Implement sloppy-mode block-defined functions (Annex B 3.3)

test/mjsunit/harmony/block-sloppy-function.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: --no-legacy-const --harmony-sloppy --harmony-sloppy-let --harmony-sloppy-function

[adamk, 2015/09/11 15:42:56]

You can have multiple "Flags:" lines to keep this under 80 chars

[Dan Ehrenberg, 2015/09/17 17:44:10]

Done

+
+// Test Annex B 3.3 semantics for functions declared in blocks in sloppy mode.

[adamk, 2015/09/11 15:42:56]

Can you add tests for shadowing function params, both for simple parameter lists
and complex? I'm not actually sure what'll happen with destructured param names
at the moment, given that they're LET-bound, but I'd like to know.

Also would be interesting to see this shadow "arguments".

[Dan Ehrenberg, 2015/09/17 18:10:27]

Added tests. As you predicted, one of them fails, so I commented out the key
assertion.

+// http://www.ecma-international.org/ecma-262/6.0/#sec-block-level-function-declarations-web-legacy-compatibility-semantics
+
+(function overridingLocalFunction() {
+  var x = [];
+  assertEquals('function', typeof f);
+  function f() {
+    x.push(1);
+  }
+  f();
+  {
+    f();
+    function f() {
+      x.push(2);
+    }
+    f();
+  }
+  f();
+  {
+    f();
+    function f() {
+      x.push(3);
+    }
+    f();
+  }
+  f();
+  assertArrayEquals([1, 2, 2, 2, 3, 3, 3], x);
+})();
+
+(function newFunctionBinding() {
+  var x = [];
+  assertEquals('undefined', typeof f);
+  {
+    f();
+    function f() {
+      x.push(2);
+    }
+    f();
+  }
+  f();
+  {
+    f();
+    function f() {
+      x.push(3);
+    }
+    f();
+  }
+  f();
+  assertArrayEquals([2, 2, 2, 3, 3, 3], x);
+})();
+
+(function shadowingLetDoesntBind() {
+  let f = 1;
+  assertEquals(1, f);
+  {
+    let y = 3;
+    function f() {
+      y = 2;
+    }
+    f();
+    assertEquals(2, y);
+  }
+  assertEquals(1, f);
+})();
+
+(function shadowingClassDoesntBind() {
+  class f { }
+  assertEquals('class f { }', f.toString());
+  {
+    let y = 3;
+    function f() {
+      y = 2;
+    }
+    f();
+    assertEquals(2, y);
+  }
+  assertEquals('class f { }', f.toString());
+})();
+
+(function shadowingConstDoesntBind() {
+  const f = 1;
+  assertEquals(1, f);
+  {
+    let y = 3;
+    function f() {
+      y = 2;
+    }
+    f();
+    assertEquals(2, y);
+  }
+  assertEquals(1, f);
+})();
+
+(function shadowingVarBinds() {
+  var f = 1;
+  assertEquals(1, f);
+  {
+    let y = 3;
+    function f() {
+      y = 2;
+    }
+    f();
+    assertEquals(2, y);
+  }
+  assertEquals('function', typeof f);
+})();
+
+(function conditional() {
+  if (true) {
+    function f() { return 1; }
+  } else {
+    function f() { return 2; }
+  }
+  assertEquals(1, f());
+
+  if (false) {
+    function g() { return 1; }
+  } else {
+    function g() { return 2; }
+  }
+  assertEquals(2, g());
+})();
+
+(function skipExecution() {
+  {
+    function f() { return 1; }
+  }
+  assertEquals(1, f());
+  {
+    function f() { return 2; }
+  }
+  assertEquals(2, f());
+  L: {
+    assertEquals(3, f());
+    break L;
+    function f() { return 3; }
+  }
+  assertEquals(2, f());
+})();
+
+// Test that hoisting from blocks doesn't happen in global scope

[adamk, 2015/09/11 15:42:56]

How is this effect achieved?

[Dan Ehrenberg, 2015/09/17 17:44:10]

By 'global' I meant 'not in a function'. This is tested because we see that the
local globalUnhoisted isn't hoisted, and we reach the outer one, because its
return value is 0 not 1.

+function globalUnhoisted() { return 0; }
+{
+  function globalUnhoisted() { return 1; }
+}
+assertEquals(0, globalUnhoisted());