[proxies] Correctly handle proxies in Function.prototype.bind

test/mjsunit/harmony/proxies-bind.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-proxies --harmony-reflect
+
+// Tests the interaction of Function.prototype.bind with proxies.
+
+
+// (Helper)
+
+var log = [];
+var logger = {};
+var handler = new Proxy({}, logger);
+
+logger.get = function(t, trap, r) {
+  return function() {
+    log.push([trap, ...arguments]);
+    return Reflect[trap](...arguments);
+  }
+};
+
+
+// Simple case
+
+var target = function(a, b, c) { "use strict"; return this };
+var proxy = new Proxy(target, handler);
+var this_value = Symbol();
+
+log.length = 0;
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(2, result.length);
+assertEquals(target.__proto__, result.__proto__);
+assertEquals(this_value, result());
+assertEquals(5, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+assertEquals(["getPrototypeOf", target], log[0]);
+assertEquals(["getOwnPropertyDescriptor", target, "length"], log[1]);
+assertEquals(["get", target, "length", proxy], log[2]);
+assertEquals(["get", target, "name", proxy], log[3]);
+assertEquals(["apply", target, this_value, ["foo"]], log[4]);
+assertEquals(new target(), new result());
+
+
+// Custom prototype
+
+log.length = 0;
+target.__proto__ = {radio: "gaga"};
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(2, result.length);
+assertSame(target.__proto__, result.__proto__);
+assertEquals(this_value, result());
+assertEquals(5, log.length);
+for (var i in log) assertSame(target, log[i][1]);
+assertEquals(["getPrototypeOf", target], log[0]);
+assertEquals(["getOwnPropertyDescriptor", target, "length"], log[1]);
+assertEquals(["get", target, "length", proxy], log[2]);
+assertEquals(["get", target, "name", proxy], log[3]);
+assertEquals(["apply", target, this_value, ["foo"]], log[4]);
+
+
+// Custom length
+
+handler = {
+  get() {return 42},
+  getOwnPropertyDescriptor() {return {configurable: true}}
+};
+proxy = new Proxy(target, handler);
+
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(41, result.length);
+assertEquals(this_value, result());
+
+
+// Long length
+
+handler = {
+  get() {return Math.pow(2, 100)},
+  getOwnPropertyDescriptor() {return {configurable: true}}
+};
+proxy = new Proxy(target, handler);
+
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(Math.pow(2, 100) - 1, result.length);
+assertEquals(this_value, result());
+
+
+// Very long length
+
+handler = {
+  get() {return 1/0},
+  getOwnPropertyDescriptor() {return {configurable: true}}
+};
+proxy = new Proxy(target, handler);
+
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(1/0, result.length);
+assertEquals(this_value, result());
+
+
+// Non-integer length
+
+handler = {
+  get() {return 4.2},
+  getOwnPropertyDescriptor() {return {configurable: true}}
+};
+proxy = new Proxy(target, handler);
+
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(3, result.length);
+assertEquals(this_value, result());
+
+
+// Undefined length
+
+handler = {
+  get() {},
+  getOwnPropertyDescriptor() {return {configurable: true}}
+};
+proxy = new Proxy(target, handler);
+
+result = Function.prototype.bind.call(proxy, this_value, "foo");
+assertEquals(0, result.length);
+assertEquals(this_value, result());
+
+
+// Non-callable
+
+assertThrows(() => Function.prototype.bind.call(new Proxy({}, {})), TypeError);
+assertThrows(() => Function.prototype.bind.call(new Proxy([], {})), TypeError);
+
+
+// Non-constructable
+
+result = Function.prototype.bind.call(() => 42, this_value, "foo");
+assertEquals(42, result());
+assertThrows(() => new result());