//===- Module.h - Describe a module -----------------------------*- C++ -*-===//
 
//
 
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 
// See https://llvm.org/LICENSE.txt for license information.
 
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
//
 
//===----------------------------------------------------------------------===//
 
//
 
/// \file
 
/// Defines the clang::Module class, which describes a module in the
 
/// source code.
 
//
 
//===----------------------------------------------------------------------===//
 
 
 
#ifndef LLVM_CLANG_BASIC_MODULE_H
 
#define LLVM_CLANG_BASIC_MODULE_H
 
 
 
#include "clang/Basic/DirectoryEntry.h"
 
#include "clang/Basic/FileEntry.h"
 
#include "clang/Basic/SourceLocation.h"
 
#include "llvm/ADT/ArrayRef.h"
 
#include "llvm/ADT/DenseSet.h"
 
#include "llvm/ADT/PointerIntPair.h"
 
#include "llvm/ADT/STLExtras.h"
 
#include "llvm/ADT/SetVector.h"
 
#include "llvm/ADT/SmallVector.h"
 
#include "llvm/ADT/StringMap.h"
 
#include "llvm/ADT/StringRef.h"
 
#include "llvm/ADT/iterator_range.h"
 
#include <array>
 
#include <cassert>
 
#include <cstdint>
 
#include <ctime>
 
#include <iterator>
 
#include <optional>
 
#include <string>
 
#include <utility>
 
#include <vector>
 
 
 
namespace llvm {
 
 
 
class raw_ostream;
 
 
 
} // namespace llvm
 
 
 
namespace clang {
 
 
 
class FileManager;
 
class LangOptions;
 
class TargetInfo;
 
 
 
/// Describes the name of a module.
 
using ModuleId = SmallVector<std::pair<std::string, SourceLocation>, 2>;
 
 
 
/// The signature of a module, which is a hash of the AST content.
 
struct ASTFileSignature : std::array<uint8_t, 20> {
 
  using BaseT = std::array<uint8_t, 20>;
 
 
 
  static constexpr size_t size = std::tuple_size<BaseT>::value;
 
 
 
  ASTFileSignature(BaseT S = {{0}}) : BaseT(std::move(S)) {}
 
 
 
  explicit operator bool() const { return *this != BaseT({{0}}); }
 
 
 
  /// Returns the value truncated to the size of an uint64_t.
 
  uint64_t truncatedValue() const {
 
    uint64_t Value = 0;
 
    static_assert(sizeof(*this) >= sizeof(uint64_t), "No need to truncate.");
 
    for (unsigned I = 0; I < sizeof(uint64_t); ++I)
 
      Value |= static_cast<uint64_t>((*this)[I]) << (I * 8);
 
    return Value;
 
  }
 
 
 
  static ASTFileSignature create(std::array<uint8_t, 20> Bytes) {
 
    return ASTFileSignature(std::move(Bytes));
 
  }
 
 
 
  static ASTFileSignature createDISentinel() {
 
    ASTFileSignature Sentinel;
 
    Sentinel.fill(0xFF);
 
    return Sentinel;
 
  }
 
 
 
  template <typename InputIt>
 
  static ASTFileSignature create(InputIt First, InputIt Last) {
 
    assert(std::distance(First, Last) == size &&
 
           "Wrong amount of bytes to create an ASTFileSignature");
 
 
 
    ASTFileSignature Signature;
 
    std::copy(First, Last, Signature.begin());
 
    return Signature;
 
  }
 
};
 
 
 
/// Describes a module or submodule.
 
///
 
/// Aligned to 8 bytes to allow for llvm::PointerIntPair<Module *, 3>.
 
class alignas(8) Module {
 
public:
 
  /// The name of this module.
 
  std::string Name;
 
 
 
  /// The location of the module definition.
 
  SourceLocation DefinitionLoc;
 
 
 
  enum ModuleKind {
 
    /// This is a module that was defined by a module map and built out
 
    /// of header files.
 
    ModuleMapModule,
 
 
 
    /// This is a C++20 module interface unit.
 
    ModuleInterfaceUnit,
 
 
 
    /// This is a C++ 20 header unit.
 
    ModuleHeaderUnit,
 
 
 
    /// This is a C++ 20 module partition interface.
 
    ModulePartitionInterface,
 
 
 
    /// This is a C++ 20 module partition implementation.
 
    ModulePartitionImplementation,
 
 
 
    /// This is a fragment of the global module within some C++ module.
 
    GlobalModuleFragment,
 
 
 
    /// This is the private module fragment within some C++ module.
 
    PrivateModuleFragment,
 
  };
 
 
 
  /// The kind of this module.
 
  ModuleKind Kind = ModuleMapModule;
 
 
 
  /// The parent of this module. This will be NULL for the top-level
 
  /// module.
 
  Module *Parent;
 
 
 
  /// The build directory of this module. This is the directory in
 
  /// which the module is notionally built, and relative to which its headers
 
  /// are found.
 
  const DirectoryEntry *Directory = nullptr;
 
 
 
  /// The presumed file name for the module map defining this module.
 
  /// Only non-empty when building from preprocessed source.
 
  std::string PresumedModuleMapFile;
 
 
 
  /// The umbrella header or directory.
 
  llvm::PointerUnion<const FileEntryRef::MapEntry *, const DirectoryEntry *>
 
      Umbrella;
 
 
 
  /// The module signature.
 
  ASTFileSignature Signature;
 
 
 
  /// The name of the umbrella entry, as written in the module map.
 
  std::string UmbrellaAsWritten;
 
 
 
  // The path to the umbrella entry relative to the root module's \c Directory.
 
  std::string UmbrellaRelativeToRootModuleDirectory;
 
 
 
  /// The module through which entities defined in this module will
 
  /// eventually be exposed, for use in "private" modules.
 
  std::string ExportAsModule;
 
 
 
  /// Does this Module scope describe part of the purview of a standard named
 
  /// C++ module?
 
  bool isModulePurview() const {
 
    return Kind == ModuleInterfaceUnit || Kind == ModulePartitionInterface ||
 
           Kind == ModulePartitionImplementation ||
 
           Kind == PrivateModuleFragment;
 
  }
 
 
 
  /// Does this Module scope describe a fragment of the global module within
 
  /// some C++ module.
 
  bool isGlobalModule() const { return Kind == GlobalModuleFragment; }
 
 
 
  bool isPrivateModule() const { return Kind == PrivateModuleFragment; }
 
 
 
  bool isModuleMapModule() const { return Kind == ModuleMapModule; }
 
 
 
private:
 
  /// The submodules of this module, indexed by name.
 
  std::vector<Module *> SubModules;
 
 
 
  /// A mapping from the submodule name to the index into the
 
  /// \c SubModules vector at which that submodule resides.
 
  llvm::StringMap<unsigned> SubModuleIndex;
 
 
 
  /// The AST file if this is a top-level module which has a
 
  /// corresponding serialized AST file, or null otherwise.
 
  OptionalFileEntryRef ASTFile;
 
 
 
  /// The top-level headers associated with this module.
 
  llvm::SmallSetVector<const FileEntry *, 2> TopHeaders;
 
 
 
  /// top-level header filenames that aren't resolved to FileEntries yet.
 
  std::vector<std::string> TopHeaderNames;
 
 
 
  /// Cache of modules visible to lookup in this module.
 
  mutable llvm::DenseSet<const Module*> VisibleModulesCache;
 
 
 
  /// The ID used when referencing this module within a VisibleModuleSet.
 
  unsigned VisibilityID;
 
 
 
public:
 
  enum HeaderKind {
 
    HK_Normal,
 
    HK_Textual,
 
    HK_Private,
 
    HK_PrivateTextual,
 
    HK_Excluded
 
  };
 
  static const int NumHeaderKinds = HK_Excluded + 1;
 
 
 
  /// Information about a header directive as found in the module map
 
  /// file.
 
  struct Header {
 
    std::string NameAsWritten;
 
    std::string PathRelativeToRootModuleDirectory;
 
    OptionalFileEntryRefDegradesToFileEntryPtr Entry;
 
 
 
    explicit operator bool() { return Entry.has_value(); }
 
  };
 
 
 
  /// Information about a directory name as found in the module map
 
  /// file.
 
  struct DirectoryName {
 
    std::string NameAsWritten;
 
    std::string PathRelativeToRootModuleDirectory;
 
    const DirectoryEntry *Entry;
 
 
 
    explicit operator bool() { return Entry; }
 
  };
 
 
 
  /// The headers that are part of this module.
 
  SmallVector<Header, 2> Headers[5];
 
 
 
  /// Stored information about a header directive that was found in the
 
  /// module map file but has not been resolved to a file.
 
  struct UnresolvedHeaderDirective {
 
    HeaderKind Kind = HK_Normal;
 
    SourceLocation FileNameLoc;
 
    std::string FileName;
 
    bool IsUmbrella = false;
 
    bool HasBuiltinHeader = false;
 
    std::optional<off_t> Size;
 
    std::optional<time_t> ModTime;
 
  };
 
 
 
  /// Headers that are mentioned in the module map file but that we have not
 
  /// yet attempted to resolve to a file on the file system.
 
  SmallVector<UnresolvedHeaderDirective, 1> UnresolvedHeaders;
 
 
 
  /// Headers that are mentioned in the module map file but could not be
 
  /// found on the file system.
 
  SmallVector<UnresolvedHeaderDirective, 1> MissingHeaders;
 
 
 
  /// An individual requirement: a feature name and a flag indicating
 
  /// the required state of that feature.
 
  using Requirement = std::pair<std::string, bool>;
 
 
 
  /// The set of language features required to use this module.
 
  ///
 
  /// If any of these requirements are not available, the \c IsAvailable bit
 
  /// will be false to indicate that this (sub)module is not available.
 
  SmallVector<Requirement, 2> Requirements;
 
 
 
  /// A module with the same name that shadows this module.
 
  Module *ShadowingModule = nullptr;
 
 
 
  /// Whether this module has declared itself unimportable, either because
 
  /// it's missing a requirement from \p Requirements or because it's been
 
  /// shadowed by another module.
 
  unsigned IsUnimportable : 1;
 
 
 
  /// Whether we tried and failed to load a module file for this module.
 
  unsigned HasIncompatibleModuleFile : 1;
 
 
 
  /// Whether this module is available in the current translation unit.
 
  ///
 
  /// If the module is missing headers or does not meet all requirements then
 
  /// this bit will be 0.
 
  unsigned IsAvailable : 1;
 
 
 
  /// Whether this module was loaded from a module file.
 
  unsigned IsFromModuleFile : 1;
 
 
 
  /// Whether this is a framework module.
 
  unsigned IsFramework : 1;
 
 
 
  /// Whether this is an explicit submodule.
 
  unsigned IsExplicit : 1;
 
 
 
  /// Whether this is a "system" module (which assumes that all
 
  /// headers in it are system headers).
 
  unsigned IsSystem : 1;
 
 
 
  /// Whether this is an 'extern "C"' module (which implicitly puts all
 
  /// headers in it within an 'extern "C"' block, and allows the module to be
 
  /// imported within such a block).
 
  unsigned IsExternC : 1;
 
 
 
  /// Whether this is an inferred submodule (module * { ... }).
 
  unsigned IsInferred : 1;
 
 
 
  /// Whether we should infer submodules for this module based on
 
  /// the headers.
 
  ///
 
  /// Submodules can only be inferred for modules with an umbrella header.
 
  unsigned InferSubmodules : 1;
 
 
 
  /// Whether, when inferring submodules, the inferred submodules
 
  /// should be explicit.
 
  unsigned InferExplicitSubmodules : 1;
 
 
 
  /// Whether, when inferring submodules, the inferr submodules should
 
  /// export all modules they import (e.g., the equivalent of "export *").
 
  unsigned InferExportWildcard : 1;
 
 
 
  /// Whether the set of configuration macros is exhaustive.
 
  ///
 
  /// When the set of configuration macros is exhaustive, meaning
 
  /// that no identifier not in this list should affect how the module is
 
  /// built.
 
  unsigned ConfigMacrosExhaustive : 1;
 
 
 
  /// Whether files in this module can only include non-modular headers
 
  /// and headers from used modules.
 
  unsigned NoUndeclaredIncludes : 1;
 
 
 
  /// Whether this module came from a "private" module map, found next
 
  /// to a regular (public) module map.
 
  unsigned ModuleMapIsPrivate : 1;
 
 
 
  /// Describes the visibility of the various names within a
 
  /// particular module.
 
  enum NameVisibilityKind {
 
    /// All of the names in this module are hidden.
 
    Hidden,
 
    /// All of the names in this module are visible.
 
    AllVisible
 
  };
 
 
 
  /// The visibility of names within this particular module.
 
  NameVisibilityKind NameVisibility;
 
 
 
  /// The location of the inferred submodule.
 
  SourceLocation InferredSubmoduleLoc;
 
 
 
  /// The set of modules imported by this module, and on which this
 
  /// module depends.
 
  llvm::SmallSetVector<Module *, 2> Imports;
 
 
 
  /// The set of top-level modules that affected the compilation of this module,
 
  /// but were not imported.
 
  llvm::SmallSetVector<Module *, 2> AffectingClangModules;
 
 
 
  /// Describes an exported module.
 
  ///
 
  /// The pointer is the module being re-exported, while the bit will be true
 
  /// to indicate that this is a wildcard export.
 
  using ExportDecl = llvm::PointerIntPair<Module *, 1, bool>;
 
 
 
  /// The set of export declarations.
 
  SmallVector<ExportDecl, 2> Exports;
 
 
 
  /// Describes an exported module that has not yet been resolved
 
  /// (perhaps because the module it refers to has not yet been loaded).
 
  struct UnresolvedExportDecl {
 
    /// The location of the 'export' keyword in the module map file.
 
    SourceLocation ExportLoc;
 
 
 
    /// The name of the module.
 
    ModuleId Id;
 
 
 
    /// Whether this export declaration ends in a wildcard, indicating
 
    /// that all of its submodules should be exported (rather than the named
 
    /// module itself).
 
    bool Wildcard;
 
  };
 
 
 
  /// The set of export declarations that have yet to be resolved.
 
  SmallVector<UnresolvedExportDecl, 2> UnresolvedExports;
 
 
 
  /// The directly used modules.
 
  SmallVector<Module *, 2> DirectUses;
 
 
 
  /// The set of use declarations that have yet to be resolved.
 
  SmallVector<ModuleId, 2> UnresolvedDirectUses;
 
 
 
  /// When \c NoUndeclaredIncludes is true, the set of modules this module tried
 
  /// to import but didn't because they are not direct uses.
 
  llvm::SmallSetVector<const Module *, 2> UndeclaredUses;
 
 
 
  /// A library or framework to link against when an entity from this
 
  /// module is used.
 
  struct LinkLibrary {
 
    LinkLibrary() = default;
 
    LinkLibrary(const std::string &Library, bool IsFramework)
 
        : Library(Library), IsFramework(IsFramework) {}
 
 
 
    /// The library to link against.
 
    ///
 
    /// This will typically be a library or framework name, but can also
 
    /// be an absolute path to the library or framework.
 
    std::string Library;
 
 
 
    /// Whether this is a framework rather than a library.
 
    bool IsFramework = false;
 
  };
 
 
 
  /// The set of libraries or frameworks to link against when
 
  /// an entity from this module is used.
 
  llvm::SmallVector<LinkLibrary, 2> LinkLibraries;
 
 
 
  /// Autolinking uses the framework name for linking purposes
 
  /// when this is false and the export_as name otherwise.
 
  bool UseExportAsModuleLinkName = false;
 
 
 
  /// The set of "configuration macros", which are macros that
 
  /// (intentionally) change how this module is built.
 
  std::vector<std::string> ConfigMacros;
 
 
 
  /// An unresolved conflict with another module.
 
  struct UnresolvedConflict {
 
    /// The (unresolved) module id.
 
    ModuleId Id;
 
 
 
    /// The message provided to the user when there is a conflict.
 
    std::string Message;
 
  };
 
 
 
  /// The list of conflicts for which the module-id has not yet been
 
  /// resolved.
 
  std::vector<UnresolvedConflict> UnresolvedConflicts;
 
 
 
  /// A conflict between two modules.
 
  struct Conflict {
 
    /// The module that this module conflicts with.
 
    Module *Other;
 
 
 
    /// The message provided to the user when there is a conflict.
 
    std::string Message;
 
  };
 
 
 
  /// The list of conflicts.
 
  std::vector<Conflict> Conflicts;
 
 
 
  /// Construct a new module or submodule.
 
  Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent,
 
         bool IsFramework, bool IsExplicit, unsigned VisibilityID);
 
 
 
  ~Module();
 
 
 
  /// Determine whether this module has been declared unimportable.
 
  bool isUnimportable() const { return IsUnimportable; }
 
 
 
  /// Determine whether this module has been declared unimportable.
 
  ///
 
  /// \param LangOpts The language options used for the current
 
  /// translation unit.
 
  ///
 
  /// \param Target The target options used for the current translation unit.
 
  ///
 
  /// \param Req If this module is unimportable because of a missing
 
  /// requirement, this parameter will be set to one of the requirements that
 
  /// is not met for use of this module.
 
  ///
 
  /// \param ShadowingModule If this module is unimportable because it is
 
  /// shadowed, this parameter will be set to the shadowing module.
 
  bool isUnimportable(const LangOptions &LangOpts, const TargetInfo &Target,
 
                      Requirement &Req, Module *&ShadowingModule) const;
 
 
 
  /// Determine whether this module can be built in this compilation.
 
  bool isForBuilding(const LangOptions &LangOpts) const;
 
 
 
  /// Determine whether this module is available for use within the
 
  /// current translation unit.
 
  bool isAvailable() const { return IsAvailable; }
 
 
 
  /// Determine whether this module is available for use within the
 
  /// current translation unit.
 
  ///
 
  /// \param LangOpts The language options used for the current
 
  /// translation unit.
 
  ///
 
  /// \param Target The target options used for the current translation unit.
 
  ///
 
  /// \param Req If this module is unavailable because of a missing requirement,
 
  /// this parameter will be set to one of the requirements that is not met for
 
  /// use of this module.
 
  ///
 
  /// \param MissingHeader If this module is unavailable because of a missing
 
  /// header, this parameter will be set to one of the missing headers.
 
  ///
 
  /// \param ShadowingModule If this module is unavailable because it is
 
  /// shadowed, this parameter will be set to the shadowing module.
 
  bool isAvailable(const LangOptions &LangOpts,
 
                   const TargetInfo &Target,
 
                   Requirement &Req,
 
                   UnresolvedHeaderDirective &MissingHeader,
 
                   Module *&ShadowingModule) const;
 
 
 
  /// Determine whether this module is a submodule.
 
  bool isSubModule() const { return Parent != nullptr; }
 
 
 
  /// Check if this module is a (possibly transitive) submodule of \p Other.
 
  ///
 
  /// The 'A is a submodule of B' relation is a partial order based on the
 
  /// the parent-child relationship between individual modules.
 
  ///
 
  /// Returns \c false if \p Other is \c nullptr.
 
  bool isSubModuleOf(const Module *Other) const;
 
 
 
  /// Determine whether this module is a part of a framework,
 
  /// either because it is a framework module or because it is a submodule
 
  /// of a framework module.
 
  bool isPartOfFramework() const {
 
    for (const Module *Mod = this; Mod; Mod = Mod->Parent)
 
      if (Mod->IsFramework)
 
        return true;
 
 
 
    return false;
 
  }
 
 
 
  /// Determine whether this module is a subframework of another
 
  /// framework.
 
  bool isSubFramework() const {
 
    return IsFramework && Parent && Parent->isPartOfFramework();
 
  }
 
 
 
  /// Set the parent of this module. This should only be used if the parent
 
  /// could not be set during module creation.
 
  void setParent(Module *M) {
 
    assert(!Parent);
 
    Parent = M;
 
    Parent->SubModuleIndex[Name] = Parent->SubModules.size();
 
    Parent->SubModules.push_back(this);
 
  }
 
 
 
  /// Is this module have similar semantics as headers.
 
  bool isHeaderLikeModule() const {
 
    return isModuleMapModule() || isHeaderUnit();
 
  }
 
 
 
  /// Is this a module partition.
 
  bool isModulePartition() const {
 
    return Kind == ModulePartitionInterface ||
 
           Kind == ModulePartitionImplementation;
 
  }
 
 
 
  /// Is this module a header unit.
 
  bool isHeaderUnit() const { return Kind == ModuleHeaderUnit; }
 
  // Is this a C++20 module interface or a partition.
 
  bool isInterfaceOrPartition() const {
 
    return Kind == ModuleInterfaceUnit || isModulePartition();
 
  }
 
 
 
  bool isModuleInterfaceUnit() const {
 
    return Kind == ModuleInterfaceUnit || Kind == ModulePartitionInterface;
 
  }
 
 
 
  /// Get the primary module interface name from a partition.
 
  StringRef getPrimaryModuleInterfaceName() const {
 
    // Technically, global module fragment belongs to global module. And global
 
    // module has no name: [module.unit]p6:
 
    //   The global module has no name, no module interface unit, and is not
 
    //   introduced by any module-declaration.
 
    //
 
    // <global> is the default name showed in module map.
 
    if (isGlobalModule())
 
      return "<global>";
 
 
 
    if (isModulePartition()) {
 
      auto pos = Name.find(':');
 
      return StringRef(Name.data(), pos);
 
    }
 
 
 
    if (isPrivateModule())
 
      return getTopLevelModuleName();
 
 
 
    return Name;
 
  }
 
 
 
  /// Retrieve the full name of this module, including the path from
 
  /// its top-level module.
 
  /// \param AllowStringLiterals If \c true, components that might not be
 
  ///        lexically valid as identifiers will be emitted as string literals.
 
  std::string getFullModuleName(bool AllowStringLiterals = false) const;
 
 
 
  /// Whether the full name of this module is equal to joining
 
  /// \p nameParts with "."s.
 
  ///
 
  /// This is more efficient than getFullModuleName().
 
  bool fullModuleNameIs(ArrayRef<StringRef> nameParts) const;
 
 
 
  /// Retrieve the top-level module for this (sub)module, which may
 
  /// be this module.
 
  Module *getTopLevelModule() {
 
    return const_cast<Module *>(
 
             const_cast<const Module *>(this)->getTopLevelModule());
 
  }
 
 
 
  /// Retrieve the top-level module for this (sub)module, which may
 
  /// be this module.
 
  const Module *getTopLevelModule() const;
 
 
 
  /// Retrieve the name of the top-level module.
 
  StringRef getTopLevelModuleName() const {
 
    return getTopLevelModule()->Name;
 
  }
 
 
 
  /// The serialized AST file for this module, if one was created.
 
  OptionalFileEntryRefDegradesToFileEntryPtr getASTFile() const {
 
    return getTopLevelModule()->ASTFile;
 
  }
 
 
 
  /// Set the serialized AST file for the top-level module of this module.
 
  void setASTFile(OptionalFileEntryRef File) {
 
    assert((!getASTFile() || getASTFile() == File) && "file path changed");
 
    getTopLevelModule()->ASTFile = File;
 
  }
 
 
 
  /// Retrieve the directory for which this module serves as the
 
  /// umbrella.
 
  DirectoryName getUmbrellaDir() const;
 
 
 
  /// Retrieve the header that serves as the umbrella header for this
 
  /// module.
 
  Header getUmbrellaHeader() const {
 
    if (auto *ME = Umbrella.dyn_cast<const FileEntryRef::MapEntry *>())
 
      return Header{UmbrellaAsWritten, UmbrellaRelativeToRootModuleDirectory,
 
                    FileEntryRef(*ME)};
 
    return Header{};
 
  }
 
 
 
  /// Determine whether this module has an umbrella directory that is
 
  /// not based on an umbrella header.
 
  bool hasUmbrellaDir() const {
 
    return Umbrella && Umbrella.is<const DirectoryEntry *>();
 
  }
 
 
 
  /// Add a top-level header associated with this module.
 
  void addTopHeader(const FileEntry *File);
 
 
 
  /// Add a top-level header filename associated with this module.
 
  void addTopHeaderFilename(StringRef Filename) {
 
    TopHeaderNames.push_back(std::string(Filename));
 
  }
 
 
 
  /// The top-level headers associated with this module.
 
  ArrayRef<const FileEntry *> getTopHeaders(FileManager &FileMgr);
 
 
 
  /// Determine whether this module has declared its intention to
 
  /// directly use another module.
 
  bool directlyUses(const Module *Requested);
 
 
 
  /// Add the given feature requirement to the list of features
 
  /// required by this module.
 
  ///
 
  /// \param Feature The feature that is required by this module (and
 
  /// its submodules).
 
  ///
 
  /// \param RequiredState The required state of this feature: \c true
 
  /// if it must be present, \c false if it must be absent.
 
  ///
 
  /// \param LangOpts The set of language options that will be used to
 
  /// evaluate the availability of this feature.
 
  ///
 
  /// \param Target The target options that will be used to evaluate the
 
  /// availability of this feature.
 
  void addRequirement(StringRef Feature, bool RequiredState,
 
                      const LangOptions &LangOpts,
 
                      const TargetInfo &Target);
 
 
 
  /// Mark this module and all of its submodules as unavailable.
 
  void markUnavailable(bool Unimportable);
 
 
 
  /// Find the submodule with the given name.
 
  ///
 
  /// \returns The submodule if found, or NULL otherwise.
 
  Module *findSubmodule(StringRef Name) const;
 
  Module *findOrInferSubmodule(StringRef Name);
 
 
 
  /// Get the Global Module Fragment (sub-module) for this module, it there is
 
  /// one.
 
  ///
 
  /// \returns The GMF sub-module if found, or NULL otherwise.
 
  Module *getGlobalModuleFragment() { return findSubmodule("<global>"); }
 
 
 
  /// Get the Private Module Fragment (sub-module) for this module, it there is
 
  /// one.
 
  ///
 
  /// \returns The PMF sub-module if found, or NULL otherwise.
 
  Module *getPrivateModuleFragment() { return findSubmodule("<private>"); }
 
 
 
  /// Determine whether the specified module would be visible to
 
  /// a lookup at the end of this module.
 
  ///
 
  /// FIXME: This may return incorrect results for (submodules of) the
 
  /// module currently being built, if it's queried before we see all
 
  /// of its imports.
 
  bool isModuleVisible(const Module *M) const {
 
    if (VisibleModulesCache.empty())
 
      buildVisibleModulesCache();
 
    return VisibleModulesCache.count(M);
 
  }
 
 
 
  unsigned getVisibilityID() const { return VisibilityID; }
 
 
 
  using submodule_iterator = std::vector<Module *>::iterator;
 
  using submodule_const_iterator = std::vector<Module *>::const_iterator;
 
 
 
  submodule_iterator submodule_begin() { return SubModules.begin(); }
 
  submodule_const_iterator submodule_begin() const {return SubModules.begin();}
 
  submodule_iterator submodule_end()   { return SubModules.end(); }
 
  submodule_const_iterator submodule_end() const { return SubModules.end(); }
 
 
 
  llvm::iterator_range<submodule_iterator> submodules() {
 
    return llvm::make_range(submodule_begin(), submodule_end());
 
  }
 
  llvm::iterator_range<submodule_const_iterator> submodules() const {
 
    return llvm::make_range(submodule_begin(), submodule_end());
 
  }
 
 
 
  /// Appends this module's list of exported modules to \p Exported.
 
  ///
 
  /// This provides a subset of immediately imported modules (the ones that are
 
  /// directly exported), not the complete set of exported modules.
 
  void getExportedModules(SmallVectorImpl<Module *> &Exported) const;
 
 
 
  static StringRef getModuleInputBufferName() {
 
    return "<module-includes>";
 
  }
 
 
 
  /// Print the module map for this module to the given stream.
 
  void print(raw_ostream &OS, unsigned Indent = 0, bool Dump = false) const;
 
 
 
  /// Dump the contents of this module to the given output stream.
 
  void dump() const;
 
 
 
private:
 
  void buildVisibleModulesCache() const;
 
};
 
 
 
/// A set of visible modules.
 
class VisibleModuleSet {
 
public:
 
  VisibleModuleSet() = default;
 
  VisibleModuleSet(VisibleModuleSet &&O)
 
      : ImportLocs(std::move(O.ImportLocs)), Generation(O.Generation ? 1 : 0) {
 
    O.ImportLocs.clear();
 
    ++O.Generation;
 
  }
 
 
 
  /// Move from another visible modules set. Guaranteed to leave the source
 
  /// empty and bump the generation on both.
 
  VisibleModuleSet &operator=(VisibleModuleSet &&O) {
 
    ImportLocs = std::move(O.ImportLocs);
 
    O.ImportLocs.clear();
 
    ++O.Generation;
 
    ++Generation;
 
    return *this;
 
  }
 
 
 
  /// Get the current visibility generation. Incremented each time the
 
  /// set of visible modules changes in any way.
 
  unsigned getGeneration() const { return Generation; }
 
 
 
  /// Determine whether a module is visible.
 
  bool isVisible(const Module *M) const {
 
    return getImportLoc(M).isValid();
 
  }
 
 
 
  /// Get the location at which the import of a module was triggered.
 
  SourceLocation getImportLoc(const Module *M) const {
 
    return M->getVisibilityID() < ImportLocs.size()
 
               ? ImportLocs[M->getVisibilityID()]
 
               : SourceLocation();
 
  }
 
 
 
  /// A callback to call when a module is made visible (directly or
 
  /// indirectly) by a call to \ref setVisible.
 
  using VisibleCallback = llvm::function_ref<void(Module *M)>;
 
 
 
  /// A callback to call when a module conflict is found. \p Path
 
  /// consists of a sequence of modules from the conflicting module to the one
 
  /// made visible, where each was exported by the next.
 
  using ConflictCallback =
 
      llvm::function_ref<void(ArrayRef<Module *> Path, Module *Conflict,
 
                         StringRef Message)>;
 
 
 
  /// Make a specific module visible.
 
  void setVisible(Module *M, SourceLocation Loc,
 
                  VisibleCallback Vis = [](Module *) {},
 
                  ConflictCallback Cb = [](ArrayRef<Module *>, Module *,
 
                                           StringRef) {});
 
 
 
private:
 
  /// Import locations for each visible module. Indexed by the module's
 
  /// VisibilityID.
 
  std::vector<SourceLocation> ImportLocs;
 
 
 
  /// Visibility generation, bumped every time the visibility state changes.
 
  unsigned Generation = 0;
 
};
 
 
 
/// Abstracts clang modules and precompiled header files and holds
 
/// everything needed to generate debug info for an imported module
 
/// or PCH.
 
class ASTSourceDescriptor {
 
  StringRef PCHModuleName;
 
  StringRef Path;
 
  StringRef ASTFile;
 
  ASTFileSignature Signature;
 
  Module *ClangModule = nullptr;
 
 
 
public:
 
  ASTSourceDescriptor() = default;
 
  ASTSourceDescriptor(StringRef Name, StringRef Path, StringRef ASTFile,
 
                      ASTFileSignature Signature)
 
      : PCHModuleName(std::move(Name)), Path(std::move(Path)),
 
        ASTFile(std::move(ASTFile)), Signature(Signature) {}
 
  ASTSourceDescriptor(Module &M);
 
 
 
  std::string getModuleName() const;
 
  StringRef getPath() const { return Path; }
 
  StringRef getASTFile() const { return ASTFile; }
 
  ASTFileSignature getSignature() const { return Signature; }
 
  Module *getModuleOrNull() const { return ClangModule; }
 
};
 
 
 
 
 
} // namespace clang
 
 
 
#endif // LLVM_CLANG_BASIC_MODULE_H