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//===- Module.h - Describe a module -----------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See 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.
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.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 <string>
#include <utility>
#include <vector>
namespace llvm {
class raw_ostream;
} // namespace llvm
namespace clang {
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<uint32_t, 5> {
ASTFileSignature(std::array<uint32_t, 5> S = {{0}})
: std::array<uint32_t, 5>(std::move(S)) {}
explicit operator bool() const {
return *this != std::array<uint32_t, 5>({{0}});
/// Describes a module or submodule.
class Module {
/// 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.
/// This is a C++ Modules TS module interface unit.
/// This is a fragment of the global module within some C++ module.
/// This is the private module fragment within some C++ module.
/// 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 DirectoryEntry *, const FileEntry *> Umbrella;
/// The module signature.
ASTFileSignature Signature;
/// The name of the umbrella entry, as written in the module map.
std::string UmbrellaAsWritten;
/// 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 named C++ module?
bool isModulePurview() const {
return Kind == ModuleInterfaceUnit || Kind == PrivateModuleFragment;
/// 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.
const FileEntry *ASTFile = nullptr;
/// 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;
enum HeaderKind {
static const int NumHeaderKinds = HK_Excluded + 1;
/// Information about a header directive as found in the module map
/// file.
struct Header {
std::string NameAsWritten;
const FileEntry *Entry;
explicit operator bool() { return Entry; }
/// Information about a directory name as found in the module map
/// file.
struct DirectoryName {
std::string NameAsWritten;
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;
Optional<off_t> Size;
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 is missing a feature from \c Requirements.
unsigned IsMissingRequirement : 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.
/// All of the names in this module are visible.
/// 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;
/// 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;
/// 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);
/// 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; }
/// Determine whether this module is a submodule of the given other
/// module.
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) {
Parent = M;
Parent->SubModuleIndex[Name] = Parent->SubModules.size();
/// 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.
const FileEntry *getASTFile() const {
return getTopLevelModule()->ASTFile;
/// Set the serialized AST file for the top-level module of this module.
void setASTFile(const FileEntry *File) {
assert((File == nullptr || getASTFile() == nullptr ||
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 *E = Umbrella.dyn_cast<const FileEntry *>())
return Header{UmbrellaAsWritten, E};
return Header{};
/// Determine whether this module has an umbrella directory that is
/// not based on an umbrella header.
bool hasUmbrellaDir() const {
return Umbrella &&<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) {
/// 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) const;
/// 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 MissingRequirement = false);
/// Find the submodule with the given name.
/// \returns The submodule if found, or NULL otherwise.
Module *findSubmodule(StringRef Name) const;
Module *findOrInferSubmodule(StringRef Name);
/// 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())
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) const;
/// Dump the contents of this module to the given output stream.
void dump() const;
void buildVisibleModulesCache() const;
/// A set of visible modules.
class VisibleModuleSet {
VisibleModuleSet() = default;
VisibleModuleSet(VisibleModuleSet &&O)
: ImportLocs(std::move(O.ImportLocs)), Generation(O.Generation ? 1 : 0) {
/// 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);
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) {});
/// 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;
} // namespace clang