Bug 1068589 - Remove forced extensible check before calling JSObject::preventExtensions. r=jwalden

--HG--
extra : rebase_source : 5ec8efb801fd67dd7c9d08ad0259aaee36f225ce

js/src/builtin/Object.cpp

@@ -1044,12 +1044,6 @@ obj_preventExtensions(JSContext *cx, unsigned argc, Value *vp)
 
     args.rval().setObject(*obj);
 
-    bool extensible;
-    if (!JSObject::isExtensible(cx, obj, &extensible))
-        return false;
-    if (!extensible)
-        return true;
-
     return JSObject::preventExtensions(cx, obj);
 }
 

js/src/jit-test/tests/proxy/target-becomes-nonextensible-during-preventExtensions.js

@@ -0,0 +1,8 @@
+// Don't assert
+var obj = {};
+var proxy = new Proxy(obj, {
+    get preventExtensions() {
+        Object.preventExtensions(obj);
+    }
+});
+Object.preventExtensions(proxy);

js/src/jsapi.cpp

@@ -6517,11 +6517,6 @@ JS_DecodeInterpretedFunction(JSContext *cx, const void *data, uint32_t length)
 JS_PUBLIC_API(bool)
 JS_PreventExtensions(JSContext *cx, JS::HandleObject obj)
 {
-    bool extensible;
-    if (!JSObject::isExtensible(cx, obj, &extensible))
-        return false;
-    if (!extensible)
-        return true;
     return JSObject::preventExtensions(cx, obj);
 }
 

js/src/jsobj.cpp

@@ -1267,10 +1267,7 @@ JSObject::sealOrFreeze(JSContext *cx, HandleObject obj, ImmutabilityType it)
     assertSameCompartment(cx, obj);
     JS_ASSERT(it == SEAL || it == FREEZE);
 
-    bool extensible;
-    if (!JSObject::isExtensible(cx, obj, &extensible))
-        return false;
-    if (extensible && !JSObject::preventExtensions(cx, obj))
+    if (!JSObject::preventExtensions(cx, obj))
         return false;
 
     AutoIdVector props(cx);

js/src/tests/ecma_6/Object/freeze-proxy.js

@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function logProxy(object = {}, handler = {}) {
+    var log = [];
+    var proxy = new Proxy(object, new Proxy(handler, {
+        get(target, propertyKey, receiver) {
+            log.push(propertyKey);
+            return target[propertyKey];
+        }
+    }));
+    return {proxy, log};
+}
+
+// The order of operations is backwards when compared to ES6 draft rev 27
+// (2014 August 24), but see https://bugs.ecmascript.org/show_bug.cgi?id=3215
+// for an explanation on why the spec version is clearly wrong.
+
+var {proxy, log} = logProxy();
+Object.freeze(proxy);
+assertDeepEq(log, ["preventExtensions", "ownKeys"]);
+
+var {proxy, log} = logProxy();
+Object.freeze(Object.freeze(proxy));
+assertDeepEq(log, ["preventExtensions", "ownKeys", "preventExtensions", "ownKeys"]);
+
+reportCompare(0, 0);

js/src/tests/ecma_6/Object/preventExtensions-proxy.js

@@ -0,0 +1,23 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function logProxy(object = {}, handler = {}) {
+    var log = [];
+    var proxy = new Proxy(object, new Proxy(handler, {
+        get(target, propertyKey, receiver) {
+            log.push(propertyKey);
+            return target[propertyKey];
+        }
+    }));
+    return {proxy, log};
+}
+
+var {proxy, log} = logProxy();
+Object.preventExtensions(proxy);
+assertDeepEq(log, ["preventExtensions"]);
+
+var {proxy, log} = logProxy();
+Object.preventExtensions(Object.preventExtensions(proxy));
+assertDeepEq(log, ["preventExtensions", "preventExtensions"]);
+
+reportCompare(0, 0);

js/src/tests/ecma_6/Object/seal-proxy.js

@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function logProxy(object = {}, handler = {}) {
+    var log = [];
+    var proxy = new Proxy(object, new Proxy(handler, {
+        get(target, propertyKey, receiver) {
+            log.push(propertyKey);
+            return target[propertyKey];
+        }
+    }));
+    return {proxy, log};
+}
+
+// The order of operations is backwards when compared to ES6 draft rev 27
+// (2014 August 24), but see https://bugs.ecmascript.org/show_bug.cgi?id=3215
+// for an explanation on why the spec version is clearly wrong.
+
+var {proxy, log} = logProxy();
+Object.seal(proxy);
+assertDeepEq(log, ["preventExtensions", "ownKeys"]);
+
+var {proxy, log} = logProxy();
+Object.seal(Object.seal(proxy));
+assertDeepEq(log, ["preventExtensions", "ownKeys", "preventExtensions", "ownKeys"]);
+
+reportCompare(0, 0);

js/src/vm/Debugger.cpp

@@ -5577,13 +5577,6 @@ DebuggerObject_sealHelper(JSContext *cx, unsigned argc, Value *vp, SealHelperOp
         ok = JSObject::freeze(cx, obj);
     } else {
         JS_ASSERT(op == PreventExtensions);
-        bool extensible;
-        if (!JSObject::isExtensible(cx, obj, &extensible))
-            return false;
-        if (!extensible) {
-            args.rval().setUndefined();
-            return true;
-        }
         ok = JSObject::preventExtensions(cx, obj);
     }
     if (!ok)

js/src/vm/Shape.cpp

@@ -1341,20 +1341,14 @@ Shape::setObjectMetadata(JSContext *cx, JSObject *metadata, TaggedProto proto, S
 /* static */ bool
 js::ObjectImpl::preventExtensions(JSContext *cx, Handle<ObjectImpl*> obj)
 {
-#ifdef DEBUG
-    bool extensible;
-    if (!JSObject::isExtensible(cx, obj, &extensible))
-        return false;
-    MOZ_ASSERT(extensible,
-               "Callers must ensure |obj| is extensible before calling "
-               "preventExtensions");
-#endif
-
     if (Downcast(obj)->is<ProxyObject>()) {
         RootedObject object(cx, obj->asObjectPtr());
         return js::Proxy::preventExtensions(cx, object);
     }
 
+    if (!obj->nonProxyIsExtensible())
+        return true;
+
     RootedObject self(cx, obj->asObjectPtr());
 
     /*