/usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/llvm/include/llvm/Bitstream/BitstreamReader.h

Bug Summary

File:	src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/llvm/include/llvm/Bitstream/BitstreamReader.h
Warning:	line 221, column 39 The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'llvm::SimpleBitstreamCursor::word_t'

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name GlobalModuleIndex.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangSerialization/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/clang/include -I /usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libclangSerialization/../include -I /usr/src/gnu/usr.bin/clang/libclangSerialization/obj -I /usr/src/gnu/usr.bin/clang/libclangSerialization/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangSerialization/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/clang/lib/Serialization/GlobalModuleIndex.cpp

/usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/clang/lib/Serialization/GlobalModuleIndex.cpp

→

1//===--- GlobalModuleIndex.cpp - Global Module Index ------------*- 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 implements the GlobalModuleIndex class.
10//
11//===----------------------------------------------------------------------===//

13#include "clang/Serialization/GlobalModuleIndex.h"
14#include "ASTReaderInternals.h"
15#include "clang/Basic/FileManager.h"
16#include "clang/Lex/HeaderSearch.h"
17#include "clang/Serialization/ASTBitCodes.h"
18#include "clang/Serialization/ModuleFile.h"
19#include "clang/Serialization/PCHContainerOperations.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/MapVector.h"
22#include "llvm/ADT/SmallString.h"
23#include "llvm/ADT/StringRef.h"
24#include "llvm/Bitstream/BitstreamReader.h"
25#include "llvm/Bitstream/BitstreamWriter.h"
26#include "llvm/Support/DJB.h"
27#include "llvm/Support/FileSystem.h"
28#include "llvm/Support/FileUtilities.h"
29#include "llvm/Support/LockFileManager.h"
30#include "llvm/Support/MemoryBuffer.h"
31#include "llvm/Support/OnDiskHashTable.h"
32#include "llvm/Support/Path.h"
33#include "llvm/Support/TimeProfiler.h"
34#include <cstdio>
35using namespace clang;
36using namespace serialization;

38//----------------------------------------------------------------------------//
39// Shared constants
40//----------------------------------------------------------------------------//
41namespace {
enum {
  /// The block containing the index.
  GLOBAL_INDEX_BLOCK_ID = llvm::bitc::FIRST_APPLICATION_BLOCKID
};

/// Describes the record types in the index.
enum IndexRecordTypes {
  /// Contains version information and potentially other metadata,
  /// used to determine if we can read this global index file.
  INDEX_METADATA,
  /// Describes a module, including its file name and dependencies.
  MODULE,
  /// The index for identifiers.
  IDENTIFIER_INDEX
};
57}

59/// The name of the global index file.
60static const char * const IndexFileName = "modules.idx";

62/// The global index file version.
63static const unsigned CurrentVersion = 1;

65//----------------------------------------------------------------------------//
66// Global module index reader.
67//----------------------------------------------------------------------------//

69namespace {

71/// Trait used to read the identifier index from the on-disk hash
72/// table.
73class IdentifierIndexReaderTrait {
74public:
typedef StringRef external_key_type;
typedef StringRef internal_key_type;
typedef SmallVector<unsigned, 2> data_type;
typedef unsigned hash_value_type;
typedef unsigned offset_type;

static bool EqualKey(const internal_key_type& a, const internal_key_type& b) {
  return a == b;
}

static hash_value_type ComputeHash(const internal_key_type& a) {
  return llvm::djbHash(a);
}

static std::pair<unsigned, unsigned>
ReadKeyDataLength(const unsigned char*& d) {
  using namespace llvm::support;
  unsigned KeyLen = endian::readNext<uint16_t, little, unaligned>(d);
  unsigned DataLen = endian::readNext<uint16_t, little, unaligned>(d);
  return std::make_pair(KeyLen, DataLen);
}

static const internal_key_type&
GetInternalKey(const external_key_type& x) { return x; }

static const external_key_type&
GetExternalKey(const internal_key_type& x) { return x; }

static internal_key_type ReadKey(const unsigned char* d, unsigned n) {
  return StringRef((const char *)d, n);
}

static data_type ReadData(const internal_key_type& k,
                          const unsigned char* d,
                          unsigned DataLen) {
  using namespace llvm::support;

  data_type Result;
  while (DataLen > 0) {
    unsigned ID = endian::readNext<uint32_t, little, unaligned>(d);
    Result.push_back(ID);
    DataLen -= 4;
  }

  return Result;
}
121};

123typedef llvm::OnDiskIterableChainedHashTable<IdentifierIndexReaderTrait>
  IdentifierIndexTable;

126}

128GlobalModuleIndex::GlobalModuleIndex(
  std::unique_ptr<llvm::MemoryBuffer> IndexBuffer,
  llvm::BitstreamCursor Cursor)
  : Buffer(std::move(IndexBuffer)), IdentifierIndex(), NumIdentifierLookups(),
    NumIdentifierLookupHits() {
auto Fail = [&](llvm::Error &&Err) {
  report_fatal_error("Module index '" + Buffer->getBufferIdentifier() +
                     "' failed: " + toString(std::move(Err)));
};

llvm::TimeTraceScope TimeScope("Module LoadIndex");
// Read the global index.
bool InGlobalIndexBlock = false;
bool Done = false;
while (!Done) {
  llvm::BitstreamEntry Entry;
  if (Expected<llvm::BitstreamEntry> Res = Cursor.advance())
    Entry = Res.get();
  else
    Fail(Res.takeError());

  switch (Entry.Kind) {
  case llvm::BitstreamEntry::Error:
    return;

  case llvm::BitstreamEntry::EndBlock:
    if (InGlobalIndexBlock) {
      InGlobalIndexBlock = false;
      Done = true;
      continue;
    }
    return;


  case llvm::BitstreamEntry::Record:
    // Entries in the global index block are handled below.
    if (InGlobalIndexBlock)
      break;

    return;

  case llvm::BitstreamEntry::SubBlock:
    if (!InGlobalIndexBlock && Entry.ID == GLOBAL_INDEX_BLOCK_ID) {
      if (llvm::Error Err = Cursor.EnterSubBlock(GLOBAL_INDEX_BLOCK_ID))
        Fail(std::move(Err));
      InGlobalIndexBlock = true;
    } else if (llvm::Error Err = Cursor.SkipBlock())
      Fail(std::move(Err));
    continue;
  }

  SmallVector<uint64_t, 64> Record;
  StringRef Blob;
  Expected<unsigned> MaybeIndexRecord =
      Cursor.readRecord(Entry.ID, Record, &Blob);
  if (!MaybeIndexRecord)
    Fail(MaybeIndexRecord.takeError());
  IndexRecordTypes IndexRecord =
      static_cast<IndexRecordTypes>(MaybeIndexRecord.get());
  switch (IndexRecord) {
  case INDEX_METADATA:
    // Make sure that the version matches.
    if (Record.size() < 1 || Record[0] != CurrentVersion)
      return;
    break;

  case MODULE: {
    unsigned Idx = 0;
    unsigned ID = Record[Idx++];

    // Make room for this module's information.
    if (ID == Modules.size())
      Modules.push_back(ModuleInfo());
    else
      Modules.resize(ID + 1);

    // Size/modification time for this module file at the time the
    // global index was built.
    Modules[ID].Size = Record[Idx++];
    Modules[ID].ModTime = Record[Idx++];

    // File name.
    unsigned NameLen = Record[Idx++];
    Modules[ID].FileName.assign(Record.begin() + Idx,
                                Record.begin() + Idx + NameLen);
    Idx += NameLen;

    // Dependencies
    unsigned NumDeps = Record[Idx++];
    Modules[ID].Dependencies.insert(Modules[ID].Dependencies.end(),
                                    Record.begin() + Idx,
                                    Record.begin() + Idx + NumDeps);
    Idx += NumDeps;

    // Make sure we're at the end of the record.
    assert(Idx == Record.size() && "More module info?")((void)0);

    // Record this module as an unresolved module.
    // FIXME: this doesn't work correctly for module names containing path
    // separators.
    StringRef ModuleName = llvm::sys::path::stem(Modules[ID].FileName);
    // Remove the -<hash of ModuleMapPath>
    ModuleName = ModuleName.rsplit('-').first;
    UnresolvedModules[ModuleName] = ID;
    break;
  }

  case IDENTIFIER_INDEX:
    // Wire up the identifier index.
    if (Record[0]) {
      IdentifierIndex = IdentifierIndexTable::Create(
          (const unsigned char *)Blob.data() + Record[0],
          (const unsigned char *)Blob.data() + sizeof(uint32_t),
          (const unsigned char *)Blob.data(), IdentifierIndexReaderTrait());
    }
    break;
  }
}
246}

248GlobalModuleIndex::~GlobalModuleIndex() {
delete static_cast<IdentifierIndexTable *>(IdentifierIndex);
250}

252std::pair<GlobalModuleIndex *, llvm::Error>
253GlobalModuleIndex::readIndex(StringRef Path) {
// Load the index file, if it's there.
llvm::SmallString<128> IndexPath;
IndexPath += Path;
llvm::sys::path::append(IndexPath, IndexFileName);

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> BufferOrErr =
    llvm::MemoryBuffer::getFile(IndexPath.c_str());
if (!BufferOrErr)
  return std::make_pair(nullptr,
                        llvm::errorCodeToError(BufferOrErr.getError()));
std::unique_ptr<llvm::MemoryBuffer> Buffer = std::move(BufferOrErr.get());

/// The main bitstream cursor for the main block.
llvm::BitstreamCursor Cursor(*Buffer);

// Sniff for the signature.
for (unsigned char C : {'B', 'C', 'G', 'I'}) {
  if (Expected<llvm::SimpleBitstreamCursor::word_t> Res = Cursor.Read(8)) {
    if (Res.get() != C)
      return std::make_pair(
          nullptr, llvm::createStringError(std::errc::illegal_byte_sequence,
                                           "expected signature BCGI"));
  } else
    return std::make_pair(nullptr, Res.takeError());
}

return std::make_pair(new GlobalModuleIndex(std::move(Buffer), Cursor),
                      llvm::Error::success());
282}

284void
285GlobalModuleIndex::getKnownModules(SmallVectorImpl<ModuleFile *> &ModuleFiles) {
ModuleFiles.clear();
for (unsigned I = 0, N = Modules.size(); I != N; ++I) {
  if (ModuleFile *MF = Modules[I].File)
    ModuleFiles.push_back(MF);
}
291}

293void GlobalModuleIndex::getModuleDependencies(
     ModuleFile *File,
     SmallVectorImpl<ModuleFile *> &Dependencies) {
// Look for information about this module file.
llvm::DenseMap<ModuleFile *, unsigned>::iterator Known
  = ModulesByFile.find(File);
if (Known == ModulesByFile.end())
  return;

// Record dependencies.
Dependencies.clear();
ArrayRef<unsigned> StoredDependencies = Modules[Known->second].Dependencies;
for (unsigned I = 0, N = StoredDependencies.size(); I != N; ++I) {
  if (ModuleFile *MF = Modules[I].File)
    Dependencies.push_back(MF);
}
309}

311bool GlobalModuleIndex::lookupIdentifier(StringRef Name, HitSet &Hits) {
Hits.clear();

// If there's no identifier index, there is nothing we can do.
if (!IdentifierIndex)
  return false;

// Look into the identifier index.
++NumIdentifierLookups;
IdentifierIndexTable &Table
  = *static_cast<IdentifierIndexTable *>(IdentifierIndex);
IdentifierIndexTable::iterator Known = Table.find(Name);
if (Known == Table.end()) {
  return false;
}

SmallVector<unsigned, 2> ModuleIDs = *Known;
for (unsigned I = 0, N = ModuleIDs.size(); I != N; ++I) {
  if (ModuleFile *MF = Modules[ModuleIDs[I]].File)
    Hits.insert(MF);
}

++NumIdentifierLookupHits;
return true;
335}

337bool GlobalModuleIndex::loadedModuleFile(ModuleFile *File) {
// Look for the module in the global module index based on the module name.
StringRef Name = File->ModuleName;
llvm::StringMap<unsigned>::iterator Known = UnresolvedModules.find(Name);
if (Known == UnresolvedModules.end()) {
  return true;
}

// Rectify this module with the global module index.
ModuleInfo &Info = Modules[Known->second];

//  If the size and modification time match what we expected, record this
// module file.
bool Failed = true;
if (File->File->getSize() == Info.Size &&
    File->File->getModificationTime() == Info.ModTime) {
  Info.File = File;
  ModulesByFile[File] = Known->second;

  Failed = false;
}

// One way or another, we have resolved this module file.
UnresolvedModules.erase(Known);
return Failed;
362}

364void GlobalModuleIndex::printStats() {
std::fprintf(stderr(&__sF[2]), "*** Global Module Index Statistics:\n");
if (NumIdentifierLookups) {
  fprintf(stderr(&__sF[2]), "  %u / %u identifier lookups succeeded (%f%%)\n",
          NumIdentifierLookupHits, NumIdentifierLookups,
          (double)NumIdentifierLookupHits*100.0/NumIdentifierLookups);
}
std::fprintf(stderr(&__sF[2]), "\n");
372}

374LLVM_DUMP_METHOD__attribute__((noinline)) void GlobalModuleIndex::dump() {
llvm::errs() << "*** Global Module Index Dump:\n";
llvm::errs() << "Module files:\n";
for (auto &MI : Modules) {
  llvm::errs() << "** " << MI.FileName << "\n";
  if (MI.File)
    MI.File->dump();
  else
    llvm::errs() << "\n";
}
llvm::errs() << "\n";
385}

387//----------------------------------------------------------------------------//
388// Global module index writer.
389//----------------------------------------------------------------------------//

391namespace {
/// Provides information about a specific module file.
struct ModuleFileInfo {
  /// The numberic ID for this module file.
  unsigned ID;

  /// The set of modules on which this module depends. Each entry is
  /// a module ID.
  SmallVector<unsigned, 4> Dependencies;
  ASTFileSignature Signature;
};

struct ImportedModuleFileInfo {
  off_t StoredSize;
  time_t StoredModTime;
  ASTFileSignature StoredSignature;
  ImportedModuleFileInfo(off_t Size, time_t ModTime, ASTFileSignature Sig)
      : StoredSize(Size), StoredModTime(ModTime), StoredSignature(Sig) {}
};

/// Builder that generates the global module index file.
class GlobalModuleIndexBuilder {
  FileManager &FileMgr;
  const PCHContainerReader &PCHContainerRdr;

  /// Mapping from files to module file information.
  typedef llvm::MapVector<const FileEntry *, ModuleFileInfo> ModuleFilesMap;

  /// Information about each of the known module files.
  ModuleFilesMap ModuleFiles;

  /// Mapping from the imported module file to the imported
  /// information.
  typedef std::multimap<const FileEntry *, ImportedModuleFileInfo>
      ImportedModuleFilesMap;

  /// Information about each importing of a module file.
  ImportedModuleFilesMap ImportedModuleFiles;

  /// Mapping from identifiers to the list of module file IDs that
  /// consider this identifier to be interesting.
  typedef llvm::StringMap<SmallVector<unsigned, 2> > InterestingIdentifierMap;

  /// A mapping from all interesting identifiers to the set of module
  /// files in which those identifiers are considered interesting.
  InterestingIdentifierMap InterestingIdentifiers;

  /// Write the block-info block for the global module index file.
  void emitBlockInfoBlock(llvm::BitstreamWriter &Stream);

  /// Retrieve the module file information for the given file.
  ModuleFileInfo &getModuleFileInfo(const FileEntry *File) {
    llvm::MapVector<const FileEntry *, ModuleFileInfo>::iterator Known
      = ModuleFiles.find(File);
    if (Known != ModuleFiles.end())
      return Known->second;

    unsigned NewID = ModuleFiles.size();
    ModuleFileInfo &Info = ModuleFiles[File];
    Info.ID = NewID;
    return Info;
  }

public:
  explicit GlobalModuleIndexBuilder(
      FileManager &FileMgr, const PCHContainerReader &PCHContainerRdr)
      : FileMgr(FileMgr), PCHContainerRdr(PCHContainerRdr) {}

  /// Load the contents of the given module file into the builder.
  llvm::Error loadModuleFile(const FileEntry *File);

  /// Write the index to the given bitstream.
  /// \returns true if an error occurred, false otherwise.
  bool writeIndex(llvm::BitstreamWriter &Stream);
};
466}

468static void emitBlockID(unsigned ID, const char *Name,
                      llvm::BitstreamWriter &Stream,
                      SmallVectorImpl<uint64_t> &Record) {
Record.clear();
Record.push_back(ID);
Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETBID, Record);

// Emit the block name if present.
if (!Name || Name[0] == 0) return;
Record.clear();
while (*Name)
  Record.push_back(*Name++);
Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_BLOCKNAME, Record);
481}

483static void emitRecordID(unsigned ID, const char *Name,
                       llvm::BitstreamWriter &Stream,
                       SmallVectorImpl<uint64_t> &Record) {
Record.clear();
Record.push_back(ID);
while (*Name)
  Record.push_back(*Name++);
Stream.EmitRecord(llvm::bitc::BLOCKINFO_CODE_SETRECORDNAME, Record);
491}

493void
494GlobalModuleIndexBuilder::emitBlockInfoBlock(llvm::BitstreamWriter &Stream) {
SmallVector<uint64_t, 64> Record;
Stream.EnterBlockInfoBlock();

498#define BLOCK(X) emitBlockID(X ## _ID, #X, Stream, Record)
499#define RECORD(X) emitRecordID(X, #X, Stream, Record)
BLOCK(GLOBAL_INDEX_BLOCK);
RECORD(INDEX_METADATA);
RECORD(MODULE);
RECORD(IDENTIFIER_INDEX);
504#undef RECORD
505#undef BLOCK

Stream.ExitBlock();
508}

510namespace {
class InterestingASTIdentifierLookupTrait
  : public serialization::reader::ASTIdentifierLookupTraitBase {

public:
  /// The identifier and whether it is "interesting".
  typedef std::pair<StringRef, bool> data_type;

  data_type ReadData(const internal_key_type& k,
                     const unsigned char* d,
                     unsigned DataLen) {
    // The first bit indicates whether this identifier is interesting.
    // That's all we care about.
    using namespace llvm::support;
    unsigned RawID = endian::readNext<uint32_t, little, unaligned>(d);
    bool IsInteresting = RawID & 0x01;
    return std::make_pair(k, IsInteresting);
  }
};
529}

531llvm::Error GlobalModuleIndexBuilder::loadModuleFile(const FileEntry *File) {
// Open the module file.

auto Buffer = FileMgr.getBufferForFile(File, /*isVolatile=*/true);
if (!Buffer)
7
←
Taking false branch→
  return llvm::createStringError(Buffer.getError(),
                                 "failed getting buffer for module file");

// Initialize the input stream
llvm::BitstreamCursor InStream(PCHContainerRdr.ExtractPCH(**Buffer));

// Sniff for the signature.
for (unsigned char C : {'C', 'P', 'C', 'H'})
8
←
Assuming '__begin1' is equal to '__end1'→
  if (Expected<llvm::SimpleBitstreamCursor::word_t> Res = InStream.Read(8)) {
    if (Res.get() != C)
      return llvm::createStringError(std::errc::illegal_byte_sequence,
                                     "expected signature CPCH");
  } else
    return Res.takeError();

// Record this module file and assign it a unique ID (if it doesn't have
// one already).
unsigned ID = getModuleFileInfo(File).ID;

// Search for the blocks and records we care about.
enum { Other, ControlBlock, ASTBlock, DiagnosticOptionsBlock } State = Other;
bool Done = false;
while (!Done) {
9
←
Loop condition is true.  Entering loop body→
  Expected<llvm::BitstreamEntry> MaybeEntry = InStream.advance();
10
←
Calling 'BitstreamCursor::advance'→
  if (!MaybeEntry)
    return MaybeEntry.takeError();
  llvm::BitstreamEntry Entry = MaybeEntry.get();

  switch (Entry.Kind) {
  case llvm::BitstreamEntry::Error:
    Done = true;
    continue;

  case llvm::BitstreamEntry::Record:
    // In the 'other' state, just skip the record. We don't care.
    if (State == Other) {
      if (llvm::Expected<unsigned> Skipped = InStream.skipRecord(Entry.ID))
        continue;
      else
        return Skipped.takeError();
    }

    // Handle potentially-interesting records below.
    break;

  case llvm::BitstreamEntry::SubBlock:
    if (Entry.ID == CONTROL_BLOCK_ID) {
      if (llvm::Error Err = InStream.EnterSubBlock(CONTROL_BLOCK_ID))
        return Err;

      // Found the control block.
      State = ControlBlock;
      continue;
    }

    if (Entry.ID == AST_BLOCK_ID) {
      if (llvm::Error Err = InStream.EnterSubBlock(AST_BLOCK_ID))
        return Err;

      // Found the AST block.
      State = ASTBlock;
      continue;
    }

    if (Entry.ID == UNHASHED_CONTROL_BLOCK_ID) {
      if (llvm::Error Err = InStream.EnterSubBlock(UNHASHED_CONTROL_BLOCK_ID))
        return Err;

      // Found the Diagnostic Options block.
      State = DiagnosticOptionsBlock;
      continue;
    }

    if (llvm::Error Err = InStream.SkipBlock())
      return Err;

    continue;

  case llvm::BitstreamEntry::EndBlock:
    State = Other;
    continue;
  }

  // Read the given record.
  SmallVector<uint64_t, 64> Record;
  StringRef Blob;
  Expected<unsigned> MaybeCode = InStream.readRecord(Entry.ID, Record, &Blob);
  if (!MaybeCode)
    return MaybeCode.takeError();
  unsigned Code = MaybeCode.get();

  // Handle module dependencies.
  if (State == ControlBlock && Code == IMPORTS) {
    // Load each of the imported PCH files.
    unsigned Idx = 0, N = Record.size();
    while (Idx < N) {
      // Read information about the AST file.

      // Skip the imported kind
      ++Idx;

      // Skip the import location
      ++Idx;

      // Load stored size/modification time.
      off_t StoredSize = (off_t)Record[Idx++];
      time_t StoredModTime = (time_t)Record[Idx++];

      // Skip the stored signature.
      // FIXME: we could read the signature out of the import and validate it.
      auto FirstSignatureByte = Record.begin() + Idx;
      ASTFileSignature StoredSignature = ASTFileSignature::create(
          FirstSignatureByte, FirstSignatureByte + ASTFileSignature::size);
      Idx += ASTFileSignature::size;

      // Skip the module name (currently this is only used for prebuilt
      // modules while here we are only dealing with cached).
      Idx += Record[Idx] + 1;

      // Retrieve the imported file name.
      unsigned Length = Record[Idx++];
      SmallString<128> ImportedFile(Record.begin() + Idx,
                                    Record.begin() + Idx + Length);
      Idx += Length;

      // Find the imported module file.
      auto DependsOnFile
        = FileMgr.getFile(ImportedFile, /*OpenFile=*/false,
                          /*CacheFailure=*/false);

      if (!DependsOnFile)
        return llvm::createStringError(std::errc::bad_file_descriptor,
                                       "imported file \"%s\" not found",
                                       ImportedFile.c_str());

      // Save the information in ImportedModuleFileInfo so we can verify after
      // loading all pcms.
      ImportedModuleFiles.insert(std::make_pair(
          *DependsOnFile, ImportedModuleFileInfo(StoredSize, StoredModTime,
                                                 StoredSignature)));

      // Record the dependency.
      unsigned DependsOnID = getModuleFileInfo(*DependsOnFile).ID;
      getModuleFileInfo(File).Dependencies.push_back(DependsOnID);
    }

    continue;
  }

  // Handle the identifier table
  if (State == ASTBlock && Code == IDENTIFIER_TABLE && Record[0] > 0) {
    typedef llvm::OnDiskIterableChainedHashTable<
        InterestingASTIdentifierLookupTrait> InterestingIdentifierTable;
    std::unique_ptr<InterestingIdentifierTable> Table(
        InterestingIdentifierTable::Create(
            (const unsigned char *)Blob.data() + Record[0],
            (const unsigned char *)Blob.data() + sizeof(uint32_t),
            (const unsigned char *)Blob.data()));
    for (InterestingIdentifierTable::data_iterator D = Table->data_begin(),
                                                   DEnd = Table->data_end();
         D != DEnd; ++D) {
      std::pair<StringRef, bool> Ident = *D;
      if (Ident.second)
        InterestingIdentifiers[Ident.first].push_back(ID);
      else
        (void)InterestingIdentifiers[Ident.first];
    }
  }

  // Get Signature.
  if (State == DiagnosticOptionsBlock && Code == SIGNATURE)
    getModuleFileInfo(File).Signature = ASTFileSignature::create(
        Record.begin(), Record.begin() + ASTFileSignature::size);

  // We don't care about this record.
}

return llvm::Error::success();
714}

716namespace {

718/// Trait used to generate the identifier index as an on-disk hash
719/// table.
720class IdentifierIndexWriterTrait {
721public:
typedef StringRef key_type;
typedef StringRef key_type_ref;
typedef SmallVector<unsigned, 2> data_type;
typedef const SmallVector<unsigned, 2> &data_type_ref;
typedef unsigned hash_value_type;
typedef unsigned offset_type;

static hash_value_type ComputeHash(key_type_ref Key) {
  return llvm::djbHash(Key);
}

std::pair<unsigned,unsigned>
EmitKeyDataLength(raw_ostream& Out, key_type_ref Key, data_type_ref Data) {
  using namespace llvm::support;
  endian::Writer LE(Out, little);
  unsigned KeyLen = Key.size();
  unsigned DataLen = Data.size() * 4;
  LE.write<uint16_t>(KeyLen);
  LE.write<uint16_t>(DataLen);
  return std::make_pair(KeyLen, DataLen);
}

void EmitKey(raw_ostream& Out, key_type_ref Key, unsigned KeyLen) {
  Out.write(Key.data(), KeyLen);
}

void EmitData(raw_ostream& Out, key_type_ref Key, data_type_ref Data,
              unsigned DataLen) {
  using namespace llvm::support;
  for (unsigned I = 0, N = Data.size(); I != N; ++I)
    endian::write<uint32_t>(Out, Data[I], little);
}
754};

756}

758bool GlobalModuleIndexBuilder::writeIndex(llvm::BitstreamWriter &Stream) {
for (auto MapEntry : ImportedModuleFiles) {
  auto *File = MapEntry.first;
  ImportedModuleFileInfo &Info = MapEntry.second;
  if (getModuleFileInfo(File).Signature) {
    if (getModuleFileInfo(File).Signature != Info.StoredSignature)
      // Verify Signature.
      return true;
  } else if (Info.StoredSize != File->getSize() ||
             Info.StoredModTime != File->getModificationTime())
    // Verify Size and ModTime.
    return true;
}

using namespace llvm;
llvm::TimeTraceScope TimeScope("Module WriteIndex");

// Emit the file header.
Stream.Emit((unsigned)'B', 8);
Stream.Emit((unsigned)'C', 8);
Stream.Emit((unsigned)'G', 8);
Stream.Emit((unsigned)'I', 8);

// Write the block-info block, which describes the records in this bitcode
// file.
emitBlockInfoBlock(Stream);

Stream.EnterSubblock(GLOBAL_INDEX_BLOCK_ID, 3);

// Write the metadata.
SmallVector<uint64_t, 2> Record;
Record.push_back(CurrentVersion);
Stream.EmitRecord(INDEX_METADATA, Record);

// Write the set of known module files.
for (ModuleFilesMap::iterator M = ModuleFiles.begin(),
                              MEnd = ModuleFiles.end();
     M != MEnd; ++M) {
  Record.clear();
  Record.push_back(M->second.ID);
  Record.push_back(M->first->getSize());
  Record.push_back(M->first->getModificationTime());

  // File name
  StringRef Name(M->first->getName());
  Record.push_back(Name.size());
  Record.append(Name.begin(), Name.end());

  // Dependencies
  Record.push_back(M->second.Dependencies.size());
  Record.append(M->second.Dependencies.begin(), M->second.Dependencies.end());
  Stream.EmitRecord(MODULE, Record);
}

// Write the identifier -> module file mapping.
{
  llvm::OnDiskChainedHashTableGenerator<IdentifierIndexWriterTrait> Generator;
  IdentifierIndexWriterTrait Trait;

  // Populate the hash table.
  for (InterestingIdentifierMap::iterator I = InterestingIdentifiers.begin(),
                                          IEnd = InterestingIdentifiers.end();
       I != IEnd; ++I) {
    Generator.insert(I->first(), I->second, Trait);
  }

  // Create the on-disk hash table in a buffer.
  SmallString<4096> IdentifierTable;
  uint32_t BucketOffset;
  {
    using namespace llvm::support;
    llvm::raw_svector_ostream Out(IdentifierTable);
    // Make sure that no bucket is at offset 0
    endian::write<uint32_t>(Out, 0, little);
    BucketOffset = Generator.Emit(Out, Trait);
  }

  // Create a blob abbreviation
  auto Abbrev = std::make_shared<BitCodeAbbrev>();
  Abbrev->Add(BitCodeAbbrevOp(IDENTIFIER_INDEX));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
  unsigned IDTableAbbrev = Stream.EmitAbbrev(std::move(Abbrev));

  // Write the identifier table
  uint64_t Record[] = {IDENTIFIER_INDEX, BucketOffset};
  Stream.EmitRecordWithBlob(IDTableAbbrev, Record, IdentifierTable);
}

Stream.ExitBlock();
return false;
849}

851llvm::Error
852GlobalModuleIndex::writeIndex(FileManager &FileMgr,
                            const PCHContainerReader &PCHContainerRdr,
                            StringRef Path) {
llvm::SmallString<128> IndexPath;
IndexPath += Path;
llvm::sys::path::append(IndexPath, IndexFileName);

// Coordinate building the global index file with other processes that might
// try to do the same.
llvm::LockFileManager Locked(IndexPath);
switch (Locked) {
1
Control jumps to 'case LFS_Owned:'  at line 866→
case llvm::LockFileManager::LFS_Error:
  return llvm::createStringError(std::errc::io_error, "LFS error");

case llvm::LockFileManager::LFS_Owned:
  // We're responsible for building the index ourselves. Do so below.
  break;
2
←
 Execution continues on line 878→

case llvm::LockFileManager::LFS_Shared:
  // Someone else is responsible for building the index. We don't care
  // when they finish, so we're done.
  return llvm::createStringError(std::errc::device_or_resource_busy,
                                 "someone else is building the index");
}

// The module index builder.
GlobalModuleIndexBuilder Builder(FileMgr, PCHContainerRdr);

// Load each of the module files.
std::error_code EC;
for (llvm::sys::fs::directory_iterator D(Path, EC), DEnd;
3
←
Loop condition is true.  Entering loop body→
     D != DEnd && !EC;
     D.increment(EC)) {
  // If this isn't a module file, we don't care.
  if (llvm::sys::path::extension(D->path()) != ".pcm") {
4
←
Taking false branch→
    // ... unless it's a .pcm.lock file, which indicates that someone is
    // in the process of rebuilding a module. They'll rebuild the index
    // at the end of that translation unit, so we don't have to.
    if (llvm::sys::path::extension(D->path()) == ".pcm.lock")
      return llvm::createStringError(std::errc::device_or_resource_busy,
                                     "someone else is building the index");

    continue;
  }

  // If we can't find the module file, skip it.
  auto ModuleFile = FileMgr.getFile(D->path());
  if (!ModuleFile)
5
←
Taking false branch→
    continue;

  // Load this module file.
  if (llvm::Error Err = Builder.loadModuleFile(*ModuleFile))
6
←
Calling 'GlobalModuleIndexBuilder::loadModuleFile'→
    return Err;
}

// The output buffer, into which the global index will be written.
SmallString<16> OutputBuffer;
{
  llvm::BitstreamWriter OutputStream(OutputBuffer);
  if (Builder.writeIndex(OutputStream))
    return llvm::createStringError(std::errc::io_error,
                                   "failed writing index");
}

return llvm::writeFileAtomically((IndexPath + "-%%%%%%%%").str(), IndexPath,
                                 OutputBuffer);
918}

920namespace {
class GlobalIndexIdentifierIterator : public IdentifierIterator {
  /// The current position within the identifier lookup table.
  IdentifierIndexTable::key_iterator Current;

  /// The end position within the identifier lookup table.
  IdentifierIndexTable::key_iterator End;

public:
  explicit GlobalIndexIdentifierIterator(IdentifierIndexTable &Idx) {
    Current = Idx.key_begin();
    End = Idx.key_end();
  }

  StringRef Next() override {
    if (Current == End)
      return StringRef();

    StringRef Result = *Current;
    ++Current;
    return Result;
  }
};
943}

945IdentifierIterator *GlobalModuleIndex::createIdentifierIterator() const {
IdentifierIndexTable &Table =
  *static_cast<IdentifierIndexTable *>(IdentifierIndex);
return new GlobalIndexIdentifierIterator(Table);
949}

←

/usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/llvm/include/llvm/Bitstream/BitstreamReader.h

→

1//===- BitstreamReader.h - Low-level bitstream reader interface -*- 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 header defines the BitstreamReader class.  This class can be used to
10// read an arbitrary bitstream, regardless of its contents.
11//
12//===----------------------------------------------------------------------===//

14#ifndef LLVM_BITSTREAM_BITSTREAMREADER_H
15#define LLVM_BITSTREAM_BITSTREAMREADER_H

17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/Bitstream/BitCodes.h"
20#include "llvm/Support/Endian.h"
21#include "llvm/Support/Error.h"
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Support/MathExtras.h"
24#include "llvm/Support/MemoryBuffer.h"
25#include <algorithm>
26#include <cassert>
27#include <climits>
28#include <cstddef>
29#include <cstdint>
30#include <memory>
31#include <string>
32#include <utility>
33#include <vector>

35namespace llvm {

37/// This class maintains the abbreviations read from a block info block.
38class BitstreamBlockInfo {
39public:
/// This contains information emitted to BLOCKINFO_BLOCK blocks. These
/// describe abbreviations that all blocks of the specified ID inherit.
struct BlockInfo {
  unsigned BlockID = 0;
  std::vector<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
  std::string Name;
  std::vector<std::pair<unsigned, std::string>> RecordNames;
};

49private:
std::vector<BlockInfo> BlockInfoRecords;

52public:
/// If there is block info for the specified ID, return it, otherwise return
/// null.
const BlockInfo *getBlockInfo(unsigned BlockID) const {
  // Common case, the most recent entry matches BlockID.
  if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
    return &BlockInfoRecords.back();

  for (unsigned i = 0, e = static_cast<unsigned>(BlockInfoRecords.size());
       i != e; ++i)
    if (BlockInfoRecords[i].BlockID == BlockID)
      return &BlockInfoRecords[i];
  return nullptr;
}

BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
  if (const BlockInfo *BI = getBlockInfo(BlockID))
    return *const_cast<BlockInfo*>(BI);

  // Otherwise, add a new record.
  BlockInfoRecords.emplace_back();
  BlockInfoRecords.back().BlockID = BlockID;
  return BlockInfoRecords.back();
}
76};

78/// This represents a position within a bitstream. There may be multiple
79/// independent cursors reading within one bitstream, each maintaining their
80/// own local state.
81class SimpleBitstreamCursor {
ArrayRef<uint8_t> BitcodeBytes;
size_t NextChar = 0;

85public:
/// This is the current data we have pulled from the stream but have not
/// returned to the client. This is specifically and intentionally defined to
/// follow the word size of the host machine for efficiency. We use word_t in
/// places that are aware of this to make it perfectly explicit what is going
/// on.
using word_t = size_t;

93private:
word_t CurWord = 0;

/// This is the number of bits in CurWord that are valid. This is always from
/// [0...bits_of(size_t)-1] inclusive.
unsigned BitsInCurWord = 0;

100public:
static const constexpr size_t MaxChunkSize = sizeof(word_t) * 8;

SimpleBitstreamCursor() = default;
explicit SimpleBitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
    : BitcodeBytes(BitcodeBytes) {}
explicit SimpleBitstreamCursor(StringRef BitcodeBytes)
    : BitcodeBytes(arrayRefFromStringRef(BitcodeBytes)) {}
explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
    : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}

bool canSkipToPos(size_t pos) const {
  // pos can be skipped to if it is a valid address or one byte past the end.
  return pos <= BitcodeBytes.size();
}

bool AtEndOfStream() {
  return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
}

/// Return the bit # of the bit we are reading.
uint64_t GetCurrentBitNo() const {
  return NextChar*CHAR_BIT8 - BitsInCurWord;
}

// Return the byte # of the current bit.
uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }

ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }

/// Reset the stream to the specified bit number.
Error JumpToBit(uint64_t BitNo) {
  size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
  unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
  assert(canSkipToPos(ByteNo) && "Invalid location")((void)0);

  // Move the cursor to the right word.
  NextChar = ByteNo;
  BitsInCurWord = 0;

  // Skip over any bits that are already consumed.
  if (WordBitNo) {
    if (Expected<word_t> Res = Read(WordBitNo))
      return Error::success();
    else
      return Res.takeError();
  }

  return Error::success();
}

/// Get a pointer into the bitstream at the specified byte offset.
const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
  return BitcodeBytes.data() + ByteNo;
}

/// Get a pointer into the bitstream at the specified bit offset.
///
/// The bit offset must be on a byte boundary.
const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
  assert(!(BitNo % 8) && "Expected bit on byte boundary")((void)0);
  return getPointerToByte(BitNo / 8, NumBytes);
}

Error fillCurWord() {
  if (NextChar >= BitcodeBytes.size())
    return createStringError(std::errc::io_error,
                             "Unexpected end of file reading %u of %u bytes",
                             NextChar, BitcodeBytes.size());

  // Read the next word from the stream.
  const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
  unsigned BytesRead;
  if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
    BytesRead = sizeof(word_t);
    CurWord =
        support::endian::read<word_t, support::little, support::unaligned>(
            NextCharPtr);
  } else {
    // Short read.
    BytesRead = BitcodeBytes.size() - NextChar;
    CurWord = 0;
    for (unsigned B = 0; B != BytesRead; ++B)
      CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
  }
  NextChar += BytesRead;
  BitsInCurWord = BytesRead * 8;
  return Error::success();
}

Expected<word_t> Read(unsigned NumBits) {
  static const unsigned BitsInWord = MaxChunkSize;

  assert(NumBits && NumBits <= BitsInWord &&((void)0)
         "Cannot return zero or more than BitsInWord bits!")((void)0);

  static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
15
←
'?' condition is true→

  // If the field is fully contained by CurWord, return it quickly.
  if (BitsInCurWord >= NumBits) {
16
←
Assuming 'NumBits' is > field 'BitsInCurWord'→
17
←
Taking false branch→
    word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));

    // Use a mask to avoid undefined behavior.
    CurWord >>= (NumBits & Mask);

    BitsInCurWord -= NumBits;
    return R;
  }

  word_t R = BitsInCurWord17.1
Field 'BitsInCurWord' is not equal to 0
1
Field 'BitsInCurWord' is not equal to 0
1
Field 'BitsInCurWord' is not equal to 0
 ? CurWord : 0;
18
←
'?' condition is true→
  unsigned BitsLeft = NumBits - BitsInCurWord;

  if (Error fillResult = fillCurWord())
19
←
Calling 'Error::operator bool'→
21
←
Returning from 'Error::operator bool'→
22
←
Taking false branch→
    return std::move(fillResult);

  // If we run out of data, abort.
  if (BitsLeft > BitsInCurWord)
23
←
Assuming 'BitsLeft' is <= field 'BitsInCurWord'→
24
←
Taking false branch→
    return createStringError(std::errc::io_error,
                             "Unexpected end of file reading %u of %u bits",
                             BitsInCurWord, BitsLeft);

  word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
25
←
The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'llvm::SimpleBitstreamCursor::word_t'

  // Use a mask to avoid undefined behavior.
  CurWord >>= (BitsLeft & Mask);

  BitsInCurWord -= BitsLeft;

  R |= R2 << (NumBits - BitsLeft);

  return R;
}

Expected<uint32_t> ReadVBR(unsigned NumBits) {
  Expected<unsigned> MaybeRead = Read(NumBits);
  if (!MaybeRead)
    return MaybeRead;
  uint32_t Piece = MaybeRead.get();

  if ((Piece & (1U << (NumBits-1))) == 0)
    return Piece;

  uint32_t Result = 0;
  unsigned NextBit = 0;
  while (true) {
    Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;

    if ((Piece & (1U << (NumBits-1))) == 0)
      return Result;

    NextBit += NumBits-1;
    MaybeRead = Read(NumBits);
    if (!MaybeRead)
      return MaybeRead;
    Piece = MaybeRead.get();
  }
}

// Read a VBR that may have a value up to 64-bits in size. The chunk size of
// the VBR must still be <= 32 bits though.
Expected<uint64_t> ReadVBR64(unsigned NumBits) {
  Expected<uint64_t> MaybeRead = Read(NumBits);
  if (!MaybeRead)
    return MaybeRead;
  uint32_t Piece = MaybeRead.get();

  if ((Piece & (1U << (NumBits-1))) == 0)
    return uint64_t(Piece);

  uint64_t Result = 0;
  unsigned NextBit = 0;
  while (true) {
    Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;

    if ((Piece & (1U << (NumBits-1))) == 0)
      return Result;

    NextBit += NumBits-1;
    MaybeRead = Read(NumBits);
    if (!MaybeRead)
      return MaybeRead;
    Piece = MaybeRead.get();
  }
}

void SkipToFourByteBoundary() {
  // If word_t is 64-bits and if we've read less than 32 bits, just dump
  // the bits we have up to the next 32-bit boundary.
  if (sizeof(word_t) > 4 &&
      BitsInCurWord >= 32) {
    CurWord >>= BitsInCurWord-32;
    BitsInCurWord = 32;
    return;
  }

  BitsInCurWord = 0;
}

/// Return the size of the stream in bytes.
size_t SizeInBytes() const { return BitcodeBytes.size(); }

/// Skip to the end of the file.
void skipToEnd() { NextChar = BitcodeBytes.size(); }
303};

305/// When advancing through a bitstream cursor, each advance can discover a few
306/// different kinds of entries:
307struct BitstreamEntry {
enum {
  Error,    // Malformed bitcode was found.
  EndBlock, // We've reached the end of the current block, (or the end of the
            // file, which is treated like a series of EndBlock records.
  SubBlock, // This is the start of a new subblock of a specific ID.
  Record    // This is a record with a specific AbbrevID.
} Kind;

unsigned ID;

static BitstreamEntry getError() {
  BitstreamEntry E; E.Kind = Error; return E;
}

static BitstreamEntry getEndBlock() {
  BitstreamEntry E; E.Kind = EndBlock; return E;
}

static BitstreamEntry getSubBlock(unsigned ID) {
  BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
}

static BitstreamEntry getRecord(unsigned AbbrevID) {
  BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
}
333};

335/// This represents a position within a bitcode file, implemented on top of a
336/// SimpleBitstreamCursor.
337///
338/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
339/// be passed by value.
340class BitstreamCursor : SimpleBitstreamCursor {
// This is the declared size of code values used for the current block, in
// bits.
unsigned CurCodeSize = 2;

/// Abbrevs installed at in this block.
std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;

struct Block {
  unsigned PrevCodeSize;
  std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;

  explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
};

/// This tracks the codesize of parent blocks.
SmallVector<Block, 8> BlockScope;

BitstreamBlockInfo *BlockInfo = nullptr;

360public:
static const size_t MaxChunkSize = sizeof(word_t) * 8;

BitstreamCursor() = default;
explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
    : SimpleBitstreamCursor(BitcodeBytes) {}
explicit BitstreamCursor(StringRef BitcodeBytes)
    : SimpleBitstreamCursor(BitcodeBytes) {}
explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
    : SimpleBitstreamCursor(BitcodeBytes) {}

using SimpleBitstreamCursor::AtEndOfStream;
using SimpleBitstreamCursor::canSkipToPos;
using SimpleBitstreamCursor::fillCurWord;
using SimpleBitstreamCursor::getBitcodeBytes;
using SimpleBitstreamCursor::GetCurrentBitNo;
using SimpleBitstreamCursor::getCurrentByteNo;
using SimpleBitstreamCursor::getPointerToByte;
using SimpleBitstreamCursor::JumpToBit;
using SimpleBitstreamCursor::Read;
using SimpleBitstreamCursor::ReadVBR;
using SimpleBitstreamCursor::ReadVBR64;
using SimpleBitstreamCursor::SizeInBytes;
using SimpleBitstreamCursor::skipToEnd;

/// Return the number of bits used to encode an abbrev #.
unsigned getAbbrevIDWidth() const { return CurCodeSize; }

/// Flags that modify the behavior of advance().
enum {
  /// If this flag is used, the advance() method does not automatically pop
  /// the block scope when the end of a block is reached.
  AF_DontPopBlockAtEnd = 1,

  /// If this flag is used, abbrev entries are returned just like normal
  /// records.
  AF_DontAutoprocessAbbrevs = 2
};

/// Advance the current bitstream, returning the next entry in the stream.
Expected<BitstreamEntry> advance(unsigned Flags = 0) {
  while (true) {
11
←
Loop condition is true.  Entering loop body→
    if (AtEndOfStream())
12
←
Taking false branch→
      return BitstreamEntry::getError();

    Expected<unsigned> MaybeCode = ReadCode();
13
←
Calling 'BitstreamCursor::ReadCode'→
    if (!MaybeCode)
      return MaybeCode.takeError();
    unsigned Code = MaybeCode.get();

    if (Code == bitc::END_BLOCK) {
      // Pop the end of the block unless Flags tells us not to.
      if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
        return BitstreamEntry::getError();
      return BitstreamEntry::getEndBlock();
    }

    if (Code == bitc::ENTER_SUBBLOCK) {
      if (Expected<unsigned> MaybeSubBlock = ReadSubBlockID())
        return BitstreamEntry::getSubBlock(MaybeSubBlock.get());
      else
        return MaybeSubBlock.takeError();
    }

    if (Code == bitc::DEFINE_ABBREV &&
        !(Flags & AF_DontAutoprocessAbbrevs)) {
      // We read and accumulate abbrev's, the client can't do anything with
      // them anyway.
      if (Error Err = ReadAbbrevRecord())
        return std::move(Err);
      continue;
    }

    return BitstreamEntry::getRecord(Code);
  }
}

/// This is a convenience function for clients that don't expect any
/// subblocks. This just skips over them automatically.
Expected<BitstreamEntry> advanceSkippingSubblocks(unsigned Flags = 0) {
  while (true) {
    // If we found a normal entry, return it.
    Expected<BitstreamEntry> MaybeEntry = advance(Flags);
    if (!MaybeEntry)
      return MaybeEntry;
    BitstreamEntry Entry = MaybeEntry.get();

    if (Entry.Kind != BitstreamEntry::SubBlock)
      return Entry;

    // If we found a sub-block, just skip over it and check the next entry.
    if (Error Err = SkipBlock())
      return std::move(Err);
  }
}

Expected<unsigned> ReadCode() { return Read(CurCodeSize); }
14
←
Calling 'SimpleBitstreamCursor::Read'→

// Block header:
//    [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]

/// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
Expected<unsigned> ReadSubBlockID() { return ReadVBR(bitc::BlockIDWidth); }

/// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
/// of this block.
Error SkipBlock() {
  // Read and ignore the codelen value.
  if (Expected<uint32_t> Res = ReadVBR(bitc::CodeLenWidth))
    ; // Since we are skipping this block, we don't care what code widths are
      // used inside of it.
  else
    return Res.takeError();

  SkipToFourByteBoundary();
  Expected<unsigned> MaybeNum = Read(bitc::BlockSizeWidth);
  if (!MaybeNum)
    return MaybeNum.takeError();
  size_t NumFourBytes = MaybeNum.get();

  // Check that the block wasn't partially defined, and that the offset isn't
  // bogus.
  size_t SkipTo = GetCurrentBitNo() + NumFourBytes * 4 * 8;
  if (AtEndOfStream())
    return createStringError(std::errc::illegal_byte_sequence,
                             "can't skip block: already at end of stream");
  if (!canSkipToPos(SkipTo / 8))
    return createStringError(std::errc::illegal_byte_sequence,
                             "can't skip to bit %zu from %" PRIu64"llu", SkipTo,
                             GetCurrentBitNo());

  if (Error Res = JumpToBit(SkipTo))
    return Res;

  return Error::success();
}

/// Having read the ENTER_SUBBLOCK abbrevid, and enter the block.
Error EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);

bool ReadBlockEnd() {
  if (BlockScope.empty()) return true;

  // Block tail:
  //    [END_BLOCK, <align4bytes>]
  SkipToFourByteBoundary();

  popBlockScope();
  return false;
}

511private:
void popBlockScope() {
  CurCodeSize = BlockScope.back().PrevCodeSize;

  CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
  BlockScope.pop_back();
}

//===--------------------------------------------------------------------===//
// Record Processing
//===--------------------------------------------------------------------===//

523public:
/// Return the abbreviation for the specified AbbrevId.
const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
  unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
  if (AbbrevNo >= CurAbbrevs.size())
    report_fatal_error("Invalid abbrev number");
  return CurAbbrevs[AbbrevNo].get();
}

/// Read the current record and discard it, returning the code for the record.
Expected<unsigned> skipRecord(unsigned AbbrevID);

Expected<unsigned> readRecord(unsigned AbbrevID,
                              SmallVectorImpl<uint64_t> &Vals,
                              StringRef *Blob = nullptr);

//===--------------------------------------------------------------------===//
// Abbrev Processing
//===--------------------------------------------------------------------===//
Error ReadAbbrevRecord();

/// Read and return a block info block from the bitstream. If an error was
/// encountered, return None.
///
/// \param ReadBlockInfoNames Whether to read block/record name information in
/// the BlockInfo block. Only llvm-bcanalyzer uses this.
Expected<Optional<BitstreamBlockInfo>>
ReadBlockInfoBlock(bool ReadBlockInfoNames = false);

/// Set the block info to be used by this BitstreamCursor to interpret
/// abbreviated records.
void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
555};

557} // end llvm namespace

559#endif // LLVM_BITSTREAM_BITSTREAMREADER_H

←

/usr/src/gnu/usr.bin/clang/libclangSerialization/../../../llvm/llvm/include/llvm/Support/Error.h

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/STLExtras.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/StringExtras.h"
20#include "llvm/ADT/Twine.h"
21#include "llvm/Config/abi-breaking.h"
22#include "llvm/Support/AlignOf.h"
23#include "llvm/Support/Compiler.h"
24#include "llvm/Support/Debug.h"
25#include "llvm/Support/ErrorHandling.h"
26#include "llvm/Support/ErrorOr.h"
27#include "llvm/Support/Format.h"
28#include "llvm/Support/raw_ostream.h"
29#include <algorithm>
30#include <cassert>
31#include <cstdint>
32#include <cstdlib>
33#include <functional>
34#include <memory>
35#include <new>
36#include <string>
37#include <system_error>
38#include <type_traits>
39#include <utility>
40#include <vector>
41 
42namespace llvm {
43 
44class ErrorSuccess;
45 
46/// Base class for error info classes. Do not extend this directly: Extend
47/// the ErrorInfo template subclass instead.
48class ErrorInfoBase {
49public:
50  virtual ~ErrorInfoBase() = default;
51 
52  /// Print an error message to an output stream.
53  virtual void log(raw_ostream &OS) const = 0;
54 
55  /// Return the error message as a string.
56  virtual std::string message() const {
57    std::string Msg;
58    raw_string_ostream OS(Msg);
59    log(OS);
60    return OS.str();
61  }
62 
63  /// Convert this error to a std::error_code.
64  ///
65  /// This is a temporary crutch to enable interaction with code still
66  /// using std::error_code. It will be removed in the future.
67  virtual std::error_code convertToErrorCode() const = 0;
68 
69  // Returns the class ID for this type.
70  static const void *classID() { return &ID; }
71 
72  // Returns the class ID for the dynamic type of this ErrorInfoBase instance.
73  virtual const void *dynamicClassID() const = 0;
74 
75  // Check whether this instance is a subclass of the class identified by
76  // ClassID.
77  virtual bool isA(const void *const ClassID) const {
78    return ClassID == classID();
79  }
80 
81  // Check whether this instance is a subclass of ErrorInfoT.
82  template <typename ErrorInfoT> bool isA() const {
83    return isA(ErrorInfoT::classID());
84  }
85 
86private:
87  virtual void anchor();
88 
89  static char ID;
90};
91 
92/// Lightweight error class with error context and mandatory checking.
93///
94/// Instances of this class wrap a ErrorInfoBase pointer. Failure states
95/// are represented by setting the pointer to a ErrorInfoBase subclass
96/// instance containing information describing the failure. Success is
97/// represented by a null pointer value.
98///
99/// Instances of Error also contains a 'Checked' flag, which must be set
100/// before the destructor is called, otherwise the destructor will trigger a
101/// runtime error. This enforces at runtime the requirement that all Error
102/// instances be checked or returned to the caller.
103///
104/// There are two ways to set the checked flag, depending on what state the
105/// Error instance is in. For Error instances indicating success, it
106/// is sufficient to invoke the boolean conversion operator. E.g.:
107///
108///   @code{.cpp}
109///   Error foo(<...>);
110///
111///   if (auto E = foo(<...>))
112///     return E; // <- Return E if it is in the error state.
113///   // We have verified that E was in the success state. It can now be safely
114///   // destroyed.
115///   @endcode
116///
117/// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
118/// without testing the return value will raise a runtime error, even if foo
119/// returns success.
120///
121/// For Error instances representing failure, you must use either the
122/// handleErrors or handleAllErrors function with a typed handler. E.g.:
123///
124///   @code{.cpp}
125///   class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
126///     // Custom error info.
127///   };
128///
129///   Error foo(<...>) { return make_error<MyErrorInfo>(...); }
130///
131///   auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
132///   auto NewE =
133///     handleErrors(E,
134///       [](const MyErrorInfo &M) {
135///         // Deal with the error.
136///       },
137///       [](std::unique_ptr<OtherError> M) -> Error {
138///         if (canHandle(*M)) {
139///           // handle error.
140///           return Error::success();
141///         }
142///         // Couldn't handle this error instance. Pass it up the stack.
143///         return Error(std::move(M));
144///       );
145///   // Note - we must check or return NewE in case any of the handlers
146///   // returned a new error.
147///   @endcode
148///
149/// The handleAllErrors function is identical to handleErrors, except
150/// that it has a void return type, and requires all errors to be handled and
151/// no new errors be returned. It prevents errors (assuming they can all be
152/// handled) from having to be bubbled all the way to the top-level.
153///
154/// *All* Error instances must be checked before destruction, even if
155/// they're moved-assigned or constructed from Success values that have already
156/// been checked. This enforces checking through all levels of the call stack.
157class LLVM_NODISCARD[[clang::warn_unused_result]] Error {
158  // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors
159  // to add to the error list. It can't rely on handleErrors for this, since
160  // handleErrors does not support ErrorList handlers.
161  friend class ErrorList;
162 
163  // handleErrors needs to be able to set the Checked flag.
164  template <typename... HandlerTs>
165  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
166 
167  // Expected<T> needs to be able to steal the payload when constructed from an
168  // error.
169  template <typename T> friend class Expected;
170 
171  // wrap needs to be able to steal the payload.
172  friend LLVMErrorRef wrap(Error);
173 
174protected:
175  /// Create a success value. Prefer using 'Error::success()' for readability
176  Error() {
177    setPtr(nullptr);
178    setChecked(false);
179  }
180 
181public:
182  /// Create a success value.
183  static ErrorSuccess success();
184 
185  // Errors are not copy-constructable.
186  Error(const Error &Other) = delete;
187 
188  /// Move-construct an error value. The newly constructed error is considered
189  /// unchecked, even if the source error had been checked. The original error
190  /// becomes a checked Success value, regardless of its original state.
191  Error(Error &&Other) {
192    setChecked(true);
193    *this = std::move(Other);
194  }
195 
196  /// Create an error value. Prefer using the 'make_error' function, but
197  /// this constructor can be useful when "re-throwing" errors from handlers.
198  Error(std::unique_ptr<ErrorInfoBase> Payload) {
199    setPtr(Payload.release());
200    setChecked(false);
201  }
202 
203  // Errors are not copy-assignable.
204  Error &operator=(const Error &Other) = delete;
205 
206  /// Move-assign an error value. The current error must represent success, you
207  /// you cannot overwrite an unhandled error. The current error is then
208  /// considered unchecked. The source error becomes a checked success value,
209  /// regardless of its original state.
210  Error &operator=(Error &&Other) {
211    // Don't allow overwriting of unchecked values.
212    assertIsChecked();
213    setPtr(Other.getPtr());
214 
215    // This Error is unchecked, even if the source error was checked.
216    setChecked(false);
217 
218    // Null out Other's payload and set its checked bit.
219    Other.setPtr(nullptr);
220    Other.setChecked(true);
221 
222    return *this;
223  }
224 
225  /// Destroy a Error. Fails with a call to abort() if the error is
226  /// unchecked.
227  ~Error() {
228    assertIsChecked();
229    delete getPtr();
230  }
231 
232  /// Bool conversion. Returns true if this Error is in a failure state,
233  /// and false if it is in an accept state. If the error is in a Success state
234  /// it will be considered checked.
235  explicit operator bool() {
236    setChecked(getPtr() == nullptr);
237    return getPtr() != nullptr;
20
←
Returning zero, which participates in a condition later→
238  }
239 
240  /// Check whether one error is a subclass of another.
241  template <typename ErrT> bool isA() const {
242    return getPtr() && getPtr()->isA(ErrT::classID());
243  }
244 
245  /// Returns the dynamic class id of this error, or null if this is a success
246  /// value.
247  const void* dynamicClassID() const {
248    if (!getPtr())
249      return nullptr;
250    return getPtr()->dynamicClassID();
251  }
252 
253private:
254#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
255  // assertIsChecked() happens very frequently, but under normal circumstances
256  // is supposed to be a no-op.  So we want it to be inlined, but having a bunch
257  // of debug prints can cause the function to be too large for inlining.  So
258  // it's important that we define this function out of line so that it can't be
259  // inlined.
260  LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn))
261  void fatalUncheckedError() const;
262#endif
263 
264  void assertIsChecked() {
265#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
266    if (LLVM_UNLIKELY(!getChecked() || getPtr())__builtin_expect((bool)(!getChecked() || getPtr()), false))
267      fatalUncheckedError();
268#endif
269  }
270 
271  ErrorInfoBase *getPtr() const {
272#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
273    return reinterpret_cast<ErrorInfoBase*>(
274             reinterpret_cast<uintptr_t>(Payload) &
275             ~static_cast<uintptr_t>(0x1));
276#else
277    return Payload;
278#endif
279  }
280 
281  void setPtr(ErrorInfoBase *EI) {
282#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
283    Payload = reinterpret_cast<ErrorInfoBase*>(
284                (reinterpret_cast<uintptr_t>(EI) &
285                 ~static_cast<uintptr_t>(0x1)) |
286                (reinterpret_cast<uintptr_t>(Payload) & 0x1));
287#else
288    Payload = EI;
289#endif
290  }
291 
292  bool getChecked() const {
293#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
294    return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
295#else
296    return true;
297#endif
298  }
299 
300  void setChecked(bool V) {
301#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
302    Payload = reinterpret_cast<ErrorInfoBase*>(
303                (reinterpret_cast<uintptr_t>(Payload) &
304                  ~static_cast<uintptr_t>(0x1)) |
305                  (V ? 0 : 1));
306#endif
307  }
308 
309  std::unique_ptr<ErrorInfoBase> takePayload() {
310    std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
311    setPtr(nullptr);
312    setChecked(true);
313    return Tmp;
314  }
315 
316  friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) {
317    if (auto P = E.getPtr())
318      P->log(OS);
319    else
320      OS << "success";
321    return OS;
322  }
323 
324  ErrorInfoBase *Payload = nullptr;
325};
326 
327/// Subclass of Error for the sole purpose of identifying the success path in
328/// the type system. This allows to catch invalid conversion to Expected<T> at
329/// compile time.
330class ErrorSuccess final : public Error {};
331 
332inline ErrorSuccess Error::success() { return ErrorSuccess(); }
333 
334/// Make a Error instance representing failure using the given error info
335/// type.
336template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
337  return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
338}
339 
340/// Base class for user error types. Users should declare their error types
341/// like:
342///
343/// class MyError : public ErrorInfo<MyError> {
344///   ....
345/// };
346///
347/// This class provides an implementation of the ErrorInfoBase::kind
348/// method, which is used by the Error RTTI system.
349template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
350class ErrorInfo : public ParentErrT {
351public:
352  using ParentErrT::ParentErrT; // inherit constructors
353 
354  static const void *classID() { return &ThisErrT::ID; }
355 
356  const void *dynamicClassID() const override { return &ThisErrT::ID; }
357 
358  bool isA(const void *const ClassID) const override {
359    return ClassID == classID() || ParentErrT::isA(ClassID);
360  }
361};
362 
363/// Special ErrorInfo subclass representing a list of ErrorInfos.
364/// Instances of this class are constructed by joinError.
365class ErrorList final : public ErrorInfo<ErrorList> {
366  // handleErrors needs to be able to iterate the payload list of an
367  // ErrorList.
368  template <typename... HandlerTs>
369  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
370 
371  // joinErrors is implemented in terms of join.
372  friend Error joinErrors(Error, Error);
373 
374public:
375  void log(raw_ostream &OS) const override {
376    OS << "Multiple errors:\n";
377    for (auto &ErrPayload : Payloads) {
378      ErrPayload->log(OS);
379      OS << "\n";
380    }
381  }
382 
383  std::error_code convertToErrorCode() const override;
384 
385  // Used by ErrorInfo::classID.
386  static char ID;
387 
388private:
389  ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
390            std::unique_ptr<ErrorInfoBase> Payload2) {
391    assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&((void)0)
392           "ErrorList constructor payloads should be singleton errors")((void)0);
393    Payloads.push_back(std::move(Payload1));
394    Payloads.push_back(std::move(Payload2));
395  }
396 
397  static Error join(Error E1, Error E2) {
398    if (!E1)
399      return E2;
400    if (!E2)
401      return E1;
402    if (E1.isA<ErrorList>()) {
403      auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
404      if (E2.isA<ErrorList>()) {
405        auto E2Payload = E2.takePayload();
406        auto &E2List = static_cast<ErrorList &>(*E2Payload);
407        for (auto &Payload : E2List.Payloads)
408          E1List.Payloads.push_back(std::move(Payload));
409      } else
410        E1List.Payloads.push_back(E2.takePayload());
411 
412      return E1;
413    }
414    if (E2.isA<ErrorList>()) {
415      auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
416      E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
417      return E2;
418    }
419    return Error(std::unique_ptr<ErrorList>(
420        new ErrorList(E1.takePayload(), E2.takePayload())));
421  }
422 
423  std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
424};
425 
426/// Concatenate errors. The resulting Error is unchecked, and contains the
427/// ErrorInfo(s), if any, contained in E1, followed by the
428/// ErrorInfo(s), if any, contained in E2.
429inline Error joinErrors(Error E1, Error E2) {
430  return ErrorList::join(std::move(E1), std::move(E2));
431}
432 
433/// Tagged union holding either a T or a Error.
434///
435/// This class parallels ErrorOr, but replaces error_code with Error. Since
436/// Error cannot be copied, this class replaces getError() with
437/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
438/// error class type.
439///
440/// Example usage of 'Expected<T>' as a function return type:
441///
442///   @code{.cpp}
443///     Expected<int> myDivide(int A, int B) {
444///       if (B == 0) {
445///         // return an Error
446///         return createStringError(inconvertibleErrorCode(),
447///                                  "B must not be zero!");
448///       }
449///       // return an integer
450///       return A / B;
451///     }
452///   @endcode
453///
454///   Checking the results of to a function returning 'Expected<T>':
455///   @code{.cpp}
456///     if (auto E = Result.takeError()) {
457///       // We must consume the error. Typically one of:
458///       // - return the error to our caller
459///       // - toString(), when logging
460///       // - consumeError(), to silently swallow the error
461///       // - handleErrors(), to distinguish error types
462///       errs() << "Problem with division " << toString(std::move(E)) << "\n";
463///       return;
464///     }
465///     // use the result
466///     outs() << "The answer is " << *Result << "\n";
467///   @endcode
468///
469///  For unit-testing a function returning an 'Expceted<T>', see the
470///  'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h
471 
472template <class T> class LLVM_NODISCARD[[clang::warn_unused_result]] Expected {
473  template <class T1> friend class ExpectedAsOutParameter;
474  template <class OtherT> friend class Expected;
475 
476  static constexpr bool isRef = std::is_reference<T>::value;
477 
478  using wrap = std::reference_wrapper<std::remove_reference_t<T>>;
479 
480  using error_type = std::unique_ptr<ErrorInfoBase>;
481 
482public:
483  using storage_type = std::conditional_t<isRef, wrap, T>;
484  using value_type = T;
485 
486private:
487  using reference = std::remove_reference_t<T> &;
488  using const_reference = const std::remove_reference_t<T> &;
489  using pointer = std::remove_reference_t<T> *;
490  using const_pointer = const std::remove_reference_t<T> *;
491 
492public:
493  /// Create an Expected<T> error value from the given Error.
494  Expected(Error Err)
495      : HasError(true)
496#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
497        // Expected is unchecked upon construction in Debug builds.
498        , Unchecked(true)
499#endif
500  {
501    assert(Err && "Cannot create Expected<T> from Error success value.")((void)0);
502    new (getErrorStorage()) error_type(Err.takePayload());
503  }
504 
505  /// Forbid to convert from Error::success() implicitly, this avoids having
506  /// Expected<T> foo() { return Error::success(); } which compiles otherwise
507  /// but triggers the assertion above.
508  Expected(ErrorSuccess) = delete;
509 
510  /// Create an Expected<T> success value from the given OtherT value, which
511  /// must be convertible to T.
512  template <typename OtherT>
513  Expected(OtherT &&Val,
514           std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr)
515      : HasError(false)
516#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
517        // Expected is unchecked upon construction in Debug builds.
518        ,
519        Unchecked(true)
520#endif
521  {
522    new (getStorage()) storage_type(std::forward<OtherT>(Val));
523  }
524 
525  /// Move construct an Expected<T> value.
526  Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
527 
528  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
529  /// must be convertible to T.
530  template <class OtherT>
531  Expected(
532      Expected<OtherT> &&Other,
533      std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) {
534    moveConstruct(std::move(Other));
535  }
536 
537  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
538  /// isn't convertible to T.
539  template <class OtherT>
540  explicit Expected(
541      Expected<OtherT> &&Other,
542      std::enable_if_t<!std::is_convertible<OtherT, T>::value> * = nullptr) {
543    moveConstruct(std::move(Other));
544  }
545 
546  /// Move-assign from another Expected<T>.
547  Expected &operator=(Expected &&Other) {
548    moveAssign(std::move(Other));
549    return *this;
550  }
551 
552  /// Destroy an Expected<T>.
553  ~Expected() {
554    assertIsChecked();
555    if (!HasError)
556      getStorage()->~storage_type();
557    else
558      getErrorStorage()->~error_type();
559  }
560 
561  /// Return false if there is an error.
562  explicit operator bool() {
563#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
564    Unchecked = HasError;
565#endif
566    return !HasError;
567  }
568 
569  /// Returns a reference to the stored T value.
570  reference get() {
571    assertIsChecked();
572    return *getStorage();
573  }
574 
575  /// Returns a const reference to the stored T value.
576  const_reference get() const {
577    assertIsChecked();
578    return const_cast<Expected<T> *>(this)->get();
579  }
580 
581  /// Check that this Expected<T> is an error of type ErrT.
582  template <typename ErrT> bool errorIsA() const {
583    return HasError && (*getErrorStorage())->template isA<ErrT>();
584  }
585 
586  /// Take ownership of the stored error.
587  /// After calling this the Expected<T> is in an indeterminate state that can
588  /// only be safely destructed. No further calls (beside the destructor) should
589  /// be made on the Expected<T> value.
590  Error takeError() {
591#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
592    Unchecked = false;
593#endif
594    return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
595  }
596 
597  /// Returns a pointer to the stored T value.
598  pointer operator->() {
599    assertIsChecked();
600    return toPointer(getStorage());
601  }
602 
603  /// Returns a const pointer to the stored T value.
604  const_pointer operator->() const {
605    assertIsChecked();
606    return toPointer(getStorage());
607  }
608 
609  /// Returns a reference to the stored T value.
610  reference operator*() {
611    assertIsChecked();
612    return *getStorage();
613  }
614 
615  /// Returns a const reference to the stored T value.
616  const_reference operator*() const {
617    assertIsChecked();
618    return *getStorage();
619  }
620 
621private:
622  template <class T1>
623  static bool compareThisIfSameType(const T1 &a, const T1 &b) {
624    return &a == &b;
625  }
626 
627  template <class T1, class T2>
628  static bool compareThisIfSameType(const T1 &, const T2 &) {
629    return false;
630  }
631 
632  template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
633    HasError = Other.HasError;
634#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
635    Unchecked = true;
636    Other.Unchecked = false;
637#endif
638 
639    if (!HasError)
640      new (getStorage()) storage_type(std::move(*Other.getStorage()));
641    else
642      new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
643  }
644 
645  template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
646    assertIsChecked();
647 
648    if (compareThisIfSameType(*this, Other))
649      return;
650 
651    this->~Expected();
652    new (this) Expected(std::move(Other));
653  }
654 
655  pointer toPointer(pointer Val) { return Val; }
656 
657  const_pointer toPointer(const_pointer Val) const { return Val; }
658 
659  pointer toPointer(wrap *Val) { return &Val->get(); }
660 
661  const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
662 
663  storage_type *getStorage() {
664    assert(!HasError && "Cannot get value when an error exists!")((void)0);
665    return reinterpret_cast<storage_type *>(&TStorage);
666  }
667 
668  const storage_type *getStorage() const {
669    assert(!HasError && "Cannot get value when an error exists!")((void)0);
670    return reinterpret_cast<const storage_type *>(&TStorage);
671  }
672 
673  error_type *getErrorStorage() {
674    assert(HasError && "Cannot get error when a value exists!")((void)0);
675    return reinterpret_cast<error_type *>(&ErrorStorage);
676  }
677 
678  const error_type *getErrorStorage() const {
679    assert(HasError && "Cannot get error when a value exists!")((void)0);
680    return reinterpret_cast<const error_type *>(&ErrorStorage);
681  }
682 
683  // Used by ExpectedAsOutParameter to reset the checked flag.
684  void setUnchecked() {
685#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
686    Unchecked = true;
687#endif
688  }
689 
690#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
691  LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn))
692  LLVM_ATTRIBUTE_NOINLINE__attribute__((noinline))
693  void fatalUncheckedExpected() const {
694    dbgs() << "Expected<T> must be checked before access or destruction.\n";
695    if (HasError) {
696      dbgs() << "Unchecked Expected<T> contained error:\n";
697      (*getErrorStorage())->log(dbgs());
698    } else
699      dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
700                "values in success mode must still be checked prior to being "
701                "destroyed).\n";
702    abort();
703  }
704#endif
705 
706  void assertIsChecked() const {
707#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
708    if (LLVM_UNLIKELY(Unchecked)__builtin_expect((bool)(Unchecked), false))
709      fatalUncheckedExpected();
710#endif
711  }
712 
713  union {
714    AlignedCharArrayUnion<storage_type> TStorage;
715    AlignedCharArrayUnion<error_type> ErrorStorage;
716  };
717  bool HasError : 1;
718#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
719  bool Unchecked : 1;
720#endif
721};
722 
723/// Report a serious error, calling any installed error handler. See
724/// ErrorHandling.h.
725LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn)) void report_fatal_error(Error Err,
726                                                bool gen_crash_diag = true);
727 
728/// Report a fatal error if Err is a failure value.
729///
730/// This function can be used to wrap calls to fallible functions ONLY when it
731/// is known that the Error will always be a success value. E.g.
732///
733///   @code{.cpp}
734///   // foo only attempts the fallible operation if DoFallibleOperation is
735///   // true. If DoFallibleOperation is false then foo always returns
736///   // Error::success().
737///   Error foo(bool DoFallibleOperation);
738///
739///   cantFail(foo(false));
740///   @endcode
741inline void cantFail(Error Err, const char *Msg = nullptr) {
742  if (Err) {
743    if (!Msg)
744      Msg = "Failure value returned from cantFail wrapped call";
745#ifndef NDEBUG1
746    std::string Str;
747    raw_string_ostream OS(Str);
748    OS << Msg << "\n" << Err;
749    Msg = OS.str().c_str();
750#endif
751    llvm_unreachable(Msg)__builtin_unreachable();
752  }
753}
754 
755/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
756/// returns the contained value.
757///
758/// This function can be used to wrap calls to fallible functions ONLY when it
759/// is known that the Error will always be a success value. E.g.
760///
761///   @code{.cpp}
762///   // foo only attempts the fallible operation if DoFallibleOperation is
763///   // true. If DoFallibleOperation is false then foo always returns an int.
764///   Expected<int> foo(bool DoFallibleOperation);
765///
766///   int X = cantFail(foo(false));
767///   @endcode
768template <typename T>
769T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
770  if (ValOrErr)
771    return std::move(*ValOrErr);
772  else {
773    if (!Msg)
774      Msg = "Failure value returned from cantFail wrapped call";
775#ifndef NDEBUG1
776    std::string Str;
777    raw_string_ostream OS(Str);
778    auto E = ValOrErr.takeError();
779    OS << Msg << "\n" << E;
780    Msg = OS.str().c_str();
781#endif
782    llvm_unreachable(Msg)__builtin_unreachable();
783  }
784}
785 
786/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
787/// returns the contained reference.
788///
789/// This function can be used to wrap calls to fallible functions ONLY when it
790/// is known that the Error will always be a success value. E.g.
791///
792///   @code{.cpp}
793///   // foo only attempts the fallible operation if DoFallibleOperation is
794///   // true. If DoFallibleOperation is false then foo always returns a Bar&.
795///   Expected<Bar&> foo(bool DoFallibleOperation);
796///
797///   Bar &X = cantFail(foo(false));
798///   @endcode
799template <typename T>
800T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
801  if (ValOrErr)
802    return *ValOrErr;
803  else {
804    if (!Msg)
805      Msg = "Failure value returned from cantFail wrapped call";
806#ifndef NDEBUG1
807    std::string Str;
808    raw_string_ostream OS(Str);
809    auto E = ValOrErr.takeError();
810    OS << Msg << "\n" << E;
811    Msg = OS.str().c_str();
812#endif
813    llvm_unreachable(Msg)__builtin_unreachable();
814  }
815}
816 
817/// Helper for testing applicability of, and applying, handlers for
818/// ErrorInfo types.
819template <typename HandlerT>
820class ErrorHandlerTraits
821    : public ErrorHandlerTraits<decltype(
822          &std::remove_reference<HandlerT>::type::operator())> {};
823 
824// Specialization functions of the form 'Error (const ErrT&)'.
825template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
826public:
827  static bool appliesTo(const ErrorInfoBase &E) {
828    return E.template isA<ErrT>();
829  }
830 
831  template <typename HandlerT>
832  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
833    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
834    return H(static_cast<ErrT &>(*E));
835  }
836};
837 
838// Specialization functions of the form 'void (const ErrT&)'.
839template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
840public:
841  static bool appliesTo(const ErrorInfoBase &E) {
842    return E.template isA<ErrT>();
843  }
844 
845  template <typename HandlerT>
846  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
847    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
848    H(static_cast<ErrT &>(*E));
849    return Error::success();
850  }
851};
852 
853/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
854template <typename ErrT>
855class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
856public:
857  static bool appliesTo(const ErrorInfoBase &E) {
858    return E.template isA<ErrT>();
859  }
860 
861  template <typename HandlerT>
862  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
863    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
864    std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
865    return H(std::move(SubE));
866  }
867};
868 
869/// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
870template <typename ErrT>
871class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
872public:
873  static bool appliesTo(const ErrorInfoBase &E) {
874    return E.template isA<ErrT>();
875  }
876 
877  template <typename HandlerT>
878  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
879    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
880    std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
881    H(std::move(SubE));
882    return Error::success();
883  }
884};
885 
886// Specialization for member functions of the form 'RetT (const ErrT&)'.
887template <typename C, typename RetT, typename ErrT>
888class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
889    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
890 
891// Specialization for member functions of the form 'RetT (const ErrT&) const'.
892template <typename C, typename RetT, typename ErrT>
893class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
894    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
895 
896// Specialization for member functions of the form 'RetT (const ErrT&)'.
897template <typename C, typename RetT, typename ErrT>
898class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
899    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
900 
901// Specialization for member functions of the form 'RetT (const ErrT&) const'.
902template <typename C, typename RetT, typename ErrT>
903class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
904    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
905 
906/// Specialization for member functions of the form
907/// 'RetT (std::unique_ptr<ErrT>)'.
908template <typename C, typename RetT, typename ErrT>
909class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
910    : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
911 
912/// Specialization for member functions of the form
913/// 'RetT (std::unique_ptr<ErrT>) const'.
914template <typename C, typename RetT, typename ErrT>
915class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
916    : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
917 
918inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
919  return Error(std::move(Payload));
920}
921 
922template <typename HandlerT, typename... HandlerTs>
923Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
924                      HandlerT &&Handler, HandlerTs &&... Handlers) {
925  if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload))
926    return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
927                                               std::move(Payload));
928  return handleErrorImpl(std::move(Payload),
929                         std::forward<HandlerTs>(Handlers)...);
930}
931 
932/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
933/// unhandled errors (or Errors returned by handlers) are re-concatenated and
934/// returned.
935/// Because this function returns an error, its result must also be checked
936/// or returned. If you intend to handle all errors use handleAllErrors
937/// (which returns void, and will abort() on unhandled errors) instead.
938template <typename... HandlerTs>
939Error handleErrors(Error E, HandlerTs &&... Hs) {
940  if (!E)
941    return Error::success();
942 
943  std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
944 
945  if (Payload->isA<ErrorList>()) {
946    ErrorList &List = static_cast<ErrorList &>(*Payload);
947    Error R;
948    for (auto &P : List.Payloads)
949      R = ErrorList::join(
950          std::move(R),
951          handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
952    return R;
953  }
954 
955  return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
956}
957 
958/// Behaves the same as handleErrors, except that by contract all errors
959/// *must* be handled by the given handlers (i.e. there must be no remaining
960/// errors after running the handlers, or llvm_unreachable is called).
961template <typename... HandlerTs>
962void handleAllErrors(Error E, HandlerTs &&... Handlers) {
963  cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
964}
965 
966/// Check that E is a non-error, then drop it.
967/// If E is an error, llvm_unreachable will be called.
968inline void handleAllErrors(Error E) {
969  cantFail(std::move(E));
970}
971 
972/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
973///
974/// If the incoming value is a success value it is returned unmodified. If it
975/// is a failure value then it the contained error is passed to handleErrors.
976/// If handleErrors is able to handle the error then the RecoveryPath functor
977/// is called to supply the final result. If handleErrors is not able to
978/// handle all errors then the unhandled errors are returned.
979///
980/// This utility enables the follow pattern:
981///
982///   @code{.cpp}
983///   enum FooStrategy { Aggressive, Conservative };
984///   Expected<Foo> foo(FooStrategy S);
985///
986///   auto ResultOrErr =
987///     handleExpected(
988///       foo(Aggressive),
989///       []() { return foo(Conservative); },
990///       [](AggressiveStrategyError&) {
991///         // Implicitly conusme this - we'll recover by using a conservative
992///         // strategy.
993///       });
994///
995///   @endcode
996template <typename T, typename RecoveryFtor, typename... HandlerTs>
997Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
998                           HandlerTs &&... Handlers) {
999  if (ValOrErr)
1000    return ValOrErr;
1001 
1002  if (auto Err = handleErrors(ValOrErr.takeError(),
1003                              std::forward<HandlerTs>(Handlers)...))
1004    return std::move(Err);
1005 
1006  return RecoveryPath();
1007}
1008 
1009/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
1010/// will be printed before the first one is logged. A newline will be printed
1011/// after each error.
1012///
1013/// This function is compatible with the helpers from Support/WithColor.h. You
1014/// can pass any of them as the OS. Please consider using them instead of
1015/// including 'error: ' in the ErrorBanner.
1016///
1017/// This is useful in the base level of your program to allow clean termination
1018/// (allowing clean deallocation of resources, etc.), while reporting error
1019/// information to the user.
1020void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {});
1021 
1022/// Write all error messages (if any) in E to a string. The newline character
1023/// is used to separate error messages.
1024inline std::string toString(Error E) {
1025  SmallVector<std::string, 2> Errors;
1026  handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) {
1027    Errors.push_back(EI.message());
1028  });
1029  return join(Errors.begin(), Errors.end(), "\n");
1030}
1031 
1032/// Consume a Error without doing anything. This method should be used
1033/// only where an error can be considered a reasonable and expected return
1034/// value.
1035///
1036/// Uses of this method are potentially indicative of design problems: If it's
1037/// legitimate to do nothing while processing an "error", the error-producer
1038/// might be more clearly refactored to return an Optional<T>.
1039inline void consumeError(Error Err) {
1040  handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
1041}
1042 
1043/// Convert an Expected to an Optional without doing anything. This method
1044/// should be used only where an error can be considered a reasonable and
1045/// expected return value.
1046///
1047/// Uses of this method are potentially indicative of problems: perhaps the
1048/// error should be propagated further, or the error-producer should just
1049/// return an Optional in the first place.
1050template <typename T> Optional<T> expectedToOptional(Expected<T> &&E) {
1051  if (E)
1052    return std::move(*E);
1053  consumeError(E.takeError());
1054  return None;
1055}
1056 
1057/// Helper for converting an Error to a bool.
1058///
1059/// This method returns true if Err is in an error state, or false if it is
1060/// in a success state.  Puts Err in a checked state in both cases (unlike
1061/// Error::operator bool(), which only does this for success states).
1062inline bool errorToBool(Error Err) {
1063  bool IsError = static_cast<bool>(Err);
1064  if (IsError)
1065    consumeError(std::move(Err));
1066  return IsError;
1067}
1068 
1069/// Helper for Errors used as out-parameters.
1070///
1071/// This helper is for use with the Error-as-out-parameter idiom, where an error
1072/// is passed to a function or method by reference, rather than being returned.
1073/// In such cases it is helpful to set the checked bit on entry to the function
1074/// so that the error can be written to (unchecked Errors abort on assignment)
1075/// and clear the checked bit on exit so that clients cannot accidentally forget
1076/// to check the result. This helper performs these actions automatically using
1077/// RAII:
1078///
1079///   @code{.cpp}
1080///   Result foo(Error &Err) {
1081///     ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
1082///     // <body of foo>
1083///     // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
1084///   }
1085///   @endcode
1086///
1087/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
1088/// used with optional Errors (Error pointers that are allowed to be null). If
1089/// ErrorAsOutParameter took an Error reference, an instance would have to be
1090/// created inside every condition that verified that Error was non-null. By
1091/// taking an Error pointer we can just create one instance at the top of the
1092/// function.
1093class ErrorAsOutParameter {
1094public:
1095  ErrorAsOutParameter(Error *Err) : Err(Err) {
1096    // Raise the checked bit if Err is success.
1097    if (Err)
1098      (void)!!*Err;
1099  }
1100 
1101  ~ErrorAsOutParameter() {
1102    // Clear the checked bit.
1103    if (Err && !*Err)
1104      *Err = Error::success();
1105  }
1106 
1107private:
1108  Error *Err;
1109};
1110 
1111/// Helper for Expected<T>s used as out-parameters.
1112///
1113/// See ErrorAsOutParameter.
1114template <typename T>
1115class ExpectedAsOutParameter {
1116public:
1117  ExpectedAsOutParameter(Expected<T> *ValOrErr)
1118    : ValOrErr(ValOrErr) {
1119    if (ValOrErr)
1120      (void)!!*ValOrErr;
1121  }
1122 
1123  ~ExpectedAsOutParameter() {
1124    if (ValOrErr)
1125      ValOrErr->setUnchecked();
1126  }
1127 
1128private:
1129  Expected<T> *ValOrErr;
1130};
1131 
1132/// This class wraps a std::error_code in a Error.
1133///
1134/// This is useful if you're writing an interface that returns a Error
1135/// (or Expected) and you want to call code that still returns
1136/// std::error_codes.
1137class ECError : public ErrorInfo<ECError> {
1138  friend Error errorCodeToError(std::error_code);
1139 
1140  virtual void anchor() override;
1141 
1142public:
1143  void setErrorCode(std::error_code EC) { this->EC = EC; }
1144  std::error_code convertToErrorCode() const override { return EC; }
1145  void log(raw_ostream &OS) const override { OS << EC.message(); }
1146 
1147  // Used by ErrorInfo::classID.
1148  static char ID;
1149 
1150protected:
1151  ECError() = default;
1152  ECError(std::error_code EC) : EC(EC) {}
1153 
1154  std::error_code EC;
1155};
1156 
1157/// The value returned by this function can be returned from convertToErrorCode
1158/// for Error values where no sensible translation to std::error_code exists.
1159/// It should only be used in this situation, and should never be used where a
1160/// sensible conversion to std::error_code is available, as attempts to convert
1161/// to/from this error will result in a fatal error. (i.e. it is a programmatic
1162///error to try to convert such a value).
1163std::error_code inconvertibleErrorCode();
1164 
1165/// Helper for converting an std::error_code to a Error.
1166Error errorCodeToError(std::error_code EC);
1167 
1168/// Helper for converting an ECError to a std::error_code.
1169///
1170/// This method requires that Err be Error() or an ECError, otherwise it
1171/// will trigger a call to abort().
1172std::error_code errorToErrorCode(Error Err);
1173 
1174/// Convert an ErrorOr<T> to an Expected<T>.
1175template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1176  if (auto EC = EO.getError())
1177    return errorCodeToError(EC);
1178  return std::move(*EO);
1179}
1180 
1181/// Convert an Expected<T> to an ErrorOr<T>.
1182template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1183  if (auto Err = E.takeError())
1184    return errorToErrorCode(std::move(Err));
1185  return std::move(*E);
1186}
1187 
1188/// This class wraps a string in an Error.
1189///
1190/// StringError is useful in cases where the client is not expected to be able
1191/// to consume the specific error message programmatically (for example, if the
1192/// error message is to be presented to the user).
1193///
1194/// StringError can also be used when additional information is to be printed
1195/// along with a error_code message. Depending on the constructor called, this
1196/// class can either display:
1197///    1. the error_code message (ECError behavior)
1198///    2. a string
1199///    3. the error_code message and a string
1200///
1201/// These behaviors are useful when subtyping is required; for example, when a
1202/// specific library needs an explicit error type. In the example below,
1203/// PDBError is derived from StringError:
1204///
1205///   @code{.cpp}
1206///   Expected<int> foo() {
1207///      return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading,
1208///                                        "Additional information");
1209///   }
1210///   @endcode
1211///
1212class StringError : public ErrorInfo<StringError> {
1213public:
1214  static char ID;
1215 
1216  // Prints EC + S and converts to EC
1217  StringError(std::error_code EC, const Twine &S = Twine());
1218 
1219  // Prints S and converts to EC
1220  StringError(const Twine &S, std::error_code EC);
1221 
1222  void log(raw_ostream &OS) const override;
1223  std::error_code convertToErrorCode() const override;
1224 
1225  const std::string &getMessage() const { return Msg; }
1226 
1227private:
1228  std::string Msg;
1229  std::error_code EC;
1230  const bool PrintMsgOnly = false;
1231};
1232 
1233/// Create formatted StringError object.
1234template <typename... Ts>
1235inline Error createStringError(std::error_code EC, char const *Fmt,
1236                               const Ts &... Vals) {
1237  std::string Buffer;
1238  raw_string_ostream Stream(Buffer);
1239  Stream << format(Fmt, Vals...);
1240  return make_error<StringError>(Stream.str(), EC);
1241}
1242 
1243Error createStringError(std::error_code EC, char const *Msg);
1244 
1245inline Error createStringError(std::error_code EC, const Twine &S) {
1246  return createStringError(EC, S.str().c_str());
1247}
1248 
1249template <typename... Ts>
1250inline Error createStringError(std::errc EC, char const *Fmt,
1251                               const Ts &... Vals) {
1252  return createStringError(std::make_error_code(EC), Fmt, Vals...);
1253}
1254 
1255/// This class wraps a filename and another Error.
1256///
1257/// In some cases, an error needs to live along a 'source' name, in order to
1258/// show more detailed information to the user.
1259class FileError final : public ErrorInfo<FileError> {
1260 
1261  friend Error createFileError(const Twine &, Error);
1262  friend Error createFileError(const Twine &, size_t, Error);
1263 
1264public:
1265  void log(raw_ostream &OS) const override {
1266    assert(Err && !FileName.empty() && "Trying to log after takeError().")((void)0);
1267    OS << "'" << FileName << "': ";
1268    if (Line.hasValue())
1269      OS << "line " << Line.getValue() << ": ";
1270    Err->log(OS);
1271  }
1272 
1273  StringRef getFileName() { return FileName; }
1274 
1275  Error takeError() { return Error(std::move(Err)); }
1276 
1277  std::error_code convertToErrorCode() const override;
1278 
1279  // Used by ErrorInfo::classID.
1280  static char ID;
1281 
1282private:
1283  FileError(const Twine &F, Optional<size_t> LineNum,
1284            std::unique_ptr<ErrorInfoBase> E) {
1285    assert(E && "Cannot create FileError from Error success value.")((void)0);
1286    assert(!F.isTriviallyEmpty() &&((void)0)
1287           "The file name provided to FileError must not be empty.")((void)0);
1288    FileName = F.str();
1289    Err = std::move(E);
1290    Line = std::move(LineNum);
1291  }
1292 
1293  static Error build(const Twine &F, Optional<size_t> Line, Error E) {
1294    std::unique_ptr<ErrorInfoBase> Payload;
1295    handleAllErrors(std::move(E),
1296                    [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error {
1297                      Payload = std::move(EIB);
1298                      return Error::success();
1299                    });
1300    return Error(
1301        std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload))));
1302  }
1303 
1304  std::string FileName;
1305  Optional<size_t> Line;
1306  std::unique_ptr<ErrorInfoBase> Err;
1307};
1308 
1309/// Concatenate a source file path and/or name with an Error. The resulting
1310/// Error is unchecked.
1311inline Error createFileError(const Twine &F, Error E) {
1312  return FileError::build(F, Optional<size_t>(), std::move(E));
1313}
1314 
1315/// Concatenate a source file path and/or name with line number and an Error.
1316/// The resulting Error is unchecked.
1317inline Error createFileError(const Twine &F, size_t Line, Error E) {
1318  return FileError::build(F, Optional<size_t>(Line), std::move(E));
1319}
1320 
1321/// Concatenate a source file path and/or name with a std::error_code 
1322/// to form an Error object.
1323inline Error createFileError(const Twine &F, std::error_code EC) {
1324  return createFileError(F, errorCodeToError(EC));
1325}
1326 
1327/// Concatenate a source file path and/or name with line number and
1328/// std::error_code to form an Error object.
1329inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) {
1330  return createFileError(F, Line, errorCodeToError(EC));
1331}
1332 
1333Error createFileError(const Twine &F, ErrorSuccess) = delete;
1334 
1335/// Helper for check-and-exit error handling.
1336///
1337/// For tool use only. NOT FOR USE IN LIBRARY CODE.
1338///
1339class ExitOnError {
1340public:
1341  /// Create an error on exit helper.
1342  ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
1343      : Banner(std::move(Banner)),
1344        GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1345 
1346  /// Set the banner string for any errors caught by operator().
1347  void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1348 
1349  /// Set the exit-code mapper function.
1350  void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1351    this->GetExitCode = std::move(GetExitCode);
1352  }
1353 
1354  /// Check Err. If it's in a failure state log the error(s) and exit.
1355  void operator()(Error Err) const { checkError(std::move(Err)); }
1356 
1357  /// Check E. If it's in a success state then return the contained value. If
1358  /// it's in a failure state log the error(s) and exit.
1359  template <typename T> T operator()(Expected<T> &&E) const {
1360    checkError(E.takeError());
1361    return std::move(*E);
1362  }
1363 
1364  /// Check E. If it's in a success state then return the contained reference. If
1365  /// it's in a failure state log the error(s) and exit.
1366  template <typename T> T& operator()(Expected<T&> &&E) const {
1367    checkError(E.takeError());
1368    return *E;
1369  }
1370 
1371private:
1372  void checkError(Error Err) const {
1373    if (Err) {
1374      int ExitCode = GetExitCode(Err);
1375      logAllUnhandledErrors(std::move(Err), errs(), Banner);
1376      exit(ExitCode);
1377    }
1378  }
1379 
1380  std::string Banner;
1381  std::function<int(const Error &)> GetExitCode;
1382};
1383 
1384/// Conversion from Error to LLVMErrorRef for C error bindings.
1385inline LLVMErrorRef wrap(Error Err) {
1386  return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
1387}
1388 
1389/// Conversion from LLVMErrorRef to Error for C error bindings.
1390inline Error unwrap(LLVMErrorRef ErrRef) {
1391  return Error(std::unique_ptr<ErrorInfoBase>(
1392      reinterpret_cast<ErrorInfoBase *>(ErrRef)));
1393}
1394 
1395} // end namespace llvm
1396 
1397#endif // LLVM_SUPPORT_ERROR_H