Requestify implicit imports

include/swift/AST/ASTTypeIDZone.def

@@ -19,6 +19,7 @@ SWIFT_TYPEID(AncestryFlags)
 SWIFT_TYPEID(CtorInitializerKind)
 SWIFT_TYPEID(FunctionBuilderBodyPreCheck)
 SWIFT_TYPEID(GenericSignature)
+SWIFT_TYPEID(ImplicitImport)
 SWIFT_TYPEID(ImplicitMemberAction)
 SWIFT_TYPEID(ParamSpecifier)
 SWIFT_TYPEID(PropertyWrapperBackingPropertyInfo)

include/swift/AST/ASTTypeIDs.h

@@ -36,6 +36,7 @@ class GenericTypeParamType;
 class InfixOperatorDecl;
 class IterableDeclContext;
 class ModuleDecl;
+struct ImplicitImport;
 class NamedPattern;
 class NominalTypeDecl;
 class OperatorDecl;

include/swift/AST/Decl.h

@@ -3032,6 +3032,10 @@ class TypeAliasDecl : public GenericTypeDecl {
   Type getUnderlyingType() const;
   void setUnderlyingType(Type type);
 
+  /// Returns the interface type of the underlying type if computed, null
+  /// otherwise. Should only be used for dumping.
+  Type getCachedUnderlyingType() const { return UnderlyingTy.getType(); }
+
   /// For generic typealiases, return the unbound generic type.
   UnboundGenericType *getUnboundGenericType() const;
 

include/swift/AST/DiagnosticsCommon.def

@@ -90,6 +90,10 @@ ERROR(attr_only_on_parameters, none,
 ERROR(function_type_no_parens,none,
       "single argument function types require parentheses", ())
 
+// Used by both the Frontend and Sema.
+ERROR(error_underlying_module_not_found,none,
+      "underlying Objective-C module %0 not found", (Identifier))
+
 // Used by -verify-generic-signatures
 ERROR(generic_signature_not_minimal,none,
       "generic requirement '%0' is redundant in %1", (StringRef, StringRef))

include/swift/AST/DiagnosticsFrontend.def

@@ -138,8 +138,6 @@ ERROR(error_stdlib_module_name,none,
 
 ERROR(error_stdlib_not_found,Fatal,
       "unable to load standard library for target '%0'", (StringRef))
-ERROR(error_underlying_module_not_found,none,
-      "underlying Objective-C module %0 not found", (Identifier))
 
 ERROR(error_unable_to_load_supplementary_output_file_map, none,
       "unable to load supplementary output file map '%0': %1",

include/swift/AST/Module.h

@@ -59,6 +59,7 @@ namespace swift {
   class FuncDecl;
   class InfixOperatorDecl;
   class LinkLibrary;
+  struct ImplicitImport;
   class ModuleLoader;
   class NominalTypeDecl;
   class EnumElementDecl;
@@ -158,6 +159,42 @@ enum class ResilienceStrategy : unsigned {
   Resilient
 };
 
+/// The kind of stdlib that should be imported.
+enum class ImplicitStdlibKind {
+  /// No standard library should be implicitly imported.
+  None,
+
+  /// The Builtin module should be implicitly imported.
+  Builtin,
+
+  /// The regular Swift standard library should be implicitly imported.
+  Stdlib
+};
+
+struct ImplicitImportInfo {
+  /// The implicit stdlib to import.
+  ImplicitStdlibKind StdlibKind;
+
+  /// Whether we should attempt to import an underlying Clang half of this
+  /// module.
+  bool ShouldImportUnderlyingModule;
+
+  /// The bridging header path for this module, empty if there is none.
+  StringRef BridgingHeaderPath;
+
+  /// The names of additional modules to be implicitly imported.
+  SmallVector<Identifier, 4> ModuleNames;
+
+  /// An additional list of already-loaded modules which should be implicitly
+  /// imported.
+  SmallVector<std::pair<ModuleDecl *, /*exported*/ bool>, 4>
+      AdditionalModules;
+
+  ImplicitImportInfo()
+      : StdlibKind(ImplicitStdlibKind::None),
+        ShouldImportUnderlyingModule(false) {}
+};
+
 class OverlayFile;
 
 /// The minimum unit of compilation.
@@ -245,6 +282,10 @@ class ModuleDecl : public DeclContext, public TypeDecl {
   llvm::SmallDenseMap<Identifier, SmallVector<OverlayFile *, 1>>
     declaredCrossImports;
 
+  /// A description of what should be implicitly imported by each file of this
+  /// module.
+  const ImplicitImportInfo ImportInfo;
+
   std::unique_ptr<SourceLookupCache> Cache;
   SourceLookupCache &getSourceLookupCache() const;
 
@@ -274,15 +315,29 @@ class ModuleDecl : public DeclContext, public TypeDecl {
   /// \see EntryPointInfoTy
   EntryPointInfoTy EntryPointInfo;
 
-  ModuleDecl(Identifier name, ASTContext &ctx);
+  ModuleDecl(Identifier name, ASTContext &ctx, ImplicitImportInfo importInfo);
 
 public:
-  static ModuleDecl *create(Identifier name, ASTContext &ctx) {
-    return new (ctx) ModuleDecl(name, ctx);
+  /// Creates a new module with a given \p name.
+  ///
+  /// \param importInfo Information about which modules should be implicitly
+  /// imported by each file of this module.
+  static ModuleDecl *
+  create(Identifier name, ASTContext &ctx,
+         ImplicitImportInfo importInfo = ImplicitImportInfo()) {
+    return new (ctx) ModuleDecl(name, ctx, importInfo);
   }
 
   using Decl::getASTContext;
 
+  /// Retrieves information about which modules are implicitly imported by
+  /// each file of this module.
+  const ImplicitImportInfo &getImplicitImportInfo() const { return ImportInfo; }
+
+  /// Retrieve a list of modules that each file of this module implicitly
+  /// imports.
+  ArrayRef<ImplicitImport> getImplicitImports() const;
+
   ArrayRef<FileUnit *> getFiles() {
     return Files;
   }

include/swift/AST/SourceFile.h

@@ -33,13 +33,6 @@ class SourceFile final : public FileUnit {
   class Impl;
   struct SourceFileSyntaxInfo;
 
-  /// The implicit module import that the SourceFile should get.
-  enum class ImplicitModuleImportKind {
-    None,
-    Builtin,
-    Stdlib
-  };
-
   /// Possible attributes for imports in source files.
   enum class ImportFlags {
     /// The imported module is exposed to anyone who imports the parent module.
@@ -128,8 +121,8 @@ class SourceFile final : public FileUnit {
 
   /// This is the list of modules that are imported by this module.
   ///
-  /// This is filled in by the import resolution phase.
-  ArrayRef<ImportedModuleDesc> Imports;
+  /// This is \c None until it is filled in by the import resolution phase.
+  Optional<ArrayRef<ImportedModuleDesc>> Imports;
 
   /// A unique identifier representing this file; used to mark private decls
   /// within the file to keep them from conflicting with other files in the
@@ -335,12 +328,14 @@ class SourceFile final : public FileUnit {
   llvm::StringMap<SourceFilePathInfo> getInfoForUsedFilePaths() const;
 
   SourceFile(ModuleDecl &M, SourceFileKind K, Optional<unsigned> bufferID,
-             ImplicitModuleImportKind ModImpKind, bool KeepParsedTokens = false,
-             bool KeepSyntaxTree = false, ParsingOptions parsingOpts = {});
+             bool KeepParsedTokens = false, bool KeepSyntaxTree = false,
+             ParsingOptions parsingOpts = {});
 
   ~SourceFile();
 
-  void addImports(ArrayRef<ImportedModuleDesc> IM);
+  /// Set the imports for this source file. This gets called by import
+  /// resolution.
+  void setImports(ArrayRef<ImportedModuleDesc> imports);
 
   enum ImportQueryKind {
     /// Return the results for testable or private imports.

include/swift/AST/TypeCheckRequests.h

@@ -23,6 +23,7 @@
 #include "swift/AST/Evaluator.h"
 #include "swift/AST/Pattern.h"
 #include "swift/AST/SimpleRequest.h"
+#include "swift/AST/SourceFile.h"
 #include "swift/AST/TypeResolutionStage.h"
 #include "swift/Basic/AnyValue.h"
 #include "swift/Basic/Statistic.h"
@@ -2344,6 +2345,45 @@ class SimpleDidSetRequest
   }
 };
 
+/// A module which has been implicitly imported.
+struct ImplicitImport {
+  using ImportOptions = SourceFile::ImportOptions;
+
+  ModuleDecl *Module;
+  ImportOptions Options;
+
+  ImplicitImport(ModuleDecl *module, ImportOptions opts = {})
+      : Module(module), Options(opts) {}
+
+  friend bool operator==(const ImplicitImport &lhs,
+                         const ImplicitImport &rhs) {
+    return lhs.Module == rhs.Module &&
+           lhs.Options.toRaw() == rhs.Options.toRaw();
+  }
+};
+
+void simple_display(llvm::raw_ostream &out, const ImplicitImport &import);
+
+/// Computes the loaded modules that should be implicitly imported by each file
+/// of a given module.
+class ModuleImplicitImportsRequest
+    : public SimpleRequest<ModuleImplicitImportsRequest,
+                           ArrayRef<ImplicitImport>(ModuleDecl *),
+                           RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  ArrayRef<ImplicitImport>
+  evaluate(Evaluator &evaluator, ModuleDecl *module) const;
+
+public:
+  // Cached.
+  bool isCached() const { return true; }
+};
+
 // Allow AnyValue to compare two Type values, even though Type doesn't
 // support ==.
 template<>

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -128,6 +128,8 @@ SWIFT_REQUEST(TypeChecker, ValidatePrecedenceGroupRequest,
               Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, MangleLocalTypeDeclRequest,
               std::string(const TypeDecl *), Cached, NoLocationInfo)
+SWIFT_REQUEST(TypeChecker, ModuleImplicitImportsRequest,
+              ArrayRef<ImplicitImport>(ModuleDecl *), Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, NamingPatternRequest,
               NamedPattern *(VarDecl *), SeparatelyCached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, OpaqueReadOwnershipRequest,

include/swift/Frontend/Frontend.h

@@ -335,14 +335,15 @@ class CompilerInvocation {
   /// in generating a cached PCH file for the bridging header.
   std::string getPCHHash() const;
 
-  SourceFile::ImplicitModuleImportKind getImplicitModuleImportKind() const {
+  /// Retrieve the stdlib kind to implicitly import.
+  ImplicitStdlibKind getImplicitStdlibKind() const {
     if (getInputKind() == InputFileKind::SIL) {
-      return SourceFile::ImplicitModuleImportKind::None;
+      return ImplicitStdlibKind::None;
     }
     if (getParseStdlib()) {
-      return SourceFile::ImplicitModuleImportKind::Builtin;
+      return ImplicitStdlibKind::Builtin;
     }
-    return SourceFile::ImplicitModuleImportKind::Stdlib;
+    return ImplicitStdlibKind::Stdlib;
   }
 
   /// Performs input setup common to these tools:
@@ -654,7 +655,6 @@ class CompilerInstance {
 private:
   SourceFile *
   createSourceFileForMainModule(SourceFileKind FileKind,
-                                SourceFile::ImplicitModuleImportKind ImportKind,
                                 Optional<unsigned> BufferID,
                                 SourceFile::ParsingOptions options = {});
 
@@ -667,38 +667,17 @@ class CompilerInstance {
 private:
   /// Load stdlib & return true if should continue, i.e. no error
   bool loadStdlib();
-  ModuleDecl *importUnderlyingModule();
-  ModuleDecl *importBridgingHeader();
 
-  void
-  getImplicitlyImportedModules(SmallVectorImpl<ModuleDecl *> &importModules);
-
-public: // for static functions in Frontend.cpp
-  struct ImplicitImports {
-    SourceFile::ImplicitModuleImportKind kind;
-    ModuleDecl *objCModuleUnderlyingMixedFramework;
-    ModuleDecl *headerModule;
-    SmallVector<ModuleDecl *, 4> modules;
-
-    explicit ImplicitImports(CompilerInstance &compiler);
-  };
-
-  static void addAdditionalInitialImportsTo(
-    SourceFile *SF, const ImplicitImports &implicitImports);
-
-private:
-  void addMainFileToModule(const ImplicitImports &implicitImports);
+  /// Retrieve a description of which modules should be implicitly imported.
+  ImplicitImportInfo getImplicitImportInfo() const;
 
   void performSemaUpTo(SourceFile::ASTStage_t LimitStage);
-  void parseAndCheckTypesUpTo(const ImplicitImports &implicitImports,
-                              SourceFile::ASTStage_t LimitStage);
+  void parseAndCheckTypesUpTo(SourceFile::ASTStage_t LimitStage);
 
-  void parseLibraryFile(unsigned BufferID,
-                        const ImplicitImports &implicitImports);
+  void parseLibraryFile(unsigned BufferID);
 
   /// Return true if had load error
-  bool
-  parsePartialModulesAndLibraryFiles(const ImplicitImports &implicitImports);
+  bool parsePartialModulesAndLibraryFiles();
 
   void forEachFileToTypeCheck(llvm::function_ref<void(SourceFile &)> fn);
 

include/swift/Frontend/FrontendOptions.h

@@ -33,6 +33,9 @@ namespace swift {
 class FrontendOptions {
   friend class ArgsToFrontendOptionsConverter;
 
+  /// A list of arbitrary modules to import and make implicitly visible.
+  std::vector<std::string> ImplicitImportModuleNames;
+
 public:
   FrontendInputsAndOutputs InputsAndOutputs;
 
@@ -44,9 +47,6 @@ class FrontendOptions {
 
   bool isOutputFileDirectory() const;
 
-  /// A list of arbitrary modules to import and make implicitly visible.
-  std::vector<std::string> ImplicitImportModuleNames;
-
   /// An Objective-C header to import and make implicitly visible.
   std::string ImplicitObjCHeaderPath;
 
@@ -322,6 +322,12 @@ class FrontendOptions {
   const PrimarySpecificPaths &
       getPrimarySpecificPathsForPrimary(StringRef) const;
 
+  /// Retrieves the list of arbitrary modules to import and make implicitly
+  /// visible.
+  ArrayRef<std::string> getImplicitImportModuleNames() const {
+    return ImplicitImportModuleNames;
+  }
+
 private:
   static bool canActionEmitDependencies(ActionType);
   static bool canActionEmitReferenceDependencies(ActionType);

lib/AST/ASTDumper.cpp

@@ -631,7 +631,7 @@ namespace {
     void visitTypeAliasDecl(TypeAliasDecl *TAD) {
       printCommon(TAD, "typealias");
       PrintWithColorRAII(OS, TypeColor) << " type='";
-      if (auto underlying = TAD->getUnderlyingType()) {
+      if (auto underlying = TAD->getCachedUnderlyingType()) {
         PrintWithColorRAII(OS, TypeColor)
           << underlying.getString();
       } else {