
278 return reinterpret_cast<ErrorInfoBase*>(
279 reinterpret_cast<uintptr_t>(Payload) &
280 ~static_cast<uintptr_t>(0x1));
281#else
282 return Payload;
283#endif
284 }
285
286 void setPtr(ErrorInfoBase *EI) {
287#if LLVM_ENABLE_ABI_BREAKING_CHECKS
288 Payload = reinterpret_cast<ErrorInfoBase*>(
289 (reinterpret_cast<uintptr_t>(EI) &
290 ~static_cast<uintptr_t>(0x1)) |
291 (reinterpret_cast<uintptr_t>(Payload) & 0x1));
292#else
293 Payload = EI;
294#endif
295 }
296
297 bool getChecked() const {
298#if LLVM_ENABLE_ABI_BREAKING_CHECKS
299 return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
300#else
301 return true;
302#endif
303 }
304
305 void setChecked(bool V) {
306#if LLVM_ENABLE_ABI_BREAKING_CHECKS
307 Payload = reinterpret_cast<ErrorInfoBase*>(
308 (reinterpret_cast<uintptr_t>(Payload) &
309 ~static_cast<uintptr_t>(0x1)) |
310 (V ? 0 : 1));
311#endif
312 }
313
314 std::unique_ptr<ErrorInfoBase> takePayload() {
315 std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
316 setPtr(nullptr);
317 setChecked(true);
318 return Tmp;
319 }
320
322 if (auto *P = E.getPtr())
323 P->log(OS);
324 else
325 OS << "success";
326 return OS;
327 }
328
329 ErrorInfoBase *Payload = nullptr;
330};
331
332/// Subclass of Error for the sole purpose of identifying the success path in
333/// the type system. This allows to catch invalid conversion to Expected<T> at
334/// compile time.
335class ErrorSuccess final : public Error {};
336
338
339/// Make a Error instance representing failure using the given error info
340/// type.
341template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
342 return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
343}
344
345/// Base class for user error types. Users should declare their error types
346/// like:
347///
348/// class MyError : public ErrorInfo<MyError> {
349/// ....
350/// };
351///
352/// This class provides an implementation of the ErrorInfoBase::kind
353/// method, which is used by the Error RTTI system.
354template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
355class ErrorInfo : public ParentErrT {
356public:
357 using ParentErrT::ParentErrT; // inherit constructors
358
359 static const void *classID() { return &ThisErrT::ID; }
360
361 const void *dynamicClassID() const override { return &ThisErrT::ID; }
362
363 bool isA(const void *const ClassID) const override {
364 return ClassID == classID() || ParentErrT::isA(ClassID);
365 }
366};
367
368/// Special ErrorInfo subclass representing a list of ErrorInfos.
369/// Instances of this class are constructed by joinError.
370class ErrorList final : public ErrorInfo<ErrorList> {
371 // handleErrors needs to be able to iterate the payload list of an
372 // ErrorList.
373 template <typename... HandlerTs>
374 friend Error handleErrors(Error E, HandlerTs &&... Handlers);
375 // visitErrors needs to be able to iterate the payload list of an
376 // ErrorList.
377 template <typename HandlerT>
378 friend void visitErrors(const Error &E, HandlerT H);
379
380 // joinErrors is implemented in terms of join.
381 friend Error joinErrors(Error, Error);
382
383public:
384 void log(raw_ostream &OS) const override {
385 OS << "Multiple errors:\n";
386 for (const auto &ErrPayload : Payloads) {
387 ErrPayload->log(OS);
388 OS << "\n";
389 }
390 }
391
392 std::error_code convertToErrorCode() const override;
393
394 // Used by ErrorInfo::classID.
395 static char ID;
396
397private:
398 ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
399 std::unique_ptr<ErrorInfoBase> Payload2) {
400 assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&
401 "ErrorList constructor payloads should be singleton errors");
402 Payloads.push_back(std::move(Payload1));
403 Payloads.push_back(std::move(Payload2));
404 }
405
406 static Error join(Error E1, Error E2) {
407 if (!E1)
408 return E2;
409 if (!E2)
410 return E1;
411 if (E1.isA<ErrorList>()) {
412 auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
413 if (E2.isA<ErrorList>()) {
414 auto E2Payload = E2.takePayload();
415 auto &E2List = static_cast<ErrorList &>(*E2Payload);
416 for (auto &Payload : E2List.Payloads)
417 E1List.Payloads.push_back(std::move(Payload));
418 } else
419 E1List.Payloads.push_back(E2.takePayload());
420
421 return E1;
422 }
423 if (E2.isA<ErrorList>()) {
424 auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
425 E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
426 return E2;
427 }
428 return Error(std::unique_ptr<ErrorList>(
429 new ErrorList(E1.takePayload(), E2.takePayload())));
430 }
431
432 std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
433};
434
435/// Concatenate errors. The resulting Error is unchecked, and contains the
436/// ErrorInfo(s), if any, contained in E1, followed by the
437/// ErrorInfo(s), if any, contained in E2.
438inline Error joinErrors(Error E1, Error E2) {
439 return ErrorList::join(std::move(E1), std::move(E2));
440}
441
442/// Tagged union holding either a T or a Error.
443///
444/// This class parallels ErrorOr, but replaces error_code with Error. Since
445/// Error cannot be copied, this class replaces getError() with
446/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
447/// error class type.
448///
449/// Example usage of 'Expected<T>' as a function return type:
450///
451/// @code{.cpp}
452/// Expected<int> myDivide(int A, int B) {
453/// if (B == 0) {
454/// // return an Error
455/// return createStringError(inconvertibleErrorCode(),
456/// "B must not be zero!");
457/// }
458/// // return an integer
459/// return A / B;
460/// }
461/// @endcode
462///
463/// Checking the results of to a function returning 'Expected<T>':
464/// @code{.cpp}
465/// if (auto E = Result.takeError()) {
466/// // We must consume the error. Typically one of:
467/// // - return the error to our caller
468/// // - toString(), when logging
469/// // - consumeError(), to silently swallow the error
470/// // - handleErrors(), to distinguish error types
471/// errs() << "Problem with division " << toString(std::move(E)) << "\n";
472/// return;
473/// }
474/// // use the result
475/// outs() << "The answer is " << *Result << "\n";
476/// @endcode
477///
478/// For unit-testing a function returning an 'Expected<T>', see the
479/// 'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h
480
481template <class T> class [[nodiscard]] Expected {
482 template <class T1> friend class ExpectedAsOutParameter;
483 template <class OtherT> friend class Expected;
484
485 static constexpr bool isRef = std::is_reference_v<T>;
486
487 using wrap = std::reference_wrapper<std::remove_reference_t<T>>;
488
489 using error_type = std::unique_ptr<ErrorInfoBase>;
490
491public:
492 using storage_type = std::conditional_t<isRef, wrap, T>;
493 using value_type = T;
494
495private:
496 using reference = std::remove_reference_t<T> &;
497 using const_reference = const std::remove_reference_t<T> &;
498 using pointer = std::remove_reference_t<T> *;
499 using const_pointer = const std::remove_reference_t<T> *;
500
501public:
502 /// Create an Expected<T> error value from the given Error.
504 : HasError(true)
505#if LLVM_ENABLE_ABI_BREAKING_CHECKS
506 // Expected is unchecked upon construction in Debug builds.
507 , Unchecked(true)
508#endif
509 {
510 assert(Err && "Cannot create Expected<T> from Error success value.");
511 new (getErrorStorage()) error_type(Err.takePayload());
512 }
513
514 /// Forbid to convert from Error::success() implicitly, this avoids having
515 /// Expected<T> foo() { return Error::success(); } which compiles otherwise
516 /// but triggers the assertion above.
518
519 /// Create an Expected<T> success value from the given OtherT value, which
520 /// must be convertible to T.
521 template <typename OtherT>
522 Expected(OtherT &&Val,
523 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr)
524 : HasError(false)
525#if LLVM_ENABLE_ABI_BREAKING_CHECKS
526 // Expected is unchecked upon construction in Debug builds.
527 ,
528 Unchecked(true)
529#endif
530 {
531 new (getStorage()) storage_type(std::forward<OtherT>(Val));
532 }
533
534 /// Move construct an Expected<T> value.
535 Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
536
537 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
538 /// must be convertible to T.
539 template <class OtherT>
541 std::enable_if_t<std::is_convertible_v<OtherT, T>> * = nullptr) {
542 moveConstruct(std::move(Other));
543 }
544
545 /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
546 /// isn't convertible to T.
547 template <class OtherT>
548 explicit Expected(
550 std::enable_if_t<!std::is_convertible_v<OtherT, T>> * = nullptr) {
551 moveConstruct(std::move(Other));
552 }
553
554 /// Move-assign from another Expected<T>.
556 moveAssign(std::move(Other));
557 return *this;
558 }
559
560 /// Destroy an Expected<T>.
562 assertIsChecked();
563 if (!HasError)
564 getStorage()->~storage_type();
565 else
566 getErrorStorage()->~error_type();
567 }
568
569 /// Return false if there is an error.
570 explicit operator bool() {
571#if LLVM_ENABLE_ABI_BREAKING_CHECKS
572 Unchecked = HasError;
573#endif
574 return !HasError;
575 }
576
577 /// Returns a reference to the stored T value.
578 reference get() {
579 assertIsChecked();
580 return *getStorage();
581 }
582
583 /// Returns a const reference to the stored T value.
584 const_reference get() const {
585 assertIsChecked();
586 return const_cast<Expected<T> *>(this)->get();
587 }
588
589 /// Returns \a takeError() after moving the held T (if any) into \p V.
590 template <class OtherT>
592 OtherT &Value,
593 std::enable_if_t<std::is_assignable_v<OtherT &, T &&>> * = nullptr) && {
594 if (*this)
595 Value = std::move(get());
596 return takeError();
597 }
598
599 /// Check that this Expected<T> is an error of type ErrT.
600 template <typename ErrT> bool errorIsA() const {
601 return HasError && (*getErrorStorage())->template isA<ErrT>();
602 }
603
604 /// Take ownership of the stored error.
605 /// After calling this the Expected<T> is in an indeterminate state that can
606 /// only be safely destructed. No further calls (beside the destructor) should
607 /// be made on the Expected<T> value.
609#if LLVM_ENABLE_ABI_BREAKING_CHECKS
610 Unchecked = false;
611#endif
612 return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
613 }
614
615 /// Returns a pointer to the stored T value.
616 pointer operator->() {
617 assertIsChecked();
618 return toPointer(getStorage());
619 }
620
621 /// Returns a const pointer to the stored T value.
622 const_pointer operator->() const {
623 assertIsChecked();
624 return toPointer(getStorage());
625 }
626
627 /// Returns a reference to the stored T value.
628 reference operator*() {
629 assertIsChecked();
630 return *getStorage();
631 }
632
633 /// Returns a const reference to the stored T value.
634 const_reference operator*() const {
635 assertIsChecked();
636 return *getStorage();
637 }
638
639private:
640 template <class T1>
641 static bool compareThisIfSameType(const T1 &a, const T1 &b) {
642 return &a == &b;
643 }
644
645 template <class T1, class T2>
646 static bool compareThisIfSameType(const T1 &, const T2 &) {
647 return false;
648 }
649
650 template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
651 HasError = Other.HasError;
652#if LLVM_ENABLE_ABI_BREAKING_CHECKS
653 Unchecked = true;
654 Other.Unchecked = false;
655#endif
656
657 if (!HasError)
658 new (getStorage()) storage_type(std::move(*Other.getStorage()));
659 else
660 new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
661 }
662
663 template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
664 assertIsChecked();
665
666 if (compareThisIfSameType(*this, Other))
667 return;
668
669 this->~Expected();
670 new (this) Expected(std::move(Other));
671 }
672
673 pointer toPointer(pointer Val) { return Val; }
674
675 const_pointer toPointer(const_pointer Val) const { return Val; }
676
677 pointer toPointer(wrap *Val) { return &Val->get(); }
678
679 const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
680
681 storage_type *getStorage() {
682 assert(!HasError && "Cannot get value when an error exists!");
683 return reinterpret_cast<storage_type *>(&TStorage);
684 }
685
686 const storage_type *getStorage() const {
687 assert(!HasError && "Cannot get value when an error exists!");
688 return reinterpret_cast<const storage_type *>(&TStorage);
689 }
690
691 error_type *getErrorStorage() {
692 assert(HasError && "Cannot get error when a value exists!");
693 return reinterpret_cast<error_type *>(&ErrorStorage);
694 }
695
696 const error_type *getErrorStorage() const {
697 assert(HasError && "Cannot get error when a value exists!");
698 return reinterpret_cast<const error_type *>(&ErrorStorage);
699 }
700
701 // Used by ExpectedAsOutParameter to reset the checked flag.
702 void setUnchecked() {
703#if LLVM_ENABLE_ABI_BREAKING_CHECKS
704 Unchecked = true;
705#endif
706 }
707
708#if LLVM_ENABLE_ABI_BREAKING_CHECKS
709 [[noreturn]] LLVM_ATTRIBUTE_NOINLINE void fatalUncheckedExpected() const {
710 dbgs() << "Expected<T> must be checked before access or destruction.\n";
711 if (HasError) {
712 dbgs() << "Unchecked Expected<T> contained error:\n";
713 (*getErrorStorage())->log(dbgs());
714 } else
715 dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
716 "values in success mode must still be checked prior to being "
717 "destroyed).\n";
718 abort();
719 }
720#endif
721
722 void assertIsChecked() const {
723#if LLVM_ENABLE_ABI_BREAKING_CHECKS
724 if (LLVM_UNLIKELY(Unchecked))
725 fatalUncheckedExpected();
726#endif
727 }
728
729 union {
732 };
733 bool HasError : 1;
734#if LLVM_ENABLE_ABI_BREAKING_CHECKS
735 bool Unchecked : 1;
736#endif
737};
738
739/// Report a serious error, calling any installed error handler. See
740/// ErrorHandling.h.
741[[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true);
742
743/// Report a fatal error if Err is a failure value.
744///
745/// This function can be used to wrap calls to fallible functions ONLY when it
746/// is known that the Error will always be a success value. E.g.
747///
748/// @code{.cpp}
749/// // foo only attempts the fallible operation if DoFallibleOperation is
750/// // true. If DoFallibleOperation is false then foo always returns
751/// // Error::success().
752/// Error foo(bool DoFallibleOperation);
753///
754/// cantFail(foo(false));
755/// @endcode
756inline void cantFail(Error Err, const char *Msg = nullptr) {
757 if (Err) {
758 if (!Msg)
759 Msg = "Failure value returned from cantFail wrapped call";
760#ifndef NDEBUG
761 std::string Str;
763 OS << Msg << "\n" << Err;
764 Msg = OS.str().c_str();
765#endif
766 llvm_unreachable(Msg);
767 }
768}
769
770/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
771/// returns the contained value.
772///
773/// This function can be used to wrap calls to fallible functions ONLY when it
774/// is known that the Error will always be a success value. E.g.
775///
776/// @code{.cpp}
777/// // foo only attempts the fallible operation if DoFallibleOperation is
778/// // true. If DoFallibleOperation is false then foo always returns an int.
779/// Expected<int> foo(bool DoFallibleOperation);
780///
781/// int X = cantFail(foo(false));
782/// @endcode
783template <typename T>
784T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
785 if (ValOrErr)
786 return std::move(*ValOrErr);
787 else {
788 if (!Msg)
789 Msg = "Failure value returned from cantFail wrapped call";
790#ifndef NDEBUG
791 std::string Str;
793 auto E = ValOrErr.takeError();
794 OS << Msg << "\n" << E;
795 Msg = OS.str().c_str();
796#endif
797 llvm_unreachable(Msg);
798 }
799}
800
801/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
802/// returns the contained reference.
803///
804/// This function can be used to wrap calls to fallible functions ONLY when it
805/// is known that the Error will always be a success value. E.g.
806///
807/// @code{.cpp}
808/// // foo only attempts the fallible operation if DoFallibleOperation is
809/// // true. If DoFallibleOperation is false then foo always returns a Bar&.
810/// Expected<Bar&> foo(bool DoFallibleOperation);
811///
812/// Bar &X = cantFail(foo(false));
813/// @endcode
814template <typename T>
815T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
816 if (ValOrErr)
817 return *ValOrErr;
818 else {
819 if (!Msg)
820 Msg = "Failure value returned from cantFail wrapped call";
821#ifndef NDEBUG
822 std::string Str;
824 auto E = ValOrErr.takeError();
825 OS << Msg << "\n" << E;
826 Msg = OS.str().c_str();
827#endif
828 llvm_unreachable(Msg);
829 }
830}
831
832/// Helper for testing applicability of, and applying, handlers for
833/// ErrorInfo types.
834template <typename HandlerT>
836 : public ErrorHandlerTraits<
837 decltype(&std::remove_reference_t<HandlerT>::operator())> {};
838
839// Specialization functions of the form 'Error (const ErrT&)'.
840template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
841public:
842 static bool appliesTo(const ErrorInfoBase &E) {
843 return E.template isA<ErrT>();
844 }
845
846 template <typename HandlerT>
847 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
848 assert(appliesTo(*E) && "Applying incorrect handler");
849 return H(static_cast<ErrT &>(*E));
850 }
851};
852
853// Specialization functions of the form 'void (const ErrT&)'.
854template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
855public:
856 static bool appliesTo(const ErrorInfoBase &E) {
857 return E.template isA<ErrT>();
858 }
859
860 template <typename HandlerT>
861 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
862 assert(appliesTo(*E) && "Applying incorrect handler");
863 H(static_cast<ErrT &>(*E));
864 return Error::success();
865 }
866};
867
868/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
869template <typename ErrT>
870class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
871public:
872 static bool appliesTo(const ErrorInfoBase &E) {
873 return E.template isA<ErrT>();
874 }
875
876 template <typename HandlerT>
877 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
878 assert(appliesTo(*E) && "Applying incorrect handler");
879 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
880 return H(std::move(SubE));
881 }
882};
883
884/// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
885template <typename ErrT>
886class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
887public:
888 static bool appliesTo(const ErrorInfoBase &E) {
889 return E.template isA<ErrT>();
890 }
891
892 template <typename HandlerT>
893 static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
894 assert(appliesTo(*E) && "Applying incorrect handler");
895 std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
896 H(std::move(SubE));
897 return Error::success();
898 }
899};
900
901// Specialization for member functions of the form 'RetT (const ErrT&)'.
902template <typename C, typename RetT, typename ErrT>
903class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
904 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
905
906// Specialization for member functions of the form 'RetT (const ErrT&) const'.
907template <typename C, typename RetT, typename ErrT>
908class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
909 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
910
911// Specialization for member functions of the form 'RetT (const ErrT&)'.
912template <typename C, typename RetT, typename ErrT>
913class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
914 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
915
916// Specialization for member functions of the form 'RetT (const ErrT&) const'.
917template <typename C, typename RetT, typename ErrT>
918class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
919 : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
920
921/// Specialization for member functions of the form
922/// 'RetT (std::unique_ptr<ErrT>)'.
923template <typename C, typename RetT, typename ErrT>
924class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
925 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
926
927/// Specialization for member functions of the form
928/// 'RetT (std::unique_ptr<ErrT>) const'.
929template <typename C, typename RetT, typename ErrT>
930class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
931 : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
932
933inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
934 return Error(std::move(Payload));
935}
936
937template <typename HandlerT, typename... HandlerTs>
938Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
939 HandlerT &&Handler, HandlerTs &&... Handlers) {
941 return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
942 std::move(Payload));
943 return handleErrorImpl(std::move(Payload),
944 std::forward<HandlerTs>(Handlers)...);
945}
946
947/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
948/// unhandled errors (or Errors returned by handlers) are re-concatenated and
949/// returned.
950/// Because this function returns an error, its result must also be checked
951/// or returned. If you intend to handle all errors use handleAllErrors
952/// (which returns void, and will abort() on unhandled errors) instead.
953template <typename... HandlerTs>
954Error handleErrors(Error E, HandlerTs &&... Hs) {
955 if (!E)
956 return Error::success();
957
958 std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
959
960 if (Payload->isA<ErrorList>()) {
961 ErrorList &List = static_cast<ErrorList &>(*Payload);
962 Error R;
963 for (auto &P : List.Payloads)
964 R = ErrorList::join(
965 std::move(R),
966 handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
967 return R;
968 }
969
970 return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
971}
972
973/// Behaves the same as handleErrors, except that by contract all errors
974/// *must* be handled by the given handlers (i.e. there must be no remaining
975/// errors after running the handlers, or llvm_unreachable is called).
976template <typename... HandlerTs>
977void handleAllErrors(Error E, HandlerTs &&... Handlers) {
978 cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
979}
980
981/// Check that E is a non-error, then drop it.
982/// If E is an error, llvm_unreachable will be called.
983inline void handleAllErrors(Error E) {
984 cantFail(std::move(E));
985}
986
987/// Visit all the ErrorInfo(s) contained in E by passing them to the respective
988/// handler, without consuming the error.
989template <typename HandlerT> void visitErrors(const Error &E, HandlerT H) {
990 const ErrorInfoBase *Payload = E.getPtr();
991 if (!Payload)
992 return;
993
994 if (Payload->isA<ErrorList>()) {
995 const ErrorList &List = static_cast<const ErrorList &>(*Payload);
996 for (const auto &P : List.Payloads)
997 H(*P);
998 return;
999 }
1000
1001 return H(*Payload);
1002}
1003
1004/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
1005///
1006/// If the incoming value is a success value it is returned unmodified. If it
1007/// is a failure value then it the contained error is passed to handleErrors.
1008/// If handleErrors is able to handle the error then the RecoveryPath functor
1009/// is called to supply the final result. If handleErrors is not able to
1010/// handle all errors then the unhandled errors are returned.
1011///
1012/// This utility enables the follow pattern:
1013///
1014/// @code{.cpp}
1015/// enum FooStrategy { Aggressive, Conservative };
1016/// Expected<Foo> foo(FooStrategy S);
1017///
1018/// auto ResultOrErr =
1019/// handleExpected(
1020/// foo(Aggressive),
1021/// []() { return foo(Conservative); },
1022/// [](AggressiveStrategyError&) {
1023/// // Implicitly conusme this - we'll recover by using a conservative
1024/// // strategy.
1025/// });
1026///
1027/// @endcode
1028template <typename T, typename RecoveryFtor, typename... HandlerTs>
1029Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
1030 HandlerTs &&... Handlers) {
1031 if (ValOrErr)
1032 return ValOrErr;
1033
1034 if (auto Err = handleErrors(ValOrErr.takeError(),
1035 std::forward<HandlerTs>(Handlers)...))
1036 return std::move(Err);
1037
1038 return RecoveryPath();
1039}
1040
1041/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
1042/// will be printed before the first one is logged. A newline will be printed
1043/// after each error.
1044///
1045/// This function is compatible with the helpers from Support/WithColor.h. You
1046/// can pass any of them as the OS. Please consider using them instead of
1047/// including 'error: ' in the ErrorBanner.
1048///
1049/// This is useful in the base level of your program to allow clean termination
1050/// (allowing clean deallocation of resources, etc.), while reporting error
1051/// information to the user.
1052void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {});
1053
1054/// Write all error messages (if any) in E to a string. The newline character
1055/// is used to separate error messages.
1056std::string toString(Error E);
1057
1058/// Like toString(), but does not consume the error. This can be used to print
1059/// a warning while retaining the original error object.
1060std::string toStringWithoutConsuming(const Error &E);
1061
1062/// Consume a Error without doing anything. This method should be used
1063/// only where an error can be considered a reasonable and expected return
1064/// value.
1065///
1066/// Uses of this method are potentially indicative of design problems: If it's
1067/// legitimate to do nothing while processing an "error", the error-producer
1068/// might be more clearly refactored to return an std::optional<T>.
1069inline void consumeError(Error Err) {
1070 handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
1071}
1072
1073/// Convert an Expected to an Optional without doing anything. This method
1074/// should be used only where an error can be considered a reasonable and
1075/// expected return value.
1076///
1077/// Uses of this method are potentially indicative of problems: perhaps the
1078/// error should be propagated further, or the error-producer should just
1079/// return an Optional in the first place.
1080template <typename T> std::optional<T> expectedToOptional(Expected<T> &&E) {
1081 if (E)
1082 return std::move(*E);
1083 consumeError(E.takeError());
1084 return std::nullopt;
1085}
1086
1087template <typename T> std::optional<T> expectedToStdOptional(Expected<T> &&E) {
1088 if (E)
1089 return std::move(*E);
1090 consumeError(E.takeError());
1091 return std::nullopt;
1092}
1093
1094/// Helper for converting an Error to a bool.
1095///
1096/// This method returns true if Err is in an error state, or false if it is
1097/// in a success state. Puts Err in a checked state in both cases (unlike
1098/// Error::operator bool(), which only does this for success states).
1099inline bool errorToBool(Error Err) {
1100 bool IsError = static_cast<bool>(Err);
1101 if (IsError)
1102 consumeError(std::move(Err));
1103 return IsError;
1104}
1105
1106/// Helper for Errors used as out-parameters.
1107///
1108/// This helper is for use with the Error-as-out-parameter idiom, where an error
1109/// is passed to a function or method by reference, rather than being returned.
1110/// In such cases it is helpful to set the checked bit on entry to the function
1111/// so that the error can be written to (unchecked Errors abort on assignment)
1112/// and clear the checked bit on exit so that clients cannot accidentally forget
1113/// to check the result. This helper performs these actions automatically using
1114/// RAII:
1115///
1116/// @code{.cpp}
1117/// Result foo(Error &Err) {
1118/// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
1119/// // <body of foo>
1120/// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
1121/// }
1122/// @endcode
1123///
1124/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
1125/// used with optional Errors (Error pointers that are allowed to be null). If
1126/// ErrorAsOutParameter took an Error reference, an instance would have to be
1127/// created inside every condition that verified that Error was non-null. By
1128/// taking an Error pointer we can just create one instance at the top of the
1129/// function.
1131public:
1132 ErrorAsOutParameter(Error *Err) : Err(Err) {
1133 // Raise the checked bit if Err is success.
1134 if (Err)
1135 (void)!!*Err;
1136 }
1137
1139 // Clear the checked bit.
1140 if (Err && !*Err)
1141 *Err = Error::success();
1142 }
1143
1144private:
1145 Error *Err;
1146};
1147
1148/// Helper for Expected<T>s used as out-parameters.
1149///
1150/// See ErrorAsOutParameter.
1151template <typename T>
1153public:
1155 : ValOrErr(ValOrErr) {
1156 if (ValOrErr)
1157 (void)!!*ValOrErr;
1158 }
1159
1161 if (ValOrErr)
1162 ValOrErr->setUnchecked();
1163 }
1164
1165private:
1166 Expected<T> *ValOrErr;
1167};
1168
1169/// This class wraps a std::error_code in a Error.
1170///
1171/// This is useful if you're writing an interface that returns a Error
1172/// (or Expected) and you want to call code that still returns
1173/// std::error_codes.
1174class ECError : public ErrorInfo<ECError> {
1175 friend Error errorCodeToError(std::error_code);
1176
1177 void anchor() override;
1178
1179public:
1180 void setErrorCode(std::error_code EC) { this->EC = EC; }
1181 std::error_code convertToErrorCode() const override { return EC; }
1182 void log(raw_ostream &OS) const override { OS << EC.message(); }
1183
1184 // Used by ErrorInfo::classID.
1185 static char ID;
1186
1187protected:
1188 ECError() = default;
1189 ECError(std::error_code EC) : EC(EC) {}
1190
1191 std::error_code EC;
1192};
1193
1194/// The value returned by this function can be returned from convertToErrorCode
1195/// for Error values where no sensible translation to std::error_code exists.
1196/// It should only be used in this situation, and should never be used where a
1197/// sensible conversion to std::error_code is available, as attempts to convert
1198/// to/from this error will result in a fatal error. (i.e. it is a programmatic
1199/// error to try to convert such a value).
1200std::error_code inconvertibleErrorCode();
1201
1202/// Helper for converting an std::error_code to a Error.
1203Error errorCodeToError(std::error_code EC);
1204
1205/// Helper for converting an ECError to a std::error_code.
1206///
1207/// This method requires that Err be Error() or an ECError, otherwise it
1208/// will trigger a call to abort().
1209std::error_code errorToErrorCode(Error Err);
1210
1211/// Helper to get errno as an std::error_code.
1212///
1213/// errno should always be represented using the generic category as that's what
1214/// both libc++ and libstdc++ do. On POSIX systems you can also represent them
1215/// using the system category, however this makes them compare differently for
1216/// values outside of those used by `std::errc` if one is generic and the other
1217/// is system.
1218///
1219/// See the libc++ and libstdc++ implementations of `default_error_condition` on
1220/// the system category for more details on what the difference is.
1221inline std::error_code errnoAsErrorCode() {
1222 return std::error_code(errno, std::generic_category());
1223}
1224
1225/// Convert an ErrorOr<T> to an Expected<T>.
1226template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1227 if (auto EC = EO.getError())
1228 return errorCodeToError(EC);
1229 return std::move(*EO);
1230}
1231
1232/// Convert an Expected<T> to an ErrorOr<T>.
1233template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1234 if (auto Err = E.takeError())
1235 return errorToErrorCode(std::move(Err));
1236 return std::move(*E);
1237}
1238
1239/// This class wraps a string in an Error.
1240///
1241/// StringError is useful in cases where the client is not expected to be able
1242/// to consume the specific error message programmatically (for example, if the
1243/// error message is to be presented to the user).
1244///
1245/// StringError can also be used when additional information is to be printed
1246/// along with a error_code message. Depending on the constructor called, this
1247/// class can either display:
1248/// 1. the error_code message (ECError behavior)
1249/// 2. a string
1250/// 3. the error_code message and a string
1251///
1252/// These behaviors are useful when subtyping is required; for example, when a
1253/// specific library needs an explicit error type. In the example below,
1254/// PDBError is derived from StringError:
1255///
1256/// @code{.cpp}
1257/// Expected<int> foo() {
1258/// return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading,
1259/// "Additional information");
1260/// }
1261/// @endcode
1262///
1263class StringError : public ErrorInfo<StringError> {
1264public:
1265 static char ID;
1266
1267 StringError(std::string &&S, std::error_code EC, bool PrintMsgOnly);
1268 /// Prints EC + S and converts to EC.
1269 StringError(std::error_code EC, const Twine &S = Twine());
1270 /// Prints S and converts to EC.
1271 StringError(const Twine &S, std::error_code EC);
1272
1273 void log(raw_ostream &OS) const override;
1274 std::error_code convertToErrorCode() const override;
1275
1276 const std::string &getMessage() const { return Msg; }
1277
1278private:
1279 std::string Msg;
1280 std::error_code EC;
1281 const bool PrintMsgOnly = false;
1282};
1283
1284/// Create formatted StringError object.
1285template <typename... Ts>
1286inline Error createStringError(std::error_code EC, char const *Fmt,
1287 const Ts &... Vals) {
1288 std::string Buffer;
1289 raw_string_ostream(Buffer) << format(Fmt, Vals...);
1290 return make_error<StringError>(Buffer, EC);
1291}
1292
1293Error createStringError(std::string &&Msg, std::error_code EC);
1294
1295inline Error createStringError(std::error_code EC, const char *S) {
1296 return createStringError(std::string(S), EC);
1297}
1298
1299inline Error createStringError(std::error_code EC, const Twine &S) {
1300 return createStringError(S.str(), EC);
1301}
1302
1303/// Create a StringError with an inconvertible error code.
1306}
1307
1308template <typename... Ts>
1309inline Error createStringError(char const *Fmt, const Ts &...Vals) {
1310 return createStringError(llvm::inconvertibleErrorCode(), Fmt, Vals...);
1311}
1312
1313template <typename... Ts>
1314inline Error createStringError(std::errc EC, char const *Fmt,
1315 const Ts &... Vals) {
1316 return createStringError(std::make_error_code(EC), Fmt, Vals...);
1317}
1318
1319/// This class wraps a filename and another Error.
1320///
1321/// In some cases, an error needs to live along a 'source' name, in order to
1322/// show more detailed information to the user.
1323class FileError final : public ErrorInfo<FileError> {
1324
1325 friend Error createFileError(const Twine &, Error);
1326 friend Error createFileError(const Twine &, size_t, Error);
1327
1328public:
1329 void log(raw_ostream &OS) const override {
1330 assert(Err && "Trying to log after takeError().");
1331 OS << "'" << FileName << "': ";
1332 if (Line)
1333 OS << "line " << *Line << ": ";
1334 Err->log(OS);
1335 }
1336
1337 std::string messageWithoutFileInfo() const {
1338 std::string Msg;
1340 Err->log(OS);
1341 return OS.str();
1342 }
1343
1344 StringRef getFileName() const { return FileName; }
1345
1346 Error takeError() { return Error(std::move(Err)); }
1347
1348 std::error_code convertToErrorCode() const override;
1349
1350 // Used by ErrorInfo::classID.
1351 static char ID;
1352
1353private:
1354 FileError(const Twine &F, std::optional<size_t> LineNum,
1355 std::unique_ptr<ErrorInfoBase> E) {
1356 assert(E && "Cannot create FileError from Error success value.");
1357 FileName = F.str();
1358 Err = std::move(E);
1359 Line = std::move(LineNum);
1360 }
1361
1362 static Error build(const Twine &F, std::optional<size_t> Line, Error E) {
1363 std::unique_ptr<ErrorInfoBase> Payload;
1364 handleAllErrors(std::move(E),
1365 [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error {
1366 Payload = std::move(EIB);
1367 return Error::success();
1368 });
1369 return Error(
1370 std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload))));
1371 }
1372
1373 std::string FileName;
1374 std::optional<size_t> Line;
1375 std::unique_ptr<ErrorInfoBase> Err;
1376};
1377
1378/// Concatenate a source file path and/or name with an Error. The resulting
1379/// Error is unchecked.
1381 return FileError::build(F, std::optional<size_t>(), std::move(E));
1382}
1383
1384/// Concatenate a source file path and/or name with line number and an Error.
1385/// The resulting Error is unchecked.
1386inline Error createFileError(const Twine &F, size_t Line, Error E) {
1387 return FileError::build(F, std::optional<size_t>(Line), std::move(E));
1388}
1389
1390/// Concatenate a source file path and/or name with a std::error_code
1391/// to form an Error object.
1392inline Error createFileError(const Twine &F, std::error_code EC) {
1393 return createFileError(F, errorCodeToError(EC));
1394}
1395
1396/// Concatenate a source file path and/or name with line number and
1397/// std::error_code to form an Error object.
1398inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) {
1399 return createFileError(F, Line, errorCodeToError(EC));
1400}
1401
1403
1404/// Helper for check-and-exit error handling.
1405///
1406/// For tool use only. NOT FOR USE IN LIBRARY CODE.
1407///
1409public:
1410 /// Create an error on exit helper.
1411 ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
1412 : Banner(std::move(Banner)),
1413 GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1414
1415 /// Set the banner string for any errors caught by operator().
1416 void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1417
1418 /// Set the exit-code mapper function.
1419 void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1420 this->GetExitCode = std::move(GetExitCode);
1421 }
1422
1423 /// Check Err. If it's in a failure state log the error(s) and exit.
1424 void operator()(Error Err) const { checkError(std::move(Err)); }
1425
1426 /// Check E. If it's in a success state then return the contained value. If
1427 /// it's in a failure state log the error(s) and exit.
1428 template <typename T> T operator()(Expected<T> &&E) const {
1429 checkError(E.takeError());
1430 return std::move(*E);
1431 }
1432
1433 /// Check E. If it's in a success state then return the contained reference. If
1434 /// it's in a failure state log the error(s) and exit.
1435 template <typename T> T& operator()(Expected<T&> &&E) const {
1436 checkError(E.takeError());
1437 return *E;
1438 }
1439
1440private:
1441 void checkError(Error Err) const {
1442 if (Err) {
1443 int ExitCode = GetExitCode(Err);
1444 logAllUnhandledErrors(std::move(Err), errs(), Banner);
1445 exit(ExitCode);
1446 }
1447 }
1448
1449 std::string Banner;
1450 std::function<int(const Error &)> GetExitCode;
1451};
1452
1453/// Conversion from Error to LLVMErrorRef for C error bindings.
1455 return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
1456}
1457
1458/// Conversion from LLVMErrorRef to Error for C error bindings.
1459inline Error unwrap(LLVMErrorRef ErrRef) {
1460 return Error(std::unique_ptr<ErrorInfoBase>(
1461 reinterpret_cast<ErrorInfoBase *>(ErrRef)));
1462}
1463
1464} // end namespace llvm
1465
1466#endif // LLVM_SUPPORT_ERROR_H
aarch64 promote const
basic Basic Alias true
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
#define LLVM_UNLIKELY(EXPR)
Definition: Compiler.h:241
#define LLVM_ATTRIBUTE_NOINLINE
LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, mark a method "not for inl...
Definition: Compiler.h:251
std::optional< std::vector< StOtherPiece > > Other
Definition: ELFYAML.cpp:1293
Provides ErrorOr<T> smart pointer.
static LLVMTargetMachineRef wrap(const TargetMachine *P)
#define F(x, y, z)
Definition: MD5.cpp:55
#define H(x, y, z)
Definition: MD5.cpp:57
static const char * getPtr(const MachOObjectFile &O, size_t Offset, size_t MachOFilesetEntryOffset=0)
#define T
#define T1
#define P(N)
if(VerifyEach)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
raw_pwrite_stream & OS
This class wraps a std::error_code in a Error.
Definition: Error.h:1174
ECError()=default
std::error_code EC
Definition: Error.h:1191
std::error_code convertToErrorCode() const override
Convert this error to a std::error_code.
Definition: Error.h:1181
ECError(std::error_code EC)
Definition: Error.h:1189
friend Error errorCodeToError(std::error_code)
Helper for converting an std::error_code to a Error.
Definition: Error.cpp:111
void setErrorCode(std::error_code EC)
Definition: Error.h:1180
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.h:1182
static char ID
Definition: Error.h:1185
Helper for Errors used as out-parameters.
Definition: Error.h:1130
ErrorAsOutParameter(Error *Err)
Definition: Error.h:1132
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:842
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:847
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:877
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:872
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:856
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:861
static bool appliesTo(const ErrorInfoBase &E)
Definition: Error.h:888
static Error apply(HandlerT &&H, std::unique_ptr< ErrorInfoBase > E)
Definition: Error.h:893
Helper for testing applicability of, and applying, handlers for ErrorInfo types.
Definition: Error.h:837
Base class for error info classes.
Definition: Error.h:45
virtual ~ErrorInfoBase()=default
virtual std::string message() const
Return the error message as a string.
Definition: Error.h:53
static const void * classID()
Definition: Error.h:67
bool isA() const
Definition: Error.h:79
virtual const void * dynamicClassID() const =0
virtual bool isA(const void *const ClassID) const
Definition: Error.h:74
virtual std::error_code convertToErrorCode() const =0
Convert this error to a std::error_code.
virtual void log(raw_ostream &OS) const =0
Print an error message to an output stream.
Base class for user error types.
Definition: Error.h:355
bool isA(const void *const ClassID) const override
Definition: Error.h:363
const void * dynamicClassID() const override
Definition: Error.h:361
static const void * classID()
Definition: Error.h:359
Special ErrorInfo subclass representing a list of ErrorInfos.
Definition: Error.h:370
std::error_code convertToErrorCode() const override
Convert this error to a std::error_code.
Definition: Error.cpp:93
friend Error handleErrors(Error E, HandlerTs &&... Handlers)
Pass the ErrorInfo(s) contained in E to their respective handlers.
Definition: Error.h:954
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.h:384
static char ID
Definition: Error.h:395
friend Error joinErrors(Error, Error)
Concatenate errors.
Definition: Error.h:438
friend void visitErrors(const Error &E, HandlerT H)
Visit all the ErrorInfo(s) contained in E by passing them to the respective handler,...
Definition: Error.h:989
Represents either an error or a value T.
Definition: ErrorOr.h:56
Subclass of Error for the sole purpose of identifying the success path in the type system.
Definition: Error.h:335
Lightweight error class with error context and mandatory checking.
Definition: Error.h:160
Error(Error &&Other)
Move-construct an error value.
Definition: Error.h:197
~Error()
Destroy a Error.
Definition: Error.h:233
const void * dynamicClassID() const
Returns the dynamic class id of this error, or null if this is a success value.
Definition: Error.h:253
friend raw_ostream & operator<<(raw_ostream &OS, const Error &E)
Definition: Error.h:321
static ErrorSuccess success()
Create a success value.
Definition: Error.h:337
Error(std::unique_ptr< ErrorInfoBase > Payload)
Create an error value.
Definition: Error.h:204
Error & operator=(const Error &Other)=delete
Error()
Create a success value. Prefer using 'Error::success()' for readability.
Definition: Error.h:182
Error(const Error &Other)=delete
Error & operator=(Error &&Other)
Move-assign an error value.
Definition: Error.h:216
bool isA() const
Check whether one error is a subclass of another.
Definition: Error.h:247
Helper for check-and-exit error handling.
Definition: Error.h:1408
void setBanner(std::string Banner)
Set the banner string for any errors caught by operator().
Definition: Error.h:1416
ExitOnError(std::string Banner="", int DefaultErrorExitCode=1)
Create an error on exit helper.
Definition: Error.h:1411
T operator()(Expected< T > &&E) const
Check E.
Definition: Error.h:1428
T & operator()(Expected< T & > &&E) const
Check E.
Definition: Error.h:1435
void operator()(Error Err) const
Check Err. If it's in a failure state log the error(s) and exit.
Definition: Error.h:1424
void setExitCodeMapper(std::function< int(const Error &)> GetExitCode)
Set the exit-code mapper function.
Definition: Error.h:1419
Helper for Expected<T>s used as out-parameters.
Definition: Error.h:1152
ExpectedAsOutParameter(Expected< T > *ValOrErr)
Definition: Error.h:1154
Tagged union holding either a T or a Error.
Definition: Error.h:481
const_reference operator*() const
Returns a const reference to the stored T value.
Definition: Error.h:634
Expected(Expected< OtherT > &&Other, std::enable_if_t<!std::is_convertible_v< OtherT, T > > *=nullptr)
Move construct an Expected<T> value from an Expected<OtherT>, where OtherT isn't convertible to T.
Definition: Error.h:548
Error moveInto(OtherT &Value, std::enable_if_t< std::is_assignable_v< OtherT &, T && > > *=nullptr) &&
Returns takeError() after moving the held T (if any) into V.
Definition: Error.h:591
pointer operator->()
Returns a pointer to the stored T value.
Definition: Error.h:616
reference operator*()
Returns a reference to the stored T value.
Definition: Error.h:628
Expected(OtherT &&Val, std::enable_if_t< std::is_convertible_v< OtherT, T > > *=nullptr)
Create an Expected<T> success value from the given OtherT value, which must be convertible to T.
Definition: Error.h:522
~Expected()
Destroy an Expected<T>.
Definition: Error.h:561
const_reference get() const
Returns a const reference to the stored T value.
Definition: Error.h:584
bool errorIsA() const
Check that this Expected<T> is an error of type ErrT.
Definition: Error.h:600
Expected(ErrorSuccess)=delete
Forbid to convert from Error::success() implicitly, this avoids having Expected<T> foo() { return Err...
Expected(Error &&Err)
Create an Expected<T> error value from the given Error.
Definition: Error.h:503
AlignedCharArrayUnion< storage_type > TStorage
Definition: Error.h:730
Error takeError()
Take ownership of the stored error.
Definition: Error.h:608
const_pointer operator->() const
Returns a const pointer to the stored T value.
Definition: Error.h:622
Expected & operator=(Expected &&Other)
Move-assign from another Expected<T>.
Definition: Error.h:555
reference get()
Returns a reference to the stored T value.
Definition: Error.h:578
AlignedCharArrayUnion< error_type > ErrorStorage
Definition: Error.h:731
std::conditional_t< isRef, wrap, T > storage_type
Definition: Error.h:492
Expected(Expected &&Other)
Move construct an Expected<T> value.
Definition: Error.h:535
Expected(Expected< OtherT > &&Other, std::enable_if_t< std::is_convertible_v< OtherT, T > > *=nullptr)
Move construct an Expected<T> value from an Expected<OtherT>, where OtherT must be convertible to T.
Definition: Error.h:540
This class wraps a filename and another Error.
Definition: Error.h:1323
Error takeError()
Definition: Error.h:1346
static char ID
Definition: Error.h:1351
std::error_code convertToErrorCode() const override
Convert this error to a std::error_code.
Definition: Error.cpp:103
std::string messageWithoutFileInfo() const
Definition: Error.h:1337
StringRef getFileName() const
Definition: Error.h:1344
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.h:1329
friend Error createFileError(const Twine &, Error)
Concatenate a source file path and/or name with an Error.
Definition: Error.h:1380
This class wraps a string in an Error.
Definition: Error.h:1263
void log(raw_ostream &OS) const override
Print an error message to an output stream.
Definition: Error.cpp:149
const std::string & getMessage() const
Definition: Error.h:1276
std::error_code convertToErrorCode() const override
Convert this error to a std::error_code.
Definition: Error.cpp:159
static char ID
Definition: Error.h:1265
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
std::string str() const
Return the twine contents as a std::string.
Definition: Twine.cpp:17
LLVM Value Representation.
Definition: Value.h:74
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
A raw_ostream that writes to an std::string.
Definition: raw_ostream.h:661
struct LLVMOpaqueError * LLVMErrorRef
Opaque reference to an error instance.
Definition: Error.h:33
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
std::optional< const char * > toString(const std::optional< DWARFFormValue > &V)
Take an optional DWARFFormValue and try to extract a string value from it.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
bool errorToBool(Error Err)
Helper for converting an Error to a bool.
Definition: Error.h:1099
void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner={})
Log all errors (if any) in E to OS.
Definition: Error.cpp:65
void visitErrors(const Error &E, HandlerT H)
Visit all the ErrorInfo(s) contained in E by passing them to the respective handler,...
Definition: Error.h:989
Error createFileError(const Twine &F, Error E)
Concatenate a source file path and/or name with an Error.
Definition: Error.h:1380
std::optional< T > expectedToStdOptional(Expected< T > &&E)
Definition: Error.h:1087
void handleAllErrors(Error E, HandlerTs &&... Handlers)
Behaves the same as handleErrors, except that by contract all errors must be handled by the given han...
Definition: Error.h:977
std::error_code inconvertibleErrorCode()
The value returned by this function can be returned from convertToErrorCode for Error values where no...
Definition: Error.cpp:98
Error handleErrors(Error E, HandlerTs &&... Hs)
Pass the ErrorInfo(s) contained in E to their respective handlers.
Definition: Error.h:954
ErrorOr< T > expectedToErrorOr(Expected< T > &&E)
Convert an Expected<T> to an ErrorOr<T>.
Definition: Error.h:1233
Error createStringError(std::error_code EC, char const *Fmt, const Ts &... Vals)
Create formatted StringError object.
Definition: Error.h:1286
std::optional< T > expectedToOptional(Expected< T > &&E)
Convert an Expected to an Optional without doing anything.
Definition: Error.h:1080
std::string toStringWithoutConsuming(const Error &E)
Like toString(), but does not consume the error.
Definition: Error.cpp:85
Error joinErrors(Error E1, Error E2)
Concatenate errors.
Definition: Error.h:438
decltype(auto) get(const PointerIntPair< PointerTy, IntBits, IntType, PtrTraits, Info > &Pair)
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:167
Expected< T > handleExpected(Expected< T > ValOrErr, RecoveryFtor &&RecoveryPath, HandlerTs &&... Handlers)
Handle any errors (if present) in an Expected<T>, then try a recovery path.
Definition: Error.h:1029
format_object< Ts... > format(const char *Fmt, const Ts &... Vals)
These are helper functions used to produce formatted output.
Definition: Format.h:125
Error handleErrorImpl(std::unique_ptr< ErrorInfoBase > Payload)
Definition: Error.h:933
Error make_error(ArgTs &&... Args)
Make a Error instance representing failure using the given error info type.
Definition: Error.h:341
raw_fd_ostream & errs()
This returns a reference to a raw_ostream for standard error.
void cantFail(Error Err, const char *Msg=nullptr)
Report a fatal error if Err is a failure value.
Definition: Error.h:756
Attribute unwrap(LLVMAttributeRef Attr)
Definition: Attributes.h:320
Expected< T > errorOrToExpected(ErrorOr< T > &&EO)
Convert an ErrorOr<T> to an Expected<T>.
Definition: Error.h:1226
OutputIt move(R &&Range, OutputIt Out)
Provide wrappers to std::move which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1849
LLVMAttributeRef wrap(Attribute Attr)
Definition: Attributes.h:315
Error errorCodeToError(std::error_code EC)
Helper for converting an std::error_code to a Error.
Definition: Error.cpp:111
std::error_code errnoAsErrorCode()
Helper to get errno as an std::error_code.
Definition: Error.h:1221
std::error_code errorToErrorCode(Error Err)
Helper for converting an ECError to a std::error_code.
Definition: Error.cpp:117
void consumeError(Error Err)
Consume a Error without doing anything.
Definition: Error.h:1069
Implement std::hash so that hash_code can be used in STL containers.
Definition: BitVector.h:858
A suitably aligned and sized character array member which can hold elements of any type.
Definition: AlignOf.h:27