Bump WebKit (oven-sh/WebKit#590 preview): ShadowRealm wraps a returned callable for the caller's realm

scripts/build/deps/webkit.ts

@@ -3,7 +3,7 @@
  * for local mode. Override via `--webkit-version=<hash>` to test a branch.
  * From https://github.com/oven-sh/WebKit releases.
  */
-export const WEBKIT_VERSION = "2e2aa2290fac856d6f451ceacb58f7f5b44dd057";
+export const WEBKIT_VERSION = "autobuild-preview-pr-590-c7520f66";
 
 /**
  * WebKit (JavaScriptCore) — the JS engine.

test/js/bun/jsc/shadow.test.js

@@ -8,3 +8,52 @@ it("shadow realm works", () => {
   expect(globalThis.someValue).toBe(1);
   expect(result).toBe(2);
 });
+
+// A callable that a wrapped function returns is wrapped for the caller's realm,
+// so its prototype is the caller's Function.prototype. The engine uses a
+// separate call path for a target that is not a plain function, so check one
+// target of each kind.
+it.each([
+  ["a plain function", `() => () => 1`],
+  ["a bound function", `(() => () => 1).bind(undefined)`],
+  ["the realm's Function constructor", `Function`],
+  ["a callable Proxy", `new Proxy(() => () => 1, {})`],
+  ["a Proxy with an apply trap", `new Proxy(() => {}, { apply: () => () => 1 })`],
+])("a callable returned through %s belongs to the caller's realm", (name, source) => {
+  const wrapped = new ShadowRealm().evaluate(source);
+  const returned = wrapped();
+  expect(typeof returned).toBe("function");
+  expect(Object.getPrototypeOf(returned)).toBe(Function.prototype);
+});
+
+it("a returned wrapper does not expose the shadow realm's global object", () => {
+  const realm = new ShadowRealm();
+  const made = realm.evaluate(`Function`)("return 1");
+
+  // The wrapper's prototype is the caller's Function.prototype, so the
+  // constructor found on it compiles code in the caller's realm.
+  const constructor = Object.getPrototypeOf(made).constructor;
+  expect(constructor).toBe(Function);
+  expect(constructor("return globalThis")()).toBe(globalThis);
+
+  // The realm's global stays out of reach, so the two globals share no state.
+  globalThis.injectedByShadowTest = { list: [] };
+  try {
+    expect(realm.evaluate(`typeof globalThis.injectedByShadowTest`)).toBe("undefined");
+  } finally {
+    delete globalThis.injectedByShadowTest;
+  }
+});
+
+it("a callable returned to the shadow realm belongs to the shadow realm", () => {
+  const realm = new ShadowRealm();
+  const fromRealm = realm.evaluate(`(f) => {
+    const proto = Object.getPrototypeOf(f());
+    if (proto !== Function.prototype) return typeof proto.constructor("return globalThis")().Bun;
+    return "ok";
+  }`);
+
+  expect(fromRealm(new Proxy(() => () => 1, {}))).toBe("ok");
+  expect(fromRealm(() => () => 1)).toBe("ok");
+  expect(fromRealm(Function)).toBe("ok");
+});