Allow updating of name of a function, as required by the standard (#…

…1398)

Make the attributes of the "name" properties of functions match current ECMAScript specs.

See #1297 for more details

src/org/mozilla/javascript/Arguments.java

@@ -424,6 +424,7 @@ private static class ThrowTypeError extends BaseFunction {
 
         ThrowTypeError(String propertyName) {
             this.propertyName = propertyName;
+            super.setInstanceIdAttributes(BaseFunction.Id_name, PERMANENT | READONLY | DONTENUM);
         }
 
         @Override

src/org/mozilla/javascript/BaseFunction.java

@@ -100,7 +100,7 @@ public boolean hasInstance(Scriptable instance) {
         throw ScriptRuntime.typeErrorById("msg.instanceof.bad.prototype", getFunctionName());
     }
 
-    private static final int Id_length = 1,
+    protected static final int Id_length = 1,
             Id_arity = 2,
             Id_name = 3,
             Id_prototype = 4,
@@ -169,7 +169,9 @@ protected Object getInstanceIdValue(int id) {
             case Id_arity:
                 return arityPropertyAttributes >= 0 ? getArity() : NOT_FOUND;
             case Id_name:
-                return namePropertyAttributes >= 0 ? getFunctionName() : NOT_FOUND;
+                return namePropertyAttributes >= 0
+                        ? (nameValue != null ? nameValue : getFunctionName())
+                        : NOT_FOUND;
             case Id_prototype:
                 return getPrototypeProperty();
             case Id_arguments:
@@ -200,6 +202,11 @@ protected void setInstanceIdValue(int id, Object value) {
             case Id_name:
                 if (value == NOT_FOUND) {
                     namePropertyAttributes = -1;
+                    nameValue = null;
+                } else if (value instanceof CharSequence) {
+                    nameValue = ScriptRuntime.toString(value);
+                } else {
+                    nameValue = "";
                 }
                 return;
             case Id_arity:
@@ -650,6 +657,7 @@ protected int findPrototypeId(String s) {
 
     private Object prototypeProperty;
     private Object argumentsObj = NOT_FOUND;
+    private String nameValue = null;
     private boolean isGeneratorFunction = false;
 
     // For function object instances, attributes are
@@ -658,6 +666,6 @@ protected int findPrototypeId(String s) {
     private int prototypePropertyAttributes = PERMANENT | DONTENUM;
     private int argumentsAttributes = PERMANENT | DONTENUM;
     private int arityPropertyAttributes = PERMANENT | READONLY | DONTENUM;
-    private int namePropertyAttributes = PERMANENT | READONLY | DONTENUM;
+    private int namePropertyAttributes = READONLY | DONTENUM;
     private int lengthPropertyAttributes = PERMANENT | READONLY | DONTENUM;
 }

src/org/mozilla/javascript/IdScriptableObject.java

@@ -867,13 +867,14 @@ protected void defineOwnProperty(
                     checkPropertyChange(name, current, desc);
                     int attr = (info >>> 16);
                     Object value = getProperty(desc, "value");
-                    if (value != NOT_FOUND && (attr & READONLY) == 0) {
+                    if (value != NOT_FOUND && ((attr & READONLY) == 0 || (attr & PERMANENT) == 0)) {
                         Object currentValue = getInstanceIdValue(id);
                         if (!sameValue(value, currentValue)) {
                             setInstanceIdValue(id, value);
                         }
                     }
-                    setAttributes(name, applyDescriptorToAttributeBitset(attr, desc));
+                    attr = applyDescriptorToAttributeBitset(attr, desc);
+                    setAttributes(name, attr);
                     return;
                 }
             }

testsrc/org/mozilla/javascript/tests/es6/Issue1297FunctionNameTest.java

@@ -0,0 +1,31 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.javascript.tests.es6;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.mozilla.javascript.Scriptable;
+import org.mozilla.javascript.tests.Utils;
+
+/** Test that we can redefine a function's name. */
+public class Issue1297FunctionNameTest {
+    private static final String source =
+            "'use strict';"
+                    + "function X() {};\n"
+                    + "Object.defineProperty(X, 'name', {value: 'y', configurable: true, writable: true});"
+                    + "X.name";
+
+    @Test
+    public void canSetFunctionName() {
+        Utils.runWithAllOptimizationLevels(
+                cx -> {
+                    Scriptable scope = cx.initStandardObjects(null);
+                    Object result = cx.evaluateString(scope, source, "test", 1, null);
+                    assertEquals("y", result);
+                    return null;
+                });
+    }
+}

testsrc/test262.properties

@@ -449,12 +449,10 @@ built-ins/Date 39/707 (5.52%)
     S15.1.3.2_A2.4_T1.js
     S15.1.3.2_A5.2.js
 
-built-ins/encodeURI 2/30 (6.67%)
-    name.js
+built-ins/encodeURI 1/30 (3.33%)
     S15.1.3.3_A5.2.js
 
-built-ins/encodeURIComponent 2/30 (6.67%)
-    name.js
+built-ins/encodeURIComponent 1/30 (3.33%)
     S15.1.3.4_A5.2.js
 
 built-ins/Error 5/42 (11.9%)
@@ -464,9 +462,8 @@ built-ins/Error 5/42 (11.9%)
     prototype/S15.11.4_A2.js
     proto-from-ctor-realm.js {unsupported: [Reflect]}
 
-built-ins/eval 3/9 (33.33%)
+built-ins/eval 2/9 (22.22%)
     length-non-configurable.js
-    name.js
     private-identifiers-not-empty.js {unsupported: [class-fields-private]}
 
 built-ins/Function 186/505 (36.83%)
@@ -674,19 +671,17 @@ built-ins/global 0/29 (0.0%)
 
 built-ins/Infinity 0/6 (0.0%)
 
-built-ins/isFinite 8/16 (50.0%)
+built-ins/isFinite 7/16 (43.75%)
     length.js
-    name.js
     toprimitive-call-abrupt.js
     toprimitive-get-abrupt.js
     toprimitive-not-callable-throws.js
     toprimitive-result-is-object-throws.js
     toprimitive-result-is-symbol-throws.js
     toprimitive-valid-result.js
 
-built-ins/isNaN 8/16 (50.0%)
+built-ins/isNaN 7/16 (43.75%)
     length.js
-    name.js
     toprimitive-call-abrupt.js
     toprimitive-get-abrupt.js
     toprimitive-not-callable-throws.js
@@ -901,13 +896,11 @@ built-ins/Object 127/3150 (4.03%)
     proto-from-ctor-realm.js {unsupported: [Reflect]}
     subclass-object-arg.js {unsupported: [Reflect.construct, Reflect, class]}
 
-built-ins/parseFloat 3/58 (5.17%)
-    name.js
+built-ins/parseFloat 2/58 (3.45%)
     S15.1.2.3_A2_T10_U180E.js {unsupported: [u180e]}
     S15.1.2.3_A7.2.js
 
-built-ins/parseInt 3/60 (5.0%)
-    name.js
+built-ins/parseInt 2/60 (3.33%)
     S15.1.2.2_A2_T10_U180E.js {unsupported: [u180e]}
     S15.1.2.2_A9.2.js