Merge pull request swiftlang#63248 from xymus/swift-export-as

[ModuleInterface] Intro the flag `-export-as` for Swift modules

Author: xymus

include/swift/AST/DiagnosticsFrontend.def

@@ -180,6 +180,11 @@ ERROR(error_stdlib_module_name,none,
       "module name \"%0\" is reserved for the standard library"
       "%select{|; use -module-name flag to specify an alternate name}1",
       (StringRef, bool))
+
+ERROR(error_bad_export_as_name,none,
+      "export-as name \"%0\" is not a valid identifier",
+      (StringRef))
+
 ERROR(error_bad_package_name,none,
       "package name \"%0\" is not a valid identifier",
       (StringRef))

include/swift/AST/FileUnit.h

@@ -322,8 +322,11 @@ class FileUnit : public DeclContext, public ASTAllocated<FileUnit> {
   /// The 'real name' is the actual binary name of the module, which can be different from the 'name'
   /// if module aliasing was used (via -module-alias flag).
   ///
-  /// Usually this is the module real name itself, but certain Clang features allow
-  /// substituting another name instead.
+  /// This is usually the module real name which can be overriden by an
+  /// `export_as` definition of a clang module, or `-export-as` flag on an
+  /// imported Swift module. Swift modules built from source do not apply
+  /// their own `-export-as` flag, this way the swiftinterface can be
+  /// verified.
   virtual StringRef getExportedModuleName() const {
     return getParentModule()->getRealName().str();
   }

include/swift/AST/Module.h

@@ -175,6 +175,10 @@ class ModuleDecl
 
   /// The name of the package this module belongs to
   mutable Identifier PackageName;
+
+  /// Module name to use when referenced in clients module interfaces.
+  mutable Identifier ExportAsName;
+
 public:
   /// Produces the components of a given module's full name in reverse order.
   ///
@@ -410,6 +414,12 @@ class ModuleDecl
     PackageName = name;
   }
 
+  Identifier getExportAsName() const { return ExportAsName; }
+
+  void setExportAsName(Identifier name) {
+    ExportAsName = name;
+  }
+
   /// Retrieve the actual module name of an alias used for this module (if any).
   ///
   /// For example, if '-module-alias Foo=Bar' is passed in when building the main module,

include/swift/Frontend/FrontendOptions.h

@@ -67,6 +67,9 @@ class FrontendOptions {
   /// The name of the package this module belongs to.
   std::string PackageName;
 
+  /// Module name to use when referenced in clients module interfaces.
+  std::string ExportAsName;
+
   /// Arguments which should be passed in immediate mode.
   std::vector<std::string> ImmediateArgv;
 

include/swift/Option/Options.td

@@ -484,6 +484,9 @@ def module_abi_name : Separate<["-"], "module-abi-name">,
 def package_name : Separate<["-"], "package-name">,
   Flags<[FrontendOption, ModuleInterfaceOptionIgnorable]>,
   HelpText<"Name of the package the module belongs to">;
+def export_as : Separate<["-"], "export-as">,
+  Flags<[FrontendOption, ModuleInterfaceOptionIgnorable]>,
+  HelpText<"Module name to use when referenced in clients module interfaces">;
 
 def emit_module : Flag<["-"], "emit-module">,
   Flags<[FrontendOption, NoInteractiveOption, SupplementaryOutput]>,

include/swift/Serialization/SerializedModuleLoader.h

@@ -455,6 +455,8 @@ class SerializedASTFile final : public LoadedFile {
 
   virtual StringRef getModuleDefiningPath() const override;
 
+  virtual StringRef getExportedModuleName() const override;
+
   ValueDecl *getMainDecl() const override;
 
   bool hasEntryPoint() const override;

include/swift/Serialization/Validation.h

@@ -108,6 +108,7 @@ class ExtendedValidationInfo {
   std::string SDKPath;
   StringRef ModuleABIName;
   StringRef ModulePackageName;
+  StringRef ExportAsName;
   struct {
     unsigned ArePrivateImportsEnabled : 1;
     unsigned IsSIB : 1;
@@ -183,6 +184,9 @@ class ExtendedValidationInfo {
   StringRef getModulePackageName() const { return ModulePackageName; }
   void setModulePackageName(StringRef name) { ModulePackageName = name; }
 
+  StringRef getExportAsName() const { return ExportAsName; }
+  void setExportAsName(StringRef name) { ExportAsName = name; }
+
   bool isConcurrencyChecked() const {
     return Bits.IsConcurrencyChecked;
   }

lib/Driver/ToolChains.cpp

@@ -253,6 +253,7 @@ void ToolChain::addCommonFrontendArgs(const OutputInfo &OI,
   inputArgs.AddLastArg(arguments, options::OPT_module_link_name);
   inputArgs.AddLastArg(arguments, options::OPT_module_abi_name);
   inputArgs.AddLastArg(arguments, options::OPT_package_name);
+  inputArgs.AddLastArg(arguments, options::OPT_export_as);
   inputArgs.AddLastArg(arguments, options::OPT_nostdimport);
   inputArgs.AddLastArg(arguments, options::OPT_parse_stdlib);
   inputArgs.AddLastArg(arguments, options::OPT_resource_dir);

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -279,6 +279,14 @@ bool ArgsToFrontendOptionsConverter::convert(
       Opts.PackageName = pkgName;
   }
 
+  if (const Arg *A = Args.getLastArg(OPT_export_as)) {
+    auto exportAs = A->getValue();
+    if (!Lexer::isIdentifier(exportAs))
+      Diags.diagnose(SourceLoc(), diag::error_bad_export_as_name, exportAs);
+    else
+      Opts.ExportAsName = exportAs;
+  }
+
   // This must be called after computing module name, module abi name,
   // and module link name. If computing module aliases is unsuccessful,
   // return early.

lib/Frontend/Frontend.cpp

@@ -1085,6 +1085,10 @@ ModuleDecl *CompilerInstance::getMainModule() const {
       MainModule->setPackageName(getASTContext().getIdentifier(
           Invocation.getFrontendOptions().PackageName));
     }
+    if (!Invocation.getFrontendOptions().ExportAsName.empty()) {
+      MainModule->setExportAsName(getASTContext().getIdentifier(
+          Invocation.getFrontendOptions().ExportAsName));
+    }
     if (Invocation.getFrontendOptions().EnableLibraryEvolution)
       MainModule->setResilienceStrategy(ResilienceStrategy::Resilient);
     if (Invocation.getLangOptions().isSwiftVersionAtLeast(6))