LibJS: Store Module::environment() as ModuleEnvironment

Let's use a more specific type here to allow for devirtualization.

Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2021-2025, Andreas Kling <andreas@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -26,6 +26,7 @@
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Iterator.h>
 #include <LibJS/Runtime/MathObject.h>
+#include <LibJS/Runtime/ModuleEnvironment.h>
 #include <LibJS/Runtime/NativeFunction.h>
 #include <LibJS/Runtime/ObjectEnvironment.h>
 #include <LibJS/Runtime/Realm.h>
@@ -1132,10 +1133,10 @@ inline ThrowCompletionOr<Value> get_global(Interpreter& interpreter, IdentifierT
 
     auto& identifier = interpreter.current_executable().get_identifier(identifier_index);
 
-    if (vm.running_execution_context().script_or_module.has<GC::Ref<Module>>()) {
+    if (auto* module = vm.running_execution_context().script_or_module.get_pointer<GC::Ref<Module>>()) {
         // NOTE: GetGlobal is used to access variables stored in the module environment and global environment.
         //       The module environment is checked first since it precedes the global environment in the environment chain.
-        auto& module_environment = *vm.running_execution_context().script_or_module.get<GC::Ref<Module>>()->environment();
+        auto& module_environment = *(*module)->environment();
         if (TRY(module_environment.has_binding(identifier))) {
             // TODO: Cache offset of binding value
             return TRY(module_environment.get_binding_value(vm, identifier, vm.in_strict_mode()));

Libraries/LibJS/Forward.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2021, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2020-2025, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2020-2022, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -189,6 +189,7 @@ class Intrinsics;
 class IteratorRecord;
 class MemberExpression;
 class MetaProperty;
+class ModuleEnvironment;
 class Module;
 struct ModuleRequest;
 class NativeFunction;

Libraries/LibJS/Module.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2021-2025, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2022, David Tuin <davidot@serenityos.org>
  * Copyright (c) 2023, networkException <networkexception@serenityos.org>
  *
@@ -8,6 +8,7 @@
 
 #include <LibJS/CyclicModule.h>
 #include <LibJS/Module.h>
+#include <LibJS/Runtime/ModuleEnvironment.h>
 #include <LibJS/Runtime/ModuleNamespaceObject.h>
 #include <LibJS/Runtime/ModuleRequest.h>
 #include <LibJS/Runtime/Promise.h>

Libraries/LibJS/Module.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ * Copyright (c) 2021-2025, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2022, David Tuin <davidot@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -100,7 +100,7 @@ public:
 
     StringView filename() const { return m_filename; }
 
-    Environment* environment() { return m_environment; }
+    GC::Ptr<ModuleEnvironment> environment() { return m_environment; }
 
     Script::HostDefined* host_defined() const { return m_host_defined; }
 
@@ -122,7 +122,7 @@ protected:
 
     virtual void visit_edges(Cell::Visitor&) override;
 
-    void set_environment(Environment* environment)
+    void set_environment(GC::Ref<ModuleEnvironment> environment)
     {
         m_environment = environment;
     }
@@ -136,7 +136,7 @@ private:
     // stores modules with a RefPtr we cannot just store the VM as that leads to
     // cycles.
     GC::Ptr<Realm> m_realm;                          // [[Realm]]
-    GC::Ptr<Environment> m_environment;              // [[Environment]]
+    GC::Ptr<ModuleEnvironment> m_environment;        // [[Environment]]
     GC::Ptr<Object> m_namespace;                     // [[Namespace]]
     Script::HostDefined* m_host_defined { nullptr }; // [[HostDefined]]
 

Libraries/LibJS/Runtime/ModuleEnvironment.cpp

@@ -34,7 +34,7 @@ ThrowCompletionOr<Value> ModuleEnvironment::get_binding_value(VM& vm, Deprecated
         // a. Let M and N2 be the indirection values provided when this binding for N was created.
 
         // b. Let targetEnv be M.[[Environment]].
-        auto* target_env = indirect_binding->module->environment();
+        auto target_env = indirect_binding->module->environment();
 
         // c. If targetEnv is empty, throw a ReferenceError exception.
         if (!target_env)
@@ -97,11 +97,10 @@ Optional<ModuleEnvironment::BindingAndIndex> ModuleEnvironment::find_binding_and
 {
     auto* indirect_binding = get_indirect_binding(name);
     if (indirect_binding != nullptr) {
-        auto* target_env = indirect_binding->module->environment();
+        auto target_env = indirect_binding->module->environment();
         if (!target_env)
             return {};
 
-        VERIFY(is<ModuleEnvironment>(target_env));
         auto& target_module_environment = static_cast<ModuleEnvironment&>(*target_env);
         auto result = target_module_environment.find_binding_and_index(indirect_binding->binding_name);
         if (!result.has_value())

Libraries/LibJS/Runtime/ModuleNamespaceObject.cpp

@@ -6,6 +6,7 @@
 
 #include <AK/QuickSort.h>
 #include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/ModuleEnvironment.h>
 #include <LibJS/Runtime/ModuleNamespaceObject.h>
 
 namespace JS {
@@ -173,7 +174,7 @@ ThrowCompletionOr<Value> ModuleNamespaceObject::internal_get(PropertyKey const&
     }
 
     // 10. Let targetEnv be targetModule.[[Environment]].
-    auto* target_environment = target_module->environment();
+    auto target_environment = target_module->environment();
 
     // 11. If targetEnv is empty, throw a ReferenceError exception.
     if (!target_environment)