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//===----- llvm/Support/Error.h - Recoverable error handling ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines an API used to report recoverable errors.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_ERROR_H
#define LLVM_SUPPORT_ERROR_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Config/abi-breaking.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <functional>
#include <memory>
#include <new>
#include <string>
#include <system_error>
#include <type_traits>
#include <utility>
#include <vector>
namespace llvm {
class ErrorSuccess;
/// Base class for error info classes. Do not extend this directly: Extend
/// the ErrorInfo template subclass instead.
class ErrorInfoBase {
public:
virtual ~ErrorInfoBase() = default;
/// Print an error message to an output stream.
virtual void log(raw_ostream &OS) const = 0;
/// Return the error message as a string.
virtual std::string message() const {
std::string Msg;
raw_string_ostream OS(Msg);
log(OS);
return OS.str();
}
/// Convert this error to a std::error_code.
///
/// This is a temporary crutch to enable interaction with code still
/// using std::error_code. It will be removed in the future.
virtual std::error_code convertToErrorCode() const = 0;
// Check whether this instance is a subclass of the class identified by
// ClassID.
virtual bool isA(const void *const ClassID) const {
return ClassID == classID();
}
// Check whether this instance is a subclass of ErrorInfoT.
template <typename ErrorInfoT> bool isA() const {
return isA(ErrorInfoT::classID());
}
// Returns the class ID for this type.
static const void *classID() { return &ID; }
private:
virtual void anchor();
static char ID;
};
/// Lightweight error class with error context and mandatory checking.
///
/// Instances of this class wrap a ErrorInfoBase pointer. Failure states
/// are represented by setting the pointer to a ErrorInfoBase subclass
/// instance containing information describing the failure. Success is
/// represented by a null pointer value.
///
/// Instances of Error also contains a 'Checked' flag, which must be set
/// before the destructor is called, otherwise the destructor will trigger a
/// runtime error. This enforces at runtime the requirement that all Error
/// instances be checked or returned to the caller.
///
/// There are two ways to set the checked flag, depending on what state the
/// Error instance is in. For Error instances indicating success, it
/// is sufficient to invoke the boolean conversion operator. E.g.:
///
/// @code{.cpp}
/// Error foo(<...>);
///
/// if (auto E = foo(<...>))
/// return E; // <- Return E if it is in the error state.
/// // We have verified that E was in the success state. It can now be safely
/// // destroyed.
/// @endcode
///
/// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
/// without testing the return value will raise a runtime error, even if foo
/// returns success.
///
/// For Error instances representing failure, you must use either the
/// handleErrors or handleAllErrors function with a typed handler. E.g.:
///
/// @code{.cpp}
/// class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
/// // Custom error info.
/// };
///
/// Error foo(<...>) { return make_error<MyErrorInfo>(...); }
///
/// auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
/// auto NewE =
/// handleErrors(E,
/// [](const MyErrorInfo &M) {
/// // Deal with the error.
/// },
/// [](std::unique_ptr<OtherError> M) -> Error {
/// if (canHandle(*M)) {
/// // handle error.
/// return Error::success();
/// }
/// // Couldn't handle this error instance. Pass it up the stack.
/// return Error(std::move(M));
/// );
/// // Note - we must check or return NewE in case any of the handlers
/// // returned a new error.
/// @endcode
///
/// The handleAllErrors function is identical to handleErrors, except
/// that it has a void return type, and requires all errors to be handled and
/// no new errors be returned. It prevents errors (assuming they can all be
/// handled) from having to be bubbled all the way to the top-level.
///
/// *All* Error instances must be checked before destruction, even if
/// they're moved-assigned or constructed from Success values that have already
/// been checked. This enforces checking through all levels of the call stack.
class LLVM_NODISCARD Error {
// ErrorList needs to be able to yank ErrorInfoBase pointers out of this
// class to add to the error list.
friend class ErrorList;
// handleErrors needs to be able to set the Checked flag.
template <typename... HandlerTs>
friend Error handleErrors(Error E, HandlerTs &&... Handlers);
// Expected<T> needs to be able to steal the payload when constructed from an
// error.
template <typename T> friend class Expected;
protected:
/// Create a success value. Prefer using 'Error::success()' for readability
Error() : Payload(nullptr) {
setPtr(nullptr);
setChecked(false);
}
public:
/// Create a success value.
static ErrorSuccess success();
// Errors are not copy-constructable.
Error(const Error &Other) = delete;
/// Move-construct an error value. The newly constructed error is considered
/// unchecked, even if the source error had been checked. The original error
/// becomes a checked Success value, regardless of its original state.
Error(Error &&Other) : Payload(nullptr) {
setChecked(true);
*this = std::move(Other);
}
/// Create an error value. Prefer using the 'make_error' function, but
/// this constructor can be useful when "re-throwing" errors from handlers.
Error(std::unique_ptr<ErrorInfoBase> Payload) {
setPtr(Payload.release());
setChecked(false);
}
// Errors are not copy-assignable.
Error &operator=(const Error &Other) = delete;
/// Move-assign an error value. The current error must represent success, you
/// you cannot overwrite an unhandled error. The current error is then
/// considered unchecked. The source error becomes a checked success value,
/// regardless of its original state.
Error &operator=(Error &&Other) {
// Don't allow overwriting of unchecked values.
assertIsChecked();
setPtr(Other.getPtr());
// This Error is unchecked, even if the source error was checked.
setChecked(false);
// Null out Other's payload and set its checked bit.
Other.setPtr(nullptr);
Other.setChecked(true);
return *this;
}
/// Destroy a Error. Fails with a call to abort() if the error is
/// unchecked.
~Error() {
assertIsChecked();
delete getPtr();
}
/// Bool conversion. Returns true if this Error is in a failure state,
/// and false if it is in an accept state. If the error is in a Success state
/// it will be considered checked.
explicit operator bool() {
setChecked(getPtr() == nullptr);
return getPtr() != nullptr;
}
/// Check whether one error is a subclass of another.
template <typename ErrT> bool isA() const {
return getPtr() && getPtr()->isA(ErrT::classID());
}
private:
void assertIsChecked() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
if (!getChecked() || getPtr()) {
dbgs() << "Program aborted due to an unhandled Error:\n";
if (getPtr())
getPtr()->log(dbgs());
else
dbgs()
<< "Error value was Success. (Note: Success values must still be "
"checked prior to being destroyed).\n";
abort();
}
#endif
}
ErrorInfoBase *getPtr() const {
return reinterpret_cast<ErrorInfoBase*>(
reinterpret_cast<uintptr_t>(Payload) &
~static_cast<uintptr_t>(0x1));
}
void setPtr(ErrorInfoBase *EI) {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
Payload = reinterpret_cast<ErrorInfoBase*>(
(reinterpret_cast<uintptr_t>(EI) &
~static_cast<uintptr_t>(0x1)) |
(reinterpret_cast<uintptr_t>(Payload) & 0x1));
#else
Payload = EI;
#endif
}
bool getChecked() const {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
#else
return true;
#endif
}
void setChecked(bool V) {
Payload = reinterpret_cast<ErrorInfoBase*>(
(reinterpret_cast<uintptr_t>(Payload) &
~static_cast<uintptr_t>(0x1)) |
(V ? 0 : 1));
}
std::unique_ptr<ErrorInfoBase> takePayload() {
std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
setPtr(nullptr);
setChecked(true);
return Tmp;
}
ErrorInfoBase *Payload;
};
/// Subclass of Error for the sole purpose of identifying the success path in
/// the type system. This allows to catch invalid conversion to Expected<T> at
/// compile time.
class ErrorSuccess : public Error {};
inline ErrorSuccess Error::success() { return ErrorSuccess(); }
/// Make a Error instance representing failure using the given error info
/// type.
template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
return Error(llvm::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
}
/// Base class for user error types. Users should declare their error types
/// like:
///
/// class MyError : public ErrorInfo<MyError> {
/// ....
/// };
///
/// This class provides an implementation of the ErrorInfoBase::kind
/// method, which is used by the Error RTTI system.
template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
class ErrorInfo : public ParentErrT {
public:
bool isA(const void *const ClassID) const override {
return ClassID == classID() || ParentErrT::isA(ClassID);
}
static const void *classID() { return &ThisErrT::ID; }
};
/// Special ErrorInfo subclass representing a list of ErrorInfos.
/// Instances of this class are constructed by joinError.
class ErrorList final : public ErrorInfo<ErrorList> {
// handleErrors needs to be able to iterate the payload list of an
// ErrorList.
template <typename... HandlerTs>
friend Error handleErrors(Error E, HandlerTs &&... Handlers);
// joinErrors is implemented in terms of join.
friend Error joinErrors(Error, Error);
public:
void log(raw_ostream &OS) const override {
OS << "Multiple errors:\n";
for (auto &ErrPayload : Payloads) {
ErrPayload->log(OS);
OS << "\n";
}
}
std::error_code convertToErrorCode() const override;
// Used by ErrorInfo::classID.
static char ID;
private:
ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
std::unique_ptr<ErrorInfoBase> Payload2) {
assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&
"ErrorList constructor payloads should be singleton errors");
Payloads.push_back(std::move(Payload1));
Payloads.push_back(std::move(Payload2));
}
static Error join(Error E1, Error E2) {
if (!E1)
return E2;
if (!E2)
return E1;
if (E1.isA<ErrorList>()) {
auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
if (E2.isA<ErrorList>()) {
auto E2Payload = E2.takePayload();
auto &E2List = static_cast<ErrorList &>(*E2Payload);
for (auto &Payload : E2List.Payloads)
E1List.Payloads.push_back(std::move(Payload));
} else
E1List.Payloads.push_back(E2.takePayload());
return E1;
}
if (E2.isA<ErrorList>()) {
auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
return E2;
}
return Error(std::unique_ptr<ErrorList>(
new ErrorList(E1.takePayload(), E2.takePayload())));
}
std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
};
/// Concatenate errors. The resulting Error is unchecked, and contains the
/// ErrorInfo(s), if any, contained in E1, followed by the
/// ErrorInfo(s), if any, contained in E2.
inline Error joinErrors(Error E1, Error E2) {
return ErrorList::join(std::move(E1), std::move(E2));
}
/// Helper for testing applicability of, and applying, handlers for
/// ErrorInfo types.
template <typename HandlerT>
class ErrorHandlerTraits
: public ErrorHandlerTraits<decltype(
&std::remove_reference<HandlerT>::type::operator())> {};
// Specialization functions of the form 'Error (const ErrT&)'.
template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
public:
static bool appliesTo(const ErrorInfoBase &E) {
return E.template isA<ErrT>();
}
template <typename HandlerT>
static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
assert(appliesTo(*E) && "Applying incorrect handler");
return H(static_cast<ErrT &>(*E));
}
};
// Specialization functions of the form 'void (const ErrT&)'.
template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
public:
static bool appliesTo(const ErrorInfoBase &E) {
return E.template isA<ErrT>();
}
template <typename HandlerT>
static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
assert(appliesTo(*E) && "Applying incorrect handler");
H(static_cast<ErrT &>(*E));
return Error::success();
}
};
/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
template <typename ErrT>
class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
public:
static bool appliesTo(const ErrorInfoBase &E) {
return E.template isA<ErrT>();
}
template <typename HandlerT>
static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
assert(appliesTo(*E) && "Applying incorrect handler");
std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
return H(std::move(SubE));
}
};
/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
template <typename ErrT>
class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
public:
static bool appliesTo(const ErrorInfoBase &E) {
return E.template isA<ErrT>();
}
template <typename HandlerT>
static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
assert(appliesTo(*E) && "Applying incorrect handler");
std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
H(std::move(SubE));
return Error::success();
}
};
// Specialization for member functions of the form 'RetT (const ErrT&)'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
: public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
// Specialization for member functions of the form 'RetT (const ErrT&) const'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
: public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
// Specialization for member functions of the form 'RetT (const ErrT&)'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
: public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
// Specialization for member functions of the form 'RetT (const ErrT&) const'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
: public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
/// Specialization for member functions of the form
/// 'RetT (std::unique_ptr<ErrT>) const'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
: public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
/// Specialization for member functions of the form
/// 'RetT (std::unique_ptr<ErrT>) const'.
template <typename C, typename RetT, typename ErrT>
class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
: public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
return Error(std::move(Payload));
}
template <typename HandlerT, typename... HandlerTs>
Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
HandlerT &&Handler, HandlerTs &&... Handlers) {
if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload))
return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
std::move(Payload));
return handleErrorImpl(std::move(Payload),
std::forward<HandlerTs>(Handlers)...);
}
/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
/// unhandled errors (or Errors returned by handlers) are re-concatenated and
/// returned.
/// Because this function returns an error, its result must also be checked
/// or returned. If you intend to handle all errors use handleAllErrors
/// (which returns void, and will abort() on unhandled errors) instead.
template <typename... HandlerTs>
Error handleErrors(Error E, HandlerTs &&... Hs) {
if (!E)
return Error::success();
std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
if (Payload->isA<ErrorList>()) {
ErrorList &List = static_cast<ErrorList &>(*Payload);
Error R;
for (auto &P : List.Payloads)
R = ErrorList::join(
std::move(R),
handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
return R;
}
return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
}
/// Behaves the same as handleErrors, except that it requires that all
/// errors be handled by the given handlers. If any unhandled error remains
/// after the handlers have run, abort() will be called.
template <typename... HandlerTs>
void handleAllErrors(Error E, HandlerTs &&... Handlers) {
auto F = handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...);
// Cast 'F' to bool to set the 'Checked' flag if it's a success value:
(void)!F;
}
/// Check that E is a non-error, then drop it.
inline void handleAllErrors(Error E) {
// Cast 'E' to a bool to set the 'Checked' flag if it's a success value:
(void)!E;
}
/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
/// will be printed before the first one is logged. A newline will be printed
/// after each error.
///
/// This is useful in the base level of your program to allow clean termination
/// (allowing clean deallocation of resources, etc.), while reporting error
/// information to the user.
void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner);
/// Write all error messages (if any) in E to a string. The newline character
/// is used to separate error messages.
inline std::string toString(Error E) {
SmallVector<std::string, 2> Errors;
handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) {
Errors.push_back(EI.message());
});
return join(Errors.begin(), Errors.end(), "\n");
}
/// Consume a Error without doing anything. This method should be used
/// only where an error can be considered a reasonable and expected return
/// value.
///
/// Uses of this method are potentially indicative of design problems: If it's
/// legitimate to do nothing while processing an "error", the error-producer
/// might be more clearly refactored to return an Optional<T>.
inline void consumeError(Error Err) {
handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
}
/// Helper for Errors used as out-parameters.
///
/// This helper is for use with the Error-as-out-parameter idiom, where an error
/// is passed to a function or method by reference, rather than being returned.
/// In such cases it is helpful to set the checked bit on entry to the function
/// so that the error can be written to (unchecked Errors abort on assignment)
/// and clear the checked bit on exit so that clients cannot accidentally forget
/// to check the result. This helper performs these actions automatically using
/// RAII:
///
/// @code{.cpp}
/// Result foo(Error &Err) {
/// ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
/// // <body of foo>
/// // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
/// }
/// @endcode
///
/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
/// used with optional Errors (Error pointers that are allowed to be null). If
/// ErrorAsOutParameter took an Error reference, an instance would have to be
/// created inside every condition that verified that Error was non-null. By
/// taking an Error pointer we can just create one instance at the top of the
/// function.
class ErrorAsOutParameter {
public:
ErrorAsOutParameter(Error *Err) : Err(Err) {
// Raise the checked bit if Err is success.
if (Err)
(void)!!*Err;
}
~ErrorAsOutParameter() {
// Clear the checked bit.
if (Err && !*Err)
*Err = Error::success();
}
private:
Error *Err;
};
/// Tagged union holding either a T or a Error.
///
/// This class parallels ErrorOr, but replaces error_code with Error. Since
/// Error cannot be copied, this class replaces getError() with
/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
/// error class type.
template <class T> class LLVM_NODISCARD Expected {
template <class OtherT> friend class Expected;
static const bool isRef = std::is_reference<T>::value;
typedef ReferenceStorage<typename std::remove_reference<T>::type> wrap;
typedef std::unique_ptr<ErrorInfoBase> error_type;
public:
typedef typename std::conditional<isRef, wrap, T>::type storage_type;
typedef T value_type;
private:
typedef typename std::remove_reference<T>::type &reference;
typedef const typename std::remove_reference<T>::type &const_reference;
typedef typename std::remove_reference<T>::type *pointer;
typedef const typename std::remove_reference<T>::type *const_pointer;
public:
/// Create an Expected<T> error value from the given Error.
Expected(Error Err)
: HasError(true)
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
// Expected is unchecked upon construction in Debug builds.
, Unchecked(true)
#endif
{
assert(Err && "Cannot create Expected<T> from Error success value.");
new (getErrorStorage()) error_type(Err.takePayload());
}
/// Forbid to convert from Error::success() implicitly, this avoids having
/// Expected<T> foo() { return Error::success(); } which compiles otherwise
/// but triggers the assertion above.
Expected(ErrorSuccess) = delete;
/// Create an Expected<T> success value from the given OtherT value, which
/// must be convertible to T.
template <typename OtherT>
Expected(OtherT &&Val,
typename std::enable_if<std::is_convertible<OtherT, T>::value>::type
* = nullptr)
: HasError(false)
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
// Expected is unchecked upon construction in Debug builds.
, Unchecked(true)
#endif
{
new (getStorage()) storage_type(std::forward<OtherT>(Val));
}
/// Move construct an Expected<T> value.
Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
/// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
/// must be convertible to T.
template <class OtherT>
Expected(Expected<OtherT> &&Other,
typename std::enable_if<std::is_convertible<OtherT, T>::value>::type
* = nullptr) {
moveConstruct(std::move(Other));
}
/// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
/// isn't convertible to T.
template <class OtherT>
explicit Expected(
Expected<OtherT> &&Other,
typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * =
nullptr) {
moveConstruct(std::move(Other));
}
/// Move-assign from another Expected<T>.
Expected &operator=(Expected &&Other) {
moveAssign(std::move(Other));
return *this;
}
/// Destroy an Expected<T>.
~Expected() {
assertIsChecked();
if (!HasError)
getStorage()->~storage_type();
else
getErrorStorage()->~error_type();
}
/// \brief Return false if there is an error.
explicit operator bool() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
Unchecked = HasError;
#endif
return !HasError;
}
/// \brief Returns a reference to the stored T value.
reference get() {
assertIsChecked();
return *getStorage();
}
/// \brief Returns a const reference to the stored T value.
const_reference get() const {
assertIsChecked();
return const_cast<Expected<T> *>(this)->get();
}
/// \brief Check that this Expected<T> is an error of type ErrT.
template <typename ErrT> bool errorIsA() const {
return HasError && getErrorStorage()->template isA<ErrT>();
}
/// \brief Take ownership of the stored error.
/// After calling this the Expected<T> is in an indeterminate state that can
/// only be safely destructed. No further calls (beside the destructor) should
/// be made on the Expected<T> vaule.
Error takeError() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
Unchecked = false;
#endif
return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
}
/// \brief Returns a pointer to the stored T value.
pointer operator->() {
assertIsChecked();
return toPointer(getStorage());
}
/// \brief Returns a const pointer to the stored T value.
const_pointer operator->() const {
assertIsChecked();
return toPointer(getStorage());
}
/// \brief Returns a reference to the stored T value.
reference operator*() {
assertIsChecked();
return *getStorage();
}
/// \brief Returns a const reference to the stored T value.
const_reference operator*() const {
assertIsChecked();
return *getStorage();
}
private:
template <class T1>
static bool compareThisIfSameType(const T1 &a, const T1 &b) {
return &a == &b;
}
template <class T1, class T2>
static bool compareThisIfSameType(const T1 &a, const T2 &b) {
return false;
}
template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
HasError = Other.HasError;
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
Unchecked = true;
Other.Unchecked = false;
#endif
if (!HasError)
new (getStorage()) storage_type(std::move(*Other.getStorage()));
else
new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
}
template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
assertIsChecked();
if (compareThisIfSameType(*this, Other))
return;
this->~Expected();
new (this) Expected(std::move(Other));
}
pointer toPointer(pointer Val) { return Val; }
const_pointer toPointer(const_pointer Val) const { return Val; }
pointer toPointer(wrap *Val) { return &Val->get(); }
const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
storage_type *getStorage() {
assert(!HasError && "Cannot get value when an error exists!");
return reinterpret_cast<storage_type *>(TStorage.buffer);
}
const storage_type *getStorage() const {
assert(!HasError && "Cannot get value when an error exists!");
return reinterpret_cast<const storage_type *>(TStorage.buffer);
}
error_type *getErrorStorage() {
assert(HasError && "Cannot get error when a value exists!");
return reinterpret_cast<error_type *>(ErrorStorage.buffer);
}
void assertIsChecked() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
if (Unchecked) {
dbgs() << "Expected<T> must be checked before access or destruction.\n";
if (HasError) {
dbgs() << "Unchecked Expected<T> contained error:\n";
(*getErrorStorage())->log(dbgs());
} else
dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
"values in success mode must still be checked prior to being "
"destroyed).\n";
abort();
}
#endif
}
union {
AlignedCharArrayUnion<storage_type> TStorage;
AlignedCharArrayUnion<error_type> ErrorStorage;
};
bool HasError : 1;
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
bool Unchecked : 1;
#endif
};
/// This class wraps a std::error_code in a Error.
///
/// This is useful if you're writing an interface that returns a Error
/// (or Expected) and you want to call code that still returns
/// std::error_codes.
class ECError : public ErrorInfo<ECError> {
friend Error errorCodeToError(std::error_code);
public:
void setErrorCode(std::error_code EC) { this->EC = EC; }
std::error_code convertToErrorCode() const override { return EC; }
void log(raw_ostream &OS) const override { OS << EC.message(); }
// Used by ErrorInfo::classID.
static char ID;
protected:
ECError() = default;
ECError(std::error_code EC) : EC(EC) {}
std::error_code EC;
};
/// The value returned by this function can be returned from convertToErrorCode
/// for Error values where no sensible translation to std::error_code exists.
/// It should only be used in this situation, and should never be used where a
/// sensible conversion to std::error_code is available, as attempts to convert
/// to/from this error will result in a fatal error. (i.e. it is a programmatic
///error to try to convert such a value).
std::error_code inconvertibleErrorCode();
/// Helper for converting an std::error_code to a Error.
Error errorCodeToError(std::error_code EC);
/// Helper for converting an ECError to a std::error_code.
///
/// This method requires that Err be Error() or an ECError, otherwise it
/// will trigger a call to abort().
std::error_code errorToErrorCode(Error Err);
/// Convert an ErrorOr<T> to an Expected<T>.
template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
if (auto EC = EO.getError())
return errorCodeToError(EC);
return std::move(*EO);
}
/// Convert an Expected<T> to an ErrorOr<T>.
template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
if (auto Err = E.takeError())
return errorToErrorCode(std::move(Err));
return std::move(*E);
}
/// This class wraps a string in an Error.
///
/// StringError is useful in cases where the client is not expected to be able
/// to consume the specific error message programmatically (for example, if the
/// error message is to be presented to the user).
class StringError : public ErrorInfo<StringError> {
public:
static char ID;
StringError(const Twine &S, std::error_code EC);
void log(raw_ostream &OS) const override;
std::error_code convertToErrorCode() const override;
private:
std::string Msg;
std::error_code EC;
};
/// Helper for check-and-exit error handling.
///
/// For tool use only. NOT FOR USE IN LIBRARY CODE.
///
class ExitOnError {
public:
/// Create an error on exit helper.
ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
: Banner(std::move(Banner)),
GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
/// Set the banner string for any errors caught by operator().
void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
/// Set the exit-code mapper function.
void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
this->GetExitCode = std::move(GetExitCode);
}
/// Check Err. If it's in a failure state log the error(s) and exit.
void operator()(Error Err) const { checkError(std::move(Err)); }
/// Check E. If it's in a success state then return the contained value. If
/// it's in a failure state log the error(s) and exit.
template <typename T> T operator()(Expected<T> &&E) const {
checkError(E.takeError());
return std::move(*E);
}
/// Check E. If it's in a success state then return the contained reference. If
/// it's in a failure state log the error(s) and exit.
template <typename T> T& operator()(Expected<T&> &&E) const {
checkError(E.takeError());
return *E;
}
private:
void checkError(Error Err) const {
if (Err) {
int ExitCode = GetExitCode(Err);
logAllUnhandledErrors(std::move(Err), errs(), Banner);
exit(ExitCode);
}
}
std::string Banner;
std::function<int(const Error &)> GetExitCode;
};
/// Report a serious error, calling any installed error handler. See
/// ErrorHandling.h.
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err,
bool gen_crash_diag = true);
} // end namespace llvm
#endif // LLVM_SUPPORT_ERROR_H