LibJS: Only allow TimeZone this value in Temporal.TimeZone#id

This is a normative change in the Temporal spec.

See: https://github.com/tc39/proposal-temporal/commit/2644fc6

2 files changed, 10 insertions, 5 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
index abf53e0b5f..4e13169c37 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
@@ -48,10 +48,11 @@ void TimeZonePrototype::initialize(GlobalObject& global_object)
 JS_DEFINE_NATIVE_FUNCTION(TimeZonePrototype::id_getter)
 {
     // 1. Let timeZone be the this value.
-    auto time_zone = vm.this_value(global_object);
+    // 2. Perform ? RequireInternalSlot(timeZone, [[InitializedTemporalTimeZone]]).
+    auto* time_zone = TRY(typed_this_object(global_object));
 
-    // 2. Return ? ToString(timeZone).
-    return js_string(vm, TRY(time_zone.to_string(global_object)));
+    // 3. Return ? ToString(timeZone).
+    return js_string(vm, TRY(Value(time_zone).to_string(global_object)));
 }
 
 // 11.4.4 Temporal.TimeZone.prototype.getOffsetNanosecondsFor ( instant ), https://tc39.es/proposal-temporal/#sec-temporal.timezone.prototype.getoffsetnanosecondsfor
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.id.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.id.js
index 7a85daf14c..7da702bbca 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.id.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.id.js
@@ -3,8 +3,12 @@ describe("correct behavior", () => {
         const timeZone = new Temporal.TimeZone("UTC");
         expect(timeZone.id).toBe("UTC");
     });
+});
 
-    test("works with any this value", () => {
-        expect(Reflect.get(Temporal.TimeZone.prototype, "id", "foo")).toBe("foo");
+describe("errors", () => {
+    test("this value must be a Temporal.TimeZone object", () => {
+        expect(() => {
+            Reflect.get(Temporal.TimeZone.prototype, "id", "foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.TimeZone");
     });
 });