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  1. //===- ModuleMap.h - Describe the layout of modules -------------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. // This file defines the ModuleMap interface, which describes the layout of a
  10. // module as it relates to headers.
  11. //
  12. //===----------------------------------------------------------------------===//
  13.  
  14. #ifndef LLVM_CLANG_LEX_MODULEMAP_H
  15. #define LLVM_CLANG_LEX_MODULEMAP_H
  16.  
  17. #include "clang/Basic/IdentifierTable.h"
  18. #include "clang/Basic/LangOptions.h"
  19. #include "clang/Basic/Module.h"
  20. #include "clang/Basic/SourceLocation.h"
  21. #include "llvm/ADT/ArrayRef.h"
  22. #include "llvm/ADT/DenseMap.h"
  23. #include "llvm/ADT/PointerIntPair.h"
  24. #include "llvm/ADT/SmallPtrSet.h"
  25. #include "llvm/ADT/SmallVector.h"
  26. #include "llvm/ADT/StringMap.h"
  27. #include "llvm/ADT/StringRef.h"
  28. #include "llvm/ADT/StringSet.h"
  29. #include "llvm/ADT/TinyPtrVector.h"
  30. #include "llvm/ADT/Twine.h"
  31. #include <ctime>
  32. #include <memory>
  33. #include <optional>
  34. #include <string>
  35. #include <utility>
  36.  
  37. namespace clang {
  38.  
  39. class DiagnosticsEngine;
  40. class DirectoryEntry;
  41. class FileEntry;
  42. class FileManager;
  43. class HeaderSearch;
  44. class SourceManager;
  45.  
  46. /// A mechanism to observe the actions of the module map parser as it
  47. /// reads module map files.
  48. class ModuleMapCallbacks {
  49.   virtual void anchor();
  50.  
  51. public:
  52.   virtual ~ModuleMapCallbacks() = default;
  53.  
  54.   /// Called when a module map file has been read.
  55.   ///
  56.   /// \param FileStart A SourceLocation referring to the start of the file's
  57.   /// contents.
  58.   /// \param File The file itself.
  59.   /// \param IsSystem Whether this is a module map from a system include path.
  60.   virtual void moduleMapFileRead(SourceLocation FileStart,
  61.                                  const FileEntry &File, bool IsSystem) {}
  62.  
  63.   /// Called when a header is added during module map parsing.
  64.   ///
  65.   /// \param Filename The header file itself.
  66.   virtual void moduleMapAddHeader(StringRef Filename) {}
  67.  
  68.   /// Called when an umbrella header is added during module map parsing.
  69.   ///
  70.   /// \param FileMgr FileManager instance
  71.   /// \param Header The umbrella header to collect.
  72.   virtual void moduleMapAddUmbrellaHeader(FileManager *FileMgr,
  73.                                           const FileEntry *Header) {}
  74. };
  75.  
  76. class ModuleMap {
  77.   SourceManager &SourceMgr;
  78.   DiagnosticsEngine &Diags;
  79.   const LangOptions &LangOpts;
  80.   const TargetInfo *Target;
  81.   HeaderSearch &HeaderInfo;
  82.  
  83.   llvm::SmallVector<std::unique_ptr<ModuleMapCallbacks>, 1> Callbacks;
  84.  
  85.   /// The directory used for Clang-supplied, builtin include headers,
  86.   /// such as "stdint.h".
  87.   const DirectoryEntry *BuiltinIncludeDir = nullptr;
  88.  
  89.   /// Language options used to parse the module map itself.
  90.   ///
  91.   /// These are always simple C language options.
  92.   LangOptions MMapLangOpts;
  93.  
  94.   /// The module that the main source file is associated with (the module
  95.   /// named LangOpts::CurrentModule, if we've loaded it).
  96.   Module *SourceModule = nullptr;
  97.  
  98.   /// Submodules of the current module that have not yet been attached to it.
  99.   /// (Ownership is transferred if/when we create an enclosing module.)
  100.   llvm::SmallVector<std::unique_ptr<Module>, 8> PendingSubmodules;
  101.  
  102.   /// The top-level modules that are known.
  103.   llvm::StringMap<Module *> Modules;
  104.  
  105.   /// Module loading cache that includes submodules, indexed by IdentifierInfo.
  106.   /// nullptr is stored for modules that are known to fail to load.
  107.   llvm::DenseMap<const IdentifierInfo *, Module *> CachedModuleLoads;
  108.  
  109.   /// Shadow modules created while building this module map.
  110.   llvm::SmallVector<Module*, 2> ShadowModules;
  111.  
  112.   /// The number of modules we have created in total.
  113.   unsigned NumCreatedModules = 0;
  114.  
  115.   /// In case a module has a export_as entry, it might have a pending link
  116.   /// name to be determined if that module is imported.
  117.   llvm::StringMap<llvm::StringSet<>> PendingLinkAsModule;
  118.  
  119. public:
  120.   /// Use PendingLinkAsModule information to mark top level link names that
  121.   /// are going to be replaced by export_as aliases.
  122.   void resolveLinkAsDependencies(Module *Mod);
  123.  
  124.   /// Make module to use export_as as the link dependency name if enough
  125.   /// information is available or add it to a pending list otherwise.
  126.   void addLinkAsDependency(Module *Mod);
  127.  
  128.   /// Flags describing the role of a module header.
  129.   enum ModuleHeaderRole {
  130.     /// This header is normally included in the module.
  131.     NormalHeader  = 0x0,
  132.  
  133.     /// This header is included but private.
  134.     PrivateHeader = 0x1,
  135.  
  136.     /// This header is part of the module (for layering purposes) but
  137.     /// should be textually included.
  138.     TextualHeader = 0x2,
  139.  
  140.     /// This header is explicitly excluded from the module.
  141.     ExcludedHeader = 0x4,
  142.  
  143.     // Caution: Adding an enumerator needs other changes.
  144.     // Adjust the number of bits for KnownHeader::Storage.
  145.     // Adjust the HeaderFileInfoTrait::ReadData streaming.
  146.     // Adjust the HeaderFileInfoTrait::EmitData streaming.
  147.     // Adjust ModuleMap::addHeader.
  148.   };
  149.  
  150.   /// Convert a header kind to a role. Requires Kind to not be HK_Excluded.
  151.   static ModuleHeaderRole headerKindToRole(Module::HeaderKind Kind);
  152.  
  153.   /// Convert a header role to a kind.
  154.   static Module::HeaderKind headerRoleToKind(ModuleHeaderRole Role);
  155.  
  156.   /// Check if the header with the given role is a modular one.
  157.   static bool isModular(ModuleHeaderRole Role);
  158.  
  159.   /// A header that is known to reside within a given module,
  160.   /// whether it was included or excluded.
  161.   class KnownHeader {
  162.     llvm::PointerIntPair<Module *, 3, ModuleHeaderRole> Storage;
  163.  
  164.   public:
  165.     KnownHeader() : Storage(nullptr, NormalHeader) {}
  166.     KnownHeader(Module *M, ModuleHeaderRole Role) : Storage(M, Role) {}
  167.  
  168.     friend bool operator==(const KnownHeader &A, const KnownHeader &B) {
  169.       return A.Storage == B.Storage;
  170.     }
  171.     friend bool operator!=(const KnownHeader &A, const KnownHeader &B) {
  172.       return A.Storage != B.Storage;
  173.     }
  174.  
  175.     /// Retrieve the module the header is stored in.
  176.     Module *getModule() const { return Storage.getPointer(); }
  177.  
  178.     /// The role of this header within the module.
  179.     ModuleHeaderRole getRole() const { return Storage.getInt(); }
  180.  
  181.     /// Whether this header is available in the module.
  182.     bool isAvailable() const {
  183.       return getRole() != ExcludedHeader && getModule()->isAvailable();
  184.     }
  185.  
  186.     /// Whether this header is accessible from the specified module.
  187.     bool isAccessibleFrom(Module *M) const {
  188.       return !(getRole() & PrivateHeader) ||
  189.              (M && M->getTopLevelModule() == getModule()->getTopLevelModule());
  190.     }
  191.  
  192.     // Whether this known header is valid (i.e., it has an
  193.     // associated module).
  194.     explicit operator bool() const {
  195.       return Storage.getPointer() != nullptr;
  196.     }
  197.   };
  198.  
  199.   using AdditionalModMapsSet = llvm::SmallPtrSet<const FileEntry *, 1>;
  200.  
  201. private:
  202.   friend class ModuleMapParser;
  203.  
  204.   using HeadersMap =
  205.       llvm::DenseMap<const FileEntry *, SmallVector<KnownHeader, 1>>;
  206.  
  207.   /// Mapping from each header to the module that owns the contents of
  208.   /// that header.
  209.   HeadersMap Headers;
  210.  
  211.   /// Map from file sizes to modules with lazy header directives of that size.
  212.   mutable llvm::DenseMap<off_t, llvm::TinyPtrVector<Module*>> LazyHeadersBySize;
  213.  
  214.   /// Map from mtimes to modules with lazy header directives with those mtimes.
  215.   mutable llvm::DenseMap<time_t, llvm::TinyPtrVector<Module*>>
  216.               LazyHeadersByModTime;
  217.  
  218.   /// Mapping from directories with umbrella headers to the module
  219.   /// that is generated from the umbrella header.
  220.   ///
  221.   /// This mapping is used to map headers that haven't explicitly been named
  222.   /// in the module map over to the module that includes them via its umbrella
  223.   /// header.
  224.   llvm::DenseMap<const DirectoryEntry *, Module *> UmbrellaDirs;
  225.  
  226.   /// A generation counter that is used to test whether modules of the
  227.   /// same name may shadow or are illegal redefinitions.
  228.   ///
  229.   /// Modules from earlier scopes may shadow modules from later ones.
  230.   /// Modules from the same scope may not have the same name.
  231.   unsigned CurrentModuleScopeID = 0;
  232.  
  233.   llvm::DenseMap<Module *, unsigned> ModuleScopeIDs;
  234.  
  235.   /// The set of attributes that can be attached to a module.
  236.   struct Attributes {
  237.     /// Whether this is a system module.
  238.     unsigned IsSystem : 1;
  239.  
  240.     /// Whether this is an extern "C" module.
  241.     unsigned IsExternC : 1;
  242.  
  243.     /// Whether this is an exhaustive set of configuration macros.
  244.     unsigned IsExhaustive : 1;
  245.  
  246.     /// Whether files in this module can only include non-modular headers
  247.     /// and headers from used modules.
  248.     unsigned NoUndeclaredIncludes : 1;
  249.  
  250.     Attributes()
  251.         : IsSystem(false), IsExternC(false), IsExhaustive(false),
  252.           NoUndeclaredIncludes(false) {}
  253.   };
  254.  
  255.   /// A directory for which framework modules can be inferred.
  256.   struct InferredDirectory {
  257.     /// Whether to infer modules from this directory.
  258.     unsigned InferModules : 1;
  259.  
  260.     /// The attributes to use for inferred modules.
  261.     Attributes Attrs;
  262.  
  263.     /// If \c InferModules is non-zero, the module map file that allowed
  264.     /// inferred modules.  Otherwise, nullptr.
  265.     const FileEntry *ModuleMapFile;
  266.  
  267.     /// The names of modules that cannot be inferred within this
  268.     /// directory.
  269.     SmallVector<std::string, 2> ExcludedModules;
  270.  
  271.     InferredDirectory() : InferModules(false) {}
  272.   };
  273.  
  274.   /// A mapping from directories to information about inferring
  275.   /// framework modules from within those directories.
  276.   llvm::DenseMap<const DirectoryEntry *, InferredDirectory> InferredDirectories;
  277.  
  278.   /// A mapping from an inferred module to the module map that allowed the
  279.   /// inference.
  280.   llvm::DenseMap<const Module *, const FileEntry *> InferredModuleAllowedBy;
  281.  
  282.   llvm::DenseMap<const Module *, AdditionalModMapsSet> AdditionalModMaps;
  283.  
  284.   /// Describes whether we haved parsed a particular file as a module
  285.   /// map.
  286.   llvm::DenseMap<const FileEntry *, bool> ParsedModuleMap;
  287.  
  288.   /// Resolve the given export declaration into an actual export
  289.   /// declaration.
  290.   ///
  291.   /// \param Mod The module in which we're resolving the export declaration.
  292.   ///
  293.   /// \param Unresolved The export declaration to resolve.
  294.   ///
  295.   /// \param Complain Whether this routine should complain about unresolvable
  296.   /// exports.
  297.   ///
  298.   /// \returns The resolved export declaration, which will have a NULL pointer
  299.   /// if the export could not be resolved.
  300.   Module::ExportDecl
  301.   resolveExport(Module *Mod, const Module::UnresolvedExportDecl &Unresolved,
  302.                 bool Complain) const;
  303.  
  304.   /// Resolve the given module id to an actual module.
  305.   ///
  306.   /// \param Id The module-id to resolve.
  307.   ///
  308.   /// \param Mod The module in which we're resolving the module-id.
  309.   ///
  310.   /// \param Complain Whether this routine should complain about unresolvable
  311.   /// module-ids.
  312.   ///
  313.   /// \returns The resolved module, or null if the module-id could not be
  314.   /// resolved.
  315.   Module *resolveModuleId(const ModuleId &Id, Module *Mod, bool Complain) const;
  316.  
  317.   /// Add an unresolved header to a module.
  318.   ///
  319.   /// \param Mod The module in which we're adding the unresolved header
  320.   ///        directive.
  321.   /// \param Header The unresolved header directive.
  322.   /// \param NeedsFramework If Mod is not a framework but a missing header would
  323.   ///        be found in case Mod was, set it to true. False otherwise.
  324.   void addUnresolvedHeader(Module *Mod,
  325.                            Module::UnresolvedHeaderDirective Header,
  326.                            bool &NeedsFramework);
  327.  
  328.   /// Look up the given header directive to find an actual header file.
  329.   ///
  330.   /// \param M The module in which we're resolving the header directive.
  331.   /// \param Header The header directive to resolve.
  332.   /// \param RelativePathName Filled in with the relative path name from the
  333.   ///        module to the resolved header.
  334.   /// \param NeedsFramework If M is not a framework but a missing header would
  335.   ///        be found in case M was, set it to true. False otherwise.
  336.   /// \return The resolved file, if any.
  337.   OptionalFileEntryRef
  338.   findHeader(Module *M, const Module::UnresolvedHeaderDirective &Header,
  339.              SmallVectorImpl<char> &RelativePathName, bool &NeedsFramework);
  340.  
  341.   /// Resolve the given header directive.
  342.   ///
  343.   /// \param M The module in which we're resolving the header directive.
  344.   /// \param Header The header directive to resolve.
  345.   /// \param NeedsFramework If M is not a framework but a missing header would
  346.   ///        be found in case M was, set it to true. False otherwise.
  347.   void resolveHeader(Module *M, const Module::UnresolvedHeaderDirective &Header,
  348.                      bool &NeedsFramework);
  349.  
  350.   /// Attempt to resolve the specified header directive as naming a builtin
  351.   /// header.
  352.   /// \return \c true if a corresponding builtin header was found.
  353.   bool resolveAsBuiltinHeader(Module *M,
  354.                               const Module::UnresolvedHeaderDirective &Header);
  355.  
  356.   /// Looks up the modules that \p File corresponds to.
  357.   ///
  358.   /// If \p File represents a builtin header within Clang's builtin include
  359.   /// directory, this also loads all of the module maps to see if it will get
  360.   /// associated with a specific module (e.g. in /usr/include).
  361.   HeadersMap::iterator findKnownHeader(const FileEntry *File);
  362.  
  363.   /// Searches for a module whose umbrella directory contains \p File.
  364.   ///
  365.   /// \param File The header to search for.
  366.   ///
  367.   /// \param IntermediateDirs On success, contains the set of directories
  368.   /// searched before finding \p File.
  369.   KnownHeader findHeaderInUmbrellaDirs(const FileEntry *File,
  370.                     SmallVectorImpl<const DirectoryEntry *> &IntermediateDirs);
  371.  
  372.   /// Given that \p File is not in the Headers map, look it up within
  373.   /// umbrella directories and find or create a module for it.
  374.   KnownHeader findOrCreateModuleForHeaderInUmbrellaDir(const FileEntry *File);
  375.  
  376.   /// A convenience method to determine if \p File is (possibly nested)
  377.   /// in an umbrella directory.
  378.   bool isHeaderInUmbrellaDirs(const FileEntry *File) {
  379.     SmallVector<const DirectoryEntry *, 2> IntermediateDirs;
  380.     return static_cast<bool>(findHeaderInUmbrellaDirs(File, IntermediateDirs));
  381.   }
  382.  
  383.   Module *inferFrameworkModule(const DirectoryEntry *FrameworkDir,
  384.                                Attributes Attrs, Module *Parent);
  385.  
  386. public:
  387.   /// Construct a new module map.
  388.   ///
  389.   /// \param SourceMgr The source manager used to find module files and headers.
  390.   /// This source manager should be shared with the header-search mechanism,
  391.   /// since they will refer to the same headers.
  392.   ///
  393.   /// \param Diags A diagnostic engine used for diagnostics.
  394.   ///
  395.   /// \param LangOpts Language options for this translation unit.
  396.   ///
  397.   /// \param Target The target for this translation unit.
  398.   ModuleMap(SourceManager &SourceMgr, DiagnosticsEngine &Diags,
  399.             const LangOptions &LangOpts, const TargetInfo *Target,
  400.             HeaderSearch &HeaderInfo);
  401.  
  402.   /// Destroy the module map.
  403.   ~ModuleMap();
  404.  
  405.   /// Set the target information.
  406.   void setTarget(const TargetInfo &Target);
  407.  
  408.   /// Set the directory that contains Clang-supplied include
  409.   /// files, such as our stdarg.h or tgmath.h.
  410.   void setBuiltinIncludeDir(const DirectoryEntry *Dir) {
  411.     BuiltinIncludeDir = Dir;
  412.   }
  413.  
  414.   /// Get the directory that contains Clang-supplied include files.
  415.   const DirectoryEntry *getBuiltinDir() const {
  416.     return BuiltinIncludeDir;
  417.   }
  418.  
  419.   /// Is this a compiler builtin header?
  420.   static bool isBuiltinHeader(StringRef FileName);
  421.   bool isBuiltinHeader(const FileEntry *File);
  422.  
  423.   /// Add a module map callback.
  424.   void addModuleMapCallbacks(std::unique_ptr<ModuleMapCallbacks> Callback) {
  425.     Callbacks.push_back(std::move(Callback));
  426.   }
  427.  
  428.   /// Retrieve the module that owns the given header file, if any. Note that
  429.   /// this does not implicitly load module maps, except for builtin headers,
  430.   /// and does not consult the external source. (Those checks are the
  431.   /// responsibility of \ref HeaderSearch.)
  432.   ///
  433.   /// \param File The header file that is likely to be included.
  434.   ///
  435.   /// \param AllowTextual If \c true and \p File is a textual header, return
  436.   /// its owning module. Otherwise, no KnownHeader will be returned if the
  437.   /// file is only known as a textual header.
  438.   ///
  439.   /// \returns The module KnownHeader, which provides the module that owns the
  440.   /// given header file.  The KnownHeader is default constructed to indicate
  441.   /// that no module owns this header file.
  442.   KnownHeader findModuleForHeader(const FileEntry *File,
  443.                                   bool AllowTextual = false,
  444.                                   bool AllowExcluded = false);
  445.  
  446.   /// Retrieve all the modules that contain the given header file. Note that
  447.   /// this does not implicitly load module maps, except for builtin headers,
  448.   /// and does not consult the external source. (Those checks are the
  449.   /// responsibility of \ref HeaderSearch.)
  450.   ///
  451.   /// Typically, \ref findModuleForHeader should be used instead, as it picks
  452.   /// the preferred module for the header.
  453.   ArrayRef<KnownHeader> findAllModulesForHeader(const FileEntry *File);
  454.  
  455.   /// Like \ref findAllModulesForHeader, but do not attempt to infer module
  456.   /// ownership from umbrella headers if we've not already done so.
  457.   ArrayRef<KnownHeader>
  458.   findResolvedModulesForHeader(const FileEntry *File) const;
  459.  
  460.   /// Resolve all lazy header directives for the specified file.
  461.   ///
  462.   /// This ensures that the HeaderFileInfo on HeaderSearch is up to date. This
  463.   /// is effectively internal, but is exposed so HeaderSearch can call it.
  464.   void resolveHeaderDirectives(const FileEntry *File) const;
  465.  
  466.   /// Resolve lazy header directives for the specified module. If File is
  467.   /// provided, only headers with same size and modtime are resolved. If File
  468.   /// is not set, all headers are resolved.
  469.   void resolveHeaderDirectives(Module *Mod,
  470.                                std::optional<const FileEntry *> File) const;
  471.  
  472.   /// Reports errors if a module must not include a specific file.
  473.   ///
  474.   /// \param RequestingModule The module including a file.
  475.   ///
  476.   /// \param RequestingModuleIsModuleInterface \c true if the inclusion is in
  477.   ///        the interface of RequestingModule, \c false if it's in the
  478.   ///        implementation of RequestingModule. Value is ignored and
  479.   ///        meaningless if RequestingModule is nullptr.
  480.   ///
  481.   /// \param FilenameLoc The location of the inclusion's filename.
  482.   ///
  483.   /// \param Filename The included filename as written.
  484.   ///
  485.   /// \param File The included file.
  486.   void diagnoseHeaderInclusion(Module *RequestingModule,
  487.                                bool RequestingModuleIsModuleInterface,
  488.                                SourceLocation FilenameLoc, StringRef Filename,
  489.                                FileEntryRef File);
  490.  
  491.   /// Determine whether the given header is part of a module
  492.   /// marked 'unavailable'.
  493.   bool isHeaderInUnavailableModule(const FileEntry *Header) const;
  494.  
  495.   /// Determine whether the given header is unavailable as part
  496.   /// of the specified module.
  497.   bool isHeaderUnavailableInModule(const FileEntry *Header,
  498.                                    const Module *RequestingModule) const;
  499.  
  500.   /// Retrieve a module with the given name.
  501.   ///
  502.   /// \param Name The name of the module to look up.
  503.   ///
  504.   /// \returns The named module, if known; otherwise, returns null.
  505.   Module *findModule(StringRef Name) const;
  506.  
  507.   /// Retrieve a module with the given name using lexical name lookup,
  508.   /// starting at the given context.
  509.   ///
  510.   /// \param Name The name of the module to look up.
  511.   ///
  512.   /// \param Context The module context, from which we will perform lexical
  513.   /// name lookup.
  514.   ///
  515.   /// \returns The named module, if known; otherwise, returns null.
  516.   Module *lookupModuleUnqualified(StringRef Name, Module *Context) const;
  517.  
  518.   /// Retrieve a module with the given name within the given context,
  519.   /// using direct (qualified) name lookup.
  520.   ///
  521.   /// \param Name The name of the module to look up.
  522.   ///
  523.   /// \param Context The module for which we will look for a submodule. If
  524.   /// null, we will look for a top-level module.
  525.   ///
  526.   /// \returns The named submodule, if known; otherwose, returns null.
  527.   Module *lookupModuleQualified(StringRef Name, Module *Context) const;
  528.  
  529.   /// Find a new module or submodule, or create it if it does not already
  530.   /// exist.
  531.   ///
  532.   /// \param Name The name of the module to find or create.
  533.   ///
  534.   /// \param Parent The module that will act as the parent of this submodule,
  535.   /// or nullptr to indicate that this is a top-level module.
  536.   ///
  537.   /// \param IsFramework Whether this is a framework module.
  538.   ///
  539.   /// \param IsExplicit Whether this is an explicit submodule.
  540.   ///
  541.   /// \returns The found or newly-created module, along with a boolean value
  542.   /// that will be true if the module is newly-created.
  543.   std::pair<Module *, bool> findOrCreateModule(StringRef Name, Module *Parent,
  544.                                                bool IsFramework,
  545.                                                bool IsExplicit);
  546.  
  547.   /// Create a global module fragment for a C++ module unit.
  548.   ///
  549.   /// We model the global module fragment as a submodule of the module
  550.   /// interface unit. Unfortunately, we can't create the module interface
  551.   /// unit's Module until later, because we don't know what it will be called
  552.   /// usually. See C++20 [module.unit]/7.2 for the case we could know its
  553.   /// parent.
  554.   Module *createGlobalModuleFragmentForModuleUnit(SourceLocation Loc,
  555.                                                   Module *Parent = nullptr);
  556.  
  557.   /// Create a global module fragment for a C++ module interface unit.
  558.   Module *createPrivateModuleFragmentForInterfaceUnit(Module *Parent,
  559.                                                       SourceLocation Loc);
  560.  
  561.   /// Create a new module for a C++ module interface unit.
  562.   /// The module must not already exist, and will be configured for the current
  563.   /// compilation.
  564.   ///
  565.   /// Note that this also sets the current module to the newly-created module.
  566.   ///
  567.   /// \returns The newly-created module.
  568.   Module *createModuleForInterfaceUnit(SourceLocation Loc, StringRef Name);
  569.  
  570.   /// Create a C++20 header unit.
  571.   Module *createHeaderUnit(SourceLocation Loc, StringRef Name,
  572.                            Module::Header H);
  573.  
  574.   /// Infer the contents of a framework module map from the given
  575.   /// framework directory.
  576.   Module *inferFrameworkModule(const DirectoryEntry *FrameworkDir,
  577.                                bool IsSystem, Module *Parent);
  578.  
  579.   /// Create a new top-level module that is shadowed by
  580.   /// \p ShadowingModule.
  581.   Module *createShadowedModule(StringRef Name, bool IsFramework,
  582.                                Module *ShadowingModule);
  583.  
  584.   /// Creates a new declaration scope for module names, allowing
  585.   /// previously defined modules to shadow definitions from the new scope.
  586.   ///
  587.   /// \note Module names from earlier scopes will shadow names from the new
  588.   /// scope, which is the opposite of how shadowing works for variables.
  589.   void finishModuleDeclarationScope() { CurrentModuleScopeID += 1; }
  590.  
  591.   bool mayShadowNewModule(Module *ExistingModule) {
  592.     assert(!ExistingModule->Parent && "expected top-level module");
  593.     assert(ModuleScopeIDs.count(ExistingModule) && "unknown module");
  594.     return ModuleScopeIDs[ExistingModule] < CurrentModuleScopeID;
  595.   }
  596.  
  597.   /// Check whether a framework module can be inferred in the given directory.
  598.   bool canInferFrameworkModule(const DirectoryEntry *Dir) const {
  599.     auto It = InferredDirectories.find(Dir);
  600.     return It != InferredDirectories.end() && It->getSecond().InferModules;
  601.   }
  602.  
  603.   /// Retrieve the module map file containing the definition of the given
  604.   /// module.
  605.   ///
  606.   /// \param Module The module whose module map file will be returned, if known.
  607.   ///
  608.   /// \returns The file entry for the module map file containing the given
  609.   /// module, or nullptr if the module definition was inferred.
  610.   OptionalFileEntryRef getContainingModuleMapFile(const Module *Module) const;
  611.  
  612.   /// Get the module map file that (along with the module name) uniquely
  613.   /// identifies this module.
  614.   ///
  615.   /// The particular module that \c Name refers to may depend on how the module
  616.   /// was found in header search. However, the combination of \c Name and
  617.   /// this module map will be globally unique for top-level modules. In the case
  618.   /// of inferred modules, returns the module map that allowed the inference
  619.   /// (e.g. contained 'module *'). Otherwise, returns
  620.   /// getContainingModuleMapFile().
  621.   OptionalFileEntryRef getModuleMapFileForUniquing(const Module *M) const;
  622.  
  623.   void setInferredModuleAllowedBy(Module *M, const FileEntry *ModMap);
  624.  
  625.   /// Canonicalize \p Path in a manner suitable for a module map file. In
  626.   /// particular, this canonicalizes the parent directory separately from the
  627.   /// filename so that it does not affect header resolution relative to the
  628.   /// modulemap.
  629.   ///
  630.   /// \returns an error code if any filesystem operations failed. In this case
  631.   /// \p Path is not modified.
  632.   std::error_code canonicalizeModuleMapPath(SmallVectorImpl<char> &Path);
  633.  
  634.   /// Get any module map files other than getModuleMapFileForUniquing(M)
  635.   /// that define submodules of a top-level module \p M. This is cheaper than
  636.   /// getting the module map file for each submodule individually, since the
  637.   /// expected number of results is very small.
  638.   AdditionalModMapsSet *getAdditionalModuleMapFiles(const Module *M) {
  639.     auto I = AdditionalModMaps.find(M);
  640.     if (I == AdditionalModMaps.end())
  641.       return nullptr;
  642.     return &I->second;
  643.   }
  644.  
  645.   void addAdditionalModuleMapFile(const Module *M, const FileEntry *ModuleMap);
  646.  
  647.   /// Resolve all of the unresolved exports in the given module.
  648.   ///
  649.   /// \param Mod The module whose exports should be resolved.
  650.   ///
  651.   /// \param Complain Whether to emit diagnostics for failures.
  652.   ///
  653.   /// \returns true if any errors were encountered while resolving exports,
  654.   /// false otherwise.
  655.   bool resolveExports(Module *Mod, bool Complain);
  656.  
  657.   /// Resolve all of the unresolved uses in the given module.
  658.   ///
  659.   /// \param Mod The module whose uses should be resolved.
  660.   ///
  661.   /// \param Complain Whether to emit diagnostics for failures.
  662.   ///
  663.   /// \returns true if any errors were encountered while resolving uses,
  664.   /// false otherwise.
  665.   bool resolveUses(Module *Mod, bool Complain);
  666.  
  667.   /// Resolve all of the unresolved conflicts in the given module.
  668.   ///
  669.   /// \param Mod The module whose conflicts should be resolved.
  670.   ///
  671.   /// \param Complain Whether to emit diagnostics for failures.
  672.   ///
  673.   /// \returns true if any errors were encountered while resolving conflicts,
  674.   /// false otherwise.
  675.   bool resolveConflicts(Module *Mod, bool Complain);
  676.  
  677.   /// Sets the umbrella header of the given module to the given
  678.   /// header.
  679.   void setUmbrellaHeader(Module *Mod, FileEntryRef UmbrellaHeader,
  680.                          const Twine &NameAsWritten,
  681.                          const Twine &PathRelativeToRootModuleDirectory);
  682.  
  683.   /// Sets the umbrella directory of the given module to the given
  684.   /// directory.
  685.   void setUmbrellaDir(Module *Mod, const DirectoryEntry *UmbrellaDir,
  686.                       const Twine &NameAsWritten,
  687.                       const Twine &PathRelativeToRootModuleDirectory);
  688.  
  689.   /// Adds this header to the given module.
  690.   /// \param Role The role of the header wrt the module.
  691.   void addHeader(Module *Mod, Module::Header Header,
  692.                  ModuleHeaderRole Role, bool Imported = false);
  693.  
  694.   /// Parse the given module map file, and record any modules we
  695.   /// encounter.
  696.   ///
  697.   /// \param File The file to be parsed.
  698.   ///
  699.   /// \param IsSystem Whether this module map file is in a system header
  700.   /// directory, and therefore should be considered a system module.
  701.   ///
  702.   /// \param HomeDir The directory in which relative paths within this module
  703.   ///        map file will be resolved.
  704.   ///
  705.   /// \param ID The FileID of the file to process, if we've already entered it.
  706.   ///
  707.   /// \param Offset [inout] On input the offset at which to start parsing. On
  708.   ///        output, the offset at which the module map terminated.
  709.   ///
  710.   /// \param ExternModuleLoc The location of the "extern module" declaration
  711.   ///        that caused us to load this module map file, if any.
  712.   ///
  713.   /// \returns true if an error occurred, false otherwise.
  714.   bool parseModuleMapFile(const FileEntry *File, bool IsSystem,
  715.                           const DirectoryEntry *HomeDir,
  716.                           FileID ID = FileID(), unsigned *Offset = nullptr,
  717.                           SourceLocation ExternModuleLoc = SourceLocation());
  718.  
  719.   /// Dump the contents of the module map, for debugging purposes.
  720.   void dump();
  721.  
  722.   using module_iterator = llvm::StringMap<Module *>::const_iterator;
  723.  
  724.   module_iterator module_begin() const { return Modules.begin(); }
  725.   module_iterator module_end()   const { return Modules.end(); }
  726.   llvm::iterator_range<module_iterator> modules() const {
  727.     return {module_begin(), module_end()};
  728.   }
  729.  
  730.   /// Cache a module load.  M might be nullptr.
  731.   void cacheModuleLoad(const IdentifierInfo &II, Module *M) {
  732.     CachedModuleLoads[&II] = M;
  733.   }
  734.  
  735.   /// Return a cached module load.
  736.   std::optional<Module *> getCachedModuleLoad(const IdentifierInfo &II) {
  737.     auto I = CachedModuleLoads.find(&II);
  738.     if (I == CachedModuleLoads.end())
  739.       return std::nullopt;
  740.     return I->second;
  741.   }
  742. };
  743.  
  744. } // namespace clang
  745.  
  746. #endif // LLVM_CLANG_LEX_MODULEMAP_H
  747.