Bug 575522 - Object.prototype.toString should return "[object Undefined]" and "[object Null]" when called with |this === undefined| or |this === null|, respectively. r=jorendorff,brendan

js/src/jsatom.cpp

@@ -158,6 +158,8 @@ const char *const js_common_atom_names[] = {
     js_name_str,                /* nameAtom                     */
     js_next_str,                /* nextAtom                     */
     js_noSuchMethod_str,        /* noSuchMethodAtom             */
+    "[object Null]",            /* objectNullAtom               */
+    "[object Undefined]",       /* objectUndefinedAtom          */
     js_proto_str,               /* protoAtom                    */
     js_set_str,                 /* setAtom                      */
     js_source_str,              /* sourceAtom                   */

js/src/jsatom.h

@@ -351,6 +351,8 @@ struct JSAtomState
     JSAtom              *nameAtom;
     JSAtom              *nextAtom;
     JSAtom              *noSuchMethodAtom;
+    JSAtom              *objectNullAtom;
+    JSAtom              *objectUndefinedAtom;
     JSAtom              *protoAtom;
     JSAtom              *setAtom;
     JSAtom              *sourceAtom;

js/src/jsobj.cpp

@@ -835,17 +835,32 @@ obj_toStringHelper(JSContext *cx, JSObject *obj)
 
 }
 
+/* ES5 15.2.4.2.  Note steps 1 and 2 are errata. */
 static JSBool
 obj_toString(JSContext *cx, uintN argc, Value *vp)
 {
-    JSObject *obj = ComputeThisFromVp(cx, vp);
-    if (!obj)
+    Value &thisv = vp[1];
+
+    /* ES5 15.2.4.2 step 1. */
+    if (thisv.isUndefined()) {
+        vp->setString(ATOM_TO_STRING(cx->runtime->atomState.objectUndefinedAtom));
+        return true;
+    }
+
+    /* ES5 15.2.4.2 step 2. */
+    if (thisv.isNull()) {
+        vp->setString(ATOM_TO_STRING(cx->runtime->atomState.objectNullAtom));
+        return true;
+    }
+
+    /* ES5 15.2.4.2 step 3. */
+    if (!thisv.isObject() && !js_PrimitiveToObject(cx, &thisv))
         return false;
 
-    JSString *str = js::obj_toStringHelper(cx, obj);
+    /* ES5 15.2.4.2 steps 4-5. */
+    JSString *str = js::obj_toStringHelper(cx, &thisv.toObject());
     if (!str)
         return false;
-
     vp->setString(str);
     return true;
 }
@@ -2692,7 +2707,7 @@ static JSFunctionSpec object_methods[] = {
 #if JS_HAS_TOSOURCE
     JS_FN(js_toSource_str,             obj_toSource,                0,0),
 #endif
-    JS_FN(js_toString_str,             obj_toString,                0,0),
+    JS_FN(js_toString_str,             obj_toString,                0,JSFUN_PRIMITIVE_THIS),
     JS_FN(js_toLocaleString_str,       obj_toLocaleString,          0,0),
     JS_FN(js_valueOf_str,              obj_valueOf,                 0,0),
 #if JS_HAS_OBJ_WATCHPOINT

js/src/tests/ecma_5/Object/jstests.list

@@ -37,4 +37,5 @@ skip-if(!xulRuntime.shell) script 15.2.3.6-dictionary-redefinition-7-of-8.js # u
 skip-if(!xulRuntime.shell) script 15.2.3.6-dictionary-redefinition-8-of-8.js # uses shell load() function
 script 15.2.3.6-define-over-method.js
 script mutation-prevention-methods.js
+script object-toString-01.js
 script vacuous-accessor-unqualified-name.js

js/src/tests/ecma_5/Object/object-toString-01.js

@@ -0,0 +1,46 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor:
+ *   Jeff Walden <jwalden+code@mit.edu>
+ */
+
+var gTestfile = 'object-toString-01.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 575522;
+var summary = '({}).toString.call(null) == "[object Null]", ' +
+              '({}).toString.call(undefined) == "[object Undefined]", ';
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var toString = Object.prototype.toString;
+
+assertEq(toString.call(null), "[object Null]");
+assertEq(toString.call(undefined), "[object Undefined]");
+
+assertEq(toString.call(true), "[object Boolean]");
+assertEq(toString.call(false), "[object Boolean]");
+
+assertEq(toString.call(0), "[object Number]");
+assertEq(toString.call(-0), "[object Number]");
+assertEq(toString.call(1), "[object Number]");
+assertEq(toString.call(-1), "[object Number]");
+assertEq(toString.call(NaN), "[object Number]");
+assertEq(toString.call(Infinity), "[object Number]");
+assertEq(toString.call(-Infinity), "[object Number]");
+
+assertEq(toString.call("foopy"), "[object String]");
+
+assertEq(toString.call({}), "[object Object]");
+
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("All tests passed!");