From 5606332ed72e60fa720cf17ad055cca8d2d36b05 Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Wed, 30 Jun 2021 17:54:47 +0300
Subject: [PATCH] LibJS: Add a [[Realm]] getter to FunctionObject and use it
 where needed

Defined by https://tc39.es/ecma262/#sec-ordinaryfunctioncreate step #17
and by https://tc39.es/ecma262/#sec-createbuiltinfunction step #6.
---
 Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp     | 5 ++---
 Userland/Libraries/LibJS/Runtime/FunctionObject.h           | 3 +++
 Userland/Libraries/LibJS/Runtime/NativeFunction.h           | 2 ++
 Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp | 1 +
 Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h   | 3 +++
 5 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
index b9441a6e4a..9f045b211f 100644
--- a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
@@ -110,9 +110,8 @@ GlobalObject* get_function_realm(GlobalObject& global_object, FunctionObject con
 {
     auto& vm = global_object.vm();
 
-    // FIXME: not sure how to do this currently.
-    // 2. If obj has a [[Realm]] internal slot, then
-    //     a. Return obj.[[Realm]].
+    if (function.realm())
+        return function.realm();
     if (is<BoundFunction>(function)) {
         auto& bound_function = static_cast<BoundFunction const&>(function);
         auto& target = bound_function.target_function();
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionObject.h b/Userland/Libraries/LibJS/Runtime/FunctionObject.h
index 2db3894dde..91f5b35cd7 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionObject.h
+++ b/Userland/Libraries/LibJS/Runtime/FunctionObject.h
@@ -47,6 +47,9 @@ public:
     // Used as the outer environment when evaluating the code of the function.
     virtual EnvironmentRecord* environment() { return nullptr; }
 
+    // [[Realm]]
+    virtual GlobalObject* realm() const { return nullptr; }
+
     enum class ThisMode : u8 {
         Lexical,
         Strict,
diff --git a/Userland/Libraries/LibJS/Runtime/NativeFunction.h b/Userland/Libraries/LibJS/Runtime/NativeFunction.h
index aa7899f456..39d66edb76 100644
--- a/Userland/Libraries/LibJS/Runtime/NativeFunction.h
+++ b/Userland/Libraries/LibJS/Runtime/NativeFunction.h
@@ -29,6 +29,8 @@ public:
 
     virtual bool is_strict_mode() const override;
 
+    GlobalObject* realm() const override { return &global_object(); }
+
 protected:
     NativeFunction(FlyString name, Object& prototype);
     explicit NativeFunction(Object& prototype);
diff --git a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
index ac2d9c0763..0c01c16fcc 100644
--- a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.cpp
@@ -56,6 +56,7 @@ OrdinaryFunctionObject::OrdinaryFunctionObject(GlobalObject& global_object, cons
     , m_body(body)
     , m_parameters(move(parameters))
     , m_environment(parent_scope)
+    , m_realm(&global_object)
     , m_function_length(function_length)
     , m_kind(kind)
     , m_is_strict(is_strict)
diff --git a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
index dfdf96cb42..5720c87845 100644
--- a/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
+++ b/Userland/Libraries/LibJS/Runtime/OrdinaryFunctionObject.h
@@ -37,6 +37,8 @@ public:
 
     virtual EnvironmentRecord* environment() override { return m_environment; }
 
+    GlobalObject* realm() const override { return m_realm; }
+
 protected:
     virtual bool is_strict_mode() const final { return m_is_strict; }
 
@@ -55,6 +57,7 @@ private:
     const Vector<FunctionNode::Parameter> m_parameters;
     Optional<Bytecode::Executable> m_bytecode_executable;
     EnvironmentRecord* m_environment { nullptr };
+    GlobalObject* m_realm { nullptr };
     i32 m_function_length { 0 };
     FunctionKind m_kind { FunctionKind::Regular };
     bool m_is_strict { false };