[modules] Detect all indirect exports and represent them as such.

src/ast/modules.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_AST_MODULES_H_
 #define V8_AST_MODULES_H_
 
 #include "src/parsing/scanner.h"  // Only for Scanner::Location.
 #include "src/pending-compilation-error-handler.h"
 #include "src/zone-containers.h"
@@ skipping 45 matching lines @@
     const AstRawString* export_name, const AstRawString* import_name,
     const AstRawString* module_request, const Scanner::Location loc,
     Zone* zone);
 
   // export * from "foo.js";
   void AddStarExport(
     const AstRawString* module_request, const Scanner::Location loc,
     Zone* zone);
 
   // Check if module is well-formed and report error if not.
+  // Also canonicalize indirect exports.
   bool Validate(DeclarationScope* module_scope,
-                PendingCompilationErrorHandler* error_handler,
-                Zone* zone) const;
+                PendingCompilationErrorHandler* error_handler, Zone* zone);
 
   struct ModuleEntry : public ZoneObject {
     const Scanner::Location location;
     const AstRawString* export_name;
     const AstRawString* local_name;
     const AstRawString* import_name;
     const AstRawString* module_request;
 
     explicit ModuleEntry(Scanner::Location loc)
         : location(loc),
           export_name(nullptr),
           local_name(nullptr),
           import_name(nullptr),
           module_request(nullptr) {}
   };
 
-  const ZoneList<const ModuleEntry*>& exports() const { return exports_; }
+  const ZoneList<ModuleEntry*>& exports() const { return exports_; }
 
   // Empty imports and namespace imports.
   const ZoneList<const ModuleEntry*>& special_imports() const {
     return special_imports_;
   }
 
   // All the remaining imports, indexed by local name.
   const ZoneMap<const AstRawString*, const ModuleEntry*>& regular_imports()
       const {
     return regular_imports_;
   }
 
  private:
-  ZoneList<const ModuleEntry*> exports_;
+  ZoneList<ModuleEntry*> exports_;
   ZoneList<const ModuleEntry*> special_imports_;
   ZoneMap<const AstRawString*, const ModuleEntry*> regular_imports_;
+
+  // Find any implicitly indirect exports and make them explicit.
+  //
+  // An explicitly indirect export is an export entry arising from an export
+  // statement of the following form:
+  //   export {a as c} from "X";
+  // An implicitly indirect export corresponds to
+  //   export {b as c};
+  // in the presence of an import statement of the form
+  //   import {a as b} from "X";
+  // This function finds such implicitly indirect export entries and rewrites
+  // them by filling in the import name and module request, as well as nulling
+  // out the local name.  Effectively, it turns
+  //   import {a as b} from "X"; export {b as c};
+  // into:
+  //   import {a as b} from "X"; export {a as c} from "X";
+  // (The import entry is never deleted.)
+  void MakeIndirectExportsExplicit();
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_MODULES_H_