ufuzz failure

[alexlamsl]

// original code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

{
    var expr1 = (--b + (typeof f0 == "function" && --_calls_ >= 0 && f0(38..toString())) || a || 3).toString();
    L31360: for (var key1 in expr1) {
        c = 1 + c;
        var key1_1 = expr1[key1];
        L31361: {}
    }
}

{
    var brake3 = 5;
    while ((c = c + 1) + (a ^= (c = c + 1) + null) && --brake3 > 0) {
        L31362: {
            if (--b + ({
                [("b" % 25 < this + "b") << (4 === Infinity || ([ , 0 ].length === 2) * "")]: ++a,
                a: a >>>= a++ + ((a && (a.var += "" % -5 !== (23..toString() ^ NaN))) > (-3 && "number") << (false << -0)),
                0: 1 === 1 ? a : b,
                a: a,
                "\t": +((2 || 1) !== null * 0 || ("bar" === /[a2][^e]+$/) >>> ~-0)
            }[a && typeof a.async == "function" && --_calls_ >= 0 && a.async({
                static: a
            }.b, 4, --b + (a >>>= -(("bar" === 2 | "" < 38..toString()) == (c = c + 1, -3 - -2))))] ? typeof a == "function" && --_calls_ >= 0 && a(true, a++ + /[abc4]/.test(((c = c + 1) + delete (((null, 
            false) >>> false / "b") * ("number" << -5 && -4 == {})) || b || 5).toString()), "undefined") : {
                [typeof async_1 === "crap"]: {
                    value: a++ + "foo"
                }
            }[(c = c + 1) + (a && a[b >>>= a])])) {
                var expr6 = (--b + ({} in {
                    async: (c = c + 1) + (0 === 1 ? a : b)
                }) || 7).toString()[b >>>= a];
                L31363: for (a in expr6) {
                    {
                        var b_1 = function yield_1(foo_2, foo_1) {
                            function f0(a_2) {
                                c = 1 + c, 5 != -0 & -25 ^ false === 3 == (NaN, -3);
                                c = 1 + c, (foo_1 && (foo_1[(c = c + 1) + ((c = 1 + c, ~(a_2 && (a_2[-1 in {
                                    0: (c = 1 + c, (23..toString() > -0) << false + 23..toString() === (23..toString() >> 3 != (foo_2 && (foo_2[c = 1 + c, 
                                    ((foo_1 && (foo_1.get = true != 24..toString())) | undefined !== "object") === (true & 5 ^ (a_2 && (a_2[c = 1 + c, 
                                    (-4 === 5) > ("" > Infinity) >= (("number" ^ undefined) <= (a_2 += [ , 0 ][1] == 4))] >>>= [] & "number")))] = -5 - true))))
                                }] /= ("bar" >>> 38..toString()) - ({} << "undefined")))) ? (c = 1 + c, (4 << "") % (a_2 = -0 | 24..toString()) >> (foo_2 %= 3 >> "foo") + ("object" && 38..toString())) : (c = 1 + c, 
                                (-5 === -0, foo_1 && (foo_1[c = 1 + c, Infinity == -5 != (-2 ^ 25) ^ (foo_2 && (foo_2[c = 1 + c, 
                                (25 == -0) >> ([ , 0 ][1] === 5) >= "bar" / 38..toString() / ~38..toString()] = true >>> "a") || +"a")] = -1 != "c")) < (-4 != -3 === (c = c + 1, 
                                -5))))] = 38..toString() >> true << (-1 && null))) == (4 <= []) >>> 4 % 0;
                            }
                            var bar_1 = f0((c = 1 + c, ({} ^ /[a2][^e]+$/) >> (undefined < "function") == (bar_1 && (bar_1[(c = c + 1) + {
                                c: (c = 1 + c, !(2 << "bar") + -("bar", false)),
                                "\t": (c = 1 + c, ("object" * ([ , 0 ].length === 2) !== (bar_1 -= [] !== 0)) + ([ , 0 ][1] / 24..toString() ^ (bar_1 && (bar_1.async /= {} >> -2))))
                            }.value] = (foo_1 && (foo_1[c = 1 + c, ~(1 * 38..toString()) & null + -3 >= ("number" > null)] /= 0 / "object")) >= ~([ , 0 ].length === 2)))), 4, (c = 1 + c, 
                            (NaN && [ , 0 ].length === 2) != (false ^ 24..toString()) !== ([ , 0 ][1] == [ , 0 ][1] || "function" ^ -3)));
                            function f1(bar, foo_1_2) {
                                c = 1 + c, (foo_1_2 += (2 >> -3) % (null && [ , 0 ][1])) / (0 % "number" === [] % "");
                                c = 1 + c, (NaN >>> "bar" === (0 & "undefined")) << (-2 >> undefined <= (-5 || 5));
                            }
                            var b = f1([ , 0 ].length === 2);
                            function f2(a, await_1, foo_2) {
                                c = 1 + c, (/[a2][^e]+$/ ^ -5) > (foo_2 && (foo_2[c = 1 + c, -(2 >= 5) << ((a && (a.next *= "b" < false)) >>> ("c" == []))] = -3 == "undefined")), 
                                NaN % 1 ^ [ , 0 ][1] * -1;
                                c = 1 + c, NaN + 1 - false / undefined + ((-3 || -1) === +/[a2][^e]+$/);
                            }
                            var b_1 = f2();
                            function f3([ foo_2_1 ]) {
                            }
                            var arguments_1 = f3([ "b", -3, (c = 1 + c, -("bar" >= true) >> (("function" ^ "undefined") <= (38..toString() !== "function"))) ]);
                            function f4(let_2) {
                            }
                            var foo_1_2 = f4((c = 1 + c, (bar_1 && (bar_1.done = (c = c + 1, "number") !== ({} == "number"))) * ((c = c + 1, 
                            NaN) | false == 1)), (c = 1 + c, (this - {} ^ (c = c + 1, this)) > ("" >> "foo" ^ Infinity !== 1)));
                        }();
                    }
                }
            }
        }
    }
}

console.log(null, a, b, c, Infinity, NaN, undefined);

// uglified code
// (beautified)
var key1, _calls_ = 10, a = 100, b = 10, c = 0, expr1 = (--b + ("function" == typeof f0 && 0 <= --_calls_ && f0(38..toString())) || a || 3).toString();

for (key1 in expr1) {
    var c = 1 + c, key1_1 = expr1[key1];
}

for (var brake3 = 5; (c += 1) + (a ^= (c += 1) + null) && 0 < --brake3; ) {
    if (--b + ({
        [(NaN < this + "b") << "" * (2 === [ , 0 ].length)]: ++a,
        0: a,
        a: a >>>= a++ + (0 < (a && (a.var += 0 != (NaN ^ 23..toString())))),
        "\t": 1
    }[a && "function" == typeof a.async && 0 <= --_calls_ && a.async({
        static: a
    }.b, 4, --b + (a >>>= -((!1 | "" < 38..toString()) == (c += 1, -1))))] ? "function" == typeof a && 0 <= --_calls_ && a(!0, a++ + /[abc4]/.test(((c += 1) + !0 || b || 5).toString()), "undefined") : {
        ["crap" == typeof async_1]: {
            value: a++ + "foo"
        }
    }[(c += 1) + (a && a[b >>>= a])])) {
        var expr6 = (--b + ({} in {
            async: (c += 1) + b
        }) || 7).toString()[b >>>= a];
        for (a in expr6) {
            var b_1 = function(foo_2, foo_1) {
                var a_2, bar_1 = (c = 1 + c, a_2 = ({} ^ /[a2][^e]+$/) >> !1 == (bar_1 && (bar_1[(c += 1) + {
                    c: 0,
                    "\t": (c = 1 + (c = 1 + c), ("object" * (2 === [ , 0 ].length) != (bar_1 -= 0 !== [])) + (0 / 24..toString() ^ (bar_1 && (bar_1.async /= {} >> -2))))
                }.value] = (foo_1 && (foo_1[c = 1 + c, !1 & ~+38..toString()] /= NaN)) >= ~(2 === [ , 0 ].length))), 
                c = 1 + c, 24..toString(), c = 1 + (c = 1 + c), void (foo_1 && (foo_1[(c += 1) + (c = 1 + c, 
                ~(a_2 && (a_2[-1 in {
                    0: (c = 1 + c, (-0 < 23..toString()) << !1 + 23..toString() === (23..toString() >> 3 != (foo_2 && (foo_2[c = 1 + c, 
                    (!0 | (foo_1 && (foo_1.get = 1 != 24..toString()))) == (1 ^ (a_2 && (a_2[c = 1 + c, 
                    0 <= (a_2 += !1) <= !1] >>>= "number" & [])))] = -6))))
                }] /= ("bar" >>> 38..toString()) - ({} << "undefined"))) ? (c = 1 + c, 4 % (a_2 = -0 | 24..toString()) >> (foo_2 %= 3) + 38..toString()) : (c = 1 + c, 
                (foo_1 && (foo_1[c = 1 + c, !0 ^ (foo_2 ? foo_2[c = 1 + c, "bar" / 38..toString() / ~38..toString() <= 0] = 1 : NaN)] = !0)) < (!0 === (c += 1, 
                -5))))] = 38..toString() >> !0 << null)));
                c = 1 + (1 + c);
                !function(a, foo_2) {
                    c = 1 + c, foo_2 && (foo_2[c = 1 + c, -0 << ((a && (a.next *= !1)) >>> ("c" == []))] = !1), 
                    c = 1 + c;
                }();
                c = 1 + c, 38..toString();
                c = 1 + c, bar_1 && (bar_1.done = (c += 1, "number" !== ("number" == {}))), c = 1 + (c += 1), 
                c += 1;
            }();
        }
    }
}

console.log(null, a, b, c, 1 / 0, NaN, void 0);

original result:
null 14 2147483647 15 Infinity NaN undefined

uglified result:
null 15 1 15 Infinity NaN undefined

// reduced test case (output will differ)

// (beautified)
var a = 0;

({
    [0]: ++a,
    a: a >>>= 1,
    0: a,
    a: 0
})[0] ? 0 : a++;

console.log(a);
// output: 1
// 
// minify: 0
// 
// options: {
//   "mangle": false,
//   "output": {
//     "v8": true
//   },
//   "validate": true
// }

minify(options):
{
  "mangle": false,
  "output": {
    "v8": true
  }
}

Suspicious compress options:
  objects