[Support] Move StringExtras.h include from Error.h to Error.cpp (part 4)

[IncludeGuardian]

Summary

1st commit
[lldb] Add missing StringExtras.h includes

In preparation for removing the #include "llvm/ADT/StringExtras.h"
from the header to source file of llvm/Support/Error.h, first add in
all the missing includes that were previously included transitively
through this header.

This is fixing all files missed in b0abd4893fa1, 39d8e6e22cd1, and
a11efd49266f.

---

2nd commit
[Support] Move StringExtras.h include from Error.h to Error.cpp

Move the implementation of the toString function from
llvm/Support/Error.h to the source file, which allows us to move
#include "llvm/ADT/StringExtras.h" to the source file as well.

As Error.h is present in a large number of translation units this
means we are unnecessarily bringing in the contents of
StringExtras.h - itself a large file with lots of includes - and
slowing down compilation.

Also move the #include "llvm/ADT/SmallVector.h" directive to the
source file as it's no longer needed, but this does not give as much of
a benefit.

This reduces the total number of preprocessing tokens across the LLVM
source files in lib from (roughly) 1,920,413,050 to 1,903,629,230 - a
reduction of ~0.87%. This should result in a small improvement in
compilation time.

[IncludeGuardian]

After the previous attempt, I believe only LLDB was failing to compile. These are the necessary changes needed to fix all of LLDB locally on main.

lldb/source/Core/SourceLocationSpec.cpp

 //===-- SourceLocationSpec.cpp --------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Core/SourceLocationSpec.h"
-#include "lldb/Utility/StreamString.h"
+#include "lldb/Utility/StreamString.h"
+#include "llvm/ADT/StringExtras.h"
 #include <optional>
 
 using namespace lldb;
 using namespace lldb_private;
 
 SourceLocationSpec::SourceLocationSpec(FileSpec file_spec, uint32_t line,
                                        std::optional<uint16_t> column,
                                        bool check_inlines, bool exact_match)

lldb/source/Plugins/Process/Linux/Procfs.cpp

 //===-- Procfs.cpp --------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Procfs.h"
-#include "lldb/Host/linux/Support.h"
+#include "lldb/Host/linux/Support.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Threading.h"
 #include <optional>
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace process_linux;

lldb/source/Plugins/SymbolFile/NativePDB/CompileUnitIndex.h

 //===-- CompileUnitIndex.h --------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLDB_SOURCE_PLUGINS_SYMBOLFILE_NATIVEPDB_COMPILEUNITINDEX_H
 #define LLDB_SOURCE_PLUGINS_SYMBOLFILE_NATIVEPDB_COMPILEUNITINDEX_H
 
 #include "lldb/Utility/RangeMap.h"
 #include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/IntervalMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/IntervalMap.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/DebugInfo/CodeView/DebugInlineeLinesSubsection.h"
 #include "llvm/DebugInfo/CodeView/StringsAndChecksums.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/PDB/Native/DbiModuleDescriptor.h"
 #include "llvm/DebugInfo/PDB/Native/ModuleDebugStream.h"
 #include "llvm/DebugInfo/PDB/PDBTypes.h"
 

lldb/source/Utility/DataExtractor.cpp

 #include "lldb/lldb-types.h"
 
 #include "lldb/Utility/DataBuffer.h"
 #include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Stream.h"
 #include "lldb/Utility/StreamString.h"
-#include "lldb/Utility/UUID.h"
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/SmallVector.h"
+#include "lldb/Utility/UUID.h"
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/MathExtras.h"
 
 #include <algorithm>
 #include <array>
 #include <cassert>
 #include <cstdint>

lldb/source/Utility/Event.cpp

 //===-- Event.cpp ---------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Utility/Event.h"
 
 #include "lldb/Utility/Broadcaster.h"
 #include "lldb/Utility/DataExtractor.h"
 #include "lldb/Utility/Endian.h"
 #include "lldb/Utility/Stream.h"
-#include "lldb/Utility/StreamString.h"
-#include "lldb/lldb-enumerations.h"
+#include "lldb/Utility/StreamString.h"
+#include "lldb/lldb-enumerations.h"
+
+#include "llvm/ADT/StringExtras.h"
 
 #include <algorithm>
 
 #include <cctype>
 
 using namespace lldb;
 using namespace lldb_private;
 

lldb/source/Utility/FileSpec.cpp

 //===-- FileSpec.cpp ------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Utility/FileSpec.h"
 #include "lldb/Utility/RegularExpression.h"
 #include "lldb/Utility/Stream.h"
 
-#include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/Triple.h"
 

lldb/source/Utility/Scalar.cpp

 #include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/DataExtractor.h"
 #include "lldb/Utility/Endian.h"
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/Stream.h"
 #include "lldb/Utility/StreamString.h"
 #include "lldb/lldb-types.h"
 #include "llvm/ADT/APSInt.h"
-#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 
 #include <cinttypes>
 #include <cstdio>
 
 using namespace lldb;
 using namespace lldb_private;
 
 using llvm::APFloat;

lldb/source/Utility/StructuredData.cpp

 //===-- StructuredData.cpp ------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Utility/StructuredData.h"
 #include "lldb/Utility/FileSpec.h"
-#include "lldb/Utility/Status.h"
+#include "lldb/Utility/Status.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <cerrno>
 #include <cinttypes>
 #include <cstdlib>
 
 using namespace lldb_private;
 using namespace llvm;
 

llvm/include/llvm/Support/Error.h

 //===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines an API used to report recoverable errors.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_SUPPORT_ERROR_H
 #define LLVM_SUPPORT_ERROR_H
-
-#include "llvm-c/Error.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringExtras.h"
+
+#include "llvm-c/Error.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/ErrorHandling.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/Format.h"
static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
     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>)'.
+
+// 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::*)(std::unique_ptr<ErrT>)>
-    : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<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'.
+/// 'RetT (std::unique_ptr<ErrT>)'.
 template <typename C, typename RetT, typename ErrT>
-class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
+class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
     : 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 by contract all errors
-/// *must* be handled by the given handlers (i.e. there must be no remaining
-/// errors after running the handlers, or llvm_unreachable is called).
-template <typename... HandlerTs>
-void handleAllErrors(Error E, HandlerTs &&... Handlers) {
-  cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
-}
-
-/// Check that E is a non-error, then drop it.
-/// If E is an error, llvm_unreachable will be called.
-inline void handleAllErrors(Error E) {
-  cantFail(std::move(E));
+/// 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 by contract all errors
+/// *must* be handled by the given handlers (i.e. there must be no remaining
+/// errors after running the handlers, or llvm_unreachable is called).
+template <typename... HandlerTs>
+void handleAllErrors(Error E, HandlerTs &&... Handlers) {
+  cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
 }
 
-/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
-///
-/// If the incoming value is a success value it is returned unmodified. If it
-/// is a failure value then it the contained error is passed to handleErrors.
-/// If handleErrors is able to handle the error then the RecoveryPath functor
-/// is called to supply the final result. If handleErrors is not able to
-/// handle all errors then the unhandled errors are returned.
+/// Check that E is a non-error, then drop it.
+/// If E is an error, llvm_unreachable will be called.
+inline void handleAllErrors(Error E) {
+  cantFail(std::move(E));
+}
+
+/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
 ///
-/// This utility enables the follow pattern:
-///
-///   @code{.cpp}
-///   enum FooStrategy { Aggressive, Conservative };
-///   Expected<Foo> foo(FooStrategy S);
+/// If the incoming value is a success value it is returned unmodified. If it
+/// is a failure value then it the contained error is passed to handleErrors.
+/// If handleErrors is able to handle the error then the RecoveryPath functor
+/// is called to supply the final result. If handleErrors is not able to
+/// handle all errors then the unhandled errors are returned.
 ///
-///   auto ResultOrErr =
-///     handleExpected(
-///       foo(Aggressive),
-///       []() { return foo(Conservative); },
-///       [](AggressiveStrategyError&) {
-///         // Implicitly conusme this - we'll recover by using a conservative
-///         // strategy.
-///       });
-///
-///   @endcode
-template <typename T, typename RecoveryFtor, typename... HandlerTs>
-Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
-                           HandlerTs &&... Handlers) {
-  if (ValOrErr)
-    return ValOrErr;
-
-  if (auto Err = handleErrors(ValOrErr.takeError(),
-                              std::forward<HandlerTs>(Handlers)...))
-    return std::move(Err);
-
-  return RecoveryPath();
-}
-
-/// 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 function is compatible with the helpers from Support/WithColor.h. You
-/// can pass any of them as the OS. Please consider using them instead of
-/// including 'error: ' in the ErrorBanner.
-///
-/// 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");
-}
+/// This utility enables the follow pattern:
+///
+///   @code{.cpp}
+///   enum FooStrategy { Aggressive, Conservative };
+///   Expected<Foo> foo(FooStrategy S);
+///
+///   auto ResultOrErr =
+///     handleExpected(
+///       foo(Aggressive),
+///       []() { return foo(Conservative); },
+///       [](AggressiveStrategyError&) {
+///         // Implicitly conusme this - we'll recover by using a conservative
+///         // strategy.
+///       });
+///
+///   @endcode
+template <typename T, typename RecoveryFtor, typename... HandlerTs>
+Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
+                           HandlerTs &&... Handlers) {
+  if (ValOrErr)
+    return ValOrErr;
+
+  if (auto Err = handleErrors(ValOrErr.takeError(),
+                              std::forward<HandlerTs>(Handlers)...))
+    return std::move(Err);
+
+  return RecoveryPath();
+}
+
+/// 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 function is compatible with the helpers from Support/WithColor.h. You
+/// can pass any of them as the OS. Please consider using them instead of
+/// including 'error: ' in the ErrorBanner.
+///
+/// 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.
+std::string toString(Error E);
 
 /// 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 std::optional<T>.

llvm/lib/Support/Error.cpp

 //===----- lib/Support/Error.cpp - Error and associated utilities ---------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Support/Error.h"
+#include "llvm/Support/Error.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <system_error>
 
 using namespace llvm;
 
 namespace {
 

 namespace llvm {
 
 void ErrorInfoBase::anchor() {}
 char ErrorInfoBase::ID = 0;
 char ErrorList::ID = 0;
 void ECError::anchor() {}
 char ECError::ID = 0;
 char StringError::ID = 0;
-char FileError::ID = 0;
-
-void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner) {
-  if (!E)
-    return;
-  OS << ErrorBanner;
-  handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
-    EI.log(OS);
-    OS << "\n";
+char FileError::ID = 0;
+
+void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner) {
+  if (!E)
+    return;
+  OS << ErrorBanner;
+  handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
+    EI.log(OS);
+    OS << "\n";
+  });
+}
+
+/// Write all error messages (if any) in E to a string. The newline character
+/// is used to separate error messages.
+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");
+}
 
 std::error_code ErrorList::convertToErrorCode() const {
   return std::error_code(static_cast<int>(ErrorErrorCode::MultipleErrors),
                          getErrorErrorCat());
 }
 
 std::error_code inconvertibleErrorCode() {
   return std::error_code(static_cast<int>(ErrorErrorCode::InconvertibleError),

 Error createStringError(std::error_code EC, char const *Msg) {
   return make_error<StringError>(Msg, EC);
 }
 
 void report_fatal_error(Error Err, bool GenCrashDiag) {
   assert(Err && "report_fatal_error called with success value");
   std::string ErrMsg;
   {
     raw_string_ostream ErrStream(ErrMsg);
   }
   report_fatal_error(Twine(ErrMsg), GenCrashDiag);
 }
 
 } // end namespace llvm
 
 LLVMErrorTypeId LLVMGetErrorTypeId(LLVMErrorRef Err) {
   return reinterpret_cast<ErrorInfoBase *>(Err)->dynamicClassID();