642164 - JM: [infer failure] Missing type in object #4:0:Object x: float

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Christian Holler (:decoder)]

The following test case (run with -n -a -m) crashes on JM tip (tested on 64
bit):

function raisesException(exception) {
  return function (code) {
      eval(code);
  };
};
function obj() {
  var o = { assertEq: true, y: 1 };
  Object.defineProperty(o, 'x', { writable: false });
  return o;
}
function in_strict_with(expr) {
  return "with(obj()) { (function () { 'use strict'; " + expr + " })(); }";
}
assertEq(raisesException(TypeError)(in_strict_with('x++;')), true);

Comment 1

[Brian Hackett [Laid off!]]

Remove some cruft when handling arithmetic overflow on INCNAME/etc. that set the result of the increment before updating the type sets to reflect the new value.

http://hg.mozilla.org/projects/jaegermonkey/rev/84090709049e

Comment 2

[Christian Holler (:decoder)]

A testcase for this bug was automatically identified at js/src/jit-test/tests/basic/bug642164.js.