text:
//===------ ModuleInterfaceLoader.cpp - Loads .swiftinterface files -------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "textual-module-interface"

#include "swift/Frontend/ModuleInterfaceLoader.h"
#include "ModuleInterfaceBuilder.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/DiagnosticsFrontend.h"
#include "swift/AST/DiagnosticsSema.h"
#include "swift/AST/FileSystem.h"
#include "swift/AST/Module.h"
#include "swift/Basic/Platform.h"
#include "swift/Frontend/Frontend.h"
#include "swift/Frontend/ModuleInterfaceSupport.h"
#include "swift/Serialization/SerializationOptions.h"
#include "swift/Serialization/Validation.h"
#include "swift/Strings.h"
#include "clang/Basic/Module.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Lex/PreprocessorOptions.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/YAMLParser.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Support/xxhash.h"

using namespace swift;
using FileDependency = SerializationOptions::FileDependency;

#pragma mark - Forwarding Modules

namespace {

/// Describes a "forwarding module", that is, a .swiftmodule that's actually
/// a YAML file inside, pointing to a the original .swiftmodule but describing
/// a different dependency resolution strategy.
struct ForwardingModule {
  /// The path to the original .swiftmodule in the prebuilt cache.
  std::string underlyingModulePath;

  /// Describes a set of file-based dependencies with their size and
  /// modification time stored. This is slightly different from
  /// \c SerializationOptions::FileDependency, because this type needs to be
  /// serializable to and from YAML.
  struct Dependency {
    std::string path;
    uint64_t size;
    uint64_t lastModificationTime;
    bool isSDKRelative;
  };
  std::vector<Dependency> dependencies;
  unsigned version = 1;

  ForwardingModule() = default;
  ForwardingModule(StringRef underlyingModulePath)
  : underlyingModulePath(underlyingModulePath) {}

  /// Loads the contents of the forwarding module whose contents lie in
  /// the provided buffer, and returns a new \c ForwardingModule, or an error
  /// if the YAML could not be parsed.
  static llvm::ErrorOr<ForwardingModule> load(const llvm::MemoryBuffer &buf);

  /// Adds a given dependency to the dependencies list.
  void addDependency(StringRef path, bool isSDKRelative, uint64_t size,
                     uint64_t modTime) {
    dependencies.push_back({path.str(), size, modTime, isSDKRelative});
  }
};

} // end anonymous namespace

#pragma mark - YAML Serialization

namespace llvm {
  namespace yaml {
    template <>
    struct MappingTraits<ForwardingModule::Dependency> {
      static void mapping(IO &io, ForwardingModule::Dependency &dep) {
        io.mapRequired("mtime", dep.lastModificationTime);
        io.mapRequired("path", dep.path);
        io.mapRequired("size", dep.size);
        io.mapOptional("sdk_relative", dep.isSDKRelative, /*default*/false);
      }
    };

    template <>
    struct SequenceElementTraits<ForwardingModule::Dependency> {
      static const bool flow = false;
    };

    template <>
    struct MappingTraits<ForwardingModule> {
      static void mapping(IO &io, ForwardingModule &module) {
        io.mapRequired("path", module.underlyingModulePath);
        io.mapRequired("dependencies", module.dependencies);
        io.mapRequired("version", module.version);
      }
    };
  }
} // end namespace llvm

llvm::ErrorOr<ForwardingModule>
ForwardingModule::load(const llvm::MemoryBuffer &buf) {
  llvm::yaml::Input yamlIn(buf.getBuffer());
  ForwardingModule fwd;
  yamlIn >> fwd;
  if (yamlIn.error())
    return yamlIn.error();

  // We only currently support Version 1 of the forwarding module format.
  if (fwd.version != 1)
    return std::make_error_code(std::errc::not_supported);
  return std::move(fwd);
}

#pragma mark - Module Discovery

namespace {

/// The result of a search for a module either alongside an interface, in the
/// module cache, or in the prebuilt module cache.
class DiscoveredModule {
  /// The kind of module we've found.
  enum class Kind {
    /// A module that's either alongside the swiftinterface or in the
    /// module cache.
    Normal,

    /// A module that resides in the prebuilt cache, and has hash-based
    /// dependencies.
    Prebuilt,

    /// A 'forwarded' module. This is a module in the prebuilt cache, but whose
    /// dependencies live in a forwarding module.
    /// \sa ForwardingModule.
    Forwarded
  };

  /// The kind of module that's been discovered.
  const Kind kind;

  DiscoveredModule(StringRef path, Kind kind,
    std::unique_ptr<llvm::MemoryBuffer> moduleBuffer)
    : kind(kind), moduleBuffer(std::move(moduleBuffer)), path(path) {}

public:
  /// The contents of the .swiftmodule, if we've read it while validating
  /// dependencies.
  std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;

  /// The path to the discovered serialized .swiftmodule on disk.
  const std::string path;

  /// Creates a \c Normal discovered module.
  static DiscoveredModule normal(StringRef path,
      std::unique_ptr<llvm::MemoryBuffer> moduleBuffer) {
    return { path, Kind::Normal, std::move(moduleBuffer) };
  }

  /// Creates a \c Prebuilt discovered module.
  static DiscoveredModule prebuilt(
      StringRef path, std::unique_ptr<llvm::MemoryBuffer> moduleBuffer) {
    return { path, Kind::Prebuilt, std::move(moduleBuffer) };
  }

  /// Creates a \c Forwarded discovered module, whose dependencies have been
  /// externally validated by a \c ForwardingModule.
  static DiscoveredModule forwarded(
      StringRef path, std::unique_ptr<llvm::MemoryBuffer> moduleBuffer) {
    return { path, Kind::Forwarded, std::move(moduleBuffer) };
  }

  bool isNormal() const { return kind == Kind::Normal; }
  bool isPrebuilt() const { return kind == Kind::Prebuilt; }
  bool isForwarded() const { return kind == Kind::Forwarded; }
};

} // end anonymous namespace

#pragma mark - Common utilities

namespace path = llvm::sys::path;

static bool serializedASTLooksValid(const llvm::MemoryBuffer &buf,
                                    bool requiresOSSAModules) {
  auto VI = serialization::validateSerializedAST(buf.getBuffer(),
                                                 requiresOSSAModules);
  return VI.status == serialization::Status::Valid;
}

#pragma mark - Module Loading

namespace {

/// Keeps track of the various reasons the module interface loader needed to
/// fall back and rebuild a module from its interface.
struct ModuleRebuildInfo {
  enum class ModuleKind {
    Normal,
    Cached,
    Forwarding,
    Prebuilt
  };
  struct OutOfDateModule {
    std::string path;
    Optional<serialization::Status> serializationStatus;
    ModuleKind kind;
    SmallVector<std::string, 10> outOfDateDependencies;
    SmallVector<std::string, 10> missingDependencies;
  };
  SmallVector<OutOfDateModule, 3> outOfDateModules;

  OutOfDateModule &getOrInsertOutOfDateModule(StringRef path) {
    for (auto &mod : outOfDateModules) {
      if (mod.path == path) return mod;
    }
    outOfDateModules.push_back({path.str(), None, ModuleKind::Normal, {}, {}});
    return outOfDateModules.back();
  }

  /// Sets the kind of a module that failed to load.
  void setModuleKind(StringRef path, ModuleKind kind) {
    getOrInsertOutOfDateModule(path).kind = kind;
  }

  /// Sets the serialization status of the module at \c path. If this is
  /// anything other than \c Valid, a note will be added stating why the module
  /// was invalid.
  void setSerializationStatus(StringRef path, serialization::Status status) {
    getOrInsertOutOfDateModule(path).serializationStatus = status;
  }

  /// Registers an out-of-date dependency at \c depPath for the module
  /// at \c modulePath.
  void addOutOfDateDependency(StringRef modulePath, StringRef depPath) {
    getOrInsertOutOfDateModule(modulePath)
        .outOfDateDependencies.push_back(depPath.str());
  }

  /// Registers a missing dependency at \c depPath for the module
  /// at \c modulePath.
  void addMissingDependency(StringRef modulePath, StringRef depPath) {
    getOrInsertOutOfDateModule(modulePath)
        .missingDependencies.push_back(depPath.str());
  }

  /// Determines if we saw the given module path and registered is as out of
  /// date.
  bool sawOutOfDateModule(StringRef modulePath) {
    for (auto &mod : outOfDateModules)
      if (mod.path == modulePath)
        return true;
    return false;
  }

  const char *invalidModuleReason(serialization::Status status) {
    using namespace serialization;
    switch (status) {
    case Status::FormatTooOld:
      return "compiled with an older version of the compiler";
    case Status::FormatTooNew:
      return "compiled with a newer version of the compiler";
    case Status::Malformed:
      return "malformed";
    case Status::TargetIncompatible:
      return "compiled for a different target platform";
    case Status::TargetTooNew:
      return "target platform newer than current platform";
    default: return nullptr;
    }
  }

  /// Emits a diagnostic for all out-of-date compiled or forwarding modules
  /// encountered while trying to load a module.
  template<typename... DiagArgs>
  void diagnose(ASTContext &ctx, DiagnosticEngine &diags,
                StringRef prebuiltCacheDir, SourceLoc loc,
                DiagArgs &&...diagArgs) {
    diags.diagnose(loc, std::forward<DiagArgs>(diagArgs)...);
    auto SDKVer = getSDKBuildVersion(ctx.SearchPathOpts.getSDKPath());
    llvm::SmallString<64> buffer = prebuiltCacheDir;
    llvm::sys::path::append(buffer, "SystemVersion.plist");
    auto PBMVer = getSDKBuildVersionFromPlist(buffer.str());
    if (!SDKVer.empty() && !PBMVer.empty()) {
      // Remark the potential version difference.
      diags.diagnose(loc, diag::sdk_version_pbm_version, SDKVer,
                         PBMVer);
    }
    // We may have found multiple failing modules, that failed for different
    // reasons. Emit a note for each of them.
    for (auto &mod : outOfDateModules) {
      diags.diagnose(loc, diag::out_of_date_module_here,
                         (unsigned)mod.kind, mod.path);

      // Diagnose any out-of-date dependencies in this module.
      for (auto &dep : mod.outOfDateDependencies) {
        diags.diagnose(loc, diag::module_interface_dependency_out_of_date,
                           dep);
      }

      // Diagnose any missing dependencies in this module.
      for (auto &dep : mod.missingDependencies) {
        diags.diagnose(loc, diag::module_interface_dependency_missing, dep);
      }

      // If there was a compiled module that wasn't able to be read, diagnose
      // the reason we couldn't read it.
      if (auto status = mod.serializationStatus) {
        if (auto reason = invalidModuleReason(*status)) {
          diags.diagnose(loc, diag::compiled_module_invalid_reason,
              mod.path, reason);
        } else {
          diags.diagnose(loc, diag::compiled_module_invalid, mod.path);
        }
      }
    }
  }
};

/// Handles the details of loading module interfaces as modules, and will
/// do the necessary lookup to determine if we should be loading from the
/// normal cache, the prebuilt cache, a module adjacent to the interface, or
/// a module that we'll build from a module interface.
class ModuleInterfaceLoaderImpl {
  friend class swift::ModuleInterfaceLoader;
  friend class swift::ModuleInterfaceCheckerImpl;
  ASTContext &ctx;
  llvm::vfs::FileSystem &fs;
  DiagnosticEngine &diags;
  ModuleRebuildInfo rebuildInfo;
  const StringRef modulePath;
  const std::string interfacePath;
  const StringRef moduleName;
  const StringRef prebuiltCacheDir;
  const StringRef backupInterfaceDir;
  const StringRef cacheDir;
  const SourceLoc diagnosticLoc;
  DependencyTracker *const dependencyTracker;
  const ModuleLoadingMode loadMode;
  ModuleInterfaceLoaderOptions Opts;
  RequireOSSAModules_t requiresOSSAModules;

  ModuleInterfaceLoaderImpl(
      ASTContext &ctx, StringRef modulePath, StringRef interfacePath,
      StringRef moduleName, StringRef cacheDir, StringRef prebuiltCacheDir,
      StringRef backupInterfaceDir,
      SourceLoc diagLoc, ModuleInterfaceLoaderOptions Opts,
      RequireOSSAModules_t requiresOSSAModules,
      DependencyTracker *dependencyTracker = nullptr,
      ModuleLoadingMode loadMode = ModuleLoadingMode::PreferSerialized)
      : ctx(ctx), fs(*ctx.SourceMgr.getFileSystem()), diags(ctx.Diags),
        modulePath(modulePath), interfacePath(interfacePath),
        moduleName(moduleName),
        prebuiltCacheDir(prebuiltCacheDir),
        backupInterfaceDir(backupInterfaceDir),
        cacheDir(cacheDir), diagnosticLoc(diagLoc),
        dependencyTracker(dependencyTracker), loadMode(loadMode), Opts(Opts),
        requiresOSSAModules(requiresOSSAModules) {}

  /// Constructs the full path of the dependency \p dep by prepending the SDK
  /// path if necessary.
  StringRef getFullDependencyPath(const FileDependency &dep,
                                  SmallVectorImpl<char> &scratch) const {
    if (!dep.isSDKRelative())
      return dep.getPath();

    path::native(ctx.SearchPathOpts.getSDKPath(), scratch);
    llvm::sys::path::append(scratch, dep.getPath());
    return StringRef(scratch.data(), scratch.size());
  }

  enum class DependencyStatus {
    UpToDate,
    OutOfDate,
    Missing
  };

  // Checks that a dependency read from the cached module is up to date compared
  // to the interface file it represents.
  DependencyStatus checkDependency(StringRef modulePath,
                                   const FileDependency &dep,
                                   StringRef fullPath) {
    auto status = fs.status(fullPath);
    if (!status)
      return DependencyStatus::Missing;

    // If the sizes differ, then we know the file has changed.
    if (status->getSize() != dep.getSize())
      return DependencyStatus::OutOfDate;

    // Otherwise, if this dependency is verified by modification time, check
    // it vs. the modification time of the file.
    if (dep.isModificationTimeBased()) {
      uint64_t mtime =
        status->getLastModificationTime().time_since_epoch().count();
      return mtime == dep.getModificationTime() ?
          DependencyStatus::UpToDate :
          DependencyStatus::OutOfDate;
    }

    // Slow path: if the dependency is verified by content hash, check it vs.
    // the hash of the file.
    auto buf = fs.getBufferForFile(fullPath, /*FileSize=*/-1,
                                   /*RequiresNullTerminator=*/false);
    if (!buf)
      return DependencyStatus::Missing;

    return xxHash64(buf.get()->getBuffer()) == dep.getContentHash() ?
        DependencyStatus::UpToDate :
        DependencyStatus::OutOfDate;
  }

  std::string getBackupPublicModuleInterfacePath() {
    return getBackupPublicModuleInterfacePath(ctx.SourceMgr, backupInterfaceDir,
                                              moduleName, interfacePath);
  }

  static std::string getBackupPublicModuleInterfacePath(SourceManager &SM,
                                                        StringRef backupInterfaceDir,
                                                        StringRef moduleName,
                                                        StringRef interfacePath) {
    if (backupInterfaceDir.empty())
      return std::string();
    auto &fs = *SM.getFileSystem();
    auto fileName = llvm::sys::path::filename(interfacePath);
    {
      llvm::SmallString<256> path(backupInterfaceDir);
      llvm::sys::path::append(path, llvm::Twine(moduleName) + ".swiftmodule");
      llvm::sys::path::append(path, fileName);
      if (fs.exists(path.str())) {
        return path.str().str();
      }
    }
    {
      llvm::SmallString<256> path(backupInterfaceDir);
      llvm::sys::path::append(path, fileName);
      if (fs.exists(path.str())) {
        return path.str().str();
      }
    }
    return std::string();
  }

  // Check if all the provided file dependencies are up-to-date compared to
  // what's currently on disk.
  bool dependenciesAreUpToDate(StringRef modulePath,
                               ArrayRef<FileDependency> deps,
                               bool skipSystemDependencies) {
    SmallString<128> SDKRelativeBuffer;
    for (auto &in : deps) {
      if (skipSystemDependencies && in.isSDKRelative() &&
          in.isModificationTimeBased()) {
        continue;
      }
      StringRef fullPath = getFullDependencyPath(in, SDKRelativeBuffer);
      switch (checkDependency(modulePath, in, fullPath)) {
      case DependencyStatus::UpToDate:
        LLVM_DEBUG(llvm::dbgs() << "Dep " << fullPath << " is up to date\n");
        break;
      case DependencyStatus::OutOfDate:
        LLVM_DEBUG(llvm::dbgs() << "Dep " << fullPath << " is out of date\n");
        rebuildInfo.addOutOfDateDependency(modulePath, fullPath);
        return false;
      case DependencyStatus::Missing:
        LLVM_DEBUG(llvm::dbgs() << "Dep " << fullPath << " is missing\n");
        rebuildInfo.addMissingDependency(modulePath, fullPath);
        return false;
      }
    }
    return true;
  }

  // Check that the output .swiftmodule file is at least as new as all the
  // dependencies it read when it was built last time.
  bool serializedASTBufferIsUpToDate(
      StringRef path, const llvm::MemoryBuffer &buf,
      SmallVectorImpl<FileDependency> &allDeps) {

    // Clear the existing dependencies, because we're going to re-fill them
    // in validateSerializedAST.
    allDeps.clear();

    LLVM_DEBUG(llvm::dbgs() << "Validating deps of " << path << "\n");
    auto validationInfo = serialization::validateSerializedAST(
        buf.getBuffer(), requiresOSSAModules,
        /*ExtendedValidationInfo=*/nullptr, &allDeps);

    if (validationInfo.status != serialization::Status::Valid) {
      rebuildInfo.setSerializationStatus(path, validationInfo.status);
      return false;
    }

    bool skipCheckingSystemDependencies =
        ctx.SearchPathOpts.DisableModulesValidateSystemDependencies;
    return dependenciesAreUpToDate(path, allDeps,
                                   skipCheckingSystemDependencies);
  }

  // Check that the output .swiftmodule file is at least as new as all the
  // dependencies it read when it was built last time.
  bool swiftModuleIsUpToDate(
    StringRef modulePath, SmallVectorImpl<FileDependency> &AllDeps,
    std::unique_ptr<llvm::MemoryBuffer> &moduleBuffer) {
    auto OutBuf = fs.getBufferForFile(modulePath);
    if (!OutBuf)
      return false;
    moduleBuffer = std::move(*OutBuf);
    return serializedASTBufferIsUpToDate(modulePath, *moduleBuffer, AllDeps);
  }

  // Check that a "forwarding" .swiftmodule file is at least as new as all the
  // dependencies it read when it was built last time. Requires that the
  // forwarding module has been loaded from disk.
  bool forwardingModuleIsUpToDate(
      StringRef path, const ForwardingModule &fwd,
      SmallVectorImpl<FileDependency> &deps,
      std::unique_ptr<llvm::MemoryBuffer> &moduleBuffer) {

    // Clear the existing dependencies, because we're going to re-fill them
    // from the forwarding module.
    deps.clear();

    LLVM_DEBUG(llvm::dbgs() << "Validating deps of " << path << "\n");

    // First, make sure the underlying module path exists and is valid.
    auto modBuf = fs.getBufferForFile(fwd.underlyingModulePath);
    if (!modBuf || !serializedASTLooksValid(*modBuf.get(), requiresOSSAModules))
      return false;

    // Next, check the dependencies in the forwarding file.
    for (auto &dep : fwd.dependencies) {
      deps.push_back(
        FileDependency::modTimeBased(
          dep.path, dep.isSDKRelative, dep.size, dep.lastModificationTime));
    }

    bool skipCheckingSystemDependencies =
        ctx.SearchPathOpts.DisableModulesValidateSystemDependencies;
    if (!dependenciesAreUpToDate(path, deps, skipCheckingSystemDependencies))
      return false;

    moduleBuffer = std::move(*modBuf);
    return true;
  }

  bool canInterfaceHavePrebuiltModule() {
    StringRef sdkPath = ctx.SearchPathOpts.getSDKPath();
    if (!sdkPath.empty() &&
        hasPrefix(path::begin(interfacePath), path::end(interfacePath),
                  path::begin(sdkPath), path::end(sdkPath))) {
      return !StringRef(interfacePath).endswith(".private.swiftinterface");
    }
    return false;
  }

  Optional<StringRef>
  computePrebuiltModulePath(llvm::SmallString<256> &scratch) {
    namespace path = llvm::sys::path;

    // Check if this is a public interface file from the SDK.
    if (!canInterfaceHavePrebuiltModule())
      return None;

    // Assemble the expected path: $PREBUILT_CACHE/Foo.swiftmodule or
    // $PREBUILT_CACHE/Foo.swiftmodule/arch.swiftmodule. Note that there's no
    // cache key here.
    scratch = prebuiltCacheDir;

    // FIXME: Would it be possible to only have architecture-specific names
    // here? Then we could skip this check.
    StringRef inParentDirName =
      path::filename(path::parent_path(interfacePath));
    if (path::extension(inParentDirName) == ".swiftmodule") {
      assert(path::stem(inParentDirName) == moduleName);
      path::append(scratch, inParentDirName);
    }
    path::append(scratch, path::filename(modulePath));

    // If there isn't a file at this location, skip returning a path.
    if (!fs.exists(scratch))
      return None;

    return scratch.str();
  }

  /// Hack to deal with build systems (including the Swift standard library, at
  /// the time of this comment) that aren't yet using target-specific names for
  /// multi-target swiftmodules, in case the prebuilt cache is.
  Optional<StringRef>
  computeFallbackPrebuiltModulePath(llvm::SmallString<256> &scratch) {
    namespace path = llvm::sys::path;
    StringRef sdkPath = ctx.SearchPathOpts.getSDKPath();

    // Check if this is a public interface file from the SDK.
    if (sdkPath.empty() ||
        !hasPrefix(path::begin(interfacePath), path::end(interfacePath),
                   path::begin(sdkPath), path::end(sdkPath)) ||
        StringRef(interfacePath).endswith(".private.swiftinterface"))
      return None;

    // If the module isn't target-specific, there's no fallback path.
    StringRef inParentDirName =
        path::filename(path::parent_path(interfacePath));
    if (path::extension(inParentDirName) != ".swiftmodule")
      return None;

    // If the interface is already using the target-specific name, there's
    // nothing else to try.
    auto normalizedTarget = getTargetSpecificModuleTriple(ctx.LangOpts.Target);
    if (path::stem(modulePath) == normalizedTarget.str())
      return None;

    // Assemble the expected path:
    // $PREBUILT_CACHE/Foo.swiftmodule/target.swiftmodule. Note that there's no
    // cache key here.
    scratch = prebuiltCacheDir;
    path::append(scratch, inParentDirName);
    path::append(scratch, normalizedTarget.str());
    scratch += ".swiftmodule";

    // If there isn't a file at this location, skip returning a path.
    if (!fs.exists(scratch))
      return None;

    return scratch.str();
  }

  bool isInResourceDir(StringRef path) {
    StringRef resourceDir = ctx.SearchPathOpts.RuntimeResourcePath;
    if (resourceDir.empty()) return false;
    return path.startswith(resourceDir);
  }

  std::pair<std::string, std::string> getCompiledModuleCandidates() {
    std::pair<std::string, std::string> result;
    // Keep track of whether we should attempt to load a .swiftmodule adjacent
    // to the .swiftinterface.
    bool shouldLoadAdjacentModule = true;

    switch (loadMode) {
    case ModuleLoadingMode::OnlyInterface:
      // Always skip both the caches and adjacent modules, and always build the
      // module interface.
      return {};
    case ModuleLoadingMode::PreferInterface:
      // If we're in the load mode that prefers .swiftinterfaces, specifically
      // skip the module adjacent to the interface, but use the caches if
      // they're present.
      shouldLoadAdjacentModule = false;
      break;
    case ModuleLoadingMode::PreferSerialized:
      // The rest of the function should be covered by this.
      break;
    case ModuleLoadingMode::OnlySerialized:
      llvm_unreachable("module interface loader should not have been created");
    }
    // [NOTE: ModuleInterfaceLoader-defer-to-ImplicitSerializedModuleLoader]
    // If there's a module adjacent to the .swiftinterface that we can
    // _likely_ load (it validates OK and is up to date), bail early with
    // errc::not_supported, so the next (serialized) loader in the chain will
    // load it.
    // Alternately, if there's a .swiftmodule present but we can't even
    // read it (for whatever reason), we should let the other module loader
    // diagnose it.

    if (shouldLoadAdjacentModule) {
      if (fs.exists(modulePath)) {
        result.first = modulePath.str();
      }
    }

    // If we have a prebuilt cache path, check that too if the interface comes
    // from the SDK.
    if (!prebuiltCacheDir.empty()) {
      llvm::SmallString<256> scratch;
      std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
      Optional<StringRef> path = computePrebuiltModulePath(scratch);
      if (!path) {
        // Hack: deal with prebuilds of modules that still use the target-based
        // names.
        path = computeFallbackPrebuiltModulePath(scratch);
      }
      if (path) {
        if (fs.exists(*path)) {
          result.second = path->str();
        }
      }
    }

    return result;
  }

  llvm::ErrorOr<DiscoveredModule>
  discoverUpToDateCompiledModuleForInterface(SmallVectorImpl<FileDependency> &deps,
                                             std::string &UsableModulePath) {
    std::string adjacentMod, prebuiltMod;
    std::tie(adjacentMod, prebuiltMod) = getCompiledModuleCandidates();
    if (!adjacentMod.empty()) {
      auto adjacentModuleBuffer = fs.getBufferForFile(adjacentMod);
      if (adjacentModuleBuffer) {
        if (serializedASTBufferIsUpToDate(adjacentMod, *adjacentModuleBuffer.get(),
                                          deps)) {
          LLVM_DEBUG(llvm::dbgs() << "Found up-to-date module at "
                                  << adjacentMod
                                  << "; deferring to serialized module loader\n");
          UsableModulePath = adjacentMod;
          return std::make_error_code(std::errc::not_supported);
        } else if (isInResourceDir(adjacentMod) &&
                   loadMode == ModuleLoadingMode::PreferSerialized) {
          // Special-case here: If we're loading a .swiftmodule from the resource
          // dir adjacent to the compiler, defer to the serialized loader instead
          // of falling back. This is mainly to support development of Swift,
          // where one might change the module format version but forget to
          // recompile the standard library. If that happens, don't fall back
          // and silently recompile the standard library -- instead, error like
          // we used to.
          LLVM_DEBUG(llvm::dbgs() << "Found out-of-date module in the "
                                     "resource-dir at "
                                  << adjacentMod
                                  << "; deferring to serialized module loader "
                                     "to diagnose\n");
          return std::make_error_code(std::errc::not_supported);
        } else {
          LLVM_DEBUG(llvm::dbgs() << "Found out-of-date module at "
                                  << adjacentMod << "\n");
          rebuildInfo.setModuleKind(adjacentMod,
                                    ModuleRebuildInfo::ModuleKind::Normal);
        }
      } else {
        LLVM_DEBUG(llvm::dbgs() << "Found unreadable module at "
                                << adjacentMod
                                << "; deferring to serialized module loader\n");
        return std::make_error_code(std::errc::not_supported);
      }
    }

    if(!prebuiltMod.empty()) {
      std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
      if (swiftModuleIsUpToDate(prebuiltMod, deps, moduleBuffer)) {
        LLVM_DEBUG(llvm::dbgs() << "Found up-to-date prebuilt module at "
                                << prebuiltMod << "\n");
        UsableModulePath = prebuiltMod;
        return DiscoveredModule::prebuilt(prebuiltMod, std::move(moduleBuffer));
      } else {
        LLVM_DEBUG(llvm::dbgs() << "Found out-of-date prebuilt module at "
                                << prebuiltMod << "\n");
        rebuildInfo.setModuleKind(prebuiltMod,
                                  ModuleRebuildInfo::ModuleKind::Prebuilt);
      }
    }
    // We cannot find any proper compiled module to use.
    return std::make_error_code(std::errc::no_such_file_or_directory);
  }

  /// Finds the most appropriate .swiftmodule, whose dependencies are up to
  /// date, that we can load for the provided .swiftinterface file.
  llvm::ErrorOr<DiscoveredModule> discoverUpToDateModuleForInterface(
    StringRef cachedOutputPath,
    SmallVectorImpl<FileDependency> &deps) {

    // First, check the cached module path. Whatever's in this cache represents
    // the most up-to-date knowledge we have about the module.
    if (auto cachedBufOrError = fs.getBufferForFile(cachedOutputPath)) {
      auto buf = std::move(*cachedBufOrError);

      // Check to see if the module is a serialized AST. If it's not, then we're
      // probably dealing with a Forwarding Module, which is a YAML file.
      bool isForwardingModule =
        !serialization::isSerializedAST(buf->getBuffer());

      // If it's a forwarding module, load the YAML file from disk and check
      // if it's up-to-date.
      if (isForwardingModule) {
        if (auto forwardingModule = ForwardingModule::load(*buf)) {
          std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
          if (forwardingModuleIsUpToDate(cachedOutputPath,
                                         *forwardingModule, deps,
                                         moduleBuffer)) {
            LLVM_DEBUG(llvm::dbgs() << "Found up-to-date forwarding module at "
                                    << cachedOutputPath << "\n");
            return DiscoveredModule::forwarded(
              forwardingModule->underlyingModulePath, std::move(moduleBuffer));
          }

          LLVM_DEBUG(llvm::dbgs() << "Found out-of-date forwarding module at "
                     << cachedOutputPath << "\n");
          rebuildInfo.setModuleKind(cachedOutputPath,
                                    ModuleRebuildInfo::ModuleKind::Forwarding);
        }
      // Otherwise, check if the AST buffer itself is up to date.
      } else if (serializedASTBufferIsUpToDate(cachedOutputPath, *buf, deps)) {
        LLVM_DEBUG(llvm::dbgs() << "Found up-to-date cached module at "
                                << cachedOutputPath << "\n");
        return DiscoveredModule::normal(cachedOutputPath, std::move(buf));
      } else {
        LLVM_DEBUG(llvm::dbgs() << "Found out-of-date cached module at "
                   << cachedOutputPath << "\n");
        rebuildInfo.setModuleKind(cachedOutputPath,
                                  ModuleRebuildInfo::ModuleKind::Cached);
      }
    }
    std::string usableModulePath;
    return discoverUpToDateCompiledModuleForInterface(deps, usableModulePath);
  }

  /// Writes the "forwarding module" that will forward to a module in the
  /// prebuilt cache.
  ///
  /// Since forwarding modules track dependencies separately from the module
  /// they point to, we'll need to grab the up-to-date file status while doing
  /// this. If the write was successful, it also updates the
  /// list of dependencies to match what was written to the forwarding file.
  bool writeForwardingModuleAndUpdateDeps(
      const DiscoveredModule &mod, StringRef outputPath,
      SmallVectorImpl<FileDependency> &deps) {
    assert(mod.isPrebuilt() &&
           "cannot write forwarding file for non-prebuilt module");
    ForwardingModule fwd(mod.path);

    SmallVector<FileDependency, 16> depsAdjustedToMTime;

    // FIXME: We need to avoid re-statting all these dependencies, otherwise
    //        we may record out-of-date information.
    SmallString<128> SDKRelativeBuffer;
    auto addDependency = [&](FileDependency dep) -> FileDependency {
      auto status = fs.status(getFullDependencyPath(dep, SDKRelativeBuffer));
      uint64_t mtime =
        status->getLastModificationTime().time_since_epoch().count();
      fwd.addDependency(dep.getPath(), dep.isSDKRelative(), status->getSize(),
                        mtime);

      // Construct new FileDependency matching what we've added to the
      // forwarding module.
      return FileDependency::modTimeBased(dep.getPath(), dep.isSDKRelative(),
                                          status->getSize(), mtime);
    };

    // Add the prebuilt module as a dependency of the forwarding module, but
    // don't add it to the outer dependency list.
    (void)addDependency(FileDependency::hashBased(fwd.underlyingModulePath,
                                                  /*SDKRelative*/false,
                                                  /*size*/0, /*hash*/0));

    // Add all the dependencies from the prebuilt module, and update our list
    // of dependencies to reflect what's recorded in the forwarding module.
    for (auto dep : deps) {
      auto adjustedDep = addDependency(dep);
      depsAdjustedToMTime.push_back(adjustedDep);
    }

    // Create the module cache if we haven't created it yet.
    StringRef parentDir = path::parent_path(outputPath);
    (void)llvm::sys::fs::create_directories(parentDir);

    auto hadError = withOutputFile(diags, outputPath,
      [&](llvm::raw_pwrite_stream &out) {
        llvm::yaml::Output yamlWriter(out);
        yamlWriter << fwd;
        return false;
      });

    if (hadError)
      return true;

    // If and only if we succeeded writing the forwarding file, update the
    // provided list of dependencies.
    deps = depsAdjustedToMTime;
    return false;
  }

  /// Looks up the best module to load for a given interface, and returns a
  /// buffer of the module's contents. Also reports the module's dependencies
  /// to the parent \c dependencyTracker if it came from the cache, or was built
  /// from the given interface. See the main comment in
  /// \c ModuleInterfaceLoader.h for an explanation of the module
  /// loading strategy.
  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
  findOrBuildLoadableModule() {

    // Track system dependencies if the parent tracker is set to do so.
    bool trackSystemDependencies = false;
    if (dependencyTracker) {
      auto ClangDependencyTracker = dependencyTracker->getClangCollector();
      trackSystemDependencies = ClangDependencyTracker->needSystemDependencies();
    }
    InterfaceSubContextDelegateImpl astDelegate(
        ctx.SourceMgr, &ctx.Diags, ctx.SearchPathOpts, ctx.LangOpts,
        ctx.ClangImporterOpts, Opts,
        /*buildModuleCacheDirIfAbsent*/ true, cacheDir, prebuiltCacheDir,
        backupInterfaceDir,
        /*serializeDependencyHashes*/ false, trackSystemDependencies,
        requiresOSSAModules);

    // Compute the output path if we're loading or emitting a cached module.
    llvm::SmallString<256> cachedOutputPath;
    StringRef CacheHash;
    astDelegate.computeCachedOutputPath(moduleName, interfacePath,
                                        cachedOutputPath, CacheHash);

    // Try to find the right module for this interface, either alongside it,
    // in the cache, or in the prebuilt cache.
    SmallVector<FileDependency, 16> allDeps;
    auto moduleOrErr =
      discoverUpToDateModuleForInterface(cachedOutputPath, allDeps);

    // If we errored with anything other than 'no such file or directory',
    // fail this load and let the other module loader diagnose it.
    if (!moduleOrErr &&
        moduleOrErr.getError() != std::errc::no_such_file_or_directory)
      return moduleOrErr.getError();

    // We discovered a module! Return that module's buffer so we can load it.
    if (moduleOrErr) {
      auto module = std::move(moduleOrErr.get());

      // If it's prebuilt, use this time to generate a forwarding module and
      // update the dependencies to use modification times.
      if (module.isPrebuilt())
        if (writeForwardingModuleAndUpdateDeps(module, cachedOutputPath,
                                               allDeps))
          return std::make_error_code(std::errc::not_supported);

      // Report the module's dependencies to the dependencyTracker
      if (dependencyTracker) {
        SmallString<128> SDKRelativeBuffer;
        for (auto &dep: allDeps) {
          StringRef fullPath = getFullDependencyPath(dep, SDKRelativeBuffer);
          dependencyTracker->addDependency(fullPath,
                                           /*IsSystem=*/dep.isSDKRelative());
        }
      }

      return std::move(module.moduleBuffer);
    }
    // If building from interface is disabled, return error.
    if (Opts.disableBuildingInterface) {
      return std::make_error_code(std::errc::not_supported);
    }

    std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;

    // We didn't discover a module corresponding to this interface.
    // Diagnose that we didn't find a loadable module, if we were asked to.
    //
    // Note that we use `diags` so that we emit this remark even when we're
    // emitting other messages to `emptyDiags` (see below); these act as status
    // messages to explain what's taking so long.
    auto remarkRebuildAll = [&]() {
      rebuildInfo.diagnose(ctx, diags, prebuiltCacheDir, diagnosticLoc,
                           diag::rebuilding_module_from_interface, moduleName,
                           interfacePath);
    };
    // Diagnose only for the standard library; it should be prebuilt in typical
    // workflows, but if it isn't, building it may take several minutes and a
    // lot of memory, so users may think the compiler is busy-hung.
    auto remarkRebuildStdlib = [&]() {
      if (moduleName != "Swift")
        return;

      auto moduleTriple = getTargetSpecificModuleTriple(ctx.LangOpts.Target);
      rebuildInfo.diagnose(ctx, diags, prebuiltCacheDir, SourceLoc(),
                           diag::rebuilding_stdlib_from_interface,
                           moduleTriple.str());
    };
    auto remarkRebuild = Opts.remarkOnRebuildFromInterface
                       ? llvm::function_ref<void()>(remarkRebuildAll)
                       : remarkRebuildStdlib;

    bool failed = false;
    std::string backupPath = getBackupPublicModuleInterfacePath();
    {
      DiagnosticEngine emptyDiags(ctx.SourceMgr);
      std::unique_ptr<llvm::SaveAndRestore<DiagnosticEngine*>> saver;
      DiagnosticEngine *diagsToUse = &ctx.Diags;
      // Avoid emitting diagnostics if we have a backup interface to use.
      // If we succeed in building this canonical interface, it's not interesting
      // to see those diagnostics.
      // If we failed in build, we will use the back up interface and it's interesting
      // to see diagnostics there.
      if (!backupPath.empty()) {
        diagsToUse = &emptyDiags;
        saver = std::make_unique<llvm::SaveAndRestore<DiagnosticEngine*>>(
          astDelegate.Diags, diagsToUse);
      }
      // Set up a builder if we need to build the module. It'll also set up
      // the genericSubInvocation we'll need to use to compute the cache paths.
      ModuleInterfaceBuilder builder(
        ctx.SourceMgr, diagsToUse,
        astDelegate, interfacePath, moduleName, cacheDir,
        prebuiltCacheDir, backupInterfaceDir, StringRef(),
        Opts.disableInterfaceLock, diagnosticLoc,
        dependencyTracker);
      // If we found an out-of-date .swiftmodule, we still want to add it as
      // a dependency of the .swiftinterface. That way if it's updated, but
      // the .swiftinterface remains the same, we invalidate the cache and
      // check the new .swiftmodule, because it likely has more information
      // about the state of the world.
      if (rebuildInfo.sawOutOfDateModule(modulePath))
        builder.addExtraDependency(modulePath);
      failed = builder.buildSwiftModule(cachedOutputPath,
                                        /*shouldSerializeDeps*/true,
                                        &moduleBuffer, remarkRebuild);
    }
    if (!failed) {
      // If succeeded, we are done.
      assert(moduleBuffer &&
             "failed to write module buffer but returned success?");
      return std::move(moduleBuffer);
    } else if (backupPath.empty()) {
      // If failed and we don't have a backup interface file, return error code.
      return std::make_error_code(std::errc::invalid_argument);
    }
    assert(failed);
    assert(!backupPath.empty());
    while (1) {
      diags.diagnose(diagnosticLoc, diag::interface_file_backup_used,
                     interfacePath, backupPath);
      // Set up a builder if we need to build the module. It'll also set up
      // the genericSubInvocation we'll need to use to compute the cache paths.
      ModuleInterfaceBuilder fallbackBuilder(
        ctx.SourceMgr, &ctx.Diags, astDelegate, backupPath, moduleName, cacheDir,
        prebuiltCacheDir, backupInterfaceDir, StringRef(),
        Opts.disableInterfaceLock, diagnosticLoc,
        dependencyTracker);
      if (rebuildInfo.sawOutOfDateModule(modulePath))
        fallbackBuilder.addExtraDependency(modulePath);
      // Add the canonical interface path as a dependency of this module.
      // This ensures that after the user manually fixed the canonical interface
      // file and removed the fallback interface file, we can rebuild the cache.
      fallbackBuilder.addExtraDependency(interfacePath);
      // Use cachedOutputPath as the output file path. This output path was
      // calcualted using the canonical interface file path to make sure we
      // can find it from the canonical interface file.
      auto failedAgain = fallbackBuilder.buildSwiftModule(cachedOutputPath,
          /*shouldSerializeDeps*/true, &moduleBuffer, remarkRebuild);
      if (failedAgain)
        return std::make_error_code(std::errc::invalid_argument);
      assert(moduleBuffer);
      return std::move(moduleBuffer);
    }
  }
};

} // end anonymous namespace

bool ModuleInterfaceCheckerImpl::isCached(StringRef DepPath) {
  if (!CacheDir.empty() && DepPath.startswith(CacheDir))
    return true;
  return !PrebuiltCacheDir.empty() && DepPath.startswith(PrebuiltCacheDir);
}

bool ModuleInterfaceLoader::isCached(StringRef DepPath) {
  return InterfaceChecker.isCached(DepPath);
}

/// Load a .swiftmodule associated with a .swiftinterface either from a
/// cache or by converting it in a subordinate \c CompilerInstance, caching
/// the results.
std::error_code ModuleInterfaceLoader::findModuleFilesInDirectory(
  ImportPath::Element ModuleID,
  const SerializedModuleBaseName &BaseName,
  SmallVectorImpl<char> *ModuleInterfacePath,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleBuffer,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleDocBuffer,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleSourceInfoBuffer,
  bool skipBuildingInterface, bool IsFramework) {

  // If running in OnlySerialized mode, ModuleInterfaceLoader
  // should not have been constructed at all.
  assert(LoadMode != ModuleLoadingMode::OnlySerialized);

  llvm::SmallString<256>
  ModPath{ BaseName.getName(file_types::TY_SwiftModuleFile) },
  InPath{  BaseName.getName(file_types::TY_SwiftModuleInterfaceFile) },
  PrivateInPath{BaseName.getName(file_types::TY_PrivateSwiftModuleInterfaceFile)};

  // First check to see if the .swiftinterface exists at all. Bail if not.
  auto &fs = *Ctx.SourceMgr.getFileSystem();
  if (!fs.exists(InPath)) {
    if (fs.exists(ModPath)) {
      LLVM_DEBUG(llvm::dbgs()
        << "No .swiftinterface file found adjacent to module file "
        << ModPath.str() << "\n");
      return std::make_error_code(std::errc::not_supported);
    }
    return std::make_error_code(std::errc::no_such_file_or_directory);
  }

  // If present, use the private interface instead of the public one.
  if (fs.exists(PrivateInPath)) {
    InPath = PrivateInPath;
  }

  // If we've been told to skip building interfaces, we are done here and do
  // not need to have the module actually built. For example, if we are
  // currently answering a `canImport` query, it is enough to have found
  // the interface.
  if (skipBuildingInterface) {
    if (ModuleInterfacePath)
      *ModuleInterfacePath = InPath;
    return std::error_code();
  }

  // Create an instance of the Impl to do the heavy lifting.
  auto ModuleName = ModuleID.Item.str();
  ModuleInterfaceLoaderImpl Impl(
      Ctx, ModPath, InPath, ModuleName, InterfaceChecker.CacheDir,
      InterfaceChecker.PrebuiltCacheDir, InterfaceChecker.BackupInterfaceDir,
      ModuleID.Loc, InterfaceChecker.Opts,
      InterfaceChecker.RequiresOSSAModules, dependencyTracker,
      llvm::is_contained(PreferInterfaceForModules, ModuleName)
          ? ModuleLoadingMode::PreferInterface
          : LoadMode);

  // Ask the impl to find us a module that we can load or give us an error
  // telling us that we couldn't load it.
  auto ModuleBufferOrErr = Impl.findOrBuildLoadableModule();
  if (!ModuleBufferOrErr)
    return ModuleBufferOrErr.getError();

  if (ModuleBuffer) {
    *ModuleBuffer = std::move(*ModuleBufferOrErr);
    if (ModuleInterfacePath)
      *ModuleInterfacePath = InPath;
  }

  // Open .swiftsourceinfo file if it's present.
  if (auto SourceInfoError = openModuleSourceInfoFileIfPresent(ModuleID,
                                                               BaseName,
                                                       ModuleSourceInfoBuffer))
    return SourceInfoError;

  // Delegate back to the serialized module loader to load the module doc.
  if (auto DocLoadErr = openModuleDocFileIfPresent(ModuleID, BaseName,
                                                   ModuleDocBuffer))
    return DocLoadErr;

  return std::error_code();
}

std::vector<std::string>
ModuleInterfaceCheckerImpl::getCompiledModuleCandidatesForInterface(
    StringRef moduleName, StringRef interfacePath) {
  // Derive .swiftmodule path from the .swiftinterface path.
  auto newExt = file_types::getExtension(file_types::TY_SwiftModuleFile);
  llvm::SmallString<32> modulePath = interfacePath;
  llvm::sys::path::replace_extension(modulePath, newExt);
  ModuleInterfaceLoaderImpl Impl(Ctx, modulePath, interfacePath, moduleName,
                                 CacheDir, PrebuiltCacheDir, BackupInterfaceDir,
                                 SourceLoc(), Opts,
                                 RequiresOSSAModules, nullptr,
                                 ModuleLoadingMode::PreferSerialized);
  std::vector<std::string> results;
  auto pair = Impl.getCompiledModuleCandidates();
  // Add compiled module candidates only when they are non-empty.
  if (!pair.first.empty())
    results.push_back(pair.first);
  if (!pair.second.empty())
    results.push_back(pair.second);
  return results;
}

bool ModuleInterfaceCheckerImpl::tryEmitForwardingModule(
    StringRef moduleName, StringRef interfacePath,
    ArrayRef<std::string> candidates, StringRef outputPath) {
  // Derive .swiftmodule path from the .swiftinterface path.
  auto newExt = file_types::getExtension(file_types::TY_SwiftModuleFile);
  llvm::SmallString<32> modulePath = interfacePath;
  llvm::sys::path::replace_extension(modulePath, newExt);
  ModuleInterfaceLoaderImpl Impl(Ctx, modulePath, interfacePath, moduleName,
                                 CacheDir, PrebuiltCacheDir,
                                 BackupInterfaceDir, SourceLoc(), Opts,
                                 RequiresOSSAModules, nullptr,
                                 ModuleLoadingMode::PreferSerialized);
  SmallVector<FileDependency, 16> deps;
  std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
  for (auto mod: candidates) {
    // Check if the candidate compiled module is still up-to-date.
    if (Impl.swiftModuleIsUpToDate(mod, deps, moduleBuffer)) {
      // If so, emit a forwarding module to the candidate.
      ForwardingModule FM(mod);
      auto hadError = withOutputFile(Ctx.Diags, outputPath,
        [&](llvm::raw_pwrite_stream &out) {
          llvm::yaml::Output yamlWriter(out);
          yamlWriter << FM;
          return false;
        });
      if (!hadError)
        return true;
    }
  }
  return false;
}

bool ModuleInterfaceLoader::buildSwiftModuleFromSwiftInterface(
    SourceManager &SourceMgr, DiagnosticEngine &Diags,
    const SearchPathOptions &SearchPathOpts, const LangOptions &LangOpts,
    const ClangImporterOptions &ClangOpts, StringRef CacheDir,
    StringRef PrebuiltCacheDir, StringRef BackupInterfaceDir,
    StringRef ModuleName, StringRef InPath,
    StringRef OutPath, StringRef ABIOutputPath,
    bool SerializeDependencyHashes,
    bool TrackSystemDependencies, ModuleInterfaceLoaderOptions LoaderOpts,
    RequireOSSAModules_t RequireOSSAModules) {
  InterfaceSubContextDelegateImpl astDelegate(
      SourceMgr, &Diags, SearchPathOpts, LangOpts, ClangOpts, LoaderOpts,
      /*CreateCacheDirIfAbsent*/ true, CacheDir, PrebuiltCacheDir,
      BackupInterfaceDir,
      SerializeDependencyHashes, TrackSystemDependencies, RequireOSSAModules);
  ModuleInterfaceBuilder builder(SourceMgr, &Diags, astDelegate, InPath,
                                 ModuleName, CacheDir, PrebuiltCacheDir,
                                 BackupInterfaceDir, ABIOutputPath,
                                 LoaderOpts.disableInterfaceLock);
  // FIXME: We really only want to serialize 'important' dependencies here, if
  //        we want to ship the built swiftmodules to another machine.
  auto failed = builder.buildSwiftModule(OutPath, /*shouldSerializeDeps*/true,
                                         /*ModuleBuffer*/nullptr, nullptr,
                                         SearchPathOpts.CandidateCompiledModules);
  if (!failed)
    return false;
  auto backInPath =
    ModuleInterfaceLoaderImpl::getBackupPublicModuleInterfacePath(SourceMgr,
      BackupInterfaceDir, ModuleName, InPath);
  if (backInPath.empty())
    return true;
  assert(failed);
  assert(!backInPath.empty());
  ModuleInterfaceBuilder backupBuilder(SourceMgr, &Diags, astDelegate, backInPath,
                                       ModuleName, CacheDir, PrebuiltCacheDir,
                                       BackupInterfaceDir, ABIOutputPath,
                                       LoaderOpts.disableInterfaceLock);
  // Ensure we can rebuild module after user changed the original interface file.
  backupBuilder.addExtraDependency(InPath);
  // FIXME: We really only want to serialize 'important' dependencies here, if
  //        we want to ship the built swiftmodules to another machine.
  return backupBuilder.buildSwiftModule(OutPath, /*shouldSerializeDeps*/true,
                                        /*ModuleBuffer*/nullptr, nullptr,
                                        SearchPathOpts.CandidateCompiledModules);
}

void ModuleInterfaceLoader::collectVisibleTopLevelModuleNames(
    SmallVectorImpl<Identifier> &names) const {
  collectVisibleTopLevelModuleNamesImpl(
      names,
      file_types::getExtension(file_types::TY_SwiftModuleInterfaceFile));
}

void InterfaceSubContextDelegateImpl::inheritOptionsForBuildingInterface(
    const SearchPathOptions &SearchPathOpts, const LangOptions &LangOpts,
    RequireOSSAModules_t RequireOSSAModules) {
  GenericArgs.push_back("-frontend");
  // Start with a genericSubInvocation that copies various state from our
  // invoking ASTContext.
  GenericArgs.push_back("-compile-module-from-interface");
  genericSubInvocation.setTargetTriple(LangOpts.Target);

  auto triple = ArgSaver.save(genericSubInvocation.getTargetTriple());
  if (!triple.empty()) {
    GenericArgs.push_back("-target");
    GenericArgs.push_back(triple);
  }

  if (LangOpts.ClangTarget.hasValue()) {
    genericSubInvocation.getLangOptions().ClangTarget = LangOpts.ClangTarget;
    auto triple = ArgSaver.save(genericSubInvocation.getLangOptions()
      .ClangTarget->getTriple());
    assert(!triple.empty());
    // In explicit module build, all PCMs will be built using the given clang target.
    // So the Swift interface should know that as well to load these PCMs properly.
    GenericArgs.push_back("-clang-target");
    GenericArgs.push_back(triple);
  }

  // Inherit the Swift language version
  genericSubInvocation.getLangOptions().EffectiveLanguageVersion =
    LangOpts.EffectiveLanguageVersion;
  GenericArgs.push_back("-swift-version");
  GenericArgs.push_back(ArgSaver.save(genericSubInvocation.getLangOptions()
    .EffectiveLanguageVersion.asAPINotesVersionString()));

  genericSubInvocation.setImportSearchPaths(
      SearchPathOpts.getImportSearchPaths());
  genericSubInvocation.setFrameworkSearchPaths(
      SearchPathOpts.getFrameworkSearchPaths());
  if (!SearchPathOpts.getSDKPath().empty()) {
    // Add -sdk arguments to the module building commands.
    // Module building commands need this because dependencies sometimes use
    // sdk-relative paths (prebuilt modules for example). Without -sdk, the command
    // will not be able to local these dependencies, leading to unnecessary
    // building from textual interfaces.
    GenericArgs.push_back("-sdk");
    GenericArgs.push_back(ArgSaver.save(SearchPathOpts.getSDKPath()));
    genericSubInvocation.setSDKPath(SearchPathOpts.getSDKPath().str());
  }

  genericSubInvocation.getFrontendOptions().InputMode
      = FrontendOptions::ParseInputMode::SwiftModuleInterface;
  if (!SearchPathOpts.RuntimeResourcePath.empty()) {
    genericSubInvocation.setRuntimeResourcePath(SearchPathOpts.RuntimeResourcePath);
  }

  // Inhibit warnings from the genericSubInvocation since we are assuming the user
  // is not in a position to fix them.
  genericSubInvocation.getDiagnosticOptions().SuppressWarnings = true;
  GenericArgs.push_back("-suppress-warnings");

  // Inherit this setting down so that it can affect error diagnostics (mostly
  // by making them non-fatal).
  genericSubInvocation.getLangOptions().DebuggerSupport = LangOpts.DebuggerSupport;
  if (LangOpts.DebuggerSupport) {
    GenericArgs.push_back("-debugger-support");
  }

  // Disable this; deinitializers always get printed with `@objc` even in
  // modules that don't import Foundation.
  genericSubInvocation.getLangOptions().EnableObjCAttrRequiresFoundation = false;
  GenericArgs.push_back("-disable-objc-attr-requires-foundation-module");

  // If we are supposed to use RequireOSSAModules, do so.
  genericSubInvocation.getSILOptions().EnableOSSAModules =
      bool(RequireOSSAModules);
  if (LangOpts.DisableAvailabilityChecking) {
    genericSubInvocation.getLangOptions().DisableAvailabilityChecking = true;
    GenericArgs.push_back("-disable-availability-checking");
  }

  // Pass-down the obfuscators so we can get the serialized search paths properly.
  genericSubInvocation.setSerializedPathObfuscator(
    SearchPathOpts.DeserializedPathRecoverer);
  SearchPathOpts.DeserializedPathRecoverer
    .forEachPair([&](StringRef lhs, StringRef rhs) {
      GenericArgs.push_back("-serialized-path-obfuscate");
      std::string pair = (llvm::Twine(lhs) + "=" + rhs).str();
      GenericArgs.push_back(ArgSaver.save(pair));
  });
}

bool InterfaceSubContextDelegateImpl::extractSwiftInterfaceVersionAndArgs(
    CompilerInvocation &subInvocation,
    SmallVectorImpl<const char *> &SubArgs,
    std::string &CompilerVersion,
    StringRef interfacePath,
    SourceLoc diagnosticLoc) {
  llvm::vfs::FileSystem &fs = *SM.getFileSystem();
  auto FileOrError = swift::vfs::getFileOrSTDIN(fs, interfacePath);
  if (!FileOrError) {
    // Don't use this->diagnose() because it'll just try to re-open
    // interfacePath.
    Diags->diagnose(diagnosticLoc, diag::error_open_input_file,
                    interfacePath, FileOrError.getError().message());
    return true;
  }
  auto SB = FileOrError.get()->getBuffer();
  auto VersRe = getSwiftInterfaceFormatVersionRegex();
  auto CompRe = getSwiftInterfaceCompilerVersionRegex();
  SmallVector<StringRef, 1> VersMatches, CompMatches;

  if (!VersRe.match(SB, &VersMatches)) {
    diagnose(interfacePath, diagnosticLoc,
             diag::error_extracting_version_from_module_interface);
    return true;
  }
  if (extractCompilerFlagsFromInterface(interfacePath, SB, ArgSaver, SubArgs)) {
    diagnose(interfacePath, diagnosticLoc,
             diag::error_extracting_version_from_module_interface);
    return true;
  }
  assert(VersMatches.size() == 2);
  // FIXME We should diagnose this at a location that makes sense:
  auto Vers = swift::version::Version(VersMatches[1], SourceLoc(), Diags);

  if (CompRe.match(SB, &CompMatches)) {
    assert(CompMatches.size() == 2);
    CompilerVersion = ArgSaver.save(CompMatches[1]).str();
  }
  else {
    // Don't diagnose; handwritten module interfaces don't include this field.
    CompilerVersion = "(unspecified, file possibly handwritten)";
  }

  // For now: we support anything with the same "major version" and assume
  // minor versions might be interesting for debugging, or special-casing a
  // compatible field variant.
  if (Vers.asMajorVersion() != InterfaceFormatVersion.asMajorVersion()) {
    diagnose(interfacePath, diagnosticLoc,
             diag::unsupported_version_of_module_interface, interfacePath, Vers);
    return true;
  }

  SmallString<32> ExpectedModuleName = subInvocation.getModuleName();
  if (subInvocation.parseArgs(SubArgs, *Diags)) {
    return true;
  }

  if (subInvocation.getModuleName() != ExpectedModuleName) {
    auto DiagKind = diag::serialization_name_mismatch;
    if (subInvocation.getLangOptions().DebuggerSupport)
      DiagKind = diag::serialization_name_mismatch_repl;
    diagnose(interfacePath, diagnosticLoc,
             DiagKind, subInvocation.getModuleName(), ExpectedModuleName);
    return true;
  }

  return false;
}

InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
    SourceManager &SM, DiagnosticEngine *Diags,
    const SearchPathOptions &searchPathOpts, const LangOptions &langOpts,
    const ClangImporterOptions &clangImporterOpts,
    ModuleInterfaceLoaderOptions LoaderOpts, bool buildModuleCacheDirIfAbsent,
    StringRef moduleCachePath, StringRef prebuiltCachePath,
    StringRef backupModuleInterfaceDir,
    bool serializeDependencyHashes, bool trackSystemDependencies,
    RequireOSSAModules_t requireOSSAModules)
    : SM(SM), Diags(Diags), ArgSaver(Allocator) {
  genericSubInvocation.setMainExecutablePath(LoaderOpts.mainExecutablePath);
  inheritOptionsForBuildingInterface(searchPathOpts, langOpts,
                                     requireOSSAModules);
  // Configure front-end input.
  auto &SubFEOpts = genericSubInvocation.getFrontendOptions();
  SubFEOpts.RequestedAction = LoaderOpts.requestedAction;
  if (!moduleCachePath.empty()) {
    genericSubInvocation.setClangModuleCachePath(moduleCachePath);
  }
  if (!prebuiltCachePath.empty()) {
    genericSubInvocation.getFrontendOptions().PrebuiltModuleCachePath =
      prebuiltCachePath.str();
  }
  if (!backupModuleInterfaceDir.empty()) {
    genericSubInvocation.getFrontendOptions().BackupModuleInterfaceDir =
      backupModuleInterfaceDir.str();
  }
  if (trackSystemDependencies) {
    genericSubInvocation.getFrontendOptions().IntermoduleDependencyTracking =
        IntermoduleDepTrackingMode::IncludeSystem;
    GenericArgs.push_back("-track-system-dependencies");
  } else {
    // Always track at least the non-system dependencies for interface building.
    genericSubInvocation.getFrontendOptions().IntermoduleDependencyTracking =
        IntermoduleDepTrackingMode::ExcludeSystem;
  }
  if (LoaderOpts.disableImplicitSwiftModule) {
    genericSubInvocation.getFrontendOptions().DisableImplicitModules = true;
    GenericArgs.push_back("-disable-implicit-swift-modules");
  }
  // Pass down -explicit-swift-module-map-file
  // FIXME: we shouldn't need this. Remove it?
  StringRef explictSwiftModuleMap = searchPathOpts.ExplicitSwiftModuleMap;
  genericSubInvocation.getSearchPathOptions().ExplicitSwiftModuleMap =
    explictSwiftModuleMap.str();
  auto &subClangImporterOpts = genericSubInvocation.getClangImporterOptions();
  // Respect the detailed-record preprocessor setting of the parent context.
  // This, and the "raw" clang module format it implicitly enables, are
  // required by sourcekitd.
  subClangImporterOpts.DetailedPreprocessingRecord =
    clangImporterOpts.DetailedPreprocessingRecord;

  // We need to add these extra clang flags because explict module building
  // related flags are all there: -fno-implicit-modules, -fmodule-map-file=,
  // and -fmodule-file=.
  // If we don't add these flags, the interface will be built with implicit
  // PCMs.
  // FIXME: With Implicit Module Builds, if sub-invocations inherit `-fmodule-map-file=` options,
  // those modulemaps become File dependencies of all downstream PCMs and their depending Swift
  // modules, triggering unnecessary re-builds. We work around this by only inheriting these options
  // when building with explicit modules. While this problem will not manifest with Explicit Modules
  // (which do not use the ClangImporter to build PCMs), we may still need a better way to
  // decide which options must be inherited here.
  if (LoaderOpts.disableImplicitSwiftModule) {
    subClangImporterOpts.ExtraArgs = clangImporterOpts.ExtraArgs;
    for (auto arg : subClangImporterOpts.ExtraArgs) {
      GenericArgs.push_back("-Xcc");
      GenericArgs.push_back(ArgSaver.save(arg));
    }
  }

  // Tell the genericSubInvocation to serialize dependency hashes if asked to do
  // so.
  auto &frontendOpts = genericSubInvocation.getFrontendOptions();
  frontendOpts.SerializeModuleInterfaceDependencyHashes =
    serializeDependencyHashes;
  if (serializeDependencyHashes) {
    GenericArgs.push_back("-serialize-module-interface-dependency-hashes");
  }

  // Tell the genericSubInvocation to remark on rebuilds from an interface if asked
  // to do so.
  frontendOpts.RemarkOnRebuildFromModuleInterface =
    LoaderOpts.remarkOnRebuildFromInterface;
  if (LoaderOpts.remarkOnRebuildFromInterface) {
    GenericArgs.push_back("-Rmodule-interface-rebuild");
  }
  // This flag only matters when we are verifying an textual interface.
  frontendOpts.DowngradeInterfaceVerificationError =
    LoaderOpts.downgradeInterfaceVerificationError;
  // Note that we don't assume cachePath is the same as the Clang
  // module cache path at this point.
  if (buildModuleCacheDirIfAbsent && !moduleCachePath.empty())
    (void)llvm::sys::fs::create_directories(moduleCachePath);
}

/// Calculate an output filename in \p genericSubInvocation's cache path that
/// includes a hash of relevant key data.
StringRef InterfaceSubContextDelegateImpl::computeCachedOutputPath(
                             StringRef moduleName,
                             StringRef useInterfacePath,
                             llvm::SmallString<256> &OutPath,
                             StringRef &CacheHash) {
  OutPath = genericSubInvocation.getClangModuleCachePath();
  llvm::sys::path::append(OutPath, moduleName);
  OutPath.append("-");
  auto hashStart = OutPath.size();
  OutPath.append(getCacheHash(useInterfacePath));
  CacheHash = OutPath.str().substr(hashStart);
  OutPath.append(".");
  auto OutExt = file_types::getExtension(file_types::TY_SwiftModuleFile);
  OutPath.append(OutExt);
  return OutPath.str();
}

/// Construct a cache key for the .swiftmodule being generated. There is a
/// balance to be struck here between things that go in the cache key and
/// things that go in the "up to date" check of the cache entry. We want to
/// avoid fighting over a single cache entry too much when (say) running
/// different compiler versions on the same machine or different inputs
/// that happen to have the same short module name, so we will disambiguate
/// those in the key. But we want to invalidate and rebuild a cache entry
/// -- rather than making a new one and potentially filling up the cache
/// with dead entries -- when other factors change, such as the contents of
/// the .swiftinterface input or its dependencies.
std::string
InterfaceSubContextDelegateImpl::getCacheHash(StringRef useInterfacePath) {
  auto normalizedTargetTriple =
      getTargetSpecificModuleTriple(genericSubInvocation.getLangOptions().Target);

  llvm::hash_code H = hash_combine(
      // Start with the compiler version (which will be either tag names or
      // revs). Explicitly don't pass in the "effective" language version --
      // this would mean modules built in different -swift-version modes would
      // rebuild their dependencies.
      swift::version::getSwiftFullVersion(),

      // Simplest representation of input "identity" (not content) is just a
      // pathname, and probably all we can get from the VFS in this regard
      // anyways.
      useInterfacePath,

      // Include the normalized target triple. In practice, .swiftinterface
      // files will be in target-specific subdirectories and would have
      // target-specific pieces #if'd out. However, it doesn't hurt to include
      // it, and it guards against mistakenly reusing cached modules across
      // targets. Note that this normalization explicitly doesn't include the
      // minimum deployment target (e.g. the '12.0' in 'ios12.0').
      normalizedTargetTriple.str(),

      // The SDK path is going to affect how this module is imported, so
      // include it.
      genericSubInvocation.getSDKPath(),

      // Whether or not we're tracking system dependencies affects the
      // invalidation behavior of this cache item.
      genericSubInvocation.getFrontendOptions().shouldTrackSystemDependencies(),

      // Whether or not OSSA modules are enabled.
      //
      // If OSSA modules are enabled, we use a separate namespace of modules to
      // ensure that we compile all swift interface files with the option set.
      unsigned(genericSubInvocation.getSILOptions().EnableOSSAModules));

  return llvm::toString(llvm::APInt(64, H), 36, /*Signed=*/false);
}

std::error_code
InterfaceSubContextDelegateImpl::runInSubContext(StringRef moduleName,
                                                 StringRef interfacePath,
                                                 StringRef outputPath,
                                                 SourceLoc diagLoc,
    llvm::function_ref<std::error_code(ASTContext&, ModuleDecl*, ArrayRef<StringRef>,
                            ArrayRef<StringRef>, StringRef)> action) {
  return runInSubCompilerInstance(moduleName, interfacePath, outputPath, diagLoc,
                                  [&](SubCompilerInstanceInfo &info){
    return action(info.Instance->getASTContext(),
                  info.Instance->getMainModule(),
                  info.BuildArguments,
                  info.ExtraPCMArgs,
                  info.Hash);
  });
}

std::error_code
InterfaceSubContextDelegateImpl::runInSubCompilerInstance(StringRef moduleName,
                                                          StringRef interfacePath,
                                                          StringRef outputPath,
                                                          SourceLoc diagLoc,
                  llvm::function_ref<std::error_code(SubCompilerInstanceInfo&)> action) {
  // We are about to mess up the compiler invocation by using the compiler
  // arguments in the textual interface file. So copy to use a new compiler
  // invocation.
  CompilerInvocation subInvocation = genericSubInvocation;

  // Save the target triple from the original context.
  llvm::Triple originalTargetTriple(subInvocation.getLangOptions().Target);

  std::vector<StringRef> BuildArgs(GenericArgs.begin(), GenericArgs.end());
  assert(BuildArgs.size() == GenericArgs.size());
  // Configure inputs
  subInvocation.getFrontendOptions().InputsAndOutputs
    .addInputFile(interfacePath);
  BuildArgs.push_back(interfacePath);
  subInvocation.setModuleName(moduleName);
  BuildArgs.push_back("-module-name");
  BuildArgs.push_back(moduleName);

  // Calculate output path of the module.
  llvm::SmallString<256> buffer;
  StringRef CacheHash;
  auto hashedOutput = computeCachedOutputPath(moduleName, interfacePath, buffer,
                                              CacheHash);
  // If no specific output path is given, use the hashed output path.
  if (outputPath.empty()) {
    outputPath = hashedOutput;
  }

  // Configure the outputs in front-end options. There must be an equal number of
  // inputs and outputs.
  std::vector<std::string> outputFiles{"/<unused>"};
  std::vector<SupplementaryOutputPaths> ModuleOutputPaths;
  ModuleOutputPaths.emplace_back();
  if (subInvocation.getFrontendOptions().RequestedAction ==
          FrontendOptions::ActionType::EmitModuleOnly) {
    ModuleOutputPaths.back().ModuleOutputPath = outputPath.str();
  }
  assert(subInvocation.getFrontendOptions().InputsAndOutputs.isWholeModule());
  subInvocation.getFrontendOptions().InputsAndOutputs
    .setMainAndSupplementaryOutputs(outputFiles, ModuleOutputPaths);

  SmallVector<const char *, 64> SubArgs;

  // If the interface was emitted by a compiler that didn't print
  // `-target-min-inlining-version` into it, default to using the version from
  // the target triple, emulating previous behavior.
  SubArgs.push_back("-target-min-inlining-version");
  SubArgs.push_back("target");

  std::string CompilerVersion;
  // Extract compiler arguments from the interface file and use them to configure
  // the compiler invocation.
  if (extractSwiftInterfaceVersionAndArgs(subInvocation,
                                          SubArgs,
                                          CompilerVersion,
                                          interfacePath,
                                          diagLoc)) {
    return std::make_error_code(std::errc::not_supported);
  }
  // Insert arguments collected from the interface file.
  BuildArgs.insert(BuildArgs.end(), SubArgs.begin(), SubArgs.end());
  if (subInvocation.parseArgs(SubArgs, *Diags)) {
    return std::make_error_code(std::errc::not_supported);
  }

  // If the target triple parsed from the Swift interface file differs
  // only in subarchitecture from the original target triple, then
  // we have loaded a Swift interface from a different-but-compatible
  // architecture slice. Use the original subarchitecture.
  llvm::Triple parsedTargetTriple(subInvocation.getTargetTriple());
  if (parsedTargetTriple.getSubArch() != originalTargetTriple.getSubArch() &&
      parsedTargetTriple.getArch() == originalTargetTriple.getArch() &&
      parsedTargetTriple.getVendor() == originalTargetTriple.getVendor() &&
      parsedTargetTriple.getOS() == originalTargetTriple.getOS() &&
      parsedTargetTriple.getEnvironment()
        == originalTargetTriple.getEnvironment()) {
    parsedTargetTriple.setArchName(originalTargetTriple.getArchName());
    subInvocation.setTargetTriple(parsedTargetTriple.str());
  }

  CompilerInstance subInstance;
  SubCompilerInstanceInfo info;
  info.Instance = &subInstance;
  info.CompilerVersion = CompilerVersion;

  subInstance.getSourceMgr().setFileSystem(SM.getFileSystem());

  ForwardingDiagnosticConsumer FDC(*Diags);
  subInstance.addDiagnosticConsumer(&FDC);
  std::string InstanceSetupError;
  if (subInstance.setup(subInvocation, InstanceSetupError)) {
    return std::make_error_code(std::errc::not_supported);
  }

  info.BuildArguments = BuildArgs;
  info.Hash = CacheHash;
  auto target = *(std::find(BuildArgs.rbegin(), BuildArgs.rend(), "-target") - 1);
  auto langVersion = *(std::find(BuildArgs.rbegin(), BuildArgs.rend(),
                                 "-swift-version") - 1);

  std::vector<StringRef> ExtraPCMArgs = {
    // PCMs should use the effective Swift language version for apinotes.
    "-Xcc",
    ArgSaver.save((llvm::Twine("-fapinotes-swift-version=") + langVersion).str())
  };
  if (!subInvocation.getLangOptions().ClangTarget.hasValue()) {
    ExtraPCMArgs.insert(ExtraPCMArgs.begin(), {"-Xcc", "-target",
                                               "-Xcc", target});
  }

  info.ExtraPCMArgs = ExtraPCMArgs;
  // Run the action under the sub compiler instance.
  return action(info);
}

struct ExplicitSwiftModuleLoader::Implementation {
  ASTContext &Ctx;
  llvm::BumpPtrAllocator Allocator;
  llvm::StringMap<ExplicitModuleInfo> ExplicitModuleMap;
  Implementation(ASTContext &Ctx) : Ctx(Ctx) {}

  void parseSwiftExplicitModuleMap(StringRef fileName) {
    ExplicitModuleMapParser parser(Allocator);
    auto result =
        parser.parseSwiftExplicitModuleMap(fileName, ExplicitModuleMap);
    if (result == std::errc::invalid_argument)
      Ctx.Diags.diagnose(SourceLoc(), diag::explicit_swift_module_map_corrupted,
                         fileName);
    else if (result == std::errc::no_such_file_or_directory)
      Ctx.Diags.diagnose(SourceLoc(), diag::explicit_swift_module_map_missing,
                         fileName);
  }
};

ExplicitSwiftModuleLoader::ExplicitSwiftModuleLoader(
      ASTContext &ctx,
      DependencyTracker *tracker,
      ModuleLoadingMode loadMode,
      bool IgnoreSwiftSourceInfoFile):
        SerializedModuleLoaderBase(ctx, tracker, loadMode,
                                   IgnoreSwiftSourceInfoFile),
        Impl(*new Implementation(ctx)) {}

ExplicitSwiftModuleLoader::~ExplicitSwiftModuleLoader() { delete &Impl; }

bool ExplicitSwiftModuleLoader::findModule(ImportPath::Element ModuleID,
           SmallVectorImpl<char> *ModuleInterfacePath,
           std::unique_ptr<llvm::MemoryBuffer> *ModuleBuffer,
           std::unique_ptr<llvm::MemoryBuffer> *ModuleDocBuffer,
           std::unique_ptr<llvm::MemoryBuffer> *ModuleSourceInfoBuffer,
           bool skipBuildingInterface, bool &IsFramework, bool &IsSystemModule) {
  // Find a module with an actual, physical name on disk, in case
  // -module-alias is used (otherwise same).
  //
  // For example, if '-module-alias Foo=Bar' is passed in to the frontend, and an
  // input file has 'import Foo', a module called Bar (real name) should be searched.
  StringRef moduleName = Ctx.getRealModuleName(ModuleID.Item).str();

  auto it = Impl.ExplicitModuleMap.find(moduleName);
  // If no explicit module path is given matches the name, return with an
  // error code.
  if (it == Impl.ExplicitModuleMap.end()) {
    return false;
  }
  auto &moduleInfo = it->getValue();

  // Set IsFramework bit according to the moduleInfo
  IsFramework = moduleInfo.isFramework;
  IsSystemModule = moduleInfo.isSystem;

  auto &fs = *Ctx.SourceMgr.getFileSystem();
  // Open .swiftmodule file
  auto moduleBuf = fs.getBufferForFile(moduleInfo.modulePath);
  if (!moduleBuf) {
    // We cannot read the module content, diagnose.
    Ctx.Diags.diagnose(SourceLoc(), diag::error_opening_explicit_module_file,
                       moduleInfo.modulePath);
    return false;
  }

  assert(moduleBuf);
  const bool isForwardingModule = !serialization::isSerializedAST(moduleBuf
    .get()->getBuffer());
  // If the module is a forwarding module, read the actual content from the path
  // encoded in the forwarding module as the actual module content.
  if (isForwardingModule) {
    auto forwardingModule = ForwardingModule::load(*moduleBuf.get());
    if (forwardingModule) {
      moduleBuf = fs.getBufferForFile(forwardingModule->underlyingModulePath);
      if (!moduleBuf) {
        // We cannot read the module content, diagnose.
        Ctx.Diags.diagnose(SourceLoc(), diag::error_opening_explicit_module_file,
                           moduleInfo.modulePath);
        return false;
      }
    } else {
      // We cannot read the module content, diagnose.
      Ctx.Diags.diagnose(SourceLoc(), diag::error_opening_explicit_module_file,
                         moduleInfo.modulePath);
      return false;
    }
  }
  assert(moduleBuf);
  // Move the opened module buffer to the caller.
  *ModuleBuffer = std::move(moduleBuf.get());

  // Open .swiftdoc file
  if (!moduleInfo.moduleDocPath.empty()) {
    auto moduleDocBuf = fs.getBufferForFile(moduleInfo.moduleDocPath);
    if (moduleBuf)
      *ModuleDocBuffer = std::move(moduleDocBuf.get());
  }
  // Open .swiftsourceinfo file
  if (!moduleInfo.moduleSourceInfoPath.empty()) {
    auto moduleSourceInfoBuf = fs.getBufferForFile(moduleInfo.moduleSourceInfoPath);
    if (moduleSourceInfoBuf)
      *ModuleSourceInfoBuffer = std::move(moduleSourceInfoBuf.get());
  }
  return true;
}

std::error_code ExplicitSwiftModuleLoader::findModuleFilesInDirectory(
  ImportPath::Element ModuleID,
  const SerializedModuleBaseName &BaseName,
  SmallVectorImpl<char> *ModuleInterfacePath,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleBuffer,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleDocBuffer,
  std::unique_ptr<llvm::MemoryBuffer> *ModuleSourceInfoBuffer,
  bool skipBuildingInterface, bool IsFramework) {
  llvm_unreachable("Not supported in the Explicit Swift Module Loader.");
  return std::make_error_code(std::errc::not_supported);
}

bool ExplicitSwiftModuleLoader::canImportModule(ImportPath::Module path,
                                                llvm::VersionTuple version,
                                                bool underlyingVersion) {
  // FIXME: Swift submodules?
  ImportPath::Element mID = path.front();
  // Look up the module with the real name (physical name on disk);
  // in case `-module-alias` is used, the name appearing in source files
  // and the real module name are different. For example, '-module-alias Foo=Bar'
  // maps Foo appearing in source files, e.g. 'import Foo', to the real module
  // name Bar (on-disk name), which should be searched for loading.
  StringRef moduleName = Ctx.getRealModuleName(mID.Item).str();
  auto it = Impl.ExplicitModuleMap.find(moduleName);
  // If no provided explicit module matches the name, then it cannot be imported.
  if (it == Impl.ExplicitModuleMap.end()) {
    return false;
  }
  return true;
}

void ExplicitSwiftModuleLoader::collectVisibleTopLevelModuleNames(
      SmallVectorImpl<Identifier> &names) const {
  for (auto &entry: Impl.ExplicitModuleMap) {
    names.push_back(Ctx.getIdentifier(entry.getKey()));
  }
}

std::unique_ptr<ExplicitSwiftModuleLoader>
ExplicitSwiftModuleLoader::create(ASTContext &ctx,
    DependencyTracker *tracker, ModuleLoadingMode loadMode,
    StringRef ExplicitSwiftModuleMap,
    bool IgnoreSwiftSourceInfoFile) {
  auto result = std::unique_ptr<ExplicitSwiftModuleLoader>(
    new ExplicitSwiftModuleLoader(ctx, tracker, loadMode,
                                  IgnoreSwiftSourceInfoFile));
  auto &Impl = result->Impl;
  // If the explicit module map is given, try parse it.
  if (!ExplicitSwiftModuleMap.empty()) {
    // Parse a JSON file to collect explicitly built modules.
    Impl.parseSwiftExplicitModuleMap(ExplicitSwiftModuleMap);
  }

  return result;
}


text:
function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; var ownKeys = Object.keys(source); if (typeof Object.getOwnPropertySymbols === 'function') { ownKeys = ownKeys.concat(Object.getOwnPropertySymbols(source).filter(function (sym) { return Object.getOwnPropertyDescriptor(source, sym).enumerable; })); } ownKeys.forEach(function (key) { _defineProperty(target, key, source[key]); }); } return target; }

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

z = _objectSpread({
  x
}, y);
z = {
  x,
  w: _objectSpread({}, y)
};

redpajama_set_name: RedPajamaGithub


text:
package com.google.inject.matcher;

import static com.google.inject.Asserts.assertEqualWhenReserialized;
import static com.google.inject.Asserts.assertEqualsBothWays;
import static com.google.inject.matcher.Matchers.annotatedWith;
import static com.google.inject.matcher.Matchers.any;
import static com.google.inject.matcher.Matchers.identicalTo;
import static com.google.inject.matcher.Matchers.inPackage;
import static com.google.inject.matcher.Matchers.inSubpackage;
import static com.google.inject.matcher.Matchers.not;
import static com.google.inject.matcher.Matchers.only;
import static com.google.inject.matcher.Matchers.returns;
import static com.google.inject.matcher.Matchers.subclassesOf;

import com.google.inject.name.Named;
import com.google.inject.name.Names;

import junit.framework.TestCase;

import java.io.IOException;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;
import java.util.AbstractList;

/**
 * @author crazybob@google.com (Bob Lee)
 */

public class MatcherTest extends TestCase {

  public void testAny() {
    assertTrue(any().matches(null));
    assertEquals("any()", any().toString());
    assertEqualsBothWays(any(), any());
    assertFalse(any().equals(not(any())));
  }

  public void testNot() {
    assertFalse(not(any()).matches(null));
    assertEquals("not(any())", not(any()).toString());
    assertEqualsBothWays(not(any()), not(any()));
    assertFalse(not(any()).equals(any()));
  }

  public void testAnd() {
    assertTrue(any().and(any()).matches(null));
    assertFalse(any().and(not(any())).matches(null));
    assertEquals("and(any(), any())", any().and(any()).toString());
    assertEqualsBothWays(any().and(any()), any().and(any()));
    assertFalse(any().and(any()).equals(not(any())));
  }

  public void testOr() {
    assertTrue(any().or(not(any())).matches(null));
    assertFalse(not(any()).or(not(any())).matches(null));
    assertEquals("or(any(), any())", any().or(any()).toString());
    assertEqualsBothWays(any().or(any()), any().or(any()));
    assertFalse(any().or(any()).equals(not(any())));
  }

  public void testAnnotatedWith() {
    assertTrue(annotatedWith(Foo.class).matches(Bar.class));
    assertFalse(annotatedWith(Foo.class).matches(
        MatcherTest.class.getMethods()[0]));
    assertEquals("annotatedWith(Foo.class)", annotatedWith(Foo.class).toString());
    assertEqualsBothWays(annotatedWith(Foo.class), annotatedWith(Foo.class));
    assertFalse(annotatedWith(Foo.class).equals(annotatedWith(Named.class)));

    try {
      annotatedWith(Baz.class);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testSubclassesOf() {
    assertTrue(subclassesOf(Runnable.class).matches(Runnable.class));
    assertTrue(subclassesOf(Runnable.class).matches(MyRunnable.class));
    assertFalse(subclassesOf(Runnable.class).matches(Object.class));
    assertEquals("subclassesOf(Runnable.class)", subclassesOf(Runnable.class).toString());
    assertEqualsBothWays(subclassesOf(Runnable.class), subclassesOf(Runnable.class));
    assertFalse(subclassesOf(Runnable.class).equals(subclassesOf(Object.class)));
  }

  public void testOnly() {
    assertTrue(only(1000).matches(1000));
    assertFalse(only(1).matches(1000));
    assertEquals("only(1)", only(1).toString());
    assertEqualsBothWays(only(1), only(1));
    assertFalse(only(1).equals(only(2)));
  }

  @SuppressWarnings("UnnecessaryBoxing")
  public void testIdenticalTo() {
    Object o = new Object();
    assertEquals("identicalTo(1)", identicalTo(1).toString());
    assertTrue(identicalTo(o).matches(o));
    assertFalse(identicalTo(o).matches(new Object()));
    assertEqualsBothWays(identicalTo(o), identicalTo(o));
    assertFalse(identicalTo(1).equals(identicalTo(new Integer(1))));
  }

  public void testInPackage() {
    Package matchersPackage = Matchers.class.getPackage();
    assertEquals("inPackage(com.google.inject.matcher)", inPackage(matchersPackage).toString());
    assertTrue(inPackage(matchersPackage).matches(MatcherTest.class));
    assertFalse(inPackage(matchersPackage).matches(Object.class));
    assertEqualsBothWays(inPackage(matchersPackage), inPackage(matchersPackage));
    assertFalse(inPackage(matchersPackage).equals(inPackage(Object.class.getPackage())));
  }

  public void testInSubpackage() {
    String stringPackageName = String.class.getPackage().getName();
    assertEquals("inSubpackage(java.lang)", inSubpackage(stringPackageName).toString());
    assertTrue(inSubpackage(stringPackageName).matches(Object.class));
    assertTrue(inSubpackage(stringPackageName).matches(Method.class));
    assertFalse(inSubpackage(stringPackageName).matches(Matchers.class));
    assertFalse(inSubpackage("jav").matches(Object.class));
    assertEqualsBothWays(inSubpackage(stringPackageName), inSubpackage(stringPackageName));
    assertFalse(inSubpackage(stringPackageName).equals(inSubpackage(Matchers.class.getPackage().getName())));
  }

  public void testReturns() throws NoSuchMethodException {
    Matcher<Method> predicate = returns(only(String.class));
    assertTrue(predicate.matches(
        Object.class.getMethod("toString")));
    assertFalse(predicate.matches(
        Object.class.getMethod("hashCode")));
    assertEquals("returns(only(class java.lang.String))", returns(only(String.class)).toString());
    assertEqualsBothWays(predicate, returns(only(String.class)));
    assertFalse(predicate.equals(returns(only(Integer.class))));
  }

  public void testSerialization() throws IOException {
    assertEqualWhenReserialized(any());
    assertEqualWhenReserialized(not(any()));
    assertEqualWhenReserialized(annotatedWith(Named.class));
    assertEqualWhenReserialized(annotatedWith(Names.named("foo")));
    assertEqualWhenReserialized(only("foo"));
    assertEqualWhenReserialized(identicalTo(Object.class));
    assertEqualWhenReserialized(inPackage(String.class.getPackage()));
    assertEqualWhenReserialized(inSubpackage(String.class.getPackage().getName()));
    assertEqualWhenReserialized(returns(any()));
    assertEqualWhenReserialized(subclassesOf(AbstractList.class));
    assertEqualWhenReserialized(only("a").or(only("b")));
    assertEqualWhenReserialized(only("a").and(only("b")));
  }

  static abstract class MyRunnable implements Runnable {}

  @Retention(RetentionPolicy.RUNTIME)
  @interface Foo {}

  @Foo
  static class Bar {}

  @interface Baz {}

  @Baz
  static class Car {}
}


text:
<?php namespace App\Services\Html;

class HtmlServiceProvider extends \Collective\Html\HtmlServiceProvider {

    /**
     * Register the form builder instance.
     */
    protected function registerFormBuilder()
    {
        $this->app->bindShared('form', function($app)
        {
            $form = new FormBuilder($app['html'], $app['url'], $app['session.store']->getToken());

            return $form->setSessionStore($app['session.store']);
        });
    }

}


text:
layout: page
title: Little Research Dinner
date: 2016-05-24
author: Frank Petty
tags: weekly links, java
status: published
summary: Fusce tempor viverra nisi sit amet iaculis.
banner: images/banner/meeting-01.jpg
booking:
  startDate: 02/22/2017
  endDate: 02/27/2017
  ctyhocn: INDCMHX
  groupCode: LRD
published: true
---
Pellentesque a semper est. Maecenas eu accumsan diam, at sodales purus. Vestibulum sit amet massa velit. Cras aliquet dictum convallis. Aenean congue molestie pretium. Nulla aliquet, lacus at finibus placerat, dolor lacus sodales velit, vel porttitor turpis diam vel elit. Phasellus metus ligula, accumsan in vehicula ac, feugiat eleifend sem. Donec venenatis malesuada vehicula. Pellentesque ut odio eu sapien dapibus mollis. Vestibulum at rhoncus nunc. Donec lacinia tortor vel odio tristique ultrices. Mauris tempor eros sit amet augue maximus, non vehicula eros ultrices. Ut sagittis feugiat varius. Suspendisse condimentum felis ut condimentum facilisis.

* Donec eget magna malesuada, posuere diam nec, congue dolor
* Nunc eget tortor non tortor eleifend tincidunt
* Sed ut nibh quis arcu rhoncus dictum
* Pellentesque vitae eros quis dolor laoreet semper
* Donec ut neque faucibus, varius enim nec, fringilla enim
* Donec ac velit consectetur, molestie leo non, vulputate sapien.

Curabitur varius laoreet metus, non finibus odio accumsan a. Donec iaculis arcu nec sem porta, ac feugiat eros ullamcorper. Suspendisse feugiat elit id arcu fringilla, vitae auctor odio vestibulum. Donec pellentesque, felis eu semper commodo, mauris nunc tincidunt purus, at facilisis mi sem in dui. Aenean tellus erat, condimentum sit amet vestibulum id, aliquet vitae est. Sed luctus purus mauris, et congue est mollis non. Proin ac nisi est. Curabitur risus elit, dictum vel massa vitae, bibendum accumsan neque. Vestibulum at libero id lorem mattis semper eget quis mi. Morbi diam neque, placerat quis volutpat eu, aliquam id felis. Curabitur vulputate rutrum neque, id aliquet felis finibus a. Sed eu tortor ac libero pretium varius. In sed urna nisl. In eu vehicula felis. Donec id consequat sem.