Object.prototype has an immutable prototype

Author: Fabrice Bellard

TODO

@@ -62,6 +62,6 @@ Optimization ideas:
 Test262o:   0/11262 errors, 463 excluded
 Test262o commit: 7da91bceb9ce7613f87db47ddd1292a2dda58b42 (es5-tests branch)
 
-Result: 66/78176 errors, 1612 excluded, 7236 skipped
-Test262 commit: 56e77d6325067a545ea7e8ff5be5d9284334e33c
+Result: 65/78182 errors, 1628 excluded, 7233 skipped
+Test262 commit: 27622d764767dcb3778784884022c2c7de5769b8
 

quickjs.c

@@ -914,6 +914,7 @@ struct JSObject {
             uint8_t is_exotic : 1; /* TRUE if object has exotic property handlers */
             uint8_t fast_array : 1; /* TRUE if u.array is used for get/put (for JS_CLASS_ARRAY, JS_CLASS_ARGUMENTS and typed arrays) */
             uint8_t is_constructor : 1; /* TRUE if object is a constructor function */
+            uint8_t has_immutable_prototype : 1; /* cannot modify the prototype */
             uint8_t tmp_mark : 1; /* used in JS_WriteObjectRec() */
             uint8_t is_HTMLDDA : 1; /* specific annex B IsHtmlDDA behavior */
             uint16_t class_id; /* see JS_CLASS_x */
@@ -5053,6 +5054,7 @@ static JSValue JS_NewObjectFromShape(JSContext *ctx, JSShape *sh, JSClassID clas
     p->is_exotic = 0;
     p->fast_array = 0;
     p->is_constructor = 0;
+    p->has_immutable_prototype = 0;
     p->tmp_mark = 0;
     p->is_HTMLDDA = 0;
     p->weakref_count = 0;
@@ -7192,6 +7194,15 @@ static inline __exception int js_poll_interrupts(JSContext *ctx)
     }
 }
 
+static void JS_SetImmutablePrototype(JSContext *ctx, JSValueConst obj)
+{
+    JSObject *p;
+    if (JS_VALUE_GET_TAG(obj) != JS_TAG_OBJECT)
+        return;
+    p = JS_VALUE_GET_OBJ(obj);
+    p->has_immutable_prototype = TRUE;
+}
+
 /* Return -1 (exception) or TRUE/FALSE. 'throw_flag' = FALSE indicates
    that it is called from Reflect.setPrototypeOf(). */
 static int JS_SetPrototypeInternal(JSContext *ctx, JSValueConst obj,
@@ -7241,7 +7252,15 @@ static int JS_SetPrototypeInternal(JSContext *ctx, JSValueConst obj,
     sh = p->shape;
     if (sh->proto == proto)
         return TRUE;
-    if (!p->extensible) {
+    if (unlikely(p->has_immutable_prototype)) {
+        if (throw_flag) {
+            JS_ThrowTypeError(ctx, "prototype is immutable");
+            return -1;
+        } else {
+            return FALSE;
+        }
+    }
+    if (unlikely(!p->extensible)) {
         if (throw_flag) {
             JS_ThrowTypeError(ctx, "object is not extensible");
             return -1;
@@ -51162,6 +51181,8 @@ static void JS_AddIntrinsicBasicObjects(JSContext *ctx)
     int i;
 
     ctx->class_proto[JS_CLASS_OBJECT] = JS_NewObjectProto(ctx, JS_NULL);
+    JS_SetImmutablePrototype(ctx, ctx->class_proto[JS_CLASS_OBJECT]);
+    
     ctx->function_proto = JS_NewCFunction3(ctx, js_function_proto, "", 0,
                                            JS_CFUNC_generic, 0,
                                            ctx->class_proto[JS_CLASS_OBJECT]);

test262_errors.txt

@@ -5,7 +5,7 @@ test262/test/staging/sm/Date/non-iso.js:76: Test262Error: Expected SameValue(«N
 test262/test/staging/sm/Date/two-digit-years.js:76: Test262Error: Expected SameValue(«915177600000», «NaN») to be true
 test262/test/staging/sm/Function/arguments-parameter-shadowing.js:15: Test262Error: Expected SameValue(«true», «false») to be true
 test262/test/staging/sm/Function/constructor-binding.js:12: Test262Error: Expected SameValue(«"function"», «"undefined"») to be true
-test262/test/staging/sm/Function/function-bind.js:14: Test262Error: Expected SameValue(«false», «true») to be true
+test262/test/staging/sm/Function/function-bind.js:14: Test262Error: Conforms to NativeFunction Syntax: "function bound unbound() {\n    [native code]\n}"
 test262/test/staging/sm/Function/function-name-for.js:12: Test262Error: Expected SameValue(«""», «"forInHead"») to be true
 test262/test/staging/sm/Function/function-toString-builtin.js:14: Test262Error: Expected match to '/^\s*function\s*(get|set)?\s*(\w+|(?:'[^']*')|(?:"[^"]*")|\d+|(?:\[[^\]]+\]))?\s*\(\s*\)\s*\{\s*\[native code\]\s*\}\s*$/', Actual value 'function bound fn() {
     [native code]
@@ -51,7 +51,6 @@ test262/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-if.js
 test262/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-notapplicable.js:15: Test262Error: Expected SameValue(«function x() {2}», «function x() {1}») to be true
 test262/test/staging/sm/lexical-environment/block-scoped-functions-deprecated-redecl.js:23: Test262Error: Expected SameValue(«3», «4») to be true
 test262/test/staging/sm/lexical-environment/var-in-catch-body-annex-b-eval.js:17: Test262Error: Expected SameValue(«"g"», «"global-x"») to be true
-test262/test/staging/sm/module/module-export-name-star.js:15: SyntaxError: identifier expected
 test262/test/staging/sm/object/defineProperties-order.js:14: Test262Error: Expected SameValue(«"ownKeys,getOwnPropertyDescriptor,getOwnPropertyDescriptor,get,get"», «"ownKeys,getOwnPropertyDescriptor,get,getOwnPropertyDescriptor,get"») to be true
 test262/test/staging/sm/regress/regress-577648-1.js:21: Test262Error: 1 Expected SameValue(«true», «false») to be true
 test262/test/staging/sm/regress/regress-577648-2.js:14: Test262Error:  Expected SameValue(«true», «false») to be true