LibJS: Implement WeakSet changes from 'Symbol as WeakMap Keys Proposal'

Userland/Libraries/LibJS/Runtime/WeakSetPrototype.cpp

@@ -1,11 +1,12 @@
 /*
- * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2021-2022, Idan Horowitz <idan.horowitz@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/HashTable.h>
 #include <AK/TypeCasts.h>
+#include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/WeakSetPrototype.h>
 
 namespace JS {
@@ -34,9 +35,9 @@ JS_DEFINE_NATIVE_FUNCTION(WeakSetPrototype::add)
 {
     auto* weak_set = TRY(typed_this_object(global_object));
     auto value = vm.argument(0);
-    if (!value.is_object())
-        return vm.throw_completion<TypeError>(global_object, ErrorType::NotAnObject, value.to_string_without_side_effects());
-    weak_set->values().set(&value.as_object(), AK::HashSetExistingEntryBehavior::Keep);
+    if (!can_be_held_weakly(value))
+        return vm.throw_completion<TypeError>(global_object, ErrorType::CannotBeHeldWeakly, value.to_string_without_side_effects());
+    weak_set->values().set(&value.as_cell(), AK::HashSetExistingEntryBehavior::Keep);
     return weak_set;
 }
 
@@ -45,9 +46,9 @@ JS_DEFINE_NATIVE_FUNCTION(WeakSetPrototype::delete_)
 {
     auto* weak_set = TRY(typed_this_object(global_object));
     auto value = vm.argument(0);
-    if (!value.is_object())
+    if (!can_be_held_weakly(value))
         return Value(false);
-    return Value(weak_set->values().remove(&value.as_object()));
+    return Value(weak_set->values().remove(&value.as_cell()));
 }
 
 // 24.4.3.4 WeakSet.prototype.has ( value ), https://tc39.es/ecma262/#sec-weakset.prototype.has
@@ -55,10 +56,10 @@ JS_DEFINE_NATIVE_FUNCTION(WeakSetPrototype::has)
 {
     auto* weak_set = TRY(typed_this_object(global_object));
     auto value = vm.argument(0);
-    if (!value.is_object())
+    if (!can_be_held_weakly(value))
         return Value(false);
     auto& values = weak_set->values();
-    return Value(values.find(&value.as_object()) != values.end());
+    return Value(values.find(&value.as_cell()) != values.end());
 }
 
 }

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.js

@@ -24,7 +24,7 @@ describe("normal behavior", () => {
     });
 
     test("constructor with single array argument", () => {
-        var a = new WeakSet([{ a: 1 }, { a: 2 }, { a: 3 }]);
+        var a = new WeakSet([{ a: 1 }, { a: 2 }, { a: 3 }, Symbol("foo")]);
         expect(a instanceof WeakSet).toBeTrue();
     });
 });

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.add.js

@@ -1,9 +1,10 @@
 test("basic functionality", () => {
     expect(WeakSet.prototype.add).toHaveLength(1);
 
-    const weakSet = new WeakSet([{ a: 1 }, { a: 2 }, { a: 3 }]);
+    const weakSet = new WeakSet([{ a: 1 }, { a: 2 }, { a: 3 }, Symbol("foo")]);
     expect(weakSet.add({ a: 4 })).toBe(weakSet);
     expect(weakSet.add({ a: 1 })).toBe(weakSet);
+    expect(weakSet.add(Symbol("bar"))).toBe(weakSet);
 });
 
 test("invalid values", () => {
@@ -11,18 +12,28 @@ test("invalid values", () => {
     [-100, Infinity, NaN, "hello", 152n].forEach(value => {
         expect(() => {
             weakSet.add(value);
-        }).toThrowWithMessage(TypeError, "is not an object");
+        }).toThrowWithMessage(TypeError, "cannot be held weakly");
     });
 });
 
 test("automatic removal of garbage-collected values", () => {
     const weakSet = new WeakSet();
-    const item = { a: 1 };
+    const objectItem = { a: 1 };
 
-    expect(weakSet.add(item)).toBe(weakSet);
+    expect(weakSet.add(objectItem)).toBe(weakSet);
     expect(getWeakSetSize(weakSet)).toBe(1);
 
-    markAsGarbage("item");
+    markAsGarbage("objectItem");
+    gc();
+
+    expect(getWeakSetSize(weakSet)).toBe(0);
+
+    const symbolItem = Symbol("foo");
+
+    expect(weakSet.add(symbolItem)).toBe(weakSet);
+    expect(getWeakSetSize(weakSet)).toBe(1);
+
+    markAsGarbage("symbolItem");
     gc();
 
     expect(getWeakSetSize(weakSet)).toBe(0);

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.delete.js

@@ -1,9 +1,11 @@
 test("basic functionality", () => {
     expect(WeakSet.prototype.delete).toHaveLength(1);
 
-    var original = [{ a: 1 }, { a: 2 }, { a: 3 }];
+    var original = [{ a: 1 }, { a: 2 }, { a: 3 }, Symbol("foo")];
     const weakSet = new WeakSet(original);
     expect(weakSet.delete(original[0])).toBeTrue();
     expect(weakSet.delete(original[0])).toBeFalse();
+    expect(weakSet.delete(original[3])).toBeTrue();
+    expect(weakSet.delete(original[3])).toBeFalse();
     expect(weakSet.delete(null)).toBeFalse();
 });

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.has.js

@@ -3,10 +3,12 @@ test("length is 1", () => {
 });
 
 test("basic functionality", () => {
-    var original = [{ a: 1 }, { a: 2 }, { a: 3 }];
+    var original = [{ a: 1 }, { a: 2 }, { a: 3 }, Symbol("foo")];
     var weakSet = new WeakSet(original);
 
     expect(new WeakSet().has()).toBeFalse();
     expect(weakSet.has(original[0])).toBeTrue();
+    expect(weakSet.has(original[3])).toBeTrue();
     expect(weakSet.has({ a: 1 })).toBeFalse();
+    expect(weakSet.has(Symbol("foo"))).toBeFalse();
 });