Reland: [modules] Properly initialize declared variables.

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index 5b3959f5c317e85875b160de8e97b7e1849c6ce9..0f07fc0794bc6d1d16e1870c60875ddbed759931 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -932,7 +932,12 @@ void BytecodeGenerator::VisitVariableDeclaration(VariableDeclaration* decl) {
       break;
     }
     case VariableLocation::MODULE:
-      // Nothing to do here.
+      if (variable->IsExport() && variable->binding_needs_init()) {
+        builder()->LoadTheHole();
+        VisitVariableAssignment(variable, Token::INIT,
+                                FeedbackVectorSlot::Invalid());
+      }
+      // Nothing to do for imports.
       break;
   }
 }
@@ -972,7 +977,8 @@ void BytecodeGenerator::VisitFunctionDeclaration(FunctionDeclaration* decl) {
       break;
     }
     case VariableLocation::MODULE:
-      DCHECK(variable->mode() == LET);
+      DCHECK_EQ(variable->mode(), LET);
+      DCHECK(variable->IsExport());
       VisitForAccumulatorValue(decl->fun());
       VisitVariableAssignment(variable, Token::INIT,
                               FeedbackVectorSlot::Invalid());
@@ -2018,6 +2024,7 @@ void BytecodeGenerator::VisitVariableLoad(Variable* variable,
             .StoreAccumulatorInRegister(module_request)
             .CallRuntime(Runtime::kLoadModuleImport, import_name, 2);
       }
+      BuildHoleCheckForVariableLoad(variable);
       break;
     }
   }