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  1. //===- Module.h - Describe a module -----------------------------*- 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. /// \file
  10. /// Defines the clang::Module class, which describes a module in the
  11. /// source code.
  12. //
  13. //===----------------------------------------------------------------------===//
  14.  
  15. #ifndef LLVM_CLANG_BASIC_MODULE_H
  16. #define LLVM_CLANG_BASIC_MODULE_H
  17.  
  18. #include "clang/Basic/DirectoryEntry.h"
  19. #include "clang/Basic/FileEntry.h"
  20. #include "clang/Basic/SourceLocation.h"
  21. #include "llvm/ADT/ArrayRef.h"
  22. #include "llvm/ADT/DenseSet.h"
  23. #include "llvm/ADT/PointerIntPair.h"
  24. #include "llvm/ADT/STLExtras.h"
  25. #include "llvm/ADT/SetVector.h"
  26. #include "llvm/ADT/SmallVector.h"
  27. #include "llvm/ADT/StringMap.h"
  28. #include "llvm/ADT/StringRef.h"
  29. #include "llvm/ADT/iterator_range.h"
  30. #include <array>
  31. #include <cassert>
  32. #include <cstdint>
  33. #include <ctime>
  34. #include <iterator>
  35. #include <optional>
  36. #include <string>
  37. #include <utility>
  38. #include <vector>
  39.  
  40. namespace llvm {
  41.  
  42. class raw_ostream;
  43.  
  44. } // namespace llvm
  45.  
  46. namespace clang {
  47.  
  48. class FileManager;
  49. class LangOptions;
  50. class TargetInfo;
  51.  
  52. /// Describes the name of a module.
  53. using ModuleId = SmallVector<std::pair<std::string, SourceLocation>, 2>;
  54.  
  55. /// The signature of a module, which is a hash of the AST content.
  56. struct ASTFileSignature : std::array<uint8_t, 20> {
  57.   using BaseT = std::array<uint8_t, 20>;
  58.  
  59.   static constexpr size_t size = std::tuple_size<BaseT>::value;
  60.  
  61.   ASTFileSignature(BaseT S = {{0}}) : BaseT(std::move(S)) {}
  62.  
  63.   explicit operator bool() const { return *this != BaseT({{0}}); }
  64.  
  65.   /// Returns the value truncated to the size of an uint64_t.
  66.   uint64_t truncatedValue() const {
  67.     uint64_t Value = 0;
  68.     static_assert(sizeof(*this) >= sizeof(uint64_t), "No need to truncate.");
  69.     for (unsigned I = 0; I < sizeof(uint64_t); ++I)
  70.       Value |= static_cast<uint64_t>((*this)[I]) << (I * 8);
  71.     return Value;
  72.   }
  73.  
  74.   static ASTFileSignature create(std::array<uint8_t, 20> Bytes) {
  75.     return ASTFileSignature(std::move(Bytes));
  76.   }
  77.  
  78.   static ASTFileSignature createDISentinel() {
  79.     ASTFileSignature Sentinel;
  80.     Sentinel.fill(0xFF);
  81.     return Sentinel;
  82.   }
  83.  
  84.   template <typename InputIt>
  85.   static ASTFileSignature create(InputIt First, InputIt Last) {
  86.     assert(std::distance(First, Last) == size &&
  87.            "Wrong amount of bytes to create an ASTFileSignature");
  88.  
  89.     ASTFileSignature Signature;
  90.     std::copy(First, Last, Signature.begin());
  91.     return Signature;
  92.   }
  93. };
  94.  
  95. /// Describes a module or submodule.
  96. ///
  97. /// Aligned to 8 bytes to allow for llvm::PointerIntPair<Module *, 3>.
  98. class alignas(8) Module {
  99. public:
  100.   /// The name of this module.
  101.   std::string Name;
  102.  
  103.   /// The location of the module definition.
  104.   SourceLocation DefinitionLoc;
  105.  
  106.   enum ModuleKind {
  107.     /// This is a module that was defined by a module map and built out
  108.     /// of header files.
  109.     ModuleMapModule,
  110.  
  111.     /// This is a C++20 module interface unit.
  112.     ModuleInterfaceUnit,
  113.  
  114.     /// This is a C++ 20 header unit.
  115.     ModuleHeaderUnit,
  116.  
  117.     /// This is a C++ 20 module partition interface.
  118.     ModulePartitionInterface,
  119.  
  120.     /// This is a C++ 20 module partition implementation.
  121.     ModulePartitionImplementation,
  122.  
  123.     /// This is a fragment of the global module within some C++ module.
  124.     GlobalModuleFragment,
  125.  
  126.     /// This is the private module fragment within some C++ module.
  127.     PrivateModuleFragment,
  128.   };
  129.  
  130.   /// The kind of this module.
  131.   ModuleKind Kind = ModuleMapModule;
  132.  
  133.   /// The parent of this module. This will be NULL for the top-level
  134.   /// module.
  135.   Module *Parent;
  136.  
  137.   /// The build directory of this module. This is the directory in
  138.   /// which the module is notionally built, and relative to which its headers
  139.   /// are found.
  140.   const DirectoryEntry *Directory = nullptr;
  141.  
  142.   /// The presumed file name for the module map defining this module.
  143.   /// Only non-empty when building from preprocessed source.
  144.   std::string PresumedModuleMapFile;
  145.  
  146.   /// The umbrella header or directory.
  147.   llvm::PointerUnion<const FileEntryRef::MapEntry *, const DirectoryEntry *>
  148.       Umbrella;
  149.  
  150.   /// The module signature.
  151.   ASTFileSignature Signature;
  152.  
  153.   /// The name of the umbrella entry, as written in the module map.
  154.   std::string UmbrellaAsWritten;
  155.  
  156.   // The path to the umbrella entry relative to the root module's \c Directory.
  157.   std::string UmbrellaRelativeToRootModuleDirectory;
  158.  
  159.   /// The module through which entities defined in this module will
  160.   /// eventually be exposed, for use in "private" modules.
  161.   std::string ExportAsModule;
  162.  
  163.   /// Does this Module scope describe part of the purview of a standard named
  164.   /// C++ module?
  165.   bool isModulePurview() const {
  166.     return Kind == ModuleInterfaceUnit || Kind == ModulePartitionInterface ||
  167.            Kind == ModulePartitionImplementation ||
  168.            Kind == PrivateModuleFragment;
  169.   }
  170.  
  171.   /// Does this Module scope describe a fragment of the global module within
  172.   /// some C++ module.
  173.   bool isGlobalModule() const { return Kind == GlobalModuleFragment; }
  174.  
  175.   bool isPrivateModule() const { return Kind == PrivateModuleFragment; }
  176.  
  177.   bool isModuleMapModule() const { return Kind == ModuleMapModule; }
  178.  
  179. private:
  180.   /// The submodules of this module, indexed by name.
  181.   std::vector<Module *> SubModules;
  182.  
  183.   /// A mapping from the submodule name to the index into the
  184.   /// \c SubModules vector at which that submodule resides.
  185.   llvm::StringMap<unsigned> SubModuleIndex;
  186.  
  187.   /// The AST file if this is a top-level module which has a
  188.   /// corresponding serialized AST file, or null otherwise.
  189.   OptionalFileEntryRef ASTFile;
  190.  
  191.   /// The top-level headers associated with this module.
  192.   llvm::SmallSetVector<const FileEntry *, 2> TopHeaders;
  193.  
  194.   /// top-level header filenames that aren't resolved to FileEntries yet.
  195.   std::vector<std::string> TopHeaderNames;
  196.  
  197.   /// Cache of modules visible to lookup in this module.
  198.   mutable llvm::DenseSet<const Module*> VisibleModulesCache;
  199.  
  200.   /// The ID used when referencing this module within a VisibleModuleSet.
  201.   unsigned VisibilityID;
  202.  
  203. public:
  204.   enum HeaderKind {
  205.     HK_Normal,
  206.     HK_Textual,
  207.     HK_Private,
  208.     HK_PrivateTextual,
  209.     HK_Excluded
  210.   };
  211.   static const int NumHeaderKinds = HK_Excluded + 1;
  212.  
  213.   /// Information about a header directive as found in the module map
  214.   /// file.
  215.   struct Header {
  216.     std::string NameAsWritten;
  217.     std::string PathRelativeToRootModuleDirectory;
  218.     OptionalFileEntryRefDegradesToFileEntryPtr Entry;
  219.  
  220.     explicit operator bool() { return Entry.has_value(); }
  221.   };
  222.  
  223.   /// Information about a directory name as found in the module map
  224.   /// file.
  225.   struct DirectoryName {
  226.     std::string NameAsWritten;
  227.     std::string PathRelativeToRootModuleDirectory;
  228.     const DirectoryEntry *Entry;
  229.  
  230.     explicit operator bool() { return Entry; }
  231.   };
  232.  
  233.   /// The headers that are part of this module.
  234.   SmallVector<Header, 2> Headers[5];
  235.  
  236.   /// Stored information about a header directive that was found in the
  237.   /// module map file but has not been resolved to a file.
  238.   struct UnresolvedHeaderDirective {
  239.     HeaderKind Kind = HK_Normal;
  240.     SourceLocation FileNameLoc;
  241.     std::string FileName;
  242.     bool IsUmbrella = false;
  243.     bool HasBuiltinHeader = false;
  244.     std::optional<off_t> Size;
  245.     std::optional<time_t> ModTime;
  246.   };
  247.  
  248.   /// Headers that are mentioned in the module map file but that we have not
  249.   /// yet attempted to resolve to a file on the file system.
  250.   SmallVector<UnresolvedHeaderDirective, 1> UnresolvedHeaders;
  251.  
  252.   /// Headers that are mentioned in the module map file but could not be
  253.   /// found on the file system.
  254.   SmallVector<UnresolvedHeaderDirective, 1> MissingHeaders;
  255.  
  256.   /// An individual requirement: a feature name and a flag indicating
  257.   /// the required state of that feature.
  258.   using Requirement = std::pair<std::string, bool>;
  259.  
  260.   /// The set of language features required to use this module.
  261.   ///
  262.   /// If any of these requirements are not available, the \c IsAvailable bit
  263.   /// will be false to indicate that this (sub)module is not available.
  264.   SmallVector<Requirement, 2> Requirements;
  265.  
  266.   /// A module with the same name that shadows this module.
  267.   Module *ShadowingModule = nullptr;
  268.  
  269.   /// Whether this module has declared itself unimportable, either because
  270.   /// it's missing a requirement from \p Requirements or because it's been
  271.   /// shadowed by another module.
  272.   unsigned IsUnimportable : 1;
  273.  
  274.   /// Whether we tried and failed to load a module file for this module.
  275.   unsigned HasIncompatibleModuleFile : 1;
  276.  
  277.   /// Whether this module is available in the current translation unit.
  278.   ///
  279.   /// If the module is missing headers or does not meet all requirements then
  280.   /// this bit will be 0.
  281.   unsigned IsAvailable : 1;
  282.  
  283.   /// Whether this module was loaded from a module file.
  284.   unsigned IsFromModuleFile : 1;
  285.  
  286.   /// Whether this is a framework module.
  287.   unsigned IsFramework : 1;
  288.  
  289.   /// Whether this is an explicit submodule.
  290.   unsigned IsExplicit : 1;
  291.  
  292.   /// Whether this is a "system" module (which assumes that all
  293.   /// headers in it are system headers).
  294.   unsigned IsSystem : 1;
  295.  
  296.   /// Whether this is an 'extern "C"' module (which implicitly puts all
  297.   /// headers in it within an 'extern "C"' block, and allows the module to be
  298.   /// imported within such a block).
  299.   unsigned IsExternC : 1;
  300.  
  301.   /// Whether this is an inferred submodule (module * { ... }).
  302.   unsigned IsInferred : 1;
  303.  
  304.   /// Whether we should infer submodules for this module based on
  305.   /// the headers.
  306.   ///
  307.   /// Submodules can only be inferred for modules with an umbrella header.
  308.   unsigned InferSubmodules : 1;
  309.  
  310.   /// Whether, when inferring submodules, the inferred submodules
  311.   /// should be explicit.
  312.   unsigned InferExplicitSubmodules : 1;
  313.  
  314.   /// Whether, when inferring submodules, the inferr submodules should
  315.   /// export all modules they import (e.g., the equivalent of "export *").
  316.   unsigned InferExportWildcard : 1;
  317.  
  318.   /// Whether the set of configuration macros is exhaustive.
  319.   ///
  320.   /// When the set of configuration macros is exhaustive, meaning
  321.   /// that no identifier not in this list should affect how the module is
  322.   /// built.
  323.   unsigned ConfigMacrosExhaustive : 1;
  324.  
  325.   /// Whether files in this module can only include non-modular headers
  326.   /// and headers from used modules.
  327.   unsigned NoUndeclaredIncludes : 1;
  328.  
  329.   /// Whether this module came from a "private" module map, found next
  330.   /// to a regular (public) module map.
  331.   unsigned ModuleMapIsPrivate : 1;
  332.  
  333.   /// Describes the visibility of the various names within a
  334.   /// particular module.
  335.   enum NameVisibilityKind {
  336.     /// All of the names in this module are hidden.
  337.     Hidden,
  338.     /// All of the names in this module are visible.
  339.     AllVisible
  340.   };
  341.  
  342.   /// The visibility of names within this particular module.
  343.   NameVisibilityKind NameVisibility;
  344.  
  345.   /// The location of the inferred submodule.
  346.   SourceLocation InferredSubmoduleLoc;
  347.  
  348.   /// The set of modules imported by this module, and on which this
  349.   /// module depends.
  350.   llvm::SmallSetVector<Module *, 2> Imports;
  351.  
  352.   /// The set of top-level modules that affected the compilation of this module,
  353.   /// but were not imported.
  354.   llvm::SmallSetVector<Module *, 2> AffectingClangModules;
  355.  
  356.   /// Describes an exported module.
  357.   ///
  358.   /// The pointer is the module being re-exported, while the bit will be true
  359.   /// to indicate that this is a wildcard export.
  360.   using ExportDecl = llvm::PointerIntPair<Module *, 1, bool>;
  361.  
  362.   /// The set of export declarations.
  363.   SmallVector<ExportDecl, 2> Exports;
  364.  
  365.   /// Describes an exported module that has not yet been resolved
  366.   /// (perhaps because the module it refers to has not yet been loaded).
  367.   struct UnresolvedExportDecl {
  368.     /// The location of the 'export' keyword in the module map file.
  369.     SourceLocation ExportLoc;
  370.  
  371.     /// The name of the module.
  372.     ModuleId Id;
  373.  
  374.     /// Whether this export declaration ends in a wildcard, indicating
  375.     /// that all of its submodules should be exported (rather than the named
  376.     /// module itself).
  377.     bool Wildcard;
  378.   };
  379.  
  380.   /// The set of export declarations that have yet to be resolved.
  381.   SmallVector<UnresolvedExportDecl, 2> UnresolvedExports;
  382.  
  383.   /// The directly used modules.
  384.   SmallVector<Module *, 2> DirectUses;
  385.  
  386.   /// The set of use declarations that have yet to be resolved.
  387.   SmallVector<ModuleId, 2> UnresolvedDirectUses;
  388.  
  389.   /// When \c NoUndeclaredIncludes is true, the set of modules this module tried
  390.   /// to import but didn't because they are not direct uses.
  391.   llvm::SmallSetVector<const Module *, 2> UndeclaredUses;
  392.  
  393.   /// A library or framework to link against when an entity from this
  394.   /// module is used.
  395.   struct LinkLibrary {
  396.     LinkLibrary() = default;
  397.     LinkLibrary(const std::string &Library, bool IsFramework)
  398.         : Library(Library), IsFramework(IsFramework) {}
  399.  
  400.     /// The library to link against.
  401.     ///
  402.     /// This will typically be a library or framework name, but can also
  403.     /// be an absolute path to the library or framework.
  404.     std::string Library;
  405.  
  406.     /// Whether this is a framework rather than a library.
  407.     bool IsFramework = false;
  408.   };
  409.  
  410.   /// The set of libraries or frameworks to link against when
  411.   /// an entity from this module is used.
  412.   llvm::SmallVector<LinkLibrary, 2> LinkLibraries;
  413.  
  414.   /// Autolinking uses the framework name for linking purposes
  415.   /// when this is false and the export_as name otherwise.
  416.   bool UseExportAsModuleLinkName = false;
  417.  
  418.   /// The set of "configuration macros", which are macros that
  419.   /// (intentionally) change how this module is built.
  420.   std::vector<std::string> ConfigMacros;
  421.  
  422.   /// An unresolved conflict with another module.
  423.   struct UnresolvedConflict {
  424.     /// The (unresolved) module id.
  425.     ModuleId Id;
  426.  
  427.     /// The message provided to the user when there is a conflict.
  428.     std::string Message;
  429.   };
  430.  
  431.   /// The list of conflicts for which the module-id has not yet been
  432.   /// resolved.
  433.   std::vector<UnresolvedConflict> UnresolvedConflicts;
  434.  
  435.   /// A conflict between two modules.
  436.   struct Conflict {
  437.     /// The module that this module conflicts with.
  438.     Module *Other;
  439.  
  440.     /// The message provided to the user when there is a conflict.
  441.     std::string Message;
  442.   };
  443.  
  444.   /// The list of conflicts.
  445.   std::vector<Conflict> Conflicts;
  446.  
  447.   /// Construct a new module or submodule.
  448.   Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent,
  449.          bool IsFramework, bool IsExplicit, unsigned VisibilityID);
  450.  
  451.   ~Module();
  452.  
  453.   /// Determine whether this module has been declared unimportable.
  454.   bool isUnimportable() const { return IsUnimportable; }
  455.  
  456.   /// Determine whether this module has been declared unimportable.
  457.   ///
  458.   /// \param LangOpts The language options used for the current
  459.   /// translation unit.
  460.   ///
  461.   /// \param Target The target options used for the current translation unit.
  462.   ///
  463.   /// \param Req If this module is unimportable because of a missing
  464.   /// requirement, this parameter will be set to one of the requirements that
  465.   /// is not met for use of this module.
  466.   ///
  467.   /// \param ShadowingModule If this module is unimportable because it is
  468.   /// shadowed, this parameter will be set to the shadowing module.
  469.   bool isUnimportable(const LangOptions &LangOpts, const TargetInfo &Target,
  470.                       Requirement &Req, Module *&ShadowingModule) const;
  471.  
  472.   /// Determine whether this module can be built in this compilation.
  473.   bool isForBuilding(const LangOptions &LangOpts) const;
  474.  
  475.   /// Determine whether this module is available for use within the
  476.   /// current translation unit.
  477.   bool isAvailable() const { return IsAvailable; }
  478.  
  479.   /// Determine whether this module is available for use within the
  480.   /// current translation unit.
  481.   ///
  482.   /// \param LangOpts The language options used for the current
  483.   /// translation unit.
  484.   ///
  485.   /// \param Target The target options used for the current translation unit.
  486.   ///
  487.   /// \param Req If this module is unavailable because of a missing requirement,
  488.   /// this parameter will be set to one of the requirements that is not met for
  489.   /// use of this module.
  490.   ///
  491.   /// \param MissingHeader If this module is unavailable because of a missing
  492.   /// header, this parameter will be set to one of the missing headers.
  493.   ///
  494.   /// \param ShadowingModule If this module is unavailable because it is
  495.   /// shadowed, this parameter will be set to the shadowing module.
  496.   bool isAvailable(const LangOptions &LangOpts,
  497.                    const TargetInfo &Target,
  498.                    Requirement &Req,
  499.                    UnresolvedHeaderDirective &MissingHeader,
  500.                    Module *&ShadowingModule) const;
  501.  
  502.   /// Determine whether this module is a submodule.
  503.   bool isSubModule() const { return Parent != nullptr; }
  504.  
  505.   /// Check if this module is a (possibly transitive) submodule of \p Other.
  506.   ///
  507.   /// The 'A is a submodule of B' relation is a partial order based on the
  508.   /// the parent-child relationship between individual modules.
  509.   ///
  510.   /// Returns \c false if \p Other is \c nullptr.
  511.   bool isSubModuleOf(const Module *Other) const;
  512.  
  513.   /// Determine whether this module is a part of a framework,
  514.   /// either because it is a framework module or because it is a submodule
  515.   /// of a framework module.
  516.   bool isPartOfFramework() const {
  517.     for (const Module *Mod = this; Mod; Mod = Mod->Parent)
  518.       if (Mod->IsFramework)
  519.         return true;
  520.  
  521.     return false;
  522.   }
  523.  
  524.   /// Determine whether this module is a subframework of another
  525.   /// framework.
  526.   bool isSubFramework() const {
  527.     return IsFramework && Parent && Parent->isPartOfFramework();
  528.   }
  529.  
  530.   /// Set the parent of this module. This should only be used if the parent
  531.   /// could not be set during module creation.
  532.   void setParent(Module *M) {
  533.     assert(!Parent);
  534.     Parent = M;
  535.     Parent->SubModuleIndex[Name] = Parent->SubModules.size();
  536.     Parent->SubModules.push_back(this);
  537.   }
  538.  
  539.   /// Is this module have similar semantics as headers.
  540.   bool isHeaderLikeModule() const {
  541.     return isModuleMapModule() || isHeaderUnit();
  542.   }
  543.  
  544.   /// Is this a module partition.
  545.   bool isModulePartition() const {
  546.     return Kind == ModulePartitionInterface ||
  547.            Kind == ModulePartitionImplementation;
  548.   }
  549.  
  550.   /// Is this module a header unit.
  551.   bool isHeaderUnit() const { return Kind == ModuleHeaderUnit; }
  552.   // Is this a C++20 module interface or a partition.
  553.   bool isInterfaceOrPartition() const {
  554.     return Kind == ModuleInterfaceUnit || isModulePartition();
  555.   }
  556.  
  557.   bool isModuleInterfaceUnit() const {
  558.     return Kind == ModuleInterfaceUnit || Kind == ModulePartitionInterface;
  559.   }
  560.  
  561.   /// Get the primary module interface name from a partition.
  562.   StringRef getPrimaryModuleInterfaceName() const {
  563.     // Technically, global module fragment belongs to global module. And global
  564.     // module has no name: [module.unit]p6:
  565.     //   The global module has no name, no module interface unit, and is not
  566.     //   introduced by any module-declaration.
  567.     //
  568.     // <global> is the default name showed in module map.
  569.     if (isGlobalModule())
  570.       return "<global>";
  571.  
  572.     if (isModulePartition()) {
  573.       auto pos = Name.find(':');
  574.       return StringRef(Name.data(), pos);
  575.     }
  576.  
  577.     if (isPrivateModule())
  578.       return getTopLevelModuleName();
  579.  
  580.     return Name;
  581.   }
  582.  
  583.   /// Retrieve the full name of this module, including the path from
  584.   /// its top-level module.
  585.   /// \param AllowStringLiterals If \c true, components that might not be
  586.   ///        lexically valid as identifiers will be emitted as string literals.
  587.   std::string getFullModuleName(bool AllowStringLiterals = false) const;
  588.  
  589.   /// Whether the full name of this module is equal to joining
  590.   /// \p nameParts with "."s.
  591.   ///
  592.   /// This is more efficient than getFullModuleName().
  593.   bool fullModuleNameIs(ArrayRef<StringRef> nameParts) const;
  594.  
  595.   /// Retrieve the top-level module for this (sub)module, which may
  596.   /// be this module.
  597.   Module *getTopLevelModule() {
  598.     return const_cast<Module *>(
  599.              const_cast<const Module *>(this)->getTopLevelModule());
  600.   }
  601.  
  602.   /// Retrieve the top-level module for this (sub)module, which may
  603.   /// be this module.
  604.   const Module *getTopLevelModule() const;
  605.  
  606.   /// Retrieve the name of the top-level module.
  607.   StringRef getTopLevelModuleName() const {
  608.     return getTopLevelModule()->Name;
  609.   }
  610.  
  611.   /// The serialized AST file for this module, if one was created.
  612.   OptionalFileEntryRefDegradesToFileEntryPtr getASTFile() const {
  613.     return getTopLevelModule()->ASTFile;
  614.   }
  615.  
  616.   /// Set the serialized AST file for the top-level module of this module.
  617.   void setASTFile(OptionalFileEntryRef File) {
  618.     assert((!getASTFile() || getASTFile() == File) && "file path changed");
  619.     getTopLevelModule()->ASTFile = File;
  620.   }
  621.  
  622.   /// Retrieve the directory for which this module serves as the
  623.   /// umbrella.
  624.   DirectoryName getUmbrellaDir() const;
  625.  
  626.   /// Retrieve the header that serves as the umbrella header for this
  627.   /// module.
  628.   Header getUmbrellaHeader() const {
  629.     if (auto *ME = Umbrella.dyn_cast<const FileEntryRef::MapEntry *>())
  630.       return Header{UmbrellaAsWritten, UmbrellaRelativeToRootModuleDirectory,
  631.                     FileEntryRef(*ME)};
  632.     return Header{};
  633.   }
  634.  
  635.   /// Determine whether this module has an umbrella directory that is
  636.   /// not based on an umbrella header.
  637.   bool hasUmbrellaDir() const {
  638.     return Umbrella && Umbrella.is<const DirectoryEntry *>();
  639.   }
  640.  
  641.   /// Add a top-level header associated with this module.
  642.   void addTopHeader(const FileEntry *File);
  643.  
  644.   /// Add a top-level header filename associated with this module.
  645.   void addTopHeaderFilename(StringRef Filename) {
  646.     TopHeaderNames.push_back(std::string(Filename));
  647.   }
  648.  
  649.   /// The top-level headers associated with this module.
  650.   ArrayRef<const FileEntry *> getTopHeaders(FileManager &FileMgr);
  651.  
  652.   /// Determine whether this module has declared its intention to
  653.   /// directly use another module.
  654.   bool directlyUses(const Module *Requested);
  655.  
  656.   /// Add the given feature requirement to the list of features
  657.   /// required by this module.
  658.   ///
  659.   /// \param Feature The feature that is required by this module (and
  660.   /// its submodules).
  661.   ///
  662.   /// \param RequiredState The required state of this feature: \c true
  663.   /// if it must be present, \c false if it must be absent.
  664.   ///
  665.   /// \param LangOpts The set of language options that will be used to
  666.   /// evaluate the availability of this feature.
  667.   ///
  668.   /// \param Target The target options that will be used to evaluate the
  669.   /// availability of this feature.
  670.   void addRequirement(StringRef Feature, bool RequiredState,
  671.                       const LangOptions &LangOpts,
  672.                       const TargetInfo &Target);
  673.  
  674.   /// Mark this module and all of its submodules as unavailable.
  675.   void markUnavailable(bool Unimportable);
  676.  
  677.   /// Find the submodule with the given name.
  678.   ///
  679.   /// \returns The submodule if found, or NULL otherwise.
  680.   Module *findSubmodule(StringRef Name) const;
  681.   Module *findOrInferSubmodule(StringRef Name);
  682.  
  683.   /// Get the Global Module Fragment (sub-module) for this module, it there is
  684.   /// one.
  685.   ///
  686.   /// \returns The GMF sub-module if found, or NULL otherwise.
  687.   Module *getGlobalModuleFragment() { return findSubmodule("<global>"); }
  688.  
  689.   /// Get the Private Module Fragment (sub-module) for this module, it there is
  690.   /// one.
  691.   ///
  692.   /// \returns The PMF sub-module if found, or NULL otherwise.
  693.   Module *getPrivateModuleFragment() { return findSubmodule("<private>"); }
  694.  
  695.   /// Determine whether the specified module would be visible to
  696.   /// a lookup at the end of this module.
  697.   ///
  698.   /// FIXME: This may return incorrect results for (submodules of) the
  699.   /// module currently being built, if it's queried before we see all
  700.   /// of its imports.
  701.   bool isModuleVisible(const Module *M) const {
  702.     if (VisibleModulesCache.empty())
  703.       buildVisibleModulesCache();
  704.     return VisibleModulesCache.count(M);
  705.   }
  706.  
  707.   unsigned getVisibilityID() const { return VisibilityID; }
  708.  
  709.   using submodule_iterator = std::vector<Module *>::iterator;
  710.   using submodule_const_iterator = std::vector<Module *>::const_iterator;
  711.  
  712.   submodule_iterator submodule_begin() { return SubModules.begin(); }
  713.   submodule_const_iterator submodule_begin() const {return SubModules.begin();}
  714.   submodule_iterator submodule_end()   { return SubModules.end(); }
  715.   submodule_const_iterator submodule_end() const { return SubModules.end(); }
  716.  
  717.   llvm::iterator_range<submodule_iterator> submodules() {
  718.     return llvm::make_range(submodule_begin(), submodule_end());
  719.   }
  720.   llvm::iterator_range<submodule_const_iterator> submodules() const {
  721.     return llvm::make_range(submodule_begin(), submodule_end());
  722.   }
  723.  
  724.   /// Appends this module's list of exported modules to \p Exported.
  725.   ///
  726.   /// This provides a subset of immediately imported modules (the ones that are
  727.   /// directly exported), not the complete set of exported modules.
  728.   void getExportedModules(SmallVectorImpl<Module *> &Exported) const;
  729.  
  730.   static StringRef getModuleInputBufferName() {
  731.     return "<module-includes>";
  732.   }
  733.  
  734.   /// Print the module map for this module to the given stream.
  735.   void print(raw_ostream &OS, unsigned Indent = 0, bool Dump = false) const;
  736.  
  737.   /// Dump the contents of this module to the given output stream.
  738.   void dump() const;
  739.  
  740. private:
  741.   void buildVisibleModulesCache() const;
  742. };
  743.  
  744. /// A set of visible modules.
  745. class VisibleModuleSet {
  746. public:
  747.   VisibleModuleSet() = default;
  748.   VisibleModuleSet(VisibleModuleSet &&O)
  749.       : ImportLocs(std::move(O.ImportLocs)), Generation(O.Generation ? 1 : 0) {
  750.     O.ImportLocs.clear();
  751.     ++O.Generation;
  752.   }
  753.  
  754.   /// Move from another visible modules set. Guaranteed to leave the source
  755.   /// empty and bump the generation on both.
  756.   VisibleModuleSet &operator=(VisibleModuleSet &&O) {
  757.     ImportLocs = std::move(O.ImportLocs);
  758.     O.ImportLocs.clear();
  759.     ++O.Generation;
  760.     ++Generation;
  761.     return *this;
  762.   }
  763.  
  764.   /// Get the current visibility generation. Incremented each time the
  765.   /// set of visible modules changes in any way.
  766.   unsigned getGeneration() const { return Generation; }
  767.  
  768.   /// Determine whether a module is visible.
  769.   bool isVisible(const Module *M) const {
  770.     return getImportLoc(M).isValid();
  771.   }
  772.  
  773.   /// Get the location at which the import of a module was triggered.
  774.   SourceLocation getImportLoc(const Module *M) const {
  775.     return M->getVisibilityID() < ImportLocs.size()
  776.                ? ImportLocs[M->getVisibilityID()]
  777.                : SourceLocation();
  778.   }
  779.  
  780.   /// A callback to call when a module is made visible (directly or
  781.   /// indirectly) by a call to \ref setVisible.
  782.   using VisibleCallback = llvm::function_ref<void(Module *M)>;
  783.  
  784.   /// A callback to call when a module conflict is found. \p Path
  785.   /// consists of a sequence of modules from the conflicting module to the one
  786.   /// made visible, where each was exported by the next.
  787.   using ConflictCallback =
  788.       llvm::function_ref<void(ArrayRef<Module *> Path, Module *Conflict,
  789.                          StringRef Message)>;
  790.  
  791.   /// Make a specific module visible.
  792.   void setVisible(Module *M, SourceLocation Loc,
  793.                   VisibleCallback Vis = [](Module *) {},
  794.                   ConflictCallback Cb = [](ArrayRef<Module *>, Module *,
  795.                                            StringRef) {});
  796.  
  797. private:
  798.   /// Import locations for each visible module. Indexed by the module's
  799.   /// VisibilityID.
  800.   std::vector<SourceLocation> ImportLocs;
  801.  
  802.   /// Visibility generation, bumped every time the visibility state changes.
  803.   unsigned Generation = 0;
  804. };
  805.  
  806. /// Abstracts clang modules and precompiled header files and holds
  807. /// everything needed to generate debug info for an imported module
  808. /// or PCH.
  809. class ASTSourceDescriptor {
  810.   StringRef PCHModuleName;
  811.   StringRef Path;
  812.   StringRef ASTFile;
  813.   ASTFileSignature Signature;
  814.   Module *ClangModule = nullptr;
  815.  
  816. public:
  817.   ASTSourceDescriptor() = default;
  818.   ASTSourceDescriptor(StringRef Name, StringRef Path, StringRef ASTFile,
  819.                       ASTFileSignature Signature)
  820.       : PCHModuleName(std::move(Name)), Path(std::move(Path)),
  821.         ASTFile(std::move(ASTFile)), Signature(Signature) {}
  822.   ASTSourceDescriptor(Module &M);
  823.  
  824.   std::string getModuleName() const;
  825.   StringRef getPath() const { return Path; }
  826.   StringRef getASTFile() const { return ASTFile; }
  827.   ASTFileSignature getSignature() const { return Signature; }
  828.   Module *getModuleOrNull() const { return ClangModule; }
  829. };
  830.  
  831.  
  832. } // namespace clang
  833.  
  834. #endif // LLVM_CLANG_BASIC_MODULE_H
  835.